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Sample records for biofilm reactor developed

  1. Nitritation performance and biofilm development of co- and counter-diffusion biofilm reactors: Modeling and experimental comparison

    DEFF Research Database (Denmark)

    Wang, Rongchang; Terada, Akihiko; Lackner, Susanne;

    2009-01-01

    A comparative study was conducted on the start-up performance and biofilm development in two different biofilm reactors with aim of obtaining partial nitritation. The reactors were both operated under oxygen limited conditions, but differed in geometry. While substrates (O-2, NH3) co-diffused in ...

  2. Biological kinetics parameters in a pure culture biofilm developed in an airlift reactor

    OpenAIRE

    Lopes, F. A.; Vieira, M. J.; Melo, L. F.

    2000-01-01

    A diffusion-reaction model was fitted to data obtained with Pseudomonas fluorescens biofilms developed in an airlift reactor under different limiting substrate conditions, in order to determine the biofilm kinetic constants and the substrate concentration profiles within the biological films. Model predicted concentration profiles within the biofilms demonstrate that all films were completely penetrated by the substrate and that the reaction rate inside the biofilms was of zero ...

  3. Investigating biofilm structure developing on carriers from lab-scale moving bed biofilm reactors based on light microscopy and optical coherence tomography.

    Science.gov (United States)

    Li, Chunyan; Felz, Simon; Wagner, Michael; Lackner, Susanne; Horn, Harald

    2016-01-01

    This study focused on characterizing the structure of biofilms developed on carriers used in lab-scale moving bed biofilm reactors. Both light microscopy (2D) and optical coherence tomography (OCT) were employed to track the biofilm development on carriers of different geometry and under different aeration rates. Biofilm structure was further characterized with respect to average biofilm thickness, biofilm growth velocity, biomass volume, compartment filling degree, surface area, etc. The results showed that carriers with a smaller compartment size stimulated a quick establishment of biofilms. Low aeration rates favored fast development of biofilms. Comparison between the results derived from 2D and 3D images revealed comparable results with respect to average biofilm thickness and compartment filling degree before the carrier compartments were fully willed with biomass. However, 3D imaging with OCT was capable of visualizing and quantifying the heterogeneous structure of biofilms, which cannot be achieved using 2D imaging. PMID:26476614

  4. A new approach for development of kinetics of wastewater treatment in aerobic biofilm reactor

    Science.gov (United States)

    Goswami, S.; Sarkar, S.; Mazumder, D.

    2016-02-01

    Biofilm process is widely used for the treatment of a variety of wastewater especially containing slowly biodegradable substances. It provides resistance against toxic environment and is capable of retaining biomass under continuous operation. Development of kinetics is very much pertinent for rational design of a biofilm process for the treatment of wastewater with or without inhibitory substances. A simple approach for development of such kinetics for an aerobic biofilm reactor has been presented using a novel biofilm model. The said biofilm model is formulated from the correlations between substrate concentrations in the influent/effluent and at biofilm liquid interface along with substrate flux and biofilm thickness complying Monod's growth kinetics. The methodology for determining the kinetic coefficients for substrate removal and biomass growth has been demonstrated stepwise along with graphical representations. Kinetic coefficients like K, k, Y, b t, b s, and b d are determined either from the intercepts of X- and Y-axis or from the slope of the graphical plots.

  5. Biofilm Development

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2015-01-01

    , and not by specific genetic programs. It appears that biofilm formation can occur through multiple pathways and that the spatial structure of the biofilms is species dependent as well as dependent on environmental conditions. Bacterial subpopulations, e.g., motile and nonmotile subpopulations, can develop...

  6. Biofilm development during the start-up period of anaerobic biofilm reactors: the biofilm Archaea community is highly dependent on the support material

    OpenAIRE

    Habouzit, Frédéric; Hamelin, Jérôme; Santa-Catalina, Gaelle; Steyer, Jean-Philippe; Bernet, Nicolas

    2014-01-01

    To evaluate the impact of the nature of the support material on its colonization by a methanogenic consortium, four substrata made of different materials: polyvinyl chloride, 2 polyethylene and polypropylene were tested during the start-up of lab-scale fixed-film reactors. The reactor performances were evaluated and compared together with the analysis of the biofilms. Biofilm growth was quantified and the structure of bacterial and archaeal communities were characterized by molecular fingerpr...

  7. Biofilm development in membrane bioreactors

    OpenAIRE

    Savnik, Veronika

    2010-01-01

    Prevention of biofilm development and its removal has crucial meaning in membrane reactor. Biofilm causes pore blocking on membranes, which causes a drop in efficiency of mixed liquor filtration and consequently deteriorates the efficiency of whole membrane bioreactor. This thesis deals with factors that affect biofilm development in membrane bioreactors. Structure and growth of biofilm are presented from its initial attachment of individual particles, their parameters of adhesion, hydrodynam...

  8. Development and validation of a microfluidic reactor for biofilm monitoring via optical methods

    Science.gov (United States)

    Meyer, Mariana T.; Roy, Varnika; Bentley, William E.; Ghodssi, Reza

    2011-05-01

    We present the design, fabrication, and verification of a microfluidic platform for optical monitoring of bacterial biofilms. Biofilm formation characterizes the majority of infections caused by bacteria that are developing increased resistance to traditional antibiotic treatment, necessitating the development of reliable tools not only for study of biofilm growth, but also for in situ examination of the response to applied stimuli. The presented platform was used to continuously and non-invasively observe the dependence of Escherichia coli biofilm formation on bacterial signaling by monitoring the change in biofilm optical density over the growth period. Results were corroborated by measurement of biofilm morphological properties via confocal microscopy, and statistical analysis was applied to verify the repeatability of observed optical and morphological differences in the biofilms formed. The presented platform will be used to characterize biofilm formation and response in drug discovery applications.

  9. Development and validation of a microfluidic reactor for biofilm monitoring via optical methods

    International Nuclear Information System (INIS)

    We present the design, fabrication, and verification of a microfluidic platform for optical monitoring of bacterial biofilms. Biofilm formation characterizes the majority of infections caused by bacteria that are developing increased resistance to traditional antibiotic treatment, necessitating the development of reliable tools not only for study of biofilm growth, but also for in situ examination of the response to applied stimuli. The presented platform was used to continuously and non-invasively observe the dependence of Escherichia coli biofilm formation on bacterial signaling by monitoring the change in biofilm optical density over the growth period. Results were corroborated by measurement of biofilm morphological properties via confocal microscopy, and statistical analysis was applied to verify the repeatability of observed optical and morphological differences in the biofilms formed. The presented platform will be used to characterize biofilm formation and response in drug discovery applications

  10. Characterisitics of Streptomyces griseus biofilms in continuous flow tubular reactors

    OpenAIRE

    Winn, Michael; Habimana, Olivier; Casey, Eoin; Murphy, Cormac D.

    2014-01-01

    The purpose of this study was to investigate the feasibility of cultivating the biotechnologically important bacterium Streptomyces griseus in single-species and mixed- species biofilms using a Tubular Biofilm Reactor (TBR). Streptomyces griseus biofilm development was found to be cyclical, starting with the initial adhesion and subsequent development of a visible biofilm after 24 hours growth, followed by the complete detachment of the biofilm as a single mass, and ending with the re-coloni...

  11. Membrane supported biofilm reactors, a litterature review

    OpenAIRE

    Hem, L.; Catsivilas, F.

    1996-01-01

    Membrane supported biofilm reactor is a new technology for biological degredation of pollutants. The utilisation of mebranes as a support for biofilm growth may occure in treatment of several types of wastewater, as removing of nitrogen from municipal wastewater or removing of spesific pollutants from industrial wastewaters. The advantages of such a technology are a better aeration control process than most other biofilm reactors, and the possibility of bubble-free aeration in the removal of ...

  12. Anaerobic granular sludge and biofilm reactors

    DEFF Research Database (Denmark)

    Skiadas, Ioannis V.; Gavala, Hariklia N.; Schmidt, Jens Ejbye;

    2003-01-01

    The long retention time of the active biomass in the high-rate anaerobic digesters is the key factor for the successful application of the high rate anaerobic wastewater treatment. The long solids retention time is achieved due to the specific reactor configuration and it is enhanced...... by the immobilization of the biomass, which forms static biofilms, particle-supported biofilms, or granules depending on the reactor's operational conditions. The advantages of the high-rate anaerobic digestion over the conventional aerobic wastewater treatment methods has created a clear trend for the change...... of the role of the anaerobic digestion in the wastewater treatment plants from a pre-treatment method to the main biological treatment method. The application of staged high-rate anaerobic digesters has shown the larger potential among the recent developments in this direction. The most common high...

  13. Improved computational model (AQUIFAS) for activated sludge, integrated fixed-film activated sludge, and moving-bed biofilm reactor systems, Part I: Semi-empirical model development.

    Science.gov (United States)

    Sen, Dipankar; Randall, Clifford W

    2008-05-01

    Research was undertaken to develop a model for activated sludge, integrated fixed-film activated sludge (IFAS), and moving-bed biofilm reactor (MBBR) systems. The model can operate with up to 12 cells (reactors) in series, with biofilm media incorporated to one or more cells, except the anaerobic cells. The process configuration can be any combination of anaerobic, anoxic, aerobic, post-anoxic with or without supplemental carbon, and reaeration; it can also include any combination of step feed and recycles, including recycles for mixed liquor, return activated sludge, nitrates, and membrane bioreactors. This paper presents the structure of the model. The model embeds a biofilm model into a multicell activated sludge model. The biofilm flux rates for organics, nutrients, and biomass can be computed by two methods--a semi-empirical model of the biofilm that is relatively simpler, or a diffusional model that is computationally intensive. The values of the kinetic parameters for the model were measured using pilot-scale activated sludge, IFAS, and MBBR systems. For the semiempirical version, a series of Monod equations were developed for chemical oxygen demand, ammonium-nitrogen, and oxidized-nitrogen fluxes to the biofilm. Within the equations, a second Monod expression is used to simulate the effect of changes in biofilm thickness and fraction nitrifiers in the biofilm. The biofilm flux model is then linked to the activated sludge model. The diffusional model and the verification of the models are presented in subsequent papers (Sen and Randall, 2008a, 2008b). The model can be used to quantify the amount of media and surface area required to achieve nitrification, identify the best locations for the media, and optimize the dissolved oxygen levels and nitrate recycle rates. Some of the advanced features include the ability to apply different media types and fill fractions in cells; quantify nitrification, denitrification, and biomass production in the biofilm and

  14. A versatile reactor for continuous monitoring of biofilm properties in laboratory and industrial conditions

    OpenAIRE

    M.O. Pereira; Morin, P.; Vieira, M. J.; Melo, L. F.

    2002-01-01

    Aims: The understanding of the dynamics of surface microbial colonization with concomitant monitoring of biofilm formation requires the development of biofilm reactors that enable direct and real-time evaluation under different hydrodynamic conditions. Methods and Results: This work proposes and discusses a simple flow cell reactor that provides a means to monitoring biofilm growth by periodical removing biofilm-attached slides for off-line, both non-destructive and destructive biofilm ana...

  15. Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor

    Directory of Open Access Journals (Sweden)

    Marchetti Leonardo

    2006-04-01

    Full Text Available Abstract Background Olive mill wastewater (OMW is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter

  16. Degradation of Non-Diffusible Organic Matter in Biofilm Reactors

    DEFF Research Database (Denmark)

    Rohold, Lars Erik; Harremoës, Poul

    1993-01-01

    A simple laboratory test has been developed in order to demonstrate qualitatively, that the removal of non-diffusible organics in a biofilm reactor requires hydrolysis by extracellular enzymes in the bulk water of the reactor. The results demonstrate the effect of changing volume of bulk water on...

  17. Development of a simplified biofilm model

    Science.gov (United States)

    Sarkar, Sushovan; Mazumder, Debabrata

    2015-11-01

    A simplified approach for analyzing the biofilm process in deriving an easy model has been presented. This simplified biofilm model formulated correlations between substrate concentration in the influent/effluent and at biofilm-liquid interface along with substrate flux and biofilm thickness. The model essentially considered the external mass transport according to Fick's Law, steady state substrate as well as biomass balance for attached growth microorganisms. In substrate utilization, Monod growth kinetics has been followed incorporating relevant boundary conditions at the liquid-biofilm interface and at the attachment surface. The numerical solution of equations was accomplished using Runge-Kutta method and accordingly an integrated computer program was developed. The model has been successfully applied in a distinct set of trials with varying range of representative input variables. The model performance was compared with available existing methods and it was found an easy, accurate method that can be used for process design of biofilm reactor.

  18. Combined Reactor and Microelectrode Measurements in Laboratory Grown Biofilms

    DEFF Research Database (Denmark)

    Larsen, Tove; Harremoës, Poul

    1994-01-01

    A combined biofilm reactor-/microelectrode experimental set-up has been constructed, allowing for simultaneous reactor mass balances and measurements of concentration profiles within the biofilm. The system consists of an annular biofilm reactor equipped with an oxygen microelectrode. Experiments...... were carried out with aerobic glucose and starch degrading biofilms. The well described aerobic glucose degradation biofilm system was used to test the combined reactor set-up. Results predicted from known biofilm kinetics were obtained. In the starch degrading biofilm, basic assumptions were tested...

  19. Modeling for Anaerobic Fixed-Bed Biofilm Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B. Y. M.; Pfeffer, J. T.

    1989-06-01

    The specific objectives of this research were: 1. to develop an equilibrium model for chemical aspects of anaerobic reactors; 2. to modify the equilibrium model for non-equilibrium conditions; 3. to incorporate the existing biofilm models into the models above to study the biological and chemical behavior of the fixed-film anaerobic reactors; 4. to experimentally verify the validity of these models; 5. to investigate the biomass-holding ability of difference packing materials for establishing reactor design criteria.

  20. Microbiology and performance of a methanogenic biofilm reactor during the start-up period

    OpenAIRE

    Cresson, R.; Dabert, P.; Bernet, N.

    2009-01-01

    Aims: To understand the interactions between anaerobic biofilm development and process performances during the start-up period of methanogenic biofilm reactor. Methods and Results: Two methanogenic inverse turbulent bed reactors have been started and monitored for 81 days. Biofilm development (adhesion, growth, population dynamic) and characteristics (biodiversity, structure) were investigated using molecular tools (PCRSSCP, FISH-CSLM). Identification of the dominant populations, in relati...

  1. Microbiology and performance of a methanogenic biofilm reactor during the start-up period

    OpenAIRE

    Cresson, R.; Dabert, P.; Bernet, N.

    2009-01-01

    Aims: To understand the interactions between anaerobic biofilm development and process performances during the start-up period of methanogenic biofilm reactor. Methods and Results: Two methanogenic inverse turbulent bed reactors have been started and monitored for 81 days. Biofilm development (adhesion, growth, population dynamic) and characteristics (biodiversity, structure) were investigated using molecular tools (PCRSSCP, FISH-CSLM). Identification of the dominant populations, in relation ...

  2. Essential factors of an integrated moving bed biofilm reactor-membrane bioreactor: Adhesion characteristics and microbial community of the biofilm.

    Science.gov (United States)

    Tang, Bing; Yu, Chunfei; Bin, Liying; Zhao, Yiliang; Feng, Xianfeng; Huang, Shaosong; Fu, Fenglian; Ding, Jiewei; Chen, Cuiqun; Li, Ping; Chen, Qianyu

    2016-07-01

    This work aims at revealing the adhesion characteristics and microbial community of the biofilm in an integrated moving bed biofilm reactor-membrane bioreactor, and further evaluating their variations over time. With multiple methods, the adhesion characteristics and microbial community of the biofilm on the carriers were comprehensively illuminated, which showed their dynamic variation along with the operational time. Results indicated that: (1) the roughness of biofilm on the carriers increased very quickly to a maximum value at the start-up stage, then, decreased to become a flat curve, which indicated a layer of smooth biofilm formed on the surface; (2) the tightly-bound protein and polysaccharide was the most important factor influencing the stability of biofilm; (3) the development of biofilm could be divided into three stages, and Gammaproteobacteria were the most dominant microbial species in class level at the last stage, which occupied the largest ratio (51.48%) among all microbes. PMID:27038266

  3. Improved Denitrification of Municipal Sludge in Biofilm-electrode Reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Le-hua; JIA Jin-ping; WANG Ya-lin; YANG Ji

    2004-01-01

    The denitrification of municipal sludge was improved by combining biofilm process with the electrochemical effect in a single novel reactor. Experiments in this reactor[electric current 60 mA, hydraulic retention time (HRTs) 6.0 h] showed that the removal of CODCr, ammonia nitrogen and total nitrogen in the biofilm-electrode reactor were 2.5%, 1.2%, 14.9%, respectively, higher than those in a traditional biofilm reactor.

  4. Chemical composition and activity of a biofilm during the start-up of an airlift reactor

    OpenAIRE

    Lopes, F. A.; Vieira, M. J.; Melo, L. F.

    2000-01-01

    For the successful operation of a biofilm reactor, it is important to characterise the fixed biomass, its activity and composition. The purpose of this research is to monitor the biofilm characteristics of an airlift reactor, namely its composition in terms of exopolymers (polysaccharides and proteins), attached biomass, thickness, total proteins, as well as its activity in terms of substrate consumption rates. During the early phases of biofilm development, a high exopolymer production was o...

  5. DEGRADATION OF AROMATIC COMPOUNDS USING MOVING BED BIOFILM REACTORS

    Directory of Open Access Journals (Sweden)

    B. Ayati, H. Ganjidoust, M. Mir Fattah

    2007-04-01

    Full Text Available For biological treatment of water, there are many different biofilm systems in use. Examples of them are trickling filters, rotating biological contactors, fixed media submerged biofilters, granular media biofilters and fluidized bed reactors. They all have their advantages and disadvantages. Hence, the Moving Bed Biofilm Reactor process was developed in Norway in the late 1980s and early 1990s to adopt the best features of the activated sludge process as well as those of the biofilter processes, without including the worst. Two cylindrical moving bed biofilm reactors were used in this study working in upflow stream conditions. Experiments have been done in aerobic batch flow regime. Laboratory experiments were conducted at room temperature (23–28C and synthetic wastewater comprising a composition of phenol and hydroquinone in each reactor as the main organic constituents, plus balanced nutrients and alkalinity were used to feed the reactor. The ratio of influent to effluent COD was determined at different retention times. The results indicated that the removal efficiency of each selected compound is affected by the detention time. At low phenol and hydroquinone concentration (from 700 to 1000 mg/L maximum removal efficiency (over 80 % was obtained. By further increasing in COD loading rate up to 3000 mg/L, a decrease in COD removal rate was occurred. In the reactor containing pyrogallol in COD of 1500 mg/L, the removal rate decreased to 10 percent because of its toxicity for microorganisms.

  6. Biofilms: a developing microscopic community

    Directory of Open Access Journals (Sweden)

    Rivera Sandra Patricia

    2004-09-01

    Full Text Available Biofilms are microbial communities composed by different microbiota embebbed in a special adaptive environment. These communities show different characteristics such as heterogeneity, diversity in microenvironments, capacity to resist antimicrobial therapy and ability to allow bacterial communication. These characteristics convert them in complex organizations that are difficult to eradicate in their own environment. In the man, biofilms are associated to a great number of slow-development infectious processes which greatly difficulties their eradication. In the industry and environment, biofilms are centered in processes known as biofouling and bioremediation. The former is the contamination of a system due to the microbial activity of a biofilm. The latter uses biofilms to improve the conditions of a contaminated system. The study of biofilms is a new and exciting field which is constantly evolving and whose implications in medicine and industry would have important repercussions for the humankind.

  7. Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors

    Directory of Open Access Journals (Sweden)

    M. Fuentes

    2009-09-01

    Full Text Available This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs. The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1ºC lab-scale AFBRs (R1 and R2 loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR, over a four month period. Step-type disturbances were applied on the inlet (glucose and acetic acid substrate concentration (chemical oxygen demand (COD from 0.85 to 2.66 g L-1 and on the feed flow rate (from 3.2 up to 6.0 L d-1 considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of 3.73⋅10(4 and 0.75⋅10(4 s² kg-1 m-1 for R1 and R2, respectively, were estimated.

  8. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    OpenAIRE

    Lemire, Joe A.; Marc A Demeter; Iain George; Howard Ceri; Turner, Raymond J.

    2015-01-01

    Moving bed biofilm reactors (MBBRs) are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR) carriers (biofilm support materials), allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that ...

  9. Contribution to valuation and dimensioning of biogas reactors which use substratum-biofilm systems

    International Nuclear Information System (INIS)

    The study develops an algorithm for valuating static substratum - biofilm systems used in biogas reactors. This valuation method permits coupling the service value of static substratum - biofilm systems as derived from individual quality factors with the costs of the substratum. Beyond this the cost-related value thus obtained is of principle value for comparing different variants. (orig.)

  10. Microbial pathogenesis and biofilm development

    DEFF Research Database (Denmark)

    Reisner, A.; Høiby, N.; Tolker-Nielsen, Tim;

    2004-01-01

    cycles of different microorganisms will eventually lead to improved treatments. Several bacteria have evolved specific strategies for virulent colonization of humans in addition to their otherwise harmless establishment as environmental inhabitants. In many such cases biofilm development seems to play a...... of polysaccharides. A recent striking finding is that DNA released from biofilm cells may be important as an initial matrix former [3]. At later times other EPS molecules may add to the shape and quality of the mature biofilm structure. Figure 1 summarizes the principle stepsinvolved in the...

  11. Phenotypic Characterization of Streptococcus pneumoniae Biofilm Development

    OpenAIRE

    Allegrucci, Magee; Hu, F.Z.; Shen, K.; J. Hayes; Ehrlich, Garth D.; Post, J Christopher; Sauer, Karin

    2006-01-01

    Streptococcus pneumoniae is among the most common pathogens associated with chronic otitis media with effusion, which has been hypothesized to be a biofilm disease. S. pneumoniae has been shown to form biofilms, however, little is known about the developmental process, the architecture, and the changes that occur upon biofilm development. In the current study we made use of a continuous-culture biofilm system to characterize biofilm development of 14 different S. pneumoniae strains representi...

  12. Applying a framework for calibrating a biofilm-reactor model:a full-scale moving-bed biofilm reactor active in nitrification

    OpenAIRE

    Brockmann, Doris; Boltz, Joshua P.; Morgenroth, Eberhard; Daigger, Glen T.; Henze, Mogens; Rittmann, Bruce; Sorensen, Kim H.; Takacs, Imre; Vanrolleghem, Peter A.; van Loosdrecht, Mark

    2013-01-01

    Many wastewater treatment plant (WWTP) simulators include biofilm reactor modules, enabling a more widespread application of biofilm models in engineering practice. To increase acceptance, and promote proper and effective biofilm model use in practice, a framework for biofilm reactor model calibration and application is needed. A step-wise calibration approach for biofilm reactor models was presented at WWTmod 2012. The proposed calibration framework was used in this study to calibrate a biof...

  13. Degradation Mechanisms of Colloidal Organic Matter in Biofilm Reactors

    DEFF Research Database (Denmark)

    Larsen, Tove; Harremoës, Poul

    1994-01-01

    The degradation mechanisms of colloidal organic matter in biofilm reactors have been studied in an idealized laboratory reactor system with soluble starch as a model substrate. Batch tests and experiments with different reactor configurations have shown that for this specific substrate, bulk liquid......-diffusible organic matter in a biofilm reactor. DH depends on the combined volumetric and surface hydraulic loading rate, Q2/(AV). In full-scale wastewater treatment plants, the degradation mechanism presented in this paper can explain important differences between the performance of trickling filters and RBC...... reactors....

  14. Microbial pathogenesis and biofilm development

    DEFF Research Database (Denmark)

    Reisner, A.; Høiby, N.; Tolker-Nielsen, Tim; Molin, Søren

    2004-01-01

    Microbial infections constitute a major cause of premature death in large parts of the world, and for several years we have seen an alarming tendency towards increasing problems of controlling such infections by antibiotic treatments. It is hoped that an improved understanding of the infectious...... been termed 'maturation', which is thought to be mediated by a differentiation process. Maturation into late stages of biofilm development resulting in stable and robust structures may require the formation of a matrix of extracellular polymeric substances (EPS), which are most often assumed to consist...... of polysaccharides. A recent striking finding is that DNA released from biofilm cells may be important as an initial matrix former [3]. At later times other EPS molecules may add to the shape and quality of the mature biofilm structure. Figure 1 summarizes the principle stepsinvolved in the...

  15. Bioremoval of trivalent chromium using Bacillus biofilms through continuous flow reactor

    International Nuclear Information System (INIS)

    Highlights: ► Effective bioremoval of Cr(III) using bacterial biofilms. ► Simplified bioreactor was fabricated for the biofilm development and Cr(III) removal. ► Economically feasible substrate like coarse sand and pebbles were used. - Abstract: Present study deals with the applicability of bacterial biofilms for the bioremoval of trivalent chromium from tannery effluents. A continuous flow reactor was designed for the development of biofilms on different substrates like glass beads, pebbles and coarse sand. The parameters for the continuous flow reactor were 20 ml/min flow rate at 30 °C, pH4. Biofilm biomass on the substrates was in the following sequence: coarse sand > pebbles > glass beads (4.8 × 107, 4.5 × 107 and 3.5 × 105 CFU/cm2), which was confirmed by CLSM. Biofilms developed using consortium of Bacillus subtilis and Bacillus cereus on coarse sand had more surface area and was able to remove 98% of Cr(III), SEM-EDX proved 92.60% Cr(III) adsorption on biofilms supported by coarse sand. Utilization of Bacillus biofilms for effective bioremoval of Cr(III) from chrome tanning effluent could be a better option for tannery industry, especially during post chrome tanning operation.

  16. Bioremoval of trivalent chromium using Bacillus biofilms through continuous flow reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sundar, K.; Sadiq, I. Mohammed; Mukherjee, Amitava [Centre for Nanobiotechnology, Nano Bio-Medicine Laboratory School of Bio Sciences and Technology VIT University, Vellore - 632014 (India); Chandrasekaran, N., E-mail: nchandrasekaran@vit.ac.in [Centre for Nanobiotechnology, Nano Bio-Medicine Laboratory School of Bio Sciences and Technology VIT University, Vellore - 632014 (India)

    2011-11-30

    Highlights: Black-Right-Pointing-Pointer Effective bioremoval of Cr(III) using bacterial biofilms. Black-Right-Pointing-Pointer Simplified bioreactor was fabricated for the biofilm development and Cr(III) removal. Black-Right-Pointing-Pointer Economically feasible substrate like coarse sand and pebbles were used. - Abstract: Present study deals with the applicability of bacterial biofilms for the bioremoval of trivalent chromium from tannery effluents. A continuous flow reactor was designed for the development of biofilms on different substrates like glass beads, pebbles and coarse sand. The parameters for the continuous flow reactor were 20 ml/min flow rate at 30 Degree-Sign C, pH4. Biofilm biomass on the substrates was in the following sequence: coarse sand > pebbles > glass beads (4.8 Multiplication-Sign 10{sup 7}, 4.5 Multiplication-Sign 10{sup 7} and 3.5 Multiplication-Sign 10{sup 5} CFU/cm{sup 2}), which was confirmed by CLSM. Biofilms developed using consortium of Bacillus subtilis and Bacillus cereus on coarse sand had more surface area and was able to remove 98% of Cr(III), SEM-EDX proved 92.60% Cr(III) adsorption on biofilms supported by coarse sand. Utilization of Bacillus biofilms for effective bioremoval of Cr(III) from chrome tanning effluent could be a better option for tannery industry, especially during post chrome tanning operation.

  17. Factors Regulating Microbial Biofilm Development in a System with Slowly Flowing Seawater

    OpenAIRE

    Pedersen, Karsten

    1982-01-01

    Microbial biofilm development was followed under growth conditions similar to those of a projected salinity power plant. Microscope glass cover slips were piled in biofilm reactors to imitate the membrane stacks in such a plant. A staining technique closely correlating absorbance values with biofilm dry weight was used for the study. Generally, the biofilms consisted of solitary and filamentous bacteria which were evenly distributed with considerable amounts of various protozoa and entrapped ...

  18. Evaluation of a hybrid anaerobic biofilm reactor treating winery effluents and using grape stalks as biofilm carrier.

    Science.gov (United States)

    Wahab, Mohamed Ali; Habouzit, Frédéric; Bernet, Nicolas; Jedidi, Naceur; Escudié, Renaud

    2016-07-01

    Wine production processes generate large amount of both winery wastewater and solid wastes. Furthermore, working periods, volumes and pollution loads greatly vary over the year. Therefore, it is recommended to develop a low-cost treatment technology for the treatment of winery effluents taking into account the variation of the organic loading rate (OLR). Accordingly, we have investigated the sequential operation of an anaerobic biofilm reactor treating winery effluents and using grape stalks (GSs) as biofilm carrier with an OLR ranging from 0.65 to 27 gCOD/L/d. The result showed that, during the start-up with wastewater influent, the chemical oxygen demand (COD) removal rate ranged from 83% to 93% and was about 91% at the end of the start-up period that lasted for 40 days. After 3 months of inactivity period of the reactor (no influent feeding), we have succeeded in restarting-up the reactor in only 15 days with a COD removal of 82% and a low concentration of volatile fatty acids (1 g/L), which confirms the robustness of the reactor. As a consequence, GSs can be used as an efficient carrier support, allowing a fast reactor start-up, while the biofilm conserves its activity during a non-feeding period. The proposed hybrid reactor thus permits to treat both winery effluents and GSs. PMID:26652186

  19. Biological Phosphorus Removal in a Moving Bed Biofilm Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Helness, Herman

    2007-09-15

    The scope of this study was to investigate use of the moving bed biofilm reactor (MBBR) process for biological phosphorus removal. The goal has been to describe the operating conditions required for biological phosphorus and nitrogen removal in a MBBR operated as a sequencing batch reactor (SBR), and determine dimensioning criteria for such a process

  20. Degradation Mechanisms of Colloidal Organic Matter in Biofilm Reactors

    DEFF Research Database (Denmark)

    Larsen, Tove; Harremoës, Poul

    1994-01-01

    The degradation mechanisms of colloidal organic matter in biofilm reactors have been studied in an idealized laboratory reactor system with soluble starch as a model substrate. Batch tests and experiments with different reactor configurations have shown that for this specific substrate, bulk liquid...... hydrolysis is the mechanism for transforming non-diffusible organic matter into biofilm diffusible substrate. A simplified mathematical description has led to the identification of the degree of hydrolysis, DH, as the parameter expressing the major difference between degradation of diffusible and non......-diffusible organic matter in a biofilm reactor. DH depends on the combined volumetric and surface hydraulic loading rate, Q2/(AV). In full-scale wastewater treatment plants, the degradation mechanism presented in this paper can explain important differences between the performance of trickling filters and RBC...

  1. Cell death in Pseudomonas aeruginosa biofilm development

    DEFF Research Database (Denmark)

    Webb, J.S.; Thompson, L.S.; James, S.;

    2003-01-01

    Bacteria growing in biofilms often develop multicellular, three-dimensional structures known as microcolonies. Complex differentiation within biofilms of Pseudomonas aeruginosa occurs, leading to the creation of voids inside microcolonies and to the dispersal of cells from within these voids....... However, key developmental processes regulating these events are poorly understood. A normal component of multicellular development is cell death. Here we report that a repeatable pattern of cell death and lysis occurs in biofilms of P. aeruginosa during the normal course of development. Cell death...... occurred with temporal and spatial organization within biofilms, inside microcolonies, when the biofilms were allowed to develop in continuous-culture flow cells. A subpopulation of viable cells was always observed in these regions. During the onset of biofilm killing and during biofilm development...

  2. Improved computational model (AQUIFAS) for activated sludge, integrated fixed-film activated sludge, and moving-bed biofilm reactor systems, part II: multilayer biofilm diffusional model.

    Science.gov (United States)

    Sen, Dipankar; Randall, Clifford W

    2008-07-01

    Research was undertaken to develop a diffusional model of the biofilm that can be applied in lieu of a semi-empirical model to upgrade an activated sludge system to an integrated fixed-film activated sludge (IFAS) or moving-bed biofilm reactor (MBBR) system. The model has been developed to operate with up to 12 cells (reactors) in series, with biofilm media incorporated to one or more of the zone cells, except the anaerobic zone cells. The values of the kinetic parameters for the model were measured using pilot-scale activated sludge, IFAS, and MBBR systems. The biofilm is divided into 12 layers and has a stagnant liquid layer. Diffusion and substrate utilization are calculated for each layer. The equations are solved simultaneously using a finite difference technique. The biofilm flux model is then linked to the activated sludge model. Advanced features include the ability to compute the biofilm thickness and the effect of biofilm thickness on performance. The biofilm diffusional model is also used to provide information and create a table of biofilm yields at different substrate concentrations that can be used in the semi-empirical model. PMID:18710146

  3. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    Directory of Open Access Journals (Sweden)

    Joe A. Lemire

    2015-10-01

    Full Text Available Moving bed biofilm reactors (MBBRs are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR carriers (biofilm support materials, allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that mixed-species biofilms can be harvested from an industrial wastewater inoculum [oil sands process water (OSPW] using the Calgary Biofilm Device (CBD. Moreover, the resultant biofilm communities had the capacity to degrade organic toxins (naphthenic acids—NAs that are found in OSPW. Therefore, we hypothesized that harnessing microbial communities from industrial wastewater, as biofilms, on MBBR carriers may be an effective method to bioremediate industrial wastewater.Here, we detail our methodology adapting the workflow employed for using the CBD, to generate inoculant carriers to seed an MBBR.In this study, OSPW-derived biofilm communities were successfully grown, and their efficacy evaluated, on commercially available MBBR carriers affixed within a modified CBD system. The resultant biofilms demonstrated the capacity to transfer biomass to recipient carriers within a scaled MBBR. Moreover, MBBR systems inoculated in this manner were fully active 2 days post-inoculation, and readily degraded a select population of NAs. Together, these findings suggest that harnessing microbial communities on carriers affixed within a modified CBD system may represent a facile and rapid method for obtaining functional inoculants for use in wastewater MBBR treatment systems.

  4. Anammox transited from denitrification in upflow biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shao-hui; ZHENG Ping; HUA Yu-mei

    2004-01-01

    Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen removal efficiency in the reactor transited from heterotrophic denitrification were higher than that in its counterpart. When the hydraulic retention time was 12 h or so, the total nitrogen loading rate was about 0.609 kg N/(m3·d), and the effluent ammonia and nitrite concentrations were less than 8.5 mg/L and 2.5 mg/L, respectively. The upflow anammox biofilm reactor was capable of keeping and accumulating the slow-growing bacteria efficiently. During operation of the reactor, the biomass color was gradually turned from brownish to red, and the ratio of ammonia consumption, nitrite consumption and nitrate production approached the theoretical one. These changes could be used as an indicator for working state of the reactor.

  5. The membrane biofilm reactor: the natural partnership of membranes and biofilm.

    Science.gov (United States)

    Rittmann, B E

    2006-01-01

    Many exciting new technologies for water-quality control combine microbiological processes with adsorption, advanced oxidation, a membrane or an electrode to improve performance, address emerging contaminants or capture renewable energy. An excellent example is the H2-based membrane biofilm reactor (MBfR), which delivers H2 gas to a biofilm that naturally accumulates on the outer surface of a bubbleless membrane. Autotrophic bacteria in the biofilm oxidise the H2 and use the electrons to reduce NO3-, CIO4- and other oxidised contaminants. This natural partnership of membranes and biofilm makes it possible to gain many cost, performance and simplicity advantages from using H2 as the electron donor for microbially catalysed reductions. The MBfR has been demonstrated for denitrification in drinking water; reduction of perchlorate in groundwater; reduction of selenate, chromate, trichloroethene and other emerging contaminants; advanced N removal in wastewater treatment and autotrophic total-N removal. PMID:16605035

  6. Biofilm technology : from support design to reactor operation

    OpenAIRE

    Matos, Maria F.; Alves, Cláudia; Brito, A. G.; R. Nogueira

    2008-01-01

    The aim of this work was to assess the feasibility of a Sequential Batch Biofilm Reactor (SBBR) to perform carbon and nitrogen removal: from support design to reactor operation. The experimental part was conducted in two phases. In the first phase, different supports were tested to select the most suitable one for SBBR operation. In the second phase, the most appropriate support was used in a SBBR to perform carbon and nitrogen removal. The results demonstrate that the support ...

  7. Microbiological and chemical approaches to degradation of mecoprop in a Moving-Bed Biofilm-Reactor

    DEFF Research Database (Denmark)

    Escola, Monica; Tue Kjærgaard Nielsen, Tue; Hansen, Lars Hestbjerg;

    Micro-pollutants are ubiquitous in wastewater effluents. Therefore, in-situ treatments of highly polluted water or polishing treatments after classical wastewater treatment have been proposed as a solution. Moving Bed Biofilm-Reactors (MBBRs) are a recent-developed biofilm technology for wastewater...... degradation and biofilm communities. This study wanted to answer howfocussed on the response of the microbial communities respond to the presence of micro-pollutants in different concentrations. To do this, MBBR chips, grown and used for wastewater effluent polishing, were exposed to the same real wastewater...... recalcitrant compounds. For all these reasonsThus, MBBRs are pointed as a valuable tool for the elimination of micro-pollutants. Several studies have focused in on describing degradation processes in biofilm by quantifying the loss of micro-pollutants over time. This can be helpful foraid optimizing...

  8. Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

    OpenAIRE

    Karcher Patrick; Ezeji Thaddeus C; Annous Bassam A; Qureshi Nasib; Maddox Ian S

    2005-01-01

    Abstract This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs/aggregates (also called granules) without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL-1 can be achieved. Th...

  9. Moving bed biofilm reactor technology: process applications, design, and performance.

    Science.gov (United States)

    McQuarrie, James P; Boltz, Joshua P

    2011-06-01

    The moving bed biofilm reactor (MBBR) can operate as a 2- (anoxic) or 3-(aerobic) phase system with buoyant free-moving plastic biofilm carriers. These systems can be used for municipal and industrial wastewater treatment, aquaculture, potable water denitrification, and, in roughing, secondary, tertiary, and sidestream applications. The system includes a submerged biofilm reactor and liquid-solids separation unit. The MBBR process benefits include the following: (1) capacity to meet treatment objectives similar to activated sludge systems with respect to carbon-oxidation and nitrogen removal, but requires a smaller tank volume than a clarifier-coupled activated sludge system; (2) biomass retention is clarifier-independent and solids loading to the liquid-solids separation unit is reduced significantly when compared with activated sludge systems; (3) the MBBR is a continuous-flow process that does not require a special operational cycle for biofilm thickness, L(F), control (e.g., biologically active filter backwashing); and (4) liquid-solids separation can be achieved with a variety of processes, including conventional and compact high-rate processes. Information related to system design is fragmented and poorly documented. This paper seeks to address this issue by summarizing state-of-the art MBBR design procedures and providing the reader with an overview of some commercially available systems and their components. PMID:21751715

  10. Biofilm development and enhanced stress resistance of a model, mixed-species community biofilm

    OpenAIRE

    Lee, Kai Wei Kelvin; Periasamy, Saravanan; Mukherjee, Manisha; Xie, Chao; Kjelleberg, Staffan; Rice, Scott A.

    2013-01-01

    Most studies of biofilm biology have taken a reductionist approach, where single-species biofilms have been extensively investigated. However, biofilms in nature mostly comprise multiple species, where interspecies interactions can shape the development, structure and function of these communities differently from biofilm populations. Hence, a reproducible mixed-species biofilm comprising Pseudomonas aeruginosa, Pseudomonas protegens and Klebsiella pneumoniae was adapted to study how interspe...

  11. Impact of Chloramination on the Development of Laboratory-Grown Biofilms Fed with Filter-Pretreated Groundwater

    OpenAIRE

    Ling, Fangqiong; Liu, Wen-Tso

    2012-01-01

    This study evaluated the continuous impact of monochloramine disinfection on laboratory-grown biofilms through the characterization of biofilm architecture and microbial community structure. Biofilm development and disinfection were achieved using CDC (Centers for Disease Control and Prevention) biofilm reactor systems with polyvinyl chloride (PVC) coupons as the substratum and sand filter-pretreated groundwater as the source of microbial seeding and growth nutrient. After 2 weeks of growth, ...

  12. Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

    Directory of Open Access Journals (Sweden)

    Karcher Patrick

    2005-08-01

    Full Text Available Abstract This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent or form flocs/aggregates (also called granules without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL-1 can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR, packed bed reactor (PBR, fluidized bed reactor (FBR, airlift reactor (ALR, upflow anaerobic sludge blanket (UASB reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes.

  13. Simultaneous removal of COD and nitrogen using a novel carbon-membrane aerated biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A membrane aerated biofilm reactor is a promising technology for wastewater treatment. In this study, a carbon-membrane aerated biofilm reactor (CMABR) has been developed, to remove carbon organics and nitrogen simultaneously from one reactor. The results showed that CMABR has a high chemical oxygen demand (COD) and nitrogen removal efficiency, as it is operated with a hydraulic retention time (HRT) of 20 h, and it also showed a perfect performance, even if the HRT was shortened to 12 h. In this period, the removal efficiencies of COD, ammonia nitrogen (NH4+-N), and total nitrogen (TN) reached 86%, 94%, and 84%, respectively. However,the removal efficiencies of NH4+-N and TN declined rapidly as the HRT was shortened to 8 h. This is because of the excessive growth of biomass on the nonwoven fiber and very high organic loading rate. The fluorescence in situ hybridization (FISH) analysis indicated that the ammonia oxidizing bacteria (AOB) were mainly distributed in the inner layer of the biofilm. The coexistence of AOB and eubacteria in one biofilm can enhance the simultaneous removal of COD and nitrogen.

  14. Oxygen Transfer Model for a Flow-Through Hollow-Fiber Membrane Biofilm Reactor

    DEFF Research Database (Denmark)

    Gilmore, K. R.; Little, J. C.; Smets, Barth F.;

    2009-01-01

    the biofilm present, oxygen transfer efficiencies between 30 and 55% were calculated from the measured data including the outlet gas oxygen concentration, ammonia consumption stoichiometry, and oxidized nitrogen production stoichiometry, all of which were in reasonable agreement. The mechanistic model......A mechanistic oxygen transfer model was developed and applied to a flow-through hollow-fiber membrane-aerated biofilm reactor. Model results are compared to conventional clean water test results as well as performance data obtained when an actively nitrifying biofilm was present on the fibers. With...... overpredicted the oxygen transfer by a factor of 1.3 relative to the result calculated from the outlet gas oxygen concentration, which was considered the most accurate of the measured benchmarks. A mass transfer coefficient derived from the clean water testing with oxygen sensors at the membrane...

  15. Impact of Chloramination on the Development of Laboratory-Grown Biofilms Fed with Filter-Pretreated Groundwater

    KAUST Repository

    Ling, Fangqiong

    2013-01-01

    This study evaluated the continuous impact of monochloramine disinfection on laboratory-grown biofilms through the characterization of biofilm architecture and microbial community structure. Biofilm development and disinfection were achieved using CDC (Centers for Disease Control and Prevention) biofilm reactor systems with polyvinyl chloride (PVC) coupons as the substratum and sand filter-pretreated groundwater as the source of microbial seeding and growth nutrient. After 2 weeks of growth, the biofilms were subjected to chloramination for 8 more weeks at concentrations of 7.5±1.4 to 9.1±0.4 mg Cl2 L-1. Control reactors received no disinfection during the development of biofilms. Confocal laser scanning microscopy and image analysis indicated that chloramination could lead to 81.4-83.5% and 86.3-95.6% reduction in biofilm biomass and thickness, respectively, but could not eliminate biofilm growth. 16S rRNA gene terminal restriction fragment length polymorphism analysis indicated that microbial community structures between chloraminated and non-chloraminated biofilms exhibited different successional trends. 16S rRNA gene pyrosequencing analysis further revealed that chloramination could select members of Actinobacteria and Acidobacteria as the dominant populations, whereas natural development leads to the selection of members of Nitrospira and Bacteroidetes as dominant biofilm populations. Overall, chloramination treatment could alter the growth of multi-species biofilms on the PVC surface, shape the biofilm architecture, and select a certain microbial community that can survive or proliferate under chloramination.

  16. Development of biofilm in anaerobic reactors treating wastewater from coffee grain processing Desenvolvimento de biofilme em reatores anaeróbios tratando água residuária do processamento dos frutos do cafeeiro

    Directory of Open Access Journals (Sweden)

    Fátima R. L. Fia

    2010-02-01

    Full Text Available In recent decades the use of anaerobic fixed bed reactors has been established in Brazil for the treatment of different effluents. As the capability of retaining microorganisms by support media (fixed bed is a factor influencing the performance of these reactors, the present study aims at evaluating the influence of three fixed bed on the effectiveness of treating an effluent with high pollution potential: wastewater from coffee grain processing (WCP, with organic matter concentrations varying from 812 to 5320 mg L-1 in the form of chemical oxygen demand (COD. Support media used for the immobilization of biomass were: blast furnace slag, polyurethane foam and #2 crushed stone with porosities of 53, 95 and 48%, respectively. The mean efficiency of COD removal in the reactor filled with polyurethane foam was 80%, attributed to its higher porosity index, which also provided greater retention and fixation of biomass which, when quantified as total volatile solids, was found to be 1301 mg g-1 of foam. The biofilm was made up of various microorganisms, including rod, curved rods, cocci, filaments and morphologies similar to Methanosaeta sp. and Methanosarcina sp.Nas últimas décadas tem-se registrado, no Brasil, o uso de reatores anaeróbios de leito fixo para o tratamento de diversos tipos de efluentes. Uma vez que a capacidade de retenção de micro-organismos pelo meio suporte (leito fixo é fator de influência no desempenho desses reatores, buscou-se, com a realização do presente estudo, avaliar a influência do leito fixo na eficiência de três unidades tratando um efluente com elevado potencial poluidor: água residuária do processamento dos frutos do cafeeiro (ARC, com concentração de matéria orgânica variando entre 812 e 5.320 mg L-1 na forma de DQO. Os tipos de suporte utilizados na imobilização da biomassa foram: escória de alto-forno, espuma de poliuretano e brita nº 2, com índice de vazios de 53, 95 e 48%, respectivamente. A

  17. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation

    DEFF Research Database (Denmark)

    Stapper, A.P.; Narasimhan, G.; Oman, D.E.;

    2004-01-01

    Extracellular polymers can facilitate the non-specific attachment of bacteria to surfaces and hold together developing biofilms. This study was undertaken to qualitatively and quantitatively compare the architecture of biofilms produced by Pseudomonas aeruginosa strain PAO1 and its alginate...... biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (BIP) and Community Statistics (COMSTAT) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating...... that the production of alginate is not critical for biofilm formation. Observation over a period of 5 days indicated a three-stage development pattern consisting of initiation, establishment and maturation. Furthermore, this study showed that phenotypically distinguishable biofilms can be...

  18. Assessing microbial competition in a hydrogen-based membrane biofilm reactor (MBfR) using multidimensional modeling.

    Science.gov (United States)

    Martin, Kelly J; Picioreanu, Cristian; Nerenberg, Robert

    2015-09-01

    The membrane biofilm reactor (MBfR) is a novel technology that safely delivers hydrogen to the base of a denitrifying biofilm via gas-supplying membranes. While hydrogen is an effective electron donor for denitrifying bacteria (DNB), it also supports sulfate-reducing bacteria (SRB) and methanogens (MET), which consume hydrogen and create undesirable by-products. SRB and MET are only competitive for hydrogen when local nitrate concentrations are low, therefore SRB and MET primarily grow near the base of the biofilm. In an MBfR, hydrogen concentrations are greatest at the base of the biofilm, making SRB and MET more likely to proliferate in an MBfR system than a conventional biofilm reactor. Modeling results showed that because of this, control of the hydrogen concentration via the intramembrane pressure was a key tool for limiting SRB and MET development. Another means is biofilm management, which supported both sloughing and erosive detachment. For the conditions simulated, maintaining thinner biofilms promoted higher denitrification fluxes and limited the presence of SRB and MET. The 2-d modeling showed that periodic biofilm sloughing helped control slow-growing SRB and MET. Moreover, the rough (non-flat) membrane assembly in the 2-d model provided a special niche for SRB and MET that was not represented in the 1-d model. This study compared 1-d and 2-d biofilm model applicability for simulating competition in counter-diffusional biofilms. Although more computationally expensive, the 2-d model captured important mechanisms unseen in the 1-d model. PMID:25854894

  19. Three-Dimensional Stratification of Bacterial Biofilm Populations in a Moving Bed Biofilm Reactor for Nitritation-Anammox

    Directory of Open Access Journals (Sweden)

    Robert Almstrand

    2014-01-01

    Full Text Available Moving bed biofilm reactors (MBBRs are increasingly used for nitrogen removal with nitritation-anaerobic ammonium oxidation (anammox processes in wastewater treatment. Carriers provide protected surfaces where ammonia oxidizing bacteria (AOB and anammox bacteria form complex biofilms. However, the knowledge about the organization of microbial communities in MBBR biofilms is sparse. We used new cryosectioning and imaging methods for fluorescence in situ hybridization (FISH to study the structure of biofilms retrieved from carriers in a nitritation-anammox MBBR. The dimensions of the carrier compartments and the biofilm cryosections after FISH showed good correlation, indicating little disturbance of biofilm samples by the treatment. FISH showed that Nitrosomonas europaea/eutropha-related cells dominated the AOB and Candidatus Brocadia fulgida-related cells dominated the anammox guild. New carriers were initially colonized by AOB, followed by anammox bacteria proliferating in the deeper biofilm layers, probably in anaerobic microhabitats created by AOB activity. Mature biofilms showed a pronounced three-dimensional stratification where AOB dominated closer to the biofilm-water interface, whereas anammox were dominant deeper into the carrier space and towards the walls. Our results suggest that current mathematical models may be oversimplifying these three-dimensional systems and unless the multidimensionality of these systems is considered, models may result in suboptimal design of MBBR carriers.

  20. Microbial community stratification in Membrane-Aerated Biofilm Reactors for Completely Autotrophic Nitrogen Removal

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Ruscalleda, Maël; Terada, Akihiko;

    bacterial granules or biofilms. In this sense, completely autotrophic nitrogen removal from high ammonium strength wastewater was achieved in a Membrane-Aereated Biofilm Reactor (MABR) in a single step. Here, a biofilm containing nitrifiers (Aerobic Ammonium and Nitrite Oxidizing Bacteria, AOB and NOB......Due to the necessity of a source of nitrite, most of the processes involving Anaerobic Ammonium Oxidation (Anammox) are based on a separated two-step process with a previous partial-nitritation reactor. However, these two processes can occur simultaneously in the same reactor by taking advantage of......, respectively) and Anaerobic Ammonium Oxidizing Bacteria (AnAOB) is grown on bubbleless aeration membranes to remove ammonium. Since oxygen permeates through the membrane-biofilm interface while ammonium diffuses into the biofilm from the biofilm-liquid interface, oxygen gradients can be established across the...

  1. Comparative Kinetic Studies and Performance Evaluation of Biofilm and Biomass Characteristics of Pseudomonas fluorescens in Degrading Synthetic Phenolic Effluent in Inverse Fluidized Bed Biofilm Reactor.

    Science.gov (United States)

    Begum, S Sabarunisha; Radha, K V

    2016-05-01

    The bioremediation potential of Pseudomonas fluorescens was studied in an Inverse Fluidized Bed Biofilm Reactor under batch recirculation conditions using synthetic phenolic effluent of various concentrations (400, 600, 800, 1000 and 1200 mg/l). The performance of the reactor was investigated and the characteristics of biomass and biofilm were determined by evaluating biofilm dry density and thickness, bioparticle density, suspended and attached biomass concentration, chemical oxygen demand and phenol removal efficiency. Biodegradation kinetics had been studied for suspended biomass culture and biofilm systems with respect to its specific growth and substrate consumption rates. Suspended biomass followed substrate inhibition kinetics and the experimental data fitted well with the Haldane model. The degradation kinetic behavior of biofilm revealed that a well adapted biofilm system with effective control of biofilm thickness in an inverse fluidized bed biofilm reactor overcomes substrate inhibition effects by tolerating higher phenol concentration and fitted well to the Monod model. PMID:27131305

  2. The composition and compression of biofilms developed on ultrafiltration membranes determine hydraulic biofilm resistance.

    Science.gov (United States)

    Derlon, Nicolas; Grütter, Alexander; Brandenberger, Fabienne; Sutter, Anja; Kuhlicke, Ute; Neu, Thomas R; Morgenroth, Eberhard

    2016-10-01

    This study aimed at identifying how to improve the level of permeate flux stabilisation during gravity-driven membrane filtration without control of biofilm formation. The focus was therefore on understanding (i) how the different fractions of the biofilms (inorganics particles, bacterial cells, EPS matrix) influence its hydraulic resistance and (ii) how the compression of biofilms impacts its hydraulic resistance, i.e., can water head be increased to increase the level of permeate flux stabilisation. Biofilms were developed on ultrafiltration membranes at 88 and 284 cm water heads with dead-end filtration for around 50 days. A larger water head resulted in a smaller biofilm permeability (150 and 50 L m(-2) h(-1) bar(-1) for biofilms grown at 88 cm and 284 cm water head, respectively). Biofilms were mainly composed of EPS (>90% in volume). The comparison of the hydraulic resistances of biofilms to model fouling layers indicated that most of the hydraulic resistance is due to the EPS matrix. The compressibility of the biofilm was also evaluated by subjecting the biofilms to short-term (few minutes) and long-term variations of transmembrane pressures (TMP). A sudden change of TMP resulted in an instantaneous and reversible change of biofilm hydraulic resistance. A long-term change of TMP induced a slow change in the biofilm hydraulic resistance. Our results demonstrate that the response of biofilms to a TMP change has two components: an immediate variation of resistance (due to compression/relaxation) and a long-term response (linked to biofilm adaptation/growth). Our results provide relevant information about the relationship between the operating conditions in terms of TMP, the biofilm structure and composition and the resulting biofilm hydraulic resistance. These findings have practical implications for a broad range of membrane systems. PMID:27318448

  3. BIODEGRADATION OF AROMATIC AMINE COMPOUNDS USING MOVING BED BIOFILM REACTORS

    Directory of Open Access Journals (Sweden)

    M. Delnavaz ، B. Ayati ، H. Ganjidoust

    2008-10-01

    Full Text Available Three moving bed biofilm reactors were used to treat synthesized wastewater of aromatic amine compounds including aniline, para-diaminobenzene and para-aminophenol that are found in many industrial wastewaters. The reactors with cylindrical shape had an internal diameter and an effective depth of 10 and 60 cm, respectively. The reactors were filled with light expanded clay aggregate as carriers and operated in an aerobic batch and continuous conditions. Evaluation of the reactors' efficiency was done at different retention time of 8, 24, 48 and 72 h with an influent COD from 100 to 3500 mg/L (filling ratio of 50%. The maximum obtained removal efficiencies were 90% (influent COD=2000 mg/L, 87% (influent COD=1000 mg/L and 75% (influent COD=750 mg/L for aniline, para-diaminobenzene and para-aminophenol, respectively. In the study of decrease in filling ratio from 50 to 30 percent, 6% decrease for both para-diaminobenzene and para-aminophenol and 7% increase for aniline degradation were obtained. The removal efficiency was decreased to about 10% after 15 days of continuous loading for each of the above three substrates. In the shock loading test, initially the COD removal rate was decreased in all reactors, but after about 10 days, it has been approached to the previous values. Finally, biodegradability of aromatic amines has been proved by nuclear magnetic resonance system.

  4. Anaerobic granular sludge and biofilm reactors

    DEFF Research Database (Denmark)

    Skiadas, Ioannis V.; Gavala, Hariklia N.; Schmidt, Jens Ejbye; Ahring, Birgitte Kiær

    2003-01-01

    role of the anaerobic digestion in the wastewater treatment plants from a pre-treatment method to the main biological treatment method. The application of staged high-rate anaerobic digesters has shown the larger potential among the recent developments in this direction. The most common high...

  5. In situ molecular imaging of hydrated biofilm in a microfluidic reactor by ToF-SIMS

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Xin; Yu, Xiao-Ying; Wang, Zhaoying; Yang, Li; Liu, Bingwen; Zhu, Zihua; Tucker, Abigail E.; Chrisler, William B.; Hill, Eric A.; Thevuthasan, Suntharampillai; Lin, Yuehe; Liu, Songqin; Marshall, Matthew J.

    2014-02-26

    The first results of using a novel single channel microfluidic reactor to enable Shewanella biofilm growth and in situ characterization using time-of-flight secondary ion mass spectrometry (ToF-SIMS) in the hydrated environment are presented. The new microfluidic interface allows direct probing of the liquid surface using ToF-SIMS, a vacuum surface technique. The detection window is an aperture of 2 m in diameter on a thin silicon nitride (SiN) membrane and it allows direct detection of the liquid surface. Surface tension of the liquid flowing inside the microchannel holds the liquid within the aperture. ToF-SIMS depth profiling was used to drill through the SiN membrane and the biofilm grown on the substrate. In situ 2D imaging of the biofilm in hydrated state was acquired, providing spatial distribution of the chemical compounds in the biofilm system. This data was compared with a medium filled microfluidic reactor devoid of biofilm and dried biofilm samples deposited on clean silicon wafers. Principle Component Analysis (PCA) was used to investigate these observations. Our results show that imaging biofilms in the hydrated environment using ToF-SIMS is possible using the unique microfluidic reactor. Moreover, characteristic biofilm fatty acids fragments were observed in the hydrated biofilm grown in the microfluidic channel, illustrating the advantage of imaging biofilm in its native environment.

  6. Biodegradation of pharmaceuticals in hospital wastewater by staged Moving Bed Biofilm Reactors (MBBR)

    DEFF Research Database (Denmark)

    Escola Casas, Monica; Chhetri, Ravi Kumar; Ooi, Gordon Tze Hoong;

    2015-01-01

    Hospital wastewater contributes a significant input of pharmaceuticals into municipal wastewater. The combination of suspended activated sludge and biofilm processes, as stand-alone or as hybrid process (hybrid biofilm and activated sludge system (Hybas™)) has been suggested as a possible solution...... for hospital wastewater treatment. To investigate the potential of such a hybrid system for the removal of pharmaceuticals in hospital wastewater a pilot plant consisting of a series of one activated sludge reactor, two Hybas™ reactors and one moving bed biofilm reactor (MBBR) has been established and...

  7. Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor

    International Nuclear Information System (INIS)

    Highlights: → Intensified biofilm-electrode reactor using cooperative denitrification is developed. → IBER combines heterotrophic and autotrophic denitrification. → CO2 formed by heterotrophic denitrification is used by autotrophic bacteria. → Optimum running conditions are C/N = 0.75, HRT = 8 h, and I = 40 mA. → A novel degradation mechanism for cooperating denitrification process is proposed. - Abstract: An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO3-N50 mg L-1) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8 h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO3-N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO2 produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate.

  8. Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yingxin [School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 3058572 (Japan); Feng, Chuanping, E-mail: fengchuangping@gmail.com [School of Water Resources and Environment, China University of Geosciences, Beijing 100083 (China); Wang, Qinghong; Yang, Yingnan; Zhang, Zhenya; Sugiura, Norio [Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 3058572 (Japan)

    2011-09-15

    Highlights: {yields} Intensified biofilm-electrode reactor using cooperative denitrification is developed. {yields} IBER combines heterotrophic and autotrophic denitrification. {yields} CO{sub 2} formed by heterotrophic denitrification is used by autotrophic bacteria. {yields} Optimum running conditions are C/N = 0.75, HRT = 8 h, and I = 40 mA. {yields} A novel degradation mechanism for cooperating denitrification process is proposed. - Abstract: An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO{sub 3}{sup -}N50 mg L{sup -1}) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8 h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO{sub 3}{sup -}N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO{sub 2} produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate.

  9. Performance comparison of biofilm and suspended sludge from a sequencing batch biofilm reactor treating mariculture wastewater under oxytetracycline stress.

    Science.gov (United States)

    Zheng, Dong; Gao, Mengchun; Wang, Zhe; She, Zonglian; Jin, Chunji; Chang, Qingbo

    2016-09-01

    The performance, extracellular polymeric substances (EPS) and microbial community of a sequencing batch biofilm reactor (SBBR) were investigated in treating mariculture wastewater under oxytetracycline stress. The chemical oxygen demand and [Formula: see text]-N removal efficiencies of the SBBR decreased with the increase of oxytetracycline concentration, and no obvious [Formula: see text]-N and [Formula: see text]-N accumulation in the effluent appeared at less than 10 mg L(-1) oxytetracycline. The specific oxygen utilization rate of the suspended sludge was more than that of the biofilm at different oxytetracycline concentrations. The specific ammonium oxidation rate (SAOR) of the biofilm was more easily affected by oxytetracycline than that of the suspended sludge, whereas the effect of oxytetracycline on the specific nitrite oxidation rate (SNOR) of the biofilm was less than that of the suspended sludge. The specific nitrate reduction rate of both the biofilm and suspended sludge was higher than the sum of the SAOR and SNOR at different oxytetracycline concentrations. The protein and polysaccharide contents in the EPS of the biofilm and suspended sludge increased with the increase of oxytetracycline concentration. The appearance of oxytetracycline in the influent could affect the chemical composition of the loosely bound EPS and tightly bound EPS. The amino, carboxyl and hydroxyl groups might be involved with interaction between EPS and oxytetracycline. The denaturing gradient gel electrophoresis profiles indicated that the variation of oxytetracycline concentration in the influent could affect the microbial communities of both the biofilm and suspended sludge. PMID:26854088

  10. Treatemnt of Wastewater with Modified Sequencing Batch Biofilm Reactor Technology

    Institute of Scientific and Technical Information of China (English)

    胡龙兴; 刘宇陆

    2002-01-01

    This paper describes the removel of COD and nitrogen from wastewater with modified sequencing batch biofilm reactor,The strategy of simultaneous feeding and draining was explored.The results show that introduction of a new batch of wastewater and withdrawal of the purifeid water can be conducted simultaneously with the maximum volumetric exchange rate of about 70%,Application of this feeding and draining mode leads to the reduction of the cycle time,the increase of the utilization of the reactor volume and the simplification of the reactor structure.The treatment of a synthetic wastewater containing COD and nitrogen was investigated.The operation mode of F(D)-O(i.e.,simultaneous feeding and draining followed by the aerobic condition)was adopted.It was found that COD was degraded very fast in the initial reaction period of time,then reduced slowly and the ammonia nitrogen and nitrate nitrogen concentrations decreased and increased with time respectively,while the nitrite nitrogen level increased first and then reduced.The relationship between the COD or ammonia nitrogen loading and its removal rate was examined,and the removal of COD,ammonia nitrogen and total nitrogen could exceed 95%,90%and 80% respectively,The fact that nitrogen could e removed more completely under constant aeration(aerobic condition)of the SBBR operation mode is very interesting and could be explained in several respects.

  11. Hydrolyzed polyacrylamide biodegradation and mechanism in sequencing batch biofilm reactor.

    Science.gov (United States)

    Yan, Miao; Zhao, Lanmei; Bao, Mutai; Lu, Jinren

    2016-05-01

    An investigation was performed to study the performance of a sequencing batch biofilm reactor (SBBR) to treat hydrolyzed polyacrylamides (HPAMs) and to determine the mechanisms of HPAM biodegradation. The mechanisms for the optimized parameters that significantly improved the degradation efficiency of the HPAMs were investigated by a synergistic effect of the co-metabolism in the sludge and the enzyme activities. The HPAM and TOC removal ratio reached 54.69% and 70.14%. A significant decrease in the total nitrogen concentration was measured. The carbon backbone of the HPAMs could be degraded after the separation of the amide group according to the data analysis. The HPLC results indicated that the HPAMs could be converted to polymer fragments without the generation of the acrylamide monomer intermediate. The results from high-throughput sequencing analysis revealed proteobacterias, bacteroidetes and planctomycetes were the key microorganisms involved in the degradation. PMID:26896716

  12. Hydraulic retention time effects on wastewater nutrient removal and bioproduct production via rotating algal biofilm reactor.

    Science.gov (United States)

    Iman Shayan, Sahand; Agblevor, Foster A; Bertin, Lorenzo; Sims, Ronald C

    2016-07-01

    Rotating algal biofilm reactor (RABR) technology was successfully employed in an effective strategy to couple the removal of wastewater nutrients with accumulation of valuable bioproducts by grown algae. A secondary stage municipal wastewater was fed to the developed system and the effects of the hydraulic retention time (HRT) parameter on both nutrient removal and bioproduct production were evaluated under fed-batch operation mode. Two sets of bench scale RABRs were designed and operated with HRTs of 2 and 6days in order to provide competitive environment for algal growth. The HRT significantly affected nitrogen and phosphorus uptakes along with lipid and starch accumulations by microalgae in harvested biofilms. Domination of nitrogen removal in 2-day HRT with higher lipid accumulation (20% on dried weight basis) and phosphorus removal in 6-day HRT with higher starch production (27% on dried weight basis) was observed by comparing the performances of the RABRs in duplicate runs. PMID:27038261

  13. Biofilm Community Dynamics in Bench-Scale Annular Reactors Simulating Arrestment of Chloraminated Drinking Water Nitrification

    Science.gov (United States)

    Annular reactors (ARs) were used to study biofilm community succession and provide an ecological insight during nitrification arrestment through simultaneously increasing monochloramine (NH2Cl) and chlorine to nitrogen mass ratios, resulting in four operational periods (I to IV)....

  14. Population changes in a biofilm reactor for phosphorus removal as evidenced by the use of FISH

    DEFF Research Database (Denmark)

    Falkentoft, C.M.; Müller, E.; Arnz, P.;

    2002-01-01

    Induction ofdenitrification was investigated for a lab-scale phosphate removing biofilm reactor where oxygen was replaced with nitrate as the electron acceptor. Acetate was used as the carbon source. The original biofilm (acclimatised with oxygen) was taken from a well-established large-scale rea......Induction ofdenitrification was investigated for a lab-scale phosphate removing biofilm reactor where oxygen was replaced with nitrate as the electron acceptor. Acetate was used as the carbon source. The original biofilm (acclimatised with oxygen) was taken from a well-established large......, phosphate removing biofilm belonged to the beta subclass of Proteobacteria. The applied set ofgene probes had been selected based on existing literature on biological phosphate removing organisms and included a recently published probe for a Rhodocyclus-like clone. However, none ofthe specific probes...

  15. Air-lift internal loop biofilm reactor for realized simultaneous nitrification and denitrification.

    Science.gov (United States)

    Zhang, Cuiyi; Wang, Lu; Yan, Ning; Zhang, Yongming; Liu, Rui

    2013-05-01

    Simultaneous nitrification and denitrification (SND) was realized by means of a novel air-lift internal loop biofilm reactor, in which aeration was set in middle of the reactor. During operation, the aeration was adjusted to get appropriate dissolve oxygen (DO) in bulk solution and let aerobic and anoxic zone coexist in one reactor. When aeration was at 0.6 and 0.2 L/min, corresponding to DO of 5.8 and 2.5 mg/L in bulk solution, ammonia nitrogen removal percentage reached about 80 and 90 %, but total nitrogen removal percentage was lower than 25 %. While the aeration was reduced to 0.1 L/min, aerobic and anoxic zones existed simultaneously in one reactor to get 75 % of ammonia nitrogen and 50 % of total nitrogen removal percentage. Biofilms were, respectively, taken from aerobic and anoxic zone to verify their function of nitrification and denitrification in two flasks, in which ammonia nitrogen was transferred into nitrate completely by aerobic biofilm, and nitrate was removed more than 80 % by anoxic biofilm. Microelectrode was used to measure the DO distribution inside biofilms in anoxic zone corresponding to different aerations. When aeration was at 0.6 and 0.2 L/min, DO inside biofilm was more than 1.5 mg/L, but the DO inside biofilm decreased to anoxic status with depth of biofilm increasing corresponding to aeration of 0.1 L/min. The experimental results indicated that SND could be realized because of simultaneous existence of aerobic and anoxic biofilms in one reactor. PMID:23001679

  16. Evaluation of Anaerobic Biofilm Reactor Kinetic Parameters Using Ant Colony Optimization.

    Science.gov (United States)

    Satya, Eswari Jujjavarapu; Venkateswarlu, Chimmiri

    2013-09-01

    Fixed bed reactors with naturally attached biofilms are increasingly used for anaerobic treatment of industry wastewaters due their effective treatment performance. The complex nature of biological reactions in biofilm processes often poses difficulty in analyzing them experimentally, and mathematical models could be very useful for their design and analysis. However, effective application of biofilm reactor models to practical problems suffers due to the lack of knowledge of accurate kinetic models and uncertainty in model parameters. In this work, an inverse modeling approach based on ant colony optimization is proposed and applied to estimate the kinetic and film thickness model parameters of wastewater treatment process in an anaerobic fixed bed biofilm reactor. Experimental data of pharmaceutical industry wastewater treatment process are used to determine the model parameters as a consequence of the solution of the rigorous mathematical models of the process. Results were evaluated for different modeling configurations derived from the combination of mathematical models, kinetic expressions, and optimization algorithms. Analysis of results showed that the two-dimensional mathematical model with Haldane kinetics better represents the pharmaceutical wastewater treatment in the biofilm reactor. The mathematical and kinetic modeling of this work forms a useful basis for the design and optimization of industry wastewater treating biofilm reactors. PMID:24065871

  17. Characterization of Biofilm in 200W Fluidized Bed Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Michelle H.; Saurey, Sabrina D.; Lee, Brady D.; Parker, Kent E.; Eisenhauer, Emalee ER; Cordova, Elsa A.; Golovich, Elizabeth C.

    2014-09-29

    Contaminated groundwater beneath the 200 West Area at the Hanford Site in Southeast Washington is currently being treated using a pump and treat system to remove organics, inorganics, radionuclides, and metals. A granular activated carbon-based fluidized bed reactor (FBR) has been added to remove nitrate, hexavalent chromium and carbon tetrachloride. Initial analytical results indicated the microorganisms effectively reduced many of the contaminants to less than cleanup levels. However shortly thereafter operational upsets of the FBR include carbon carry over, over production of microbial extracellular polymeric substance (biofilm) materials, and over production of hydrogen sulfide. As a result detailed investigations were undertaken to understand the functional diversity and activity of the microbial community present in the FBR over time. Molecular analyses including terminal restriction fragment length polymorphism analysis, quantitative polymerase chain reaction and fluorescent in situ hybridization analyses were performed on the microbial community extracted from the biofilm within the bed and from the inoculum, to determine functional dynamics of the FBR bed over time and following operational changes. Findings from these analyses indicated: 1) the microbial community within the bed was completely different than community used for inoculation, and was likely from the groundwater; 2) analyses early in the testing showed an FBR community dominated by a few Curvibacter and Flavobacterium species; 3) the final sample taken indicated that the microbial community in the FBR bed had become more diverse; and 4) qPCR analyses indicated that bacteria involved in nitrogen cycling, including denitrifiers and anaerobic ammonia oxidizing bacteria, were dominant in the bed. These results indicate that molecular tools can be powerful for determining functional diversity within FBR type reactors. Coupled with micronutrient, influent and effluent chemistry evaluations, a more

  18. Treatment of domestic wastewater in an up-flow anaerobic sludge blanket reactor followed by moving bed biofilm reactor

    NARCIS (Netherlands)

    Tawfik, A.; El-Gohary, F.; Temmink, B.G.

    2010-01-01

    The performance of a laboratory-scale sewage treatment system composed of an up-flow anaerobic sludge blanket (UASB) reactor and a moving bed biofilm reactor (MBBR) at a temperature of (22-35 A degrees C) was evaluated. The entire treatment system was operated at different hydraulic retention times

  19. Membrane biofilm reactors for nitrogen removal: state-of-the-art and research needs.

    Science.gov (United States)

    Hwang, Jong Hyuk; Cicek, Nazim; Oleszkiewicz, Jan A

    2009-01-01

    Historical developments up-to-date and operational challenges of membrane biofilm reactor (MBfR) were reviewed. A database of international, peer-reviewed journal articles regarding MBfR research from 1984 to 2008 was established and analyzed with a total of 107 papers. MBfR studies began to evolve in the early 1980s, since then the number of published papers increased steadily. After 2000, geographic locations where the research was conducted widened beyond North America and Europe to Asia. Research studies were divided into 4 categories and reviewed according to their main research focuses. In spite of the short history of MBfRs, studies have shown promising potential, possibly extending their application beyond nitrogen removal and organics removal. The MBfR research branched out to new fields including autotrophic denitrification. There are some important aspects of MBfRs that pose significant challenges to the application of this technology on a commercial scale in the near-future. The main challenge revolves around biofilm thickness and activity control. Further laboratory and demonstration scale studies on some of the proposed strategies for biofilm control are needed. Ultimately, more field studies with real wastewater should be performed to evaluate the resilience of the process in the face of flow and strength fluctuations, establishing optimum operational strategies. PMID:19934494

  20. A study on the use of the BioBall® as a biofilm carrier in a sequencing batch reactor.

    Science.gov (United States)

    Masłoń, Adam; Tomaszek, Janusz A

    2015-11-01

    Described in this study are experiments conducted to evaluate the removal of organics and nutrients from synthetic wastewater by a moving bed sequencing batch biofilm reactor using BioBall® carriers as biofilm media. The work involving a 15L-laboratory scale MBSBBR (moving bed sequencing batch biofilm reactor) model showed that the wastewater treatment system was based on biochemical processes taking place with activated sludge and biofilm microorganisms developing on the surface of the BioBall® carriers. Classical nitrification and denitrification and the typical enhanced biological phosphorus removal process were achieved in the reactor analyzed, which operated with a volumetric organic loading of 0.84-0.978gCODL(-1)d(-1). The average removal efficiencies for COD, total nitrogen and total phosphorus were found to be 97.7±0.5%, 87.8±2.6% and 94.3±1.3%, respectively. Nitrification efficiency reached levels in the range 96.5-99.7%. PMID:26298401

  1. Development of biofilm in anaerobic reactors treating wastewater from coffee grain processing Desenvolvimento de biofilme em reatores anaeróbios tratando água residuária do processamento dos frutos do cafeeiro

    OpenAIRE

    Fátima R. L. Fia; Alisson C. Borges; Antonio T. de Matos; Iolanda C. S. Duarte; Ronaldo Fia; Lidiane C. de Campos

    2010-01-01

    In recent decades the use of anaerobic fixed bed reactors has been established in Brazil for the treatment of different effluents. As the capability of retaining microorganisms by support media (fixed bed) is a factor influencing the performance of these reactors, the present study aims at evaluating the influence of three fixed bed on the effectiveness of treating an effluent with high pollution potential: wastewater from coffee grain processing (WCP), with organic matter concentrations vary...

  2. Biofilms

    OpenAIRE

    López, Daniel; Vlamakis, Hera; Kolter, Roberto

    2010-01-01

    The ability to form biofilms is a universal attribute of bacteria. Biofilms are multicellular communities held together by a self-produced extracellular matrix. The mechanisms that different bacteria employ to form biofilms vary, frequently depending on environmental conditions and specific strain attributes. In this review, we emphasize four well-studied model systems to give an overview of how several organisms form biofilms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and ...

  3. Nitrate removal from groundwater by a novel three-dimensional electrode biofilm reactor

    International Nuclear Information System (INIS)

    The contamination of nitrate in groundwater has become an ever-increasing environmental problem. To improve denitrification rate effectively, a novel three-dimensional (3D) bio-electrochemical reactor was developed, which introduced activated carbon (AC) into the cathode chamber as the third bipolar electrode. The influence parameters such as temperature, pH, current and initial nitrate loading were investigated systematically. The role of the third electrode was explored and a possible denitrification mechanism was suggested. The presence of AC not only provided much more sites for biofilm formation and hydrogen gas yield, but also produced carbon dioxide to afford a favorable anoxic environment. Thus, the 3D reactor showed good denitrification performance in wider conditions. The denitrification rate could reach 0.222 mg NO3 N/cm2/d while the current efficiency could reach as high as 227%, indicating promising for nitrate removal from groundwater

  4. Biohydrogen production from diary processing wastewater by anaerobic biofilm reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rios-Gonzalez, L.J.; Moreno-Davila, I.M.; Rodriguez-Martinez, J.; Garza-Garcia, Y. [Universidad Autonoma de Coahuila, Saltillo, Coahuila (Mexico)]. E-mail: leopoldo.rios@mail.uadec.mx

    2009-09-15

    This article describes biological hydrogen production from diary wastewater via anaerobic fermentation using pretreated heat shock (100 degrees Celsius, 30 min.) and acid (pH 3.0, 24 h) treatment procedures to selectively enrich the hydrogen producing mixed consortia prior to inoculation to batch reactors. Bioreactor used for immobilization consortia was operated at mesophilic (room) temperature (20{+-}3 degrees Celsius), under acidophilic conditions (pH 4.0-4.5), HRT (2h), and a natural support for generate hydrogen producing mixed consortia biofilm: Opuntia imbricata. Reactor was initially operated with sorbitol (5g/L) for 60 days of operation. Batch tests were conducted using 20{+-}0.02g of natural support with biofilm. Batch experiments were conducted to investigate the effect of COD (2.9-21.1 g-COD/L), at initial pH of 7.0, 32{+-}1 degrees Celsius. Maximum hydrogen yield was obtained at 21.1 g-COD/L. Experiments of pH effect were conducted using the optimal substrate concentration (21.2 g-COD/L), at pH 4 to 7 and 11.32 (pH diary wastewater) ,and 32{+-}1 degrees Celsius. Experiments results indicate the optimum initial cultivation was pH 4.0, but we can consider also a stable hydrogen production at pH 11.32 (pH diary wastewater), so we can avoid to fit the pH, and use diary wastewater as it left the process of cheese manufacture. The operational pH of 4.0 is 1.5 units below that of previously reported hydrogen producing organisms. The influence of the effect of temperature were conducted using the optimal substrate concentration (21.2 g-COD/L), two pH levels: 4.0 and 11.32, and four different temperatures: 16{+-}3 degrees Celsius (room temperature), 3 C, 45{+-}1 degrees Celsius y 55{+-}1 degrees Celsius.Optimal temperature for hydrogen production from diary wastewater at pH 4.0 was 55{+-}1 degrees Celsius, and for pH 11.32 was 16{+-}3 degrees Celsius.Therefore, the results suggests biofilm reactors in a natural support like Opuntia imbricata have good potential

  5. Assembly and development of the Pseudomonas aeruginosa biofilm matrix.

    OpenAIRE

    Luyan Ma; Matthew Conover; Haiping Lu; Parsek, Matthew R.; Kenneth Bayles; Wozniak, Daniel J.

    2009-01-01

    Virtually all cells living in multicellular structures such as tissues and organs are encased in an extracellular matrix. One of the most important features of a biofilm is the extracellular polymeric substance that functions as a matrix, holding bacterial cells together. Yet very little is known about how the matrix forms or how matrix components encase bacteria during biofilm development. Pseudomonas aeruginosa forms environmentally and clinically relevant biofilms and is a paradigm organis...

  6. Temporal and Stochastic Control of Staphylococcus aureus Biofilm Development

    OpenAIRE

    Moormeier, Derek E.; Bose, Jeffrey L.; Horswill, Alexander R.; Bayles, Kenneth W.

    2014-01-01

    ABSTRACT Biofilm communities contain distinct microniches that result in metabolic heterogeneity and variability in gene expression. Previously, these niches were visualized within Staphylococcus aureus biofilms by observing differential expression of the cid and lrg operons during tower formation. In the present study, we examined early biofilm development and identified two new stages (designated “multiplication” and “exodus”) that were associated with changes in matrix composition and a di...

  7. Pseudomonas aeruginosa Displays Multiple Phenotypes during Development as a Biofilm

    OpenAIRE

    Sauer, Karin; Anne K. Camper; Ehrlich, Garth D.; Costerton, J. William; Davies, David G

    2002-01-01

    Complementary approaches were employed to characterize transitional episodes in Pseudomonas aeruginosa biofilm development using direct observation and whole-cell protein analysis. Microscopy and in situ reporter gene analysis were used to directly observe changes in biofilm physiology and to act as signposts to standardize protein collection for two-dimensional electrophoretic analysis and protein identification in chemostat and continuous-culture biofilm-grown populations. Using these appro...

  8. Inverse modeling approach for evaluation of kinetic parameters of a biofilm reactor using tabu search.

    Science.gov (United States)

    Kumar, B Shiva; Venkateswarlu, Ch

    2014-08-01

    The complex nature of biological reactions in biofilm reactors often poses difficulties in analyzing such reactors experimentally. Mathematical models could be very useful for their design and analysis. However, application of biofilm reactor models to practical problems proves somewhat ineffective due to the lack of knowledge of accurate kinetic models and uncertainty in model parameters. In this work, we propose an inverse modeling approach based on tabu search (TS) to estimate the parameters of kinetic and film thickness models. TS is used to estimate these parameters as a consequence of the validation of the mathematical models of the process with the aid of measured data obtained from an experimental fixed-bed anaerobic biofilm reactor involving the treatment of pharmaceutical industry wastewater. The results evaluated for different modeling configurations of varying degrees of complexity illustrate the effectiveness of TS for accurate estimation of kinetic and film thickness model parameters of the biofilm process. The results show that the two-dimensional mathematical model with Edward kinetics (with its optimum parameters as mu(max)rho(s)/Y = 24.57, Ks = 1.352 and Ki = 102.36) and three-parameter film thickness expression (with its estimated parameters as a = 0.289 x 10(-5), b = 1.55 x 10(-4) and c = 15.2 x 10(-6)) better describes the biofilm reactor treating the industry wastewater. PMID:25306783

  9. Complete degradation of polychlorinated hydrocarbons by a two-stage biofilm reactor.

    OpenAIRE

    Fathepure, B Z; Vogel, T M

    1991-01-01

    A two-stage anaerobic-aerobic biofilm reactor successfully degraded a mixture of chlorinated organic compounds to water-soluble metabolic intermediates and carbon dioxide. Reductive dechlorination of hexachlorobenzene (HCB), tetrachloroethylene (PCE), and chloroform (CF) occurred on all tested primary carbon sources such as glucose, methanol, and acetate. However, the extent of dechlorination was maximum when the anaerobic biofilm column was fed acetate as a primary carbon source. HCB, PCE, a...

  10. Current Trends in Development of Liposomes for Targeting Bacterial Biofilms.

    Science.gov (United States)

    Rukavina, Zora; Vanić, Željka

    2016-01-01

    Biofilm targeting represents a great challenge for effective antimicrobial therapy. Increased biofilm resistance, even with the elevated concentrations of very potent antimicrobial agents, often leads to failed therapeutic outcome. Application of biocompatible nanomicrobials, particularly liposomally-associated nanomicrobials, presents a promising approach for improved drug delivery to bacterial cells and biofilms. Versatile manipulations of liposomal physicochemical properties, such as the bilayer composition, membrane fluidity, size, surface charge and coating, enable development of liposomes with desired pharmacokinetic and pharmacodynamic profiles. This review attempts to provide an unbiased overview of investigations of liposomes destined to treat bacterial biofilms. Different strategies including the recent advancements in liposomal design aiming at eradication of existing biofilms and prevention of biofilm formation, as well as respective limitations, are discussed in more details. PMID:27231933

  11. Development and maturation of Escherichia coli K-12 biofilms

    DEFF Research Database (Denmark)

    Reisner, A.; Haagensen, J.A.J.; Schembri, Mark;

    2003-01-01

    The development and maturation of E. coli biofilms in flow-chambers was investigated. We found that the presence of transfer constitutive IncF plasmids induced biofilm development forming structures resembling those reported for Pseudomonas aeruginosa . The development occurred in a step-wise pro......The development and maturation of E. coli biofilms in flow-chambers was investigated. We found that the presence of transfer constitutive IncF plasmids induced biofilm development forming structures resembling those reported for Pseudomonas aeruginosa . The development occurred in a step....... We further provide evidence that flagella, type 1 fimbriae, curli and Ag43 are all dispensable for the observed biofilm maturation. In addition, our results indicate that cell-to-cell signalling mediated by autoinducer 2 (AI-2) is not required for differentiation of E. coli within a biofilm community....... We suggest on the basis of these results that E. coli K-12 biofilm development and maturation is dependent on cell-cell adhesion factors, which may act as inducers of self-assembly processes that result in differently structured biofilms depending on the adhesive properties on the cell surface....

  12. Effect of the C:N:P ratio on the denitrifying dephosphatation in a sequencing batch biofilm reactor (SBBR).

    Science.gov (United States)

    Mielcarek, Artur; Rodziewicz, Joanna; Janczukowicz, Wojciech; Thornton, Arthur J; Jóźwiak, Tomasz; Szymczyk, Paula

    2015-12-01

    A series of investigations were conducted using sequencing batch biofilm reactor (SBBR) to explore the influence of C:N:P ratio on biological dephosphatation including the denitrifying dephosphatation and the denitrification process. Biomass in the reactor occurred mainly in the form of a biofilm attached to completely submerged disks. Acetic acid was used as the source of organic carbon. C:N:P ratios have had a significant effect on the profiles of phosphate release and phosphate uptake and nitrogen removal. The highest rates of phosphate release and phosphate uptake were recorded at the C:N:P ratio of 140:70:7. The C:N ratio of 2.5:1 ensured complete denitrification. The highest rate of denitrification was achieved at the C:N:P ratio of 140:35:7. The increase of nitrogen load caused an increase in phosphates removal until a ratio C:N:P of 140:140:7. Bacteria of the biofilm exposed to alternate conditions of mixing and aeration exhibited enhanced intracellular accumulation of polyphosphates. Also, the structure of the biofilm encouraged anaerobic-aerobic as well as anoxic-anaerobic and absolutely anaerobic conditions in a SBBR. These heterogeneous conditions in the presence of nitrates may be a significant factor determining the promotion of denitrifying polyphosphate accumulating organism (DNPAO) development. PMID:26702975

  13. Development of a high-throughput Candida albicans biofilm chip.

    Directory of Open Access Journals (Sweden)

    Anand Srinivasan

    Full Text Available We have developed a high-density microarray platform consisting of nano-biofilms of Candida albicans. A robotic microarrayer was used to print yeast cells of C. albicans encapsulated in a collagen matrix at a volume as low as 50 nL onto surface-modified microscope slides. Upon incubation, the cells grow into fully formed "nano-biofilms". The morphological and architectural complexity of these biofilms were evaluated by scanning electron and confocal scanning laser microscopy. The extent of biofilm formation was determined using a microarray scanner from changes in fluorescence intensities due to FUN 1 metabolic processing. This staining technique was also adapted for antifungal susceptibility testing, which demonstrated that, similar to regular biofilms, cells within the on-chip biofilms displayed elevated levels of resistance against antifungal agents (fluconazole and amphotericin B. Thus, results from structural analyses and antifungal susceptibility testing indicated that despite miniaturization, these biofilms display the typical phenotypic properties associated with the biofilm mode of growth. In its final format, the C. albicans biofilm chip (CaBChip is composed of 768 equivalent and spatially distinct nano-biofilms on a single slide; multiple chips can be printed and processed simultaneously. Compared to current methods for the formation of microbial biofilms, namely the 96-well microtiter plate model, this fungal biofilm chip has advantages in terms of miniaturization and automation, which combine to cut reagent use and analysis time, minimize labor intensive steps, and dramatically reduce assay costs. Such a chip should accelerate the antifungal drug discovery process by enabling rapid, convenient and inexpensive screening of hundreds-to-thousands of compounds simultaneously.

  14. Model-based evaluation of ferrous iron oxidation by acidophilic bacteria in chemostat and biofilm airlift reactors.

    Science.gov (United States)

    Ebrahimi, Sirous; Faraghi, Neda; Hosseini, Maryam

    2015-10-01

    This article presents a model-based evaluation of ferrous iron oxidation in chemostat and biofilm airlift reactors inoculated with a mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans bacteria. The competition between the two types of bacteria in the chemostat and in the biofilm airlift reactors together with the distribution of both bacteria along the biofilm thickness at different time sections has been studied. The bacterial distribution profiles along the biofilm in the airlift reactor at different time scales show that in the beginning A. ferrooxidans bacteria are dominant, but when the reactor operates for a long time the desirable L. ferrooxidans species outcompete A. ferrooxidans as a result of the low Fe(2+) and high Fe(3+) concentrations. The results obtained from the simulation were compared with the experimental data of continuously operated internal loop airlift biofilm reactor. The model results are in good agreement with the experimental results. PMID:26264929

  15. Hydrolysis and degradation of filtrated organic particulates in a biofilm reactor under anoxic and aerobic conditions

    DEFF Research Database (Denmark)

    Janning, K.F.; Mesterton, K.; Harremoës, P.

    1997-01-01

    carbon to the bulk liquid was observed as an indication of hydrolysis taking place. The second experiment was designed as a series of on-line OUR batch experiments in a biofilm reactor with recirculation, in order to investigate further the degradation of particulate organic matter. After the biofilm had......Two experiments were performed in order to investigate the anoxic and the aerobic degradation of filtrated organic matter in a biofilter. In submerged lab: scale reactors with Biocarbone media as filter material, accumulated particulate organic matter from pre-settled wastewater served as the only...

  16. Bioluminescence imaging of fungal biofilm development in live animals.

    Science.gov (United States)

    Vande Velde, Greetje; Kucharíková, Soňa; Van Dijck, Patrick; Himmelreich, Uwe

    2014-01-01

    Fungal biofilms formed on various types of medical implants represent a major problem for hospitalized patients. These biofilms and related infections are usually difficult to treat because of their resistance to the classical antifungal drugs. Animal models are indispensable for investigating host-pathogen interactions and for identifying new antifungal targets related to biofilm development. A limited number of animal models is available that can be used for testing novel antifungal drugs in vivo against C. albicans, one of the most common pathogens causing fungal biofilms. Fungal load in biofilms in these models is traditionally analyzed postmortem, requiring host sacrifice and enumeration of microorganisms from individual biofilms in order to evaluate the amount of colony forming units and the efficacy of antifungal treatment. Bioluminescence imaging (BLI) made compatible with small animal models for in vivo biofilm formation is a valuable noninvasive tool to follow-up biofilm development and its treatment longitudinally, reducing the number of animals needed for such studies. Due to the nondestructive and noninvasive nature of BLI, the imaging procedure can be repeated in the same animal, allowing follow-up of the biofilm growth in vivo without removing the implanted device or detaching the biofilm from its substrate. The method described here introduces BLI of C. albicans biofilm formation in vivo on subcutaneously implanted catheters in mice. One of the main challenges to overcome for BLI of fungi is the hampered intracellular substrate delivery through the fungal cell wall, which is managed by using extracellularly located Gaussia luciferase. Although detecting a quantifiable in vivo BLI signal from biofilms formed on the inside of implanted catheters is challenging, BLI proved to be a practical tool in the study of fungal biofilms. This method describing the use of BLI for in vivo follow-up of device-related fungal biofilm formation has the potential for

  17. Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor

    International Nuclear Information System (INIS)

    Nitrification of saline wastewaters was investigated in bench-scale moving-bed biofilm reactors (MBBR). Wastewater from a chemical industry and domestic sewage, both treated by the activated sludge process, were fed to moving-bed reactors. The industrial wastewater contained 8000 mg Cl-/L and the salinity of the treated sewage was gradually increased until that level. Residual substances present in the treated industrial wastewater had a strong inhibitory effect on the nitrification process. Assays to determine inhibitory effects were performed with the industrial wastewater, which was submitted to ozonation and carbon adsorption pretreatments. The latter treatment was effective for dissolved organic carbon (DOC) removal and improved nitrification efficiency. Nitrification percentage of the treated domestic sewage was higher than 90% for all tested chloride concentrations up to 8000 mg/L. Results obtained in a sequencing batch reactor (SBR) were consistent with those attained in the MBBR systems, allowing tertiary nitrification and providing adequate conditions for adaptation of nitrifying microorganisms even under stressing and inhibitory conditions.

  18. Chromate reduction by Arthrobacter CR47 in biofilm packed bed reactors

    International Nuclear Information System (INIS)

    Bacterial strain Cr47 was isolated from a landfarming process soil sample. It was identified, by 16s rDNA sequencing, as Arthrobacter sp. The time course of the Cr(VI) reduction was monitored in batch operated packed bed biofilm reactors (12mL void volume) and in recirculating packed bed biofilm reactors (100 mL void volume) inoculated with bacterial strain Cr47. The reduction was evaluated with, 30 mg L-1 Cr(VI) laboratory solutions prepared with K2Cr2O7 and enriched with glucose-minimal medium, and with 30 mg L-1 Cr(VI) industrial model solutions prepared with chrome plating waste waters enriched with sucrose-minimal medium. Under batch mode the reduction reaction by the biofilm seemed to fit well an exponential-decay model with a first order kinetic parameter of 0.071 mg(L h)-1 Cr(VI). In the recirculating reactor, monitored after 4 weeks from inoculation and fed with laboratory solutions the removal rate was 0.79 mg(L h)-1. In the reactor fed with the industrial model solutions the maximum Cr(VI) removal rate attained was 0.49 mg(L h)-1. Artrobacter sp. packed bed biofilm reactors achieved Cr(VI) reduction rates comparable to other aerobic and anaerobic fixed film bioreactors previously reported

  19. Low-biodegradable composite chemical wastewater treatment by biofilm configured sequencing batch reactor (SBBR)

    International Nuclear Information System (INIS)

    Biofilm configured system with sequencing/periodic discontinuous batch mode operation was evaluated for the treatment of low-biodegradable composite chemical wastewater (low BOD/COD ratio ∼0.3, high sulfate content: 1.75 g/l) in aerobic metabolic function. Reactor was operated under anoxic-aerobic-anoxic microenvironment conditions with a total cycle period of 24 h [fill: 15 min; reaction: 23 h (aeration along with recirculation); settle: 30 min; decant: 15 min] and the performance of the system was studied at organic loading rates (OLR) of 0.92, 1.50, 3.07 and 4.76 kg COD/cum-day. Substrate utilization showed a steady increase with increase in OLR and system performance sustained at higher loading rates. Maximum non-cumulative substrate utilization was observed after 4 h of the cycle operation. Sulfate removal efficiency of 20% was observed due to the induced anoxic conditions prevailing during the sequence phase operation of the reactor and the existing internal anoxic zones in the biofilm matrix. Biofilm configured sequencing batch reactor (SBR) showed comparatively higher efficiency to the corresponding suspended growth and granular activated carbon (GAC) configured systems studied with same wastewater. Periodic discontinuous batch mode operation of the biofilm reactors results in a more even distribution of the biomass throughout the reactor and was able to treat large shock loads than the continuous flow process. Biofilm configured system coupled with periodic discontinuous batch mode operation imposes regular variations in the substrate concentration on biofilm organisms. As a result, organisms throughout the film achieve maximum growth rates resulting in improved reaction potential leading to stable and robust system which is well suited for treating highly variable wastes

  20. Using optical coherence tomography to quantify biofilm structure and mass transfer in combination with mathematical modeling

    OpenAIRE

    Li, Chunyan

    2015-01-01

    The evolution of biofilm structure on the carriers used in moving bed biofilm reactor was investigated by means of optical coherence tomography and biofilm image analysis. A method was developed by combining biofilm imaging and mathematical modeling to study the mass transfer characteristics in the vicinity of biofilm surface. The method was further used to examine the effect of the deposition of organic particle at biofilm surface on the mass transfer from bulk liquid into biofilms.

  1. Disturbance Frequency Determines Morphology and Community Development in Multi-Species Biofilm at the Landscape Scale

    OpenAIRE

    Milferstedt, Kim; Santa-Catalina, Gaelle; Godon, Jean-Jacques; Escudié, Renaud; Bernet, Nicolas

    2013-01-01

    Many natural and engineered biofilm systems periodically face disturbances. Here we present how the recovery time of a biofilm between disturbances (expressed as disturbance frequency) shapes the development of morphology and community structure in a multi-species biofilm at the landscape scale. It was hypothesized that a high disturbance frequency favors the development of a stable adapted biofilm system while a low disturbance frequency promotes a dynamic biofilm response. Biofilms were gro...

  2. High-rate wastewater treatment combining a moving bed biofilm reactor and enhanced particle separation.

    Science.gov (United States)

    Helness, H; Melin, E; Ulgenes, Y; Järvinen, P; Rasmussen, V; Odegaard, H

    2005-01-01

    Many cities around the world are looking for compact wastewater treatment alternatives since space for treatment plants is becoming scarce. In this paper development of a new compact, high-rate treatment concept with results from experiments in lab-scale and pilot-scale are presented. The idea behind the treatment concept is that coagulation/floc separation may be used to separate suspended and colloidal matter (resulting in > 70% organic matter removal in normal wastewater) while a high-rate biofilm process (based on Moving Bed biofilm reactors) may be used for removing low molecular weight, easily biodegradable, soluble organic matter. By using flotation for floc/biomass separation, the total residence time for a plant according to this concept will normally be cationic polymer combined with iron is used as coagulant at low dosages (i.e. 1-2 mg polymer/l, 5-10 mg Fe/l) resulting in low sludge production (compared to conventional chemical treatment) and sufficient P-removal. PMID:16459783

  3. Heavy metals-bioremediation by highly radioresistant Deinococcus radiodurans biofilm prospective use in nuclear reactor decontamination

    International Nuclear Information System (INIS)

    metals. The study signifies the potential use of D. radiodurans biofilms, which can tolerate >20 kGy in nuclear reactor decontamination process for the removal of active heavy metals. (author)

  4. Biofilm activity and sludge characteristics affected by exogenous N-acyl homoserine lactones in biofilm reactors.

    Science.gov (United States)

    Hu, Huizhi; He, Junguo; Liu, Jian; Yu, Huarong; Zhang, Jie

    2016-07-01

    This study verified the effect of N-acyl homoserine lactone (AHL) concentrations on mature biofilm systems. Three concentrations of an AHL mixture were used in the batch test. Introducing of 5nM AHLs significantly increased biofilm activity and increased sludge characteristics, which resulted in better pollutant removal performance, whereas exogenous 50nM and 500nM AHLs limited pollutant removal, especially COD and nitrogen removal. To further identify how exogenous signal molecular affects biofilm system nitrogen removal, analyzing of nitrifying bacteria through real-time polymerase chain reaction (RT-PCR) revealed that these additional signal molecules affect nitrifying to total bacteria ratio. In addition, the running state of the system was stable during 15days of operation without an AHL dose, which suggests that the changes in the system due to AHL are irreversible. PMID:27030953

  5. Assembly and development of the Pseudomonas aeruginosa biofilm matrix.

    Directory of Open Access Journals (Sweden)

    Luyan Ma

    2009-03-01

    Full Text Available Virtually all cells living in multicellular structures such as tissues and organs are encased in an extracellular matrix. One of the most important features of a biofilm is the extracellular polymeric substance that functions as a matrix, holding bacterial cells together. Yet very little is known about how the matrix forms or how matrix components encase bacteria during biofilm development. Pseudomonas aeruginosa forms environmentally and clinically relevant biofilms and is a paradigm organism for the study of biofilms. The extracellular polymeric substance of P. aeruginosa biofilms is an ill-defined mix of polysaccharides, nucleic acids, and proteins. Here, we directly visualize the product of the polysaccharide synthesis locus (Psl exopolysaccharide at different stages of biofilm development. During attachment, Psl is anchored on the cell surface in a helical pattern. This promotes cell-cell interactions and assembly of a matrix, which holds bacteria in the biofilm and on the surface. Chemical dissociation of Psl from the bacterial surface disrupted the Psl matrix as well as the biofilm structure. During biofilm maturation, Psl accumulates on the periphery of 3-D-structured microcolonies, resulting in a Psl matrix-free cavity in the microcolony center. At the dispersion stage, swimming cells appear in this matrix cavity. Dead cells and extracellular DNA (eDNA are also concentrated in the Psl matrix-free area. Deletion of genes that control cell death and autolysis affects the formation of the matrix cavity and microcolony dispersion. These data provide a mechanism for how P. aeruginosa builds a matrix and subsequently a cavity to free a portion of cells for seeding dispersal. Direct visualization reveals that Psl is a key scaffolding matrix component and opens up avenues for therapeutics of biofilm-related complications.

  6. Sulfur-based denitrification: Effect of biofilm development on denitrification fluxes.

    Science.gov (United States)

    Wang, Yue; Bott, Charles; Nerenberg, Robert

    2016-09-01

    Elemental sulfur (S(o)) can serve as an electron donor for denitrification. However, the mechanisms and rates of S(o)-based denitrification, which depend on a biofilm development on a solid S(o) surface, are not well understood. We used completely-mixed reactors packed with S(o) chips to systematically explore the behavior of S(o)-based denitrification as a function of the bulk nitrate (NO3(-)) concentration and biofilm development. High-purity (99.5%) and agricultural-grade (90% purity) S(o) chips were tested to explore differences in performance. NO3(-) fluxes followed a Monod-type relationship with the bulk NO3(-) concentration. For high-purity S(o), the maximum NO3(-) flux increased from 0.4 gN/m(2)-d at 21 days to 0.9 g N/m(2)-d at around 100 days, but then decreased to 0.65 gN/m(2)-d at 161 days. The apparent (extant) half-saturation constant for NO3(-) KSapp, based on the bulk NO3(-) concentration and NO3(-) fluxes into the biofilm, increased from 0.1 mgN/L at 21 days to 0.8 mgN/L at 161 days, reflecting the increasing mass transfer resistance as the biofilm thickness increased. Nitrite (NO2(-)) accumulation became significant at bulk NO3(-) concentration above 0.2 mgN/L. The behavior of the agricultural-grade S(o) was very similar to the high-purity S(o). The kinetic behavior of S(o)-based denitrification was consistent with substrate counter-diffusion, where the soluble sulfur species diffuse from the S(o) particle into the base of the biofilm, while NO3(-) diffuses into the biofilm from the bulk. Initially, the fluxes were low due to biomass limitation (thin biofilms). As the biofilm thickness increased with time, the fluxes first increased, stabilized, and then decreased. The decrease was probably due to increasing diffusional resistance in the thick biofilm. Results suggest that fluxes comparable to heterotrophic biofilm processes can be achieved, but careful management of biofilm accumulation is important to maintain high fluxes. PMID:27187050

  7. Fixed-biofilm reactors applied to waste water treatment and aquacultural water recirculating systems.

    NARCIS (Netherlands)

    Bovendeur, J.

    1989-01-01

    Fixed-biofilm waste water treatment may be regarded as one of the oldest engineered biological waste water treatment methods. With the recent introduction of modern packing materials, this type of reactor has received a renewed impuls for implementation in a wide field of water treatment.In this the

  8. Feasibility of treating partially soluble wastewater in anaerobic sequencing batch biofilm reactor (ASBBR) with mechanical stirring.

    Science.gov (United States)

    Pinho, Samantha Cristina; Ratusznei, Suzana Maria; Rodrigues, José Alberto Domingues; Foresti, Eugenio; Zaiat, Marcelo

    2005-03-01

    This work reports on the treatment of partially soluble wastewater in an anaerobic sequencing batch biofilm reactor, containing biomass immobilized on polyurethane matrices and stirred mechanically. The results showed that agitation provided optimal mixing and improved the overall organic matter consumption rates. The system showed to be feasible to enhance the treatment of partially soluble wastewaters. PMID:15491835

  9. Start-up strategies of membrane-aerated biofilm reactor (MABR) for completely autotrophic nitrogen removal

    DEFF Research Database (Denmark)

    Sun, Sheng-Peng; Pellicer i Nàcher, Carles; Terada, Akihiko;

    2009-01-01

    downside of this process stems from a long start-up period due to the slow growth rate of AnAOB. Therefore, two different start-up strategies, i.e., continuous inoculation of AnAOB and sequential batch inoculation of AOB and AnAOB, were tested in two laboratory scale membrane-aerated biofilm reactor (MABRs...

  10. Toluene removal in a biofilm reactor for waste gas treatment

    DEFF Research Database (Denmark)

    Pedersen, A.R.; Arvin, E.

    1997-01-01

    surface removal rates estimated by parameter fitting corresponded to previously observed values. The effect of the gas flow on the mass transfer coefficient and the biological removal rate may be explained by different flow patterns of the gas and the liquid phases. A characterisation of the biofilm...

  11. Biofilm development on metal surfaces in tropical marine waters

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; Bhosle, N.B.

    environments. However, little is known about biofilm bacteria developed on metal surfaces, especially immersed in tropical marine waters. Similarly, not much is known about the nature of organic matter deposited on the surfaces over the period of immersion...

  12. Development and maturation of Escherichia coli K-12 biofilms

    DEFF Research Database (Denmark)

    Reisner, A.; Haagensen, J.A.J.; Schembri, Mark; Zechner, E.L.; Molin, Søren

    2003-01-01

    The development and maturation of E. coli biofilms in flow-chambers was investigated. We found that the presence of transfer constitutive IncF plasmids induced biofilm development forming structures resembling those reported for Pseudomonas aeruginosa . The development occurred in a step....... We suggest on the basis of these results that E. coli K-12 biofilm development and maturation is dependent on cell-cell adhesion factors, which may act as inducers of self-assembly processes that result in differently structured biofilms depending on the adhesive properties on the cell surface.......-wise process: (i) attachment of cells to the substratum, (ii) clonal growth and microcolony formation, and (iii) differentiation into expanding structures rising 70-100 mum into the water phase. The first two steps were the same in the plasmid-carrying and plasmid-free strains, whereas the third step only...

  13. Oxidation behavior of ammonium in a 3-dimensional biofilm-electrode reactor.

    Science.gov (United States)

    Tang, Jinjing; Guo, Jinsong; Fang, Fang; Chen, Youpeng; Lei, Lijing; Yang, Lin

    2013-12-01

    Excess nitrogenous compounds are detrimental to natural water systems and to human health. To completely realize autohydrogenotrophic nitrogen removal, a novel 3-dimensional biofilm-electrode reactor was designed. Titanium was electroplated with ruthenium and used as the anode. Activated carbon fiber felt was used as the cathode. The reactor was separated into two chambers by a permeable membrane. The cathode chamber was filled with granular graphite and glass beads. The cathode and cathode chamber were inhabited with domesticated biofilm. In the absence of organic substances, a nitrogen removal efficiency of up to 91% was achieved at DO levels of 3.42 +/- 0.37 mg/L when the applied current density was only 0.02 mA/cm2. The oxidation of ammonium in biofilm-electrode reactors was also investigated. It was found that ammonium could be oxidized not only on the anode but also on particle electrodes in the cathode chamber of the biofilm-electrode reactor. Oxidation rates of ammonium and nitrogen removal efficiency were found to be affected by the electric current loading on the biofilm-electrode reactor. The kinetic model of ammonium at different electric currents was analyzed by a first-order reaction kinetics equation. The regression analysis implied that when the current density was less than 0.02 mA/cm2, ammonium removal was positively correlated to the current density. However, when the current density was more than 0.02 mA/cm2, the electric current became a limiting factor for the oxidation rate of ammonium and nitrogen removal efficiency. PMID:24649670

  14. Evolution of the microbial community of the biofilm in a methane-based membrane biofilm reactor reducing multiple electron acceptors.

    Science.gov (United States)

    Chen, Ran; Luo, Yi-Hao; Chen, Jia-Xian; Zhang, Yin; Wen, Li-Lian; Shi, Ling-Dong; Tang, Youneng; Rittmann, Bruce E; Zheng, Ping; Zhao, He-Ping

    2016-05-01

    Previous work documented complete perchlorate reduction in a membrane biofilm reactor (MBfR) using methane as the sole electron donor and carbon source. This work explores how the biofilm's microbial community evolved as the biofilm stage-wise reduced different combinations of perchlorate, nitrate, and nitrite. The initial inoculum, carrying out anaerobic methane oxidation coupled to denitrification (ANMO-D), was dominated by uncultured Anaerolineaceae and Ferruginibacter sp. The microbial community significantly changed after it was inoculated into the CH4-based MBfR and fed with a medium containing perchlorate and nitrite. Archaea were lost within the first 40 days, and the uncultured Anaerolineaceae and Ferruginibacter sp. also had significant losses. Replacing them were anoxic methanotrophs, especially Methylocystis, which accounted for more than 25 % of total bacteria. Once the methanotrophs became important, methanol-oxidizing denitrifying bacteria, namely, Methloversatilis and Methylophilus, became important in the biofilm, probably by utilizing organic matter generated by the metabolism of methanotrophs. When methane consumption was equal to the maximum-possible electron-donor supply, Methylomonas, also an anoxic methanotroph, accounted for >10 % of total bacteria and remained a major part of the community until the end of the experiments. We propose that aerobic methane oxidation coupled to denitrification and perchlorate reduction (AMO-D and AMO-PR) directly oxidized methane and reduced NO3 (-) to NO2 (-) or N2O under anoxic condition, producing organic matter for methanol-assimilating denitrification and perchlorate reduction (MA-D and MA-PR) to reduce NO3 (-). Simultaneously, bacteria capable of anaerobic methane oxidation coupled to denitrification and perchlorate reduction (ANMO-D and ANMO-PR) used methane as the electron donor to respire NO3 (-) or ClO4 (-) directly. Graphical Abstract ᅟ. PMID:26841777

  15. Utilizing a one-dimensional multispecies model to simulate the nutrient reduction and biomass structure in two types of H2-based membrane-aeration biofilm reactors (H2-MBfR): model development and parametric analysis.

    Science.gov (United States)

    Wang, Zuowei; Xia, Siqing; Xu, Xiaoyin; Wang, Chenhui

    2016-02-01

    In this study, a one-dimensional multispecies model (ODMSM) was utilized to simulate NO3 (-)-N and ClO4 (-) reduction performances in two kinds of H2-based membrane-aeration biofilm reactors (H2-MBfR) within different operating conditions (e.g., NO3 (-)-N/ClO4 (-) loading rates, H2 partial pressure, etc.). Before the simulation process, we conducted the sensitivity analysis of some key parameters which would fluctuate in different environmental conditions, then we used the experimental data to calibrate the more sensitive parameters μ1 and μ2 (maximum specific growth rates of denitrification bacteria and perchlorate reduction bacteria) in two H2-MBfRs, and the diversity of the two key parameters' values in two types of reactors may be resulted from the different carbon source fed in the reactors. From the simulation results of six different operating conditions (four in H2-MBfR 1 and two in H2-MBfR 2), the applicability of the model was approved, and the variation of the removal tendency in different operating conditions could be well simulated. Besides, the rationality of operating parameters (H2 partial pressure, etc.) could be judged especially in condition of high nutrients' loading rates. To a certain degree, the model could provide theoretical guidance to determine the operating parameters on some specific conditions in practical application. PMID:26490919

  16. Development of mixed microbial granular biofilms for denitrification of concentrated wastes

    International Nuclear Information System (INIS)

    Nitrate containing wastes are generated at various stages of the nuclear fuel cycle; fuel fabrication and reprocessing. A treatment process for removing nitrate from such concentrated nitrate bearing effluents is needed. Among other available options, biological denitrification is an economical and technically feasible method for nitrate removal. Granular biofilm based sequencing batch reactors (SBRs) may allow designing a compact and high rate processes suitable for the treatment of concentrated effluents. Hence, experiments were carried out in laboratory scale sequencing batch reactors (SBRs) to develop granular biofilms (composed of mixed microbes) for removing nitrate from the concentrated nitrate containing-media. Microbial granular biofilms, capable of consuming nitrate up to 2710 mg/l nitrate-N, were developed under anaerobic conditions in a 6-litre volume sequencing batch reactor (SBR). The SBR was inoculated with activated sludge flocs and operated with 24-h cycle and 50% volumetric exchange ratio. Synthetic media containing acetate as the energy source and electron donor, at carbon to nitrogen molar ratio of 2:1 and 3:1 was fed into the SBRs. Nitrate-N concentration in the SBR was increased in a step-wise manner starting from 677 to 2710 mg/l (1355 to 5420 mg/l in the feed). Complete removal of influent nitrate occurred within the first few hours of SBR cycle period. Effluent nitrate and nitrite levels (∼3 mg/l nitrate-N or nitrite-N) at the end of SBR cycle period (24 h) were found to be below the discharge limits. Under these conditions biomass predominantly consisted of granular biofilms. Results show the potential of granular biofilm based SBR for converting nitrate to nitrogen gas from concentrated nitrate bearing industrial effluents. (author)

  17. Role of Moving Bed Biofilm Reactor and Sequencing Batch Reactor in Biological Degradation of Formaldehyde Wastewater

    Directory of Open Access Journals (Sweden)

    B. Ayati

    2011-10-01

    Full Text Available Nowadays formaldehyde is used as raw material in many industries. It has also disinfection applications in some public places. Due to its toxicity for microorganisms, chemical or anaerobic biological methods are applied for treating wastewater containing formaldehyde.In this research, formaldehyde removal efficiencies of aerobic biological treatment systems including moving bed biofilm (MMBR and sequencing batch reactors (SBR were investigated. During all experiments, the efficiency of SBR was more than MBBR, but the difference was not significant statistically. According to the results, the best efficiencies were obtained for influent formaldehyde COD of 200 mg/L in MBBR and SBR which were 93% and 99.4%, respectively. The systems were also capable to treat higher formaldehyde concentrations (up to 2500 mg/L with lower removal efficiency. The reaction kinetics followed the Stover-Kincannon second order model. The gram-positive and gram-negative bacillus and coccus as well as the gram-positive binary bacillus were found to be the most dominant species. The results of 13C-NMR analysis have shown that formaldehyde and urea were converted into N-{[(aminocarbonyl amino] methyl}urea and the residual formaldehyde was polymerized at room temperature.

  18. Biofilm

    Czech Academy of Sciences Publication Activity Database

    Kvíderová, Jana

    Berlin: Springer, 2015 - (Amils, R.; Gargaud, M.; Cernicharo Quintanilla, J.; James Claves, H.; Irvine, W.; Pinti, D.; Viso, M.), s. 1-3 ISBN 978-3-642-27833-4 Institutional support: RVO:67985939 Keywords : biofilm * microbial mat * astrobiology Subject RIV: EF - Botanics

  19. Suspended sludge and biofilm shaped different anammox communities in two pilot-scale one-stage anammox reactors.

    Science.gov (United States)

    Zheng, Bingyu; Zhang, Liang; Guo, Jianhua; Zhang, Shujun; Yang, Anming; Peng, Yongzhen

    2016-07-01

    The abundance and diversity of anammox bacteria was investigated in two pilot-scale integrated fixed-film activated sludge (IFAS) reactors treating high ammonium wastewater. Reactor A was inoculated with nitrifying sludge, while Reactor B was inoculated with suspended anammox sludge with the dominant anammox bacteria of Candidatus 'Kuenenia'. After 180days' operation, the predominate anammox bacteria was Candidatus 'Brocadia' (65%) in the biofilm, while Candidatus 'Kuenenia' (86%) outcompeted with other anammox bacteria in suspended sludge in Reactor A. Candidatus 'Kuenenia' were dominated in suspended sludge through the entire experiment in Reactor B. In contrast, the predominated species shifted from Candidatus 'Kuenenia' (89%) into Candidatus 'Brocadia' (66%) in the biofilm of Reactor B. This study indicated that Candidatus 'Brocadia' preferred to grow in the biofilm, while Candidatus 'Kuenenia' would dominant over other anammox bacteria in the suspended sludge. Further studies are required to identify the internal factors affecting the distribution of anammox bacteria. PMID:27023382

  20. Enhancing mass transfer and ethanol production in syngas fermentation of Clostridium carboxidivorans P7 through a monolithic biofilm reactor

    International Nuclear Information System (INIS)

    Highlights: • Syngas fermentation process is limited by gas-to-liquid mass transfer. • A novel monolithic biofilm reactor (MBR) for efficient mass transfer was developed. • MBR with slug flow resulted in higher kLa than bubble column reactor (BCR). • MBR enhanced ethanol productivity by 53% compared to BCR. • MBR was demonstrated as a promising reactor configuration for syngas fermentation. - Abstract: Syngas fermentation is a promising process for producing fuels and chemicals from lignocellulosic biomass. Currently syngas fermentation faces several engineering challenges, with gas-to-liquid mass transfer limitation representing the major bottleneck. The aim of this work is to evaluate the performance of a monolithic biofilm reactor (MBR) as a novel reactor configuration for syngas fermentation. The volumetric mass transfer coefficient (kLa) of the MBR was evaluated in abiotic conditions within a wide range of gas flow rates (i.e., gas velocity in monolithic channels) and liquid flow rates (i.e., liquid velocity in the channels). The kLa values of the MBR were higher than those of a controlled bubble column reactor (BCR) in certain conditions, due to the slug flow pattern in the monolithic channels. A continuous syngas fermentation using Clostridium carboxidivorans P7 was conducted in the MBR system under varying operational conditions, with the variables including syngas flow rate, liquid recirculation between the monolithic column and reservoir, and dilution rate. It was found that the syngas fermentation performance – measured by such parameters as syngas utilization efficiency, ethanol concentration and productivity, and ratio of ethanol to acetic acid – depended not only on the mass transfer efficiency but also on the biofouling or abrading of the biofilm attached on the monolithic channel wall. At a condition of 300 mL/min of syngas flow rate, 500 mL/min of liquid flow rate, and 0.48 day−1 of dilution rate, the MBR produced much higher syngas

  1. Biosurfactants production in biofilm reactor and their recovery by pertraction [abstract

    Directory of Open Access Journals (Sweden)

    Chtioui, O.

    2010-01-01

    Full Text Available This study was focused on production and isolation of microbial surfactants with interesting properties for application in agriculture, petrol industry, pollution remediation and pharmaceutical fields. The biosurfactant production was performed by free and immobilized aerobic cells of Bacillus subtilis ATCC 21332. This strain produces lipopeptides of the surfactin and fengycin families. The colonizing behavior of Bacillus subtilis strain was evaluated under several experimental and cultural conditions at different sterile solid materials with modified surface properties. After preliminary screening tests with five polymer materials, polypropylene foamed with powder activated carbon (PPch was selected for cells immobilization and production of lipopeptides. The aims of work are to develop a new technology using the specificity of a biofilm reactor as well as a perspective continuous separation based on a liquid membrane technique (known also as pertraction. Using the classical aerated reactor the lipopeptides generate extensive foaming that imposes difficulties on plant-scale process realization. In order to avoid this drawback, while using the new type reactor conditions, the air was injected over the surface of cultural medium. With this configuration, the biofilm on the solid support and the culture medium are alimented in oxygen directly from the interfaces. The obtained results showed that the production of both lipopeptides and especially of the fengycin was greatly enhanced by the immobilization. The longer time of preliminary cells colonization enhanced highly the production of surfactin, especially at the beginning of fermentation process (the first 24 h. This effect was less evident after 48 h fermentation. To confirm the applicability of the liquid membrane process to lipopeptides recovery from aqueous media, including fermentation broth, extraction behavior of the lipopeptides into organic solvents was studied. For both lipopeptides

  2. Synchronized dynamics of bacterial niche-specific functions during biofilm development in a cold seep brine pool

    KAUST Repository

    Zhang, Weipeng

    2015-07-14

    The biology of biofilm in deep-sea environments is barely being explored. Here, biofilms were developed at the brine pool (characterized by limited carbon sources) and the normal bottom water adjacent to Thuwal cold seeps. Comparative metagenomics based on 50 Gb datasets identified polysaccharide degradation, nitrate reduction, and proteolysis as enriched functional categories for brine biofilms. The genomes of two dominant species: a novel deltaproteobacterium and a novel epsilonproteobacterium in the brine biofilms were reconstructed. Despite rather small genome sizes, the deltaproteobacterium possessed enhanced polysaccharide fermentation pathways, whereas the epsilonproteobacterium was a versatile nitrogen reactor possessing nar, nap and nif gene clusters. These metabolic functions, together with specific regulatory and hypersaline-tolerant genes, made the two bacteria unique compared with their close relatives including those from hydrothermal vents. Moreover, these functions were regulated by biofilm development, as both the abundance and the expression level of key functional genes were higher in later-stage biofilms, and co-occurrences between the two dominant bacteria were demonstrated. Collectively, unique mechanisms were revealed: i) polysaccharides fermentation, proteolysis interacted with nitrogen cycling to form a complex chain for energy generation; ii) remarkably, exploiting and organizing niche-specific functions would be an important strategy for biofilm-dependent adaptation to the extreme conditions.

  3. Biodegradation Rates of Aromatic Contaminants in Biofilm Reactors

    DEFF Research Database (Denmark)

    Arcangeli, Jean-Pierre; Arvin, Erik

    1995-01-01

    This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols......, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic...

  4. Treatment of domestic wastewater in an up-flow anaerobic sludge blanket reactor followed by moving bed biofilm reactor

    OpenAIRE

    Tawfik, A.; El-Gohary, F.; Temmink, B.G.

    2010-01-01

    The performance of a laboratory-scale sewage treatment system composed of an up-flow anaerobic sludge blanket (UASB) reactor and a moving bed biofilm reactor (MBBR) at a temperature of (22-35 A degrees C) was evaluated. The entire treatment system was operated at different hydraulic retention times (HRT's) of 13.3, 10 and 5.0 h. An overall reduction of 80-86% for CODtotal; 51-73% for CODcolloidal and 20-55% for CODsoluble was found at a total HRT of 5-10 h, respectively. By prolonging the HRT...

  5. Anaerobic biofilm reactors for dark fermentative hydrogen production from wastewater: A review.

    Science.gov (United States)

    Barca, Cristian; Soric, Audrey; Ranava, David; Giudici-Orticoni, Marie-Thérèse; Ferrasse, Jean-Henry

    2015-06-01

    Dark fermentation is a bioprocess driven by anaerobic bacteria that can produce hydrogen (H2) from organic waste and wastewater. This review analyses a relevant number of recent studies that have investigated dark fermentative H2 production from wastewater using two different types of anaerobic biofilm reactors: anaerobic packed bed reactor (APBR) and anaerobic fluidized bed reactor (AFBR). The effect of various parameters, including temperature, pH, carrier material, inoculum pretreatment, hydraulic retention time, substrate type and concentration, on reactor performances was investigated by a critical discussion of the results published in the literature. Also, this review presents an in-depth study on the influence of the main operating parameters on the metabolic pathways. The aim of this review is to provide to researchers and practitioners in the field of H2 production key elements for the best operation of the reactors. Finally, some perspectives and technical challenges to improve H2 production were proposed. PMID:25746594

  6. Syntrophic microbial communities on straw as biofilm carrier increase the methane yield of a biowaste-digesting biogas reactor

    Directory of Open Access Journals (Sweden)

    Frank R. Bengelsdorf

    2015-08-01

    Full Text Available Biogas from biowaste can be an important source of renewable energy, but the fermentation process of low-structure waste is often unstable. The present study uses a full-scale biogas reactor to test the hypothesis that straw as an additional biofilm carrier will increase methane yield; and this effect is mirrored in a specific microbial community attached to the straw. Better reactor performance after addition of straw, at simultaneously higher organic loading rate and specific methane yield confirmed the hypothesis. The microbial communities on straw as a biofilm carrier and of the liquid reactor content were investigated using 16S rDNA amplicon sequencing by means of 454 pyrosequencing technology. The results revealed high diversity of the bacterial communities in the liquid reactor content as well as the biofilms on the straw. The most abundant archaea in all samples belonged to the genera Methanoculleus and Methanosarcina. Addition of straw resulted in a significantly different microbial community attached to the biofilm carrier. The bacterium Candidatus Cloacamonas acidaminovorans and methanogenic archaea of the genus Methanoculleus dominated the biofilm on straw. Syntrophic interactions between the hydrogenotrophic Methanoculleus sp. and members of the hydrogen-producing bacterial community within biofilms may explain the improved methane yield. Thus, straw addition can be used to improve and to stabilize the anaerobic process in substrates lacking biofilm-supporting structures.

  7. Degradation of Phenolic Compounds in Coal Gasification Wastewater by Biofilm Reactor with Isolated Klebsiella sp

    Institute of Scientific and Technical Information of China (English)

    Fang Fang; HongJun Han; ChunYan Xu; Qian Zhao; LingHan Zhang

    2014-01-01

    This study was conducted to evaluate the degradation of phenolic compounds by one strain isolated from coal gasification wastewater ( CGW ) . 16S rRNA gene sequences homology and phylogenetic analysis showed that the isolate is belonged to the genus Klebsiella sp. The effect of different phenolic compounds on the isolate was investigated by determining OD600 and phenoloxidase activity, of which the results showed that the isolate can utilize phenol, 4-methyl phenol, 3, 5-dimethyl phenol and resorcinol as carbon resources. The biofilm reactor ( formed by the isolate) can resist the influent concentration of phenolic compounds as high as 750 mg/L when fed with synthetic CGW and incubated at optimum conditions. The capacity of improving the biodegradability of CGW through degrading phenolic compounds was testified with fed the biofilm reactor with real CGW. Thus, it might be an effective strain for bioaugmentation of CGW treatment.

  8. Real-Time Microscopic Observation of Candida Biofilm Development and Effects Due to Micafungin and Fluconazole

    OpenAIRE

    Kaneko, Yukihiro; Miyagawa, Susumu; Takeda, On; Hakariya, Masateru; Matsumoto, Satoru; Ohno, Hideaki; Miyazaki, Yoshitsugu

    2013-01-01

    To understand the process of Candida biofilm development and the effects of antifungal agents on biofilms, we analyzed real-time data comprising time-lapse images taken at times separated by brief intervals. The growth rate was calculated by measuring the change of biofilm thickness every hour. For the antifungal study, 5-h-old biofilms of Candida albicans were treated with either micafungin (MCFG) or fluconazole (FLCZ). MCFG began to suppress biofilm growth a few minutes after the initiation...

  9. Calcium transcriptionally regulates the biofilm machinery of Xylella fastidiosa to promote continued biofilm development in batch cultures.

    Science.gov (United States)

    Parker, Jennifer K; Chen, Hongyu; McCarty, Sara E; Liu, Lawrence Y; De La Fuente, Leonardo

    2016-05-01

    The functions of calcium (Ca) in bacteria are less characterized than in eukaryotes, where its role has been studied extensively. The plant-pathogenic bacterium Xylella fastidiosa has several virulence features that are enhanced by increased Ca concentrations, including biofilm formation. However, the specific mechanisms driving modulation of this feature are unclear. Characterization of biofilm formation over time showed that 4 mM Ca supplementation produced denser biofilms that were still developing at 96 h, while biofilm in non-supplemented media had reached the dispersal stage by 72 h. To identify changes in global gene expression in X. fastidiosa grown in supplemental Ca, RNA-Seq of batch culture biofilm cells was conducted at three 24-h time intervals. Results indicate that a variety of genes are differentially expressed in response to Ca, including genes related to attachment, motility, exopolysaccharide synthesis, biofilm formation, peptidoglycan synthesis, regulatory functions, iron homeostasis, and phages. Collectively, results demonstrate that Ca supplementation induces a transcriptional response that promotes continued biofilm development, while biofilm cells in nonsupplemented media are driven towards dispersion of cells from the biofilm structure. These results have important implications for disease progression in planta, where xylem sap is the source of Ca and other nutrients for X. fastidiosa. PMID:26913481

  10. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor

    OpenAIRE

    Shohreh Azizi; Ilunga Kamika; Memory Tekere

    2016-01-01

    For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 h...

  11. Nitrogen removal in a Sequencing Batch Biofilm Reactor : effect of carbon availability and intermittent aeration

    OpenAIRE

    Vieira, Maria Madalena Costa; Brito, A. G.; R. Nogueira

    2009-01-01

    This study aimed to investigate the effects of carbon availability and intermittent aeration on nitrogen removal in a Sequencing Batch Biofilm Reactor (SBBR). The percentage of nitrogen removal in the SBBRs operating with dump fill and slow fill with optimum intermittent aeration was quite similar, 75.7% and 69.2%, respectively, indicating that intermittent aeration allowed a considerable energy saving without compromising significantly nitrogen removal. Accumulation of stor...

  12. Biological nutrient removal from municipal wastewater in sequencing batch biofilm reactors

    Energy Technology Data Exchange (ETDEWEB)

    Arnz, P.

    2001-07-01

    Enhanced biological phosphorus removal (EBPR) has only been put into practice in activated sludge systems. In recent years, the Sequencing Batch Biofilm Reactor (SBBR) has emerged as an alternative allowing EBPR to be achieved in a biofilm reactor. High efficiency of phosphate removal was demonstrated in a SBBR fed with synthetic wastewater containing acetate. The aim of this study was to investigate EBPR from municipal wastewater in semi full-scale and laboratory-scale SBBRs. The focus of the investigation in the semi full-scale reactor was on determination of achievable reaction rates and effluent concentrations under varying influent conditions throughout all seasons of a year. Interactions between nitrogen and phosphorus removal and the influence of backwashing on the reactor performance was examined. Summing up, it can be stated that the SBBR proved to be an attractive alternative to activated sludge systems. Phosphorus elimination efficiency was comparable to common systems but biomass sedimentation problems were avoided. In order to further exploit the potential of the SBBR and to achieve reactor performances superior to those of existing systems designing a special biofilm carrier material may allow to increase the phenomenon of simultaneous nitrification/denitrification while maintaining EBPR activity. (orig.) [German] Die vermehrte biologische Phosphorelimination (Bio-P) aus Abwasser wurde bisher nur in Belebtschlammsystemen praktiziert. In den letzten Jahren konnte jedoch gezeigt werden, dass sich durch die Anwendung des Sequencing Batch Biofilm Reactor (SBBR) - Verfahrens auch in Biofilmreaktoren Bio-P verwirklichen laesst. Versuche in Laboranlagen haben ergeben, dass sich eine weitgehende Phosphorelimination aufrecht erhalten laesst, wenn die Reaktoren mit einem ideal zusammengesetzten, synthetischen Abwasser beschickt werden. Ziel dieser Arbeit war es, Bio-P aus kommunalem Abwasser in SBBR-Versuchsanlagen im halbtechnischen und im Labormassstab zu

  13. Toluene biodegradation and biofilm growth in an aerobic fixed-film reactor

    DEFF Research Database (Denmark)

    Arcangeli, Jean-Pierre; Arvin, Erik

    1992-01-01

    characterization of the carbon fractions leaving the reactor showed a significant production of soluble polymers and formation of suspended biomass. The latter was probably due to the detachment of filamentous bacteria. A decrease in toluene degradation was observed when the oxygen concentration was increased from....../mg toluene degraded was found. A chemical oxygen demand balance relative to three biofilm growth scenarios showed that only a minor fraction of the carbon in the influent accumulated as biomass in the reactor. Of this accumulated biomass only a small fraction was active biomass, about 5% protein. A...

  14. Combating biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong;

    2012-01-01

    Biofilms are complex microbial communities consisting of microcolonies embedded in a matrix of self-produced polymer substances. Biofilm cells show much greater resistance to environmental challenges including antimicrobial agents than their free-living counterparts. The biofilm mode of life is...... believed to significantly contribute to successful microbial survival in hostile environments. Conventional treatment, disinfection and cleaning strategies do not proficiently deal with biofilm-related problems, such as persistent infections and contamination of food production facilities. In this review......, strategies to control biofilms are discussed, including those of inhibition of microbial attachment, interference of biofilm structure development and differentiation, killing of biofilm cells and induction of biofilm dispersion....

  15. Liquid Flow in Biofilm Systems

    OpenAIRE

    Stoodley, Paul; deBeer, Dirk; Lewandowski, Zbigniew

    1994-01-01

    A model biofilm consisting of Pseudomonas aeruginosa, Pseudomonas fluorescens, and Klebsiella pneumoniae was developed to study the relationships between structural heterogeneity and hydrodynamics. Local fluid velocity in the biofilm system was measured by a noninvasive method of particle image velocimetry, using confocal scanning laser microscopy. Velocity profiles were measured in conduit and porous medium reactors in the presence and absence of biofilm. Liquid flow was observed within biof...

  16. Candida albicans biofilm development in vitro for photodynamic therapy study

    International Nuclear Information System (INIS)

    Photodynamic therapy (PDT) is a phototherapy based on the use of a photo sensitizer (PS) in the presence of low intensity light with resonant wavelength of absorption of the PS and biological systems that can raise awareness, generating reactive oxygen species. Studies show that PDT has a lethal effect on Candida albicans. The biofilm formed by C. albicans is the cause of infections associated with medical devices such as catheters, with a proven resistance to antifungal agents, and the removal of the catheter colonized almost always is necessary. However, few studies in literature report the behavior and response of biofilm organized by C. albicans against PDT. The aims of this study were to develop a methodology for in vitro biofilm formation of C. albicans, evaluate the sensitivity of the biofilm of C. albicans to antimicrobial photodynamic therapy using PS as the methylene blue (MB) and hypocrellin B: La+3 (HBLa+3) and analyze the biofilm by Optical Coherence Tomography (OCT). For biofilm formation, discs were made from elastomeric silicone catheters. The PS were dissolved in solution of PBS, and the MB had two different concentrations tested in the biofilm: 100μM and 1mM; HBLa+3 only one of 10μM. The irradiation of both dyes with the microorganism was done by two different LEDs, one with red emission at λ = 630nm ± 20nm and the other one blue emission at λ = 460nm ± 30nm. We performed a curve of survival fraction versus time of irradiation of each sample with biofilm and suspension of the microorganism in the yeast form to verify the susceptibility of the front PDT. The yeast showed 100% reduction using both PS, but at different times of irradiation (30s to HBLa+3 and 6 min for the MB at 100μM). When the therapy was applied in biofilm, the MB 100μM did not show any significant reduction, while at concentration of 1mM was reduced by 100% after 6 min of irradiation. The HBLa+3 biofilm group showed a lower reduction in the concentration of 10μM in

  17. Simultaneous Organics and Nutrients Removal from Domestic Wastewater in a Combined Cylindrical Anoxic/Aerobic Moving Bed Biofilm Reactor

    Directory of Open Access Journals (Sweden)

    Husham T. Ibrahim

    2014-03-01

    Full Text Available The aim of present study was to design and construct an continuous up-flow pilot scale Moving Bed Biofilm Reactor (MBBR which is consists of combined cylindrical Anoxic/Aerobic MBBR in nested form with anoxic/aerobic volume ratio equal to 0.16 to treated 4 m3 /days of domestic wastewater in Chongqing city at Southwest China. The treatment must be satisfactory to meet with grade B of discharge standard of pollutants for municipal wastewater treatment plant in China (GB/T18918-2002. Kaldnes (K1 media was used as a carrier in both reactors at a media fill ratio equal to 50%. The reactors was operated under the Anoxic/Oxic (An/O process which must meet stringent TN limits without sludge returning into the system and only an internal recycling was performed from aerobic to anoxic reactor. After developing the biofilm on the media, reactor was operated at 3 different Hydraulic Residence Time (HRT ranging from 4.95 to 8.25 h. During operation the internal recycle ratio to eliminate nitrogen compounds were 100% of inflow rate and the average Dissolved Oxygen concentration (DO in aerobic and anoxic MBBRs were 4.49 and 0.16 mg/L, respectively. The obtained results showed that the HRT of 6.2 h was suitable for simultaneous removal of COD, NH4+-N, TN and TP. In this HRT the average removal efficiencies were 93.15, 98.06, 71.67 and 90.88% for COD, NH4+-N, TN and TP, respectively.

  18. Iris reactor development

    International Nuclear Information System (INIS)

    The development progress of the IRIS (International Reactor Innovative and Secure) nuclear power system is presented. IRIS is currently being developed by an international consortium of industry, laboratory, university and utility establishments, led by Westinghouse. It is aimed at achieving the four major objectives of the Generation IV nuclear systems, i.e., proliferation resistance, enhanced safety, economic competitiveness and reduced waste. The project first year activities, which are summarized here, were focused on core neutronics, in-vessel configuration, steam generator and containment design, safety approach and economic performance. Details of these studies are provided in parallel papers in these proceedings. (author)

  19. Acoustic Wave Monitoring of Biofilm Development in Porous Media

    Science.gov (United States)

    Biofilm development in porous media can result in significant changes to the hydrogeological properties of subsurface systems with implications for fluid flow and contaminant transport. As such, a number of numerical models and simulations have been developed in an attempt to qua...

  20. Effect of bacterial interference on biofilm development by Legionella pneumophila.

    Science.gov (United States)

    Guerrieri, Elisa; Bondi, Moreno; Sabia, Carla; de Niederhäusern, Simona; Borella, Paola; Messi, Patrizia

    2008-12-01

    In the ecology of Legionella pneumophila a crucial role may be played by its relationship with the natural flora; thus we investigated the interactions between Legionella and other aquatic bacteria, particularly within biofilms. Among 80 aquatic bacteria screened for the production of bacteriocin-like substances (BLSs), 66.2% of them were active against L. pneumophila. The possible effect of some of these aquatic bacteria on the development and stability of L. pneumophila biofilms was studied. Pseudomonas fluorescens, the best BLS producer, showed the greatest negative effect on biofilm formation and strongly enhanced the detachment of Legionella. Pseudomonas aeruginosa, Burkholderia cepacia, Pseudomonas putida, Aeromonas hydrophila, and Stenotrophomonas maltophilia, although producing BLSs at different levels, were less active in the biofilm experiments. Acinetobacter lwoffii did not produce any antagonistic compound and was the only one able to strongly enhance L. pneumophila biofilm. Our results highlight that BLS production may contribute to determining the fate of L. pneumophila within ecological niches. The interactions observed in this study are important features of L. pneumophila ecology, which knowledge may lead to more effective measures to control the persistence of the germ in the environment. PMID:18769851

  1. Biohydrogen production from glucose in upflow biofilm reactors with plastic carriers under extreme thermophilic conditions (70(degree)C)

    DEFF Research Database (Denmark)

    Zheng, H.; Zeng, Raymond Jianxiong; Angelidaki, Irini

    2008-01-01

    Biohydrogen could efficiently be produced in glucose-fed biofilm reactors filled with plastic carriers and operated at 70°C. Batch experiments were, in addition, conducted to enrich and cultivate glucose-fed extremethermophilic hydrogen producing microorganisms from a biohydrogen CSTR reactor fed...... with synthetic medium with glucose as the only carbon and energy source. A biofilm reactor, started up with plastic carriers, that were previously inoculated with the enrichment cultures, resulted in higher hydrogen yield (2.21 mol H2/mol glucose consumed) but required longer start up time (1 month), while...

  2. Single-cell twitching chemotaxis in developing biofilms.

    Science.gov (United States)

    Oliveira, Nuno M; Foster, Kevin R; Durham, William M

    2016-06-01

    Bacteria form surface-attached communities, known as biofilms, which are central to bacterial biology and how they affect us. Although surface-attached bacteria often experience strong chemical gradients, it remains unclear whether single cells can effectively perform chemotaxis on surfaces. Here we use microfluidic chemical gradients and massively parallel automated tracking to study the behavior of the pathogen Pseudomonas aeruginosa during early biofilm development. We show that individual cells can efficiently move toward chemoattractants using pili-based "twitching" motility and the Chp chemosensory system. Moreover, we discovered the behavioral mechanism underlying this surface chemotaxis: Cells reverse direction more frequently when moving away from chemoattractant sources. These corrective maneuvers are triggered rapidly, typically before a wayward cell has ventured a fraction of a micron. Our work shows that single bacteria can direct their motion with submicron precision and reveals the hidden potential for chemotaxis within bacterial biofilms. PMID:27222583

  3. Biological treatment of para-chlorophenol containing synthetic wastewater using rotating brush biofilm reactor

    International Nuclear Information System (INIS)

    A novel rotating brush biofilm reactor (RBBR) was used for para-chlorophenol (4-chlorophenol, 4-CP), COD and toxicity removal from synthetic wastewater containing different concentrations of 4-CP. Effects of major operating variables such as the feed 4-CP and COD concentrations and A/Q (biofilm surface area/feed flow rate) ratio on the performance of the biofilm reactor were investigated. A Box-Wilson statistical experiment design method was used by considering the feed 4-CP (0-1000 mg l-1), COD (2000-6000 mg l-1) and A/Q ratio (73-293 m2 day m-3) as the independent variables while the 4-CP, COD and toxicity removals were the objective functions. The results were correlated by a response function and the coefficients were determined by regression analysis. Percent 4-CP, COD and toxicity removals determined from the response functions were in good agreement with the experimental results. 4-CP, COD and toxicity removals increased with decreasing feed 4-CP and increasing A/Q ratio. Optimum conditions resulting in maximum COD, 4-CP and toxicity removals were found to be A/Q ratio of nearly 180 m2 day m-3, feed COD of nearly 4000 mg l-1 and feed 4-CP of less than 205 mg l-1

  4. Development of a High-Throughput Candida albicans Biofilm Chip

    OpenAIRE

    Srinivasan, Anand; Uppuluri, Priya; Lopez-Ribot, Jose; Ramasubramanian, Anand K.

    2011-01-01

    We have developed a high-density microarray platform consisting of nano-biofilms of Candida albicans. A robotic microarrayer was used to print yeast cells of C. albicans encapsulated in a collagen matrix at a volume as low as 50 nL onto surface-modified microscope slides. Upon incubation, the cells grow into fully formed “nano-biofilms”. The morphological and architectural complexity of these biofilms were evaluated by scanning electron and confocal scanning laser microscopy. The extent of bi...

  5. Degradation of formaldehyde in anaerobic sequencing batch biofilm reactor (ASBBR)

    International Nuclear Information System (INIS)

    The present study evaluated the degradation of formaldehyde in a bench-scale anaerobic sequencing batch reactor, which contained biomass immobilized in polyurethane foam matrices. The reactor was operated for 212 days at 35 deg. C with 8 h sequential cycles, under different affluent formaldehyde concentrations ranging from 31.6 to 1104.4 mg/L (formaldehyde loading rates from 0.08 to 2.78 kg/m3 day). The results indicate excellent reactor stability and over 99% efficiency in formaldehyde removal, with average effluent formaldehyde concentration of 3.6 ± 1.7 mg/L. Formaldehyde degradation rates increased from 204.9 to 698.3 mg/L h as the initial concentration of formaldehyde was increased from around 100 to around 1100 mg/L. However, accumulation of organic matter was observed in the effluent (chemical oxygen demand (COD) values above 500 mg/L) due to the presence of non-degraded organic acids, especially acetic and propionic acids. This observation poses an important question regarding the anaerobic route of formaldehyde degradation, which might differ substantially from that reported in the literature. The anaerobic degradation pathway can be associated with the formation of long-chain oligomers from formaldehyde. Such long- or short-chain polymers are probably the precursors of organic acid formation by means of acidogenic anaerobic microorganisms

  6. Bioreduction of Chromate in a Methane-Based Membrane Biofilm Reactor.

    Science.gov (United States)

    Lai, Chun-Yu; Zhong, Liang; Zhang, Yin; Chen, Jia-Xian; Wen, Li-Lian; Shi, Ling-Dong; Sun, Yan-Ping; Ma, Fang; Rittmann, Bruce E; Zhou, Chen; Tang, Youneng; Zheng, Ping; Zhao, He-Ping

    2016-06-01

    For the first time, we demonstrate chromate (Cr(VI)) bioreduction using methane (CH4) as the sole electron donor in a membrane biofilm reactor (MBfR). The experiments were divided into five stages lasting a total of 90 days, and each stage achieved a steady state for at least 15 days. Due to continued acclimation of the microbial community, the Cr(VI)-reducing capacity of the biofilm kept increasing. Cr(VI) removal at the end of the 90-day test reached 95% at an influent Cr(VI) concentration of 3 mg Cr/L and a surface loading of 0.37g of Cr m(-2) day(-1). Meiothermus (Deinococci), a potential Cr(VI)-reducing bacterium, was negligible in the inoculum but dominated the MBfR biofilm after Cr(VI) was added to the reactor, while Methylosinus, a type II methanotrophs, represented 11%-21% of the total bacterial DNA in the biofilm. Synergy within a microbial consortia likely was responsible for Cr(VI) reduction based on CH4 oxidation. In the synergy, methanotrophs fermented CH4 to produce metabolic intermediates that were used by the Cr(VI)-reducing bacteria as electron donors. Solid Cr(III) was the main product, accounting for more than 88% of the reduced Cr in most cases. Transmission electron microscope (TEM) and energy dispersive X-ray (EDS) analysis showed that Cr(III) accumulated inside and outside of some bacterial cells, implying that different Cr(VI)-reducing mechanisms were involved. PMID:27161770

  7. Treatment of oilfield wastewater in moving bed biofilm reactors using a novel suspended ceramic biocarrier

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Zhiyong, E-mail: bluemanner@163.com [State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249 (China); Lu, Mang [School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, Jiangxi Province (China); Huang, Wenhui [School of Energy Resources, China University of Geosciences, Beijing 100083 (China); Xu, Xiaochun [School of Geosciences and Resources, China University of Geosciences, Beijing 100083 (China)

    2011-11-30

    Highlights: Black-Right-Pointing-Pointer We invented a novel suspended ceramic carrier. Black-Right-Pointing-Pointer The suspended ceramic carrier is modified with sepiolite. Black-Right-Pointing-Pointer The carriers were used in MBBR to remediate wastewater. - Abstract: In this study, a novel suspended ceramic carrier was prepared, which has high strength, optimum density (close to water), and high porosity. Two different carriers, unmodified and sepiolite-modified suspended ceramic carriers were used to feed two moving bed biofilm reactors (MBBRs) with a filling fraction of 50% to treat oilfield produced water. The hydraulic retention time (HRT) was varied from 36 to 10 h. The results, during a monitoring period of 190 days, showed that removal efficiency of chemical oxygen demand was the highest in reactor 3 filled with the sepiolite-modified carriers, followed by reactor 2 filled with the unmodified carriers, with the lowest in reactor 1 (activated sludge reactor), at an HRT of 10 h. Similar trends were found in the removal efficiencies of ammonia nitrogen and polycyclic aromatic hydrocarbons. Reactor 3 was more shock resistant than reactors 2 and 1. The results indicate that the suspended ceramic carrier is an excellent MBBR carrier.

  8. Treatment of oilfield wastewater in moving bed biofilm reactors using a novel suspended ceramic biocarrier

    International Nuclear Information System (INIS)

    Highlights: ► We invented a novel suspended ceramic carrier. ► The suspended ceramic carrier is modified with sepiolite. ► The carriers were used in MBBR to remediate wastewater. - Abstract: In this study, a novel suspended ceramic carrier was prepared, which has high strength, optimum density (close to water), and high porosity. Two different carriers, unmodified and sepiolite-modified suspended ceramic carriers were used to feed two moving bed biofilm reactors (MBBRs) with a filling fraction of 50% to treat oilfield produced water. The hydraulic retention time (HRT) was varied from 36 to 10 h. The results, during a monitoring period of 190 days, showed that removal efficiency of chemical oxygen demand was the highest in reactor 3 filled with the sepiolite-modified carriers, followed by reactor 2 filled with the unmodified carriers, with the lowest in reactor 1 (activated sludge reactor), at an HRT of 10 h. Similar trends were found in the removal efficiencies of ammonia nitrogen and polycyclic aromatic hydrocarbons. Reactor 3 was more shock resistant than reactors 2 and 1. The results indicate that the suspended ceramic carrier is an excellent MBBR carrier.

  9. Reactor simulator development. Workshop material

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) has established a programme in nuclear reactor simulation computer programs to assist its Member States in education and training. The objective is to provide, for a variety of advanced reactor types, insight and practice in reactor operational characteristics and their response to perturbations and accident situations. To achieve this, the IAEA arranges for the supply or development of simulation programs and training material, sponsors training courses and workshops, and distributes documentation and computer programs. This publication consists of course material for workshops on development of such reactor simulators. Participants in the workshops are provided with instruction and practice in the development of reactor simulation computer codes using a model development system that assembles integrated codes from a selection of pre-programmed and tested sub-components. This provides insight and understanding into the construction and assumptions of the codes that model the design and operational characteristics of various power reactor systems. The main objective is to demonstrate simple nuclear reactor dynamics with hands-on simulation experience. Using one of the modular development systems, CASSIMtm , a simple point kinetic reactor model is developed, followed by a model that simulates the Xenon/Iodine concentration on changes in reactor power. Lastly, an absorber and adjuster control rod, and a liquid zone model are developed to control reactivity. The built model is used to demonstrate reactor behavior in sub-critical, critical and supercritical states, and to observe the impact of malfunctions of various reactivity control mechanisms on reactor dynamics. Using a PHWR simulator, participants practice typical procedures for a reactor startup and approach to criticality. This workshop material consists of an introduction to systems used for developing reactor simulators, an overview of the dynamic simulation

  10. Natural genetic transformation in Acinetobacter sp. BD413 Biofilms: introducing natural genetic transformation as a tool for bioenhancement of biofilm reactors

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickx, L.

    2002-07-01

    This study focussed on the localization and quantification of natural genetic transformation using neutral and disadvantageous genes in monoculture biofilms to investigate gene transfer and expression of the transferred genes in the absence of a selective advantage. Data obtained by this investigation were regarded as initial steps for evaluating the applicability of adding catabolic traits into the indigenous bacterial community of biofilm reactors by in situ natural genetic transformation. Because Acinetobacter spp. strains are readily found in waste water treatment plants and because Acinetobacter sp. BD413 possesses a high effective level of competence, natural genetic transformation was investigated in monoculture Acinetobacter sp. BD413 biofilms. The genes used for transformation encoded for the green fluorescent protein (GFP) and its variants. Monitoring of transformation events were performed with the use of automated confocal laser scanning microscopy (CLSM) and semi automated digital image processing and analysis. (orig.)

  11. A fungal biofilm reactor based on metal structured packing improves the quality of a Gla::GFP fusion protein produced by Aspergillus oryzae

    OpenAIRE

    Zune, Quentin; Delepierre, Anissa; Gofflot, Sebastien; Bauwens, Julien; Twizere, Jean-Claude; Punt, P. J.; Francis, Frédéric; Bawin, Thomas; Toye, Dominique; Delvigne, Frank

    2015-01-01

    Fungal biofilm is known to promote the excretion of secondary metabolites in accordance with solid-state related physiological mechanisms. This work is based on the comparative analysis of classical submerged fermentation with a fungal biofilm reactor for the production of a Gla::GFP fusion protein by Aspergillus oryzae. The biofilm reactor comprises a metal structured packing allowing the attachment of the fungal biomass. Since the production of the target protein is under the control of the...

  12. Biofilm Fixed Film Systems

    Directory of Open Access Journals (Sweden)

    Dipesh Das

    2011-09-01

    Full Text Available The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, rotating biological contactors, fluidized bed bioreactors, submerged bed biofilm reactors, biological granular activated carbon, membrane bioreactors, and immobilized cell reactors. Innovative reactors, not easily classified, are then presented, followed by a section on biofilms on sand, soil and sediment.

  13. How Staphylococcus aureus biofilms develop their characteristic structure

    OpenAIRE

    Periasamy, Saravanan; Joo, Hwang-Soo; Duong, Anthony C.; Bach, Thanh-Huy L.; Tan, Vee Y.; Chatterjee, Som S.; Cheung, Gordon Y. C.; Otto, Michael

    2012-01-01

    Biofilms cause significant problems in the environment and during the treatment of infections. However, the molecular mechanisms underlying biofilm formation are poorly understood. There is a particular lack of knowledge about biofilm maturation processes, such as biofilm structuring and detachment, which are deemed crucial for the maintenance of biofilm viability and the dissemination of cells from a biofilm. Here, we identify the phenol-soluble modulin (PSM) surfactant peptides as key biofi...

  14. Phosphorus removal by a fixed-bed hybrid polymer nanocomposite biofilm reactor

    OpenAIRE

    M. de OLIVEIRA; A.L. Rodrigues; Ribeiro, D. C.; R. Nogueira; Machado, A.V.

    2014-01-01

    Eutrophication is one of the main challenges regarding the ecological quality of surface waters, phosphorus bioavailability being its main driver. In this context, a novel hybrid polymer nanocomposite (HPN-Pr) biofilm reactor aimed at integrated chemical phosphorus adsorption and biological removal was conceived. The assays pointed to removal of 1.2 mg P/g of reactive phosphorus and 1.01 mg P/g of total phosphorus under steady-state conditions. A mathematical adsorption–biological model was a...

  15. Assessing the antimicrobial activity of zinc oxide thin films using disk diffusion and biofilm reactor

    International Nuclear Information System (INIS)

    The electronic and chemical properties of semiconductor materials may be useful in preventing growth of microorganisms. In this article, in vitro methods for assessing microbial growth on semiconductor materials will be presented. The structural and biological properties of silicon wafers coated with zinc oxide thin films were evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, and MTT viability assay. The antimicrobial properties of zinc oxide thin films were established using disk diffusion and CDC Biofilm Reactor studies. Our results suggest that zinc oxide and other semiconductor materials may play a leading role in providing antimicrobial functionality to the next-generation medical devices

  16. Molecular Basis for Saccharomyces cerevisiae Biofilm Development

    DEFF Research Database (Denmark)

    Andersen, Kaj Scherz

    In this study, I sought to identify genes regulating the global molecular program for development of sessile multicellular communities, also known as biofilm, of the eukaryotic microorganism, Saccharomyces cerevisiae (yeast). Yeast biofilm has a clinical interest, as biofilms can cause chronic...

  17. Nitrogen and carbon removal efficiency of a polyvinyl alcohol gel based moving bed biofilm reactor system.

    Science.gov (United States)

    Gani, Khalid Muzamil; Singh, Jasdeep; Singh, Nitin Kumar; Ali, Muntjeer; Rose, Vipin; Kazmi, A A

    2016-01-01

    In this study, the effectiveness of polyvinyl alcohol (PVA) gel beads in treating domestic wastewater was investigated: a moving bed biofilm reactor (MBBR) configuration (oxic-anoxic and oxic) with 10% filling fraction of biomass carriers was operated in a continuously fed regime at temperatures of 25, 20, 15 and 6 °C with hydraulic retention times (HRTs) of 32 h, 18 h, 12 h and 9 h, respectively. Influent loadings were in the range of 0.22-1.22 kg N m(-3) d(-1) (total nitrogen (TN)), 1.48-7.82 kg chemical oxygen demand (COD) m(-3) d(-1) (organic) and 0.12-0.89 kg NH4(+)-N m(-3)d(-1) (ammonia nitrogen). MBBR performance resulted in the maximum TN removal rate of 1.22 kg N m(-3) d(-1) when the temperature and HRT were 6 °C and 9 h, respectively. The carbon removal rate at this temperature and HRT was 6.82 kg COD m(-3) d(-1). Ammonium removal rates ranged from 0.13 to 0.75 kg NH4(+)-N m(-3) d(-1) during the study. Total phosphorus and suspended solid removal efficiency ranged from 84 to 98% and 85 to 94% at an influent concentration of 3.3-7.1 mg/L and 74-356 mg/L, respectively. The sludge wasted from the MBBR exhibited light weight features characterized by sludge volume index value of 185 mL/g. Experimental data obtained can be useful in further developing the concept of PVA gel based wastewater treatment systems. PMID:27054722

  18. Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    Huiqiang Li; Hongjun Han; Maoan Du; Wei Wang

    2011-01-01

    Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater.Nitrification of the MBBR was inhibited almost completely during start-up period.Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition.Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little effect on nitrification recovery.Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days.Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water.The ratio of nitrification decreased to 25% when infiuent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70%for another 4 days.

  19. Autotrophic nitrogen removal in one lab-scale vertical submerged biofilm reactor

    Science.gov (United States)

    Liang, Zhiwei; Chen, Yingxu; Li, Wenhong; Yang, Shangyuan; Du, Ping

    In this study, the process performance of a new vertical submerged biofilm reactor for complete autotrophic ammonia removal was investigated using synthetic wastewater. The main objectives of this study were to evaluate the flexibility of the reactor, achieve partial autotrophic nitrification with influent ammonium nitrogen ranging from 40 to 280 mg L -1, and achieve a stable half partial autotrophic nitrification by controlling hydraulic retention time (HRT) and alkalinity. A very low concentration of nitrate was observed in the effluent during nitrification. Then autotrophic denitrification revealed Anammox bacteria were present and active in the central anaerobic parts of the bioreactor which was inoculated with a mixed microbial consortium from activated sludge. The results of this study demonstrated that autotrophic denitrification processes can coexist with heterotrophic denitrifying processes in the same environment even if Anammox bacteria were less competitive than heterotrophic denitrifying bacteria.

  20. Effect of the kinetics of ammonium and nitrite oxidation on nitritation success or failure for different biofilm reactor geometries

    DEFF Research Database (Denmark)

    Lackner, Susanne; Smets, Barth F.

    2012-01-01

    The effect of biokinetics on nitritation was investigated in two biofilm geometries, the Membrane Aerated Biofilm Reactor (MABR) and a conventional biofilm system. A 1D biofilm model was used and evaluated by global sensitivity analysis using the variance based Sobol method. The main focus was on...... the influence of key biokinetic parameters (maximum specific growth rates, oxygen and nitrogen affinity constants of AOB (ammonium oxidizing bacteria) and NOB (nitrite oxidizing bacteria)) and their ratios on nitritation efficiency in these geometries. This exhaustive simulation study revealed that...... nitritation strongly depends on the chosen kinetic parameters of AOB and NOB. The maximum specific growth rates (μmax,AOB and μmax,NOB) had the strongest impact on nitritation efficiency (NE). In comparison, the counter-diffusion geometry yielded more parameter combinations (27.5%) that resulted in high NE...

  1. A review of investigations on wastewater treatment with MSOBR (membrane supported and oxygenated biofilm reactors); Una revision de las investigaciones sobre el tratamiento de aguas residuales con RBSOM (reactores de biopelicula que emplean membranas con material soporte y medio de oxigenacion)

    Energy Technology Data Exchange (ETDEWEB)

    Esteban Garcia, A. L.; Tejero Monzon, I.

    2007-07-01

    MSOBR (membrane supported and oxygenated biofilm reactors) are biological reactors for wastewater treatment in which biofilm support and oxygenation functions are carried out by gas permeable membranes. In these conditions, with oxygen and substratum (carbonaceous, nitroge neous) diffusing into the biofilm from opposite sides, different environments are developed inside the biofilm, allowing simultaneous nitrification, denitrification and carbon removal. Other added advantages, such us the possibility of a high oxygen transfer efficiency or those derived from the absence of bubbles in aeration (minimizing foaming and VOC emissions), have lead numerous research groups to work in the development of different MSOBR systems, with promising results that make possible to consider their practical applicability in the near future. (Author) 69 refs.

  2. Aerobic moving bed biofilm reactor treating thermomechanical pulping whitewater under thermophilic conditions.

    Science.gov (United States)

    Jahren, Sigrun J; Rintala, Jukka A; Odegaard, Hallvard

    2002-02-01

    The continuously operated laboratory scale Kaldnes moving bed biofilm reactor (MBBR) was used for thermophilic (55 degrees C) aerobic treatment of TMP whitewater. In the MBBR, the biomass is grown on carrier elements that move along with the water in the reactor. Inoculation with mesophilic activated sludge gave 60-65% SCOD removal from the first day onwards. During the 107 days of experiment, the 60-65% SCOD removals were achieved at organic loading rates of 2.5-3.5 kg SCODm(-3) d(-1), the highest loading rates applied during the run and HRT of 13-22h. Carbohydrates, which contributed to 50-60% of the influent SCOD. were removed by 90-95%, while less than 15% of the lignin-like material (30-35% of SCODin) was removed. The sludge yield was 0.23g VSSg SCOD(-1)removed. The results show that the aerobic biofilm process can be successfully operated under thermophilic conditions. PMID:11848344

  3. Inhibition of perchlorate reduction by nitrate in a fixed biofilm reactor

    International Nuclear Information System (INIS)

    Perchlorate and nitrate were reduced simultaneously in fixed biofilm reactors. Reduction of 1000 μg L-1 perchlorate decreased slightly with the addition of 10-16 mg L-1 NO3-N when excess acetate was supplied while denitrification was complete. When influent acetate was reduced by 50% to well below the stoichiometric requirement, perchlorate reduction decreased by 70% while denitrification decreased by only 20%, suggesting that competition for electrons by nitrate was a factor in inhibition. Reduction of nitrate was favored over perchlorate, even though reactor biofilm had been enriched under perchlorate-reducing conditions for 10 months. When excess acetate was restored, perchlorate and nitrate returned to initial levels. The average most probable numbers of perchlorate- and nitrate-reducing bacteria during excess substrate operation were not significantly different and ranged between 2.0 x 105 and 7.9 x 105 cells cm-2 media surface area. The effect of nitrate on chloride generation by suspensions of perchlorate-reducing populations was studied using a chloride ion probe. The rate of reduction of 2 mM perchlorate decreased by 30% in the presence of 2 mM nitrate when excess acetate was added. When acetate was limited, perchlorate reduction decreased by 70% in the presence of equi-molar nitrate

  4. Modelisation of Nitrification under Inhibited Environment by Moving Bed Bio-Film Reactor Technique

    Directory of Open Access Journals (Sweden)

    Pham T.H. Duc

    2010-01-01

    Full Text Available Problem statement: Nitrification by Moving Bed Biofilm Reactor (MBBR involves physical, chemical and biological processes to remove toxic ammonia for aquaculture that are governed by a variety of parameters, like substrate and dissolved oxygen concentrations, organic matters, temperature, pH, alkalinity and turbulence level, which impact negatively or positively on nitrification kinetics. Approach: The situation becomes more serious as the reaction rate is inhibited by low ammonium concentration and high salinity. That problems usually occur in treatment systems of aquatic breeding hatcheries. Results: In this study, experiments have been conducted to evaluate the impact of salinity on nitrification rate through kinetic constant (k and reaction order (n based on general equation v = kCn. Moving bed biofilm reactor was operated continuously at same initial amounts of nitrogen and Phosphorus very low (oligotrophic conditions. Firstly, over view the impact of salinity on kinetic rate to modeling that effect k and n to modelisation that affects and obtained the impact of salinity content in the reaction medium (X and the acclimatization phase (Y on the kinetic constant (k = 0.097 e (-0.0003Yƒ{0.0346X and on the kinetic order (n = (0.0002Y-0.0195 X-0.009Y + 1.2382. Conclusion/Recommendations: Results from kinetic analysis allowed the prediction of the reaction rate and reaction yield with rather high accuracy, helping the design and operation of a biofilter under practical conditions.

  5. Effect of pipe material and low level disinfectants on biofilm development in a simulated drinking water distribution system

    Institute of Scientific and Technical Information of China (English)

    Ling-ling ZHOU; Yong-ji ZHANG; Gui-bai LI

    2009-01-01

    The efficiency of chlorine and chloramines disinfection on biofilm development in a simulated drinking water distribution system was investigated by using heterotrophic bacterial spread plate technique.The experiments were carried out with four annular reactors(ARs)with stainless steel(SS)or copper(Cu)material slides.The results showed that there were fewer bacteria attached to Cu slides without a disinfectant compared with those attached to SS slides.When the water was disinfected with chloramines,the heterotrophic plate counts(HPCs)on the biofilm attached to the Cu slides were significantly lower(by 3.46 log CFU/cm2)than those attached to the SS slides.Likewise,the biofilm HPC numbers on the Cu slides were slightly lower(by 1.19log CFU/cm2) than those on the SS slides disinfected with chlorine.In a quasi-steady state.the HPC levels on Cu slides can be reduced to 3.0 log CFU/cm2 with chlorine and to about 0.9 log CFU/cm2 with chloramines.The addition of chloramines resulted in a more efficient reduction of biofilm heterotrophic bacteria than did chlorine.We concluded that the chlorine and chloramines levels usually employed in water distribution system were not SUfficient to prevent the growth and development of microbial biofilm.The combination of copper pipe slides and chlorarnincs as the disinfectant was the most efficient combination to bring about diminished bacterial levels.

  6. Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

    Directory of Open Access Journals (Sweden)

    Demirci Ali

    2009-07-01

    Full Text Available Abstract Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, thermogravimetric analysis (TGA, and dynamic mechanical analysis (DMA. Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L that was 2.5-fold greater than the control (2.82 g/L. The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93% and similar crystal size (5.2 nm to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to

  7. APPLICATIONS OF BIOTECHNOLOGY IN DEVELOPMENT OF BIOMATERIALS: NANOTECHNOLOGY AND BIOFILMS

    Energy Technology Data Exchange (ETDEWEB)

    Brigmon, R.; Berry, T.; Narayan, R.

    2010-11-29

    Biotechnology is the application of biological techniques to develop new tools and products for medicine and industry. Due to various properties including chemical stability, biocompatibility, and specific activity, e.g. antimicrobial properties, many new and novel materials are being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. Many of these materials are less than 100 nanometers in size. Nanotechnology is the engineering discipline encompassing designing, producing, testing, and using structures and devices less than 100 nanometers. One of the challenges associated with biomaterials is microbial contamination that can lead to infections. In recent work we have examined the functionalization of nanoporous biomaterials and antimicrobial activities of nanocrystalline diamond materials. In vitro testing has revealed little antimicrobial activity against Pseudomonas fluorescens bacteria and associated biofilm formation that enhances recalcitrance to antimicrobial agents including disinfectants and antibiotics. Laser scanning confocal microscopy studies further demonstrated properties and characteristics of the material with regard to biofilm formation.

  8. A simple flow cell for monitoring biofilm formation in laboratory and industrial conditions

    OpenAIRE

    Pereira, Maria Olívia; Vieira, M. J.; Melo, L. F.

    2000-01-01

    This work proposes and discusses a simple flow cell reactor that provides a means to monitoring biofilm growth by periodical removing biofilm-attached slides for off-line, nondestructive and destructive biofilm analysis without the stoppage of the flow. With this flow cell, biofilm growth and respiratory activity can be easily followed, either in well defined laboratory conditions or in an industrial environment. The reproducible and typical biofilm development curves obtained ...

  9. 电极生物膜法反硝化工艺研究进展%Progress in the research on denitrification process by biofilm-electrode reactor

    Institute of Scientific and Technical Information of China (English)

    蓝梅; 刘晓露; 赵军; 张佳媛

    2012-01-01

    电极生物膜法反硝化是一种新型的将电化学法与生物膜法相结合的生物反硝化方法.特别在缺乏碳源时,该法为反硝化提供了一种新的途径.结合国内外对电极生物膜法反硝化的研究发展,系统介绍了电极生物膜法反硝化工艺的影响因素,同时指出该工艺在电极材料的选择、反应器构型设计、电化学和生物膜协同作用的原理与条件优化方面存在的问题和今后的研究发展趋势.%Biofilm-electrode denitrification is a novel method which combines electrochemical method with biofilm process. It provides a new approach,especially when there is lack of carbon source for denitrification. According to the development of research on denitrification by biofilm-electrode reactor in China and aboard,the factors influencing denitrification by biofilm-electrode reactor are introduced systematically. At the same time,the problems existed in the aspects, such as the selection of electrode materials in this process, the design of reactor configuration, and the principle and condition optimization of the synergistic effect between electrochemistry and bio-film,as well as the trend of future research development, are put forward.

  10. Modulation of crystalline Proteus mirabilis biofilm development on urinary catheters.

    Science.gov (United States)

    Stickler, David J; Morgan, Sheridan D

    2006-05-01

    The crystalline biofilms formed by Proteus mirabilis can seriously complicate the care of patients undergoing long-term bladder catheterization. The generation of alkaline urine by the bacterial urease causes calcium and magnesium phosphates to precipitate from urine and accumulate in the catheter biofilm, blocking the flow of urine from the bladder. The pH at which these salts crystallize from a urine sample, the nucleation pH (pH(n)), can be elevated by diluting the urine and by increasing its citrate content. The aim of this study was to examine whether manipulation of pH(n) in these ways modulated the rate at which crystalline biofilm developed. Experiments in laboratory models of the catheterized bladder infected with P. mirabilis showed that when the bladder was supplied with a concentrated urine (pH(n) 6.7) at a low fluid output (720 ml per 24 h), catheters blocked at 19-31 h. Diluting this urine 1:4 increased the pH(n) to 7.5 and models supplied with this urine at 2880 ml per 24 h took 110-137 h to block. When models were supplied with urine containing citrate at 1.5 mg ml(-1) or above (pH(n) 8.3-9.1), the catheters drained freely for the full 7 day experimental period. Scanning electron microscopy revealed that the catheter biofilms that developed in urine with high pH(n) values were devoid of crystalline formations. These observations should encourage a clinical trial to examine the effect of increasing a patient's fluid intake with citrate-containing drinks on the encrustation and blockage of catheters. PMID:16585633

  11. Analysis of Microbial Communities in Biofilms from CSTR-Type Hollow Fiber Membrane Biofilm Reactors for Autotrophic Nitrification and Hydrogenotrophic Denitrification.

    Science.gov (United States)

    Shin, Jung-Hun; Kim, Byung-Chun; Choi, Okkyoung; Kim, Hyunook; Sang, Byoung-In

    2015-10-28

    Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH4(+)-N/m(3)/d and 0.10-0.21 kg NO3(-)-N/m(3)/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH4(+) or NO3(-) loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs. PMID:26095385

  12. A steady-state biofilm model for simultaneous reduction of nitrate and perchlorate, part 1: model development and numerical solution.

    Science.gov (United States)

    Tang, Youneng; Zhao, Heping; Marcus, Andrew K; Krajmalnik-Brown, Rosa; Rittmann, Bruce E

    2012-02-01

    A multispecies biofilm model is developed for simultaneous reduction of nitrate and perchlorate in the H(2)-based membrane biofilm reactor. The one-dimension model includes dual-substrate Monod kinetics for a steady-state biofilm with five solid and five dissolved components. The solid components are autotrophic denitrifying bacteria, autotrophic perchlorate-reducing bacteria, heterotrophic bacteria, inert biomass, and extracellular polymeric substances (EPS). The dissolved components are nitrate, perchlorate, hydrogen (H(2)), substrate-utilization-associated products, and biomass-associated products (BAP). The model explicitly considers four mechanisms involved in how three important operating conditions (H(2) pressure, nitrate loading, and perchlorate loading) affect nitrate and perchlorate removals: (1) competition for H(2), (2) promotion of PRB growth due to having two electron acceptors (nitrate and perchlorate), (3) competition between nitrate and perchlorate reduction for the same resources in the PRB: electrons and possibly reductase enzymes, and (4) competition for space in the biofilm. Two other special features are having H(2) delivered from the membrane substratum and solving directly for steady state using a novel three-step approach: finite-difference for approximating partial differential and/or integral equations, Newton-Raphson for solving nonlinear equations, and an iterative scheme to obtain the steady-state biofilm thickness. An example result illustrates the model's features. PMID:22191376

  13. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems

    OpenAIRE

    Mazioti, Aikaterini A.; Stasinakis, Athanasios S.; Pantazi, Ypapanti; Andersen, Henrik Rasmus

    2015-01-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The Activated Sludge system was operated under low organic loading conditions. The Moving Bed Biofilm Reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed p...

  14. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems

    DEFF Research Database (Denmark)

    Mazioti, Aikaterini A.; Stasinakis, Athanasios S.; Pantazi, Ypapanti; Andersen, Henrik Rasmus

    2015-01-01

    Biofilm Reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in...... biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic....

  15. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    Science.gov (United States)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-01-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  16. Effects of Iron Chelators on the Formation and Development of Aspergillus fumigatus Biofilm.

    Science.gov (United States)

    Nazik, Hasan; Penner, John C; Ferreira, Jose A; Haagensen, Janus A J; Cohen, Kevin; Spormann, Alfred M; Martinez, Marife; Chen, Vicky; Hsu, Joe L; Clemons, Karl V; Stevens, David A

    2015-10-01

    Iron acquisition is crucial for the growth of Aspergillus fumigatus. A. fumigatus biofilm formation occurs in vitro and in vivo and is associated with physiological changes. In this study, we assessed the effects of Fe chelators on biofilm formation and development. Deferiprone (DFP), deferasirox (DFS), and deferoxamine (DFM) were tested for MIC against a reference isolate via a broth macrodilution method. The metabolic effects (assessed by XTT [2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt]) on biofilm formation by conidia were studied upon exposure to DFP, DFM, DFP plus FeCl3, or FeCl3 alone. A preformed biofilm was exposed to DFP with or without FeCl3. The DFP and DFS MIC50 against planktonic A. fumigatus was 1,250 μM, and XTT gave the same result. DFM showed no planktonic inhibition at concentrations of ≤2,500 μM. By XTT testing, DFM concentrations of biofilms forming in A. fumigatus or preformed biofilms (P biofilm formation (P Biofilm formation with 625 μM DFP plus any concentration of FeCl3 was lower than that in the controls (P biofilms, DFP in the range of ≥625 to 1,250 μM was inhibitory compared to the controls (P biofilm formation (P biofilm increased with 2,500 μM FeCl3 only (P biofilms of A. fumigatus clinical isolates to DFP were noted. In conclusion, iron stimulates biofilm formation and preformed biofilms. Chelators can inhibit or enhance biofilms. Chelation may be a potential therapy for A. fumigatus, but we show here that chelators must be chosen carefully. Individual isolate susceptibility assessments may be needed. PMID:26239975

  17. Applying insights from biofilm biology to drug development - can a new approach be developed?

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Ciofu, Oana; Molin, Søren;

    2013-01-01

    Most of the research on bacterial pathogenesis has focused on acute infections, but much less is known about the pathogenesis of infections caused by bacteria that grow as aggregates in biofilms. These infections tend to be chronic as they resist innate and adaptive immune defence mechanisms as w...... pathology, and discuss how a deep insight into the physical and biological characteristics of biofilms can inform therapeutic strategies and molecular targets for the development of anti-biofilm drugs.......Most of the research on bacterial pathogenesis has focused on acute infections, but much less is known about the pathogenesis of infections caused by bacteria that grow as aggregates in biofilms. These infections tend to be chronic as they resist innate and adaptive immune defence mechanisms as...... well as antibiotics, and the treatment of biofilm infections presents a considerable unmet clinical need. To date, there are no drugs that specifically target bacteria in biofilms; however, several approaches are in early-stage development. Here, we review current insights into biofilm physiology and...

  18. Medical Biofilms

    OpenAIRE

    Bryers, James D.

    2008-01-01

    For more than two decades, Biotechnology and Bioengineering has documented research focused on natural and engineered microbial biofilms within aquatic and subterranean ecosystems, wastewater and waste-gas treatment systems, marine vessels and structures, and industrial bioprocesses. Compared to suspended culture systems, intentionally engineered biofilms are heterogeneous reaction systems that can increase reactor productivity, system stability, and provide inherent cell: product separation....

  19. An integrated mathematical model for chemical oxygen demand (COD) removal in moving bed biofilm reactors (MBBR) including predation and hydrolysis.

    Science.gov (United States)

    Revilla, Marta; Galán, Berta; Viguri, Javier R

    2016-07-01

    An integrated mathematical model is proposed for modelling a moving bed biofilm reactor (MBBR) for removal of chemical oxygen demand (COD) under aerobic conditions. The composite model combines the following: (i) a one-dimensional biofilm model, (ii) a bulk liquid model, and (iii) biological processes in the bulk liquid and biofilm considering the interactions among autotrophic, heterotrophic and predator microorganisms. Depending on the values for the soluble biodegradable COD loading rate (SCLR), the model takes into account a) the hydrolysis of slowly biodegradable compounds in the bulk liquid, and b) the growth of predator microorganisms in the bulk liquid and in the biofilm. The integration of the model and the SCLR allows a general description of the behaviour of COD removal by the MBBR under various conditions. The model is applied for two in-series MBBR wastewater plant from an integrated cellulose and viscose production and accurately describes the experimental concentrations of COD, total suspended solids (TSS), nitrogen and phosphorous obtained during 14 months working at different SCLRs and nutrient dosages. The representation of the microorganism group distribution in the biofilm and in the bulk liquid allow for verification of the presence of predator microorganisms in the second reactor under some operational conditions. PMID:27085154

  20. Novel nitrifiers and comammox in a full-scale hybrid biofilm and activated sludge reactor revealed by metagenomic approach.

    Science.gov (United States)

    Chao, Yuanqing; Mao, Yanping; Yu, Ke; Zhang, Tong

    2016-09-01

    Biofilms are widely used in wastewater treatment for their particular enhancement of nitrogen removal and other significant advantages. In this study, the diversity and potential functions of nitrogen removal bacteria in suspended activated sludge (AS) and biofilm of a full-scale hybrid reactor were uncovered by metagenomes (∼34 Gb), coupled with PCR-based 454 reads (>33 K reads). The results indicated that the diversity and abundance of nitrifiers and denitrifiers in biofilm did not surpass that in AS, while more nitrification and denitrification genes were indeed found in biofilm than AS, suggesting that the increased nitrogen removal ability by applying biofilm might be attributed to the enhancement of removal efficiency, rather than the biomass accumulation of nitrogen removal bacteria. The gene annotation and phylogenetic analysis results revealed that AS and biofilm samples consisted of 6.0 % and 9.4 % of novel functional genes for nitrogen removal and 18 % and 30 % of new Nitrospira species for nitrite-oxidizing bacteria, respectively. Moreover, the identification of Nitrospira-like amoA genes provided metagenomic evidence for the presence of complete ammonia oxidizer (comammox) with the functional potential to perform the complete oxidation of ammonia to nitrate. These findings have significant implications in expanding our knowledge of the biological nitrogen transformations in wastewater treatment. PMID:27287850

  1. Improved computational model (AQUIFAS) for activated sludge, integrated fixed-film activated sludge, and moving-bed biofilm reactor systems, part III: analysis and verification.

    Science.gov (United States)

    Sen, Dipankar; Randall, Clifford W

    2008-07-01

    Research was undertaken to analyze and verify a model that can be applied to activated sludge, integrated fixed-film activated sludge (IFAS), and moving-bed biofilm reactor (MBBR) systems. The model embeds a biofilm model into a multicell activated sludge model. The advantage of such a model is that it eliminates the need to run separate computations for a plant being retrofitted from activated sludge to IFAS or MBBR. The biofilm flux rates for organics, nutrients, and biomass can be computed by two methods-a semi-empirical model of the biofilm that is relatively simpler, or a diffusional model of the biofilm that is computationally intensive. Biofilm support media can be incorporated to the anoxic and aerobic cells, but not the anaerobic cells. The model can be run for steady-state and dynamic simulations. The model was able to predict the changes in nitrification and denitrification at both pilot- and full-scale facilities. The semi-empirical and diffusional models of the biofilm were both used to evaluate the biofilm flux rates for media at different locations. The biofilm diffusional model was used to compute the biofilm thickness and growth, substrate concentrations, volatile suspended solids (VSS) concentration, and fraction of nitrifiers in each layer inside the biofilm. Following calibration, both models provided similar effluent results for reactor mixed liquor VSS and mixed liquor suspended solids and for the effluent organics, nitrogen forms, and phosphorus concentrations. While the semi-empirical model was quicker to run, the diffusional model provided additional information on biofilm thickness, quantity of growth in the biofilm, and substrate profiles inside the biofilm. PMID:18710147

  2. Continuous Drip Flow System to Develop Biofilm of E. faecalis under Anaerobic Conditions

    Directory of Open Access Journals (Sweden)

    Ana Maria Gonzalez

    2014-01-01

    Full Text Available Purpose. To evaluate a structurally mature E. faecalis biofilm developed under anaerobic/dynamic conditions in an in vitro system. Methods. An experimental device was developed using a continuous drip flow system designed to develop biofilm under anaerobic conditions. The inoculum was replaced every 24 hours with a fresh growth medium for up to 10 days to feed the system. Gram staining was done every 24 hours to control the microorganism purity. Biofilms developed under the system were evaluated under the scanning electron microscope (SEM. Results. SEM micrographs demonstrated mushroom-shaped structures, corresponding to a mature E. faecalis biofilm. In the mature biofilm bacterial cells are totally encased in a polymeric extracellular matrix. Conclusions. The proposed in vitro system model provides an additional useful tool to study the biofilm concept in endodontic microbiology, allowing for a better understanding of persistent root canal infections.

  3. Extracellular DNA formation during biofilm development by freshwater bacteria

    DEFF Research Database (Denmark)

    Tang, Lone; Schramm, Andreas; Revsbech, Niels Peter;

    2011-01-01

    a transient peak at 6 hours, and in Rheinheimera the concentration peaked at 12 hours and remained high. Interestingly, the Rheinheimera biofilm dispersed immediately after the eDNA concentration peaked. The antimicrobial effect of eDNA was tested in growth experiments, and Rheinheimera was strongly......Extracellular DNA (eDNA) has been shown to be important for biofilm formation, both in the initial step of biofilm formation (attachment), and for securing the structural stability of the mature biofilm. It is unclear whether a general consensus exists for when in biofilm formation the presence of...... eDNA is most important. In this study, we investigated the significance of eDNA during biofilm formation in four freshwater isolates. The aim was to relate the quantity and timing of eDNA production to the isolates’ ability to form biofilms. eDNA and biofilm biomass was quantified over time during...

  4. Dual susbstrate limitations in upflow packed-bed biofilm reactors - a theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Beg, A.A. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Chemical Engineering; Hassan, M.M. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Chemical Engineering; Chaudhry, M.A.S. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Chemical Engineering

    1997-01-01

    The performance of an upflow packed-bed biofilm reactor has been analyzed under dual substrate limitation conditions. The numerical solution of the proposed equations defining the system has been obtained for a wide range of operating conditions for a case of practical significance involving glucose and oxygen as dual substrates. The results show that the inlet glucose concentration defines the limiting substrate at a position near the inlet of the reactor. For inlet glucose concentrations up to 300 mg/l, glucose acts as the limiting substrate. However, for inlet concentrations of 400 mg/l of glucose or higher, oxygen assumes the role of the limiting substrate at that position. For all other positions in the reactor, glucose acts as the limiting substrate, irrespective of its inlet concentration. Extensive computations were performed in order to define regions where glucose, oxygen or both are limiting. The predicted results have been found to be in agreement with the theoretical criteria, proposed in the literature, of determining the limiting substrate. (orig.)

  5. Biodegradation of pharmaceuticals from hospital wastewater in staged Moving Bed Biofilm Reactors (MBBR)

    DEFF Research Database (Denmark)

    Escola, Monica; Kumar Chhetri, Ravi; Ooi, Gordon;

    2015-01-01

    Hospital wastewater may represent an important source of pharmaceuticals into wastewater treatment plants, which are usually inefficient for complete pharmaceuticals removal. Consequently, on-site treatment of hospital wastewater has been suggested. MBBRs (Moving Bed Biofilm Reactors) rely on...... pharmaceuticals from hospital wastewater. A pilot MBBR line consisting of three tanks in series containing AnoxKaldnes™ K5 carriers was installed to treat a fraction of the wastewater from the oncology department of Aarhus University Hospital. Two sampling campaigns were conducted to study the removal of...... wastewater treatment. In both experiments, the first tank was observed to conduct the main part of the pharmaceuticals removal, matching the general parameters data. Overall, the MBBR was shown to treat hospital wastewater efficiently. However, for removal of recalcitrant pharmaceuticals, a polishing...

  6. Chloro-Organics in Papermill Effluent: Identification and Removal by Sequencing Batch Biofilm Reactor

    Science.gov (United States)

    Abd. Rahman, Rakmi; Zahrim, A. Y.; Abu Bakar, Azizah

    Effluents from paper mills are among major sources of aquatic pollution and may be toxic since they contain chlorinated phenolic compounds which are measured as adsorbable organic halides (AOX). In this work, removal of chlorophenol was investigated using a Sequencing Batch Biofilm Reactor (SBBR) with Granular Activated Carbon (GAC) as a growth media. Wastewater for this study was obtained from treated effluent outlet of a papermill in Selangor. Treatment of the papermill secondary effluent shows that SBBR process, with a combination of adsorption and biodegradation, gave a good removal of pentachlorophenol (PCP), on average, about 70%. The growth kinetic parameters obtained were: YH = 0.6504 mg biomass/mg PCP, dH = 6.50x10-5 h-1, μh = 0.00315 h-1 and Ks = 5.82 mg PCP L-1. These show that the SBBR system is suitable to be operated at long SRTs.

  7. Study of moving bed biofilm reactor in diethyl phthalate and diallyl phthalate removal from synthetic wastewater.

    Science.gov (United States)

    Ahmadi, Ehsan; Gholami, Mitra; Farzadkia, Mahdi; Nabizadeh, Ramin; Azari, Ali

    2015-05-01

    Phthalic acid esters have received significant attention over the last few years since they are considered as priority pollutants. In this study, effects of different operation conditions including hydraulic retention time, phthalates loading rates and aeration rate on process performance of moving bed biofilm reactor (MBBR) for removing diethyl phthalate (DEP) and diallyl phthalate (DAP) from synthetic wastewater was evaluated. In optimum conditions, 94.96% and 93.85% removal efficiency were achieved for DEP and DAP, respectively. Moreover, MBBR achieved to remove more than 92% of COD for both phthalates. The results showed that DEP had a higher biodegradation rate compared to DAP, according to the selected parameters such as half saturation constant, overall reaction rate and maximum specific growth rate. The Grau second order model found as the best model for predicting MBBR performance due to its high correlation coefficients and more conformity of its kinetic coefficients to the results. PMID:25727760

  8. The Pseudomonas Quinolone Signal Inhibits Biofilm Development of Streptococcus mutans

    OpenAIRE

    Inaba, Tomohiro; Oura, Hiromu; Morinaga, Kana; Toyofuku, Masanori; Nomura, Nobuhiko

    2015-01-01

    Bacteria often thrive in natural environments through a sessile mode of growth, known as the biofilm. Biofilms are well-structured communities and their formation is tightly regulated. However, the mechanisms by which interspecies interactions alter the formation of biofilms have not yet been elucidated in detail. We herein demonstrated that a quorum-sensing signal in Pseudomonas aeruginosa (the Pseudomonas quinolone signal; PQS) inhibited biofilm formation by Streptococcus mutans. Although t...

  9. Model-based evaluation of the role of Anammox on nitric oxide and nitrous oxide productions in membrane aerated biofilm reactor

    DEFF Research Database (Denmark)

    Ni, Bing-Jie; Smets, Barth F.; Yuan, Zhiguo;

    2013-01-01

    A multispecies one-dimensional biofilm model considering nitric oxide (NO) and nitrous oxide (N2O) productions for membrane aerated biofilm reactor (MABR) that remove nitrogen autotrophically through aerobic ammonia oxidation followed by Anammox is used to study the role of Anammox activity on th...

  10. Development and evaluation of different normalization strategies for gene expression studies in Candida albicans biofilms by real-time PCR

    Directory of Open Access Journals (Sweden)

    Deforce Dieter

    2006-08-01

    Full Text Available Abstract Background Candida albicans biofilms are commonly found on indwelling medical devices. However, the molecular basis of biofilm formation and development is not completely understood. Expression analysis of genes potentially involved in these processes, such as the ALS (Agglutinine Like Sequence gene family can be performed using quantitative PCR (qPCR. In the present study, we investigated the expression stability of eight housekeeping genes potentially useful as reference genes to study gene expression in Candida albicans (C. albicans biofilms, using the geNorm Visual Basic Application (VBA for Microsoft Excel. To validate our normalization strategies we determined differences in ALS1 and ALS3 expression levels between C. albicans biofilm cells and their planktonic counterparts. Results The eight genes tested in this study are ranked according to their expression stability (from most stable to least stable as follows: ACT1 (β-actin/PMA1 (adenosine triphosphatase, RIP (ubiquinol cytochrome-c reductase complex component, RPP2B (cytosolic ribosomal acidic protein P2B, LSC2 (succinyl-CoA synthetase β-subunit fragment, IMH3 (inosine-5'-monophosphate dehydrogenase fragment, CPA1 (carbamoyl-phosphate synthethase small subunit and GAPDH (glyceraldehyde-3-phosphate dehydrogenase. Our data indicate that five genes are necessary for accurate and reliable normalization of gene expression data in C. albicans biofilms. Using different normalization strategies, we found a significant upregulation of the ALS1 gene and downregulation of the ALS3 gene in C. albicans biofilms grown on silicone disks in a continous flow system, the CDC reactor (Centre for Disease Control, for 24 hours. Conclusion In conclusion, we recommend the use of the geometric mean of the relative expression values from the five housekeeping genes (ACT1, PMA1, RIP, RPP2B and LSC2 for normalization, when analysing differences in gene expression levels between C. albicans biofilm

  11. Current Trends in Development of Liposomes for Targeting Bacterial Biofilms

    OpenAIRE

    Zora Rukavina; Željka Vanić

    2016-01-01

    Biofilm targeting represents a great challenge for effective antimicrobial therapy. Increased biofilm resistance, even with the elevated concentrations of very potent antimicrobial agents, often leads to failed therapeutic outcome. Application of biocompatible nanomicrobials, particularly liposomally-associated nanomicrobials, presents a promising approach for improved drug delivery to bacterial cells and biofilms. Versatile manipulations of liposomal physicochemical properties, such as the b...

  12. Resilience and recovery: the effect of triclosan exposure timing during development, on the structure and function of river biofilm communities.

    Science.gov (United States)

    Lawrence, J R; Topp, E; Waiser, M J; Tumber, V; Roy, J; Swerhone, G D W; Leavitt, P; Paule, A; Korber, D R

    2015-04-01

    Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 μg l(-1) TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: (i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and (ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (pbacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism. Direct counts of protozoans indicated that TCS was suppressive, whereas micrometazoan populations were, in some instances, stimulated. These results indicate that even a relatively brief exposure of a river biofilm community to relatively low levels of TCS alters both the trajectory and final community structure. Although some evidence of recovery was observed, removal of TCS did not result in a return to the unexposed reference condition. PMID:25731684

  13. Involvement of bacterial migration in the development of complex multicellular structures in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Klausen, Mikkel; Aaes-Jorgensen, A.; Molin, Søren; Tolker-Nielsen, Tim

    2003-01-01

    Detailed knowledge of the developmental process from single cells scattered on a surface to complex multicellular biofilm structures is essential in order to create strategies to control biofilm development. In order to study bacterial migration patterns during Pseudomonas aeruginosa biofilm...... development, we have performed an investigation with time-lapse confocal laser scanning microscopy of biofilms formed by various combinations of colour-coded P. aeruginosa wild type and motility mutants. We show that mushroom-shaped multicellular structures in P. aeruginosa biofilms can form in a sequential...... process involving a non-motile bacterial subpopulation and a migrating bacterial subpopulation. The non-motile bacteria form the mushroom stalks by growth in certain foci of the biofilm. The migrating bacteria form the mushroom caps by climbing the stalks and aggregating on the tops in a process which is...

  14. Chemoinformatics-assisted development of new anti-biofilm compounds

    DEFF Research Database (Denmark)

    Dürig, Anna; Kouskoumvekaki, Irene; Vejborg, Rebecca Munk;

    2010-01-01

    Bacterial biofilms are associated with a large number of infections. Biofilm-dwelling bacteria are particularly resistant to antibiotics, making it hard to eradicate biofilm-associated infections. Here, we use a novel cross-disciplinary approach combining microbiology and chemoinformatics to...... identify new and efficient anti-biofilm drugs. We found that ellagic acid (present in green tea) significantly inhibited biofilm formation of Streptococcus dysgalactiae. Based on ellagic acid, we performed in silico screening of the Chinese Natural Product Database to predict a 2nd-generation list of...

  15. Conservation of acquired morphology and community structure in aged biofilms after facing environmental stress.

    Science.gov (United States)

    Saur, T; Escudié, R; Santa-Catalina, G; Bernet, N; Milferstedt, K

    2016-01-01

    The influence of growth history on biofilm morphology and microbial community structure is poorly studied despite its important role for biofilm development. Here, biofilms were exposed to a change in hydrodynamic conditions at different growth stages and we observed how biofilm age affected the change in morphology and bacterial community structure. Biofilms were developed in two bubble column reactors, one operated under constant shear stress and one under variable shear stress. Biofilms were transferred from one reactor to the other at different stages in their development by withdrawing and inserting the support medium from one reactor to the other. The developments of morphology and microbial community structure were followed by image analysis and molecular tools. When transferred early in biofilm development, biofilms adapted to the new hydrodynamic conditions and adopted features of the biofilm already developed in the receiving reactor. Biofilms transferred at a late state of biofilm development continued their initial trajectories of morphology and community development even in a new environment. These biofilms did not immediately adapt to their new environment and kept features acquired during their early growth phase, a property we called memory effect. PMID:26492343

  16. ANALYSIS OF CHROMATE UPTAKE IN BACTERIAL BIOFILMS DEVELOPED ON ABIOTIC SUPPORT

    OpenAIRE

    Aditi Bhattacharya

    2014-01-01

    Microorganisms also practice community living and form biofilms developed on preferred surfaces. The sessile and planktonic organisms show differences in hydrophobicity as determined by the BATH index. The saccharides of the EPS produced was determined using the phenol-sulphuric acid method and Rhamnolipids using the Orcinol method. Dye released from stained biofilms is also indicative of the density of the biofilm. Motility was reduced on formation of cell aggregates in m...

  17. Assessing biofilm development in drinking water distribution systems by Machine Learning methods

    OpenAIRE

    Ramos Martínez, Eva

    2016-01-01

    [EN] One of the main challenges of drinking water utilities is to ensure high quality supply, in particular, in chemical and microbiological terms. However, biofilms invariably develop in all drinking water distribution systems (DWDSs), despite the presence of residual disinfectant. As a result, water utilities are not able to ensure total bacteriological control. Currently biofilms represent a real paradigm in water quality management for all DWDSs. Biofilms are complex communities of microo...

  18. Development and Validation of an In Vivo Candida albicans Biofilm Denture Model▿

    OpenAIRE

    Nett, Jeniel E.; Marchillo, Karen; Spiegel, Carol A.; Andes, David R.

    2010-01-01

    The most common form of oral candidiasis, denture-associated stomatitis, involves biofilm growth on an oral prosthetic surface. Cells in this unique environment are equipped to withstand host defenses and survive antifungal therapy. Studies of the biofilm process on dentures have primarily been limited to in vitro models. We developed a rodent acrylic denture model and characterized the Candida albicans and mixed oral bacterial flora biofilm formation, architecture, and drug resistance in viv...

  19. CARBOHYDRATE ENHANCED BIOFILM GROWTH IN ANAEROBIC FLUIDIZED BED REACTOR TREATING SYNTHETIC WASTEWATER = EFEITO DA ADIÇÃO DE CARBOIDRATOS NO CRESCIMENTO DE BIOFILME EM REATOR ANAERÓBIO DE LEITO FLUIDIFICADO

    Directory of Open Access Journals (Sweden)

    Renata Medici Frayne Cuba

    2010-01-01

    Full Text Available Biofilm dynamics in anaerobic fluidized bed reactor was studied since start-up during a 600-day operation time. Specific methanogenic activity tests revealed gas production by the anaerobic biomass since 30th operation day. Scanning Electron Microscopy (SEM micrographs permitted to verify three bacterial development stages depending on the organic loading imposed to the system. Increasing of organic loading caused methanogenic specific activity depletion due to diffusion resistance through anaerobic biofilm. With maximum organic loading of 28.5 kg COD.m-3.day-1, almost 10% of the volatile solids fixed in inert particle surface were detected as polymeric extracellular material. = A dinâmica do biofilme em um reator anaeróbio de leito fluidificado foi estudada durante 600 dias desde a partida do sistema. Testes de atividade metanogênica específica revelaram produção de gás pela biomassa anaeróbia desde o trigésimo dia de operação. Microfotografias obtidas com microscópio eletrônico de varredura (MEV permitiram verificar três estágios no desenvolvimento das bactérias, dependendo da carga orgânica imposta ao sistema. O aumento de carga orgânica causou a diminuição da atividade metanogênica específica devido à resistência à difusividade ao longo do biofilme anaeróbio. Com carga orgânica máxima de 28,5 kg COD. m-3.dia-1, aproximadamente 10% dos sólidos voláteis aderidos na superfície das partículas inertes foi identificado como material polimérico extracelular.

  20. Development and optimization of biofilm based algal cultivation

    Science.gov (United States)

    Gross, Martin Anthony

    This dissertation describes research done on biofilm based algal cultivation systems. The system that was developed in this work is the revolving algal biofilm cultivation system (RAB). A raceway-retrofit, and a trough-based pilot-scale RAB system were developed and investigated. Each of the systems significantly outperformed a control raceway pond in side-by-side tests. Furthermore the RAB system was found to require significantly less water than the raceway pond based cultivation system. Lastly a TEA/LCA analysis was conducted to evaluate the economic and life cycle of the RAB cultivation system in comparison to raceway pond. It was found that the RAB system was able to grow algae at a lower cost and was shown to be profitable at a smaller scale than the raceway pond style of algal cultivation. Additionally the RAB system was projected to have lower GHG emissions, and better energy and water use efficiencies in comparison to a raceway pond system. Furthermore, fundamental research was conducted to identify the optimal material for algae to attach on. A total of 28 materials with a smooth surface were tested for initial cell colonization and it was found that the tetradecane contact angle of the materials had a good correlation with cell attachment. The effects of surface texture were evaluated using mesh materials (nylon, polypropylene, high density polyethylene, polyester, aluminum, and stainless steel) with openings ranging from 0.05--6.40 mm. It was found that both surface texture and material composition influence algal attachment.

  1. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor.

    Science.gov (United States)

    Azizi, Shohreh; Kamika, Ilunga; Tekere, Memory

    2016-01-01

    For the effective application of a modified packed bed biofilm reactor (PBBR) in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni) was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT) of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l) concentrations of combined heavy metals at an optimum HRT condition (2 hours), while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD) of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l), is capable of removing the industrial contamination in wastewater. PMID:27186636

  2. Evaluation of Heavy Metal Removal from Wastewater in a Modified Packed Bed Biofilm Reactor.

    Directory of Open Access Journals (Sweden)

    Shohreh Azizi

    Full Text Available For the effective application of a modified packed bed biofilm reactor (PBBR in wastewater industrial practice, it is essential to distinguish the tolerance of the system for heavy metals removal. The industrial contamination of wastewater from various sources (e.g. Zn, Cu, Cd and Ni was studied to assess the impacts on a PBBR. This biological system was examined by evaluating the tolerance of different strengths of composite heavy metals at the optimum hydraulic retention time (HRT of 2 hours. The heavy metal content of the wastewater outlet stream was then compared to the source material. Different biomass concentrations in the reactor were assessed. The results show that the system can efficiently treat 20 (mg/l concentrations of combined heavy metals at an optimum HRT condition (2 hours, while above this strength there should be a substantially negative impact on treatment efficiency. Average organic reduction, in terms of the chemical oxygen demand (COD of the system, is reduced above the tolerance limits for heavy metals as mentioned above. The PBBR biological system, in the presence of high surface area carrier media and a high microbial population to the tune of 10 000 (mg/l, is capable of removing the industrial contamination in wastewater.

  3. Wound biofilms: lessons learned from oral biofilms

    OpenAIRE

    Mancl, Kimberly A.; Kirsner, Robert S.; Ajdic, Dragana

    2013-01-01

    Biofilms play an important role in the development and pathogenesis of many chronic infections. Oral biofilms, more commonly known as dental plaque,are a primary cause of oral diseases including caries, gingivitis and periodontitis. Oral biofilms are commonly studied as model biofilm systems as they are easily accessible, thus biofilm research in oral diseases is advanced with details of biofilm formation and bacterial interactions being well-elucidated. In contrast, wound research has relati...

  4. Biofilm Fixed Film Systems

    OpenAIRE

    Dipesh Das; Yung-Tse Hung; Charles Moretti; Hasibul Hasan; Harvey Gullicks

    2011-01-01

    The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, r...

  5. Resilience and recovery: The effect of triclosan exposure timing during development, on the structure and function of river biofilm communities

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, J.R., E-mail: john.lawrence@ec.gc.ca [Environment Canada, 11 Innovation Blvd., Saskatoon, SK S7N 3H5 (Canada); Topp, E. [Agriculture and Agri-Food Canada, London, ON (Canada); Waiser, M.J.; Tumber, V.; Roy, J.; Swerhone, G.D.W. [Environment Canada, 11 Innovation Blvd., Saskatoon, SK S7N 3H5 (Canada); Leavitt, P. [University of Regina, Regina, SK (Canada); Paule, A. [Global Institute for Water Security, University of Saskatchewan, Saskatoon, SK (Canada); Korber, D.R. [Food and Bioproduct Sciences, University of Saskatchewan, Saskatoon, SK (Canada)

    2015-04-15

    Highlights: • Triclosan negatively affected structure and metabolism of biofilms under all exposure conditions. • Biofilm age, timing and exposure regime alter the effects of triclosan. • Regardless of exposure regime algae and cyanobacteria were the most affected. • Although recovery was evident no community regained the reference condition. • Initial recruitment may be significant in determining community recovery. - Abstract: Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 μg l{sup −1} TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: (i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and (ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (p < 0.05) reductions in cyanobacterial biomass. No significant effects were observed on bacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism

  6. Resilience and recovery: The effect of triclosan exposure timing during development, on the structure and function of river biofilm communities

    International Nuclear Information System (INIS)

    Highlights: • Triclosan negatively affected structure and metabolism of biofilms under all exposure conditions. • Biofilm age, timing and exposure regime alter the effects of triclosan. • Regardless of exposure regime algae and cyanobacteria were the most affected. • Although recovery was evident no community regained the reference condition. • Initial recruitment may be significant in determining community recovery. - Abstract: Triclosan (TCS) is a ubiquitous antibacterial agent found in soaps, scrubs, and consumer products. There is limited information on hazardous effects of TCS in the environment. Here, rotating annular reactors were used to cultivate river biofilm communities exposed to 1.8 μg l−1 TCS with the timing and duration of exposure and recovery during development varied. Two major treatment regimens were employed: (i) biofilm development for 2, 4 or 6 weeks prior to TCS exposure and (ii) exposure of biofilms to TCS for 2, 4 or 6 weeks followed by recovery. Biofilms not exposed to TCS were used as a reference condition. Communities cultivated without and then exposed to TCS all exhibited reductions in algal biomass and significant (p < 0.05) reductions in cyanobacterial biomass. No significant effects were observed on bacterial biomass. CLSM imaging of biofilms at 8 weeks revealed unique endpoints in terms of community architecture. Community composition was altered by any exposure to TCS, as indicated by significant shifts in denaturing gradient gel electrophoresis fingerprints and exopolymer composition relative to the reference. Bacterial, algal and cyanobacterial components initially exposed to TCS were significantly different from those TCS-free at time zero. Pigment analyses suggested that significant changes in composition of algal and cyanobacterial populations occurred with TCS exposure. Bacterial thymidine incorporation rates were reduced by TCS exposure and carbon utilization spectra shifted in terms substrate metabolism

  7. Simultaneous removal of nitrogen and phosphorus from swine wastewater in a sequencing batch biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    Reti Hai; Yiqun He; Xiaohui Wang; Yuan Li

    2015-01-01

    In this study, the performance of a sequencing batch biofilm reactor (SBBR) for removal of nitrogen and phosphorus from swine wastewater was evaluated. The replacement rate of wastewater was set at 12.5%throughout the exper-iment. The anaerobic and aerobic times were 3 h and 7 h, respectively, and the dissolved oxygen concentration of the aerobic phase was about 3.95 mg·L−1. The SBBR process demonstrated good performance in treating swine wastewater. The percentage removal of total chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) was 98.2%, 95.7%, 95.6%, and 96.2%at effluent concentrations of COD 85.6 mg·L−1, NH4+-N 35.22 mg·L−1, TN 44.64 mg·L−1, and TP 1.13 mg·L−1, respectively. Simultaneous nitrification and denitrification phenomenon was observed. Further improvement in removal efficiency of NH4+-N and TN occurred at COD/TN ratio of 11:1, with effluent concentrations at NH4+-N 18.5 mg·L−1 and TN 34 mg·L−1, while no such improvement in COD and TP removal was found. Microbial electron microscopy analysis showed that the fil er surface was covered with a thick biofilm, forming an anaerobic–aerobic microenvironment and facilitating the removal of nitrogen, phosphorus and organic matters. A long-term experiment (15 weeks) showed that stable removal efficiency for N and P could be achieved in the SBBR system.

  8. Nitrogen removal by granular nitritation-anammox in an upflow membrane-aerated biofilm reactor.

    Science.gov (United States)

    Li, Xiaojin; Sun, Shan; Badgley, Brian D; Sung, Shihwu; Zhang, Husen; He, Zhen

    2016-05-01

    The nitritation-anammox process has been a promising nitrogen removal technology towards sustainable wastewater treatment, but its application in treating domestic wastewater with relatively low ammonium concentrations (mainstream) remains a great challenge. In this study, an innovative lab-scale upflow membrane-aerated biofilm reactor (UMABR) was employed to treat a synthetic wastewater containing 70 mg N L(-1) ammonium. With a DO level at 0.6 ± 0.1 mg O2 L(-1) and HRT of 32 h, the effluent ammonium concentration was 4.8 ± 2.0 mg N L(-1). Increasing the nitrogen loading rate from 52.4 to 104.8 g N m(-3) d(-1) with stepwise decreasing HRT from 32 to 16 h resulted in an average TN removal efficiency of 81% without nitrite accumulation. The average observed NO3(-)-N (residue)/NH4(+)-N (consumed) ratio of 8% was below the "theoretical ratio" of 13% and further reduction of nitrate residue needs to be addressed. Fluorescence in situ hybridization (FISH) and high-throughput sequencing analyses showed the coexistence of anammox bacteria and ammonium-oxidizing bacteria (AOB) in both biofilm and granular samples. Anammox bacteria accounted for up to 63.3% of the microbial community of the granules, with Candidatus Jettenia being the distinctly dominant anammox genus. In contrast, the biofilm contained abundant Nitrosomonadaceae (AOB, 33.1%). In addition, the brown-yellow granules exhibited a more balanced community structure with anammox bacteria and AOB accounting for 33.7% and 18.2%, respectively, which may contribute to the long-term operation of single-stage nitritation-anammox process. These results demonstrate that the nitritation-anammox UMABR could potentially be used for nitrogen removal from mainstream in some specific regions with relatively warm temperature. PMID:26921710

  9. Performance analysis of a pilot-scale membrane aerated biofilm reactor for the treatment of landfill leachate

    OpenAIRE

    Syron, Eoin; Semmens, Michael J.; CASEY, Eoin

    2015-01-01

    A 60 L membrane aerated biofilm reactor (MABR) was successfully employed to treat landfill leachate, which contained very high concentrations of refractory chemical oxygen demand (COD) and ammonium. Air or pure oxygen was supplied to the bioreactor through polydimethyl siloxane hollow fibre membranes. Over a year of operation with an average hydraulic retention time of about 5 days, and influent ammonium concentrations ranging from 500 to 2500 mg/L, the MABR achieved 80–99% nitrification. Sim...

  10. Treatment of High-Strength Nitrogen Wasetewater With a Hollow-Fiber Membrane-Aerated Biofilm Reactor: A Comprehensive Evaluation

    OpenAIRE

    Gilmore, Kevin R

    2008-01-01

    Protecting the quality and quantity of our water resources requires advanced treatment technologies capable of removing nutrients from wastewater. This research work investigated the capability of one such technology, a hollow-fiber membrane-aerated biofilm reactor (HFMBR), to achieve completely autotrophic nitrogen removal from a wastewater with high nitrogen content. Because the extent of oxygenation is a key parameter for controlling the metabolic processes that occur in a wastewate...

  11. Combination of upflow anaerobic sludge blanket (UASB) reactor and partial nitritation/anammox moving bed biofilm reactor (MBBR) for municipal wastewater treatment.

    Science.gov (United States)

    Malovanyy, Andriy; Yang, Jingjing; Trela, Jozef; Plaza, Elzbieta

    2015-03-01

    In this study the combination of an upflow anaerobic sludge blanket (UASB) reactor and a deammonification moving bed biofilm reactor (MBBR) for mainstream wastewater treatment was tested. The competition between aerobic ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) was studied during a 5months period of transition from reject water to mainstream wastewater followed by a 16months period of mainstream wastewater treatment. The decrease of influent ammonium concentration led to a wash-out of suspended biomass which had a major contribution to nitrite production. Influence of a dissolved oxygen concentration and a transient anoxia mechanism of NOB suppression were studied. It was shown that anoxic phase duration has no effect on NOB metabolism recovery and oxygen diffusion rather than affinities of AOB and NOB to oxygen determine the rate of nitrogen conversion in a biofilm system. Anammox activity remained on the level comparable to reject water treatment systems. PMID:25600011

  12. Developed Fungal-Bacterial Biofilms as A Novel Tool for Bioremoval of Hexavelant Chromium from Wastewater

    DEFF Research Database (Denmark)

    Herath, Lasantha; Rajapaksha, R. M. A. U.; Vithanage, M.;

    2014-01-01

    Remediation measures for hexavalent Chromium [Cr(VI)] are required for a safe environment. As a recent development in microbiology, bacterial biofilms are being studied as effective bioremediation agents. When bacteria are in fungal surface-attached biofilm mode, they are called fungal...

  13. Multiple roles of biosurfactants in structural biofilm development by Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Pamp, Sünje Johanna; Tolker-Nielsen, Tim

    2007-01-01

    . aeruginosa rhl4 mutants were defective in migration-dependent development of mushroom-shaped multicellular structures in the later phase of biofilm formation. Experiments involving three-color-coded mixed-strain P. aeruginosa biofilms demonstrated that the wild-type and rhl4 and pil4 mutant strains formed...

  14. Quorum sensing-controlled biofilm development in Serratia liquefaciens MG1

    DEFF Research Database (Denmark)

    Labbate, M.; Queek, S.Y.; Koh, K.S.; Rice, S.A.; Givskov, Michael Christian; Kjelleberg, S.

    2004-01-01

    aggregates and differentiated cell chains. Signal-based complementation of this mutant resulted in a biofilm with the wild-type architecture. Two quorum-sensing-regulated genes (bsmA and bsmB) involved in biofilm development were identified, and we propose that these genes are engaged in fine-tuning the...

  15. Model-Based Feasibility Assessment of Membrane Biofilm Reactor to Achieve Simultaneous Ammonium, Dissolved Methane, and Sulfide Removal from Anaerobic Digestion Liquor.

    Science.gov (United States)

    Chen, Xueming; Liu, Yiwen; Peng, Lai; Yuan, Zhiguo; Ni, Bing-Jie

    2016-01-01

    In this study, the membrane biofilm reactor (MBfR) is proposed to achieve simultaneous removal of ammonium, dissolved methane, and sulfide from main-stream and side-stream anaerobic digestion liquors. To avoid dissolved methane stripping, oxygen is introduced through gas-permeable membranes, which also from the substratum for the growth of a biofilm likely comprising ammonium oxidizing bacteria (AOB), anaerobic ammonium oxidation (Anammox) bacteria, denitrifying anaerobic methane oxidation (DAMO) microorganisms, aerobic methane oxidizing bacteria (MOB), and sulfur oxidizing bacteria (SOB). A mathematical model is developed and applied to assess the feasibility of such a system and the associated microbial community structure under different operational conditions. The simulation studies demonstrate the feasibility of achieving high-level (>97.0%), simultaneous removal of ammonium, dissolved methane, and sulfide in the MBfRs from both main-stream and side-stream anaerobic digestion liquors through adjusting the influent surface loading (or hydraulic retention time (HRT)) and the oxygen surface loading. The optimal HRT was found to be inversely proportional to the corresponding oxygen surface loading. Under the optimal operational conditions, AOB, DAMO bacteria, MOB, and SOB dominate the biofilm of the main-stream MBfR, while AOB, Anammox bacteria, DAMO bacteria, and SOB coexist in the side-stream MBfR to remove ammonium, dissolved methane, and sulfide simultaneously. PMID:27112502

  16. Model-Based Feasibility Assessment of Membrane Biofilm Reactor to Achieve Simultaneous Ammonium, Dissolved Methane, and Sulfide Removal from Anaerobic Digestion Liquor

    Science.gov (United States)

    Chen, Xueming; Liu, Yiwen; Peng, Lai; Yuan, Zhiguo; Ni, Bing-Jie

    2016-04-01

    In this study, the membrane biofilm reactor (MBfR) is proposed to achieve simultaneous removal of ammonium, dissolved methane, and sulfide from main-stream and side-stream anaerobic digestion liquors. To avoid dissolved methane stripping, oxygen is introduced through gas-permeable membranes, which also from the substratum for the growth of a biofilm likely comprising ammonium oxidizing bacteria (AOB), anaerobic ammonium oxidation (Anammox) bacteria, denitrifying anaerobic methane oxidation (DAMO) microorganisms, aerobic methane oxidizing bacteria (MOB), and sulfur oxidizing bacteria (SOB). A mathematical model is developed and applied to assess the feasibility of such a system and the associated microbial community structure under different operational conditions. The simulation studies demonstrate the feasibility of achieving high-level (>97.0%), simultaneous removal of ammonium, dissolved methane, and sulfide in the MBfRs from both main-stream and side-stream anaerobic digestion liquors through adjusting the influent surface loading (or hydraulic retention time (HRT)) and the oxygen surface loading. The optimal HRT was found to be inversely proportional to the corresponding oxygen surface loading. Under the optimal operational conditions, AOB, DAMO bacteria, MOB, and SOB dominate the biofilm of the main-stream MBfR, while AOB, Anammox bacteria, DAMO bacteria, and SOB coexist in the side-stream MBfR to remove ammonium, dissolved methane, and sulfide simultaneously.

  17. Model-Based Feasibility Assessment of Membrane Biofilm Reactor to Achieve Simultaneous Ammonium, Dissolved Methane, and Sulfide Removal from Anaerobic Digestion Liquor

    Science.gov (United States)

    Chen, Xueming; Liu, Yiwen; Peng, Lai; Yuan, Zhiguo; Ni, Bing-Jie

    2016-01-01

    In this study, the membrane biofilm reactor (MBfR) is proposed to achieve simultaneous removal of ammonium, dissolved methane, and sulfide from main-stream and side-stream anaerobic digestion liquors. To avoid dissolved methane stripping, oxygen is introduced through gas-permeable membranes, which also from the substratum for the growth of a biofilm likely comprising ammonium oxidizing bacteria (AOB), anaerobic ammonium oxidation (Anammox) bacteria, denitrifying anaerobic methane oxidation (DAMO) microorganisms, aerobic methane oxidizing bacteria (MOB), and sulfur oxidizing bacteria (SOB). A mathematical model is developed and applied to assess the feasibility of such a system and the associated microbial community structure under different operational conditions. The simulation studies demonstrate the feasibility of achieving high-level (>97.0%), simultaneous removal of ammonium, dissolved methane, and sulfide in the MBfRs from both main-stream and side-stream anaerobic digestion liquors through adjusting the influent surface loading (or hydraulic retention time (HRT)) and the oxygen surface loading. The optimal HRT was found to be inversely proportional to the corresponding oxygen surface loading. Under the optimal operational conditions, AOB, DAMO bacteria, MOB, and SOB dominate the biofilm of the main-stream MBfR, while AOB, Anammox bacteria, DAMO bacteria, and SOB coexist in the side-stream MBfR to remove ammonium, dissolved methane, and sulfide simultaneously. PMID:27112502

  18. Antibacterial Effect of Dental Adhesive Containing Dimethylaminododecyl Methacrylate on the Development of Streptococcus mutans Biofilm

    Directory of Open Access Journals (Sweden)

    Suping Wang

    2014-07-01

    Full Text Available Antibacterial bonding agents and composites containing dimethylaminododecyl methacrylate (DMADDM have been recently developed. The objectives of this study were to investigate the antibacterial effect of novel adhesives containing different mass fractions of DMADDM on Streptococcus mutans (S. mutans biofilm at different developmental stages. Different mass fractions of DMADDM were incorporated into adhesives and S. mutans biofilm at different developmetal stages were analyzed by MTT assays, lactic acid measurement, confocal laser scanning microscopy and scanning electron microscopy observations. Exopolysaccharides (EPS staining was used to analyze the inhibitory effect of DMADDM on the biofilm extracellular matrix. Dentin microtensile strengths were also measured. Cured adhesives containing DMADDM could greatly reduce metabolic activity and lactic acid production during the development of S. mutans biofilms (p < 0.05. In earlier stages of biofilm development, there were no significant differences of inhibitory effects between the 2.5% DMADDM and 5% DMADDM group. However, after 72 h, the anti-biofilm effects of adhesives containing 5% DMADDM were significantly stronger than any other group. Incorporation of DMADDM into adhesive did not adversely affect dentin bond strength. In conclusion, adhesives containing DMADDM inhibited the growth, lactic acid production and EPS metabolism of S. mutans biofilm at different stages, with no adverse effect on its dentin adhesive bond strength. The bonding agents have the potential to control dental biofilms and combat tooth decay, and DMADDM is promising for use in a wide range of dental adhesive systems and restoratives.

  19. Media surface properties and the development of nitrifying biofilms in mixed cultures for wastewater treatment.

    OpenAIRE

    Stephenson, Tom; Reid, E.; Avery, L. M.; Jefferson, Bruce

    2013-01-01

    Plastic was tested to select biofilm support media that would enhance nitrification in the presence of heterotrophs. Eight different types (acrylonitrile butadiene styrene, nylon, polycarbonate, polyethylene, polypropylene, polytetraflouroethylene (PTFE), polyvinyl chloride and tufnol) were immersed in an aerobic fed-batch reactor receiving domestic settled wastewater. Nitrification rates did not correlate with biomass concentrations, nor surface roughness of the plastics as measured by atomi...

  20. A fungal biofilm reactor based on metal structured packing improves the quality of a Gla::GFP fusion protein produced by Aspergillus oryzae.

    Science.gov (United States)

    Zune, Q; Delepierre, A; Gofflot, S; Bauwens, J; Twizere, J C; Punt, P J; Francis, F; Toye, D; Bawin, T; Delvigne, F

    2015-08-01

    Fungal biofilm is known to promote the excretion of secondary metabolites in accordance with solid-state-related physiological mechanisms. This work is based on the comparative analysis of classical submerged fermentation with a fungal biofilm reactor for the production of a Gla::green fluorescent protein (GFP) fusion protein by Aspergillus oryzae. The biofilm reactor comprises a metal structured packing allowing the attachment of the fungal biomass. Since the production of the target protein is under the control of the promoter glaB, specifically induced in solid-state fermentation, the biofilm mode of culture is expected to enhance the global productivity. Although production of the target protein was enhanced by using the biofilm mode of culture, we also found that fusion protein production is also significant when the submerged mode of culture is used. This result is related to high shear stress leading to biomass autolysis and leakage of intracellular fusion protein into the extracellular medium. Moreover, 2-D gel electrophoresis highlights the preservation of fusion protein integrity produced in biofilm conditions. Two fungal biofilm reactor designs were then investigated further, i.e. with full immersion of the packing or with medium recirculation on the packing, and the scale-up potentialities were evaluated. In this context, it has been shown that full immersion of the metal packing in the liquid medium during cultivation allows for a uniform colonization of the packing by the fungal biomass and leads to a better quality of the fusion protein. PMID:25935344

  1. The Psl economy in early P. aeruginosa biofilm development

    Science.gov (United States)

    Zhao, Kun; Tseng, Boo Shan; Jin, Fan; Gibiansky, Max; Harrison, Joe; Parsek, Matthew; Wong, Gerard

    2012-02-01

    Psl from P. aeruginosa (PAO1) is a mannose- and galactose-rich exopolysaccharide (EPS). It has been shown that Psl plays an important role in bacterial surface adhesion. Here, we examine role of Psl in controlling motility and microcolony formation during early biofilm development, by translating video microscopy movies into searchable databases of bacterial trajectories. We use a massively-parallel cell tracking algorithm to extract the full motility history of every cell in a large community. We find that at early stages of growth, P. aeruginosa motility is guided by Psl and self-organize in a manner analogous to a capitalist economic system, resulting in a power law bacterial distribution where a small number of bacteria are extremely ``rich'' in communally produced Psl. By comparing overproducers and underproducers of Psl, we find that local Psl levels determine post-division cell fates: High local Psl levels drive the formation of sessile microcolonies that grow exponentially.

  2. SP-100 Reactor Subsystem Development

    Science.gov (United States)

    Demuth, Scott F.

    1994-07-01

    The SP-100 reactor subsystem consists of the pressure vessel, vessel internals, and fuel elements. Type A (standard) Nb-1Zr and rhenium materials development efforts related to fabrication of the vessel, vessel internals, and fuel cladding/liner have been completed. Type A and Type C (PWC-11) Nb-1Zr loop fabrication has been successfully demonstrated by prototypic testing with flowing lithium at 1350 K for 1500 hr. Development of UN fuel has been completed, and the performance validated by irradiation testing to the full life (7 yr. full power) burnup of 6 atom %. Neutronic and hydraulic core performance have been validated by engineering mockup critical experiments in the Zero Power Physics Reactor at Argonne National Laboratory, and detailed core hydraulic flow testing with water. Essentially all feasibility issues have been settled for the full life SP-100 reactor subsystem. Remaining SP-100 reactor subsystem development efforts are focused on further reducing mass by the use of Type C (PWC-11) Nb-1Zr rather than Type A, and demonstrating fuel life for beyond full life to perhaps 9 atom % burnup.

  3. Biofilm reactor based real-time analysis of biochemical oxygen demand.

    Science.gov (United States)

    Liu, Changyu; Jia, Jianbo; Dong, Shaojun

    2013-04-15

    We reported a biofilm reactor (BFR) based analytical system for real-time biochemical oxygen demand (BOD) monitoring. It does not need a blank solution and other chemical reagents to operate. The initial dissolved oxygen (DO) in sample solution was measured as blank, while DO in the BFR effluent was measured as response. The DO difference obtained before and after the sample solution flowed through the BFR was regarded as an indicator of real-time BOD. The analytical performance of this reagent-free BFR system was equal to the previous BFR system operated using phosphate buffer saline (PBS) and high purity deionized water in reproducibility, accuracy and long-term stability. Besides, this method embraces many notable advantages, such as no secondary pollution. Additionally, the sample solutions are free from temperature controlling and air-saturation before injection. Significantly, this is a real-time BOD analysis method. This method was successfully carried out in a simulated emergency, and the obtained results agreed well with conventional BOD₅. These advantages, coupled with simplicity in device, convenience in operation and minimal maintenance, make such a reagent-free BFR analytical system promising for practical BOD real-time warning. PMID:23228491

  4. Cometabolic degradation of lincomycin in a Sequencing Batch Biofilm Reactor (SBBR) and its microbial community.

    Science.gov (United States)

    Li, Yancheng; Zhou, Jian; Gong, Benzhou; Wang, Yingmu; He, Qiang

    2016-08-01

    Cometabolism technology was employed to degrade lincomycin wastewater in Sequencing Batch Biofilm Reactor (SBBR). In contrast with the control group, the average removal rate of lincomycin increased by 56.0% and Total Organic Carbon (TOC) increased by 52.5% in the cometabolic system with glucose as growth substrate. Under the same condition, Oxidation-Reduction Potential (ORP) was 85.1±7.3mV in cometabolic system and 198.2±8.4mV in the control group, indicating that glucose changed the bulk ORP and created an appropriate growing environment for function bacteria. Functional groups of lincomycin were effectively degraded in cometabolic system proved by FTIR and GC-MS. Meanwhile, results of DGGE and 16S rDNA showed great difference in dominant populations between cometabolic system and the control group. In cometabolic system, Roseovarius (3.35%), Thiothrix (2.74%), Halomonas (2.49%), Ignavibacterium (2.02%), and TM7_genus_incertae_sedis (1.93%) were verified as dominant populations at genus level. Cometabolism may be synergistically caused by different functional dominant bacteria. PMID:27183234

  5. Mechanism studies on nitrogen removal when treating ammonium-rich leachate by sequencing batch biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    XU Zhengyong; YANG Zhaohui; ZENG Guangming; XIAO Yong; DENG Jiuhua

    2007-01-01

    The nitrogen removal mechanism was studied and analyzed when treating the ammonium-rich landfill leachate by a set of sequencing batch biofilm reactors(SBBRs),which was designed independently.At the liquid temperature of(32±0.4)℃,and after a 58-days domestication period and a 33-days stabilization period.the efficiency of ammonium removal in the SBBR went up to 95%.Highly frequent intermittent aeration suppressed the activity of nitratebacteria.and also eliminated the influence on the activity of anaerobic ammonium oxidation(ANAMMOX)bacteria and nitritebacteria.This influence was caused by the accumulation of nitrous acid and the undulation of pH.During the aeration stage,the concentration of dissolved oxygen was controlled at 1.2-1.4 mg/L.The nitritebacteria became dominant and nitrite accumulated gradually.During the anoxic stage,along with the concentration debasement of the dissolved oxygen,ANAMMOX bacteria became dominant;then,the nitrite that was accumulated in the aeration stage was wiped off with ammonium simultaneously.

  6. Study on treatment of coking wastewater by biofilm reactors combined with zero-valent iron process

    International Nuclear Information System (INIS)

    Experiments were conducted to investigate the behavior of the integrated system with biofilm reactors and zero-valent iron (ZVI) process for coking wastewater treatment. Particular attention was paid to the performance of the integrated system for removal of organic and inorganic nitrogen compounds. Maximal removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and total inorganic nitrogen (TIN) were up to 96.1, 99.2 and 92.3%, respectively. Moreover, it was found that some phenolic compounds were effectively removed. The refractory organic compounds were primarily removed in ZVI process of the integrated system. These compounds, with molecular weights either ranged 10,000-30,000 Da or 0-2000 Da, were mainly the humic acid (HA) and hydrophilic (HyI) compounds. Oxidation-reduction and coagulation were the main removal mechanisms in ZVI process, which could enhance the biodegradability of the system effluent. Furthermore, the integrated system showed a rapid recovery performance against the sudden loading shock and remained high efficiencies for pollutants removal. Overall, the integrated system was proved feasible for coking wastewater treatment in practical applications

  7. Autohydrogenotrophic denitrification of drinking water using a polyvinyl chloride hollow fiber membrane biofilm reactor

    International Nuclear Information System (INIS)

    A hollow fiber membrane biofilm reactor (MBfR) using polyvinyl chloride (PVC) hollow fiber was evaluated in removing nitrate form contaminated drinking water. During a 279-day operation period, the denitrification rate increased gradually with the increase of influent nitrate loading. The denitrification rate reached a maximum value of 414.72 g N/m3 d (1.50 g N/m2 d) at an influent NO3--N concentration of 10 mg/L and a hydraulic residence time of 37.5 min, and the influent nitrate was completely reduced. At the same time, the effluent quality analysis showed the headspace hydrogen content (3.0%) was lower enough to preclude having an explosive air. Under the condition of the influent nitrate surface loading of 1.04 g N/m2d, over 90% removal efficiencies of the total nitrogen and nitrate were achieved at the hydrogen pressure above 0.04 MPa. The results of denaturing gel gradient electrophoresis (DGGE), 16S rDNA gene sequence analysis, and hierarchical cluster analysis showed that the microbial community structures in MBfR were of low diversity, simple and stable at mature stages; and the beta-Proteobacteria, including Rhodocyclus, Hydrogenophaga, and beta-Proteobacteria HTCC379, probably play an important role in autohydrogenotrophic denitrification.

  8. Demonstration study of biofilm reactor based rapid biochemical oxygen demand determination of surface water

    Directory of Open Access Journals (Sweden)

    Changyu Liu

    2016-05-01

    Full Text Available Application investigations of rapid biochemical oxygen demand (BOD online analyzer for surface water in Wuxi, China were carried out since 2013. The analyzer adopted a novel working principle, that is, the oxygen concentration of the sample to be tested was regarded as a reference, and the oxygen consumption by the biofilm reactor (BFR was calculated according to the difference between the reference and sample effluent from BFR. The BFR was fabricated via a cultivation process using naturally occurring microbial seeds from in site surface water. This analytical principle was first presented and clearly clarified, and the impact of microbial endogenous respiration to the measured values was also proposed and analyzed. The improved analyzers were equipped in three application sites with significant differences in BOD concentration, for the purpose of evaluating the feasibility and applicability of the proposed method. This study revealed that the online analyzer could continually operate over 30 days without human intervention and additional chemical reagent consumption. The obtained rapid BOD trend line showed that this analyzer could track the fluctuation of the biodegradable organic compound level timely and accurately. The innovative analytical method, as well as the outstanding adaptation and well accuracy rating, provided the highlights for wide applications in the future.

  9. Impact of free ammonia on anammox rates (anoxic ammonium oxidation) in a moving bed biofilm reactor.

    Science.gov (United States)

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2012-06-01

    Using a bench scale moving bed bioreactor (MBBR), the effect of free ammonia (FA, NH(3), the un-ionized form of ammonium NH(4)(+)) concentration on anoxic ammonium oxidation (anammox) was evaluated based on the volumetric nitrogen removal rate (NRR). Although, a detailed microbial analysis was not conducted, the major NRR observed was assumed to be by anammox, based on the nitrogen conversion ratios of nitrite to ammonium and nitrate to ammonium. Since the concentration of free ammonia as a proportion of the total ammonia concentration is pH-dependent, the impact of changing the operating pH from 6.9 to 8.2, was investigated under constant nitrogen loading conditions during continuous reactor operation. Furthermore, the effect of sudden nitrogen load changes was investigated under constant pH conditions. Batch tests were conducted to determine the immediate response of the anammox consortium to shifts in pH and FA concentrations. It was found that FA was inhibiting NRR at concentrations exceeding 2 mg N L(-1). In the pH range 7-8, the decrease in anammox activity was independent of pH and related only to the concentration of FA. Nitrite concentrations of up to 120 mg N L(-1) did not negatively affect NRR for up to 3.5 h. It was concluded that a stable NRR in a moving bed biofilm reactor depended on maintaining FA concentrations below 2 mg N L(-1) when the pH was maintained between 7 and 8. PMID:22483855

  10. Final Stage Development of Reactor Console Simulator

    International Nuclear Information System (INIS)

    The Reactor Console Simulator PUSPATI TRIGA Reactor was developed since end of 2011 and now in the final stage of development. It is will be an interactive tool for operator training and teaching of PUSPATI TRIGA Reactor. Behavior and characteristic for reactor console and reactor itself can be evaluated and understand. This Simulator will be used as complement for actual present reactor console. Implementation of human system interface (HSI) is using computer screens, keyboard and mouse. Multiple screens are used to match the physical of present reactor console. LabVIEW software are using for user interface and mathematical calculation. Polynomial equation based on control rods calibration data as well as operation parameters record was used to calculate and estimated reactor console parameters. The capabilities in user interface, reactor physics and thermal-hydraulics can be expanded and explored to simulation as well as modeling for New Reactor Console, Research Reactor and Nuclear Power Plant. (author)

  11. Evaluation of micropollutant removal and fouling reduction in a hybrid moving bed biofilm reactor-membrane bioreactor system.

    Science.gov (United States)

    Luo, Yunlong; Jiang, Qi; Ngo, Huu H; Nghiem, Long D; Hai, Faisal I; Price, William E; Wang, Jie; Guo, Wenshan

    2015-09-01

    A hybrid moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) system and a conventional membrane bioreactor (CMBR) were compared in terms of micropollutant removal efficiency and membrane fouling propensity. The results show that the hybrid MBBR-MBR system could effectively remove most of the selected micropollutants. By contrast, the CMBR system showed lower removals of ketoprofen, carbamazepine, primidone, bisphenol A and estriol by 16.2%, 30.1%, 31.9%, 34.5%, and 39.9%, respectively. Mass balance calculations suggest that biological degradation was the primary removal mechanism in the MBBR-MBR system. During operation, the MBBR-MBR system exhibited significantly slower fouling development as compared to the CMBR system, which could be ascribed to the wide disparity in the soluble microbial products (SMP) levels between MBBR-MBR (4.02-6.32 mg/L) and CMBR (21.78 and 33.04 mg/L). It is evident that adding an MBBR process prior to MBR treatment can not only enhance micropollutant elimination but also mitigate membrane fouling. PMID:26031758

  12. The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus.

    Directory of Open Access Journals (Sweden)

    Jin Hwan Park

    2015-09-01

    Full Text Available A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3',5'-cyclic diguanylic acid (c-di-GMP and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose.

  13. Design of a Simple Model of Candida albicans Biofilms Formed under Conditions of Flow: Development, Architecture and Drug Resistance

    OpenAIRE

    Uppuluri, Priya; Chaturvedi, Ashok K.; Ribot, Jose Lopez

    2009-01-01

    Candida albicans biofilms on most medical devices are exposed to a flow of body fluids that provide water and nutrients to the fungal cells. While C. albicans biofilms grown in vitro under static conditions have been exhaustively studied, the same is not true for biofilms developed under continuous flow of replenishing nutrients. Here, we describe a simple flow biofilm (FB) model that can be built easily with materials commonly available in most microbiological laboratories. We demonstrate th...

  14. Removal of multiple electron acceptors by pilot-scale, two-stage membrane biofilm reactors.

    Science.gov (United States)

    Zhao, He-Ping; Ontiveros-Valencia, Aura; Tang, Youneng; Kim, Bi-O; Vanginkel, Steven; Friese, David; Overstreet, Ryan; Smith, Jennifer; Evans, Patrick; Krajmalnik-Brown, Rosa; Rittmann, Bruce

    2014-05-01

    We studied the performance of a pilot-scale membrane biofilm reactor (MBfR) treating groundwater containing four electron acceptors: nitrate (NO3(-)), perchlorate (ClO4(-)), sulfate (SO4(2-)), and oxygen (O2). The treatment goal was to remove ClO4(-) from ∼200 μg/L to less than 6 μg/L. The pilot system was operated as two MBfRs in series, and the positions of the lead and lag MBfRs were switched regularly. The lead MBfR removed at least 99% of the O2 and 63-88% of NO3(-), depending on loading conditions. The lag MBfR was where most of the ClO4(-) reduction occurred, and the effluent ClO4(-) concentration was driven to as low as 4 μg/L, with most concentrations ≤10 μg/L. However, SO4(2-) reduction occurred in the lag MBfR when its NO3(-) + O2 flux was smaller than ∼0.18 g H2/m(2)-d, and this was accompanied by a lower ClO4(-) flux. We were able to suppress SO4(2-) reduction by lowering the H2 pressure and increasing the NO3(-) + O2 flux. We also monitored the microbial community using the quantitative polymerase chain reaction targeting characteristic reductase genes. Due to regular position switching, the lead and lag MBfRs had similar microbial communities. Denitrifying bacteria dominated the biofilm when the NO3(-) + O2 fluxes were highest, but sulfate-reducing bacteria became more important when SO4(2-) reduction was enhanced in the lag MBfR due to low NO3(-) + O2 flux. The practical two-stage strategy to achieve complete ClO4(-) and NO3(-) reduction while suppressing SO4(2-) reduction involved controlling the NO3(-) + O2 surface loading between 0.18 and 0.34 g H2/m(2)-d and using a low H2 pressure in the lag MBfR. PMID:24565802

  15. Treatment of pesticide wastewater by moving-bed biofilm reactor combined with Fenton-coagulation pretreatment

    International Nuclear Information System (INIS)

    In order to treat pesticide wastewater having high chemical oxygen demand (COD) value and poor biodegradability, Fenton-coagulation process was first used to reduce COD and improve biodegradability and then was followed by biological treatment. Optimal experimental conditions for the Fenton process were determined to be Fe2+ concentration of 40 mmol/L and H2O2 dose of 97 mmol/L at initial pH 3. The interaction mechanism of organophosphorous pesticide and hydroxyl radicals was suggested to be the breakage of the P=S double bond and formation of sulfate ions and various organic intermediates, followed by formation of phosphate and consequent oxidation of intermediates. For the subsequent biological treatment, 3.2 g/L Ca(OH)2 was added to adjust the pH and further coagulate the pollutants. The COD value could be evidently decreased from 33,700 to 9300 mg/L and the ratio of biological oxygen demand (BOD5) to COD of the wastewater was enhanced to over 0.47 by Fenton oxidation and coagulation. The pre-treated wastewater was then subjected to biological oxidation by using moving-bed biofilm reactor (MBBR) inside which tube chip type bio-carriers were fluidized upon air bubbling. Higher than 85% of COD removal efficiency could be achieved when the bio-carrier volume fraction was kept more than 20% by feeding the pretreated wastewater containing 3000 mg/L of inlet COD at one day of hydraulic retention time (HRT), but a noticeable decrease in the COD removal efficiency when the carrier volume was decreased down to 10%, only 72% was observed. With the improvement of biodegradability by using Fenton pretreatment, also due to the high concentration of biomass and high biofilm activity using the fluidizing bio-carriers, high removal efficiency and stable operation could be achieved in the biological process even at a high COD loading of 37.5 gCOD/(m2 carrier day)

  16. Biofilm Matrix Proteins

    OpenAIRE

    Fong, Jiunn N. C.; Yildiz, Fitnat H.

    2015-01-01

    Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enz...

  17. Sequential Aeration of Membrane-Aerated Biofilm Reactors for High-Rate Autotrophic Nitrogen Removal: Experimental Demonstration

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Sun, Sheng-Peng; Lackner, Susanne;

    2010-01-01

    One-stage autotrophic nitrogen (N) removal, requiring the simultaneous activity of aerobic and anaerobic ammonium oxidizing bacteria (AOB and AnAOB), can be obtained in spatially redox-stratified biofilms. However, previous experience with Membrane-Aerated Biofilm Reactors (MABRs) has revealed a...... difficulty in reducing the abundance and activity of nitrite oxidizing bacteria (NOB), which drastically lowers process efficiency. Here we show how sequential aeration is an effective strategy to attain autotrophic N removal in MABRs: Two separate MABRs, which displayed limited or no N removal under......S rRNA gene confirmed that sequential aeration, even at elevated average O2 loads, stimulated the abundance of AnAOB and AOB and prevented the increase in NOB. Nitrous oxide (N2O) emissions were 100-fold lower compared to other anaerobic ammonium oxidation (Anammox)-nitritation systems. Hence, by...

  18. Nitritation and denitritation of ammonium-rich wastewater using fluidized-bed biofilm reactors

    International Nuclear Information System (INIS)

    Fluidized-bed biofilm nitritation and denitritation reactors (FBBNR and FBBDR) were operated to eliminate the high concentrations of nitrogen by nitritation and denitritation process. The dissolved oxygen (DO) concentration was varied from 1.5 to 2.5 g/m3 at the top of the reactor throughout the experiment. NH4-N conversion and NO2-N accumulation in the nitritation reactor effluent was over 90 and 65%, respectively. The average NH4-N removal efficiency was 99.2 and 90.1% at the NLR of 0.9 and 1.2 kg NH4-N/m3 day, respectively. Increasing the NLR from 1.1 to 1.2 kg NH4-N/m3 day decreased the NH4-N elimination approximately two-fold while NH4-N conversion to NO2-N differences were negligible. The NO2-N/NOx-N ratios corresponded to 0.74, 0.73, 0.72, and 0.69, respectively, indicating the occurrence of partial nitrification. An average free ammonia concentration in the FBBNR was high enough to inhibit nitrite oxidizers selectively, and it seems to be a determining factor for NO2-N accumulation in the process. In the FBBDR, the NOx-N (NO2-N + NO3-N) concentrations supplied were between 227 and 330 mg N/l (NLR was between 0.08 and 0.4 kg/m3 day) and the influent flow was increased as long as the total nitrogen removal was close to 90%. The NO2-N and NO3-N concentrations in the effluent were 3.0 and 0.9 mg/l at 0.08 kg/m3 day loading rate. About 98% removal of NOx-N was achieved at the lowest NLR in the FBBDR. The FBBDR exhibited high nitrogen removal up to the NLR of 0.25 kg/m3 day. The NOx-N effluent concentration never exceeded 15 mg/l. The total nitrogen removal efficiency in the FBBRs was higher than 93% at 21 ± 1 deg. C

  19. Microbial activity catalyzes oxygen transfer in membrane-aerated nitritating biofilm reactors

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Domingo Felez, Carlos; Lackner, Susanne;

    2013-01-01

    attain partial nitritation showed that predicted oxygen transfer rates are enhanced up to six times with biofilm activity. The higher availability of ammonia at the biofilm base drives this process. Such behavior can be captured with the addition of two terms (depending on system characteristics and...

  20. Plasma treatment of electrodes significantly enhances the development of anodic electrochemically active biofilms

    International Nuclear Information System (INIS)

    Highlights: • Plasma pre-treatment of electrodes produces chemical modifications at surface level. • Nitrogen and plasma treatment were studied before inoculation with a mixed microbial consortia. • Plasma treatment accelerates the current development in microbial bio-electrochemical systems. • Plasma enhances the initial attachment of cells. • After treatment, a mature electroactive biofilm is developed in half the time as blank electrodes. -- Abstract: Surface modifications of electrode materials are important for improved performance of microbial bio-electrochemical systems. Here, we studied the effect of pre-treating both glassy carbon and graphite felt electrodes with either an oxygen or a nitrogen plasma before reactor inoculation with a mixed microbial consortia. The plasma produces chemical modifications at the electrode surface level. X-ray photoelectron spectroscopy and water contact angle analysis showed that the plasma removes surface contamination, produces ion implantation and renders the hydrophobic surfaces highly hydrophilic. Plasma pre-treatment considerably accelerated the generation of a bio-electrochemical anodic current after inoculation. Nitrogen plasma pre-treatment yielded the best performance, followed closely by oxygen plasma. Plasma pre-treated electrodes reached a plateau of maximum current density twice as fast as untreated electrodes. Analysis of the current development profiles suggests that the plasma pre-treatment is neither producing a preferential attachment of certain types of bacteria over others nor accelerating the extracellular electron transfer rate. The results indicate that the plasma treatment considerably enhances the initial cell adhesion, which results in subsequently faster biofilm development. Plasma pre-treatment of electrodes is an inexpensive, fast, safe and straightforward technique to achieve more rapid start-up of bio-electrochemical processes

  1. Rock physics models for constraining quantitative interpretation of ultrasonic data for biofilm growth and development

    Science.gov (United States)

    Alhadhrami, Fathiya Mohammed

    This study examines the use of rock physics modeling for quantitative interpretation of seismic data in the context of microbial growth and biofilm formation in unconsolidated sediment. The impetus for this research comes from geophysical experiments by Davis et al. (2010) and Kwon and Ajo-Franklin et al. (2012). These studies observed that microbial growth has a small effect on P-wave velocities (VP) but a large effect on seismic amplitudes. Davis et al. (2010) and Kwon and Ajo-Franklin et al. (2012) speculated that the amplitude variations were due to a combination of rock mechanical changes from accumulation of microbial growth related features such as biofilms. A more definite conclusion can be drawn by developing rock physics models that connect rock properties to seismic amplitudes. The primary objective of this work is to provide an explanation for high amplitude attenuation due to biofilm growth. The results suggest that biofilm formation in the Davis et al. (2010) experiment exhibit two growth styles: a loadbearing style where biofilm behaves like an additional mineral grain and a non-loadbearing mode where the biofilm grows into the pore spaces. In the loadbearing mode, the biofilms contribute to the stiffness of the sediments. We refer to this style as "filler." In the non-loadbearing mode, the biofilms contribute only to change in density of sediments without affecting their strength. We refer to this style of microbial growth as "mushroom." Both growth styles appear to be changing permeability more than the moduli or the density. As the result, while the VP velocity remains relatively unchanged, the amplitudes can change significantly depending on biofilm saturation. Interpreting seismic data from biofilm growths in term of rock physics models provide a greater insight into the sediment-fluid interaction. The models in turn can be used to understand microbial enhanced oil recovery and in assisting in solving environmental issues such as creating bio

  2. Biofilm development by potentially pathogenic non-pigmented rapidly growing mycobacteria

    OpenAIRE

    Fernández-Roblas Ricardo; Ayala Guillermo; Kinnari Teemu J; Martín-de-Hijas Nieves Z; Esteban Jaime; Gadea Ignacio

    2008-01-01

    Abstract Background A study to evaluate the biofilm-development ability in three different media (Middlebrook 7H9, sterile tap water and PBS-5% glucose) was performed with 19 collection strains from 15 different species on non-pigmented rapidly growing mycobacteria (NPRGM). A microtiter plate assay was developed to evaluate the percentage of covered surface of the microtiter plate wells in different days from day 1 to day 69. Results All strains were able to develop biofilm in all the tested ...

  3. Study of hydraulic and toxic shocks in two anaerobic-aerobic Pilot Moving Bed Biofilm Reactors used for nitrification and denitrification

    International Nuclear Information System (INIS)

    Pilot Moving Bed Biofilm Reactors fed on synthetic wastewater, were used in order to study nitrification and denitrification of high concentration wastewater. To investigate the stability of the nitrification and denitrification process in moving bed biofilm systems, a hydraulic shock and a toxic shock were applied to the system. These two systems showed high stability and process efficiency did not change significantly, in spite of intensive variation during the applied shocks

  4. Prediction of moving bed biofilm reactor (MBBR) performance for the treatment of aniline using artificial neural networks (ANN)

    International Nuclear Information System (INIS)

    In this study, the results of 1-year efficiency forecasting using artificial neural networks (ANN) models of a moving bed biofilm reactor (MBBR) for a toxic and hard biodegradable aniline removal were investigated. The reactor was operated in an aerobic batch and continuous condition with 50% by volume which was filled with light expanded clay aggregate (LECA) as carrier. Efficiency evaluation of the reactors was obtained at different retention time (RT) of 8, 24, 48 and 72 h with an influent COD from 100 to 4000 mg/L. Exploratory data analysis was used to detect relationships between the data and dependent evaluated one. The appropriate architecture of the neural network models was determined using several steps of training and testing of the models. The ANN-based models were found to provide an efficient and a robust tool in predicting MBBR performance for treating aromatic amine compounds.

  5. Feasible reactor power cutback logic development for an integral reactor

    Energy Technology Data Exchange (ETDEWEB)

    Han, Soon-Kyoo [KHNP Co., Ltd., Uljin-gun, Gyeong-buk (Korea, Republic of); Lee, Chung-Chan; Choi, Suhn; Kang, Han-Ok [Korea Atomic Energy Research Institute (KAERI), Daedeokdaero, Yuseong, Daejeon (Korea, Republic of)

    2013-07-15

    Major features of integral reactors that have been developed around the world recently are simplified operating systems and passive safety systems. Even though highly simplified control system and very reliable components are utilized in the integral reactor, the possibility of major component malfunction cannot be ruled out. So, feasible reactor power cutback logic is required to cope with the malfunction of components without inducing reactor trip. Simplified reactor power cutback logic has been developed on the basis of the real component data and operational parameters of plant in this study. Due to the relatively high rod worth of the integral reactor the control rod assembly drop method which had been adapted for large nuclear power plants was not desirable for reactor power cutback of the integral reactor. Instead another method, the control rod assembly control logic of reactor regulating system controls the control rod assembly movements, was chosen as an alternative. Sensitivity analyses and feasibility evaluations were performed for the selected method by varying the control rod assembly driving speed. In the results, sensitivity study showed that the performance goal of reactor power cutback system could be achieved with the limited range of control rod assembly driving speed. (orig.)

  6. Feasible reactor power cutback logic development for an integral reactor

    International Nuclear Information System (INIS)

    Major features of integral reactors that have been developed around the world recently are simplified operating systems and passive safety systems. Even though highly simplified control system and very reliable components are utilized in the integral reactor, the possibility of major component malfunction cannot be ruled out. So, feasible reactor power cutback logic is required to cope with the malfunction of components without inducing reactor trip. Simplified reactor power cutback logic has been developed on the basis of the real component data and operational parameters of plant in this study. Due to the relatively high rod worth of the integral reactor the control rod assembly drop method which had been adapted for large nuclear power plants was not desirable for reactor power cutback of the integral reactor. Instead another method, the control rod assembly control logic of reactor regulating system controls the control rod assembly movements, was chosen as an alternative. Sensitivity analyses and feasibility evaluations were performed for the selected method by varying the control rod assembly driving speed. In the results, sensitivity study showed that the performance goal of reactor power cutback system could be achieved with the limited range of control rod assembly driving speed. (orig.)

  7. Flow velocity impact on biofilm development in subsurface environments - A laboratory experiment

    Science.gov (United States)

    Roubinet, D.; Boisson, A.; Aquilina, L.; Bour, O.; Davy, P.

    2012-12-01

    Biofilm development is the result of complex interactions between structural, physical, chemical and biological properties. Natural circulation of chemically rich water in subsurface environments both promotes and limits biofilm growth, with a strong impact on its shape and reactivity. Understanding the interaction between hydrodynamic processes and biofilm properties requires more experimental and modeling investigations. We propose an experimental approach to study the relationship between hydrodynamic parameters and reactivity at the pore-scale. The experimental set-up allows monitoring denitrification process for nitrate rich site water passing continuously through plastic tubes for several flow velocities. This idealized 1D flow experiment enables to reproduce pore-scale interactions between flow velocity and biological activities in natural conditions. The observed dynamic of nitrate transformation is related to different evolution of the biofilm structure and illustrates the impact of flow velocity on biofilm growth and shape. It leads to identify several regimes at the different phases of the biofilm development where flow velocity is a determinant factor for biofilm stability and performance.

  8. Effect of mechanical stress on biofilms challenged by different chemicals

    OpenAIRE

    Simões, M; Pereira, Maria Olívia; Vieira, M. J.

    2005-01-01

    In this study a methodology was applied in order to ascertain the mechanical stability of biofilms, by using a stainlesssteel (SS) rotating device immersed in a biological reactor where biofilms formed by Pseudomonas fluorescens were allowed to grow for 7 days at a Reynolds number of agitation of 2400. The biofilms developed with this system were characterised in terms of amount of total, extracellular and intracellular proteins and polysaccharides, amount of mass, metabolic activ...

  9. Method for Studying Microbial Biofilms in Flowing-Water Systems

    OpenAIRE

    Pedersen, Karsten

    1982-01-01

    A method for the study of microbial biofilms in flowing-water systems was developed with special reference to the flow conditions in electrochemical concentration cells. Seawater was circulated in a semiclosed flow system through biofilm reactors (3 cm s−1) with microscope cover slips arranged in lamellar piles parallel with the flow. At fixed time intervals cover slips with their biofilm were removed from the pile, stained with crystal violet, and mounted on microscope slides. The absorbance...

  10. Streptococcus mutans protein synthesis during mixed-species biofilm development by high-throughput quantitative proteomics.

    Science.gov (United States)

    Klein, Marlise I; Xiao, Jin; Lu, Bingwen; Delahunty, Claire M; Yates, John R; Koo, Hyun

    2012-01-01

    Biofilms formed on tooth surfaces are comprised of mixed microbiota enmeshed in an extracellular matrix. Oral biofilms are constantly exposed to environmental changes, which influence the microbial composition, matrix formation and expression of virulence. Streptococcus mutans and sucrose are key modulators associated with the evolution of virulent-cariogenic biofilms. In this study, we used a high-throughput quantitative proteomics approach to examine how S. mutans produces relevant proteins that facilitate its establishment and optimal survival during mixed-species biofilms development induced by sucrose. Biofilms of S. mutans, alone or mixed with Actinomyces naeslundii and Streptococcus oralis, were initially formed onto saliva-coated hydroxyapatite surface under carbohydrate-limiting condition. Sucrose (1%, w/v) was then introduced to cause environmental changes, and to induce biofilm accumulation. Multidimensional protein identification technology (MudPIT) approach detected up to 60% of proteins encoded by S. mutans within biofilms. Specific proteins associated with exopolysaccharide matrix assembly, metabolic and stress adaptation processes were highly abundant as the biofilm transit from earlier to later developmental stages following sucrose introduction. Our results indicate that S. mutans within a mixed-species biofilm community increases the expression of specific genes associated with glucan synthesis and remodeling (gtfBC, dexA) and glucan-binding (gbpB) during this transition (P<0.05). Furthermore, S. mutans up-regulates specific adaptation mechanisms to cope with acidic environments (F1F0-ATPase system, fatty acid biosynthesis, branched chain amino acids metabolism), and molecular chaperones (GroEL). Interestingly, the protein levels and gene expression are in general augmented when S. mutans form mixed-species biofilms (vs. single-species biofilms) demonstrating fundamental differences in the matrix assembly, survival and biofilm maintenance in the

  11. Streptococcus mutans protein synthesis during mixed-species biofilm development by high-throughput quantitative proteomics.

    Directory of Open Access Journals (Sweden)

    Marlise I Klein

    Full Text Available Biofilms formed on tooth surfaces are comprised of mixed microbiota enmeshed in an extracellular matrix. Oral biofilms are constantly exposed to environmental changes, which influence the microbial composition, matrix formation and expression of virulence. Streptococcus mutans and sucrose are key modulators associated with the evolution of virulent-cariogenic biofilms. In this study, we used a high-throughput quantitative proteomics approach to examine how S. mutans produces relevant proteins that facilitate its establishment and optimal survival during mixed-species biofilms development induced by sucrose. Biofilms of S. mutans, alone or mixed with Actinomyces naeslundii and Streptococcus oralis, were initially formed onto saliva-coated hydroxyapatite surface under carbohydrate-limiting condition. Sucrose (1%, w/v was then introduced to cause environmental changes, and to induce biofilm accumulation. Multidimensional protein identification technology (MudPIT approach detected up to 60% of proteins encoded by S. mutans within biofilms. Specific proteins associated with exopolysaccharide matrix assembly, metabolic and stress adaptation processes were highly abundant as the biofilm transit from earlier to later developmental stages following sucrose introduction. Our results indicate that S. mutans within a mixed-species biofilm community increases the expression of specific genes associated with glucan synthesis and remodeling (gtfBC, dexA and glucan-binding (gbpB during this transition (P<0.05. Furthermore, S. mutans up-regulates specific adaptation mechanisms to cope with acidic environments (F1F0-ATPase system, fatty acid biosynthesis, branched chain amino acids metabolism, and molecular chaperones (GroEL. Interestingly, the protein levels and gene expression are in general augmented when S. mutans form mixed-species biofilms (vs. single-species biofilms demonstrating fundamental differences in the matrix assembly, survival and biofilm

  12. Effects of pH profiles on nisin production in biofilm reactor.

    Science.gov (United States)

    Pongtharangkul, Thunyarat; Demirci, Ali

    2006-08-01

    Apart from its widely accepted commercial applications as a food preservative, nisin emerges as a promising alternative in medical applications for bacterial infection in both humans and livestock. Improving nisin production through optimization of fermentation parameters would make nisin more cost-effective for various applications. Since nisin production by Lactococcus lactis NIZO 22186 was highly influenced by the pH profile employed during fermentation, three different pH profiles were evaluated in this study: (1) a constant pH profile at 6.8 (profile 1), (2) a constant pH profile with autoacidification at 4 h (profile 2), and (3) a stepwise pH profile with pH adjustment every 2 h (profile 3). The results demonstrated that the low-pH stress exerted during the first 4 h of fermentation in profile 3 detrimentally affected nisin production, resulting in a very low maximum nisin concentration (593 IU ml(-1)). On the other hand, growth and lactic acid production were only slightly delayed, indicating that the loss in nisin production was not a result of lower growth or shifting of metabolic activity toward lactic acid production. Profile 2, in which pH was allowed to drop freely via autoacidification after 4 h of fermentation, was found to yield almost 1.9 times higher nisin (3,553 IU ml(-1)) than profile 1 (1,898 IU ml(-1)), possibly as a result of less adsorption of nisin onto producer cells. Therefore, a combination of constant pH and autoacidification period (profile 2) was recommended as the pH profile during nisin production in a biofilm reactor. PMID:16331455

  13. msaABCR operon positively regulates biofilm development by repressing proteases and autolysis in Staphylococcus aureus

    OpenAIRE

    Sahukhal, Gyan S; Batte, Justin L.; Elasri, Mohamed O.

    2015-01-01

    Staphylococcus aureus is an important human pathogen that causes nosocomial and community-acquired infections. One of the most important aspects of staphylococcal infections is biofilm development within the host, which renders the bacterium resistant to the host’s immune response and antimicrobial agents. Biofilm development is very complex and involves several regulators that ensure cell survival on surfaces within the extracellular polymeric matrix. Previously, we identified the msaABCR op...

  14. Involvement of bacterial migration in the development of complex multicellular structures in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Klausen, Mikkel; Aaes-Jorgensen, A.; Molin, Søren;

    2003-01-01

    development, we have performed an investigation with time-lapse confocal laser scanning microscopy of biofilms formed by various combinations of colour-coded P. aeruginosa wild type and motility mutants. We show that mushroom-shaped multicellular structures in P. aeruginosa biofilms can form in a sequential...... process involving a non-motile bacterial subpopulation and a migrating bacterial subpopulation. The non-motile bacteria form the mushroom stalks by growth in certain foci of the biofilm. The migrating bacteria form the mushroom caps by climbing the stalks and aggregating on the tops in a process which...

  15. The AECL reactor development programme

    International Nuclear Information System (INIS)

    The modem CANDU-PHWR power reactor is the result of more than 50 years of evolutionary design development in Canada. It is one of only three commercially successful designs in the world to this date. The basis for future development is the CANDU 6 and CANDU 9 models. Four of the first type are operating and four more will go an line before the end of this decade. The CANDU 9 is a modernized single-unit version of the twelve large multi-unit plants operated by Ontario Hydro. All of these plants use proven technology which resulted from research, development, design construction, and operating experience over the past 25 years. Looking forward another 25 years, AECL plans to retain all of the essential features that distinguish today's CANDU reactors (heavy water moderation, on-power fuelling simple bundle design, horizontal fuel channels, etc.). The end product of the planned 25-year development program is more than a specific design - it is a concept which embodies advanced features expected from ongoing R and D programs. To carry out the evolutionary work we have selected seven main areas for development: Safety Technology, Fuel and Fuel Cycles, Fuel Channels, Systems and Components, Heavy Water and Tritium Information Technology, and Construction. There are three strategic measures of success for each of these work areas: improved economics, advanced fuel cycle utilization, and enhanced safety/plant robustness. The paper describes these work programs and the overall goals of each of them. (author)

  16. Environmental switching during biofilm development in a cold seep system and functional determinants of species sorting

    KAUST Repository

    Zhang, Weipeng

    2015-11-28

    The functional basis for species sorting theory remains elusive, especially for microbial community assembly in deep sea environments. Using artificial surface-based biofilm models, our recent work revealed taxonomic succession during biofilm development in a newly defined cold seep system, the Thuwal cold seeps II, which comprises a brine pool and the adjacent normal bottom water (NBW) to form a metacommunity via the potential immigration of organisms from one patch to another. Here, we designed an experiment to investigate the effects of environmental switching between the brine pool and the NBW on biofilm assembly, which could reflect environmental filtering effects during bacterial immigration to new environments. Analyses of 16S rRNA genes of 71 biofilm samples suggested that the microbial composition of biofilms established in new environments was determined by both the source community and the incubation conditions. Moreover, a comparison of 18 metagenomes provided evidence for biofilm community assembly that was based primarily on functional features rather than taxonomic identities; metal ion resistance and amino acid metabolism were the major species sorting determinants for the succession of biofilm communities. Genome binning and pathway reconstruction of two bacterial species (Marinobacter sp. and Oleispira sp.) further demonstrated metal ion resistance and amino acid metabolism as functional traits conferring the survival of habitat generalists in both the brine pool and NBW. The results of the present study sheds new light on microbial community assembly in special habitats and bridges a gap in species sorting theory.

  17. ANALYSIS OF CHROMATE UPTAKE IN BACTERIAL BIOFILMS DEVELOPED ON ABIOTIC SUPPORT

    Directory of Open Access Journals (Sweden)

    Aditi Bhattacharya

    2014-08-01

    Full Text Available Microorganisms also practice community living and form biofilms developed on preferred surfaces. The sessile and planktonic organisms show differences in hydrophobicity as determined by the BATH index. The saccharides of the EPS produced was determined using the phenol-sulphuric acid method and Rhamnolipids using the Orcinol method. Dye released from stained biofilms is also indicative of the density of the biofilm. Motility was reduced on formation of cell aggregates in mature biofilms. The extent of light penetration through the biofilms indicates the extent of stacking, its cohesive or incrusting nature, determined using a light meter. Chromium has wide industrial use and hexavalent chromate is toxic on account of its higher solubility. Among the different processes and approaches being used by microorganisms for chromate remediation, the use of biofilms may be a good alternative for bioremediation of hexavalent chromium to trivalent chromium. Chromate uptake was studied in suspended or free living daughter cells that have originated out of a single mature biofilm. FTIR spectra of loaded and unloaded biomass can be used to determine the functional groups responsible for biosorption of chromium

  18. Environmental switching during biofilm development in a cold seep system and functional determinants of species sorting.

    Science.gov (United States)

    Zhang, Weipeng; Tian, Renmao; Bo, Yang; Cao, Huiluo; Cai, Lin; Chen, Lianguo; Zhou, Guowei; Sun, Jin; Zhang, Xixiang; Al-Suwailem, Abdulaziz; Qian, Pei-Yuan

    2016-05-01

    The functional basis for species sorting theory remains elusive, especially for microbial community assembly in deep-sea environments. Using artificial surface-based biofilm models, our recent work revealed taxonomic succession during biofilm development in a newly defined cold seep system, the Thuwal cold seeps II, which comprises a brine pool and the adjacent normal bottom water (NBW) to form a metacommunity via the potential immigration of organisms from one patch to another. Here, we designed an experiment to investigate the effects of environmental switching between the brine pool and the NBW on biofilm assembly, which could reflect environmental filtering effects during bacterial immigration to new environments. Analyses of 16S rRNA genes of 71 biofilm samples suggested that the microbial composition of biofilms established in new environments was determined by both the source community and the incubation conditions. Moreover, a comparison of 18 metagenomes provided evidence for biofilm community assembly that was based primarily on functional features rather than taxonomic identities; metal ion resistance and amino acid metabolism were the major species sorting determinants for the succession of biofilm communities. Genome binning and pathway reconstruction of two bacterial species (Marinobacter sp. and Oleispira sp.) further demonstrated metal ion resistance and amino acid metabolism as functional traits conferring the survival of habitat generalists in both the brine pool and NBW. The results of this study shed new light on microbial community assembly in special habitats and bridge a gap in species sorting theory. PMID:26614914

  19. Different carbon isotope fractionation patterns during the development of phototrophic freshwater and marine biofilms

    Directory of Open Access Journals (Sweden)

    M. Staal

    2007-08-01

    Full Text Available Natural phototrophic biofilms are influenced by a broad array of abiotic and biotic factors and vary over temporal and spatial scales. Different developmental stages can be distinguished and growth rates will vary due to the thickening of the biofilm, which is expected to lead to a limitation of light or mass transport. This study shows that variation in CO2(aq availability leads to a fractionation shift and thereby affects δ13C signatures during biofilm development. For phototrophic freshwater biofilms it was found that the δ13C value became less negative with the thickening of the biofilm, while the opposite trend was found in marine biofilms. Modeling and pH profiling indicated that the trend in the freshwater system was caused by an increase in CO2(aq limitation resulting in an increase of HCO3 as C-source. The opposite trend in the marine system could be explained by a higher heterotrophic biomass and activity causing a higher carbon recycling and thereby lower δ13C values. We conclude that δ13C was more related to the net areal photosynthesis rate and carbon recycling, rather than to the growth rate of the biofilms.

  20. Dynamics of Streptococcus mutans transcriptome in response to starch and sucrose during biofilm development.

    Directory of Open Access Journals (Sweden)

    Marlise I Klein

    Full Text Available The combination of sucrose and starch in the presence of surface-adsorbed salivary α-amylase and bacterial glucosyltransferases increase the formation of a structurally and metabolically distinctive biofilm by Streptococcus mutans. This host-pathogen-diet interaction may modulate the formation of pathogenic biofilms related to dental caries disease. We conducted a comprehensive study to further investigate the influence of the dietary carbohydrates on S. mutans-transcriptome at distinct stages of biofilm development using whole genomic profiling with a new computational tool (MDV for data mining. S. mutans UA159 biofilms were formed on amylase-active saliva coated hydroxyapatite discs in the presence of various concentrations of sucrose alone (ranging from 0.25 to 5% w/v or in combination with starch (0.5 to 1% w/v. Overall, the presence of sucrose and starch (suc+st influenced the dynamics of S. mutans transcriptome (vs. sucrose alone, which may be associated with gradual digestion of starch by surface-adsorbed amylase. At 21 h of biofilm formation, most of the differentially expressed genes were related to sugar metabolism, such as upregulation of genes involved in maltose/maltotriose uptake and glycogen synthesis. In addition, the groEL/groES chaperones were induced in the suc+st-biofilm, indicating that presence of starch hydrolysates may cause environmental stress. In contrast, at 30 h of biofilm development, multiple genes associated with sugar uptake/transport (e.g. maltose, two-component systems, fermentation/glycolysis and iron transport were differentially expressed in suc+st-biofilms (vs. sucrose-biofilms. Interestingly, lytT (bacteria autolysis was upregulated, which was correlated with presence of extracellular DNA in the matrix of suc+st-biofilms. Specific genes related to carbohydrate uptake and glycogen metabolism were detected in suc+st-biofilms in more than one time point, indicating an association between presence of starch

  1. Simultaneous Organics and Nutrients Removal from Domestic Wastewater in a Combined Cylindrical Anoxic/Aerobic Moving Bed Biofilm Reactor

    OpenAIRE

    Husham T. Ibrahim; He Qiang; Wisaam S. Al-Rekabi

    2014-01-01

    The aim of present study was to design and construct an continuous up-flow pilot scale Moving Bed Biofilm Reactor (MBBR) which is consists of combined cylindrical Anoxic/Aerobic MBBR in nested form with anoxic/aerobic volume ratio equal to 0.16 to treated 4 m3 /days of domestic wastewater in Chongqing city at Southwest China. The treatment must be satisfactory to meet with grade B of discharge standard of pollutants for municipal wastewater treatment plant in China (GB/T18918-2002). Kaldnes (...

  2. Fast Reactor Development Strategy in China

    International Nuclear Information System (INIS)

    As one of the largest developing countries, China needs a reliable energy supplement. At the same time, China should improve the energy structure to decrease CO2 emissions. Nuclear and renewable energies are the main solutions to these issues. According to the research results, the nuclear capacity should increase to 400 GW(e) up to 2050. Fast reactors must be developed considering the limitation of uranium resources. In order to deploy fast reactor technology, the ‘experimental reactor, demonstration reactor and commercial reactor’ strategy has been suggested. China has finished the construction of the China Experimental Fast Reactor (CEFR) and gained necessary experience about fast reactors. The China Institute of Atomic Energy (CIAE) has begun to design the CFR-600, a 600 MW(e) demonstration fast reactor. This reactor will be put into operation before 2025. After that, a larger commercial reactor will be constructed. Besides fast reactors, all of other key sectors of fuel cycle will be developed at the same time such as reprocessing, fast reactor fuel, etc. There are two main tasks of fast reactors, one of which is to raise the utility ratio of uranium, and the other one is to transmute the long life waste of light water reactors. The fast reactor will be designed as a breeder and burner, respectively. (author)

  3. Effect of alcohols on filamentation, growth, viability and biofilm development in Candida albicans

    Directory of Open Access Journals (Sweden)

    Nitin M Chauhan

    2013-12-01

    Full Text Available In this study we report the potential of alcohols as morphogenetic regulators in Candida albicans. All the alcohols tested influenced various modes of growth like planktonic as well as biofilm forms. Viability was affected at high concentrations. Among the alcohols, the response of C. albicans to amyl alcohol (pentanol was noteworthy. Amyl alcohol at a concentration 0.5% which was not inhibitory to growth and viability specifically inhibited morphogenetic switching from yeast to hyphal forms. It also inhibited normal biofilm development favoring yeast dominated biofilms. Based on this study we hypothesize that alcohols produced under anaerobic conditions may not favor biofilm development and support dissemination of yeast cells. Since anaerobic conditions are not found to favor production of quorum sensing molecules like farnesol, the alcohols may play a role in morphogenetic regulation.

  4. Determining the optimal transmembrane gas pressure for nitrification in membrane-aerated biofilm reactors based on oxygen profile analysis.

    Science.gov (United States)

    Wang, Rongchang; Xiao, Fan; Wang, Yanan; Lewandowski, Zbigniew

    2016-09-01

    The goal of this study was to investigate the effect of transmembrane gas pressure (P g) on the specific ammonium removal rate in a membrane-aerated biofilm reactor (MABR). Our experimental results show that the specific ammonium removal rate increased from 4.98 to 9.26 gN m(-2) day(-1) when P g increased from 2 to 20 kPa in an MABR with a biofilm thickness of approximately 600 μm. However, this improvement was not linear; there was a threshold of P g separating the stronger and weaker effects of P g. The ammonium removal rate was improved less significantly when P g was over the threshold, indicating that there is an optimal threshold of P g for maximizing ammonium removal in an MABR. The change in oxygen penetration depth (d p) is less sensitive to P g in the ammonia-oxidizing active layer than in the inactive layer in membrane-aerated biofilm. The location of the P g threshold is at the same point as the thickness of the active layer on the curve of d p versus P g; thus, the active layer thickness and the optimal P g can be determined on the basis of the changes in the slope of d p to P g. PMID:27170321

  5. Mycoalgae biofilm: development of a novel platform technology using algae and fungal cultures

    OpenAIRE

    Rajendran, Aravindan; Hu, Bo

    2016-01-01

    Background Microalgae is considered a promising source for biofuel and bioenergy production, bio-remediation and production of high-value bioactive compounds, but harvesting microalgae is a major bottleneck in the algae based processes. The objective of this research is to mimic the growth of natural lichen and develop a novel biofilm platform technology using filamentous fungi and microalgae to form a lichen type of biofilm “mycoalgae” in a supporting polymer matrix. Results The possibility ...

  6. Development of In Vitro Denture Biofilm Models for Studying Denture-related Halitosis and Stomatitis

    OpenAIRE

    Wu, Tingxi

    2012-01-01

    Denture stomatitis and denture-related halitosis are two of the most prevalent denture related infectious diseases. The establishment of denture biofilm models for disease-associated pathogens is essential in further investigating the pathogenesis of these diseases. Chapter I and II of this thesis reported the successful development of denture biofilm model for Candida albican, the main pathogen of denterun stomatitis; as well as the denture models for halitosis-related bacteria, including Kl...

  7. Lysogenic Conversion and Phage Resistance Development in Phage Exposed Escherichia coli Biofilms

    Directory of Open Access Journals (Sweden)

    Abram Aertsen

    2013-01-01

    Full Text Available In this study, three-day old mature biofilms of Escherichia coli were exposed once to either a temperate Shiga-toxin encoding phage (H-19B or an obligatory lytic phage (T7, after which further dynamics in the biofilm were monitored. As such, it was found that a single dose of H-19B could rapidly lead to a near complete lysogenization of the biofilm, with a subsequent continuous release of infectious H-19B particles. On the other hand, a single dose of T7 rapidly led to resistance development in the biofilm population. Together, our data indicates a profound impact of phages on the dynamics within structured bacterial populations.

  8. Subaerial biofilms on granitic historic buildings: microbial diversity and development of phototrophic multi-species cultures.

    Science.gov (United States)

    Vázquez-Nion, D; Rodríguez-Castro, J; López-Rodríguez, M C; Fernández-Silva, I; Prieto, B

    2016-07-01

    Microbial communities of natural subaerial biofilms developed on granitic historic buildings of a World Heritage Site (Santiago de Compostela, NW Spain) were characterized and cultured in liquid BG11 medium. Environmental barcoding through next-generation sequencing (Pacific Biosciences) revealed that the biofilms were mainly composed of species of Chlorophyta (green algae) and Ascomycota (fungi) commonly associated with rock substrata. Richness and diversity were higher for the fungal than for the algal assemblages and fungi showed higher heterogeneity among samples. Cultures derived from natural biofilms showed the establishment of stable microbial communities mainly composed of Chlorophyta and Cyanobacteria. Although most taxa found in these cultures were not common in the original biofilms, they are likely common pioneer colonizers of building stone surfaces, including granite. Stable phototrophic multi-species cultures of known microbial diversity were thus obtained and their reliability to emulate natural colonization on granite should be confirmed in further experiments. PMID:27192622

  9. Lysogenic conversion and phage resistance development in phage exposed Escherichia coli biofilms.

    Science.gov (United States)

    Moons, Pieter; Faster, David; Aertsen, Abram

    2013-01-01

    In this study, three-day old mature biofilms of Escherichia coli were exposed once to either a temperate Shiga-toxin encoding phage (H-19B) or an obligatory lytic phage (T7), after which further dynamics in the biofilm were monitored. As such, it was found that a single dose of H-19B could rapidly lead to a near complete lysogenization of the biofilm, with a subsequent continuous release of infectious H-19B particles. On the other hand, a single dose of T7 rapidly led to resistance development in the biofilm population. Together, our data indicates a profound impact of phages on the dynamics within structured bacterial populations. PMID:23344561

  10. Enzymatic cleaning of biofouled thin-film composite reverse osmosis (RO) membrane operated in a biofilm membrane reactor.

    Science.gov (United States)

    Khan, Mohiuddin; Danielsen, Steffen; Johansen, Katja; Lorenz, Lindsey; Nelson, Sara; Camper, Anne

    2014-02-01

    Application of environmentally friendly enzymes to remove thin-film composite (TFC) reverse osmosis (RO) membrane biofoulants without changing the physico-chemical properties of the RO surface is a challenging and new concept. Eight enzymes from Novozyme A/S were tested using a commercially available biofouling-resistant TFC polyamide RO membrane (BW30, FilmTech Corporation, Dow Chemical Co.) without filtration in a rotating disk reactor system operated for 58 days. At the end of the operation, the accumulated biofoulants on the TFC RO surfaces were treated with the three best enzymes, Subtilisin protease and lipase; dextranase; and polygalacturonase (PG) based enzymes, at neutral pH (~7) and doses of 50, 100, and 150 ppm. Contact times were 18 and 36 h. Live/dead staining, epifluorescence microscopy measurements, and 5 μm thick cryo-sections of enzyme and physically treated biofouled membranes revealed that Subtilisin protease- and lipase-based enzymes at 100 ppm and 18 h contact time were optimal for removing most of the cells and proteins from the RO surface. Culturable cells inside the biofilm declined by more than five logs even at the lower dose (50 ppm) and shorter incubation period (18 h). Subtilisin protease- and lipase-based enzyme cleaning at 100 ppm and for 18 h contact time restored the hydrophobicity of the TFC RO surface to its virgin condition while physical cleaning alone resulted in a 50° increase in hydrophobicity. Moreover, at this optimum working condition, the Subtilisin protease- and lipase-based enzyme treatment of biofouled RO surface also restored the surface roughness measured with atomic force microscopy and the mass percentage of the chemical compositions on the TFC surface estimated with X-ray photoelectron spectroscopy to its virgin condition. This novel study will encourage the further development and application of enzymes to remove biofoulants on the RO surface without changing its surface properties. PMID:24329165

  11. Reduction of Precursors of Chlorination By-products in Drinking Water Using Fluidized-bed Biofilm Reactor at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    SHU-GUANG XIE; DONG-HUI WEN; DONG-WEN SHI; XIAO-YAN TANG

    2006-01-01

    Objective To investigate the reduction of chlorination by-products (CBPs) precursors using the fluidized-bed biofilm reactor (FBBR). Methods Reduction of total organic carbon (TOC), ultraviolet absorbance (UV254), trihalomethane (THM)formation potential (THMFP), haloacetic acid (HAA) formation potential (HAAFP), and ammonia in FBBR were evaluated in detail. Results The reduction of TOC or UV254 was low, on average 12.6% and 4.7%, respectively, while the reduction of THMFP and HAAFP was significant. The reduction of ammonia was 30%-40% even below 3℃, however, it could quickly rise to over 50% above 3℃. Conclusions The FBBR effectively reduces CBPs and ammonia in drinking water even at low temperature and seems to be a very promising and competitive drinking water reactor for polluted surface source waters, especially in China.

  12. Nitrogen removal from on-site treated anaerobic effluents using intermittently aerated moving bed biofilm reactors at low temperature.

    Science.gov (United States)

    Luostarinen, Sari; Luste, Sami; Valentín, Lara; Rintala, Jukka

    2006-05-01

    On-site post-treatment of anaerobically pre-treated dairy parlour wastewater (DPWWe; 10 degrees C) and mixture of kitchen waste and black water (BWKWe; 20 degrees C) was studied in moving bed biofilm reactors (MBBR). The focus was on removal of nitrogen and of residual chemical oxygen demand (COD). Moreover, the effect of intermittent aeration and continuous vs. sequencing batch operation was studied. All MBBRs removed 50-60% of nitrogen and 40-70% of total COD (CODt). Complete nitrification was achieved, but denitrification was restricted by lack of carbon. Nitrogen removal was achieved in a single reactor by applying intermittent aeration. Continuous and sequencing batch operation provided similar nitrogen and COD removal, wherefore simpler continuous feeding may be preferred for on-site applications. Combination of pre-treating upflow anaerobic sludge blanket (UASB) -septic tank and MBBR removed over 92% of CODt, 99% of biological oxygen demand (BOD7), and 65-70% of nitrogen. PMID:16647521

  13. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems.

    Science.gov (United States)

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Pantazi, Ypapanti; Andersen, Henrik R

    2015-09-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The activated sludge system was operated under low organic loading conditions. The moving bed biofilm reactor (MBBR) system consisted of two serially connected reactors filled with K3-biocarriers. It was either operated under low or high organic loading conditions. Target compounds were removed partially and with different rates in tested systems. For MBBR, increased loading resulted in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalized to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic. PMID:26093257

  14. New developments in small reactors

    International Nuclear Information System (INIS)

    During the fifty years since nuclear fission was discovered, nuclear energy has emerged to play an increasingly important role in meeting global energy needs. At the recent World Energy Conference in Montreal, 1989 September, experts agreed that nuclear power will continue to be an essential part of the future energy mix. The demand for economic and reliable energy sources is driven by the growth in the world's population and the essential role energy plays in industrial development. Global energy requirements, expected to double over the next 40 years, will seriously challenge suppliers in their ability to meet the demand. Ultimately, efficient energy utilization will become singularly important. Industrialization and economic development manifest themselves in urbanization. Urban dwellers consume significantly more energy per capita compared with their rural neighbours. Consequently, concentrated and environmentally acceptable energy sources, combined with efficient distribution systems, are now recognized as essential to meet urban energy demands. In considering the alternatives that will meet these requirements, nuclear energy qualifies as both a concentrated and environmentally benign source. Nuclear electricity generation is a mature technology that paves the way for other applications. If nuclear energy is to realize its full potential as a safe and cost-effective alternative to fossil fuels, applications beyond those that are currently being serviced by large, central nuclear power stations must be identified, and appropriately designed and sized reactors developed as an investment in the future. To meet this potential, new small reactor concepts are being developed to satisfy the expected energy demands, while also displaying characteristics that address current public concerns for providing minimal environmental impact. Concepts ranging in sized from 10 MW(t) to 1000 MW(t) are being pursued in a number of countries, including Canada, USA, UK, China, and

  15. Process Performance and Bacterial Community Structure Under Increasing Influent Disturbances in a Membrane-Aerated Biofilm Reactor.

    Science.gov (United States)

    Tian, Hailong; Yan, Yingchun; Chen, Yuewen; Wu, Xiaolei; Li, Baoan

    2016-02-01

    The membrane-aerated biofilm reactor (MABR) is a promising municipal wastewater treatment process. In this study, two cross-flow MABRs were constructed to explore the carbon and nitrogen removal performance and bacterial succession, along with changes of influent loading shock comprising flow velocity, COD, and NH4-N concentrations. Redundancy analysis revealed that the function of high flow velocity was mainly embodied in facilitating contaminants diffusion and biosorption rather than the success of overall bacterial populations (p > 0.05). In contrast, the influent NH4-N concentration contributed most to the variance of reactor efficiency and community structure (p < 0.05). Pyrosequencing results showed that Anaerolineae, and Beta- and Alphaproteobacteria were the dominant groups in biofilms for COD and NH4-N removal. Among the identified genera, Nitrosomonas and Nitrospira were the main nitrifiers, and Hyphomicrobium, Hydrogenophaga, and Rhodobacter were the key denitrifiers. Meanwhile, principal component analysis indicated that bacterial shift in MABR was probably the combination of stochastic and deterministic processes. PMID:26528534

  16. Efficiency influence of exogenous betaine on anaerobic sequencing batch biofilm reactor treating high salinity mustard tuber wastewater.

    Science.gov (United States)

    He, Qiang; Kong, Xiang-Juan; Chai, Hong-Xiang; Fan, Ming-Yu; Du, Jun

    2012-01-01

    When treating a composite mustard tuber wastewater with high concentrations of salt (about 20 g Cl(-) L(-1)) and organics (about 8000 mg L(-1) COD) by an anaerobic sequencing batch biofilm reactor (ASBBR) in winter, both high salinity and low temperature will inhibit the activity of anaerobic microorganisms and lead to low treatment efficiency. To solve this problem, betaine was added to the influent to improve the activity of the anaerobic sludge, and an experimental study was carried to investigate the influence of betaine on treating high salinity mustard tuber wastewater by the ASBBR. The results show that, when using anaerobic acclimated sludge in the ASBBR, and controlling biofilm density at 50% and water temperature at 8-12 degrees C, the treatment efficiency of the reactor could be improved by adding the betaine at different concentrations. The efficiency reached the highest when the optimal dosage ofbetaine was 0.5 mmol L(-1). The average effluent COD, after stable acclimation, was 4461 mg L(-1). Relative to ASBBR without adding betaine, the activity of the sludge increased significantly. Meanwhile, the dehydrogenase activity of anaerobic microorganisms and the COD removal efficiency were increased by 18.6% and 18.1%, respectively. PMID:22988630

  17. Bioreduction of para-chloronitrobenzene in drinking water using a continuous stirred hydrogen-based hollow fiber membrane biofilm reactor

    International Nuclear Information System (INIS)

    Highlights: → We designed a novel hollow fiber membrane biofilm reactor for p-CNB removal. → Biotransformation pathway of p-CNB in the reactor was investigated in this study. → Nitrate and sulfate competed more strongly for hydrogen than p-CNB. → This reactor achieved high removal efficiency and hydrogen utilization efficiency. - Abstract: para-Chloronitrobenzene (p-CNB) is particularly harmful and persistent in the environment and is one of the priority pollutants. A feasible degradation pathway for p-CNB is bioreduction under anaerobic conditions. Bioreduction of p-CNB using a hydrogen-based hollow fiber membrane biofilm reactor (HFMBfR) was investigated in the present study. The experiment results revealed that p-CNB was firstly reduced to para-chloraniline (p-CAN) as an intermediate and then reduced to aniline that involves nitro reduction and reductive dechlorination with H2 as the electron donor. The HFMBfR had reduced p-CNB to a major extent with a maximum removal percentage of 99.3% at an influent p-CNB concentration of 2 mg/L and a hydraulic residence time of 4.8 h, which corresponded to a p-CNB flux of 0.058 g/m2 d. The H2 availability, p-CNB loading, and the presence of competing electron acceptors affected the p-CNB reduction. Flux analysis indicated that the reduction of p-CNB and p-CAN could consume fewer electrons than that of nitrate and sulfate. The HFMBfR had high average hydrogen utilization efficiencies at different steady states in this experiment, with a maximum efficiency at 98.2%.

  18. Characterizing temporal development of biofilm porosity using artificial neural networks.

    Science.gov (United States)

    Veluchamy, Raaja Raajan Angathevar; Beyenal, Haluk; Lewandowski, Zbigniew

    2008-01-01

    We used artificial neural networks (ANN) to compute parameters characterising biofilm structure from biofilm images and to interpolate a limited number of experimental data characterising the effects of nutrient concentration and flow velocity on the areal porosity of biofilms. ANN were trained using a set of experimental data characterising structural parameters of biofilms of Pseudomonas aeruginosa (ATCC #700829), Pseudomonas fluorescens (ATCC #700830) and Klebsiella pneumoniae (ATCC #700831) for various flow velocities and glucose concentrations. We used 80% of the data to train ANN and 10% of the data to validate the results, which is routinely carried out as a countermeasure against overtraining. Trained ANN were used to interpolate into the data set and evaluate the missing 10% of the data. To compare ANN accuracy in evaluating the missing data with the accuracies achieved using other interpolation algorithms, we used spline, cubic, linear and nearest-neighbour interpolation algorithms to evaluate the missing data. ANN estimates were consistently closer to the experimental data than the estimates made using the other methods. PMID:18587172

  19. Development of Spatial Distribution Patterns by Biofilm Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Hansen, Susse Kirkelund; Bak Christensen, Bjarke;

    2015-01-01

    Confined spatial patterns of microbial distribution are prevalent in nature, such as in microbial mats, soil communities, and water stream biofilms. The symbiotic two-species consortium of Pseudomonas putida and Acinetobacter sp. C6, originally isolated from a creosote-polluted aquifer, has evolved......, as well as the ecology of engineered communities that have the potential for enhanced and sustainable bioprocessing capacity....

  20. Comparison of waste water treatment between completely mixed and fluidised bed reactor; development and structure of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Toman, M.; Mejac, B.

    1988-08-01

    The aerobic biological treatment of waste water from production of semisynthetic antibiotics in a completely mixed reactor and in a fluidised bed reactor was studied. The formation and development of new biomass on the sand of a fluidised bed was observed, so that differences in the structure of organisms of the concomitant biocenosis could be detected. In a fluidised bed reactor the same quality of treatednwater was gained on account of a 4-5 times higher volumetric and hydraulic loading as it was the case with a conventional activated sludge plant. The biocenosis of the fluidised bed was abundant in individua and species. The biofilm of the sand depended on substrate degradation rate as well as on rubbing among the sand particles. An optimal biofilm developed on the sand of a fluidised bed reactor 10 to 15 days after the experiment had began, and that condition remained unchanged as the experiment continued.

  1. Clustering of Pseudomonas aeruginosa transcriptomes from planktonic cultures, developing and mature biofilms reveals distinct expression profiles

    Directory of Open Access Journals (Sweden)

    Saqi Mansoor

    2006-06-01

    Full Text Available Abstract Background Pseudomonas aeruginosa is a genetically complex bacterium which can adopt and switch between a free-living or biofilm lifestyle, a versatility that enables it to thrive in many different environments and contributes to its success as a human pathogen. Results Transcriptomes derived from growth states relevant to the lifestyle of P. aeruginosa were clustered using three different methods (K-means, K-means spectral and hierarchical clustering. The culture conditions used for this study were; biofilms incubated for 8, 14, 24 and 48 hrs, and planktonic culture (logarithmic and stationary phase. This cluster analysis revealed the existence and provided a clear illustration of distinct expression profiles present in the dataset. Moreover, it gave an insight into which genes are up-regulated in planktonic, developing biofilm and confluent biofilm states. In addition, this analysis confirmed the contribution of quorum sensing (QS and RpoS regulated genes to the biofilm mode of growth, and enabled the identification of a 60.69 Kbp region of the genome associated with stationary phase growth (stationary phase planktonic culture and confluent biofilms. Conclusion This is the first study to use clustering to separate a large P. aeruginosa microarray dataset consisting of transcriptomes obtained from diverse conditions relevant to its growth, into different expression profiles. These distinct expression profiles not only reveal novel aspects of P. aeruginosa gene expression but also provide a growth specific transcriptomic reference dataset for the research community.

  2. Effect of Particulate Contaminants on the Development of Biofilms at Air/Water Interfaces.

    Science.gov (United States)

    Zhang, Zhenhuan; Christopher, Gordon

    2016-03-22

    The development of biofilms at air/water or oil/water interfaces has important ramifications on several applications, but it has received less attention than biofilm formation on solid surfaces. A key difference between the growth of biofilms on solid surfaces versus liquid interfaces is the range of complicated boundary conditions the liquid interface can create that may affect bacteria, as they adsorb onto and grow on the interface. This situation is exacerbated by the existence of complex interfaces in which interfacially adsorbed components can even more greatly affect interfacial boundary conditions. In this work, we present evidence as to how particle-laden interfaces impact biofilm growth at an air/water interface. We find that particles can enhance the rate of growth and final strength of biofilms at liquid interfaces by providing sites of increased adhesive strength for bacteria. The increased adhesion stems from creating localized areas of hydrophobicity that protrude in the water phase and provide sites where bacteria preferentially adhere. This mechanism is found to be primarily controlled by particle composition, with particle size providing a secondary effect. This increased adhesion through interfacial conditions creates biofilms with properties similar to those observed when adhesion is increased through biological means. Because of the generally understood ubiquity of increased bacteria attachment to hydrophobic surfaces, this result has general applicability to pellicle formation for many pellicle-forming bacteria. PMID:26943272

  3. Modeling bacterial attachment to surfaces as an early stage of biofilm development.

    Science.gov (United States)

    El Moustaid, Fadoua; Eladdadi, Amina; Uys, Lafras

    2013-06-01

    Biofilms are present in all natural, medical and industrial surroundings where bacteria live. Biofilm formation is a key factor in the growth and transport of both beneficial and harmful bacteria. While much is known about the later stages of biofilm formation, less is known about its initiation which is an important first step in the biofilm formation. In this paper, we develop a non-linear system of partial differential equations of Keller-Segel type model in one-dimensional space, which couples the dynamics of bacterial movement to that of the sensing molecules. In this case, bacteria perform a biased random walk towards the sensing molecules. We derive the boundary conditions of the adhesion of bacteria to a surface using zero-Dirichlet boundary conditions, while the equation describing sensing molecules at the interface needed particular conditions to be set. The numerical results show the profile of bacteria within the space and the time evolution of the density within the free-space and on the surface. Testing different parameter values indicate that significant amount of sensing molecules present on the surface leads to a faster bacterial movement toward the surface which is the first step of biofilm initiation. Our work gives rise to results that agree with the biological description of the early stages of biofilm formation. PMID:23906151

  4. 移动床生物膜反应器污水处理技术简介%Introduction of the Mobile Bed Biofilm Reactor for Wastewater Treatment

    Institute of Scientific and Technical Information of China (English)

    詹志薇

    2011-01-01

    Mobile bed biofilm reactor is novel wastewater treatment process.It overcomes the disadvantages of conventional activated sludge process and fix bed biofilm processes.However,the technology is not be widely known yet.Hence,the mechanism,research status,applications of mobile bed biofilm reactor were discussed in the paper.%简述了移动床生物膜反应器的工艺原理和特点,详细介绍了国内外移动床生物膜反应器的研究现状,最后提出移动床生物膜反应器在实际工程应用和理论研究中的发展趋势。

  5. Biodegradation of phenol with chromium(VI) reduction in an anaerobic fixed-biofilm process-Kinetic model and reactor performance

    International Nuclear Information System (INIS)

    A mathematical model system was derived to describe the simultaneous removal of phenol biodegradation with chromium(VI) reduction in an anaerobic fixed-biofilm reactor. The model system incorporates diffusive mass transport and double Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to validate the kinetic model system. Batch kinetic tests were conducted independently to evaluate the biokinetic parameters used in the model simulation. The removal efficiencies of phenol and chromium(VI) in an anaerobic fixed-biofilm process were approximately 980 mg/g and 910 mg/g, respectively, under a steady-state condition. In the steady state, model-predicted biofilm thickness reached up to 350 μm and suspended cells in the effluent were 85 mg cell/l. The experimental results agree closely with the results of the model simulations.

  6. Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Franck, Stephanie; Gülay, Arda;

    2014-01-01

    (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r...... reduction of the NOB Nitrospira and Nitrobacter and a 10-fold increase in AnAOB numbers. The study of biofilm sections with relevant 16S rRNA fluorescent probes revealed strongly stratified biofilm structures fostering aerobic ammonium oxidizing bacteria (AOB) in biofilm areas close to the membrane surface......-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal....

  7. Can those organic micro-pollutants that are recalcitrant in activated sludge treatment be removed from wastewater by biofilm reactors (slow sand filters)?

    Science.gov (United States)

    Escolà Casas, Mònica; Bester, Kai

    2015-02-15

    The degradation of seven compounds which are usually recalcitrant in classical activated sludge treatment (e.g., diclofenac, propranolol, iopromide, iohexol, iomeprol tebuconazole and propiconazole) was studied in a biofilm reactor (slow sand filtration). This reactor was used to treat real effluent-wastewater at different flow rates (hydraulic loadings) under aerobic conditions so removal and degradation kinetics of these recalcitrant compounds were calculated. With the hydraulic loading rate of 0.012 m(3)m(2)h(-1) the reactor removed 41, 94, 58, 57 and 85% of diclofenac, propranolol, iopromide, iohexol and iomeprol respectively. For these compounds the removal efficiency was dependent on hydraulic residence-times. Only 59 and 21% of the incoming tebuconazole and propiconazole respectively were removed but their removal did not depend on hydraulic residence time. Biofilm reactors are thus efficient in removing micro-pollutants and could be considered as an option for advanced treatment in small wastewater treatment plants. PMID:25460965

  8. The Role of Sucrose in the Development of Oral Biofilm in a Simulated Mouth System

    Directory of Open Access Journals (Sweden)

    Zubaidah H. Abdul Rahim

    2006-01-01

    Full Text Available The development of oral biofilm consisting of early settlers and late settlers in the presence and absence of sucrose using a simulated mouth model was investigated. The experiments were carried out by growing the early settlers’ biofilm consisting of Strep. mitis and Strep. sanguinis and late settlers’ biofilm of Strep. mutans in the simulated mouth system. Experiments using three different nutrient conditions (A, B and C were carried out. In A, sterile saliva was used as the nutrient source in which the early settlers were suspended and pumped into the simulated mouth system and allowed to grow for 24 hrs. In B, 1% of BHI broth was added to the sterile saliva three times a day at 6 hrs interval to demonstrate the effect of glucose on the development of the biofilms. In C, the 1% BHI was supplemented with 1% sucrose in order to show the effect of glucose in the presence of sucrose on the development of the biofilm. The experiments were subsequently repeated with the late settlers. In all the experiments, A serves as the control where the nutrient source is minimal. The data collected were analyzed using Student t-test. From the results obtained, it was observed that both glucose and sucrose enhanced the development of early and late settlers’ biofilms. The growth of late settlers’ biofilm however, was found to be significantly higher in the presence of sucrose (93x106 CFU mL-1 compared to glucose (66x106 CFU mL-1 with a p value <0.05.

  9. Software development for research reactors

    International Nuclear Information System (INIS)

    The Texas A and M University Nuclear Science Center, in a program jointly sponsored with the International Atomic Energy Agency, is developing a series of computer software programs of use at research reactor facilities. The programs cover a wide range of topics including activation and shielding calculations, control rod calibrations, power calorimetrics, and fuel inventory including burnup. Many of the programs are modified and improved versions of programs already in use at the NSC that ran on outdated computing equipment. All of the new versions were written in Fortran77 on the NSC's new TI Pro microcomputer and are IBM-compatible. This paper describes the development and translation efforts in preparing the programs for use by other facilities, and gives an overview of the aim of the development effort. A brief description of each program that has been or is to be written is given including the required inputs and the resulting outputs. This paper also addresses the original needs that brought about the development program and the benefits to facility operations that each program provides. The programs discussed are available to interested parties in a hard-copy listing as requested. (author)

  10. Analysis of the Microbial Community in an Acidic Hollow-Fiber Membrane Biofilm Reactor (Hf-MBfR Used for the Biological Conversion of Carbon Dioxide to Methane.

    Directory of Open Access Journals (Sweden)

    Hyun Chul Shin

    Full Text Available Hydrogenotrophic methanogens can use gaseous substrates, such as H2 and CO2, in CH4 production. H2 gas is used to reduce CO2. We have successfully operated a hollow-fiber membrane biofilm reactor (Hf-MBfR for stable and continuous CH4 production from CO2 and H2. CO2 and H2 were diffused into the culture medium through the membrane without bubble formation in the Hf-MBfR, which was operated at pH 4.5-5.5 over 70 days. Focusing on the presence of hydrogenotrophic methanogens, we analyzed the structure of the microbial community in the reactor. Denaturing gradient gel electrophoresis (DGGE was conducted with bacterial and archaeal 16S rDNA primers. Real-time qPCR was used to track changes in the community composition of methanogens over the course of operation. Finally, the microbial community and its diversity at the time of maximum CH4 production were analyzed by pyrosequencing methods. Genus Methanobacterium, related to hydrogenotrophic methanogens, dominated the microbial community, but acetate consumption by bacteria, such as unclassified Clostridium sp., restricted the development of acetoclastic methanogens in the acidic CH4 production process. The results show that acidic operation of a CH4 production reactor without any pH adjustment inhibited acetogenic growth and enriched the hydrogenotrophic methanogens, decreasing the growth of acetoclastic methanogens.

  11. Application of response surface methodology to optimize the operational parameters for enhanced removal efficiency of organic matter and nitrogen: moving bed biofilm reactor.

    Science.gov (United States)

    Barwal, Anjali; Chaudhary, Rubina

    2016-05-01

    An attempt of response surface methodology (RSM) has been made for more effective utilization and optimization for considerable reduction of operational conditions such as reaction time, aeration time, energy consumption, etc. for municipal wastewater treatment process using moving bed biofilm reactor (MBBR). A mathematical-statistical model was developed for the second-order response surface through the fit of a polynomial function and a central composite design (CCD) in the form of a full factorial design. CCD was employed to assess the interactive effects of the three main independent operational parameters, including biocarrier filling rate (0-70 %), aeration rate (0.21-0.42 m(3) h(-1)), and reactor run time (1-15 days), on the removal efficiency of chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total Kjeldahl nitrogen (TKN). Analysis of variance expressed a high coefficient of determination (R (2) = 0.84-0.95), thereby indicating that the model is significant. Using a desirability function for the highest COD (93 %), BOD (96 %), and TKN (69 %) removal, the optimum carrier filling rate, aeration rate, and reactor run time were identified to be 40 %, 0.21 m(3) h(-1), and 7 days, respectively. It shows that RSM can be a suitable method to optimize the operational parameters of MBBR with enhanced removal efficiency and less power consumption. PMID:26857006

  12. The catabolite repression control protein Crc plays a role in the development of antimicrobial-tolerant subpopulations in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Zhang, Lianbo; Chiang, Wen-Chi; Gao, Qingguo;

    2012-01-01

    Bacteria form complex surface-attached biofilm communities in nature. Biofilm cells differentiate into subpopulations which display tolerance towards antimicrobial agents. However, the signal transduction pathways regulating subpopulation differentiation in biofilms are largely unelucidated. In t....... In the present study, we show that the catabolite repression control protein Crc regulates the metabolic state of Pseudomonas aeruginosa cells in biofilms, and plays an important role in the development of antimicrobial-tolerant subpopulations in P. aeruginosa biofilms....

  13. Effects of gene augmentation on the removal of 2,4-dichlorophenoxyacetic acid in a biofilm reactor under different scales and substrate conditions

    International Nuclear Information System (INIS)

    With a conjugative plasmid pJP4 carrying strain as the donor, two bioaugmentation experiments were conducted in a microcosm biofilm reactor with 2,4-D as the sole carbon source operated in fed-batch mode, and an enlarged lab-scale sequence batch biofilm reactor with mixed carbon sources of 2,4-D and other easily biodegradable compounds, respectively. In the microcosm study under sole carbon source condition, bioaugmentation led to a persistently increased 2,4-D degradation rate in the five operation cycles with enhancement of 13-64%. For the enlarged lab-scale bioaugmentation experiment under mixed carbon source conditions, no enhancement in 2,4-D removal could be observed during start-up period. After a period of operation, biofilm samples from the bioaugmented reactor demonstrated a stronger degradation capacity than the control and showed the presence of a large number of transconjugants. This study indicates that bioaugmentation based on plasmid horizontal transfer is a feasible strategy to establish functional microbial community in a biofilm reactor, and the strong selective pressure of 2,4-D existing alone and persistently was more favorable for the success of gene augmentation.

  14. Tracking the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors operated at different COD/N ratios.

    Science.gov (United States)

    Bassin, J P; Abbas, B; Vilela, C L S; Kleerebezem, R; Muyzer, G; Rosado, A S; van Loosdrecht, M C M; Dezotti, M

    2015-09-01

    In this study, the impact of COD/N ratio and feeding regime on the dynamics of heterotrophs and nitrifiers in moving-bed biofilm reactors was addressed. Based on DGGE analysis of 16S rRNA genes, the influent COD was found to be the main factor determining the overall bacterial diversity. The amoA-gene-based analysis suggested that the dynamic behavior of the substrate in continuous and pulse-feeding reactors influenced the selection of specific ammonium-oxidizing bacteria (AOB) strains. Furthermore, AOB diversity was directly related to the applied COD/N ratio and ammonium-nitrogen load. Maximum specific ammonium oxidation rates observed under non-substrate-limiting conditions were observed to be proportional to the fraction of nitrifiers within the bacterial community. FISH analysis revealed that Nitrosomonas genus dominated the AOB community in all reactors. Moreover, Nitrospira was found to be the only nitrite-oxidizing bacteria (NOB) in the fully autotrophic system, whereas Nitrobacter represented the dominant NOB genus in the organic carbon-fed reactors. PMID:26025351

  15. Pseudomonas aeruginosa lipopolysaccharide inhibits Candida albicans hyphae formation and alters gene expression during biofilm development.

    Science.gov (United States)

    Bandara, H M H N; K Cheung, B P; Watt, R M; Jin, L J; Samaranayake, L P

    2013-02-01

    Elucidation of bacterial and fungal interactions in multispecies biofilms will have major impacts on understanding the pathophysiology of infections. The objectives of this study were to (i) evaluate the effect of Pseudomonas aeruginosa lipopolysaccharide (LPS) on Candida albicans hyphal development and transcriptional regulation, (ii) investigate protein expression during biofilm formation, and (iii) propose likely molecular mechanisms for these interactions. The effect of LPS on C. albicans biofilms was assessed by XTT-reduction and growth curve assays, light microscopy, scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). Changes in candidal hypha-specific genes (HSGs) and transcription factor EFG1 expression were assessed by real-time polymerase chain reaction and two-dimensional gel electrophoresis, respectively. Proteome changes were examined by mass spectrometry. Both metabolic activities and growth rates of LPS-treated C. albicans biofilms were significantly lower (P yeasts in test biofilms compared with the controls. SEM and CLSM further confirmed these data. Significantly upregulated HSGs (at 48 h) and EFG1 (up to 48 h) were noted in the test biofilms (P < 0.05) but cAMP levels remained unaffected. Proteomic analysis showed suppression of candidal septicolysin-like protein, potential reductase-flavodoxin fragment, serine hydroxymethyltransferase, hypothetical proteins Cao19.10301(ATP7), CaO19.4716(GDH1), CaO19.11135(PGK1), CaO19.9877(HNT1) by P. aeruginosa LPS. Our data imply that bacterial LPS inhibit C. albicans biofilm formation and hyphal development. The P. aeruginosa LPS likely target glycolysis-associated mechanisms during candidal filamentation. PMID:23194472

  16. Possible inhibitory molecular mechanism of farnesol on the development of fluconazole resistance in Candida albicans biofilm.

    Science.gov (United States)

    Yu, Li-Hua; Wei, Xin; Ma, Ming; Chen, Xiao-Jun; Xu, Shuang-Bo

    2012-02-01

    Candida albicans biofilm infections are usually treated with azole antifungals such as fluconazole. However, the development of resistance to this drug in C. albicans biofilms is very common, especially in immunocompromised individuals. The upregulation of the sterol biosynthetic pathway gene ERG and the efflux pump genes CDR and MDR may contribute to this azole tolerance in Candida species. We hypothesize that farnesol, an endogenous quorum sensing molecule with possible antimicrobial properties which is also the precursor of ergosterols in C. albicans, may interfere with the development of fluconazole resistance in C. albicans biofilms. To test this hypothesis, MICs were compared and morphology changes were observed by confocal laser scanning microscopy (CLSM) for farnesol-treated and -untreated and fluconazole-resistant groups. The expression of possible target genes (ERG11, ERG25, ERG6, ERG5, ERG3, ERG1, MDR1, CDR1, and CDR2) in biofilms was analyzed by reverse transcription-PCR (RT-PCR) and quantitative PCR (qPCR) to investigate the molecular mechanisms of the inhibitory effects of farnesol. The results showed a decreased MIC of fluconazole and thinner biofilms for the farnesol-treated group, indicating that farnesol inhibited the development of fluconazole resistance. The sterol biosynthetic pathway may contribute to the inhibitory effects of farnesol, as the transcription levels of the ERG11, ERG25, ERG6, ERG3, and ERG1 genes decreased in the farnesol-treated group. PMID:22106223

  17. Mechanical systems development of integral reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Keun Bae; Chang, M. H.; Kim, J. I.; Choi, S.; Kim, K. S.; Kim, T. W.; Jeong, K. H.; Kim, J. H.; Kim, Y. W.; Lee, G. M.

    1997-07-01

    While Korean nuclear reactor strategy seems to remain focused on the large capacity power generation, it is expected that demand of small and medium size reactor will arise for multi-purpose applications such as small capacity power generation, co-generation and sea water desalination. This in mind, survey has been made on the worldwide small and medium integral reactors under development. Reviewed are their technical characteristics, development status, design features, application plans, etc. For the mechanical design scope of work, the structural concept compatible with the characteristics and requirements of integral reactor has been established. Types of major components were evaluated and selected. Functional and structural concept, equipment layout and supporting concept within the reactor pressure vessel have also been established. Preliminary mechanical design requirements were developed considering the reactor lifetime, operation conditions, and the expected loading combinations. To embody the concurrent design approach, recent CAD technology and team engineering concept were evaluated. (author). 31 refs.,16 tabs., 35 figs.

  18. Mechanical systems development of integral reactor

    International Nuclear Information System (INIS)

    While Korean nuclear reactor strategy seems to remain focused on the large capacity power generation, it is expected that demand of small and medium size reactor will arise for multi-purpose applications such as small capacity power generation, co-generation and sea water desalination. This in mind, survey has been made on the worldwide small and medium integral reactors under development. Reviewed are their technical characteristics, development status, design features, application plans, etc. For the mechanical design scope of work, the structural concept compatible with the characteristics and requirements of integral reactor has been established. Types of major components were evaluated and selected. Functional and structural concept, equipment layout and supporting concept within the reactor pressure vessel have also been established. Preliminary mechanical design requirements were developed considering the reactor lifetime, operation conditions, and the expected loading combinations. To embody the concurrent design approach, recent CAD technology and team engineering concept were evaluated. (author). 31 refs.,16 tabs., 35 figs

  19. Development and antimicrobial susceptibility studies of in vitro monomicrobial and polymicrobial biofilm models with Aspergillus fumigatus and Pseudomonas aeruginosa

    OpenAIRE

    Manavathu, Elias K.; Vager, Dora L; Vazquez, Jose A

    2014-01-01

    Background Mixed microbial infections of the respiratory tracts with P. aeruginosa and A. fumigatus capable of producing biofilms are commonly found in cystic fibrosis patients. The primary objective of this study was to develop an in vitro model for P. aeruginosa and A. fumigatus polymicrobial biofilm to study the efficacy of various antimicrobial drugs alone and in combinations against biofilm-embedded cells. Simultaneous static cocultures of P. aeruginosa and sporelings were used for the d...

  20. Development of integrated modular water reactor

    International Nuclear Information System (INIS)

    In order to adapt for environmental problem to reduce emission of greenhouse effect gas and develop a power generation plant with economical efficiency and small output, a number of R and Ds on small scale reactors have been progressed without any practice. The largest subject on the development consists in how cost of construction, operation and maintenance on the small scale reactors can be reduced to those of large scale ones by its specific technology. Therefore, if by adding wide simplification of apparatuses based on introduction of novel technology and added values specific to the small scale reactors, a business model on installing many small scale reactors can be established, a practicable feasibility of the small scale reactors valuable to introduction of actual scale machine will enable to be found. Authors have progressed development on a novel small scale reactor capable of flexibly corresponding to social needs for nuclear power generation. As a result, by integrating the reactor system and introducing self pressurisation and natural circulation as an innovative 300,000 kW output class small scale reactor, a plant concept reducing feasibility to occur any large scale accident to its ultimate limit together with planning wide simplification of apparatus could be established. The reactor is the titled integrated modular water reactor (IMR), and is at present under investigation on its formability confirmation and its concept design. Here were reported on plant concepts and characteristics of IMR, in this report. (G.K.)

  1. Microbial succession within an anaerobic sequencing batch biofilm reactor (ASBBR treating cane vinasse at 55ºC

    Directory of Open Access Journals (Sweden)

    Maria Magdalena Ferreira Ribas

    2009-08-01

    Full Text Available The aim of this work was to investigate the anaerobic biomass formation capable of treating vinasse from the production of sugar cane alcohol, which was evolved within an anaerobic sequencing batch biofilm reactor (ASBBR as immobilized biomass on cubes of polyurethane foam at the temperature of 55ºC. The reactor was inoculated with mesophilic granular sludge originally treating poultry slaughterhouse wastewater. The evolution of the biofilm in the polyurethane foam matrices was assessed during seven experimental phases which were thus characterized by the changes in the organic matter concentrations as COD (1.0 to 20.0 g/L. Biomass characterization proceeded with the examination of sludge samples under optical and scanning electron microscopy. The reactor showed high microbial morphological diversity along the trial. The predominance of Methanosaeta-like cells was observed up to the organic load of 2.5 gCOD/L.d. On the other hand, Methanosarcinalike microorganisms were the predominant archaeal population within the foam matrices at high organic loading ratios above 3.3 gCOD/L.d. This was suggested to be associated to a higher specific rate of acetate consumption by the later organisms.Este trabalho investigou a formação de um biofilme anaeróbio capaz de tratar vinhaça da produção de álcool de cana-de-açúcar, que evoluiu dentro de um reator operado em bateladas seqüenciais com biofilme (ASBBR tendo a biomassa imobilizada em cubos de espuma de poliuretano na temperatura de 55ºC. O reator foi inoculado com lodo granular mesofílico tratando água residuária de abatedouro de aves. A evolução do biofilme nas matrizes de espuma de poliuretano foi observada durante sete fases experimentais que foram caracterizadas por mudanças nas concentrações de matéria orgânica como DQO (1,0 a 20,0 g/L. A caracterização da biomassa foi feita por exames de amostras do lodo em microscopia ótica e eletrônica de varredura. O reator apresentou

  2. Role of a Tannerella forsythia exopolysaccharide synthesis operon in biofilm development.

    Science.gov (United States)

    Honma, Kiyonobu; Inagaki, Satoru; Okuda, Katsuji; Kuramitsu, Howard K; Sharma, Ashu

    2007-04-01

    Tannerella forsythia is a Gram-negative oral anaerobe implicated in the development of periodontitis, a chronic inflammatory disease induced by bacterial infections which leads to tooth loss if untreated. Since biofilms formed by periodontal bacteria are considered important in disease progression and pose difficulties in treatment, we sought to investigate the underlying mechanisms of T. forsythia biofilm formation. This was carried out by screening random insertion mutants of T. forsythia for alterations in biofilm development. This approach lead to the identification of an operon involved in exopolysaccharide (EPS) synthesis. An isogenic mutant of one of the genes, wecC, contained within the operon was constructed. The isogenic wecC mutant showed increased ability to form biofilms as compared to the parent strain. The wecC mutant also formed aggregated microcolonies and showed increased cell-surface associated hydrophobicity as compared to the parent strain. Moreover, biochemical characterization of the wecC mutant indicated that glycosylation of surface glycoproteins was reduced. Therefore, our results suggest that the wecC operon is associated with glycosylation of surface-glycoprotein expression and likely plays an inhibitory role in T. forsythia biofilm formation. PMID:17363213

  3. Simultaneous ammonia and nitrate removal in an airlift reactor using poly(butylene succinate) as carbon source and biofilm carrier.

    Science.gov (United States)

    Ruan, Yun-Jie; Deng, Ya-Le; Guo, Xi-Shan; Timmons, Michael B; Lu, Hui-Feng; Han, Zhi-Ying; Ye, Zhang-Ying; Shi, Ming-Ming; Zhu, Song-Ming

    2016-09-01

    In this study, an airlift inner-loop sequencing batch reactor using poly(butylene succinate) as the biofilm carrier and carbon source was operated under an alternant aerobic/anoxic strategy for nitrogen removal in recirculating aquaculture system. The average TAN and nitrate removal rates of 47.35±15.62gNH4-Nm(-3)d(-1) and 0.64±0.14kgNO3-Nm(-3)d(-1) were achieved with no obvious nitrite accumulation (0.70±0.76mg/L) and the dissolved organic carbon in effluents was maintained at 148.38±39.06mg/L. Besides, the activities of dissimilatory nitrate reduction to ammonium and sulfate reduction activities were successfully inhibited. The proteome KEGG analysis illustrated that ammonia might be removed through heterotrophic nitrification, while the activities of nitrate and nitrite reductases were enhanced through aeration treatment. The microbial community analysis revealed that denitrifiers of Azoarcus and Simplicispira occupied the dominate abundance which accounted for the high nitrate removal performance. Overall, this study broadened our understanding of simultaneous nitrification and denitrification using biodegradable material as biofilm carrier. PMID:27343453

  4. Reactor containment research and development

    Energy Technology Data Exchange (ETDEWEB)

    Weil, N. A.

    1963-06-15

    An outline is given of containment concepts, sources and release rates of energy, responses of containment structures, effects of projectiles, and leakage rates of radioisotopes, with particular regard to major reactor accidents. (T.F.H.)

  5. Advanced research reactor fuel development

    International Nuclear Information System (INIS)

    The fabrication technology of the U3Si fuel dispersed in aluminum for the localization of HANARO driver fuel has been launches. The increase of production yield of LEU metal, the establishment of measurement method of homogeneity, and electron beam welding process were performed. Irradiation test under normal operation condition, had been carried out and any clues of the fuel assembly breakdown was not detected. The 2nd test fuel assembly has been irradiated at HANARO reactor since 17th June 1999. The quality assurance system has been re-established and the eddy current test technique has been developed. The irradiation test for U3Si2 dispersed fuels at HANARO reactor has been carried out in order to compare the in-pile performance of between the two types of U3Si2 fuels, prepared by both the atomization and comminution processes. KAERI has also conducted all safety-related works such as the design and the fabrication of irradiation rig, the analysis of irradiation behavior, thermal hydraulic characteristics, stress analysis for irradiation rig, and thermal analysis fuel plate, for the mini-plate prepared by international research cooperation being irradiated safely at HANARO. Pressure drop test, vibration test and endurance test were performed. The characterization on powders of U-(5.4 ∼ 10 wt%) Mo alloy depending on Mo content prepared by rotating disk centrifugal atomization process was carried out in order to investigate the phase stability of the atomized U-Mo alloy system. The γ-U phase stability and the thermal compatibility of atomized U-16at.%Mo and U-14at.%Mo-2at.%X(: Ru, Os) dispersion fuel meats at an elevated temperature have been investigated. The volume increases of U-Mo compatibility specimens were almost the same as or smaller than those of U3Si2. However the atomized alloy fuel exhibited a better irradiation performance than the comminuted alloy. The RERTR-3 irradiation test of nano-plates will be conducted in the Advanced Test Reactor(ATR). 49

  6. Advanced research reactor fuel development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Kyu; Pak, H. D.; Kim, K. H. [and others

    2000-05-01

    The fabrication technology of the U{sub 3}Si fuel dispersed in aluminum for the localization of HANARO driver fuel has been launches. The increase of production yield of LEU metal, the establishment of measurement method of homogeneity, and electron beam welding process were performed. Irradiation test under normal operation condition, had been carried out and any clues of the fuel assembly breakdown was not detected. The 2nd test fuel assembly has been irradiated at HANARO reactor since 17th June 1999. The quality assurance system has been re-established and the eddy current test technique has been developed. The irradiation test for U{sub 3}Si{sub 2} dispersed fuels at HANARO reactor has been carried out in order to compare the in-pile performance of between the two types of U{sub 3}Si{sub 2} fuels, prepared by both the atomization and comminution processes. KAERI has also conducted all safety-related works such as the design and the fabrication of irradiation rig, the analysis of irradiation behavior, thermal hydraulic characteristics, stress analysis for irradiation rig, and thermal analysis fuel plate, for the mini-plate prepared by international research cooperation being irradiated safely at HANARO. Pressure drop test, vibration test and endurance test were performed. The characterization on powders of U-(5.4 {approx} 10 wt%) Mo alloy depending on Mo content prepared by rotating disk centrifugal atomization process was carried out in order to investigate the phase stability of the atomized U-Mo alloy system. The {gamma}-U phase stability and the thermal compatibility of atomized U-16at.%Mo and U-14at.%Mo-2at.%X(: Ru, Os) dispersion fuel meats at an elevated temperature have been investigated. The volume increases of U-Mo compatibility specimens were almost the same as or smaller than those of U{sub 3}Si{sub 2}. However the atomized alloy fuel exhibited a better irradiation performance than the comminuted alloy. The RERTR-3 irradiation test of nano

  7. De-mercurization of wastewater by Bacillus cereus (JUBT1): Growth kinetics, biofilm reactor study and field emission scanning electron microscopic analysis

    International Nuclear Information System (INIS)

    Graphical abstract: The assembly of biofilm reactor, based on attached growth of Bacillus cereus (JUBT1) on rice husk packing, and an activated carbon filter has been able to ensure the removal of mercury up to near-zero level. Highlights: → A new mercury resistant bacterial strain, Bacillus cereus (JUBT1), has been isolated. → Growth kinetics has been determined. → Biofilm reactor using attached growth of bacteria ensures near-zero level of mercury. → Confinement of mercury is confirmed through energy dispersive spectrometric analysis. - Abstract: Removal of mercuric ions by a mercury resistant bacteria, called Bacillus cereus (JUBT1), isolated from the sludge of a local chlor-alkali industry, has been investigated. Growth kinetics of the bacteria have been determined. A multiplicative, non-competitive relationship between sucrose and mercury ions has been observed with respect to bacterial growth. A combination of biofilm reactor, using attached growth of Bacillus cereus (JUBT1) on rice husk packing, and an activated carbon filter has been able to ensure the removal of mercury up to near-zero level. Energy dispersive spectrometry analysis of biofilm and the activated carbon has proved the transformation of Hg2+ to Hg0 and its confinement in the system.

  8. De-mercurization of wastewater by Bacillus cereus (JUBT1): Growth kinetics, biofilm reactor study and field emission scanning electron microscopic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ghoshal, Sanjukta; Bhattacharya, Pinaki [Chemical Engineering Department, Jadavpur University Kolkata 700 032, West Bengal (India); Chowdhury, Ranjana, E-mail: ranjana.juchem@gmail.com [Chemical Engineering Department, Jadavpur University Kolkata 700 032, West Bengal (India)

    2011-10-30

    Graphical abstract: The assembly of biofilm reactor, based on attached growth of Bacillus cereus (JUBT1) on rice husk packing, and an activated carbon filter has been able to ensure the removal of mercury up to near-zero level. Highlights: {yields} A new mercury resistant bacterial strain, Bacillus cereus (JUBT1), has been isolated. {yields} Growth kinetics has been determined. {yields} Biofilm reactor using attached growth of bacteria ensures near-zero level of mercury. {yields} Confinement of mercury is confirmed through energy dispersive spectrometric analysis. - Abstract: Removal of mercuric ions by a mercury resistant bacteria, called Bacillus cereus (JUBT1), isolated from the sludge of a local chlor-alkali industry, has been investigated. Growth kinetics of the bacteria have been determined. A multiplicative, non-competitive relationship between sucrose and mercury ions has been observed with respect to bacterial growth. A combination of biofilm reactor, using attached growth of Bacillus cereus (JUBT1) on rice husk packing, and an activated carbon filter has been able to ensure the removal of mercury up to near-zero level. Energy dispersive spectrometry analysis of biofilm and the activated carbon has proved the transformation of Hg{sup 2+} to Hg{sup 0} and its confinement in the system.

  9. Can those organic micro-pollutants that are recalcitrant in activated sludge treatment be removed from wastewater by biofilm reactors (slow sand filters)?

    International Nuclear Information System (INIS)

    The degradation of seven compounds which are usually recalcitrant in classical activated sludge treatment (e.g., diclofenac, propranolol, iopromide, iohexol, iomeprol tebuconazole and propiconazole) was studied in a biofilm reactor (slow sand filtration). This reactor was used to treat real effluent-wastewater at different flow rates (hydraulic loadings) under aerobic conditions so removal and degradation kinetics of these recalcitrant compounds were calculated. With the hydraulic loading rate of 0.012 m3 m2 h−1 the reactor removed 41, 94, 58, 57 and 85% of diclofenac, propranolol, iopromide, iohexol and iomeprol respectively. For these compounds the removal efficiency was dependent on hydraulic residence-times. Only 59 and 21% of the incoming tebuconazole and propiconazole respectively were removed but their removal did not depend on hydraulic residence time. Biofilm reactors are thus efficient in removing micro-pollutants and could be considered as an option for advanced treatment in small wastewater treatment plants. - Highlights: • A biofilm reactor (biofilter) can remove micro-pollutants from WWTP effluent. • Sorption could be excluded as the dominant removal mechanism. • Biodegradation was responsible for removing seven compounds. • The removal efficiency was usually proportional to the hydraulic residence-time. • Single first-order removal rates apply for most compounds

  10. Can those organic micro-pollutants that are recalcitrant in activated sludge treatment be removed from wastewater by biofilm reactors (slow sand filters)?

    Energy Technology Data Exchange (ETDEWEB)

    Escolà Casas, Mònica; Bester, Kai, E-mail: kb@dmu.dk

    2015-02-15

    The degradation of seven compounds which are usually recalcitrant in classical activated sludge treatment (e.g., diclofenac, propranolol, iopromide, iohexol, iomeprol tebuconazole and propiconazole) was studied in a biofilm reactor (slow sand filtration). This reactor was used to treat real effluent-wastewater at different flow rates (hydraulic loadings) under aerobic conditions so removal and degradation kinetics of these recalcitrant compounds were calculated. With the hydraulic loading rate of 0.012 m{sup 3} m{sup 2} h{sup −1} the reactor removed 41, 94, 58, 57 and 85% of diclofenac, propranolol, iopromide, iohexol and iomeprol respectively. For these compounds the removal efficiency was dependent on hydraulic residence-times. Only 59 and 21% of the incoming tebuconazole and propiconazole respectively were removed but their removal did not depend on hydraulic residence time. Biofilm reactors are thus efficient in removing micro-pollutants and could be considered as an option for advanced treatment in small wastewater treatment plants. - Highlights: • A biofilm reactor (biofilter) can remove micro-pollutants from WWTP effluent. • Sorption could be excluded as the dominant removal mechanism. • Biodegradation was responsible for removing seven compounds. • The removal efficiency was usually proportional to the hydraulic residence-time. • Single first-order removal rates apply for most compounds.

  11. Bioelectrochemical Reduction of Fe(II)EDTA-NO in a Biofilm Electrode Reactor: Performance, Mechanism, and Kinetics.

    Science.gov (United States)

    Xia, Yinfeng; Zhao, Jingkai; Li, Meifang; Zhang, Shihan; Li, Sujing; Li, Wei

    2016-04-01

    A biofilm electrode reactor (BER) is proposed to effectively regenerate Fe(II)EDTA, a solvent for NOx removal from flue gas, from Fe(II)EDTA-NO, a spent solution. In this study, the performance, mechanism, and kinetics of the bioelectrochemical reduction of Fe(II)EDTA-NO were investigated. The pathways of Fe(II)EDTA-NO reduction were investigated via determination of nitrogen element balance in the BER and an abiotic electrode reactor. The experimental results indicate that the chelated NO (Fe(II)EDTA-NO) is reduced to N2 with N2O as an intermediate. However, the oxidation of NO occurred in the absence of Fe(II)EDTA in abiotic reactors. Furthermore, the accumulation of N2O was suppressed with the help of electricity. The preponderant electron donor for reduction of Fe(II)EDTA-NO was also confirmed via analysis of the electron conservation. About 87% of Fe(II)EDTA-NO was reduced using Fe(II)EDTA as the electron donor in the presence of both glucose and cathode electrons while the cathode electrons were utilized for the reduction of Fe(III)EDTA to Fe(II)EDTA. Michaelis-Menten kinetic constants of bioelectrochemical reduction of Fe(II)EDTA-NO were also calculated. The maximum reduction rate of Fe(II)EDTA-NO was 13.04 mol m(-3) h(-1), which is 50% higher than that in a conventional biofilter. PMID:26900881

  12. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment.

    Science.gov (United States)

    Smith, Adam L; Skerlos, Steven J; Raskin, Lutgarde

    2015-09-01

    Membrane biofilm development was evaluated to improve psychrophilic (15°C) anaerobic membrane bioreactor (AnMBR) treatment of domestic wastewater. An AnMBR containing three replicate submerged membrane housings with separate permeate collection was operated at three levels of membrane fouling by independently controlling biogas sparging for each membrane unit. High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration two to three times the equilibrium concentration predicted by Henry's law. Illumina sequencing of 16S rRNA targeting Bacteria and Archaea and reverse transcription-quantitative polymerase chain reaction targeting the methyl coenzyme-M reductase (mcrA) gene in methanogens indicated that the membrane biofilm was enriched in highly active methanogens and syntrophic bacteria. Restoring fouled membranes to a transmembrane pressure (TMP) near zero by increasing biogas sparging did not disrupt the biofilm's treatment performance, suggesting that microbes in the foulant layer were tightly adhered and did not significantly contribute to TMP. Dissolved methane oversaturation persisted without high TMP, implying that methanogenesis in the biofilm, rather than high TMP, was the primary driving force in methane oversaturation. The results describe an attractive operational strategy to improve treatment performance in low-temperature AnMBR by supporting syntrophy and methanogenesis in the membrane biofilm through controlled membrane fouling. PMID:26238293

  13. The control of biofilm formation by hydrodynamics of purified water in industrial distribution system

    OpenAIRE

    Florjanič, Maja; Kristl, Julijana

    2015-01-01

    Systems for storage and distribution of purified water at ambient temperature are highly susceptible to microbial contamination. The water flow, microbial content and chemical quality of the purified water in an industrial water system have been simulated in a biofilm annular reactor (BAR) to study the impact of different hydrodynamic conditions on biofilm development. Our results reveal the potential of stagnant purified water at total organic compounds (TOC) below 50 ppb to develop biofilm ...

  14. Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity

    International Nuclear Information System (INIS)

    Highlights: • Biofilm stages in static batch conditions were similar to dynamic conditions. • Expression of csgA gene increased earlier than alg8 gene in biofilm maturation. • AgNPs had higher effect on less mature biofilms. • Removal of extracellular polymeric substance made biofilms susceptible to AgNPs. - Abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1–3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms

  15. Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity

    Energy Technology Data Exchange (ETDEWEB)

    Thuptimdang, Pumis, E-mail: pumis.th@gmail.com [International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok 10330 (Thailand); Center of Excellence on Hazardous Substance Management, Bangkok 10330 (Thailand); Limpiyakorn, Tawan, E-mail: tawan.l@chula.ac.th [Center of Excellence on Hazardous Substance Management, Bangkok 10330 (Thailand); Department of Environmental Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Research Unit Control of Emerging Micropollutants in Environment, Chulalongkorn University, Bangkok 10330 (Thailand); McEvoy, John, E-mail: john.mcevoy@ndsu.edu [Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108 (United States); Prüß, Birgit M., E-mail: birgit.pruess@ndsu.edu [Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108 (United States); Khan, Eakalak, E-mail: eakalak.khan@ndsu.edu [Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58108 (United States)

    2015-06-15

    Highlights: • Biofilm stages in static batch conditions were similar to dynamic conditions. • Expression of csgA gene increased earlier than alg8 gene in biofilm maturation. • AgNPs had higher effect on less mature biofilms. • Removal of extracellular polymeric substance made biofilms susceptible to AgNPs. - Abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1–3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms.

  16. Space reactor fuels performance and development issues

    International Nuclear Information System (INIS)

    Three compact reactor concepts are now under consideration by the US Space Nuclear Power Program (the SP-100 Program) as candidates for the first 100-kWe-class space reactor. Each of these reactor designs puts unique constraints and requirements on the fuels system, and raises issues of fuel systems feasibility and performance. This paper presents a brief overview of the fuel requirements for the proposed space reactor designs, a delineation of the technical feasibility issues that each raises, and a description of the fuel systems development and testing program that has been established to address key technical issues

  17. Space reactor fuels performance and development issues

    International Nuclear Information System (INIS)

    Three compact reactor concepts are now under consideration by the U.S. Space Nuclear Power Program (the SP-100 Program) as candidates for the first 100-kWe-class space reactor. Each of these reactor designs puts unique constraints and requirements on the fuels system, and raises issues of fuel systems feasibility and performance. This paper presents a brief overview of the fuel requirements for the proposed space reactor designs, a delineation of the technical feasibility issues that each raises, and a description of the fuel systems development and testing program that has been established to address key technical issues

  18. Efficient surface functionalization of wound dressings by a phytoactive nanocoating refractory to Candida albicans biofilm development.

    Science.gov (United States)

    Anghel, Ion; Holban, Alina Maria; Andronescu, Ecaterina; Grumezescu, Alexandru Mihai; Chifiriuc, Mariana Carmen

    2013-12-01

    The present study reports the fabrication and characterization of a novel nanostructured phyto-bioactive coated rayon/polyester wound dressing (WD) surface refractory to Candida albicans adhesion, colonization and biofilm formation, based on functionalized magnetite nanoparticles and Anethum graveolens (AG) and Salvia officinalis (SO) essential oils (EOs). TEM, XRD, TGA, FT-IR were used for the characterization of the fabricated nanobiocoated WDs. Using magnetic nanoparticles for the stabilization and controlled release of EOs, the activity of natural volatile compounds is significantly enhanced and their effect is stable during time. For this reason the nanobiocoated surfaces exhibited a longer term anti-biofilm effect, maintained for at least 72 h. Besides their excellent anti- adherence properties, the proposed solutions exhibit the advantage of using vegetal natural compounds, which are less toxic and easily biodegradable in comparison with synthetic antifungal drugs, representing thus promising approaches for the development of successful ways to control and prevent fungal biofilms associated infections. PMID:24706124

  19. Assessment of fusion reactor development. Proceedings

    International Nuclear Information System (INIS)

    Symposium on assessment of fusion reactor development was held to make clear critical issues, which should be resolved for the commercial fusion reactor as a major energy source in the next century. Discussing items were as follows. (1) The motive force of fusion power development from viewpoints of future energy demand, energy resources and earth environment for 'Sustainable Development'. (2) Comparison of characteristics with other alternative energy sources, i.e. fission power and solar cell power. (3) Future planning of fusion research and advanced fuel fusion (D3He). (4) Critical issues of fusion reactor development such as Li extraction from the sea water, structural material and safety. (author)

  20. An evaluation of the performance and optimization of a new wastewater treatment technology: the air suction flow-biofilm reactor.

    Science.gov (United States)

    Forde, P; Kennelly, C; Gerrity, S; Collins, G; Clifford, Eoghan

    2015-01-01

    In this laboratory study, a novel wastewater treatment technology, the air suction flow-biofilm reactor (ASF-BR) - a sequencing batch biofilm reactor technology with a passive aeration mechanism - was investigated for its efficiency in removing organic carbon, nitrogen and phosphorus, from high-strength synthetic wastewaters. A laboratory-scale ASF-BR comprising 2 reactors, 350 mm in diameter and 450 mm in height, was investigated over 2 studies (Studies 1 and 2) for a total of 430 days. Study 1 lasted a total of 166 days and involved a 9-step sequence alternating between aeration, anoxic treatment and settlement. The cycle time was 12.1 h and the reactors were operated at a substrate loading rate of 3.60 g filtered chemical oxygen demand (CODf)/m2 media/d, 0.28 g filtered total nitrogen (TNf)/m2 media/d, 0.24 g ammonium-nitrogen (NH4-N)/m2 media/d and 0.07 g ortho-phosphate (PO4-P)/m2 media/d. The average removal rates achieved during Study 1 were 98% CODf, 88% TNf, 97% NH4-N and 35% PO4-P. During Study 2 (264 days), the unit was operated at a loading rate of 2.49 g CODf/m2 media/d, 0.24 g TNf/m2 media/d, 0.20 g NH4-N/m2 media/d and 0.06 PO4-P/m2 media/d. The energy requirement during this study was reduced by modifying the treatment cycle in include fewer pumping cycles. Removal rates in Study 2 averaged 97% CODf, 86% TNf, 99% NH4-N and 76% PO4-P. The excess sludge production of the system was evaluated and detailed analyses of the treatment cycles were carried out. Biomass yields were estimated at 0.09 g SS/g CODf, removed and 0.21 g SS/g CODf, removed for Studies 1 and 2, respectively. Gene analysis showed that the use of a partial vacuum did not affect the growth of ammonia-oxidizing bacteria. The results indicate that the ASF-BR and passive aeration technologies can offer efficient alternatives to existing technologies. PMID:25413003

  1. Sulfate reducing bacteria and their activities in oil sands process-affected water biofilm

    International Nuclear Information System (INIS)

    Biofilm reactors were constructed to grow stratified multispecies biofilm in oil sands process-affected water (OSPW) supplemented with growth medium. The development of sulfate reducing bacteria (SRB) within the biofilm and the biofilm treatment of OSPW were evaluated. The community structure and potential activity of SRB in the biofilm were investigated with H2S microsensor measurements, dsrB gene-based denaturing gradient gel electrophoresis (DGGE), and the real time quantitative polymerase chain reaction (qPCR). Multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H2S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the stratified biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. The study expands current knowledge of biofilm treatment of OSPW and the function of anaerobic SRB in OSPW biofilm, and thus provides information for future bioreactor development in the reclamation of OSPW. - Graphical abstract: The development of sulfate reducing bacteria (SRB) within Oil Sands Process-affected Water (OSPW) biofilm and the biofilm treatment of OSPW were evaluated by Liu and coworkers. Combined microsensor and molecular biology techniques were utilized in this study. Their results demonstrated that multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H2S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. - Highlights: • Biofilm in oil sands wastewater was developed on engineered biocarriers. • Bacterial community and in situ activity of SRB were studied in the biofilm. • Sulfate

  2. Sulfate reducing bacteria and their activities in oil sands process-affected water biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hong; Yu, Tong, E-mail: tong.yu@ualberta.ca; Liu, Yang, E-mail: yang.liu@ualberta.ca

    2015-12-01

    Biofilm reactors were constructed to grow stratified multispecies biofilm in oil sands process-affected water (OSPW) supplemented with growth medium. The development of sulfate reducing bacteria (SRB) within the biofilm and the biofilm treatment of OSPW were evaluated. The community structure and potential activity of SRB in the biofilm were investigated with H{sub 2}S microsensor measurements, dsrB gene-based denaturing gradient gel electrophoresis (DGGE), and the real time quantitative polymerase chain reaction (qPCR). Multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H{sub 2}S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the stratified biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. The study expands current knowledge of biofilm treatment of OSPW and the function of anaerobic SRB in OSPW biofilm, and thus provides information for future bioreactor development in the reclamation of OSPW. - Graphical abstract: The development of sulfate reducing bacteria (SRB) within Oil Sands Process-affected Water (OSPW) biofilm and the biofilm treatment of OSPW were evaluated by Liu and coworkers. Combined microsensor and molecular biology techniques were utilized in this study. Their results demonstrated that multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H{sub 2}S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. - Highlights: • Biofilm in oil sands wastewater was developed on engineered biocarriers. • Bacterial community and in situ activity of SRB were studied in the

  3. Biofilm development by potentially pathogenic non-pigmented rapidly growing mycobacteria

    Directory of Open Access Journals (Sweden)

    Fernández-Roblas Ricardo

    2008-10-01

    Full Text Available Abstract Background A study to evaluate the biofilm-development ability in three different media (Middlebrook 7H9, sterile tap water and PBS-5% glucose was performed with 19 collection strains from 15 different species on non-pigmented rapidly growing mycobacteria (NPRGM. A microtiter plate assay was developed to evaluate the percentage of covered surface of the microtiter plate wells in different days from day 1 to day 69. Results All strains were able to develop biofilm in all the tested media. Middlebrook 7H9 showed the fastest growth, followed by sterile tap water and PBS-5% glucose. A sigmoid growth curve was detected in all the strains both in Middlebrook 7H9 and in sterile tap water. A difference could be detected for Mycobacterium abscessus in tap water, where it showed faster growth than all the other strains. Conclusion Biofilm development seems to be a property of all the species of NPRGM and it depends on the nutrients present in the medium. The microtiter plate assay described here is a useful tool to evaluate differences in biofilm development among the different species of rapidly growing mycobacteria.

  4. Sulfate reducing bacteria and their activities in oil sands process-affected water biofilm.

    Science.gov (United States)

    Liu, Hong; Yu, Tong; Liu, Yang

    2015-12-01

    Biofilm reactors were constructed to grow stratified multispecies biofilm in oil sands process-affected water (OSPW) supplemented with growth medium. The development of sulfate reducing bacteria (SRB) within the biofilm and the biofilm treatment of OSPW were evaluated. The community structure and potential activity of SRB in the biofilm were investigated with H2S microsensor measurements, dsrB gene-based denaturing gradient gel electrophoresis (DGGE), and the real time quantitative polymerase chain reaction (qPCR). Multispecies biofilm with a thickness of 1000 μm was successfully developed on engineered biocarriers. H2S production was observed in the deeper anoxic zone of the biofilm from around 750 μm to 1000 μm below the bulk water-biofilm interface, revealing sulfate reduction in the deeper zone of the stratified biofilm. The biofilm removed chemical oxygen demand (COD), sulfate, and nitrogen. The study expands current knowledge of biofilm treatment of OSPW and the function of anaerobic SRB in OSPW biofilm, and thus provides information for future bioreactor development in the reclamation of OSPW. PMID:26204047

  5. Treatment of Spacecraft Wastewater Using a Hollow Fiber Membrane Biofilm Redox Control Reactor

    Science.gov (United States)

    Smith, Daniel P.

    2003-01-01

    The purpose of this project was to develop and evaluate design concepts for biological treatment reactors for the purification of spacecraft wastewater prior to reverse osmosis treatment. The motivating factor is that wastewater recovery represents the greatest single potential reduction in the resupply requirements for crewed space missions. Spacecraft wastewater composition was estimated from the characteristics of the three major component streams: urine/flush water, hygiene water, and atmospheric condensate. The key characteristics of composite spacecraft wastewater are a theoretical oxygen demand of 4519 mg/L, of which 65% is nitrogenous oxygen demand, in a volume of 11.5 liter/crew-day. The organic carbon to nitrogen ratio of composite wastewater is 0.86. Urine represents 93% of nitrogen and 49% of the organic carbon in the composite wastestream. Various bioreaction scenarios were evaluated to project stoichiometric oxygen demands and the ability of wastewater carbon to support denitrification. Ammonia nitrification to the nitrite oxidation state reduced the oxygen requirement and enabled wastewater carbon to provide nearly complete denitrification. A conceptual bioreactor design was established using hollow fiber membranes for bubbleless oxygen transfer in a gravity-free environment, in close spatial juxtaposition to a second interspaced hollow fiber array for supplying molecular hydrogen. Highly versatile redox control and an enhanced ability to engineer syntrophic associations are stated advantages. A prototype reactor was constructed using a microporous hollow fiber membrane module for aeration. Maintaining inlet gas pressure within 0.25 psi of the external water pressure resulted in bubble free operation with no water ingress into hollow fiber lumens. Recommendations include the design and operational testing of hollow fiber bioreactors using: 1) Partial nitrification/nitrite predenitrification; 2) Limited aeration for simultaneous nitrification

  6. Removal of absorbable organic halides (aox) from recycled paper mill effluent using granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR)

    International Nuclear Information System (INIS)

    Paper mills generate varieties of pollutants depending upon the type of the pulping process. Paper mill wastewaters have high chemical oxygen demand (COD) and colour, indicating high concentrations of recalcitrant organics. The study was conducted employing a Granular Activated Carbon - Sequencing Batch Biofilm Reactor (GAC-SBBR), containing 3.0 L working volume, operated in aerobic condition and packed with 200 g/L of 2-3 mm granular activated carbon (coconut shells) as a medium for biofilm growth. For the first couple of month, the HRT was 36 hours and the HRT of this reactor was adjusted to 24 hours in order to evaluate the performance of the system. The treated wastewater sample for these studies came from a recycle paper factory from MNI Sdn Bhd with 4 different samples characteristics. The adsorbable organic halides (AOX) to be determined and treated were Pentachlorophenol (PCP), 2,3,4,5-Tetrachlorophenol (2,3,4,5-TeCP), 2,4,6-Trichlorophenol (2,4,6-TCP), 2,4-Dichlorophenol ( 2,4-DCP), 2-Chlorophenol (CP) and phenol. Results showed that, the biofilm attached onto granular activated carbon (GAC) could substantially remove these recalcitrant in the wastewater. More over, results from the studies showed that high removal was achieved by the biofilm SBR with 10-100% removal of AOX and depending on HRT. (Author)

  7. Start-up of membrane bioreactor and hybrid moving bed biofilm reactor-membrane bioreactor: kinetic study.

    Science.gov (United States)

    Leyva-Díaz, J C; Poyatos, J M

    2015-01-01

    A hybrid moving bed biofilm reactor-membrane bioreactor (hybrid MBBR-MBR) system was studied as an alternative solution to conventional activated sludge processes and membrane bioreactors. This paper shows the results obtained from three laboratory-scale wastewater treatment plants working in parallel in the start-up and steady states. The first wastewater treatment plant was a MBR, the second one was a hybrid MBBR-MBR system containing carriers both in anoxic and aerobic zones of the bioreactor (hybrid MBBR-MBRa), and the last one was a hybrid MBBR-MBR system which contained carriers only in the aerobic zone (hybrid MBBR-MBRb). The reactors operated with a hydraulic retention time of 30.40 h. A kinetic study for characterizing heterotrophic biomass was carried out and organic matter and nutrients removals were evaluated. The heterotrophic biomass of the hybrid MBBR-MBRb showed the best kinetic performance in the steady state, with yield coefficient for heterotrophic biomass=0.30246 mg volatile suspended solids per mg chemical oxygen demand, maximum specific growth rate for heterotrophic biomass=0.00308 h(-1) and half-saturation coefficient for organic matter=3.54908 mg O2 L(-1). The removal of organic matter was supported by the kinetic study of heterotrophic biomass. PMID:26606088

  8. Characteristics of hydrogenotrophic denitrification in a combined system of gas-permeable membrane and a biofilm reactor

    International Nuclear Information System (INIS)

    A double Monod form was employed to describe two-step hydrogenotrophic denitrification, and the saturation constants of nitrate, nitrite and hydrogen were determined by batch tests. A combined system of gas-permeable membrane and a biofilm reactor (GPM-BR) was employed to remove nitrate from drinking water. The gas-permeable membrane was tested to exclusively deliver hydrogen to an independent attached growth system. The denitrification performance of the GPM-BR was investigated with different nitrate loadings of 96.78, 163.16 and 342.58 mg N/(L d). The nitrate removal rate (NRR) of the reactor could achieve 471.36 mg N/(L d) with sufficient dissolved hydrogen (DH) in the batch tests. While in the continuous experiments, NRR ranged from 96.72 to 301.44 mg N/(L d) under different nitrate loadings. Although low nitrate loading of 96.78 mg N/(L d) led to better nitrate removal, the denitrification capacity of GPM-BR would be limited and sulfate reduction occurred.

  9. Actual Application of a H2-Based Polyvinyl Chloride Hollow Fiber Membrane Biofilm Reactor to Remove Nitrate from Groundwater

    Directory of Open Access Journals (Sweden)

    Yanhao Zhang

    2015-01-01

    Full Text Available To evaluate the actual performance of the H2-based polyvinyl chloride hollow fiber membrane biofilm reactor (HF-MBfR, we used HF-MBfR to remove nitrate from the nitrate contaminated groundwater with the dissolved oxygen (~6.2 mg/L in Zhangqiu city (Jinan, China. The reactor was operated over 135 days with the actual nitrate contaminated groundwater. The result showed that maximum of nitrate denitrification rate achieved was over 133.8 g NO3--N/m3d (1.18 g NO3--N/m2d and the total nitrogen removal was more than 95.0% at the conditions of influent nitrate 50 mg/L, hydrogen pressure 0.05 MPa, and dissolved oxygen (DO 6.2 mg/L, with the nitrate in effluent under the value limits of drinking water. The fluxes analysis showed that the electron-equivalent fluxes of nitrate, sulfate, and oxygen account for about 81.2%, 15.2%, and 3.6%, respectively, which indicated that nitrate reduction could consume more electrons than that of sulfate reduction and dissolved oxygen reduction. The nitrate reduction was not significantly influenced by sulfate reduction and the dissolved oxygen reduction. Based on the actual groundwater quality on site, the Langelier Saturation Index (LSI was 0.4, and the membrane could be at the risk of surface scaling.

  10. Hydrogen sulfide oxidation in novel Horizontal-Flow Biofilm Reactors dominated by an Acidithiobacillus and a Thiobacillus species.

    Science.gov (United States)

    Gerrity, S; Kennelly, C; Clifford, E; Collins, G

    2016-09-01

    Hydrogen Sulfide (H2S) is an odourous, highly toxic gas commonly encountered in various commercial and municipal sectors. Three novel, laboratory-scale, Horizontal-Flow Biofilm Reactors (HFBRs) were tested for the removal of H2S gas from air streams over a 178-day trial at 10°C. Removal rates of up to 15.1 g [H2S] m(-3) h(-1) were achieved, demonstrating the HFBRs as a feasible technology for the treatment of H2S-contaminated airstreams at low temperatures. Bio-oxidation of H2S in the reactors led to the production of H(+) and sulfate (SO(2-)4) ions, resulting in the acidification of the liquid phase. Reduced removal efficiency was observed at loading rates of 15.1 g [H2S] m(-3) h(-1). NaHCO3 addition to the liquid nutrient feed (synthetic wastewater (SWW)) resulted in improved H2S removal. Bacterial diversity, which was investigated by sequencing and fingerprinting 16S rRNA genes, was low, likely due to the harsh conditions prevailing in the systems. The HFBRs were dominated by two species from the genus Acidithiobacillus and Thiobacillus. Nonetheless, there were significant differences in microbial community structure between distinct HFBR zones due to the influence of alkalinity, pH and SO4 concentrations. Despite the low temperature, this study indicates HFBRs have an excellent potential to biologically treat H2S-contaminated airstreams. PMID:26829048

  11. Development trends in reactor technology

    International Nuclear Information System (INIS)

    There are two ways to increase the efficiency of a nuclear power plant besides improving the cost situation, availability and acceptance. On the one hand, the conversion of thermal energy into mechanical energy can be enhanced. This is an approach analogous to increasing the efficiency of conventional steam power plants which, consequently, benefits from the most recent advances in that technology. The other approach involves the improved conversion of fuel into thermal energy, i.e. an optimization of burnup. The worldwide Generation IV integrated research effort is pursuing both ways. This report focuses on two typical examples of the research program, i.e. one light water reactor with supercritical steam conditions raising plant efficiency to more than 44%, and one lead-cooled fast reactor which, in addition, increases burnup to more than 150 GWd/t. (orig.)

  12. Magnetite nanoparticles for functionalized textile dressing to prevent fungal biofilms development

    Science.gov (United States)

    Anghel, Ion; Grumezescu, Alexandru Mihai; Andronescu, Ecaterina; Anghel, Alina Georgiana; Ficai, Anton; Saviuc, Crina; Grumezescu, Valentina; Vasile, Bogdan Stefan; Chifiriuc, Mariana Carmen

    2012-09-01

    The purpose of this work was to investigate the potential of functionalized magnetite nanoparticles to improve the antibiofilm properties of textile dressing, tested in vitro against monospecific Candida albicans biofilms. Functionalized magnetite (Fe3O4/C18), with an average size not exceeding 20 nm, has been synthesized by precipitation of ferric and ferrous salts in aqueous solution of oleic acid (C18) and NaOH. Transmission electron microscopy, X-ray diffraction analysis, and differential thermal analysis coupled with thermo gravimetric analysis were used as characterization methods for the synthesized Fe3O4/C18. Scanning electron microscopy was used to study the architecture of the fungal biofilm developed on the functionalized textile dressing samples and culture-based methods for the quantitative assay of the biofilm-embedded yeast cells. The optimized textile dressing samples proved to be more resistant to C. albicans colonization, as compared to the uncoated ones; these functionalized surfaces-based approaches are very useful in the prevention of wound microbial contamination and subsequent biofilm development on viable tissues or implanted devices.

  13. Observations on the development of the crystalline bacterial biofilms that encrust and block Foley catheters.

    Science.gov (United States)

    Stickler, D J; Morgan, S D

    2008-08-01

    The care of many patients undergoing long-term bladder catheterisation is complicated when the flow of urine through the catheter is blocked by encrustation. The problem results from infection by urease-producing bacteria, especially Proteus mirabilis, and the subsequent formation of crystalline biofilms on the catheter. The aim of this study was to discover how P. mirabilis initiates the development of these crystalline biofilms. The early stages in the formation of the biofilms were observed on a range of Foley catheters in a laboratory model of the catheterised bladder. Scanning electron micrographs revealed that when all-silicone, silicone-coated latex, hydrogel-coated latex, hydrogel/silver-coated latex and nitrofurazone silicone catheters were inserted into bladder models containing P. mirabilis and alkaline urine, their surfaces were rapidly coated with a microcrystalline foundation layer. X-ray microanalysis showed that this material was composed of calcium phosphate. Bacterial colonisation of the foundation layer followed and by 18h the catheters were encrusted by densely populated crystalline P. mirabilis biofilms. These observations have important implications for the development of encrustation-resistant catheters. In the case of silver catheters for example, bacterial cells can attach to the crystalline foundation layer and continue to grow, protected from contact with the underlying silver. If antimicrobials are to be incorporated into catheters to prevent encrustation, it is important that they diffuse into the urine and prevent the rise in pH that triggers crystal formation. PMID:18550219

  14. 生物膜反应器在污水处理中的应用进展%Biofilm Reactor Applications Progress in Wastewater Treatment

    Institute of Scientific and Technical Information of China (English)

    王世农

    2011-01-01

    生物膜反应器在污水处理工艺中是与活性污泥法并行的一种生物污水处理方法,广泛应用于工业废水和城市污水处理的二级处理中,也是污水处理的关键环节。对生物膜反应器在污水处理中的应用进展进行了综述。%Biofilm reactor process is a method in parallel with an activated sludge biological treatment in wastewater treatment,and widely used in industrial wastewater and urban sewage secondary treatment,also the key factor of sewage treatment.This overviews the biofilm reactor in sewage treatment field for research and reviews the newly progress.

  15. Bacterial Composition of Biofilms Collected From Two Service Areas in a Metropolitan Drinking Water Distribution System

    Science.gov (United States)

    The development and succession of bacteria were examined by 16S rRNA gene clone libraries generated from various biofilms within a metropolitan water distribution system. Biofilms were obtained from off-line devices using polycarbonate coupons from annular reactors incubated for ...

  16. Survival of biofilm-associated Legionella pneumophila exposed to various stressors.

    Science.gov (United States)

    Vatansever, Cansu; Türetgen, Irfan

    2015-03-01

    Biofilm is crucial for the multiplication and survival of Legionella pneumophila. The survival after different stressors of biofilm-associated L. pneumophila was evaluated during 150 days in this study. Mixed biofilms were allowed to develop on coupons in a biofilm reactor, which was experimentally infected with L. pneumophila. A dose of 2 ppm of monochloramine was found ineffective to kill younger (60 days) biofilm-associated L. pneumophila, whereas shock treatment (500 and 1000 ppm) was found to be significantly successful, as expected. Also, short exposure to 60 °C was insufficient to kill all young L. pneumophila within biofilms. A significant amount of young L. pneumophila bacteria also resisted pH 11 and 3 molar salt solution. No significant change was observed after exposure to 4 °C, ultra pure water and pH 5. Interestingly, L. pneumophila bacteria in biofilm became more sensitive after 90 days. PMID:25842533

  17. Multispecies Biofilm Development on Space Station Heat Exhanger Core Material

    Science.gov (United States)

    Pyle, B. H.; Roth, S. R.; Vega, L. M.; Pickering, K. D.; Alvarez, Pedro J. J.; Roman, M. C.

    2007-01-01

    Investigations of microbial contamination of the cooling system aboard the International Space Station (ISS) suggested that there may be a relationship between heat exchanger (HX) materials and the degree of microbial colonization and biofilm formation. Experiments were undertaken to test the hypothesis that biofilm formation is influenced by the type and previous exposure of HX surfaces. Acidovorax delafieldii, Comamonas acidovorans, Hydrogenophaga pseudoflava, Pseudomonas stutzeri, Sphingomonas paucimobilis, and Stenotrophomonas maltophilia, originally isolated from ISS cooling system fluid, were cultured on R2A agar and suspended separately in fresh filter-sterilized ISS cooling fluid, pH 8.3. Initial numbers in each suspension ranged from 10(exp 6)-10(exp 7) CFU/ml, and a mixture contained greater than 10(exp 7) CFU/ml. Coupons of ISS HX material, previously used on orbit (HXOO) or unused (HXUU), polycarbonate (PC) and 316L polished stainless steel (SS) were autoclaved, covered with multispecies suspension in sterile tubes and incubated in the dark at ambient (22-25 C). Original HX material contained greater than 90% Ni, 4.5% Si, and 3.2% B, with a borate buffer. For approximately 10 weeks, samples of fluid were plated on R2A agar, and surface colonization assessed by SYBR green or BacLight staining and microscopy. Suspension counts for the PC and SC samples remained steady at around 10(exp 7) CFU/ml. HXUU counts declined about 1 log in 21 d then remained steady, and HXOO counts declined 2 logs in 28 d, fluctuated and stabilized about 10(exp 3) CFU/ml from 47-54 d. Predominantly yellow S. paucimobilis predominated on plates from HXOO samples up to 26 d, then white or translucent colonies of other species appeared. All colony types were seen on plates from other samples throughout the trial. Epifluorescence microscopy indicated microbial growth on all surfaces by 21 d, followed by variable colonization. After 54 d, all but the HXOO samples had well

  18. Development of biofilm-targeted antimicrobial wound dressing for the treatment of chronic wound infections.

    Science.gov (United States)

    Ng, Shiow-Fern; Leow, Hon-Lunn

    2015-01-01

    It has been established that microbial biofilms are largely responsible for the recalcitrance of many wound infections to conventional antibiotics. It was proposed that the efficacy of antibiotics could be optimized via the inhibition of bacterial biofilm growth in wounds. The combination of antibiofilm agent and antibiotics into a wound dressing may be a plausible strategy in wound infection management. Xylitol is an antibiofilm agent that has been shown to inhibit the biofilm formation. The purpose of this study was to develop an alginate film containing xylitol and gentamicin for the treatment of wound infection. Three films, i.e. blank alginate film (SA), alginate film with xylitol (F5) and alginate film with xylitol and gentamicin (AG), were prepared. The films were studied for their physical properties, swelling ratio, moisture absorption, moisture vapor transmission rate (MVTR), mechanical and rheology properties, drug content uniformity as well as in vitro drug release properties. Antimicrobial and antibiofilm in vitro studies on Staphylococcus aureus and Pseudomonas aeruginosa were also performed. The results showed that AG demonstrates superior mechanical properties, rheological properties and a higher MVTR compared with SA and F5. The drug flux of AG was higher than that of commercial gentamicin cream. Furthermore, antimicrobial studies showed that AG is effective against both S. aureus and P. aeruginosa, and the antibiofilm assays demonstrated that the combination was effective against biofilm bacteria. In summary, alginate films containing xylitol and gentamicin may potentially be used as new dressings for the treatment of wound infection. PMID:25758412

  19. The US Liquid Metal Reactor Development Program

    International Nuclear Information System (INIS)

    The US Liquid Metal Reactor Development Program has been restructured to take advantage of the opportunity today to carry out R and D on truly advanced reactor technology. The program gives particular emphasis to improvements to reactor safety. The new directions are based on the technology of the Integral Fast Reactor (IFR). Much of the basis for superior safety performance using IFR technology has been experimentally verified and aggressive programs continue in EBR-II and TREAT. Progress has been made in demonstrating both the metallic fuel and the new electrochemical processes of the IFR. The FFTF facility is converting to metallic fuel; however, FFTF also maintains a considerable US program in oxide fuels. In addition, generic programs are continuing in steam generator testing, materials development, and, with international cooperation, aqueous reprocessing. Design studies are carried out in conjunction with the IFR technology development program. In summary, the US maintains an active development program in Liquid Metal Reactor technology, and new directions in reactor safety are central to the program

  20. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

    use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

  1. Development of Korea advanced liquid metal reactor

    International Nuclear Information System (INIS)

    Future nuclear power plants should not only have the features of improved safety and economic competitiveness but also provide a means to resolve spent fuel storage problems by minimizing volume of high level wastes. It is widely believed that liquid metal reactors (LMRs) have the highest potential of meeting these requirements. In this context, the LMR development program was launched as a national long-term R and D program in 1992, with a target to introduce a commercial LMR around 2030. Korea Advanced Liquid Metal Reactor (KALIMER), a 150 MWe pool-type sodium cooled prototype reactor, is currently under the conceptual design study with the target schedule to complete its construction by the mid-2010s. This paper summarizes the KALIMER development program and major technical features of the reactor system. (author)

  2. Strategies of development of reactor types

    International Nuclear Information System (INIS)

    The development of nuclear energy in the coming decades will depend on the goals followed, on the available technologies and on the strategies implemented in the world in agreement with public acceptation. This article is limited to the technical aspects of the strategies of development of reactor types: 1 - objectives; 2 - common constraints to all reactor types: safety and terrorism risks, wastes, non-proliferation, economics; 3 - different reactor types: general considerations, proven technologies (PWR, BWR, Candu), non-proven technologies but having an important experience, technologies at the design stage; 4 - energy systems and 'Generation IV forum': systems based on thermal neutron reactors and low enrichment, systems for the valorization of 238U, systems for Pu burning, systems allowing the destruction of minor actinides, thorium-based systems, the Gen IV international forum; 5 - conclusion. (J.S.)

  3. Experimental biofilms within drinking water treatment plant origin; evaluation of nutrient concentration and temperature influences upon their development

    Directory of Open Access Journals (Sweden)

    Anca FARKAS

    2009-11-01

    Full Text Available From the planktonic free-floating state, microorganisms pass to the solid state, the biofilm, cells being strongly attached to each other and usually to the interface. This changing in cells’ behavior induces surface colonization and complex interactions development within the biofilm. If the biofilm’s role into the natural aquatic habitats is, undoubtedly, a positive one, consisting in water self-purification, drinking water pipe networks biofouling can be responsible for a wide range of water quality and operational problems. This exploratory experiment was performed in order to investigate, in a time interval of 7 days, the influence of certain environmental factors such as nutrient concentration and temperature upon in vitro biofilm’s development, origin in the biofilm of water treatment plant. The method used for in vitro biofilm growth monitoring is the colorimetric measurement of the biomass. Descriptive analyses, including the mean value, variability, trends, correlations and graphic displays were performed. The correlation analysis shown that the biofilm development in the discussed experiment was influenced as by the origin source as by the temperature, time and nutrients concentration. The biomass increment was significantly different for the biofilms with clarifier and sand filter sites origin, grown at 22 oC, while at 8 oC, the differences were not significant from a statistical point of view. For all the dilutions, moments and temperatures considered, the biofilm’s development with clarifier origin registered was significantly higher than the biofilm with sand filter origin.

  4. Fast reactors and advanced light water reactors for sustainable development

    International Nuclear Information System (INIS)

    Complete text of publication follows: The importance of nuclear energy, as a realistic option to solve the issues of the depletion of energy resources and the global environment, has been re-acknowledged worldwide. In response to this international movement, the papers compiling the most recent findings in the fields of fast reactors (FR) and advanced light water reactors (LWR) were gathered and published in this special issue. This special issue compiles six articles, most of which are very meticulously performed studies of the multi year development of design and assessment methods for large sodium-cooled FRs (SFRs), and two are related to the fuel cycle options that are leading to a greater understanding on the efficient utilization of energy resources. The Japanese sodium-cooled fast reactor (JSFR) is addressed in two manuscripts. H. Yamano et al. reviewed the current design which adopts a number of innovative technologies in order to achieve economic competitiveness, enhanced reliability, and safety. Their safety assessments of both design basis accidents and severe accidents indicate that the devised JSFR satisfies well their risk target. T. Takeda et al. discussed the improvement of the modeling accuracy for the detailed calculation of JSFR's features in three areas: neutronics, fuel materials, and thermal hydraulics. The verification studies which partly use the measured data from the prototype FBR Monju are also described. Two of these manuscripts deal with those aspects of advanced design of SFR that have hitherto not been explored in great depth. The paper by G. Palmiotti et al. explored the possibility of using the sensitivity methodologies in the reactor physics field. A review of the methods used is provided, and several examples illustrate the success of the methodology in reactor physics. A new application as the improvement of nuclear basic parameters using integral experiments is also described. F. Baque et al. reviewed the evolution of the in

  5. Breeder reactor fuel fabrication system development

    International Nuclear Information System (INIS)

    Significant progress has been made in the design and development of remotely operated breeder reactor fuel fabrication and support systems (e.g., analytical chemistry). These activities are focused by the Secure Automated Fabrication (SAF) Program sponsored by the Department of Energy to provide: a reliable supply of fuel pins to support US liquid metal cooled breeder reactors and at the same time demonstrate the fabrication of mixed uranium/plutonium fuel by remotely operated and automated methods

  6. Investigating Nitrosomonas europaea stress biomarkers in batch, continuous culture, and biofilm reactors.

    Science.gov (United States)

    Radniecki, Tyler S; Lauchnor, Ellen G

    2011-01-01

    The understanding of nitrification inhibition in ammonia oxidizing bacteria (AOB) by priority pollutants and emerging contaminants is critical in managing the nitrogen cycle to preserve current water supplies, one of the National Academy of Engineers Grand Challenges in Engineering for the twenty-first century. Nitrosomonas europaea is an excellent model AOB for nitrification inhibition experimentation due to its well-defined NH(3) metabolism and the availability of a wide range of physiological and transcriptional tools that can characterize the mechanism of nitrification inhibition and probe N. europaea's response to the inhibitor. This chapter is a compilation of the physiological and transcriptional methods that have been used to characterize nitrification inhibition of N. europaea under a wide variety of growth conditions including batch, continuously cultured, and in biofilms. The protocols presented here can be applied to other AOB, and may be readily adapted for other autotrophic bacteria (e.g., nitrite oxidizing bacteria). PMID:21514466

  7. Development of an automatic reactor inspection system

    International Nuclear Information System (INIS)

    Using recent technologies on a mobile robot computer science, we developed an automatic inspection system for weld lines of the reactor vessel. The ultrasonic inspection of the reactor pressure vessel is currently performed by commercialized robot manipulators. Since, however, the conventional fixed type robot manipulator is very huge, heavy and expensive, it needs long inspection time and is hard to handle and maintain. In order to resolve these problems, we developed a new automatic inspection system using a small mobile robot crawling on the vertical wall of the reactor vessel. According to our conceptual design, we developed the reactor inspection system including an underwater inspection robot, a laser position control subsystem, an ultrasonic data acquisition/analysis subsystem and a main control subsystem. We successfully carried out underwater experiments on the reactor vessel mockup, and real reactor ready for Ulchine nuclear power plant unit 6 at Dusan Heavy Industry in Korea. After this project, we have a plan to commercialize our inspection system. Using this system, we can expect much reduction of the inspection time, performance enhancement, automatic management of inspection history, etc. In the economic point of view, we can also expect import substitution more than 4 million dollars. The established essential technologies for intelligent control and automation are expected to be synthetically applied to the automation of similar systems in nuclear power plants

  8. The influence of resin-based dental materials on oral biofilms developement

    OpenAIRE

    Ionescu, Andrei Cristian

    2015-01-01

    Resin-based composites (RBCs) are the most widespread restorative dental materials used nowadays. Nanotechnologies allowed the development and improvement of a new generation of RBCs which nevertheless still present many unsolved issues. The most important is secondary caries, which is the recurrence of dental caries in tissues close to the restoration. Dental caries disease is driven by a dysbiotic biofilm colonizing both natural and artificial surfaces. Many approaches have been developed i...

  9. Applying moving bed biofilm reactor for removing linear alkylbenzene sulfonate using synthetic media

    Directory of Open Access Journals (Sweden)

    Jalaleddin Mollaei

    2015-01-01

    Full Text Available Detergents and problems of their attendance into water and wastewater cause varied difficulties such as producing foam, abnormality in the growth of algae, accumulation and dispersion in aqueous environments. One of the reactors was designated with 30% of the media with the similar conditions exactly same as the other which had filling rate about 10 %, in order to compare both of them together. A standard method methylene blue active substance was used to measure anionic surfactant. The concentrations of linear alkylbenzene sulfonate which examined were 50, 100, 200, 300 and 400 mg/l in HRT 72, 24 and 8 hrs. The removal percentage for both of reactors at the beginning of operating at50 mg/l concentration of pollutant had a bit difference and with gradually increasing the pollutant concentration and decreasing Hydraulic retention time, the variation between the removal percentage of both reactors became significant as the reactor that had the filling rate about 30 %, showed better condition than the other reactor with 10 % filling rate. Ideal condition in this experiment was caught at hydraulic retention time about 72 hrs and 200 mg/l pollutants concentration with 99.2% removal by the reactor with 30% filling rate. While the ideal condition for the reactor with 10% filling rate with the same hydraulic retention time and 100 mg/l pollutants concentrations was obtained about 99.4% removal. Regarding anionic surfactant standard in Iran which is 1.5 mg/l for surface water discharge, using this process is suitable for treating municipal wastewater and industrial wastewater which has a range of the pollutant between 100-200 mg/l. but for the industries that produce detergents products which make wastewater containing more than 200 mg/l surfactants, using secondary treatment process for achieving discharge standard is required.

  10. The effect of selected plant extracts on the development of single-species dental biofilms

    International Nuclear Information System (INIS)

    To determine the effect of a mixture of plant extracts on the adherence and retention of bacteria in dental biofilm. Study Design: Experimental study. Place and Duration of Study:Department of Oral Biology, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia, from December 2009 to December 2011. Methodology: For determination of adhering ability, experimental pellicle was first treated with the Plant Extracts Mixture (PEM) before inoculating it with individual bacterial species ( S. mitis / S. sanguinis / S. mutans). For the determination of retention ability, the procedure was repeated with the experimental pellicle being inoculated first with the individual bacterial species and then treating it with the PEM. These two experiments were repeated with deionized distilled water (negative control) and Thymol (0.64%) (positive control). The bacterial populations in biofilms for the two experiments were expressed as Colony Forming Unit (CFU) / mL x 10/sup 4/ and the corresponding values were expressed as mean +- SD. Results: The effect of the Plant Extracts Mixture (PEM) for the two experiments was compared with that of Thymol and deionized distilled water. It was shown that there is a reduced adherence of bacteria to PEM-treated and Thymol (0.064%) treated experimental pellicle compared with the negative control (p < 0.001). It was also found that the retention of bacteria in both treated biofilms is also lower than that of negative control (p = 0.001). Conclusion: Plant Extracts Mixture (PEM) may influence the development of dental biofilm by affecting the adhering and retention capacities of the bacterial species in the dental biofilms. (author)

  11. Las degradation in a fluidized bed reactor and phylogenetic characterization of the biofilm

    Directory of Open Access Journals (Sweden)

    L. L. Oliveira

    2013-09-01

    Full Text Available A fluidized bed reactor was used to study the degradation of the surfactant linear alkylbenzene sulfonate (LAS. The reactor was inoculated with anaerobic sludge and was fed with a synthetic substrate supplemented with LAS in increasing concentrations (8.2 to 45.8 mg l-1. The removal efficiency of 93% was obtained after 270 days of operation. Subsequently, 16S rRNA gene sequencing and phylogenetic analysis of the sample at the last stage of the reactor operation recovered 105 clones belonging to the domain Bacteria. These clones represented a variety of phyla with significant homology to Bacteroidetes (40%, Proteobacteria (42%, Verrucomicrobia (4%, Acidobacteria (3%, Firmicutes (2%, and Gemmatimonadetes (1%. A small fraction of the clones (8% was not related to any phylum. Such phyla variety indicated the role of microbial consortia in degrading the surfactant LAS.

  12. Extracellular polymeric substances govern the development of biofilm and mass transfer of polycyclic aromatic hydrocarbons for improved biodegradation.

    Science.gov (United States)

    Zhang, Yinping; Wang, Fang; Zhu, Xiaoshu; Zeng, Jun; Zhao, Qiguo; Jiang, Xin

    2015-10-01

    The hypothesis that extracellular polymeric substances (EPS) affect the formation of biofilms for subsequent enhanced biodegradation of polycyclic aromatic hydrocarbons was tested. Controlled formation of biofilms on humin particles and biodegradation of phenanthrene and pyrene were performed with bacteria and EPS-extracted bacteria of Micrococcus sp. PHE9 and Mycobacterium sp. NJS-P. Bacteria without EPS extraction developed biofilms on humin, in contrast the EPS-extracted bacteria could not attach to humin particles. In the subsequent biodegradation of phenanthrene and pyrene, the biodegradation rates by biofilms were significantly higher than those of EPS-extracted bacteria. Although, both the biofilms and EPS-extracted bacteria showed increases in EPS contents, only the EPS contents in biofilms displayed significant correlations with the biodegradation efficiencies of phenanthrene and pyrene. It is proposed that the bacterial-produced EPS was a key factor to mediate bacterial attachment to other surfaces and develop biofilms, thereby increasing the bioavailability of poorly soluble PAH for enhanced biodegradation. PMID:26141288

  13. High temperature reactor development in the Netherlands

    International Nuclear Information System (INIS)

    This year, some clear design choices have been made in the WHITE Reactor development programme. The activities will be concentrated at the development of a small size pebble bed HTR for combined heat and power production with a closed cycle gas turbine. Objective of the development is threefold: 1. restoring social support; 2. establishing commercial viability after market introduction; and 3. making the market introduction itself feasible, i.e. limited development and first-of-a-kind costs. This design is based on the peu-a-peu design of KFA Juelich and will be optimized. The computer codes necessary for this are being prepared for this work. The dynamic neutronics code PANTHER is being coupled to the thermal hydraulics code THERMIX-DIREKT. For this reactor type, fuel temperatures are maximal in the scenario of depressurization with recriticality. Even for this scenario, fuel temperatures of the 20MWth PAP-GT do not exceed 1300 deg. C, so there should be room for upscaling for economic reasons. On the other hand, it would be convenient to fuel the reactor batchwise instead of continuously, and the use of thorium could be required. These two features may lead to a larger temperature margin. The optimal design must unite these features in the best acceptable way. To gain expertise in calculations on gas cooled graphite moderate reactors, benchmark calculations are being performed in parallel with international partners. Parallel to this, special expertise is being built up on HTR fuel and HTR reactor vessels. (author). 3 refs

  14. Effect of Cu(II) shock loads on shortcut biological nitrogen removal in a hybrid biofilm nitrogen removal reactor.

    Science.gov (United States)

    Yin, Jun; Xu, Hengjuan; Shen, Dongsheng; Wang, Kun; Lin, Ying

    2015-06-01

    The effect of Cu(II) shock loads on shortcut biological nitrogen removal during a continuous-flow anoxic/aerobic process was investigated using a hybrid biofilm nitrogen removal reactor. The results demonstrated that [Formula: see text]-N removal was not affected by any Cu(II) shock loads, but TN removal was inhibited by Cu(II) of shock loads of 2 and 5 mg/L, and the performance could not be recovered at 5 mg/L. Furthermore, the TN removal pathway also changed in response to Cu(II) concentrations of 2 and 5 mg/L. Denitrification is more sensitive to Cu(II) shock in SBNR processes. Examination of amoA communities using quantitative PCR showed that the abundance of AOB in the aerobic tank decreased after Cu(II) shock with 5 mg/L, which supported the observed changes in [Formula: see text]-N removal efficiency. The abundance of denitrification genes declined obviously at Cu(II) concentrations of 2 and 5 mg/L, which explained the decreased TN removal efficiency at those concentrations. PMID:25833010

  15. High efficiency removal of 2-chlorophenol from drinking water by a hydrogen-based polyvinyl chloride membrane biofilm reactor

    Energy Technology Data Exchange (ETDEWEB)

    Xia Siqing [State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of Ministry of Education, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Zhang Zhiqiang, E-mail: zhiqiang@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of Ministry of Education, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Zhong Fohua [State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze River Water Environment of Ministry of Education, College of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Zhang Jiao [School of Civil Engineering and Transportation, Shanghai Technical College of Urban Management, Shanghai 200432 (China)

    2011-02-28

    A continuously stirred hydrogen-based membrane biofilm reactor (MBfR) with polyvinyl chloride (PVC) hollow fiber membrane was investigated for removing 2-chlorophenol (2-CP) from contaminated drinking water. The bioreactor startup was achieved by acclimating the microorganisms from a denitrifying and sulfate-reducing MBfR to the drinking water contaminated by 2-CP. The effects of some major factors, including 2-CP loading, H{sub 2} pressure, nitrate loading, and sulfate loading, on the removal of 2-CP by the MBfR were systematically investigated. Although the effluent 2-CP concentration increased with its increasing influent loading, the removing efficiency of 2-CP by the MBfR could be up to 94.7% under a high influent loading (25.71 mg/L d). The removing efficiency of 2-CP by the MBfR could be improved by higher H{sub 2} pressure, and lower influent nitrate concentration and sulfate concentration. A high H{sub 2} pressure can assure enough available H{sub 2} as the electron donor for 2-CP degradation. The competition in the electron donor made nitrate and sulfate inhibit the degradation of 2-CP in the MBfR. The electron flux analyses indicated that the degradation of 2-CP only accounted for a small part of electron flux, and the autohydrogenotrophic bacteria in the MBfR were highly efficient for the 2-CP removal.

  16. Effect of inorganic carbon on the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor.

    Science.gov (United States)

    Chen, You-Peng; Li, Shan; Fang, Fang; Guo, Jin-Song; Zhang, Qiang; Gao, Xu

    2012-12-01

    Ammonia-oxidizing bacteria (AOB) and anaerobic ammonia-oxidizing bacteria (AnAOB) are autotrophic microorganisms. Inorganic carbon (IC) is their main carbon source. The effects of IC limitation on AOB and AnAOB in the completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor (SBBR) were examined. The optimal IC concentration in the influent was investigated. The start-up time of the CANON process from the activated sludge in the SBBR was 80 d under controlled free ammonia (FA) conditions and sufficient IC source. The AOB and AnAOB activities were limited by an IC concentration of 50 mg-C-L(-1) in the influent, whilst the nitrogen loading rate (NLR) was 200 mg-N x L(-1) x d(-1). The experiment on recovering the influent IC showed that AOB and AnAOB activities were affected by the IC limitation, and not by the pH or FA, at 200mg-N x L(-1) x d(-1) NLR and 50mg-C x L(-1) IC in the CANON process. The activities were recovered by increasing the IC concentration in the influent. From an economic point of view, the optimal IC concentration in the influent was 250mg-C x L(-1) at 200mg-N x L(-1) x d(-1) NLR in this CANON system. PMID:23437661

  17. High efficiency removal of 2-chlorophenol from drinking water by a hydrogen-based polyvinyl chloride membrane biofilm reactor

    International Nuclear Information System (INIS)

    A continuously stirred hydrogen-based membrane biofilm reactor (MBfR) with polyvinyl chloride (PVC) hollow fiber membrane was investigated for removing 2-chlorophenol (2-CP) from contaminated drinking water. The bioreactor startup was achieved by acclimating the microorganisms from a denitrifying and sulfate-reducing MBfR to the drinking water contaminated by 2-CP. The effects of some major factors, including 2-CP loading, H2 pressure, nitrate loading, and sulfate loading, on the removal of 2-CP by the MBfR were systematically investigated. Although the effluent 2-CP concentration increased with its increasing influent loading, the removing efficiency of 2-CP by the MBfR could be up to 94.7% under a high influent loading (25.71 mg/L d). The removing efficiency of 2-CP by the MBfR could be improved by higher H2 pressure, and lower influent nitrate concentration and sulfate concentration. A high H2 pressure can assure enough available H2 as the electron donor for 2-CP degradation. The competition in the electron donor made nitrate and sulfate inhibit the degradation of 2-CP in the MBfR. The electron flux analyses indicated that the degradation of 2-CP only accounted for a small part of electron flux, and the autohydrogenotrophic bacteria in the MBfR were highly efficient for the 2-CP removal.

  18. Fungal biofilm reactor improves the quality of a fusion protein GLA::GFP produced by Aspergillus oryzae

    OpenAIRE

    Zune, Quentin; Delepierre, Anissa; Bauwens, Julien; Francis, Frédéric; Toye, Dominique; Punt, Peter; Thonart, Philippe; Delvigne, Frank

    2015-01-01

    Fungal biofilm is known to promote the excretion of secondary metabolites, in accordance with solid-state related physiological mechanisms. In this work, the potentialities of fungal biofilm will be investigated in the context of the production of a Gla::GFP fusion protein by Aspergillus oryzae. Since the production of this protein is under the control of the promoter glaB, specifically induced in solid-state fermentation, biofilm mode of culture is expected to enhance the global productivity...

  19. Development of a web-based platform for the systematic and large-scale study of microbial adhesionand biofilms

    OpenAIRE

    Azevedo, N. F.; Lourenço, Anália; Pereira, Maria Olívia; Veiga, Nuno; Machado, Idalina

    2010-01-01

    High-throughput biofilm studies are rapidly accumulating a large amount of omics-scale data. In other biological areas that deal with large datasets, such as genomics or proteomics, ways for simplifying the visualization and understanding of the obtained results have already been developed. As such, we have started the development of a Web-based platform for analogous management, visualization and exploration of biofilm data. This platform, named Biofomics, is comprised of three m...

  20. Development of demonstration advanced thermal reactor

    International Nuclear Information System (INIS)

    The design of the advanced thermal demonstration reactor with 600 MWe output was started in 1975. In order to make the compact core, 648 fuel assemblies, each comprising 36 fuel rods, were used, and the mean channel output was increased by 20% as compared with the prototype reactor. The heavy water dumping mechanism for the calandria was abolished. Advanced thermal reactors are suitable to burn plutonium, since the control rod worth does not change, the void reactivity coefficient of coolant shifts to the negative side, and the harmful influence of high order plutonium is small. The void reactivity coefficient is nearly zero, the fluctuation of output in relation to pressure disturbance is small, and the local output change of fuel by the operation of control rods is small, therefore, the operation following load change is relatively easy. The coolant recirculation system is of independent loop construction dividing the core into two, and steam and water are separated in respective steam drums. At present, the rationalizing design is in progress by the leadership of the Power Reactor and Nuclear Fuel Development Corp. The outline of the demonstration reactor, the reactor construction, the nuclear-thermal-hydraulic characteristics and the output control characteristics are reported. (Kako, I.)

  1. Luncheon address: Development of the CANDU reactor

    International Nuclear Information System (INIS)

    The paper is a highlight of the some of the achievements in the development of the CANDU Reactor, taken from the book Canada Enters the Nuclear Age. The CANDU reactor is one of Canada's greatest scientific/engineering achievements, that started in the 1940's and bore fruit with the reactors of the 60's, 70's, and 80's. The Government decided in the 1950's to proceed with a demonstration nuclear power reactor (NPD), AECL invited 7 Canadian corporations to bid on a contract to design and construct the NPD plant. General Electric was selected. A utility was also essential for participation and Ontario Hydro was chosen. In May 1957 it was concluded that the minimum commercial size would be about 200MWe and it should use horizontal pressure tubes to contain the fuel and pressurized heavy water coolant. The book also talks of standard out-reactor components such as pumps, valves, steam generators and piping. A major in-reactor component of interest was the fuel, fuel channels and pressure tubes. A very high level of cooperation was required for the success of the CANDU program

  2. Comparative studies on biofilm development by Aspergillus niger on polyester sheet and muslin cloth

    OpenAIRE

    Nitin Verma; Mukesh C.Bansal; Vivek kumar

    2010-01-01

    Filamentous fungi are naturally adapted to adhere on the surfaces in submerged cultures. Cell adhesion plays a vital role in biofilm development in submerged cultures. The objective of the present study is to evaluate the growth rate of Aspergillus on the polyester sheet and muslin cloth with and without solid support in submerged cultures. The growth of A. niger was observed to be high in polyester sheet when compared with muslin cloth.

  3. Membrane biofilm development improves COD removal in anaerobic membrane bioreactor wastewater treatment

    OpenAIRE

    Smith, Adam L; Skerlos, Steven J; Raskin, Lutgarde

    2015-01-01

    Membrane biofilm development was evaluated to improve psychrophilic (15°C) anaerobic membrane bioreactor (AnMBR) treatment of domestic wastewater. An AnMBR containing three replicate submerged membrane housings with separate permeate collection was operated at three levels of membrane fouling by independently controlling biogas sparging for each membrane unit. High membrane fouling significantly improved permeate quality, but resulted in dissolved methane in the permeate at a concentration tw...

  4. Reactor physics needs in developing countries

    International Nuclear Information System (INIS)

    The aim of this paper the identification of needs on Reactor Physics in developing countries embarked in the installation and later on in the operation of Commercial Nuclear Power Plants. In this context the main task of Reactor Physics should be focused in the application of Physical models with inclusion of thermohydraulic process to solve the various realistic problems which appear to ensure a safe, economical and reliable core design and reactor operation. The first part of the paper deals with the scope of Reactor Physics and its interrelation with other disciplines as seen from the view point of developing countries possibilities. Needs requiring a quick response, i.e., those demands coming during the development of a specific Nuclear Power Plant Project, are summarized in the second part of the lecture. Plant startup has been chosen as reference to separate two categories of requirements: Requirements prior to startup phase include reactor core verification, licensing aspects review and study of fuel utilization alternatives; whereas the period during and after startup mainly embraces codes checkup and normalization, core follow-up and long term prediction

  5. High-effective denitrification of low C/N wastewater by combined constructed wetland and biofilm-electrode reactor (CW-BER).

    Science.gov (United States)

    He, Yuan; Wang, Yuhui; Song, Xinshan

    2016-03-01

    The low denitrification effect on constructed wetlands (CWs) treating low carbon to nitrogen ratio (C/N) wastewater was a problem. In this study, a novel coupled system by installing CW and biofilm-electrode reactor (CW-BER) was developed. In this system, the heterotrophic and autotrophic denitrifying bacteria all played their roles in denitrification process. The system was investigated systematically with simulated wastewater at different C/Ns, electric current intensities (I), hydraulic retention times (HRTs), and pH. Results showed that the optimum running conditions were C/N=0.75-1, I=15 mA, HRT=12 h, and pH=7.5. The highest removal efficiency of NO3-N and TN at the best conditions was respectively 63.03% and 98.11% for CW-BER. Also, the TN and NO3-N enhancive removal efficiency of CW-BER was 23.26% and 24.20%, respectively. No residual organic carbon source was detected in final effluent at the best parameters. PMID:26735879

  6. Development of advanced nuclear reactors in Russia

    International Nuclear Information System (INIS)

    Several advanced reactor designs have been so far developed in Russia. The AES-91 and AES-92 plants with the VVER-1000 reactors have been developed at the beginning of 1990. However, the former design has been built in China and the latest which is certified meeting European Utility Requirements is being built in India. Moreover, the model VVER-1500 reactor with 50-60 MWd/t burn-up and an enhanced safety was being developed by Gidropress about 2005, excepting to be completed in 2007. But, this schedule has slipped in favor of development of the AES-2006 power plant incorporating a third-generation standardized VVER-1200 reactor of 1170 MWe. This is an evolutionary development of the well-proven VVER-1000 reactor in the AES-92 plant, with longer life, greater power and efficiency and its lead units are being built at Novovoronezh II, to start operation in 2012-13. Based on Atomenergoproekt declaration, the AES-2006 conforms to both Russian standards and European Utility Requirements. The most important features of the AES-2006 design are mentioned as: a design based on the passive safety systems, double containment, longer plant service life of 50 years with a capacity factor of 92%, longer irreplaceable components service life of 60 years, a 28.6% lower amount of concrete and metal, shorter construction time of 54 months, a Core Damage Frequency of 1x10-7/ year and lower liquid and solid wastes by 70% and 80% respectively. The presented paper includes a comparative analysis of technological and safety features, economic parameters and environmental impact of the AES-2006 design versus the other western advanced reactors. Since the Bushehr phase II NPP and several other NPPs are planning in Iran, such analysis would be of a great importance

  7. Feedback of reactor operating data to nuclear methods development

    International Nuclear Information System (INIS)

    The problems in obtaining power reactor data for reliable nuclear methods development and the major sources of power reactor data for this purpose are reviewed. Specific examples of the use of power reactor data in nuclear methods development are discussed. The paper concludes with recommendations on the key elements of an effective program to use power reactor data in nuclear methods development

  8. The development of fast reactors in France

    International Nuclear Information System (INIS)

    Only minor changes were introduced in the French nuclear programme by the new government in 1981. The operating conditions of Rapsodie were very satisfactory up to January 1982. After a leak in the double primary jacket (nitrogen circuit) the reactor was shut down for investigations. Phenix is continuing to operate smoothly. Construction of Super Phenix (Creys Malville power plant) is proceeding normally though with some delay. The studies for the future (after Creys Malville) are following their way both for the Project 1500 (Super Phenix 2) and for the specific plants of the fuel cycle. Research and development are largely directed toward Super Phenix 1 needs and the prospects of Super Phenix 2. International cooperation remains very intensive. The financial resources devoted to the development of fast reactors are globally stable. Including fuel cycle and safety (but excluding the Phenix operation) about 1300 millions of francs will be devoted to fast reactors by the C.E.A. in 1982. (author)

  9. BN-1200 reactor power unit design development

    International Nuclear Information System (INIS)

    In February 2010, the RF Government has approved the Federal Target Program “New Generation Nuclear Power Technologies for the Period of 2010-2015 and for the long-term up to 2020”. Within this Program, the R&D work for new generation 1200MWe sodium fast reactor is provided. The BN-1200 design is based on the combination of approved and innovative technical decisions, which allow: – reliable power unit with large BN reactor to be developed in a short period of time for commercial construction as a part of closed nuclear fuel cycle; – qualitatively new technical level of power unit to be provided according to generation 4 NPP requirements. The paper characterizes the activities performed now for the power unit design in various areas: – power unit design; – reactor plant (RP) detailed design development; – R&D work to validate the RP system and equipment; – code upgrading and verification; – safety validation. (author)

  10. Ozo-Dyes mixture degradation in a fixed bed biofilm reactor packed with volcanic porous rock

    International Nuclear Information System (INIS)

    Textile industries discharge great amounts of dyes and dyeing-process auxiliaries, which pollute streams and water bodies. Several dyes, especially the ones containing the azo group, can cause harmful effects to different organisms including humans. Through bacterial and mammalian tests, azo dyes or their derived aromatic amines have shown cell genotoxicity. The purpose of this work was to evaluate the effect of air flow rate on azo-dyes mixture biodegradation by a microbial community immobilized in a packed bed reactor. (Author)

  11. Ozo-Dyes mixture degradation in a fixed bed biofilm reactor packed with volcanic porous rock

    Energy Technology Data Exchange (ETDEWEB)

    Contreras-Blancas, E.; Cobos-Vasconcelos, D. de los; Juarez-Ramirez, C.; Poggi-Varaldo, H. M.; Ruiz-Ordaz, N.; Galindez-Mayer, J.

    2009-07-01

    Textile industries discharge great amounts of dyes and dyeing-process auxiliaries, which pollute streams and water bodies. Several dyes, especially the ones containing the azo group, can cause harmful effects to different organisms including humans. Through bacterial and mammalian tests, azo dyes or their derived aromatic amines have shown cell genotoxicity. The purpose of this work was to evaluate the effect of air flow rate on azo-dyes mixture biodegradation by a microbial community immobilized in a packed bed reactor. (Author)

  12. Applying moving bed biofilm reactor for removing linear alkylbenzene sulfonate using synthetic media

    OpenAIRE

    Jalaleddin Mollaei; Seyed Bagher Mortazavi; Ahmad Jonidi Jafari

    2015-01-01

    Detergents and problems of their attendance into water and wastewater cause varied difficulties such as producing foam, abnormality in the growth of algae, accumulation and dispersion in aqueous environments. One of the reactors was designated with 30% of the media with the similar conditions exactly same as the other which had filling rate about 10 %, in order to compare both of them together. A standard method methylene blue active substance was used to measure anionic surfactant. The co...

  13. [Analysis of Precipitation Formation in Biofilm CANUN Reactor and its effect on Nitrogen Removal].

    Science.gov (United States)

    Fu, Kun-ming; Wang, Hui-fang; Zuo, Zao-rong; Qiu, Fu-guo

    2015-08-01

    A CANON reactor with polymeric sponge as carrier was started by incubating sludge from another CANON reactor using synthetic inorganic ammonia-rich wastewater as raw water, and was operated at 30 degrees C +/- 1 degree C, pH 6.92-8.52. The precipitation on the surface of carriers was studied in this paper, including influence on nitrogen removal efficiency, causes for formation and composition. The results showed that: (1) the precipitation could influence the distribution of substrate to undermine the performance of CANON reactors; (2) the precipitation was calcium carbohydrate; (3) the production of precipitation may be a common result of four effects that were the regulatory effect of microorganisms on pH value, stripping effect, the role of extracellular polymers, adsorption of sponge and simultaneous chemical, biological reactions; (4) once the precipitation formed, it was difficult to recover to normal. Therefore, some measures are necessary to avoid precipitation, including: (1) raw water pretreatment to reduce the concentrations of Ca2 and Mg2. (2) ensuring short-cut nitrification stable, which could avoid increase of pH because of reduction of DO; (3) we can choose other carriers to reduce precipitation, which must ensure the optimal total nitrogen removal performance and stable short-cut nitrification. PMID:26592023

  14. Upgrading of a wastewater treatment plant with a hybrid moving bed biofilm reactor (MBBR

    Directory of Open Access Journals (Sweden)

    Luigi Falletti

    2014-11-01

    Full Text Available The wastewater treatment plant of Porto Tolle (RO, Italy was originally projected for 2200 person equivalent (p.e. and it was made of a pumping station, an activated sludge oxidation tank (395 m3, a settler (315 m3, and two sludge drying beds. Other units were not yet in use in 2008: a fine screen, a sand and grit removal unit, a new settler (570 m3, a disinfection tank and a sludge thickener. Effective hydraulic load was 245% higher, organic load was 46% lower and nitrogen load was 39% higher than project values. Moreover, higher pollutant loads and more strict emission limits for nitrogen were expected. So the plant was upgraded: the old settler was divided into a sector of 180 m3 that was converted into a predenitrification tank, and a sector of 100 m3 that was converted into a hybrid MBBR tank filled with 50% AnoxKaldnesTM K3 carriers; the new settler was connected to the hybrid MBBR, and the other units were started. Biofilm growth was observed two months after plant restarting, its concentration reached 1.1 gTS/m2 (0.26 kgTS/m3, while activated sludge concentration was 2.0–2.8 kgTSS/m3 in all the period of study. The upgraded plant treats 1587 m3/d wastewater with 57 kgCOD/d, 23 kgBOD/d and 13.3 kgN/d, and has a significant residual capacity; the effluent respects all emission limits.

  15. Selection and identification of a bacterial community able to degrade and detoxify m-nitrophenol in continuous biofilm reactors.

    Science.gov (United States)

    González, Ana J; Fortunato, María S; Papalia, Mariana; Radice, Marcela; Gutkind, Gabriel; Magdaleno, Anahí; Gallego, Alfredo; Korol, Sonia E

    2015-12-01

    Nitroaromatics are widely used for industrial purposes and constitute a group of compounds of environmental concern because of their persistence and toxic properties. Biological processes used for decontamination of nitroaromatic-polluted sources have then attracted worldwide attention. In the present investigation m-nitrophenol (MNP) biodegradation was studied in batch and continuous reactors. A bacterial community able to degrade the compound was first selected from a polluted freshwater stream and the isolates were identified by the analysis of the 16S rRNA gene sequence. The bacterial community was then used in biodegradation assays. Batch experiments were conducted in a 2L aerobic microfermentor at 28 °C and with agitation (200 rpm). The influence of abiotic factors in the biodegradation process in batch reactors, such as initial concentration of the compound and initial pH of the medium, was also studied. Continuous degradation of MNP was performed in an aerobic up-flow fixed-bed biofilm reactor. The biodegradation process was evaluated by determining MNP and ammonium concentrations and chemical oxygen demand (COD). Detoxification was assessed by Vibrio fischeri and Pseudokirchneriella subcapitata toxicity tests. Under batch conditions the bacterial community was able to degrade 0.72 mM of MNP in 32 h, with efficiencies higher than 99.9% and 89.0% of MNP and COD removals respectively and with concomitant release of ammonium. When the initial MNP concentration increased to 1.08 and 1.44 mM MNP the biodegradation process was accomplished in 40 and 44 h, respectively. No biodegradation of the compound was observed at higher concentrations. The community was also able to degrade 0.72 mM of the compound at pH 5, 7 and 9. In the continuous process biodegradation efficiency reached 99.5% and 96.8% of MNP and COD removal respectively. The maximum MNP removal rate was 37.9 gm(-3) day(-1). Toxicity was not detected after the biodegradation process. PMID:26283285

  16. Hydrodynamic and biological study of a methanogenic bio-film process: the inverse turbulent bed reactor; Etude hydrodynamique et biologique d'un procede de methanisation a biofilm: le reacteur a lit turbule inverse

    Energy Technology Data Exchange (ETDEWEB)

    Michaud, S.

    2001-11-01

    This work deals with the operation and start-up of a turbulent bed reactor with ExtendospheresO as a support, for the anaerobic treatment of a food process wastewater. An hydrodynamic study was carried out to characterise the liquid flow and mixing with this carrier of small size (147 {mu}m) and density (0.7). Phase behaviour during fluidizing gas injection can be described by an homogeneous liquid-solid pseudo-fluid whose apparent viscosity depends on the solid concentration. A biological study showed that the initial contact between cells and particles caused a physiological adaptation of microorganisms to the presence of solid after a transitory inhibition of methane production. The methane yield has been showed to be an interesting parameter to monitor bio-film formation and detachment. A low hydraulic retention time during the start-up period has been decisive to reduce the lag-period during carrier colonization. A robust continuous operation of the reactor has been obtained using a pH-controlled feeding. Gas velocity has been shown to be an important parameter to control cells concentration, density and durability of the bio-film. (author)

  17. Biochemical composition and changes of extracellular polysaccharides (ECPS) produced during microphytobenthic biofilm development (Marennes-Oléron, France).

    OpenAIRE

    Pierre, Guillaume; Graber, Marianne; Rafiliposon, Beby; Dupuy, Christine; Orvain, Francis; De Crignis, Margot; Maugard, Thierry

    2012-01-01

    The main goal of this work was to study the dynamics and biochemical composition of ExtraCellular Polysaccharides (ECPS), a fraction of the Extracellular Polymeric Substances (EPS) produced during the development of a microphytobenthic biofilm in a European intertidal mudflat (Marennes-Oléron Bay, France) during winter. Microphytobenthic biomass was surveyed during four consecutive emersion periods to confirm the biofilm growth. Bacteria abundance was also checked considering the importance o...

  18. Influence of O Polysaccharides on Biofilm Development and Outer Membrane Vesicle Biogenesis in Pseudomonas aeruginosa PAO1

    OpenAIRE

    Murphy, Kathleen; Park, Amber J.; Hao, Youai; Brewer, Dyanne; Lam, Joseph S.; Khursigara, Cezar M.

    2014-01-01

    Pseudomonas aeruginosa is a common opportunistic human pathogen known for its ability to adapt to changes in its environment during the course of infection. These adaptations include changes in the expression of cell surface lipopolysaccharide (LPS), biofilm development, and the production of a protective extracellular exopolysaccharide matrix. Outer membrane vesicles (OMVs) have been identified as an important component of the extracellular matrix of P. aeruginosa biofilms and are thought to...

  19. The cidA murein hydrolase regulator contributes to DNA release and biofilm development in Staphylococcus aureus

    OpenAIRE

    Rice, Kelly C.; Mann, Ethan E.; Endres, Jennifer L.; Weiss, Elizabeth C.; Cassat, James E.; Smeltzer, Mark S.; Bayles, Kenneth W.

    2007-01-01

    The Staphylococcus aureus cidA and lrgA genes have been shown to affect cell lysis under a variety of conditions during planktonic growth. It is hypothesized that these genes encode holins and antiholins, respectively, and may serve as molecular control elements of bacterial cell lysis. To examine the biological role of cell death and lysis, we studied the impact of the cidA mutation on biofilm development. Interestingly, this mutation had a dramatic impact on biofilm morphology and adherence...

  20. Experimental biofilms within drinking water treatment plant origin; evaluation of nutrient concentration and temperature influences upon their development

    OpenAIRE

    Farkas, Anca; Brînduşa BOCOS; Tigan, Stefan; Corina MURESAN; Romeo CHIRA

    2009-01-01

    From the planktonic free-floating state, microorganisms pass to the solid state, the biofilm, cells being strongly attached to each other and usually to the interface. This changing in cells’ behavior induces surface colonization and complex interactions development within the biofilm. If the biofilm’s role into the natural aquatic habitats is, undoubtedly, a positive one, consisting in water self-purification, drinking water pipe networks biofouling can be responsible for a wide range of wat...

  1. Fast Reactor Development Strategy in China

    International Nuclear Information System (INIS)

    • China devotes herself to the peaceful use of nuclear to meet the growing energy demand. Proper amount of nuclear power plants could provide clean energy with low risk. • Fast reactor is a promising technology to ensure the sustainable development of nuclear energy, which can produce new fuel from depleted uranium and burn the long-life radioactive waste at the same time. It is expected that fast reactor will provide enough clean power to people for a long term in the future

  2. Nuclear power reactor development in Japan

    International Nuclear Information System (INIS)

    Based on the current situation in Japan that nearly 40 LWRs (PWR/BWR nearly 50/50) have been operating with excellent performance; the number of un-intended shutdown is the smallest, leaker fuel is practically zero and thus coolant activity is the lowest in the world, they proceed to introduce advanced LWR (ALWR) of 1,300 MWe in early '90s, followed by the further improvement into higher duty LWR (so-called next generation LWR). National program for advanced thermal reactor (ATR) and FBR development has been steadily performed; a demonstration reactor of ATR and a prototype of FBR are under construction, which are to be put into operation by middle 1990s. Lately-revised high temperature gas cooled reactor program for process heat generation is put into practice in 1989 and its experimental reactor to be used also for irradiation facility will be completed 7 years later. Smaller-size LWR and so-called 'inherent safety type reactor' have also been interested. Overview on those activities are presented. (author)

  3. Development of plutonium: Fast Neutrons Reactors option

    International Nuclear Information System (INIS)

    Phenix reactor is shortly described with combustible assembly with some operational data. 'CAPRA'(Plutonium Enhance Consumption in Fast Reactors) is an R and D program for the development of an optimized combustible for fast reactors for burning more plutonium. Three ways are tested: a 45% Pu concentration in an oxide fuel keeping actual fabrication and reprocessing options giving a 80 kg/TWh Pu consumption, a fuel without U238 but with a W or a Mo matrix with problems of reprocessing and core reactivity giving a 110 kg/TWh Pu consumption, and a nitride fuel with an up to 65% Pu concentration giving a 90 to 100 kg/TWh Pu consumption. (A.B.)

  4. Fast Reactor Fuel Development in Europe

    International Nuclear Information System (INIS)

    Research and development of minor-actinide-bearing fuels in Europe has made significant progress, with a number of scoping irradiation tests made on a number of candidate fuels foreseen for fast reactors and dedicated minor actinide transmutation systems, e.g. the accelerator driven system. Currently, efforts concentrate on uranium based fuels, as the deployment of fast reactor fleets requires Pu generation in order to achieve sustainability. Both homogeneous and heterogeneous concepts for minor actinide reactor recycling are considered. In the former, the minor actinides are added in small quantities to the mixed oxide fuel, while in the latter, the minor actinides are loaded in significant quantities in UO2. Irradiation programmes to test these concepts for pellet and SPHEREPAC fuel configurations are under way. (author)

  5. Development of smart nuclear instrumentation for reactors

    International Nuclear Information System (INIS)

    Variety of nuclear instruments are required for different applications in reactors such as reactor start-up, reactor protection and regulating system, area monitoring, failed fuel detection, stack monitoring etc. Attempts are made to develop a standardized microcomputer based hardware for configuring different types of instruments. PC architecture is chosen due to easy availability of components/boards and software. These instruments have dual redundant Network Interface Cards for connecting to a Primary Radiation Data LAN which in turn can be connected to Plant Information Bus through Gateways. These SMART instruments can be tested/calibrated through specific commands from remote computers connected over the LAN. This paper describes the various issues involved and the design details. (author)

  6. An in vitro dynamic microcosm biofilm model for caries lesion development and antimicrobial dose-response studies.

    Science.gov (United States)

    Maske, T T; Brauner, K V; Nakanishi, L; Arthur, R A; van de Sande, F H; Cenci, M S

    2016-03-01

    Some dynamic biofilm models for dental caries development are limited as they require multiple experiments and do not allow independent biofilm growth units, making them expensive and time-consuming. This study aimed to develop and test an in vitro dynamic microcosm biofilm model for caries lesion development and for dose-response to chlorhexidine. Microcosm biofilms were grown under two different protocols from saliva on bovine enamel discs for up to 21 days. The study outcomes were as follows: the percentage of enamel surface hardness change, integrated hardness loss, and the CFU counts from the biofilms formed. The measured outcomes, mineral loss and CFU counts showed dose-response effects as a result of the treatment with chlorhexidine. Overall, the findings suggest that biofilm growth for seven days with 0.06 ml min(-1) salivary flow under exposure to 5% sucrose (3 × daily, 0.25 ml min(-1), 6 min) was suitable as a pre-clinical model for enamel demineralization and antimicrobial studies. PMID:26905384

  7. Development of equipment for in situ studies of biofilm in hot water systems

    DEFF Research Database (Denmark)

    Bagh, Lene Karen; Albrechtsen, Hans-Jørgen; Arvin, Erik; Schmidt-Jørgensen, Finn

    1999-01-01

    plugs was made of the same material as used in the hot water system and the test plugs were flush with the inner surface of the tank. When the operating shaft was removed from the tank, biofilm could be collected. In the distribution system, biofilm samples were collected from test plugs inserted in...... sampling ports in a by-pass. Heterotrophic plate counts (HPC) revealed 10(4)-10(6) CFU cm(-2) on the test plugs in the hot water system after an exposure period of 7 d. The number of bacteria was not influenced by the location of the plug within each cluster of plugs in the distribution system, or at......New equipment was developed for in situ studies of biofilms in hot water tanks and hot water pipes under normal operation and pressure. Sampling ports were installed in the wall of a hot water tank and through these operating shafts were inserted with a test plug in the end. The surface of the test...

  8. Biohybrid nanostructured iron oxide nanoparticles and Satureja hortensis to prevent fungal biofilm development.

    Science.gov (United States)

    Anghel, Ion; Grumezescu, Alexandru Mihai; Holban, Alina Maria; Ficai, Anton; Anghel, Alina Georgiana; Chifiriuc, Mariana Carmen

    2013-01-01

    Cutaneous wounds are often superinfected during the healing process and this leads to prolonged convalescence and discomfort. Usage of suitable wound dressings is very important for an appropriate wound care leading to a correct healing. The aim of this study was to demonstrate the influence of a nano-coated wound dressing (WD) on Candida albicans colonization rate and biofilm formation. The modified WD was achieved by submerging the dressing pieces into a nanofluid composed of functionalized magnetite nanoparticles and Satureja hortensis (SO) essential oil (EO). Chemical composition of the EO was established by GC-MS. The fabricated nanostructure was characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Differential Thermal Analysis (DTA) and Fourier Transform-Infrared Spectroscopy (FT-IR). The analysis of the colonized surfaces using (Scanning Electron Microscopy) SEM revealed that C. albicans adherence and subsequent biofilm development are strongly inhibited on the surface of wound dressing fibers coated with the obtained nanofluid, comparing with regular uncoated materials. The results were also confirmed by the assay of the viable fungal cells embedded in the biofilm. Our data demonstrate that the obtained phytonanocoating improve the resistance of wound dressing surface to C. albicans colonization, which is often an etiological cause of local infections, impairing the appropriate wound healing. PMID:24009022

  9. Biohybrid Nanostructured Iron Oxide Nanoparticles and Satureja hortensis to Prevent Fungal Biofilm Development

    Directory of Open Access Journals (Sweden)

    Mariana Carmen Chifiriuc

    2013-09-01

    Full Text Available Cutaneous wounds are often superinfected during the healing process and this leads to prolonged convalescence and discomfort. Usage of suitable wound dressings is very important for an appropriate wound care leading to a correct healing. The aim of this study was to demonstrate the influence of a nano-coated wound dressing (WD on Candida albicans colonization rate and biofilm formation. The modified WD was achieved by submerging the dressing pieces into a nanofluid composed of functionalized magnetite nanoparticles and Satureja hortensis (SO essential oil (EO. Chemical composition of the EO was established by GC-MS. The fabricated nanostructure was characterized by X-ray Diffraction (XRD, Transmission Electron Microscopy (TEM, Differential Thermal Analysis (DTA and Fourier Transform-Infrared Spectroscopy (FT-IR. The analysis of the colonized surfaces using (Scanning Electron Microscopy SEM revealed that C. albicans adherence and subsequent biofilm development are strongly inhibited on the surface of wound dressing fibers coated with the obtained nanofluid, comparing with regular uncoated materials. The results were also confirmed by the assay of the viable fungal cells embedded in the biofilm. Our data demonstrate that the obtained phytonanocoating improve the resistance of wound dressing surface to C. albicans colonization, which is often an etiological cause of local infections, impairing the appropriate wound healing.

  10. Developments at the inter faculty reactor institute

    International Nuclear Information System (INIS)

    The Inter faculty Reactor Institute is part of the Delft University of Technology. It is a central training and research facility for the Dutch Universities and it has a national function for providing expertise in nuclear reactors, ionizing radiation and radio nuclides to the academic community. The institute operates a 2 MW pool type unclear reactor with a maximum neutron flux of 1.5 x 1017 m -2s-1, a 3 MV pulsed electron accelerator, different positron sources and other experimental facilities for research with radio nuclides and radiation. In 5 scientific departments an extensive research program is carried out in the areas of neutron physics, Moessbauer spectrometry, radiochemistry, radiation chemistry, reactor physics and nuclear technology. The applications are mainly in the fields of materials science, environment and biology, sensors and instrumentation, energy and sustainable production technologies. On January first 1997 the institute obtained a new licence, which allowed the change from HEU to LEU. This change has been prepared and initiated. During a period of 4 years the total inventory of our core will be changed from HEU to LEU. In July 1997 the construction started for a new beam hall. In this building existing instruments will be positioned along with a number of new instruments that are currently being developed. The new instruments are in the first place connected with a newly developed intense positron source, which is connected to the reactor. Two new instruments are connected to this source: a positron - electron microscope and a 2-D angular correlation measuring set-up. During the past year new plans for future R and D have been initiated. The development started with an assessment of the quality of our R and D quality. In this process first a yardstick for quality was developed and used in a self assessment. Subsequently the Royal Dutch Academy of Science installed a panel of internationally recognised experts. They made the assessment. The

  11. Morphological observation and microbial population dynamics in anaerobic polyurethane foam biofilm degrading gelatin

    Directory of Open Access Journals (Sweden)

    Tommaso G.

    2002-01-01

    Full Text Available This work reports on a preliminary study of anaerobic degradation of gelatin with emphasis on the development of the proteolytic biofilm in polyurethane foam matrices in differential reactors. The evolution of the biofilm was observed during 22 days by optical and scanning electron microscopy (SEM analyses. Three distinct immobilization patterns could be observed in the polyurethane foam: cell aggregates entrapped in matrix pores, thin biofilms attached to inner polyurethane foam surfaces and individual cells that have adhered to the support. Rods, cocci and vibrios were observed as the predominant morphologies of bacterial cells. Methane was produced mainly by hydrogenothrophic reactions during the operation of the reactors.

  12. Complete bromate and nitrate reduction using hydrogen as the sole electron donor in a rotating biofilm-electrode reactor.

    Science.gov (United States)

    Zhong, Yu; Li, Xin; Yang, Qi; Wang, Dongbo; Yao, Fubing; Li, Xiaoming; Zhao, Jianwei; Xu, Qiuxiang; Zhang, Chang; Zeng, Guangming

    2016-04-15

    Simultaneous reduction of bromate and nitrate was investigated using a rotating biofilm-electrode reactor (RBER) with graphite carbon (GC) rods as anode and activated carbon fiber (ACF) bonded with steel ring as cathode. In RBER, the community of denitrifying bacteria immobilized on the cathode surface could completely utilize hydrogen (H2) as the electron donor, which was internally produced by the electrolysis of water. The short-term test confirmed that the RBER system could reduce 150-800μg/L bromate to below 10μg/L under autotrophic conditions. The reduced bromate was considered to be roughly equivalent to the amount of bromide in effluent, indicating that bromate was completely reduced to bromide without accumulation of by-products. The long-term test (over 120 days) showed that the removal fluxes of bromate and nitrate could be improved by increasing the electric current and decreasing the hydraulic retention time (HRT). But nitrite in effluent was significantly accumulated when the electric current was beyond 10mA and the HRT was less than 6h. The maximum bromate reduction rate estimated by the Monod equation was 109.12μg/Lh when the electric current was 10mA and HRT was 12h. It was proposed that the electron transfer process in RBER produced H2 on the surface of the ACF cathode, and the microbial cultures attached closely on the cathode which could completely utilize H2 as electron donors for reduction of bromate and nitrate. PMID:26775102

  13. New developments in transportation for research reactors

    International Nuclear Information System (INIS)

    For more than 30 years, Transnucleaire has been performing safely a large number of national and international transports of radioactive material. Transnucleaire has also designed and supplied numerous packagings for all types of nuclear fuel cycle radioactive materials: for front-end and back-end products and for power and research reactors. Since the last meeting held in Bruges, Transnucleaire has been continuously involved in transportation activities for fresh and irradiated materials for research reactors. We are pleased to take the opportunity in this meeting to share with reactor operators, official bodies and other partners, the on-going developments in transportation and associated services. Special attention will be paid to the starting of transports of MTR spent fuel elements to the La Hague reprocessing plant where COGEMA offers reprocessing services on a long-term basis to reactors operators. Detailed information is provided on regulatory issues, which may affect transport activities: evolution of the regulations, real experiences of recent transportation and development of new packaging designs. Options and solutions will be proposed by Transnucleaire to improve the situation for continuation of national and international transports at an acceptable price whilst maintaining an ultimate level of safety (author)

  14. Attached biomass growth and substrate utilization rate in a moving bed biofilm reactor

    Directory of Open Access Journals (Sweden)

    J. J. Marques

    2008-12-01

    Full Text Available A moving bed bioreactor containing cubes of polyether foam immersed in a synthetic wastewater (an aqueous mixture of meat extract, yeast extract, dextrose, meat peptone, ammonium chloride, potassium chloride, sodium chloride, sodium bicarbonate, potassium mono-hydrogen-phosphate and magnesium sulphate was used to evaluate bacterial growth and biomass yield parameters based on Monod's equation. The wastewater was supplied in the bottom of the equipment flowing ascending in parallel with a diffused air current that provided the mixing of the reactor content. Suspended and attached biomass concentration was measured through gravimetric methods. Good agreement was found between experimental kinetic parameters values and those obtained by other researchers. The only significant difference was the high global biomass content about 2 times the values obtained in conventional processes, providing high performance with volumetric loading rates up to 5.5 kg COD/m³/d.

  15. Probiotic lactobacilli inhibit early stages of Candida albicans biofilm development by reducing their growth, cell adhesion, and filamentation.

    Science.gov (United States)

    Matsubara, Victor Haruo; Wang, Yi; Bandara, H M H N; Mayer, Marcia Pinto Alves; Samaranayake, Lakshman P

    2016-07-01

    We evaluated the inhibitory effects of the probiotic Lactobacillus species on different phases of Candida albicans biofilm development. Quantification of biofilm growth and ultrastructural analyses were performed on C. albicans biofilms treated with Lactobacillus rhamnosus, Lactobacillus casei, and Lactobacillus acidophilus planktonic cell suspensions as well as their supernatants. Planktonic lactobacilli induced a significant reduction (p probiotic strain and the biofilm phase. L. rhamnosus supernatants had no significant effect on the mature biofilm (p > 0.05), but significantly reduced the early stages of Candida biofilm formation (p probiotic Lactobacillus on C. albicans entailed both cell-cell interactions and secretion of exometabolites that may impact on pathogenic attributes associated with C. albicans colonization on host surfaces and yeast filamentation. This study clarifies, for the first time, the mechanics of how Lactobacillus species may antagonize C. albicans host colonization. Our data elucidate the inhibitory mechanisms that define the probiotic candicidal activity of lactobacilli, thus supporting their utility as an adjunctive therapeutic mode against mucosal candidal infections. PMID:27087525

  16. Importance of the operating pH in maintaining the stability of anoxic ammonium oxidation (anammox) activity in moving bed biofilm reactors.

    Science.gov (United States)

    Jaroszynski, L W; Cicek, N; Sparling, R; Oleszkiewicz, J A

    2011-07-01

    Two bench-scale parallel moving bed biofilm reactors (MBBR) were operated to assess pH-associated anammox activity changes during long term treatment of anaerobically digested sludge centrate pre-treated in a suspended growth partial nitrification reactor. The pH was maintained at 6.5 in reactor R1, while it was allowed to vary naturally between 7.5 and 8.1 in reactor R2. At high nitrogen loads reactor R2 had a 61% lower volumetric specific nitrogen removal rate than reactor R1. The low pH and the associated low free ammonia (FA) concentrations were found to be critical to stable anammox activity in the MBBR. Nitrite enhanced the nitrogen removal rate in the conditions of low pH, all the way up to the investigated level of 50mg NO(2)-N/L. At low FA levels nitrite concentrations up to 250 mg NO(2)-N/L did not cause inactivation of anammox consortia over a 2-days exposure time. PMID:21565492

  17. Fate of deposited cells in an aerobic binary bacterial biofilm

    International Nuclear Information System (INIS)

    A biofilm is a matrix of microbial cells and their extracellular products that is associated with a solid surface. Previous studies on biofilm development have employed only dissolved compounds as growth limiting substrates, without the influence of microbial species invading from the bulk liquid. The goal of this research project was to quantify the kinetics of processes governing suspended biomass turnover in biofilm systems, and the accompanying effects of suspended cell deposition on biofilm population dynamics. Experiments were conducted with two species of bacteria, Pseudomonas putida ATCC 11172 grown on glucose, and Hyphomicrobium ZV620 grown on methanol. Cryptic growth and particulate hydrolysis studies were evaluated, using combinations of these two bacteria, by measuring the uptake of radiolabelled cell lysis products, under batch conditions. Biofilms studies were performed to investigate bacterial deposition, continual biofilm removal by shear induced erosion, and biofilm ecology. Biofilms were developed in a flow cell reactor, under laminar flow conditions. Bacterial species were differentiated by radioactively labelling each species with their carbon substrate. A mathematical model was developed to predict the biofilm ecology of mixed cultures. The equations developed predict biofilm accumulation, as well as substrate and oxygen consumption. Results indicate that cryptic growth will occur for bacteria growing on their own species soluble lysis products and in some cases, bacteria growing on the soluble lysis products of other species. Particulate hydrolysis only occurred for Pseudomonas putida growing on Pseudomonas putida lysis products, but the lack of particulate hydrolysis occurring in the other studies may have been due to the short experimental period

  18. Pronounced Effect of the Nature of the Inoculum on Biofilm Development in Flow Systems▿

    OpenAIRE

    Kroukamp, Otini; Dumitrache, Romeo G.; Wolfaardt, Gideon M

    2010-01-01

    Biofilm formation renders sessile microbial populations growing in continuous-flow systems less susceptible to variation in dilution rate than planktonic cells, where dilution rates exceeding an organism's maximum growth rate (μmax) results in planktonic cell washout. In biofilm-dominated systems, the biofilm's overall μmax may therefore be more relevant than the organism's μmax, where the biofilm μmax is considered as a net process dependent on the adsorption rate, growth rate, and removal r...

  19. Development and Characterization of an In Vivo Central Venous Catheter Candida albicans Biofilm Model

    OpenAIRE

    Andes, D.; Nett, J.; Oschel, P.; Albrecht, R.; Marchillo, K.; Pitula, A.

    2004-01-01

    Biofilms represent a niche for microorganisms where they are protected from both the host immune system and antimicrobial therapies. Biofilm growth serves as an increasing source of clinical infections. Candida infections are difficult to manage due to their persistent nature and associated drug resistance. Observations made in biofilm research have generally been limited to in vitro models. Using a rat central venous catheter model, we characterized in vivo Candida albicans biofilm developme...

  20. Role of advanced reactors for sustainable development

    International Nuclear Information System (INIS)

    Availability of energy is an important prerequisite for socio-economic development in all parts of the world. Nuclear energy is an essentially unlimited energy resource with the potential to provide energy in the form of electricity, district heat and process heat under environmentally acceptable conditions. However, this potential will be realized only if nuclear power plants can meet the challenges of national safety requirements, economic competitiveness and public acceptance. Worldwide a tremendous amount of experience has been accumulated during development, licensing, construction and operation of nuclear power plants. This experience forms a sound basis for further improvements. Nuclear programmes in Member States are addressing the development of advanced reactors which are intended to have better economics, higher reliability and improved safety. The IAEA, as a global international governmental organization dealing with nuclear power, promotes international information exchange and international co-operation between all countries with their own advanced nuclear power programmes and offers assistance to countries with an interest in exploratory or research programmes. The paper gives an overview about trends in advanced reactor development programmes in Member States and the possible application of advanced reactors for electricity generation and heat production. (author)

  1. Two-step nitrification in a pure moving bed biofilm reactor-membrane bioreactor for wastewater treatment: nitrifying and denitrifying microbial populations and kinetic modeling.

    Science.gov (United States)

    Leyva-Díaz, J C; González-Martínez, A; Muñío, M M; Poyatos, J M

    2015-12-01

    The moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) is a novel solution to conventional activated sludge processes and membrane bioreactors. In this study, a pure MBBR-MBR was studied. The pure MBBR-MBR mainly had attached biomass. The bioreactor operated with a hydraulic retention time (HRT) of 9.5 h. The kinetic parameters for heterotrophic and autotrophic biomasses, mainly nitrite-oxidizing bacteria (NOB), were evaluated. The analysis of the bacterial community structure of the ammonium-oxidizing bacteria (AOB), NOB, and denitrifying bacteria (DeNB) from the pure MBBR-MBR was carried out by means of pyrosequencing to detect and quantify the contribution of the nitrifying and denitrifying bacteria in the total bacterial community. The relative abundance of AOB, NOB, and DeNB were 5, 1, and 3%, respectively, in the mixed liquor suspended solids (MLSS), and these percentages were 18, 5, and 2%, respectively, in the biofilm density (BD) attached to carriers. The pure MBBR-MBR had a high efficiency of total nitrogen (TN) removal of 71.81±16.04%, which could reside in the different bacterial assemblages in the fixed biofilm on the carriers. In this regard, the kinetic parameters for autotrophic biomass had values of YA=2.3465 mg O2 mg N(-1), μm, A=0.7169 h(-1), and KNH=2.0748 mg NL(-1). PMID:26264139

  2. Development and application of reactor noise diagnostics

    International Nuclear Information System (INIS)

    A number of problems in reactor noise diagnostics have been investigated within the framework of the present thesis. The six papers presented cover three relatively different areas, namely the use of analytical calculations of the neutron noise in simple reactor models, some aspects of boiling water reactor (BWR) stability and diagnostics of core barrel motion in pressurized water reactors (PWRs). The noise induced by small vibrations of a strong absorber has been the subject of several previous investigations. For a conventional δ-function source model, the equations can not be linearized in the traditional manner. Thus, a new source model, which is called the ε/d model, was developed. The correct solution has been derived in the ε/d model for both 1-D and 2-D reactor models. Recently, several reactor diagnostic problems have occurred which include a control rod partially inserted into the reactor core. In order to study such problems, we have developed an analytically solvable, axially non-homogenous, 2-D reactor model. This model has also been used to study the noise induced by a rod maneuvering experiment. Comparisons of the noise with the results of different reactor kinetic approximations have yielded information on the validity of the approximations in this relatively realistic model. In case of an instability event in a BWR, the noise may consist of one or several co-existing modes of oscillation and besides the fundamental mode, a regional first azimuthal mode has been observed in e.g. the Swedish BWR Ringhals-1. In order to determine the different stability characteristics of the different modes separately, it is important to be able to decompose the noise into its mode constituents. A separation method based on factorisation of the flux has been attempted previously, but without success. The reason for the failure of the factorisation method is the presence of the local component of the noise and its axial correlation properties. In the paper

  3. Development and application of reactor noise diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Joakim K.H

    1999-04-01

    A number of problems in reactor noise diagnostics have been investigated within the framework of the present thesis. The six papers presented cover three relatively different areas, namely the use of analytical calculations of the neutron noise in simple reactor models, some aspects of boiling water reactor (BWR) stability and diagnostics of core barrel motion in pressurized water reactors (PWRs). The noise induced by small vibrations of a strong absorber has been the subject of several previous investigations. For a conventional {delta}-function source model, the equations can not be linearized in the traditional manner. Thus, a new source model, which is called the {epsilon}/d model, was developed. The correct solution has been derived in the {epsilon}/d model for both 1-D and 2-D reactor models. Recently, several reactor diagnostic problems have occurred which include a control rod partially inserted into the reactor core. In order to study such problems, we have developed an analytically solvable, axially non-homogenous, 2-D reactor model. This model has also been used to study the noise induced by a rod maneuvering experiment. Comparisons of the noise with the results of different reactor kinetic approximations have yielded information on the validity of the approximations in this relatively realistic model. In case of an instability event in a BWR, the noise may consist of one or several co-existing modes of oscillation and besides the fundamental mode, a regional first azimuthal mode has been observed in e.g. the Swedish BWR Ringhals-1. In order to determine the different stability characteristics of the different modes separately, it is important to be able to decompose the noise into its mode constituents. A separation method based on factorisation of the flux has been attempted previously, but without success. The reason for the failure of the factorisation method is the presence of the local component of the noise and its axial correlation properties. In

  4. Developing the MAPLE materials test reactor concept

    International Nuclear Information System (INIS)

    MAPLE-MTR is a new multipurpose research facility being planned by AECL Research as a possible replacement for the 35-year-old NRU reactor. In developing the MAPLE-MTR concept, AECL is starting from the recent design and licensing experience with the MAPLE-X10 reactor. By starting from technology developed to support the MAPLE-X10 design and adapting it to produce a concept that satisfies the requirements of fuel channel materials testing and fuel irradiation programs, AECL expects to minimize the need for major advances in nuclear technology (e.g., fuel, heat transfer). Formulation of the MAPLE-MTR concept is at an early stage. This report describes the irradiation requirements of the research areas, how these needs are translated into design criteria for the project and elements of the preliminary design concept

  5. Experimental development of power reactor intelligent control

    International Nuclear Information System (INIS)

    The US nuclear utility industry initiated an ambitious program to modernize the control systems at a minimum of ten existing nuclear power plants by the year 2000. That program addresses urgent needs to replace obsolete instrumentation and analog controls with highly reliable state-of-the-art computer-based digital systems. Large increases in functionality that could theoretically be achieved in a distributed digital control system are not an initial priority in the industry program but could be logically considered in later phases. This paper discusses the initial development of an experimental sequence for developing, testing, and verifying intelligent fault-accommodating control for commercial nuclear power plant application. The sequence includes an ultra-safe university research reactor (TRIGA) and a passively safe experimental power plant (Experimental Breeder Reactor 2)

  6. The development of breeder reactors in the US

    International Nuclear Information System (INIS)

    This article discusses the early history of breeder development in the US, the early history of the fast reactor in the US, changes during the Carter administration, and the development of LMFBR technology. Topics considered include the intermediate-energy plutonium breeder, the molten plutonium breeder, the aqueous homogeneous reactor, the molten-salt reactor, the liquid metal-fueled reactor, electronuclear breeding, the Experimental Breeder Reactor-I, the Experimental Breeder Reactor-II, the Enrico Fermi Reactor, a programmatic change to ceramic fuel, the South East Fast Oxide Reactor, the sodium void coefficient, the 1000-MWe studies of 1964, the 1000-MWe studies of 1967-1969, the FARET design, the Fast Flux Test Facility, the Clinch River Breeder Reactor (CRBR), the gas-cooled fast breeder, the light-water breeder, materials for cladding and duct walls, and reactor safety. It is pointed out that the Congress opposes the construction of the CRBR, while the Reagan administration strongly supports it

  7. Reactor alarm system development and application issues

    International Nuclear Information System (INIS)

    The new hardware and software technologies, and the need in research reactors for assistance systems in operation and maintenance, have given an appropriate background to develop a computer based system named ''Reactor Alarm System'' (RAS). RAS is a software package, user oriented, with emphasis on production, experiments and maintenance goals. It is designed to run on distributed systems conformed with microcomputers under QNX operating system. RAS main features are: a) Alarm Panel Display; b) Alarm Page; c) Alarm Masking and Inhibition; d) Alarms Color and Attributes; e) Condition Classification; and f) Arrangement Presentation. RAS design allows it to be installed as a part of a computer based Supervision and Control System in new installations or retrofit existing reactor instrumentation systems. The analysis of human factors during development stage and successive user feedback from different applications, brought out several RAS improvements: a) Multiple-copy alarm summaries; b) Improved alarm handling; c) Extended dictionary; and d) Enhanced hardware availability. It has proved successful in providing new capabilities for operators, and also has shown the continuous increase of user-demands, reflecting the expectations placed today on computer-based systems. (author). 6 figs, 1 tabs

  8. Prometheus Reactor I&C Software Development Methodology, for Action

    Energy Technology Data Exchange (ETDEWEB)

    T. Hamilton

    2005-07-30

    The purpose of this letter is to submit the Reactor Instrumentation and Control (I&C) software life cycle, development methodology, and programming language selections and rationale for project Prometheus to NR for approval. This letter also provides the draft Reactor I&C Software Development Process Manual and Reactor Module Software Development Plan to NR for information.

  9. Prometheus Reactor I and C Software Development Methodology, for Action

    International Nuclear Information System (INIS)

    The purpose of this letter is to submit the Reactor Instrumentation and Control (I and C) software life cycle, development methodology, and programming language selections and rationale for project Prometheus to NR for approval. This letter also provides the draft Reactor I and C Software Development Process Manual and Reactor Module Software Development Plan to NR for information

  10. Developing the fuel for research reactors

    International Nuclear Information System (INIS)

    A review of papers dealing with the possibility of research reactor adaptation to moderately and slightly enriched fuel with the 235U content of 45 and 20%, respectively, is presented. The main peculiarities and results of investigations carried out in two main directions, are under consideration: the increase of specific uranium content in traditional fuels (UAlsub(x)-Al, U3O8-Al, U,ZrHsub(x)) by means of improvements in technology and production (USA, FRG and France); the development of new highly dense kinds of fuel, such as U3Si, U3Si-Al, UO2 (USA, France). A conclusion is drawn that the research reactor fuel enrichment may be decreased

  11. 基于神经网络的SBBR系统建模方法%Modeling based on neural network for sequencing batch biofilm reactor system

    Institute of Scientific and Technical Information of China (English)

    卿晓霞; 梁汉超; 周健; 余建平

    2012-01-01

    It is difficult to build the model of sequencing batch biofilm reactor. This problem has been studied and solved by using the neural network technique. The 7-12-3 back-propagation neural network technique is developed for the system with excluding abnormal data according to pauta criterion,adjusting the network connection weights by training samples,monitoring the training process timely with test samples and the LM algorithm. The model output result being compared with actually measured data,the coefficient of COD is 0.857,ammonia is 0.918,and phosphate is 0.942, meeting the modeling requirement of sewage treatment process.%针对序批式生物膜系统难以构建水质模型的问题,采用神经网络技术进行建模方法研究.根据拉伊达准则剔除异常数据,并用训练样本调整网络连接权值,用检验样本实时动态监控训练过程,用LM算法构建了一个7-12-3结构的BP神经网络模型.将模型输出结果与实测数据进行比较,其相关系数分别为ROOD=0.857,RNH4+-N=0.918,RPO43--P=0.942,能够满足污水处理过程建模的要求.

  12. Kinetic modeling and microbial assessment by fluorescent in situ hybridization in anaerobic sequencing batch biofilm reactors treating sulfate-rich wastewater

    Directory of Open Access Journals (Sweden)

    A. J. Silva

    2011-06-01

    Full Text Available This paper reports the results of applying anaerobic sequencing batch biofilm reactors (AnSBBR for treating sulfate-rich wastewater. The reactor was filled with polyurethane foam matrices or with eucalyptus charcoal, used as the support for biomass attachment. Synthetic wastewater was prepared with two ratios between chemical oxygen demand (COD and sulfate concentration (COD/SO4(2- of 0.4 and 3.2. For a COD/SO4(2- ratio of 3.2, the AnSBBR performance was influenced by the support material used; the average levels of organic matter removal were 67% and 81% in the reactors filled with polyurethane foam and charcoal, respectively, and both support materials were associated with similar levels of sulfate reduction (above 90%. In both reactors, sulfate-reducing bacteria (SRB represented more than 65% of the bacterial community. The kinetic model indicated equilibrium between complete- and incomplete-oxidizing SRB in the reactor filled with polyurethane foam and predominantly incomplete-oxidizing SRB in the reactor filled with charcoal. Methanogenic activity seems to have been the determining factor to explain the better performance of the reactor filled with charcoal to remove organic matter at a COD/SO4(2- ratio of 3.2. For a COD/SO4(2- ratio of 0.4, low values of sulfate reduction (around 32% and low reaction rates were observed as a result of the small SRB population (about 20% of the bacterial community. Although the support material did not affect overall performance for this condition, different degradation pathways were observed; incomplete oxidation of organic matter by SRB was the main kinetic pathway and methanogenesis was negligible in both reactors.

  13. 复合生物膜反应器处理低浓度生活污水%Treatment of low concentration domestic sewage by complex biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    丁杰; 刘绍根; 成雄剑

    2012-01-01

    Using complex biofilm reactor to treat low concentration domestic sewage, when the average mass concentration of CODcr, NH3-N and TP in the influent water were 85, 9.5 and 0.86 mg/L, the corresponding indexes in the effluent water were 20, 4.6, 0.41 mg/L respectively, the average removal rates reached 76.5%, 51.6% and 52.3%, which showed a good treatment effect. Besides, complex biofilm reactor has advantages of small floor area, low capital construction investment and low operation cost, the economic benefit is notable.%采用复合生物膜反应器处理低浓度生活污水,在进水CODCr、NH3-N、TP的平均质量浓度分别为85、9.5、0.86 mg/L的情况下,对应水质指标的出水平均质量浓度分别为20、4.6、0.41 mg/L,平均去除率达到76.5%、51.6%、52.3%,取得较好的去除效果.复合生物膜反应器占地面积较小,基建费用和运行费用较低,经济效益明显.

  14. Hydrogenotrophic denitrification process efficiency and the number of denitrifying bacteria (MPN) in the sequencing batch biofilm reactor (SBBR) with platinum and carbon anodes.

    Science.gov (United States)

    Kłodowska, Izabella; Rodziewicz, Joanna; Janczukowicz, Wojciech; Gotkowska-Płachta, Anna; Cydzik-Kwiatkowska, Agnieszka

    2016-04-15

    This work reports on the effect of electric current density and anode material (platinum, carbon) on the concentration of oxidized and mineral forms of nitrogen, on physical parameters (pH, redox potential, electrical conductivity) and the number of denitrifying bacteria in the biofilm (MPN). Experiments were conducted under anaerobic conditions without and with the flow of electric current (with density of 79 mA·m(-2) and 132 mA·m(-2)). Results obtained in the study enabled concluding that increasing density of electric current caused a decreasing concentration of nitrate in the reactor with platinum anode (R1) and carbon anode (R2). Its concentration depended on anode material. The highest hydrogenotrophic denitrification efficiency was achieved in R2 in which the process was aided by inorganic carbon (CO2) that originated from carbon anode oxidation and the electrical conductivity of wastewater increased as a result of the presence of HCO3(-) and CO3(2-) ions. Strong oxidizing properties of the platinum anode (R1) prevented the accumulation of adverse forms of nitrogen, including nitrite and ammonia. The increase in electric current density affected also a lower number of denitrifying bacteria (MPN) in the biofilm in both reactors (R1 and R2). Metal oxides accumulated on the surface of the cathode had a toxic effect upon microorganisms and impaired the production of a hydrogen donor. PMID:26809836

  15. COD, 2,4,6-trichlorophenol (TCP) and toxicity removal from synthetic wastewater in a rotating perforated-tubes biofilm reactor

    International Nuclear Information System (INIS)

    Synthetic wastewater containing different concentrations of 2,4,6-trichlorophenol (TCP) was biologically treated using a novel rotating perforated-tubes biofilm reactor (RTBR) for chemical oxygen demand (COD), TCP and toxicity removal. Performance of the reactor was investigated as function of major operating variables such as the feed TCP and COD concentrations and A/Q (biofilm surface area/feed flow rate) ratio. A Box-Behnken statistical experiment design method was used by considering the feed TCP (0-400 mg L-1), COD (1000-4000 mg L-1) and A/Q ratio (23-163 m2 d m-3) as the independent variables while percent TCP, COD, and toxicity removals were the objective functions. The results were correlated with the quadratic model since this was found to be the most suitable one. Response function coefficients were determined by correlating the experimental data with the response function. Percent TCP, COD and toxicity removals estimated from the response functions were in good agreement with the experimental results. TCP, COD and toxicity removals increased with increasing A/Q ratio and decreasing feed TCP concentrations. Percent toxicity removals were always lower than TCP removals indicating presence or formation of some toxic by products from TCP biodegradation. For the feed TCP of 400 mg L-1, the optimum conditions resulting in maximum COD (99%), TCP (100%) and toxicity (93%) removals were A/Q ratio of nearly 165 m2 d m-3 and feed COD of 2985 mg L-1

  16. Innovative hybrid biological reactors using membranes

    International Nuclear Information System (INIS)

    In this paper we present two lines of research on hybrid reactors including the use of membranes, although with different functions: RBPM, biofilm reactors and membranes filtration RBSOM, supported biofilm reactors and oxygen membranes. (Author) 14 refs.

  17. Development of PUSPATI TRIGA Reactor Simulator For Education Purpose

    International Nuclear Information System (INIS)

    The PUSPATI TRIGA Reactor Simulator was developed in 2012 purposely for 3V program. It is an interactive tool for students understand how to operate the PUSPATI TRIGA Reactor. Students can feeling and understand how to operate the reactor from start-up to shut-down in manual mode of operation. Movement of control rod and reactor parameters are displaying in interactively. Behavior and characteristic for reactor console and reactor itself can be evaluated and understand. Implementation of human system interface is using computer screens, keyboard and mouse. LabVIEW software are using for user interface and mathematical calculation. Polynomial equation based on control rods calibration data as well as operation parameters record was used to calculate and estimated reactor console parameters. The capabilities in user interface, reactor physics and thermal-hydraulics can be expanded and explored to simulation as well as modeling for New Reactor Console, Research Reactor and Nuclear Power Plant. (author)

  18. Sodium fast neutron reactors. Status and perspective of development

    International Nuclear Information System (INIS)

    This report reveals data on development history of domestic fast neutron reactors cooled with sodium (BN reactors). It also shows BN reactors' unique role in expanding source of nuclear power raw materials and in solving ecological problems relating to radioactive wastes. There is brief information on characteristics and operation experience of research reactors BR-10, BOR-60, pilot-industrial reactors BN-350 and BN-600. As well there is data on BN-800 reactor designing that obtained a license for building. There are considered BN reactor peculiarities in regard of safety and design decisions on safety provision at the level meeting standard document requirements. BN reactor technical and economic indices and the ways of their improvement are evaluated. There is brief information on alternative perspective technologies of fast reactors, in particular regarding 'BREST-300' reactor cooled with lead coolant

  19. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

    Bacteria in natural, industrial and clinical settings predominantly live in biofilms, i.e., sessile structured microbial communities encased in self-produced extracellular matrix material. One of the most important characteristics of microbial biofilms is that the resident bacteria display a...... remarkable increased tolerance toward antimicrobial attack. Biofilms formed by opportunistic pathogenic bacteria are involved in devastating persistent medical device-associated infections, and chronic infections in individuals who are immune-compromised or otherwise impaired in the host defense. Because the...... use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

  20. Compaction and relaxation of biofilms

    KAUST Repository

    Valladares Linares, R.

    2015-06-18

    Operation of membrane systems for water treatment can be seriously hampered by biofouling. A better characterization of biofilms in membrane systems and their impact on membrane performance may help to develop effective biofouling control strategies. The objective of this study was to determine the occurrence, extent and timescale of biofilm compaction and relaxation (decompaction), caused by permeate flux variations. The impact of permeate flux changes on biofilm thickness, structure and stiffness was investigated in situ and non-destructively with optical coherence tomography using membrane fouling monitors operated at a constant crossflow velocity of 0.1 m s−1 with permeate production. The permeate flux was varied sequentially from 20 to 60 and back to 20 L m−2 h−1. The study showed that the average biofilm thickness on the membrane decreased after elevating the permeate flux from 20 to 60 L m−2 h−1 while the biofilm thickness increased again after restoring the original flux of 20 L m−2 h−1, indicating the occurrence of biofilm compaction and relaxation. Within a few seconds after the flux change, the biofilm thickness was changed and stabilized, biofilm compaction occurred faster than the relaxation after restoring the original permeate flux. The initial biofilm parameters were not fully reinstated: the biofilm thickness was reduced by 21%, biofilm stiffness had increased and the hydraulic biofilm resistance was elevated by 16%. Biofilm thickness was related to the hydraulic biofilm resistance. Membrane performance losses are related to the biofilm thickness, density and morphology, which are influenced by (variations in) hydraulic conditions. A (temporarily) permeate flux increase caused biofilm compaction, together with membrane performance losses. The impact of biofilms on membrane performance can be influenced (increased and reduced) by operational parameters. The article shows that a (temporary) pressure increase leads to more

  1. Autotrophic Nitrogen Removal in a Membrane-Aerated Biofilm Reactor Under Continuous Aeration: A Demonstration

    DEFF Research Database (Denmark)

    Gilmore, Kevin R.; Terada, Akihiko; Smets, Barth F.;

    2013-01-01

    allowed anaerobic ammonium-oxidizing bacteria (AnaerAOB) to develop and be retained for > 250 days. Daily autotrophic nitrogen removal of 1.7 g N/m(2) (75% of influent N load) was achieved at an oxygen/nitrogen surface loading ratio of 2.2, with up to 85% of the influent N proceeding through Anaer......AOB. During early nitritation, nitrogen oxide (NO(g), NO2(g), and N2O(g)) emissions comprised up to 10% of the removed influent nitrogen, but emissions disappeared after proliferation of AnaerAOB. Microbial communities were radially stratified, with aerobic ammonium-oxidizing bacteria (AerAOB) colonizing...... elimination of gaseous nitrogen oxide emissions....

  2. Bacterial biofilms: prokaryotic adventures in multicellularity

    DEFF Research Database (Denmark)

    Webb, J.S.; Givskov, Michael Christian; Kjelleberg, S.

    2003-01-01

    The development of bacterial biofilms includes both the initial social behavior of undifferentiated cells, as well as cell death and differentiation in the mature biofilm, and displays several striking similarities with higher organisms. Recent advances in the field provide new insight into...... differentiation and cell death events in bacterial biofilm development and propose that biofilms have an unexpected level of multicellularity....

  3. The enrichment of surface passive film on stainless steel during biofilm development in coastal seawater.

    Science.gov (United States)

    Eashwar, M; Sreedhar, G; Lakshman Kumar, A; Hariharasuthan, R; Kennedy, J

    2015-01-01

    The surface passive film on UNS S30400 alloy was characterized before and after biofilm development under different regimes of diurnal lighting in quiescent flowing coastal seawater. As exemplified by atomic force microscopy, the passive film grew under all test conditions with conspicuous variations in morphological features. X-ray photon spectroscopy illustrated an enrichment of the outer film by iron oxide and a progressive increase in the iron oxide/chromium oxide ratio with lighting. Mott-Schottky plots reflected the duplex nature of the film, comprising an outer n-type and an inner p-type configuration. The slopes of the plots showed a strong decrease in donor and acceptor densities with biofilm coverage and lighting, thus confirming passive film growth. These results provide new insights that passive film enrichment is an intrinsic process under practical marine conditions, and show that the evolution of the passive film is a key step to sustained passivity and/or its breakdown by microbial mechanisms. PMID:26222313

  4. ENGINEERING DEVELOPMENT OF SLURRY BUBBLE COLUMN REACTOR (SBCR) TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Bernard A. Toseland, Ph.D.

    1999-01-01

    The major technical objectives of this program are threefold: (1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, (2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and (3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors.

  5. ENGINEERING DEVELOPMENT OF SLURRY BUBBLE COLUMN REACTOR (SBCR) TECHNOLOGY

    International Nuclear Information System (INIS)

    The major technical objectives of this program are threefold: (1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, (2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and (3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors

  6. ENGINEERING DEVELOPMENT OF SLURRY BUBBLE COLUMN REACTOR (SBCR) TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Bernard A. Toseland, Ph.D.

    2002-01-01

    The major technical objectives of this program are threefold: (1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, (2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and (3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors.

  7. ENGINEERING DEVELOPMENT OF SLURRY BUBBLE COLUMN REACTOR (SBCR) TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Bernard A. Toseland

    2002-09-30

    The major technical objectives of this program are threefold: (1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, (2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and (3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors.

  8. ENGINEERING DEVELOPMENT OF SLURRY BUBBLE COLUMN REACTOR (SBCR) TECHNOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Bernard A. Toseland

    2000-06-30

    The major technical objectives of this program are threefold: (1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, (2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and (3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors.

  9. Engineering Development of Slurry Bubble Column Reactor (SBCR) Technology

    Energy Technology Data Exchange (ETDEWEB)

    Toseland, B.A.

    1998-10-29

    The major technical objectives of this program are threefold: (1) to develop the design tools and a fundamental understanding of the fluid dynamics of a slurry bubble column reactor to maximize reactor productivity, (2) to develop the mathematical reactor design models and gain an understanding of the hydrodynamic fundamentals under industrially relevant process conditions, and (3) to develop an understanding of the hydrodynamics and their interaction with the chemistries occurring in the bubble column reactor. Successful completion of these objectives will permit more efficient usage of the reactor column and tighter design criteria, increase overall reactor efficiency, and ensure a design that leads to stable reactor behavior when scaling up to large diameter reactors.

  10. Pore-scale imaging of biofilm grown under varying flow rates

    Science.gov (United States)

    Iltis, G.; Connolly, J.; Davit, Y.; Gerlach, R.; Wood, B. D.; Wildenschild, D.

    2012-12-01

    Biofilm growth in porous media can influence porosity, permeability, dispersion, diffusion, and mass transport of solutes. Even small scale changes in pore morphology have been shown to significantly influence the hydrodynamics of porous systems. The direct observation of biofilm formation and development in porous media is challenging. To date, porous media-associated biofilm research has focused predominantly on investigations of biomass formation in two-dimensional systems, due to (1) the opaque nature of common porous materials, and (2) the direct dependence of conventional biofilm imaging techniques on optically transparent systems. In order to further understand porous media-associated biofilm growth, techniques for quantitatively assessing the three-dimensional spatial distribution of biomass, non-destructively, within opaque porous materials is required for the development of improved reactive transport and biofilm growth models. Through the addition of a barium sulfate suspension to the aqueous phase of experimental column growth reactors, delineation of the biofilm matrix from both the solid and free-flowing aqueous phases is attainable using synchrotron based x-ray computed microtomography. Using this technique, three-dimensional imaging of biofilm within glass bead-packed column growth reactors is possible at a resolution on the order of 10 um/pixel. Results will be presented where biofilm growth characteristics and changes in porous media hydrodynamics associated with bioclogging have been investigated across the Darcy flow regime and into the steady inertial flow regime (0.1 tests and differential pressure measurements. In addition, pore scale imaging enables the analysis of spatial changes to macropore morphology, as well as spatial variation in properties potentially relevant to reactive transport models such as biofilm thickness, reactive surface area, and attachment surface area. Quantitative analysis of these parameters will be discussed for

  11. New developments on research reactor fuel transportation

    International Nuclear Information System (INIS)

    In twelve months after the last meeting held in Williamsburg, this paper gives an overview of the work we accomplished during this year and about the foreseeable developments for the next decade. Last year we were confronted to several difficulties, technical and political, in relation with the transport of MTR spent fuel to the USA. The presentation is focused on the evolution of transport regulations and transport equipment developments: transport means and casks, i.e. evolution of transport regulations and cask development. The progress expected in the next six months will be decisive for most reactor operators. Whatever decision is made, our company and its partners are ready to provide their expertise to solve transportation and storage needs in providing adapted equipment and services

  12. Polyphasic analysis of an Azoarcus-Leptothrix-dominated bacterial biofilm developed on stainless steel surface in a gasoline-contaminated hypoxic groundwater.

    Science.gov (United States)

    Benedek, Tibor; Táncsics, András; Szabó, István; Farkas, Milán; Szoboszlay, Sándor; Fábián, Krisztina; Maróti, Gergely; Kriszt, Balázs

    2016-05-01

    Pump and treat systems are widely used for hydrocarbon-contaminated groundwater remediation. Although biofouling (formation of clogging biofilms on pump surfaces) is a common problem in these systems, scarce information is available regarding the phylogenetic and functional complexity of such biofilms. Extensive information about the taxa and species as well as metabolic potential of a bacterial biofilm developed on the stainless steel surface of a pump submerged in a gasoline-contaminated hypoxic groundwater is presented. Results shed light on a complex network of interconnected hydrocarbon-degrading chemoorganotrophic and chemolitotrophic bacteria. It was found that besides the well-known hydrocarbon-degrading aerobic/facultative anaerobic biofilm-forming organisms (e.g., Azoarcus, Leptothrix, Acidovorax, Thauera, Pseudomonas, etc.), representatives of Fe(2+)-and Mn(2+)-oxidizing (Thiobacillus, Sideroxydans, Gallionella, Rhodopseudomonas, etc.) as well as of Fe(3+)- and Mn(4+)-respiring (Rhodoferax, Geobacter, Magnetospirillum, Sulfurimonas, etc.) bacteria were present in the biofilm. The predominance of β-Proteobacteria within the biofilm bacterial community in phylogenetic and functional point of view was revealed. Investigation of meta-cleavage dioxygenase and benzylsuccinate synthase (bssA) genes indicated that within the biofilm, Azoarcus, Leptothrix, Zoogloea, and Thauera species are most probably involved in intrinsic biodegradation of aromatic hydrocarbons. Polyphasic analysis of the biofilm shed light on the fact that subsurface microbial accretions might be reservoirs of novel putatively hydrocarbon-degrading bacterial species. Moreover, clogging biofilms besides their detrimental effects might supplement the efficiency of pump and treat systems. PMID:26825521

  13. Biofilm Formation by the Fungal Pathogen Candida albicans: Development, Architecture, and Drug Resistance

    OpenAIRE

    Chandra, Jyotsna; Kuhn, Duncan M.; Mukherjee, Pranab K.; Hoyer, Lois L.; McCormick, Thomas; Ghannoum, Mahmoud A.

    2001-01-01

    Biofilms are a protected niche for microorganisms, where they are safe from antibiotic treatment and can create a source of persistent infection. Using two clinically relevant Candida albicans biofilm models formed on bioprosthetic materials, we demonstrated that biofilm formation proceeds through three distinct developmental phases. These growth phases transform adherent blastospores to well-defined cellular communities encased in a polysaccharide matrix. Fluorescence and confocal scanning l...

  14. Dynamics of development and dispersal in sessile microbial communities: examples from Pseudomonas aeruginosa and Pseudomonas putida model biofilms

    DEFF Research Database (Denmark)

    Klausen, M.; Gjermansen, Morten; Kreft, J.-U.;

    2006-01-01

    Surface-associated microbial communities in many cases display dynamic developmental patterns. Model biofilms formed by Pseudomonas aeruginosa and Pseudomonas putida in laboratory flow-chamber setups represent examples of such behaviour. Dependent on the experimental conditions the bacteria in...... organisms do not possess comprehensive genetic programs for biofilm development. Instead the bacteria appear to have evolved a number of different mechanisms to optimize surface colonization, of which they express a subset in response to the prevailing environmental conditions. These mechanisms include the...... ability to regulate cellular adhesiveness and migration in response to micro-environmental signals including those secreted by the bacteria themselves....

  15. History of fast reactor fuel development

    Science.gov (United States)

    Kittel, J. H.; Frost, B. R. T.; Mustelier, J. P.; Bagley, K. Q.; Crittenden, G. C.; Van Dievoet, J.

    1993-09-01

    The first fast breeder reactors, constructed in the 1945-1960 time period, used metallic fuels composed of uranium, plutonium, or their alloys. They were chosen because most existing reactor operating experience had been obtained on metallic fuels and because they provided the highest breeding ratios. Difficulties in obtaining adequate dimensional stability in metallic fuel elements under conditions of high fuel burnup led in the 1960s to the virtual worldwide choice of ceramic fuels. Although ceramic fuels provide lower breeding performance, this objective is no longer an important consideration in most national programs. Mixed uranium and plutonium dioxide became the ceramic fuel that has received the widest use. The more advanced ceramic fuels, mixed uranium and plutonium carbides and nitrides, continue under development. More recently, metal fuel elements of improved design have joined ceramic fuels in achieving goal burnups of 15 to 20 percent. Low-swelling fuel cladding alloys have also been continuously developed to deal with the unexpected problem of void formation in stainless steels subjected to fast neutron irradiation, a phenomenon first observed in the 1960s.

  16. Development of the HANARO research reactor simulator for operator training

    International Nuclear Information System (INIS)

    HANARO (High flux Advanced Neutron Application ReactOr) is multi purpose research reactor in Korea Atomic Energy research Institute, and is operating since 1995. It is needed that training and retraining programs for the operating staff, including: reactor manager, shift supervisors, reactor operators, and others working at the research reactor facility. Recently, we developed HANARO research reactor real time simulator for operating staff training to satisfy these programs. The development of computer based training simulator have provided an easy understanding of reactor physics, operation, and control. Real time simulator is recognized as the ultimate training tool because they allow experiencing, in a dynamic mode, every type of operational condition which can be encountered including: start up, variation of power, shut down, operation during accidents, etc. Also, the simulator will be used as a dynamic test-bed for the reactor regulating system control algorithm

  17. Development of the HANARO research reactor simulator for operator training

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kee Choon; Kim, Jang Yeol; Park, Jae Chang; Lee, Seung Wook; Hwang, In Ah; Lee, Dong Young [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    HANARO (High flux Advanced Neutron Application ReactOr) is multi purpose research reactor in Korea Atomic Energy research Institute, and is operating since 1995. It is needed that training and retraining programs for the operating staff, including: reactor manager, shift supervisors, reactor operators, and others working at the research reactor facility. Recently, we developed HANARO research reactor real time simulator for operating staff training to satisfy these programs. The development of computer based training simulator have provided an easy understanding of reactor physics, operation, and control. Real time simulator is recognized as the ultimate training tool because they allow experiencing, in a dynamic mode, every type of operational condition which can be encountered including: start up, variation of power, shut down, operation during accidents, etc. Also, the simulator will be used as a dynamic test-bed for the reactor regulating system control algorithm.

  18. Development of studies on helium cooled fast reactors

    International Nuclear Information System (INIS)

    A necessity is shown of developing breeders with high reproductive properties. Helium cooled fast reactor is considered. The reactor performances, heating circuit with the use of a steam turbine unit in the secondary circuit is outlined. The reactor design and fuel assemblies are described

  19. Fast Reactor Fuel Development in Japan

    International Nuclear Information System (INIS)

    The future fast reactor and its fuel cycle system under development in Japan uses oxide fuel with simplified pelletizing fuel fabrication technology as a reference concept. Its driver fuel consists of large diameter annular fuel pellets, oxide dispersion strengthened ferritic steel cladding fuel pins with a ferritic-martensitic steel subassembly wrapper tube and minoractinide- bearing oxide fuel. The target burnup of the driver fuel is 150 GW.d/t in discharge average, which corresponds to 250 GW.d/t of peak burnup and 250 dpa of peak neutron dose. Fuel developmental efforts, including out-of-pile studies such as material characteristics experimental evaluation and fuel property measurements, various irradiation tests and fuel fabrication technology developments were planned and are in progress. Future fuels will be realized through Joyo irradiation tests and Monju demonstrations. International collaborative efforts are also an important part of such activities. (author)

  20. A Sensor To Detect the Early Stages in the Development of Crystalline Proteus mirabilis Biofilm on Indwelling Bladder Catheters

    OpenAIRE

    Stickler, D. J.; Jones, S.M.; Adusei, G. O.; Waters, M. G.

    2006-01-01

    A simple sensor has been developed to detect the early stages of urinary catheter encrustation and avoid the clinical crises induced by catheter blockage. In laboratory models of colonization by Proteus mirabilis, the sensor signaled encrustation at an average time of 43 h before catheters were blocked with crystalline biofilm.

  1. Development of Education and Training Programs Using ISIS Research Reactor

    International Nuclear Information System (INIS)

    As a part of the French Alternative Energies and Atomic Energy Commission (CEA), the National Institute for Nuclear Science and Technology (INSTN) carries out various education and training programs on nuclear reactor theory and operation. These programs take advantage of the use of an extensive range of training tools that includes software applications, simulators, as well as the use of research reactors. After a presentation of ISIS reactor, we present the training courses that have been developed on ISIS reactor and their use in education and training programs developed by INSTN. We report on how the training courses carried out on ISIS research reactor ensure a practical and comprehensive understanding of the reactor principle and operation, bringing tremendous benefit to the trainees. We also discuss the future development of education and training programs using the ISIS research reactor as a very powerful tool for the development of the human resources needed by the nuclear industry and the nuclear programs. (author)

  2. Development of space reactor core heat pipes

    International Nuclear Information System (INIS)

    The Space Power Advance Reactor (SPAR) core heat pupes are being developed to transport 15 kW of power at 1400 K. A straight, 2-m-long, 15.9-mm-diam heat pipe was fabricated of low-carbon arc-cast molybdenum and filled with sodium as the working fluid. This nonconcentric, annular, screen-tube-wick pipe was tested successfully at 16.1 kW at 1310 K, at which point a boiling limit was encountered. Follow-on work has produced an as yet untested heat pipe which has its wick centered in the evaporator by spacer wires to alleviate the boiling limit problem. A dual artery wick heat pipe is being fabricated to further improve on the boiling limit and increase redundancy. Because the heat pipe must bend around the radiation shield of the SPAR reactor, a series of bending experiments was performed. Promising results were achieved by filling the pipe completely with sodium and bending at 3650 K

  3. Decision aid software development for nuclear reactors

    International Nuclear Information System (INIS)

    The development of new techniques, especially in the field of Artificial Intelligence, makes it possible to design more powerful computerised systems supporting tasks related to the design and operation of nuclear power plants. The potential contribution and perspectives for the integration of such systems depend upon whether the improvement of existing plants, the design of next generation reactors or future projects are concerned. This paper will present four systems which show the state of the art in the field of knowledge-based systems. The first one is related to the automatic generation of accidental procedures dealing with the loss of electrical power supply. The second one aims at assisting the power plant utility in following the technical specifications during maintenance operations. Finally, the last two are designed to help an emergency team to evaluate and to forecast the evaluation of an accidental situation in a nuclear reactor plant. Perspectives for one-line operator assistance are then discussed, as well as the main technical topics which will make possible the design of such systems. We conclude with the difficulties which are encountered upon integration of these tools: their validation and the task sharing between man and machine. (author). 8 refs

  4. Biofilm enhanced subsurface sequestration of supercritical CO2

    Science.gov (United States)

    Mitchell, A. C.; Phillips, A.; Hiebert, R.; Gerlach, R.; Kaszuba, J.; Cunningham, A.

    2007-12-01

    In order to develop subsurface CO2 storage as a viable engineered mechanism to reduce concentrations of atmospheric CO2, any potential ¡°leakage¡± of injected supercritical CO2 (scCO2) from the ground to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing scCO2 leakage. Firstly, experiments were performed to test whether biofilms were more resilient than planctonic cells to scCO2. Bacillus mojavensis biofilms were grown on a sand support matrix in scCO2 extractor cartridges at 30°C. B. mojavensis was also grown under suspended planctonic conditions in the same media overnight and aliquots were decanted into scCO2 extractor cartridges. Biofilm and suspended B. mojavensis samples were processed on a Supercritical Fluid Extractor with pressurization to 2000 psi at 35°C, and a 20 minute flow of scCO2. Suspended growth samples revealed a 3 log reduction in cell viability while biofilm only showed a 1 log reduction, demonstrating that B. mojavensis biofilms are more resilient than planctonic cells to scCO2. Protective extra cellular polymeric substances which make up the biofilm matrix likely provide a protective barrier against scCO2. Secondly, the ability of biofilms to grow under high pressure and reduce the permeability of porous geological matrices was investigated using a unique high pressure (8.9MPa), moderate temperature (¡Ý 32°C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm accumulation in rock pores which resulted in core permeability. Permeability did not increase in response to starvation and scCO2 challenges. Viable population assays of organisms in the effluent indicated survival of the microorganisms following scCO2 challenges of <71h and starvation for <363h

  5. Oral Biofilm Architecture on Natural Teeth

    NARCIS (Netherlands)

    Zijnge, Vincent; van Leeuwen, M. Barbara M.; Degener, John E.; Abbas, Frank; Thurnheer, Thomas; Gmuer, Rudolf; Harmsen, Hermie J. M.; Jonsson, Ing-Marie; Juuti, Jarmo T.; François, Patrice; AlMajidi, Rana; Pietiäinen, Milla; Girard, Myriam; Lindholm, Catharina; Saller, Manfred J.; Driessen, Arnold J.M.; Kuusela, Pentti; Bokarewa, Maria; Schrenzel, Jacques; Kontinen, Vesa P.; Neyrolles, Olivier

    2010-01-01

    Periodontitis and caries are infectious diseases of the oral cavity in which oral biofilms play a causative role. Moreover, oral biofilms are widely studied as model systems for bacterial adhesion, biofilm development, and biofilm resistance to antibiotics, due to their widespread presence and acces

  6. Distribution and hydrophobic properties of Extracellular Polymeric Substances in biofilms in relation towards cohesion.

    Science.gov (United States)

    Ras, M; Lefebvre, D; Derlon, N; Hamelin, J; Bernet, N; Paul, E; Girbal-Neuhauser, E

    2013-05-20

    A heterotrophic biofilm (B1) and a mixed autotrophic-heterotrophic biofilm (B2) were developed in an annular reactor and submitted to an erosion test in order to selectively detach top layers from the bottom layers. Densities of the basal layers were 5-fold higher and 3-fold higher than the densities of the entire biofilms B1 and B2, respectively. After extraction, EPS content in B1 biofilm was found higher in the basal layer (95 mg g⁻¹ VSS) compared to the top layer (30 mg g⁻¹ VSS), while B2 biofilm had a higher EPS content in the top layer (303 mg g⁻¹ VSS) compared to the basal layer (135 mg g⁻¹ VSS). Hydrophobic Interaction Chromatography (HIC) indicates that hydrophobic EPS (HEPS) in both biofilms reached 21% of EPS in basal cohesive layers, and remained slightly lower or identical (16-19%) in top detached biofilm layers. Strong interacting HEPS were found in a higher proportion in the mixed autotrophic-heterotrophic B2 which was also more diversified in terms of bacterial populations than the B1 heterotrophic biofilm. These results show that HEPS content correlates better with cohesive properties of the biofilm layers than global EPS content and that strong hydrophobic adhesion forces may be related to microbial populations such as the presence of nitrifiers. PMID:23524058

  7. Ammonia oxidizing bacteria and archaea in horizontal flow biofilm reactors treating ammonia-contaminated air at 10 °C.

    Science.gov (United States)

    Gerrity, Seán; Clifford, Eoghan; Kennelly, Colm; Collins, Gavin

    2016-05-01

    The objective of this study was to demonstrate the feasibility of novel, Horizontal Flow Biofilm Reactor (HFBR) technology for the treatment of ammonia (NH3)-contaminated airstreams. Three laboratory-scale HFBRs were used for remediation of an NH3-containing airstream at 10 °C during a 90-d trial to test the efficacy of low-temperature treatment. Average ammonia removal efficiencies of 99.7 % were achieved at maximum loading rates of 4.8 g NH3 m(3) h(-1). Biological nitrification of ammonia to nitrite (NO2 (-)) and nitrate (NO3 (-)) was mediated by nitrifying bacterial and archaeal biofilm populations. Ammonia-oxidising bacteria (AOB) were significantly more abundant than ammonia-oxidising archaea (AOA) vertically at each of seven sampling zones along the vertical HFBRs. Nitrosomonas and Nitrosospira, were the two most dominant bacterial genera detected in the HFBRs, while an uncultured archaeal clone dominated the AOA community. The bacterial community composition across the three HFBRs was highly conserved, although variations occurred between HFBR zones and were driven by physicochemical variables. The study demonstrates the feasibility of HFBRs for the treatment of ammonia-contaminated airstreams at low temperatures; identifies key nitrifying microorganisms driving the removal process; and provides insights for process optimisation and control. The findings are significant for industrial applications of gas oxidation technology in temperate climates. PMID:26879980

  8. BIOFILM DEVELOPMENT IN TIME ON A SILICONE VOICE PROSTHESIS - A CASE-STUDY

    NARCIS (Netherlands)

    NEU, TR; DEBOER, CE; VERKERKE, GJ; SCHUTTE, HK; RAKHORST, G; VANDERMEI, HC; BUSSCHER, HJ

    1994-01-01

    Voice prostheses from silicone elastomers become rapidly colonised by a mixed biofilm of bacteria and yeasts. In this study, microorganisms were isolated from biofilms on explanted prostheses after having been in place for various time intervals ranging from 1 to 67 d. The isolates were examined for

  9. Distinct roles of extracellular polymeric substances in Pseudomonas aeruginosa biofilm development

    DEFF Research Database (Denmark)

    Yang, Liang; Hu, Yifan; Liu, Yang;

    2011-01-01

    polysaccharides are also essential for subpopulation interactions and macrocolony formation in the later stages of P. aeruginosa PAO1 biofilm formation. Pel and Psl polysaccharides have different impacts on Pseudomonas quinolone signal‐mediated extracellular DNA release in P. aeruginosa PAO1 biofilms. Psl...

  10. A simple birth-death-migration individual-based model for biofilm development

    OpenAIRE

    Mabrouk, Nabil; Deffuant, Guillaume

    2011-01-01

    Bacteria growth, detachment and surface-associated motility are recongnized to play an important role in microbial biofilm formation. In this paper we we investigate using an individual-based model how these processes interplay to yield complex biofilm spatial patterns.

  11. Status of the DEBENE fast breeder reactor development, March 1979

    International Nuclear Information System (INIS)

    Status report of the Fast-breeder reactor development in Germany covers the following: description of the political situation in Federal republic of germany during 1978; international cooperation in the field of fast reactor technology development; operation description of the KNK-II fast core experimental power plant; status of construction of the SNR-300; results of the research and development programs concerned with fuel element, cladding, absorber rods and core structural materials development; sodium effects; neutron irradiation effects on SS properties; reactor physics related to experiments in fast critical assemblies; fast reactor safety issues; core disruption accidents; sodium boiling experiments, measuring methods developed; component tests

  12. Development of a system model for advanced small modular reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Tom Goslee,; Holschuh, Thomas Vernon,

    2014-01-01

    This report describes a system model that can be used to analyze three advance small modular reactor (SMR) designs through their lifetime. Neutronics of these reactor designs were evaluated using Monte Carlo N-Particle eXtended (MCNPX/6). The system models were developed in Matlab and Simulink. A major thrust of this research was the initial scoping analysis of Sandia's concept of a long-life fast reactor (LLFR). The inherent characteristic of this conceptual design is to minimize the change in reactivity over the lifetime of the reactor. This allows the reactor to operate substantially longer at full power than traditional light water reactors (LWRs) or other SMR designs (e.g. high temperature gas reactor (HTGR)). The system model has subroutines for lifetime reactor feedback and operation calculations, thermal hydraulic effects, load demand changes and a simplified SCO2 Brayton cycle for power conversion.

  13. Changes in tolerance to herbicide toxicity throughout development stages of phototrophic biofilms.

    Science.gov (United States)

    Paule, A; Roubeix, V; Lauga, B; Duran, R; Delmas, F; Paul, E; Rols, J L

    2013-11-15

    Ecotoxicological experiments have been performed in laboratory-scale microcosms to investigate the sensitivity of phototrophic biofilm communities to the alachlor herbicide, in relation to the stages of phototrophic biofilm maturation (age of the phototrophic biofilms) and physical structure (intact biofilm versus recolonization). The phototrophic biofilms were initially cultivated on artificial supports in a prototype rotating annular bioreactor (RAB) with Taylor-Couette type flow under constant operating conditions. Biofilms were collected after 1.6 and 4.4 weeks of culture providing biofilms with different maturation levels, and then exposed to nominal initial alachlor concentration of 10 μg L(-1) in either intact or recolonized biofilms for 15 days in microcosms (mean time-weighted average concentration - TWAC of 5.52 ± 0.74 μg L(-1)). At the end of the exposure period, alachlor effects were monitored by a combination of biomass descriptors (ash-free dry mass - AFDM, chlorophyll a), structural molecular fingerprinting (T-RFLP), carbon utilization spectra (Biolog) and diatom species composition. We found significant effects that in terms of AFDM, alachlor inhibited growth of the intact phototrophic biofilms. No effect of alachlor was observed on diatom composition or functional and structural properties of the bacterial community regardless of whether they were intact or recolonized. The intact three-dimensional structure of the biofilm did not appear to confer protection from the effects of alachlor. Bacterial community structure and biomass level of 4.4 weeks - intact phototrophic biofilms were significantly influenced by the biofilm maturation processes rather than alachlor exposure. The diatom communities which were largely composed of mobile and colonizer life-form populations were not affected by alachlor. This study showed that the effect of alachlor (at initial concentration of 10 μg L(-1) or mean TWAC of 5.52 ± 0.74 μg L(-1)) is mainly limited to

  14. Decommissioning technology development for research reactors

    International Nuclear Information System (INIS)

    Although it is expected that the decommissioning of a nuclear power plant will happen since 2020, the need of partial decommissioning and decontamination for periodic inspection and life extension has been on an increasing trend and domestic market has gradually been extended. Therefore, in this project the decommissioning DB system on the KRR-1 and 2 was developed as establishing the information classification system of the research reactor dismantling and the structural design and optimization of the decommissioning DB system. Also in order to secure the reliability and safety about the dismantling process, the main dismantling simulation technology that can verify the dismantling process before their real dismantling work was developed. And also the underwater cutting equipment was developed to remove these stainless steel parts highly activated from the RSR. First, the its key technologies were developed and then the design, making, and capability analysis were performed. Finally the actual proof was achieved for applying the dismantling site. an automatic surface contamination measuring equipment was developed in order to get the sample automatically and measure the radiation/radioactivity

  15. Research requirements for alternative reactor development strategies

    International Nuclear Information System (INIS)

    The purpose of this paper is to estimate and compare resource requirements and other fuel cycle quantities for alternative reactor deployment strategies. The paper examines from global and national perspectives the interaction of various fuel cycle alternatives described in the previous U.S. submissions to Working Groups 4, 5, 8 and Subgroup 1A/2A. Nuclear energy forecasts of Subgroup 1A/2A are used in the calculation of uranium demand for each strategy. These uranium demands are then compared to U.S. estimates of annual uranium producibility. Annual rather than cumulative producibility was selected because it does not assume preplanned stockpiling, and is therefore more conservative. The strategies attempt to span a range of nuclear power mixes which could evolve if appropriate commercial and governmental climates develop

  16. Advanced Small Modular Reactor Economics Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Thomas J [ORNL

    2014-10-01

    The US Department of Energy Office of Nuclear Energy’s Advanced Small Modular Reactor (SMR) research and development activities focus on four key areas: Developing assessment methods for evaluating advanced SMR technologies and characteristics; and Developing and testing of materials, fuels and fabrication techniques; and Resolving key regulatory issues identified by US Nuclear Regulatory Commission and industry; and Developing advanced instrumentation and controls and human-machine interfaces. This report focuses on development of assessment methods to evaluate advanced SMR technologies and characteristics. Specifically, this report describes the expansion and application of the economic modeling effort at Oak Ridge National Laboratory. Analysis of the current modeling methods shows that one of the primary concerns for the modeling effort is the handling of uncertainty in cost estimates. Monte Carlo–based methods are commonly used to handle uncertainty, especially when implemented by a stand-alone script within a program such as Python or MATLAB. However, a script-based model requires each potential user to have access to a compiler and an executable capable of handling the script. Making the model accessible to multiple independent analysts is best accomplished by implementing the model in a common computing tool such as Microsoft Excel. Excel is readily available and accessible to most system analysts, but it is not designed for straightforward implementation of a Monte Carlo–based method. Using a Monte Carlo algorithm requires in-spreadsheet scripting and statistical analyses or the use of add-ons such as Crystal Ball. An alternative method uses propagation of error calculations in the existing Excel-based system to estimate system cost uncertainty. This method has the advantage of using Microsoft Excel as is, but it requires the use of simplifying assumptions. These assumptions do not necessarily bring into question the analytical results. In fact, the

  17. Status of Fast Reactor Research and Technology Development

    International Nuclear Information System (INIS)

    In 1985, the International Atomic Energy Agency (IAEA) published a report titled 'Status of Liquid Metal Cooled Fast Breeder Reactors' (Technical Reports Series No. 246). The report was a general review of the status of fast reactor development at that time, covering some aspects of design and operation and reviewing experience from the earliest days. It summarized the programmes and plans in all countries which were pursuing the development of fast reactors. In 1999, the IAEA published a follow-up report titled 'Status of Liquid Metal Cooled Fast Reactor Technology' (IAEA-TECDOC-1083), necessitated by the substantial advances in fast reactor technology development and changes in the economic and regulatory environment which took place during the period of 1985-1998. Chief among these were the demonstration of reliable operation by several prototypes and experimental reactors, the reliable operation of fuel at a high burnup and the launch of new fast reactor programmes by some additional Member States. In 2006, the Technical Working Group on Fast Reactors (TWG-FR) identified the need to update its past publications and recommended the preparation of a new status report on fast reactor technology. The present status report intends to provide comprehensive and detailed information on the technology of fast neutron reactors. The focus is on practical issues that are useful to engineers, scientists, managers, university students and professors, on the following topics: experience in construction, operation and decommissioning; various areas of research and development; engineering; safety; and national strategies and public acceptance of fast reactors.

  18. Effect of hydraulic retention time on inorganic nutrient recovery and biodegradable organics removal in a biofilm reactor treating plant biomass leachate

    Energy Technology Data Exchange (ETDEWEB)

    Krumins, V.; Hummerick, M.; Levine, L.; Strayer, R.; Adams, J.L.; Bauer, J. [Dynamac Corporation, Kennedy Space Center, FL (United States)

    2002-12-01

    A fixed-film (biofilm) reactor was designed and its performance was determined at various retention times. The goal was to find the optimal retention time for recycling plant nutrients in an advanced life support system, to minimize the size, mass, and volume (hold-up) of a production model. The prototype reactor was tested with aqueous leachate from wheat crop residue at 24, 12, 6, and 3 h hydraulic retention times (HRTs). Biochemical oxygen demand (BOD), nitrates and other plant nutrients, carbohydrates, total phenolics, and microbial counts were monitored to characterize reactor performance. BOD removal decreased significantly from 92% at the 24 h HRT to 73% at 3 h. Removal of phenolics was 62% at the 24 h retention time, but 37% at 3 h. Dissolved oxygen concentrations, nitric acid consumption, and calcium and magnesium removals were also affected by HRT. Carbohydrate removals, carbon dioxide (CO{sub 2}) productions, denitrification, potassium concentrations, and microbial counts were not affected by different retention times. A 6 h HRT will be used in future studies to determine the suitability of the bioreactor effluent for hydroponic plant production. (author)

  19. Optimization of the moving-bed biofilm sequencing batch reactor (MBSBR) to control aeration time by kinetic computational modeling: Simulated sugar-industry wastewater treatment.

    Science.gov (United States)

    Faridnasr, Maryam; Ghanbari, Bastam; Sassani, Ardavan

    2016-05-01

    A novel approach was applied for optimization of a moving-bed biofilm sequencing batch reactor (MBSBR) to treat sugar-industry wastewater (BOD5=500-2500 and COD=750-3750 mg/L) at 2-4h of cycle time (CT). Although the experimental data showed that MBSBR reached high BOD5 and COD removal performances, it failed to achieve the standard limits at the mentioned CTs. Thus, optimization of the reactor was rendered by kinetic computational modeling and using statistical error indicator normalized root mean square error (NRMSE). The results of NRMSE revealed that Stover-Kincannon (error=6.40%) and Grau (error=6.15%) models provide better fits to the experimental data and may be used for CT optimization in the reactor. The models predicted required CTs of 4.5, 6.5, 7 and 7.5h for effluent standardization of 500, 1000, 1500 and 2500mg/L influent BOD5 concentrations, respectively. Similar pattern of the experimental data also confirmed these findings. PMID:26943932

  20. Effect of hydraulic retention time on inorganic nutrient recovery and biodegradable organics removal in a biofilm reactor treating plant biomass leachate

    Science.gov (United States)

    Krumins, Valdis; Hummerick, Mary; Levine, Lanfang; Strayer, Richard; Adams, Jennifer L.; Bauer, Jan

    2002-01-01

    A fixed-film (biofilm) reactor was designed and its performance was determined at various retention times. The goal was to find the optimal retention time for recycling plant nutrients in an advanced life support system, to minimize the size, mass, and volume (hold-up) of a production model. The prototype reactor was tested with aqueous leachate from wheat crop residue at 24, 12, 6, and 3 h hydraulic retention times (HRTs). Biochemical oxygen demand (BOD), nitrates and other plant nutrients, carbohydrates, total phenolics, and microbial counts were monitored to characterize reactor performance. BOD removal decreased significantly from 92% at the 24 h HRT to 73% at 3 h. Removal of phenolics was 62% at the 24 h retention time, but 37% at 3 h. Dissolved oxygen concentrations, nitric acid consumption, and calcium and magnesium removals were also affected by HRT. Carbohydrate removals, carbon dioxide (CO2) productions, denitrification, potassium concentrations, and microbial counts were not affected by different retention times. A 6 h HRT will be used in future studies to determine the suitability of the bioreactor effluent for hydroponic plant production.

  1. The galactophilic lectin, LecA, contributes to biofilm development in Pseudomonas aeruginosa.

    Science.gov (United States)

    Diggle, Stephen P; Stacey, Rachael E; Dodd, Christine; Cámara, Miguel; Williams, Paul; Winzer, Klaus

    2006-06-01

    LecA (PA-IL) is a cytotoxic lectin and adhesin produced by Pseudomonas aeruginosa which binds hydrophobic galactosides with high specificity and affinity. By using a lecA-egfp translation fusion and immunoblot analysis of the biofilm extracellular matrix, we show that lecA is expressed in biofilm-grown cells. In static biofilm assays on both polystyrene and stainless steel, biofilm depth and surface coverage was reduced by mutation of lecA and enhanced in the LecA-overproducing strain PAO-P47. Biofilm surface coverage by the parent strain, PAO-P47 but not the lecA mutant on steel coupons was also inhibited by growth in the presence of either isopropyl-beta-D-thiogalactoside (IPTG) or p-nitrophenyl-alpha-D-galactoside (NPG). Furthermore, mature wild-type biofilms formed in the absence of these hydrophobic galactosides could be dispersed by the addition of IPTG. In contrast, addition of p-nitrophenyl-alpha-L-fucose (NPF) which has a high affinity for the P. aeruginosa LecB (PA-IIL) lectin had no effect on biofilm formation or dispersal. Planktonic growth of P. aeruginosa PAO1 was unaffected by the presence of IPTG, NPG or NPF, nor was the strain able to utilize these sugars as carbon sources, suggesting that the observed effects on biofilm formation were due to the competitive inhibition of LecA-ligand binding. Similar results were also obtained for biofilms grown under dynamic flow conditions on steel coupons, suggesting that LecA contributes to P. aeruginosa biofilm architecture under different environmental conditions. PMID:16689730

  2. Biodegradation of 2,4,6-trichlorophenol in a packed-bed biofilm reactor equipped with an internal net draft tube riser for aeration and liquid circulation

    International Nuclear Information System (INIS)

    For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for liquid circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high AD/AR ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values εG, and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies (∼95%), and by the stoichiometric release of chloride ions from the halogenated compound (∼80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions)

  3. Biodegradation of 2,4,6-trichlorophenol in a packed-bed biofilm reactor equipped with an internal net draft tube riser for aeration and liquid circulation

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-De Jesus, A.; Romano-Baez, F.J.; Leyva-Amezcua, L.; Juarez-Ramirez, C.; Ruiz-Ordaz, N. [Departamento de Ingenieria Bioquimica, Escuela Nacional de Ciencias Biologicas, IPN. Prol. Carpio y Plan de Ayala, Colonia Santo Tomas, s/n. CP 11340, Mexico, D.F. (Mexico); Galindez-Mayer, J. [Departamento de Ingenieria Bioquimica, Escuela Nacional de Ciencias Biologicas, IPN. Prol. Carpio y Plan de Ayala, Colonia Santo Tomas, s/n. CP 11340, Mexico, D.F. (Mexico)], E-mail: cmayer@encb.ipn.mx

    2009-01-30

    For the aerobic biodegradation of the fungicide and defoliant 2,4,6-trichlorophenol (2,4,6-TCP), a bench-scale packed-bed bioreactor equipped with a net draft tube riser for liquid circulation and oxygenation (PB-ALR) was constructed. To obtain a high packed-bed volume relative to the whole bioreactor volume, a high A{sub D}/A{sub R} ratio was used. Reactor's downcomer was packed with a porous support of volcanic stone fragments. PB-ALR hydrodynamics and oxygen mass transfer behavior was evaluated and compared to the observed behavior of the unpacked reactor operating as an internal airlift reactor (ALR). Overall gas holdup values {epsilon}{sub G}, and zonal oxygen mass transfer coefficients determined at various airflow rates in the PB-ALR, were higher than those obtained with the ALR. When comparing mixing time values obtained in both cases, a slight increment in mixing time was observed when reactor was operated as a PB-ALR. By using a mixed microbial community, the biofilm reactor was used to evaluate the aerobic biodegradation of 2,4,6-TCP. Three bacterial strains identified as Burkholderia sp., Burkholderia kururiensis and Stenotrophomonas sp. constituted the microbial consortium able to cometabolically degrade the 2,4,6-TCP, using phenol as primary substrate. This consortium removed 100% of phenol and near 99% of 2,4,6-TCP. Mineralization and dehalogenation of 2,4,6-TCP was evidenced by high COD removal efficiencies ({approx}95%), and by the stoichiometric release of chloride ions from the halogenated compound ({approx}80%). Finally, it was observed that the microbial consortium was also capable to metabolize 2,4,6-TCP without phenol as primary substrate, with high removal efficiencies (near 100% for 2,4,6-TCP, 92% for COD and 88% for chloride ions)

  4. Development in UK commercial fast reactor design

    International Nuclear Information System (INIS)

    The design of the CDFR commercial demonstration fast reactor which should be put into operation early in the 90-ties is described. Basic elements of the reactor components are considered. The choice of the integrated primary coolant circuit, and design of intermediate heat exchangers, sodium pumps and charging machines is substantiated. The reactor power is 1320 MW(e), or 3300 MW(t). The sodium temperature at the reactor inlet is 370 deg C, at its outlet 540 deg C. Linear loading per fuel element length is 40 W/mm. The conclusion is drawn that the described design of the demonstration reactor fully corresonds to requirements of a full-scale commercial NPP with a fast reactor

  5. Development Program of the Advanced HANARO Reactor in Korea

    International Nuclear Information System (INIS)

    The development program of an advanced HANARO (AHR) reactor started in Korea to keep abreast of the increasing future demand, from both home and abroad, for research activities. This paper provides a review of the status of research reactors in Korea, the operating experience of the HANARO, the design principles and preliminary features of an advanced HANARO reactor, and the specific strategy of an advanced HANARO reactor development program. The design principles were established in order to design a new multi-purpose research reactor that is safe, economically competitive and technically feasible. These include the adaptation of the HANARO design concept, its operating experience, a high ratio of flux to power, a high degree of safety, improved economic efficiency, improved operability and maintainability, increased space and expandability, and ALARA design optimization. The strategy of an advanced HANARO reactor development program considers items such as providing a digital advanced HANARO reactor in cyber space, a method for the improving the design quality and economy of research reactors by using Computer Integrated Engineering, and more effective advertising using diverse virtual reality. This development program will be useful for promoting the understanding of and interest in the operating HANARO as well as an advanced HANARO reactor under development in Korea. It will provide very useful information to a country that may need a research reactor in the near future for the promotion of public health, bio-technology, drug design, pharmacology, material processing, and the development of new materials. (author)

  6. Biofilm monitoring on rotating discs by image analysis.

    Science.gov (United States)

    Pons, Marie-Noëlle; Milferstedt, Kim; Morgenroth, Eberhard

    2009-05-01

    The macrostructure development of biofilms grown in a lab-scale rotating biological contactor was monitored by analyzing the average opacity and the texture of gray-level images of the discs. The reactor was fed with municipal or synthetic wastewater. Experiments lasted on average 4-14 weeks. The images were obtained with a flat-bed scanner. The opacity and its standard deviation are directly extracted from the annular zone where the biofilm develops. This zone is defined by the outer edge of the disc and the waterline. The spatial gray-level dependence matrix (SGLDM) approach was used for the texture assessment. As this method requires rectangular images, a geometrical transformation had to be developed to transform the ring into a workable area. This transformation now allows quantitative image analysis on circular biofilms. As a last step, Principal Components Analysis was applied to the set of textural descriptors to reduce the number of textural parameters. Opacity and textural information allowed the non-intrusive monitoring of the growth/regrowth of the biofilms as well as biofilm loss, due to detachment, auto-digestion, or protozoan grazing. Textural description was very valuable by helping to discriminate biofilms of similar opacity characteristics but presenting different macrostructures. PMID:19132742

  7. Experience and prospects for developing research reactors of different types

    International Nuclear Information System (INIS)

    NIKIET has a 60-year experience in the development of research reactors. Altogether, there have been more than 25 NIKIET-designed plants of different types built in Russia and 20 more in other countries, including pool-type water-cooled and water moderated research reactors, tank-type and pressure-tube research reactors, pressurized high-flux, heavy-water, pulsed and other research reactors. Most of the research reactors were designed as multipurpose plants for operation at research centers in a broad range of applications. Besides, unique research reactors were developed for specific application fields. Apart from the experience in the development of research reactor designs and the participation in the reactor construction, a unique amount of knowledge has been gained on the operation of research reactors. This makes it possible to use highly reliable technical solutions in the designs of new research reactors to ensure increased safety, greater economic efficiency and maintainability of the reactor systems. A multipurpose pool-type research reactor of a new generation is planned to be built at the Center for Nuclear Energy Science & Technology (CNEST) in the Socialist Republic of Vietnam to be used to support a spectrum of research activities, training of skilled personnel for Vietnam nuclear industry and efficient production of isotopes. It is exactly the applications a research reactor is designed for that defines the reactor type, design and capacity, and the selection of fuel and components subject to all requirements of industry regulations. The design of the new research reactor has a great potential in terms of upgrading and installation of extra experimental devices. (author)

  8. Impact of Irgarol 1051 on the larval development and metamorphosis of Balanus amphitirite Darwin, diatom, Amphora coffeaformis and natural biofilm

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, D.V.

    The effect of Irgarol 1051 on the biofilm-forming diatom, Amphora coffeaformis, and on natural biofilm was assessed. A reduction in the number of A. coffeaformis cells within a biofilm was observed after treatment with Irgarol 1051, confirming its...

  9. Permeabilizing biofilms

    Science.gov (United States)

    Soukos, Nikolaos S.; Lee, Shun; Doukas, Apostolos G.

    2008-02-19

    Methods for permeabilizing biofilms using stress waves are described. The methods involve applying one or more stress waves to a biofilm, e.g., on a surface of a device or food item, or on a tissue surface in a patient, and then inducing stress waves to create transient increases in the permeability of the biofilm. The increased permeability facilitates delivery of compounds, such as antimicrobial or therapeutic agents into and through the biofilm.

  10. Gas cooled fast reactor research and development program

    International Nuclear Information System (INIS)

    The research and development work in the field of core thermal-hydraulics, steam generator research and development, experimental and analytical physics and carbide fuel development carried out 1978 for the Gas Cooled Fast Breeder Reactor at the Swiss Federal Institute for Reactor Research is described. (Auth.)

  11. Gas cooled fast reactor research and development program

    International Nuclear Information System (INIS)

    The research and development work in the field of core thermal-hydraulics, steam generator research and development, experimental and analytical physics and carbide fuel development carried out 1979 for the Gas Cooled Fast Breeder Reactor at the Swiss Federal Institute for Reactor Research is described. (Auth.)

  12. RELAP/SCDAPSIM Reactor System Simulator Development and Training for University and Reactor Applications

    International Nuclear Information System (INIS)

    The RELAP/SCDAPSIM code, designed to predict the behaviour of reactor systems during normal and accident conditions, is being developed as part of an international nuclear technology development program called SDTP (SCDAP Development and Training Program). SDTP involves more than 60 organizations in 28 countries. One of the important applications of the code is for simulator training of university faculty and students, reactor analysts, and reactor operations and technical support staff. Examples of RELAP/SCDAPSIM-based system thermal hydraulic and severe accident simulator packages include the SAFSIM simulator developed by NECSA for the SAFARI research reactor in South Africa, university-developed simulators at the University of Mexico and Shanghai Jiao Tong University in China, and commercial VISA and RELSIM packages used for analyst and reactor operations staff training. This paper will briefly describe the different packages/facilities. (authors)

  13. Status of fast reactor development in India

    International Nuclear Information System (INIS)

    The economic liberalization process has accelerated the industrial growth and this requires considerable energy input. Nuclear energy has to play an important role in supporting the increasing demand of energy. In this year FBTR was operated at 10.2 MWt power in a sustained manner. Several physics and engineering experiments were carried out. The mixed carbide fuel has achieved a peak burnup of 16,000 MW d/t without failure. First batch of irradiation experiments was completed and pins were delivered to RML for PIE. For PFBR, a thorough review of the conceptual design was carried out towards reducing the capital cost, construction time and for improving plant reliability. A 2 loop concept with 2 PSPs, 4 IHXs and 2 secondary loops having 4 integrated SG modules has been finally chosen with an expected savings of 15% in NSSS capital cost, 2-3 years in construction time and 10-12% in capacity factor. Number of materials to be used for major components was reduced to three to facilitate speedy development. Operating temperatures were finalized after optimization studies. Discussion is in progress to finalize fuel handling system. Research and development activities are continuing at ICGAR in the areas of reactor physics, engineering development, core engineering, thermal hydraulics, structural mechanics, metallurgy, post irradiation examination, instrumentation and electronics, chemistry, fuel reprocessing, safety research and health physics etc. (author). 9 figs

  14. CMEIAS bioimage informatics that define the landscape ecology of immature microbial biofilms developed on plant rhizoplane surfaces

    Directory of Open Access Journals (Sweden)

    Frank B Dazzo

    2015-10-01

    Full Text Available Colonization of the rhizoplane habitat is an important activity that enables certain microorganisms to promote plant growth. Here we describe various types of computer-assisted microscopy that reveal important ecological insights of early microbial colonization behavior within biofilms on plant root surfaces grown in soil. Examples of the primary data are obtained by analysis of processed images of rhizoplane biofilm landscapes analyzed at single-cell resolution using the emerging technology of CMEIAS bioimage informatics software. Included are various quantitative analyses of the in situ biofilm landscape ecology of microbes during their pioneer colonization of white clover roots, and of a rhizobial biofertilizer strain colonized on rice roots where it significantly enhances the productivity of this important crop plant. The results show that spatial patterns of immature biofilms developed on rhizoplanes that interface rhizosphere soil are highly structured (rather than distributed randomly when analyzed at the appropriate spatial scale, indicating that regionalized microbial cell-cell interactions and the local environment can significantly affect their cooperative and competitive colonization behaviors.

  15. Growing and analyzing biofilms in flow chambers

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim; Sternberg, Claus

    2011-01-01

    This unit describes the setup of flow chamber systems for the study of microbial biofilms, and methods for the analysis of structural biofilm formation. Use of flow chambers allows direct microscopic investigation of biofilm formation. The biofilms in flow chambers develop under hydrodynamic......, and disassembly and cleaning of the system. In addition, embedding and fluorescent in situ hybridization of flow chamber-grown biofilms are addressed....

  16. Arsenate Retention by Epipsammic Biofilms Developed on Streambed Sediments: Influence of Phosphate

    Directory of Open Access Journals (Sweden)

    D. M. Prieto

    2013-01-01

    Full Text Available Natural geological conditions together with the impact of human activities could produce environmental problems due to high As concentrations. The aim of this study was to assess the role of epipsammic biofilm-sediment systems onto As (V sorption and to evaluate the effect of the presence of equimolar P concentrations on As retention. A natural biofilm was grown on sediment samples in the laboratory, using river water as nutrient supplier. Sorption experiments with initial As concentrations 0, 5, 25, 50, 100, 250, and 500 μg L−1 were performed. The average percentage of As sorbed was 78.9±3.5 and 96.9±6.6% for the sediment and biofilm-sediment systems, respectively. Phosphate decreased by 25% the As sorption capactity in the sediment devoid of biofilm, whereas no significant effect was observed in the systems with biofilm. Freundlich, Sips, and Toth models were the best to describe experimental data. The maximum As sorption capacity of the sediment and biofilm-sediment systems was, respectively, 6.6 and 6.8 μg g−1 and 4.5 and 7.8 μg g−1 in the presence of P. In conclusion, epipsammic biofilms play an important role in the environmental quality of river systems, increasing As retention by the system, especially in environments where both As and P occur simultaneously.

  17. Advanced Reactor Development in the United States

    International Nuclear Information System (INIS)

    In the United States, three technologies are employed for the new generation of advanced reactors. These technologies are Advanced Light Water Reactors (A LWRs) for the 1990s and beyond, the Modular High Temperature Gas Reactor (M HTGR) for commercial use after the turn of the century, and Liquid Metal Reactors (LWRs) to provide energy production and to convert reactor fission waste to a more manageable waste product. Each technology contributes to the energy solution. Light Water Reactors For The 1990s And Beyond--The U. S. Program The economic and national security of the United States requires a diversified energy supply base built primarily upon adequate, domestic resources that are relatively free from international pressures. Nuclear energy is a vital component of this supply and is essential to meet current and future national energy demands. It is a safe, economically continues to contribute to national energy stability, and strength. The Light Water Reactor (LWR) has been a major and successful contributor to the electrical generating needs of many nations throughout the world. It is being counted upon in the United States as a key to revitalizing nuclear energy option in the 1990s. In recent years, DOE joined with the industry to ensure the availability and future viability of the LWR option. This national program has the participation of the Nation's utility industry, the Electric Power Research Institute (EPRI), and several of the major reactor manufacturers and architect-engineers. Separate but coordinated parts of this program are managed by EPRI and DOE

  18. Development of the CGN's reactor design software

    International Nuclear Information System (INIS)

    Starting from 1990's, CGN has been actively involved in the introduction, digestion, absorption and re-innovation of reactor design software, and is gradually establishing a software R and D system with CGN's characteristics. This paper briefly introduces the software introduction history and its application status in CGN, and summarizes the independent reactor software R and D system of CGN. (authors)

  19. Liquid metal reactor development. Development of LMR coolant technology

    Energy Technology Data Exchange (ETDEWEB)

    Nam, H. Y.; Choi, S. K.; Hwang, J. s.; Lee, Y. B.; Choi, B. H.; Kim, J. M.; Kim, Y. G.; Kim, M. J.; Lee, S. D.; Kang, Y. H.; Maeng, Y. Y.; Kim, T. R.; Park, J. H.; Park, S. J.; Cha, J. H.; Kim, D. H.; Oh, S. K.; Park, C. G.; Hong, S. H.; Lee, K. H.; Chun, M. H.; Moon, H. T.; Chang, S. H.; Lee, D. N.

    1997-07-15

    Following studies have been performed during last three years as the 1.2 phase study of the mid and long term nuclear technology development plan. First, the small scale experiments using the sodium have been performed such as the basic turbulent mixing experiment which is related to the design of a compact reactor, the flow reversal characteristics experiment by natural circulation which is necessary for the analysis of local flow reversal when the electromagnetic pump is installed, the feasibility test of the decay heat removal by wall cooling and the operation of electromagnetic pump. Second, the technology of operation mechanism of sodium facility is developed and the technical analysis and fundamental experiments of sodium measuring technology has been performed such as differential pressure measuring experiment, local flow rate measuring experimenter, sodium void fraction measuring experiment, under sodium facility, the free surface movement experiment and the side orifice pressure drop experiment. A new bounded convection scheme was introduced to the ELBO3D thermo-hydraulic computer code designed for analysis of experimental result. A three dimensional computer code was developed for the analysis of free surface movement and the analysis model of transmission of sodium void fraction was developed. Fourth, the small scale key components are developed. The submersible-in-pool type electromagnetic pump which can be used as primary pump in the liquid metal reactor is developed. The SASS which uses the Curie-point electromagnet and the mock-up of Pantograph type IVTM were manufactured and their feasibility was evaluated. Fifth, the high temperature characteristics experiment of stainless steel which is used as a major material for liquid metal reactor and the material characteristics experiment of magnet coil were performed. (author). 126 refs., 98 tabs., 296 figs.

  20. Liquid metal reactor development. Development of LMR coolant technology

    International Nuclear Information System (INIS)

    Following studies have been performed during last three years as the 1.2 phase study of the mid and long term nuclear technology development plan. First, the small scale experiments using the sodium have been performed such as the basic turbulent mixing experiment which is related to the design of a compact reactor, the flow reversal characteristics experiment by natural circulation which is necessary for the analysis of local flow reversal when the electromagnetic pump is installed, the feasibility test of the decay heat removal by wall cooling and the operation of electromagnetic pump. Second, the technology of operation mechanism of sodium facility is developed and the technical analysis and fundamental experiments of sodium measuring technology has been performed such as differential pressure measuring experiment, local flow rate measuring experimenter, sodium void fraction measuring experiment, under sodium facility, the free surface movement experiment and the side orifice pressure drop experiment. A new bounded convection scheme was introduced to the ELBO3D thermo-hydraulic computer code designed for analysis of experimental result. A three dimensional computer code was developed for the analysis of free surface movement and the analysis model of transmission of sodium void fraction was developed. Fourth, the small scale key components are developed. The submersible-in-pool type electromagnetic pump which can be used as primary pump in the liquid metal reactor is developed. The SASS which uses the Curie-point electromagnet and the mock-up of Pantograph type IVTM were manufactured and their feasibility was evaluated. Fifth, the high temperature characteristics experiment of stainless steel which is used as a major material for liquid metal reactor and the material characteristics experiment of magnet coil were performed. (author). 126 refs., 98 tabs., 296 figs.

  1. Developing an ultrasonic NDE system for a research reactor tank

    International Nuclear Information System (INIS)

    Ultrasonic testing is one of the established tools for routine in-service inspection of reactor tanks. As part of the preventive maintenance of the IRR2 reactor, an ultrasonic scanning system was developed for the inspection of the reactor tank wall. Here, we present the main features of the special equipment developed for this task. In addition, we describe the procedure used for validating the inspection method. A special apparatus was developed for the ultrasonic scanning of a research reactor tank wall, the operation of which was practiced using a full-scale mock-up. The inspection technique was validated using a variety of flaws that were unknown to the operators

  2. Developments in the regulation of research reactors

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (IAEA) has data on over 670 research reactors in the world. Fewer than half of them are operational and a significant number are in a shutdown but not decommissioned state. The International Nuclear Safety Advisory Group (INSAG) has expressed concerns about the safety of many research reactors and this has resulted in a process to draw up an international Code of Conduct on the Safety of Research Reactors. The IAEA is also reviewing its safety standards applying to research reactors. On the home front, regulation of the construction of the Replacement Research Reactor continues. During the construction phase, regulation has centred around the consideration of Requests for Approval (RFA) for the manufacture and installation of systems, structures and components important for safety. Quality control of construction of systems, structures and components is the central issue. The process for regulation of commissioning is under consideration

  3. Future fuel cycle development for CANDU reactors

    International Nuclear Information System (INIS)

    The CANDU reactor has proven to be safe and economical and has demonstrated outstanding performance with natural uranium fuel. The use of on-power fuelling, coupled with excellent neutron economy, leads to a very flexible reactor system with can utilize a wide variety of fuels. The spectrum of fuel cycles ranges from natural uranium, through slightly enriched uranium, to plutonium and ultimately thorium fuels which offer many of the advantages of the fast breeder reactor system. CANDU can also burn the recycled uranium and/or the plutonium from fuel discharged from light water reactors. This synergistic relationship could obviate the need to re-enrich the reprocessed uranium and allow a simpler reprocessing scheme. Fule management strategies that will permit future fuel cycles to be used in existing CANDU reactors have been identified. Evolutionary design changes will lead to an even greater flexibility, which will guarantee the continued success of the CANDU system. (author)

  4. 白腐真菌生物膜反应器中活性艳红 X-3B脱色与降解的实验研究%Experimental Study on Decolorization and Degradation of Reactive Brilliant Red X-3B in a White Rot Fungal Biofilm Reactor

    Institute of Scientific and Technical Information of China (English)

    黄民生; 黄荣; 程永前; 张国莹

    2001-01-01

    Experimental results of an azo dye(reactive brilliant red X-3B, RBR X-3B) decolorization and degradation in a white rot fungal biofilm reactor were introduced and discussed. The fungal biofilm reactor is highly potential for dye decolorization and degradation with the highest decoloring rate of 95% within 96 hours reaction time at initial pH 4.5 under high nitrogen level (HN) (24 mmol/L ammonium tartrate) condition. Experimental conditions, such as nutrient nitrogen levels in reaction mixture and initial pH, significantly affected dye decolorization and degradation. Effluents from this biofilm reactor can be well treated to meet the discharging requirements by use of chemical flocculation. RBR X-3B was first absorbed onto fungal biomass and then degraded gradually. The SH-13 fungus monopolized the biofilm throughout the experiments, though the reactor was exposed to open air for 4 months.

  5. Role of Tec1 in the Development, Architecture, and Integrity of Sexual Biofilms of Candida albicans

    OpenAIRE

    Daniels, Karla J.; Srikantha, Thyagarajan; Pujol, Claude; Park, Yang-Nim; Soll, David R.

    2015-01-01

    MTL-homozygous (a/a or α/α) white cells form a complex sexual biofilm that exhibits the same architecture as that of MTL-heterozygous (a/α) pathogenic biofilms. However, the former is regulated by the mitogen-activated protein (MAP) kinase pathway, while the latter is regulated by the Ras1/cyclic AMP (cAMP) pathway. We previously demonstrated that in the formation of an MTL-homozygous, mature (48 h) sexual biofilm in RPMI 1640 medium, the MAP kinase pathway targets Tec1 rather than Cph1, the ...

  6. Latest developments in biofilm technologies for wastewater treatment: Twenty five years of research of the environmental engineering group (University of Cantabria, Spain); Tecnologias de biopelicula innovadoras para la depuracion de aguas residuales: veinticinco anos de investigacion del Grupo de Ingenieria Ambiental de la Universidad de Camtabria

    Energy Technology Data Exchange (ETDEWEB)

    Tejero Monzon, J. I.; Esteban-Garcia, A. L.; Florio, L. del; Diez Montero, R.; Lobo Garcia de Cortazar, A.; Rodriguez-Hernandez, L.

    2012-07-01

    Biological wastewater treatments are based on the use of active biomass, or set of organisms, in charge of carrying out the removal of contaminants. the biomass can be dispersed in suspension within the bulk liquid (activated sludge processes) or attached to a support media (biofilm processes). Biofilm technology was historically the first to be spread and applied. Nevertheless, since the 1950s, activated sludge technology gained more and more popularity given the supposed operation simplicity and higher quality of the effluent. Recently, new developments pushed forward the biofilm technology again. In this context, the Environmental Engineering Group of the University of Cantabria, since its foundation more than 2 decades ago, has been working on research and development of innovative wastewater treatment technologies based on biofilm. In this article, the know-how of the Group is illustrated, including the development of innovative submerged fixed bed reactors with and without (micro) filtration membranes, processes of biofilm supported by and aerated through membranes, as well as integrated systems (hybrid or combined) aimed at nutrient removal. submerged aerated fixed technologies, especially in hybrid configuration, as much as sludge blanket reactors (combined with biofilm processes) allow for increasing biomass concentration and may provide an attractive solution to upgrade existing WWTP. In combination with membrane filtration, they produce an effluent suitable for reuse o discharge in sensitive areas. On the other, hand, the possibility of aerating (diffusing the gas) directly through the membrane lumen into the biomass thereby grown, without need of oxygenating the whole wastewater flow to be treated, may be a real energetic paradigm shift. The developed technologies are here described alongside their experimental and modeling assessment, ranging from laboratory and bench scale up to pilot scale systems treating real municipal wastewater. (Author)

  7. History of fast reactor fuel development

    International Nuclear Information System (INIS)

    The first fast breeder eactors, constructed in the 1945-1960 time period, used metallic fuels composed of uranium, plutonium, or their alloys. They were chosen because most existing reactor operating experience had been obtained on metallic fuels and because they provided the highest breeding ratios. Difficulties in obtaining adequate dimensional stability in metallic fuel elements under conditions of high fuel burnup led in the 1960s to the virtual worldwide choice of ceramic fuels. Although ceramic fuels provide lower breeding performance, this objective is no longer an important consideration in most national programs. Mixed uranium and plutonium dioxide became the ceramic fuel that has received the widest use. The more advanced ceramic fuels, mixed uranium and plutonium carbides and nitrides, continue under development. More recently, metal fuel elements of improved design have joined ceramic fuels in achieving goal burnups of 15 to 20 percent. Low-swelling fuel cladding alloys have also been continuously developed to deal with the unexpected problem of void formation in stainless steels subjected to fast neutron irradiation, a phenomenon first observed in the 1960s. (orig.)

  8. Development of nuclear fuel for integrated reactor

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kee Nam; Kim, H. K.; Kang, H. S.; Yoon, K. H.; Chun, T. H.; In, W. K.; Oh, D. S.; Kim, D. W.; Woo, Y. M

    1999-04-01

    The spacer grid assembly which provides both lateral and vertical support for the fuel rods and also provides a flow channel between the fuel rods to afford the heat transfer from the fuel pellet into the coolant in a reactor, is one of the major structural components of nuclear fuel for LWR. Therefore, the spacer grid assembly is a highly ranked component when the improvement of hardware is pursued for promoting fuel performance. Main objective of this project is to develop the inherent spacer grid assembly and to research relevant technologies on the spacer grid assembly. And, the UO{sub 2}-based SMART fuel is preliminarily designed for the 330MWt class SMART, which is planned to produce heat as well as electricity. Results from this project are listed as follows. 1. Three kinds of spacer grid candidates have been invented and applied for domestic and US patents. In addition, the demo SG(3x3 array) were fabricated, which the mechanical/structural test was carried out with. 2. The mechanical/structural technologies related to the spacer grid development are studied and relevant test requirements were established. 3. Preliminary design data of the UO{sub 2}-based SMART fuel have been produced. The structural characteristics of several components such as the top/bottom end piece and the holddown spring assembly were analysed by consulting the numerical method.

  9. Development of nuclear fuel for integrated reactor

    International Nuclear Information System (INIS)

    The spacer grid assembly which provides both lateral and vertical support for the fuel rods and also provides a flow channel between the fuel rods to afford the heat transfer from the fuel pellet into the coolant in a reactor, is one of the major structural components of nuclear fuel for LWR. Therefore, the spacer grid assembly is a highly ranked component when the improvement of hardware is pursued for promoting fuel performance. Main objective of this project is to develop the inherent spacer grid assembly and to research relevant technologies on the spacer grid assembly. And, the UO2-based SMART fuel is preliminarily designed for the 330MWt class SMART, which is planned to produce heat as well as electricity. Results from this project are listed as follows. 1. Three kinds of spacer grid candidates have been invented and applied for domestic and US patents. In addition, the demo SG(3x3 array) were fabricated, which the mechanical/structural test was carried out with. 2. The mechanical/structural technologies related to the spacer grid development are studied and relevant test requirements were established. 3. Preliminary design data of the UO2-based SMART fuel have been produced. The structural characteristics of several components such as the top/bottom end piece and the holddown spring assembly were analysed by consulting the numerical method

  10. Establishment of regulatory framework for the development reactor licensing

    International Nuclear Information System (INIS)

    With a trend that various types of advanced reactor designs are currently under development worldwide, the Korea Atomic Energy Research Institute has been developing an advanced reactor called ' System-integrated Modular Advanced Reactor (SMART)', which is a small sized integral type pressurized water reactor with a rated thermal power of 330 MW. To demonstrate the safety and the performance of the SMART reactor design, the SMART Research and Development Center has embarked to build a scaled-down pilot plant of SMART, called 'SMART-P' with a rated thermal power of 65 MW. In preparation for the forthcoming applications for both construction permit and operating license of SMART-P in the near future, the Korea Institute of Nuclear Safety is developing a new regulatory framework for licensing review of such a development reactor, which covers establishment of licensing process, identification and resolution of technical and safety issues, development of regulatory evaluation or verification-purpose computer codes and analytical methods, and establishment of design-specific, general design and operating criteria, regulations, and associated regulatory guides. This paper presents the current activities for establishing a regulatory framework for the licensing of a research and development reactor. Discussions are made on the SMART-P development program, the current Korean regulatory framework for reactor licensing, the SMART-P licensing-related issues, and the approach and strategy for developing an effective regulatory framework for the SMART-P licensing

  11. Beneficial biofilms

    Directory of Open Access Journals (Sweden)

    Sara R Robertson

    2015-10-01

    Full Text Available Surface-adherent biofilm growth is a common trait of bacteria and other microorganisms in nature. Within biofilms, organisms are present in high density and are enmeshed in an organic matrix containing polysaccharides and other molecules. The close proximity of organisms within biofilms facilitates microbial interactions and signaling, including many metabolic processes in which consortia rather than individual organisms participate. Biofilm growth also enables microorganisms to withstand chemical and biological stresses. Here, we review some current literature and document representative beneficial aspects of biofilms using examples from wastewater treatment, microbial fuel cells, biological repair (biocementation of stonework, and biofilm protection against Candida albicans infections. Finally, we address a chemical ecology strategy whereby desired microbial succession and beneficial biofilm formation can be encouraged via manipulation of culture conditions and bacterial signaling.

  12. Gas cooled fast reactor research and development program

    International Nuclear Information System (INIS)

    The research and development work in the field of core thermal-hydraulics, experimental and analytical physics and carbide fuel development carried out 1978 for the Gas Cooled Fast Breeder Reactor at the Swiss Federal Institute for Reactor Research is described. (Auth.)

  13. Phenazine-1-Carboxylic Acid Promotes Bacterial Biofilm Development via Ferrous Iron Acquisition▿†

    OpenAIRE

    Wang, Yun; Wilks, Jessica C.; Danhorn, Thomas; Ramos, Itzel; Croal, Laura; Newman, Dianne K.

    2011-01-01

    The opportunistic pathogen Pseudomonas aeruginosa forms biofilms, which render it more resistant to antimicrobial agents. Levels of iron in excess of what is required for planktonic growth have been shown to promote biofilm formation, and therapies that interfere with ferric iron [Fe(III)] uptake combined with antibiotics may help treat P. aeruginosa infections. However, use of these therapies presumes that iron is in the Fe(III) state in the context of infection. Here we report the ability o...

  14. Characterization and Comparison of Biofilm Development by Pathogenic and Commensal Isolates of Histophilus somni▿

    OpenAIRE

    Sandal, Indra; Hong, Wenzhou; Swords, W. Edward; Inzana, Thomas J.

    2007-01-01

    Histophilus somni (Haemophilus somnus) is an obligate inhabitant of the mucosal surfaces of bovines and sheep and an opportunistic pathogen responsible for respiratory disease, meningoencephalitis, myocarditis, arthritis, and other systemic infections. The identification of an exopolysaccharide produced by H. somni prompted us to evaluate whether the bacterium was capable of forming a biofilm. After growth in polyvinyl chloride wells a biofilm was formed by all strains examined, although most...

  15. BNCT Technology Development on HANARO Reactor

    International Nuclear Information System (INIS)

    So as to establish the biological effects of BNCT in the HANARO Reactor, biological damages in cells and animals with treatment of boron/neutron were investigated. And 124I-BPA animal PET image, analysis technology of the boron contents in the mouse tissues by ICP-AES was established. A Standard clinical protocol, a toxicity evaluation report and an efficacy investigation report of BNCT has been developed. Based on these data, the primary permission of clinical application was acquired through IRB of our hospital. Three cases of pre-clinical experiment for boron distribution and two cases of medium-sized animal simulation experiment using cat with verifying for 2 months after BNCT was performed and so the clinical demonstration with a patient was prepared. Also neutron flux, fast neutron flux and gamma ray dose of BNCT facility were calculated and these data will be utilized good informations for clinical trials and further BNCT research. For the new synthesis of a boron compound, o-carboranyl ethylamine, o-carboranylenepiperidine, o-carboranyl-THIQ and o-carboranyl-s-triazine derivatives were synthesized. Among them, boron uptake in the cancer cell of the triazine derivative was about 25 times than that of BPA and so these three synthesized methods of new boron compounds were patented

  16. BNCT Technology Development on HANARO Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Ki Jung; Park, Kyung Bae; Whang, Seung Ryul; Kim, Myong Seop

    2007-06-15

    So as to establish the biological effects of BNCT in the HANARO Reactor, biological damages in cells and animals with treatment of boron/neutron were investigated. And 124I-BPA animal PET image, analysis technology of the boron contents in the mouse tissues by ICP-AES was established. A Standard clinical protocol, a toxicity evaluation report and an efficacy investigation report of BNCT has been developed. Based on these data, the primary permission of clinical application was acquired through IRB of our hospital. Three cases of pre-clinical experiment for boron distribution and two cases of medium-sized animal simulation experiment using cat with verifying for 2 months after BNCT was performed and so the clinical demonstration with a patient was prepared. Also neutron flux, fast neutron flux and gamma ray dose of BNCT facility were calculated and these data will be utilized good informations for clinical trials and further BNCT research. For the new synthesis of a boron compound, o-carboranyl ethylamine, o-carboranylenepiperidine, o-carboranyl-THIQ and o-carboranyl-s-triazine derivatives were synthesized. Among them, boron uptake in the cancer cell of the triazine derivative was about 25 times than that of BPA and so these three synthesized methods of new boron compounds were patented.

  17. Enhancement of research reactor utilization in the developing countries

    International Nuclear Information System (INIS)

    As the research reactor represents a significant capital investment on the part of any institution and in addition there are recurring annual operating costs, therefore, the subject of its effective utilization has always been of interest. World wide there are about three hundred research reactors. Of these, 92 are located in the developing countries. Together, these reactors represent quite significant research potential. In the present paper, reasons of under utilization, procedures necessary to measure the productivity, ways and means of enhancing the utilization of research reactors are described. In the end, use of two research reactors at PINSTECH are described to illustrate some of the ways in which a successful utilization of a research reactor can made in the developing country. (author) 9 figs

  18. Inactivation model for disinfection of biofilms in drinking water

    International Nuclear Information System (INIS)

    The purpose of the project was to investigate experimentally the effects of free chlorine, monochloramine and chlorine dioxide on the removal of biofilm growth in water as it applies to drinking water in distribution systems. In particular, biofilm kill for a particular dosage of disinfectant was measured as a function of time for each disinfectant over a range of disinfectant concentrations. These results were used to formulate concentration-time (Ct) inactivation values for each disinfectant to compare the efficacy of the three disinfectants for biofilm control. The biofilm reactor system consisted of a 125 mL columns, each containing tightly packed 3 mm glass beads on which heterotrophic bacterial biofilm is established. Following an initial biofilm inoculation period, the glass beads were removed from the columns and placed into glass jars for disinfection with free chlorine, monochloramine and chlorine dioxide. Cell counts were determined on a time series basis with the goal of achieving a Ct inactivation model that is similar to models presently used for inactivation of suspended cells. Ultimately this research could be used to develop a rationale method for setting regulatory values for secondary disinfection in drinking water distribution systems, which presently in only a few states and provinces. (author)

  19. Development of tokamak reactor systems analysis code 'TORSAC'

    International Nuclear Information System (INIS)

    This report describes Tokamak Reactor Systems Analysis Code ''TORSAC'' which has been developed in order to assess the impact of the design choises on reactor systems and to improve tokamak designs in wide parameter range. This computer code has following functions. (1) Systematic sensitivity analysis for a set of given design parameters, (2) Cost calculation of a new reactor concept designed automatically as a result of systematic sensitivity analysis. (author)

  20. Development of Denitrifying and Nitrifying Bacteria and Their Co-occurrence in Newly Created Biofilms in Urban Streams

    Science.gov (United States)

    Vaessen, T. N.; Martí Roca, E.; Pinay, G.; Merbt, S. N.

    2015-12-01

    Biofilms play a pivotal role on nutrient cycling in streams, which ultimately dictates the export of nutrients to downstream ecosystems. The extent to which biofilms influence the concentration of dissolved nutrients, oxygen and pH in the water column may be determined by the composition of the microbial assemblages and their activity. Evidence of biological interactions among bacteria and algae are well documented. However, the development, succession and co-occurence of nitrifying and denitrifying bacteria remain poorly understood. These bacteria play a relevant role on the biogeochemical process associated to N cycling, and their relative abundance can dictate the fate of dissolved inorganic nitrogen in streams. In particular, previous studies indicated that nitrifiers are enhanced in streams receiving inputs from wastewater treatment plant (WWTP) effluents due to both increases in ammonium concentration and inputs of nitrifiers. However, less is known about the development of denitrifiers in receiving streams, although environmental conditions seem to favor it. We conducted an in situ colonization experiment in a stream receiving effluent from a WWTP to examine how this input influences the development and co-occurrence of nitrifying and denitrifying bacteria. We placed artificial substrata at different locations relative to the effluent and sampled them over time to characterize the developed biofilm in terms of bulk measurements (organic matter content and algae) as well as in terms of abundance of nitrifiers and denitrifiers (using qPCR). The results of this study contribute to a better understanding of the temporal dynamics of denitrifiers and nitrifiers in relation to the developed organic matter, dissolved oxygen and pH and the biomass accrual in stream biofilms under the influence of nutrients inputs from WWTP effluent. Ultimately, the results provide insights on the potential role of nitrifiers and denitrifiers on N cycling in WWTP effluent receiving