WorldWideScience

Sample records for identifying fouling events

  1. Identifying jet quantum numbers event by event

    International Nuclear Information System (INIS)

    Teper, M.J.

    1979-12-01

    A method is proposed to identify the parton that gives rise to any particular jet. The method improves with the number of particles in the jet, and should indicate which of the jets in a three jet event at PETRA is the gluon jet. (author)

  2. Use of genetic algorithm to identify thermophysical properties of deposited fouling in heat exchanger tubes

    International Nuclear Information System (INIS)

    Adili, Ali; Ben Salah, Mohieddine; Kerkeni, Chekib; Ben Nasrallah, Sassi

    2009-01-01

    At high temperature, the circulation of fluid in heat exchangers provides a tendency for fouling accumulation to take place on the internal surface of tubes. This paper shows an experimental process of thermophysical properties estimation of the fouling deposited on internal surface of a heat exchanger tube using genetic algorithms (GAs). The genetic algorithm is used to minimize an objective function containing calculated and measured temperatures. The experimental bench using a photothermal method with a finite width pulse heat excitation is used and the estimated parameters are obtained with high accuracy

  3. Identifying optimal cleaning cycles for heat exchangers subject to fouling and ageing

    International Nuclear Information System (INIS)

    Pogiatzis, Thomas; Ishiyama, Edward M.; Paterson, William R.; Vassiliadis, Vassilios S.; Wilson, D. Ian

    2012-01-01

    Fouling of heat exchangers causes reduced heat transfer and other penalties. Regular cleaning represents one widely used fouling mitigation strategy, where the schedule of cleaning actions can be optimised to minimise the cost of fouling. This paper investigates, for the first time, the situation where there are two cleaning methods available so that the mode of cleaning has to be selected as well as the cleaning interval. Ageing is assumed to convert the initial deposit, labelled 'gel', into a harder and more conductive form, labelled 'coke', which cannot be removed by one of the cleaning methods. The second method can remove both the gel layer and the coke layer, but costs more and requires the unit to be off-line longer for cleaning. Experimental data demonstrating the effects of ageing are presented. The industrial application is the comparison of cleaning-in-place methods with off-line mechanical cleaning. A process model is constructed for an isolated counter-current heat exchanger subject to fouling, where ageing is described by a simple two-layer model. Solutions generated by an NLP-based approach prove to be superior to a simpler heuristic. A series of case studies demonstrate that combinations of chemical and mechanical cleaning can be superior to mechanical cleaning alone for certain combinations of parameters.

  4. Identifying Adverse Drug Events by Relational Learning.

    Science.gov (United States)

    Page, David; Costa, Vítor Santos; Natarajan, Sriraam; Barnard, Aubrey; Peissig, Peggy; Caldwell, Michael

    2012-07-01

    The pharmaceutical industry, consumer protection groups, users of medications and government oversight agencies are all strongly interested in identifying adverse reactions to drugs. While a clinical trial of a drug may use only a thousand patients, once a drug is released on the market it may be taken by millions of patients. As a result, in many cases adverse drug events (ADEs) are observed in the broader population that were not identified during clinical trials. Therefore, there is a need for continued, post-marketing surveillance of drugs to identify previously-unanticipated ADEs. This paper casts this problem as a reverse machine learning task , related to relational subgroup discovery and provides an initial evaluation of this approach based on experiments with an actual EMR/EHR and known adverse drug events.

  5. Identifying Wind and Solar Ramping Events: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Florita, A.; Hodge, B. M.; Orwig, K.

    2013-01-01

    Wind and solar power are playing an increasing role in the electrical grid, but their inherent power variability can augment uncertainties in power system operations. One solution to help mitigate the impacts and provide more flexibility is enhanced wind and solar power forecasting; however, its relative utility is also uncertain. Within the variability of solar and wind power, repercussions from large ramping events are of primary concern. At the same time, there is no clear definition of what constitutes a ramping event, with various criteria used in different operational areas. Here the Swinging Door Algorithm, originally used for data compression in trend logging, is applied to identify variable generation ramping events from historic operational data. The identification of ramps in a simple and automated fashion is a critical task that feeds into a larger work of 1) defining novel metrics for wind and solar power forecasting that attempt to capture the true impact of forecast errors on system operations and economics, and 2) informing various power system models in a data-driven manner for superior exploratory simulation research. Both allow inference on sensitivities and meaningful correlations, as well as the ability to quantify the value of probabilistic approaches for future use in practice.

  6. Identifying Prominent Life Events on Twitter

    OpenAIRE

    Dickinson, Thomas; Fernández, Miriam; Thomas, Lisa A.; Mulholland, Paul; Briggs, Pam; Alani, Harith

    2015-01-01

    Social media is a common place for people to post and share digital reflections of their life events, including major events such as getting married, having children, graduating, etc. Although the creation of such posts is straightforward, the identification of events on online media remains a challenge. Much research in recent years focused on extracting major events from Twitter, such as earthquakes, storms, and floods. This paper however, targets the automatic detection of personal life ev...

  7. Text mining electronic health records to identify hospital adverse events

    DEFF Research Database (Denmark)

    Gerdes, Lars Ulrik; Hardahl, Christian

    2013-01-01

    Manual reviews of health records to identify possible adverse events are time consuming. We are developing a method based on natural language processing to quickly search electronic health records for common triggers and adverse events. Our results agree fairly well with those obtained using manu...

  8. Assessing quantitative EEG spectrograms to identify non-epileptic events.

    Science.gov (United States)

    Goenka, Ajay; Boro, Alexis; Yozawitz, Elissa

    2017-09-01

    To evaluate the sensitivity and specificity of quantitative EEG (QEEG) spectrograms in order to distinguish epileptic from non-epileptic events. Seventeen patients with paroxysmal non-epileptic events, captured during EEG monitoring, were retrospectively assessed using QEEG spectrograms. These patients were compared to a control group of 13 consecutive patients (ages 25-60 years) with epileptic seizures of similar semiology. Assessment of raw EEG was employed as the gold standard against which epileptic and non-epileptic events were validated. QEEG spectrograms, available using Persyst 12 EEG system integration software, were each assessed with respect to their usefulness to distinguish epileptic from non-epileptic seizures. The given spectrogram was interpreted as indicating a seizure if, at the time of the clinically identified event, it showed a visually significant change from baseline. Eighty-two clinically identified paroxysmal events were analysed (46 non-epileptic and 36 epileptic). The "seizure detector trend analysis" spectrogram correctly classified 33/46 (71%) non-epileptic events (no seizure indicated during a clinically identified event) vs. 29/36 (81%) epileptic seizures (seizure indicated during a clinically identified event) (p=0.013). Similarly, "rhythmicity spectrogram", FFT spectrogram, "asymmetry relative spectrogram", and integrated-amplitude EEG spectrogram detected 28/46 (61%), 30/46 (65%), 22/46 (48%) and 27/46 (59%) non-epileptic events vs. 27/36 (75%), 25/36 (69%), 25/36 (69%) and 27/36 (75%) epileptic events, respectively. High sensitivities and specificities for QEEG seizure detection analyses suggest that QEEG may have a role at the bedside to facilitate early differentiation between epileptic seizures and non-epileptic events in order to avoid unnecessary administration of antiepileptic drugs and possible iatrogenic consequences.

  9. Impact of organic fractions identified by SEC and fluorescence EEM on the hydraulic reversibility of ultrafiltration membrane fouling by secondary effluents

    KAUST Repository

    Haberkampa, Jens

    2011-05-01

    Loss of membrane filtration performance due to organic fouling is still a significant drawback for the application of low-pressure membranes in tertiary wastewater treatment. The present study investigates the relevance of different organic fractions present in secondary effluents in terms of hydraulically reversible and irreversible fouling of hollow-fibre ultrafiltration membranes. A good correlation between the hydraulically reversible filtration resistance and the total organic biopolymer concentration according to size exclusion chromatography (SEC) was observed. Qualitatively biopolymers consist mainly of polysaccharides as well as proteins with high molecular weight. Polysaccharides are retained by the membrane pores, but can be removed by simple UF backwashing. On the other hand, fluorescence excitation-emission matrix (EEM) analysis indicates that the extent of the hydraulically irreversible fouling correlates with the presence of protein-like substances. Removal of protein-like substances by biological slow sand filtration or chemical coagulation results in the significant reduction of the hydraulically irreversible fouling, which is presumably due to proteins in the molecular range of biopolymers. In contrast to the comparatively low sensitivity of colorimetric methods for the analysis of proteins and polysaccharides, the combined application of size exclusion chromatography and fluorescence EEM analysis is a promising tool for the determination of the organic fouling propensity of secondary effluents. ©2011 Desalination Publications. All rights reserved.

  10. Impact of organic fractions identified by SEC and fluorescence EEM on the hydraulic reversibility of ultrafiltration membrane fouling by secondary effluents

    KAUST Repository

    Haberkampa, Jens; Ernst, Mathias; Paar, Hendrik; Pallischeck, Daniela; Amy, Gary L.; Jekel, Martin R.

    2011-01-01

    Loss of membrane filtration performance due to organic fouling is still a significant drawback for the application of low-pressure membranes in tertiary wastewater treatment. The present study investigates the relevance of different organic fractions present in secondary effluents in terms of hydraulically reversible and irreversible fouling of hollow-fibre ultrafiltration membranes. A good correlation between the hydraulically reversible filtration resistance and the total organic biopolymer concentration according to size exclusion chromatography (SEC) was observed. Qualitatively biopolymers consist mainly of polysaccharides as well as proteins with high molecular weight. Polysaccharides are retained by the membrane pores, but can be removed by simple UF backwashing. On the other hand, fluorescence excitation-emission matrix (EEM) analysis indicates that the extent of the hydraulically irreversible fouling correlates with the presence of protein-like substances. Removal of protein-like substances by biological slow sand filtration or chemical coagulation results in the significant reduction of the hydraulically irreversible fouling, which is presumably due to proteins in the molecular range of biopolymers. In contrast to the comparatively low sensitivity of colorimetric methods for the analysis of proteins and polysaccharides, the combined application of size exclusion chromatography and fluorescence EEM analysis is a promising tool for the determination of the organic fouling propensity of secondary effluents. ©2011 Desalination Publications. All rights reserved.

  11. Effects of structural factors on upwelling fouling community, Southeast Brazil

    Directory of Open Access Journals (Sweden)

    Bruno Pereira Masi

    Full Text Available Abstract To assess the successional pattern of fouling organisms three hypotheses were tested: 1 a thermocline is caused by seasonal upwelling events, and therefore, depth influences the successional trajectory of the fouling community; 2 a reduction in the intensity of natural light of the substrate influences the fouling composition and the successional trajectory; 3 fish predation influences the community composition and its successional trajectory. During one year, up-facing and down-facing PVC panels on open, partially caged or fully caged, and placed at depths of 1.5 and 3.5 meters were monthly sampled by digital photograph to determine the community composition and by contact point to estimate the percent coverage of organisms. The upwelling impact provided different water masses, and light intensity was also a determining factor of the overall successional trajectory of the fouling community. After the installation of full and partial cages, differences were identified in the respective successional trajectories. The results of this study suggest that each physical factor or biological process can change the successional trajectory of the community, and the successional model (e.g., convergent, divergent, parallel, or cyclic depends on the magnitudes of the determinants that act on the community at each stage of its trajectory.

  12. How do stocking density and straw provision affect fouling in conventionally housed slaughter pigs?

    DEFF Research Database (Denmark)

    Larsen, Mona Lilian Vestbjerg; Bertelsen, Maja; Pedersen, Lene Juul

    2017-01-01

    with excreta and/or urine. Only the first event of fouling for each pen was included, and thus results represent whether a pen had a fouling event or not and when it happened. Data was analysed by using a Cox regression assuming proportional hazard and with right censoring of pens that never developed fouling...

  13. Identifying risk event in Indonesian fresh meat supply chain

    Science.gov (United States)

    Wahyuni, H. C.; Vanany, I.; Ciptomulyono, U.

    2018-04-01

    The aim of this paper is to identify risk issues in Indonesian fresh meat supply chain from the farm until to the “plate”. The critical points for food safety in physical fresh meat product flow are also identified. The paper employed one case study in the Indonesian fresh meat company by conducting observations and in-depth three stages of interviews. At the first interview, the players, process, and activities in the fresh meat industry were identified. In the second interview, critical points for food safety were recognized. The risk events in each player and process were identified in the last interview. The research will be conducted in three stages, but this article focuses on risk identification process (first stage) only. The second stage is measuring risk and the third stage focuses on determining the value of risk priority. The results showed that there were four players in the fresh meat supply chain: livestock (source), slaughter (make), distributor and retail (deliver). Each player has different activities and identified 16 risk events in the fresh meat supply chain. Some of the strategies that can be used to reduce the occurrence of such risks include improving the ability of laborers on food safety systems, improving cutting equipment and distribution processes

  14. Model track studies on fouled ballast using ground penetrating radar and multichannel analysis of surface wave

    Science.gov (United States)

    Anbazhagan, P.; Lijun, Su; Buddhima, Indraratna; Cholachat, Rujikiatkamjorn

    2011-08-01

    Ballast fouling is created by the breakdown of aggregates or outside contamination by coal dust from coal trains, or from soil intrusion beneath rail track. Due to ballast fouling, the conditions of rail track can be deteriorated considerably depending on the type of fouling material and the degree of fouling. So far there is no comprehensive guideline available to identify the critical degree of fouling for different types of fouling materials. This paper presents the identification of degree of fouling and types of fouling using non-destructive testing, namely seismic surface-wave and ground penetrating radar (GPR) survey. To understand this, a model rail track with different degree of fouling has been constructed in Civil engineering laboratory, University of Wollongong, Australia. Shear wave velocity obtained from seismic survey has been employed to identify the degree of fouling and types of fouling material. It is found that shear wave velocity of fouled ballast increases initially, reaches optimum fouling point (OFP), and decreases when the fouling increases. The degree of fouling corresponding after which the shear wave velocity of fouled ballast will be smaller than that of clean ballast is called the critical fouling point (CFP). Ground penetrating radar with four different ground coupled antennas (500 MHz, 800 MHz, 1.6 GHz and 2.3 GHz) was also used to identify the ballast fouling condition. It is found that the 800 MHz ground coupled antenna gives a better signal in assessing the ballast fouling condition. Seismic survey is relatively slow when compared to GPR survey however it gives quantifiable results. In contrast, GPR survey is faster and better in estimating the depth of fouling.

  15. Performance Analysis: Work Control Events Identified January - August 2010

    Energy Technology Data Exchange (ETDEWEB)

    De Grange, C E; Freeman, J W; Kerr, C E; Holman, G; Marsh, K; Beach, R

    2011-01-14

    This performance analysis evaluated 24 events that occurred at LLNL from January through August 2010. The analysis identified areas of potential work control process and/or implementation weaknesses and several common underlying causes. Human performance improvement and safety culture factors were part of the causal analysis of each event and were analyzed. The collective significance of all events in 2010, as measured by the occurrence reporting significance category and by the proportion of events that have been reported to the DOE ORPS under the ''management concerns'' reporting criteria, does not appear to have increased in 2010. The frequency of reporting in each of the significance categories has not changed in 2010 compared to the previous four years. There is no change indicating a trend in the significance category and there has been no increase in the proportion of occurrences reported in the higher significance category. Also, the frequency of events, 42 events reported through August 2010, is not greater than in previous years and is below the average of 63 occurrences per year at LLNL since 2006. Over the previous four years, an average of 43% of the LLNL's reported occurrences have been reported as either ''management concerns'' or ''near misses.'' In 2010, 29% of the occurrences have been reported as ''management concerns'' or ''near misses.'' This rate indicates that LLNL is now reporting fewer ''management concern'' and ''near miss'' occurrences compared to the previous four years. From 2008 to the present, LLNL senior management has undertaken a series of initiatives to strengthen the work planning and control system with the primary objective to improve worker safety. In 2008, the LLNL Deputy Director established the Work Control Integrated Project Team to develop the core requirements and graded

  16. Identifying events that impact self-efficacy in physics learning

    Directory of Open Access Journals (Sweden)

    Vashti Sawtelle

    2012-09-01

    Full Text Available We present a method of analyzing the development of self-efficacy in real time using a framework of self-efficacy opportunities (SEOs. Considerable research has shown a connection between self-efficacy, or the confidence in one’s own ability to perform a task, and success in science fields. Traditional methods of investigating the development of self-efficacy have required participants to recollect past events. This reliance on participant memory makes it difficult to understand what impact particular events may have on developing self-efficacy in the moment. We use video recordings of three undergraduate Modeling Instruction students solving a physics problem to characterize SEOs in a moment-by-moment analysis. We then validate these characterizations of the development of self-efficacy by reviewing the problem-solving session with the participants and find evidence that the SEOs identified are taken up and impact self-efficacy. This characterization and validation of SEOs in the moment represents a first step towards establishing a methodology for analyzing the development of self-efficacy in real time.

  17. Fouling in pressure retarded osmosis

    Energy Technology Data Exchange (ETDEWEB)

    Thelin, Willy

    2008-07-01

    A salinity power field laboratory was established at Sunndalsoera during the fall of 2002 in order to investigate the fouling potential in PRO in conditions prevailing in a typical sea water and a typically Norwegian surface water. The laboratory contained four identical units for long term testing of small samples of flat sheet membranes. The water flux, the differential pressures across the flow channels as well as the temperature in the membrane cell were logged to a computer. The logging data could be monitored from any remote location with access to the internet. Each unit was equipped with an automatically controlled system for membrane cleaning. Several series of osmotic flux experiments of three to eight months duration were executed while investigating the effect of various routines for membrane treatment, including disinfection, backflushing and chemical cleaning. Further, the potential of NOM fouling and CaCO{sub 3} scaling were investigated in more detail during a large number of laboratory experiments performed under controlled conditions at SINTEF Petroleum Research in Trondheim and Lappeenranta University of Technology in Lappeenranta, Finland. The cellulose acetate membrane used for most of the fouling experiments was characterized in order to determine the intrinsic transport parameters of the membrane. Further, the saturation index at the membrane skin with respect to CaCO{sub 3} was modelled both for real cases with typically Norwegian surface waters as well as for the scaling experiments performed with synthetic waters in the laboratory. Several of the membrane samples which were exposed to fouling conditions during the osmotic experiments were subjected to characterization by scanning electron microscopy (SEM), wave length dispersive spectroscopy (WDS), optical microscopy and fluorescence microscopy in order to identify and quantify the foulants that were deposited on the membranes during the experiments. Further, procedures for the estimation

  18. Early warning of diarrhea and pen fouling in growing pigs using sensor-based monitoring

    DEFF Research Database (Denmark)

    Jensen, D. B.; Toft, Nils; Kristensen, A. R.

    2016-01-01

    then identify specific pens in need of extra attention. Here we evaluate the value of monitoring live weight, feed usage, humidity, drinking behavior and pen temperature in relation to early warnings of diarrhea and pen fouling in slaughter pigs. Materials and methods: We used data collected in 16 pens (8...... double-pens) between November 2013 and December 2014 at a commercial Danish farm. During this time, three new batches were inserted. We monitored the mean live weight of the pigs per pen (weekly, only in 4 pens), feed usage per double-pen (daily), humidity per section (daily), temperature at two...... positions per pen (hourly), water flow per double-pen (liters/hour/pig) and drinking frequency per pen (activations/hour/pig). Staff registrations of diarrhea and pen fouling were the events of interest. The data were divided into a learning set (15 events) and a test set (18 events). The data were modeled...

  19. Optimal design of tests for heat exchanger fouling identification

    International Nuclear Information System (INIS)

    Palmer, Kyle A.; Hale, William T.; Such, Kyle D.; Shea, Brian R.; Bollas, George M.

    2016-01-01

    Highlights: • Built-in test design that optimizes the information extractable from the said test. • Method minimizes the covariance of a fault with system uncertainty. • Method applied for the identification and quantification of heat exchanger fouling. • Heat exchanger fouling is identifiable despite the uncertainty in inputs and states. - Graphical Abstract: - Abstract: Particulate fouling in plate fin heat exchangers of aircraft environmental control systems is a recurring issue in environments rich in foreign object debris. Heat exchanger fouling detection, in terms of quantification of its severity, is critical for aircraft maintenance scheduling and safe operation. In this work, we focus on methods for offline fouling detection during aircraft ground handling, where the allowable variability range of admissible inputs is wider. We explore methods of optimal experimental design to estimate heat exchanger inputs and input trajectories that maximize the identifiability of fouling. In particular, we present a methodology in which D-optimality is used as a criterion for statistically significant inference of heat exchanger fouling in uncertain environments. The optimal tests are designed on the basis of a heat exchanger model of the inherent mass, energy and momentum balances, validated against literature data. The model is then used to infer sensitivities of the heat exchanger outputs with respect to fouling metrics and maximize them by manipulating input trajectories; thus enhancing the accuracy in quantifying the fouling extent. The proposed methodology is evaluated with statistical indices of the confidence in estimating thermal fouling resistance at uncertain operating conditions, explored in a series of case studies.

  20. Identifying Preserved Storm Events on Beaches from Trenches and Cores

    Science.gov (United States)

    Wadman, H. M.; Gallagher, E. L.; McNinch, J.; Reniers, A.; Koktas, M.

    2014-12-01

    Recent research suggests that even small scale variations in grain size in the shallow stratigraphy of sandy beaches can significantly influence large-scale morphology change. However, few quantitative studies of variations in shallow stratigraphic layers, as differentiated by variations in mean grain size, have been conducted, in no small part due to the difficulty of collecting undisturbed sediment cores in the energetic lower beach and swash zone. Due to this lack of quantitative stratigraphic grain size data, most coastal morphology models assume that uniform grain sizes dominate sandy beaches, allowing for little to no temporal or spatial variations in grain size heterogeneity. In a first-order attempt to quantify small-scale, temporal and spatial variations in beach stratigraphy, thirty-five vibracores were collected at the USACE Field Research Facility (FRF), Duck, NC, in March-April of 2014 using the FRF's Coastal Research and Amphibious Buggy (CRAB). Vibracores were collected at set locations along a cross-shore profile from the toe of the dune to a water depth of ~1m in the surf zone. Vibracores were repeatedly collected from the same locations throughout a tidal cycle, as well as pre- and post a nor'easter event. In addition, two ~1.5m deep trenches were dug in the cross-shore and along-shore directions (each ~14m in length) after coring was completed to allow better interpretation of the stratigraphic sequences observed in the vibracores. The elevations of coherent stratigraphic layers, as revealed in vibracore-based fence diagrams and trench data, are used to relate specific observed stratigraphic sequences to individual storm events observed at the FRF. These data provide a first-order, quantitative examination of the small-scale temporal and spatial variability of shallow grain size along an open, sandy coastline. The data will be used to refine morphological model predictions to include variations in grain size and associated shallow stratigraphy.

  1. Identifying and Synchronizing Health Information Technology (HIT) Events from FDA Medical Device Reports.

    Science.gov (United States)

    Kang, Hong; Wang, Frank; Zhou, Sicheng; Miao, Qi; Gong, Yang

    2017-01-01

    Health information technology (HIT) events, a subtype of patient safety events, pose a major threat and barrier toward a safer healthcare system. It is crucial to gain a better understanding of the nature of the errors and adverse events caused by current HIT systems. The scarcity of HIT event-exclusive databases and event reporting systems indicates the challenge of identifying the HIT events from existing resources. FDA Manufacturer and User Facility Device Experience (MAUDE) database is a potential resource for HIT events. However, the low proportion and the rapid evolvement of HIT-related events present challenges for distinguishing them from other equipment failures and hazards. We proposed a strategy to identify and synchronize HIT events from MAUDE by using a filter based on structured features and classifiers based on unstructured features. The strategy will help us develop and grow an HIT event-exclusive database, keeping pace with updates to MAUDE toward shared learning.

  2. Seasonal variations in fouling diatom communities on the Yantai coast

    Science.gov (United States)

    Yang, Cuiyun; Wang, Jianhua; Yu, Yang; Liu, Sujing; Xia, Chuanhai

    2015-03-01

    Fouling diatoms are a main component of biofilm, and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater, on the Yantai coast, northern Yellow Sea, China, using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3, 7, 14, and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca, Nitzschia, Navicula, Amphora, Gomphonema, and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions, we found that Cylindrotheca grew very fast, which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.

  3. Milk fouling in heat exchangers

    NARCIS (Netherlands)

    Jeurnink, T.J.M.

    1996-01-01


    The mechanisms of fouling of heat exchangers by milk were studied. Two major fouling mechanisms were indentified during the heat treatment of milk: (i) the formation and the subsequent deposition of activated serum protein molecules as a result of the heat denaturation; (ii) the

  4. Master Logic Diagram: An Approach to Identify Initiating Events of HTGRs

    Science.gov (United States)

    Purba, J. H.

    2018-02-01

    Initiating events of a nuclear power plant being evaluated need to be firstly identified prior to applying probabilistic safety assessment on that plant. Various types of master logic diagrams (MLDs) have been proposedforsearching initiating events of the next generation of nuclear power plants, which have limited data and operating experiences. Those MLDs are different in the number of steps or levels and different in the basis for developing them. This study proposed another type of MLD approach to find high temperature gas cooled reactor (HTGR) initiating events. It consists of five functional steps starting from the top event representing the final objective of the safety functions to the basic event representing the goal of the MLD development, which is an initiating event. The application of the proposed approach to search for two HTGR initiating events, i.e. power turbine generator trip and loss of offsite power, is provided. The results confirmed that the proposed MLD is feasiblefor finding HTGR initiating events.

  5. WANO Activities Related to Identifying and Reducing the Likelihood for Recurring Events

    International Nuclear Information System (INIS)

    Llewellyn, Michael

    2003-01-01

    Since its inception, WANO has encouraged members to share operating experience and events information through the WANO Operating Experience Programme. Preventing recurring events is a prime reason for sharing events information. Over 2500 events have been shared through WANO since 1989. However, a review of WANO activities in 1997 identified that this information was not being used very well by WANO members, and that WANO was not adding much 'value' to the events sharing process. At the time, WANO only provided the 'postal exchange' function for events sharing, and was not reviewing events across WANO to help members focus on the really important issues. Often, these very important issues involve recurring events. As a result of the 1997 review of the WANO operating experience process, WANO re-sourced and developed new analysis capabilities and began producing new types of reports for its members. The resource commitment includes four seconded engineers (one from each WANO Regional Centre) brought to Paris to staff a WANO Operating Experience Central Team. This team analyses events across WANO, writes WANO event reports, provides operating experience-related training, and provides technical support to members to improve their use of operating experience information. One focus area for events analysis by WANO is the identification and subsequent industry notification of recurring events. As a result of the 1997 review of WANO activities, in 1998 WANO began production of several new types of event-based reports to communicate significant industry events to our members. A key focus of analysis of these significant events is whether they are recurring events (that is, very similar to previous events either at that NPP or another NPP in the industry). The reports are called Significant Operating Experience Reports (SOERs) and Significant Event Reports (SERs). Significant Operating Experience Reports (SOERs) are written by WANO when several event reports indicate that

  6. Contribution of effluent organic matter (EfOM) to ultrafiltration (UF) membrane fouling: Isolation, characterization, and fouling effect of EfOM fractions

    KAUST Repository

    Zheng, Xing

    2014-11-01

    EfOM has been regarded as a major organic foulant resulting in UF membrane fouling in wastewater reclamation. To investigate fouling potential of different EfOM fractions, the present study isolated EfOM into hydrophobic neutrals (HPO-N), colloids, hydrophobic acids (HPO-A), transphilic neutrals and acids (TPI), and hydrophilics (HPI), and tested their fouling effect in both salt solution and pure water during ultrafiltration (UF). Major functional groups and chemical structure of the isolates were identified using Fourier transform infrared spectroscopy (FT-IR) and solid-state carbon nuclear magnetic resonance (13C NMR) analysis. The influence of the isolation process on the properties of EfOM fractions was minor because the raw and reconstituted secondary effluents were found similar with respect to UV absorbance, molecular size distribution, and fluorescence character. In membrane filtration tests, unified membrane fouling index (UMFI) and hydraulic resistance were used to quantify irreversible fouling potential of different water samples. Results show that under similar DOC level in feed water, colloids present much more irreversible fouling than other fractions. The fouling effect of the isolates is related to their size, chemical properties, and solution chemistry. Further investigations have identified that the interaction between colloids and other fractions also influences the performance of colloids in fouling phenomena. © 2014 Elsevier Ltd.

  7. Modeling of crude oil fouling in preheat exchangers of refinery distillation units

    Energy Technology Data Exchange (ETDEWEB)

    Jafari Nasr, Mohammad Reza; Majidi Givi, Mehdi [National Petrochemical Research and Technology Company (NPC-RT), P.O. Box 14385, Tehran (Iran)

    2006-10-15

    The aim of this paper is to propose a new model for crude oil fouling in preheat exchangers of crude distillation units. The experimental results of Australian light crude oil with the tube side surface temperature between 200 and 260{sup o}C and fluid velocity ranged 0.25-0.4m/s were used [Z. Saleh, R. Sheikholeslami, A.P. Watkinson, Heat exchanger fouling by a light australian crude oil, in: Heat Exchanger Fouling and Cleaning Fundamentals and Applications, Santa Fe, 2003]. The amount of activation energy depends on the surface temperature has been calculated. A new model including a term for fouling formation and a term for fouling removal due to chemical and tube wall shear stress was proposed, respectively. The main superiority of the model are independent to Pr number, thermal fouling removal and determination of {beta} based on experimental tests. Finally using the proposed model the fouling rate of Australian light crude oil has been calculated and the threshold curves to identify fouling and no fouling formation zones have been drawn. (author)

  8. Membrane Bioreactor (MBR Technology for Wastewater Treatment and Reclamation: Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Oliver Terna Iorhemen

    2016-06-01

    Full Text Available The membrane bioreactor (MBR has emerged as an efficient compact technology for municipal and industrial wastewater treatment. The major drawback impeding wider application of MBRs is membrane fouling, which significantly reduces membrane performance and lifespan, resulting in a significant increase in maintenance and operating costs. Finding sustainable membrane fouling mitigation strategies in MBRs has been one of the main concerns over the last two decades. This paper provides an overview of membrane fouling and studies conducted to identify mitigating strategies for fouling in MBRs. Classes of foulants, including biofoulants, organic foulants and inorganic foulants, as well as factors influencing membrane fouling are outlined. Recent research attempts on fouling control, including addition of coagulants and adsorbents, combination of aerobic granulation with MBRs, introduction of granular materials with air scouring in the MBR tank, and quorum quenching are presented. The addition of coagulants and adsorbents shows a significant membrane fouling reduction, but further research is needed to establish optimum dosages of the various coagulants/adsorbents. Similarly, the integration of aerobic granulation with MBRs, which targets biofoulants and organic foulants, shows outstanding filtration performance and a significant reduction in fouling rate, as well as excellent nutrients removal. However, further research is needed on the enhancement of long-term granule integrity. Quorum quenching also offers a strong potential for fouling control, but pilot-scale testing is required to explore the feasibility of full-scale application.

  9. Membrane Bioreactor (MBR) Technology for Wastewater Treatment and Reclamation: Membrane Fouling.

    Science.gov (United States)

    Iorhemen, Oliver Terna; Hamza, Rania Ahmed; Tay, Joo Hwa

    2016-06-15

    The membrane bioreactor (MBR) has emerged as an efficient compact technology for municipal and industrial wastewater treatment. The major drawback impeding wider application of MBRs is membrane fouling, which significantly reduces membrane performance and lifespan, resulting in a significant increase in maintenance and operating costs. Finding sustainable membrane fouling mitigation strategies in MBRs has been one of the main concerns over the last two decades. This paper provides an overview of membrane fouling and studies conducted to identify mitigating strategies for fouling in MBRs. Classes of foulants, including biofoulants, organic foulants and inorganic foulants, as well as factors influencing membrane fouling are outlined. Recent research attempts on fouling control, including addition of coagulants and adsorbents, combination of aerobic granulation with MBRs, introduction of granular materials with air scouring in the MBR tank, and quorum quenching are presented. The addition of coagulants and adsorbents shows a significant membrane fouling reduction, but further research is needed to establish optimum dosages of the various coagulants/adsorbents. Similarly, the integration of aerobic granulation with MBRs, which targets biofoulants and organic foulants, shows outstanding filtration performance and a significant reduction in fouling rate, as well as excellent nutrients removal. However, further research is needed on the enhancement of long-term granule integrity. Quorum quenching also offers a strong potential for fouling control, but pilot-scale testing is required to explore the feasibility of full-scale application.

  10. Workshop on an Assessment of Gas-Side Fouling in Fossil Fuel Exhaust Environments

    Science.gov (United States)

    Marner, W. J. (Editor); Webb, R. L. (Editor)

    1982-01-01

    The state of the art of gas side fouling in fossil fuel exhaust environments was assessed. Heat recovery applications were emphasized. The deleterious effects of gas side fouling including increased energy consumption, increased material losses, and loss of production were identified.

  11. Using Active Learning to Identify Health Information Technology Related Patient Safety Events.

    Science.gov (United States)

    Fong, Allan; Howe, Jessica L; Adams, Katharine T; Ratwani, Raj M

    2017-01-18

    The widespread adoption of health information technology (HIT) has led to new patient safety hazards that are often difficult to identify. Patient safety event reports, which are self-reported descriptions of safety hazards, provide one view of potential HIT-related safety events. However, identifying HIT-related reports can be challenging as they are often categorized under other more predominate clinical categories. This challenge of identifying HIT-related reports is exacerbated by the increasing number and complexity of reports which pose challenges to human annotators that must manually review reports. In this paper, we apply active learning techniques to support classification of patient safety event reports as HIT-related. We evaluated different strategies and demonstrated a 30% increase in average precision of a confirmatory sampling strategy over a baseline no active learning approach after 10 learning iterations.

  12. A new index for identifying different types of El Niño Modoki events

    Science.gov (United States)

    Wang, Xin; Tan, Wei; Wang, Chunzai

    2018-04-01

    El Niño Modoki events can be further classified into El Niño Modoki I and II in terms of their opposite impacts on southern China rainfall (Wang and Wang, J Clim 26:1322-1338, 2013) and the Indian Ocean dipole mode (Wang and Wang, Clim Dyn 42:991-1005, 2014). The present paper develops an index to identify the types of El Niño events. The El Niño Modoki II (MII) index is defined as the leading principle component of multivariate empirical orthogonal function analysis of the normalized El Niño Modoki index, Niño4 index and 850 hPa relative vorticity anomalies averaged near the Philippine Sea during autumn. The MII index exhibits dominant variations on interannual (2-3 and 4-5 years) and decadal (10-20 years) timescales. El Niño Modoki II events can be well identified by using the MII index value being larger than 1 standard deviation. Further analyses and numerical model experiments confirm that the MII index can portray the major oceanic and atmospheric features of El Niño Modoki II events. The constructed MII index along with previous ENSO indices can be used for classifying and identifying all types of El Niño events. Because of distinct impacts induced by different types of El Niño events, the implication of the present study is that climate prediction and future climate projection under global warming can be improved by using the MII index and other indices to identify the types of El Niño events.

  13. 49 CFR 214.323 - Foul time.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Foul time. 214.323 Section 214.323 Transportation... TRANSPORTATION RAILROAD WORKPLACE SAFETY Roadway Worker Protection § 214.323 Foul time. Working limits established on controlled track through the use of foul time procedures shall comply with the following...

  14. Contribution of different effluent organic matter fractions to membrane fouling in ultrafiltration of treated domestic wastewater

    KAUST Repository

    Zheng, Xing; Croue, Jean-Philippe

    2012-01-01

    In the present work, effluent organic matter (EfOM) in treated domestic wastewater was separated into hydrophobic neutrals, colloids, hydrophobic acids, transphilic acids and neutrals and hydrophilic compounds. Their contribution to dissolved organic carbon (DOC) was identified. Further characterization was conducted with respect to molecular size and hydrophobicity. Each isolated fraction was dosed into salt solution to identify its fouling potential in ultrafiltration (UF) using a hydrophilized polyethersulfone membrane. The results show that each kind of EfOM leads to irreversible fouling. At similar delivered DOC load to the membrane, colloids present the highest fouling effect in terms of both reversible and irreversible fouling. The hydrophobic organics show much lower reversibility than the biopolymers present. However, as they are of much smaller size than the membrane pore opening, they cannot lead to such severe fouling as biopolymers do. In all of the isolated fractions, hydrophilics show the lowest fouling potential. For either colloids or hydrophobic substances, increasing their content in feedwater leads to worse fouling. The co-effect between biopolymers and other EfOM fractions has also been identified as one of the mechanisms contributing to UF fouling in filtering EfOM-containing waters. © IWA Publishing 2012.

  15. Contribution of different effluent organic matter fractions to membrane fouling in ultrafiltration of treated domestic wastewater

    KAUST Repository

    Zheng, Xing

    2012-12-01

    In the present work, effluent organic matter (EfOM) in treated domestic wastewater was separated into hydrophobic neutrals, colloids, hydrophobic acids, transphilic acids and neutrals and hydrophilic compounds. Their contribution to dissolved organic carbon (DOC) was identified. Further characterization was conducted with respect to molecular size and hydrophobicity. Each isolated fraction was dosed into salt solution to identify its fouling potential in ultrafiltration (UF) using a hydrophilized polyethersulfone membrane. The results show that each kind of EfOM leads to irreversible fouling. At similar delivered DOC load to the membrane, colloids present the highest fouling effect in terms of both reversible and irreversible fouling. The hydrophobic organics show much lower reversibility than the biopolymers present. However, as they are of much smaller size than the membrane pore opening, they cannot lead to such severe fouling as biopolymers do. In all of the isolated fractions, hydrophilics show the lowest fouling potential. For either colloids or hydrophobic substances, increasing their content in feedwater leads to worse fouling. The co-effect between biopolymers and other EfOM fractions has also been identified as one of the mechanisms contributing to UF fouling in filtering EfOM-containing waters. © IWA Publishing 2012.

  16. Analyzing and Identifying Teens' Stressful Periods and Stressor Events From a Microblog.

    Science.gov (United States)

    Li, Qi; Xue, Yuanyuan; Zhao, Liang; Jia, Jia; Feng, Ling

    2017-09-01

    Increased health problems among adolescents caused by psychological stress have aroused worldwide attention. Long-standing stress without targeted assistance and guidance negatively impacts the healthy growth of adolescents, threatening the future development of our society. So far, research focused on detecting adolescent psychological stress revealed from each individual post on microblogs. However, beyond stressful moments, identifying teens' stressful periods and stressor events that trigger each stressful period is more desirable to understand the stress from appearance to essence. In this paper, we define the problem of identifying teens' stressful periods and stressor events from the open social media microblog. Starting from a case study of adolescents' posting behaviors during stressful school events, we build a Poisson-based probability model for the correlation between stressor events and stressful posting behaviors through a series of posts on Tencent Weibo (referred to as the microblog throughout the paper). With the model, we discover teens' maximal stressful periods and further extract details of possible stressor events that cause the stressful periods. We generalize and present the extracted stressor events in a hierarchy based on common stress dimensions and event types. Taking 122 scheduled stressful study-related events in a high school as the ground truth, we test the approach on 124 students' posts from January 1, 2012 to February 1, 2015 and obtain some promising experimental results: (stressful periods: recall 0.761, precision 0.737, and F 1 -measure 0.734) and (top-3 stressor events: recall 0.763, precision 0.756, and F 1 -measure 0.759). The most prominent stressor events extracted are in the self-cognition domain, followed by the school life domain. This conforms to the adolescent psychological investigation result that problems in school life usually accompanied with teens' inner cognition problems. Compared with the state-of-the-art top

  17. Engineering factors influencing Corbicula fouling in nuclear-service water systems

    International Nuclear Information System (INIS)

    Henager, C.H.; Johnson, K.I.; Page, T.L.

    1983-06-01

    Corbicula fouling is a continuing problem in nuclear-service water systems. More knowledge of biological and engineering factors is needed to develop effective detection and control methods. A data base on Corbicula fouling was compiled from nuclear and non-nuclear power stations and industries using raw water. This data base was used in an analysis to identify systems and components which are conducive to fouling by Corbicula. Bounds on several engineering parameters such as velocity and temperature which support Corbicula growth are given. Service water systems found in BWR and PWR reactors are listed and those that show fouling are identified. Possible safety implications of Corbicula fouling are discussed for specific service water systems. Several effective control methods in current use include backflushing with heated water, centrifugal strainers, and continuous chlorination during spawning seasons

  18. Utilization of Satellite Data to Identify and Monitor Changes in Frequency of Meteorological Events

    Science.gov (United States)

    Mast, J. C.; Dessler, A. E.

    2017-12-01

    Increases in temperature and climate variability due to human-induced climate change is increasing the frequency and magnitude of extreme heat events (i.e., heatwaves). This will have a detrimental impact on the health of human populations and habitability of certain land locations. Here we seek to utilize satellite data records to identify and monitor extreme heat events. We analyze satellite data sets (MODIS and AIRS land surface temperatures (LST) and water vapor profiles (WV)) due to their global coverage and stable calibration. Heat waves are identified based on the frequency of maximum daily temperatures above a threshold, determined as follows. Land surface temperatures are gridded into uniform latitude/longitude bins. Maximum daily temperatures per bin are determined and probability density functions (PDF) of these maxima are constructed monthly and seasonally. For each bin, a threshold is calculated at the 95th percentile of the PDF of maximum temperatures. Per each bin, an extreme heat event is defined based on the frequency of monthly and seasonal days exceeding the threshold. To account for the decreased ability of the human body to thermoregulate with increasing moisture, and to assess lethality of the heat events, we determine the wet-bulb temperature at the locations of extreme heat events. Preliminary results will be presented.

  19. Patient-identified events implicated in the development of body dysmorphic disorder.

    Science.gov (United States)

    Weingarden, Hilary; Curley, Erin E; Renshaw, Keith D; Wilhelm, Sabine

    2017-06-01

    Little is known about the causes of body dysmorphic disorder (BDD), but researchers have proposed a diathesis-stress model. This study uses a patient-centered approach to identify stressful events to which patients attribute the development of their BDD symptoms. An Internet-recruited sample of 165 adults with BDD participated. A large minority of participants attributed the development of their BDD to a triggering event. Bullying experiences were the most commonly described type of event. Additionally, most events were interpersonal and occurred during grade school or middle school. There were no differences in severity of psychosocial outcomes between participants who did or did not attribute their BDD to a specific triggering event. However, participants who specifically attributed their BDD development to a bullying experience had poorer psychosocial outcomes (i.e., perceived social support, depression severity, functional impairment, quality of life) compared to those who attributed their BDD development to another type of triggering event. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Asphaltene Aggregation and Fouling Behavior

    Science.gov (United States)

    Derakhshesh, Marzie

    This thesis explored the properties of asphaltene nano-aggregates in crude oil and toluene based solutions and fouling at process furnace temperatures, and the links between these two phenomena. The link between stability of asphaltenes at ambient conditions and fouling at the conditions of a delayed coker furnace, at over 450 °C, was examined by blending crude oil with an aliphatic diluent in different ratios. The stability of the blends were measured using a S-value analyzer, then fouling rates were measured on electrically heated stainless steel 316 wires in an autoclave reactor. The less stable the blend, the greater the rate and extent of fouling. The most severe fouling occurred with the unstable asphaltenes. SEM imaging of the foulant illustrates very different textures, with the structure becoming more porous with lower stability. Under cross-polarized light, the coke shows the presence of mesophase in the foulant layer. These data suggest a correlation between the fouling rate at high temperature furnace conditions and the stability index of the crude oil. Three organic polysulfides were introduced to the crude oil to examine their effect on fouling. The polysulfides are able to reduce coking and carbon monoxide generation in steam crackers. The fouling results demonstrated that polysulfide with more sulfur content increased the amount of corrosion-fouling of the wire. Various additives, solvents, ultrasound, and heat were employed to attempt to completely disaggregate the asphaltene nano-aggregates in solution at room temperature. The primary analytical technique used to monitor the nano-aggregation state of the asphaltenes in solution was the UV-visible spectroscopy. The results indicate that stronger solvents, such as pyridine and quinoline, combined with ionic liquids yield a slight reduction in the apparent absorbance at longer wavelengths, indicative of a decrease in the nano-aggregate size although the magnitude of the decrease is not significant

  1. Why conventional detection methods fail in identifying the existence of contamination events.

    Science.gov (United States)

    Liu, Shuming; Li, Ruonan; Smith, Kate; Che, Han

    2016-04-15

    Early warning systems are widely used to safeguard water security, but their effectiveness has raised many questions. To understand why conventional detection methods fail to identify contamination events, this study evaluates the performance of three contamination detection methods using data from a real contamination accident and two artificial datasets constructed using a widely applied contamination data construction approach. Results show that the Pearson correlation Euclidean distance (PE) based detection method performs better for real contamination incidents, while the Euclidean distance method (MED) and linear prediction filter (LPF) method are more suitable for detecting sudden spike-like variation. This analysis revealed why the conventional MED and LPF methods failed to identify existence of contamination events. The analysis also revealed that the widely used contamination data construction approach is misleading. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Tuning and Test of Fragmentation Models Based on Identified Particles and Precision Event Shape Data

    CERN Document Server

    Abreu, P; Adye, T; Ajinenko, I; Alekseev, G D; Alemany, R; Allport, P P; Almehed, S; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barate, R; Barbi, M S; Bardin, Dimitri Yuri; Baroncelli, A; Bärring, O; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Belous, K S; Benvenuti, Alberto C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bloch, D; Blume, M; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenke, T; Brenner, R A; Bricman, C; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Buys, A; Cabrera, S; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chen, M; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cindro, V; Collins, P; Contreras, J L; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahl-Jensen, Erik; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Dauncey, P D; Davenport, Martyn; Da Silva, W; Defoix, C; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Dijkstra, H; Di Ciaccio, Lucia; Di Diodato, A; Djama, F; Dolbeau, J; Dönszelmann, M; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Durand, J D; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Ferrer, A; Fichet, S; Filippas-Tassos, A; Firestone, A; Fischer, P A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Graziani, E; Green, C; Grefrath, A; Gris, P; Grosdidier, G; Grzelak, K; Gumenyuk, S A; Gunnarsson, P; Günther, M; Guy, J; Hahn, F; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kapusta, F; Karafasoulis, K; Karlsson, M; Karvelas, E; Katsanevas, S; Katsoufis, E C; Keränen, R; Khokhlov, Yu A; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klapp, O; Klein, H; Klovning, A; Kluit, P M; Köne, B; Kokkinias, P; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Libby, J; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; López, J M; Loukas, D; Lutz, P; Lyons, L; Naughton, J M; Maehlum, G; Mahon, J R; Maio, A; Malmgren, T G M; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Masik, J; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Merk, M; Meroni, C; Meyer, S; Meyer, W T; Myagkov, A; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Mulders, M; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Pain, R; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernegger, H; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Petrovykh, M; Phillips, H T; Piana, G; Pierre, F; Plaszczynski, S; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Rosso, E; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Rybicki, K; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sahr, O; Sajot, G; Salt, J; Sánchez, J; Sannino, M; Schimmelpfennig, M; Schneider, H; Schwickerath, U; Schyns, M A E; Sciolla, G; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Serbelloni, L; Shellard, R C; Siegrist, P; Silvestre, R; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sokolov, A; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stanescu, C; Stapnes, Steinar; Stavitski, I; Stevenson, K; Stichelbaut, F; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Thomas, J; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Todorova, S; Toet, D Z; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Trischuk, W; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; van Apeldoorn, G W; van Dam, P; Van Eldik, J; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Waldner, F; Weierstall, M; Weilhammer, Peter; Weiser, C; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Woschnagg, K; Yip, K; Yushchenko, O P; Zach, F; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zucchelli, G C; Zumerle, G

    1996-01-01

    Event shape and charged particle inclusive distributions are measured using 750000 decays of the $Z$ to hadrons from the DELPHI detector at LEP. These precise data allow a decisive confrontation with models of the hadronization process. Improved tunings of the JETSET ARIADNE and HERWIG parton shower models and the JETSET matrix element model are obtained by fitting the models to these DELPHI data as well as to identified particle distributions from all LEP experiments. The description of the data distributions by the models is critically reviewed with special importance attributed to identified particles.

  3. Fouling control in biomass boilers

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, Luis M.; Gareta, Raquel [Centro de Investigacion de Recursos y Consumos Energeticos (CIRCE), Universidad de Zaragoza, Centro Politecnico Superior, Maria de Luna, 3, 50018 Zaragoza (Spain)

    2009-05-15

    One of the important challenges for biomass combustion in industrial applications is the fouling tendency and how it affects to the boiler performance. The classical approach for this question is to activate sootblowing cycles with different strategies to clean the boiler (one per shift, one each six hours..). Nevertheless, it has been often reported no effect on boiler fouling or an excessive steam consumption for sootblowing. This paper illustrates the methodology and the application to select the adequate time for activating sootblowing in an industrial biomass boiler. The outcome is a control strategy developed with artificial intelligence (Neural Network and Fuzzy Logic Expert System) for optimizing the biomass boiler cleaning and maximizing heat transfer along the time. Results from an optimize sootblowing schedule show savings up to 12 GWh/year in the case-study biomass boiler. Extra steam generation produces an average increase of turbine power output of 3.5%. (author)

  4. Cleaning protocol for a FO membrane fouled in wastewater reuse

    KAUST Repository

    Valladares Linares, Rodrigo

    2013-05-30

    Forward osmosis (FO) is an emerging technology which can be applied in water reuse applications. Osmosis is a natural process that involves less energy consumption than reverse osmosis (RO), and therefore can be applied as a dilution process before low-pressure RO; it is expected to compete favourably against current advanced water reuse technologies that use microfiltration/ultrafiltration and RO. The focus of this research was to assess the efficiency of different cleaning procedures to remove fouling from the surface of a FO membrane during the operation of a submerged system working in FO-mode (active layer (AL) facing feed solution) intended for secondary wastewater effluent (SWWE) recovery, using seawater as draw solution (DS), which will be diluted and can further be fed to a low-pressure RO unit to produce fresh water. Natural organic matter (NOM) fouling was expected to affect the AL, while for the support layer (SL), transparent exopolymer particles (TEP) were used as indicators of fouling due to their stickiness and propensity to enhance the attachment of other foulants in seawater on the membrane surface. The composition of the NOM fouling layer was determined after proper characterisation with a liquid chromatograph coupled with organic carbon detection (LC-OCD), showing biopolymers and protein-like substances as the main constituents. NOM fouling showed high hydraulic reversibility after a 25% flux decline was observed, up to 89.5% when in situ air scouring for 15 min was used as a cleaning technique. Chemical cleaning with a mixture of Alconox, an industrial detergent containing phosphates, and sodium EDTA showed to increase the reversibility (93.6%). Osmotic backwash using a 4% NaCl solution and DI water proved to be ineffective to recover flux due to the salt diffusion phenomena occurring at the AL. Part of the flux that could not be recovered is attributable to TEP fouling on the SL, which forms clusters clearly identifiable with an optical

  5. Cleaning protocol for a FO membrane fouled in wastewater reuse

    KAUST Repository

    Valladares Linares, Rodrigo; Li, Zhenyu; Yangali-Quintanilla, Victor; Li, Qingyu; Amy, Gary L.

    2013-01-01

    Forward osmosis (FO) is an emerging technology which can be applied in water reuse applications. Osmosis is a natural process that involves less energy consumption than reverse osmosis (RO), and therefore can be applied as a dilution process before low-pressure RO; it is expected to compete favourably against current advanced water reuse technologies that use microfiltration/ultrafiltration and RO. The focus of this research was to assess the efficiency of different cleaning procedures to remove fouling from the surface of a FO membrane during the operation of a submerged system working in FO-mode (active layer (AL) facing feed solution) intended for secondary wastewater effluent (SWWE) recovery, using seawater as draw solution (DS), which will be diluted and can further be fed to a low-pressure RO unit to produce fresh water. Natural organic matter (NOM) fouling was expected to affect the AL, while for the support layer (SL), transparent exopolymer particles (TEP) were used as indicators of fouling due to their stickiness and propensity to enhance the attachment of other foulants in seawater on the membrane surface. The composition of the NOM fouling layer was determined after proper characterisation with a liquid chromatograph coupled with organic carbon detection (LC-OCD), showing biopolymers and protein-like substances as the main constituents. NOM fouling showed high hydraulic reversibility after a 25% flux decline was observed, up to 89.5% when in situ air scouring for 15 min was used as a cleaning technique. Chemical cleaning with a mixture of Alconox, an industrial detergent containing phosphates, and sodium EDTA showed to increase the reversibility (93.6%). Osmotic backwash using a 4% NaCl solution and DI water proved to be ineffective to recover flux due to the salt diffusion phenomena occurring at the AL. Part of the flux that could not be recovered is attributable to TEP fouling on the SL, which forms clusters clearly identifiable with an optical

  6. Identifying Typhoon Tracks based on Event Synchronization derived Spatially Embedded Climate Networks

    Science.gov (United States)

    Ozturk, Ugur; Marwan, Norbert; Kurths, Jürgen

    2017-04-01

    Complex networks are commonly used for investigating spatiotemporal dynamics of complex systems, e.g. extreme rainfall. Especially directed networks are very effective tools in identifying climatic patterns on spatially embedded networks. They can capture the network flux, so as the principal dynamics of spreading significant phenomena. Network measures, such as network divergence, bare the source-receptor relation of the directed networks. However, it is still a challenge how to catch fast evolving atmospheric events, i.e. typhoons. In this study, we propose a new technique, namely Radial Ranks, to detect the general pattern of typhoons forward direction based on the strength parameter of the event synchronization over Japan. We suggest to subset a circular zone of high correlation around the selected grid based on the strength parameter. Radial sums of the strength parameter along vectors within this zone, radial ranks are measured for potential directions, which allows us to trace the network flux over long distances. We employed also the delay parameter of event synchronization to identify and separate the frontal storms' and typhoons' individual behaviors.

  7. Performing drought indices to identify the relationship between agricultural losses and drought events in Spain.

    Science.gov (United States)

    Peña Gallardo, Marina; Serrano, Sergio Martín Vicente; Portugués Santiago, Beguería; Burguera Miquel, Tomás

    2017-04-01

    Drought leads to crop failures reducing the productivity. For this reason, the need of appropriate tool for recognize dry periods and evaluate the impact of drought on crop production is important. In this study, we provide an assessment of the relationship between drought episodes and crop failures in Spain as one of the direct consequences of drought is the diminishing of crop yields. First, different drought indices [the Standardized Precipitation and Evapotranspiration Index (SPEI); the Standardized Precipitation Index (SPI); the self-calibrated Palmer Moisture Anomaly Index (Z-Index), the self-calibrated Crop Moisture Index (CMI) and the Standardized Palmer Drought Index (SPDI)] have been calculated at different time scales in order to identify the dry events occurred in Spain and determine the duration and intensity of each event. Second, the drought episodes have been correlated with crop production estimated and final crop production data provided by the Spanish Crop Insurance System for the available period from 1995 to 2014 at the municipal spatial scale, with the purpose of knowing if the characteristics of the drought episodes are reflected on the agricultural losses. The analysis has been carried out in particular for two types of crop, wheat and barley. The results indicate the existence of an agreement between the most important drought events in Spain and the response of the crop productions and the proportion of hectare insurance. Nevertheless, this agreement vary depending on the drought index applied. Authors found a higher competence of the drought indices calculated at different time scales (SPEI, SPI and SPDI) identifying the begging and end of the drought events and the correspondence with the crop failures.

  8. Physiologically-based toxicokinetic models help identifying the key factors affecting contaminant uptake during flood events

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, Markus; Eichbaum, Kathrin [Department of Ecosystem Analysis, Institute for Environmental Research,ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Kammann, Ulrike [Thünen-Institute of Fisheries Ecology, Palmaille 9, 22767 Hamburg (Germany); Hudjetz, Sebastian [Department of Ecosystem Analysis, Institute for Environmental Research,ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Cofalla, Catrina [Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Buchinger, Sebastian; Reifferscheid, Georg [Federal Institute of Hydrology (BFG), Department G3: Biochemistry, Ecotoxicology, Am Mainzer Tor 1, 56068 Koblenz (Germany); Schüttrumpf, Holger [Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Preuss, Thomas [Department of Environmental Biology and Chemodynamics, Institute for Environmental Research,ABBt- Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); and others

    2014-07-01

    Highlights: • A PBTK model for trout was coupled with a sediment equilibrium partitioning model. • The influence of physical exercise on pollutant uptake was studies using the model. • Physical exercise during flood events can increase the level of biliary metabolites. • Cardiac output and effective respiratory volume were identified as relevant factors. • These confounding factors need to be considered also for bioconcentration studies. - Abstract: As a consequence of global climate change, we will be likely facing an increasing frequency and intensity of flood events. Thus, the ecotoxicological relevance of sediment re-suspension is of growing concern. It is vital to understand contaminant uptake from suspended sediments and relate it to effects in aquatic biota. Here we report on a computational study that utilizes a physiologically based toxicokinetic model to predict uptake, metabolism and excretion of sediment-borne pyrene in rainbow trout (Oncorhynchus mykiss). To this end, data from two experimental studies were compared with the model predictions: (a) batch re-suspension experiments with constant concentration of suspended particulate matter at two different temperatures (12 and 24 °C), and (b) simulated flood events in an annular flume. The model predicted both the final concentrations and the kinetics of 1-hydroxypyrene secretion into the gall bladder of exposed rainbow trout well. We were able to show that exhaustive exercise during exposure in simulated flood events can lead to increased levels of biliary metabolites and identified cardiac output and effective respiratory volume as the two most important factors for contaminant uptake. The results of our study clearly demonstrate the relevance and the necessity to investigate uptake of contaminants from suspended sediments under realistic exposure scenarios.

  9. Physiologically-based toxicokinetic models help identifying the key factors affecting contaminant uptake during flood events

    International Nuclear Information System (INIS)

    Brinkmann, Markus; Eichbaum, Kathrin; Kammann, Ulrike; Hudjetz, Sebastian; Cofalla, Catrina; Buchinger, Sebastian; Reifferscheid, Georg; Schüttrumpf, Holger; Preuss, Thomas

    2014-01-01

    Highlights: • A PBTK model for trout was coupled with a sediment equilibrium partitioning model. • The influence of physical exercise on pollutant uptake was studies using the model. • Physical exercise during flood events can increase the level of biliary metabolites. • Cardiac output and effective respiratory volume were identified as relevant factors. • These confounding factors need to be considered also for bioconcentration studies. - Abstract: As a consequence of global climate change, we will be likely facing an increasing frequency and intensity of flood events. Thus, the ecotoxicological relevance of sediment re-suspension is of growing concern. It is vital to understand contaminant uptake from suspended sediments and relate it to effects in aquatic biota. Here we report on a computational study that utilizes a physiologically based toxicokinetic model to predict uptake, metabolism and excretion of sediment-borne pyrene in rainbow trout (Oncorhynchus mykiss). To this end, data from two experimental studies were compared with the model predictions: (a) batch re-suspension experiments with constant concentration of suspended particulate matter at two different temperatures (12 and 24 °C), and (b) simulated flood events in an annular flume. The model predicted both the final concentrations and the kinetics of 1-hydroxypyrene secretion into the gall bladder of exposed rainbow trout well. We were able to show that exhaustive exercise during exposure in simulated flood events can lead to increased levels of biliary metabolites and identified cardiac output and effective respiratory volume as the two most important factors for contaminant uptake. The results of our study clearly demonstrate the relevance and the necessity to investigate uptake of contaminants from suspended sediments under realistic exposure scenarios

  10. CHEMICAL CLEANING OF NANOFILTRATION MEMBRANES FOULED BY ORGANIC MATTERS

    Directory of Open Access Journals (Sweden)

    CHARLENE C. H. KOO

    2016-07-01

    Full Text Available Membrane fouling is a term to describe non-integral substance on membrane surface which results in rapid decline of permeation flux and deteriorate the performance of membrane. Chemical cleaning agents especially like alkaline cleaners are most widely employed to restore the membrane performance. This research mainly investigated the potential use of sodium hydroxide (NaOH and sodium hypochlorite (NaOCl as the chemical cleaning agents to restore the permeate flux of organically fouled nanofiltration (NF membranes under varying applied pressure and flow condition. The performances of the cleaning protocols were quantified using flux recovery and resistance removal. The results demonstrated that NaOCl is more effective than NaOH. This observation is also in line with FTIR analysis in which the transmittance intensity showed by FTIR spectra of NaOCl is higher than that of NaOH. The results also reported that higher flux recovery and resistance removal were achieved when the fouled NF membranes were cleaned with higher concentration of chemical agents and applied pressure. However, the improvements of flux recovery and resistance removal by increasing the applied pressure were found insignificant at higher applied pressure range (16 to 18 bar than the lower applied pressure range (i.e. 12 to 14 bar. This research plays an important role by identifying the key parameters that could restore the flux of organically fouled NF membranes significantly.

  11. Can surveillance systems identify and avert adverse drug events? A prospective evaluation of a commercial application.

    Science.gov (United States)

    Jha, Ashish K; Laguette, Julia; Seger, Andrew; Bates, David W

    2008-01-01

    Computerized monitors can effectively detect and potentially prevent adverse drug events (ADEs). Most monitors have been developed in large academic hospitals and are not readily usable in other settings. We assessed the ability of a commercial program to identify and prevent ADEs in a community hospital. and Measurement We prospectively evaluated the commercial application in a community-based hospital. We examined the frequency and types of alerts produced, how often they were associated with ADEs and potential ADEs, and the potential financial impact of monitoring for ADEs. Among 2,407 patients screened, the application generated 516 high priority alerts. We were able to review 266 alerts at the time they were generated and among these, 30 (11.3%) were considered substantially important to warrant contacting the physician caring for the patient. These 30 alerts were associated with 4 ADEs and 11 potential ADEs. In all 15 cases, the responsible physician was unaware of the event, leading to a change in clinical care in 14 cases. Overall, 23% of high priority alerts were associated with an ADE (95% confidence interval [CI] 12% to 34%) and another 15% were associated with a potential ADE (95% CI 6% to 24%). Active surveillance used approximately 1.5 hours of pharmacist time daily. A commercially available, computer-based ADE detection tool was effective at identifying ADEs. When used as part of an active surveillance program, it can have an impact on preventing or ameliorating ADEs.

  12. Identifying Changes in the Probability of High Temperature, High Humidity Heat Wave Events

    Science.gov (United States)

    Ballard, T.; Diffenbaugh, N. S.

    2016-12-01

    Understanding how heat waves will respond to climate change is critical for adequate planning and adaptation. While temperature is the primary determinant of heat wave severity, humidity has been shown to play a key role in heat wave intensity with direct links to human health and safety. Here we investigate the individual contributions of temperature and specific humidity to extreme heat wave conditions in recent decades. Using global NCEP-DOE Reanalysis II daily data, we identify regional variability in the joint probability distribution of humidity and temperature. We also identify a statistically significant positive trend in humidity over the eastern U.S. during heat wave events, leading to an increased probability of high humidity, high temperature events. The extent to which we can expect this trend to continue under climate change is complicated due to variability between CMIP5 models, in particular among projections of humidity. However, our results support the notion that heat wave dynamics are characterized by more than high temperatures alone, and understanding and quantifying the various components of the heat wave system is crucial for forecasting future impacts.

  13. Model-based analysis of the effect of different operating conditions on fouling mechanisms in a membrane bioreactor.

    Science.gov (United States)

    Sabia, Gianpaolo; Ferraris, Marco; Spagni, Alessandro

    2016-01-01

    This study proposes a model-based evaluation of the effect of different operating conditions with and without pre-denitrification treatment and applying three different solids retention times on the fouling mechanisms involved in membrane bioreactors (MBRs). A total of 11 fouling models obtained from literature were used to fit the transmembrane pressure variations measured in a pilot-scale MBR treating real wastewater for more than 1 year. The results showed that all the models represent reasonable descriptions of the fouling processes in the MBR tested. The model-based analysis confirmed that membrane fouling started by pore blocking (complete blocking model) and by a reduction of the pore diameter (standard blocking) while cake filtration became the dominant fouling mechanism over long-term operation. However, the different fouling mechanisms occurred almost simultaneously making it rather difficult to identify each one. The membrane "history" (i.e. age, lifespan, etc.) seems the most important factor affecting the fouling mechanism more than the applied operating conditions. Nonlinear regression of the most complex models (combined models) evaluated in this study sometimes demonstrated unreliable parameter estimates suggesting that the four basic fouling models (complete, standard, intermediate blocking and cake filtration) contain enough details to represent a reasonable description of the main fouling processes occurring in MBRs.

  14. Signal detection to identify serious adverse events (neuropsychiatric events in travelers taking mefloquine for chemoprophylaxis of malaria

    Directory of Open Access Journals (Sweden)

    Naing C

    2012-08-01

    Full Text Available Cho Naing,1,3 Kyan Aung,1 Syed Imran Ahmed,2 Joon Wah Mak31School of Medical Sciences, 2School of Pharmacy and Health Sciences, 3School of Postgraduate Studies and Research, International Medical University, Kuala Lumpur, MalaysiaBackground: For all medications, there is a trade-off between benefits and potential for harm. It is important for patient safety to detect drug-event combinations and analyze by appropriate statistical methods. Mefloquine is used as chemoprophylaxis for travelers going to regions with known chloroquine-resistant Plasmodium falciparum malaria. As such, there is a concern about serious adverse events associated with mefloquine chemoprophylaxis. The objective of the present study was to assess whether any signal would be detected for the serious adverse events of mefloquine, based on data in clinicoepidemiological studies.Materials and methods: We extracted data on adverse events related to mefloquine chemoprophylaxis from the two published datasets. Disproportionality reporting of adverse events such as neuropsychiatric events and other adverse events was presented in the 2 × 2 contingency table. Reporting odds ratio and corresponding 95% confidence interval [CI] data-mining algorithm was applied for the signal detection. The safety signals are considered significant when the ROR estimates and the lower limits of the corresponding 95% CI are ≥2.Results: Two datasets addressing adverse events of mefloquine chemoprophylaxis (one from a published article and one from a Cochrane systematic review were included for analyses. Reporting odds ratio 1.58, 95% CI: 1.49–1.68 based on published data in the selected article, and 1.195, 95% CI: 0.94–1.44 based on data in the selected Cochrane review. Overall, in both datasets, the reporting odds ratio values of lower 95% CI were less than 2.Conclusion: Based on available data, findings suggested that signals for serious adverse events pertinent to neuropsychiatric event were

  15. The ghost of fouling communities past: the effect of original community on subsequent recruitment.

    Science.gov (United States)

    Ralston, Emily A; Swain, Geoffrey W

    2014-01-01

    Biofouling on ships has been linked to the spread of invasive species, which has been identified as one of the current primary threats to the environment. Previous research on antifouling coatings suggested that the quantity of fouling, as well as community composition, on biocidal coatings was modified by prior fouling settlement. The experiment reported in this paper was designed to determine how preconditioning affected the rate and composition of subsequent fouling on transplanted silicone coatings. A series of 10 × 20 cm panels coated with Intersleek 700 or DC3140 were placed at three locations in Florida (Ponce Inlet, Sebastian Inlet, and Port of Miami), which were characterized by distinct fouling communities. Panels were immersed for four months, cleaned, and reciprocally transplanted among the three sites. Fouling community composition and coverage were characterized at bimonthly intervals both before and after transplantation. The original fouling community affected the subsequent fouling composition and recolonization by tunicates, sea anemones, barnacles, sponges, hydroids, and arborescent bryozoans. The community-level effects were short-term, lasting 2-4 months, but specific responses lasted up to 14 months post-transplant.

  16. EDF approach for fouling mitigation

    International Nuclear Information System (INIS)

    Dijoux, M.; Nordmann, F.; Stutzmann, A.

    2001-01-01

    The situation and evolution of fouling of steam generator tubing are described in the 58 French PWR units, and the different studies and actions carried out to try to solve the problem and avoid any power output reduction associated to pressure drop. The remedies include the selection of the best secondary water treatment with amines such as morpholine in order to minimise corrosion product transport as well as mechanical remedies such as sludge lancing or chemical cleaning. Other options like dispersant addition are under evaluation. (R.P.)

  17. Identifying evidence of climate change impact on extreme events in permeable chalk catchments

    Science.gov (United States)

    Butler, A. P.; Nubert, S.

    2009-12-01

    The permeable chalk catchments of southern England are vital for the economy and well being of the UK. Not only important as a water resource, their freely draining soils support intensive agricultural production, and the rolling downs and chalk streams provide important habitants for many protected plant and animal species. Consequently, there are concerns about the potential impact of climate change on such catchments, particularly in relation to groundwater recharge. Of major concern are possible changes in extreme events, such as groundwater floods and droughts, as any increase in the frequency and/or severity of these has important consequences for water resources, ecological systems and local infrastructure. Studies of climate change impact on extreme events for such catchments have indicated that, under medium and high emissions scenarios, droughts are likely to become more severe whilst floods less so. However, given the uncertainties in such predictions and the inherent variability in historic data, producing definitive evidence of changes in flood/drought frequency/severity poses a significant challenge. Thus, there is a need for specific extreme event statistics that can be used as indicators of actual climate change in streamflow and groundwater level observations. Identifying such indicators that are sufficiently robust requires catchments with long historic time series data. One such catchment is the River Lavant, an intermittent chalk stream in West Sussex, UK. Located within this catchment is Chilgrove House, the site of the UK’s longest groundwater monitoring well (with a continuous record of water level observations of varying frequency dating back to 1836). Using a variety of meteorological datasets, the behaviour of the catchment has been modelled, from 1855 to present, using a 'leaky aquifer' conceptual model. Model calibration was based on observed daily streamflow, at a gauging station just outside the town of Chichester, from 1970. Long

  18. Analysis of fouling in refuse waste incinerators

    NARCIS (Netherlands)

    Beek, van M.C.; Rindt, C.C.M.; Wijers, J.G.; Steenhoven, van A.A.

    2001-01-01

    Gas-side fouling of waste-heat-recovery boilers, caused mainly by the deposition of particulate matter, reduces the heat transfer in the boiler. The fouling as observed on the tube bundles in the boiler of a Dutch refuse waste incinerator varied from thin and powdery for the economizer to thick and

  19. Flux Recovery of a Forward Osmosis Membrane After a Fouling Process

    Science.gov (United States)

    Romero-Mangado, Jaione; Parodi, Jurek; Gamboa-Vazquez, Sonia; Stefanson, Ofir; Diaz-Cartagena, Diana C.; Flynn, Michael

    2016-01-01

    Wastewater treatment through forward osmosis (FO) membranes is a process that has been evaluated in the past years as an innovative technology for the Next Generation Life Support Systems. FO technologies are cost effective, and require very low energy consumption, but are subject to membrane fouling. Membrane fouling occurs when unwanted materials accumulate on the active side of the membrane during the wastewater treatment process, which leads to a decrease in membrane flux rate. The aim of this study is to identify the materials that cause flux rate reduction due to membrane fouling, as well as to evaluate the flux rate recovery after membrane treatment using commercially available antifoulants. Fourier Transform Infrared (FTIR) spectrometry results identified possible compounds that cause membrane fouling and FO testing results demonstrated flux rate recovery after membrane treatment using antifoulants.

  20. Alternative splicing events identified in human embryonic stem cells and neural progenitors.

    Directory of Open Access Journals (Sweden)

    Gene W Yeo

    2007-10-01

    Full Text Available Human embryonic stem cells (hESCs and neural progenitor (NP cells are excellent models for recapitulating early neuronal development in vitro, and are key to establishing strategies for the treatment of degenerative disorders. While much effort had been undertaken to analyze transcriptional and epigenetic differences during the transition of hESC to NP, very little work has been performed to understand post-transcriptional changes during neuronal differentiation. Alternative RNA splicing (AS, a major form of post-transcriptional gene regulation, is important in mammalian development and neuronal function. Human ESC, hESC-derived NP, and human central nervous system stem cells were compared using Affymetrix exon arrays. We introduced an outlier detection approach, REAP (Regression-based Exon Array Protocol, to identify 1,737 internal exons that are predicted to undergo AS in NP compared to hESC. Experimental validation of REAP-predicted AS events indicated a threshold-dependent sensitivity ranging from 56% to 69%, at a specificity of 77% to 96%. REAP predictions significantly overlapped sets of alternative events identified using expressed sequence tags and evolutionarily conserved AS events. Our results also reveal that focusing on differentially expressed genes between hESC and NP will overlook 14% of potential AS genes. In addition, we found that REAP predictions are enriched in genes encoding serine/threonine kinase and helicase activities. An example is a REAP-predicted alternative exon in the SLK (serine/threonine kinase 2 gene that is differentially included in hESC, but skipped in NP as well as in other differentiated tissues. Lastly, comparative sequence analysis revealed conserved intronic cis-regulatory elements such as the FOX1/2 binding site GCAUG as being proximal to candidate AS exons, suggesting that FOX1/2 may participate in the regulation of AS in NP and hESC. In summary, a new methodology for exon array analysis was introduced

  1. New insights into controlling tube-bundle fouling using alternative amines

    International Nuclear Information System (INIS)

    Turner, C.W.; Klimas, S.J.; Guzonas, D.A.; Frattini, P.L.; Fruzzetti, K.

    2002-01-01

    deposit consolidation result in a low rate of deposit removal and a high fouling rate Conversely, amines that tend to inhibit deposit consolidation produce a higher rate of deposit removal and a lower fouling rate. Dimethylamine and dodecylamine have been identified as two amines that inhibit the rate of deposit consolidation and, consequently, result in fouling rates that are up to 5 times lower than rates measured for amines that promote consolidation. A significant difference between morpholine (high fouling rate) and dimethylamine (low fouling rate) is that the latter desorbs more slowly from the surface of magnetite. How to account for a correlation between slow desorption kinetics and lower rate constants for deposition and consolidation is still under investigation. (author)

  2. Searching for storm water inflows in foul sewers using fibre-optic distributed temperature sensing.

    Science.gov (United States)

    Schilperoort, Rémy; Hoppe, Holger; de Haan, Cornelis; Langeveld, Jeroen

    2013-01-01

    A major drawback of separate sewer systems is the occurrence of illicit connections: unintended sewer cross-connections that connect foul water outlets from residential or industrial premises to the storm water system and/or storm water outlets to the foul sewer system. The amount of unwanted storm water in foul sewer systems can be significant, resulting in a number of detrimental effects on the performance of the wastewater system. Efficient removal of storm water inflows into foul sewers requires knowledge of the exact locations of the inflows. This paper presents the use of distributed temperature sensing (DTS) monitoring data to localize illicit storm water inflows into foul sewer systems. Data results from two monitoring campaigns in foul sewer systems in the Netherlands and Germany are presented. For both areas a number of storm water inflow locations can be derived from the data. Storm water inflow can only be detected as long as the temperature of this inflow differs from the in-sewer temperatures prior to the event. Also, the in-sewer propagation of storm and wastewater can be monitored, enabling a detailed view on advection.

  3. Swarm-Aurora: A web-based tool for quickly identifying multi-instrument auroral events

    Science.gov (United States)

    Chaddock, D.; Donovan, E.; Spanswick, E.; Knudsen, D. J.; Frey, H. U.; Kauristie, K.; Partamies, N.; Jackel, B. J.; Gillies, M.; Holmdahl Olsen, P. E.

    2016-12-01

    In recent years there has been a dramatic increase in ground-based auroral imaging systems. These include the continent-wide THEMIS-ASI network, and imagers operated by other programs including GO-Canada, MIRACLE, AGO, OMTI, and more. In the near future, a new Canadian program called TREx will see the deployment of new narrow-band ASIs that will provide multi-wavelength imaging across Western Canada. At the same time, there is an unprecedented fleet of international spacecraft probing geospace at low and high altitudes. We are now in the position to simultaneously observe the magnetospheric drivers of aurora, observe in situ the waves, currents, and particles associated with MI coupling, and the conjugate aurora. Whereas a decade ago, a single magnetic conjunction between one ASI and a low altitude satellite was a relatively rare event, we now have a plethora of triple conjunctions between imagers, low-altitude spacecraft, and near-equatorial magnetospheric probes. But with these riches comes a new level of complexity. It is often difficult to identify the many useful conjunctions for a specific line of inquiry from the multitude of conjunctions where the geospace conditions are often not relevant and/or the imaging is compromised by clouds, moon, or other factors. Swarm-Aurora was designed to facilitate and drive the use of Swarm in situ measurements in auroral science. The project seeks to build a bridge between the Swarm science community, Swarm data, and the complimentary auroral data and community. Swarm-Aurora (http://swarm-aurora.phys.ucalgary.ca) incorporates a web-based tool which provides access to quick-look summary data for a large array of instruments, with Swarm in situ and ground-based ASI data as the primary focus. This web interface allows researchers to quickly and efficiently browse Swarm and ASI data to identify auroral events of interest to them. This allows researchers to be able to easily and quickly identify Swarm overflights of ASIs that

  4. Identifying biologically meaningful hot-weather events using threshold temperatures that affect life-history.

    Directory of Open Access Journals (Sweden)

    Susan J Cunningham

    Full Text Available Increases in the frequency, duration and intensity of heat waves are frequently evoked in climate change predictions. However, there is no universal definition of a heat wave. Recent, intense hot weather events have caused mass mortalities of birds, bats and even humans, making the definition and prediction of heat wave events that have the potential to impact populations of different species an urgent priority. One possible technique for defining biologically meaningful heat waves is to use threshold temperatures (T(thresh above which known fitness costs are incurred by species of interest. We set out to test the utility of this technique using T(thresh values that, when exceeded, affect aspects of the fitness of two focal southern African bird species: the southern pied babbler Turdiodes bicolor (T(thresh = 35.5 °C and the common fiscal Lanius collaris (T(thresh = 33 °C. We used these T(thresh values to analyse trends in the frequency, duration and intensity of heat waves of magnitude relevant to the focal species, as well as the annual number of hot days (maximum air temperature > T(thresh, in north-western South Africa between 1961 and 2010. Using this technique, we were able to show that, while all heat wave indices increased during the study period, most rapid increases for both species were in the annual number of hot days and in the maximum intensity (and therefore intensity variance of biologically meaningful heat waves. Importantly, we also showed that warming trends were not uniform across the study area and that geographical patterns in warming allowed both areas of high risk and potential climate refugia to be identified. We discuss the implications of the trends we found for our focal species, and the utility of the T(thresh technique as a conservation tool.

  5. Fouling distribution in forward osmosis membrane process.

    Science.gov (United States)

    Lee, Junseok; Kim, Bongchul; Hong, Seungkwan

    2014-06-01

    Fouling behavior along the length of membrane module was systematically investigated by performing simple modeling and lab-scale experiments of forward osmosis (FO) membrane process. The flux distribution model developed in this study showed a good agreement with experimental results, validating the robustness of the model. This model demonstrated, as expected, that the permeate flux decreased along the membrane channel due to decreasing osmotic pressure differential across the FO membrane. A series of fouling experiments were conducted under the draw and feed solutions at various recoveries simulated by the model. The simulated fouling experiments revealed that higher organic (alginate) fouling and thus more flux decline were observed at the last section of a membrane channel, as foulants in feed solution became more concentrated. Furthermore, the water flux in FO process declined more severely as the recovery increased due to more foulants transported to membrane surface with elevated solute concentrations at higher recovery, which created favorable solution environments for organic adsorption. The fouling reversibility also decreased at the last section of the membrane channel, suggesting that fouling distribution on FO membrane along the module should be carefully examined to improve overall cleaning efficiency. Lastly, it was found that such fouling distribution observed with co-current flow operation became less pronounced in counter-current flow operation of FO membrane process. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  6. Current research and development of controlling membrane fouling ...

    African Journals Online (AJOL)

    Fouling is a major problem influencing the operational performance, stability and cost of a membrane bioreactor (MBR). The composition of wastewater and biomass grown in the MBR are directly related to fouling. Many factors including operational parameters can affect the fouling process. The extent of fouling can be ...

  7. Identify alternative splicing events based on position-specific evolutionary conservation.

    Directory of Open Access Journals (Sweden)

    Liang Chen

    Full Text Available The evolution of eukaryotes is accompanied by the increased complexity of alternative splicing which greatly expands genome information. One of the greatest challenges in the post-genome era is a complete revelation of human transcriptome with consideration of alternative splicing. Here, we introduce a comparative genomics approach to systemically identify alternative splicing events based on the differential evolutionary conservation between exons and introns and the high-quality annotation of the ENCODE regions. Specifically, we focus on exons that are included in some transcripts but are completely spliced out for others and we call them conditional exons. First, we characterize distinguishing features among conditional exons, constitutive exons and introns. One of the most important features is the position-specific conservation score. There are dramatic differences in conservation scores between conditional exons and constitutive exons. More importantly, the differences are position-specific. For flanking intronic regions, the differences between conditional exons and constitutive exons are also position-specific. Using the Random Forests algorithm, we can classify conditional exons with high specificities (97% for the identification of conditional exons from intron regions and 95% for the classification of known exons and fair sensitivities (64% and 32% respectively. We applied the method to the human genome and identified 39,640 introns that actually contain conditional exons and classified 8,813 conditional exons from the current RefSeq exon list. Among those, 31,673 introns containing conditional exons and 5,294 conditional exons classified from known exons cannot be inferred from RefSeq, UCSC or Ensembl annotations. Some of these de novo predictions were experimentally verified.

  8. How different is the composition of the fouling layer of wastewater reuse and seawater desalination RO membranes?

    KAUST Repository

    Khan, Muhammad; Busch, Markus; Molina, Veró nica Garcí a; Emwas, Abdul-Hamid M.; Aubry, Cyril; Croue, Jean-Philippe

    2014-01-01

    To study the effect of water quality and operating parameters on membrane fouling, a comparative analysis of wastewater (WW) and seawater (SW) fouled reverse osmosis (RO) membranes was conducted. Membranes were harvested from SWRO and WWRO pilot plants located in Vilaseca (East Spain), both using ultrafiltration as pretreatment. The SWRO unit was fed with Mediterranean seawater and the WWRO unit was operated using secondary effluent collected from the municipal wastewater treatment plant. Lead and terminal SWRO and WWRO modules were autopsied after five months and three months of operation, respectively. Ultrastructural, chemical, and microbiological analyses of the fouling layers were performed. Results showed that the WWRO train had mainly bio/organic fouling at the lead position element and inorganic fouling at terminal position element, whereas SWRO train had bio/organic fouling at both end position elements. In the case of WWRO membranes, Betaproteobacteria was the major colonizing species; while Ca, S, and P were the major present inorganic elements. The microbial population of SWRO membranes was mainly represented by Alpha and Gammaproteobacteria. Ca, Fe, and S were the main identified inorganic elements of the fouling layer of SWRO membranes. These results confirmed that the RO fouling layer composition is strongly impacted by the source water quality. © 2014 Elsevier Ltd.

  9. How different is the composition of the fouling layer of wastewater reuse and seawater desalination RO membranes?

    KAUST Repository

    Khan, Muhammad

    2014-08-01

    To study the effect of water quality and operating parameters on membrane fouling, a comparative analysis of wastewater (WW) and seawater (SW) fouled reverse osmosis (RO) membranes was conducted. Membranes were harvested from SWRO and WWRO pilot plants located in Vilaseca (East Spain), both using ultrafiltration as pretreatment. The SWRO unit was fed with Mediterranean seawater and the WWRO unit was operated using secondary effluent collected from the municipal wastewater treatment plant. Lead and terminal SWRO and WWRO modules were autopsied after five months and three months of operation, respectively. Ultrastructural, chemical, and microbiological analyses of the fouling layers were performed. Results showed that the WWRO train had mainly bio/organic fouling at the lead position element and inorganic fouling at terminal position element, whereas SWRO train had bio/organic fouling at both end position elements. In the case of WWRO membranes, Betaproteobacteria was the major colonizing species; while Ca, S, and P were the major present inorganic elements. The microbial population of SWRO membranes was mainly represented by Alpha and Gammaproteobacteria. Ca, Fe, and S were the main identified inorganic elements of the fouling layer of SWRO membranes. These results confirmed that the RO fouling layer composition is strongly impacted by the source water quality. © 2014 Elsevier Ltd.

  10. Reduced Clostridium difficile Tests and Laboratory-Identified Events With a Computerized Clinical Decision Support Tool and Financial Incentive.

    Science.gov (United States)

    Madden, Gregory R; German Mesner, Ian; Cox, Heather L; Mathers, Amy J; Lyman, Jason A; Sifri, Costi D; Enfield, Kyle B

    2018-06-01

    We hypothesized that a computerized clinical decision support tool for Clostridium difficile testing would reduce unnecessary inpatient tests, resulting in fewer laboratory-identified events. Census-adjusted interrupted time-series analyses demonstrated significant reductions of 41% fewer tests and 31% fewer hospital-onset C. difficile infection laboratory-identified events following this intervention.Infect Control Hosp Epidemiol 2018;39:737-740.

  11. Reliability Based Management of Marine Fouling

    DEFF Research Database (Denmark)

    Faber, Michael Havbro; Hansen, Peter Friis

    1999-01-01

    The present paper describes the results of a recent study on the application of methods from structural reliability to optimise management of marine fouling on jacket type structures.In particular the study addresses effects on the structural response by assessment and quantification of uncertain......The present paper describes the results of a recent study on the application of methods from structural reliability to optimise management of marine fouling on jacket type structures.In particular the study addresses effects on the structural response by assessment and quantification...... of uncertainties of a set of parameters. These are the seasonal variation of marine fouling parameters, the wave loading (taking into account the seasonal variation in sea-state statistics), and the effects of spatial variations and seasonal effects of marine fouling parameters. Comparison of design values...

  12. FOULING ORGANISMS OF BUOYS WITHIN MAKHACHKALA SEAPORT

    Directory of Open Access Journals (Sweden)

    C. N. Imachova

    2011-01-01

    Full Text Available It is investigated biofouling buoys within Makhachkala seaport. Seasonal dynamics of development of community, structure species and trophic structure is revealed. It is established vertical zonality in distribution of fouling.

  13. Characterization of fouling of membrane contactors

    DEFF Research Database (Denmark)

    Ciurkot, Kaludia; Zarebska, Agata; Christensen, Knud Villy

    2013-01-01

    of ammonia and membrane fouling tendency. The surface morphology of both clean and fouled membranes by model manure solution and undigested pig manure has been studied by: Optical and Atomic Force Microscopy and contact angle measurements. Based on the experimental results, it is concluded that real manure...... achieved higher ammonia removal than the synthetic model manure solution. This might be due to the larger particle size of the milled straw in the model solution compared to the size of suspended solids present in real manure. From the fouling autopsy, it was found that PTFE membranes are more prone...... to fouling than PP membranes. In both membranes the hydrophobicity decreased after running the process for 30 h, especially when undigested pig manure was used....

  14. Identifying treatment effect heterogeneity in clinical trials using subpopulations of events: STEPP.

    Science.gov (United States)

    Lazar, Ann A; Bonetti, Marco; Cole, Bernard F; Yip, Wai-Ki; Gelber, Richard D

    2016-04-01

    Investigators conducting randomized clinical trials often explore treatment effect heterogeneity to assess whether treatment efficacy varies according to patient characteristics. Identifying heterogeneity is central to making informed personalized healthcare decisions. Treatment effect heterogeneity can be investigated using subpopulation treatment effect pattern plot (STEPP), a non-parametric graphical approach that constructs overlapping patient subpopulations with varying values of a characteristic. Procedures for statistical testing using subpopulation treatment effect pattern plot when the endpoint of interest is survival remain an area of active investigation. A STEPP analysis was used to explore patterns of absolute and relative treatment effects for varying levels of a breast cancer biomarker, Ki-67, in the phase III Breast International Group 1-98 randomized clinical trial, comparing letrozole to tamoxifen as adjuvant therapy for postmenopausal women with hormone receptor-positive breast cancer. Absolute treatment effects were measured by differences in 4-year cumulative incidence of breast cancer recurrence, while relative effects were measured by the subdistribution hazard ratio in the presence of competing risks using O-E (observed-minus-expected) methodology, an intuitive non-parametric method. While estimation of hazard ratio values based on O-E methodology has been shown, a similar development for the subdistribution hazard ratio has not. Furthermore, we observed that the subpopulation treatment effect pattern plot analysis may not produce results, even with 100 patients within each subpopulation. After further investigation through simulation studies, we observed inflation of the type I error rate of the traditional test statistic and sometimes singular variance-covariance matrix estimates that may lead to results not being produced. This is due to the lack of sufficient number of events within the subpopulations, which we refer to as instability of

  15. Using Lead Concentrations and Stable Lead Isotope Ratios to Identify Contamination Events in Alluvial Soils

    Directory of Open Access Journals (Sweden)

    Diane Saint-Laurent

    2010-01-01

    Full Text Available Soils contaminated with hydrocarbons (C10–C50, polycyclic aromatic hydrocarbons (PAHs, and other contaminants (e.g., As, Cd, Cu, Pb were recently discovered on the banks of the Saint-François and Massawippi rivers. Alluvial soils are contaminated over a distance of 100 kilometers, and the level of the contaminated-hydrocarbon layer in the soil profiles is among the highest at the Windsor and Richmond sites. Concentrations of lead and stable lead isotope ratios (204Pb/206Pb, 207Pb/206Pb, 208Pb/206Pb are also used to identify contamination events. The maximum and minimum values detected in soil profiles for arsenic, cadmium, and lead vary from 3.01 to 37.88 mg kg-1 (As, 0.11 to 0.81 mg kg-1 (Cd 12.32 to 149.13 mg kg-1 (Pb, respectively, while the 207Pb/206Pb isotopic ratio values are between 0.8545 and 0.8724 for all the profiles. The highest values of trace elements (As, Pb and Zn were detected in the hydrocarbon layer (C10–C50, most often located at the bottom of the profiles (160, 200, and 220 cm in depth. The various peaks recorded in the soils and the position of the profiles suggest that various contaminants were transported by the river on several occasions and infiltrated the soil matrix or deposited on floodplains during successive floods. Atmospheric particles which entered the river or deposited on riverbanks must also be considered as another source of pollution recorded in soils.

  16. Using Lead Concentrations and Stable Lead Isotope Ratios to Identify Contamination Events in Alluvial Soils

    International Nuclear Information System (INIS)

    Saint-Laurent, D.; St-Laurent, J.; Hahni, M.; Chapados, C.; Ghaleb, B.

    2010-01-01

    Soils contaminated with hydrocarbons (C10,C50), polycyclic aromatic hydrocarbons (PAHs), and other contaminants (e.g., As, Cd, Cu, Pb) were recently discovered on the banks of the Saint-Francois and Massawippi rivers. Alluvial soils are contaminated over a distance of 100 kilometers, and the level of the contaminated-hydrocarbon layer in the soil profiles is among the highest at the Windsor and Richmond sites. Concentrations of lead and stable lead isotope ratios ( 204 Pb/ 206 Pb, 206 Pb/ 207 Pb, 208 Pb/ 20 '6Pb) are also used to identify contamination events. The maximum and minimum values detected in soil profiles for arsenic, cadmium, and lead vary from 3.01 to 37.88?mg kg -1 (As), 0.11 to 0.81?mg kg-1 (Cd) 12.32 to 149.13?mg kg -1 (Pb), respectively, while the 207 Pb/ 206 Pb isotopic ratio values are between 0.8545 and 0.8724 for all the profiles. The highest values of trace elements (As, Pb and Zn) were detected in the hydrocarbon layer (C10,C50), most often located at the bottom of the profiles (160, 200, and 220 cm in depth). The various peaks recorded in the soils and the position of the profiles suggest that various contaminants were transported by the river on several occasions and infiltrated the soil matrix or deposited on flood plains during successive floods. Atmospheric particles which entered the river or deposited on riverbanks must also be considered as another source of pollution recorded in soils

  17. Positive predictive value of a register-based algorithm using the Danish National Registries to identify suicidal events.

    Science.gov (United States)

    Gasse, Christiane; Danielsen, Andreas Aalkjaer; Pedersen, Marianne Giørtz; Pedersen, Carsten Bøcker; Mors, Ole; Christensen, Jakob

    2018-04-17

    It is not possible to fully assess intention of self-harm and suicidal events using information from administrative databases. We conducted a validation study of intention of suicide attempts/self-harm contacts identified by a commonly applied Danish register-based algorithm (DK-algorithm) based on hospital discharge diagnosis and emergency room contacts. Of all 101 530 people identified with an incident suicide attempt/self-harm contact at Danish hospitals between 1995 and 2012 using the DK-algorithm, we selected a random sample of 475 people. We validated the DK-algorithm against medical records applying the definitions and terminology of the Columbia Classification Algorithm of Suicide Assessment of suicidal events, nonsuicidal events, and indeterminate or potentially suicidal events. We calculated positive predictive values (PPVs) of the DK-algorithm to identify suicidal events overall, by gender, age groups, and calendar time. We retrieved medical records for 357 (75%) people. The PPV of the DK-algorithm to identify suicidal events was 51.5% (95% CI: 46.4-56.7) overall, 42.7% (95% CI: 35.2-50.5) in males, and 58.5% (95% CI: 51.6-65.1) in females. The PPV varied further across age groups and calendar time. After excluding cases identified via the DK-algorithm by unspecific codes of intoxications and injury, the PPV improved slightly (56.8% [95% CI: 50.0-63.4]). The DK-algorithm can reliably identify self-harm with suicidal intention in 52% of the identified cases of suicide attempts/self-harm. The PPVs could be used for quantitative bias analysis and implemented as weights in future studies to estimate the proportion of suicidal events among cases identified via the DK-algorithm. Copyright © 2018 John Wiley & Sons, Ltd.

  18. Spider Transcriptomes Identify Ancient Large-Scale Gene Duplication Event Potentially Important in Silk Gland Evolution.

    Science.gov (United States)

    Clarke, Thomas H; Garb, Jessica E; Hayashi, Cheryl Y; Arensburger, Peter; Ayoub, Nadia A

    2015-06-08

    The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae). © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  19. Influence of Microalgae onto submerged surfaces on Fouling

    Science.gov (United States)

    Kong, M.; Eom, C.; Yoon, B.; Yoon, H.; Kim, B.; Chung, K.

    2012-12-01

    Lots of algae together with organic matter deposited on the submerged surface can be easily observed occurring in the shallower water along the coast. This is mainly because only those organisms with the ability to adapt to the new situations created by man can firmly adhere enough to avoid being washed off. Chemical and microbiological characteristics of the fouling microalgae developed on various surfaces in contact with the seawater were made. The microbial compositions of the microalgae formed on the submerged surfaces were tested for. The quantities of the diverse microalgae in the samples developed on the prohibiting submerged surface were larger when there was no concern about materials for special selection for fouling. To confirm formation of microalgae on adsorbents was done SEM-EDS (Scanning Electron Microscope-Spectrometer) analysis. Microbial identified using optical microscope. In addition to, we quantified attaching microalgae as pass time. Experiment results, ten species which are Nitzshhia sp., Eucampia sp., Coscinodiscus sp., Licmophora sp., Rhizosolenia sp., Cylindrotheca sp., Striateela sp., Thalassionema sp., Guinardia sp., and Helicostomella sp. discovered to reservoir formed biofouling. They showed the important role microbial activity in fouling and corrosion of the surfaces in contact with the any seawater.

  20. Drag of Clean and Fouled Net Panels--Measurements and Parameterization of Fouling.

    Directory of Open Access Journals (Sweden)

    Lars Christian Gansel

    Full Text Available Biofouling is a serious problem in marine aquaculture and it has a number of negative impacts including increased forces on aquaculture structures and reduced water exchange across nets. This in turn affects the behavior of fish cages in waves and currents and has an impact on the water volume and quality inside net pens. Even though these negative effects are acknowledged by the research community and governmental institutions, there is limited knowledge about fouling related effects on the flow past nets, and more detailed investigations distinguishing between different fouling types have been called for. This study evaluates the effect of hydroids, an important fouling organism in Norwegian aquaculture, on the forces acting on net panels. Drag forces on clean and fouled nets were measured in a flume tank, and net solidity including effect of fouling were determined using image analysis. The relationship between net solidity and drag was assessed, and it was found that a solidity increase due to hydroids caused less additional drag than a similar increase caused by change in clean net parameters. For solidities tested in this study, the difference in drag force increase could be as high as 43% between fouled and clean nets with same solidity. The relationship between solidity and drag force is well described by exponential functions for clean as well as for fouled nets. A method is proposed to parameterize the effect of fouling in terms of an increase in net solidity. This allows existing numerical methods developed for clean nets to be used to model the effects of biofouling on nets. Measurements with other types of fouling can be added to build a database on effects of the accumulation of different fouling organisms on aquaculture nets.

  1. Identifying Adverse Events Using International Classification of Diseases, Tenth Revision Y Codes in Korea: A Cross-sectional Study

    Directory of Open Access Journals (Sweden)

    Minsu Ock

    2018-01-01

    Full Text Available Objectives The use of administrative data is an affordable alternative to conducting a difficult large-scale medical-record review to estimate the scale of adverse events. We identified adverse events from 2002 to 2013 on the national level in Korea, using International Classification of Diseases, tenth revision (ICD-10 Y codes. Methods We used data from the National Health Insurance Service-National Sample Cohort (NHIS-NSC. We relied on medical treatment databases to extract information on ICD-10 Y codes from each participant in the NHIS-NSC. We classified adverse events in the ICD-10 Y codes into 6 types: those related to drugs, transfusions, and fluids; those related to vaccines and immunoglobulin; those related to surgery and procedures; those related to infections; those related to devices; and others. Results Over 12 years, a total of 20 817 adverse events were identified using ICD-10 Y codes, and the estimated total adverse event rate was 0.20%. Between 2002 and 2013, the total number of such events increased by 131.3%, from 1366 in 2002 to 3159 in 2013. The total rate increased by 103.9%, from 0.17% in 2002 to 0.35% in 2013. Events related to drugs, transfusions, and fluids were the most common (19 446, 93.4%, followed by those related to surgery and procedures (1209, 5.8% and those related to vaccines and immunoglobulin (72, 0.3%. Conclusions Based on a comparison with the results of other studies, the total adverse event rate in this study was significantly underestimated. Improving coding practices for ICD-10 Y codes is necessary to precisely monitor the scale of adverse events in Korea.

  2. Effects of physical and chemical aspects on membrane fouling and cleaning using interfacial free energy analysis in forward osmosis.

    Science.gov (United States)

    Zhang, Wanzhu; Dong, Bingzhi

    2018-05-20

    Natural organic matter (NOM) in micro-polluted water purification using membranes is a critical issue to handle. Understanding the fouling mechanism in the forward osmosis (FO) process, particularly identifying the predominant factor that controls membrane fouling, could have significant effects on exerting the advantages of FO technique. Cellulose triacetate no-woven (CTA-NW) membrane is applied to experiments with a high removal efficiency (> 99%) for the model foulant. Tannic acid (TA) is used as a surrogate foulant for NOM in the membrane fouling process, thus enabling the analysis of the effects of physical and chemical aspects of water flux, retention, and adsorption. The membrane fouling behavior is affected mainly by the combined effects of the osmotic dragging force and the interaction of the pH in the working solution, foulants, and calcium ions, as demonstrated by the water flux loss and the changes of membrane retention and adsorption. The fouled CTA-NW membrane (in PRO mode) could be flux-recovered by > 85% through physical cleaning methods. The interfacial free energy analysis theory was used to analyze the membrane fouling behavior with calculating the interfacial cohesion and adhesion free energies. The cohesion free energy refers to the deposition of foulants (TA or TA combined with calcium ions) on a fouled membrane. In addition, the adhesion free energy could be used to evaluate the interaction between foulants and a clean membrane.

  3. Systematic procedures for identifying t quarks in p-barp collider events with a muon and jets

    International Nuclear Information System (INIS)

    Barger, V.; Baer, H.; Martin, A.D.; Phillips, R.J.N.

    1984-01-01

    Substantial rates are predicted for events containing a muon and jets resulting from W→tb-bar, Z→tt-bar, and tt-bar hadroproduction, with t→μνb decay. We investigate selective cuts to reject backgrounds from bb-bar, cc-bar, and cs-bar production and to identify the t-quark events. For example, from a data sample containing 50 W +- →e +- ν events, we expect that clean samples of approximately 4 tb-bar-(or t-barb-) and conservatively 4 tt-bar-initiated μ +- +jets events can be selected for a t-quark mass below 45 GeV. We suggest methods for distinguishing the contributions and for determining m/sub t/

  4. In-line quantification and characterization of membrane fouling

    KAUST Repository

    Bucs, Szilard; Hekkert, Sacco Te Lintel; Staal, Marc Jaap; Vrouwenvelder, Johannes S.

    2016-01-01

    Methods of detecting, quantifying and/or characterizing the fouling of a device from a combination of pressure and spectroscopic data are provided. The device can be any device containing components susceptible to fouling. Components can include

  5. Role of membrane fouling substances on the rejection of N-nitrosamines by reverse osmosis.

    Science.gov (United States)

    Fujioka, Takahiro; Kodamatani, Hitoshi; Aizawa, Hidenobu; Gray, Stephen; Ishida, Kenneth P; Nghiem, Long D

    2017-07-01

    The impact of fouling substances on the rejection of four N-nitrosamines by a reverse osmosis (RO) membrane was evaluated by characterizing individual organic fractions in a secondary wastewater effluent and deploying a novel high-performance liquid chromatography-photochemical reaction-chemiluminescence (HPLC-PR-CL) analytical technique. The HPLC-PR-CL analytical technique allowed for a systematic examination of the correlation between the fouling level and the permeation of N-nitrosamines in the secondary wastewater effluent and synthetic wastewaters through an RO membrane. Membrane fouling caused by the secondary wastewater effluent led to a notable decrease in the permeation of N-nitrosodimethylamine (NDMA) while a smaller but nevertheless discernible decrease in the permeation of N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPYR) and N-nitrosomorpholine (NMOR) was also observed. Fluorescence spectrometry analysis revealed that major foulants in the secondary wastewater effluent were humic and fulvic acid-like substances. Analysis using the size exclusion chromatography technique also identified polysaccharides and proteins as additional fouling substances. Thus, further examination was conducted using solutions containing model foulants (i.e., sodium alginate, bovine serum albumin, humic acid and two fulvic acids). Similar to the secondary wastewater effluent, membrane fouling with fulvic acid solutions resulted in a decrease in N-nitrosamine permeation. In contrast, membrane fouling with the other model foulants resulted in a negligible impact on N-nitrosamine permeation. Overall, these results suggest that the impact of fouling on the permeation of N-nitrosamines by RO is governed by specific small organic fractions (e.g. fulvic acid-like organics) in the secondary wastewater effluent. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Inorganic fouling mitigation by salinity cycling in batch reverse osmosis

    OpenAIRE

    Maswadeh, Laith A.; Warsinger, David Elan Martin; Tow, Emily W.; Connors, Grace B.; Swaminathan, Jaichander; Lienhard, John H

    2018-01-01

    Enhanced fouling resistance has been observed in recent variants of reverse osmosis (RO) desalination which use time-varying batch or semi-batch processes, such as closed-circuit RO (CCRO) and pulse flow RO (PFRO). However, the mechanisms of batch processes' fouling resistance are not well-understood, and models have not been developed for prediction of their fouling performance. Here, a framework for predicting reverse osmosis fouling is developed by comparing the fluid residence time in bat...

  7. Identifying Population Vulnerable to Extreme Heat Events in San Jose, California.

    Science.gov (United States)

    Rivera, A. L.

    2016-12-01

    The extreme heat days not only make cities less comfortable for living but also they are associated with increased morbidity and mortality. Mapping studies have demonstrated spatial variability in heat vulnerability. A study conducted between 2000 and 2011 in New York City shows that deaths during heat waves was more likely to occur in black individuals, at home in census tracts which received greater public assistance. This map project intends to portray areas in San Jose California that are vulnerable to extreme heat events. The variables considered to build a vulnerability index are: land surface temperature, vegetated areas (NDVI), and people exposed to these area (population density).

  8. Bibliography on Fouling, Biodeterioration and their Control.

    Science.gov (United States)

    1981-06-01

    34 In: Proceedings of the 4th International Congress on Marine Corrosion and Fouling. pp 271- 277. Antibes, 1976 294. Jones, G. D. and R. G. Asperger ...J. "Antifouling Measures on Ships - A General Survey" Report NTIS AD-B032-858 (October, 1978) 335. Lustigman, B. and I. R. Isquith, "The Enhanced ...Fouling Organisms. In: Proceedings of the Protection of Materials in the Sea" pp 327-329. Bombay, 1977. 437. Ray, L. L. "Citric Acid Enhancement of Copper

  9. Fouling mechanisms of dairy streams during membrane distillation

    NARCIS (Netherlands)

    Hausmann, A.; Sanciolo, P.; Vasiljevic, T.; Weeks, M.; Schroën, C.G.P.H.; Gray, S.; Duke, M.

    2013-01-01

    This study reports on fouling mechanisms of skim milk and whey during membrane distillation (MD) using polytetrafluoroethylene (PTFE) membranes. Structural and elemental changes along the fouling layer from the anchorpoint at the membrane to the topsurface of the fouling layer have been investigated

  10. Slagging and fouling evaluation of PC-fired boilers using AshPro{sup SM}

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhanhua; Iman, Felicia; Lu, Pisi [SmartBurn, LLC, Madison, WI (United States)

    2013-07-01

    SmartBurn {sup registered} applied AshPro{sup SM} model to two 512 MW Tangential-fired (T-fired) boilers firing US western sub- bituminous coals to evaluate the boiler slagging behaviors with different operating conditions and OFA. The boiler convective pass fouling behaviors with three different coals were also evaluated. The slagging evaluation results indicate that the OFA configuration and air flow distribution have dramatically impacts on the ash impaction rates and slagging patterns on the furnace walls. Deposit growth and strength vary at the different regions of the furnace walls. The fouling evaluation reveals that the tube bank configuration, the amount of incoming ash, the profiles of flue gas temperature, velocity, and species all have significant impacts on fouling deposit formation, growth, and strength development. In addition, the varying ash particle sizes and chemical compositions from different coals also play important roles on the fouling deposit strength development and removal. The investigation demonstrated that AshPro{sup SM} model can be used to evaluate localized slagging and fouling problems that are related to specific boiler configuration and operating conditions. It can be used to identify the major causes of ash deposition and can guide changes in boiler operation.

  11. Identifying Weak Ties from Publicly Available Social Media Data in an Event

    DEFF Research Database (Denmark)

    Prakash Gupta, Jayesh; Menon, Karan; Kärkkäinen, Hannu

    2016-01-01

    The concept of weak ties was introduced by Granovetter through the seminal paper titled "Strength of weak ties". Since then the role of weak ties in general and their specific role as occupying the structural hole has been explored in many different fields. In this study, we identify actual or po...

  12. Positive predictive value of a register-based algorithm using the Danish National Registries to identify suicidal events

    DEFF Research Database (Denmark)

    Gasse, Christiane; Danielsen, Andreas Aalkjaer; Pedersen, Marianne Giørtz

    2018-01-01

    events overall, by gender, age groups, and calendar time. RESULTS: We retrieved medical records for 357 (75%) people. The PPV of the DK-algorithm to identify suicidal events was 51.5% (95% CI: 46.4-56.7) overall, 42.7% (95% CI: 35.2-50.5) in males, and 58.5% (95% CI: 51.6-65.1) in females. The PPV varied...... further across age groups and calendar time. After excluding cases identified via the DK-algorithm by unspecific codes of intoxications and injury, the PPV improved slightly (56.8% [95% CI: 50.0-63.4]). CONCLUSIONS: The DK-algorithm can reliably identify self-harm with suicidal intention in 52......PURPOSE: It is not possible to fully assess intention of self-harm and suicidal events using information from administrative databases. We conducted a validation study of intention of suicide attempts/self-harm contacts identified by a commonly applied Danish register-based algorithm (DK...

  13. New insights into controlling tube-bundle fouling using alternative amines

    Energy Technology Data Exchange (ETDEWEB)

    Turner, C.W.; Klimas, S.J.; Guzonas, D.A.; Fruzzetti, K. [Atomic Energy of Canada Ltd. (Canada); Frattini, P.L. [Electric Power Research Inst. (United States)

    2002-07-01

    A volatile amine is added to the secondary heat-transport system of a nuclear power plant to reduce the rate of corrosion and corrosion product transport in the feedwater and to protect steam generator (SG) crevices and materials exposed to steam condensate. Volatility and base strength of the amine at the SG operating temperature are two important considerations when choosing the optimum amine (or mixture of amines) for corrosion control in the steam cycle. The investigation has found that the rate of tube-bundle fouling is strongly dependent upon the surface chemistry of the corrosion products. For example, the fouling rates of fully oxidized iron oxides, such as hematite and lepidocrocite, are at least an order of magnitude greater than the fouling rate of magnetite under identical operating conditions. The difference is related to the sign of the surface charge on the corrosion products at temperature. The choice of amine for pH-control also influences the fouling rate. This was originally thought to be a surface-charge effect as well, but recent tests have suggested that it is related to the role that the amine plays in governing the rate of deposit consolidation on the heat-transfer surface. Amines that promote a high rate of deposit consolidation result in a low rate of deposit removal and a high fouling rate. Conversely, amines that tend to inhibit deposit consolidation produce a higher rate of deposit removal and a lower fouling rate. Dimethyl-amine and dodecyl-amine have been identified as two amines that inhibit the rate of deposit consolidation and, consequently, result in fouling rates that are up to 5 times lower than rates measured for amines that promote consolidation. A significant difference between morpholine (high fouling rate) and dimethyl-amine (low fouling rate) is that the latter desorbs more slowly from the surface of magnetite. How to account for a correlation between slow desorption kinetics and lower rate constants for deposition and

  14. New insights into controlling tube-bundle fouling using alternative amines

    International Nuclear Information System (INIS)

    Turner, C.W.; Klimas, S.J.; Guzonas, D.A.; Fruzzetti, K.; Frattini, P.L.

    2002-01-01

    A volatile amine is added to the secondary heat-transport system of a nuclear power plant to reduce the rate of corrosion and corrosion product transport in the feedwater and to protect steam generator (SG) crevices and materials exposed to steam condensate. Volatility and base strength of the amine at the SG operating temperature are two important considerations when choosing the optimum amine (or mixture of amines) for corrosion control in the steam cycle. The investigation has found that the rate of tube-bundle fouling is strongly dependent upon the surface chemistry of the corrosion products. For example, the fouling rates of fully oxidized iron oxides, such as hematite and lepidocrocite, are at least an order of magnitude greater than the fouling rate of magnetite under identical operating conditions. The difference is related to the sign of the surface charge on the corrosion products at temperature. The choice of amine for pH-control also influences the fouling rate. This was originally thought to be a surface-charge effect as well, but recent tests have suggested that it is related to the role that the amine plays in governing the rate of deposit consolidation on the heat-transfer surface. Amines that promote a high rate of deposit consolidation result in a low rate of deposit removal and a high fouling rate. Conversely, amines that tend to inhibit deposit consolidation produce a higher rate of deposit removal and a lower fouling rate. Dimethyl-amine and dodecyl-amine have been identified as two amines that inhibit the rate of deposit consolidation and, consequently, result in fouling rates that are up to 5 times lower than rates measured for amines that promote consolidation. A significant difference between morpholine (high fouling rate) and dimethyl-amine (low fouling rate) is that the latter desorbs more slowly from the surface of magnetite. How to account for a correlation between slow desorption kinetics and lower rate constants for deposition and

  15. Domain-restricted mutation analysis to identify novel driver events in human cancer

    Directory of Open Access Journals (Sweden)

    Sanket Desai

    2017-10-01

    Full Text Available Analysis of mutational spectra across various cancer types has given valuable insights into tumorigenesis. Different approaches have been used to identify novel drivers from the set of somatic mutations, including the methods which use sequence conservation, geometric localization and pathway information. Recent computational methods suggest use of protein domain information for analysis and understanding of the functional consequence of non-synonymous mutations. Similarly, evidence suggests recurrence at specific position in proteins is robust indicators of its functional impact. Building on this, we performed a systematic analysis of TCGA exome derived somatic mutations across 6089 PFAM domains and significantly mutated domains were identified using randomization approach. Multiple alignment of individual domain allowed us to prioritize for conserved residues mutated at analogous positions across different proteins in a statistically disciplined manner. In addition to the known frequently mutated genes, this analysis independently identifies low frequency Meprin and TRAF-Homology (MATH domain in Speckle Type BTB/POZ (SPOP protein, in prostate adenocarcinoma. Results from this analysis will help generate hypotheses about the downstream molecular mechanism resulting in cancer phenotypes.

  16. Identifying the null subject: evidence from event-related brain potentials.

    Science.gov (United States)

    Demestre, J; Meltzer, S; García-Albea, J E; Vigil, A

    1999-05-01

    Event-related brain potentials (ERPs) were recorded during spoken language comprehension to study the on-line effects of gender agreement violations in controlled infinitival complements. Spanish sentences were constructed in which the complement clause contained a predicate adjective marked for syntactic gender. By manipulating the gender of the antecedent (i.e., the controller) of the implicit subject while holding constant the gender of the adjective, pairs of grammatical and ungrammatical sentences were created. The detection of such a gender agreement violation would indicate that the parser had established the coreference relation between the null subject and its antecedent. The results showed a complex biphasic ERP (i.e., an early negativity with prominence at anterior and central sites, followed by a centroparietal positivity) in the violating condition as compared to the non-violating conditions. The brain reacts to NP-adjective gender agreement violations within a few hundred milliseconds of their occurrence. The data imply that the parser has properly coindexed the null subject of an infinitive clause with its antecedent.

  17. SDI: Is it a reliable fouling index?

    NARCIS (Netherlands)

    Al-Hadidi, A.M.M.; Kemperman, Antonius J.B.; Schippers, J.C.; Wessling, Matthias; van der Meer, Walterus Gijsbertus Joseph

    2012-01-01

    The ASTM considers the silt density index (SDI) test as a standard test for fouling potential of RO and NF feed waters. Up to date, the SDI is used at many full- and pilot-scale installations. The design and choice of the applied RO pretreatment is to a large extent based on the SDI test on the raw

  18. Amphiphilic copolymers for fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, Stefan Møller; Hvilsted, Søren

    of the coatings [9,10,11]. This work shows the effect of an amphiphilic copolymer that induces hydrophilicity on the surface of the silicone-based fouling release coatings. The behaviour of these copolymers within the coating upon immersion and the interaction of these surface-active additives with other...

  19. Fouling in organic-cooled systems

    International Nuclear Information System (INIS)

    Charlesworth, D.H.

    1963-04-01

    Studies of organic coolants in the out-reactor 250-0-1 loop and in the in-reactor X-7 loop have shown that fouling films are deposited on heat-transfer surfaces by two mechanisms, one involving soluble impurities and the other insoluble impurities in the coolant. The simultaneous action of two mechanisms of deposition can lead to a wide variety of compositions and structures of the deposited film. The concentration of impurities is the most important factor controlling the deposition rate. Coolant velocity and surface temperature also have major effects on the fouling rate. At low chlorine levels continuous coolant cleanup through Attapulgus clay has been shown to reduce deposition rates under representative reactor conditions from 100 μg/cm 2 hr to 1 μg/cm 2 hr. Chlorine, which is a strong promoter of fouling, is not removed by Attapulgus clay. Further studies of its important effect on fouling and its removal will be the subjects of separate reports. An acceptable deposition rate of 0.3 μg/cm 2 hr should be achieved by intensive purification, coupled with the exclusion of impurities such as chlorine. (author)

  20. CROSS-FLOW ULTRAFILTRATION OF SECONDARY EFFLUENTS. MEMBRANE FOULING ANALYSIS

    Directory of Open Access Journals (Sweden)

    Luisa Vera

    2014-12-01

    Full Text Available The application of cross-flow ultrafiltration to regenerate secondary effluents is limited by membrane fouling. This work analyzes the influence of the main operational parameters (transmembrane pressure and cross-flow velocity about the selectivity and fouling observed in an ultrafiltration tubular ceramic membrane. The experimental results have shown a significant retention of the microcolloidal and soluble organic matter (52 – 54% in the membrane. The fouling analysis has defined the critical operational conditions where the fouling resistance is minimized. Such conditions can be described in terms of a dimensionless number known as shear stress number and its relationship with other dimensionless parameter, the fouling number.

  1. The Modified Fouling Index Ultrafiltration constant flux for assessing particulate/colloidal fouling of RO systems

    KAUST Repository

    Salinas-Rodriguez, Sergio G.

    2015-02-18

    Reliable methods for measuring and predicting the fouling potential of reverse osmosis (RO) feed water are important in preventing and diagnosing fouling at the design stage, and for monitoring pre-treatment performance during plant operation. The Modified Fouling Index Ultrafiltration (MFI-UF) constant flux is a significant development with respect to assessing the fouling potential of RO feed water. This research investigates (1) the variables influencing the MFI-UF test at constant flux filtration (membrane pore size, membrane material, flux rate); and (2) the application of MFI-UF into pre-treatment assessment and RO fouling estimation. The dependency of MFI on flux, means that to assess accurately particulate fouling in RO systems, the MFI should be measured at a flux similar to a RO system (close to 20 L/m2/h) or extrapolated from higher fluxes. The two studied membrane materials showed reproducible results; 10% for PES membranes and 6.3% for RC membranes. Deposition factors (amount of particles that remain on the surface of membrane) were measured in a full-scale plant ranging between 0.2 and 0.5. The concept of “safe MFI” is presented as a guideline for assessing pre-treatment for RO systems.

  2. Mitigation of Syngas Cooler Plugging and Fouling

    Energy Technology Data Exchange (ETDEWEB)

    Bockelie, Michael J. [Reaction Engineering International, Salt Lake City, UT (United States)

    2015-06-29

    This Final Report summarizes research performed to develop a technology to mitigate the plugging and fouling that occurs in the syngas cooler used in many Integrated Gasification Combined Cycle (IGCC) plants. The syngas cooler is a firetube heat exchanger located downstream of the gasifier. It offers high thermal efficiency, but its’ reliability has generally been lower than other process equipment in the gasification island. The buildup of ash deposits that form on the fireside surfaces in the syngas cooler (i.e., fouling) lead to reduced equipment life and increased maintenance costs. Our approach to address this problem is that fouling of the syngas cooler cannot be eliminated, but it can be better managed. The research program was funded by DOE using two budget periods: Budget Period 1 (BP1) and Budget Period 2 (BP2). The project used a combination of laboratory scale experiments, analysis of syngas cooler deposits, modeling and guidance from industry to develop a better understanding of fouling mechanisms and to develop and evaluate strategies to mitigate syngas cooler fouling and thereby improve syngas cooler performance. The work effort in BP 1 and BP 2 focused on developing a better understanding of the mechanisms that lead to syngas cooler plugging and fouling and investigating promising concepts to mitigate syngas cooler plugging and fouling. The work effort focused on the following: • analysis of syngas cooler deposits and fuels provided by an IGCC plant collaborating with this project; • performing Jet cleaning tests in the University of Utah Laminar Entrained Flow Reactor to determine the bond strength between an ash deposit to a metal plate, as well as implementing planned equipment modifications to the University of Utah Laminar Entrained Flow Reactor and the one ton per day, pressurized Pilot Scale Gasifier; • performing Computational Fluid Dynamic modeling of industrially relevant syngas cooler configurations to develop a better

  3. Using event related potentials to identify a user's behavioural intention aroused by product form design.

    Science.gov (United States)

    Ding, Yi; Guo, Fu; Zhang, Xuefeng; Qu, Qingxing; Liu, Weilin

    2016-07-01

    The capacity of product form to arouse user's behavioural intention plays a decisive role in further user experience, even in purchase decision, while traditional methods rarely give a fully understanding of user experience evoked by product form, especially the feeling of anticipated use of product. Behavioural intention aroused by product form designs has not yet been investigated electrophysiologically. Hence event related potentials (ERPs) were applied to explore the process of behavioural intention when users browsed different smart phone form designs with brand and price not taken into account for mainly studying the brain activity evoked by variety of product forms. Smart phone pictures with different anticipated user experience were displayed with equiprobability randomly. Participants were asked to click the left mouse button when certain picture gave them a feeling of behavioural intention to interact with. The brain signal of each participant was recorded by Curry 7.0. The results show that pictures with an ability to arouse participants' behavioural intention for further experience can evoke enhanced N300 and LPPs (late positive potentials) in central-parietal, parietal and occipital regions. The scalp topography shows that central-parietal, parietal and occipital regions are more activated. The results indicate that the discrepancy of ERPs can reflect the neural activities of behavioural intention formed or not. Moreover, amplitude of ERPs occurred in corresponding brain areas can be used to measure user experience. The exploring of neural correlated with behavioural intention provide an accurate measurement method of user's perception and help marketers to know which product can arouse users' behavioural intention, maybe taken as an evaluating indicator of product design. Copyright © 2016 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  4. Clustering of transcriptional profiles identifies changes to insulin signaling as an early event in a mouse model of Alzheimer's disease.

    Science.gov (United States)

    Jackson, Harriet M; Soto, Ileana; Graham, Leah C; Carter, Gregory W; Howell, Gareth R

    2013-11-25

    Alzheimer's disease affects more than 35 million people worldwide but there is no known cure. Age is the strongest risk factor for Alzheimer's disease but it is not clear how age-related changes impact the disease. Here, we used a mouse model of Alzheimer's disease to identify age-specific changes that occur prior to and at the onset of traditional Alzheimer-related phenotypes including amyloid plaque formation. To identify these early events we used transcriptional profiling of mouse brains combined with computational approaches including singular value decomposition and hierarchical clustering. Our study identifies three key events in early stages of Alzheimer's disease. First, the most important drivers of Alzheimer's disease onset in these mice are age-specific changes. These include perturbations of the ribosome and oxidative phosphorylation pathways. Second, the earliest detectable disease-specific changes occur to genes commonly associated with the hypothalamic-adrenal-pituitary (HPA) axis. These include the down-regulation of genes relating to metabolism, depression and appetite. Finally, insulin signaling, in particular the down-regulation of the insulin receptor substrate 4 (Irs4) gene, may be an important event in the transition from age-related changes to Alzheimer's disease specific-changes. A combination of transcriptional profiling combined with computational analyses has uncovered novel features relevant to Alzheimer's disease in a widely used mouse model and offers avenues for further exploration into early stages of AD.

  5. A novel computational method identifies intra- and inter-species recombination events in Staphylococcus aureus and Streptococcus pneumoniae.

    Directory of Open Access Journals (Sweden)

    Lisa Sanguinetti

    Full Text Available Advances in high-throughput DNA sequencing technologies have determined an explosion in the number of sequenced bacterial genomes. Comparative sequence analysis frequently reveals evidences of homologous recombination occurring with different mechanisms and rates in different species, but the large-scale use of computational methods to identify recombination events is hampered by their high computational costs. Here, we propose a new method to identify recombination events in large datasets of whole genome sequences. Using a filtering procedure of the gene conservation profiles of a test genome against a panel of strains, this algorithm identifies sets of contiguous genes acquired by homologous recombination. The locations of the recombination breakpoints are determined using a statistical test that is able to account for the differences in the natural rate of evolution between different genes. The algorithm was tested on a dataset of 75 genomes of Staphylococcus aureus and 50 genomes comprising different streptococcal species, and was able to detect intra-species recombination events in S. aureus and in Streptococcus pneumoniae. Furthermore, we found evidences of an inter-species exchange of genetic material between S. pneumoniae and Streptococcus mitis, a closely related commensal species that colonizes the same ecological niche. The method has been implemented in an R package, Reco, which is freely available from supplementary material, and provides a rapid screening tool to investigate recombination on a genome-wide scale from sequence data.

  6. Violence in youth sports: hazing, brawling and foul play.

    Science.gov (United States)

    Fields, S K; Collins, C L; Comstock, R D

    2010-01-01

    By separating hazing, brawling, and foul play and failing to recognise that their connection to sport binds them together into a cohesive subset of sport injury and youth violence, past research has failed to show how sports-related violence is a broad example of interpersonal violence. The acceptance of violence within the sporting culture may, in part, explain why sports-related violence has not yet been widely recognised as a public health concern. This review shows that sports-related violence, including hazing, brawling and foul play, occurs among youth athletes of all ages and in a variety of different sports. The few studies to address this issue have all acknowledged the dangers of sports-related violence; however, no incident tracking method has been developed. Future research must provide accurate national estimates of the incidence of sports-related violence among youth, identify associated risk factors, evaluate preventive interventions and identify effective methods of distributing and implementing evidence-based interventions. Monitoring the magnitude and distribution of the burden of sports-related violence and building the scientific infrastructure necessary to support the development and widespread application of effective sports-related prevention interventions are essential first steps toward a reduction in the incidence of sports-related violence.

  7. Events

    Directory of Open Access Journals (Sweden)

    Igor V. Karyakin

    2016-02-01

    Full Text Available The 9th ARRCN Symposium 2015 was held during 21st–25th October 2015 at the Novotel Hotel, Chumphon, Thailand, one of the most favored travel destinations in Asia. The 10th ARRCN Symposium 2017 will be held during October 2017 in the Davao, Philippines. International Symposium on the Montagu's Harrier (Circus pygargus «The Montagu's Harrier in Europe. Status. Threats. Protection», organized by the environmental organization «Landesbund für Vogelschutz in Bayern e.V.» (LBV was held on November 20-22, 2015 in Germany. The location of this event was the city of Wurzburg in Bavaria.

  8. Understanding the fouling of UF/MF hollow fibres of biologically treated wastewaters using advanced EfOM characterization and statistical tools

    KAUST Repository

    Filloux, Emmanuelle

    2012-08-01

    Five secondary effluents and a river water source were characterized using size exclusion chromatography (LC-OCD-UVD-OND) and emission-excitation matrix (EEM) fluorescence spectroscopy in order to identify the major effluent organic matter (EfOM) fractions responsible for membrane fouling. This study showed the feasibility of coupling fluorescence EEM and LC-OCD-UVD-OND to investigate the fouling potential as well as a means to differentiate natural organic matter (NOM) from EfOM. The secondary effluents and river water showed a significant difference in organic matter characteristics and fouling potential, highlighting the importance of biological processes and the feed water source on EfOM characteristics and fouling potential. On the basis of statistical analysis, protein-like substances were found to be highly correlated to the fouling potential of secondary effluents. © 2012 Elsevier Ltd.

  9. Understanding the fouling of UF/MF hollow fibres of biologically treated wastewaters using advanced EfOM characterization and statistical tools

    KAUST Repository

    Filloux, Emmanuelle; Labanowski, Jé rô me; Croue, Jean-Philippe

    2012-01-01

    Five secondary effluents and a river water source were characterized using size exclusion chromatography (LC-OCD-UVD-OND) and emission-excitation matrix (EEM) fluorescence spectroscopy in order to identify the major effluent organic matter (EfOM) fractions responsible for membrane fouling. This study showed the feasibility of coupling fluorescence EEM and LC-OCD-UVD-OND to investigate the fouling potential as well as a means to differentiate natural organic matter (NOM) from EfOM. The secondary effluents and river water showed a significant difference in organic matter characteristics and fouling potential, highlighting the importance of biological processes and the feed water source on EfOM characteristics and fouling potential. On the basis of statistical analysis, protein-like substances were found to be highly correlated to the fouling potential of secondary effluents. © 2012 Elsevier Ltd.

  10. Novel graphical approach as fouling pinch for increasing fouling formation period in heat exchanger network (HEN) state of the art

    International Nuclear Information System (INIS)

    Azad, Abazar Vahdat; Ghaebi, Hadi; Amidpour, Majid

    2011-01-01

    In this paper a new graphical tool is proposed for investigation of fouling formation period in heat exchanger networks (HEN). The objective of this paper is increasing the time that HEN can perform its desirable heat transfer operation without required cleaning process. In a typical heat exchanger network, fouling formation rate of some streams is more than other ones. The method obtained in this work is based on given more opportunity for fouling formation for streams with high fouling formation rate. In fact high fouling formation rate streams are replaced with low fouling formation rate streams between different heat exchangers so that more fouling formation opportunity may be given for HEN. Therefore the HEN cleaning time decreases in fixed time period and the high fouling formation streams should pass from the path that the low fouling formation rate stream previously has passed, and inversely. As a result, secondly stream with high fouling formation rate mixes with residues of primary stream (low fouling formation rate stream). Therefore we should consider to adoption and conformability of streams structures (for prevention of streams destruction) and thermal considerations (for desirable heat transfer). Outlet temperatures of hot and cold streams should state in predefined temperatures. For satisfying thermal consideration after streams replacement this approach can be used in plants that cleanliness and its operational costs are most important problem.

  11. A new index for identifying socioeconomic drought events under climate change over the East River basin in China

    Science.gov (United States)

    Shi, H.; Chen, J.; Wang, K.; Niu, J.

    2017-12-01

    Drought, which means severe water deficiencies, is a complex natural hazard that may have destructive damages on societal properties and lives. Generally, socioeconomic drought occurs when the water resources systems cannot meet the water demands due to a weather-related shortfall in water supply to societies. This paper aims to propose a new index (i.e., socioeconomic drought index (SEDI)) for identifying socioeconomic drought events on different levels (i.e., slight, moderate, severe and extreme) under climate change through considering the gap between water supply and demand. First, the minimum in-stream water requirement (MWR) is determined through comprehensively considering the requirements of water quality, ecology, navigation and water supply. Second, according to the monthly water deficit calculated as the monthly streamflow data minus the MWR, drought month can be identified. Third, according to the cumulative water deficit derived from the monthly water deficit, drought duration (i.e., the number of continuous drought months) can be detected. Fourth, the SEDI of each socioeconomic drought event can be calculated through integrating the impacts of the cumulative water deficit and drought duration. The study area is the East River basin in South China, and the impact of a multi-year reservoir (i.e., the Xinfengjiang Reservoir) on drought is also analyzed. For historical and future drought analysis, it is concluded that the proposed SEDI is feasible to identify socioeconomic drought events. The results show that a number of socioeconomic drought events (including some extreme ones) may occur during 2020-2099, and the appropriate reservoir operation can significantly ease such situation.

  12. Automatically Identifying Fusion Events between GLUT4 Storage Vesicles and the Plasma Membrane in TIRF Microscopy Image Sequences

    Directory of Open Access Journals (Sweden)

    Jian Wu

    2015-01-01

    Full Text Available Quantitative analysis of the dynamic behavior about membrane-bound secretory vesicles has proven to be important in biological research. This paper proposes a novel approach to automatically identify the elusive fusion events between VAMP2-pHluorin labeled GLUT4 storage vesicles (GSVs and the plasma membrane. The differentiation is implemented to detect the initiation of fusion events by modified forward subtraction of consecutive frames in the TIRFM image sequence. Spatially connected pixels in difference images brighter than a specified adaptive threshold are grouped into a distinct fusion spot. The vesicles are located at the intensity-weighted centroid of their fusion spots. To reveal the true in vivo nature of a fusion event, 2D Gaussian fitting for the fusion spot is used to derive the intensity-weighted centroid and the spot size during the fusion process. The fusion event and its termination can be determined according to the change of spot size. The method is evaluated on real experiment data with ground truth annotated by expert cell biologists. The evaluation results show that it can achieve relatively high accuracy comparing favorably to the manual analysis, yet at a small fraction of time.

  13. Effects of COD/N ratio on soluble microbial products in effluent from sequencing batch reactors and subsequent membrane fouling.

    Science.gov (United States)

    Ly, Quang Viet; Nghiem, Long D; Sibag, Mark; Maqbool, Tahir; Hur, Jin

    2018-05-01

    The relative ratios of chemical oxygen demand (COD) to nitrogen (N) in wastewater are known to have profound effects on the characteristics of soluble microbial products (SMP) from activated sludge. In this study, the changes in the SMP characteristics upon different COD/N ratios and the subsequent effects on ultrafiltration (UF) membrane fouling potentials were examined in sequencing batch reactors (SBR) using excitation emission matrix-parallel factor analysis (EEM-PARAFAC) and size exclusion chromatography (SEC). Three unique fluorescent components were identified from the SMP samples in the bioreactors operated at the COD/N ratios of 100/10 (N rich), 100/5 (N medium), and 100/2 (N deficient). The tryptophan-like component (C1) was the most depleted at the N medium condition. Fulvic-like (C2) and humic-like (C3) components were more abundant with N rich wastewater. Greater abundances of large size biopolymer (BP) and low molecular weight neutrals (LMWN) were found under the N deficient and N rich conditions, respectively. SMPs from various COD/N exhibited a greater degree on membrane fouling following the order of 100/2 > 100/10 > 100/5. C1 and C2 had close associations with reversible and irreversible fouling, respectively, while the reversible fouling potential of C3 depended on the COD/N ratios. No significant impact of COD/N ratio was observed on the relative contributions of SMP size fractions to either reversible or irreversible fouling potential. However, the COD/N ratios likely altered the BP foulants' composition with greater contribution of proteinaceous substances to reversible fouling under the N deficient condition than at other N richer conditions. The opposite trend was observed for irreversible fouling. Our results provided further insight into changes in different SMP constitutes and their membrane fouling in response to microbial activities under different COD/N ratios. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Audience Perception of Hate Speech and Foul Language in the Social Media in Nigeria: Implications for Morality and Law

    Directory of Open Access Journals (Sweden)

    Terfa T. Alakali

    2017-01-01

    Full Text Available This paper examined the phenomenon of hate speech and foul language on social media platforms in Nigeria, and assessed their moral and legal consequences in the society and to journalism practice. It used both quantitative and qualitative methodology to investigate the phenomenon. In the first place, the paper employed the survey research methodology to sample 384 respondents using questionnaire and focus group discussion as instruments for data collection. Findings from the research indicate that promoting hate speech and foul language on social media have moral and legal consequences in the society and to journalism practice. Findings also show that although, the respondents understand that hate speech and foul language attract legal consequences, they do not know what obligations are created by law against perpetrators of hate speech and foul language in Nigeria. The paper therefore, adopted the qualitative, doctrinal and analytical methodology to discuss the legal consequences and obligations created against perpetrators of hate speech and foul language in Nigeria. The paper concluded based on the findings that hate speech and foul language is prevalent on social media platforms in Nigeria and that there are adequate legal provisions to curb the phenomenon in Nigeria. It recommends among others things that the Nigerian government and NGOs should sponsor monitoring projects like the UMATI in Kenya to better understand the use of hate speech and that monitoring agencies set up under the legal regime should adopt mechanisms to identify and remove hate speech content on social media platforms in Nigeria.

  15. 17th International Conference on Petroleum Phase Behavior and Fouling

    DEFF Research Database (Denmark)

    von Solms, Nicolas; Yan, Wei; Andersen, Simon

    2017-01-01

    This special section of Energy & Fuels contains contributedpapers from the 17th International Conference on PetroleumPhase Behavior and Fouling (Petrophase 2016). Petrophase 2016 was organized by the Technical University of Denmark and Schlumberger and took place in Elsinore (Helsingør) Denmark...... from June 19th to 23rd at the Beach Hotel Marienlyst. Petrophase is an international conference aimed at researchers in industry and academia dedicated to the study of the properties and chemistry of petroleum fluids and their effect on producing, processing, and refining in the upstream, midstream......, and downstream industries. The conference started in 1999 as “The International Conference on Petroleum Phase Behavior & Fouling” and has since evolved into an annual event taking place in countries all around the world. Petrophase has been fortunate to have enjoyed financial and organizational support from many...

  16. Coke fouling monitoring by electrical resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Bombardelli, Clovis; Mari, Livia Assis; Kalinowski, Hypolito Jose [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Eletrica e Informatica Industrial (CPGEI)

    2008-07-01

    An experimental method to simulate the growth of the coke fouling that occurs in the oil processing is proposed relating the thickness of the encrusted coke to its electrical resistivity. The authors suggest the use of the fouling electrical resistivity as a transducer element for determining its thickness. The sensor is basically two electrodes in an electrically isolated device where the inlay can happen in order to compose a purely resistive transducer. Such devices can be easily constructed in a simple and robust form with features capable to face the high temperatures and pressures found in relevant industrial processes. For validation, however, it is needed a relationship between the electrical resistivity and the fouling thickness, information not yet found in the literature. The present work experimentally simulates the growth of a layer of coke on an electrically insulating surface, equipped with electrodes at two extremities to measure the electrical resistivity during thermal cracking essays. The method is realized with a series of consecutive runs. The results correlate the mass of coke deposited and its electrical resistivity, and it can be used to validate the coke depositions monitoring employing the resistivity as a control parameter. (author)

  17. Impact of fouling on UV effectiveness

    International Nuclear Information System (INIS)

    Dykstra, T.S.; Chauret, C.

    2002-01-01

    In recent years ultraviolet light has gained in popularity as an attractive disinfection alternative due to its ability to inactivate bacteria and viruses. UV light has the potential to inactivate Cryptosporidium parvum and Giardia lamblia with a very low potential for the formation of harmful disinfection by-products. Previous studies have reported that particulate material present in the water can act to reduce the exposure of UV light to the receiving waters and that the interference of organic particles can serve to protect bacteria and viruses from intended disinfection. Disinfection capacity can also be reduced by organics in the source water that can accumulate on the surface of quartz sleeves. The purpose of this study was to determine the ability of a medium pressure UV light, at drinking water treatment levels, to inactivate MS 2 bacteriophage after a quartz tube has been fouled with organic rich source water for a 12- week period. To this end the inactivation of MS 2 was determined under clean and fouled conditions, in the presence and absence of humic rich water. The effect of lamp age on inactivation was also investigated. The results suggest that organic fouling of a quartz tube has a significant impact on the disinfection capacity of a medium pressure UV lamp. The presence of organics in the source water also plays a significant role in reducing the capacity of UV for bacterial and viral disinfection. Lamp age also seems to have some effect on the efficiency of UV disinfection. (author)

  18. Nonlinear Methodologies for Identifying Seismic Event and Nuclear Explosion Using Random Forest, Support Vector Machine, and Naive Bayes Classification

    Directory of Open Access Journals (Sweden)

    Longjun Dong

    2014-01-01

    Full Text Available The discrimination of seismic event and nuclear explosion is a complex and nonlinear system. The nonlinear methodologies including Random Forests (RF, Support Vector Machines (SVM, and Naïve Bayes Classifier (NBC were applied to discriminant seismic events. Twenty earthquakes and twenty-seven explosions with nine ratios of the energies contained within predetermined “velocity windows” and calculated distance are used in discriminators. Based on the one out cross-validation, ROC curve, calculated accuracy of training and test samples, and discriminating performances of RF, SVM, and NBC were discussed and compared. The result of RF method clearly shows the best predictive power with a maximum area of 0.975 under the ROC among RF, SVM, and NBC. The discriminant accuracies of RF, SVM, and NBC for test samples are 92.86%, 85.71%, and 92.86%, respectively. It has been demonstrated that the presented RF model can not only identify seismic event automatically with high accuracy, but also can sort the discriminant indicators according to calculated values of weights.

  19. Impact of sludge flocs on membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Christensen, Morten Lykkegaard; Niessen, Wolfgang; Jørgensen, Mads Koustrup

    Membrane bioreactors (MBR) are widely used for wastewater treatment, but membrane fouling reduces membrane performance and thereby increases the cost for membranes and fouling control. Large variation in filtration properties measured as flux decline was observed for the different types of sludges....... Further, the flux could partly be reestablished after the relaxation period depending on the sludge composition. The results underline that sludge properties are important for membrane fouling and that control of floc properties, as determined by the composition of the microbial communities...... and the physico-chemical properties, is an efficient method to reduce membrane fouling in the MBR. High concentration of suspended extracellular substances (EPS) and small particles (up to 10 µm) resulted in pronounced fouling propensity. The membrane fouling resistance was reduced at high concentration...

  20. A comprehensive review of milk fouling on heated surfaces.

    Science.gov (United States)

    Sadeghinezhad, E; Kazi, S N; Dahari, M; Safaei, Mohammad Reza; Sadri, Rad; Badarudin, A

    2015-01-01

    Heat exchanger performance degrades rapidly during operation due to formation of deposits on heat transfer surfaces which ultimately reduces service life of the equipment. Due to scaling, product deteriorates which causes lack of proper heating. Chemistry of milk scaling is qualitatively understood and the mathematical models for fouling at low temperatures have been produced but the behavior of systems at ultra high temperature processing has to be studied further to understand in depth. In diversified field, the effect of whey protein fouling along with pressure drop in heat exchangers were conducted by many researchers. Adding additives, treatment of heat exchanger surfaces and changing of heat exchanger configurations are notable areas of investigation in milk fouling. The present review highlighted information about previous work on fouling, influencing parameters of fouling and its mitigation approach and ends up with recommendations for retardation of milk fouling and necessary measures to perform the task.

  1. Corrosion and fouling concerns of service water piping and heat exchanger components

    International Nuclear Information System (INIS)

    Witt, F.J.

    1991-01-01

    In this paper, the author would like to discuss NRC generic communications issued to all operating nuclear power plants for service water systems relative to corrosion (including microbiologically influenced corrosion (MIC) and typical operational events involving system failure and degradations as a result of corrosion and fouling. Lessons can be learned from the unforeseen experience of others, and knowing and understanding these experiences can improve the performance of safety-related service water systems

  2. Very Low Surface Energy (Membrane Separations: An Integrated Polymer Chemistry/Engineering Approach and The Influence of Backpulsing on Fouling Properties of Novel Nanofiltration Membranes for Wastewater Remediation

    National Research Council Canada - National Science Library

    Freeman, Benny

    1998-01-01

    ...: An Integrated Polymer Chemistry/Engineering Approach, is to explore several new classes of polymeric materials to identify promising routes for developing low-fouling nanofiltration membranes for wastewater remediation...

  3. Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

    Directory of Open Access Journals (Sweden)

    Mourad Laqbaqbi

    2017-03-01

    Full Text Available Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD, osmotic distillation (OD and osmotic membrane distillation (OMD use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED, membrane capacitive deionization (MCD, reverse osmosis (RO, nanofiltration (NF, ultrafiltration (UF, microfiltration (MF, etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling, fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

  4. NOM and TEP fouling of a forward osmosis (FO) membrane: Foulant identification and cleaning

    KAUST Repository

    Valladares Linares, Rodrigo; Yangali-Quintanilla, Victor; Li, Zhenyu; Amy, Gary L.

    2012-01-01

    The study of forward osmosis (FO) membranes has increased due to the already demonstrated advantages compared to high-energy membrane processes such as reverse osmosis (RO). This research focuses on characterization of the natural organic matter (NOM) fraction causing fouling on the active layer (AL) of a FO membrane in a novel plate and frame module configuration, facing secondary wastewater effluent as a feed solution (FS) and seawater used as a draw solution (DS). In addition, transparent exopolymer particles (TEP) were observed on the support layer (SL) of the membrane in contact with the DS. The NOM fouling layer, after characterizing the water samples and membranes used, was found to be composed of biopolymers and protein-like substances, which adversely affect the flux of water through the FO membrane. However, NOM fouling showed high reversibility, up to 90% when air scouring for 15. min is used as a cleaning technique. The irreversible fouling in this work was found to be 8.2% after chemical cleaning. On the support layer of the membrane, TEP formed clusters clearly identifiable with an optical microscope and a TEP-specific dye. Chemical cleaning with 1% NaOCl for 10. min proved to be the most effective method to remove TEP. © 2012.

  5. Membrane Fouling Potential of Secondary Effluent Organic Matter (EfOM) from Conventional Activated Sludge Process

    KAUST Repository

    Wei, Chunhai; Amy, Gary L.

    2012-01-01

    Secondary effluent organic matter (EfOM) from a conventional activated sludge process was filtered through constant-pressure dead-end filtration tests with a sequential ultrafiltration (UF, molecular weight cut-off (MWCO) of 10k Dalton) and nanofiltration (NF, MWCO of 200 Dalton) array to investigate its membrane fouling potential. Advanced analytical methods including liquid chromatography with online carbon detection (LC-OCD) and fluorescent excitation-emission matrix (F-EEM) were employed for EfOM characterization. EfOM consisted of humic substances and building blocks, low molecular weight (LMW) neutrals, biopolymers (mainly proteins) and hydrophobic organics according to the sequence of their organic carbon fractions. The UF rejected only biopolymers and the NF rejected most humics and building blocks and a significant part of LMW neutrals. Simultaneous occurrence of cake layer and standard blocking during the filtration process of both UF and NF was identified according to constant-pressure filtration equations, which was possibly caused by the heterogeneous nature of EfOM with a wide MW distribution (several ten to several million Dalton). Thus the corresponding two fouling indices (kc for cake layer and ks for standard blocking) from UF and NF could characterize the fouling potential of macromolecular biopolymers and low to intermediate MW organics (including humics, building blocks, LMW neutrals), respectively. Compared with macromolecular biopolymers, low to intermediate MW organics exhibited a much higher fouling potential due to their lower molecular weight and higher concentration.

  6. NOM and TEP fouling of a forward osmosis (FO) membrane: Foulant identification and cleaning

    KAUST Repository

    Valladares Linares, Rodrigo

    2012-12-01

    The study of forward osmosis (FO) membranes has increased due to the already demonstrated advantages compared to high-energy membrane processes such as reverse osmosis (RO). This research focuses on characterization of the natural organic matter (NOM) fraction causing fouling on the active layer (AL) of a FO membrane in a novel plate and frame module configuration, facing secondary wastewater effluent as a feed solution (FS) and seawater used as a draw solution (DS). In addition, transparent exopolymer particles (TEP) were observed on the support layer (SL) of the membrane in contact with the DS. The NOM fouling layer, after characterizing the water samples and membranes used, was found to be composed of biopolymers and protein-like substances, which adversely affect the flux of water through the FO membrane. However, NOM fouling showed high reversibility, up to 90% when air scouring for 15. min is used as a cleaning technique. The irreversible fouling in this work was found to be 8.2% after chemical cleaning. On the support layer of the membrane, TEP formed clusters clearly identifiable with an optical microscope and a TEP-specific dye. Chemical cleaning with 1% NaOCl for 10. min proved to be the most effective method to remove TEP. © 2012.

  7. Membrane morphology and topology for fouling control in Reverse Osmosis filtration systems

    Science.gov (United States)

    Ling, Bowen; Battiato, Ilenia

    2017-11-01

    Reverse Osmosis Membrane (ROM) filtration systems are widely utilized in waste-water recovery, seawater desalination, landfill water treatment, etc. During filtration, the system performance is dramatically affected by membrane fouling which causes a significant decrease in permeate flux as well as an increase in the energy input required to operate the system. Design and optimization of ROM filtration systems aim at reducing membrane fouling by studying the coupling between membrane structure, local flow field and foulant adsorption patterns. Yet, current studies focus exclusively on oversimplified steady-state models that ignore any dynamic coupling between fluid flow and transport through the membrane. In this work, we develop a customized solver (SUMembraneFoam) under OpenFOAM to solve the transient equations. The simulation results not only predict macroscopic quantities (e.g. permeate flux, pressure drop, etc.) but also show an excellent agreement with the fouling patterns observed in experiments. It is observed that foulant deposition is strongly controlled by the local shear stress on the membrane, and channel morphology or membrane topology can be modified to control the shear stress distribution and reduce fouling. Finally, we identify optimal regimes for design.

  8. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran

    2015-05-06

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  9. Hydraulically irreversible fouling on ceramic MF/UF membranes: comparison of fouling indices, foulant composition and irreversible pore narrowing

    KAUST Repository

    Shang, Ran; Vuong, Francois; Hu, Jingyi; Li, Sheng; Kemperman, Antoine J.B.; Nijmeijer, Kitty; Cornelissen, Emile R.; Heijman, Sebastiaan G.J.; Rietveld, Luuk C.

    2015-01-01

    The application of ceramic membranes in water treatment is becoming increasing attractive because of their long life time and excellent chemical, mechanical and thermal stability. However, fouling of ceramic membranes, especially hydraulically irreversible fouling, is still a critical aspect affecting the operational cost and energy consumption in water treatment plants. In this study, four ceramic membranes with pore sizes or molecular weight cut-off (MWCO) of 0.20 μm, 0.14 μm, 300 kDa and 50 kDa were compared during natural surface water filtration with respect to hydraulically irreversible fouling index (HIFI), foulant composition and narrowing of pore size due to the irreversible fouling. Our results showed that the hydraulically irreversible fouling index (HIFI) was proportional to the membrane pore size (r2=0.89) when the same feed water was filtrated. The UF membranes showed lower HIFI values than the MF membranes. Pore narrowing (internal fouling) was found to be a main fouling pattern of the hydraulically irreversible fouling. The internal fouling was caused by monolayer adsorption of foulants with different sizes that is dependent on the size of the membrane pore.

  10. An unmet challenge: consideration of heavy fouling in severe accident analyses

    Energy Technology Data Exchange (ETDEWEB)

    Robert H Leyse [CEO Inz, Inc., PO BOX 2850, Sun Valley, ID 83353 (United States)

    2005-07-01

    Full text of publication follows: The impact of heavy fouling of fuel elements in light water cooled and moderated nuclear reactors has not been considered in the analysis of severe accidents such as Reactivity Insertion Accidents and Loss of Coolant Accidents. This is the case even though operation of nuclear power reactors with significant fouling deposits is commonplace. Fouling deposits have substantial thermal resistance. This has led to fuel element failures in several instances as the zirconium alloy cladding has failed due to high temperature corrosion. Although the details of current fouling have not been disclosed, in one case the deposits have been described as, 'unusually heavy' which induced the corrosion by thermally insulating the fuel rods' and 'rods that failed had heavy crud with clumpy formations'. Such heavy clumpy fouling is complex with substantial thermal resistance. Relatively straightforward fouling at the Experimental Boiling Water Reactor was classified in terms of the thickness and the thermal conductivity.7 Thickness of the fouling was 0.013 cm, the thermal conductivity was 0.008 W/cm-C; thus the heat transfer coefficient was 0.6 W/(cm{sup 2})(C). The peak heat flux in today's large light water reactors is in the range of 150 W/cm{sup 2} and the temperature gradient for EBWR-type fouling would be 250 C. However, the effective heat transfer coefficient of the heavy, clumpy fouling in today's reactors is likely substantially less than the EBWR case. Clearly, the heat transfer characteristics are vastly degraded in contrast to clean as-built cores. The challenge for the licensees of nuclear power reactors is to produce thorough evaluations of the impact of heavy fouling on severe accidents. The findings are needed for the accurate licensing of water-cooled nuclear reactors. The United States Nuclear Regulatory Commission has evaluated two related Petitions for Rulemaking that have been initiated by the

  11. An unmet challenge: consideration of heavy fouling in severe accident analyses

    International Nuclear Information System (INIS)

    Robert H Leyse

    2005-01-01

    Full text of publication follows: The impact of heavy fouling of fuel elements in light water cooled and moderated nuclear reactors has not been considered in the analysis of severe accidents such as Reactivity Insertion Accidents and Loss of Coolant Accidents. This is the case even though operation of nuclear power reactors with significant fouling deposits is commonplace. Fouling deposits have substantial thermal resistance. This has led to fuel element failures in several instances as the zirconium alloy cladding has failed due to high temperature corrosion. Although the details of current fouling have not been disclosed, in one case the deposits have been described as, 'unusually heavy' which induced the corrosion by thermally insulating the fuel rods' and 'rods that failed had heavy crud with clumpy formations'. Such heavy clumpy fouling is complex with substantial thermal resistance. Relatively straightforward fouling at the Experimental Boiling Water Reactor was classified in terms of the thickness and the thermal conductivity.7 Thickness of the fouling was 0.013 cm, the thermal conductivity was 0.008 W/cm-C; thus the heat transfer coefficient was 0.6 W/(cm 2 )(C). The peak heat flux in today's large light water reactors is in the range of 150 W/cm 2 and the temperature gradient for EBWR-type fouling would be 250 C. However, the effective heat transfer coefficient of the heavy, clumpy fouling in today's reactors is likely substantially less than the EBWR case. Clearly, the heat transfer characteristics are vastly degraded in contrast to clean as-built cores. The challenge for the licensees of nuclear power reactors is to produce thorough evaluations of the impact of heavy fouling on severe accidents. The findings are needed for the accurate licensing of water-cooled nuclear reactors. The United States Nuclear Regulatory Commission has evaluated two related Petitions for Rulemaking that have been initiated by the author regarding these matters. Currently the

  12. Foul or dive? Motor contributions to judging ambiguous foul situations in football

    NARCIS (Netherlands)

    Renden, P.G.; Kerstens, S.; Oudejans, R.R.D.; Canal Bruland, R.

    2014-01-01

    Football (soccer) referees frequently face situations in which they have to distinguish dives and fouls. Yet, little is known about the contributing factors that characterise the ability to judge these ambiguous situations correctly. To this end, in the current article we tested the hypothesis that

  13. Global mapping of protein phosphorylation events identifies novel signalling hubs mediating fatty acid starvation responses in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Pultz, Dennis; Bennetzen, Martin; Rødkær, Steven Vestergaard

    2011-01-01

    Dietary restriction (DR) extends the life span of multiple species, ranging from single-celled organisms like yeast to mammals. This increase in longevity by dietary restriction is coupled to profound beneficial effects on age-related pathology. Despite the number of studies on DR...... and the physiological changes DR induces, only little is known about the genetics and signalling networks, which regulate the DR response. We have recently shown that inhibition of fatty acid synthesis in Saccharomyces cerevisiae induces autophagy mediated by TORC1 signalling and affects life span. In the present study...... in a temporal manner in response to inhibition of fatty acid synthesis by cerulenin. By in silico analysis of these phosphorylation events, we have identified the major downstream regulated processes and signalling networks mediating the cellular response to fatty acid starvation. The analysis further...

  14. A study on development of a plugging margin evaluation method taking into account the fouling of shell-and tube heat exchangers

    International Nuclear Information System (INIS)

    Hwang, Kyeong Mo; Jin, Tae Eun; Kim, Kyung Hoon

    2006-01-01

    As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a Korean nuclear power plant

  15. Development of an online morbidity, mortality, and near-miss reporting system to identify patterns of adverse events in surgical patients.

    Science.gov (United States)

    Bilimoria, Karl Y; Kmiecik, Thomas E; DaRosa, Debra A; Halverson, Amy; Eskandari, Mark K; Bell, Richard H; Soper, Nathaniel J; Wayne, Jeffrey D

    2009-04-01

    To design a Web-based system to track adverse and near-miss events, to establish an automated method to identify patterns of events, and to assess the adverse event reporting behavior of physicians. A Web-based system was designed to collect physician-reported adverse events including weekly Morbidity and Mortality (M&M) entries and anonymous adverse/near-miss events. An automated system was set up to help identify event patterns. Adverse event frequency was compared with hospital databases to assess reporting completeness. A metropolitan tertiary care center. Identification of adverse event patterns and completeness of reporting. From September 2005 to August 2007, 15,524 surgical patients were reported including 957 (6.2%) adverse events and 34 (0.2%) anonymous reports. The automated pattern recognition system helped identify 4 event patterns from M&M reports and 3 patterns from anonymous/near-miss reporting. After multidisciplinary meetings and expert reviews, the patterns were addressed with educational initiatives, correction of systems issues, and/or intensive quality monitoring. Only 25% of complications and 42% of inpatient deaths were reported. A total of 75.2% of adverse events resulting in permanent disability or death were attributed to the nature of the disease. Interventions to improve reporting were largely unsuccessful. We have developed a user-friendly Web-based system to track complications and identify patterns of adverse events. Underreporting of adverse events and attributing the complication to the nature of the disease represent a problem in reporting culture among surgeons at our institution. Similar systems should be used by surgery departments, particularly those affiliated with teaching hospitals, to identify quality improvement opportunities.

  16. Use of satellite imagery to identify vegetation cover changes following the Waldo Canyon Fire event, Colorado, 2012-2013

    Science.gov (United States)

    Cole, Christopher J.; Friesen, Beverly A.; Wilson, Earl M.

    2014-01-01

    The Waldo Canyon Fire of 2012 was one of the most destructive wildfire events in Colorado history. The fire burned a total of 18,247 acres, claimed 2 lives, and destroyed 347 homes. The Waldo Canyon Fire continues to pose challenges to nearby communities. In a preliminary emergency assessment conducted in 2012, the U.S. Geological Survey (USGS) concluded that drainage basins within and near the area affected by the Waldo Canyon Fire pose a risk for future debris flow events. Rainfall over burned, formerly vegetated surfaces resulted in multiple flood and debris flow events that affected the cities of Colorado Springs and Manitou Springs in 2013. One fatality resulted from a mudslide near Manitou Springs in August 2013. Federal, State, and local governments continue to monitor these hazards and other post-fire effects, along with the region’s ecological recovery. At the request of the Colorado Springs Office of Emergency Management, the USGS Special Applications Science Center developed a geospatial product to identify vegetation cover changes following the 2012 Waldo Canyon Fire event. Vegetation cover was derived from July 2012 WorldView-2 and September 2013 QuickBird multispectral imagery at a spatial resolution of two meters. The 2012 image was collected after the fire had reached its maximum extent. Per-pixel increases and decreases in vegetation cover were identified by measuring spectral changes that occurred between the 2012 and 2013 image dates. A Normalized Difference Vegetation Index (NDVI), and Green-Near Infrared Index (GRNIR) were computed from each image. These spectral indices are commonly used to characterize vegetation cover and health condition, due to their sensitivity to detect foliar chlorophyll content. Vector polygons identifying surface-cover feature boundaries were derived from the 2013 imagery using image segmentation software. This geographic software groups similar image pixels into vector objects based upon their spatial and spectral

  17. Dynamic coating of mf/uf membranes for fouling mitigation

    KAUST Repository

    Tabatabai, S. Assiyeh Alizadeh; Leiknes, TorOve

    2017-01-01

    A membrane system including an anti-fouling layer and a method of applying an anti-fouling layer to a membrane surface are provided. In an embodiment, the surface is a microfiltration (MF) or an ultrafiltration (UF) membrane surface. The anti

  18. Fouling detection in heat exchangers by Takagi-Sugeno observers

    International Nuclear Information System (INIS)

    Delrot, Sabrina

    2012-01-01

    The phenomenon of fouling in heat exchangers is currently an important topic. Indeed, the fouling is a costly issue that increases the energy loss (directly or indirectly through an over-sizing of the equipment), and therefore increases the water consumption. As a side effect, fouling increases CO 2 consumption that leads to environmental consequences. Fouling can be detected either on local scale, using expensive and specific sensors or on global scale. Global estimation of fouling can be done by measuring the variation of the mass of the exchanger, or by estimating the efficiency of the exchanger through the transfer coefficient. These two methods require very restricting conditions: a powered exchanger to measure mass variation and a steady state exchanger to estimate the efficiency. The work introduced in this thesis deals with the development of non-linear observers that detect fouling early enough to start an efficient cleaning process. As a beginning, a finite element model of a counter current tubular exchanger was proposed. Then three approaches, based on non-linear Takagi-Sugeno observers, were suggested to detect early fouling in heat exchangers. First approach consisted in a set of observers that estimated the parameters of fouling effect through an interpolation method. The second approach proposed a polynomial Takagi-Sugeno observer, using the theory of sums of squares. Finally, a observer of Takagi-Sugeno type with unknown inputs was developed. As a conclusion, a comparison between those different methods was done. (author)

  19. Membrane fouling mechanism transition in relation to feed water composition

    KAUST Repository

    Myat, Darli Theint; Mergen, Max R D; Zhao, Oliver; Stewart, Matthew B.; Orbell, John D.; Merle, Tony; Croue, Jean-Philippe; Gray, Stephen R.

    2014-01-01

    on hydrophobic PP membrane occurred during the first 24h of filtration and contributed to fouling for both raw wastewater and pre-treated wastewaters. However, after the first 24h of filtration the contribution of humic substances to fouling diminished

  20. Trophic structure of the fouling community in Odessa Bay (Black Sea

    Directory of Open Access Journals (Sweden)

    A. Y. Varigin

    2016-06-01

    Full Text Available The trophic structure of the coastal fouling community of Odessa Bay (Black Sea, which was composed of 10 species of macrophytes, 57 invertebrate species and 4 species of fish, was determined. The basic trophic relationship between organisms composing the community is shown. A minimization of interspecific trophic competition within the community is noted. The main sources of food material entering the fouling community were determined. We show that a significant proportion of food in the form of detritus, dissolved organic matter and small planktonic organisms enters the community from the water column. Filtration and pumping activity of sestonophage-organisms, particularly mussels, helps to attract food material to the community. Primary producers of the community are macrophytes and microphytes, which develop on account of their photosynthetic activity and ensure the provision of food to herbivores. The trophic group of detritophages consumes different fractions of the detritus which accumulates in the byssus threads of bivalve molluscs. In this context, mussel druses act as sediment traps, collecting detritus. Numerous polyphages, which are essentially omnivores and do not usually lack food material, were noted in the community. A small group of carnivorous invertebrates, whose representatives actively attack small animals, was identified. The abundance of these species in the community was about 1%, and their biomass less than 0.6%. Fish living in macrophyte weeds are the consumers in the community. We determined that the highest relative abundance (over 36% in the fouling community was reached by sestonophages and polyphages. We found that the undisputed leader in the relative biomass (over 97% in the fouling community ofOdessaBaywas the sestonophages (mainly composed of mussels. We determined that the trophic structure index of the community was 0.94, which confirms the significant dominance in biomass of bivalves over other species in

  1. FLUX ENHANCEMENT IN CROSSFLOW MEMBRANE FILTRATION: FOULING AND IT'S MINIMIZATION BY FLOW REVERSAL

    International Nuclear Information System (INIS)

    Shamsuddin Ilias

    2005-01-01

    Fouling problems are perhaps the single most important reason for relatively slow acceptance of ultrafiltration in many areas of chemical and biological processing. To overcome the losses in permeate flux associated with concentration polarization and fouling in cross flow membrane filtration, we investigated the concept of flow reversal as a method to enhance membrane flux in ultrafiltration. Conceptually, flow reversal prevents the formation of stable hydrodynamic and concentration boundary layers at or near the membrane surface. Further more, periodic reversal of the flow direction of the feed stream at the membrane surface results in prevention and mitigation of membrane fouling. Consequently, these advantages are expected to enhance membrane flux significantly. A crossflow membrane filtration unit was designed and built to test the concept of periodic flow reversal for flux enhancement. The essential elements of the system include a crossflow hollow fiber membrane module integrated with a two-way valve to direct the feed flow directions. The two-way valve is controlled by a controller-timer for periodic reversal of flow of feed stream. Another important feature of the system is that with changing feed flow direction, the permeate flow direction is also changed to maintain countercurrent feed and permeate flows for enhanced mass transfer driving force (concentration difference). In this report, we report our application of Flow Reversal technique in clarification of apple juice containing pectin. The presence of pectin in apple juice makes the clarification process difficult and is believed to cause membrane fouling. Of all compounds found in apple juice, pectin is most often identified as the major hindrance to filtration performance. Based on our ultrafiltration experiments with apple juice, we conclude that under flow reversal conditions, the permeate flux is significantly enhanced when compared with the conventional unidirectional flow. Thus, flow reversal

  2. Identifying cognitive preferences for attractive female faces: an event-related potential experiment using a study-test paradigm.

    Science.gov (United States)

    Zhang, Yan; Kong, Fanchang; Chen, Hong; Jackson, Todd; Han, Li; Meng, Jing; Yang, Zhou; Gao, Jianguo; Najam ul Hasan, Abbasi

    2011-11-01

    In this experiment, sensitivity to female facial attractiveness was examined by comparing event-related potentials (ERPs) in response to attractive and unattractive female faces within a study-test paradigm. Fourteen heterosexual participants (age range 18-24 years, mean age 21.67 years) were required to judge 84 attractive and 84 unattractive face images as either "attractive" or "unattractive." They were then asked whether they had previously viewed each face in a recognition task in which 50% of the images were novel. Analyses indicated that attractive faces elicited more enhanced ERP amplitudes than did unattractive faces in judgment (N300 and P350-550 msec) and recognition (P160 and N250-400 msec and P400-700 msec) tasks on anterior locations. Moreover, longer reaction times and higher accuracy rate were observed in identifying attractive faces than unattractive faces. In sum, this research identified neural and behavioral bases related to cognitive preferences for judging and recognizing attractive female faces. Explanations for the results are that attractive female faces arouse more intense positive emotions in participants than do unattractive faces, and they also represent reproductive fitness and mating value from the evolutionary perspective. Copyright © 2011 Wiley-Liss, Inc.

  3. Retroviral insertional mutagenesis identifies Zeb2 activation as a novel leukemogenic collaborating event in CALM-AF10 transgenic mice.

    Science.gov (United States)

    Caudell, David; Harper, David P; Novak, Rachel L; Pierce, Rachel M; Slape, Christopher; Wolff, Linda; Aplan, Peter D

    2010-02-11

    The t(10;11) translocation results in a CALM-AF10 fusion gene in a subset of leukemia patients. Expression of a CALM-AF10 transgene results in leukemia, with prolonged latency and incomplete penetrance, suggesting that additional events are necessary for leukemic transformation. CALM-AF10 mice infected with the MOL4070LTR retrovirus developed acute leukemia, and ligation-mediated polymerase chain reaction was used to identify retroviral insertions at 19 common insertion sites, including Zeb2, Nf1, Mn1, Evi1, Ift57, Mpl, Plag1, Kras, Erg, Vav1, and Gata1. A total of 26% (11 of 42) of the mice had retroviral integrations near Zeb2, a transcriptional corepressor leading to overexpression of the Zeb2-transcript. A total of 91% (10 of 11) of mice with Zeb2 insertions developed B-lineage acute lymphoblastic leukemia, suggesting that Zeb2 activation promotes the transformation of CALM-AF10 hematopoietic precursors toward B-lineage leukemias. More than half of the mice with Zeb2 integrations also had Nf1 integrations, suggesting cooperativity among CALM-AF10, Zeb2, and Ras pathway mutations. We searched for Nras, Kras, and Ptpn11 point mutations in the CALM-AF10 leukemic mice. Three mutations were identified, all of which occurred in mice with Zeb2 integrations, consistent with the hypothesis that Zeb2 and Ras pathway activation promotes B-lineage leukemic transformation in concert with CALM-AF10.

  4. Knowledge based system for fouling assessment of power plant boiler

    International Nuclear Information System (INIS)

    Afgan, N.H.; He, X.; Carvalho, M.G.; Azevedo, J.L.T.

    1999-01-01

    The paper presents the design of an expert system for fouling assessment in power plant boilers. It is an on-line expert system based on selected criteria for the fouling assessment. Using criteria for fouling assessment based on 'clean' and 'not-clean' radiation heat flux measurements, the diagnostic variable are defined for the boiler heat transfer surface. The development of the prototype knowledge-based system for fouling assessment in power plants boiler comprise the integrations of the elements including knowledge base, inference procedure and prototype configuration. Demonstration of the prototype knowledge-based system for fouling assessment was performed on the Sines power plant. It is a 300 MW coal fired power plant. 12 fields are used with 3 on each side of boiler

  5. Filtration Behaviour and Fouling Mechanisms of Polysaccharides

    Directory of Open Access Journals (Sweden)

    Sondus Jamal

    2014-07-01

    Full Text Available This study investigated filtration behaviors of polysaccharides solutions, both alone and in mixture with proteins, in the short-time constant flux filtration with the focus on factors affecting the transmembrane pressure (TMP increase rate, the irreversible filtration resistance, and the membrane rejection behavior. The results showed that the TMP increase rates in the short-time constant flux filtration of alginate solutions were significantly affected by the calcium addition, alginate concentration, and flux. Although the addition of calcium resulted in a decrease in the TMP increase rate, it was found that the irreversible fouling developed during the filtration increased with the calcium addition, implying that the double-sided effect of calcium on membrane filtration and that the TMP increase rate observed in the filtration does not always reflect the irreversible membrane fouling development. It was also found that for the filtration of solutions containing mixed alginate and BSA, alginate exerted a dominant effect on the TMP increase rate and the membrane exhibited a reduced rejection to both alginate and BSA molecules compared to that in the filtration of the pure alginate or BSA.

  6. Genome characterization of Turkey Rotavirus G strains from the United States identifies potential recombination events with human Rotavirus B strains.

    Science.gov (United States)

    Chen, Fangzhou; Knutson, Todd P; Porter, Robert E; Ciarlet, Max; Mor, Sunil Kumar; Marthaler, Douglas G

    2017-12-01

    Rotavirus G (RVG) strains have been detected in a variety of avian species, but RVG genomes have been published from only a single pigeon and two chicken strains. Two turkey RVG strains were identified and characterized, one in a hatchery with no reported health issues and the other in a hatchery with high embryo/poult mortality. The two turkey RVG strains shared only an 85.3 % nucleotide sequence identity in the VP7 gene while the other genes possessed high nucleotide identity among them (96.3-99.9 %). Low nucleotide percentage identities (31.6-87.3 %) occurred among the pigeon and chicken RVG strains. Interestingly, potential recombination events were detected between our RVG strains and a human RVB strain, in the VP6 and NSP3 segments. The epidemiology of RVG in avian flocks and the pathogenicity of the two different RVG strains should be further investigated to understand the ecology and impact of RVG in commercial poultry flocks.

  7. Predictive values of diagnostic codes for identifying serious hypocalcemia and dermatologic adverse events among women with postmenopausal osteoporosis in a commercial health plan database.

    Science.gov (United States)

    Wang, Florence T; Xue, Fei; Ding, Yan; Ng, Eva; Critchlow, Cathy W; Dore, David D

    2018-04-10

    Post-marketing safety studies of medicines often rely on administrative claims databases to identify adverse outcomes following drug exposure. Valid ascertainment of outcomes is essential for accurate results. We aim to quantify the validity of diagnostic codes for serious hypocalcemia and dermatologic adverse events from insurance claims data among women with postmenopausal osteoporosis (PMO). We identified potential cases of serious hypocalcemia and dermatologic events through ICD-9 diagnosis codes among women with PMO within claims from a large US healthcare insurer (June 2005-May 2010). A physician adjudicated potential hypocalcemic and dermatologic events identified from the primary position on emergency department (ED) or inpatient claims through medical record review. Positive predictive values (PPVs) and 95% confidence intervals (CIs) quantified the fraction of potential cases that were confirmed. Among 165,729 patients with PMO, medical charts were obtained for 40 of 55 (73%) potential hypocalcemia cases; 16 were confirmed (PPV 40%, 95% CI 25-57%). The PPV was higher for ED than inpatient claims (82 vs. 24%). Among 265 potential dermatologic events (primarily urticaria or rash), we obtained 184 (69%) charts and confirmed 128 (PPV 70%, 95% CI 62-76%). The PPV was higher for ED than inpatient claims (77 vs. 39%). Diagnostic codes for hypocalcemia and dermatologic events may be sufficient to identify events giving rise to emergency care, but are less accurate for identifying events within hospitalizations.

  8. Direct and indirect costs for adverse drug events identified in medical records across care levels, and their distribution among payers.

    Science.gov (United States)

    Natanaelsson, Jennie; Hakkarainen, Katja M; Hägg, Staffan; Andersson Sundell, Karolina; Petzold, Max; Rehnberg, Clas; Jönsson, Anna K; Gyllensten, Hanna

    2017-11-01

    Adverse drug events (ADEs) cause considerable costs in hospitals. However, little is known about costs caused by ADEs outside hospitals, effects on productivity, and how the costs are distributed among payers. To describe the direct and indirect costs caused by ADEs, and their distribution among payers. Furthermore, to describe the distribution of patient out-of-pocket costs and lost productivity caused by ADEs according to socio-economic characteristics. In a random sample of 5025 adults in a Swedish county, prevalence-based costs for ADEs were calculated. Two different methods were used: 1) based on resource use judged to be caused by ADEs, and 2) as costs attributable to ADEs by comparing costs among individuals with ADEs to costs among matched controls. Payers of costs caused by ADEs were identified in medical records among those with ADEs (n = 596), and costs caused to individual patients were described by socio-economic characteristics. Costs for resource use caused by ADEs were €505 per patient with ADEs (95% confidence interval €345-665), of which 38% were indirect costs. Compared to matched controls, the costs attributable to ADEs were €1631, of which €410 were indirect costs. The local health authorities paid 58% of the costs caused by ADEs. Women had higher productivity loss than men (€426 vs. €109, p = 0.018). Out-of-pocket costs displaced a larger proportion of the disposable income among low-income earners than higher income earners (0.7% vs. 0.2%-0.3%). We used two methods to identify costs for ADEs, both identifying indirect costs as an important component of the overall costs for ADEs. Although the largest payers of costs caused by ADEs were the local health authorities responsible for direct costs, employers and patients costs for lost productivity contributed substantially. Our results indicate inequalities in costs caused by ADEs, by sex and income. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thérien-Aubin, Héloïse

    2011-11-01

    A major problem to be addressed with thin composite films used in processes such as coatings or water purification is the biofouling of the surface. To address this problem in a model system, functionalized polyaramide membranes containing an atom transfer radical polymerization (ATRP) initiator were synthesized as a versatile approach to easily modify the surface properties of the polyaramide. Poly(methacrylic acid) brushes were grown using surface initiated ATRP followed by the functionalization of the poly(methacrylic acid) brushes with different side-chains chosen to reduce adhesion between the membrane and foulant. The relation between membrane fouling and the physicochemical properties of the surface was investigated in detail. © 2011 Elsevier Ltd. All rights reserved.

  10. Microbial fouling control in heat exchangers

    International Nuclear Information System (INIS)

    McCoy, W.F.

    1991-01-01

    Biofilm formation in turbulent flow has been studied a great deal during the last 15 years. Such studies have provided the basis for further experiments designed to test the efficacy of industrial antimicrobials against biofilms in laboratory models and in actual real-world industrial water-treatment programs. Biofilm microbiology is relevant from the industrial perspective because adherent populations of microorganisms often cause an economic impact on industrial processes. For example, it is the adherent population of microorganisms in cooling-water systems that can eventually contribute to significant heat transfer and fluid frictional resistances. The microbiology of biofilms in heat exchangers can be related to the performance of industrial antimicrobials. The development of fouling biofilms and methods to quantitatively observe the effect of biofouling control agents are discussed in this paper

  11. Fouling-resistant polymer brush coatings

    KAUST Repository

    Thé rien-Aubin, Hé loï se; Chen, Lin; Ober, Christopher K.

    2011-01-01

    A major problem to be addressed with thin composite films used in processes such as coatings or water purification is the biofouling of the surface. To address this problem in a model system, functionalized polyaramide membranes containing an atom transfer radical polymerization (ATRP) initiator were synthesized as a versatile approach to easily modify the surface properties of the polyaramide. Poly(methacrylic acid) brushes were grown using surface initiated ATRP followed by the functionalization of the poly(methacrylic acid) brushes with different side-chains chosen to reduce adhesion between the membrane and foulant. The relation between membrane fouling and the physicochemical properties of the surface was investigated in detail. © 2011 Elsevier Ltd. All rights reserved.

  12. Effect of surface fouling on the output of PV panels

    Science.gov (United States)

    Zhang, Zele

    2018-04-01

    Surface fouling on the photovoltaic system caused by the output of a certain impact, therefore, it is very important to explore the effect of fouling on its contribution. Through the use of photovoltaic panels to collect Baoding area under different weather output data, and the collected data for comparative analysis, obtained under different environments on the impact of its contribution. It is concluded that the output of the photovoltaic cells will decrease, and the power drop rate will stabilize after three or four days. The effect of fouling on the fog haze and low temperature is more obvious.

  13. Experimental study on fouling in the heat exchangers of surface water heat pumps

    International Nuclear Information System (INIS)

    Bai, Xuelian; Luo, Te; Cheng, Kehui; Chai, Feng

    2014-01-01

    Fouling in the heat exchangers plays a key role on the performance of surface water heat pumps. It is also the basement for the system design criteria and operation energy efficiency. In this paper, experimental measurements are performed both in the field and the laboratory with different water qualities, temperatures and velocities. The research will focus on the dynamic growth characteristics of fouling and its main components. By studying the variation rules of fouling resistance, the fouling resistance allowance for certain water condition is recommended. Furthermore, a fouling prediction model in surface water heat pump will be developed and validated based on elaborating with fouling principle under specified water conditions. - Highlights: • Field and laboratory experiments are taken to measure the fouling variation. • Fouling growth process can be divided into four stages. • We recommend fouling resistance allowances for certain conditions. • A fouling prdiction model is developed and validated

  14. CONCENTRIC TUBE-FOULING RIG FOR INVESTIGATION OF FOULING DEPOSIT FORMATION FROM PASTEURISER OF VISCOUS FOOD LIQUID

    Directory of Open Access Journals (Sweden)

    N. I. KHALID

    2013-02-01

    Full Text Available This paper reports the work on developing concentric tube-fouling rig, a new fouling deposit monitoring device. This device can detect and quantify the level of fouling deposit formation. It can also functioning as sampler for fouling deposit study, which can be attached at any food processing equipment. The design is initiated with conceptual design. The rig is designed with inner diameter of 7 cm and with tube length of 37 cm. A spiral insert with 34.5 cm length and with 5.4 cm diameter is fitted inside the tube to ensure the fluid flows around the tube. In this work, the rig is attached to the lab-scale concentric tube-pasteurizer to test its effectiveness and to collect a fouling sample after pasteurization of pink guava puree. Temperature changes are recorded during the pasteurization and the data is used to plot the heat transfer profile. Thickness of the fouling deposit is also measured. The trends for thickness, heat resistance profile and heat transfer profile for concentric tube-fouling rig matched the trends obtained from lab-scale concentric tube-pasteurizer very well. The findings from this work have shown a good potential of this rig however there is a limitation with spiral insert, which is discussed in this paper.

  15. Energy dependence of identified hadron spectra and event-by-event fluctuations in p+p interactions from NA61/SHINE at the CERN SPS

    CERN Document Server

    Rybczynski, Maciej; Aduszkiewicz, A.; Ali, Y.; Anticic, T.; Antoniou, N.; Argyriades, J.; Baatar, B.; Blondel, A.; Blumer, J.; Bogomilov, M.; Bravar, A.; Brooks, W.; Brzychczyk, J.; Bubak, A.; Bunyatov, S.A.; Busygina, O.; Christakoglou, P.; Czopowicz, T.; Davis, N.; Debieux, S.; Dembinski, H.; Diakonos, F.; Di Luise, S.; Dominik, W.; Drozhzhova, T.; Dumarchez, J.; Dynowski, K.; Engel, R.; Ereditato, A.; Esposito, L.S.; Feofilov, G.A.; Fodor, Z.; Ferrero, A.; Fulop, A.; Gazdzicki, M.; Golubeva, M.; Grabez, B.; Grebieszkow, K.; Grzeszczuk, A.; Guber, F.; Hakobyan, H.; Hasegawa, T.; Hierholzer, M.; Idczak, R.; Igolkin, S.; Ivanov, Y.; Ivashkin, A.; Jakovic, D.; Kadija, K.; Kapoyannis, A.; Katrynska, N.; Kaptur, E.; Kielczewska, D.; Kikola, D.; Kirejczyk, M.; Kisiel, J.; Kiss, T.; Kleinfelder, S.; Kobayashi, T.; Kolesnikov, V.I.; Kolev, D.; Kondratiev, V.P.; Korzenev, A.; Kowalski, S.; Krasnoperov, A.; Kuleshov, S.; Kurepin, A.; Larsen, D.; Laszlo, A.; Lyubushkin, V.V.; Mackowiak-Pawlowska, M.; Majka, Z.; Maksiak, B.; Malakhov, A.I.; Maletic, D.; Marchionni, A.; Marcinek, A.; Marin, V.; Marton, K.; Mathes, H.J.; Matulewicz, T.; Matveev, V.; Melkumov, G.L.; Mrowczynski, St.; Murphy, S.; Nakadaira, T.; Nirkko, M.; Nishikawa, K.; Palczewski, T.; Palla, G.; Panagiotou, A.D.; Paul, T.; Pistillo, C.; Redij, A.; Peryt, W.; Petukhov, O.; Planeta, R.; Pluta, J.; Popov, B.A.; Posiadala, M.; Pulawski, S.; Puzovic, J.; Rauch, W.; Ravonel, M.; Renfordt, R.; Robert, A.; Röhrich, D.; Rondio, E.; Roth, M.; Rubbia, A.; Rustamov, A.; Rybczynski, M.; Sadovsky, A.; Sakashita, K.; Savic, M.; Sekiguchi, T.; Seyboth, P.; Shibata, M.; Sipos, M.; Skrzypczak, E.; Slodkowski, M.; Staszel, P.; Stefanek, G.; Stepaniak, J.; Stroebele, H.; Susa, T.; Szuba, M.; Tada, M.; Tereshchenko, V.; Tolyhi, T.; Tsenov, R.; Turko, L.; Ulrich, R.; Unger, M.; Vassiliou, M.; Veberic, D.; Vechernin, V.V.; Vesztergombi, G.; Vinogradov, L.; Wilczek, A.; Wlodarczyk, Z.; Wojtaszek, A.; Wyszynski, O.; Zambelli, L.; Zipper, W.

    2013-01-01

    NA61/SHINE at the CERN SPS is a fixed-target experiment pursuing a rich physics program including measurements for heavy ion, neutrino and cosmic ray physics. The main goal of the ion program is to explore the most interesting $T, mu_{B}$ region of the phase diagram of strongly interacting matter. We plan to study the properties of the onset of deconfinement and to search for the signatures of the critical point. The search is performed by varying collision energy (13A-158A GeV/c) and system size (p+p, Be+Be, Ar+Ca, Xe+La). Thanks to its large acceptance and excellent particle identification capability NA61/SHINE is well suited for performing high-precision particle production measurements as well as for studying event-by-event fluctuations in p+p, p+nucleus and nucleus+nucleus collisions. Preliminary results on p+p interactions at 20, 31, 40, 80 and 158 GeV/c are presented. They include inclusive spectra of pi+, pi-, K- and protons as a function of transverse momentum/mass and rapidity as well as event-by-ev...

  16. Experimental investigation of the behaviour and fate of block copolymers in fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós

    Fouling-release coatings (FRC) were developed as an environmentally friendly alternative after the ban of highly toxic antifouling coatings based on tributyltin. Poly(dimethylsiloxane) (PDMS) has been the most widely used polymer for FRC, and its fouling-inhibition properties have been enhanced....... FRC provide superior fuel savings to the shipping industry on the first stages of immersion compared to other current technologies, albeit its performance declines over time. This project is mainly concerned with improving the understanding of FRC and identifying the causes that result...... to the interfaces of the PDMS film could be observed by following the fluorescence intensity at different depths over time. The chemical stability of PDMS-PEG-based copolymers in PDMS coatings immersed for up to 30 months in seawater in Singapore was also investigated. The copolymer remaining in the coatings after...

  17. Membrane fouling related to microbial community and extracellular polymeric substances at different temperatures.

    Science.gov (United States)

    Gao, Da-Wen; Wen, Zhi-Dan; Li, Bao; Liang, Hong

    2013-09-01

    An anoxic-aerobic membrane bioreactor was established to investigate the role of microorganisms and microbial metabolites in membrane fouling at different temperatures. The results showed that the membrane fouling cycle at 303, 293, and 283 K were 30, 29, and 5.5 days, respectively. Polysaccharides dominated the extracellular polymeric substances (EPS) and soluble microbial products (SMP) at 303 and 293 K, instead, proteins was the predominant composition of metabolites at 283 K. The correlation coefficient (r(2)) was calculated to identify the relationship between temperature (T), filtration resistance (R) and compositions of EPS and SMP. In biocake, the EPS polysaccharides (EPSc) was the most correlative factor to temperature (T) and filtration resistance (R); in mixed liquor, the ratio of SMP polysaccharides to proteins (SMPc/p) was the most correlative factor. The microbial community structure and the dominant species was the major reason causing the change of EPS and SMP composition. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Slow Earthquake Hunters: A New Citizen Science Project to Identify and Catalog Slow Slip Events in Geodetic Data

    Science.gov (United States)

    Bartlow, N. M.

    2017-12-01

    Slow Earthquake Hunters is a new citizen science project to detect, catalog, and monitor slow slip events. Slow slip events, also called "slow earthquakes", occur when faults slip too slowly to generate significant seismic radiation. They typically take between a few days and over a year to occur, and are most often found on subduction zone plate interfaces. While not dangerous in and of themselves, recent evidence suggests that monitoring slow slip events is important for earthquake hazards, as slow slip events have been known to trigger damaging "regular" earthquakes. Slow slip events, because they do not radiate seismically, are detected with a variety of methods, most commonly continuous geodetic Global Positioning System (GPS) stations. There is now a wealth of GPS data in some regions that experience slow slip events, but a reliable automated method to detect them in GPS data remains elusive. This project aims to recruit human users to view GPS time series data, with some post-processing to highlight slow slip signals, and flag slow slip events for further analysis by the scientific team. Slow Earthquake Hunters will begin with data from the Cascadia subduction zone, where geodetically detectable slow slip events with a duration of at least a few days recur at regular intervals. The project will then expand to other areas with slow slip events or other transient geodetic signals, including other subduction zones, and areas with strike-slip faults. This project has not yet rolled out to the public, and is in a beta testing phase. This presentation will show results from an initial pilot group of student participants at the University of Missouri, and solicit feedback for the future of Slow Earthquake Hunters.

  19. A Practical Approach for Studying Fouling Process in Li-Recovery Pilot Plant

    Science.gov (United States)

    Kong, M.; Yoon, H.; Eom, C.; Kim, B.; Chung, K.

    2011-12-01

    The efficiency of selective ion recovery such as lithium from seawater has been major interest of previous studies. However, the characterization of adsorption behavior as well as dissolution yield as discharging environmentally problematic chemical species must carefully studied in various conditions including different seawater conditions [1]. Marine biofouling communities are complex, highly dynamic ecosystems consisting of a diverse range of organisms. The development of such communities begins with bacterial attachment followed by the colonization of higher organisms such as invertebrate larvae and algal spores [2-3]. Monitoring and field studies regarding fouling problems during operation of Li-recovery pilot plant which is designed by the Korea Institute of Geoscience & Mineral Resources (KIGAM) were major concern of this study. We examined fouling process for the duration of exposure time in real marine environment. Substrated with no-antifouling treated material and antifouling treated material were exposed and tested for different behaviors toward fouling in ocean. SEM-EDS (Scanning Electron Microscope-Energy dispersive Spectroscopy) analysis was done for surface identification of specific elements for possible dissolution during seawater exposure. To identify organic compound was used GC-MS (Gas Chromatography Mass Spectrometer) analysis. Experiment results, organisms such as alga are fouled the most on 30 days and antitreated material is fouled less than non antitreated material. Operating Li-recovery pilot plant to sea, we need to consider in order to effectively and economically resolve the fouling problem. Acknowledgement : This research was supported by the national research project titled "The Development of Technology for Extraction of Resources Dissolved in Seawater" of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Land, Transport and Maritime Affairs. References [1] M. Y. Diego, K. Soren, and D. J. Kim

  20. Polymeric membranes: surface modification for minimizing (bio)colloidal fouling.

    Science.gov (United States)

    Kochkodan, Victor; Johnson, Daniel J; Hilal, Nidal

    2014-04-01

    This paper presents an overview on recent developments in surface modification of polymer membranes for reduction of their fouling with biocolloids and organic colloids in pressure driven membrane processes. First, colloidal interactions such as London-van der Waals, electrical, hydration, hydrophobic, steric forces and membrane surface properties such as hydrophilicity, charge and surface roughness, which affect membrane fouling, have been discussed and the main goals of the membrane surface modification for fouling reduction have been outlined. Thereafter the recent studies on reduction of (bio)colloidal of polymer membranes using ultraviolet/redox initiated surface grafting, physical coating/adsorption of a protective layer on the membrane surface, chemical reactions or surface modification of polymer membranes with nanoparticles as well as using of advanced atomic force microscopy to characterize (bio)colloidal fouling have been critically summarized. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Abundance of bacterial and diatom fouling on various surfaces

    Digital Repository Service at National Institute of Oceanography (India)

    PrabhaDevi

    Abundance of bacterial and diatom fouling on aluminium, fibreglass and stainless steel were studied from Dona Paula waters of the Zuari Estuary. Both these forms were reversibly attached in large numbers to surfaces during the initial 24 hr...

  2. Fouling in small hydro projects; Verschmutzung von Kleinwasserkraftwerken - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Abgottspon, A.; Staubli, T.

    2010-03-15

    This comprehensive final report for the Swiss Federal Office of Energy (SFOE) takes a look at fouling problems encountered in small hydro installations. The report is based on ten interviews made with operators of small hydro power stations in Switzerland. A parallel project carried out in Germany is mentioned. A large variation in the degree of fouling in the various hydro power stations is noted. Sources such as leaves in autumn and algae are discussed, as are the various rinsing procedures used to clear the turbines of fouling. Power losses are discussed and measures that can be taken to prevent fouling are described. Measurements made at an installation in Freienstein, Switzerland, are presented and discussed. The report is completed with an appendix containing calculations, details on the Freienstein power plant and the results of interviews made with the ten hydro power installations examined.

  3. Scaling and particulate fouling in membrane filtration systems

    NARCIS (Netherlands)

    Boerlage, S.F.E.

    2001-01-01

    Membrane filtration technologies have emerged as cost competitive and viable techniques in drinking and industrial water production. Despite advancements in membrane manufacturing and technology, membrane scaling and fouling remain major problems and may limit future growth in the industry. Scaling

  4. Fouling-induced enzyme immobilization for membrane reactors

    DEFF Research Database (Denmark)

    Luo, Jianquan; Meyer, Anne S.; Jonsson, Gunnar Eigil

    2013-01-01

    A simple enzyme immobilization method accomplished by promoting membrane fouling formation is proposed. The immobilization method is based on adsorption and entrapment of the enzymes in/on the membrane. To evaluate the concept, two membrane orientations, skin layer facing feed (normal mode......, but the reverse mode allowed for higher enzyme loading and stability, and irreversible fouling (i.e. pore blocking) developed more readily in the support structure than in the skin layer. Compared with an enzymatic membrane reactor (EMR) with free enzymes, the novel EMR with enzymes immobilized in membrane......) and support layer facing feed (reverse mode), were used to immobilize alcohol dehydrogenase (ADH, EC 1.1.1.1) and glutamate dehydrogenase (GDH, EC 1.4.1.3), respectively. The nature of the fouling in each mode was determined by filtration fouling models. The permeate flux was larger in the normal mode...

  5. Fouling Kinetics and Associated Dynamics of Structural Modifications

    DEFF Research Database (Denmark)

    Jacob, Jerome; Prádanos, Pedro; Calvo, J. I.

    1998-01-01

    It is shown that the fouling behaviour of microfiltration membranes does not agree within all the time ranges of any of the commonly used membrane blocking models (i.e. complete, standard, intermediate or cake blocking). The resulting experimental kinetics of flux decline do not fit to only one...... of these models, but according to a successive or simultaneous coexistence of two or more of them. This is studied by analysing the structural modifications associated with the fouling kinetics. To achieve this goal, here we analyse the dynamical changes on the structure of four microporous membranes made...... by Sartorius (ST02 and ST045, neutral) and Spectrum (SP02 and SP045, positively charged) when fouled by permeating a protein aqueous solution (bovine serum albumin (BSA) at 1 g l(-1)) under 10 kPa in a dead-end device. The structure after different fouling times is obtained by using an extended bubble point...

  6. Ultrafiltration Membrane Fouling and the Effect of Ion Exchange Resins

    KAUST Repository

    Jamaly, Sanaa

    2011-12-01

    Membrane fouling is a challenging process for the ultrafiltration membrane during wastewater treatment. This research paper determines the organic character of foulants of different kinds of wastewater before and after adding some ion exchange resins. Two advanced organic characterization methods are compared in terms of concentration of dissolved organic carbons: The liquid chromatography with organic carbon (LC-OCD) and Shimadzu total organic carbon (TOC). In this study, two secondary wastewater effluents were treated using ultrafiltration membrane. To reduce fouling, pretreatment using some adsorbents were used in the study. Six ion exchange resins out of twenty were chosen to compare the effect of adsorbents on fouling membrane. Based on the percent of dissolved organic carbon’s removal, three adsorbents were determined to be the most efficient (DOWEX Marathon 11 anion exchange resin, DOWEX Optipore SD2 polymeric adsorbent, and DOWEX PSR2 anion exchange), and three other ones were determined to the least efficient (DOWEX Marathon A2 anion exchange resin, DOWEX SAR anion exchange resin, and DOWEX Optipore L493 polymeric adsorbent). Organic characterization for feed, permeate, and backwash samples were tested using LC-OCD and TOC to better understand the characteristics of foulants to prevent ultrafiltration membrane fouling. The results suggested that the polymeric ion exchange resin, DOWEX SD2, reduced fouling potential for both treated wastewaters. All the six ion exchange resins removed more humic fraction than other organic fractions in different percent, so this fraction is not the main for cause for UF membrane fouling. The fouling of colloids was tested before and after adding calcium. There is a severe fouling after adding Ca2+ to effluent colloids.

  7. Development of a test platform for anti-fouling coatings

    OpenAIRE

    Meskens, R.; Willemen, R.; Potters, G.; De Baere, K.; Lenaerts, S.

    2017-01-01

    Marine fouling, or the growth of marine organisms on fully or partly submerged structures, is an unwanted phenomenon in the marine industry. Bio fouling will increase the hydrodynamic drag of ships, causing an increased fuel consumption, promote the corrosion of the metallic structures and trigger undesired transport of invasive species (IMO and the environment 2009, 2009).The impact is economic as well as environmental. More fuel consumption is synonym for more CO2 and other detrimental emis...

  8. High Concentration Protein Ultrafiltration: a Comparative Fouling Assessment

    Science.gov (United States)

    Lim, Y. P.; Mohammad, A. W.

    2018-05-01

    In this paper, the predominant fouling mechanism via pH manipulation in gelatin ultrafiltration (UF) at constant operating pressure was studied. Two 30 kDa molecular weight cut off (MWCO) UF membranes with different hydrophilic/hydrophobic properties were tested at solution pH near gelatin isoelectric point (IEP), pH below and above gelatin’s IEP. The resistance-in-series model was used to determine quantitatively the contribution of each filtration resistance occurred during gelatin UF. The governing fouling mechanisms were investigated using classical blocking laws. The results demonstrated that concentration polarization remain as dominant fouling resistance in gelatin UF, but exceptional case was observed at pH away from gelatin’s IEP, showing that combined reversible and irreversible fouling resistances contributed around 57% and 37%, respectively to the overall fouling resistances. Under all experimental condition tested, permeate flux decline was accurately predicted by all the models studied. Fouling profile was fitted well with “Standard Blocking”, “Intermediate Blocking” and “Cake Filtration” model for regenerated cellulose acetate (RCA) membrane and “Cake Filtration” model for polyethersulphone (PES) membrane.

  9. Ultrasonic control of ceramic membrane fouling: Effect of particle characteristics.

    Science.gov (United States)

    Chen, Dong; Weavers, Linda K; Walker, Harold W

    2006-02-01

    In this study, the effect of particle characteristics on the ultrasonic control of membrane fouling was investigated. Ultrasound at 20 kHz was applied to a cross-flow filtration system with gamma-alumina membranes in the presence of colloidal silica particles. Experimental results indicated that particle concentration affected the ability of ultrasound to control membrane fouling, with less effective control of fouling at higher particle concentrations. Measurements of sound wave intensity and images of the cavitation region indicated that particles induced additional cavitation bubbles near the ultrasonic source, which resulted in less turbulence reaching the membrane surface and subsequently less effective control of fouling. When silica particles were modified to be hydrophobic, greater inducement of cavitation bubbles near the ultrasonic source occurred for a fixed concentration, also resulting in less effective control of fouling. Particle size influenced the cleaning ability of ultrasound, with better permeate recovery observed with larger particles. Particle size did not affect sound wave intensity, suggesting that the more effective control of fouling by large particles was due to greater lift and cross-flow drag forces on larger particles compared to smaller particles.

  10. Kinetic study of seawater reverse osmosis membrane fouling

    KAUST Repository

    Khan, Muhammad

    2013-10-01

    Reverse osmosis (RO) membrane fouling is not a static state but a dynamic phenomenon. The investigation of fouling kinetics and dynamics of change in the composition of the foulant mass is essential to elucidate the mechanism of fouling and foulant-foulant interactions. The aim of this work was to study at a lab scale the fouling process with an emphasis on the changes in the relative composition of foulant material as a function of operating time. Fouled membrane samples were collected at 8 h, and 1, 2, and 4 weeks on a lab-scale RO unit operated in recirculation mode. Foulant characterization was performed by CLSM, AFM, ATR-FTIR, pyrolysis GC-MS, and ICP-MS techniques. Moreover, measurement of active biomass and analysis of microbial diversity were performed by ATP analysis and DNA extraction, followed by pyro-sequencing, respectively. A progressive increase in the abundance of almost all the foulant species was observed, but their relative proportion changed over the age of the fouling layer. Microbial population in all the membrane samples was dominated by specific groups/species belonging to Proteobacteria and Actinobacteria phyla; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age. © 2013 American Chemical Society.

  11. Short Review on Predicting Fouling in RO Desalination

    Directory of Open Access Journals (Sweden)

    Alejandro Ruiz-García

    2017-10-01

    Full Text Available Reverse Osmosis (RO membrane fouling is one of the main challenges that membrane manufactures, the scientific community and industry professionals have to deal with. The consequences of this inevitable phenomenon have a negative effect on the performance of the desalination system. Predicting fouling in RO systems is key to evaluating the long-term operating conditions and costs. Much research has been done on fouling indices, methods, techniques and prediction models to estimate the influence of fouling on the performance of RO systems. This paper offers a short review evaluating the state of industry knowledge in the development of fouling indices and models in membrane systems for desalination in terms of use and applicability. Despite major efforts in this field, there are gaps in terms of effective methods and models for the estimation of fouling in full-scale RO desalination plants. In existing models applied to full-scale RO desalination plants, neither the spacer geometry of membranes, nor the efficiency and frequency of chemical cleanings are considered.

  12. On-line fouling monitor for heat exchangers

    International Nuclear Information System (INIS)

    Tsou, J.L.

    1995-01-01

    Biological and/or chemical fouling in utility service water system heat exchangers adversely affects operation and maintenance costs, and reduced heat transfer capability can force a power deaerating or even a plant shut down. In addition, service water heat exchanger performance is a safety issue for nuclear power plants, and the issue was highlighted by NRC in Generic Letter 89-13. Heat transfer losses due to fouling are difficult to measure and, usually, quantitative assessment of the impact of fouling is impossible. Plant operators typically measure inlet and outlet water temperatures and flow rates and then perform complex calculations for heat exchanger fouling resistance or ''cleanliness''. These direct estimates are often imprecise due to inadequate instrumentation. Electric Power Research Institute developed and patented an on-line condenser fouling monitor. This monitor may be installed in any location within the condenser; does not interfere with routine plant operations, including on-line mechanical and chemical treatment methods; and provides continuous, real-time readings of the heat transfer efficiency of the instrumented tube. This instrument can be modified to perform on-line monitoring of service water heat exchangers. This paper discusses the design, construction of the new monitor, and algorithm used to calculate service water heat exchanger fouling

  13. Identifying and Overcoming Barriers to Effective Consideration of Human and Organisational Factors in Event Analysis and Root Cause Analysis. Workshop Proceedings, September 21-22, 2009, Paris, France

    International Nuclear Information System (INIS)

    2011-01-01

    Nuclear licensees must have effective processes for learning from operating experience in order to manage safety, secure continuous improvement and defend against the potential for repeat events. These processes include root cause analysis (RCA) to identify the underlying causes of events and mechanisms to learn from these analyses and to implement improvements. Correctly identifying and correcting the causes of events will allow lessons to be learned and shared with others in the industry. The treatment of Human and Organisational Factors (HOF) in RCA is of special interest to WGHOF. It is estimated that approximately 60-80% of events in the nuclear industry can be attributed to human and organisational factors. Although the importance of correctly identifying the HOF causes is understood, there is still a tendency for the analysis to focus solely on the technical issues of the event. The history of prominent events across the major hazards sector shows that HOF lessons often fail to be learned. A NEA/CSNI special experts meeting entitled 'Identification of Barriers to Analyzing and Identifying Human and Organisational Factors in Root Cause Analysis' was held at the NEA Headquarters in Paris, France on September 21-22, 2009. A total of 17 participants from 10 countries representing licensee organisations, regulators, international organisations and an independent consultant attended the meeting. The meeting was structured to allow for small group discussions during which a number of themes were explored, followed by plenary discussion. There were also four papers presented which complemented the discussion themes. As set out in the objectives of this work, the participants identified barriers to the effective treatment of HOF in RCA and recommendations to mitigate the effects of these barriers. Many of the barriers and recommendations identified relate to the RCA process in general, not specifically to the treatment of HOF in the RCA process. This is logical, for

  14. A study on method to identify actual causes and conditions of safety rule deviations through analyzing events due to unsafe acts of workers

    International Nuclear Information System (INIS)

    Hirotsu, Yuko; Takeda, Daisuke

    2010-01-01

    The purpose of this study is to establish a method to understand actual causes and condition of intentional deviation from safety rules (including norm and written rules that has developed to anticipate, prevent, detect and recover human errors) in an organization by analyzing events due to unsafe acts of workers (human factor events) and to propose effective measures. Firstly, by reviewing literature regarding safety violations, the following two advantages of investigating actual condition of safety rule deviation through human factor event analysis were extracted, such as (a) being able to clarify relationships between deviations, human errors, and events, and (b) being able to identify specific causal factors that influenced the decision to deviate, including acts of people concerned, problems with rules, task demands, environment and management. Next, through the analysis of human factor event data in accordance with existing human error analysis method on the basis of advantages above, the following three requirements for analyzing event data were extracted, such as (a) gathering information such as rules concerning to the work activities related to the human factor events, and whether there are intentional deviations of the rules, (b) gathering information and identify interrelations among causal factors of the intentional deviations, and (c) gathering information on general condition of deviations and the causal factors. (author)

  15. Abrasion and algal fouling of coarse material on the Murman littoral

    Directory of Open Access Journals (Sweden)

    Malavenda S. V.

    2017-03-01

    Full Text Available On the Murmansk coast of the Barents Sea the boulder littoral zone is widely spread mostly covered by Fucus communities. This is one of the most productive benthic communities of the Barents Sea. The studies of intertidal communities have the long history, but the dynamics of intertidal ecosystems due to surf and storms is not clear. The goal of the work is to identify the leading factors that determine the rate of abrasion of coarse material and fouling algae-macrophytes of the intertidal zone of Murman. The study has been conducted in the Zelenetskaya Bay of the Barents Sea on the basis of the biological station of the MMBI KSC RAS. The rate of abrasion has been carried out during 2004–2013, phyto-overgrowing – 2009–2013. In three pilot landfills 12 samples of coarse material have been exposed during the year (from July to next July. The weight change of the sample as well as species composition and biomass of algae of fouling communities have been investigated. The influence of the surf intensity, temperature of water and air has been analyzed (univariate analysis of variance ANOVA has been applied. It has been shown that on the littoral of the Murmansk coast the abrasion of coarse material is determined primarily by the number of storms, so the storm rate has been proposed. It has been revealed that the density of fouling boulders with macroalgae depends primarily on the intensity of the surf and the average gradient of air temperature. The basis for the emerging communities of annual species are green (Acrosiphonia arcta, Blidingia minima, Spongomorpha aeruginosa and brown algae (Pylaiella littoralis, Dictyosiphon chordaria. These algae groups are found everywhere in Fucus communities of the boulder intertidal zone of the Murman coast and probably they are the intermediate stage of fouling the coarse-grained material

  16. Identifying deliberate attempts to fake memory impairment through the combined use of reaction time and event-related potential measures

    NARCIS (Netherlands)

    van Hooff, Johanna C.; Sargeant, Elizabeth; Foster, Jonathan K.; Schmand, Ben A.

    2009-01-01

    The central aim of this study was to evaluate the value of reaction time (RT) measures and event-related potentials (ERPs) for the assessment of simulated memory impairment. In two identical experiments (N = 24), healthy volunteers carried out an adapted version of the Amsterdam Short-Term Memory

  17. Bagging grey swans : A supply network approach to identifying and managing low-probability high-impact supply chain events

    NARCIS (Netherlands)

    Rossetti, Christian; Akkermans, Henk; Bhakoo, Vikram; Carnovale, Steven

    Over the past decade practitioners and researchers have become increasingly focused on managing risks in extended supply chains. Whether these risks involve supply disruptions, financial liabilities for a supplier’s actions, or large market shifts; Grey Swan events, defined as unforeseen

  18. Superhydrophilic Thin-Film Composite Forward Osmosis Membranes for Organic Fouling Control: Fouling Behavior and Antifouling Mechanisms

    KAUST Repository

    Tiraferri, Alberto

    2012-10-16

    This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes. © 2012 American Chemical Society.

  19. Superhydrophilic thin-film composite forward osmosis membranes for organic fouling control: fouling behavior and antifouling mechanisms.

    Science.gov (United States)

    Tiraferri, Alberto; Kang, Yan; Giannelis, Emmanuel P; Elimelech, Menachem

    2012-10-16

    This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes.

  20. Experimental study of composition and influence factors on fouling of stainless steel and copper in seawater

    International Nuclear Information System (INIS)

    Yang, Dazhang; Liu, Jianhua; E, Xiaoxue; Jiang, Linlin

    2016-01-01

    Highlights: • An increase of seawater temperature deteriorates the fouling and corrosion. • The main compositions of crystals are Mg(OH) 2 , Al(OH) 3 and their complex compounds. • The images of the seawater fouling on stainless steel and copper were shown in the paper. • A higher heat flux and A higher Reynolds number are prone to crystallization fouling accumulation in seawater. - Abstract: Metals and alloys are easily fouled in marine environment. It is a big problem for heat exchangers using cooling seawater in power plants or ships. In the paper, a seawater-fouling dynamic test device was built to investigate the composition and influence factors on fouling of stainless steel and copper in the cooling seawater system. Moreover, the static trials were performed to study the fouling and corrosion of stainless steel and copper in marine environment. The experimental results show that the seawater fouling of stainless steel is crystallization fouling, and the main elements of fouling are magnesium and aluminum. In addition, the results show that the seawater fouling of copper is corrosion fouling. In the dynamic experiments, the effects of heat flux and Reynolds number on stainless steel fouling were studied. The results show that higher heat flux and higher Reynolds number of seawater lead to the accumulation of seawater fouling.

  1. KARAKTERISTIK INTERAKSI MEMBRAN-FOULANT DAN FOULANT-FOULANT SEBAGAI DASAR PENGENDALIAN FOULING

    Directory of Open Access Journals (Sweden)

    Heru Susanto

    2012-05-01

    Full Text Available THE CHARACTERISTICS OF MEMBRANE-FOULANT AND FOULANT-FOULANT INTERACTIONS AS THE BASIS FOR CONTROL OF FOULING. Industrial membrane applications for solid liquid and liquid-liquid filtration are limited by fouling and concentration polarization. Because fouling significantly reduces the membrane performance and often changes the membrane selectivity, efforts to overcome the fouling problem are very important from practical applications point of view. This paper presents the basic knowledge required to control fouling and recent development in fouling control including the method developed by the author. Control of fouling can be done by (i commercial membrane modification (post modification by photo-graft polymerization, (ii modification by polymer blending during membrane manufacturing and (iii integration of a pretreatment into membrane processes. The results showed that all the developed methods can significantly reduce the resulting fouling; however, none of the method could totally remove the occurring fouling. The understanding of the membrane-foulant and foulant-foulant interactions is the key to success in control of fouling.Aplikasi teknologi membran untuk pemisahan padat cair di  berbagai industri dibatasi oleh peristiwa fouling yang menyebabkan penurunan laju produk dan perubahan selektifitas membran. Oleh karena itu, pengendalian fouling merupakan upaya yang mutlak harus dilakukan. Makalah ini mempresentasikan pengetahuan dasar yang diperlukan untuk pengendalian fouling dan perkembangan terkini dalam pengendalian fouling termasuk hasil-hasil yang telah dikembangkan oleh penulis. Pengendalian fouling dilakukan dengan (i modifikasi membran komersial (post modification menggunakan metode photo-grafting, (ii modifikasi dengan pencampuran polimer selama proses pembuatan (polymer blend dan (iii integrasi unit perlakuan awal (pre-treatment dengan proses membran. Hasil penelitian menunjukkan bahwa kesemua metode yang dikembangkan dapat

  2. Membrane fouling of forward osmosis (FO) membrane for municipal wastewater treatment: A comparison between direct FO and OMBR.

    Science.gov (United States)

    Sun, Yan; Tian, Jiayu; Zhao, Zhiwei; Shi, Wenxin; Liu, Dongmei; Cui, Fuyi

    2016-11-01

    In this work, membrane fouling behavior in a direct forward osmosis (FO) and an osmotic membrane bioreactor (OMBR) for municipal wastewater treatment was systematically investigated and compared. During the long-term operation, much severer flux decline was observed for the direct FO than that for the OMBR. The cake layer was found to be much thicker, together with large amounts of microorganisms growing on the membrane surface in direct FO. Interestingly, no obvious attachment of microorganisms on the membrane surface was observed in the OMBR. The fourier transform infrared spectroscopy (FTIR) and excitation emission matrices (EEM) analyses showed the polysaccharides and proteins were the dominant organic foulants in the fouling layer, and the quantity of the organic substances was also higher in direct FO than that in OMBR. Energy-dispersive X-ray (EDX) results indicated the main inorganic elements in the fouling layer were Ca, Mg, Fe and P, all of which exhibited higher relative percentages in direct FO than that in OMBR. The occurrence of higher contents of microorganisms, organic foulants and inorganic elements in the cake layer caused a higher filtration resistance for the FO membrane in the direct FO. Although more severe membrane fouling was identified in direct FO, the hydraulic and chemical cleaning was more effective on recovering the water permeability of the membrane in direct FO than that in OMBR. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Fouling of Structured Surfaces during Pool Boiling of Aqueous Solutions

    International Nuclear Information System (INIS)

    Esawy, M.

    2011-01-01

    Bubble characteristics in terms of density, size, frequency and motion are key factors that contribute to the superiority of nucleate pool boiling over the other modes of heat transfer. Nevertheless, if heat transfer occurs in an environment which is prone to fouling, the very same parameters may lead to accelerated deposit formation due to concentration effects beneath the growing bubbles. This has led heat exchanger designers frequently to maintain the surface temperature below the boiling point if fouling occurs, e.g. in thermal seawater desalination plants. The present study investigates the crystallization fouling of various structured surfaces during nucleate pool boiling of CaSO 4 solutions to shed light into their fouling behaviour compared with that of plain surfaces for the same operating conditions. As for the experimental part, a comprehensive set of clean and fouling experiments was performed rigorously. The structured tubes included low finned tubes of different fin densities, heights and materials and re-entrant cavity Turbo-B tube types.The fouling experiments were carried out at atmospheric pressure for different heat fluxes ranging from 100 to 300 k W/m 2 and CaSO 4 concentrations of 1.2 and 1.6 g/L. For the sake of comparison, similar runs were performed on plain stainless steel and copper tubes.Overall for the finned tubes, the experimental results showed a significant reduction of fouling resistances of up to 95% compared to those of the stainless steel and copper plain tubes. In addition, the scale formation that occurred on finned tubes was primarily a scattered and thin crystalline layer which differs significantly from those of plain tubes which suffered from a thick and homogenous layer of deposit with strong adhesion. Higher fin densities and lower fin heights always led to better antifouling performance for all investigated finned tubes. It was also shown that the surface material strongly affects the scale formation of finned tubes i

  4. In-line quantification and characterization of membrane fouling

    KAUST Repository

    Bucs, Szilard

    2016-06-16

    Methods of detecting, quantifying and/or characterizing the fouling of a device from a combination of pressure and spectroscopic data are provided. The device can be any device containing components susceptible to fouling. Components can include membranes, pipes, or reactors. Suitable devices include membrane devices, heat exchangers, and chemical or bio-reactors. Membrane devices can include, for example, microfiltration devices, ultrafiltration devices, nanofiltration devices, reverse osmosis, forward osmosis, osmosis, reverse electrodialysis, electro- deionisation or membrane distillation devices. The methods can be applied to any type of membrane, including tubular, spiral, hollow fiber, flat sheet, and capillary membranes. The spectroscopic characterization can include measuring one or more of the absorption, fluorescence, or raman spectroscopic data of one or more foulants. The methods can allow for the early detection and/or characterization of fouling. The characterization can include determining the specific foulant(s) or type of foulant(s) present. The characterization of fouling can allow for the selection of an appropriate de-fouling method and timing.

  5. Forward osmosis membrane fouling and cleaning for wastewater reuse

    Directory of Open Access Journals (Sweden)

    Youngbeom Yu

    2017-06-01

    Full Text Available Membrane fouling properties and different physical cleaning methods for forward osmosis (FO and reverse osmosis (RO laboratory-scale filtration systems were investigated. The membrane fouling, with respect to flux reduction, was lower in FO than in RO when testing an activated sludge effluent. Cross-flow velocity, air-scouring, osmotic backwashing and effect of a spacer were compared to determine the most effective cleaning method for FO. After a long period of fouling with activated sludge, the flux was fully recovered in a short period of osmotic backwashing compared with cleaning by changing cross-flow velocity and air-scouring. In this study, the osmotic backwashing was found to be the most efficient way to clean the FO membrane. The amount of RNA recovered from FO membranes was about twice that for RO membranes; biofouling could be more significant in FO than in RO. However, the membrane fouling in FO was lower than that in RO. The spacer increased the flux in FO with activated sludge liquor suspended solids of 2,500 mg/L, and there were effects of spacer on performance of FO–MBR membrane fouling. However, further studies are required to determine how the spacer geometry influences on the performance of the FO membrane.

  6. Rejection of Organic Micropollutants by Clean and Fouled Nanofiltration Membranes

    Directory of Open Access Journals (Sweden)

    Lifang Zhu

    2015-01-01

    Full Text Available The rejection of organic micropollutants, including three polycyclic aromatic hydrocarbons (PAHs and three phthalic acid esters (PAEs, by clean and fouled nanofiltration membranes was investigated in the present study. The rejection of organic micropollutants by clean NF90 membranes varied from 87.9 to more than 99.9%, while that of NF270 membranes ranged from 32.1 to 92.3%. Clear time-dependence was observed for the rejection of hydrophobic micropollutants, which was attributed to the adsorption of micropollutants on the membrane. Fouling with humic acid had a negligible influence on the rejection of organic micropollutants by NF90 membranes, while considerable effects were observed with NF270 membranes, which are significantly looser than NF90 membranes. The observed enhancement in the rejection of organic micropollutants by fouled NF270 membranes was attributed to pore blocking, which was a dominating fouling mechanism for loose NF membranes. Changes in the ionic strength (from 10 to 20 mM reduced micropollutant rejection by both fouled NF membranes, especially for the rejection of dimethyl phthalate and diethyl phthalate by NF270 membranes (from 65.8 to 25.0% for dimethyl phthalate and 75.6 to 33.3% for diethyl phthalate.

  7. The New Performance Calculation Method of Fouled Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    Huadong Yang

    2014-01-01

    Full Text Available Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds’ law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.

  8. CFD modeling of fouling in crude oil pre-heaters

    International Nuclear Information System (INIS)

    Bayat, Mahmoud; Aminian, Javad; Bazmi, Mansour; Shahhosseini, Shahrokh; Sharifi, Khashayar

    2012-01-01

    Highlights: ► A conceptual CFD-based model to predict fouling in industrial crude oil pre-heaters. ► Tracing fouling formation in the induction and developing continuation periods. ► Effect of chemical components, shell-side HTC and turbulent flow on the fouling rate. - Abstract: In this study, a conceptual procedure based on the computational fluid dynamic (CFD) technique has been developed to predict fouling rate in an industrial crude oil pre-heater. According to the developed CFD concept crude oil was assumed to be composed of three pseudo-components comprising of petroleum, asphaltene and salt. The binary diffusion coefficients were appropriately categorized into five different groups. The species transport model was applied to simulate the mixing and transport of chemical species. The possibility of adherence of reaction products to the wall was taken into account by applying a high viscosity for the products in competition with the shear stress on the wall. Results showed a reasonable agreement between the model predictions and the plant data. The CFD model could be applied to new operating conditions to investigate the details of the crude oil fouling in the industrial pre-heaters.

  9. Zeta-potential of fouled thin film composite membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1999-10-01

    The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)

  10. A survey of gas-side fouling in industrial heat-transfer equipment

    Science.gov (United States)

    Marner, W. J.; Suitor, J. W.

    1983-11-01

    Gas-side fouling and corrosion problems occur in all of the energy intensive industries including the chemical, petroleum, primary metals, pulp and paper, glass, cement, foodstuffs, and textile industries. Topics of major interest include: (1) heat exchanger design procedures for gas-side fouling service; (2) gas-side fouling factors which are presently available; (3) startup and shutdown procedures used to minimize the effects of gas-side fouling; (4) gas-side fouling prevention, mitigation, and accommodation techniques; (5) economic impact of gas-side fouling on capital costs, maintenance costs, loss of production, and energy losses; and (6) miscellaneous considerations related to gas-side fouling. The present state-of-the-art for industrial gas-side fouling is summarized by a list of recommendations for further work in this area.

  11. Species interactions within a fouling diatom community: Roles of nutrients, initial inoculum and competitive strategies

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A

    Diatoms constitute an important component of the fouling community. Although a lot of work has dealt with the fouling diatom community structure, work on the species interactions within the community is still meager. In this regard, a study...

  12. In-situ non-invasive device for early detection of fouling in aquatic systems

    KAUST Repository

    Fortunato, Luca; Leiknes, TorOve

    2017-01-01

    depth profile of the fouling. Data concerning the depth profile can be extracted and used to assess the fouling on the surface, in one or more aspects, the method can include providing an optical tomography spectrometer; optically positioning the optical

  13. Molecular Mechanisms of Ultrafiltration Membrane Fouling in Polymer-Flooding Wastewater Treatment: Role of Ions in Polymeric Fouling.

    Science.gov (United States)

    Liu, Guicai; Yu, Shuili; Yang, Haijun; Hu, Jun; Zhang, Yi; He, Bo; Li, Lei; Liu, Zhiyuan

    2016-02-02

    Polymer (i.e., anionic polyacrylamide (APAM)) fouling of polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes and its relationships to intermolecular interactions were investigated using atomic force microscopy (AFM). Distinct relations were obtained between the AFM force spectroscopy measurements and calculated fouling resistance over the concentration polarization layer (CPL) and gel layer (GL). The measured maximum adhesion forces (Fad,max) were closely correlated with the CPL resistance (Rp), and the proposed molecular packing property (largely based on the shape of AFM force spectroscopy curve) of the APAM chains was related to the GL resistance (Rg). Calcium ions (Ca(2+)) and sodium ions (Na(+)) caused more severe fouling. In the presence of Ca(2+), the large Rp corresponded to high foulant-foulant Fad,max, resulting in high flux loss. In addition, the Rg with Ca(2+) was minor, but the flux recovery rate after chemical cleaning was the lowest, indicating that Ca(2+) created more challenges in GL cleaning. With Na(+), the fouling behavior was complicated and concentration-dependent. The GL structures with Na(+), which might correspond to the proposed molecular packing states among APAM chains, played essential roles in membrane fouling and GL cleaning.

  14. Experimental study of particulate fouling onto heat exchanger elements

    International Nuclear Information System (INIS)

    Chandrasa

    1994-01-01

    An experimental study of particulate fouling onto tubular heat exchanger surfaces was carried out using sodium sulfate particles. An experimental apparatus equipped with an aerosol generator has been used to examine the deposition of small particles under controlled conditions. Two sets of experiments were performed. Firstly, the deposition against time of solid particles onto single heat exchanger tube in cross-flow was studied. The effects of a number variables such as particle size, gas velocity and temperature on the deposition was analysed. Secondly, the deposition for the aerosol particles as they passed through a bank of finned tubes was examined. The deposition patterns on various tubes depended on local conditions (velocity and temperature) within the bank. It was found that the fouling resistance increases as aerosol flow rate decreases. The smaller particles showed higher fouling resistance. (author) [fr

  15. Dynamic coating of mf/uf membranes for fouling mitigation

    KAUST Repository

    Tabatabai, S. Assiyeh Alizadeh

    2017-01-19

    A membrane system including an anti-fouling layer and a method of applying an anti-fouling layer to a membrane surface are provided. In an embodiment, the surface is a microfiltration (MF) or an ultrafiltration (UF) membrane surface. The anti-fouling layer can include a stimuli responsive layer and a dynamic protective layer applied over the stimuli responsive layer that can be a coating on a surface of the membrane. The stimuli responsive polymer layer can act as an adhesive prior to coating with the dynamic protective layer to aid in adhering the dynamic protective layer to the membrane surface. The dynamic protective layer can be formed by suitable nanoparticles that can prevent adhesion of foulants directly to the membrane surface. The stimuli responsive layer can be responsive to physio- chemical stimuli to cause a release of the stimuli responsive layer and the dynamic protective layer including foulants from the membrane.

  16. A Short Review of Membrane Fouling in Forward Osmosis Processes

    Science.gov (United States)

    Chun, Youngpil; Mulcahy, Dennis; Zou, Linda; Kim, In S.

    2017-01-01

    Interest in forward osmosis (FO) research has rapidly increased in the last decade due to problems of water and energy scarcity. FO processes have been used in many applications, including wastewater reclamation, desalination, energy production, fertigation, and food and pharmaceutical processing. However, the inherent disadvantages of FO, such as lower permeate water flux compared to pressure driven membrane processes, concentration polarisation (CP), reverse salt diffusion, the energy consumption of draw solution recovery and issues of membrane fouling have restricted its industrial applications. This paper focuses on the fouling phenomena of FO processes in different areas, including organic, inorganic and biological categories, for better understanding of this long-standing issue in membrane processes. Furthermore, membrane fouling monitoring and mitigation strategies are reviewed. PMID:28604649

  17. Fouling in a MBR system with rotating membrane discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Bentzen, Thomas Ruby; Christensen, Morten Lykkegaard

    concentrations and a clear effluent with no bacteria present in the permeate [1]. However, the process performance is limited by membrane fouling, which results in a lower productivity and higher energy demand and hence places demands for limitation of fouling and/or cleaning of the membranes. One way to do...... uses rotating ceramic membrane discs for creation of shear, which can be changed by controlling the membrane rotation speed of the membrane. Furthermore, the influence of shear on fouling is studied at different radii from the center of rotation, by dividing membranes into different concentric rings......Membrane bioreactors (MBR) are an attractive alternative solution for municipal and industrial wastewater treatment. The MBR, which is a combination of a bioreactor for sludge degradation and a membrane for separation, has the advantages of a low footprint, ability to handle high sludge...

  18. Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Huaqiang Chu

    2013-09-01

    Full Text Available The application of low pressure membranes (microfiltration/ultrafiltration has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM. This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.. Perspectives of further research are also discussed.

  19. Industrial fouling: problem characterization, economic assessment, and review of prevention, mitigation, and accommodation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Garrett-Price, B.A.; Smith, S.A.; Watts, R.L.

    1984-02-01

    A comprehensive overview of heat exchanger fouling in the manufacturing industries is provided. Specifically, this overview addresses: the characteristics of industrial fouling problems; the mitigation and accommodation techniques currently used by industry; and the types and magnitude of costs associated with industrial fouling. A detailed review of the fouling problems, costs and mitigation techniques is provided for the food, textile, pulp and paper, chemical, petroleum, cement, glass and primary metals industries.

  20. Effects of dissolved organic matters (DOMs) on membrane fouling in anaerobic ceramic membrane bioreactors (AnCMBRs) treating domestic wastewater.

    Science.gov (United States)

    Yue, Xiaodi; Koh, Yoong Keat Kelvin; Ng, How Yong

    2015-12-01

    Anaerobic membrane bioreactors (AnMBRs) have been regarded as a potential solution to achieve energy neutrality in the future wastewater treatment plants. Coupling ceramic membranes into AnMBRs offers great potential as ceramic membranes are resistant to corrosive chemicals such as cleaning reagents and harsh environmental conditions such as high temperature. In this study, ceramic membranes with pore sizes of 80, 200 and 300 nm were individually mounted in three anaerobic ceramic membrane bioreactors (AnCMBRs) treating real domestic wastewater to examine the treatment efficiencies and to elucidate the effects of dissolved organic matters (DOMs) on fouling behaviours. The average overall chemical oxygen demands (COD) removal efficiencies could reach around 86-88%. Although CH4 productions were around 0.3 L/g CODutilised, about 67% of CH4 generated was dissolved in the liquid phase and lost in the permeate. When filtering mixed liquor of similar properties, smaller pore-sized membranes fouled slower in long-term operations due to lower occurrence of pore blockages. However, total organic removal efficiencies could not explain the fouling behaviours. Liquid chromatography-organic carbon detection, fluorescence spectrophotometer and high performance liquid chromatography coupled with fluorescence and ultra-violet detectors were used to analyse the DOMs in detail. The major foulants were identified to be biopolymers that were produced in microbial activities. One of the main components of biopolymers--proteins--led to different fouling behaviours. It is postulated that the proteins could pass through porous cake layers to create pore blockages in membranes. Hence, concentrations of the DOMs in the soluble fraction of mixed liquor (SML) could not predict membrane fouling because different components in the DOMs might have different interactions with membranes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. High-resolution phylogenetic analysis of residual bacterial species of fouled membranes after NaOCl cleaning.

    Science.gov (United States)

    Navarro, Ronald R; Hori, Tomoyuki; Inaba, Tomohiro; Matsuo, Kazuyuki; Habe, Hiroshi; Ogata, Atsushi

    2016-05-01

    Biofouling is one of the major problems during wastewater treatment using membrane bioreactors (MBRs). In this regard, sodium hypochlorite (NaOCl) has been widely used to wash fouled membranes for maintenance and recovery purposes. Advanced chemical and biological characterization was conducted in this work to evaluate the performance of aqueous NaOCl solutions during washing of polyacrylonitrile membranes. Fouled membranes from MBR operations supplemented with artificial wastewater were washed with 0.1% and 0.5% aqueous NaOCl solutions for 5, 10 and 30 min. The changes in organics composition on the membrane surface were directly monitored by an attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectrometer. In addition, high-throughput Illumina sequencing of 16S rRNA genes was applied to detect any residual microorganisms. Results from ATR-FT-IR analysis indicated the complete disappearance of functional groups representing different fouling compounds after at least 30 min of treatment with 0.1% NaOCl. However, the biomolecular survey revealed the presence of residual bacteria even after 30 min of treatment with 0.5% NaOCl solution. Evaluation of microbial diversity of treated samples using Chao1, Shannon and Simpson reciprocal indices showed an increase in evenness while no significant decline in richness was observed. These implied that only the population of dominant species was mainly affected. The high-resolution phylogenetic analysis revealed the presence of numerous operational taxonomic units (OTUs) whose close relatives exhibit halotolerance. Some OTUs related to thermophilic and acid-resistant strains were also identified. Finally, the taxonomic analysis of recycled membranes that were previously washed with NaOCl also showed the presence of numerous halotolerant-related OTUs in the early stage of fouling. This further suggested the possible contribution of such chemical tolerance on their survival against NaOCl washing, which in turn

  2. Online fouling detection in electrical circulation heaters using neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Lalot, S. [M.E.T.I.E.R., Longuenesse Cedex (France); Universite de Valenciennes (France). LME; Lecoeuche, S. [M.E.T.I.E.R., Longuenesse Cedex (France); Universite de Lille (France). Laboratoire 13D

    2003-06-01

    Here is presented a method that is able to detect fouling during the service of a circulation electrical heater. The neural based technique is divided in two major steps: identification and classification. Each step uses a neural network, the connection weights of the first one being the inputs of the second network. Each step is detailed and the main characteristics and abilities of the two neural networks are given. It is shown that the method is able to discriminate fouling from viscosity modification that would lead to the same type of effect on the total heat transfer coefficient. (author)

  3. A New Concept of Ultrafiltration Fouling Control : Backwashing with Low Ionic Strength Water

    NARCIS (Netherlands)

    Li, S.

    2011-01-01

    Ultrafiltration (UF) is a proven technology in water treatment nowadays. However, fouling remains a major challenge in the operation of UF, especially in regard to colloidal NOM fouling. In general, a number of colloidal NOM fouling mechanisms may occur, such as adsorption, gel formation. Colloidal

  4. Protein fouling in carbon nanotubes enhanced ultrafiltration membrane: Fouling mechanism as a function of pH and ionic strength

    KAUST Repository

    Lee, Jieun; Jeong, Sanghyun; Ye, Yun; Chen, Vicki; Vigneswaran, Saravanamuthu; Leiknes, TorOve; Liu, Zongwen

    2016-01-01

    The protein fouling behavior was investigated in the filtration of the multiwall carbon nanotube (MWCNT) composite membrane and commercial polyethersulfone ultrafiltration (PES-UF) membrane. The effect of solution chemistry such as pH and ionic strength on the protein fouling mechanism was systematically examined using filtration model such as complete pore blocking, intermediate pore blocking and cake layer formation. The results showed that the initial permeate flux pattern and fouling behavior of the MWCNT composite membrane were significantly influenced by pH and ionic strength while the effect of PES-UF membrane on flux was minimal. In a lysozyme (Lys) filtration, the severe pore blocking in the MWCNT membrane was made by the combined effect of intra-foulant interaction (Lys-Lys) and electrostatic repulsion between the membrane surface and the foulant at pH 4.7 and 10.4, and increasing ionic strength where the foulant-foulant interaction and membrane-fouling interaction were weak. In a bovine serum albumin (BSA) filtration, severe pore blocking was reduced by less deposition via the electrostatic interaction between the membrane and foulant at pH 4.7 and 10.4 and increasing ionic strength, at which the interaction between the membrane and BSA became weak. For binary mixture filtration, the protein fouling mechanism was more dominantly affected by foulant-foulant interaction (Lys-BSA, Lys-Lys, and BSA-BSA) at pH 7.0 and increase in ionic strength. This research demonstrates that MWCNT membrane fouling can be alleviated by changing pH condition and ionic strength based on the foulant-foulant interaction and the electrostatic interaction between the membrane and foulant.

  5. Protein fouling in carbon nanotubes enhanced ultrafiltration membrane: Fouling mechanism as a function of pH and ionic strength

    KAUST Repository

    Lee, Jieun

    2016-11-04

    The protein fouling behavior was investigated in the filtration of the multiwall carbon nanotube (MWCNT) composite membrane and commercial polyethersulfone ultrafiltration (PES-UF) membrane. The effect of solution chemistry such as pH and ionic strength on the protein fouling mechanism was systematically examined using filtration model such as complete pore blocking, intermediate pore blocking and cake layer formation. The results showed that the initial permeate flux pattern and fouling behavior of the MWCNT composite membrane were significantly influenced by pH and ionic strength while the effect of PES-UF membrane on flux was minimal. In a lysozyme (Lys) filtration, the severe pore blocking in the MWCNT membrane was made by the combined effect of intra-foulant interaction (Lys-Lys) and electrostatic repulsion between the membrane surface and the foulant at pH 4.7 and 10.4, and increasing ionic strength where the foulant-foulant interaction and membrane-fouling interaction were weak. In a bovine serum albumin (BSA) filtration, severe pore blocking was reduced by less deposition via the electrostatic interaction between the membrane and foulant at pH 4.7 and 10.4 and increasing ionic strength, at which the interaction between the membrane and BSA became weak. For binary mixture filtration, the protein fouling mechanism was more dominantly affected by foulant-foulant interaction (Lys-BSA, Lys-Lys, and BSA-BSA) at pH 7.0 and increase in ionic strength. This research demonstrates that MWCNT membrane fouling can be alleviated by changing pH condition and ionic strength based on the foulant-foulant interaction and the electrostatic interaction between the membrane and foulant.

  6. Factors Influencing Membrane fouling in the MBR Process

    Directory of Open Access Journals (Sweden)

    Parvin Nahid

    2018-01-01

    Full Text Available Biological processes of wastewater treatmnent have found wide applications due to their lower costs and higher efficiency. Membrane bioreactors (MBR’s form one group of such processes in which membrane fouling is of great importance. Efficiency of critical flux (CF has been proved to be a parameter effective in fouling control (CF. CF is itself influenced by three main groups of variables that include sludge parameters, operating conditions, and membrane types. In this stidy, the effects of such factors as trans-membrane pressure, protein and carbohydrate concentrations in extracellular polymeric substances (EPS, and soluble microbial products (SMP on CF were investigated in a submerged MBR.  Moreover, the effects of such operating conditions as periodic and continuous suctions at two sludge concentrations were studied. It was found that increasing flux led to enhanced membrane fouling rates. Extracellular polymeric substances (EPS were found to have no relations with critical flux (CF, probably because EPS are mostly found as bigger flocks. Finally, a reverse relationship was established between CF and carbohydrate concentration of the SMP. Membrane fouling control was observed to be positively affected by the rest modes during periodic suctions.

  7. Fouling layer characterization and pore-blocking mechanisms in an ...

    African Journals Online (AJOL)

    Fouling layer characterization and pore-blocking mechanisms in an UF membrane externally coupled to a UASB reactor. ... Regarding pore-blocking mechanisms, standard blocking was the predominant mechanism at the beginning of filtration, coexisting at the end of it with cake filtration. In the first filtration cycle (1 h), after ...

  8. Artificial cilia for microparticle manipulation and anti-fouling

    NARCIS (Netherlands)

    Zhang, S.; Wang, Y.; den Toonder, J.M.J.

    2016-01-01

    The (bio-)fouling of surfaces submerged in liquid forms serious a problem for many applications. One inspiration to address this issue is the use of cilia which, in nature, are found very effective in particle manipulation. We have fabricated magnetically actuated artificial cilia (MAAC) using a

  9. Biomimetic non-fouling surfaces: extending the concepts

    Czech Academy of Sciences Publication Activity Database

    Pop-Georgievski, Ognen; Rodriguez-Emmenegger, Cesar; de los Santos Pereira, Andres; Proks, Vladimír; Brynda, Eduard; Rypáček, František

    2013-01-01

    Roč. 1, č. 22 (2013), s. 2859-2867 ISSN 2050-750X R&D Projects: GA ČR GAP205/12/1702; GA MŠk(CZ) LH13178; GA ČR GAP108/11/1857 Institutional support: RVO:61389013 Keywords : non-fouling * polymer brushes * polydopamine Subject RIV: CD - Macromolecular Chemistry

  10. A microfluidic membrane chip for in situ fouling characterization

    NARCIS (Netherlands)

    Ngene, I.S.; Lammertink, Rob G.H.; Wessling, Matthias; van der Meer, Walterus Gijsbertus Joseph

    2010-01-01

    A new method for non-invasive in situ monitoring of a microfiltration process is described. In microfiltration systems, local information on the deposition characteristics can be used to determine the cake behavior during a filtration run. Typically, non-invasive methods of fouling study are

  11. Influence of membrane properties on fouling in submerged membrane bioreactors

    NARCIS (Netherlands)

    van der Marel, P.; Zwijnenburg, A.; Kemperman, Antonius J.B.; Wessling, Matthias; Temmink, Hardy; van der Meer, Walterus Gijsbertus Joseph

    2010-01-01

    Polymeric flat-sheet membranes with different properties were used in filtration experiments with activated sludge from a pilot-scale MBR to investigate the influence of membrane pore size, surface porosity, pore morphology, and hydrophobicity on membrane fouling. An improved flux-step method was

  12. Influence of membrane properties on fouling in MBRs

    NARCIS (Netherlands)

    van der Marel, P.

    2009-01-01

    The membrane bioreactor (MBR) applies membranes for separating activated sludge and the purified water in the activated sludge process used for wastewater treatment. Membrane fouling occurs by activated sludge material depositing on the membrane surface or inside the membrane pores. The subject of

  13. Two-dimensional stochastic modeling of membrane fouling

    NARCIS (Netherlands)

    Wessling, Matthias

    2001-01-01

    The phenomenon of fouling of microfiltration membranes by much smaller particles such as proteins is described by a new developed simulation algorithm based on diffusion limited aggregation simulation techniques. The model specifies the membrane morphology explicitly and allows to (a) characterize

  14. Ion exchange resin fouling of molybdenum in recovery uranium processess

    International Nuclear Information System (INIS)

    Zhang Guowei; Zhao Guirong

    1990-09-01

    The relationship between anion exchange resin fouling and molybdic acid polymerization was studied. By using potentiometer titration and laser-Raman spectroscopy the relationship of molybdic acid polymerization and the pH value of solution or the molybdenum concentration was determined. It was shown that as the concentration of initial molybdenum in solution decreases from 0.2 mol/L to 0.5 mmol/L, the pH value of starting polymerization decreased from 6.5 to 4.5. The experimental results show that the fouling of 201 x 7 resin in the acidic solution is mainly caused by the adsorbing of Mo 3 O 26 4- ion and occupying the exchange radical site of the resin. Under the leaching conditions the molybdenum and phosphate existing in the leaching liquor can form 12-molybdo-phosphate ion. It also leads to resin fouling. The molybdenum on the fouled resin can synergically be desorbed by mixed desorbents containing ammonium hydroxide and ammonium sulfate. The desorbed resin can be used for uranium adsorption and the desorbed molybdenum can be recovered by ion exchange method

  15. Temperature and body weight affect fouling of pig pens

    NARCIS (Netherlands)

    Aarnink, A.J.A.; Schrama, J.W.; Heetkamp, M.J.W.; Stefanowska, J.; Huynh, T.T.T.

    2006-01-01

    Fouling of the solid lying area in pig housing is undesirable for reasons of animal welfare, animal health, environmental pollution, and labor costs. In this study the influence of temperature on the excreting and lying behavior of growing-finishing pigs of different BW (25, 45, 65, 85, or 105 kg)

  16. Water hammer reduces fouling during natural water ultrafiltration.

    Science.gov (United States)

    Broens, F; Menne, D; Pothof, I; Blankert, B; Roesink, H D W; Futselaar, H; Lammertink, R G H; Wessling, M

    2012-03-15

    Today's ultrafiltration processes use permeate flow reversal to remove fouling deposits on the feed side of ultrafiltration membranes. We report an as effective method: the opening and rapid closing of a valve on the permeate side of an ultrafiltration module. The sudden valve closure generates pressure fluctuations due to fluid inertia and is commonly known as "water hammer". Surface water was filtrated in hollow fiber ultrafiltration membranes with a small (5%) crossflow. Filtration experiments above sustainable flux levels (>125 l (m2h)(-1)) show that a periodic closure of a valve on the permeate side improves filtration performance as a consequence of reduced fouling. It was shown that this effect depends on flux and actuation frequency of the valve. The time period that the valve was closed proved to have no effect on filtration performance. The pressure fluctuations generated by the sudden stop in fluid motion due to the valve closure are responsible for the effect of fouling reduction. High frequency recording of the dynamic pressure evolution shows water hammer related pressure fluctuations to occur in the order of 0.1 bar. The pressure fluctuations were higher at higher fluxes (higher velocities) which is in agreement with the theory. They were also more effective at higher fluxes with respect to fouling mitigation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Identifying and quantifying proteolytic events and the natural N terminome by terminal amine isotopic labeling of substrates.

    Science.gov (United States)

    Kleifeld, Oded; Doucet, Alain; Prudova, Anna; auf dem Keller, Ulrich; Gioia, Magda; Kizhakkedathu, Jayachandran N; Overall, Christopher M

    2011-09-22

    Analysis of the sequence and nature of protein N termini has many applications. Defining the termini of proteins for proteome annotation in the Human Proteome Project is of increasing importance. Terminomics analysis of protease cleavage sites in degradomics for substrate discovery is a key new application. Here we describe the step-by-step procedures for performing terminal amine isotopic labeling of substrates (TAILS), a 2- to 3-d (depending on method of labeling) high-throughput method to identify and distinguish protease-generated neo-N termini from mature protein N termini with all natural modifications with high confidence. TAILS uses negative selection to enrich for all N-terminal peptides and uses primary amine labeling-based quantification as the discriminating factor. Labeling is versatile and suited to many applications, including biochemical and cell culture analyses in vitro; in vivo analyses using tissue samples from animal and human sources can also be readily performed. At the protein level, N-terminal and lysine amines are blocked by dimethylation (formaldehyde/sodium cyanoborohydride) and isotopically labeled by incorporating heavy and light dimethylation reagents or stable isotope labeling with amino acids in cell culture labels. Alternatively, easy multiplex sample analysis can be achieved using amine blocking and labeling with isobaric tags for relative and absolute quantification, also known as iTRAQ. After tryptic digestion, N-terminal peptide separation is achieved using a high-molecular-weight dendritic polyglycerol aldehyde polymer that binds internal tryptic and C-terminal peptides that now have N-terminal alpha amines. The unbound naturally blocked (acetylation, cyclization, methylation and so on) or labeled mature N-terminal and neo-N-terminal peptides are recovered by ultrafiltration and analyzed by tandem mass spectrometry (MS/MS). Hierarchical substrate winnowing discriminates substrates from the background proteolysis products and

  18. Membrane fouling mechanism transition in relation to feed water composition

    KAUST Repository

    Myat, Darli Theint

    2014-12-01

    The impact of secondary effluent wastewater from the Eastern Treatment Plant (ETP), Melbourne, Australia, before and after ion exchange (IX) treatment and polyaluminium chlorohydrate (PACl) coagulation, on hydrophobic polypropylene (PP) and hydrophilic polyvinylidene fluoride (PVDF) membrane fouling was studied. Laboratory fouling tests were operated over 3-5 days with regular, intermittent backwash. During the filtration with PP membranes, organic rejection data indicated that humic adsorption on hydrophobic PP membrane occurred during the first 24h of filtration and contributed to fouling for both raw wastewater and pre-treated wastewaters. However, after the first 24h of filtration the contribution of humic substances to fouling diminished and biopolymers that contribute to cake layer development became more prominent in their contribution to the fouling rate. For PVDF membranes, the per cent removal of humic substances from both raw wastewater and pre-treated wastewaters was very small as indicated by no change in UV254 from the feed to the permeate over the filtration period, even during the early stages of filtration. This suggested that the hydrophobic PP membrane adsorbed humic substances while the hydrophilic PVDF membrane did not. The highest mass of biopolymer removal by each PVDF membrane was from ETP water followed by PACl and IX treated water respectively. This was possibly due to differences in the backwashing efficiency linked to the filter cake contributed by biopolymers. Hydraulic backwashing was more effective during the later stages of filtration for the ETP water compared to IX and PACl treated waters, indicating that the filter cake contributed by ETP biopolymers was more extensively removed by hydraulic backwashing. It was proposed that humic substances may act to stabilise biopolymers in solution and that removing humics substances by coagulation or IX results in greater adhesive forces between the biopolymers and membrane/filter cake

  19. Are anti-fouling effects in coralline algae species specific?

    Directory of Open Access Journals (Sweden)

    Alexandre Bigio Villas Bôas

    2004-03-01

    Full Text Available The crustose coralline algae are susceptible to be covered by other algae, which in turn can be affected by anti-fouling effects. In this study the hypothesis tested was that these algae can inhibit the growth of epiphytes in a species specific way. In the laboratory, propagules of Sargassum furcatum and Ulva fasciata were liberated and cultivated on pieces of coralline algae and slide covers (controls and their survival and growth were compared. Spongites and Hydrolithon significantly inhibited the growth of U. fasciata but not Sargassum. In the field, pieces of three species of live and dead coralline algae and their copies in epoxy putty discs were fixed on the rock. After one month epiphytic algae were identified and their dry mass quantified. Lithophyllum did not affect the epiphyte growth. In contrast Spongites and an unidentified coralline significantly inhibited the growth of Enteromorpha spp., Ulva fasciata and Hincksia mitchelliae. Colpomenia sinuosa was absent on all living crusts, but present on controls. Results show that the epiphyte-host relation depends on the species that are interacting. The sloughing of superficial cells of coralline crusts points to the possible action of physical anti-fouling effect, though a chemical one is not rejected.As algas calcárias crostosas são susceptíveis ao recobrimento por outras algas, entretanto, estas podem ser afetadas por efeitos anti-incrustantes. Neste estudo foi testada a hipótese de que estas algas possam inibir o crescimento somente de algumas espécies de epífitas. No laboratório, propágulos de Sargassum furcatum e Ulva fasciata foram liberados e cultivados sobre pedaços de algas calcárias e lamínulas de microscopia (controle e as suas sobrevivência e crescimento comparadas. Spongites e Hydrolithon inibiram significativamente o crescimento de U. fasciata, mas não de Sargassum. No campo, pedaços de três espécies de algas calcárias vivas, mortas e cópias destas em

  20. Rejection of micropollutants by clean and fouled forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo

    2011-12-01

    As forward osmosis (FO) gains attention as an efficient technology to improve wastewater reclamation processes, it is fundamental to determine the influence of fouling in the rejection of emerging contaminants (micropollutants). This study focuses on the rejection of 13 selected micropollutants, spiked in a secondary wastewater effluent, by a FO membrane, using Red Sea water as draw solution (DS), differentiating the effects on the rejection caused by a clean and fouled membrane. The resulting effluent was then desalinated at low pressure with a reverse osmosis (RO) membrane, to produce a high quality permeate and determine the rejection with a coupled forward osmosis - low pressure reverse osmosis (FO-LPRO) system. When considering only FO with a clean membrane, the rejection of the hydrophilic neutral compounds was between 48.6% and 84.7%, for the hydrophobic neutrals the rejection ranged from 40.0% to 87.5%, and for the ionic compounds the rejections were between 92.9% and 96.5%. With a fouled membrane, the rejections were between 44.6% and 95.2%, 48.7%-91.5% and 96.9%-98.6%, respectively. These results suggest that, except for the hydrophilic neutral compounds, the rejection of the micropollutants is increased by the presence of a fouling layer, possibly due to the higher hydrophilicity of the FO fouled membrane compared to the clean one, the increased adsorption capacity of hydrophilic compounds and reduced mass transport capacity, membrane swelling, and the higher negative charge of the membrane surface, related to the foulants composition, mainly NOM acids (carboxylic radicals) and polysaccharides or polysaccharide-like substances. However, when coupled with RO, the rejections in both cases increased above 96%. The coupled FO-LPRO system was an effective double barrier against the selected micropollutants. © 2011 Elsevier Ltd.

  1. Rejection of micropollutants by clean and fouled forward osmosis membrane

    KAUST Repository

    Valladares Linares, Rodrigo; Yangali-Quintanilla, Victor; Li, Zhenyu; Amy, Gary L.

    2011-01-01

    As forward osmosis (FO) gains attention as an efficient technology to improve wastewater reclamation processes, it is fundamental to determine the influence of fouling in the rejection of emerging contaminants (micropollutants). This study focuses on the rejection of 13 selected micropollutants, spiked in a secondary wastewater effluent, by a FO membrane, using Red Sea water as draw solution (DS), differentiating the effects on the rejection caused by a clean and fouled membrane. The resulting effluent was then desalinated at low pressure with a reverse osmosis (RO) membrane, to produce a high quality permeate and determine the rejection with a coupled forward osmosis - low pressure reverse osmosis (FO-LPRO) system. When considering only FO with a clean membrane, the rejection of the hydrophilic neutral compounds was between 48.6% and 84.7%, for the hydrophobic neutrals the rejection ranged from 40.0% to 87.5%, and for the ionic compounds the rejections were between 92.9% and 96.5%. With a fouled membrane, the rejections were between 44.6% and 95.2%, 48.7%-91.5% and 96.9%-98.6%, respectively. These results suggest that, except for the hydrophilic neutral compounds, the rejection of the micropollutants is increased by the presence of a fouling layer, possibly due to the higher hydrophilicity of the FO fouled membrane compared to the clean one, the increased adsorption capacity of hydrophilic compounds and reduced mass transport capacity, membrane swelling, and the higher negative charge of the membrane surface, related to the foulants composition, mainly NOM acids (carboxylic radicals) and polysaccharides or polysaccharide-like substances. However, when coupled with RO, the rejections in both cases increased above 96%. The coupled FO-LPRO system was an effective double barrier against the selected micropollutants. © 2011 Elsevier Ltd.

  2. Temporal and spatial variation in the fouling of silicone coatings in Pearl Harbor, Hawaii.

    Science.gov (United States)

    Holm, E R; Nedved, B T; Phillips, N; Deangelis, K L; Hadfield, M G; Smith, C M

    2000-01-01

    An antifouling or foul-release coating cannot be globally effective if it does not perform well in a range of environmental conditions, against a diversity of fouling organisms. From 1996 to 1998, the field test sites participating in the United States Navy's Office of Naval Research 6.2 Biofouling program examined global variation in the performance of 3 silicone foul-release coatings, viz. GE RTV11, Dow Corning RTV 3140, and Intersleek (International Coatings Ltd), together with a control anticorrosive coating (Ameron Protective Coatings F-150 series). At the University of Hawaii's test site in Pearl Harbor, significant differences were observed among the coatings in the rate of accumulation of fouling. The control coating failed rapidly; after 180-220 d immersion a community dominated by molluscs and sponges developed that persisted for the remainder of the experiment. Fouling of the GE and Dow Corning silicone coatings was slower, but eventually reached a similar community structure and coverage as the control coatings. The Intersleek coating remained lightly fouled throughout the experiment. Spatial variation in the structure of the community fouling the coatings was observed, but not in the extent of fouling. The rate of accumulation of fouling reflected differences among the coatings in adhesion of the tubeworm Hydroides elegans. The surface properties of these coatings may have affected the rate of fouling and the structure of the fouling community through their influence on larval settlement and subsequent interactions with other residents, predators, and the physical environment.

  3. Intelligent Image Recognition System for Marine Fouling Using Softmax Transfer Learning and Deep Convolutional Neural Networks

    Directory of Open Access Journals (Sweden)

    C. S. Chin

    2017-01-01

    Full Text Available The control of biofouling on marine vessels is challenging and costly. Early detection before hull performance is significantly affected is desirable, especially if “grooming” is an option. Here, a system is described to detect marine fouling at an early stage of development. In this study, an image of fouling can be transferred wirelessly via a mobile network for analysis. The proposed system utilizes transfer learning and deep convolutional neural network (CNN to perform image recognition on the fouling image by classifying the detected fouling species and the density of fouling on the surface. Transfer learning using Google’s Inception V3 model with Softmax at last layer was carried out on a fouling database of 10 categories and 1825 images. Experimental results gave acceptable accuracies for fouling detection and recognition.

  4. Fouling mitigation in membrane distillation processes during ammonia stripping from pig manure

    DEFF Research Database (Denmark)

    Zarebska, Agata; Amor, Angel Cid; Ciurkot, Klaudia

    2015-01-01

    Over time fouling leads to membrane wetting. This is the biggest obstacle to widespread use of membrane distillation (MD) for ammonia removal from animal slurry. Feed pretreatment and cleaning strategies of membrane surfaces are the most common methods to prevent or diminish fouling phenomena....... This study investigates preliminary fouling of polypropylene (PP) and polytetrafluoroethylene (PTFE) membranes. A model manure solution was used as feed. In addition cleaning efficiencies with deionized water, NaOH/citric acid, and Novadan agents were studied. Further microfiltration and ultrafiltration were...... examined as manure pretreatment to diminish fouling. To this end polyvinylidene fluoride membranes (PVDF 0.2 µm and 150 kDa respectively) were used. Organic fouling was shown to be dominant. For the model manure solution the fouling comprised lipids, carbohydrates and proteins. For pig slurry the fouling...

  5. Nanoparticle fouling and its combination with organic fouling during forward osmosis process for silver nanoparticles removal from simulated wastewater

    Science.gov (United States)

    Zhao, Yanxiao; Wang, Xinhua; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-05-01

    The increasing and wide application of silver nanoparticles (Ag NPs) has resulted in their appearance in wastewater. In consideration of their potential toxicity and environmental impacts, it is necessary to find effective technology for their removal from wastewater. Here, forward osmosis (FO) membrane was applied for Ag NPs removal from wastewater, and single and combined fouling of nanoparticles and organic macromolecules were further investigated during the FO process. The findings demonstrated that FO membrane can effectively remove Ag NPs from wastewater due to its high rejection performance. Fouling tests indicated that water flux declined appreciably even at the beginning of the single Ag NPs fouling test, and more remarkable flux decline and larger amounts of deposited Ag NPs were observed with an increase of Ag NPs concentration. However, the addition of bovine serum albumin (BSA) could effectively alleviate the FO membrane fouling induced by Ag NPs. The interaction between Ag NPs and BSA was responsible for this phenomenon. BSA can easily form a nanoparticle-protein corona surrounded nanoparticles, which prevented nanoparticles from aggregation due to the steric stabilization mechanism. Furthermore, the interaction between BSA and Ag NPs occurred not only in wastewater but also on FO membrane surface.

  6. FOULING CHARACTERIZATION OF MEMBRANE CONTACTORS USED FOR THE RECOVERY AND CONCENTRATION OF AMMONIA FROM UNDIGESTED PIG SLURRY

    DEFF Research Database (Denmark)

    Zarebska, Agata; Norddahl, Birgir; Christensen, Knud Villy

    2012-01-01

    The main obstacle impeding implementation of membrane contactors for the recovery and concentration of ammonia from swine manure is the phenomena of membrane fouling. Fouling is defined as the accumulation of suspended or dissolved substances on the membrane surface and/or within its pores. Due...... to the different types of fouling which can occur in a membrane system, characterization of fouling is a complex problem. Fouling intensity, morphology and composition of fouling layers has been determined using Scanning Electron Microscopy, X-ray Energy Dispersive Spectrometry and Attenuated Total Reflectance...... Infrared Spectrometry. Based on the analysis of fouled membranes, it is concluded that membrane fouling is dominated by organic fouling in combination with biofouling mainly due to adsorption and deposition of undegraded organic matter. The average fouling layer thickness was estimated to 127.4 μm after...

  7. The AFFORD clinical decision aid to identify emergency department patients with atrial fibrillation at low risk for 30-day adverse events.

    Science.gov (United States)

    Barrett, Tyler W; Storrow, Alan B; Jenkins, Cathy A; Abraham, Robert L; Liu, Dandan; Miller, Karen F; Moser, Kelly M; Russ, Stephan; Roden, Dan M; Harrell, Frank E; Darbar, Dawood

    2015-03-15

    There is wide variation in the management of patients with atrial fibrillation (AF) in the emergency department (ED). We aimed to derive and internally validate the first prospective, ED-based clinical decision aid to identify patients with AF at low risk for 30-day adverse events. We performed a prospective cohort study at a university-affiliated tertiary-care ED. Patients were enrolled from June 9, 2010, to February 28, 2013, and followed for 30 days. We enrolled a convenience sample of patients in ED presenting with symptomatic AF. Candidate predictors were based on ED data available in the first 2 hours. The decision aid was derived using model approximation (preconditioning) followed by strong bootstrap internal validation. We used an ordinal outcome hierarchy defined as the incidence of the most severe adverse event within 30 days of the ED evaluation. Of 497 patients enrolled, stroke and AF-related death occurred in 13 (3%) and 4 (aid included the following: age, triage vitals (systolic blood pressure, temperature, respiratory rate, oxygen saturation, supplemental oxygen requirement), medical history (heart failure, home sotalol use, previous percutaneous coronary intervention, electrical cardioversion, cardiac ablation, frequency of AF symptoms), and ED data (2 hours heart rate, chest radiograph results, hemoglobin, creatinine, and brain natriuretic peptide). The decision aid's c-statistic in predicting any 30-day adverse event was 0.7 (95% confidence interval 0.65, 0.76). In conclusion, in patients with AF in the ED, Atrial Fibrillation and Flutter Outcome Risk Determination provides the first evidence-based decision aid for identifying patients who are at low risk for 30-day adverse events and candidates for safe discharge. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. EDF steam generators fleet: In-operation monitoring of TSP blockage and tube fouling

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, P.; Gay, N.; Crinon, R. [Electricite De France (France)

    2012-07-01

    EDF operates 58 Pressurized Water Reactors in France. In the mid 2000‟s some of them have been affected by Steam Generators (SG) Tube Support Plates (TSP) blockage and U-tubes external surface fouling with iron oxides deposits due to corrosion of secondary-side components. These issues have been tackled by a global maintenance strategy of chemical cleanings and a method for in-operation monitoring of fouling and TSP blockage has been developed and is implemented since mid 2009. This monitoring is aimed at giving information for SG maintenance planning as regards non destructive examinations and chemical cleaning. This paper will first remind of the physical reasons of fouling and TSP blockage and identify the resulting stakes regarding safety and availability along with the action levers available to control both phenomena. Then details will be given on how in-operation monitoring of fouling and TSP blockage is carried out, using measurements of Wide Range water Level (WRL) and SG steam pressure during thermally stabilized periods. Information will also be given on how those data are analyzed and shared as well at a local as at a corporate level to participate in the planning of SG inspection and maintenance operations. Finally, possible refinements will be discussed, notably regarding the issue of WRL measurements reliability and the possibility to use the analysis of SG dynamic behavior during power transients to assess the TSP blockage ratio. In terms of „issues requiring discussion‟, the following are operational issues currently being investigated by EDF: 1. SG pressure can have quite large variations during one operating cycle (notably after a plant trip) and from one cycle to the other and generally pressure tends to decrease on a long-term basis. How can such variations be explained? What are the solutions to moderate/stop the pressure loss? 2. On some of the SG-models operated by EDF, hard curative Chemical Cleaning of the U-tubes didn't bring

  9. Understanding ozone mechanisms to alleviate ceramic membrane fouling

    Science.gov (United States)

    Chu, Irma Giovanna Llamosas

    Ceramic membranes are a strong prospect as an advanced treatment in the drinking water domain. But their high capital cost and the lack of specific research on their performance still discourage their application in this field. Thus, knowing that fouling is the main drawback experienced in filtration processes, this bench-scale study was aimed to assess the impact of an ozonation pre-treatment on the alleviation of the fouling of UF ceramic membranes. Preozonation and filtration steps were performed under two different pH and ozone doses. Chosen pH values were at the limits of natural surface waters range (6.5 and 8.5) to keep practicability. Raw water from the Thousand Isle's river at Quebec-Canada was used for the tests. The filtration setup involved an unstirred dead-end filtration cell operated at constant flux. Results showed that pre-oxidation by ozone indeed reduced the fouling degree of the membranes according to the dose applied (up to 60 and 85% for membranes 8 and 50 kDa, respectively). Direct NOM oxidation was found responsible for this effect as the presence of molecular ozone was not essential to achieve these results. In the context of this experiment, however, pH showed to be more effective than the ozonation pre-treatment to keep fouling at low levels: 70% lower at pH 6.5 than at pH 8.5 for un-ozonated waters, which was contrary to most of the literature found on the topic (Changwon, 2013; De Angelis & Fidalgo, 2013; Karnik et al., 2005; S. Lee & Kim, 2014). This behaviour results mainly from the operation mode used in the experiment, the electrical repulsions between MON molecules at basic pH that led to the accumulation of material on the feed side of the membranes (concentration polarisation) and ulterior cake formation. In addition, solution pH showed an influence in the definition of fouling mechanisms. At solution pH 6.5, which was precisely the isoelectric point of the membranes (+/-6.5), the blocking fouling mode was frequently detected

  10. Whole genome analysis of selected human and animal rotaviruses identified in Uganda from 2012 to 2014 reveals complex genome reassortment events between human, bovine, caprine and porcine strains.

    Science.gov (United States)

    Bwogi, Josephine; Jere, Khuzwayo C; Karamagi, Charles; Byarugaba, Denis K; Namuwulya, Prossy; Baliraine, Frederick N; Desselberger, Ulrich; Iturriza-Gomara, Miren

    2017-01-01

    Rotaviruses of species A (RVA) are a common cause of diarrhoea in children and the young of various other mammals and birds worldwide. To investigate possible interspecies transmission of RVAs, whole genomes of 18 human and 6 domestic animal RVA strains identified in Uganda between 2012 and 2014 were sequenced using the Illumina HiSeq platform. The backbone of the human RVA strains had either a Wa- or a DS-1-like genetic constellation. One human strain was a Wa-like mono-reassortant containing a DS-1-like VP2 gene of possible animal origin. All eleven genes of one bovine RVA strain were closely related to those of human RVAs. One caprine strain had a mixed genotype backbone, suggesting that it emerged from multiple reassortment events involving different host species. The porcine RVA strains had mixed genotype backbones with possible multiple reassortant events with strains of human and bovine origin.Overall, whole genome characterisation of rotaviruses found in domestic animals in Uganda strongly suggested the presence of human-to animal RVA transmission, with concomitant circulation of multi-reassortant strains potentially derived from complex interspecies transmission events. However, whole genome data from the human RVA strains causing moderate and severe diarrhoea in under-fives in Uganda indicated that they were primarily transmitted from person-to-person.

  11. Amphiphilic polymer based on fluoroalkyl and PEG side chains for fouling release coating

    Science.gov (United States)

    Cong, W. W.; Wang, K.; Yu, X. Y.; Zhang, H. Q.; Lv, Z.; Gui, T. J.

    2017-12-01

    Under static conditions, fouling release coating could not express good release property to marine organisms. Amphiphilic polymer with mixture of fluorinated monomer and short side group of polyethylene glycol (PEG) was synthesized. And also we studied the ability of amphiphilic polymer to influence the surface properties and how it controlled the adhesion of marine organisms to coated surfaces. By incorporating fluorinated monomer and PEG side chain into the polymer, the effect of incorporating both polar and non-polar groups on fouling-release coating could be studied. The dry surface was characterized by three-dimensional digital microscopy and scanning electron microscopy (SEM), and the morphology of the amphiphilic fouling release coating showed just like flaky petal. The amphiphilic polymer in fouling release coating tended to reconstruct in water, and the ability was examined by static contact angle, which was smaller than the PDMS (polydimethylsiloxane) fouling release coating. Also surface energy was calculated by three solvents, and surface energy of amphiphilic fouling release coating was higher than that of the PDMS fouling release coating. To understand more about its fouling release property, seawater exposure method was adopted in gulf of Qingdao port. Fewer diatoms Navicula were found in biofilm after using amphiphilic fouling release coating. In general, coating containing both PEG and fluorinated side chain possessed certain fouling release property.

  12. Impact of effluent organic matter on low-pressure membrane fouling in tertiary treatment

    KAUST Repository

    Ayache, C.; Pidou, Marc; Croue, Jean-Philippe; Labanowski, Jé rô me; Poussade, Yvan; Tazi-Pain, Annie; Keller, Jurg R.; Gernjak, Wolfgang

    2013-01-01

    This study aims at comparing low-pressure membrane fouling obtained with two different secondary effluents at bench and pilot-scale based on the determination of two fouling indices: the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI). The main objective was to investigate if simpler and less costly bench-scale experimentation can substitute for pilot-scale trials when assessing the fouling potential of secondary effluent in large scale membrane filtration plants producing recycled water. Absolute values for specific flux and total fouling index for the bench-scale system were higher than those determined from pilot-scale, nevertheless a statistically significant correlation (r2 = 0.63, α = 0.1) was obtained for the total fouling index at both scales. On the contrary no such correlation was found for the hydraulically irreversible fouling index. Advanced water characterization tools such as excitation-emission matrix fluorescence spectroscopy (EEM) and liquid chromatography with organic carbon detection (LC-OCD) were used for the characterization of foulants. On the basis of statistical analysis, biopolymers and humic substances were found to be the major contribution to total fouling (r2 = 0.95 and r2 = 0.88, respectively). Adsorption of the low molecular weight neutral compounds to the membrane was attributed to hydraulically irreversible fouling (r2 = 0.67). © 2013 Elsevier Ltd.

  13. Fouling on ion-exchange membranes: Classification, characterization and strategies of prevention and control.

    Science.gov (United States)

    Mikhaylin, Sergey; Bazinet, Laurent

    2016-03-01

    The environmentally friendly ion-exchange membrane (IEM) processes find more and more applications in the modern industries in order to demineralize, concentrate and modify products. Moreover, these processes may be applied for the energy conversion and storage. However, the main drawback of the IEM processes is a formation of fouling, which significantly decreases the process efficiency and increases the process cost. The present review is dedicated to the problematic of IEM fouling phenomena. Firstly, the major types of IEM fouling such as colloidal fouling, organic fouling, scaling and biofouling are discussed along with consideration of the main factors affecting fouling formation and development. Secondly, the review of the possible methods of IEM fouling characterization is provided. This section includes the methods of fouling visualization and characterization as well as methods allowing investigations of characteristics of the fouled IEMs. Eventually, the reader will find the conventional and modern strategies of prevention and control of different fouling types. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Impact of effluent organic matter on low-pressure membrane fouling in tertiary treatment

    KAUST Repository

    Ayache, C.

    2013-05-01

    This study aims at comparing low-pressure membrane fouling obtained with two different secondary effluents at bench and pilot-scale based on the determination of two fouling indices: the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI). The main objective was to investigate if simpler and less costly bench-scale experimentation can substitute for pilot-scale trials when assessing the fouling potential of secondary effluent in large scale membrane filtration plants producing recycled water. Absolute values for specific flux and total fouling index for the bench-scale system were higher than those determined from pilot-scale, nevertheless a statistically significant correlation (r2 = 0.63, α = 0.1) was obtained for the total fouling index at both scales. On the contrary no such correlation was found for the hydraulically irreversible fouling index. Advanced water characterization tools such as excitation-emission matrix fluorescence spectroscopy (EEM) and liquid chromatography with organic carbon detection (LC-OCD) were used for the characterization of foulants. On the basis of statistical analysis, biopolymers and humic substances were found to be the major contribution to total fouling (r2 = 0.95 and r2 = 0.88, respectively). Adsorption of the low molecular weight neutral compounds to the membrane was attributed to hydraulically irreversible fouling (r2 = 0.67). © 2013 Elsevier Ltd.

  15. Robust design optimization method for centrifugal impellers under surface roughness uncertainties due to blade fouling

    Science.gov (United States)

    Ju, Yaping; Zhang, Chuhua

    2016-03-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  16. Using Remote Sensing and High-Resolution Digital Elevation Models to Identify Potential Erosional Hotspots Along River Channels During High Discharge Storm Events

    Science.gov (United States)

    Orland, E. D.; Amidon, W. H.

    2017-12-01

    As global warming intensifies, large precipitation events and associated floods are becoming increasingly common. Channel adjustments during floods can occur by both erosion and deposition of sediment, often damaging infrastructure in the process. There is thus a need for predictive models that can help managers identify river reaches that are most prone to adjustment during storms. Because rivers in post-glacial landscapes often flow over a mixture of bedrock and alluvial substrates, the identification of bedrock vs. alluvial channel reaches is an important first step in predicting vulnerability to channel adjustment during flood events, especially because bedrock channels are unlikely to adjust significantly, even during floods. This study develops a semi-automated approach to predicting channel substrate using a high-resolution LiDAR-derived digital elevation model (DEM). The study area is the Middlebury River in Middlebury, VT-a well-studied watershed with a wide variety of channel substrates, including reaches with documented channel adjustments during recent flooding events. Multiple metrics were considered for reference—such as channel width and drainage area—but the study utilized channel slope as a key parameter for identifying morphological variations within the Middlebury River. Using data extracted from the DEM, a power law was fit to selected slope and drainage area values for each branch in order to model idealized slope-drainage area relationships, which were then compared with measured slope-drainage area relationships. Differences in measured slope minus predicted slope (called delta-slope) are shown to help predict river channel substrate. Compared with field observations, higher delta-slope values correlate with more stable, boulder rich channels or bedrock gorges; conversely the lowest delta-slope values correlate with flat, sediment rich alluvial channels. The delta-slope metric thus serves as a reliable first-order predictor of channel

  17. Contribution of effluent organic matter (EfOM) to ultrafiltration (UF) membrane fouling: Isolation, characterization, and fouling effect of EfOM fractions

    KAUST Repository

    Zheng, Xing; Khan, Muhammad; Croue, Jean-Philippe

    2014-01-01

    EfOM has been regarded as a major organic foulant resulting in UF membrane fouling in wastewater reclamation. To investigate fouling potential of different EfOM fractions, the present study isolated EfOM into hydrophobic neutrals (HPO-N), colloids

  18. Experimental and numerical investigation of gas side particulate fouling onto heat exchanger tubes

    International Nuclear Information System (INIS)

    Bailer, Frederic

    1998-01-01

    This work deals with gas side particulate fouling onto heat exchanger tubes. An experimental and numerical investigation was carried out. By means of a new testing loop designed for this study, the deposit kinetics were obtained in dust-controlled conditions at the beginning of the fouling process. Experimental results pointed out the existence of various transport regimes: for sub-micronic particles, convective diffusion augmented by thermophoresis in the presence of a temperature gradient governs the particle deposition; inertial impaction controls the super-micronic particles deposition: in the intermediate granulometric range, combined action of particle inertia and thermophoresis must be considered. Moreover, measurements on an other testing loop using a more concentrated aerosol allowed us to point out the modification of the mechanisms with time and the influence of the deposit shape. A numerical model predicting the particle deposition, based on the TRIO software and an Eulerian-Lagrangian approach, was developed and validated against experimental results from the literature and from our study. Numerical approach gave us an accurate understanding of the phenomena by means of local parameters computations. In this way, the different mechanisms which control particulate deposition onto heat exchangers tubes were identified and modelled, especially before the onset of the inertial impaction. (author) [fr

  19. Effect of barnacle fouling on ship resistance and powering.

    Science.gov (United States)

    Demirel, Yigit Kemal; Uzun, Dogancan; Zhang, Yansheng; Fang, Ho-Chun; Day, Alexander H; Turan, Osman

    2017-11-01

    Predictions of added resistance and the effective power of ships were made for varying barnacle fouling conditions. A series of towing tests was carried out using flat plates covered with artificial barnacles. The tests were designed to allow the examination of the effects of barnacle height and percentage coverage on the resistance and effective power of ships. The drag coefficients and roughness function values were evaluated for the flat plates. The roughness effects of the fouling conditions on the ships' frictional resistances were predicted. Added resistance diagrams were then plotted using these predictions, and powering penalties for these ships were calculated using the diagrams generated. The results indicate that the effect of barnacle size is significant, since a 10% coverage of barnacles each 5 mm in height caused a similar level of added power requirements to a 50% coverage of barnacles each 1.25 mm in height.

  20. Beer Clarification with polysulfone membrane and study on fouling mechanism

    Directory of Open Access Journals (Sweden)

    Ricardo Cardoso de Oliveira

    2011-12-01

    Full Text Available The aims of the present work were to study the relationship between the fluxes, permeate quality, and fouling mechanism. A polysulfone membrane with 100 KDa and 0.12 m² of surface area was used. Permeate fluxes were measured for different pressures (0.5, 1.0, 1.5, and 2.0 bar at the same temperature of 8 ºC. The fluxes measured for each pressure ranged from 22, 24, 27 and 30 kg h-1m-2 at 0.5, 1.0, 1.5 and 2.0 bar, respectively. Samples of the feed and permeate were analyzed for pH, color, turbidity, sugar, bitterness, and proteins. The fouling mechanisms observed were cake filtration, partial pore blocking, and complete pore blocking.

  1. Characterization of a non-fouling ultrafiltration membrane

    DEFF Research Database (Denmark)

    Wei, J.; Helm, G.S.; Corner-Walker, N.

    2006-01-01

    This report describes the properties of surface-modified poly(vinylidene fluoride) (PVDF) membranes. These membranes were created by coating hydrophilic polymers on the support PVDF membrane to reduce the tendency to protein fouling. The modified membranes with different molecular weight cut......-off (MWCO) were characterized by filtration studies using bovine serum albumin (BSA) and an enzyme solution as test media, and the membranes exhibited the non-fouling property. The surface chemistry of the unmodified and modified PVDF membranes was characterized by X-ray photoelectron spectroscopy (XPS......) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). These surface sensitive techniques were used to confirm the successful surface modification. ToF-SIMS imaging visualizes the distribution of the coating layer on the PVDF membrane. Furthermore, the amount of protein adsorption onto the membrane...

  2. Worldwide genetic differentiation in the common fouling barnacle, Amphibalanus amphitrite

    KAUST Repository

    Chen, Hsi-Nien

    2014-10-21

    © 2014, © 2014 Taylor & Francis. Amphibalanus amphitrite is a common fouling barnacle distributed globally in tropical and subtropical waters. In the present study, the genetic (mitochondrial cytochrome oxidase subunit I) and morphological differentiation in A. amphitrite from 25 localities around the world were investigated. The results revealed three clades within A. amphitrite with a genetic divergence of ~ 4% among clades, whereas there were no diagnostic morphological differences among clades. Clade 1 is widely distributed in both temperate and tropical waters, whereas Clade 3 is currently restricted to the tropical region. The deep divergence among clades suggests historical isolation within A. amphitrite; thus, the present geographical overlaps are possibly a result of the combined effects of rising sea level and human-mediated dispersals. This study highlights the genetic differentiation that exists in a common, widely distributed fouling organism with great dispersal potential; future antifouling research should take into account the choice of lineages.

  3. Flow and fouling in membrane filters: Effects of membrane morphology

    Science.gov (United States)

    Sanaei, Pejman; Cummings, Linda J.

    2015-11-01

    Membrane filters are widely-used in microfiltration applications. Many types of filter membranes are produced commercially, for different filtration applications, but broadly speaking the requirements are to achieve fine control of separation, with low power consumption. The answer to this problem might seem obvious: select the membrane with the largest pore size and void fraction consistent with the separation requirements. However, membrane fouling (an inevitable consequence of successful filtration) is a complicated process, which depends on many parameters other than membrane pore size and void fraction; and which itself greatly affects the filtration process and membrane functionality. In this work we formulate mathematical models that can (i) account for the membrane internal morphology (internal structure, pore size & shape, etc.); (ii) fouling of membranes with specific morphology; and (iii) make some predictions as to what type of membrane morphology might offer optimum filtration performance.

  4. Characteristics of heat transfer fouling of thin stillage using model thin stillage and evaporator concentrates

    Science.gov (United States)

    Challa, Ravi Kumar

    The US fuel ethanol demand was 50.3 billion liters (13.3 billion gallons) in 2012. Corn ethanol was produced primarily by dry grind process. Heat transfer equipment fouling occurs during corn ethanol production and increases the operating expenses of ethanol plants. Following ethanol distillation, unfermentables are centrifuged to separate solids as wet grains and liquid fraction as thin stillage. Evaporator fouling occurs during thin stillage concentration to syrup and decreases evaporator performance. Evaporators need to be shutdown to clean the deposits from the evaporator surfaces. Scheduled and unscheduled evaporator shutdowns decrease process throughput and results in production losses. This research were aimed at investigating thin stillage fouling characteristics using an annular probe at conditions similar to an evaporator in a corn ethanol production plant. Fouling characteristics of commercial thin stillage and model thin stillage were studied as a function of bulk fluid temperature and heat transfer surface temperature. Experiments were conducted by circulating thin stillage or carbohydrate mixtures in a loop through the test section which consisted of an annular fouling probe while maintaining a constant heat flux by electrical heating and fluid flow rate. The change in fouling resistance with time was measured. Fouling curves obtained for thin stillage and concentrated thin stillage were linear with time but no induction periods were observed. Fouling rates for concentrated thin stillage were higher compared to commercial thin stillage due to the increase in solid concentration. Fouling rates for oil skimmed and unskimmed concentrated thin stillage were similar but lower than concentrated thin stillage at 10% solids concentration. Addition of post fermentation corn oil to commercial thin stillage at 0.5% increments increased the fouling rates up to 1% concentration but decreased at 1.5%. As thin stillage is composed of carbohydrates, protein, lipid

  5. Liquid infused porous surfaces for mineral fouling mitigation.

    Science.gov (United States)

    Charpentier, Thibaut V J; Neville, Anne; Baudin, Sophie; Smith, Margaret J; Euvrard, Myriam; Bell, Ashley; Wang, Chun; Barker, Richard

    2015-04-15

    Prevention of mineral fouling, known as scale, is a long-standing problem in a wide variety of industrial applications, such as oil production, water treatment, and many others. The build-up of inorganic scale such as calcium carbonate on surfaces and facilities is undesirable as it can result in safety risks and associated flow assurance issues. To date the overwhelming amount of research has mainly focused on chemical inhibition of scale bulk precipitation and little attention has been paid to deposition onto surfaces. The development of novel more environmentally-friendly strategies to control mineral fouling will most probably necessitate a multifunctional approach including surface engineering. In this study, we demonstrate that liquid infused porous surfaces provide an appealing strategy for surface modification to reduce mineral scale deposition. Microporous polypyrrole (PPy) coatings were fabricated onto stainless steel substrates by electrodeposition in potentiostatic mode. Subsequent infusion of low surface energy lubricants (fluorinated oil Fluorinert FC-70 and ionic liquid 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIm)) into the porous coatings results in liquid-repellent slippery surfaces. To assess their ability to reduce surface scaling the coatings were subjected to a calcium carbonate scaling environment and the scale on the surface was quantified using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). PPy surfaces infused with BMIm (and Fluorinert to a lesser extent) exhibit remarkable antifouling properties with the calcium carbonate deposition reduced by 18 times in comparison to untreated stainless steel. These scaling tests suggest a correlation between the stability of the liquid infused surfaces in artificial brines and fouling reduction efficiency. The current work shows the great potential of such novel coatings for the management of mineral scale fouling. Copyright © 2014 Elsevier Inc. All rights

  6. Regression analysis of a chemical reaction fouling model

    International Nuclear Information System (INIS)

    Vasak, F.; Epstein, N.

    1996-01-01

    A previously reported mathematical model for the initial chemical reaction fouling of a heated tube is critically examined in the light of the experimental data for which it was developed. A regression analysis of the model with respect to that data shows that the reference point upon which the two adjustable parameters of the model were originally based was well chosen, albeit fortuitously. (author). 3 refs., 2 tabs., 2 figs

  7. Fouling Resilient Perforated Feed Spacers for Membrane Filtration

    KAUST Repository

    Kerdi, Sarah

    2018-04-24

    The improvement of feed spacers with optimal geometry remains a key challenge for spiral-wound membrane systems in water treatment due to their impact on the hydrodynamic performance and fouling development. In this work, novel spacer designs are proposed by intrinsically modifying cylindrical filaments through perforations. Three symmetric perforated spacers (1-Hole, 2-Hole, and 3-Hole) were in-house 3D-printed and experimentally evaluated in terms of permeate flux, feed channel pressure drop and membrane fouling. Spacer performance is characterized and compared with standard no perforated (0-Hole) design under constant feed pressure and constant feed flow rate. Perforations in the spacer filaments resulted in significantly lowering the net pressure drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50% - 61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L.m-2.h-1 and 6.6 L.m-2.h-1 steady state flux for constant pressure and constant feed flow rate, respectively. The 1-Hole spacer was found to be the most efficient among the perforated spacers with 75% and 23% increase in permeate production at constant pressure and constant feed flow, respectively. Furthermore, membrane surface of 1-Hole spacer was found to be cleanest in terms of fouling, contributing to maintain higher permeate flux production. Hydrodynamic understanding of these perforated spacers is also quantified by performing Direct Numerical Simulation (DNS). The performance enhancement of these perforated spacers is attributed to the formation of micro-jets in the spacer cell that aided in producing enough unsteadiness/turbulence to clean the membrane surface and mitigate fouling phenomena. In the case of 1-Hole spacer, the unsteadiness intensity at the outlet of micro-jets and the shear stress fluctuations created inside the cells are higher than those observed with

  8. Hybrid system for fouling control in biomass boilers

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, Luis M.; Gareta, Raquel [Centro de Investigacin de Recursos y Consumos Energeticos (CIRCE), Universidad de Zaragoza, Centro Politecnico Superior, Mareda de Luna, 3, Zaragoza 50018, (Spain)

    2006-12-15

    Renewable energy sources are essential paths towards sustainable development and CO{sub 2} emission reduction. For example, the European Union has set the target of achieving 22% of electricity generation from renewable sources by 2010. However, the extensive use of this energy source is being avoided by some technical problems as fouling and slagging in the surfaces of boiler heat exchangers. Although these phenomena were extensively studied in the last decades in order to optimize the behaviour of large coal power boilers, a simple, general and effective method for fouling control has not been developed. For biomass boilers, the feedstock variability and the presence of new components in ash chemistry increase the fouling influence in boiler performance. In particular, heat transfer is widely affected and the boiler capacity becomes dramatically reduced. Unfortunately, the classical approach of regular sootblowing cycles becomes clearly insufficient for them. Artificial Intelligence (AI) provides new means to undertake this problem. This paper illustrates a methodology based on Neural Networks (NNs) and Fuzzy-Logic Expert Systems to select the moment for activating sootblowing in an industrial biomass boiler. The main aim is to minimize the boiler energy and efficiency losses with a proper sootblowing activation. Although the NN type used in this work is well-known and the Hybrid Systems had been extensively used in the last decade, the excellent results obtained in the use of AI in industrial biomass boilers control with regard to previous approaches makes this work a novelty. (Author)

  9. Electrochemical acidification of Kraft black liquor by electrodialysis with bipolar membrane: Ion exchange membrane fouling identification and mechanisms.

    Science.gov (United States)

    Haddad, Maryam; Mikhaylin, Sergey; Bazinet, Laurent; Savadogo, Oumarou; Paris, Jean

    2017-02-15

    Integrated forest biorefinery offers promising pathways to sustainably diversify the revenue of pulp and paper industry. In this context, lignin can be extracted from a residual stream of Kraft pulping process, called black liquor, and subsequently converted into a wide spectrum of bio-based products. Electrochemical acidification of Kraft black liquor by electrodialysis with bipolar membrane results in lignin extraction and caustic soda production. Even though the implementation of this method requires less chemicals than the chemical acidification process, fouling of the ion exchange membranes and especially bipolar membrane impairs its productivity. Membrane thickness and ash content measurements along with scanning electron microscopy (SEM), elemental analysis (EDX) and X-ray photoelectron spectrometry (XPS) analysis were performed to identify the nature and mechanisms of the membrane fouling. The results revealed that the fouling layer mostly consisted of organic components and particularly lignin. Based on our proposed fouling mechanisms, throughout the electrodialysis process the pH of the black liquor gradually decreased and as a result more proton ions were available to trigger protonation reaction of lignin phenolic groups and decrease the lignin solubility. Due to the abundance of the proton ions on the surface of the cation exchange layers of the bipolar membrane, destabilized lignin macro-molecules started to self-aggregate and formed lignin clusters on its surface. Over the time, these lignin clusters covered the entire surface of the bipolar membrane and the spaces between the membranes and, eventually, attached to the surface of the cation exchange membrane. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Fouling Characterization of Forward Osmosis Biomimetic Aquaporin Membranes Used for Water Recovery from Municipal Wastewater

    DEFF Research Database (Denmark)

    Zarebska, Agata; Petrinic, Irena; Hey, Tobias

    , organic, and biological fouling, membrane characterization is not a trivial task. The aim of this work is to characterize fouling of FO biomimetic aquaporin membranes during water recovery from municipal wastewater. Membrane fouling was characterized using Scanning Electron Microscopy, X-ray Dispersive......Generally more than 99.93% of municipal wastewater is composed of water, therefore water recovery can alleviate global water stress which currently exists. Traditional ways to extract water from wastewater by the use of membrane bioreactors combined with reverse osmosis (RO), or micro...... compared to other pressure driven membrane processes, some fouling can occur. This entails that by reducing fouling, increased FO membrane performance can be expected, thus increasing the economic viability of FO processes. Since various types of fouling might occur in membrane systems such as inorganic...

  11. Characterization of Irreversible Fouling after Ultrafiltration of Thermomechanical Pulp Mill Process Water

    DEFF Research Database (Denmark)

    Thuvander, Johan; Zarebska, Agata; Hélix-Nielsen, Claus

    2018-01-01

    process streams is fouling of the membranes. Fouling not only increases operating costs but also reduces the operating time of the membrane plant. When optimizing the membrane cleaning method, it is important to know which compounds cause the fouling. In this work fouling of an ultrafiltration membrane...... was studied. The fouling propensity of untreated process water and microfiltrated process water was compared. Fouled membranes were analyzed using scanning electron microscopy and attenuated total reflection Fourier transform infrared spectrometry. Acid hydrolysis of membranes exposed to untreated process......Large volumes of wastewater with dissolved wood components are treated in wastewater treatment plants at thermomechanical pulp mills. It has been shown previously that hemicelluloses in these wastewater streams can be recovered by membrane filtration. A serious obstacle when treating lignocellulose...

  12. Ultrasonic Reflectometry for Monitoring the Effect of Pressure on Sludge Fouling of MF Membranes

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Kujundzic, Elmira; Greenberg, Alan

    Membrane fouling remains the key limitation for the widespread use of membrane bioreactors (MBR) for wastewater treatment. This constraint has led to an increasing number of studies that examine the influence of various operational parameters and physicochemical properties on fouling layer...... formation and characteristics. In other membrane applications real-time monitoring has proven to be useful by providing a more quantitative characterization of fouling layer formation [1]. One such technique, ultrasonic reflectometry (UR), has been successfully used to detect fouling formed by a wide range...... of the effect of pressure on the fouling layer structure. The ability of UR to detect and monitor sludge fouling was studied in a series of replicated experiments of 15, 30 and 60-min duration that used commercial microfiltration (MF) membranes at a transmembrane pressure of 15 kPa. By analyzing the peak...

  13. Application of the RES methodology for identifying features, events and processes (FEPs) for near-field analysis of copper-steel canister

    International Nuclear Information System (INIS)

    Vieno, T.; Hautojaervi, A.; Raiko, H.; Ahonen, L.; Salo, J.P.

    1994-12-01

    Rock Engineering Systems (RES) is an approach to discover the important characteristics and interactions of a complex problem. Recently RES has been applied to identify features, events and processes (FEPs) for performance analysis of nuclear waste repositories. The RES methodology was applied to identify FEPs for the near-field analysis of the copper-steel canister for spent fuel disposal. The aims of the exercise were to learn and test the RES methodology and, secondly, to find out how much the results differ when RES is applied by two different groups on the same problem. A similar exercise was previously carried out by a SKB group. A total of 90 potentially significant FEPs were identified. The exercise showed that the RES methodology is a practicable tool to get a comprehensive and transparent picture of a complex problem. The approach is easy to learn and use. It reveals the important characteristics and interactions and organizes them in a format easy to understand. (9 refs., 5 figs., 3 tabs.)

  14. Field study of the long-term release of block copolymers from fouling-release coatings

    DEFF Research Database (Denmark)

    Noguer, Albert Camós; Olsen, A.; Hvilsted, Søren

    2017-01-01

    The addition of block copolymers (i.e. oils) is a common technique to enhance the biofouling-resistance properties of poly(dimethylsiloxane) (PDMS)-based fouling-release coatings. These copolymers diffuse from the bulk to the surface of the coating, thus modifying the properties of the surface an...... fouling-release coatings. Finally, the potential of long-term field-studies is discussed, as compared to short-term laboratory experiments usually performed within fouling-release coatings studies....

  15. Studies on fouling diatoms from the Zuari Estuary, Goa (west coast of India)

    Digital Repository Service at National Institute of Oceanography (India)

    Redekar, P.D.; Wagh, A.B.

    from offshore waters of Bombay High area using aluminium panels and recorded 58 species of fouling diatoms Of these Navicula Coscinodiscus Rhizosolenia and Chaetoceros were found to be common The dominance of Centrales over Pennales in water column... on fouling diatoms from the Zuari estuary, Goa (West coast of India) 119 Pangu (1993) used mild steel, aluminium, fiberglass and glass test panels and the immersion period of panels was long (1 month to 11 months) The fouling diatoms from Waghotana...

  16. Intra-event correlations and the statistical moments of the identified particle multiplicity distributions in the RHIC beam energy scan data collected by STAR

    Science.gov (United States)

    Llope, W. J.; STAR Collaboration

    2013-10-01

    Specific products of the statistical moments of the multiplicity distributions of identified particles can be directly compared to susceptibility ratios obtained from lattice QCD calculations. They may also diverge for nuclear systems formed close to a possible QCD critical point due to the phenomenon of critical opalescence. Of particular interest are the moments products for net-protons, net-kaons, and net-charge, as these are considered proxies for conserved quantum numbers. The moments products have been measured by the STAR experiment for Au+Au collisions at seven beam energies ranging from 7.7 to 200 GeV. In this presentation, the experimental results are compared to data-based calculations in which the intra-event correlations of the numbers of positive and negative particles are broken by construction. The importance of intra-event correlations to the moments products values for net-protons, net-kaons, and net-charge can thus be evaluated. Work supported by the U.S. Dept of Energy under grant DE-PS02-09ER09.

  17. Search for charged Higgs bosons and measurement of |V sub c sub s | in quark and lepton flavour identified events at LEP2

    CERN Document Server

    Kiiskinen, A P

    1999-01-01

    A search for pair produced charged Higgs bosons was performed on the high energy data collected by DELPHI at LEP2. All three major final states, tau nu tau nu, cs tau nu and cscs were searched for. The analyses used a combination of event shape variables, di-jet masses and jet flavour tagging. The jet flavours were identified by using life time tagging and particle identification based on the RICH detector complemented by ionisation energy loss measurements. A similar type of jet flavour tagging was also used in extracting the |V sub c sub s | element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix in hadronic decays of the W sup+- boson.

  18. Understanding the risk of scaling and fouling in hollow fiber forward osmosis membrane application

    KAUST Repository

    Majeed, Tahir; Phuntsho, Sherub; Jeong, Sanghyun; Zhao, Yanxia; Gao, Baoyu; Shon, Ho Kyong

    2016-01-01

    Fouling studies of forward osmosis (FO) were mostly conducted based on fouling evaluation principals applied to pressure membrane processes such as reverse osmosis (RO)/nanofiltration (NF)/microfiltration (MF)/ultrafiltration (UF). For RO/NF/MF/UF processes, the single flux driving force (hydraulic pressure) remains constant, thus the fouling effect is easily evaluated by comparing flux data with the baseline. Whilst, the scenario of fouling effects for FO process is entirely different from RO/NF/MF/UF processes. Continuously changing driving force (osmotic pressure difference), the changes in concentration polarization associated with the varying draw solution/feed solution concentration and the fouling layer effects collectively influence the FO flux. Thus, usual comparison of the FO flux outcome with the baseline results can not exactly indicate the real affect of membrane fouling, rather presents a misleading cumulative effect. This study compares the existing FO fouling technique with an alternate fouling evaluation approach using two FO set-ups. Scaling and fouling risk for hollow fiber FO was separately investigated using synthetic water samples and model organic foulants as alginate, humic acid and bovine serum albumin. Results indicated that FO flux declines up to 5% and 49% in active layer-feed solution and active layer-draw solution orientations respectively.

  19. Advanced Marine Coatings for Naval Vessels - Phase 1. Antifouling and Fouling Release Coatings

    National Research Council Canada - National Science Library

    McCarthy, Gregory

    2003-01-01

    ... in combinatorial materials chemistry high-throughput discovery and evaluation methodology. The protective coatings application being addressed is environmentally compliant antifouling and fouling release coating for Navy ships...

  20. Understanding the risk of scaling and fouling in hollow fiber forward osmosis membrane application

    KAUST Repository

    Majeed, Tahir

    2016-06-23

    Fouling studies of forward osmosis (FO) were mostly conducted based on fouling evaluation principals applied to pressure membrane processes such as reverse osmosis (RO)/nanofiltration (NF)/microfiltration (MF)/ultrafiltration (UF). For RO/NF/MF/UF processes, the single flux driving force (hydraulic pressure) remains constant, thus the fouling effect is easily evaluated by comparing flux data with the baseline. Whilst, the scenario of fouling effects for FO process is entirely different from RO/NF/MF/UF processes. Continuously changing driving force (osmotic pressure difference), the changes in concentration polarization associated with the varying draw solution/feed solution concentration and the fouling layer effects collectively influence the FO flux. Thus, usual comparison of the FO flux outcome with the baseline results can not exactly indicate the real affect of membrane fouling, rather presents a misleading cumulative effect. This study compares the existing FO fouling technique with an alternate fouling evaluation approach using two FO set-ups. Scaling and fouling risk for hollow fiber FO was separately investigated using synthetic water samples and model organic foulants as alginate, humic acid and bovine serum albumin. Results indicated that FO flux declines up to 5% and 49% in active layer-feed solution and active layer-draw solution orientations respectively.

  1. Different types of asynchronous music and effects on performance of basketball foul shot.

    Science.gov (United States)

    Geisler, G; Leith, L M

    2001-12-01

    48 undergraduate women performed basketball foul shots with and without background music. Slow music, fast music, and music personally selected by subjects did not significantly affect shooting performance.

  2. Assessment of Silt Density Index (SDI) as Fouling Propensity Parameter in Reverse Osmosis Desalination

    KAUST Repository

    Rachman, Rinaldi

    2011-07-01

    Reverse osmosis operations are facing persistent fouling phenomenon that has challenged the integrity of these processes. Prediction of fouling potential by measuring a fouling index toward feed water is essential to ensure robust operation. Moreover, employing a reliable fouling index with good reproducibility and precision is necessary. Silt density index (SDI) is considered insufficient in terms of reliability and empirical theory, among other limitations. Nevertheless due its simplicity, SDI measurement is utilized extensively in RO desalination systems. The aim of this research is to assess the reliability of SDI. Methods include the investigation of different SDI membranes and study of the nature of the SDI filtration. Results demonstrate the existence of the membrane properties\\' variation within manufacturers, which then causes a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role on SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. Moreover, turbidity assisted SDI measurements along with determination of UF pretreated and clean water fouling potential, establishes the indication of non-fouling related phenomena involved on SDI measurement such as a natural organic matter adsorption and hydrodynamic condition that alters during filtration. Additionally, it was found that the latter affects the sensitivity of SDI by being represented by some portions of SDI value. Keywords: Reverse Osmosis, Fouling index, Particulate Fouling, Silt Density Index (SDI), and Assessment of SDI.

  3. Bio-fouling and its control in the cooling water system of PFBR

    International Nuclear Information System (INIS)

    Satpathy, K.K.; Kannan, S.E.

    2004-06-01

    This report gives an overview of the bio-fouling problems that could be visualized in the different sections of the cooling system of PFBR, which is based on the experience observed at MAPS as well as from the experience of some of the work carried out at Kalpakkam. International as well as the MAPS practices of bio-fouling control are discussed. Based on these, an appropriate method for bio-fouling control is suggested. In addition, a few time bound, field, as well as laboratory experiments are proposed to be carried out, for deciding precise and accurate method of bio-fouling control for PFBR cooling water system. (author)

  4. The fouling serpulids (Polychaeta: Serpulidae from United States coastal waters: an overview

    Directory of Open Access Journals (Sweden)

    J. Rolando Bastida-Zavala

    2017-08-01

    Full Text Available Serpulids are an important component of fouling communities. This paper provides an overview of the serpulid species found in North America, as part of a broader study of fouling invertebrates focused on NIS (non-indigenous species in United States coastal ecosystems. Almost 4400 serpulid specimens were examined from selected fouling plates. Fouling plates were deployed in 26 bays and coastal lagoons along the continental coasts of the United States and Hawaiian islands, primarily in bays and lagoons with salinities averaging 20‰ or greater. Twenty-five serpulid species were identified, including four new records for the United States (Ficopomatus uschakovi, Hydroides cf. brachyacantha, H. longispinosa and Protula longiseta, three known NIS, two presumed NIS, three cryptogenic serpulids, and several range extensions. Crucigera websteri extends its northward range from Santa Barbara Island to Humboldt Bay, California; Ficopomatus enigmaticus, first recorded in North America from San Francisco, California in 1920, Rockport, Texas in 1952 and Barnegat Bay, New Jersey in 1980, is now recorded at additional localities on the east coast (Chesapeake Bay, Virginia, Charleston, South Carolina and Indian River, Florida and the northern Gulf of Mexico (Galveston Bay, Texas; F. miamiensis extends its westward range from Louisiana to Texas; F. uschakovi, an Indo-Pacific and Western African species, was recorded formally for the first time from the northern Gulf of Mexico (Galveston Bay and Corpus Christi, Texas and the east coast of Florida (Jacksonville. Hydroides cf. brachyacantha extends its northward range from Curaҫao to Pensacola Bay, Florida; H. dirampha from Veracruz, Mexico to Corpus Christi, Texas; H. floridana extends its westward range from Louisiana to Texas; H. gracilis extends its northward range from Pacific Grove to San Francisco, California; Salmacina huxleyi from Cape Hatteras, North Carolina to Rhode Island; and Spirobranchus

  5. Environmentally Safe Control of Zebra Mussel Fouling

    Energy Technology Data Exchange (ETDEWEB)

    Daniel Molloy

    2008-02-29

    The two primary objectives of this USDOE-NETL contract were successfully achieved during the project: (1) to accelerate research on the development of the bacterium Pseudomonas fluorescens strain CL145A (Pf-CL145A) as a biocontrol agent for zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis)--two invasive freshwater bivalve species that are infesting water pipes in power plants; and (2) to identify a private-sector company that would move forward to commercialize Pf-CL145A as a substitute for the current polluting use of biocide chemicals for control of these dreissenid mussels in power plant pipes.

  6. Fouling of Seawater Reverse Osmosis (SWRO) Membrane: Chemical and Microbiological Characterization

    KAUST Repository

    Khan, Muhammad T.

    2013-12-01

    In spite of abundant water resources, world is suffering from the scarcity of usable water. Seawater Reverse Osmosis (SWRO) desalination technology using polymeric membranes has been recognized as a key solution to water scarcity problem. However, economic sustainability of this advanced technology is adversely impacted by the membrane fouling problem. Fouling of RO membranes is a highly studied phenomenon. However, literature is found to be lacking a detailed study on kinetic and dynamic aspects of SWRO membrane fouling. The factors that impact the fouling dynamics, i.e., pretreatment and water quality were also not adequately studied at full–scale of operation. Our experimental protocol was designed to systematically explore these fouling aspects with the objective to improve the understanding of SWRO membrane fouling mechanisms. An approach with multiple analytical techniques was developed for fouling characterization. In addition to the fouling layer characterization, feed water quality was also analysed to assess its fouling potential. Study of SWRO membrane fouling dynamics and kinetics revealed variations in relative abundance of chemical and microbial constituents of the fouling layer, over operating time. Aromatic substances, most likely humic–like substances, were observed at relatively high abundance in the initial fouling layer, followed by progressive increase in relative abundances of proteins and polysaccharides. Microbial population grown on all membranes was dominated by specific groups/species belonging to different classes of Proteobacteria phylum; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age and with the position of membrane element in RO vessel. Our results demonstrated that source water quality can significantly impact the RO membrane fouling scenarios. Moreover, the major role of chlorination in the SWRO membrane fouling was highlighted. It was found that intermittent mode of chlorination

  7. Application of electrochemical processes to membrane bioreactors for improving nutrient removal and fouling control.

    Science.gov (United States)

    Borea, Laura; Naddeo, Vincenzo; Belgiorno, Vincenzo

    2017-01-01

    Membrane bioreactor (MBR) technology is becoming increasingly popular as wastewater treatment due to the unique advantages it offers. However, membrane fouling is being given a great deal of attention so as to improve the performance of this type of technology. Recent studies have proven that the application of electrochemical processes to MBR represents a promising technological approach for membrane fouling control. In this work, two intermittent voltage gradients of 1 and 3 V/cm were applied between two cylindrical perforated electrodes, immersed around a membrane module, at laboratory scale with the aim of investigating the treatment performance and membrane fouling formation. For comparison purposes, the reactor also operated as a conventional MBR. Mechanisms of nutrient removal were studied and membrane fouling formation evaluated in terms of transmembrane pressure variation over time and sludge relative hydrophobicity. Furthermore, the impact of electrochemical processes on transparent exopolymeric particles (TEP), proposed as a new membrane fouling precursor, was investigated in addition to conventional fouling precursors such as bound extracellular polymeric substances (bEPS) and soluble microbial products (SMP). All the results indicate that the integration of electrochemical processes into a MBR has the advantage of improving the treatment performance especially in terms of nutrient removal, with an enhancement of orthophosphate (PO 4 -P) and ammonia nitrogen (NH 4 -N) removal efficiencies up to 96.06 and 69.34 %, respectively. A reduction of membrane fouling was also observed with an increase of floc hydrophobicity to 71.72 %, a decrease of membrane fouling precursor concentrations, and, thus, of membrane fouling rates up to 54.33 %. The relationship found between TEP concentration and membrane fouling rate after the application of electrochemical processes confirms the applicability of this parameter as a new membrane fouling indicator.

  8. Demographic clusters identified within the northern Gulf of Mexico common bottlenose dolphin (Tursiops truncates unusual mortality event: January 2010-June 2013.

    Directory of Open Access Journals (Sweden)

    Stephanie Venn-Watson

    Full Text Available A multi-year unusual mortality event (UME involving primarily common bottlenose dolphins (Tursiops truncates was declared in the northern Gulf of Mexico (GoM with an initial start date of February 2010 and remains ongoing as of August 2014. To examine potential changing characteristics of the UME over time, we compared the number and demographics of dolphin strandings from January 2010 through June 2013 across the entire GoM as well as against baseline (1990-2009 GoM stranding patterns. Years 2010 and 2011 had the highest annual number of stranded dolphins since Louisiana's record began, and 2011 was one of the years with the highest strandings for both Mississippi and Alabama. Statewide, annual numbers of stranded dolphins were not elevated for GoM coasts of Florida or Texas during the UME period. Demographic, spatial, and temporal clusters identified within this UME included increased strandings in northern coastal Louisiana and Mississippi (March-May 2010; Barataria Bay, Louisiana (August 2010-December 2011; Mississippi and Alabama (2011, including a high prevalence and number of stranded perinates; and multiple GoM states during early 2013. While the causes of the GoM UME have not been determined, the location and magnitude of dolphin strandings during and the year following the 2010 Deepwater Horizon oil spill, including the Barataria Bay cluster from August 2010 to December 2011, overlap in time and space with locations that received heavy and prolonged oiling. There are, however, multiple known causes of previous GoM dolphin UMEs, including brevetoxicosis and dolphin morbillivirus. Additionally, increased dolphin strandings occurred in northern Louisiana and Mississippi before the Deepwater Horizon oil spill. Identification of spatial, temporal, and demographic clusters within the UME suggest that this mortality event may involve different contributing factors varying by location, time, and bottlenose dolphin populations that will be

  9. Using CFD to investigate heater fouling in a utility boiler

    International Nuclear Information System (INIS)

    Pang, L.; Sun, B.; Salcudean, M.

    2004-01-01

    A simulation investigation into the combustion and heat transfer process in a utility boiler is presented. The work is based on the commercial software Fluent 6.1.18. Flow, chemistry, energy, conservation and radiation models are used to simulate the process inside the furnace. Radiation and convection models are considered in the horizontal heater. The temperature and velocity fields are calculated to unveil the process inside and outside the furnace. The result shows that the fouling in reheater is formed because of the temperature and velocity field in the flue gas passage. A limited test is done to validate the simulation. (author)

  10. Fundamentals of membrane bioreactors materials, systems and membrane fouling

    CERN Document Server

    Ladewig, Bradley

    2017-01-01

    This book provides a critical, carefully researched, up-to-date summary of membranes for membrane bioreactors. It presents a comprehensive and self-contained outline of the fundamentals of membrane bioreactors, especially their relevance as an advanced water treatment technology. This outline helps to bring the technology to the readers’ attention, and positions the critical topic of membrane fouling as one of the key impediments to its more widescale adoption. The target readership includes researchers and industrial practitioners with an interest in membrane bioreactors.

  11. Fouling resilient perforated feed spacers for membrane filtration.

    Science.gov (United States)

    Kerdi, Sarah; Qamar, Adnan; Vrouwenvelder, Johannes S; Ghaffour, Noreddine

    2018-04-24

    The improvement of feed spacers with optimal geometry remains a key challenge for spiral-wound membrane systems in water treatment due to their impact on the hydrodynamic performance and fouling development. In this work, novel spacer designs are proposed by intrinsically modifying cylindrical filaments through perforations. Three symmetric perforated spacers (1-Hole, 2-Hole, and 3-Hole) were in-house 3D-printed and experimentally evaluated in terms of permeate flux, feed channel pressure drop and membrane fouling. Spacer performance is characterized and compared with standard no perforated (0-Hole) design under constant feed pressure and constant feed flow rate. Perforations in the spacer filaments resulted in significantly lowering the net pressure drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50%-61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L m -2 .h -1 and 6.6 L m -2 .h -1 steady state flux for constant pressure and constant feed flow rate, respectively. The 1-Hole spacer was found to be the most efficient among the perforated spacers with 75% and 23% increase in permeate production at constant pressure and constant feed flow, respectively. Furthermore, membrane surface of 1-Hole spacer was found to be cleanest in terms of fouling, contributing to maintain higher permeate flux production. Hydrodynamic understanding of these perforated spacers is also quantified by performing Direct Numerical Simulation (DNS). The performance enhancement of these perforated spacers is attributed to the formation of micro-jets in the spacer cell that aided in producing enough unsteadiness/turbulence to clean the membrane surface and mitigate fouling phenomena. In the case of 1-Hole spacer, the unsteadiness intensity at the outlet of micro-jets and the shear stress fluctuations created inside the cells are higher than those

  12. Organic fouling behavior of superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membranes functionalized with surface-tailored nanoparticles: Implications for organic fouling in membrane bioreactors

    KAUST Repository

    Liang, Shuai; Qi, Genggeng; Xiao, Kang; Sun, Jianyu; Giannelis, Emmanuel P.; Huang, Xia; Elimelech, Menachem

    2014-01-01

    This study systematically investigates the organic fouling behavior of a superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membrane functionalized via post-fabrication tethering of surface-tailored silica nanoparticles to poly

  13. Costs and benefits to European shipping of ballast-water and hull-fouling treatment

    NARCIS (Netherlands)

    Fernandes, Jose A.; Santos, Lionel; Vance, Thomas; Fileman, Tim; Smith, David; Bishop, John D.D.; Viard, Frédérique; Queirós, Ana M.; Merino, Gorka; Buisman, Erik; Austen, Melanie C.

    2016-01-01

    Maritime transport and shipping are impacted negatively by biofouling, which can result in increased fuel consumption. Thus, costs for fouling reduction can be considered an investment to reduce fuel consumption. Anti-fouling measures also reduce the rate of introduction of non-indigenous species

  14. A zwitterionic macro-crosslinker for durable non-fouling coatings.

    Science.gov (United States)

    Wang, Wei; Lu, Yang; Xie, Jinbing; Zhu, Hui; Cao, Zhiqiang

    2016-03-28

    A novel zwitterionic macro-crosslinker was developed and applied to fabricate durable non-fouling coatings on a polyurethane substrate. The zwitterionic macro-crosslinker coating exhibited superior durability over the traditional brush polymer coating and was able to retain its non-fouling property even after weeks of shearing in flowing liquid.

  15. Searching for storm water inflows in foul sewers using fibre-optic distributed temperature sensing

    NARCIS (Netherlands)

    Schilperoort, R.; Hoppe, H.; Haan, C.; Langeveld, J.G.

    2012-01-01

    A major drawback of separate sewer systems is the occurrence of illicit connections: unintended sewer cross-connections that connect foul water outlets from residential or industrial premises to the storm water system and/or storm water outlets to the foul sewer system. The amount of unwanted storm

  16. Fouling behavior of silica nanoparticle-surfactant mixtures during constant flux dead-end ultrafiltration

    NARCIS (Netherlands)

    Trzaskus, Krzystof; Lee, Sooi Li; de Vos, Wiebe Matthijs; Kemperman, Antonius J.B.; Nijmeijer, Kitty

    2017-01-01

    The increasing use of engineered nanoparticles in customer products results in their accumulation in water sources. In this experimental study, we investigated the role of surfactant type (cationic, anionic and non-ionic) and concentration on fouling development, nanoparticle rejection and fouling

  17. The impact of fouling on performance evaluation of evaporative coolers and condensers

    Energy Technology Data Exchange (ETDEWEB)

    Qureshi, B.A.; Zubair, S.M. [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia). Mechanical Engineering Dept.

    2005-11-15

    Fouling of evaporative cooler and condenser tubes is one of the most important factors affecting their thermal performance, which reduces effectiveness and heat transfer capability with time. In this paper, the experimental data on fouling reported in the literature are used to develop a fouling model for this class of heat exchangers. The model predicts the decrease in heat transfer rate with the growth of fouling. A detailed model of evaporative coolers and condensers, in conjunction with the fouling model, is used to study the effect of fouling on the thermal performance of these heat exchangers at different air inlet wet bulb temperatures. The results demonstrate that fouling of tubes reduces gains in performance resulting from decreasing values of air inlet wet bulb temperature. It is found that the maximum decrease in effectiveness due to fouling is about 55 and 78% for the evaporative coolers and condensers, respectively, investigated in this study. For the evaporative cooler, the value of process fluid outlet temperature T{sub p,out} varies by 0.66% only at the clean condition for the ambient wet bulb temperatures considered. (author)

  18. The Influence of Unsportsmanlike Fouls on Basketball Teams' Performance According to Context-Related Variables.

    Science.gov (United States)

    Gómez, Miguel-Ángel; Ortega Toro, Enrique; Furley, Philip

    2016-07-01

    The aim of the current study was to analyze the temporal effects that unsportsmanlike fouls may have on basketball teams' scoring performance under consideration of context-related variables. The authors analyzed 130 unsportsmanlike fouls from 362 elite basketball games (men's and women's Olympic Games, European and World Championships). The context-related variables studied were score-line, quality of opposition, timeout situation, minutes remaining, and player status. The data were analyzed with linear-regression models. The results showed that both teams (the team that made the foul and the opponent) had similar positive scoring performances during 1 and 3 ball possessions after the unsportsmanlike foul (short-term effect). However, 5 ball possessions after the foul (midterm effect), the team that made the foul had a scoring disadvantage (-0.96) and the opponent team an advantage (0.78). The context-related variable quality of opposition was significant only during 1 ball possession, with negative effects for the team that made the foul and positive effects for the opponent. The final outcome showed a positive effect for score-line when the unsportsmanlike foul was made (0.96) and for quality of opposition (0.64).

  19. Silt density index and modified fouling index relation, and effect of pressure, temperature and membrane resistance

    NARCIS (Netherlands)

    Al-Hadidi, A.M.M.; Alhadidi, A.; Kemperman, Antonius J.B.; Blankert, B.; Blankert, B.; Schippers, J.C.; Wessling, Matthias; van der Meer, Walterus Gijsbertus Joseph

    2011-01-01

    Particulate matter present in feed water of reverse osmosis and nanofiltration membrane elements tends to deposit on the membrane surface and spacers. This type of fouling results in permeate flux decline, loss of product quality and membrane damage. To characterize the fouling potential of RO feed

  20. Tube micro-fouling, boiling and steam pressure after chemical cleaning

    International Nuclear Information System (INIS)

    Hu, M.H.

    1998-01-01

    This paper presents steam pressure trends after chemical cleaning of steam generator tubes at four plants. The paper also presents tube fouling factor that serves as an objective parameter to assess tubing boiling conditions for understanding the steam pressure trend. Available water chemistry data helps substantiate the concept of tube micro-fouling, its effect on tubing boiling, and its impact on steam pressure. All four plants experienced a first mode of decreasing steam pressure in the post-cleaning operation. After 3 to 4 months of operation, the decreasing trend stopped for three plants and then restored to a pre-cleaning value or better. The fourth plant is soil in decreasing trend after 12 months of operation. Dissolved chemicals, such as silica, titanium can precipitate on tube surface. The precipitate micro-fouling can deactivate or eliminate boiling nucleation sites. Therefore, the first phase of the post-cleaning operation suffered a decrease in steam pressure or an increase in fouling factor. It appears that micro fouling by magnetite deposit can activate or create more bubble nucleation sites. Therefore, the magnetite deposit micro-fouling results in a decrease in fouling factor, and a recovery in steam pressure. Fully understanding the boiling characteristics of the tubing at brand new, fouled and cleaned conditions requires further study of tubing surface conditions. Such study should include boiling heat transfer tests and scanning electronic microscope examination. (author)

  1. CO2 saturated water as two-phase flow for fouling control in reverse electrodialysis

    NARCIS (Netherlands)

    Moreno, J.; de Hart, N.; Saakes, M.; Nijmeijer, K.

    2017-01-01

    When natural feed waters are used in the operation of a reverse electrodialysis (RED) stack, severe fouling on the ion exchange membranes and spacers occurs. Fouling of the RED stack has a strong influence on the gross power density output; which can decrease up to 50%. Moreover, an increase in the

  2. SRBreak: A read-depth and split-read framework to identify breakpoints of different events inside simple copy-number variable regions

    Directory of Open Access Journals (Sweden)

    HOANG T NGUYEN

    2016-09-01

    Full Text Available Copy-number variation (CNV has been associated with increased risk of complex diseases. High throughput sequencing (HTS technologies facilitate the detection of copy-number variable regions (CNVRs and their breakpoints. This helps in understanding genome structures of genomes as well as their evolution process. Various approaches have been proposed for detecting CNV breakpoints, but currently it is still challenging for tools based on a single analysis method to identify breakpoints of CNVs. It has been shown, however, that pipelines which integrate multiple approaches are able to report more reliable breakpoints. Here, based on HTS data, we have developed a pipeline to identify approximate breakpoints (±10 bp relating to different ancestral events within a specific CNVR. The pipeline combines read-depth and split-read information to infer breakpoints, using information from multiple samples to allow an imputation approach to be taken. The main steps involve using a normal mixture model to cluster samples into different groups, followed by simple kernel-based approaches to maximise information obtained from read-depth and split-read approaches, after which common breakpoints of groups are inferred. The pipeline uses split-read information directly from CIGAR strings of BAM files, without using a re-alignment step. On simulated data sets, it was able to report breakpoints for very low-coverage samples including those for which only single-end reads were available. When applied to three loci from existing human resequencing data sets (NEGR1, LCE3, IRGM the pipeline obtained good concordance with results from the 1000 Genomes Project (92%, 100% and 82%, respectively.The package is available at https://github.com/hoangtn/SRBreak, and also as a docker-based application at https://registry.hub.docker.com/u/hoangtn/srbreak/.

  3. Monitoring Protein Fouling on Polymeric Membranes Using Ultrasonic Frequency-Domain Reflectometry

    Directory of Open Access Journals (Sweden)

    Robin Fong

    2011-08-01

    Full Text Available Novel signal-processing protocols were used to extend the in situ sensitivity of ultrasonic frequency-domain reflectometry (UFDR for real-time monitoring of microfiltration (MF membrane fouling during protein purification. Different commercial membrane materials, with a nominal pore size of 0.2 µm, were challenged using bovine serum albumin (BSA and amylase as model proteins. Fouling induced by these proteins was observed in flat-sheet membrane filtration cells operating in a laminar cross-flow regime. The detection of membrane-associated proteins using UFDR was determined by applying rigorous statistical methodology to reflection spectra of ultrasonic signals obtained during membrane fouling. Data suggest that the total power reflected from membrane surfaces changes in response to protein fouling at concentrations as low as 14 μg/cm2, and results indicate that ultrasonic spectra can be leveraged to detect and monitor protein fouling on commercial MF membranes.

  4. Compressibility of the fouling layer formed by membrane bioreactor sludge and supernatant

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Poorasgari, Eskandar; Christensen, Morten Lykkegaard

    Membrane bioreactors (MBR) are increasingly used for wastewater treatment as they give high effluent quality, low footprint and efficient sludge degradation. However, the accumulation and deposition of sludge components on and within the membrane (fouling) limits the widespread application of MBR....... Compressibility of the gel layer was studied in a dead-end filtration system, whereas the compressibility of a fouling layer formed by MBR sludge was studied in a submerged system hollow sheet membrane by TMP stepping. It was shown that the fouling layer formed by the MBR sludge was highly compressible within....... Hence, for MBR systems operated at constant flux mode, the applied pressure should be increased over time, to compensate for the lower permeability. Increasing applied pressure causes compression of the fouling layer and results in a more severe permeability decline [1]. In a general view, the fouling...

  5. Low fouling polysulfone ultrafiltration membrane via click chemistry

    KAUST Repository

    Xie, Yihui

    2014-10-13

    Hydrophilic surfaces are known to be less prone to fouling. Ultrafiltration membranes are frequently prepared from rather hydrophobic polymers like polysulfone (PSU). Strategies to keep the good pore forming characteristics of PSU, but with improved hydrophilicity are proposed here. PSU functionalized with 1,2,3-triazole ring substituents containing OH groups was successfully synthesized through click chemistry reaction. The structures of the polymers were confirmed using NMR spectroscopy and Fourier transform infrared spectroscopy (FTIR). High thermal stability (>280°C) was observed by thermal gravimetric analysis. Elemental analysis showed the presence of nitrogen containing triazole group with different degrees of functionalization (23%, 49%, 56%, and 94%). The glass transition temperature shifted with the introduction of triazole pendant groups from 190°C (unmodified) to 171°C. Ultrafiltration membranes were prepared via phase inversion by immersion in different coagulation baths (NMP/water mixtures with volume ratios from 0/100 to 40/60). The morphologies of these membranes were studied by field emission scanning electron microscopy (FESEM). The optimized PSU bearing triazole functions membranes exhibited water permeability up to 187 L m-2 h-1 bar-1, which is 23 times higher than those prepared under the same conditions but with unmodified polysulfone (PSU; 8 L m-2 h-1 bar-1). Results of bovine serum albumin protein rejection test indicated that susceptibility to fouling decreased with the modification, due to the increased hydrophilicity, while keeping high protein rejection ratio (>99%).

  6. Self-Replenishing Vascularized Fouling-Release Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Howell, C; Vu, TL; Lin, JJ; Kolle, S; Juthani, N; Watson, E; Weaver, JC; Alvarenga, J; Aizenberg, J

    2014-08-13

    Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella sauna, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.

  7. EVALUASI KINERJA HEAT EXCHANGER DENGAN METODE FOULING F

    Directory of Open Access Journals (Sweden)

    Bambang Setyoko

    2012-02-01

    Full Text Available The performance of heat exchangers usually deteriorates with time as a result of accumulation of depositson heat transfer surfaces. The layer of deposits represents additional resistance to heat transfer and causesthe rate of heat transfer in a heat exchanger to decrease. The net effect of these accumulations on heattransfer is represented by a fouling factor Rf , which is a measure of the thermal resistance introduced byfouling.In this case, the type of fouling is the precipitation of solid deposits in a fluid on the heat transfer surface.The mineral deposits forming on the inner and the outer surfaces of fine tubes in the heat exchanger. Thefouling factor is increases with time as the solid deposits build up on the heat exchanger surface. Foulingincreases with increasing temperature and decreasing velocity.In this research, we obtain the coefisien clean overal 5,93 BTU/h.ft2.oF, Dirt factor 0,004 BTU/h.ft2 0F,Pressure drope in tube 2,84 . 10-3 Psi and pressure drope in shell 4,93 . 10-4 Psi.This result are less thanthe standard of parameter. Its means this Heat exchanger still clean relativity and can operate continousslywithout cleaning.

  8. The Effect of Concentration Factor on Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Appana Lok

    2017-09-01

    Full Text Available Bench-scale systems are often used to evaluate pretreatment methods and operational conditions that can be applied in full-scale ultrafiltration (UF systems. However, the membrane packing density is substantially different in bench and full-scale systems. Differences in concentration factor (CF at the solution–membrane interface as a result of packing density may impact the mass transfer and fouling rate and the applicability of bench-scale systems. The present study compared membrane resistance when considering raw water (CF = 1 and reject water (also commonly referred to as concentrate water (CF > 1 as feed in UF systems operated in deposition (dead-end mode. A positive relationship was observed between the concentration of the organic matter in the solution being filtered and resistance. Bench-scale trials conducted with CF = 1 water were more representative of full-scale operation than trials conducted with elevated CFs when considering membrane resistance and permeate quality. As such, the results of this study indicate that the use of the same feed water as used at full-scale (CF = 1 is appropriate to evaluate fouling in UF systems operated in deposition mode.

  9. Nanomaterials for membrane fouling control: accomplishments and challenges.

    Science.gov (United States)

    Yang, Qian; Mi, Baoxia

    2013-11-01

    We report a review of recent research efforts on incorporating nanomaterials-including metal/metal oxide nanoparticles, carbon-based nanomaterials, and polymeric nanomaterials-into/onto membranes to improve membrane antifouling properties in biomedical or potentially medical-related applications. In general, nanomaterials can be incorporated into/onto a membrane by blending them into membrane fabricating materials or by attaching them to membrane surfaces via physical or chemical approaches. Overall, the fascinating, multifaceted properties (eg, high hydrophilicity, superparamagnetic properties, antibacterial properties, amenable functionality, strong hydration capability) of nanomaterials provide numerous novel strategies and unprecedented opportunities to fully mitigate membrane fouling. However, there are still challenges in achieving a broader adoption of nanomaterials in the membrane processes used for biomedical applications. Most of these challenges arise from the concerns over their long-term antifouling performance, hemocompatibility, and toxicity toward humans. Therefore, rigorous investigation is still needed before the adoption of some of these nanomaterials in biomedical applications, especially for those nanomaterials proposed to be used in the human body or in contact with living tissue/body fluids for a long period of time. Nevertheless, it is reasonable to predict that the service lifetime of membrane-based biomedical devices and implants will be prolonged significantly with the adoption of appropriate fouling control strategies. Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  10. Fibrinogen Reduction During Selective Plasma Exchange due to Membrane Fouling.

    Science.gov (United States)

    Ohkubo, Atsushi; Okado, Tomokazu; Miyamoto, Satoko; Hashimoto, Yurie; Komori, Shigeto; Yamamoto, Motoki; Maeda, Takuma; Itagaki, Ayako; Yamamoto, Hiroko; Seshima, Hiroshi; Kurashima, Naoki; Iimori, Soichiro; Naito, Shotaro; Sohara, Eisei; Uchida, Shinichi; Rai, Tatemitsu

    2017-06-01

    Fibrinogen is substantially reduced by most plasmapheresis modalities but retained in selective plasma exchange using Evacure EC-4A10 (EC-4A). Although EC-4A's fibrinogen sieving coefficient is 0, a session of selective plasma exchange reduced fibrinogen by approximately 19%. Here, we investigated sieving coefficient in five patients. When the mean processed plasma volume was 1.15 × plasma volume, the mean reduction of fibrinogen during selective plasma exchange was approximately 15%. Fibrinogen sieving coefficient was 0 when the processed plasma volume was 1.0 L, increasing to 0.07 when the processed plasma volume was 3.0 L, with a mean of 0.03 during selective plasma exchange. When fibrinogen sieving coefficient was 0, selective plasma exchange reduced fibrinogen by approximately 10%. Scanning electron microscopy images revealed internal fouling of EC-4A's hollow fiber membrane by substances such as fibrinogen fibrils. Thus, fibrinogen reduction by selective plasma exchange may be predominantly caused by membrane fouling rather than filtration. © 2017 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.

  11. Identification of effluent organic matter fractions responsible for low-pressure membrane fouling

    KAUST Repository

    Filloux, Emmanuelle

    2012-11-01

    Anion exchange resin (AER), powder activated carbon (PAC) adsorption and ozonation treatments were applied on biologically treated wastewater effluent with the objective to modify the effluent organic matter (EfOM) matrix. Both AER and PAC led to significant total organic carbon (TOC) removal, while the TOC remained nearly constant after ozonation. Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis showed that the AER treatment preferentially removed high and intermediate molecular weight (MW) humic-like structures while PAC removed low MW compounds. Only a small reduction of the high MW colloids (i.e. biopolymers) was observed for AER and PAC treatments. Ozonation induced a large reduction of the biopolymers and an important increase of the low MW humic substances (i.e. building blocks).Single-cycle microfiltration (MF) and ultrafiltration (UF) tests were conducted using commercially available hollow fibres at a constant flux. After reconcentration to their original organic carbon content, the EfOM matrix modified by AER and PAC treatments exhibited higher UF membrane fouling compared to untreated effluent; result that correlated with the higher concentration of biopolymers. On the contrary, ozonation which induced a significant degradation of the biopolymers led to a minor flux reduction for both UF and MF filtration tests. Based on a single filtration, results indicate that biopolymers play a major role in low pressure membrane fouling and that intermediate and low MW compounds have minor impact. Thus, this approach has shown to be a valid methodology to identify the foulant fractions of EfOM. © 2012 Elsevier Ltd.

  12. A novel technology for fouling mitigation and dose reduction in BWR

    International Nuclear Information System (INIS)

    Kim, Young-Jin; Varela, Juan

    2014-01-01

    In a boiling water reactor (BWR), a jet pump provides an internal circulation path for the core coolant flow and consists of four main sections: the nozzle section, inlet mixer section (throat barrel), flare and diffuser. A high velocity coolant flow moves through the nozzles and discharges into the inlet mixer, and over time, oxide particulates (cruds) build up on the inside 304 stainless steel (SS) surfaces of the nozzles and the inlet mixer forming a layer of crud fouling. Cruds are typically removed from the surfaces of BWR components during regularly scheduled shutdowns of the reactor that is highly costly. Thus, a cost-effective is being developed to mitigate the crud fouling and the accumulation of radioactive species by using a colloid-based process. A colloid-based process can be applied to components in service, and does not require extensive equipment and extreme processing parameters as compared to other deposition processes and is not limited by geometric constraints as is the CVD process. Several parameters, such as concentration of TiO 2 nanoparticle, deposition/post-annealing temperature, and hydrodynamic flow condition, etc., for developing the optimum TiO 2 coating process have been examined to identify the most critical condition that can be applicable at plants. Preliminary results showed that the post-annealing treatment of coating is essential for improving the adherence and coherence of colloidal TiO 2 nanoparticles to the substrate. In addition, the presence of oxide on the coating surface is detrimental to the coating durability and thus pre-existing oxide surfaces require to be cleaned before coating. (author)

  13. Microaerophilic conditions permit to mimic in vitro events occurring during in vivo Helicobacter pylori infection and to identify Rho/Ras-associated proteins in cellular signaling.

    Science.gov (United States)

    Cottet, Sandra; Corthésy-Theulaz, Irène; Spertini, François; Corthésy, Blaise

    2002-09-13

    Molecular dissection of the mechanisms underlying Helicobacter pylori infection suffers from the lack of in vitro systems mimicking in vivo observations. A system was developed whereby human epithelial cells (Caco-2) grown as polarized monolayers and bacteria can communicate with each other under culture conditions optimal for each partner. Caco-2 cells grown on filter supports were inserted in a vertical position into diffusion chambers equilibrated with air and 5% CO(2) at their basolateral surface (aerophilic conditions) and 5% CO(2), 5% O(2), 90% N(2) (microaerophilic conditions) in the apical compartment. Remarkably, the epithelial polarized layer was stable under these asymmetric culture conditions for at least 24 h, and the presence of Caco-2 cells was necessary to maintain H. pylori growth. In contrast to previous studies conducted with non-polarized Caco-2 cells and other cell lines kept under aerophilic conditions, we found H. pylori-dependent stimulation of cytokine secretion (MCP-1 (monocyte chemoattractant protein-1), GRO-alpha (growth-regulated oncogene-alpha), RANTES (regulated on activation normal T cell expressed and secreted)). This correlated with nuclear translocation of NF-kappaB p50 and p65 subunits. Tyrosine phosphorylation of nine cellular proteins was induced or enhanced; we identified p120(RasGAP), p190(RhoGAP), p62dok (downstream of tyrosine kinases), and cortactin as H. pylori-inducible targets. Moreover, reduction of H. pylori urease expression was observed in adherent bacteria as compared with bacteria in suspension. In addition to mimicking several observations seen in the inflamed gastric mucosa, the novel in vitro system was allowed to underscore complex cellular events not seen in classical in vitro analyses of microaerophilic bacteria-epithelial cell cross-talk.

  14. Heat transfer fouling characteristics of microfiltered thin stillage from the dry grind process.

    Science.gov (United States)

    Arora, Amit; Dien, Bruce S; Belyea, Ronald L; Singh, Vijay; Tumbleson, M E; Rausch, Kent D

    2010-08-01

    We investigated effects of microfiltration (MF) on heat transfer fouling tendencies of thin stillage. A stainless steel MF membrane (0.1 micron pore size) was used to remove solids from thin stillage. At filtration conditions of 690kPa, the MF process effectively recovered total solids from thin stillage. Thin stillage was concentrated from 7.0% to 22.4% solids with average permeate flux rates of 180+/-30 L/m(2)/h at 75 degrees C. In retentate streams, protein and fat contents were increased from 23.5 and 16.7% db to 27.6 and 31.1% db, respectively, and ash content was reduced from 10.5% to 3.8% db. Removal of solids, protein and fat generated a microfiltration permeate (MFP) that was used as an input stream to the fouling probe system; MFP fouling tendencies were measured. An annular fouling probe was used to measure fouling tendencies of thin stillage from a commercial dry grind facility. When comparing diluted thin stillage (DTS) stream and MFP, a reduction in solids concentration was not the only reason of fouling decrement. Selective removal of protein and fat played an important role in mitigating the fouling. At t=10h, mean fouling rates of MFP were an order of magnitude lower when compared to thin stillage and diluted streams. When maximum probe temperature (200 degrees C) was reached, mean fouling rates for thin stillage, DTS and MFP were 7.1x10(-4), 4.2x10(-4) and 2.6x10(-4) m(2) degrees C/kW/min, respectively. In DTS and MFP, the induction period was prolonged by factors of 4.3 and 9.5, respectively, compared to the induction period for thin stillage fouling. Mean fouling rates were decreased by factors of 2.3 and 23.4 for DTS and MFP, respectively. Fouling of MFP took twice the time to reach a probe temperature of 200 degrees C than did thin stillage (22 h vs 10 h, respectively). A reduction in heat transfer fouling could be achieved by altering process stream composition using microfiltration. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Analysis of the influence of operating conditions on fouling rates in fired heaters

    International Nuclear Information System (INIS)

    Morales-Fuentes, A.; Picón-Núñez, M.; Polley, G.T.; Méndez-Díaz, S.

    2014-01-01

    Fouling due to chemical reaction in preheat trains for the processing of crude oil plays a key role in the operation and maintenance costs and on greenhouse emissions to atmosphere in crude processing plants. A preheat train consists of a set of heat transfer units that provide the crude oil stream the required amount of thermal energy to reach its target temperature either by heat recovery or by direct firing. Fired heaters supply external high temperature heating through the burning of fuel which result in complex heat transfer processes due to the large temperature and pressure changes and vaporization that takes place inside the unit. In this work, a thermo-hydraulic analysis of the performance of fired heaters is carried out through the application of commercial software to solve the mathematical models using finite difference methods; the analysis is applied to the crude side of a vertical fired heater in order to evaluate the impact of process conditions such as throughput and crude inlet temperature (CIT) on the fouling that take place at the early stages of operation. Using a fouling rate model based on thermo-hydraulic parameters, fouling rates are predicted assuming steady state operation and clean conditions. Although variations in process conditions are known to influence fouling rates, little work has been done on the subject. In this work excess air and steam injection are studied as a means to mitigate fouling. Results show that throughput reduction brings about a marked increase in the fouling rates. A decrease in CIT affects only the convection zone and it is found that this effect is negligible. In terms of excess air, it is found that although it affects negatively the heater efficiency it can be used to balance heat transfer between the convection and radiation zone in a way that fouling rates are reduced; however this strategy should be considered right from the design stage. Finally it is observed that steam injection is an effective method

  16. The influence of hydrodynamic factors, membrane surface properties and channel geometries on membrane performance and fouling mechanisms

    Directory of Open Access Journals (Sweden)

    Pervov Alexey

    2016-01-01

    Full Text Available Modern theoretical understanding of colloidal and suspended matter membrane fouling mechanisms are presented and discussed. State-of-the-art simulation models of concentration polarization calculations for different channel conditions are described and influence of the fouling layers on the flux and rejection decrease are evaluated. Results of experimental investigations are presented that suggest a quantitative evaluation of fouling rates and membrane flux prognosis due to colloidal fouling with time. The influence of channel geometry on fouling is demonstrated and discussed. The main disadvantage of spiral wounded membrane modules which is attributed to the presence of a separation spacer mesh in the feed channel is discussed.

  17. The Thermal Hydraulics of Tube Support Fouling in Nuclear Steam Generators

    International Nuclear Information System (INIS)

    Rummens, Helena E.C.; Rogers, J.T.; Turner, C.W.

    2004-01-01

    It is hypothesized that the thermal-hydraulic environment plays a role in the fouling of tube supports in nuclear steam generators. Experiments were performed to simulate the thermal-hydraulic environment near various designs of supports. Pressure loss, local velocity, turbulence intensity, and local void fraction were measured to characterize the effect of the support. Fouling mechanisms specific to supports were inferred from these experimental data and from actual steam generator inspection results. An analytical model was developed to predict the rate of particulate deposition on the supports, to better understand the complex processes involved.This paper presents the following set of tools for assessing the fouling propensity of a given support design: (1) proposed fouling mechanisms, (2) criteria for support fouling propensity, (3) correlation of fouling with parameters such as mass flux and quality, (4) descriptions of experimental tools such as flow visualization and measurement of pressure-loss profiles, and (5) analytical tools.An important conclusion from this and our previous work is that the fouling propensity is greater with broached support plates, both trefoil and quatrefoil, than with lattice bar supports and formed bar supports, in which significant cross flows occur

  18. Characterization of biofoulants illustrates different membrane fouling mechanisms for aerobic and anaerobic membrane bioreactors

    KAUST Repository

    Xiong, Yanghui

    2015-11-17

    This study compares the membrane fouling mechanisms of aerobic (AeMBR) and anaerobic membrane bioreactors (AnMBR) of the same reactor configuration at similar operating conditions. Although both the AeMBR and AnMBR achieved more than 90% COD removal efficiency, the fouling mechanisms were different. Molecular weight (MW) fingerprint profiles showed that a majority of fragments in anaerobic soluble microbial products (SMP) were retained by the membrane and some fragments were present in both SMP and in soluble extracellular polymeric substances (EPS), suggesting that the physical retention of SMP components contributed to the AnMBR membrane fouling. One of the dominant fragments was comprised of glycoliproprotein (size 630-640 kD) and correlated in abundance in AnMBR-EPS with the extent of anaerobic membrane fouling. In contrast, all detected AeMBR-SMP fragments permeated through the membrane. Aerobic SMP and soluble EPS also showed very different fingerprinting profiles. A large amount of adenosine triphosphate was present in the AeMBR-EPS, suggesting that microbial activity arising from certain bacterial populations, such as unclassified Comamonadaceae and unclassified Chitinophagaceae, may play a role in aerobic membrane fouling. This study underlines the differences in fouling mechanisms between AeMBR and AnMBR systems and can be applied to facilitate the development of appropriate fouling control strategies.

  19. Characteristics of membrane fouling in submerged membrane bioreactor under sub-critical flux operation.

    Science.gov (United States)

    Su, Y C; Huang, C P; Pan, Jill R; Lee, H C

    2008-01-01

    Recently, the membrane bioreactor (MBR) process has become one of the novel technologies to enhance the performance of biological treatment of wastewater. Membrane bioreactor process uses the membrane unit to replace a sediment tank, and this can greatly enhance treatment performance. However, membrane fouling in MBR restricts its widespread application because it leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary, which then increases operating and maintenance costs. This study investigated the sludge characteristics in membrane fouling under sub-critical flux operation and also assessed the effect of shear stress on membrane fouling. Membrane fouling was slow under sub-critical flux operation. However, as filamentous microbes became dominant in the reactor, membrane fouling increased dramatically due to the increased viscosity and polysaccharides. A close link was found between membrane fouling and the amount of polysaccharides in soluble EPS. The predominant resistance was the cake resistance which could be minimized by increasing the shear stress. However, the resistance of colloids and solutes was not apparently reduced by increasing shear stress. Therefore, smaller particles such as macromolecules (e.g. polysaccharides) may play an important role in membrane fouling under sub-critical flux operation.

  20. Fouling characteristics and cleaning strategies of NF membranes for the advanced treatment of antibiotic production wastewater.

    Science.gov (United States)

    Wang, Jianxing; Li, Kun; Yu, Dawei; Zhang, Junya; Wei, Yuansong

    2017-04-01

    The nanofiltration (NF) membrane fouling characteristics and cleaning strategies were investigated through a laboratory-scale NF fouling test treating membrane bioreactor (MBR) effluent and MBR-granular activated carbon (GAC) effluent of an antibiotic production wastewater by DK and NF90 membranes, respectively. Results showed that organic fouling is the main NF membrane fouling for treating both the MBR effluent and MBR-GAC effluent. Soluble microbial by-product (SMP)-like and aromatic protein-like substances were the dominant components in the foulants, whereas humic-like substances had little contribution to the NF fouling. The fouling of DK was more severe than that of NF90. However, foulants respond by UV 254 were more easily to foul NF90 membrane. It could get satisfactory effect using combined cleaning of acid (HCl, pH 2.0∼2.5) and alkali (NaOH + 0.3 wt% NaDS, pH 10.0∼10.5). The favorable cleaning strategy is "acid + alkali" for treating MBR-GAC effluent, while it is "alkali + acid" for treating MBR effluent.

  1. Irreversible membrane fouling abatement through pre-deposited layer of hierarchical porous carbons

    KAUST Repository

    Hamad, Juma

    2014-11-01

    In this work, dual-templated hierarchical porous carbons (HPCs), produced from a coupled ice-hard templating approach, are shown to be a highly effective solution to the commonly occurring problem of irreversible fouling of low-pressure membranes used for pre-treatment in wastewater reuse. For the first time, dual-templated HPCs, along with their respective counterparts - single-templated meso-porous carbon (MPCs) (without macropores) - are tested in terms of their fouling reduction capacity and ability to remove different effluent organic matter fractions present in wastewater and compared with a commercially available powdered activated carbon (PAC). The synthesized HPCs provided exceptional fouling abatement, a 4-fold higher fouling reduction as compared to the previously reported best performing commercial PAC and ~2.5-fold better fouling reduction than their respective mesoporous counterpart. Thus, it is shown that not only mesoporosity, but macroporosity is also necessary to achieve high fouling reduction, thus emphasizing the need for dual templating. In the case of HPCs, the pre-deposition technique is also found to outperform the traditional sorbent-feed mixing approach, mainly in terms of removal of fouling components. Based on their superior performance, a high permeability (ultra-low-pressure) membrane consisting of the synthesized HPC pre-deposited on a large pore size membrane support (0.45μm membrane), is shown to give excellent pre-treatment performance for wastewater reuse application. © 2014 Elsevier Ltd.

  2. Mini-review: impact and dynamics of surface fouling by solitary and compound ascidians.

    Science.gov (United States)

    Aldred, Nick; Clare, Anthony S

    2014-01-01

    Globally, ascidians are a significant contributor to benthic marine fouling communities, but have remained poorly studied in this context. In some cases, such as in shellfish and finfish aquaculture, ascidians are the most problematic of all fouling organisms. The disproportionate impact of ascidian fouling in some specific geographic locations has been related directly to anthropogenic translocation of these organisms around the globe. In the case of ascidians, therefore, the economic issue of biofouling and the ecological ramifications of invasion are inextricably linked. This mini-review briefly discusses the introduction of non-native ascidians to areas where they have subsequently proven to be a significant fouling pest. The elements of ascidian reproductive ecology that support their aggressive fouling character are discussed and the scant information pertaining to their adhesion and adhesives is presented. Finally, strategies for mitigating ascidian fouling are examined. It is suggested that sufficient working knowledge currently exists to support the inclusion of one or more common ascidian species as 'standard' test organisms used for evaluation of novel fouling-resistant surfaces.

  3. Effect of fouling on removal of trace organic compounds by nanofiltration

    Directory of Open Access Journals (Sweden)

    S. Hajibabania

    2011-12-01

    Full Text Available The fate of chemical of concern is not yet fully understood during treatment of impaired waters. The aim of this paper is to assess the impact of different organic-based fouling layers on the removal of a large range of trace organics. Both model and real water samples (mixed with trace organic contaminants at environmental concentration of 2 μg l−1 were used to simulate fouling in nanofiltration under controlled environment. The new and fouled membranes were systematically characterised for surface charge, hydrophobicity and roughness. It was observed that fouling generally reduced the membrane surface charge; however, the alterations of the membrane hydrophobicity and surface roughness were dependent on the foulants composition. The rejection of charged trace organics was observed to be improved due to the increased electrostatic repulsion by fouled membranes and the adsorption of the trace organic chemicals onto organic matters. On the other hand, the removal of nonionic compounds decreased when fouling occurred, due to the presence of cake enhanced concentration polarization. The fouling layer structure was found to play an important role in the rejection of the trace organic compounds.

  4. Investigation of severe UF membrane fouling induced by three marine algal species

    KAUST Repository

    Merle, Tony

    2016-02-06

    Reducing membrane fouling caused by seawater algal bloom is a challenge for regions of the world where most of their freshwater is produced by seawater desalination. This study aims to compare ultrafiltration (UF) fouling potential of three ubiquitous marine algal species cultures (i.e., Skeletonena costatum-SKC, Tetraselmis sp.-TET, and Hymenomonas sp.-HYM) sampled at different phases of growth. Results showed that flux reduction and irreversible fouling were more severe during the decline phase as compared to the exponential phase, for all species. SKC and TET were responsible for substantial irreversible fouling but their impact was significantly lower than HYM. The development of a transparent gel layer surrounding the cell during the HYM growth and accumulating in water is certainly responsible for the more severe observed fouling. Chemical backwash with a standard chlorine solution did not recover any membrane permeability. For TET and HYM, the Hydraulically Irreversible Fouling Index (HIFI) was correlated to their biopolymer content but this correlation is specific for each species. Solution pre-filtration through a 1.2 μm membrane proved that cells and particulate algal organic matter (p-AOM) considerably contribute to fouling, especially for HYM for which the HIFI was reduced by a factor of 82.3.

  5. Membrane filtration device for studying compression of fouling layers in membrane bioreactors.

    Directory of Open Access Journals (Sweden)

    Mads Koustrup Jørgensen

    Full Text Available A filtration devise was developed to assess compressibility of fouling layers in membrane bioreactors. The system consists of a flat sheet membrane with air scouring operated at constant transmembrane pressure to assess the influence of pressure on resistance of fouling layers. By fitting a mathematical model, three model parameters were obtained; a back transport parameter describing the kinetics of fouling layer formation, a specific fouling layer resistance, and a compressibility parameter. This stands out from other on-site filterability tests as model parameters to simulate filtration performance are obtained together with a characterization of compressibility. Tests on membrane bioreactor sludge showed high reproducibility. The methodology's ability to assess compressibility was tested by filtrations of sludges from membrane bioreactors and conventional activated sludge wastewater treatment plants from three different sites. These proved that membrane bioreactor sludge showed higher compressibility than conventional activated sludge. In addition, detailed information on the underlying mechanisms of the difference in fouling propensity were obtained, as conventional activated sludge showed slower fouling formation, lower specific resistance and lower compressibility of fouling layers, which is explained by a higher degree of flocculation.

  6. CEGB research on the effects of fouling of plastic packings on natural draught cooling tower performance

    International Nuclear Information System (INIS)

    Winter, R.J.

    1989-01-01

    Plastic film packings were first used in CEGB natural draught cooling towers in 1985. Since then, cooling towers at seven power stations have been repacked using various commercial designs of plastic packing, with generally satisfactory results in economic terms. However, fouling of all the packings has occurred to some extent, ranging from very thin films on the surface of the sheets, which actually enhances performance, to heavy and voluminous formations which severely constrict the inter-sheet passages, causing performance loss and threatening the structural integrity of the whole fill. At CERL, methods have been developed to relate the degree of fouling to the thermal performance loss. This information is enabling accurate calculations to be made of the economics of repacking. Samples of fouled packing from operation towers are tested using the Experimental Cooling Tower at the Central Electricity Research Laboratories at Leatherhead. A systematic investigation is also underway of the changes in pressure drop and mass transfer coefficients which take place as fouling develops, using progressively-fouled packing samples from a purpose-built Packing Fouling Facility located at one of the power stations. The performance data obtained is fed-back into models by which the effect of high fouling loadings on various packings is calculated, enabling packing economic life to be predicted

  7. Improving the reliability of open-cycle water systems: Application of biofouling surveillance and control techniques to sediment and corrosion fouling at nuclear power plants

    International Nuclear Information System (INIS)

    Johnson, K.I.; Neitzel, D.A.

    1987-03-01

    Biofouling surveillance and control techniques are evaluated for their applicability to sediment and corrosion fouling and suggestions are given to improve their effectiveness. Alternate techniques to better detect and control sedimentation and corrosion are also evaluated. Environmental conditions that allow biofouling, sedimentation, and corrosion to occur are summarized. A correlation between sediment and corrosion is identified and the causes are described. Environmental regulations, especially those in the Clean Water Act of 1977, are reviewed to identify those that may limit or prevent the use of surveillance and control techniques described in this report. Flow velocity is the major design factor that determines whether or not biofouling, sedimentation, and corrosion will occur. Monitoring flow conditions can provide early warning of conditions that will allow fouling to occur. Visual inspection is the most common and most effective technique for identifying the cause and extent of fouling in the open-cycle water system. Most biofouling control techniques in current use are not effective against sediment and corrosion. Frequent, high-velocity flushing of cooling loops may effectively remove sediment and reduce under-sediment corrosion. Alternate biocide treatments such as targeted chlorination or the use of ozone or 2,2-dibromo-3-nitrilo propionamide (DBNPA) may also be effective in reducing under-sediment corrosion

  8. Effect of resins of heat exchanger fouling by asphaltene-containing oils

    Energy Technology Data Exchange (ETDEWEB)

    Al-Atar, E.; Watkinson, A.P. [British Columbia Univ., Dept. of Chemical and Bio-Resource Engineering, Vancouver, BC (Canada)

    1999-07-01

    The effects of resins on the thermal fouling of asphaltene containing oils in heat exchangers was investigated as well as the nature of the deposits. Building on previous research, a sample of de-asphalted vacuum bottoms (DAO), serving as a source of natural resins, heavy oil (HO) and fuel oil was used to investigate the effects of resin concentration on the rate of thermal fouling. The conditions of the study included: fluid circulation through the UBC annular fouling test section for up to 30 hour periods, monitoring of thermal fouling by measurement, and nitrogen atmospheres at a bulk temperature of 85 degrees C, a bulk velocity of 0.85 am/s, and a pressure of 410 kPa. Physical and chemical characterization of the deposits was affected, and filtration at the bulk temperature before and after a run was used to determine the occurrence of fine solids in the fluid. The rate of fouling generally decreased tending generally towards asymptotic behavior in the limit, and after one day Rf values up to 0.3 m2K/kW occurred with severe fouling. An increase in the fouling rate occurred with increased DAO concentration in the mixture, at a fixed heavy oil concentration of 5 weight percent, and the relation between Asomaning's colloidal instability index and the trends in fouling rate was not observed, although there were some indications of reduced fouling as there was an increase in the ratio of resins to asphaltenes, however, blends of the DAO-HO-FO helped to control the concentration of asphaltenes and resins that are possible. (Abstract only).

  9. Seawater ultrafiltration fouling control: Backwashing with demineralized water/SWRO permeate

    KAUST Repository

    Li, Sheng; Heijman, Sebastiaan G J; Verberk, J. Q J C; Amy, Gary L.; Van Dijk, Johannis C.

    2012-01-01

    In this study, the effect of demineralized water backwashing on fouling control of seawater ultrafiltration was investigated. Seawater from Scheveningen beach in The Hague and a desalination plant of Evides Company at Zeeland in the Netherlands was used as feed water, while demineralized water and UF permeate were used as backwash water for a fouling control efficiency comparison under different fluxes and backwash durations. Furthermore, demineralized waters with 5 or 50 mmol/l NaCl were applied for backwashing as well, to check the influence of monovalent cations on UF fouling control. Additionally, SWRO permeate was used for backwashes in long-term experiments to check the possibility of it replacing demineralized water. Results show that seawater UF fouling control is substantially improved by demineralized water backwashing. However, due to the high salinity of seawater, more water was required to dilute the cation concentration and limit the dispersion effect near the membrane surface than was needed for surface water. A 2-min demineralized water backwash showed better fouling control efficiency than a 1-min backwash. Furthermore, the presence of monovalent cations in the backwash water deteriorated the fouling control efficiency of the backwash, indicating the existence of a charge screening effect. The demineralized water with 5 and 50 mmol/l NaCl both showed a similar fouling control efficiency which is better than the UF permeate backwash. The calcium ions in UF permeate probably deteriorates the fouling control efficiency by maintaining a Ca-bridging effect between the membranes and NOM. SWRO permeate backwashing successfully controls membrane fouling as well. © 2012 Elsevier B.V. All rights reserved.

  10. The effect of surface chemistry on particulate fouling under flow-boiling conditions

    International Nuclear Information System (INIS)

    Turner, C.W.; Klimas, S.J.

    2001-01-01

    A model of particulate fouling has been developed that takes account of the influence of deposit consolidation on the kinetics of the fouling process. Fouling kinetics predicted by the model are linear, falling-rate or asymptotic, depending on the relative magnitudes of the rate constants for deposition, re-entrainment, and consolidation. One of the key predictions of the model is that the steady-state fouling rate is proportional to the ratio Kλ c /λ, where K, λ c and λ are the rate constants for deposition, consolidation, and removal, respectively. Tests conducted in a high-temperature recirculating-water loop have demonstrated that chemistry exerts a strong influence on the fouling kinetics of particulate corrosion product under flow-boiling conditions in alkaline water at 270 o C. For example, the fouling rates of lepidocrocite and hematite are 12 and 50 times greater, respectively, than the rate for magnetite. It is argued that the difference can be attributed to the sign of the surface charge that develops on the metal oxide surfaces in the high-temperature coolant, which, in turn, is a function of pH relative to the isoelectric point of the metal oxide. Chemical effects also influence fouling behaviour through the rate of consolidation. For example, when morpholine is used for the alkalizing agent the fouling rate is 3-5 times higher than the case when the pH is controlled using dimethylamine. The difference is attributed to the rate of deposit consolidation, which is 6-20 times greater than the rate of deposit removal for morpholine compared to 0.2-0.3 times the rate of removal for dimethylamine. The results of this investigation, together with the insights provided by the fouling model, are being used to guide the selection of the alkalizing amine to optimize its properties for both corrosion (pH) control and deposit control in the steam generator. (author)

  11. Seawater ultrafiltration fouling control: Backwashing with demineralized water/SWRO permeate

    KAUST Repository

    Li, Sheng

    2012-09-01

    In this study, the effect of demineralized water backwashing on fouling control of seawater ultrafiltration was investigated. Seawater from Scheveningen beach in The Hague and a desalination plant of Evides Company at Zeeland in the Netherlands was used as feed water, while demineralized water and UF permeate were used as backwash water for a fouling control efficiency comparison under different fluxes and backwash durations. Furthermore, demineralized waters with 5 or 50 mmol/l NaCl were applied for backwashing as well, to check the influence of monovalent cations on UF fouling control. Additionally, SWRO permeate was used for backwashes in long-term experiments to check the possibility of it replacing demineralized water. Results show that seawater UF fouling control is substantially improved by demineralized water backwashing. However, due to the high salinity of seawater, more water was required to dilute the cation concentration and limit the dispersion effect near the membrane surface than was needed for surface water. A 2-min demineralized water backwash showed better fouling control efficiency than a 1-min backwash. Furthermore, the presence of monovalent cations in the backwash water deteriorated the fouling control efficiency of the backwash, indicating the existence of a charge screening effect. The demineralized water with 5 and 50 mmol/l NaCl both showed a similar fouling control efficiency which is better than the UF permeate backwash. The calcium ions in UF permeate probably deteriorates the fouling control efficiency by maintaining a Ca-bridging effect between the membranes and NOM. SWRO permeate backwashing successfully controls membrane fouling as well. © 2012 Elsevier B.V. All rights reserved.

  12. Flux dependency of particulate/colloidal fouling in seawater reverse osmosis systems

    KAUST Repository

    Salinas Rodríguez, S. G.

    2012-01-01

    Fouling is the main operational problem in seawater reverse osmosis systems (SWRO). Particulate fouling is traditionally measured through the silt density index (SDI) and through the modified fouling index (MFI). In recent years, ultrafiltration membranes were used successfully at constant flux-MFI-UF-to measure particulate/colloidal fouling potential and tested in sea water applications. Furthermore, constant flux operation allows predicting the rate of fouling in RO systems. The objectives of this study are: (1) to measure the flux effect in MFI-UF with different membranes (100, 30 and 10 kDa) for raw seawater and pre-treated water before reverse osmosis in three different locations; (2) to study the particulate and colloidal fouling potential of seawater in reverse osmosis systems; (3) to project the increase in pressure due to cake resistance in reverse osmosis systems. In this research, flat ultrafiltration membranes (100, 50, 30 and 10 kDa) are used in a con- stant flux filtration mode to test and compare real seawaters from various locations (North and Mediterranean Sea) and from various full scale facilities including different pre-treatments (i.e., ultrafiltration and coagulation + dual media filtration). The operated fluxes range from 350 down to values close to real RO operation, 15l(m2h)-1. After each filtration test, the MFI-UF is calculated to assess the particulate fouling potential. The obtained results showed that: (1) the particulate and colloidal fouling potential is directly proportional to the applied flux during filtration. This proportionality is related to the compression of the cake deposit occurring at high flux values; (2) the higher the flux, the higher the required pressure, the less porous the cake and therefore the higher the specific cake resistance; (3) particulate and colloidal fouling potential of seawater is site specific and is influenced by pre-treatment. © 2012 Desalination Publications. All rights reserved.

  13. Performance evaluation of a once-through multi-stage flash distillation system: Impact of brine heater fouling

    International Nuclear Information System (INIS)

    Baig, Hasan; Antar, Mohamed A.; Zubair, Syed M.

    2011-01-01

    Multi-stage flash distillation (MSF) system modeling involves a number of process variables. An estimation of all these process variables requires both analytical solutions and experimental/field analysis. However, the accurate estimate of variables related to the brine heater operation in a MSF system is very important for a reliable operation of the system. For example, steam operating conditions as well as the brine properties including fouling of the brine heater tubes have a significant effect on the heat transfer characteristics of the brine heater, which in turn influence the distillate output from the system. In this study, the effect of various design as well as operating conditions on the performance ratio (PR), brine temperature and salinity as it leaves the last flash stage are investigated in a once-through system. Increasing the number of stages from 24 to 32 has a significant effect on the PR, it ranges between 79% (for ΔT = 1.5) and 327% (for ΔT = 2.3) for a top-brine temperature of 106 o C. This value increase as the top-brine temperature increases. Increasing the stage-to-stage temperature difference increases the water salinity as it leaves the final stage and reduces its temperature that would imply better energy utilization within the plant. Results show that brine side heat exchanger fouling has a significant effect in decreasing the overall heat transfer coefficient, which reduces the production rate as the fouling increases with time. A sensitivity analysis to identify the key parameters, which can have a significant influence on the desalination plant performance, is carried out in an attempt to contribute a better understanding and operation of MSF desalination processes.

  14. Fouling Bryozoa from some Alexandria harbours, EGYPT. (I Erect species

    Directory of Open Access Journals (Sweden)

    KH.M. ABDEL-SALAM

    2008-05-01

    Full Text Available The fouling erect Bryozoa settled on polystyrene test panels immersed half a meter deep in the water of Abu Qir Harbour, the Eastern Harbour and El-Dekheila Harbour were studied. The present study yields 5 species of erect bryozoa. These areAmathia pruvoti, Zoobotryon verticillatum, Bowerbankia gracilis,Bugula neritina and Bugula stolonifera. The first three ones pertain to 3 genera of the family Vesiculariidae belonging to suborder the Stolonifera; while the other two species affiliate to the genus Bugula belonging to the family Bugulidae of suborder Anasca. The present record of Amathia pruvoti is the first from the Egyptian Mediterranean waters. A re-description, supplied with full structural illustrations of the recorded species is given. Moreover, the temporal and spatial distributions of the species recorded are encountered.

  15. A new concept for anti-fouling paint for Yachts

    DEFF Research Database (Denmark)

    Wallstroem, Eva; Jespersen, Henrik T.; Schaumburg, Kjeld

    2011-01-01

    It is shown to be possible to develop yacht paint with a reduction of 70% of biocide, without pigments/fillers (cuprous oxide and zinc oxide) that may cause long-term adverse effects in the aquatic environment, and to obtain application and usage properties that match present commercial anti......-fouling products for yachts. To be able to reduce the amount of biocide, in this case zinc pyrithione, it is necessary to have control over the amount of biocide present in the surface layer. The control is achieved by encapsulating the biocide in a silica gel. The silica gel is dispersed together with pigments...... that is formulated without introducing new compounds and with reduced amount of zinc pyrithione (1/3). Finally, it is shown that it is possible to make antifouling paint for yachts without zinc or copper based pigments by using other traditional pigments and fillers, which have no known long-term adverse effect...

  16. Temperature and body weight affect fouling of pig pens.

    Science.gov (United States)

    Aarnink, A J A; Schrama, J W; Heetkamp, M J W; Stefanowska, J; Huynh, T T T

    2006-08-01

    Fouling of the solid lying area in pig housing is undesirable for reasons of animal welfare, animal health, environmental pollution, and labor costs. In this study the influence of temperature on the excreting and lying behavior of growing-finishing pigs of different BW (25, 45, 65, 85, or 105 kg) was studied. Ten groups of 5 pigs were placed in partially slatted pens (60% solid concrete, 40% metal-slatted) in climate respiration chambers. After an adaptation period, temperatures were raised daily for 9 d. Results showed that above certain inflection temperatures (IT; mean 22.6 degrees C, SE = 0.78) the number of excretions (relative to the total number of excretions) on the solid floor increased with temperature (mean increase 9.7%/ degrees C, SE = 1.41). Below the IT, the number of excretions on the solid floor was low and not influenced by temperature (mean 13.2%, SE = 3.5). On average, the IT for excretion on the solid floor decreased with increasing BW, from approximately 25 degrees C at 25 kg to 20 degrees C at 100 kg of BW (P temperature also affected the pattern and postural lying. The temperature at which a maximum number of pigs lay on the slatted floor (i.e., the IT for lying) decreased from approximately 27 degrees C at 25 kg to 23 degrees C at 100 kg of BW (P temperatures, pigs lay more on their sides and less against other pigs (P Temperature affects lying and excreting behavior of growing-finishing pigs in partially slatted pens. Above certain IT, pen fouling increases linearly with temperature. Inflection temperatures decrease at increasing BW.

  17. Application of electrochemical impedance spectroscopy to monitor seawater fouling on stainless steels and copper alloys

    International Nuclear Information System (INIS)

    Feron, D.

    1991-01-01

    Electrochemical impedance spectroscopy may be applied to detect and to follow seawater fouling. Experiments have been conducted with natural seawater flowing inside tube-electrodes at temperatures between 30 deg C and 85 deg C. With stainless steel tubes, mineral and organic foulings have been followed; a linear relationship between the dry weight of the organic fouling and its electrical resistance, has been observed. On copper alloy tubes, only mineral deposits have occurred and so have been detected by impedance spectroscopy. (Author). 5 refs., 6 figs

  18. Effects of salinity on the characteristics of biomass and membrane fouling in membrane bioreactors

    DEFF Research Database (Denmark)

    Jang, D.; Hwang, Yuhoon; Shin, H.

    2013-01-01

    This study investigated the effects of high salinity on the performance and membrane fouling of membrane bioreactor (MBR) with saline wastewater. Synthetic wastewaters containing 5-20g/L salts (NaCl) were treated in identical lab-scale (7L) MBRs monitoring removals of dissolved organic carbon (DOC......; and the changes in microbial composition in turn have affected the performance of the MBRs. Membrane fouling was accelerated by the increased pore blocking resistance at higher salt concentrations. Analysis results of physicochemical and biological characteristics of biomass (EPS, floc size, zeta potential......) verified the impacts of high salinity on the increased membrane fouling....

  19. Coke fouling process on the oil refining; Processo de incrustacao por coque no refino do petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Bombardelli, Clovis; Fiorentin, Leila D.; Negrao, Cezar O.R.; Franco, Admilson T. [Centro Federal de Educacao Tecnologica do Parana (CEFET-PR), Curitiba, PR (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica e de Materiais (PPGEM)

    2004-07-01

    The heavy crude fraction processing is performed under very high vacuum to minimize thermal cracking which cause coke deposition and damage the equipment. The current tendency is to process heavier oil leading to higher process temperatures and consequently to greater fouling. This situation demands better knowledge fouling process by carbonization. This problem is pronounced in the residual gasoil region of a vacuum distillation unit because it obstructs the recirculation circuits and the spray system with serious environmental and economics implications. This paper review the main correlated published work related to coke generation and fouling and presents a discussion about the works. (author)

  20. The effect of hydraulic retention time on the performance and fouling characteristics of membrane sequencing batch reactors used for the treatment of synthetic petroleum refinery wastewater.

    Science.gov (United States)

    Shariati, Seyed Ramin Pajoum; Bonakdarpour, Babak; Zare, Nasim; Ashtiani, Farzin Zokaee

    2011-09-01

    The use of membrane sequencing batch reactors, operated at HRT of 8, 16 and 24h, was considered for the treatment of a synthetic petroleum wastewater. Increase in HRT resulted in statistically significant decrease in MLSS. Removal efficiencies higher than 97% were found for the three model hydrocarbon pollutants at all HRTs, with air stripping making a small contribution to overall removal. Particle size distribution (PSD) and microscopic analysis showed reduction in the protozoan populations in the activated sludge with decreasing HRT. PSD analysis also showed a higher proportion of larger and smaller sized particles at the lowest HRT. The rate of membrane fouling was found to increase with decreasing HRT; SMP, especially carbohydrate SMP, and mixed liquor apparent viscosity also showed a pronounced increase with decreasing HRT, whereas the concentration of EPS and its components decreased. FTIR analysis identified organic compounds as the main component of membrane pore fouling. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Performance and membrane fouling of a step-fed submerged membrane sequencing batch reactor treating swine biogas digestion slurry.

    Science.gov (United States)

    Han, Zhiying; Chen, Shixia; Lin, Xiaochang; Yu, Hongjun; Duan, Li'an; Ye, Zhangying; Jia, Yanbo; Zhu, Songming; Liu, Dezhao

    2018-01-02

    To identify the performance of step-fed submerged membrane sequencing batch reactor (SMSBR) treating swine biogas digestion slurry and to explore the correlation between microbial metabolites and membrane fouling within this novel reactor, a lab-scale step-fed SMSBR was operated under nitrogen loading rate of 0.026, 0.052 and 0.062 g NH 4 + -N (gVSS·d) -1 . Results show that the total removal efficiencies for NH 4 + -N, total nitrogen and chemical oxygen demand in the reactor (>94%, >89% and >97%, respectively) were high during the whole experiment. However, the cycle removal efficiency of NH 4 + -N decreased significantly when the nitrogen loading rate was increased to 0.062 g NH 4 + -N (gVSS·d) -1 . The total removal efficiency of total phosphorus in the step-fed SMSBR was generally higher than 75%, though large fluctuations were observed during the experiments. In addition, the concentrations of microbial metabolites, i.e., soluble microbial products (SMP) and extracellular polymeric substances (EPS) from activated sludge increased as nitrogen loading rate increased, both showing quadratic equation correlations with viscosity of the mixed liquid in the step-fed SMSBR (both R 2 > 0.90). EPS content was higher than SMP content, while protein (PN) was detected as the main component in both SMP and EPS. EPS PN was found to be well correlated with transmembrane pressure, membrane flux and the total membrane fouling resistance. Furthermore, the three-dimensional excitation-emission matrix fluorescence spectroscopy results suggested the tryptophan-like protein as one of the main contributors to the membrane fouling. Overall, this study showed that the step-fed SMSBR could be used to treat swine digestion slurry at nitrogen loading rate of 0.052 g NH 4 + -N (gVSS·d) -1 , and the control strategy of membrane fouling should be developed based on reducing the tryptophan-like PN in EPS.

  2. Evaluation of hygiene practices in catering premises at large-scale events in the UK: identifying risks for the Olympics 2012.

    Science.gov (United States)

    Willis, C; Elviss, N; Aird, H; Fenelon, D; McLauchlin, J

    2012-08-01

    To investigate hygiene practices of caterers at large events in order to: support the production of guidance on catering at such events; to compare hygiene standards at weekends with other times in the week; and to learn lessons in preparation for the London Olympics in 2012. UK-wide study of caterers at large events, including questionnaires on hygiene procedures and microbiological examination of food, water and environmental samples. In total, 1364 samples of food, water, surface swabs and cloths were collected at 139 events, by local authority sampling officers, and transported to laboratories for microbiological analysis. Eight percent of food samples were of an unsatisfactory quality, and a further 2% contained potentially hazardous levels of Bacillus spp. A significantly higher proportion of unsatisfactory food samples were taken from vendors without adequate food safety procedures in place. Fifty-two percent of water samples, 38% of swabs and 71% of cloths were also unsatisfactory. The majority of samples (57%) were collected on Saturdays, Sundays or bank holidays. Environmental swab results were significantly poorer at weekends compared with other days of the week. This study reinforces the fact that food hygiene is a continuing cause for concern in mobile vendors, and indicates a need for an ongoing programme of training and monitoring of caterers in preparation for the London Olympics. Copyright © 2012 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  3. Structure of proton-proton events at high center-of-mass energy with an identified particle of large transverse momentum

    International Nuclear Information System (INIS)

    Hanke, P.

    1977-01-01

    At the CERN-ISR events of pp-collisions, in which particles of large transverse momentum psub(T) are produced, were studied at √S = 52 GeV center-of-mass energy, using the 'Split-Field'-magnetspectrometer. The lorentz-invariant production cross-section of positive particles with high psub(T) was measured in the fragmentation region (average* approximately 20 0 ). In the same kinematical region the pion-fraction of produced particles for both charges was determined. In these events the effect of 'strangeness'-conservation on the dynamics of additionally produced particles was investigated. The comparison of events with negative pions and events with heavier particles - mainly kaons - at high psub(T) indicates, that the compensation of transverse momentum does not depend on the 'strangeness' of the particle at high psub(T). The quantum-number conservation rather influences the particle-content from the hadronic rest inside longitudinal phase-space. This was shown by reconstruction of decay-vertices of neutral kaons. The results obtained can be interpreted by 'constituent'-models of the proton-structure. (orig.) [de

  4. Comparison of regeneration efficiency of strong base anion exchangers fouled by iron and humic acids

    Czech Academy of Sciences Publication Activity Database

    Kus, P.; Kunesova, K.; Šlouf, Miroslav

    2014-01-01

    Roč. 49, č. 15 (2014), s. 2352-2357 ISSN 0149-6395 Institutional support: RVO:61389013 Keywords : regeneration * iron * fouling Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.171, year: 2014

  5. Butenolide inhibits marine fouling by altering the primary metabolism of three target organisms

    KAUST Repository

    Zhang, Yifan; Zhang, Huoming; He, Lisheng; Liu, Changdong; Xü , Ying; Qian, Peiyuan

    2012-01-01

    Butenolide is a very promising antifouling compound that inhibits ship hull fouling by a variety of marine organisms, but its antifouling mechanism was previously unknown. Here we report the first study of butenolides molecular targets in three

  6. Irreversible membrane fouling abatement through pre-deposited layer of hierarchical porous carbons

    KAUST Repository

    Hamad, Juma; Dua, Rubal; Kurniasari, Novita; Kennedy, Maria Dolores; Wang, Peng; Amy, Gary L.

    2014-01-01

    In this work, dual-templated hierarchical porous carbons (HPCs), produced from a coupled ice-hard templating approach, are shown to be a highly effective solution to the commonly occurring problem of irreversible fouling of low-pressure membranes

  7. Seasonal variations in the fouling diatom community structure from a monsoon influenced tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Anil, A.C.

    Seasonal variations in the fouling diatom community from a monsoon influenced tropical estuary were investigated. The community composition did not differ significantly between stainless steel and polystyrene substrata due to dominance by Navicula...

  8. Fouling development in direct contact membrane distillation: Non-invasive monitoring and destructive analysis

    KAUST Repository

    Fortunato, Luca; Jang, Yongsun; Lee, Jung Gil; Jeong, Sanghyun; Lee, Sangho; Leiknes, TorOve; Ghaffour, NorEddine

    2017-01-01

    of organic compounds and salts. Liquid chromatography with organic carbon detection (LC-OCD) analysis revealed the abundance of biopolymer in the fouling layer formed at the initial phase. In the second phase, formation of carbonate crystals on the membrane

  9. Characterization of biofoulants illustrates different membrane fouling mechanisms for aerobic and anaerobic membrane bioreactors

    KAUST Repository

    Xiong, Yanghui; Harb, Moustapha; Hong, Pei-Ying

    2015-01-01

    efficiency, the fouling mechanisms were different. Molecular weight (MW) fingerprint profiles showed that a majority of fragments in anaerobic soluble microbial products (SMP) were retained by the membrane and some fragments were present in both SMP

  10. A note on the fouling hydroids from the offshore waters of Bombay

    Digital Repository Service at National Institute of Oceanography (India)

    Venugopalan, V.P.; Wagh, A.B.

    This short communication brings out the preliminary results of the studies on fouling hydroids from an offshore region of the Arabian sea. A total of ten species falling under four different families have been collected of these four species viz...

  11. Development of a Comprehensive Fouling Model for a Rotating Membrane Bioreactor System Treating Wastewater

    Directory of Open Access Journals (Sweden)

    Parneet Paul

    2015-01-01

    Full Text Available Membrane bioreactors (MBRs are now main stream wastewater treatment technologies. In recent times, novel pressure driven rotating membrane disc modules have been specially developed that induce high shear on the membrane surface, thereby reducing fouling. Previous research has produced dead-end filtration fouling model which combines all three classical mechanisms that was later used by another researcher as a starting point for a greatly refined model of a cross flow side-stream MBR that incorporated both hydrodynamics and soluble microbial products’ (SMP effects. In this study, a comprehensive fouling model was created based on this earlier work that incorporated all three classical fouling mechanisms for a rotating MBR system. It was tested and validated for best fit using appropriate data sets. The initial model fit appeared good for all simulations, although it still needs to be calibrated using further appropriate data sets.

  12. Comparison and analysis of membrane fouling between flocculent sludge membrane bioreactor and granular sludge membrane bioreactor.

    Directory of Open Access Journals (Sweden)

    Wang Jing-Feng

    Full Text Available The goal of this study is to investigate the effect of inoculating granules on reducing membrane fouling. In order to evaluate the differences in performance between flocculent sludge and aerobic granular sludge in membrane reactors (MBRs, two reactors were run in parallel and various parameters related to membrane fouling were measured. The results indicated that specific resistance to the fouling layer was five times greater than that of mixed liquor sludge in the granular MBR. The floc sludge more easily formed a compact layer on the membrane surface, and increased membrane resistance. Specifically, the floc sludge had a higher moisture content, extracellular polymeric substances concentration, and negative surface charge. In contrast, aerobic granules could improve structural integrity and strength, which contributed to the preferable permeate performance. Therefore, inoculating aerobic granules in a MBR presents an effective method of reducing the membrane fouling associated with floc sludge the perspective of from the morphological characteristics of microbial aggregates.

  13. Application of Nano PAC on Mitigating Membrane Fouling by Surface Properties Optimization

    Directory of Open Access Journals (Sweden)

    Mi Hairong

    2016-01-01

    Full Text Available Membrane material has been widely accepted owing to the ability in water treatment, but the membrane fouling problem in using process is seriously restricted the promotion of membrane technology. So in this research nano PAC flocculant is added into the raw water to reach the goals of strengthening treatment efficiency and mitigating membrane fouling. According to the TMP change, it results that the PAC dosage of 45mg/L can realize the purpose to mitigate membrane fouling best. Compared with MBR, the MCBR is 16 days tardiness at the change of TMP, 1/3 gel layer filtration resistance less and 3.5% C element content fewer. The sum of C, O and N elements content, in addition, in the gel layer pollutants is more than 95%. That means membrane pollution is mainly caused by organic matter and nano PAC has the effect on surface properties optimization and membrane fouling mitigating.

  14. Fouling diatom community with reference to substratum variability in tropical marine environment

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Desai, D.V.; Khandeparker, L.; Anil, A.C.; Wagh, A.B.

    form encountered. The paper deals with the qualitative and quantitative aspects of diatom colonization, their community structure, and correlation between the prevailing diatom population in the environment and that in the fouling community...

  15. The problem of fouling in submerged membrane bioreactors - Model validation and experimental evidence

    Science.gov (United States)

    Tsibranska, Irene; Vlaev, Serafim; Tylkowski, Bartosz

    2018-01-01

    Integrating biological treatment with membrane separation has found a broad area of applications and industrial attention. Submerged membrane bioreactors (SMBRs), based on membrane modules immersed in the bioreactor, or side stream ones connected in recycle have been employed in different biotechnological processes for separation of thermally unstable products. Fouling is one of the most important challenges in the integrated SMBRs. A number of works are devoted to fouling analysis and its treatment, especially exploring the opportunity for enhanced fouling control in SMBRs. The main goal of the review is to provide a comprehensive yet concise overview of modeling the fouling in SMBRs in view of the problematics of model validation, either by real system measurements at different scales or by analysis of the obtained theoretical results. The review is focused on the current state of research applying computational fluid dynamics (CFD) modeling techniques.

  16. Marine bacterial transparent exopolymer particles (TEP) and TEP precursors: Characterization and RO fouling potential

    KAUST Repository

    Li, Sheng; Winters, Harvey; Jeong, Sanghyun; Emwas, Abdul-Hamid M.; Vigneswaran, Saravanamuthu; Amy, Gary L.

    2015-01-01

    This paper investigated the characteristics and membrane fouling potential of bacterial transparent exopolymer particles (TEP)/TEP precursors released from two marine bacteria, Pseudidiomarina homiensis (P. homiensis) and Pseudoalteromonas atlantica

  17. Design of shell-and-tube heat exchangers when the fouling depends on local temperature and velocity

    Energy Technology Data Exchange (ETDEWEB)

    Butterworth, D. [HTFS, Hyprotech, Didcot (United Kingdom)

    2002-07-01

    Shell-and-tube heat exchangers are normally designed on the basis of a uniform and constant fouling resistance that is specified in advance by the exchanger user. The design process is then one of determining the best exchanger that will achieve the thermal duty within the specified pressure drop constraints. It has been shown in previous papers [Designing shell-and-tube heat exchangers with velocity-dependant fouling, 34th US national Heat Transfer Conference, 20-22 August 2000, Pittsburg, PA; Designing shell-and-tube heat exchangers with velocity-dependant fouling, 2nd Int. Conf. on Petroleum and Gas Phase Behavior and Fouling, 27-31 August 2000, Copenhagen] that this approach can be extended to the design of exchangers where the design fouling resistance depends on velocity. The current paper briefly reviews the main findings of the previous papers and goes on to treat the case where the fouling depends also on the local temperatures. The Ebert-Panchal [Analysis of Exxon crude-oil, slip-stream coking data, Engineering Foundation Conference on Fouling Mitigation of Heat Exchangers, 18-23 June 1995, California] form of fouling rate equation is used to evaluate this fouling dependence. When allowing for temperature effects, it becomes difficult to divorce the design from the way the exchanger will be operated up to the point when the design fouling is achieved. However, rational ways of separating the design from the operation are proposed. (author)

  18. Morphometric and molecular identification of individual barnacle cyprids from wild plankton: an approach to detecting fouling and invasive barnacle species.

    Science.gov (United States)

    Chen, Hsi-Nien; Høeg, Jens T; Chan, Benny K K

    2013-01-01

    The present study used DNA barcodes to identify individual cyprids to species. This enables accurate quantification of larvae of potential fouling species in the plankton. In addition, it explains the settlement patterns of barnacles and serves as an early warning system of unwanted immigrant species. Sequences from a total of 540 individual cypris larvae from Taiwanese waters formed 36 monophyletic clades (species) in a phylogenetic tree. Of these clades, 26 were identified to species, but 10 unknown monophyletic clades represented non-native species. Cyprids of the invasive barnacle, Megabalanus cocopoma, were identified. Multivariate analysis of antennular morphometric characters revealed three significant clusters in a nMDS plot, viz. a bell-shaped attachment organ (most species), a shoe-shaped attachment organ (some species), and a spear-shaped attachment organ (coral barnacles only). These differences in attachment organ structure indicate that antennular structures interact directly with the diverse substrata involved in cirripede settlement.

  19. Hydrophilic, bactericidal nanoheater-enabled reverse osmosis membranes to improve fouling resistance.

    Science.gov (United States)

    Ray, Jessica R; Tadepalli, Sirimuvva; Nergiz, Saide Z; Liu, Keng-Ku; You, Le; Tang, Yinjie; Singamaneni, Srikanth; Jun, Young-Shin

    2015-06-03

    Polyamide (PA) semipermeable membranes typically used for reverse osmosis water treatment processes are prone to fouling, which reduces the amount and quality of water produced. By synergistically coupling the photothermal and bactericidal properties of graphene oxide (GO) nanosheets, gold nanostars (AuNS), and hydrophilic polyethylene glycol (PEG) on PA reverse osmosis membrane surfaces, we have dramatically improved fouling resistance of these membranes. Batch fouling experiments from three classes of fouling are presented: mineral scaling (CaCO3 and CaSO4), organic fouling (humic acid), and biofouling (Escherichia coli). Systematic analyses and a variety of complementary techniques were used to elucidate fouling resistance mechanisms from each layer of modification on the membrane surface. Both mineral scaling and organic fouling were significantly reduced in PA-GO-AuNS-PEG membranes compared to other membranes. The PA-GO-AuNS-PEG membrane was also effective in killing all near-surface bacteria compared to PA membranes. In the PA-GO-AuNS-PEG membrane, the GO nanosheets act as templates for in situ AuNS growth, which then facilitated localized heating upon irradiation by an 808 nm laser inactivating bacteria on the membrane surface. Furthermore, AuNS in the membrane assisted PEG in preventing mineral scaling on the membrane surface. In flow-through flux and foulant rejection tests, PA-GO-AuNS-PEG membranes performed better than PA membranes in the presence of CaSO4 and humic acid model foulants. Therefore, the newly suggested membrane surface modifications will not only reduce fouling from RO feeds, but can improve overall membrane performance. Our innovative membrane design reported in this study can significantly extend the lifetime and water treatment efficacy of reverse osmosis membranes to alleviate escalating global water shortage from rising energy demands.

  20. Techno-Economic Analysis of Gas Turbine Compressor Washing to Combat Fouling

    OpenAIRE

    Abass, Kabir Oliade

    2015-01-01

    Among the major deterioration problems a gas turbine encountered while in operation is compressor blade fouling. This is the accumulation and adhesion of dirt and sediment on the compressor blade which contributes between 70 to 85% of gas turbine performance loss. Fouling reduces turbine air mass flow capacity, compressor pressure ratio and overall gas turbine efficiency. In most cases, its effect does not manifest immediately in gas turbine power output and efficiency since they are not meas...

  1. Influence of twisted tape turbulence promoter on fouling reduction in microfiltration of milk proteins

    Directory of Open Access Journals (Sweden)

    Popović Svetlana S.

    2011-01-01

    Full Text Available Membrane filtration has become one of the major technologies in the food industry. It is widely applied in the dairy industry, and it is mostly used for the concentration and fractionation of milk proteins and for the whey processing. Of all pressure driven membrane processes, ultrafiltration is the most widely used. The major disadvantage of pressure driven membrane processes is severe fouling of membrane during filtration particularly when the fluids containing proteins are processed. Fouling with proteins is complex phenomenon because it occurs at the membrane surface as well as in the pores of membrane, and depends on the operating conditions and on the interactions of proteins and membrane material. In order to reduce fouling of the membrane different techniques have been developed, and one of them relies on the changing of the hydrodynamic conditions in the membrane or module. In this study, influence of twisted tape turbulence promoters on the fouling reduction in cross-flow microfiltration of skim milk was investigated. Twisted tapes with tree characteristic ratios of helix element length to the tape diameter (aspect ratio were studied. It was shown that twisted tapes with different aspect ratios reduce fouling of membrane by a factor of three or more. The presence of twisted tape induces changes in the flow patterns from straight to helicoidally thus producing turbulence flow at the lower cross-flow rates. Turbulence intensification prevents accumulation of proteins at membrane surface enabling reduction in reversible fouling what results in the reduction of overall membrane fouling. The best performance was achieved using a twisted tape with the lowest aspect ratio of 1.0. This promoter reduces fouling seven times at low transmembrane pressure and low cross-flow velocity. The twisted tape with aspect ratio 1.0 induces the most intensive turbulence, the longest helicoidal flow path, and appearance of vortices near the membrane surfaces

  2. Effect of IX dosing on polypropylene and PVDF membrane fouling control

    KAUST Repository

    Myat, Darli Theint

    2013-07-01

    The performance of ion exchange (IX) resin for organics removal from wastewater was assessed using advanced characterisation techniques for varying doses of IX. Organic characterisation using liquid chromatography with a photodiode array (PDA) and fluorescence spectroscopy (Method A), and UV254, organic carbon and organic nitrogen detectors (Method B), was undertaken on wastewater before and after magnetic IX treatment. Results showed partial removal of the biopolymer fraction at high IX doses. With increasing concentration of IX, evidence for nitrogen-containing compounds such as proteins and amino acids disappeared from the LC-OND chromatogram, complementary to the fluorescence response. A greater fluorescence response of tryptophan-like proteins (278nm/343nm) for low IX concentrations was consistent with aggregation of tryptophan-like compounds into larger aggregates, either by self-aggregation or with polysaccharides. Recycling of IX resin through multiple adsorption steps without regeneration maintained the high level of humics removal but there was no continued removal of biopolymer. Subsequent membrane filtration of the IX treated waters resulted in complex fouling trends. Filtration tests with either polypropylene (PP) or polyvinylidene fluoride (PVDF) membranes showed higher rates of initial fouling following treatment with high IX doses (10mL/L) compared to filtration of untreated water, while treatment with lower IX doses resulted in decreased fouling rates relative to the untreated water. However, at longer filtration times the rate of fouling of IX treated waters was lower than untreated water and the relative fouling rates corresponded to the amount of biopolymer material in the feed. It was proposed that the mode of fouling changed from pore constriction during the initial filtration period to filter cake build up at longer filtration times. The organic composition strongly influenced the rate of fouling during the initial filtration period due to

  3. A novel assessment of the traction forces upon settlement of two typical marine fouling invertebrates using PDMS micropost arrays

    Directory of Open Access Journals (Sweden)

    Kang Xiao

    2018-01-01

    Full Text Available Marine biofouling poses a severe threat to maritime and aquaculture industries. To prevent the attachment of marine biofouling organisms on man-made structures, countless cost and effort was spent annually. In particular, most attention has been paid on the development of efficient and environmentally friendly fouling-resistant coatings, as well as larval settlement mechanism of several major biofouling invertebrates. In this study, polydimethylsiloxane (PDMS micropost arrays were utilized as the settlement substrata and opposite tractions were identified during early settlement of the barnacle Amphibalanus amphitrite and the bryozoan Bugula neritina. The settling A. amphitrite pushed the periphery microposts with an average traction force of 376.2 nN, while settling B. neritina pulled the periphery microposts with an average traction force of 205.9 nN. These micropost displacements are consistent with the body expansion of A. amphitrite during early post-settlement metamorphosis stage and elevation of wall epithelium of B. neritina during early pre-ancestrula stage, respectively. As such, the usage of micropost array may supplement the traditional histological approach to indicate the early settlement stages or even the initiation of larval settlement of marine fouling organisms, and could finally aid in the development of automatic monitoring platform for the real-time analysis on this complex biological process.

  4. Assessing the Robustness of Thermoeconomic Diagnosis of Fouled Evaporators: Sensitivity Analysis of the Exergetic Performance of Direct Expansion Coils

    Directory of Open Access Journals (Sweden)

    Antonio Piacentino

    2016-03-01

    Full Text Available Thermoeconomic diagnosis of refrigeration systems is a pioneering approach to the diagnosis of malfunctions, which has been recently proven to achieve good performances for the detection of specific faults. Being an exergy-based diagnostic technique, its performance is influenced by the trends of exergy functions in the “design” and “abnormal” conditions. In this paper the sensitivity of performance of thermoeconomic diagnosis in detecting a fouled direct expansion coil and quantifying the additional consumption it induces is investigated; this fault is critical due to the simultaneous air cooling and dehumidification occurring in the coil, that induce variations in both the chemical and thermal fractions of air exergy. The examined parameters are the temperature and humidity of inlet air, the humidity of reference state and the sensible/latent heat ratio (varied by considering different coil depths. The exergy analysis reveals that due to the more intense dehumidification occurring in presence of fouling, the exergy efficiency of the evaporator coil eventually increases. Once the diagnostic technique is based only on the thermal fraction of air exergy, the results suggest that the performance of the technique increases when inlet air has a lower absolute humidity, as evident from the “optimal performance” regions identified on a psychrometric chart.

  5. In-situ non-invasive device for early detection of fouling in aquatic systems

    KAUST Repository

    Fortunato, Luca

    2017-01-05

    An in-situ, non-destructive sensor device, system and method are provided to detect or assess fouling at a very early stage of development. They can be used to detect or assess fouling on a surface of an aquatic system. They can be used to obtain a depth profile of the fouling. Data concerning the depth profile can be extracted and used to assess the fouling on the surface, in one or more aspects, the method can include providing an optical tomography spectrometer; optically positioning the optical tomography spectrometer in association with a surface of an area to be assessed for fouling in an aqueous system; irradiating the surface; acquiring, from irradiating the surface, a plurality of signals as a function of a distance from the surface at different times; extracting data from the signals as a function of the distance to obtain a depth profile of the surface at the different times; and determining a change in the depth profile between the different times to assess fouling on the surface.

  6. Influence of the adhesion force crystal/heat exchanger surface on fouling mitigation

    International Nuclear Information System (INIS)

    Forster, M.; Augustin, W.; Bohnet, M.

    1999-01-01

    The accumulation of unwanted crystalline deposits (fouling) reduces the efficiency of heat exchangers considerably. In order to decrease the cost of fouling two strategies have been developed. The first fouling mitigation strategy is based on the modification of energy-and-geometry-related characteristics of the heat transfer surface to realize an increased duration of the induction period. By means of a drop-shape-analysis measurement device the interaction at the interface crystal/heat transfer surface is determined. The deployment of the fracture energy model and the interfacial defect model relates wetting characteristics to the adhesion phenomenon. Hence, a first estimation of the optimal choice of surface material is realized. Furthermore, the influence of surface topography on interfacial interactions has been analyzed. The second fouling mitigation strategy is based on the adjustment of the hydrodynamic flow conditions using a pulsation technique. Here, single strokes of higher velocity are superimposed on the stationary flow. These strokes shift the equilibrium of forces to an improved removal process. Fouling experiments have proved that pulsation is a powerful tool to mitigate the built-up of fouling layers on heat transfer surfaces. (author)

  7. Colloidal Fouling of Nanofiltration Membranes: Development of a Standard Operating Procedure

    Directory of Open Access Journals (Sweden)

    Md Abdullaha Al Mamun

    2017-01-01

    Full Text Available Fouling of nanofiltration (NF membranes is the most significant obstacle to the development of a sustainable and energy-efficient NF process. Colloidal fouling and performance decline in NF processes is complex due to the combination of cake formation and salt concentration polarization effects, which are influenced by the properties of the colloids and the membrane, the operating conditions of the test, and the solution chemistry. Although numerous studies have been conducted to investigate the influence of these parameters on the performance of the NF process, the importance of membrane preconditioning (e.g., compaction and equilibrating with salt water, as well as the determination of key parameters (e.g., critical flux and trans-membrane osmotic pressure before the fouling experiment have not been reported in detail. The aim of this paper is to present a standard experimental and data analysis protocol for NF colloidal fouling experiments. The developed methodology covers preparation and characterization of water samples and colloidal particles, pre-test membrane compaction and critical flux determination, measurement of experimental data during the fouling test, and the analysis of that data to determine the relative importance of various fouling mechanisms. The standard protocol is illustrated with data from a series of flat sheet, bench-scale experiments.

  8. A global fouling factor methodology for analyzing steam generator thermal performance degradation

    International Nuclear Information System (INIS)

    Kreider, M.A.; White, G.A.; Varrin, R.D. Jr.

    1998-06-01

    Over the past few years, steam generator (SG) thermal performance degradation has led to decreased plant efficiency and power output at numerous PWR nuclear power plants with recirculating-type SGs. The authors have developed and implemented methodologies for quantitatively evaluating the various sources of SG performance degradation, both internal and external to the SG pressure boundary. These methodologies include computation of the global fouling factor history, evaluation of secondary deposit thermal resistance using deposit characterization data, and consideration of pressure loss causes unrelated to the tube bundle, such as hot-leg temperature streaming and SG moisture separator fouling. In order to evaluate the utility of the global fouling factor methodology, the authors performed case studies for a number of PWR SG designs. Key results from two of these studies are presented here. In tandem with the fouling-factor analyses, a study evaluated for each plant the potential causes of pressure loss. The combined results of the global fouling factor calculations and the pressure-loss evaluations demonstrated two key points: (1) that the available thermal margin against fouling, which can vary substantially from plant to plant, has an important bearing on whether a given plant exhibits losses in electrical generating capacity, and (2) that a wide variety of causes can result in SG thermal performance degradation

  9. Mechanistic modeling of the loss of protein sieving due to internal and external fouling of microfilters.

    Science.gov (United States)

    Bolton, Glen R; Apostolidis, Alex J

    2017-09-01

    Fed-batch and perfusion cell culture processes used to produce therapeutic proteins can use microfilters for product harvest. In this study, new explicit mathematical models of sieving loss due to internal membrane fouling, external membrane fouling, or a combination of the two were generated. The models accounted for membrane and cake structures and hindered solute transport. Internal membrane fouling was assumed to occur due to the accumulation of foulant on either membrane pore walls (pore-retention model) or membrane fibers (fiber-retention model). External cake fouling was assumed to occur either by the growth of a single incompressible cake layer (cake-growth) or by the accumulation of a number of independent cake layers (cake-series). The pore-retention model was combined with either the cake-series or cake-growth models to obtain models that describe internal and external fouling occurring either simultaneously or sequentially. The models were tested using well-documented sieving decline data available in the literature. The sequential pore-retention followed by cake-growth model provided a good fit of sieving decline data during beer microfiltration. The cake-series and cake-growth models provided good fits of sieving decline data during the microfiltration of a perfusion cell culture. The new models provide insights into the mechanisms of fouling that result in the loss of product sieving. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1323-1333, 2017. © 2017 American Institute of Chemical Engineers.

  10. Detection and location of fouling on photovoltaic panels using a drone-mounted infrared thermography system

    Science.gov (United States)

    Zhang, Peng; Zhang, Lifu; Wu, Taixia; Zhang, Hongming; Sun, Xuejian

    2017-01-01

    Due to weathering and external forces, solar panels are subject to fouling and defects after a certain amount of time in service. These fouling and defects have direct adverse consequences such as low-power efficiency. Because solar power plants usually have large-scale photovoltaic (PV) panels, fast detection and location of fouling and defects across large PV areas are imperative. A drone-mounted infrared thermography system was designed and developed, and its ability to detect rapid fouling on large-scale PV panel systems was investigated. The infrared images were preprocessed using the K neighbor mean filter, and the single PV module on each image was recognized and extracted. Combining the local and global detection method, suspicious sites were located precisely. The results showed the flexible drone-mounted infrared thermography system to have a strong ability to detect the presence and determine the position of PV fouling. Drone-mounted infrared thermography also has good technical feasibility and practical value in the detection of PV fouling detection.

  11. Microbial community structure characteristics associated membrane fouling in A/O-MBR system.

    Science.gov (United States)

    Gao, Da-Wen; Wen, Zhi-Dan; Li, Bao; Liang, Hong

    2014-02-01

    The study demonstrated the potential relationship between microbial community structure and membrane fouling in an anoxic-oxic membrane bioreactor (A/O-MBR). The results showed that the microbial community structure in biocake was different with aerobic mixture, and the dominant populations were out of sync during the fouling process. Based on microbial community structure and metabolites analysis, the results showed that the succession of microbial community might be the leading factor to the variation of metabolites, and it might be the primary cause of membrane fouling. The rise of Shannon diversity index (H) of the microbial community in A/O-MBR went with the gradually serious membrane fouling. Pareto-Lorenz curve was used to describe the evenness of microbial distribution in A/O-MBR, and the result indicated when community evenness was low, the membrane fouling took place smoothly or slightly, otherwise, high evenness of microbial community would lead to more seriously membrane fouling. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Effect of Biological Contact Filters (BCFs on Membrane Fouling in Drinking Water Treatment Systems

    Directory of Open Access Journals (Sweden)

    Susumu Hasegawa

    2017-12-01

    Full Text Available Membrane fouling is a serious problem in drinking water treatment systems. Biological contact filters (BCFs are often used as a pretreatment to remove ammonia, dissolved organic matter (DOM, and metal ions such as iron and manganese. In this study, the effect of BCF as a pretreatment for membrane fouling was evaluated using a laboratory-scale mini module consisting of a mini BCF column and a mini MF column. Initially, it was confirmed that the main foulant was a biopolymer (at low concentration in the raw water. Subsequently, the biopolymer concentrations in the BCF influent and effluent were measured with the excitation emission matrix (EEM fluorescence spectroscopy and the liquid chromatograph organic carbon detector (LC-OCD. The fouling potential of the BCF influent and effluent was also measured to evaluate MF membrane fouling rate. The results demonstrate that application of the BCF reduced the biopolymer concentration of the effluent and reduced membrane fouling. The effect of BCF was also established in an actual drinking water treatment plant. It was found that optimizing the contact time of raw water with the BCF was crucial to reduce membrane fouling.

  13. Exercise electrocardiogram in middle-aged and older leisure time sportsmen: 100 exercise tests would be enough to identify one silent myocardial ischemia at risk for cardiac event.

    Science.gov (United States)

    Hupin, David; Edouard, Pascal; Oriol, Mathieu; Laukkanen, Jari; Abraham, Pierre; Doutreleau, Stéphane; Guy, Jean-Michel; Carré, François; Barthélémy, Jean-Claude; Roche, Frédéric; Chatard, Jean-Claude

    2018-04-15

    The importance of exercise electrocardiogram (ECG) has been controversial in the prevention of cardiac events among sportsmen. The aim of this study was to determine the frequency of silent myocardial ischemia (SMI) from an exercise ECG and its relationship with induced coronary angiographic assessment and potentially preventable cardiac events. This prospective cohort study included leisure time asymptomatic sportsmen over 35years old, referred from 2011 to 2014 in the Sports Medicine Unit of the University Hospital of Saint-Etienne. Of the cohort of 1500 sportsmen (1205 men; mean age 50.7±9.4years; physical activity level 32.8±26.8MET-h/week), 951 (63%) had at least one cardiovascular disease (CVD) risk factor. Family history, medical examination and standard resting 12-lead were collected. A total of 163 exercise ECGs (10.9%) were defined as positive, most of them due to SMI (n=129, 8.6%). SMI was an indication for coronary angiography in 23 cases, leading to 17 documented SMIs (1.1%), including 11 significant stenoses requiring revascularization. In multivariate logistic regression analysis, a high risk of CVD (OR=2.65 [CI 95%: 1.33-5.27], p=0.005) and an age >50years (OR=2.71 [CI 95%: 1.65-4.44], p<0.0001) were independently associated with confirmed SMI. The association of positive exercise ECG with significant coronary stenosis was stronger among sportsmen with CVD risk factors and older than 50years. Screening by exercise ECG can lower the risk of cardiac events in middle-aged and older sportsmen. One hundred tests would be enough to detect one silent myocardial ischemia at risk for cardiac event. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Polymeric dispersants for control of steam generator fouling

    International Nuclear Information System (INIS)

    Balakrishnan, P.V.; Klimas, S.J.; Lepine, L.; Turner, C.W.

    1999-05-01

    Fouling of steam generators by corrosion products from the feedtrain leads to loss of heat-transfer efficiency, disturbances in thermalhydraulics, and potential corrosion problems resulting from the development of sites for localized accumulation of aggressive chemicals. This report summarizes studies of the use of polymeric dispersants for the control of fouling, which were conducted at the Chalk River Laboratories. High-temperature settling studies on magnetite suspensions were performed to screen available generic dispersants, and the dispersants were ranked in terms of their dispersion efficiency; polyacrylic acid (PAA) and the phosphonate, HEDP, were ranked as the most efficient. Polyacrylic acid was considered more suitable than HEDP for nuclear steam generators, and more emphasis was given to the former in these studies. The dispersants had no effect on the particle deposition rates under single-phase forced-convective flow, but did reduce the deposition rates under flow-boiling conditions. The extent to which the deposition rates were reduced increased in proportion to the dispersant concentration. Preliminary corrosion tests indicated that pitting or general corrosion of steam generator tube materials in the presence of PAA was negligible. Corrosion of carbon steel, although higher in a magnetite-packed crevice under heat flux than in bulk water, was lower in the presence of PAA than in its absence. Some impurities (e.g., sulphate, sodium) were observed in commercially available PAA products at small, though significant concentrations, making these products unacceptable for use in nuclear plants. However, the PAA could be purified by ion exchange. Preliminary experiments, to assess the thermal stability of PAA at steam generator operating temperature, showed the polymer to break down in deaerated solutions and under argon cover to give hydrogen and carbon dioxide as the two major products in the gas phase and variable concentrations of acetate and formate

  15. SODIUM ALUMINOSILICATE FOULING AND CLEANING OF DECONTAMINATED SALT SOLUTION COALESCERS

    International Nuclear Information System (INIS)

    Poirier, M.; Thomas Peters, T.; Fernando Fondeur, F.; Samuel Fink, S.

    2008-01-01

    During initial non-radioactive operations at the Modular Caustic Side Solvent Extraction Unit (MCU), the pressure drop across the decontaminated salt solution coalescer reached ∼10 psi while processing ∼1250 gallons of salt solution, indicating possible fouling or plugging of the coalescer. An analysis of the feed solution and the 'plugged coalescer' concluded that the plugging was due to sodium aluminosilicate solids. MCU personnel requested Savannah River National Laboratory (SRNL) to investigate the formation of the sodium aluminosilicate solids (NAS) and the impact of the solids on the decontaminated salt solution coalescer. Researchers performed developmental testing of the cleaning protocols with a bench-scale coalescer container 1-inch long segments of a new coalescer element fouled using simulant solution. In addition, the authors obtained a 'plugged' Decontaminated Salt Solution coalescer from non-radioactive testing in the MCU and cleaned it according to the proposed cleaning procedure. Conclusions from this testing include the following: (1) Testing with the bench-scale coalescer showed an increase in pressure drop from solid particles, but the increase was not as large as observed at MCU. (2) Cleaning the bench-scale coalescer with nitric acid reduced the pressure drop and removed a large amount of solid particles (11 g of bayerite if all aluminum is present in that form or 23 g of sodium aluminosilicate if all silicon is present in that form). (3) Based on analysis of the cleaning solutions from bench-scale test, the 'dirt capacity' of a 40 inch coalescer for the NAS solids tested is calculated as 450-950 grams. (4) Cleaning the full-scale coalescer with nitric acid reduced the pressure drop and removed a large amount of solid particles (60 g of aluminum and 5 g of silicon). (5) Piping holdup in the full-scale coalescer system caused the pH to differ from the target value. Comparable hold-up in the facility could lead to less effective cleaning and

  16. Anti-fouling properties of Fab’ fragments immobilized on silane-based adlayers

    International Nuclear Information System (INIS)

    Crivianu-Gaita, Victor; Romaschin, Alexander; Thompson, Michael

    2015-01-01

    Highlights: • Simple and mixed adlayers formed with Fab’ linker and/or spacers. • Binding of Fab’ fragments through TUBTS linker resulted in oriented immobilization. • Immobilized Fab’ fragments have inherent anti-fouling character. • Up to 80% fouling reduction when Fab’ fragments introduced to surfaces. • Used the minimally fouling surfaces to detect a cancer biomarker (PTHrP) in serum. - Graphical abstract: Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a difficult task. The last decade has seen an increase in the use of immobilized antigen-binding antibody fragments (Fab’) in biosensors. One Fab’ linker compound S-(11-trichlorosilyl-undecanyl)-benzothiosulfonate (TUBTS) and three spacers were used to create the silane-based adlayers. The ultra-high frequency electromagnetic piezoelectric acoustic sensor (EMPAS) was used to gauge the fouling properties of the various surfaces using bovine serum albumin (BSA), goat IgG, and mouse serum. X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM) were employed to characterize the surfaces. It was discovered that immobilized oriented Fab’ fragments reduced the fouling levels of surfaces up to 80% compared to the surfaces without fragments. An explanation for this phenomenon is that the antibody fragments increase the hydration of the surfaces and aid in the formation of an anti-fouling water barrier. The anti-fouling effect of the Fab’ fragments is at its maximum when there is an even distribution of fragments across the surfaces. Finally, using Fab’-covered surfaces, a cancer biomarker was detected from serum, showing the applicability of this work to the field of biodetection. - Abstract: Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a

  17. Anti-fouling properties of Fab’ fragments immobilized on silane-based adlayers

    Energy Technology Data Exchange (ETDEWEB)

    Crivianu-Gaita, Victor [Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6 (Canada); Romaschin, Alexander [Clinical Biochemistry, St. Michael' s Hospital, Toronto, ON M5B 1W8 (Canada); Thompson, Michael, E-mail: mikethom@chem.utoronto.ca [Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6 (Canada)

    2015-12-30

    Highlights: • Simple and mixed adlayers formed with Fab’ linker and/or spacers. • Binding of Fab’ fragments through TUBTS linker resulted in oriented immobilization. • Immobilized Fab’ fragments have inherent anti-fouling character. • Up to 80% fouling reduction when Fab’ fragments introduced to surfaces. • Used the minimally fouling surfaces to detect a cancer biomarker (PTHrP) in serum. - Graphical abstract: Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a difficult task. The last decade has seen an increase in the use of immobilized antigen-binding antibody fragments (Fab’) in biosensors. One Fab’ linker compound S-(11-trichlorosilyl-undecanyl)-benzothiosulfonate (TUBTS) and three spacers were used to create the silane-based adlayers. The ultra-high frequency electromagnetic piezoelectric acoustic sensor (EMPAS) was used to gauge the fouling properties of the various surfaces using bovine serum albumin (BSA), goat IgG, and mouse serum. X-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM) were employed to characterize the surfaces. It was discovered that immobilized oriented Fab’ fragments reduced the fouling levels of surfaces up to 80% compared to the surfaces without fragments. An explanation for this phenomenon is that the antibody fragments increase the hydration of the surfaces and aid in the formation of an anti-fouling water barrier. The anti-fouling effect of the Fab’ fragments is at its maximum when there is an even distribution of fragments across the surfaces. Finally, using Fab’-covered surfaces, a cancer biomarker was detected from serum, showing the applicability of this work to the field of biodetection. - Abstract: Biosensors require surfaces that are highly specific towards the target analyte and that are minimally fouling. However, surface tuning to minimize fouling is a

  18. Studies of identified hadrons in qq-bar events at LEPI, in W sup + W sup - and qq-bar events at LEPII and search for stable and long-lived heavy charged particles

    CERN Document Server

    Neufeld, N

    1999-01-01

    The use of RICH detectors allows the identification of charged pions, kaons and protons, covering the full momentum range 0.7qq-bar, Z sup 0->bb-bar and Z sup 0->uu-bar, dd-bar, ss-bar, selected from approx 1,400,000 Z sup 0 decays collected by DELPHI in 1994. This study has been extended to high-energy qq-bar events at LEPII. New heavy particles from 2 GeV/c sup 2 to the kinematic limit at LEPII have been searched using the RICH detectors.

  19. Source water quality shaping different fouling scenarios in a full-scale desalination plant at the Red Sea

    KAUST Repository

    Khan, Muhammad

    2013-02-01

    The complexity of Reverse Osmosis (RO) membrane fouling phenomenon has been widely studied and several factors influencing it have been reported by many researchers. This original study involves the investigation of two different fouling profiles produced at a seawater RO desalination plant installed on a floating mobile barge. The plant was moved along the coastline of the Red Sea in Saudi Arabia. The two locations where the barge was anchored showed different water quality. At the second location, two modules were harvested. One of the modules was pre-fouled by inorganics during plant operation at the previous site while the other was installed at the second site. Fouled membranes were subjected to a wide range of chemical and microbiological characterization procedures. Drastically different fouling patterns were observed in the two membranes which indicates the influence of source water quality on membrane surface modification and on fouling of RO membranes. © 2012 Elsevier Ltd.

  20. Measurement of the Jet Vertex Charge algorithm performance for identified $b$-jets in $t\\bar{t}$ events in $pp$ collisions with the ATLAS detector

    CERN Document Server

    The ATLAS collaboration

    2018-01-01

    The Jet Vertex Charge algorithm, developed recently within the ATLAS collaboration, discriminates between jets resulting from the hadronisation of a bottom quark or bottom antiquark. This note describes a measurement of the performance of the algorithm and the extraction of data-to-simulation scale factors, made using $b$-tagged jets in candidate single lepton $t\\bar{t}$ events. The data sample was collected by the ATLAS detector at the LHC using $pp$ collisions at $\\sqrt{s}$ = 13 TeV in 2015 and 2016 and corresponds to a total integrated luminosity of 36.1 fb$^{-1}$ . Overall, good agreement is found between data and the simulation.

  1. A global fouling factor methodology for analyzing steam generator thermal performance degradation

    International Nuclear Information System (INIS)

    Kreider, M.A.; White, G.A.; Varrin, R.D.

    1998-01-01

    Over the past few years, steam generator (SG) thermal performance degradation has led to decreased plant efficiency and power output at numerous PWR nuclear power plants with recirculating-type SGs. The authors have developed and implemented methodologies for quantitatively evaluating the various sources of SG performance degradation, both internal and external to the SG pressure boundary. These methodologies include computation of the global fouling factor history, evaluation of secondary deposit thermal resistance using deposit characterization data, and consideration of pressure loss causes unrelated to the tube bundle, such as hot-leg temperature streaming and SG moisture separator performance. In order to evaluate the utility of the global fouling factor methodology, the authors performed case studies for a number of PWR SG designs. Key results from two of these studies are presented here. Uncertainty analyses were performed to determine whether the calculated fouling factor for each plant represented significant fouling or whether uncertainty in key variables (e.g., steam pressure or feedwater flow rate) could be responsible for calculated fouling. The methodology was validated using two methods: by predicting the SG pressure following chemical cleaning at San Onofre 2 and also by performing a sensitivity study with the industry-standard thermal-hydraulics code ATHOS to investigate the effects of spatially varying tube scale distributions. This study indicated that the average scale thickness has a greater impact on fouling than the spatial distribution, showing that the assumption of uniform resistance inherent to the global fouling factor is reasonable. In tandem with the fouling-factor analyses, a study evaluated for each plant the potential causes of pressure loss. The combined results of the global fouling factor calculations and the pressure loss evaluations demonstrated two key points: 1) that the available thermal margin against fouling, which can

  2. Sedimentation and fouling of optical surfaces at the ANTARES site

    Science.gov (United States)

    ANTARES Collaboration; CAU CEFREM Collaboration; Amram, P.; Anghinolfi, M.; Anvar, S.; Ardellier-Desages, F. E.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Bailey, D.; Basa, S.; Battaglieri, M.; Bellotti, R.; Beltramelli, J.; Benhammou, Y.; Berthier, R.; Bertin, V.; Billault, M.; Blaes, R.; Bland, R. W.; Blondeau, F.; de Botton, N.; Boulesteix, J.; Brooks, C. B.; Brunner, J.; Cafagna, F.; Calzas, A.; Capone, A.; Caponetto, L.; Cârloganu, C.; Carmona, E.; Carr, J.; Cartwright, S. L.; Cecchini, S.; Ciacio, F.; Circella, M.; Compère, C.; Cooper, S.; Coyle, P.; Cuneo, S.; Danilov, M.; van Dantzig, R.; de Marzo, C.; Destelle, J.-J.; de Vita, R.; Dispau, G.; Druillole, F.; Engelen, J.; Feinstein, F.; Ferdi, C.; Festy, D.; Fopma, J.; Gallone, J.-M.; Giacomelli, G.; Goret, P.; Gournay, J.-F.; Hallewell, G.; Heijboer, A.; Hernández-Rey, J. J.; Hubbard, J. R.; Jaquet, M.; de Jong, M.; Karolak, M.; Keller, P.; Kooijman, P.; Kouchner, A.; Kudryavtsev, V. A.; Lafoux, H.; Lagier, P.; Lamare, P.; Languillat, J.-C.; Laubier, L.; Laugier, J.-P.; Leilde, B.; Le Provost, H.; Le van Suu, A.; Lo Nigro, L.; Lo Presti, D.; Loucatos, S.; Louis, F.; Lyashuk, V.; Magnier, P.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazeau, B.; Mazure, A.; McMillan, J. E.; Migneco, E.; Millot, C.; Mols, P.; Montanet, F.; Montaruli, T.; Moscoso, L.; Musumeci, M.; Nezri, E.; Nooren, G. J.; Oberski, J. E. J.; Olivetto, C.; Oppelt-Pohl, A.; Palanque-Delabrouille, N.; Papaleo, R.; Payre, P.; Perrin, P.; Petruccetti, M.; Petta, C.; Piattelli, P.; Poinsignon, J.; Potheau, R.; Queinec, Y.; Racca, C.; Raia, G.; Randazzo, N.; Rethore, F.; Riccobene, G.; Ricol, J.-S.; Ripani, M.; Roca-Blay, V.; Romeyer, A.; Rostovstev, A.; Russo, G. V.; Sacquin, Y.; Salusti, E.; Schuller, J.-P.; Schuster, W.; Soirat, J.-P.; Souvorova, O.; Spooner, N. J. C.; Spurio, M.; Stolarczyk, T.; Stubert, D.; Taiuti, M.; Tao, C.; Thompson, L. F.; Tilav, S.; Triay, R.; Usik, A.; Valdy, P.; Valente, V.; Varlamov, I.; Vaudaine, G.; Vernin, P.; Vladimirsky, E.; Vorobiev, M.; de Witt Huberts, P.; de Wolf, E.; Zakharov, V.; Zavatarelli, S.; Zornoza, Juan de Dios; Zún~Iga, J.; Aloïsi, J.-C.; Kerhervé, Ph.; Monaco, A.

    2003-05-01

    ANTARES is a project leading towards the construction and deployment of a neutrino telescope in the deep Mediterranean Sea. The telescope will use an array of photomultiplier tubes to detect the Cherenkov light emitted by muons resulting from the interaction with matter of high energy neutrinos. In the vicinity of the deployment site the ANTARES Collaboration has performed a series of in situ measurements to study the change in light transmission through glass surfaces during immersions of several months. The average loss of light transmission is estimated to be only ~2% at the equator of a glass sphere one year after deployment. It decreases with increasing zenith angle, and tends to saturate with time. The transmission loss, therefore, is expected to remain small for the several year lifetime of the ANTARES detector whose optical modules are oriented downwards. The measurements were complemented by the analysis of the 210Pb activity profile in sediment cores and the study of biofouling on glass plates. Despite a significant sedimentation rate at the site, in the 0.02-0.05 cmyr-1 range, the sediments adhere loosely to the glass surfaces and can be washed off by water currents. Further, fouling by deposits of light-absorbing particulates is only significant for surfaces facing upwards.

  3. Inducible defenses against herbivory and fouling in seaweeds

    Science.gov (United States)

    Pereira, Renato Crespo; Costa, Erica da Silva; Sudatti, Daniela Bueno; da Gama, Bernardo Antonio Perez

    2017-04-01

    Secondary metabolites play an important ecological role as a defense mechanism in seaweeds. Chemical defenses are well known to change in response to herbivory, but other driving factors, either biotic or abiotic, are often neglected. Epibiosis may not only reduce seaweed fitness, but also increase attractiveness to consumers, and thus defense production should also be triggered by epibionts. In this study, three Southwestern Atlantic seaweeds, Gracilaria cearensis, Pterocladiella capillacea (Rhodophyceae) and Codium decorticatum (Chlorophyceae) were investigated in laboratory bioassays designed to test whether the action of herbivory or simulated epibiosis influences chemical defenses. Crossed induction experiments were also performed in order to assess whether herbivore induction influences antifouling chemical defense, as well as whether epibiont induction would affect defense against herbivores. The effect of laboratory conditions on seaweeds in the absence of field stimuli was also investigated by comparing consumption of artificial food with extracts from acclimatized and non-acclimatized seaweeds (i.e., natural defense levels). Only the green seaweed C. decorticatum exhibited inducible antifouling defenses triggered by simulated epibiosis, but not by herbivores. In the other seaweeds there was no induction either by herbivory or simulated epibiosis. Acclimatization did not affect C. decorticatum defenses. However, non-acclimatized G. cearensis artificial foods were preferred over acclimatized ones, while extracts from acclimatized P. capillacea increased herbivore consumption, highlighting the need to acclimatize seaweeds before the main induction experiments. This is the first report of inducible defenses due to simulated fouling in seaweeds.

  4. Soil model systems used to assess fouling, soil adherence and surface cleanability in the laboratory: a review

    OpenAIRE

    Toure, Yetioman; Mabon, Nicolas; Sindic, Marianne

    2013-01-01

    Surface fouling is a chronic problem in processing industries. The hygienic state of surfaces is thus a critical parameter with respect to the performance of the production process and to the final quality of the product. For this reason, cleaning and disinfection are essential. The most important first step in implementing a fouling mitigation strategy through cleaning and disinfection is to understand the mechanisms of fouling. This allows ways to be found to reduce, even to eliminate fouli...

  5. Erroneous cardiac ECG-gated PET list-mode trigger events can be retrospectively identified and replaced by an offline reprocessing approach: first results in rodents

    International Nuclear Information System (INIS)

    Böning, Guido; Todica, Andrei; Vai, Alessandro; Lehner, Sebastian; Xiong, Guoming; Mille, Erik; Ilhan, Harun; Fougère, Christian la; Bartenstein, Peter; Hacker, Marcus

    2013-01-01

    The assessment of left ventricular function, wall motion and myocardial viability using electrocardiogram (ECG)-gated [ 18 F]-FDG positron emission tomography (PET) is widely accepted in human and in preclinical small animal studies. The nonterminal and noninvasive approach permits repeated in vivo evaluations of the same animal, facilitating the assessment of temporal changes in disease or therapy response. Although well established, gated small animal PET studies can contain erroneous gating information, which may yield to blurred images and false estimation of functional parameters. In this work, we present quantitative and visual quality control (QC) methods to evaluate the accuracy of trigger events in PET list-mode and physiological data. Left ventricular functional analysis is performed to quantify the effect of gating errors on the end-systolic and end-diastolic volumes, and on the ejection fraction (EF). We aim to recover the cardiac functional parameters by the application of the commonly established heart rate filter approach using fixed ranges based on a standardized population. In addition, we propose a fully reprocessing approach which retrospectively replaces the gating information of the PET list-mode file with appropriate list-mode decoding and encoding software. The signal of a simultaneously acquired ECG is processed using standard MATLAB vector functions, which can be individually adapted to reliably detect the R-peaks. Finally, the new trigger events are inserted into the PET list-mode file. A population of 30 mice with various health statuses was analyzed and standard cardiac parameters such as mean heart rate (119 ms ± 11.8 ms) and mean heart rate variability (1.7 ms ± 3.4 ms) derived. These standard parameter ranges were taken into account in the QC methods to select a group of nine optimal gated and a group of eight sub-optimal gated [ 18 F]-FDG PET scans of mice from our archive. From the list-mode files of the optimal gated group

  6. Organic fouling behavior of superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membranes functionalized with surface-tailored nanoparticles: Implications for organic fouling in membrane bioreactors

    KAUST Repository

    Liang, Shuai

    2014-08-01

    This study systematically investigates the organic fouling behavior of a superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membrane functionalized via post-fabrication tethering of surface-tailored silica nanoparticles to poly(methacrylic acid)-grafted PVDF membrane surface. Sodium alginate (SA), Suwannee River natural organic matter (SRNOM), and bovine serum albumin (BSA) were used as model organic foulants to investigate the antifouling behavior of the superhydrophilic membrane with combined-fouling (mixture of foulants) and individual-fouling (single foulant) tests. A membrane bioreactor (MBR) plant supernatant was also used to verify the organic antifouling property of the superhydrophilic membrane under realistic conditions. Foulant size distributions and foulant-membrane interfacial forces were measured to interpret the observed membrane fouling behavior. Molecular weight cutoff measurements confirmed that membrane functionalization did not adversely affect the intrinsic membrane selectivity. Both filtration tests with the synthetic foulant-mixture solution (containing SA, SRNOM, and BSA) and MBR plant supernatant demonstrated the reliability and durability of the antifouling property of the superhydrophilic membrane. The conspicuous reduction in foulant-membrane interfacial forces for the functionalized membrane further verified the antifouling properties of the superhydrophilic membrane, suggesting great potential for applications in wastewater treatment. © 2014 Elsevier B.V.

  7. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong; Fu, Xiuzhu; Chung, Neal Tai-Shung

    2014-01-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  8. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  9. Fouling of roughened stainless steel surfaces during convective heat transfer to aqueous solutions

    International Nuclear Information System (INIS)

    Herz, A.; Malayeri, M.R.; Mueller-Steinhagen, H.

    2008-01-01

    The deterioration of heat transfer performance due to fouling is the prime cause for higher energy consumption and inefficiency in many industrial heat exchangers such as those in power plants, refineries, food and dairy industries. Fouling is also a very complex process in which many geometrical, physical and operating parameters are involved with poorly understood interaction. Among them, the surface roughness is an important surface characteristic that would greatly influence crystallisation fouling mechanisms and hence deposition morphology and stickability to the surface. In this work, the effect of the surface roughness of AISI 304 BA stainless steel surfaces on fouling of an aqueous solution with inverse solubility behaviour has been investigated under convective heat transfer. Several experiments have been performed on roughened surfaces ranging from 0.18 to 1.55 μm for different bulk concentrations and heat fluxes. The EDTA titration method was used to measure the concentration of the calcium sulphate salt in order to maintain it at constant value during each fouling run. Experimental results show that the heat transfer coefficient of very rough surfaces (1.55 μm) decreases more rapidly than that of 0.54 μm. Several facts contribute to this behaviour notably (1) increased of primary heterogeneous nucleation rate on the surfaces; (2) reduction of local shear stress in the valleys and (3) reduced removal rate of the crystals from the surfaces where the roughness elements protrude out of the viscous sub-layer. The results also show linear and proportional variation of the fouling rate and heat flux within the range of operating conditions. In addition, the deposition process in terms of fouling rate could only be affected at lower surface contact angles. Such results would particularly be of interest for new surface treatment technologies which aim at altering the surface texture

  10. Reducing ultrafiltration membrane fouling during potable water reuse using pre-ozonation.

    Science.gov (United States)

    Wang, Hui; Park, Minkyu; Liang, Heng; Wu, Shimin; Lopez, Israel J; Ji, Weikang; Li, Guibai; Snyder, Shane A

    2017-11-15

    Wastewater reclamation has increasingly become popular to secure potable water supply. Low-pressure membrane processes such as microfiltration (MF) and ultrafiltration (UF) play imperative roles as a barrier of macromolecules for such purpose, but are often limited by membrane fouling. Effluent organic matter (EfOM), including biopolymers and particulates, in secondary wastewater effluents have been known to be major foulants in low-pressure membrane processes. Hence, the primary aim of this study was to investigate the effects of pre-ozonation as a pre-treatment for UF on the membrane fouling caused by EfOM in secondary wastewater effluents for hydrophilic regenerated cellulose (RC) and hydrophobic polyethersulfone (PES) UF membranes. It was found that greater fouling reduction was achieved by pre-ozonation for the hydrophilic RC membrane than the hydrophobic PES membrane at increasing ozone doses. In addition, the physicochemical property changes of EfOM, including biopolymer fractions, by pre-ozonation were systemically investigated. The classical pore blocking model and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theories were employed to scrutinize the fouling alleviation mechanism by pre-ozonation. As a result, the overarching mechanisms of fouling reduction were attributed to the following key reasons: (1) Ozone degraded macromolecules such as biopolymers like proteins and polysaccharides into smaller fractions, thereby increasing free energy of cohesion of EfOM and rendering them more hydrophilic and stable; (2) pre-ozonation augmented the interfacial free energy of adhesion between foulants and the RC/PES membranes, leading to the increase of repulsions and/or the decrease of attractions; and (3) pre-ozonation prolonged the transition from pore blocking to cake filtration that was a dominant fouling mechanism, thereby reducing fouling. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Membrane fouling and anti-fouling strategies using RO retentate from a municipal water recycling plant as the feed for osmotic power generation

    KAUST Repository

    Chen, Si Cong; Amy, Gary L.; Chung, Neal Tai-Shung

    2015-01-01

    RO retentate from a municipal water recycling plant is considered as a potential feed stream for osmotic power generation in this paper. The feasibility of using RO retentate from a municipal water recycling plant was examined from two aspects: (a) the membrane fouling propensity of RO retentate, and (b) the efficacy of anti-fouling strategies. The membranes used in this study were the inner selective thin film composite polyethersulfone (TFC/PES) hollow fiber membranes, which possessed a high water permeability and good mechanical strength. Scaling by phosphate salts was found to be one possible inorganic fouling on the innermost layer of the PES membrane, whereas silica fouling was observed to be the governing fouling on the outmost surface of the PES membrane. Two anti-fouling pretreatments, i.e., pH adjustment and anti-scalant pre-treatment for the feed stream, were studied and found to be straightforward and effective. Using RO retentate at pH 7.2 as the feed and 1 M NaCl as the draw solution, the average power density was 7.3 W/m at 20 bar. The average power density increased to 12.6 W/m by modifying RO retentate with an initial pH value of 5.5 using HCl and to 13.4 W/m by adding 1.1 mM ethylenediaminetetraacetic acid (EDTA). Moreover, the flux recovery of the fouled membranes, without the indicated pretreatments, reached 84.9% using deionized (DI) water flushing and 95.0% using air bubbling under a high crossflow velocity of 23.3 cm/s (Re = 2497) for 30 min. After pretreatment by pH adjustment, the flux recovery increased to 94.6% by DI water flushing and 100.0% by air bubbling. After pretreatment by adding 1.1 mM EDTA into RO retentate, flux was almost fully restored by physical cleaning by DI water flushing and air bubbling. These results provide insight into developing an effective pretreatment by either pH adjustment or EDTA addition before PRO and physical cleaning methods by DI water flushing and air bubbling for membrane used in osmotic power

  12. Membrane fouling and anti-fouling strategies using RO retentate from a municipal water recycling plant as the feed for osmotic power generation

    KAUST Repository

    Chen, Si Cong

    2015-10-25

    RO retentate from a municipal water recycling plant is considered as a potential feed stream for osmotic power generation in this paper. The feasibility of using RO retentate from a municipal water recycling plant was examined from two aspects: (a) the membrane fouling propensity of RO retentate, and (b) the efficacy of anti-fouling strategies. The membranes used in this study were the inner selective thin film composite polyethersulfone (TFC/PES) hollow fiber membranes, which possessed a high water permeability and good mechanical strength. Scaling by phosphate salts was found to be one possible inorganic fouling on the innermost layer of the PES membrane, whereas silica fouling was observed to be the governing fouling on the outmost surface of the PES membrane. Two anti-fouling pretreatments, i.e., pH adjustment and anti-scalant pre-treatment for the feed stream, were studied and found to be straightforward and effective. Using RO retentate at pH 7.2 as the feed and 1 M NaCl as the draw solution, the average power density was 7.3 W/m at 20 bar. The average power density increased to 12.6 W/m by modifying RO retentate with an initial pH value of 5.5 using HCl and to 13.4 W/m by adding 1.1 mM ethylenediaminetetraacetic acid (EDTA). Moreover, the flux recovery of the fouled membranes, without the indicated pretreatments, reached 84.9% using deionized (DI) water flushing and 95.0% using air bubbling under a high crossflow velocity of 23.3 cm/s (Re = 2497) for 30 min. After pretreatment by pH adjustment, the flux recovery increased to 94.6% by DI water flushing and 100.0% by air bubbling. After pretreatment by adding 1.1 mM EDTA into RO retentate, flux was almost fully restored by physical cleaning by DI water flushing and air bubbling. These results provide insight into developing an effective pretreatment by either pH adjustment or EDTA addition before PRO and physical cleaning methods by DI water flushing and air bubbling for membrane used in osmotic power

  13. Membrane fouling and anti-fouling strategies using RO retentate from a municipal water recycling plant as the feed for osmotic power generation.

    Science.gov (United States)

    Chen, Si Cong; Amy, Gary L; Chung, Tai-Shung

    2016-01-01

    RO retentate from a municipal water recycling plant is considered as a potential feed stream for osmotic power generation in this paper. The feasibility of using RO retentate from a municipal water recycling plant was examined from two aspects: (a) the membrane fouling propensity of RO retentate, and (b) the efficacy of anti-fouling strategies. The membranes used in this study were the inner selective thin film composite polyethersulfone (TFC/PES) hollow fiber membranes, which possessed a high water permeability and good mechanical strength. Scaling by phosphate salts was found to be one possible inorganic fouling on the innermost layer of the PES membrane, whereas silica fouling was observed to be the governing fouling on the outmost surface of the PES membrane. Two anti-fouling pretreatments, i.e., pH adjustment and anti-scalant pre-treatment for the feed stream, were studied and found to be straightforward and effective. Using RO retentate at pH 7.2 as the feed and 1 M NaCl as the draw solution, the average power density was 7.3 W/m(2) at 20 bar. The average power density increased to 12.6 W/m(2) by modifying RO retentate with an initial pH value of 5.5 using HCl and to 13.4 W/m(2) by adding 1.1 mM ethylenediaminetetraacetic acid (EDTA). Moreover, the flux recovery of the fouled membranes, without the indicated pretreatments, reached 84.9% using deionized (DI) water flushing and 95.0% using air bubbling under a high crossflow velocity of 23.3 cm/s (Re = 2497) for 30 min. After pretreatment by pH adjustment, the flux recovery increased to 94.6% by DI water flushing and 100.0% by air bubbling. After pretreatment by adding 1.1 mM EDTA into RO retentate, flux was almost fully restored by physical cleaning by DI water flushing and air bubbling. These results provide insight into developing an effective pretreatment by either pH adjustment or EDTA addition before PRO and physical cleaning methods by DI water flushing and air bubbling for membrane used in

  14. The preventing recurrent vascular events and neurological worsening through intensive organized case-management (PREVENTION trial protocol [clinicaltrials.gov identifier: NCT00931788

    Directory of Open Access Journals (Sweden)

    Tsuyuki Ross

    2010-04-01

    Full Text Available Abstract Background Survivors of transient ischemic attack (TIA or stroke are at high risk for recurrent vascular events and aggressive treatment of vascular risk factors can reduce this risk. However, vascular risk factors, especially hypertension and high cholesterol, are not managed optimally even in those patients seen in specialized clinics. This gap between the evidence for secondary prevention of stroke and the clinical reality leads to suboptimal patient outcomes. In this study, we will be testing a pharmacist case manager for delivery of stroke prevention services. We hypothesize this new structure will improve processes of care which in turn should lead to improved outcomes. Methods We will conduct a prospective, randomized, controlled open-label with blinded ascertainment of outcomes (PROBE trial. Treatment allocation will be concealed from the study personnel, and all outcomes will be collected in an independent and blinded manner by observers who have not been involved in the patient's clinical care or trial participation and who are masked to baseline measurements. Patients will be randomized to control or a pharmacist case manager treating vascular risk factors to guideline-recommended target levels. Eligible patients will include all adult patients seen at stroke prevention clinics in Edmonton, Alberta after an ischemic stroke or TIA who have uncontrolled hypertension (defined as systolic blood pressure (BP > 140 mm Hg or dyslipidemia (fasting LDL-cholesterol > 2.00 mmol/L and who are not cognitively impaired or institutionalized. The primary outcome will be the proportion of subjects who attain 'optimal BP and lipid control'(defined as systolic BP Conclusions Nearly one-quarter of those who survive a TIA or minor stroke suffer another vascular event within a year. If our intervention improves the provision of secondary prevention therapies in these patients, the clinical (and financial implications will be enormous.

  15. Molecular characterization of a Xylanase-producing fungus isolated from fouled soil

    Directory of Open Access Journals (Sweden)

    Punniavan Sakthiselvan

    2014-12-01

    Full Text Available Xylanase (EC 3. 2. 1. 8, hydrolyzes xylo-oligosaccharides into D-xylose and required for complete hydrolysis of native cellulose and biomass conversion. It has broad range of applications in the pulp and paper, pharmaceutical and Agri-food industries. Fifty fungal species were isolated from the fouled soil around an oil refinery and screened for the production of xylanase enzyme by enrichment culture techniques. The isolated fungal strain was identified as Hypocrea lixii SS1 based on the results of biochemical tests and 18s rRNA sequencing. The phylogenetic tree was constructed using the MEGA 5 software. Further, Hypocrea lixii SS1 was tested for the ability to utilize the sunflower oil sludge (waste from the oil industry as the sole carbon source for xylanase production. The growth characteristics of Hypocrea lixii SS1 were also studied and maximum growth was found on the 7th day of incubation. The fungus showed a remarkable xylanase production of 38.9 U/mL. Xylanase was purified using a combination of 0-50% NH4SO2 precipitation, DEAE-sepharose and Sephacryl S-200 chromatography. Single peak obtained in RP-HPLC confirms the purity of xylanase. Further the enzyme produced was affirmed as xylanase with its molecular weight (29 kDa using SDS-PAGE.

  16. The GLOFOULING Partnerships project and the anti-fouling systems: challenges for Marine Environment Protection

    Directory of Open Access Journals (Sweden)

    Fabián Ramírez Cabrales

    2018-05-01

    Full Text Available Within the framework of the Agenda 2030 for Sustainable Development, the regulation of international maritime transport is a priority to face the challenges on the Protection of the Marine Environment. However, some states present difficulties in complying with international or normative agreements adopted by the International Maritime Organization (IMO. In particular, we revised the Guidelines for the control and management of ships’ biofouling to minimize the transfer of invasive aquatic species and their linkage with the Glofouling Associations project, including the adverse effects of the use of antifouling systems and the biocides that may contain. As preliminary results, we identified the challenges that this global project entails for States, shipbuilders, ship maintenance and cleaning companies, universities, port authorities, repair facilities, dry docks and ship recycling, manufacturers and suppliers of anti-fouling paints and other stakeholders. We concluded that the challenges for the international maritime community are linked to the ability of States and stakeholders to enhance scientific knowledge, develop research capacity and transfer marine technology to mitigate marine biological contamination of ships.

  17. Identifying Relationships between High-Risk Sexual Behaviors and Screening Positive for Chlamydia and Gonorrhea in School-Wide Screening Events

    Science.gov (United States)

    Salerno, Jennifer; Darling-Fisher, Cindy; Hawkins, Nicole M.; Fraker, Elizabeth

    2013-01-01

    Background: This article describes a school-wide sexually transmitted infection (STI) screening to identify adolescent high-risk sexual behaviors, STI history/incidence, and presence of chlamydia and gonorrhea, and examines relationships between high-risk behaviors and screening positive for chlamydia and gonorrhea in an alternative high school…

  18. Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (70ºC - 74.5ºC

    Directory of Open Access Journals (Sweden)

    Suvit Tia

    2006-11-01

    Full Text Available Effects of fluid flowrate on coconut milk fouling at pasteurization temperature (heating from 70ºC to 74.5ºC were investigated. A test section equipped with four flat plates forming one coconut milk channel and two hot water channels was constructed with the total heat transfer area of 0.051 m2. Three different flowrates of coconut milk (2, 4 and 6 litres per minute (LPM were studied. Monitoring of the overall heat transfer coefficient (U with time (t and the rate of increase of the fouling resistance (dRf/dt was done for all experimental runs. The results illustrated that there were two fouling periods: a fouling period and a post-fouling period, where the rate of increase of the fouling resistance of the fouling period was found to be higher than that of the post-fouling period. The effects of fluid flowrate were found to increase the fouling rate when the flowrate decreased. Published fouling models by protein solutions were unable to predict accurately the fouling rate for coconut milk. Non-linear regression models were then provided by using the experimental data to illustrate the effects of fluid flowrate on coconut milk fouling. The role of protein and fat on coconut milk fouling was explained according to microanalysis of the deposit and chemistry data of the coconut milk from previous research.

  19. Physical–chemical properties, separation performance, and fouling resistance of mixed-matrix ultrafiltration membranes

    KAUST Repository

    Hoek, Eric M.V.; Ghosh, Asim K.; Huang, Xiaofei; Liong, Monty; Zink, Jeffrey I.

    2011-01-01

    Herein we report on the formation and characterization of mixed-matrix ultrafiltration (UF) membranes hand-cast by nonsolvent induced phase inversion. We evaluated nanometer-to-micrometer sized inorganic fillers (silver, copper, silica, zeolite, and silver-zeolite) materials with polysulfone (PSf) as the polymeric dispersing matrix. In general, mixed-matrix membranes were rougher, more hydrophilic, and more mechanically robust. Only sub-micron zeolite-PSf mixed-matrix membranes exhibited simultaneous improvements in water permeability and solute selectivity; all other mixed-matrix membranes were more permeable, but less selective due to defects associated with poor polymer-filler binding. Protein and bacterial fouling resistance of mixed-matrix membranes containing silver, zeolite, and silver-zeolite nanoparticles were compared to a low-fouling, poly(acrylonitrile) (PAN) UF membrane. Zeolite and silver containing membranes exhibited better protein fouling resistance (due to higher hydrophilicity), whereas silver and silver-zeolite based membranes produce better bacterial fouling resistance due to antimicrobial properties. Overall, zeolite-PSf and silver exchanged zeolite-PSf membranes offered the best combination of improved permeability, selectivity, and fouling resistance - superior to the commercial PAN membrane. © 2011 Elsevier B.V.

  20. Surface and anti-fouling properties of a polyampholyte hydrogel grafted onto a polyethersulfone membrane.

    Science.gov (United States)

    Zhang, Wei; Yang, Zhe; Kaufman, Yair; Bernstein, Roy

    2018-05-01

    Zwitterion polymers have anti-fouling properties; therefore, grafting new zwitterions to surfaces, particularly as hydrogels, is one of the leading research directions for preventing fouling. Specifically, polyampholytes, polymers of random mixed charged subunits with a net-electric charge, offer a synthetically easy alternative for studying new zwitterions with a broad spectrum of charged moieties. Here, a novel polyampholyte hydrogel was grafted onto the surface of polyethersulfone membrane by copolymerizing a mixture of vinylsulfonic acid (VSA) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METMAC) as the negatively and positively charged monomers, respectively, using various monomer ratios in the polymerization solution, and with N,N'-methylenebisacrylamide as the crosslinker. The physicochemical, morphological and anti-fouling properties of the modified membranes were systematically investigated. Hydrophilic hydrogels were successfully grafted using monomers at different molar ratios. A thin-film zwitterion hydrogel (∼90 nm) was achieved at a 3:1 [VSA:METMAC] molar ratio in the polymerization solution. Among all examined membranes, the zwitterion polyampholyte-modified membrane demonstrated the lowest adsorption of proteins, humic acid, and sodium alginate. It also had low fouling and high flux recovery following filtration with a protein or with an extracellular polymeric substance solution. These findings suggest that this polyampholyte hydrogel is applicable as a low fouling surface coating. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Differential natural organic matter fouling of ceramic versus polymeric ultrafiltration membranes.

    Science.gov (United States)

    Lee, Seung-Jin; Kim, Jae-Hong

    2014-01-01

    Ceramic ultrafiltration membranes has drawn increasing attention in drinking water treatment sectors as an alternative to traditional polymeric counterparts, yet only limited information has been made available about the characteristics of ceramic membrane fouling by natural organic matter. The effects of solution chemistry including ionic strength, divalent ion concentration and pH on the flux behavior were comparatively evaluated for ceramic and polymeric ultrafiltration of synthetic water containing model natural organic matter. Filtration characteristics were further probed via resistance-in-series model analysis, fouling visualization using quantum dots, batch adsorption test, contact angle measurement, solute-membrane surface adhesion force measurement, and quantitative comparison of fouling characteristics between ceramic and polymeric membranes. The results collectively suggested that the effects of solution chemistry on fouling behavior of ceramic membranes were generally similar to polymeric counterparts in terms of trends, while the extent varied significantly depending on water quality parameters. Lower fouling tendency and enhanced cleaning efficiency were observed with the ceramic membrane, further promoting the potential for ceramic membrane application to surface water treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Physical–chemical properties, separation performance, and fouling resistance of mixed-matrix ultrafiltration membranes

    KAUST Repository

    Hoek, Eric M.V.

    2011-12-01

    Herein we report on the formation and characterization of mixed-matrix ultrafiltration (UF) membranes hand-cast by nonsolvent induced phase inversion. We evaluated nanometer-to-micrometer sized inorganic fillers (silver, copper, silica, zeolite, and silver-zeolite) materials with polysulfone (PSf) as the polymeric dispersing matrix. In general, mixed-matrix membranes were rougher, more hydrophilic, and more mechanically robust. Only sub-micron zeolite-PSf mixed-matrix membranes exhibited simultaneous improvements in water permeability and solute selectivity; all other mixed-matrix membranes were more permeable, but less selective due to defects associated with poor polymer-filler binding. Protein and bacterial fouling resistance of mixed-matrix membranes containing silver, zeolite, and silver-zeolite nanoparticles were compared to a low-fouling, poly(acrylonitrile) (PAN) UF membrane. Zeolite and silver containing membranes exhibited better protein fouling resistance (due to higher hydrophilicity), whereas silver and silver-zeolite based membranes produce better bacterial fouling resistance due to antimicrobial properties. Overall, zeolite-PSf and silver exchanged zeolite-PSf membranes offered the best combination of improved permeability, selectivity, and fouling resistance - superior to the commercial PAN membrane. © 2011 Elsevier B.V.

  3. Fouling development in direct contact membrane distillation: Non-invasive monitoring and destructive analysis

    KAUST Repository

    Fortunato, Luca

    2017-12-26

    Fouling development in direct contact membrane distillation (DCMD) for seawater desalination was evaluated combining in-situ monitoring performed using optical coherence tomography (OCT) together with destructive techniques. The non-invasive monitoring with OCT provided a better understanding of the fouling mechanism by giving an appropriate sampling timing for the membrane autopsy. The on-line monitoring system allowed linking the flux trend with the structure of fouling deposited on the membrane surface. The water vapor flux trend was divided in three phases based on the deposition and formation of different foulants over time. The initial flux decline was due to the deposition of a 50–70 nm porous fouling layer consisting of a mixture of organic compounds and salts. Liquid chromatography with organic carbon detection (LC-OCD) analysis revealed the abundance of biopolymer in the fouling layer formed at the initial phase. In the second phase, formation of carbonate crystals on the membrane surface was observed but did not affect the flux significantly. In the last phase, the water vapor flux dropped to almost zero due to the deposition of a dense thick layer of sulfate crystals on the membrane surface.

  4. Comparison of fouling characteristics in different pore-sized submerged ceramic membrane bioreactors.

    Science.gov (United States)

    Jin, Le; Ong, Say Leong; Ng, How Yong

    2010-12-01

    Membrane fouling, the key disadvantage that inevitably occurs continuously in the membrane bioreactor (MBR), baffles the wide-scale application of MBR. Ceramic membrane, which possesses high chemical and thermal resistance, has seldom been used in MBR to treat municipal wastewater. Four ceramic membranes with the same materials but different pore sizes, ranging from 80 to 300 nm, were studied in parallel using four lab-scale submerged MBRs (i.e., one type of ceramic membrane in one MBR). Total COD and ammonia nitrogen removal efficiencies were observed to be consistently above 94.5 and 98%, respectively, in all submerged ceramic membrane bioreactors. The experimental results showed that fouling was mainly affected by membrane's microstructure, surface roughness and pore sizes. Ceramic membrane with the roughest surface and biggest pore size (300 nm) had the highest fouling potential with respect to the TMP profile. The 80 nm membrane with a smoother surface and relatively uniform smaller pore openings experienced least membrane fouling with respect to TMP increase. The effects of the molecular weight distribution, particle size distribution and other biomass characteristics such as extracellular polymeric substances, zeta potential and capillary suction time, were also investigated in this study. Results showed that no significant differences of these attributes were observed. These observations indicate that the membrane surface properties are the dominant factors leading to different fouling potential in this study. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Numerical simulation of calcium sulfate (CaSO4) fouling in the plate heat exchanger

    Science.gov (United States)

    Xu, Zhiming; Zhao, Yu; Han, Zhimin; Wang, Jingtao

    2018-07-01

    Plate heat exchanger is a widely used apparatus in the industrial production processes. Through a numerical simulation method, this paper calculates the deposition rate of CaSO4 fouling on heat transfer surfaces of the plate heat exchanger under saturation in the bulk. The effects of CaSO4 concentration in the range 0.7 kg/m3 to 1.5 kg/m3, inlet flow velocity under turbulent flow, and the fluid's inlet temperature from 288 K to 328 K on the deposition rate, removal mass rate and fouling resistance are investigated. The simulation results are compared with the experimental results showing similar trend. The simulation results show that the concentration and the flow velocity affect significantly the fouling characteristics in the plate heat exchanger. The deposition mass rate, removal mass rate, and asymptotic value of fouling resistance all increase with the increase in CaSO4 concentration and the inlet temperature of the hot fluid, while the asymptotic value of fouling resistance decreases with the increasing of inlet flow velocity. The influence of the inlet temperature of cold fluid may be negligible.

  6. Iodine-infused aeration for hull fouling prevention: a vessel-scale study.

    Science.gov (United States)

    Dickenson, Natasha C; Krumholz, Jason S; Hunsucker, Kelli Z; Radicone, Michael

    2017-11-01

    Biofouling is a significant economic and ecological problem, causing reduced vessel performance and increases in fuel consumption and emissions. Previous research has shown iodine vapor (I 2 )-infused aeration to be an environmentally friendly method for deterring the settlement of fouling organisms. An aeration system was deployed on a vessel with hull sections coated with two types of antifoulant coatings, Intersleek ® 1100 (fouling-release) and Interspeed ® BRA-640 (ablative copper biocide), as well as an inert epoxy barrier coating, to assess the effectiveness of aeration in conjunction with common marine coatings. I 2 -infused aeration resulted in consistent reductions of 80-90% in hard fouling across all three coatings. Additionally, aeration reduced the soft fouling rate by 45-70% when used in conjunction with both Intersleek ® and Interspeed ® BRA versus those coatings alone. The results of this study highlight the contribution of I 2 -infused aeration as a standalone mechanism for fouling prevention or as a complement to traditional antifouling coatings.

  7. FLUX PROFILES AND MATHEMATICAL MODELING OF FOULING MECHANISM FOR ULTRAFILTRATION OF KONJAC GLUCOMANNAN

    Directory of Open Access Journals (Sweden)

    NITA ARYANTI

    2016-07-01

    Full Text Available This study was focused on principles and fouling analysis of konjac glucomannan (KGM separation using ultrafiltration system. Two Polyethersulfone membranes (PES having molecular weight cut-off of 10 and 20 kDa were used. It was found that membrane having larger pore size provided higher flux profiles. Evaluation of different transmembrane pressures resulted on possibility of more severe fouling at higher membrane pressure. With the increase of konjac glucomannan concentration, decrease of profile flux was observed. Further, a simple mathematical modelling of fouling mechanism was analyzed based on Hermia’s model. The images of membrane surfaces and cross-sections obtained by scanning electron microscopy (SEM were examined and being compared with the model. The research found that the fouling mechanisms of KGM ultrafiltration using membrane with pore size of 10 kDa was complete blocking. On the contrary, cake/gel layer formation was a fouling mechanism for ultrafiltration system with pore size of 20kDa.

  8. Novel Fouling-Reducing Coatings for Ultrafiltration, Nanofiltration, and Reverse Osmosis Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Benny Freeman

    2008-08-31

    Polymeric membranes could potentially be the most flexible and viable long-term strategy for treatment of produced water from oil and gas production. However, widespread use of membranes, including reverse osmosis (RO) membranes, for produced water purification is hindered due to fouling caused by the impurities present in the water. Fouling of RO membranes is likely caused by surface properties including roughness, hydrophilicity, and charge, so surface modification is the most widely considered approach to improve the fouling properties of current RO membranes. This project focuses on two main approaches to surface modification: coating and grafting. Hydrophilic coating and grafting materials based on poly(ethylene glycol) (PEG) are applied to commercial RO membranes manufactured by Dow FilmTec and GE. Crossflow filtration experiments are used to determine the fouling resistance of modified membranes, and compare their performance to that of unmodified commercial RO membranes. Grafting and coating are shown to be two alternative methods of producing modified membranes with improved fouling resistance.

  9. Numerical simulation of calcium sulfate (CaSO4) fouling in the plate heat exchanger

    Science.gov (United States)

    Xu, Zhiming; Zhao, Yu; Han, Zhimin; Wang, Jingtao

    2018-01-01

    Plate heat exchanger is a widely used apparatus in the industrial production processes. Through a numerical simulation method, this paper calculates the deposition rate of CaSO4 fouling on heat transfer surfaces of the plate heat exchanger under saturation in the bulk. The effects of CaSO4 concentration in the range 0.7 kg/m3 to 1.5 kg/m3, inlet flow velocity under turbulent flow, and the fluid's inlet temperature from 288 K to 328 K on the deposition rate, removal mass rate and fouling resistance are investigated. The simulation results are compared with the experimental results showing similar trend. The simulation results show that the concentration and the flow velocity affect significantly the fouling characteristics in the plate heat exchanger. The deposition mass rate, removal mass rate, and asymptotic value of fouling resistance all increase with the increase in CaSO4 concentration and the inlet temperature of the hot fluid, while the asymptotic value of fouling resistance decreases with the increasing of inlet flow velocity. The influence of the inlet temperature of cold fluid may be negligible.

  10. Pore channel surface modification for enhancing anti-fouling membrane distillation

    Science.gov (United States)

    Qiu, Haoran; Peng, Yuelian; Ge, Lei; Villacorta Hernandez, Byron; Zhu, Zhonghua

    2018-06-01

    Membrane surface modification by forming a functional layer is an effective way to improve the anti-fouling properties of membranes; however, the additional layer and the potential blockage of bulk pores may increase the mass transfer resistance and reduce the permeability. In this study, we applied a novel method of preparing anti-fouling membranes for membrane distillation by dispersing graphene oxide (GO) on the channel surface of polyvinylidene fluoride membranes. The surface morphology and properties were characterized by scanning electron microscopy, atomic force microscope, and Fourier transform infrared spectrometry. Compared to the membrane surface modification by nanoparticles (e.g. SiO2), GO was mainly located on the pore surface of the membrane bulk, rather than being formed as an individual layer onto the membrane surface. The performance was evaluated via a direct-contact membrane distillation process with anionic and cationic surfactants as the foulants, separately. Compared to the pristine PVDF membrane, the anti-fouling behavior and distillate flux of the GO-modified membranes were improved, especially when using the anionic surfactant as the foulant. The enhanced anti-fouling performance can be attributed to the oxygen containing functional groups in GO and the healing of the membrane pore defects. This method may provide an effective route to manipulate membrane pore surface properties for anti-fouling separation without increasing mass transfer resistance.

  11. Modeling and field studies of fouling in once-through steam generators

    International Nuclear Information System (INIS)

    Thompson, R.; Gaudreau, T.

    1995-01-01

    Efforts of the past 10 years to minimize fouling of the Crystal River-3 once-through steam generators are reviewed. The major focus has been on improving at-temperature pH control in the secondary cycle. Various concentrations of different pH control agents were tested in the field for hundreds of days to determine their effect on steam generator fouling. High concentrations of morpholine (50--100 ppm) in the feedwater were found to apparently produce de-fouling of the steam generators without an associated decrease in feedwater iron concentration as compared to that at lower levels of morpholine. Computer modeling of the pH(t) within the OTSG for the various chemistries tested indicates that the pH can change significantly with elevation within the steam generator by varying the pH control agent or its concentration. It is postulated that these variations in pH may change the surface charge of the tubes, tube support plates, and/or corrosion product particles in solution, to favor either deposition or repulsion of the particles, and thereby producing conditions that either favor fouling or de-fouling of the OTSG. Crystal River-3 experience indicates that corrosion product deposition and release processes inside the steam generator can be chemically manipulated to favor release, and thereby maximize plant performance, and delay or avoid costly hydraulic or chemical cleanings

  12. Identifying the Climatic Conditions in Iraq by Tracking Down Cooling Events in the North Atlantic Ocean in the Period 3000–0 BC

    Directory of Open Access Journals (Sweden)

    Muslih Khamis D.

    2014-09-01

    Full Text Available North Atlantic Oscillation (NAO, monthly averages of precipitation in the Baghdad station, and petrologic tracer proxy data for ocean properties in the North Atlantic (NA have been used in an attempt to identify climatic conditions in Iraq during the study period. The study showed that contemporary changes in precipitation in Iraq are associated with NAO, as a negative relationship is found between them. Moreover, the study found that there is a strong negative correlation between NAOI and SST in NA, where drift ice indices explain between 33–36% of the NAOI variability.

  13. Mobile phone sensors and supervised machine learning to identify alcohol use events in young adults: Implications for just-in-time adaptive interventions.

    Science.gov (United States)

    Bae, Sangwon; Chung, Tammy; Ferreira, Denzil; Dey, Anind K; Suffoletto, Brian

    2017-11-27

    Real-time detection of drinking could improve timely delivery of interventions aimed at reducing alcohol consumption and alcohol-related injury, but existing detection methods are burdensome or impractical. To evaluate whether phone sensor data and machine learning models are useful to detect alcohol use events, and to discuss implications of these results for just-in-time mobile interventions. 38 non-treatment seeking young adult heavy drinkers downloaded AWARE app (which continuously collected mobile phone sensor data), and reported alcohol consumption (number of drinks, start/end time of prior day's drinking) for 28days. We tested various machine learning models using the 20 most informative sensor features to classify time periods as non-drinking, low-risk (1 to 3/4 drinks per occasion for women/men), and high-risk drinking (>4/5 drinks per occasion for women/men). Among 30 participants in the analyses, 207 non-drinking, 41 low-risk, and 45 high-risk drinking episodes were reported. A Random Forest model using 30-min windows with 1day of historical data performed best for detecting high-risk drinking, correctly classifying high-risk drinking windows 90.9% of the time. The most informative sensor features were related to time (i.e., day of week, time of day), movement (e.g., change in activities), device usage (e.g., screen duration), and communication (e.g., call duration, typing speed). Preliminary evidence suggests that sensor data captured from mobile phones of young adults is useful in building accurate models to detect periods of high-risk drinking. Interventions using mobile phone sensor features could trigger delivery of a range of interventions to potentially improve effectiveness. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Electro-Conductive Membranes for Permeation Enhancement and Fouling Mitigation: A Short Review.

    Science.gov (United States)

    Formoso, Patrizia; Pantuso, Elvira; De Filpo, Giovanni; Nicoletta, Fiore Pasquale

    2017-07-28

    The research on electro-conductive membranes has expanded in recent years. These membranes have strong prospective as key components in next generation water treatment plants because they are engineered in order to enhance their performance in terms of separation, flux, fouling potential, and permselectivity. The present review summarizes recent developments in the preparation of electro-conductive membranes and the mechanisms of their response to external electric voltages in order to obtain an improvement in permeation and mitigation in the fouling growth. In particular, this paper deals with the properties of electro-conductive polymers and the preparation of electro-conductive polymer membranes with a focus on responsive membranes based on polyaniline, polypyrrole and carbon nanotubes. Then, some examples of electro-conductive membranes for permeation enhancement and fouling mitigation by electrostatic repulsion, hydrogen peroxide generation and electrochemical oxidation will be presented.

  15. Heat Exchange and Fouling Analysis on a Set of Hydrogen Sulphide Gas Coolers

    Directory of Open Access Journals (Sweden)

    Andrés Adrian Sánchez-Escalona

    2017-07-01

    Full Text Available The sulphide acid coolers are tube and shell jacketed heat exchangers designed to cool down the produced gas from 416,15 K to 310,15 K in addition to separate the sulphur carried over by the outlet gas from the reactor tower. The investigation was carried out by applying the passive experimentation process in an online cooler set in order to determine the heat transfer rates and fouling based on heat resistance. It was corroborated that the operation of this equipment outside design parameters increases outlet gas temperature and liquid sulphur carryovers. Efficiency loss is caused by fouling elements in the fluid, which results in changes in the overall heat transfer rate. The linear tendency of the fouling heat resistance based on time for three gas flowrates.

  16. Anti fouling effect of two saturated copper coatings applied on carbon steel structures

    International Nuclear Information System (INIS)

    Guiamet, P. S.; Gomez de Saravia, S. G.

    2008-01-01

    Biofouling is the colonization of man-made substrata by sessile organisms. The aim of this paper is to evaluate the performance of two anti fouling saturated copper coating. Bioassays were carried out at a harbor in Argentine (38 degree centigrade 02' S-57 degree centigrade 32'W). during six months, one series of pipes and panels were removed monthly to estimate the recruitment of macro and micro fouling species and immediately replaced by clean ones. Another series was removed from the beginning of exposure to monitor the development of the established community (accumulative pipes and panels along six months). Data obtained from control (without a saturated copper coating) and saturated-copper coated pipes and panels were compared in order to estimate performance of the coating. One of two saturated copper coating demonstrated a good effect anti fouling. (Author) 25 refs

  17. Mathematical models of membrane fouling in cross-flow micro-filtration

    Directory of Open Access Journals (Sweden)

    Mónica Jimena Ortíz Jerez

    2008-01-01

    Full Text Available The greatest difficulty arising during cross-flow micro-filtration is the formation of a cake layer on the membrane sur-face (also called fouling, thereby affecting system performance. Fouling has been related to permeate flux decay re-sulting from changes in operating variables. Many articles have been published in an attempt to explain this phe-nomenon but it has not yet been fully understood because it depends on specific solution/membrane interactions and differing parameters. This work was aimed at presenting an analytical review of recently published mathematical models to explain fouling. Although the reviewed models can be adjusted to any type of application, a simple “con-centration polarisation” model is advisable in the particular case of tropical fruit juices for describing the insoluble solids being deposited on membrane surface.

  18. Fouling kinetics in microfiltration of protein solutions using different membrane configurations

    DEFF Research Database (Denmark)

    Jakobsen, Sune; Jonsson, Gunnar Eigil

    1997-01-01

    Protein fouling in microfiltration has a large impact on the permeate flux and observed retention of the proteins despite the fact that the protein molecule is several times smaller than the average pore size in microfiltration membranes. This is due to adsorption and deposition of protein...... molecules and aggregates. The effect of membrane configuration upon protein fouling was investigated in crossflow filtration with asymmetric membranes either in a normal mode or in a reverse mode. It was observed by Jonsson et al. [1] that beer filtration in a reverse mode results in a smaller decrease...... in the flux compared to beer filtration in a normal mode. Similar results for protein filtration were observed by Bowen et al. [2]. One possible way to avoid fouling is the novel backshock technique (see Jonsson et al. [1]). The effect of backshock on protein filtration was investigated using a hollow fiber...

  19. Electro-Conductive Membranes for Permeation Enhancement and Fouling Mitigation: A Short Review

    Directory of Open Access Journals (Sweden)

    Patrizia Formoso

    2017-07-01

    Full Text Available The research on electro-conductive membranes has expanded in recent years. These membranes have strong prospective as key components in next generation water treatment plants because they are engineered in order to enhance their performance in terms of separation, flux, fouling potential, and permselectivity. The present review summarizes recent developments in the preparation of electro-conductive membranes and the mechanisms of their response to external electric voltages in order to obtain an improvement in permeation and mitigation in the fouling growth. In particular, this paper deals with the properties of electro-conductive polymers and the preparation of electro-conductive polymer membranes with a focus on responsive membranes based on polyaniline, polypyrrole and carbon nanotubes. Then, some examples of electro-conductive membranes for permeation enhancement and fouling mitigation by electrostatic repulsion, hydrogen peroxide generation and electrochemical oxidation will be presented.

  20. Growth of fouling diatoms from the Zuari estuary, Goa (west coast of India) under different salinities in the laboratory

    Digital Repository Service at National Institute of Oceanography (India)

    Redekar, P.D.; Wagh, A.B.

    Diatoms take part in the initial process of fouling i.e. primary film formation. In order to understand the growth of the diatoms under different salinity conditions in the laboratory, this work was undertaken. Fouling diatoms on glass slides were...

  1. Fouling reduction by ozone-enhanced backwashing process in ultrafiltration of petroleum-based oil in water emulsion

    Science.gov (United States)

    Aryanti, Nita; Prihatiningtyas, Indah; Kusworo, Tutuk Djoko

    2017-06-01

    Ultrafiltration membrane has been successfully applied for oily waste water treatment. However, one significant drawback of membrane technology is fouling which is responsible for permeate flux decline as well as reducing membrane performance. One method commonly used to reduce fouling is a backwashing process. The backwashing is carried out by a push of reversed flow from permeate side to the feed side of a membrane to remove fouling on the membrane pore and release fouling release fouling layer on the external side. However, for adsorptive fouling, the backwashing process was not effective. On the other hand, Ozone demonstrated great performance for reducing organics fouling. Hence this research was focused on backwashing process with ozone for removing fouling due to ultrafiltration of petroleum based oil emulsion. Gasoline and diesel oil were selected as dispersed phase, while as continuous phase was water added with Tween 80 as a surfactant. This research found that the Ozone backwashing was effective to improve flux recovery. In ultrafiltration of gasoline emulsion, the flux recovery after Ozone backwashing was in the range of 42-74%. For ultrafiltration of diesel oil emulsion, the permeate flux recovery was about 35-84%. In addition, foulant deposition was proposed and predicting that foulant deposition for ultrafiltration of gasoline-in-water emulsion was surfactant as the top layer and the oil was underneath the surfactant. On the other hand, for ultrafiltration of diesel oil-in-water emulsion, the oil was predicted as a top layer above the surfactant foulant.

  2. Influence of natural organic matter fouling and osmotic backwash on pressure retarded osmosis energy production from natural salinity gradients.

    Science.gov (United States)

    Yip, Ngai Yin; Elimelech, Menachem

    2013-01-01

    Pressure retarded osmosis (PRO) has the potential to produce clean, renewable energy from natural salinity gradients. However, membrane fouling can lead to diminished water flux productivity, thus reducing the extractable energy. This study investigates organic fouling and osmotic backwash cleaning in PRO and the resulting impact on projected power generation. Fabricated thin-film composite membranes were fouled with model river water containing natural organic matter. The water permeation carried foulants from the feed river water into the membrane porous support layer and caused severe water flux decline of ∼46%. Analysis of the water flux behavior revealed three phases in membrane support layer fouling. Initial foulants of the first fouling phase quickly adsorbed at the active-support layer interface and caused a significantly greater increase in hydraulic resistance than the subsequent second and third phase foulants. The water permeability of the fouled membranes was lowered by ∼39%, causing ∼26% decrease in projected power density. A brief, chemical-free osmotic backwash was demonstrated to be effective in removing foulants from the porous support layer, achieving ∼44% recovery in projected power density. The substantial performance recovery after cleaning was attributed to the partial restoration of the membrane water permeability. This study shows that membrane fouling detrimentally impacts energy production, and highlights the potential strategies to mitigate fouling in PRO power generation with natural salinity gradients.

  3. Combined effects of coagulation and adsorption on ultrafiltration membrane fouling control and subsequent disinfection in drinking water treatment.

    Science.gov (United States)

    Xing, Jiajian; Liang, Heng; Cheng, Xiaoxiang; Yang, Haiyan; Xu, Daliang; Gan, Zhendong; Luo, Xinsheng; Zhu, Xuewu; Li, Guibai

    2018-06-02

    This study investigated the combined effects of coagulation and powdered activated carbon (PAC) adsorption on ultrafiltration (UF) membrane fouling control and subsequent disinfection efficiency through filtration performance, dissolved organic carbon (DOC) removal, fluorescence excitation-emission matrix (EEM) spectroscopy, and disinfectant curve. The fouling behavior of UF membrane was comprehensively analyzed especially in terms of pollutant removal and fouling reversibility to understand the mechanism of fouling accumulation and disinfectant dose reduction. Pre-coagulation with or without adsorption both achieved remarkable effect of fouling mitigation and disinfection dose reduction. The two pretreatments were effective in total fouling control and pre-coagulation combined with PAC adsorption even decreased hydraulically irreversible fouling notably. Besides, pre-coagulation decreased residual disinfectant decline due to the removal of hydrophobic components of natural organic matters (NOM). Pre-coagulation combined with adsorption had a synergistic effect on further disinfectant decline rate reduction and decreased total disinfectant consumption due to additional removal of hydrophilic NOM by PAC adsorption. The disinfectant demand was further reduced after membrane. These results show that membrane fouling and disinfectant dose can be reduced in UF coupled with pretreatment, which could lead to the avoidance of excessive operation cost disinfectant dose for drinking water supply.

  4. Flux patterns and membrane fouling propensity during desalination of seawater by forward osmosis

    KAUST Repository

    Li, Zhenyu; Yangali-Quintanilla, Victor; Valladares Linares, Rodrigo; Li, Qingyu; Zhan, Tong; Amy, Gary L.

    2012-01-01

    The membrane fouling propensity of natural seawater during forward osmosis was studied. Seawater from the Red Sea was used as the feed in a forward osmosis process while a 2. M sodium chloride solution was used as the draw solution. The process was conducted in a semi-batch mode under two crossflow velocities, 16.7. cm/s and 4.2. cm/s. For the first time reported, silica scaling was found to be the dominant inorganic fouling (scaling) on the surface of membrane active layer during seawater forward osmosis. Polymerization of dissolved silica was the major mechanism for the formation of silica scaling. After ten batches of seawater forward osmosis, the membrane surface was covered by a fouling layer of assorted polymerized silica clusters and natural organic matter, especially biopolymers. Moreover, the absorbed biopolymers also provided bacterial attachment sites. The accumulated organic fouling could be partially removed by water flushing while the polymerized silica was difficult to remove. The rate of flux decline was about 53% with a crossflow velocity of 16.7. cm/s while reaching more than 70% with a crossflow velocity of 4.2. cm/s. Both concentration polarization and fouling played roles in the decrease of flux. The salt rejection was stable at about 98% during seawater forward osmosis. In addition, an almost complete rejection of natural organic matter was attained. The results from this study are valuable for the design and development of a successful protocol for a pretreatment process before seawater forward osmosis and a cleaning method for fouled membranes. © 2011 Elsevier Ltd.

  5. Fouling of coarse-clastic sediments with macrophytes depending on the rate of abrasion, Murmansk coast

    Science.gov (United States)

    Malavenda, S. V.; Mitayev, M. V.; Malavenda, S. S.; Gerasimova, M. V.

    2017-05-01

    It is shown for the first time that the hydrodynamics and average daily gradient of air temperature affect the rate of abrasion of the coarse-clastic material on the boulder littoral of the Murmansk coast, as well as the density of its fouling by macroalgae. The proportion and biomass of species-explerents vary depending on the hydrological and meteorological conditions. The annual species-explerents ( Acrosiphonia arcta, Blidingia minima, Spongomorpha aeruginosa, Pylaiella littoralis) are the basis for new phytocenoses. In the fucus phytocenoses of the boulder littoral, these groupings represent the intermediate stage of fouling of the coarse-clastic material.

  6. Dynamics of the Fouling Layer Microbial Community in a Membrane Bioreactor

    DEFF Research Database (Denmark)

    Ziegler, Anja Sloth; McIlroy, Simon Jon; Larsen, Poul

    2016-01-01

    Membrane fouling presents the greatest challenge to the application of membrane bioreactor (MBR) technology. Formation of biofilms on the membrane surface is the suggested cause, yet little is known of the composition or dynamics of the microbial community responsible. To gain an insight...... of the fouling process, we concurrently investigated the communities of the biofilm, MBR bulk sludge, and the conventional activated sludge system used to seed the MBR system over several weeks from start-up. As the biofilm matured the initially abundant betaproteobacterial genera Limnohabitans, Hydrogenophaga...

  7. Polyamide desalination membrane characterization and surface modification to enhance fouling resistance.

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mukul M. (Univeristy of Texas at Austin, Austin, TX); Freeman, Benny D. (Univeristy of Texas at Austin, Austin, TX); Van Wagner, Elizabeth M. (Univeristy of Texas at Austin, Austin, TX); Hickner, Michael A. (Pennsylvania State University, University Park, PA); Altman, Susan Jeanne

    2010-08-01

    The market for polyamide desalination membranes is expected to continue to grow during the coming decades. Purification of alternative water sources will also be necessary to meet growing water demands. Purification of produced water, a byproduct of oil and gas production, is of interest due to its dual potential to provide water for beneficial use as well as to reduce wastewater disposal costs. However, current polyamide membranes are prone to fouling, which decreases water flux and shortens membrane lifetime. This research explored surface modification using poly(ethylene glycol) diglycidyl ether (PEGDE) to improve the fouling resistance of commercial polyamide membranes. Characterization of commercial polyamide membrane performance was a necessary first step before undertaking surface modification studies. Membrane performance was found to be sensitive to crossflow testing conditions. Concentration polarization and feed pH strongly influenced NaCl rejection, and the use of continuous feed filtration led to higher water flux and lower NaCl rejection than was observed for similar tests performed using unfiltered feed. Two commercial polyamide membranes, including one reverse osmosis and one nanofiltration membrane, were modified by grafting PEGDE to their surfaces. Two different PEG molecular weights (200 and 1000) and treatment concentrations (1% (w/w) and 15% (w/w)) were studied. Water flux decreased and NaCl rejection increased with PEGDE graft density ({micro}g/cm{sup 2}), although the largest changes were observed for low PEGDE graft densities. Surface properties including hydrophilicity, roughness and charge were minimally affected by surface modification. The fouling resistance of modified and unmodified membranes was compared in crossflow filtration studies using model foulant solutions consisting of either a charged surfactant or an oil in water emulsion containing n-decane and a charged surfactant. Several PEGDE-modified membranes demonstrated improved

  8. Inhibition of fouling by animal growth - a study using wood constituents

    International Nuclear Information System (INIS)

    Shukla, S.K.

    1983-01-01

    Inhibitory effects of constituents from Dalbergia retusa, Tectona grandis and Lophira procera heartwoods on fouling were studied in field and laboratory tests and compared with a copper paint. Lophira extract impaired fouling by barnacles and tubeworms, R-4 methoxydalbergione, obtusaquinone and lapachol didn't. Lapachol proved to be more effective than R-4 methoxydalbergione and obtusaquinone against Balanus improvisus in LD 50 -tests. Maximum inhibition of 45 Ca and 14 C uptake in the shell of Balanus improvisus was caused by lapachol. The same trend was observed in studies on alkaline phosphatase of mantel. (orig.) [de

  9. Thermodynamic analysis of effects of contact angle on interfacial interactions and its implications for membrane fouling control.

    Science.gov (United States)

    Chen, Jianrong; Shen, Liguo; Zhang, Meijia; Hong, Huachang; He, Yiming; Liao, Bao-Qiang; Lin, Hongjun

    2016-02-01

    Concept of hydrophobicity always fails to accurately assess the interfacial interaction and membrane fouling, which calls for reliable parameters for this purpose. In this study, effects of contact angle on interfacial interactions related to membrane fouling were investigated based on thermodynamic analysis. It was found that, total interaction energy between sludge foulants and membrane monotonically decreases and increases with water and glycerol contact angle, respectively, indicating that these two parameters can be reliable indicators predicting total interaction energy and membrane fouling. Membrane roughness decreases interaction strength for over 20 times, and effects of membrane roughness on membrane fouling should consider water and glycerol contact angle on membrane. It was revealed existence of a critical water and glycerol contact angle for a given membrane bioreactor. Meanwhile, diiodomethane contact angle has minor effect on the total interaction, and cannot be regarded as an effective indicator assessing interfacial interactions and membrane fouling. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Fouling deposition characteristic by variation of coal particle size and deposition temperature in DTF (Drop Tube Furnace)

    Energy Technology Data Exchange (ETDEWEB)

    Namkung, Hueon; Jeon, Youngshin; Kim, Hyungtaek [Ajou Univ., Suwon (Korea, Republic of). Div. of Energy Systems Research; Xu, Li-hua [IAE, Suwon (Korea, Republic of). Plant Engineering Center

    2013-07-01

    One of the major operation obstacles in gasification process is ash deposition phenomenon. In this investigation, experiment was carried out to examine coal fouling characteristics using a laminar DTF (Drop Tube Furnace) with variation of operating condition such as different coal size, and probe surface temperature. Four different samples of pulverized coal were injected into DTF under various conditions. The ash particles are deposited on probe by impacting and agglomerating action. Fouling grains are made of eutectic compound, which is made by reacting with acid minerals and alkali minerals, in EPMA (Electron Probe Micro-Analysis). And agglomeration area of fouling at top layer is wide more than it of middle and bottom layer. The major mineral factors of fouling phenomenon are Fe, Ca, and Mg. The deposition quantity of fouling increases with increasing particle size, high alkali mineral (Fe, Ca, and Mg) contents, and ash deposition temperature.

  11. Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products.

    Science.gov (United States)

    Duan, Liang; Tian, Zhiyong; Song, Yonghui; Jiang, Wei; Tian, Yuan; Li, Shan

    2015-01-01

    The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.

  12. Filtration behavior of casein glycomacropeptide (CGMP) in an enzymatic membrane reactor: fouling control by membrane selection and threshold flux operation

    DEFF Research Database (Denmark)

    Luo, Jianquan; Morthensen, Sofie Thage; Meyer, Anne S.

    2014-01-01

    . In this study, the filtration performance and fouling behavior during ultrafiltration (UF) of CGMP for the enzymatic production of 3′-sialyllactose were investigated. A 5kDa regenerated cellulose membrane with high anti-fouling performance, could retain CGMP well, permeate 3′-sialyllactose, and was found...... to be the most suitable membrane for this application. Low pH increased CGMP retention but produced more fouling. Higher agitation and lower CGMP concentration induced larger permeate flux and higher CGMP retention. Adsorption fouling and pore blocking by CGMP in/on membranes could be controlled by selecting...... a highly hydrophilic membrane with appropriate pore size. Operating under threshold flux could minimize the concentration polarization and cake/gel/scaling layers, but might not avoid irreversible fouling caused by adsorption and pore blocking. The effects of membrane properties, pH, agitation and CGMP...

  13. The Role of Difficulty in Identifying and Describing Feelings in Non-Suicidal Self-Injury Behavior (NSSI): Associations With Perceived Attachment Quality, Stressful Life Events, and Suicidal Ideation.

    Science.gov (United States)

    Cerutti, Rita; Zuffianò, Antonio; Spensieri, Valentina

    2018-01-01

    Objective: Core alexithymic features, such as the difficulty in identifying and describing feelings, are associated with poor attachment styles and emotional trauma, which influence the capacity to regulate affect. Additionally, emotional regulation has been found to be the most commonly identified function associated with non-suicidal self-injury behavior (NSSI) in adolescents as they attempt to modulate strong emotions. However, few studies have examined the link between difficulty in identifying and describing feelings (core components of alexithymia), NSSI behaviors, quality of attachment, life stressors and suicidal ideation in healthy early adolescents. Consequently, this study aims to investigate these constructs and the relationship among them in a large non-clinical sample of adolescents. Methods: Seven hundred and nine middle school students (50.4% males), aged 10-15 years ( M = 12.6; SD = 1.06) were involved in this study. In order to investigate the variables considered in the study, the following measures were administered: the Deliberate Self-Harm Inventory exploring non-suicidal self-injurious behaviors; the Alexithymia Questionnaire for Children examining difficulty in identifying and describing feelings; the Inventory of Parent and Peer Attachment assessing the quality of parental and peer attachment; the Life Stressor Checklist-Revised outlining stressful/traumatic events and the Children's Depression Inventory evaluating suicidal ideation. Results: We found significantly positive relationships among difficulty in identifying and describing feelings, NSSI behaviors, stressful events, and suicidal ideation. Data indicated a significant negative association of difficulty in identifying and describing feelings with quality of attachment to parents and peers. Further findings highlighted that difficulty in identifying and describing feelings significantly mediated the effect of quality of attachment (parent and peer) on NSSI and suicidal ideation

  14. Fouling assemblages associated with estuarine artificial reefs in new South Wales, Australia

    Directory of Open Access Journals (Sweden)

    Rob Mckenzie

    2011-01-01

    Full Text Available Previous studies examining the dynamics of succession on artificial reefs have predominantly focussed on fish communities and largely ignored the role of fouling assemblages in explaining the patterns of community structure associated with artificial reefs. The objective of this study was to record the development of epibiotic assemblages on three "design specific" (Reef Ball® estuarine artificial reefs systems located in Lake Macquarie, Botany Bay and St Georges Basin in New South Wales, Australia. Recruitment to the artificial reefs was relatively rapid with the majority of taxa identified over the two-year study period observed within the first year post-deployment. The artificial reefs in Lake Macquarie and St Georges Basin were characterised by low diversity with four and nine taxa recorded respectively in contrast to the sixteen taxa observed on the Botany Bay reefs. Results indicated no significant differences in percentage cover of taxa among reefs in either St Georges Basin or Lake Macquarie. In contrast, comparisons between individual Botany Bay reefs identified significant differences in the percentage cover of species between artificial reefs. Analysis of assemblage structure with reef age indicated discrete patterns among estuaries with an overall reduction in the percentage cover of filamentous turfing algae (FTA identified for all reef systems with an increase in reef age. Variations in environmental and physical conditions (turbidity, water flow, wave action and proximity to naturally occurring reef may have contributed to the observed differences in fouling assemblages between estuaries and between artificial reefs within Botany Bay.Estudos prévios que examinaram a dinâmica de sucessão em recifes artificiais foram focalizados nas comunidades de peixes, e sempre ignoraram o papel exercido pelos organismos incrustantes sobre a estruturação das comunidades associadas aos recifes artificiais. O presente estudo tem por objetivo

  15. Functionalized ultra-low fouling carboxy- and hydroxy-functional surface platforms: Functionalization capacity, biorecognition capability and resistance to fouling from undiluted biological media

    Czech Academy of Sciences Publication Activity Database

    Vaisocherová, Hana; Ševců, Veronika; Adam, Pavel; Špačková, Barbora; Hegnerová, Kateřina; de los Santos Pereira, Andres; Rodriguez-Emmenegger, Cesar; Riedel, Tomáš; Houska, Milan; Brynda, Eduard; Homola, Jiří

    2014-01-01

    Roč. 51, 15 January (2014), s. 150-157 ISSN 0956-5663 R&D Projects: GA ČR GBP205/12/G118; GA MŠk EE2.3.30.0029 Institutional support: RVO:67985882 ; RVO:61389013 Keywords : Low-fouling coatings * Polymer brushes * Surface chemistry Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; CD - Macromolecular Chemistry (UMCH-V) Impact factor: 6.409, year: 2014

  16. Quand la foule devient peuple … avec Léon Gambetta When the Crowd Becomes People… with Léon Gambetta

    Directory of Open Access Journals (Sweden)

    Aude Dontenwille-Gerbaud

    2010-09-01

    Full Text Available De 1870 à 1882 en France, la foule se montre un acteur essentiel dans la construction de la Troisième République. Non plus la foule qui prend la Bastille ou celle des barricades, mais la foule qui ovationne les grands leaders républicains qui ne peuvent faire sans elle. Si l’on veut bien considérer les discours « fondateurs » de Léon Gambetta, non pas seulement dans leur dimension textuelle, mais également dans leur profonde théâtralité, il convient d’analyser les grands rassemblements comme la naissance d’une modernité politique. La mémoire des foules révolutionnaires hante les esprits. Tout à la fois source vive d’inspiration pour le tribun ou d’inquiétude pour les conservateurs, les foules républicaines sont l’objet de toutes les attentions. Dans ce moment clef de l’histoire de France, le projet républicain entend les instruire, transformer en quelque sorte l’énergie issue de la foule « aveugle » en celle d’un peuple éclairé. La philosophie politique permet à l’historien d’analyser autrement ce moment fondateur. Les éclairages de Jürgen Habermas, Claude Lefort et Paul Ricoeur amènent à dépasser l’analyse classique d’une idée républicaine, pour évoquer la construction d’une société démocratique.From 1870 to 1882 in France, the crowd becomes a central actor in the construction of the Third Republic. The image of the crowd assaulting the Bastille or controlling the barricades is replaced by a crowd cheering the great republican leaders who rely on its support. A sound assessment of Léon Gambetta’s “founding” speeches needs to consider not only their textual content but also their theatrical dimension in order to analyse these events as forerunners of modern politics. As the memory of the revolutionary crowds is persisting in the first years of the Third Republic, the republican crowds catch the attention of actors from all sides of the political spectrum. In this key

  17. Attentional Mechanisms in Sports via Brain-Electrical Event-Related Potentials

    Science.gov (United States)

    Hack, Johannes; Memmert, Daniel; Rup, Andre

    2009-01-01

    In this study, we examined attention processes in complex, sport-specific decision-making tasks without interdependencies from anticipation. Psychophysiological and performance data recorded from advanced and intermediate level basketball referees were compared. Event-related potentials obtained while judging game situations in foul recognition…

  18. Contact angle studies on PDMS surfaces fouled by bovine serum albumin

    CSIR Research Space (South Africa)

    Windvoel, VT

    2010-01-01

    Full Text Available Polydimethylsiloxane (PDMS) has a hydrophobic surface, forming a contact angle of around 110º with deionised water. It is due to its hydrophobic nature that the elastomer is prone to bio-fouling, such as non-specific adsorption of biomaterials like...

  19. Development of a dynamic model for cleaning ultra filtration membranes fouled by surface water

    NARCIS (Netherlands)

    Zondervan, Edwin; Betlem, Ben H.L.; Roffel, Brian

    2007-01-01

    In this paper, a dynamic model for cleaning ultra filtration membranes fouled by surface water is proposed. A model that captures the dynamics well is valuable for the optimization of the cleaning process. The proposed model is based on component balances and contains three parameters that can be

  20. Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems

    KAUST Repository

    Rachman, Rinaldi; Ghaffour, NorEddine; Wali, F.; Amy, Gary L.

    2013-01-01

    Due to its simplicity, silt density index (SDI) is extensively used in reverse osmosis systems despite its limitations in predicting membrane fouling. Employing a reliable fouling index with good reproducibility and precision is necessary. The aim of this investigation is to assess the reliability of SDI in order to understand the reasons for the low level of precision and accuracy. Different commercial SDI membranes and feed water quality were used in this study. Results showed the existence of membrane properties' variation within manufacturers, which then causes a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role in SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. Moreover, turbidity-assisted SDI measurements along with determination of ultrafiltration permeate and clean water fouling potential, establish the indication of nonfouling-related phenomena involved on SDI measurement such as natural organic matter adsorption and hydrodynamic conditions that alters during filtration. Additionally, it was found that the latter affects the sensitivity of SDI by being represented by some portions of SDI values. © 2013 Desalination Publications.

  1. Fouling control mechanisms of demineralized water backwash: Reduction of charge screening and calcium bridging effects

    KAUST Repository

    Li, Sheng

    2011-12-01

    This paper investigates the impact of the ionic environment on the charge of colloidal natural organic matter (NOM) and ultrafiltration (UF) membranes (charge screening effect) and the calcium adsorption/bridging on new and fouled membranes (calcium bridging effect) by measuring the zeta potentials of membranes and colloidal NOM. Fouling experiments were conducted with natural water to determine whether the reduction of the charge screening effect and/or calcium bridging effect by backwashing with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent electrolytes. In addition, calcium also adsorbed onto the membranes, and consequently bridged colloidal NOM and membranes via binding with functional groups. The charge screening effect could be eliminated by flushing NOM and membranes with demineralized water, since a cation-free environment was established. However, only a limited amount of the calcium bridging connection was removed with demineralized water backwashes, so the calcium bridging effect mostly could not be eliminated. As demineralized water backwash was found to be effective in fouling control, it can be concluded that the reduction of the charge screening is the dominant mechanism for this. © 2011 Elsevier Ltd.

  2. Influence of feed composition and membrane fouling on forward osmosis performance

    DEFF Research Database (Denmark)

    Schneider, Carina; Sathyadev Rajmohan, Rajath; Zarebska, Agata

    2016-01-01

    at the beginning and at the end of each experiment, regarding their total solids (TS), volatile solids (VS), total suspended solids (TSS), particle size distribution, Total Kjeldahl Nitrogen (TKN), Total available nitrogen (TAN), total organic carbon (TOC) and total phosphate (TP). The fouled membranes were...

  3. Integrated approach to characterize fouling on a flat sheet membrane gravity driven submerged membrane bioreactor

    KAUST Repository

    Fortunato, Luca

    2016-10-07

    Fouling in membrane bioreactors (MBR) is acknowledged to be complex and unclear. An integrated characterization methodology was employed in this study to understand the fouling on a gravity-driven submerged MBR (GD-SMBR). It involved the use of different analytical tools, including optical coherence tomography (OCT), liquid chromatography with organic carbon detection (LC-OCD), total organic carbon (TOC), flow cytometer (FCM), adenosine triphosphate analysis (ATP) and scanning electron microscopy (SEM). The three-dimensional (3D) biomass morphology was acquired in a real-time through non-destructive and in situ OCT scanning of 75% of the total membrane surface directly in the tank. Results showed that the biomass layer was homogeneously distributed on the membrane surface. The amount of biomass was selectively linked with final destructive autopsy techniques. The LC-OCD analysis indicated the abundance of low molecular weight (LMW) organics in the fouling composition. Three different SEM techniques were applied to investigate the detailed fouling morphology on the membrane. © 2016 Elsevier Ltd

  4. Fouling control mechanisms of demineralized water backwash: Reduction of charge screening and calcium bridging effects

    KAUST Repository

    Li, Sheng; Heijman, Bas G J; Verberk, J. Q J C; Le-Clech, Pierre; Lu, Jie; Kemperman, Antoine J B; Amy, Gary L.; Van Dijk, Johannis C.

    2011-01-01

    with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent

  5. Cake layers and long filtration times protect ceramic micro-filtration membranes for fouling

    NARCIS (Netherlands)

    Lu, J.

    2013-01-01

    The objective of this research was to decrease membrane fouling of a ceramic microfiltration system and at the same time increase the recovery. A conventional operation in micro- and ultrafiltration is an in-line coagulation and a frequent hydraulic backwash. The idea about these frequent backwashes

  6. Assessment of silt density index (SDI) as fouling propensity parameter in reverse osmosis (RO) desalination systems

    KAUST Repository

    Rachman, Rinaldi

    2013-01-01

    Due to its simplicity, silt density index (SDI) is extensively used in reverse osmosis systems despite its limitations in predicting membrane fouling. Employing a reliable fouling index with good reproducibility and precision is necessary. The aim of this investigation is to assess the reliability of SDI in order to understand the reasons for the low level of precision and accuracy. Different commercial SDI membranes and feed water quality were used in this study. Results showed the existence of membrane properties\\' variation within manufacturers, which then causes a lack of accuracy in fouling risk estimation. The nature of particles during SDI filtration provides information that particle concentration and size play a significant role in SDI quantification with substantial representation given by particles with size close to membrane nominal pore size. Moreover, turbidity-assisted SDI measurements along with determination of ultrafiltration permeate and clean water fouling potential, establish the indication of nonfouling-related phenomena involved on SDI measurement such as natural organic matter adsorption and hydrodynamic conditions that alters during filtration. Additionally, it was found that the latter affects the sensitivity of SDI by being represented by some portions of SDI values. © 2013 Desalination Publications.

  7. Superheater fouling in a BFB boiler firing wood-based fuel blends

    NARCIS (Netherlands)

    Stam, A.F.; Haasnoot, K.; Brem, Gerrit

    2014-01-01

    Four different fuel blends have been fired in a 28 MWel BFB. Wood pellets (test 0) were not problematic for about ten years, contrary to a mixture of demolition wood, wood cuttings, compost overflow, paper sludge and roadside grass (test 1) which caused excessive fouling at a superheater bundle

  8. Carbohydrade metabolism in suspended and attached cells of marine fouling diatom, Navicula sp.

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Sawant, S.S.; Garg, A.; Wagh, A.B.

    A marine fouling diatom, @iNavicula@@ sp. was cultured in the laboratory under 12-hour light : 12-hour dark conditions. Cells in suspension and attached to the flask walls were analyzed for chlorophyll a, cell organic carbon, total cell carbohydrate...

  9. Minimizing fouling at hydrogenated conical-tip carbon electrodes during dopamine detection in vivo.

    Science.gov (United States)

    Chandra, Shaneel; Miller, Anthony D; Bendavid, Avi; Martin, Philip J; Wong, Danny K Y

    2014-03-04

    In this paper, physically small conical-tip carbon electrodes (∼2-5 μm diameter and ∼4 μm axial length) were hydrogenated to develop a probe capable of withstanding fouling during dopamine detection in vivo. Upon hydrogenation, the resultant hydrophobic sp(3) carbon surface deters adsorption of amphiphilic lipids, proteins, and peptides present in extracellular fluid and hence minimizes electrode fouling. These hydrogenated carbon electrodes showed a 35% decrease in sensitivity but little change in the limit of detection for dopamine over a 7-day incubation in a synthetic laboratory solution containing 1.0% (v/v) caproic acid (a lipid), 0.1% (w/v) bovine serum albumin and 0.01% (w/v) cytochrome C (both are proteins), and 0.002% (w/v) human fibrinopeptide B (a peptide). Subsequently, during dopamine detection in vivo, over 70% of the dopamine oxidation current remained after the first 30 min of a 60-min experiment, and at least 50% remained over the next half-period at the hydrogenated carbon electrodes. On the basis of these results, an initial average electrode surface fouling rate of 1.2% min(-1) was estimated, which gradually declined to 0.7% min(-1). These results support minimal fouling at hydrogenated carbon electrodes applied to dopamine detection in vivo.

  10. Characterization of soluble microbial products and their fouling impacts in membrane bioreactors

    KAUST Repository

    Jiang, Tao; Kennedy, Maria Dolores; Schepper, Veerle D.; Nam, Seongnam; Nopens, Ingmar; Vanrolleghem, Peter A.; Amy, Gary L.

    2010-01-01

    Membrane bioreactor (MBR) fouling is not only influenced by the soluble microbial products (SMP) concentration but by their characteristics. Experiments of separate producing biomass associated products (BAP) and utilization associated products (UAP) allowed the separation of BAP and UAP effects from sludge water (SW). Thus, filtration of individual SMP components and further characterization becomes possible. Unstirred cell filtration was used to study fouling mechanisms and liquid chromatography-organic carbon detection (LC-OCD) and fluorescence excitation-emission matrix (EEM) were used to characterize the foulant. Generally, the SMP exhibiting characteristics of higher molecular weight, greater hydrophilicity and a more reduced state showed a higher retention percentage. However, the higher retention does not always yield higher fouling effects. The UAP filtration showed the highest specific cake resistance and pore blocking resistance attributed to their higher percentage of low molecular weight molecules, although their retention percentage was lower than the SW and BAP filtration. The UAP produced in the cell proliferation phase appeared to have the highest fouling potential. © 2010 American Chemical Society.

  11. Fouling Characteristics of Dissolved Organic Matter in Papermaking Process Water on Polyethersulfone Ultrafiltration Membranes

    Directory of Open Access Journals (Sweden)

    Wenpeng Su

    2015-07-01

    Full Text Available In the papermaking industry, closure of process water (whitewater circuits has been used to reduce fresh water consumption. Membrane separation technology has potential for use in treating process water for recirculation. The purpose of this study was to reveal the fouling characteristics of a polyethersulfone (PES ultrafiltration membrane caused by dissolved organic matter (DOM in process water. Ultrafiltration membranes (UF and DAX ion exchange resins were applied to characterize the molecular weight (MW and hydrophilicity distribution of DOM. The interactions between various fractions of DOM and a PES ultrafiltration membrane were investigated. The membrane fouling characteristics were elucidated by examining the filtration resistances and linearized Herman’s blocking models. The results demonstrated that the membrane was fouled significantly by much of the MW distribution. The membrane was fouled more significantly by the low MW fraction rather than the high MW fraction. The filtration resistances and the fitted equation of Hermia’s laws indicated that hydrophilic organics were the main foulants. The hydrophilic organics partially block the membrane pores and form intermediate blocking, reducing the effective filtration area, while the hydrophobic organics form a gel layer or cake on the surface of the membrane.

  12. A novel surface cleaning method for chemical removal of fouling lead layer from chromium surfaces

    International Nuclear Information System (INIS)

    Gholivand, Kh.; Khosravi, M.; Hosseini, S.G.; Fathollahi, M.

    2010-01-01

    Most products especially metallic surfaces require cleaning treatment to remove surface contaminations that remain after processing or usage. Lead fouling is a general problem which arises from lead fouling on the chromium surfaces of bores and other interior parts of systems which have interaction with metallic lead in high temperatures and pressures. In this study, a novel chemical solution was introduced as a cleaner reagent for removing metallic lead pollution, as a fouling metal, from chromium surfaces. The cleaner aqueous solution contains hydrogen peroxide (H 2 O 2 ) as oxidizing agent of lead layer on the chromium surface and acetic acid (CH 3 COOH) as chelating agent of lead ions. The effect of some experimental parameters such as acetic acid concentration, hydrogen peroxide concentration and temperature of the cleaner solution during the operation on the efficiency of lead cleaning procedure was investigated. The results of scanning electron microscopy (SEM) showed that using this procedure, the lead pollution layer could be completely removed from real chromium surfaces without corrosion of the original surface. Finally, the optimum conditions for the complete and fast removing of lead pollution layer from chromium surfaces were proposed. The experimental results showed that at the optimum condition (acetic acid concentration 28% (V/V), hydrogen peroxide 8% (V/V) and temperature 35 deg. C), only 15-min time is needed for complete removal of 3 g fouling lead from a chromium surface.

  13. Characterization of soluble microbial products and their fouling impacts in membrane bioreactors

    KAUST Repository

    Jiang, Tao

    2010-09-01

    Membrane bioreactor (MBR) fouling is not only influenced by the soluble microbial products (SMP) concentration but by their characteristics. Experiments of separate producing biomass associated products (BAP) and utilization associated products (UAP) allowed the separation of BAP and UAP effects from sludge water (SW). Thus, filtration of individual SMP components and further characterization becomes possible. Unstirred cell filtration was used to study fouling mechanisms and liquid chromatography-organic carbon detection (LC-OCD) and fluorescence excitation-emission matrix (EEM) were used to characterize the foulant. Generally, the SMP exhibiting characteristics of higher molecular weight, greater hydrophilicity and a more reduced state showed a higher retention percentage. However, the higher retention does not always yield higher fouling effects. The UAP filtration showed the highest specific cake resistance and pore blocking resistance attributed to their higher percentage of low molecular weight molecules, although their retention percentage was lower than the SW and BAP filtration. The UAP produced in the cell proliferation phase appeared to have the highest fouling potential. © 2010 American Chemical Society.

  14. Investigation of severe UF membrane fouling induced by three marine algal species

    KAUST Repository

    Merle, Tony; Dramas, Laure; Gutierrez, Leonardo; Garcia-Molina, Veronica; Croue, Jean-Philippe

    2016-01-01

    Index (HIFI) was correlated to their biopolymer content but this correlation is specific for each species. Solution pre-filtration through a 1.2 μm membrane proved that cells and particulate algal organic matter (p-AOM) considerably contribute to fouling

  15. Light scattering evidence of selective protein fouling on biocompatible block copolymer micelles

    Czech Academy of Sciences Publication Activity Database

    Giacomelli, F. C.; Štěpánek, Petr; Schmidt, V.; Jäger, Eliezer; Jäger, Alessandro; Giacomelli, C.

    2012-01-01

    Roč. 4, č. 15 (2012), s. 4504-4514 ISSN 2040-3364 R&D Projects: GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505 Keywords : copolymer micelles * protein fouling * light scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.233, year: 2012

  16. Prediction of Agglomeration, Fouling, and Corrosion Tendency of Fuels in CFB Co-Combustion

    Science.gov (United States)

    Barišć, Vesna; Zabetta, Edgardo Coda; Sarkki, Juha

    Prediction of agglomeration, fouling, and corrosion tendency of fuels is essential to the design of any CFB boiler. During the years, tools have been successfully developed at Foster Wheeler to help with such predictions for the most commercial fuels. However, changes in fuel market and the ever-growing demand for co-combustion capabilities pose a continuous need for development. This paper presents results from recently upgraded models used at Foster Wheeler to predict agglomeration, fouling, and corrosion tendency of a variety of fuels and mixtures. The models, subject of this paper, are semi-empirical computer tools that combine the theoretical basics of agglomeration/fouling/corrosion phenomena with empirical correlations. Correlations are derived from Foster Wheeler's experience in fluidized beds, including nearly 10,000 fuel samples and over 1,000 tests in about 150 CFB units. In these models, fuels are evaluated based on their classification, their chemical and physical properties by standard analyses (proximate, ultimate, fuel ash composition, etc.;.) alongside with Foster Wheeler own characterization methods. Mixtures are then evaluated taking into account the component fuels. This paper presents the predictive capabilities of the agglomeration/fouling/corrosion probability models for selected fuels and mixtures fired in full-scale. The selected fuels include coals and different types of biomass. The models are capable to predict the behavior of most fuels and mixtures, but also offer possibilities for further improvements.

  17. Succession and physiological health of freshwater microalgal fouling in a Tasmanian hydropower canal.

    Science.gov (United States)

    Perkins, Kathryn J; Andrewartha, Jessica M; McMinn, Andrew; Cook, Suellen S; Hallegraeff, Gustaaf M

    2010-08-01

    Freshwater microalgal biofouling in hydropower canals in Tarraleah, Tasmania, is dominated by a single diatom species, Gomphonema tarraleahae. The microfouling community is under investigation with the aim of reducing its impact on electricity generation. Species succession was investigated using removable glass slides. Fouled slides were examined microscopically and for chlorophyll a biomass. Chl a biomass increased steeply after 8 weeks (0.09-0.87 mg m(-2)), but increased much earlier on slides surrounded by a biofouled inoculum. Succession began with low profile diatoms such as Tabellaria flocculosa, progressing to stalked diatoms such as Gomphonema spp. and Cymbella aspera. Few chlorophytes and no filamentous algae were present. Pulse amplitude modulated fluorometry was used to measure the physiological health of fouling on the canal wall. Maximum quantum yield (F(v)/F(m)) measurements were consistently <0.18, indicating that the fouling mat consisted of dead or dying algae. The succession and physiological health of cells in the fouling community has broad implications for mitigation techniques used.

  18. Airfoil-shaped micro-mixers for reducing fouling on membrane surfaces

    Science.gov (United States)

    Ho, Clifford K; Altman, Susan J; Clem, Paul G; Hibbs, Michael; Cook, Adam W

    2012-10-23

    An array of airfoil-shaped micro-mixers that enhances fluid mixing within permeable membrane channels, such as used in reverse-osmosis filtration units, while minimizing additional pressure drop. The enhanced mixing reduces fouling of the membrane surfaces. The airfoil-shaped micro-mixer can also be coated with or comprised of biofouling-resistant (biocidal/germicidal) ingredients.

  19. Integrated approach to characterize fouling on a flat sheet membrane gravity driven submerged membrane bioreactor.

    Science.gov (United States)

    Fortunato, Luca; Jeong, Sanghyun; Wang, Yiran; Behzad, Ali R; Leiknes, TorOve

    2016-12-01

    Fouling in membrane bioreactors (MBR) is acknowledged to be complex and unclear. An integrated characterization methodology was employed in this study to understand the fouling on a gravity-driven submerged MBR (GD-SMBR). It involved the use of different analytical tools, including optical coherence tomography (OCT), liquid chromatography with organic carbon detection (LC-OCD), total organic carbon (TOC), flow cytometer (FCM), adenosine triphosphate analysis (ATP) and scanning electron microscopy (SEM). The three-dimensional (3D) biomass morphology was acquired in a real-time through non-destructive and in situ OCT scanning of 75% of the total membrane surface directly in the tank. Results showed that the biomass layer was homogeneously distributed on the membrane surface. The amount of biomass was selectively linked with final destructive autopsy techniques. The LC-OCD analysis indicated the abundance of low molecular weight (LMW) organics in the fouling composition. Three different SEM techniques were applied to investigate the detailed fouling morphology on the membrane. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Fouling in gravity driven Point-of-Use drinking water treatment systems

    NARCIS (Netherlands)

    Chawla, Charu; Zwijnenburg, A.; Kemperman, Antonius J.B.; Nijmeijer, Dorothea C.

    2017-01-01

    This paper describes fouling in simulated Point-of-Use (PoU) systems based on low pressure hollow fiber ultrafiltration membranes. Various operational configurations such as recirculation of feed, discontinuous vs. continuous filtration, and inside/out vs. outside/in were compared to study their

  1. Contribution to the investigation concerning the fouling and washing of steam generators

    International Nuclear Information System (INIS)

    Dijoux, M.; Vito, S. de; Millet, L.

    2002-01-01

    Steam generator secondary side tube deposits affect optimal operation of the nuclear power plants. Stress corrosion cracking (ODSCC) occurs under deposits located in confined areas, in particular the tube - tube support plates crevices for 600-MA tubes. Fouling on free span of the bundle leads to thermal transfer inhibition for all type of tube alloys. Flow accelerated corrosion (FAC) and general corrosion of the feed water train components, depending on the chemical treatment applied, are the mainly responsible for the secondary fouling. An appropriate maintenance requires a good knowledge of deposits. In this context, a study program on deposits has been started covering the following points: - Spatial distribution and mass determination by Eddy Current Testing (ECT); - Composition by chemical analysis; - Characterization by micrographic analysis; - Modelling of deposition by computer code; and - Effects on thermal transfer and fouling factor calculation. These examinations bring a best understanding of fouling mechanisms and allow to act on influential parameters: chemical secondary treatment, selection of materials in the feed water train, and pollution ingress reduction. They permit to evaluate the interest to schedule cleaning operations such as lancing or chemical cleaning. (authors)

  2. Differential Adverse Event Profiles Associated with BCG as a Preventive Tuberculosis Vaccine or Therapeutic Bladder Cancer Vaccine Identified by Comparative Ontology-Based VAERS and Literature Meta-Analysis.

    Directory of Open Access Journals (Sweden)

    Jiangan Xie

    Full Text Available M. bovis strain Bacillus Calmette-Guérin (BCG has been the only licensed live attenuated vaccine against tuberculosis (TB for nearly one century and has also been approved as a therapeutic vaccine for bladder cancer treatment since 1990. During its long time usage, different adverse events (AEs have been reported. However, the AEs associated with the BCG preventive TB vaccine and therapeutic cancer vaccine have not been systematically compared. In this study, we systematically collected various BCG AE data mined from the US VAERS database and PubMed literature reports, identified statistically significant BCG-associated AEs, and ontologically classified and compared these AEs related to these two types of BCG vaccine. From 397 VAERS BCG AE case reports, we identified 64 AEs statistically significantly associated with the BCG TB vaccine and 14 AEs with the BCG cancer vaccine. Our meta-analysis of 41 peer-reviewed journal reports identified 48 AEs associated with the BCG TB vaccine and 43 AEs associated with the BCG cancer vaccine. Among all identified AEs from VAERS and literature reports, 25 AEs belong to serious AEs. The Ontology of Adverse Events (OAE-based ontological hierarchical analysis indicated that the AEs associated with the BCG TB vaccine were enriched in immune system (e.g., lymphadenopathy and lymphadenitis, skin (e.g., skin ulceration and cyanosis, and respiratory system (e.g., cough and pneumonia; in contrast, the AEs associated with the BCG cancer vaccine mainly occurred in the urinary system (e.g., dysuria, pollakiuria, and hematuria. With these distinct AE profiles detected, this study also discovered three AEs (i.e., chills, pneumonia, and C-reactive protein increased shared by the BCG TB vaccine and bladder cancer vaccine. Furthermore, our deep investigation of 24 BCG-associated death cases from VAERS identified the important effects of age, vaccine co-administration, and immunosuppressive status on the final BCG

  3. Inefficacy of osmotic backwash induced by sodium chloride salt solution in controlling SWRO membrane fouling

    Science.gov (United States)

    Farooque, A. Mohammed; Al-Jeshi, Subhi; Saeed, Mohamed O.; Alreweli, Ali

    2014-12-01

    A study was conducted to evaluate the efficacy of osmotic backwash induced by high salt (NaCl) concentration solution on feed side of seawater reverse osmosis (SWRO) membranes, online and offline, in controlling membrane fouling and therefore minimizing/eliminating the need for chemical cleaning. SWRO membranes were deliberately fouled by feeding seawater from an open intake located on the Arabian Gulf Coast without dosing chemicals. The fouled membranes were subjected to offline cleaning with the salt solution of up to 25 % concentration. Despite the partial removal of foulants from the membrane surface, SWRO membrane performance could not be restored, indicating the ineffectiveness of osmotic backwash in aiding offline salt cleaning. Similarly, online osmotic backwash was found to be not only ineffective in removing foulants from membrane surfaces but actually increased the fouling rate, as indicated by faster fouling rates compared to other cases. Although the driving force required for the osmotic backwash existed, the generated back flow proved to be insufficient to detach foulants from membrane surfaces. During the study period, the average SWRO membrane flux was maintained between 19 and 23 LMH, whereas the average generated back flow flux by high salt concentration solution was only 11 LMH, which was not adequate to remove foulants from membrane surfaces. Moreover, it seems that the membrane configuration as well as inherent microstructure of SWRO membrane places certain constraints on the osmotic backwash process and renders osmotic backwash ineffective in tackling SWRO membrane fouling. Hence, chemical cleaning is essential to restore SWRO membrane performance whenever fouling occurs, and the use of highly concentrated salt solution does not have any significant benefit. Membrane autopsy revealed only an insignificant accumulation of biofouling layer despite the absence of disinfection. However, it was shown that culturable biofilm bacteria species

  4. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: Roles played by stabilization surfactants of oil droplets

    KAUST Repository

    Lu, Dongwei

    2015-04-07

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater. © 2015 American Chemical Society.

  5. Hydrophilic Fe2O3 dynamic membrane mitigating fouling of support ceramic membrane in ultrafiltration of oil/water emulsion

    KAUST Repository

    Lu, Dongwei; Cheng, Wei; Zhang, Tao; Lu, Xinglin; Liu, Qianliang; Jiang, Jin; Ma, Jun

    2016-01-01

    Oil/water (O/W) emulsion is daily produced and difficult to be treated effectively. Ceramic membrane ultrafiltration is one of reliable processes for the treatment of O/W emulsion, yet still hindered by membrane fouling. In this study, two types of Fe2O3 dynamic membranes (i.e., pre-coated dynamic membrane and self-forming dynamic membrane) were prepared to mitigate the fouling of support ceramic membrane in O/W emulsion treatment. Pre-coated dynamic membrane (DM) significantly reduced the fouling of ceramic membrane (i.e., 10% increase of flux recovery rate), while self-forming dynamic membrane aggravated ceramic membrane fouling (i.e., 8.6% decrease of flux recovery rate) after four filtration cycles. A possible fouling mechanism was proposed to explain this phenomenon, which was then confirmed by optical images of fouled membranes and the analysis of COD rejection. In addition, the cleaning efficiency of composite membranes (i.e., Fe2O3 dynamic membrane and support ceramic membrane) was enhanced by substitution of alkalescent water backwash for deionized water backwash. The possible reason for this enhancement was also explained. Our result suggests that pre-coated Fe2O3 dynamic membrane with alkalescent water backwash can be a promising technology to reduce the fouling of ceramic membrane and enhance membrane cleaning efficiency in the treatment of oily wastewater.

  6. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: roles played by stabilization surfactants of oil droplets.

    Science.gov (United States)

    Lu, Dongwei; Zhang, Tao; Ma, Jun

    2015-04-07

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater.

  7. The Application and Research of the GA-BP Neural Network Algorithm in the MBR Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Chunqing Li

    2014-01-01

    Full Text Available It is one of the important issues in the field of today's sewage treatment of researching the MBR membrane flux prediction for membrane fouling. Firstly this paper used the principal component analysis method to achieve dimensionality and correlation of input variables and obtained the three major factors affecting membrane fouling most obvious: MLSS, total resistance, and operating pressure. Then it used the BP neural network to establish the system model of the MBR intelligent simulation, the relationship between three parameters, and membrane flux characterization of the degree of membrane fouling, because the BP neural network has slow training speed, is sensitive to the initial weights and the threshold, is easy to fall into local minimum points, and so on. So this paper used genetic algorithm to optimize the initial weights and the threshold of BP neural network and established the membrane fouling prediction model based on GA-BP network. As this research had shown, under the same conditions, the BP network model optimized by GA of MBR membrane fouling is better than that not optimized for prediction effect of membrane flux. It demonstrates that the GA-BP network model of MBR membrane fouling is more suitable for simulation of MBR membrane fouling process, comparing with the BP network.

  8. Hydrophilic Fe2O3 dynamic membrane mitigating fouling of support ceramic membrane in ultrafiltration of oil/water emulsion

    KAUST Repository

    Lu, Dongwei

    2016-03-17

    Oil/water (O/W) emulsion is daily produced and difficult to be treated effectively. Ceramic membrane ultrafiltration is one of reliable processes for the treatment of O/W emulsion, yet still hindered by membrane fouling. In this study, two types of Fe2O3 dynamic membranes (i.e., pre-coated dynamic membrane and self-forming dynamic membrane) were prepared to mitigate the fouling of support ceramic membrane in O/W emulsion treatment. Pre-coated dynamic membrane (DM) significantly reduced the fouling of ceramic membrane (i.e., 10% increase of flux recovery rate), while self-forming dynamic membrane aggravated ceramic membrane fouling (i.e., 8.6% decrease of flux recovery rate) after four filtration cycles. A possible fouling mechanism was proposed to explain this phenomenon, which was then confirmed by optical images of fouled membranes and the analysis of COD rejection. In addition, the cleaning efficiency of composite membranes (i.e., Fe2O3 dynamic membrane and support ceramic membrane) was enhanced by substitution of alkalescent water backwash for deionized water backwash. The possible reason for this enhancement was also explained. Our result suggests that pre-coated Fe2O3 dynamic membrane with alkalescent water backwash can be a promising technology to reduce the fouling of ceramic membrane and enhance membrane cleaning efficiency in the treatment of oily wastewater.

  9. INVESTIGATION OF FOULING DEPOSIT FORMATION DURING PASTEURIZATION OF CHILI SAUCE BY USING LAB-SCALE CONCENTRIC TUBE-PASTEURIZER

    Directory of Open Access Journals (Sweden)

    NUR ATIKA ALI

    2014-06-01

    Full Text Available This paper investigates the characteristics of fouling deposits obtained from chilli sauce pasteurization. A lab-scale concentric tube-pasteurizer was used to pasteurize the chilli sauce at 0.712 kg/min and 90±5°C. It was operated for 3 hours. Temperature changes were recorded during pasteurization and the data was used to plot the heat transfer profile and the fouling resistance profile. The thickness of the fouling deposit was also measured and the image was taken for every hour. The fouling deposit was collected at every hour to test its stickiness, hardness and flow behaviour. Proximate analysis was also performed and it shows that the fouling deposit from the chilli sauce is categorized as carbohydrate-based fouling deposits. Activation energy of chilli sauce is 7049.4 J.mole-1 which shows a greater effect of temperature on the viscosity. The hardness, stickiness of fouling deposit and the heat resistance increases as the chilli sauce continuously flows inside the heat exchanger.

  10. Contribution of assimilable organic carbon to biological fouling in seawater reverse osmosis membrane treatment.

    Science.gov (United States)

    Weinrich, Lauren; LeChevallier, Mark; Haas, Charles N

    2016-09-15

    Biological fouling occurs on RO membranes when bacteria and nutrients are present in conditions that are conducive to growth and proliferation of the bacteria. Controlling microbial growth on the membranes is typically limited to biocide application (i.e., disinfectants) in seawater RO plants. However, biological growth and subsequent fouling has not been well-managed. Pretreatment has not been focused on nutrient limitation. This project used a biological assay, the assimilable organic carbon (AOC) test to evaluate pretreatment effects on the nutrient supply. The AOC test provided a useful surrogate measurement for the biodegradability or biofouling potential of RO feed water. Biofouling observed in controlled conditions at the bench- and pilot-scale resulted in statistically significant correlations between AOC and the operational effects caused by biofouling. Membrane fouling rates are observed through operational changes over time such as increased differential pressure between the membrane feed and concentrate locations and decreased permeate flux through the membrane. In full scale plants there were strong correlations when AOC was used as a predictor variable for increased differential pressure (0.28-0.55 bar from September-December 2012) and decreased specific flux (1.40 L per hour/(m(2) · bar)). Increased differential pressure was associated with RO membrane biological fouling when the median AOC was 50 μg/L during pilot testing. Conditions were also evaluated at the bench-scale using a flat sheet RO membrane. In a comparison test using 30 and 1000 μg/L AOC, fouling was detected on more portions of the membrane when AOC was higher. Biofilm and bacterial deposits were apparent from scanning electron microscope imaging and biomass measurements using ATP. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Flux Enhancement in Crossflow Membrane Filtration: Fouling and It's Minimization by Flow Reversal. Final Report

    International Nuclear Information System (INIS)

    Shamsuddin Ilias

    2005-01-01

    Fouling problems are perhaps the single most important reason for relatively slow acceptance of ultrafiltration in many areas of chemical and biological processing. To overcome the losses in permeate flux associated with concentration polarization and fouling in cross flow membrane filtration, we investigated the concept of flow reversal as a method to enhance membrane flux in ultrafiltration. Conceptually, flow reversal prevents the formation of stable hydrodynamic and concentration boundary layers at or near the membrane surface. Further more, periodic reversal of the flow direction of the feed stream at the membrane surface results in prevention and mitigation of membrane fouling. Consequently, these advantages are expected to enhance membrane flux significantly. A crossflow membrane filtration unit was designed and built to test the concept of periodic flow reversal for flux enhancement. The essential elements of the system include a crossflow hollow fiber membrane module integrated with a two-way valve to direct the feed flow directions. The two-way valve is controlled by a controller-timer for periodic reversal of flow of feed stream. Another important feature of the system is that with changing feed flow direction, the permeate flow direction is also changed to maintain countercurrent feed and permeate flows for enhanced mass transfer driving force (concentration difference). Three feed solutions (Bovine serum albumin (BSA), apple juice and citrus fruit pectin) were studied in crossflow membrane filtration. These solutes are well-known in membrane filtration for their fouling and concentration polarization potentials. Laboratory-scale tests on a hollow-fiber ultrafiltration membrane module using each of the feed solutes show that under flow reversal conditions, the permeate flux is significantly enhanced when compared with the conventional unidirectional flow. The flux enhancement is dramatic (by an order of magnitude) with increased feed concentration and

  12. A semi-empirical model for the prediction of fouling in railway ballast using GPR

    Science.gov (United States)

    Bianchini Ciampoli, Luca; Tosti, Fabio; Benedetto, Andrea; Alani, Amir M.; Loizos, Andreas; D'Amico, Fabrizio; Calvi, Alessandro

    2016-04-01

    The first step in the planning for a renewal of a railway network consists in gathering information, as effectively as possible, about the state of the railway tracks. Nowadays, this activity is mostly carried out by digging trenches at regular intervals along the whole network, to evaluate both geometrical and geotechnical properties of the railway track bed. This involves issues, mainly concerning the invasiveness of the operations, the impacts on the rail traffic, the high costs, and the low levels of significance concerning such discrete data set. Ground-penetrating radar (GPR) can represent a useful technique for overstepping these issues, as it can be directly mounted onto a train crossing the railway, and collect continuous information along the network. This study is aimed at defining an empirical model for the prediction of fouling in railway ballast, by using GPR. With this purpose, a thorough laboratory campaign was implemented within the facilities of Roma Tre University. In more details, a 1.47 m long × 1.47 m wide × 0.48 m height plexiglass framework, accounting for the domain of investigation, was laid over a perfect electric conductor, and filled up with several configuration of railway ballast and fouling material (clayey sand), thereby representing different levels of fouling. Then, the set of fouling configurations was surveyed with several GPR systems. In particular, a ground-coupled multi-channel radar (600 MHz and 1600 MHz center frequency antennas) and three air-launched radar systems (1000 MHz and 2000 MHz center frequency antennas) were employed for surveying the materials. By observing the results both in terms of time and frequency domains, interesting insights are highlighted and an empirical model, relating in particular the shape of the frequency spectrum of the signal and the percentage of fouling characterizing the surveyed material, is finally proposed. Acknowledgement The Authors thank COST, for funding the Action TU1208 "Civil

  13. Strategies to control zebra mussel fouling at Kewaunee Nuclear Power Plant

    International Nuclear Information System (INIS)

    Schwartz, D.; Kasper, J.R.; Pisani, W.

    1992-01-01

    The zebra mussel, Dreissena polymorpha, is currently infesting the Great Lakes. First discovered in Lake St. Clair, it is now widespread in Lakes Erie and Ontario. The initial efforts relating to zebra mussel control at Wisconsin Public Service Corporation's (WPSC) Kewaunee Nuclear Power Plant (KNPP) precipitated from the Nuclear Regulatory Commission's (NRC) Generic Letter 89-13 regarding fouling of service water (SW) systems at nuclear power plants. In the summer of 1990, Stone and Webster Engineering Corporation (Stone and Webster) was contracted to perform an evaluation of known problems within the SW system. The purposes of the study were to evaluate the actual and potential magnitude of these problems, to evaluate corrective actions to resolve the problems, and to prepare recommendations which would adequately address the issues. Two of the recommendations of this study were to continue a zebra mussel monitoring program which WPSC had already implemented and to evaluate various biocide injection programs should one be required for zebra mussel control. The concern of utilities operating power stations which use waters infested with zebra mussels as their source of cooling and/or makeup water is that mussels (both adults and veligers) will enter plant water systems and foul piping and heat exchangers. This type of fouling can restrict flow through piping, process equipment, and heat exchangers. This type of fouling can restrict flow through piping, process equipment, and heat exchangers, thereby increasing head losses and reducing heat transfer capabilities. The greatest concern in that fouling of this type is within safety-related piping and equipment that are components of service water systems at nuclear power plants

  14. Special Experts Meeting: Identifying and Overcoming Barriers to the Effective Consideration of Human and Organizational Factors in Event Analysis and Root Cause Analysis. Nuclear Energy Agency / Working Group on Human and Organizational Factors

    International Nuclear Information System (INIS)

    2011-01-01

    The main mission of the Nuclear Energy Agency (NEA) Working Group on Human and Organisational Factors (WGHOF) is to improve the understanding and treatment of human and organisational factors (HOF) within the nuclear industry in order to support the continued safety performance of nuclear installations and improve the effectiveness of regulatory practices in member countries. WGHOF developed a CSNI (Committee on the Safety of Nuclear Installations) Activity Proposal Sheet (CAPS) outlining the work and milestones necessary towards achieving the following objectives: - Identify barriers to analyzing and correctly identifying the Human and Organisational Factors (HOF) causes of events; - Identify barriers to implementing lessons learned from these analyses; and - Develop recommendations for overcoming these barriers to: improve the identification of HOF causes of events and support the successful implementation of appropriate corrective actions The CAPS can be found in Appendix A. The first activity under the plan was the development of a questionnaire. This was distributed to WGHOF members and their counterparts from the Working Group on Operating Experience (WGOE). The questionnaire was comprised of 20 questions based on the objectives of the CSNI Activity Proposed Sheet. The intended survey participants were licensees with previous experience conducting root cause analyses. Responses were received from 26 respondents from 11 different countries. The results of the questionnaire were analyzed to identify themes for further discussion during a specialist meeting planned for September 2009. The following themes were presented during the WGHOF meeting in March of 2009 and endorsed for further work: - Roles and Influence of Senior Management, - Skills and Knowledge of the Investigators, - Qualitative Nature of HOF, - Influence of the Regulator, - Systematic Approach to Investigation. A summary of the questionnaire responses is provided in Appendix B

  15. Effect of skim milk treated with high hydrostatic pressure on permeate flux and fouling during ultrafiltration.

    Science.gov (United States)

    Leu, Mathilde; Marciniak, Alice; Chamberland, Julien; Pouliot, Yves; Bazinet, Laurent; Doyen, Alain

    2017-09-01

    Ultrafiltration (UF) is largely used in the dairy industry to generate milk and whey protein concentrate for standardization of milk or production of dairy ingredients. Recently, it was demonstrated that high hydrostatic pressure (HHP) extended the shelf life of milk and improved rennet coagulation and cheese yield. Pressurization also modified casein micelle size distribution and promoted aggregation of whey proteins. These changes are likely to affect UF performance. Consequently, this study determined the effect of skim milk pressurization (300 and 600 MPa, 5 min) on UF performance in terms of permeate flux decline and fouling. The effect of HHP on milk proteins was first studied and UF was performed in total recycle mode at different transmembrane pressures to determine optimal UF operational parameters and to evaluate the effect of pressurization on critical and limiting fluxes. Ultrafiltration was also performed in concentration mode at a transmembrane pressure of 345 kPa for 130 or 140 min to evaluate the decline of permeate flux and to determine fouling resistances. It was observed that average casein micelle size decreased by 32 and 38%, whereas β-lactoglobulin denaturation reached 30 and 70% at 300 and 600 MPa, respectively. These results were directly related to UF performance because initial permeate fluxes in total recycle mode decreased by 25% at 300 and 600 MPa compared with nonpressurized milk, critical flux, and limiting flux, which were lower during UF of milk treated with HHP. During UF in concentration mode, initial permeate fluxes were 30% lower at 300 and 600 MPa compared with the control, but the total flux decline was higher for nonpressurized milk (62%) compared with pressure-treated milk (30%). Fouling resistances were similar, whatever the treatment, except at 600 MPa where irreversible fouling was higher. Characterization of the fouling layer showed that caseins and β-lactoglobulin were mainly involved in membrane fouling after UF of

  16. Long-term performance and fouling analysis of full-scale direct nanofiltration (NF) installations treating anoxic groundwater

    KAUST Repository

    Beyer, Florian; Rietman, Bas M.; Zwijnenburg, Arie; Van Den Brink, Paula J.; Vrouwenvelder, Johannes S.; Jarzembowska, Monika; Laurinonyte, Judita; Stams, Alfons JM M; Plugge, Caroline M.

    2014-01-01

    . Investigations using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), total organic carbon (TOC) and adenosine triphosphate (ATP) measurements revealed a complex mixture of organic, biological and inorganic materials. The fouling

  17. Growth inhibition of fouling bacteria and diatoms by extract of terrestrial plant, @iDerris scandens@@ (Dicotyledonae:Leguminocae)

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Sonak, S.; Garg, A.

    Methanol extract of terrestrial plant, @iDerris scandens@@ Benth, was found to inhibit growth of four diatoms and 7 bacterial species of fouling community. The concentrations required to bring about 100% inhibition of growth of the diatoms ranged...

  18. Growth inhibition of fouling bacteria and diatoms by extract of terrestrial plant, Derris scandens (Dicotyledonae:Leguminocae)

    Digital Repository Service at National Institute of Oceanography (India)

    Sawant, S.S.; Sonak, S.; Garg, A.

    Methanol extract of terrestrial plant, Derris scandens Benth, was found to inhibit growth of four diatoms and 7 bacterial species of fouling community. The concentrations required to bring about 100% inhibition of growth of the diatoms ranged...

  19. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: Roles played by stabilization surfactants of oil droplets

    KAUST Repository

    Lu, Dongwei; Zhang, Tao; Ma, Jun

    2015-01-01

    of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged

  20. Biofouling and barnacle adhesion data for fouling-release coatings subjected to static immersion at seven marine sites

    Digital Repository Service at National Institute of Oceanography (India)

    Swain, G.; Anil, A.C.; Baier, R; Chia, F.-S.; Conte, E.; Cook, A.; Hadfield, M.; Haslbeck, E.; Holm, E.; Kavanagh, C.; Kohrs, D.; Kovach, B.; Lee, C.; Mazzella, L.; Meyer, A.E.; Qian, P.-Y.; Sawant, S.S.; Schultz, M.; Sigurdsson, J.; Smith, C.; Soo, L.; Terlizzi, A.; Wagh, A.; Zimmerman, R; Zupo, V.

    Little is known about the performance of fouling release coatings at different geographical locations. An investigation was designed to measure the differences in biofouling and biofouling adhesion strength on three known silicone formulations...

  1. The use of microbial and chemical analyses to characterize the variations in fouling profile of seawater reverse osmosis (SWRO) membrane

    KAUST Repository

    Manes, Carmem Lara De O; Khan, Muhammad; Molina, Veró nica Garcí a; Croue, Jean-Philippe

    2013-01-01

    and microbiological composition. The overall assessment of chemical parameters revealed that fouling layers were mainly composed by bio and organic material (proteins and lipids). Ca and Fe were found to be the most abundant elements having an increasing concentration

  2. Investigation of Filtration Membranes from the Dairy Protein Industry for Residual Fouling Using Infrared Spectroscopy and Chemometrics

    DEFF Research Database (Denmark)

    Jensen, Jannie Krog

    the reversible fouling can be removed/cleaned. The aim of this thesis is to investigate the residual fouling that is deposited on ultrafiltration and microfiltration membranes after usage. The membrane surfaces are investigated using infrared spectroscopy with an attenuated reflectance sampling unit...... and this is thesis work highlights the strengths and weaknesses of using infrared spectroscopy to investigate residual fouling on membranes and in particular the challenges with the infrared penetration depth when layering in the samples occurs. Real size production membrane cartridges at different stages of use...... microfiltration membrane cartridges were investigated with Attenuated- Total-Reflection Fourier-Transform-Infrared (ATR FT-IR) to map the residual fouling on both types of cartridges. The height of the characteristic amide peaks from proteins were used to determine the relative concentrations. The first...

  3. Change in the fouling propensity of sludge in membrane bioreactors (MBR) in relation to the accumulation of biopolymer clusters.

    Science.gov (United States)

    Sun, Fei-yun; Wang, Xiao-mao; Li, Xiao-yan

    2011-04-01

    A membrane bioreactor (MBR) and an activated sludge process (ASP) were operated side by side to evaluate the change of sludge supernatant characteristics and the evolution of the sludge fouling propensity. The MBR sludge had a higher organic concentration and more biopolymer clusters (BPC) in the supernatant compared with ASP. BPC increased in both concentration and size in the MBR. The results show that the change in the liquid-phase property had a profound effect on the sludge fouling propensity. MBR operation transformed typical activated sludge to MBR sludge with a higher fouling propensity. Distinct from the ASP, membrane filtration retained soluble microbial products (SMP) within the MBR, and the vast membrane surface provided a unique environment for the transformation of SMP to large size BPC, leading to further sludge deposition on the membrane surface. Thus, membrane filtration is the crucial cause of the inevitable fouling problem in submerged MBRs. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Enhanced fouling by inorganic and organic foulants on pressure retarded osmosis (PRO) hollow fiber membranes under high pressures

    KAUST Repository

    Chen, Sicong; Wan, Chunfeng; Chung, Neal Tai-Shung

    2015-01-01

    We have studied, for the first time, the fouling behavior of pressure retarded osmosis (PRO) hollow fiber membranes under low, moderate and high hydraulic pressures. The thin film composite (TFC) polyethersulfone (PES) membrane has a high water permeability and good mechanical strength. Membrane fouling by gypsum (CaSO4·2H2O) scalants, sodium alginate, and the combined foulants was examined under various pressures up to an ultrahigh hydraulic pressure of 18bar. In the combined fouling experiments, the membranes were conditioned by one of foulants followed by the other. Flux decline results suggested that such conditioning could increase the rate of combined fouling because of the change in membrane surface chemistry. Specially, the co-existence of gypsum crystals and alginate under 0bar led to the synergistic combined fouling and resulted in a greater flux decline than the sum of individual fouling. Interestingly, such gypsum-alginate synergistic fouling was not observed under high pressure PRO tests because the increased reverse salt flux inhibited the formation of gypsum crystals. Therefore, alginate fouling could be the dominant fouling mechanism for both (1) alginate conditioning and then scalants fouling, and (2) scalants conditioning and then alginate fouling PRO processes under 8bar and 18bar. Since the reverse salt flux increases from 5.6±1.1g/m2h at 0bar to 74.3±9.7g/m2h at 8bar, and finally to 150.5±2.5g/m2h under 18bar, the reverse salt ions lead to substantial declines of normalized flux under 8bar and 18bar because the reverse sodium ions not only reduce the effective driving force across the PRO membrane but also induce a significant cake-enhanced sodium concentration polarization layer and facilitate alginate gelation near the membrane surface. Therefore, the removal of alginate type foulants from the feed water stream may become essential for the success of PRO processes under high pressures.

  5. Enhanced fouling by inorganic and organic foulants on pressure retarded osmosis (PRO) hollow fiber membranes under high pressures

    KAUST Repository

    Chen, Sicong

    2015-04-01

    We have studied, for the first time, the fouling behavior of pressure retarded osmosis (PRO) hollow fiber membranes under low, moderate and high hydraulic pressures. The thin film composite (TFC) polyethersulfone (PES) membrane has a high water permeability and good mechanical strength. Membrane fouling by gypsum (CaSO4·2H2O) scalants, sodium alginate, and the combined foulants was examined under various pressures up to an ultrahigh hydraulic pressure of 18bar. In the combined fouling experiments, the membranes were conditioned by one of foulants followed by the other. Flux decline results suggested that such conditioning could increase the rate of combined fouling because of the change in membrane surface chemistry. Specially, the co-existence of gypsum crystals and alginate under 0bar led to the synergistic combined fouling and resulted in a greater flux decline than the sum of individual fouling. Interestingly, such gypsum-alginate synergistic fouling was not observed under high pressure PRO tests because the increased reverse salt flux inhibited the formation of gypsum crystals. Therefore, alginate fouling could be the dominant fouling mechanism for both (1) alginate conditioning and then scalants fouling, and (2) scalants conditioning and then alginate fouling PRO processes under 8bar and 18bar. Since the reverse salt flux increases from 5.6±1.1g/m2h at 0bar to 74.3±9.7g/m2h at 8bar, and finally to 150.5±2.5g/m2h under 18bar, the reverse salt ions lead to substantial declines of normalized flux under 8bar and 18bar because the reverse sodium ions not only reduce the effective driving force across the PRO membrane but also induce a significant cake-enhanced sodium concentration polarization layer and facilitate alginate gelation near the membrane surface. Therefore, the removal of alginate type foulants from the feed water stream may become essential for the success of PRO processes under high pressures.

  6. Fouling prevention of peptides from a tryptic whey hydrolysate during electromembrane processes by use of monovalent ion permselective membranes

    OpenAIRE

    Persico, Mathieu; Bazinet, Laurent

    2017-01-01

    Peptide adsorption occurring on conventional anion- and cation-exchange membranes is one of the main technological locks in electrodialysis (ED) for hydrolysate demineralization. Hence, the peptide fouling of monovalent anion (MAP) and monovalent cation (MCP) permselective membranes was studied and compared to conventional membranes (AMX-SB and CMX-SB). It appeared that the main peptide sequences responsible for fouling were TPEVDDEALEKFDK, VAGTWY and VLVLDTDYK for both anionic membranes; and...

  7. Anti-fouling protection on a ship's hull: evaluation of recent developments and formulation of innovative alternatives

    OpenAIRE

    Meskens, R.

    2017-01-01

    Marine fouling, or the growth of marine organisms on fully or partly submerged structures, is an unwanted phenomenon in the marine industry. Bio fouling will increase the hydrodynamic drag of ships, causing an increased fuel consumption, promote the corrosion of the metallic structures and trigger undesired transport of invasive species (IMO and the environment 2009, 2009).The impact is economic as well as environmental. More fuel consumption is synonym for more CO2 and other detrimental emis...

  8. Identified Hadron Production as a Function of Event Multiplicity and Transverse Spherocity in pp Collisions at $\\sqrt{s}$ = 7 and 13 TeV with the ALICE Detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00510339; Oskarsson, Anders; Silvermyr, David

    This study reports on identified hadron production as a function of event multiplicity ($\\langle\\textrm{d}N_{\\textrm{ch}}/\\textrm{d}η\\rangle$) and transverse spherocity ($S_\\textrm{O}$ ) in proton-proton collisions at $\\sqrt{s}$ = 7 and 13 TeV measured with the ALICE detector at the LHC. The particle spectra and their ratios measured in high-multiplicity events show signatures of an expanding medium. Integrated particle yields as a function of multiplicity measured in pp collisions at $\\sqrt{s}$ = 7 and 13 TeV are compared to those measured in p-Pb and Pb-Pb collisions. Hadrochemical composition of particles are found to be similar in different colliding systems under different $\\sqrt{s}$, provided similar multiplicities are compared. This suggests that hadron yields are dominantly driven by $\\langle\\textrm{d}N_{\\textrm{ch}}/\\textrm{d}η\\rangle$, and not the colliding system or center-of-mass energy. On the other hand, particle spectra measured in pp collisions at $\\sqrt{s}$ = 13 TeV is harder than that at 7...

  9. Removal of antibiotic-resistant bacteria and antibiotic resistance genes affected by varying degrees of fouling on anaerobic microfiltration membranes

    KAUST Repository

    Cheng, Hong; Hong, Pei-Ying

    2017-01-01

    An anaerobic membrane bioreactor was retrofitted with polyvinylidene fluoride (PVDF) microfiltration membrane units, each of which was fouled to a different extent. The membranes with different degrees of fouling were evaluated for their efficiencies in removing three antibiotic-resistant bacteria (ARB), namely, blaNDM-1-positive Escherichia coli PI-7, blaCTX-M-15-positive Klebsiella pneumoniae L7, and blaOXA-48-positive E. coli UPEC-RIY-4, as well as their associated plasmid-borne antibiotic resistance genes (ARGs). The results showed that the log removal values (LRVs) of ARGs correlated positively with the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes with a minimal foulant layer could remove more than 5 log units of ARB. However, as the membranes progressed to subcritical fouling, the LRVs of ARB decreased at increasing operating transmembrane pressures (TMPs). The LRV recovered back to 5 when the membrane was critically fouled, and the achieved LRV remained stable at different operating TMPs. Furthermore, characterization of the surface attributed the removal of both the ARB and ARGs to adsorption, which was facilitated by an increasing hydrophobicity and a decreasing surface ζ potential as the membranes fouled. Our results indicate that both the TMP and the foulant layer synergistically affected ARB removal, but the foulant layer was the main factor that contributed to ARG removal.

  10. Formation of fouling deposits on a carbon steel surface from Colombian heavy crude oil under preheating conditions

    Science.gov (United States)

    Muñoz Pinto, D. A.; Cuervo Camargo, S. M.; Orozco Parra, M.; Laverde, D.; García Vergara, S.; Blanco Pinzon, C.

    2016-02-01

    Fouling in heat exchangers is produced by the deposition of undesired materials on metal surfaces. As fouling progresses, pressure drop and heat transfer resistance is observed and therefore the overall thermal efficiency of the equipment diminishes. Fouling is mainly caused by the deposition of suspended particles, such as those from chemical reactions, crystallization of certain salts, and some corrosion processes. In order to understand the formation of fouling deposits from Colombian heavy oil (API≈12.3) on carbon steel SA 516 Gr 70, a batch stirred tank reactor was used. The reactor was operated at a constant pressure of 340psi while varying the temperature and reaction times. To evaluate the formation of deposits on the metal surfaces, the steel samples were characterized by gravimetric analysis and Scanning Electron Microscopy (SEM). On the exposed surfaces, the results revealed an increase in the total mass derived from the deposition of salt compounds, iron oxides and alkaline metals. In general, fouling was modulated by both the temperature and the reaction time, but under the experimental conditions, the temperature seems to be the predominant variable that controls and accelerates fouling.

  11. Removal of antibiotic-resistant bacteria and antibiotic resistance genes affected by varying degrees of fouling on anaerobic microfiltration membranes

    KAUST Repository

    Cheng, Hong

    2017-09-28

    An anaerobic membrane bioreactor was retrofitted with polyvinylidene fluoride (PVDF) microfiltration membrane units, each of which was fouled to a different extent. The membranes with different degrees of fouling were evaluated for their efficiencies in removing three antibiotic-resistant bacteria (ARB), namely, blaNDM-1-positive Escherichia coli PI-7, blaCTX-M-15-positive Klebsiella pneumoniae L7, and blaOXA-48-positive E. coli UPEC-RIY-4, as well as their associated plasmid-borne antibiotic resistance genes (ARGs). The results showed that the log removal values (LRVs) of ARGs correlated positively with the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes with a minimal foulant layer could remove more than 5 log units of ARB. However, as the membranes progressed to subcritical fouling, the LRVs of ARB decreased at increasing operating transmembrane pressures (TMPs). The LRV recovered back to 5 when the membrane was critically fouled, and the achieved LRV remained stable at different operating TMPs. Furthermore, characterization of the surface attributed the removal of both the ARB and ARGs to adsorption, which was facilitated by an increasing hydrophobicity and a decreasing surface ζ potential as the membranes fouled. Our results indicate that both the TMP and the foulant layer synergistically affected ARB removal, but the foulant layer was the main factor that contributed to ARG removal.

  12. Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes Affected by Varying Degrees of Fouling on Anaerobic Microfiltration Membranes.

    Science.gov (United States)

    Cheng, Hong; Hong, Pei-Ying

    2017-11-07

    An anaerobic membrane bioreactor was retrofitted with polyvinylidene fluoride (PVDF) microfiltration membrane units, each of which was fouled to a different extent. The membranes with different degrees of fouling were evaluated for their efficiencies in removing three antibiotic-resistant bacteria (ARB), namely, bla NDM-1 -positive Escherichia coli PI-7, bla CTX-M-15 -positive Klebsiella pneumoniae L7, and bla OXA-48 -positive E. coli UPEC-RIY-4, as well as their associated plasmid-borne antibiotic resistance genes (ARGs). The results showed that the log removal values (LRVs) of ARGs correlated positively with the extent of membrane fouling and ranged from 1.9 to 3.9. New membranes with a minimal foulant layer could remove more than 5 log units of ARB. However, as the membranes progressed to subcritical fouling, the LRVs of ARB decreased at increasing operating transmembrane pressures (TMPs). The LRV recovered back to 5 when the membrane was critically fouled, and the achieved LRV remained stable at different operating TMPs. Furthermore, characterization of the surface attributed the removal of both the ARB and ARGs to adsorption, which was facilitated by an increasing hydrophobicity and a decreasing surface ζ potential as the membranes fouled. Our results indicate that both the TMP and the foulant layer synergistically affected ARB removal, but the foulant layer was the main factor that contributed to ARG removal.

  13. Marine fouling release silicone/carbon nanotube nanocomposite coatings: on the importance of the nanotube dispersion state.

    Science.gov (United States)

    Beigbeder, Alexandre; Mincheva, Rosica; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Claes, Michael; Dubois, Philippe

    2010-05-01

    The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating.

  14. Temperature as a predictor of fouling and diarrhea in Slaughter pigs

    DEFF Research Database (Denmark)

    Jensen, Dan Børge; Toft, Nils; Kristensen, Anders Ringgaard

    2015-01-01

    The PigIT Project aims at improving welfare and production of slaughter pigs by integration of various sensor systems for alarm purposes. Here we present an exploratory analysis to assess the predictive value of temperature sensor data with respect to pen fouling and diarrhea. We recorded...... the temperature at four locations in two double-pens (by the drinking nipples and by the corridor) between November 2013 and December 2014. Logistic regression models were made to express the probability of fouling and diarrhea per day, and were reduced via backwards elimination. Furthermore, fitting the models...... was attempted with the raw temperature data as well as data averaged over 10, 15, 30 and 60 minutes. The predictive performances were evaluated with Matthews Correlation Coefficient (MCC). For diarrhea, the minimal and maximal temperatures at the water nipple and the corridor, as well as the maximal rate...

  15. Thiolated polyethylene oxide as a non-fouling element for nano-patterned bio-devices

    International Nuclear Information System (INIS)

    Lisboa, Patricia; Valsesia, Andrea; Colpo, Pascal; Gilliland, Douglas; Ceccone, Giacomo; Papadopoulou-Bouraoui, Andri; Rauscher, Hubert; Reniero, Fabiano; Guillou, Claude; Rossi, Francois

    2007-01-01

    This work describes the synthesis of a thiolated polyethylene oxide that self-assembles on gold to create a non-fouling surface. Thiolated polyethylene oxide was synthesised by reacting 16-mercaptohexadecanoic acid with polyethylene glycol mono methyl ether. The coverage of the thiolated polyethylene oxide on gold was studied by cyclic voltammetry, and the modified surfaces were characterised by X-ray photoelectron spectroscopy and ellipsometry. Protein resistance was assessed using quartz crystal microbalance. Results showed a non-fouling character produced by the thiolated polyethylene oxide. The synthesised product was used as the passivation layer on nano-patterned surfaces consisting of arrayed nano-spots, fabricated by plasma based colloidal lithography. The specific adsorption of anti-bovine serum albumin in the mercaptohexadecanoic acid spots was verified by atomic force microscopy

  16. Impact of the fouling mechanism on enzymatic depolymerization of xylan in different configurations of membrane reactors

    DEFF Research Database (Denmark)

    Mohd Sueb, Mohd Shafiq Bin; Luo, Jianquan; Meyer, Anne S.

    2017-01-01

    In order to maximize enzymatic xylan depolymerization while simultaneously purifying the resulting monosaccharide (xylose), different ultrafiltration (UF) membrane reactor configurations were evaluated. Initial results showed that the two hydrolytic enzymes required for complete depolymerization...... which hindered enzymatic attack in addition to fouling. Reaction with both enzymes followed by UF was found to be the optimal configuration, providing at least 40% higher xylan hydrolysis than the cascade configuration (involving sequential reaction with each of the enzymes separately......) and the simultaneous reaction-filtration with both enzymes, respectively. This study thus confirmed that the reactor configuration has a crucial impact on the performance of both the reaction and the separation process of xylose during enzymatic xylan degradation, and that the type of fouling mechanism varies...

  17. Irreversible fouling of membrane bioreactors due to formation of a non-biofilm gel layer

    DEFF Research Database (Denmark)

    Poorasgari, Eskandar; Larsen, Poul; Zheng, Xing

    2014-01-01

    Extra-cellular polymeric substances (EPS), known to contribute to fouling in membrane bio-reactors (MBRs), are generally divided into bound and free EPS. The free EPS are able to form a gel layer on the membrane active surface. The mechanisms involved in formation of such layer and its effects...... on performance of the MBR membranes were studied. The free EPS, extracted by centrifugation and microfiltration, contained a significant amount of humic-like substances. Under static contact to the membrane, adsorption of humic-like substances to the membrane occurred and could be explained by conventional...... adsorption kinetics. Due to static adsorption, surface roughness of the membrane declined significantly, indicating that adsorbed matters to the membranefilled the cavities of the membrane surface. Filtration of the free EPS caused 50% waterflux decline. The fouling resistance linearly increased...

  18. Anti-fouling properties of microstructured surfaces bio-inspired by rice leaves and butterfly wings.

    Science.gov (United States)

    Bixler, Gregory D; Theiss, Andrew; Bhushan, Bharat; Lee, Stephen C

    2014-04-01

    Material scientists often look to biology for new engineering solutions to materials science problems. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (antifouling) and lotus leaf (self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we study antifouling properties of four microstructured surfaces inspired by rice leaves and fabricated with photolithography and hot embossing techniques. Anti-biofouling effectiveness is determined with bioassays using Escherichia coli whilst inorganic fouling with simulated dirt particles. Antifouling data are presented to understand the role of surface geometrical features resistance to fouling. Conceptual modeling provides design guidance when developing novel antifouling surfaces for applications in the medical, marine, and industrial fields. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Copper current collectors reduce long-term fouling of air cathodes in microbial fuel cells

    KAUST Repository

    Myung, Jaewook; Yang, Wulin; Saikaly, Pascal; Logan, Bruce E

    2018-01-01

    Long-term operation of wastewater-fed, microbial fuel cells (MFCs) with cathodes made of activated carbon and stainless steel (SS) current collectors can result in decreased performance due to cathode fouling. Copper has good antimicrobial properties, and it is more electrically conductive than SS. To demonstrate that a copper current collector could produce a more fouling resistant cathode, MFCs with air cathodes using either SS or copper current collectors were operated using domestic wastewater for 27 weeks. The reduction in biofouling over time was shown by less biofilm formation on the copper cathode surface compared to SS cathodes, due to the antimicrobial properties of copper. Maximum power densities from 17–27 weeks were 440 ± 38 mW/m2 using copper and 370 ± 21 mW/m2 using SS cathodes. The main difference in the microbial community was a nitrifying community on the SS cathodes, which was not present on the copper cathodes.

  20. Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

    KAUST Repository

    Fang, Jason

    2010-05-01

    The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity. Increasing the compositional complexity of the system by including fluorinated or POSS-functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs. Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability. © 2010 Elsevier Ltd.

  1. Copper current collectors reduce long-term fouling of air cathodes in microbial fuel cells

    KAUST Repository

    Myung, Jaewook

    2018-02-05

    Long-term operation of wastewater-fed, microbial fuel cells (MFCs) with cathodes made of activated carbon and stainless steel (SS) current collectors can result in decreased performance due to cathode fouling. Copper has good antimicrobial properties, and it is more electrically conductive than SS. To demonstrate that a copper current collector could produce a more fouling resistant cathode, MFCs with air cathodes using either SS or copper current collectors were operated using domestic wastewater for 27 weeks. The reduction in biofouling over time was shown by less biofilm formation on the copper cathode surface compared to SS cathodes, due to the antimicrobial properties of copper. Maximum power densities from 17–27 weeks were 440 ± 38 mW/m2 using copper and 370 ± 21 mW/m2 using SS cathodes. The main difference in the microbial community was a nitrifying community on the SS cathodes, which was not present on the copper cathodes.

  2. Averting the foul taste of pediatric medicines improves adherence and can be lifesaving ? Pheburane? (sodium phenylbutyrate)

    OpenAIRE

    Koren, Gideon; Rieder, Michael J; Amitai, Yona

    2016-01-01

    Background Children?s aversions to poor and mostly bitter tastes and their inability to swallow tablets and capsules are major challenges in pediatric medicine. Sodium phenylbutyrate (NaPB) is a lifesaving waste nitrogen, alternative to urea nitrogen, for individuals suffering from urea cycle disorders. A major issue in the use of NaPB is its highly foul taste, which often leads to children being unable to consume it, resulting in ineffective treatment, or alternatively, necessitating the app...

  3. Non-fouling hydrogels of 2-hydroxyethyl methacrylate and zwitterionic carboxybetaine (meth)acrylamides

    Czech Academy of Sciences Publication Activity Database

    Kostina, Nina Yu.; Rodriguez-Emmenegger, Cesar; Houska, Milan; Brynda, Eduard; Michálek, Jiří

    2012-01-01

    Roč. 13, č. 12 (2012), s. 4164-4170 ISSN 1525-7797 R&D Projects: GA AV ČR KAN200520804; GA ČR GAP205/12/1702; GA ČR GAP106/12/1451 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : zwitterionic hydrogels * non-fouling properties * carboxybetaine Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.371, year: 2012

  4. Fouling of heat exchanger surfaces by dust particles from flue gases of glass furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Mutsaers, P.L.M.; Beerkens, R.G.C.; Waal, H. de (Nederlandse Centrale Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek, Delft. Inst. of Applied Physics)

    1989-08-01

    Fouling by dust particles generally leads to a reduction of the heat transfer and causes corrosion of secondary heat exchangers. A deposition model, including thermodynamic equilibrium calculations, has been derived and applied to describe the deposition (i.e. fouling) process and the nature of the deposition products in a secondary heat exchanger. The deposition model has been verified by means of laboratory experiments, for the case of flue gases from soda-lime glass furnaces. Corrosion of iron-containing metallic materials, caused by the deposition products, has been briefly investigated with the same equipment. There is a close similarity between the experimental results and model calculations. The largest deposition rates from flue gases on cylindrical tubes in cross-flow configuration, are predicted and measured at the upstream stagnation point. The lowest deposition rates are determined at downstream stagnation point locations. At tube surface temperatures of approximately 520 to 550 K, the fouling rate on the tube reaches a maximum. In this temperature region NaHSO{sub 4} is the most important deposition product. This component is mainly formed at temperatures from 470 up to 540 K. The compound Na{sub 3}H(SO{sub 4}){sub 2} seems to be stable up to 570 K, for even higher temperatures Na{sub 2}SO{sub 4} has been found. These deposition products react with iron, SO{sub 3}, oxygen and water vapour forming the complex corrosion product Na{sub 3}Fe(SO{sub 4}){sub 3}. NaHSO{sub 4}, which is formed at tube surface temperatures below 540 K, causes more severe corrosion of iron-containing materials than Na{sub 2}SO{sub 4}. Maintaining temperatures of the heat exchanger surfaces above 550 to 600 K reduces the fouling tendency and corrosion in case of flue gases from oil-fired soda-lime glass furnaces. (orig.).

  5. Use of pooled blood plasmas in the assessment of fouling resistance

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Rodriguez-Emmenegger, Cesar; Surman, František; Riedel, Tomáš; Bologna Alles, A.; Brynda, Eduard

    2014-01-01

    Roč. 4, č. 5 (2014), s. 2318-2321 ISSN 2046-2069 R&D Projects: GA MŠk EE2.3.30.0029; GA ČR GAP106/12/1451; GA ČR GAP205/12/1702; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : blood plasma * fouling * biomaterials Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.840, year: 2014

  6. Achieving reduced fouling of cooling water exchangers with stainless steel tubes

    International Nuclear Information System (INIS)

    Iftikhar, A.; Mir, N.

    2010-01-01

    Good performance of cooling water heat exchangers plays a vital role in the over all energy efficiency of a chemical plant. Heavy fouling on carbon steel tubes of the cooling water exchangers was causing poor performance and frequent cleaning requirement. The carbon steel tubes were replaced with stainless steel tubes. Improved performance was achieved and cleaning frequency reduced. The paper covers the details of study and methodology applied for the above changes along with summary of results. (author)

  7. Applying thermosettable zwitterionic copolymers as general fouling-resistant and thermal-tolerant biomaterial interfaces.

    Science.gov (United States)

    Chou, Ying-Nien; Chang, Yung; Wen, Ten-Chin

    2015-05-20

    We introduced a thermosettable zwitterionic copolymer to design a high temperature tolerance biomaterial as a general antifouling polymer interface. The original synthetic fouling-resistant copolymer, poly(vinylpyrrolidone)-co-poly(sulfobetaine methacrylate) (poly(VP-co-SBMA)), is both thermal-tolerant and fouling-resistant, and the antifouling stability of copolymer coated interfaces can be effectively controlled by regulating the VP/SBMA composition ratio. We studied poly(VP-co-SBMA) copolymer gels and networks with a focus on their general resistance to protein, cell, and bacterial bioadhesion, as influenced by the thermosetting process. Interestingly, we found that the shape of the poly(VP-co-SBMA) copolymer material can be set at a high annealing temperature of 200 °C while maintaining good antifouling properties. However, while the zwitterionic PSBMA polymer gels were bioinert as expected, control of the fouling resistance of the PSBMA polymer networks was lost in the high temperature annealing process. A poly(VP-co-SBMA) copolymer network composed of PSBMA segments at 32 mol % showed reduced fibrinogen adsorption, tissue cell adhesion, and bacterial attachment, but a relatively higher PSBMA content of 61 mol % was required to optimize resistance to platelet adhesion and erythrocyte attachment to confer hemocompatibility to human blood. We suggest that poly(VP-co-SBMA) copolymers capable of retaining stable fouling resistance after high temperature shaping have a potential application as thermosettable materials in a bioinert interface for medical devices, such as the thermosettable coating on a stainless steel blood-compatible metal stent investigated in this study.

  8. Preparation, Characterization and Analysis of Fouling Mechanisms of TiO2- Embedded PVDF Membranes

    Directory of Open Access Journals (Sweden)

    Yoones Jafarzadeh

    2017-01-01

    Full Text Available Titanium dioxide (TiO2-embedded polyvinylidene fluoride (PVDF mixed matrix membranes were prepared through a nonsolvent induced phase separation (NIPS method. The structure of the membranes was characterized by FESEM, EDX, water drop contact angle measurement, pure water flux and mean pore radius analysis. The results showed that the prepared membranes had asymmetric structures with macro-voids and the presence of TiO2 nanoparticles increased the size of macro-voids. Moreover, pure water flux increased from 41 kg/m2h to 162 kg/m2h the content of TiO2 nanoparticles increased from 1 wt% to 5 wt% as embedded membrane. The contact angle dropped from 100° for 1 wt% TiO2- embedded membrane to 69° for 5 wt% TiO2-embedded membrane, showing that the hydrophilicity of membranes increased by addition of inorganic TiO2 nanoparticles. The fouling behavior oftheprepared mixed matrix membranes was studied in filtration process of 1% humic acid solution. The results showed that fouling resistance of the membranes increased with higher content of TiO2 nanoparticles. The results of classic fouling modeling of membranes showed that for 2 and 5 wt% TiO2-embedded membranes the best fit of the data occurred with the intermediate blockage model whereas cake formation model was the dominant mechanism for other membranes. Moreover, the analysis of fouling mechanisms by combined models showed that cake filtration-intermediate blockage model was in good agreement with the experimental data for all membranes. Finally, the results showed that the rejection of membranes increased with the addition of TiO2 nanoparticles, and then decreased.

  9. Fouling-Resistant Membranes for Treating Concentrated Brines for Water Reuse in Advanced Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hendren, Zachary [RTI International, Research Triangle Park, NC (United States); Choi, Young Chul [RTI International, Research Triangle Park, NC (United States)

    2014-10-14

    The high total dissolved solids (TDS) levels in the wastewater quality generated from unconventional oil and gas development make the current state-of-the art approach to water treatment/disposal untenable. Our proposed membrane technology approach addresses the two major challenges associated with this water: 1) the membrane distillation process removes the high TDS content, which is often 8 times higher than that of seawater, and 2) our novel membrane coating prevents the formation of scale that would otherwise pose a significant operational hurdle. This is accomplished through next-generation electrically conductive membranes that mitigate fouling beyond what is currently possible, and allow for the flexibility to treat to the water to levels desirable for multiple reuse options, thus reducing fresh water withdrawal, all the way to direct disposal into the environment. The overall project objective was to demonstrate the efficacy of membrane distillation (MD) as a cost-savings technology to treat concentrated brines (such as, but not limited to, produced waters generated from fossil fuel extraction) that have high levels of TDS for beneficial water reuse in power production and other industrial operations as well as agricultural and municipal water uses. In addition, a novel fouling-resistant nanocomposite membrane was developed to reduce the need for chemicals to address membrane scaling due to the precipitation of divalent ions in high-TDS waters and improve overall MD performance via an electrically conductive membrane distillation process (ECMD). This anti-fouling membrane technology platform is based on incorporating carbon nanotubes (CNTs) into the surface layer of existing, commercially available MD membranes. The CNTs impart electrical conductivity to the membrane surface to prevent membrane scaling and fouling when an electrical potential is applied.

  10. Combination of Electrochemical Processes with Membrane Bioreactors for Wastewater Treatment and Fouling Control: A Review

    OpenAIRE

    Ensano, Benny M. B.; Borea, Laura; Naddeo, Vincenzo; Belgiorno, Vincenzo; de Luna, Mark D. G.; Ballesteros, Florencio C.

    2016-01-01

    This paper provides a critical review about the integration of electrochemical processes into membrane bioreactors (MBR) in order to understand the influence of these processes on wastewater treatment performance and membrane fouling control. The integration can be realized either in an internal or an external configuration. Electrically enhanced membrane bioreactors or electro membrane bioreactors (eMBRs) combine biodegradation, electrochemical and membrane filtration processes into one syst...

  11. Combination of electrochemical processes with membrane bioreactors for wastewater treatment and fouling control: A review

    OpenAIRE

    Benny Marie B. Ensano; Laura Borea; Vincenzo Naddeo; Vincenzo Belgiorno; Mark Daniel G. de Luna; Mark Daniel G. de Luna; Florencio C. Ballesteros, Jr.; Florencio C. Ballesteros, Jr.

    2016-01-01

    This paper provides a critical review about the integration of electrochemical processes into membrane bioreactors (MBR) in order to understand the influence of these processes on wastewater treatment performance and membrane fouling control. The integration can be realized either in an internal or an external configuration. Electrically enhanced membrane bioreactors or electro membrane bioreactors (eMBRs) combine biodegradation, electrochemical and membrane filtration processes into one syst...

  12. Optimisation and Characterisation of Anti-Fouling Ternary SAM Layers for Impedance-Based Aptasensors

    Directory of Open Access Journals (Sweden)

    Anna Miodek

    2015-09-01

    Full Text Available An aptasensor with enhanced anti-fouling properties has been developed. As a case study, the aptasensor was designed with specificity for human thrombin. The sensing platform was developed on screen printed electrodes and is composed of a self-assembled monolayer made from a ternary mixture of 15-base thiolated DNA aptamers specific for human thrombin co-immobilised with 1,6-hexanedithiol (HDT and further passivated with 1-mercapto-6-hexanol (MCH. HDT binds to the surface by two of its thiol groups forming alkyl chain bridges and this architecture protects from non-specific attachment of molecules to the electrode surface. Using Electrochemical Impedance Spectroscopy (EIS, the aptasensor is able to detect human thrombin as variations in charge transfer resistance (Rct upon protein binding. After exposure to a high concentration of non-specific Bovine Serum Albumin (BSA solution, no changes in the Rct value were observed, highlighting the bio-fouling resistance of the surface generated. In this paper, we present the optimisation and characterisation of the aptasensor based on the ternary self-assembled monolayer (SAM layer. We show that anti-fouling properties depend on the type of gold surface used for biosensor construction, which was also confirmed by contact angle measurements. We further studied the ratio between aptamers and HDT, which can determine the specificity and selectivity of the sensing layer. We also report the influence of buffer pH and temperature used for incubation of electrodes with proteins on detection and anti-fouling properties. Finally, the stability of the aptasensor was studied by storage of modified electrodes for up to 28 days