Start-Up and Aeration Strategies for a Completely Autotrophic Nitrogen Removal Process in an SBR

Directory of Open Access Journals (Sweden)

Xiaoling Zhang

2017-01-01

Full Text Available The start-up and performance of the completely autotrophic nitrogen removal via nitrite (CANON process were examined in a sequencing batch reactor (SBR with intermittent aeration. Initially, partial nitrification was established, and then the DO concentration was lowered further, surplus water in the SBR with high nitrite was replaced with tap water, and continuous aeration mode was turned into intermittent aeration mode, while the removal of total nitrogen was still weak. However, the total nitrogen (TN removal efficiency and nitrogen removal loading reached 83.07% and 0.422 kgN/(m3·d, respectively, 14 days after inoculating 0.15 g of CANON biofilm biomass into the SBR. The aggregates formed in SBR were the mixture of activated sludge and granular sludge; the volume ratio of floc and granular sludge was 7 : 3. DNA analysis showed that Planctomycetes-like anammox bacteria and Nitrosomonas-like aerobic ammonium oxidization bacteria were dominant bacteria in the reactor. The influence of aeration strategies on CANON process was investigated using batch tests. The result showed that the strategy of alternating aeration (1 h and nonaeration (1 h was optimum, which can obtain almost the same TN removal efficiency as continuous aeration while reducing the energy consumption, inhibiting the activity of NOB, and enhancing the activity of AAOB.

Sludge granulation in an UASB-moving bed biofilm hybrid reactor for efficient organic matter removal and nitrogen removal in biofilm reactor.

Science.gov (United States)

Chatterjee, Pritha; Ghangrekar, M M; Rao, Surampalli

2018-02-01

A hybrid upflow anaerobic sludge blanket (UASB)-moving bed biofilm (MBB) and rope bed biofilm (RBB) reactor was designed for treatment of sewage. Possibility of enhancing granulation in an UASB reactor using moving media to improve sludge retention was explored while treating low-strength wastewater. The presence of moving media in the top portion of the UASB reactor allowed a high solid retention time even at very short hydraulic retention times and helped in maintaining selection pressure in the sludge bed to promote formation of different sized sludge granules with an average settling velocity of 67 m/h. These granules were also found to contain plenty of extracellular polymeric substance (EPS) such as 58 mg of polysaccharides (PS) per gram of volatile suspended solids (VSS) and protein (PN) content of 37 mg/g VSS. Enriched sludge of nitrogen-removing bacteria forming a porous biofilm on the media in RBB was also observed in a concentration of around 894 g/m 2 . The nitrogen removing sludge also had a high EPS content of around 22 mg PS/g VSS and 28 mg PN/g VSS. This hybrid UASB-MBB-RBB reactor with enhanced anaerobic granular sludge treating both carbonaceous and nitrogenous matter may be a sustainable solution for decentralized sewage treatment.

META-ANALYSIS OF NITROGEN REMOVAL IN RIPARIAN BUFFERS

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Riparian buffer zones, the vegetated region adjacent to streams and wetlands, are thought to be effective at intercepting and controlling nitrogen loads entering water bodies. Riparian buffer width may be positively related to nitrogen removal effectiveness by influencing nitrog...

Nitrogen removal from concentrated latex wastewater by land treatment

Directory of Open Access Journals (Sweden)

Vikanda Thongnuekhang

2004-05-01

Full Text Available Most of the concentrated latex factories in the South of Thailand discharge treated wastewater that contains high level of nitrogen to a nearby river or canals leading to a water pollution problem. A study of land treatment system was conducted to treat and utilize nitrogen in treated wastewater from the concentrated latex factory. The experimental pilot-scale land treatment system was constructed at the Faculty of Engineering, Prince of Songkla University, Hat Yai Campus. It consisted of water convolvulus (Ipomea aquatica, I. Reptans, tropical carpet grass (Axonopus compresus (Swartz Beav. and control unit (no plantation. The treated wastewater from the stabilization pond system of the selected concentrated latex factoryin Songkhla was used to irrigate each experimental unit. Influent and effluent from the experimental units were analyzed for TKN, NH3-N, Org-N, NO3 --N, NO2 --N, BOD5, sulfate, pH and EC. The land treatment system resulted a high removal efficiency for nitrogen. Tropical carpet grass provided higher removal efficiency than other units for all parameters. The removal efficiency of water convolvulus and control unit were not significantly different. The average removal efficiency of TKN, NH3-N, Org-N, BOD5 and sulfate for tropical carpet grass unit were 92, 97, 61, 88 and 52%, for water convolvulus unit were 75, 80, 43, 41 and 30%, and for control unit were 74, 80, 41, 31 and 28%, respectively. Mass balance of nitrogen transformation was conducted. It revealed that plant uptake was the major mechanism for nitrogen removal in land treatment.

Nitrogen Removal in Greywater Living Walls: Insights into the Governing Mechanisms

Directory of Open Access Journals (Sweden)

Harsha S. Fowdar

2018-04-01

Full Text Available Nitrogen is a pollutant of great concern when present in excess in surface waters. Living wall biofiltration systems that employ ornamentals and climbing plants are an emerging green technology that has recently demonstrated significant potential to reduce nitrogen concentrations from greywater before outdoor domestic re-use. However, there still exists a paucity of knowledge around the mechanisms governing this removal, particularly in regards to the fate of dissolved organic nitrogen (DON within these systems. Understanding the fate of nitrogen in living wall treatment systems is imperative both to optimise designs and to predict the long-term viability of these systems, more so given the growing interest in adopting green infrastructure within urban cities. A laboratory study was undertaken to investigate the transformation and fate of nitrogen in biofilters planted with different climbing plants and ornamental species. An isotropic tracer (15N-urea was applied to quantify the amount removed through coupled nitrification-denitrification. The results found that nitrification-denitrification formed a minor removal pathway in planted systems, comprising only 0–15% of added 15N. DON and ammonium were effectively reduced by all biofilter designs, indicating effective mineralisation and nitrification rates. However, in designs with poor nitrogen removal, the effluent was enriched with nitrate, suggesting limited denitrification rates. Given the likely dominance of plant assimilation in removal, this indicates that plant selection is a critical design parameter, as is maintaining healthy plant growth for optimal nitrogen removal in greywater living wall biofilters in their early years of operation.

Synergic Adsorption–Biodegradation by an Advanced Carrier for Enhanced Removal of High-Strength Nitrogen and Refractory Organics

KAUST Repository

Ahmad, Muhammad; Liu, Sitong; Mahmood, Nasir; Mahmood, Asif; Ali, Muhammad; Zheng, Maosheng; Ni, Jinren

2017-01-01

Coking wastewater contains not only high-strength nitrogen but also toxic biorefractory organics. This study presents simultaneous removal of high-strength quinoline, carbon, and ammonium in coking wastewater by immobilized bacterial communities

Mechanism of nitrogen removal in wastewater lagoon: a case study.

Science.gov (United States)

Vendramelli, Richard A; Vijay, Saloni; Yuan, Qiuyan

2017-06-01

Ammonia being a nutrient facilitates the growth of algae in wastewater and causes eutrophication. Nitrate poses health risk if it is present in drinking water. Hence, nitrogen removal from wastewater is required. Lagoon wastewater treatment systems have become common in Canada these days. The study was conducted to understand the nitrogen removal mechanisms from the existing wastewater treatment lagoon system in the town of Lorette, Manitoba. The lagoon system consists of two primary aerated cells and two secondary unaerated cells. Surface samples were collected periodically from lagoon cells and analysed from 5 May 2015 to 9 November 2015. The windward and leeward sides of the ponds were sampled and the results were averaged. It was found that the free ammonia volatilization to the atmosphere is responsible for most of the ammonia removal. Ammonia and nitrate assimilation into biomass and biological growth in the cells appears to be the other mechanisms of nitrogen removal over the monitoring period. Factors affecting the nitrogen removal efficiency were found to be pH, temperature and hydraulic residence time. Also, the ammonia concentration in the effluent from the wastewater treatment lagoon was compared with the regulatory standard.

Removal of nitrogen by a layered soil infiltration system during intermittent storm events.

Science.gov (United States)

Cho, Kang Woo; Song, Kyung Guen; Cho, Jin Woo; Kim, Tae Gyun; Ahn, Kyu Hong

2009-07-01

The fates of various nitrogen species were investigated in a layered biological infiltration system under an intermittently wetting regime. The layered system consisted of a mulch layer, coarse soil layer (CSL), and fine soil layer (FSL). The effects of soil texture were assessed focusing on the infiltration rate and the removal of inorganic nitrogen species. The infiltration rate drastically decreased when the uniformity coefficient was larger than four. The ammonium in the synthetic runoff was shown to be removed via adsorption during the stormwater dosing and nitrification during subsequent dry days. Stable ammonium adsorption was observed when the silt and clay content of CSL was greater than 3%. This study revealed that the nitrate leaching was caused by nitrification during dry days. Various patterns of nitrate flushing were observed depending on the soil configuration. The washout of nitrate was more severe as the silt/clay content of the CSL was greater. However, proper layering of soil proved to enhance the nitrate removal. Consequently, a strictly sandy CSL over FSL with a silt and clay content of 10% was the best configuration for the removal of ammonium and nitrate.

Ammonium nitrogen removal from coking wastewater by chemical precipitation recycle technology.

Science.gov (United States)

Zhang, Tao; Ding, Lili; Ren, Hongqiang; Xiong, Xiang

2009-12-01

Ammonium nitrogen removal from wastewater has been of considerable concern for several decades. In the present research, we examined chemical precipitation recycle technology (CPRT) for ammonium nitrogen removal from coking wastewater. The pyrolysate resulting from magnesium ammonium phosphate (MAP) pyrogenation in sodium hydroxide (NaOH) solution was recycled for ammonium nitrogen removal from coking wastewater. The objective of this study was to investigate the conditions for MAP pyrogenation and to characterize of MAP pyrolysate for its feasibility in recycling. Furthermore, MAP pyrolysate was characterized by scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) as well as X-ray diffraction (XRD). The MAP pyrolysate could be produced at the optimal condition of a hydroxyl (OH(-)) to ammonium molar ratio of 2:1, a heating temperature of 110 degrees C, and a heating time of 3h. Surface characterization analysis indicated that the main component of the pyrolysate was amorphous magnesium sodium phosphate (MgNaPO(4)). The pyrolysate could be recycled as a magnesium and phosphate source at an optimum pH of 9.5. When the recycle times were increased, the ammonium nitrogen removal ratio gradually decreased if the pyrolysate was used without supplementation. When the recycle times were increased, the ammonium nitrogen removal efficiency was not decreased if the added pyrolysate was supplemented with MgCl(2).6H(2)O plus Na(2)HPO(4).12H(2)O during treatment. A high ammonium nitrogen removal ratio was obtained by using pre-formed MAP as seeding material.

Oxygen Limited Bioreactors System For Nitrogen Removal Using Immobilized Mix Culture

Science.gov (United States)

Pathak, B. K.; Sumino, T.; Saiki, Y.; Kazama, F.

2005-12-01

Recently nutrients concentrations especially nitrogen in natural water is alarming in the world wide. Most of the effort is being done on the removal of high concentration of nitrogen especially from the wastewater treatment plants. The removal efficiency is targeted in all considering the effluent discharge standard set by the national environment agency. In many cases, it does not meet the required standard and receiving water is being polluted. Eutrophication in natural water bodies has been reported even if the nitrogen concentration is low and self purification of natural systems itself is not sufficient to remove the nitrogen due to complex phenomenon. In order to recover the pristine water environment, it is very essential to explore bioreactor systems for natural water systems using immobilized mix culture. Microorganism were entrapped in Polyethylene glycol (PEG) prepolymer gel and cut into 3mm cubic immobilized pellets. Four laboratory scale micro bio-reactors having 0.1 L volumes were packed with immobilized pellets with 50% compact ratio. RUN1, RUN2, RUN3 and RUN4 were packed with immobilized pellets from reservoirs sediments, activated sludge (AS), mixed of AS, AG and biodegradable plastic and anaerobic granules (AG) respectively. Water from Shiokawa Reservoirs was feed to all reactors with supplemental ammonia and nitrite nitrogen as specified in the results and discussions. The reactors were operated dark incubated room in continuous flow mode with hydraulic retention time of 12 hours under oxygen limiting condition. Ammonium, nitrate nitrite nitrogen and total organic carbon (TOC) concentrations were measured as described in APWA and AWWA (1998). Laboratory scale four bioreactors containing different combination of immobilized cell were monitored for 218 days. Influent NH4+-N and NO2--N concentration were 2.27±0.43 and 2.05±0.41 mg/l respectively. Average dissolved oxygen concentration and pH in the reactors were 0.40-2.5 mg/l and pH 6

Antipollution system to remove nitrogen dioxide gas

Science.gov (United States)

Metzler, A. J.; Slough, J. W.

1971-01-01

Gas phase reaction system using anhydrous ammonia removes nitrogen dioxide. System consists of ammonia injection and mixing section, reaction section /reactor/, and scrubber section. All sections are contained in system ducting.

Simultaneous removal of nitrogen oxides and sulfur oxides from combustion gases

Science.gov (United States)

Clay, David T.; Lynn, Scott

1976-10-19

A process for the simultaneous removal of sulfur oxides and nitrogen oxides from power plant stack gases comprising contacting the stack gases with a supported iron oxide catalyst/absorbent in the presence of sufficient reducing agent selected from the group consisting of carbon monoxide, hydrogen, and mixtures thereof, to provide a net reducing atmosphere in the SO.sub.x /NO.sub.x removal zone. The sulfur oxides are removed by absorption substantially as iron sulfide, and nitrogen oxides are removed by catalytic reduction to nitrogen and ammonia. The spent iron oxide catalyst/absorbent is regenerated by oxidation and is recycled to the contacting zone. Sulfur dioxide is also produced during regeneration and can be utilized in the production of sulfuric acid and/or sulfur.

Further contributions to the understanding of nitrogen removal in waste stabilization ponds.

Science.gov (United States)

Bastos, R K X; Rios, E N; Sánchez, I A

2018-06-01

A set of experiments were conducted in Brazil in a pilot-scale waste stabilization pond (WSP) system (a four-maturation-pond series) treating an upflow anaerobic sludge blanket (UASB) reactor effluent. Over a year and a half the pond series was monitored under two flow rate conditions, hence also different hydraulic retention times and surface loading rates. On-site and laboratory trials were carried out to assess: (i) ammonia losses by volatilization using acrylic capture chambers placed at the surface of the ponds; (ii) organic nitrogen sedimentation rates using metal buckets placed at the bottom of the ponds for collecting settled particulate matter; (iii) nitrogen removal by algal uptake based on the nitrogen content of the suspended particulate matter in samples from the ponds' water column. In addition, nitrification and denitrification rates were measured in laboratory-based experiments using pond water and sediment samples. The pond system achieved high nitrogen removal (69% total nitrogen and 92% ammonia removal). The average total nitrogen removal rates varied from 10,098 to 3,849 g N/ha·d in the first and the last ponds, respectively, with the following fractions associated with the various removal pathways: (i) 23.5-45.6% sedimentation of organic nitrogen; (ii) 13.1-27.8% algal uptake; (iii) 1.2-3.1% ammonia volatilization; and (iv) 0.15-0.34% nitrification-denitrification.

Nitrate-nitrogen removal with small-scale reverse osmosis ...

African Journals Online (AJOL)

The nitrate-nitrogen concentration in water supplied to clinics in Limpopo Province is too high to be fit for human consumption (35 to 75 mg/ℓ NO3-N). Therefore, small-scale technologies (reverse osmosis, ion-exchange and electrodialysis) were evaluated for nitrate-nitrogen removal to make the water potable (< 10 mg/ℓ ...

Enhanced nitrogen removal from electroplating tail wastewater through two-staged anoxic-oxic (A/O) process.

Science.gov (United States)

Yan, Xinmei; Zhu, Chunyan; Huang, Bin; Yan, Qun; Zhang, Guangsheng

2018-01-01

Consisted of anaerobic (ANA), anoxic-1 (AN1), aerobic-1 (AE1), anoxic-2 (AN2), aerobic-2 (AE2) reactors and sediment tank, the two-staged A/O process was applied for depth treatment of electroplating tail wastewater with high electrical conductivity and large amounts of ammonia nitrogen. It was found that the NH 4 + -N and COD removal efficiencies reached 97.11% and 83.00%, respectively. Besides, the short-term salinity shock of the control, AE1 and AE2 indicated that AE1 and AE2 have better resistance to high salinity when the concentration of NaCl ranged from 1 to 10g/L. Meanwhile, it was found through high-throughput sequencing that bacteria genus Nitrosomonas, Nitrospira and Thauera, which are capable of nitrogen removal, were enriched in the two-staged A/O process. Moreover, both salt-tolerant bacteria and halophili bacteria were also found in the combined process. Therefore, microbial community within the two-staged A/O process could be acclimated to high electrical conductivity, and adapted for electroplating tail wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Redox stratified biofilms to support completely autotrophic nitrogen removal: Principles and results

DEFF Research Database (Denmark)

Pellicer i Nàcher, Carles; Smets, Barth F.

liquid. If operated properly, MABRs yield compact and homogeneous redox-stratified biofilms capable of hosting side-by-side aerobic and anaerobic microbial communities. We have recently demonstrated that completely autotrophic nitrogen removal is feasible in MABRs at nitrogen removal rates as high as 5......After 10 years of pilot and full-scale studies, completely autotrophic nitrogen via coupled aerobic and anaerobic ammonium oxidation is now firmly established in the wastewater treatment community. The reasons for the popularization of the technology are numerous, but the most attractive....... The continuous and sustained inoculation of metabolically active anaerobic oxidizing bacteria from a biofilm reactor placed in the recirculation line of our MABRs showed to shorten considerably the onset of autotrophic nitrogen removal. However, the main hurdle keeping MABRs from attaining high removal...

[Characteristics of nitrogen and phosphorus removal and control of membrane fouling in MBR and SMBR].

Science.gov (United States)

Guo, Xiao-Ma; Zhao, Yan; Wang, Kai-Yan; Zhao Yang-Guo

2015-03-01

To improve the efficiency and running stability of wastewater advanced treatment, a sequencing membrane bioreactor (SMBR) and a traditional membrane bioreactor (MBR) were used to investigate the characteristics of nitrogen and phosphorus removal, and the effect of anoxic time on treatment systems and membrane fouling. Simultaneously, molecular biology techniques were applied to analyze the composition of microbial community and the structure of suspended sludge. The results showed that SMBR had higher efficiency in removing TN than MBR, which indicated that intermittent aeration could enhance the ability of nitrogen removal. SMBR and MBR had a similar removal efficiency of NH4(+)-N, TP, COD, and turbidity with the removal rates of 94%, 78%, 80%, and 97%, respectively. Extension of SMBR anoxic time had no effect on COD, NH4(+) -N removal but decreased TN and TP removal rate, dropping from 61% and 74% to 46% and 52%, respectively. Intermittent aeration and powder activated carbon (PAC) could both mitigate membrane fouling. The analysis on microbial community indicated that there was no difference in the composition and structure of microbial community between SMBR and MBR. Nitrospira and Dechloromonas were both highly abundant functional groups, which provided the basis for highly efficient control of bioreactors.

Liquid Nitrogen Removal of Critical Aerospace Materials

Science.gov (United States)

Noah, Donald E.; Merrick, Jason; Hayes, Paul W.

2005-01-01

Identification of innovative solutions to unique materials problems is an every-day quest for members of the aerospace community. Finding a technique that will minimize costs, maximize throughput, and generate quality results is always the target. United Space Alliance Materials Engineers recently conducted such a search in their drive to return the Space Shuttle fleet to operational status. The removal of high performance thermal coatings from solid rocket motors represents a formidable task during post flight disassembly on reusable expended hardware. The removal of these coatings from unfired motors increases the complexity and safety requirements while reducing the available facilities and approved processes. A temporary solution to this problem was identified, tested and approved during the Solid Rocket Booster (SRB) return to flight activities. Utilization of ultra high-pressure liquid nitrogen (LN2) to strip the protective coating from assembled space shuttle hardware marked the first such use of the technology in the aerospace industry. This process provides a configurable stream of liquid nitrogen (LN2) at pressures of up to 55,000 psig. The performance of a one-time certification for the removal of thermal ablatives from SRB hardware involved extensive testing to ensure adequate material removal without causing undesirable damage to the residual materials or aluminum substrates. Testing to establish appropriate process parameters such as flow, temperature and pressures of the liquid nitrogen stream provided an initial benchmark for process testing. Equipped with these initial parameters engineers were then able to establish more detailed test criteria that set the process limits. Quantifying the potential for aluminum hardware damage represented the greatest hurdle for satisfying engineers as to the safety of this process. Extensive testing for aluminum erosion, surface profiling, and substrate weight loss was performed. This successful project clearly

Research on the enhancement of biological nitrogen removal at low temperatures from ammonium-rich wastewater by the bio-electrocoagulation technology in lab-scale systems, pilot-scale systems and a full-scale industrial wastewater treatment plant.

Science.gov (United States)

Li, Liang; Qian, Guangsheng; Ye, Linlin; Hu, Xiaomin; Yu, Xin; Lyu, Weijian

2018-04-17

In cold areas, nitrogen removal performance of wastewater treatment plants (WWTP) declines greatly in winter. This paper systematically describes the enhancement effect of a periodic reverse electrocoagulation technology on biological nitrogen removal at low temperatures. The study showed that in the lab-scale systems, the electrocoagulation technology improved the biomass amount, enzyme activity and the amount of nitrogen removal bacteria (Nitrosomonas, Nitrobacter, Paracoccus, Thauera and Enterobacter). This enhanced nitrification and denitrification of activated sludge at low temperatures. In the pilot-scale systems, the electrocoagulation technology increased the relative abundance of cold-adapted microorganisms (Luteimonas and Trueperaceae) at low temperatures. In a full-scale industrial WWTP, comparison of data from winter 2015 and winter 2016 showed that effluent chemical oxygen demand (COD), NH 4 + -N, and NO 3 - -N reduced by 10.37, 3.84, and 136.43 t, respectively, throughout the winter, after installation of electrocoagulation devices. These results suggest that the electrocoagulation technology is able to improve the performance of activated sludge under low-temperature conditions. This technology provides a new way for upgrading of the performance of WWTPs in cold areas. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nitrogen removal and microbial communities in a three-stage system simulating a riparian environment.

Science.gov (United States)

Wang, Ziyuan; Wang, Zhixin; Pei, Yuansheng

2014-06-01

The riparian zone is an active interface for nitrogen removal, in which nitrogen transformations by microorganisms have not been valued. In this study, a three-stage system was constructed to simulate the riparian zone environments, and nitrogen removal as well as the microbial community was investigated in this 'engineered riparian system'. The results demonstrated that stage 1 of this system accounted for 41-51 % of total nitrogen removal. Initial ammonium loading and redox potential significantly impacted the nitrogen removal performances. Stages 1 and 2 were both composed of an anoxic/oxic (A/O) zone and an anaerobic column. The A/O zone removed most of the ammonium load (6.8 g/m(2)/day), while the anaerobic column showed a significant nitrate removal rate (11.1 g/m(2)/day). Molecular biological analysis demonstrated that bacterial diversity was high in the A/O zones, where ammonium-oxidizing bacteria and nitrite-oxidizing bacteria accounted for 8.42 and 3.32 % of the bacterial population, respectively. The denitrifying bacteria Acidovorax sp. and the nitrifying bacteria Nitrosospira/Nitrosomonas were the predominant microorganisms in this engineered riparian system. This three-stage system was established to achieve favorable nitrogen removal and the microbial community in the system was also retained. This investigation should deepen our understanding of biological nitrogen removal in engineered riparian zones.

Mathematical modeling of simultaneous carbon-nitrogen-sulfur removal from industrial wastewater.

Science.gov (United States)

Xu, Xi-Jun; Chen, Chuan; Wang, Ai-Jie; Ni, Bing-Jie; Guo, Wan-Qian; Yuan, Ye; Huang, Cong; Zhou, Xu; Wu, Dong-Hai; Lee, Duu-Jong; Ren, Nan-Qi

2017-01-05

A mathematical model of carbon, nitrogen and sulfur removal (C-N-S) from industrial wastewater was constructed considering the interactions of sulfate-reducing bacteria (SRB), sulfide-oxidizing bacteria (SOB), nitrate-reducing bacteria (NRB), facultative bacteria (FB), and methane producing archaea (MPA). For the kinetic network, the bioconversion of C-N by heterotrophic denitrifiers (NO 3 - →NO 2 - →N 2 ), and that of C-S by SRB (SO 4 2- →S 2- ) and SOB (S 2- →S 0 ) was proposed and calibrated based on batch experimental data. The model closely predicted the profiles of nitrate, nitrite, sulfate, sulfide, lactate, acetate, methane and oxygen under both anaerobic and micro-aerobic conditions. The best-fit kinetic parameters had small 95% confidence regions with mean values approximately at the center. The model was further validated using independent data sets generated under different operating conditions. This work was the first successful mathematical modeling of simultaneous C-N-S removal from industrial wastewater and more importantly, the proposed model was proven feasible to simulate other relevant processes, such as sulfate-reducing, sulfide-oxidizing process (SR-SO) and denitrifying sulfide removal (DSR) process. The model developed is expected to enhance our ability to predict the treatment of carbon-nitrogen-sulfur contaminated industrial wastewater. Copyright © 2016 Elsevier B.V. All rights reserved.

Synergic Adsorption–Biodegradation by an Advanced Carrier for Enhanced Removal of High-Strength Nitrogen and Refractory Organics

KAUST Repository

Ahmad, Muhammad

2017-03-29

Coking wastewater contains not only high-strength nitrogen but also toxic biorefractory organics. This study presents simultaneous removal of high-strength quinoline, carbon, and ammonium in coking wastewater by immobilized bacterial communities composed of a heterotrophic strain Pseudomonas sp. QG6 (hereafter referred as QG6), ammonia-oxidizing bacteria (AOB), and anaerobic ammonium oxidation bacteria (anammox). The bacterial immobilization was implemented with the help of a self-designed porous cubic carrier that created structured microenvironments including an inner layer adapted for anaerobic bacteria, a middle layer suitable for coaggregation of certain aerobic and anaerobic bacteria, and an outer layer for heterotrophic bacteria. By coating functional polyurethane foam (FPUF) with iron oxide nanoparticles (IONPs), the biocarrier (IONPs-FPUF) could provide a good outer-layer barrier for absorption and selective treatment of aromatic compounds by QG6, offer a conducive environment for anammox in the inner layer, and provide a mutualistic environment for AOB in the middle layer. Consequently, simultaneous nitrification and denitrification were reached with the significant removal of up to 322 mg L (98%) NH, 311 mg L (99%) NO, and 633 mg L (97%) total nitrogen (8 mg L averaged NO concentration was recorded in the effluent), accompanied by an efficient removal of chemical oxygen demand by 3286 mg L (98%) and 350 mg L (100%) quinoline. This study provides an alternative way to promote synergic adsorption and biodegradation with the help of a modified biocarrier that has great potential for treatment of wastewater containing high-strength carbon, toxic organic pollutants, and nitrogen.

Synergic Adsorption-Biodegradation by an Advanced Carrier for Enhanced Removal of High-Strength Nitrogen and Refractory Organics.

Science.gov (United States)

Ahmad, Muhammad; Liu, Sitong; Mahmood, Nasir; Mahmood, Asif; Ali, Muhammad; Zheng, Maosheng; Ni, Jinren

2017-04-19

Coking wastewater contains not only high-strength nitrogen but also toxic biorefractory organics. This study presents simultaneous removal of high-strength quinoline, carbon, and ammonium in coking wastewater by immobilized bacterial communities composed of a heterotrophic strain Pseudomonas sp. QG6 (hereafter referred as QG6), ammonia-oxidizing bacteria (AOB), and anaerobic ammonium oxidation bacteria (anammox). The bacterial immobilization was implemented with the help of a self-designed porous cubic carrier that created structured microenvironments including an inner layer adapted for anaerobic bacteria, a middle layer suitable for coaggregation of certain aerobic and anaerobic bacteria, and an outer layer for heterotrophic bacteria. By coating functional polyurethane foam (FPUF) with iron oxide nanoparticles (IONPs), the biocarrier (IONPs-FPUF) could provide a good outer-layer barrier for absorption and selective treatment of aromatic compounds by QG6, offer a conducive environment for anammox in the inner layer, and provide a mutualistic environment for AOB in the middle layer. Consequently, simultaneous nitrification and denitrification were reached with the significant removal of up to 322 mg L -1 (98%) NH 4 , 311 mg L -1 (99%) NO 2 , and 633 mg L -1 (97%) total nitrogen (8 mg L -1 averaged NO 3 concentration was recorded in the effluent), accompanied by an efficient removal of chemical oxygen demand by 3286 mg L -1 (98%) and 350 mg L -1 (100%) quinoline. This study provides an alternative way to promote synergic adsorption and biodegradation with the help of a modified biocarrier that has great potential for treatment of wastewater containing high-strength carbon, toxic organic pollutants, and nitrogen.

Removal of ammonia nitrogen in wastewater by microwave radiation: A pilot-scale study

International Nuclear Information System (INIS)

Lin Li; Chen Jing; Xu Zuqun; Yuan Songhu; Cao Menghua; Liu Huangcheng; Lu Xiaohua

2009-01-01

A large removal of ammonia nitrogen in wastewater has been achieved by microwave (MW) radiation in our previous bench-scale study. This study developed a continuous pilot-scale MW system to remove ammonia nitrogen in real wastewater. A typical high concentration of ammonia nitrogen contaminated wastewater, the coke-plant wastewater from a Coke company, was treated. The output power of the microwave reactor was 4.8 kW and the handling capacity of the reactor was about 5 m 3 per day. The ammonia removal efficiencies under four operating conditions, including ambient temperature, wastewater flow rate, aeration conditions and initial concentration were evaluated in the pilot-scale experiments. The ammonia removal could reach about 80% for the real coke-plant wastewater with ammonia nitrogen concentrations of 2400-11000 mg/L. The running cost of the MW technique was a little lower than the conventional steam-stripping method. The continuous microwave system showed the potential as an effective method for ammonia nitrogen removal in coke-plant water treatment. It is proposed that this process is suitable for the treatment of toxic wastewater containing high concentrations of ammonia nitrogen.

Nitrogen and phosphorus removed from a subsurface flow multi-stage filtration system purifying agricultural runoff.

Science.gov (United States)

Zhao, Yaqi; Huang, Lei; Chen, Yucheng

2018-07-01

Agricultural nonpoint source pollution has been increasingly serious in China since the 1990s. The main causes were excessive inputs of nitrogen fertilizer and pesticides. A multi-stage filtration system was built to test the purification efficiencies and removal characteristics of nitrogen and phosphorus when treating agricultural runoff. Simulated runoff pollution was prepared by using river water as source water based on the monitoring of local agricultural runoff. Experimental study had been performed from September to November 2013, adopting 12 h for flooding and 12 h for drying. The results showed that the system was made adaptive to variation of inflow quality and quantity, and had good removal for dissolved total nitrogen, total nitrogen, dissolved total phosphorus (DTP), and total phosphorus, and the average removal rate was 27%, 36%, 32%, and 48%, respectively. Except nitrate ([Formula: see text]), other forms of nitrogen and phosphorus all decreased with the increase of stages. Nitrogen was removed mainly in particle form the first stage, and mostly removed in dissolved form the second and third stage. Phosphorus was removed mainly in particulate during the first two stages, but the removal of particulate phosphorus and DTP were almost the same in the last stage. An approximate logarithmic relationship between removal loading and influent loading to nitrogen and phosphorus was noted in the experimental system, and the correlation coefficient was 0.78-0.94. [Formula: see text]: ammonium; [Formula: see text]: nitrite; [Formula: see text]: nitrate; DTN: dissolved total nitrogen; TN: total nitrogen; DTP: dissolved total phosphorus; TP: total phosphorus; PN: particulate nitrogen; PP: particulate phosphorus.

Nitrogen removal from landfill leachate via ex situ nitrification and sequential in situ denitrification

International Nuclear Information System (INIS)

Zhong Qi; Li Daping; Tao Yong; Wang Xiaomei; He Xiaohong; Zhang Jie; Zhang Jinlian; Guo Weiqiang; Wang Lan

2009-01-01

Ex situ nitrification and sequential in situ denitrification represents a novel approach to nitrogen management at landfills. Simultaneous ammonia and organics removal was achieved in a continuous stirred tank reactor (CSTR). The results showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l -1 d -1 and 3.84 g COD l -1 d -1 , respectively. The ammonia and chemical oxygen demand (COD) removal was over 99% and 57%, respectively. In the run of the CSTR, free ammonia (FA) inhibition and low dissolved oxygen (DO) were found to be key factors affecting nitrite accumulation. In situ denitrification was studied in a municipal solid waste (MSW) column by recalculating nitrified leachate from CSTR. The decomposition of MSW was accelerated by the recirculation of nitrified leachate. Complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON loading of 28.6 g N t -1 TS d -1 and denitrification was the main reaction responsible. Additionally, methanogenesis inhibition was observed while TON loading was over 11.4 g N t -1 TS d -1 and the inhibition was enhanced with the increase of TON loading

Effects of Nitrogen and Nutrient Removal on Nitrate Accumulation and Growth Characteristics of Spinach (Spinacia oleraceae L.

Directory of Open Access Journals (Sweden)

mohammadsadegh sadeghi

2017-12-01

was conducted with twolevels of removal (removal of nutrient one week before harvest or not to remove and fourlevels of nitrogen (25, 50, 100 and 200 mg/l with sixreplications. During the growing season in the greenhouse, temperature was fixed between 24-27 °C and photoperiod of 16 hours of light and 8 hours of darkness. The measured traits were root fresh and dry weight, shoot fresh and dry weight, Fv/Fm ratio, and chlorophyll index, number of leaf per plant, leaf area, nitrate and total nitrogen. Results and Discussion: The results of this experiment showed that increasingnitrogen concentration from 25 to 200 mg/l increased shoot dry weight, number of leaves and leaf area, by 22.00, 7.26, 4.79 and 14.00 fold, respectively. Nitrogen also increased Fv/Fm and chlorophyll index. Nutrient removal in a week before harvest had no significant effect on fresh and dry weight of shoots and roots, number of leaves,leaf area, chlorophyll index and Fv/Fm. Increasing concentrations of nitrogen increased nitrate and total nitrogen in petiole while removing the nutrient solution in a week before harvest significantly decreased amounts of the above-mentioned traits. Nutrient solution removal is an appropriate strategy to reduce nitrate accumulation in spinach that has no effect on yield loss. Conclusions: The results showed that increasing the concentration of nitrogen increased plant growth indicators such as shoot fresh and dry weight, root fresh and dry weight, leaf area and number of leaf per plants, so that the greatest increase was obtained from concentration of 200 mg/lit. Increasing the concentration of nitrogen enhanced nitrate and total nitrogen of petiole so that the highest concentration of nitrate and total nitrogen was observed in200 mg/lit nitrogen. Nutrient solution removal in a week before the harvest had a significant effect in reducing all traits but it decreased nitrate accumulation and total nitrogen of petiole significantly. At the end of the experiment, it was

Removal of organic nitrogen compounds in LCO reduces the hydrodesulphurization severity

Energy Technology Data Exchange (ETDEWEB)

Yang, H.; Chen, J.; Ring, Z. [National Centre for Upgrading Technology, Devon, AB (Canada)

2006-07-01

Canada and the United States committed to reducing diesel sulphur from 500 to 15 part per million by 2006. Refineries could benefit from a better understanding of the effects of feed matrix on sulphur removal by hydrodesulphurization (HDS) in selecting the right feed or feed pre-treatment options for their existing HDS units and achieve the required sulphur level at minimum cost. This paper presented a study that examined the influence of nitrogen compounds on the HDS activities of substituted dibenzothiophenes in light oil cycle over a nitrogen/molybdenum on alumina oxide (Al{sub 2}O{sub 3}) commercial catalyst using five light cycle oil feeds with different concentrations of organic nitrogen compounds. The paper discussed experiments that were conducted under conditions close to industrial HDS processes. The paper addressed feed preparation; the nitrogen effect on HDS reactivity of dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyl dibenzothiophene; sulphur composition analysis; hydrodenitrogenation; and kinetic modeling. It was concluded that organic nitrogen compounds have more of an inhibition effect on sulphur removal by the hydrogenation pathway than by the hydrogenolysis pathway. Nitrogen removal by feed pre-treatment was found to be an attractive alternative to achieve the ultra-low sulphur goal. 26 refs., 3 tabs., 9 figs.

A coupled system of half-nitritation and ANAMMOX for mature landfill leachate nitrogen removal.

Science.gov (United States)

Li, Yun; Li, Jun; Zhao, Baihang; Wang, Xiujie; Zhang, Yanzhuo; Wei, Jia; Bian, Wei

2017-09-01

A coupled system of membrane bioreactor-nitritation (MBR-nitritation) and up-flow anaerobic sludge blanket-anaerobic ammonium oxidation (UASB-ANAMMOX) was employed to treat mature landfill leachate containing high ammonia nitrogen and low C/N. MBR-nitritation was successfully realized for undiluted mature landfill leachate with initial concentrations of 900-1500 mg/L [Formula: see text] and 2000-4000 mg/L chemical oxygen demand. The effluent [Formula: see text] concentration and the [Formula: see text] accumulation efficiency were 889 mg/L and 97% at 125 d, respectively. Half-nitritation was quickly realized by adjustment of hydraulic retention time and dissolved oxygen (DO), and a low DO control strategy could allow long-term stable operation. The UASB-ANAMMOX system showed high effective nitrogen removal at a low concentration of mature landfill leachate. The nitrogen removal efficiency was inhibited at excessive influent substrate concentration and the nitrogen removal efficiency of the system decreased as the concentration of mature landfill leachate increased. The MBR-nitritation and UASB-ANAMMOX processes were coupled for mature landfill leachate treatment and together resulted in high effective nitrogen removal. The effluent average total nitrogen concentration and removal efficiency values were 176 mg/L and 83%, respectively. However, the average nitrogen removal load decreased from 2.16 to 0.77 g/(L d) at higher concentrations of mature landfill leachate.

Simultaneous removal of nitrogen oxide/nitrogen dioxide/sulfur dioxide from gas streams by combined plasma scrubbing technology.

Science.gov (United States)

Chang, Moo Been; Lee, How Ming; Wu, Feeling; Lai, Chi Ren

2004-08-01

Oxides of nitrogen (NOx) [nitrogen oxide (NO) + nitrogen dioxide (NO2)] and sulfur dioxide (SO2) are removed individually in traditional air pollution control technologies. This study proposes a combined plasma scrubbing (CPS) system for simultaneous removal of SO2 and NOx. CPS consists of a dielectric barrier discharge (DBD) and wet scrubbing in series. DBD is used to generate nonthermal plasmas for converting NO to NO2. The water-soluble NO2 then can be removed by wet scrubbing accompanied with SO2 removal. In this work, CPS was tested with simulated exhausts in the laboratory and with diesel-generator exhausts in the field. Experimental results indicate that DBD is very efficient in converting NO to NO2. More than 90% removal of NO, NOx, and SO2 can be simultaneously achieved with CPS. Both sodium sulfide (Na2S) and sodium sulfite (Na2SO3) scrubbing solutions are good for NO2 and SO2 absorption. Energy efficiencies for NOx and SO2 removal are 17 and 18 g/kWh, respectively. The technical feasibility of CPS for simultaneous removal of NO, NO2, and SO2 from gas streams is successfully demonstrated in this study. However, production of carbon monoxide as a side-product (approximately 100 ppm) is found and should be considered.

Rapid startup and high rate nitrogen removal from anaerobic sludge digester liquor using a SNAP process.

Science.gov (United States)

Qiao, Sen; Nishiyama, Takashi; Fujii, Tatsuo; Bhatti, Zafar; Furukawa, Kenji

2012-02-01

In this study, a single-stage autotrophic nitrogen removal reactor, packed with a novel acrylic fiber biomass carrier material (Biofix), was applied for nitrogen removal from sludge digester liquor. For rapid start-up, conventional activated sludge was added to the reactor soon after the attachment of anammox biomass on the Biofix carriers, which allowed conventional activated sludge to form a protective layer of biofilm around the anammox biomass. The Nitrogen removal efficiency reached 75% within 1 week at a nitrogen loading rate of 0.46 kg-N/m(3)/day for synthetic wastewater treatment. By the end of the synthetic wastewater treatment period, the maximum nitrogen removal rate had increased to 0.92 kg-N/m(3)/day at a nitrogen loading rate of 1.0 kg-N/m(3)/day. High nitrogen removal rate was also achieved during the actual raw digester liquor treatment with the highest nitrogen removal rate being 0.83 kg-N/m(3)/day at a nitrogen loading rate of 0.93 kg-N/m(3)/day. The thick biofilm on Biofix carriers allowed anammox bacteria to survive under high DO concentration of 5-6 mg/l resulting in stable and high nitrogen removal performance. FISH and CLSM analysis demonstrated that anammox bacteria coexisted and surrounded by ammonium oxidizing bacteria.

Evaluation of the performance of the Tyson Foods wastewater treatment plant for nitrogen removal.

Science.gov (United States)

Ubay-Cokgor, E; Randall, C W; Orhon, D

2005-01-01

In this paper, the performance of the Tyson Foods wastewater treatment plant with an average flow rate of 6500 m3/d was evaluated before and after upgrading of the treatment system for nitrogen removal. This study was also covered with an additional recommendation of BIOWIN BNR program simulation after the modification period to achieve an additional nutrient removal. The results clearly show that the upgrading was very successful for improved nitrogen removal, with a 57% decrease on the total nitrogen discharge. There also were slight reductions in the discharged loads of biological oxygen demand, total suspended solids, ammonium and total phosphorus with denitrification, even though the effluent flow was higher during operation of the nitrogen removal configuration.

Dissolved organic nitrogen recalcitrance and bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater treatment facilities.

Science.gov (United States)

Fan, Lu; Brett, Michael T; Jiang, Wenju; Li, Bo

2017-10-01

The objective of this study was to determine the composition of nitrogen (N) in the effluents of advanced N removal (ANR) wastewater treatment plants (WWTPs). This study also tested two different experimental protocols for determining dissolved N recalcitrance. An analysis of 15 effluent samples from five WWTPs, showed effluent concentrations and especially effluent composition varied greatly from one system to the other, with total nitrogen (TN) ranging between 1.05 and 8.10 mg L -1 . Nitrate (NO 3 - ) accounted for between 38 ± 32% of TN, and ammonium accounted for a further 29 ± 28%. All of these samples were dominated by dissolved inorganic nitrogen (DIN; NO 3 -  + NH 4 + ), and uptake experiments indicated the DIN fraction was as expected highly bioavailable. Dissolved organic N (DON) accounted for 20 ± 11% for the total dissolved N in these effluents, and uptake experiments indicated the bioavailability of this fraction varied between 27 ± 26% depending on the WWTP assessed. These results indicate near complete DIN removal should be the primary goal of ANR treatment systems. The comparison of bioavailable nitrogen (BAN) quantification protocols showed that the dissolved nitrogen uptake bioassay approach was clearly a more reliable way to determine BAN concentrations compared to the conventional cell yield protocol. Moreover, because the nitrogen uptake experiment was much more sensitive, this protocol made it easier to detect extrinsic factors (such as biological contamination or toxicity) that could affect the accuracy of these bioassays. Based on these results, we recommend the nitrogen uptake bioassay using filtered and autoclaved samples to quantify BAN concentrations. However, for effluent samples indicating toxicity, algal bioassays will not accurately quantify BAN. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen removal from digested slurries using a simplified ammonia stripping technique.

Science.gov (United States)

Provolo, Giorgio; Perazzolo, Francesca; Mattachini, Gabriele; Finzi, Alberto; Naldi, Ezio; Riva, Elisabetta

2017-11-01

This study assessed a novel technique for removing nitrogen from digested organic waste based on a slow release of ammonia that was promoted by continuous mixing of the digestate and delivering a continuous air stream across the surface of the liquid. Three 10-day experiments were conducted using two 50-L reactors. In the first two, nitrogen removal efficiencies were evaluated from identical digestates maintained at different temperatures (30°C and 40°C). At the start of the first experiment, the digestates were adjusted to pH 9 using sodium hydroxide, while in the second experiment pH was not adjusted. The highest ammonia removal efficiency (87%) was obtained at 40°C with pH adjustment. However at 40°C without pH adjustment, removal efficiencies of 69% for ammonia and 47% for total nitrogen were obtained. In the third experiment two different digestates were tested at 50°C without pH adjustment. Although the initial chemical characteristics of the digestates were different in this experiment, the ammonia removal efficiencies were very similar (approximately 85%). Despite ammonia removal, the pH increased in all experiments, most likely due to carbon dioxide stripping that was promoted by temperature and mixing. The technique proved to be suitable for removing nitrogen following anaerobic digestion of livestock manure because effective removal was obtained at natural pH (≈8) and 40°C, common operating conditions at typical biogas plants that process manure. Furthermore, the electrical energy requirement to operate the process is limited (estimated to be 3.8kWhm -3 digestate). Further improvements may increase the efficiency and reduce the processing time of this treatment technique. Even without these advances slow-rate air stripping of ammonia is a viable option for reducing the environmental impact associated with animal manure management. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dissolved organic nitrogen recalcitrance and bioavailable nitrogen quantification for effluents from advanced nitrogen removal wastewater treatment facilities

International Nuclear Information System (INIS)

Fan, Lu; Brett, Michael T.; Jiang, Wenju; Li, Bo

2017-01-01

The objective of this study was to determine the composition of nitrogen (N) in the effluents of advanced N removal (ANR) wastewater treatment plants (WWTPs). This study also tested two different experimental protocols for determining dissolved N recalcitrance. An analysis of 15 effluent samples from five WWTPs, showed effluent concentrations and especially effluent composition varied greatly from one system to the other, with total nitrogen (TN) ranging between 1.05 and 8.10 mg L −1 . Nitrate (NO 3 − ) accounted for between 38 ± 32% of TN, and ammonium accounted for a further 29 ± 28%. All of these samples were dominated by dissolved inorganic nitrogen (DIN; NO 3 −  + NH 4 + ), and uptake experiments indicated the DIN fraction was as expected highly bioavailable. Dissolved organic N (DON) accounted for 20 ± 11% for the total dissolved N in these effluents, and uptake experiments indicated the bioavailability of this fraction varied between 27 ± 26% depending on the WWTP assessed. These results indicate near complete DIN removal should be the primary goal of ANR treatment systems. The comparison of bioavailable nitrogen (BAN) quantification protocols showed that the dissolved nitrogen uptake bioassay approach was clearly a more reliable way to determine BAN concentrations compared to the conventional cell yield protocol. Moreover, because the nitrogen uptake experiment was much more sensitive, this protocol made it easier to detect extrinsic factors (such as biological contamination or toxicity) that could affect the accuracy of these bioassays. Based on these results, we recommend the nitrogen uptake bioassay using filtered and autoclaved samples to quantify BAN concentrations. However, for effluent samples indicating toxicity, algal bioassays will not accurately quantify BAN. - Highlights: • DIN was the dominated N pool for most of the tested effluent samples. • DON bioavailability considerably varied depending on the WWTP assessed. �

Municipal wastewater treatment for effective removal of organic matter and nitrogen

International Nuclear Information System (INIS)

Grebenevich, E.V.; Zaletova, N.A.; Terentieva, N.A.

1987-01-01

The organic matter, as well as nitrogen and phosphorus, are nutrient substances. Their excess concentrations in water receiving bodies lead to eutrophication, moreover, the nitrogen content in water bodies is standardized according the sanitary-toxicological criterion of harmfulness: NH 4 + -N ≤0,39-2,0 mgl - , NO 3 -N ≤9,1-10 mgl - . The municipal wastewater contain, usually, organic matter estimated by BOD 150-200 mgl - , and COD 300-400 mgl - , the nitrogen compounds 50-60 mgl - , and NH 4 + -N 20-25 mgl - . NO x -N are practically absent. Their presence indicated on discharge of industrial wastewater. The total phosphorus is present in the concentration of 15 mgl - , PO 4 - - P 5-8 mgl - . Activated sludge process has been most widely used in the USSR for municipal wastewater treatment. The activated sludge is biocenoses of heterotrophic and auto trophic microorganisms. They consume nutrient matters, transferring pollution of wastewater by means of enzyme systems in acceptable forms. C, N and P-containing matters are removed from wastewater by biological intake for cell synthesis. Moreover C- containing matters are removed by oxidation to CO 2 and H 2 O. P-containing compounds under definite conditions associate with solid fraction of activated sludge and thus simultaneously removed from wastewater. The removal of nitrogen in addition to biosynthesis is carried out only in the denitrification process, when oxygen of NO x -N is used for oxidation of organic matter and produced gaseous nitrogen escapes into the atmosphere

Nitrogen Removal from Landfill Leachate by Microalgae

Science.gov (United States)

Pereira, Sérgio F. L.; Gonçalves, Ana L.; Moreira, Francisca C.; Silva, Tânia F. C. V.; Vilar, Vítor J. P.; Pires, José C. M.

2016-01-01

Landfill leachates result from the degradation of solid residues in sanitary landfills, thus presenting a high variability in terms of composition. Normally, these effluents are characterized by high ammoniacal-nitrogen (N–NH4+) concentrations, high chemical oxygen demands and low phosphorus concentrations. The development of effective treatment strategies becomes difficult, posing a serious problem to the environment. Phycoremediation appears to be a suitable alternative for the treatment of landfill leachates. In this study, the potential of Chlorella vulgaris for biomass production and nutrients (mainly nitrogen and phosphorus) removal from different compositions of a landfill leachate was evaluated. Since microalgae also require phosphorus for their growth, different loads of this nutrient were evaluated, giving the following N:P ratios: 12:1, 23:1 and 35:1. The results have shown that C. vulgaris was able to grow in the different leachate compositions assessed. However, microalgal growth was higher in the cultures presenting the lowest N–NH4+ concentration. In terms of nutrients uptake, an effective removal of N–NH4+ and phosphorus was observed in all the experiments, especially in those supplied with phosphorus. Nevertheless, N–NO3− removal was considered almost negligible. These promising results constitute important findings in the development of a bioremediation technology for the treatment of landfill leachates. PMID:27869676

Nitrogen removal in a SBR operated with and without pre-denitrification: effect of the carbon:nitrogen ratio and the cycle time.

Science.gov (United States)

Mees, Juliana Bortoli Rodrigues; Gomes, Simone Damasceno; Hasan, Salah Din Mahmud; Gomes, Benedito Martins; Boas, Márcio Antonio Vilas

2014-01-01

The effects of cycle time (CT) (8, 12 and 16h) and C/N ratio (3, 6 and 9) on nitrogen removal efficiencies in a bench top sequencing batch reactor treating slaughterhouse wastewater were investigated under different operating conditions: in condition 1, the reaction comprises an aerobic/anoxic phase and in condition II, the reaction comprises anoxic I/aerobic/anoxic II phases (with pre-denitrification). The greatest percentages of nitrogen removal were obtained in the CT range from 12 to 16 h and C/N ratios from 3 to 6, with mean efficiency values of 80.76% and 85.57% in condition I and 90.99% and 91.09% in condition II. Although condition II gave a higher removal of total inorganic nitrogen (NH4+ - N + NO2- - N + NO3- - N) than condition I, only condition I showed statistically significant and predictive regression for all the steps of nitrogen removal.

Removal of 14C from nitrogen annulus gas

International Nuclear Information System (INIS)

Cheh, C.H.

1985-01-01

A dry, ambient temperature process using Ca(OH) 2 as the sorbent to remove 14 CO 2 from moderator cover gas was further developed to remove 14 C from the extremely dry nitrogen annulus gas. Thermal gravimetric analysis was carried out to study the thermal stability of Ca(OH) 2 and the CO 2 -Ca(OH) 2 reaction at elevated temperatures under extremely low humidity conditions. Results shows that to achieve high utilization and avoid decomposition of Ca(OH) 2 , humidification of the annulus gas was necessary at high or low temperatures. Results of the bench scale (1-10 L/min) oxidizer study showed that, with 0.5% Pd or alumina as the catalyst, it was possible to achieve complete oxidation of CO and over 80% oxidation of CH 4 with 1% hydrogen in the nitrogen. The gas superficial velocity should be less than or equal to30 cm/s and the residence time greater than or equal to0.5 s. A pilot scale (up to 160 L/min) system including a catalytic oxidizer, a humidifier/demister, a Ca(OH) 2 reactor, a condenser/demister and regenerable molecular sieve dryers, was assembled and tested with simulated nitrogen annulus gas. Results showed that complete oxidation of the CO and 60-100% oxidation of the CH 4 with 0.5% H 2 in the simulated gas were achieved in the pilot plant. The CO 2 concentration was reduced from 30-60 μL/L at the inlet of the Ca(OH) 2 reactor to 1 μL/L or less at the outlet. After modifications of the dryer to overcome the problems encountered, the simulated annulus gas was dried to 0 C dew point before recirculation. Equipment specifications and operating conditions of a 14 C removal system for nitrogen annulus gas are summarized

The effects of operating factors on the removal of total ammonia nitrogen and florfenicol antibiotic from synthetic trout fish farm wastewater through nanofiltration

International Nuclear Information System (INIS)

Cheshmberah, F.; Solaimany Nazar, A.R.; Farhadian, M.

2016-01-01

An aquaculture system can be a potentially significant source of antibacterial compounds and ammonia in an aquatic environment. In this study, the removal of total ammonia nitrogen and florfenicol antibiotic from synthetic aqueous wastewater was assessed by applying a commercial thin film composite polyamide nanofilter. The effects of p H (6.5-8.5), pressure (4-10 bar), concentration of total ammonia nitrogen (1-9 mg/L), and florfenicol (0.2-5 mg/L) on the removal efficiency of the nanofilter were studied at a constant 70% recovery rate. It was found that by increasing the p H within the range of 6.5 to 8.5, it enhanced the removal efficiency by up to 98% and 100% for total ammonia nitrogen and florfenicol, respectively. With an increase in pressure from 4 to 7 bar, the removal percentage increased and then, it decreased from 7 to 10 bar. The interactions factors did not have significant effects on the both pollutants removal efficiencies. To obtain optimal removal efficiencies, an experimental design and statistical analysis via the response surface method were adopted.

The Influence of the Ratio of Nitrate to Ammonium Nitrogen on Nitrogen Removal in the Economical Growth of Vegetation in Hybrid Constructed Wetlands

Directory of Open Access Journals (Sweden)

Haq Nawaz Abbasi

2017-03-01

Full Text Available Growing vegetables economically in the use of constructed wetland for wastewater treatment can play a role in overcoming water and food scarcity. Allium porrum L., Solanum melongena L., Ipomoea aquatica Forsk., and Capsicum annuum L. plants were selected to grow in hybrid constructed wetland (CW under natural conditions. The impact of the ratio of nitrate to ammonium nitrogen on ammonium and nitrate nitrogen removal and on total nitrogen were studied in wastewater. Constructed wetland planted with Ipomoea aquatica Forsk. and Solanum melongena L. showed higher removal efficiency for ammonium nitrogen under higher ammonium concentration, whereas Allium porrum L.-planted CW showed higher nitrate nitrogen removal when NO3–N concentration was high in wastewater. Capsicum annuum L.-planted CW showed little efficiency for both nitrogen sources compared to other vegetables.

Anaerobic ammonium oxidation and its contribution to nitrogen removal in China’s coastal wetlands

Science.gov (United States)

Hou, Lijun; Zheng, Yanling; Liu, Min; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Deng, Fengyu; Chen, Fei; Jiang, Xiaofen

2015-01-01

Over the past several decades, human activities have caused substantial enrichment of reactive nitrogen in China’s coastal wetlands. Although anaerobic ammonium oxidation (anammox), the process of oxidizing ammonium into dinitrogen gas through the reduction of nitrite, is identified as an important process for removing reactive nitrogen, little is known about the dynamics of anammox and its contribution to nitrogen removal in nitrogen-enriched environments. Here, we examine potential rates of anammox and associate them with bacterial diversity and abundance across the coastal wetlands of China using molecular and isotope tracing techniques. High anammox bacterial diversity was detected in China’s coastal wetlands and included Candidatus Scalindua, Kuenenia, Brocadia, and Jettenia. Potential anammox rates were more closely associated with the abundance of anammox bacteria than to their diversity. Among all measured environmental variables, temperature was a key environmental factor, causing a latitudinal distribution of the anammox bacterial community composition, biodiversity and activity along the coastal wetlands of China. Based on nitrogen isotope tracing experiments, anammox was estimated to account for approximately 3.8–10.7% of the total reactive nitrogen removal in the study area. Combined with denitrification, anammox can remove 20.7% of the total external terrigenous inorganic nitrogen annually transported into China’s coastal wetland ecosystems. PMID:26494435

Intensified nitrogen and phosphorus removal in a novel electrolysis-integrated tidal flow constructed wetland system.

Science.gov (United States)

Ju, Xinxin; Wu, Shubiao; Zhang, Yansheng; Dong, Renjie

2014-08-01

A novel electrolysis-integrated tidal flow constructed wetland (CW) system was developed in this study. The dynamics of intensified nitrogen and phosphorus removal and that of hydrogen sulphide control were evaluated. Ammonium removal of up to 80% was achieved with an inflow concentration of 60 mg/L in wetland systems with and without electrolysis integration. Effluent nitrate concentration decreased from 2 mg/L to less than 0.5 mg/L with the decrease in current intensity from 1.5 mA/cm(2) to 0.57 mA/cm(2) in the electrolysis-integrated wetland system, thus indicating that the current intensity of electrolysis plays an important role in nitrogen transformations. Phosphorus removal was significantly enhanced, exceeding 95% in the electrolysis-integrated CW system because of the in-situ formation of a ferric iron coagulant through the electro-dissolution of a sacrificial iron anode. Moreover, the electrolyzed wetland system effectively inhibits sulphide accumulation as a result of a sulphide precipitation coupled with ferrous-iron electro-dissolution and/or an inhibition of bacterial sulphate reduction under increased aerobic conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation on nitrogen oxides and nanoparticle removal and nitrogen monoxide generation using a wet-type nonthermal plasma reactor

Science.gov (United States)

Takehana, Kotaro; Kuroki, Tomoyuki; Okubo, Masaaki

2018-05-01

Nitrogen oxides (NOx) emitted from power plants and combustion sources cause air pollution problems. Selective catalytic reduction technology is remarkably useful for NOx removal. However, there are several drawbacks such as preparation of reducing agents, usage of harmful heavy metals, and higher cost. On the other hand, trace NO is a vasodilator agent and employed in inhalation therapies for treating pulmonary hypertension in humans. Considering these factors, in the present study, a wet-type nonthermal plasma reactor, which can control NOx and nanoparticle emissions and generate NO, is investigated. The fundamental characteristics of the reactor are investigated. First, the experiment of nanoparticle removal is carried out. Collection efficiencies of over 99% are achieved for nanoparticles at 50 and 100 ml min‑1 of liquid flow rates. Second, experiments of NOx removal under air atmosphere and NOx generation under nitrogen atmosphere are carried out. NOx-removal efficiencies of over 95% under the air plasma are achieved in 50–200 ml min‑1 liquid flow rates. Moreover, under nitrogen plasma, NOx is generated, of which the major portion is NO. For example, NO concentration is 25 ppm, while NOx concentration is 31 ppm at 50 ml min‑1 liquid flow rate. Finally, experiments of NO generation under the nitrogen atmosphere with or without flowing water are carried out. When water flows on the inner surface of the reactor, approximately 14 ppm of NO is generated. Therefore, NO generation requires flowing water. It is considered that the reaction of N and OH, which is similar to the extended Zeldovich mechanism, could occur to induce NO formation. From these results, it is verified that the wet-type plasma reactor is useful for NOx removal and NO generation under nitrogen atmosphere with flowing water.

Bioremediation of polluted wasewaterwater influent: phiosphorus and nitrogen removal. Scientific Research and Essays

DEFF Research Database (Denmark)

Muchie, Mammo; Akpor, OB

2010-01-01

Akpor OB and Muchie M. (2010). Bioremediation of polluted wasewaterwater influent: phiosphorus and nitrogen removal. Scientific Research and Essays, Vol. 5(21), pp. 3222–3230......Akpor OB and Muchie M. (2010). Bioremediation of polluted wasewaterwater influent: phiosphorus and nitrogen removal. Scientific Research and Essays, Vol. 5(21), pp. 3222–3230...

Enhancing biological nitrogen fixation

Energy Technology Data Exchange (ETDEWEB)

Danso, S.K.A.; Eskew, D.L. (Joint FAO/IAEA Div. of Isotope and Radiation Applications of Atomic Energy for Food and Agricultural Development, Vienna (Austria))

1984-06-01

Several co-ordinated research programmes (CRPs) conducted by the Soil Fertility, Irrigation and Crop Production Section of the Joint FAO/IAEA Division have concentrated on finding the most efficient way of applying nitrogen fertilizers to various crops, using nitrogen-15 (/sup 15/N) as a tracer. The findings of these studies have been adopted in many countries around the world, resulting in savings of nitrogen fertilizers worth many millions of dollars every year. More recently, the Section's CRPs have focused on enhancing the natural process of biological di-nitrogen fixation. The /sup 15/N isotope technique has proven to be very valuable in studies of the legume-Rhizobium symbiosis, allowing many more experiments than before to be done and yielding much new practical information. The Soils Section is now working to extend the use of the technique to other nitrogen-fixing symbioses.

Autotrophic nitrogen removal process in a potable water treatment biofilter that simultaneously removes Mn and NH4(+)-N.

Science.gov (United States)

Cai, Yan'an; Li, Dong; Liang, Yuhai; Zeng, Huiping; Zhang, Jie

2014-11-01

Ammonia (NH4(+)-N) removal pathways were investigated in a potable water treatment biofilter that simultaneously removes manganese (Mn) and NH4(+)-N. The results indicated a significant loss of nitrogen in the biofilter. Both the completely autotrophic nitrogen removal over nitrite (CANON) process and nitrification were more likely to contribute to NH4(+)-N removal. Moreover, the model calculation results demonstrated that the CANON process contributed significantly to the removal of NH4(+)-N. For influent NH4(+)-N levels of 1.030 and 1.749mg/L, the CANON process contribution was about 48.5% and 46.6%, respectively. The most important finding was that anaerobic ammonia oxidation (ANAMMOX) bacteria were detectable in the biofilter. It is interesting that the CANON process was effective even for such low NH4(+)-N concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Removal of nitrogen from anaerobically digested swine wastewater ...

African Journals Online (AJOL)

This result indicates that the sulfur-packed biofilter would be used as an efficient option for denitrification by autotrophic denitrifiers during swine wastewater treatment. Key words: Biological nitrogen removal, nitrification, denitrification, chemical oxygen demand (COD), intermittent aeration, sulfur-packed bed reactor, swine ...

Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition

International Nuclear Information System (INIS)

Chen Chuan; Ren Nanqi; Wang Aijie; Liu Lihong; Lee, Duu-Jong

2010-01-01

The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed.

New concepts of microbial treatment processes for the nitrogen removal: effect of protein and amino acids degradation.

Science.gov (United States)

González-Martínez, Alejandro; Calderón, Kadiya; González-López, Jesús

2016-05-01

High concentrations of proteins and amino acids can be found in wastewater and wastewater stream produced in anaerobic digesters, having shown that amino acids could persist over different managements for nitrogen removal affecting the nitrogen removal processes. Nitrogen removal is completely necessary because of their implications and the significant adverse environmental impact of ammonium such as eutrophication and toxicity to aquatic life on the receiving bodies. In the last decade, the treatment of effluents with high ammonium concentration through anammox-based bioprocesses has been enhanced because these biotechnologies are cheaper and more environmentally friendly than conventional technologies. However, it has been shown that the presence of important amounts of proteins and amino acids in the effluents seriously affects the microbial autotrophic consortia leading to important losses in terms of ammonium oxidation efficiency. Particularly the presence of sulfur amino acids such as methionine and cysteine has been reported to drastically decrease the autotrophic denitrification processes as well as affect the microbial community structure promoting the decline of ammonium oxidizing bacteria in favor of other phylotypes. In this context we discuss that new biotechnological processes that improve the degradation of protein and amino acids must be considered as a priority to increase the performance of the autotrophic denitrification biotechnologies.

Nitrogen removal in maturation waste stabilisation ponds via biological uptake and sedimentation of dead biomass.

Science.gov (United States)

Camargo Valero, M A; Mara, D D; Newton, R J

2010-01-01

In this work a set of experiments was undertaken in a pilot-scale WSP system to determine the importance of organic nitrogen sedimentation on ammonium and total nitrogen removals in maturation ponds and its seasonal variation under British weather conditions, from September 2004 to May 2007. The nitrogen content in collected sediment samples varied from 4.17% to 6.78% (dry weight) and calculated nitrogen sedimentation rates ranged from 273 to 2868 g N/ha d. High ammonium removals were observed together with high concentrations of chlorophyll-a in the pond effluent. Moreover, chlorophyll-a had a very good correlation with the corresponding increment of VSS (algal biomass) and suspended organic nitrogen (biological nitrogen uptake) in the maturation pond effluents. Therefore, when ammonium removal reached its maximum, total nitrogen removal was very poor as most of the ammonia taken up by algae was washed out in the pond effluent in the form of suspended solids. After sedimentation of the dead algal biomass, it was clear that algal-cell nitrogen was recycled from the sludge layer into the pond water column. Recycled nitrogen can either be taken up by algae or washed out in the pond effluent. Biological (mainly algal) uptake of inorganic nitrogen species and further sedimentation of dead biomass (together with its subsequent mineralization) is one of the major mechanisms controlling in-pond nitrogen recycling in maturation WSP, particularly when environmental and operational conditions are favourable for algal growth.

Simultaneous nitrogen, phosphorous, and hardness removal from reverse osmosis concentrate by microalgae cultivation.

Science.gov (United States)

Wang, Xiao-Xiong; Wu, Yin-Hu; Zhang, Tian-Yuan; Xu, Xue-Qiao; Dao, Guo-Hua; Hu, Hong-Ying

2016-05-01

While reverse osmosis (RO) is a promising technology for wastewater reclamation, RO concentrate (ROC) treatment and disposal are important issues to consider. Conventional chemical and physical treatment methods for ROC present certain limitations, such as relatively low nitrogen and phosphorus removal efficiencies as well as the requirement of an extra process for hardness removal. This study proposes a novel biological approach for simultaneous removal of nitrogen, phosphorus, and calcium (Ca(2+)) and magnesium (Mg(2+)) ions from the ROC of municipal wastewater treatment plants by microalgal cultivation and algal biomass production. Two microalgae strains, Chlorella sp. ZTY4 and Scenedesmus sp. LX1, were used for batch cultivation of 14-16 days. Both strains grew well in ROC with average biomass production of 318.7 mg/L and lipid contents up to 30.6%, and nitrogen and phosphorus could be effectively removed with efficiencies of up to 89.8% and 92.7%, respectively. Approximately 55.9%-83.7% Ca(2+) could be removed from the system using the cultured strains. Mg(2+) removal began when Ca(2+) precipitation ceased, and the removal efficiency of the ion could reach up to 56.0%. The most decisive factor influencing Ca(2+) and Mg(2+) removal was chemical precipitation with increases in pH caused by algal growth. The results of this study provide a new biological approach for removing nitrogen, phosphorous, and hardness from ROC. The results suggest that microalgal cultivation presents new opportunities for applying an algal process to ROC treatment. The proposed approach serves dual purposes of nutrient and hardness reduction and production of lipid rich micro-algal biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

The effect of nitrogen on phosphorus and potassium removal by cauliflower

NARCIS (Netherlands)

Everaarts, A.P.; Moel, de C.P.

2009-01-01

The effect of the amount of nitrogen applied and of the method of application on the amounts of phosphorus and potassium removed from the field with the product in cauliflower cultivation was studied in three field experiments. Band placement or split application of nitrogen did not influence

The effects of operating factors on the removal of total ammonia nitrogen and florfenicol antibiotic from synthetic trout fish farm wastewater through nanofiltration

Directory of Open Access Journals (Sweden)

Ali Reza Solaimany Nazar

2016-04-01

Full Text Available An aquaculture system can be a potentially significant source of antibacterial compounds and ammonia in an aquatic environment. In this study, the removal of total ammonia nitrogen and florfenicol antibiotic from synthetic aqueous wastewater was assessed by applying a commercial TFC (thin film composite polyamide nanofilter. The effects of pH (6.5-8.5, pressure (4-10 bar, concentration of total ammonia nitrogen (1-9 mg/L, and florfenicol (0.2-5 mg/L on the removal efficiency of the nanofilter were studied at a constant 70% recovery rate. It was found that by increasing the pH within the range of 6.5 to 8.5, it enhanced the removal efficiency by up to 98% and 100% for total ammonia nitrogen and florfenicol, respectively. With an increase in pressure from 4 to 7 bar, the removal percentage increased and then, it decreased from 7 to 10 bar. The interactions factors did not have significant effects on the both pollutants removal efficiencies. To obtain optimal removal efficiencies, an experimental design and statistical analysis via the response surface method were adopted.

Biological nitrogen and phosphorus removal by filamentous bacteria ...

African Journals Online (AJOL)

The availability of excess nutrients (phosphorus (P) and nitrogen (N)) in wastewater systems causes many water quality problems. These problems include eutrophication whereby algae grow excessively and lead to depletion of oxygen, death of the aquatic life and bad odours. Biological phosphorus removal has gained ...

Nitrogen Transformation and Removal in Horizontal Surface Flow ...

African Journals Online (AJOL)

The potential use of Constructed Mangrove Wetlands (CMWs) as a cheaper, effective and appropriate method for Nitrogen removal from domestic sewage of coastal zone in peri-urban cities was investigated from August 2007 to. September, 2008. Field investigations were made on horizontal surface flow constructed ...

Integration of pneumatic fracturing with bioremediation from the enhanced removal of BTX from low permeability gasoline-contaminated soils

International Nuclear Information System (INIS)

Venkatraman, S.N.; Kosson, D.S.; Schuring, J.R.; Boland, T.M.

1995-01-01

A pilot-scale evaluation of the integrated pneumatic fracturing and bioremediation system was carried out to demonstrate the enhanced removal of BTX from a gasoline contaminated, low permeability soil formation. The fracturing enhanced subsurface permeability by an average of over 36 times, and established an extended bioremediation zone supporting aerobic, denitrifying and methanogenic populations. Subsurface amendment injections consisting of phosphate and nitrogen were made periodically over a 50-week period to stimulate microbial activity. Results indicate that 79% of the soil-phase BTX was removed during the field test, with over 85% of the mass removed attributable to bioremediation

Effects of porous carrier size on biofilm development, microbial distribution and nitrogen removal in microaerobic bioreactors

KAUST Repository

Ahmad, Muhammad; Liu, Sitong; Mahmood, Nasir; Mahmood, Asif; Ali, Muhammad; Zheng, Maosheng; Ni, Jinren

2017-01-01

In this study, effects of porous carrier’s size (polyurethane-based) on microbial characteristics were systematically investigated in addition to nitrogen removal performance in six microaerobic bioreactors. Among different sized carriers (50, 30, 20, 15,10, 5 mm), 15 mm carrier showed highest nitrogen removal (98%) due to optimal micro-environments created for aerobic nitrifiers in outer layer (0∼7 mm), nitrifiers and denitrifiers in middle layer (7∼10 mm) and anaerobic denitrifiers in inner layer (10∼15 mm). Candidatus brocadia, a dominant anammox bacteria, was solely concentrated close to centroid (0∼70 μm) and strongly co-aggregated with other bacterial communities in the middle layer of the carrier. Contrarily, carriers with a smaller (<15 mm) or larger size (>15 mm) either destroy the effective zone for anaerobic denitrifiers or damage the microaerobic environments due to poor mass transfer. This study is of particular use for optimal design of carriers in enhancing simultaneous nitrification-denitrification in microaerobic wastewater treatment processes.

Effects of porous carrier size on biofilm development, microbial distribution and nitrogen removal in microaerobic bioreactors

KAUST Repository

Ahmad, Muhammad

2017-03-15

In this study, effects of porous carrier’s size (polyurethane-based) on microbial characteristics were systematically investigated in addition to nitrogen removal performance in six microaerobic bioreactors. Among different sized carriers (50, 30, 20, 15,10, 5 mm), 15 mm carrier showed highest nitrogen removal (98%) due to optimal micro-environments created for aerobic nitrifiers in outer layer (0∼7 mm), nitrifiers and denitrifiers in middle layer (7∼10 mm) and anaerobic denitrifiers in inner layer (10∼15 mm). Candidatus brocadia, a dominant anammox bacteria, was solely concentrated close to centroid (0∼70 μm) and strongly co-aggregated with other bacterial communities in the middle layer of the carrier. Contrarily, carriers with a smaller (<15 mm) or larger size (>15 mm) either destroy the effective zone for anaerobic denitrifiers or damage the microaerobic environments due to poor mass transfer. This study is of particular use for optimal design of carriers in enhancing simultaneous nitrification-denitrification in microaerobic wastewater treatment processes.

Method for combined removal of mercury and nitrogen oxides from off-gas streams

Science.gov (United States)

Mendelsohn, Marshall H [Downers Grove, IL; Livengood, C David [Lockport, IL

2006-10-10

A method for removing elemental Hg and nitric oxide simultaneously from a gas stream is provided whereby the gas stream is reacted with gaseous chlorinated compound to convert the elemental mercury to soluble mercury compounds and the nitric oxide to nitrogen dioxide. The method works to remove either mercury or nitrogen oxide in the absence or presence of each other.

Sediment diffusion method improves wastewater nitrogen removal in the receiving lake sediments.

Science.gov (United States)

Aalto, Sanni L; Saarenheimo, Jatta; Ropponen, Janne; Juntunen, Janne; Rissanen, Antti J; Tiirola, Marja

2018-07-01

Sediment microbes have a great potential to transform reactive N to harmless N 2 , thus decreasing wastewater nitrogen load into aquatic ecosystems. Here, we examined if spatial allocation of the wastewater discharge by a specially constructed sediment diffuser pipe system enhanced the microbial nitrate reduction processes. Full-scale experiments were set on two Finnish lake sites, Keuruu and Petäjävesi, and effects on the nitrate removal processes were studied using the stable isotope pairing technique. All nitrate reduction rates followed nitrate concentrations, being highest at the wastewater-influenced sampling points. Complete denitrification with N 2 as an end-product was the main nitrate reduction process, indicating that the high nitrate and organic matter concentrations of wastewater did not promote nitrous oxide (N 2 O) production (truncated denitrification) or ammonification (dissimilatory nitrate reduction to ammonium; DNRA). Using 3D simulation, we demonstrated that the sediment diffusion method enhanced the contact time and amount of wastewater near the sediment surface especially in spring and in autumn, altering organic matter concentration and oxygen levels, and increasing the denitrification capacity of the sediment. We estimated that natural denitrification potentially removed 3-10% of discharged wastewater nitrate in the 33 ha study area of Keuruu, and the sediment diffusion method increased this areal denitrification capacity on average 45%. Overall, our results indicate that sediment diffusion method can supplement wastewater treatment plant (WWTP) nitrate removal without enhancing alternative harmful processes. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Nitrogen removal from urban wastewater by activated sludge ...

African Journals Online (AJOL)

This study deals with nitrogen removal from urban wastewater employing the activated sludge process at low temperature. It aims at determining the performances and rates of nitrification, and characterising the autotrophic biomass (concentration and kinetic parameters) at 11°C and for F/M ratios higher than the ...

Removal of sulfur and nitrogen containing pollutants from discharge gases

Energy Technology Data Exchange (ETDEWEB)

Joubert, James I. (Pittsburgh, PA)

1986-01-01

Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

Removal of sulfur and nitrogen containing pollutants from discharge gases

Energy Technology Data Exchange (ETDEWEB)

Joubert, J.I.

1985-02-08

Oxides of sulfur and of nitrogen are removed from waste gases by reaction with an unsupported copper oxide powder to form copper sulfate. The resulting copper sulfate is dissolved in water to effect separation from insoluble mineral ash and dried to form solid copper sulfate pentahydrate. This solid sulfate is thermally decomposed to finely divided copper oxide powder with high specific surface area. The copper oxide powder is recycled into contact with the waste gases requiring cleanup. A reducing gas can be introduced to convert the oxide of nitrogen pollutants to nitrogen.

Enhanced performance of denitrifying sulfide removal process under micro-aerobic condition.

Science.gov (United States)

Chen, Chuan; Ren, Nanqi; Wang, Aijie; Liu, Lihong; Lee, Duu-Jong

2010-07-15

The denitrifying sulfide removal (DSR) process with bio-granules comprising both heterotrophic and autotrophic denitrifiers can simultaneously convert nitrate, sulfide and acetate into di-nitrogen gas, elementary sulfur and carbon dioxide, respectively, at high loading rates. This study determines the reaction rate of sulfide oxidized into sulfur, as well as the reduction of nitrate to nitrite, would be enhanced under a micro-aerobic condition. The presence of limited oxygen mitigated the inhibition effects of sulfide on denitrifier activities, and enhanced the performance of DSR granules. The advantages and disadvantages of applying the micro-aerobic condition to the DSR process are discussed. 2010 Elsevier B.V. All rights reserved.

Effects of slash removal in an experimental nitrogen gradient. Final report for the project

International Nuclear Information System (INIS)

Nohrstedt, H.Oe.; Ring, Eva; Sikstroem, Ulf; Hoegbom, Lars; Nordlund, Sten

2000-04-01

During four years after clear-felling, the effects of slash removal, including needles, were studied on a productive spruce site (site index G30) in the province of Vaermland, western Sweden. The study was made in an old fertilization experiment, in which at the most 2400 kg N/ha had been added during a twenty-year period. Despite the fact that the site is rich in nitrogen and that much slash was removed (100 ton d. m./ha), there were only very minor effects of the slash removal on the variables under study. These were the composition of soil water, the content of inorganic nitrogen in soil, the biomass of the field layer and the development of the planted spruce seedlings. The only statistically significant effect was that the content of nitrate was reduced in the humus layer. No data supported the idea that the previous fertilization influenced the effect of the slash removal, even though the fertilization had increased the content of total nitrogen in soil and the nitrogen leaching. Thus, we have not been able to repeat the observation from another Swedish study that slash removal reduces leaching of nitrogen and accompanying base cations, e. g. potassium. The effect of slash removal seems to depend on site conditions. Research is needed to reveal the variation in response and decisive factors. Our results, that the survival of spruce seedlings tends to be favoured by slash removal and that the early height growth is unaffected, are in accordance with results from previous studies. Our result, that the biomass of the total field layer is unaffected by slash removal, is not possible to compare with results from other studies, since these were mainly of a qualitative nature

Reactor performance in terms of COD and nitrogen removal and bacterial community structure of a three-stage rotating bioelectrochemical contactor

KAUST Repository

Sayess, Rassil R.

2013-02-01

Integrating microbial fuel cell (MFC) into rotating biological contactor (RBC) creates an opportunity for enhanced removal of COD and nitrogen coupled with energy generation from wastewater. In this study, a three-stage rotating bioelectrochemical contactor (referred to as RBC-MFC unit) integrating MFC with RBC technology was constructed for simultaneous removal of carbonaceous and nitrogenous compounds and electricity generation from a synthetic medium containing acetate and ammonium. The performance of the RBC-MFC unit was compared to a control reactor (referred to as RBC unit) that was operated under the same conditions but without current generation (i.e. open-circuit mode). The effect of hydraulic loading rate (HLR) and COD/N ratio on the performance of the two units was investigated. At low (3.05 gCOD g-1N) and high COD/N ratio (6.64 gCOD g-1N), both units achieved almost similar COD and ammonia-nitrogen removal. However, the RBC-MFC unit achieved significantly higher denitrification and nitrogen removal compared to the RBC unit indicating improved denitrification at the cathode due to current flow. The average voltage under 1000 Ω external resistance ranged between 0.03 and 0.30 V and between 0.02 and 0.21 V for stages 1 and 2 of the RBC-MFC unit. Pyrosequencing analysis of bacterial 16S rRNA gene revealed high bacterial diversity at the anode and cathode of both units. Genera that play a role in nitrification (Nitrospira; Nitrosomonas), denitrification (Comamonas; Thauera) and electricity generation (Geobacter) were identified at the electrodes. Geobacter was only detected on the anode of the RBC-MFC unit. Nitrifiers and denitrifiers were more abundant in the RBC-MFC unit compared to the RBC unit and were largely present on the cathode of both units suggesting that most of the nitrogen removal occurred at the cathode. © 2012 Elsevier Ltd.

Enhancing nitrogen removal in stormwater treatment facilities for transportation.

Science.gov (United States)

2015-01-01

Stormwater from roadways is a point source of pollution. State DOTs must comply with Total Maximum : Daily Load (TMDL) regulations for nutrients such as nitrogen, which causes water quality impairment. Existing stormwater treatment technologies, such...

Enhancement of removal of SO2 and NOx by powdery materials in radiation treatment of exhaust gases

International Nuclear Information System (INIS)

Tokunaga, Okihiro; Namba, Hideki; Suzuki, Nobutake

1985-01-01

We studied the effect of powdery silica on radiation removal of SO 2 and NOx from mixtures of SO 2 , NOx, water vapour, oxygen and nitrogen under irradiation by electron beams of 1.5 MeV at 120 0 C. The SO 2 and NOx concentrations decreased when powdery silica was fed without irradiation. Decrements of SO 2 and NOx concentrations were markedly enhanced when powdery silica was fed together with the irradiation. The enhancement of SO 2 - and NOx-removal is attributed to the adsorption of SO 2 and NO on the water-covered surface of powdery silica, and the effective removal of NO 2 due to the reaction with water adsorbed on the surface of powdery silica. The results obtained show that the addition of powdery silica under irradiation is an effective method of enhancing the removal of SO 2 and NOx. (author)

Physico-chemical technologies for nitrogen removal from wastewaters: a review

Directory of Open Access Journals (Sweden)

Andrea G. Capodaglio

2015-07-01

Full Text Available The paper examines the main physico-chemical processes for nitrogen removal from wastewaters, considering both those that have been long known and still widely applied at the industrial scale, and those that are still at the research level. Special attention is paid to the latest technological developments, as well as to operational problems and fields of application. The processes considered are briefly summarized as follows: ammonia air and steam stripping; ammonia vacuum distillation; ammonia precipitation as struvite; ammonia and nitrate removal by selected ion exchange; breakpoint chlorination; chloramine removal by selected activated carbon; ammonia adsorption on charcoal; chemical reduction of nitrate; advanced oxidation processes to convert ammonia and organic-N into nitrogen gas or nitrate. Special attention is given to advanced oxidation processes, as great research efforts are currently addressed to their implementation. These specifically include ozonation, peroxon oxidation, catalytic wet air oxidation, photo-catalytic oxidation and electrochemical oxidation.

A study on nitrogen removal efficiency of Pseudomonas stutzeri ...

African Journals Online (AJOL)

USER

2010-02-08

Feb 8, 2010 ... ambient temperature in the reaction system, the efficiency of nitrogen removal was studied. The results ... no reported experiment which has been conducted to ... controlled shaker at 32°C with a 150 r/min rotating speed (Ahn,.

Effect of dissolved oxygen on nitrogen removal and process control in aerobic granular sludge reactor

International Nuclear Information System (INIS)

Yuan Xiangjuan; Gao Dawen

2010-01-01

A sequencing batch reactor (SBR) with aerobic granular sludge was operated to determine the effect of different DO concentrations on biological nitrogen removal process and to investigate the spatial profiles of DO, ORP and pH as online control parameters in such systems. The results showed that DO concentration had a significant effect on nitrification efficiencies and the profiles of DO, ORP and pH. The specific nitrification rate was decreased from 0.0595 mgNH 4 + -N/(gMLSS min) to 0.0251 mgNH 4 + -N/(gMLSS min) after DO concentration was dropped off from 4.5 mg/L to 1.0 mg/L. High DO concentration improved the nitrification and increased the volumetric NH 4 + -N removal. Low DO concentration enhanced TIN removal, while prolonged the nitrification duration. Also there existed a good correlation between online control parameters (ORP, pH) and nutrient (COD, NH 4 + -N, NO 2 - -N, NO 3 - -N) variations in aerobic granular sludge reactor when DO was 2.5 mg/L, 3.5 mg/L and 4.5 mg/L. However it was difficult to identify the end of nitrification and denitrification when DO was 1.0 mg/L, due to no apparent bending points on ORP and pH curves. In conclusion, the optimal DO concentration was suggested at 2.5 mg/L as it not only achieved high nitrogen removal efficiency and decreased the reaction duration, but also saved operation cost by aeration and mixing.

A novel control strategy for single-stage autotrophic nitrogen removal in SBR

DEFF Research Database (Denmark)

Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine; Gernaey, Krist

2015-01-01

A novel feedforward–feedback control strategy was developed for complete autotrophic nitrogen removal in a sequencing batch reactor. The aim of the control system was to carry out the regulation of the process while keeping the system close to the optimal operation. The controller was designed...... based on a process model and then tested experimentally. The resulting batch-to-batch control strategy had the total nitrogen removal efficiency as controlled variable and the setting of the aeration mass flow controller as manipulated variable. Compared to manual operation mode (constant air supply......), the controller resulted in a significant performance improvement: removal efficiency was kept at a stable high level in the presence of influent ammonium concentration disturbances, and the absolute deviation on removal efficiency was reduced by 40%. The successful validation of the controller in a lab...

Removal and recovery of nitrogen and sulfur oxides from gaseous mixtures containing them

International Nuclear Information System (INIS)

Cooper, H.B.H.

1984-01-01

A cyclic process for removing lower valence nitrogen oxides from gaseous mixtures includes treating the mixtures with an aqueous media including alkali metal carbonate and alkali metal bicarbonate and a preoxygen oxidant to form higher valence nitrogen oxides and to capture these oxides as alkali metal salts, expecially nitrites and nitrates, in a carbonate/bicarbonate-containing product aqueous media. Highly selective recovery of nitrates in high purity and yield may then follow, as by crystallization, with the carbonate and bicarbonate alkali metal salts strongly increasing the selectivity and yield of nitrates. The product nitrites are converted to nitrates by oxidation after lowering the product aqueous media pH to below about 9. A cyclic process for removing sulfur oxides from gas mixtures includes treating these mixtures includes treating these mixtures with aqueous media including alkali metal carbonate and alkali metal bicarbonate where the ratio of alkali metal to sulfur dioxide is not less than 2. The sulfur values may be recovered from the resulting carbonate/bicarbonate/-sulfite containing product aqueous media as alkali metal sulfate or sulfite salts which are removed by crystallization from the carbonate-containing product aqueous media. As with the nitrates, the carbonate/bicarbonate system strongly increases yield of sulfate or sulfite during crystallization. Where the gas mixtures include both sulfur dioxide and lower valence nitrogen oxides, the processes for removing lower valence nitrogen oxides and sulfur dioxide may be combined into a single removal/recovery system, or may be effected in sequence

[Phylogenetic analysis and nitrogen removal characteristics of a heterotrophic nitrifying-aerobic denitrifying bacteria strain from marine environment].

Science.gov (United States)

Sun, Xuemei; Li, Qiufen; Zhang, Yan; Liu, Huaide; Zhao, Jun; Qu, Keming

2012-06-04

We determined the phylogenetic position of a heterotrophic nitrifying-aerobic denitrifying bacterium X3, and detected its nitrogen removal characteristics for providing evidence to explain the principle of heterotrophic nitrification-aerobic denitrification and to improve the process in purification of marine-culture wastewater. The evolutionary position of the strain was determined based on its morphological, physiological, biochemical characteristics and 16SrRNA gene sequence. The nitrification-denitrification ability of this strain was detected by detecting its nitrogen removal efficiency and growth on different inorganic nitrogen source. Strain X3 was identified as Halomonas sp. It grew optimally at salinity 3%, pH 8.5, C:N 10:1 at 28 degrees C, and it could still survive at 15% salinity. The removal of NH4+ -N, NO2(-) -N and NO3(-) -N was 98.29%, 99.07%, 96.48% respectively within 24 h. When three inorganic nitrogen existed simultaneously, it always utilized ammonia firstly, and the total inorganic nitrogen removal was higher than with only one nitrogen, suggesting that strain X3 has the ability of simultaneous nitrification and denitrification and completing the whole nitrogen removing process. Strain X3 belonged to the genus of Halomonas. It had strong simultaneous nitrification and denitrification capability and could live in high-salinity environment.

Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis.

Science.gov (United States)

Bao, K Q; Gao, J Q; Wang, Z B; Zhang, R Q; Zhang, Z Y; Sugiura, N

2012-01-01

Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions.

Method of removing oxides of sulfur and oxides of nitrogen from exhaust gases

Science.gov (United States)

Walker, Richard J.

1986-01-01

A continuous method is presented for removing both oxides of sulfur and oxides of nitrogen from combustion or exhaust gases with the regeneration of the absorbent. Exhaust gas is cleaned of particulates and HCl by a water scrub prior to contact with a liquid absorbent that includes an aqueous solution of bisulfite and sulfite ions along with a metal chelate, such as, an iron or zinc aminopolycarboxylic acid. Following contact with the combustion gases the spent absorbent is subjected to electrodialysis to transfer bisulfite ions into a sulfuric acid solution while splitting water with hydroxide and hydrogen ion migration to equalize electrical charge. The electrodialysis stack includes alternate layers of anion selective and bipolar membranes. Oxides of nitrogen are removed from the liquid absorbent by air stripping at an elevated temperature and the regenerated liquid absorbent is returned to contact with exhaust gases for removal of sulfur oxides and nitrogen oxides.

Optimization for zeolite regeneration and nitrogen removal performance of a hypochlorite-chloride regenerant.

Science.gov (United States)

Zhang, Wei; Zhou, Zhen; An, Ying; Du, Silu; Ruan, Danian; Zhao, Chengyue; Ren, Ning; Tian, Xiaoce

2017-07-01

Simultaneous zeolites regeneration and nitrogen removal were investigated by using a mixed solution of NaClO and NaCl (NaClO-NaCl solution), and effects of the regenerant on ammonium removal performance and textural properties of zeolites were analyzed by long-term adsorption and regeneration operations. Mixed NaClO-NaCl solution removed more NH 4 + exchanged on zeolites and converted more of them to nitrogen than using NaClO or NaCl solution alone. Response surface methodological analysis indicated that molar ratio of hypochlorite and nitrogen (ClO - /N), NaCl concentration and pH value all had significant effects on zeolites regeneration and NH 4 + conversion to nitrogen, and the optimum condition was obtained at ClO - /N of 1.75, NaCl concentration of 20 g/L and pH of 10.0. Zeolites regenerated by mixed NaClO-NaCl solution showed higher ammonium adsorption rate and lower capacity than unused zeolites. Zeolites and the regeneration solution were both effective even after 20 cycles of use. Composition and morphological analysis revealed that the main mineral species and surface morphology of zeolites before and after NaClO-NaCl regeneration were unchanged. Textural analysis indicated that NaClO-NaCl regeneration leads to an increased surface area of zeolites, especially the microporosity. The results indicated that NaClO-NaCl regeneration is an attractive method to achieve sustainable removal of nitrogen from wastewater through zeolite. Copyright © 2017 Elsevier Ltd. All rights reserved.

Re-use of winery wastewaters for biological nutrient removal.

Science.gov (United States)

Rodríguez, L; Villaseñor, J; Buendía, I M; Fernández, F J

2007-01-01

The aim of this study was to evaluate the feasibility of the re-use of the winery wastewater to enhance the biological nutrient removal (BNR) process. In batch experiments it was observed that the addition of winery wastewater mainly enhanced the nitrogen removal process because of the high denitrification potential (DNP), of about 130 mg N/g COD, of the contained substrates. This value is very similar to that obtained by using pure organic substrates such as acetate. The addition of winery wastewater did not significantly affect either phosphorus or COD removal processes. Based on the experimental results obtained, the optimum dosage to remove each mg of N-NO3 was determined, being a value of 6.7 mg COD/mg N-NO3. Because of the good properties of the winery wastewater to enhance the nitrogen removal, the viability of its continuous addition in an activated sludge pilot-scale plant for BNR was studied. Dosing the winery wastewater to the pilot plant a significant increase in the nitrogen removal was detected, from 58 to 75%. The COD removal was slightly increased, from 89 to 95%, and the phosphorus removal remained constant.

Startup and oxygen concentration effects in a continuous granular mixed flow autotrophic nitrogen removal reactor.

Science.gov (United States)

Varas, Rodrigo; Guzmán-Fierro, Víctor; Giustinianovich, Elisa; Behar, Jack; Fernández, Katherina; Roeckel, Marlene

2015-08-01

The startup and performance of the completely autotrophic nitrogen removal over nitrite (CANON) process was tested in a continuously fed granular bubble column reactor (BCR) with two different aeration strategies: controlling the oxygen volumetric flow and oxygen concentration. During the startup with the control of oxygen volumetric flow, the air volume was adjusted to 60mL/h and the CANON reactor had volumetric N loadings ranging from 7.35 to 100.90mgN/Ld with 36-71% total nitrogen removal and high instability. In the second stage, the reactor was operated at oxygen concentrations of 0.6, 0.4 and 0.2mg/L. The best condition was 0.2 mgO2/L with a total nitrogen removal of 75.36% with a CANON reactor activity of 0.1149gN/gVVSd and high stability. The feasibility and effectiveness of CANON processes with oxygen control was demonstrated, showing an alternative design tool for efficiently removing nitrogen species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitrogen removal in a single-chamber microbial fuel cell with nitrifying biofilm enriched at the air cathode

KAUST Repository

Yan, Hengjing

2012-05-01

Nitrogen removal is needed in microbial fuel cells (MFCs) for the treatment of most waste streams. Current designs couple biological denitrification with side-stream or combined nitrification sustained by upstream or direct aeration, which negates some of the energy-saving benefits of MFC technology. To achieve simultaneous nitrification and denitrification, without extra energy input for aeration, the air cathode of a single-chamber MFC was pre-enriched with a nitrifying biofilm. Diethylamine-functionalized polymer (DEA) was used as the Pt catalyst binder on the cathode to improve the differential nitrifying biofilm establishment. With pre-enriched nitrifying biofilm, MFCs with the DEA binder had an ammonia removal efficiency of up to 96.8% and a maximum power density of 900 ± 25 mW/m 2, compared to 90.7% and 945 ± 42 mW/m 2 with a Nafion binder. A control with Nafion that lacked nitrifier pre-enrichment removed less ammonia and had lower power production (54.5% initially, 750 mW/m 2). The nitrifying biofilm MFCs had lower Coulombic efficiencies (up to 27%) than the control reactor (up to 36%). The maximum total nitrogen removal efficiency reached 93.9% for MFCs with the DEA binder. The DEA binder accelerated nitrifier biofilm enrichment on the cathode, and enhanced system stability. These results demonstrated that with proper cathode pre-enrichment it is possible to simultaneously remove organics and ammonia in a single-chamber MFC without supplemental aeration. © 2012 Elsevier Ltd.

Nitrogen removal on recycling water process of wastewater treatment plant effluent using subsurface horizontal wetland with continuous feed

Science.gov (United States)

Tazkiaturrizki, T.; Soewondo, P.; Handajani, M.

2018-01-01

Recycling water is a generic term for water reclamation and reuse to solve the scarcity of water. Constructed wetlands have been recognized as providing many benefits for wastewater treatment including water supply and control by recycling water. This research aims to find the best condition to significantly remove nitrogen using constructed wetland for recycling water of Bojongsoang Waste Water Treatment Plan (WWTP) effluent. Using media of soil, sand, gravel, and vegetation (Typha latifolia and Scirpus grossus) with an aeration system, BOD and COD parameters have been remarkably reduced. On the contrary, the removal efficiency for nitrogen is only between 50-60%. Modifications were then conducted by three step of treatment, i.e., Step I is to remove BOD/COD using Typha latifolia with an aeration system, Step II is todecrease nitrogen using Scirpus grossus with/without aeration, and Step III isto complete the nitrogen removal with denitrification process by Glycine max without aeration. Results of the research show that the nitrogen removal has been successfully increased to a high efficiency between 80-99%. The combination of aeration system and vegetation greatly affects the nitrogen removal. The vegetation acts as the organic nitrogen consumer (plant uptake) for amino acids, nitrate, and ammonium as nutrition, as well as theoxygen supplier to the roots so that aerobic microsites are formed for ammonification microorganisms.

Towards an optimal experimental design for N2O model calibration during biological nitrogen removal

DEFF Research Database (Denmark)

Domingo Felez, Carlos; Valverde Pérez, Borja; Plósz, Benedek G.

Process models describing nitrous oxide (N2O) production during biological nitrogen removal allow for the development of mitigation strategies of this potent greenhouse gas. N2O is an intermediate of nitrogen removal, hence its prediction is negatively affected by the uncertainty associated to it...... of strategies to minimize the carbon footprint of wastewater treatment plants....

Nitrogen removal from wastewater through microbial electrolysis cells and cation exchange membrane.

Science.gov (United States)

Haddadi, Sakineh; Nabi-Bidhendi, Gholamreza; Mehrdadi, Nasser

2014-02-17

Vulnerability of water resources to nutrients led to progressively stricter standards for wastewater effluents. Modification of the conventional procedures to meet the new standards is inevitable. New technologies should give a priority to nitrogen removal. In this paper, ammonium chloride and urine as nitrogen sources were used to investigate the capacity of a microbial electrolysis cell (MEC) configured by cation exchange membrane (CEM) for electrochemical removal of nitrogen over open-and closed-circuit potentials (OCP and CCP) during biodegradation of organic matter. Results obtained from this study indicated that CEM was permeable to both organic and ammonium nitrogen over OCP. Power substantially mediated ammonium migration from anodic wastewater to the cathode, as well. With a urine rich wastewater in the anode, the maximum rate of ammonium intake into the cathode varied from 34.2 to 40.6 mg/L.h over CCP compared to 10.5-14.9 mg/L.h over OCP. Ammonium separation over CCP was directly related to current. For 1.46-2.12 mmol electron produced, 20.5-29.7 mg-N ammonium was removed. Current also increased cathodic pH up to 12, a desirable pH for changing ammonium ion to ammonia gas. Results emphasized the potential for MEC in control of ammonium through ammonium separation and ammonia volatilization provided that membrane characteristic is considered in their development.

Nitrogen removal and its relationship with the nitrogen-cycle genes and microorganisms in the horizontal subsurface flow constructed wetlands with different design parameters.

Science.gov (United States)

Chen, Jun; Ying, Guang-Guo; Liu, You-Sheng; Wei, Xiao-Dong; Liu, Shuang-Shuang; He, Liang-Ying; Yang, Yong-Qiang; Chen, Fan-Rong

2017-07-03

This study aims to investigate nitrogen removal and its relationship with the nitrogen-cycle genes and microorganisms in the horizontal subsurface flow constructed wetlands (CWs) with different design parameters. Twelve mesocosm-scale CWs with four substrates and three hydraulic loading rates were set up in the outdoor. The result showed the CWs with zeolite as substrate and HLR of 20 cm/d were selected as the best choice for the TN and NH 3 -N removal. It was found that the single-stage mesocosm-scale CWs were incapable to achieve high removals of TN and NH 3 -N due to inefficient nitrification process in the systems. This was demonstrated by the lower abundance of the nitrification genes (AOA and AOB) than the denitrification genes (nirK and nirS), and the less diverse nitrification microorganisms than the denitrification microorganisms in the CWs. The results also show that microorganism community structure including nitrogen-cycle microorganisms in the constructed wetland systems was affected by the design parameters especially the substrate type. These findings show that nitrification is a limiting factor for the nitrogen removal by CWs.

Total nitrogen and total phosphorus removal from brackish aquaculture wastewater using effective microorganism

Science.gov (United States)

Mohamad, K. A.; Mohd, S. Y.; Sarah, R. S.; Mohd, H. Z.; Rasyidah, A.

2017-09-01

Aquaculture is one of dominant food based industry in the world with 8.3% annual growth rate and its development had led to adverse effect on the environment. High nutrient production in form of nitrogenous compound and phosphorus contributed to environmental deterioration such as eutrophication and toxicity to the industry. Usage of Effective Microorganism (EM), one of the biological approaches to remove Total Nitrogen (TN) and Total Phosphorus (TP) in aquaculture pond was proposed. Samples were obtained from the Sea Bass intensive brackish aquaculture wastewater (AW) from fish farm at Juru, Penang and the parameters used to measure the removal of nitrogenous compounds include, pH, EM dosage, shaking, contact time and optimum variable conditions. From the study, for effective contact time, day 6 is the optimum contact time for both TN and TP with 99.74% and 62.78% removal respectively while in terms of optimum pH, the highest TN removal was at pH 7 with 66.89 %. The optimum dosage of EM is 1.5 ml with ratio 1:166 for 81.5 % TN removal was also found appropriate during the experiment. At varied optimum conditions of EM, the removal efficiency of TN and TP were 81.53% and 38.94% respectively while the removal mechanism of TN was highly dependent on the decomposition rate of specific bacteria such as Nitrobacter bacteria, Yeast and Bacillus Subtilis sp. The study has established the efficacy of EM's ability to treat excessive nutrient of TN and TP from AW.

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

of 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......, 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 biofilm, allowing nitrogen removal in a single reactor by simultaneous activity of the mentioned biocatalysts. This work consists on the analysis of the microbial community existing in two laboratory-scale reactors operated for more than 300 days, which removed up to 5.5 g-N/m2/day. The system contained...

Long-term population dynamics and in situ physiology in activated sludge systems with enhanced biological phosphorus removal operated with and without nitrogen removal

DEFF Research Database (Denmark)

Lee, N.; Nielsen, P.H.; Aspegren, H.

2003-01-01

. However, we observed a lower correlation (0.9). The Actinobacteria were the only additional group of bacteria which showed a similar degree of correlation to the P content in activated sludge as the Rhodocyclus-related bacteria - but only for the system without nitrogen removal. Significant amounts (less...... of the Betaproteobacteria (part of them identified as Rhodocyclus-related bacteria) as well as the Actinobacteria were able to take up P-33(i), [H-3]-acetate and [H-3]-glucose under anaerobic-aerobic conditions. The contribution of anoxic P-33(i) uptake under alternating anaerobic-anoxic conditions was significantly lower...

[Rapid startup and nitrogen removal characteristic of anaerobic ammonium oxidation reactor in packed bed biofilm reactor with suspended carrier].

Science.gov (United States)

Chen, Sheng; Sun, De-zhi; Yu, Guang-lu

2010-03-01

Packed bed biofilm reactor with suspended carrier was used to cultivate ANAMMOX bacteria with sludge inoculums from WWTP secondary settler. The startup of ANAMMOX reactor was comparatively studied using high nitrogen loading method and low nitrogen loading method with aerobically biofilmed on the carrier, and the nitrogen removal characteristic was further investigated. The results showed that the reactor could be started up successfully within 90 days using low nitrogen loading method, the removal efficiencies of ammonium and nitrite were nearly 100% and the TN removal efficiencywas over 75% , however, the high nitrogen loading method was proved unsuccessfully for startup of ANAMMOX reactor probably because of the inhibition effect of high concentration of ammonium and nitrite. The pH value of effluent was slightly higher than the influent and the pH value can be used as an indicator for the process of ANAMMOX reaction. The packed bed ANAMMOX reactor with suspended carrier showed good characteristics of high nitrogen loading and high removal efficiency, 100% of removal efficiency could be achieved when the influent ammonium and nitrite concentration was lower than 800 mg/L.

Integrated nitrogen removal biofilter system with ceramic membrane for advanced post-treatment of municipal wastewater.

Science.gov (United States)

Son, Dong-Jin; Yun, Chan-Young; Kim, Woo-Yeol; Zhang, Xing-Ya; Kim, Dae-Gun; Chang, Duk; Sunwoo, Young; Hong, Ki-Ho

2016-12-01

The pre-denitrification biofilm process for nitrogen removal was combined with ceramic membrane with pore sizes of 0.05-0.1 µm as a system for advanced post-treatment of municipal wastewater. The system was operated under an empty bed hydraulic retention time of 7.8 h, recirculation ratio of 3, and transmembrane pressure of 0.47 bar. The system showed average removals of organics, total nitrogen, and solids as high as 93%, 80%, and 100%, respectively. Rapid nitrification could be achieved and denitrification was performed in the anoxic filter without external carbon supplements. The residual particulate organics and nitrogen in effluent from biofilm process could be also removed successfully through membrane filtration and the removal of total coliform was noticeably improved after membrane filtration. Thus, a system composed of the pre-denitrification biofilm process with ceramic membrane would be a compact and flexible option for advanced post-treatment of municipal wastewater.

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

Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration...... (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......-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....

Modelling nitrogen transformation and removal in mara river basin wetlands upstream of lake Victoria

Science.gov (United States)

Mayo, Aloyce W.; Muraza, Marwa; Norbert, Joel

2018-06-01

Lake Victoria, the largest lake in Africa, is a resource of social-economic potential in East Africa. This lake receives water from numerous tributaries including Mara River, which contributes about 4.8% of the total Lake water inflow. Unfortunately, Mara River basin faces environmental problems because of intensive settlement, agriculture, overgrazing in the basin and mining activities, which has lead to water pollution in the river, soil erosion and degradation, decreased soil fertility, loss of vegetation cover, decreased water infiltration capacity and increased sedimentation. One of the pollutants carried by the river includes nitrogen, which has contributed to ecological degradation of the Lake Victoria. Therefore this research work was intended to determine the effectiveness of Mara River wetland for removal of nitrogen and to establish nitrogen removal mechanisms in the wetland. To predict nitrogen removal in the wetland, the dynamics of nitrogen transformation was studied using a conceptual numerical model that takes into account of various processes in the system using STELLA II version 9.0®2006 software. Samples of model input from water, plants and sediments were taken for 45 days and were analyzed for pH, temperature, and DO in situ and chemical parameters such as NH3-N, Org-N, NO2-N, and NO3-N were analyzed in the laboratory in accordance with Standard methods. For plants, the density, dominance, biomass productivity and TN were determined and for sediments TN was analyzed. Inflow into the wetland was determined using stage-discharge relationship and was found to be 734,400 m3/day and the average wetland volume was 1,113,500 m3. Data collected by this study were used for model calibration of nitrogen transformation in this wetland while data from another wetland were used for model validation. It was found that about 37.8% of total nitrogen was removed by the wetland system largely through sedimentation (26.6%), plant uptake (6.6%) and

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

Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration...

Method of removing nitrogen monoxide from a nitrogen monoxide-containing gas using a water-soluble iron ion-dithiocarbamate, xanthate or thioxanthate

Science.gov (United States)

Liu, D. Kwok-Keung; Chang, Shih-Ger

1987-08-25

The present invention relates to a method of removing of nitrogen monoxide from a nitrogen monoxide-containing gas which method comprises contacting a nitrogen oxide-containing gas with an aqueous solution of water soluble organic compound-iron ion chelate complex. The NO absorption efficiency of ferrous urea-dithiocarbamate and ferrous diethanolamine-xanthate as a function of time, oxygen content and solution ph is presented. 3 figs., 1 tab.

Nitrogen Removal from Digested Black Water by One-stage Partial Nitritation and Anammox

DEFF Research Database (Denmark)

Vlaeminck, S.E.; Terada, Akihiko; Smets, Barth F.

2009-01-01

This study assessed the technical feasibility to treat digested black water from vacuum toilets (> 1000 mg NH4+-N L-1) in a lab-scale oxygen-limited autotrophic nitrification/denitrification (OLAND) rotating biological contactor. After an adaptation period of 2.5 months, a stable. nitrogen removal...... conversion was very low, in contrast to the high specific AnAOB activity. DGGE analysis showed that the dominant AerAOB and AnAOB species were resistant to the transition from synthetic medium to digested black water. This study demonstrates high-rate nitrogen removal from digested black water by one...

Combined Pre-Precipitation, Biological Sludge Hydrolysis and Nitrogen Reduction - A Pilot Demonstration of Integrated Nutrient Removal

DEFF Research Database (Denmark)

Kristensen, G. H.; Jørgensen, P. E.; Strube, R.

1992-01-01

solubilization was 10-13% of the suspended COD. The liquid phase of the hydrolyzed sludge, the hydrolysate, was separated from the suspended fraction by centrifugation and added to the biological nitrogen removal stage to support denitrification. The hydrolysate COD consisted mainly of volatile fatty acids......A pilot study was performed to investigate advanced wastewater treatment by pre-precipitation in combination with biological nitrogen removal supported by biological sludge hydrolysis. The influent wastewater was pretreated by addition of a pre-polymerized aluminum salt, followed by flocculation......, resulting in high denitrification rates. Nitrogen reduction was performed based on the Bio-Denitro principle in an activated sludge system. Nitrogen was reduced from 45 mg/l to 9 mg/l and phosphorus was reduced from 11 mg/l to 0.5 mg/l. The sludge yield was low, approx. 0.3-0.4 gCOD/gCOD removed...

The Effect of HLRs on Nitrogen Removal by Using a Pilot-scale Aerated Steel Slag System

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Hamdan R.

2017-01-01

Full Text Available Discharge from domestic wastewater treatment plant amongst the main sources of nitrogen pollution in the environment. However, to remove nitrogen conventionally in domestic wastewater require high cost and complex chemical treatment method. Vertical flow aerated rock filter emerged as one of attractive alternative wastewater treatment method due to simplicity and compactness of the system. However, the application is yet to be developed in warm climate countries in particular Malaysia. Therefore, this study was conducted to investigate the effect of hydraulic loading rate (HLR to the performance of a pilot-scale Vertical Flow Aerated Rock Filter (VFARF in removing nitrogen from domestic wastewater using pilot-scale VFARF systems with steel slag as the filter media. Furthermore, this study has been designed to focus on the effects of two HLRs; 2.72 and 1.04 m3/m3.day. Influent and effluent of the filter systems were monitored biweekly basis for 11 weeks and analyzed for selected parameters. Results from this study shows that the VFARF with HLR 1.04 m3/m3.day has performed better in terms of removal ammonium-nitrogen and TKN as the system able to remove 90.4 ± 6.9%, 86.2 ± 10.7%, whilst the VFARF with 2.72 m3/m3.day remove 87.4 ± 9.9%, 80 ± 11.7%, respectively. From the observation, it can be concluded that nitrogen removal does affect by HLR as the removal in lower HLR system was higher due to high DO level in the VFARF system with 1.04 m3/m3.day which range from 4.5 to 5.1 mg/L whilst the DO level was slightly lower in the VFARF system with 2.72 m3/m3.day in the range of 3.7 to 4.5 mg/L.

Effects of Invasive-Plant Management on Nitrogen-Removal Services in Freshwater Tidal Marshes.

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Mary Alldred

Full Text Available Establishing relationships between biodiversity and ecosystem function is an ongoing endeavor in contemporary ecosystem and community ecology, with important practical implications for conservation and the maintenance of ecosystem services. Removal of invasive plant species to conserve native diversity is a common management objective in many ecosystems, including wetlands. However, substantial changes in plant community composition have the potential to alter sediment characteristics and ecosystem services, including permanent removal of nitrogen from these systems via microbial denitrification. A balanced assessment of costs associated with keeping and removing invasive plants is needed to manage simultaneously for biodiversity and pollution targets. We monitored small-scale removals of Phragmites australis over four years to determine their effects on potential denitrification rates relative to three untreated Phragmites sites and adjacent sites dominated by native Typha angustifolia. Sediment ammonium increased following the removal of vegetation from treated sites, likely as a result of decreases in both plant uptake and nitrification. Denitrification potentials were lower in removal sites relative to untreated Phragmites sites, a pattern that persisted at least two years following removal as native plant species began to re-colonize treated sites. These results suggest the potential for a trade-off between invasive-plant management and nitrogen-removal services. A balanced assessment of costs associated with keeping versus removing invasive plants is needed to adequately manage simultaneously for biodiversity and pollution targets.

Effects of Invasive-Plant Management on Nitrogen-Removal Services in Freshwater Tidal Marshes.

Science.gov (United States)

Alldred, Mary; Baines, Stephen B; Findlay, Stuart

2016-01-01

Establishing relationships between biodiversity and ecosystem function is an ongoing endeavor in contemporary ecosystem and community ecology, with important practical implications for conservation and the maintenance of ecosystem services. Removal of invasive plant species to conserve native diversity is a common management objective in many ecosystems, including wetlands. However, substantial changes in plant community composition have the potential to alter sediment characteristics and ecosystem services, including permanent removal of nitrogen from these systems via microbial denitrification. A balanced assessment of costs associated with keeping and removing invasive plants is needed to manage simultaneously for biodiversity and pollution targets. We monitored small-scale removals of Phragmites australis over four years to determine their effects on potential denitrification rates relative to three untreated Phragmites sites and adjacent sites dominated by native Typha angustifolia. Sediment ammonium increased following the removal of vegetation from treated sites, likely as a result of decreases in both plant uptake and nitrification. Denitrification potentials were lower in removal sites relative to untreated Phragmites sites, a pattern that persisted at least two years following removal as native plant species began to re-colonize treated sites. These results suggest the potential for a trade-off between invasive-plant management and nitrogen-removal services. A balanced assessment of costs associated with keeping versus removing invasive plants is needed to adequately manage simultaneously for biodiversity and pollution targets.

[Effect of Different Purple Parent Rock on Removal Rates of Nitrogen, Phosphorus and Organics in Landscape Water].

Science.gov (United States)

Huang, Xue-jiao; Liu, Xiao-chen; Li, Zhen-lun; Shi, Wen-hao; Yang, Shan

2015-05-01

In order to understand the impacts of physicochemical properties of purple parent rock on the removal rates of nitrogen, phosphorus and organics in landscape water systems, four types of purple parent rocks including Peng-lai-zhen Formation (S1) , Sha-xi-miao Formation (S2) , Fei-xian-guan Formation (S3) and Sui-ning Formation (S4) , which distribute widely in Chongqing, were selected and autoclaved, and added to unsterile landscape water collected from Chong-de Lake in Southwest University, and the landscape water only was used as control. And several indicators such as total nitrogen and phosphorus and so on of every disposal were investigated periodically. The results indicated that: (1) The highest removal rates of total nitrogen, total phosphorus and Ammonia nitrogen were observed in Sl, which were 45.1%, 62.3% and 90%, respectively; the highest removal rate of COD was 94.5% in S4; the ammonia nitrogen content in the purple parent rocks was not obviously changed before and after the experiments, which indicated that the adsorption of ammonia nitrogen on purple parent rock surface was not the main reason for the decrease of ammonia nitrogen in water. (2) Arsenate had inhibitory effect on the sulfate-reducing bacteria, while copper and magnesium had promoting effect on gram-negative bacteria. (3) The microbial diversity was positively correlated to total nitrogen in water. (4) Based on the PCA analyses of microbial community structure and environmental factors, the mineral elements released from parent rock affected the structure and composition of microbial community in the test water, and then influenced the removal rates of nitrogen, phosphorus and organics in water systems.

Removing Spilled Oil With Liquid Nitrogen

Science.gov (United States)

Snow, Daniel B.

1991-01-01

Technique proposed to reduce more quickly, contain, clean up, and remove petroleum products and such other pollutants as raw sewage and chemicals without damage to humans, animals, plants, or the environment. Unique and primary aspect of new technique is use of cryogenic fluid to solidify spill so it can be carried away in solid chunks. Liquid nitrogen (LN2), with boiling point at -320 degrees F (-196 degrees C), offers probably best tradeoff among extreme cold, cost, availability, and lack of impact on environment among various cryogenic fluids available. Other applications include extinguishing fires at such locations as oil derricks or platforms and at tank farms containing such petroleum products as gasoline, diesel fuel, and kerosene.

Removal of hard COD, nitrogenous compounds and phenols from a ...

African Journals Online (AJOL)

The objective of this study was to identify the factors affecting the suspended and fixed biomass in the removal of hard COD, nitrogenous compounds and phenols from a coal gasification wastewater (CGWW) stream using a hybrid fixed-film bioreactor (H-FFBR) process under real-time plant operational conditions and ...

Performance of an autotrophic nitrogen removing reactor: Diagnosis through fuzzy logic

DEFF Research Database (Denmark)

Vangsgaard, Anna Katrine; Mauricio Iglesias, Miguel; Mutlu, Ayten Gizem

Autotrophic nitrogen removal through nitritation-anammox in one stage SBRs is an energy and cost efficient alternative to conventional treatment methods. Intensification of an already complex biological system challenges our ability to observe, understand, diagnose, and control the system. A fuzzy...

Optimization of an Sbr process for nitrogen removal from concentrated wastewater via nitrite

International Nuclear Information System (INIS)

Longhi, L.; Basilico, D.; Meloni, A.; Canziani, R.

2009-01-01

The results of an experimentation carried out on a pilot-scale Sbr for nitrogen removal via nitridation-denitration are reported. The experimentation was carried out in the period July October 2007 and was aimed at achieving design data for the upgrade of a full scale wastewater treatment plant (WWTP), following the new regulations issued by Lombardy Regional Authority for the discharge of effluents into sensitive areas. One aspect that has been considered in the upgrade is nitrogen removal from the supernatant coming from anaerobic sludge digestion. The experimental results provided sound design data based on real biological activity measurements and operational process parameters such as oxygen and organic carbon requirements. [it

On the 'hysteresis' effect in the biological nitrogen removal :theory and full scale experimental evaluation

International Nuclear Information System (INIS)

Tatano, F.

1996-01-01

The wastewater treatments plants localized in the Ruhr River (Germany), generally present a typical wastewater temperature variation curve during the winter period. These temperature changes produce specific effects on the nitrogen removal efficiencies in the activated sludge systems. The so called 'hysteresis' phenomenon is responsible for these effects. The paper deals with some simplified theoretical considerations and with a full scale experimental evaluations of the effects caused by the hysteresis phenomenon in the biological nitrogen removal

Bioelectrode-based approach for enhancing nitrate and nitrite removal and electricity generation from eutrophic lakes

DEFF Research Database (Denmark)

Zhang, Yifeng; Angelidaki, Irini

Nitrate and nitrite contamination of surface waters (e.g. lakes) has become a severe environmental and health problem, especially in developing countries. The recent demonstration of nitrate reduction at the cathode of microbial fuel cell (MFC) provides an opportunity to develop a new technology...... from nitrate- and nitrite-rich synthetic lake waters at initial concentration of 10 mg-N/L. Along with the electricity production a total nitrogen removal of 62% and 77% was accomplished, for nitrate and nitrite, respectively. The nitrogen removal was almost 4 times higher under close-circuit condition...... with biocathode, compared to either the open-circuit operation or with abiotic cathode. The mass balance on nitrogen indicates that most of the removed nitrate and nitrite (84.7±0.1% and 81.8±0.1%, respectively) was reduced to nitrogen gas. The nitrogen removal and power generation was limited by the dissolved...

Nitrogen Removal Efficiency at Centralized Domestic Wastewater Treatment Plants in Bangkok, Thailand

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Pongsak Noophan

2009-07-01

Full Text Available In this study, influents and effluents from centralized domestic wastewater treatment systems in Bangkok (Rattanakosin, Dindaeng, Chongnonsi, Nongkhaem, and Jatujak were randomly collected in order to measure organic nitrogen plus ammonium-nitrogen (total Kjeldahl nitrogen, total organic carbon, total suspended solids, and total volatile suspended solids by using Standard Methods for the Examination of Water and Wastewater 1998. Characteristics of influent and effluent (primary data of the centralized domestic wastewater treatment system from the Drainage and Sewerage Department of Bangkok Metropolitan Administration were used to analyze efficiency of systems. Fluorescent in situ hybridization (FISH was used to identify specific nitrifying bacteria (ammonium oxidizing bacteria specific for Nitrosomonas spp. and nitrite oxidizing bacteria specific for Nitrobacter spp. and Nitrospira spp.. Although Nitrosomonas spp. and Nitrobacter spp. were found, Nitrospira spp. was most prevalent in the aeration tank of centralized wastewater treatment systems. Almost all of the centralized domestic wastewater treatment plants in Bangkok are designed for activated sludge type biological nutrient removal (BNR. However, low efficiency nitrogen removal was found at centralized wastewater treatment plants in Bangkok. Influent ratio of TOC:N at centralized treatment plant is less than 2.5. Centralized wastewater treatment systems have not always been used suitability and used successfully in some areas of Bangkok Thailand.

Digestate application in landfill bioreactors to remove nitrogen of old landfill leachate.

Science.gov (United States)

Peng, Wei; Pivato, Alberto; Lavagnolo, Maria Cristina; Raga, Roberto

2018-04-01

Anaerobic digestion of organics is one of the most used solution to gain renewable energy from waste and the final product, the digestate, still rich in putrescible components and nutrients, is mainly considered for reutilization (in land use) as a bio-fertilizer or a compost after its treatment. Alternative approaches are recommended in situations where conventional digestate management practices are not suitable. Aim of this study was to develop an alternative option to use digestate to enhance nitrified leachate treatment through a digestate layer in a landfill bioreactor. Two identical landfill columns (Ra and Rb) filled with the same solid digestate were set and nitrified leachate was used as influent. Ra ceased after 75 day's operation to get solid samples and calculate the C/N mass balance while Rb was operated for 132 days. Every two or three days, effluent from the columns were discarded and the columns were refilled with nitrified leachate (average N-NO 3 - concentration = 1,438 mg-N/L). N-NO 3 - removal efficiency of 94.7% and N-NO 3 - removal capacity of 19.2 mg N-NO 3 - /gTS-digestate were achieved after 75 days operation in Ra. Prolonging the operation to 132 days in Rb, N-NO 3 - removal efficiency and N-NO 3 - removal capacity were 72.5% and 33.1 mg N-NO 3 - /gTS-digestate, respectively. The experimental analysis of the process suggested that 85.4% of nitrate removal could be attributed to denitrification while the contribution percentage of adsorption was 14.6%. These results suggest that those solid digestates not for agricultural or land use, could be used in landfill bioreactors to remove the nitrogen from old landfill leachate. Copyright © 2018 Elsevier Ltd. All rights reserved.

The physiological and biochemical mechanism of nitrate-nitrogen removal by water hyacinth from agriculture eutrophic wastewater

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WU Wenwei

Full Text Available ABSTRACT Large amount of agriculturl wastewater containing high level nitrate-nitrogen (NO3 --N is produced from modern intensive agricultural production management due to the excessive use of chemical fertilizers and livestock scale farming. The hydroponic experiment of water hyacinth was conducted for analyzing the content of NO3 --N, soluble sugar content, N-transported the amino acid content and growth change in water hyacinth to explore its purification ability to remove NO3 --N from agriculture eutrophic wastewater and physiological and biochemical mechanism of this plant to remove NO3 --N. The results showed that the water hyacinth could effectively utilize the NO3 --N from agriculture eutrophic wastewater. Compared with the control, the contents of NO3 -change to NO3 --N in the root, leaf petiole and leaf blade of water hyacinth after treatment in the wastewater for a week was significantly higher than that in the control plants treated with tap water, and also the biomass of water hyacinth increased significantly, indicating that the accumulation of biomass due to the rapid growth of water hyacinth could transfer some amount of NO3 --N.13C-NMR analysis confirmed that water hyacinth would convert the part nitrogen absorbed from agriculture eutrophic wastewater to ammonia nitrogen, which increased the content of aspartic acid and glutamic acid, decreased the content of soluble sugar, sucrose and fructose and the content of N-storaged asparagine and glutamine, lead to enhance the synthesis of plant amino acids and promote the growth of plants. These results indicate that the nitrate in agriculture eutrophic wastewater can be utilized by water hyacinth as nitrogen nutrition, and can promote plant growth by using soluble sugar and amide to synthesis amino acids and protein.

Transgenic plants that exhibit enhanced nitrogen assimilation

Science.gov (United States)

Coruzzi, Gloria M.; Brears, Timothy

1999-01-01

The present invention relates to a method for producing plants with improved agronomic and nutritional traits. Such traits include enhanced nitrogen assimilatory and utilization capacities, faster and more vigorous growth, greater vegetative and reproductive yields, and enriched or altered nitrogen content in vegetative and reproductive parts. More particularly, the invention relates to the engineering of plants modified to have altered expression of key enzymes in the nitrogen assimilation and utilization pathways. In one embodiment of the present invention, the desired altered expression is accomplished by engineering the plant for ectopic overexpression of one of more the native or modified nitrogen assimilatory enzymes. The invention also has a number of other embodiments, all of which are disclosed herein.

Effect of operational cycle time length on nitrogen removal in an alternating oxidation ditch system.

Science.gov (United States)

Mantziaras, I D; Stamou, A; Katsiri, A

2011-06-01

This paper refers to nitrogen removal optimization of an alternating oxidation ditch system through the use of a mathematical model and pilot testing. The pilot system where measurements have been made has a total volume of 120 m(3) and consists of two ditches operating in four phases during one cycle and performs carbon oxidation, nitrification, denitrification and settling. The mathematical model consists of one-dimensional mass balance (convection-dispersion) equations based on the IAWPRC ASM 1 model. After the calibration and verification of the model, simulation system performance was made. Optimization is achieved by testing operational cycles and phases with different time lengths. The limits of EU directive 91/271 for nitrogen removal have been used for comparison. The findings show that operational cycles with smaller time lengths can achieve higher nitrogen removals and that an "equilibrium" between phase time percentages in the whole cycle, for a given inflow, must be achieved.

Novel heterotrophic nitrogen removal and assimilation characteristic of the newly isolated bacterium Pseudomonas stutzeri AD-1.

Science.gov (United States)

Qing, Hui; Donde, Oscar Omondi; Tian, Cuicui; Wang, Chunbo; Wu, Xingqiang; Feng, Shanshan; Liu, Yao; Xiao, Bangding

2018-04-18

AD-1, an aerobic denitrifier, was isolated from activated sludge and identified as Pseudomonas stutzeri. AD-1 completely removed NO 3 - or NO 2 - and removed 99.5% of NH 4 + during individual culturing in a broth medium with an initial nitrogen concentration of approximately 50 mg L -1 . Results showed that larger amounts of nitrogen were removed through assimilation by the bacteria. And when NH 4 + was used as the sole nitrogen source in the culture medium, neither NO 2 - nor NO 3 - was detected, thus indicating that AD-1 may not be a heterotrophic nitrifier. Only trace amount of N 2 O was detected during the denitrification process. Single factor experiments indicated that the optimal culture conditions for AD-1 were: a carbon-nitrogen ratio (C/N) of 15, a temperature of 25°C and sodium succinate or glucose as a carbon source. In conclusion, due to the ability of AD-1 to utilize nitrogen of different forms with high efficiencies for its growth while producing only trace emissions of N 2 O, the bacterium had outstanding potential to use in the bioremediation of high-nitrogen-containing wastewaters. Meanwhile, it may also be a proper candidate for biotreatment of high concentration organic wastewater. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Kinetic Interpretation of Nitrogen Removal in Pilot Scale Experiments

DEFF Research Database (Denmark)

Harremoës, Poul; Sinkjær, Ole

1995-01-01

with biological and chemical phosphorus removal. Nitrification and denitrification rates have been measured in batch tests on activated sludge extracted from the pilot plants and by measuring transient concentrations during the alternating mode of operation in the aerobic and anoxic tanks. The data were......Pilot plant experiments have been performed over a period of four years in order to establish an experimental basis for the upgrading of the treatment plants of The City of Copenhagen to nutrient removal. The choice of design is the alternating mode of operating biological nitrogen removal...... normalized to standard conditions by correcting them according to the kinetic theory. The average normalized nitrification rate was measured to be between 54 and 60 mg NH~-N/(g VSSn~t' h) by different test methods at 7°C. The denitrification rate was measured to vary between 0.85 and 0.95mg NO~--N/(g VSS. h...

[Isolation, Identification and Nitrogen Removal Characteristics of a Heterotrophic Nitrification-Aerobic Denitrification Strain y3 Isolated from Marine Environment].

Science.gov (United States)

Sun, Qing-hua; Yu, De-shuang; Zhang, Pei-yu; Lin, Xue-zheng; Xu, Guang-yao; Li, Jin

2016-03-15

A heterotrophic nitrification--aerobic denitrification bacterium named y3 was isolated from the sludge of Jiaozhou Bay using the enrichment medium with seawater as the matrix. It was identified as Pseudomonas sp. based on the morphological observation, physiological experiments and sequence analysis of 16S rRNA. The experiment results showed that the optimal carbon resource was sodium citrate, the optimal pH was 7.0, and the optimal C/N was 13. The strain could use NH₄Cl, NaNO₂ and KNO₃ as sole nitrogen source, and the removal efficiencies were 98.69%, 78.38% and 72.95% within 20 hours, respectively. There was no nitrate and nitrite accumulation during the heterotrophic nitrification process. Within 20 hours, the nitrogen removal efficiencies were 99.56%, 99.75% and 99.41%, respectively, in the mixed system with NO₃⁻-N: NO²⁻-N of 2:1, 1:1 and 1:2. When the NH₄⁺-N: NO₃⁻-N ratios were 2: 1 , 1: 1 , 1: 2, the nitrogen removal efficiencies were all 100% . When the NH₄⁺-N:NO₂⁻-N ratios were 2:1,1:1,1:2, the nitrogen removal efficiencies were 90.43%, 92.79% and 99.96%, respectively. They were higher than those with single nitrogen source. As a result, strain y3 had good nitrogen removal performance in high saline wastewater treatment.

Enhanced cytocompatibility of silver-containing biointerface by constructing nitrogen functionalities

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei, E-mail: weizhang@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Jun [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Huaiyu [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Xu, Ying; Wang, Pingli [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Ji, Junhui, E-mail: jhji@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chu, Paul K. [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2015-09-15

Graphical abstract: Constructing nitrogen functionalities is promising method to enhance cytocompatibility of the biointerface by simultaneous Ag and N{sub 2} plasma modification. - Highlights: • N{sub 2} plasma immersion ion implantation (PIII) treatment generates plenty of nitrogen functionalities on polymer substrate. • N{sub 2} PIII treatment increases surface roughness and hydrophilicity and improves its capability to adsorb protein. • Simultaneous Ag and N{sub 2} plasma modification constructs nitrogen functionalities to enhance cytocompatibility of the biointerface. - Abstract: Silver (Ag) has recently been introduced into polymeric biomedical implants by plasma immersion ion implantation (PIII) to enhance the antibacterial capability. However, Ag ions and nanoparticles can increase the cytotoxicity and inhibit cellular proliferation and the relationship is time- and dose-dependent. In this study, Ag and N{sub 2} PIII is conducted in concert to produce nitrogen functional groups as well as Ag-containing biointerface. In addition to the creation of nitrogen functionalities, the surface roughness and hydrophilicity are improved in favor of protein adsorption. Compared to the biointerface created by Ag PIII only, the nitrogen functionalities generated by N{sub 2} co-PIII do not affect DNA synthesis and the total protein level but evidently enhance cellular adhesion, viability, and proliferation at the biointerface. The modified surface is observed to upregulate the osteogenesis-related marker expression of bone cells in contact. Our findings suggest that dual Ag and N{sub 2} PIII is a desirable technique to enhance both the cytocompatibility and antibacterial capability of medical polymers.

Nitrogen Removal from Milking Center Wastewater via Simultaneous Nitrification and Denitrification Using a Biofilm Filtration Reactor

Directory of Open Access Journals (Sweden)

Seung-Gun Won

2015-06-01

Full Text Available Milking center wastewater (MCW has a relatively low ratio of carbon to nitrogen (C/N ratio, which should be separately managed from livestock manure due to the negative impacts of manure nutrients and harmful effects on down-stream in the livestock manure process with respect to the microbial growth. Simultaneous nitrification and denitrification (SND is linked to inhibition of the second nitrification and reduces around 40% of the carbonaceous energy available for denitrification. Thus, this study was conducted to find the optimal operational conditions for the treatment of MCW using an attached-growth biofilm reactor; i.e., nitrogen loading rate (NLR of 0.14, 0.28, 0.43, and 0.58 kg m−3 d−1 and aeration rate of 0.06, 0.12, and 0.24 m3 h−1 were evaluated and the comparison of air-diffuser position between one-third and bottom of the reactor was conducted. Four sand packed-bed reactors with the effective volume of 2.5 L were prepared and initially an air-diffuser was placed at one third from the bottom of the reactor. After the adaptation period of 2 weeks, SND was observed at all four reactors and the optimal NLR of 0.45 kg m−3 d−1 was found as a threshold value to obtain higher nitrogen removal efficiency. Dissolved oxygen (DO as one of key operational conditions was measured during the experiment and the reactor with an aeration rate of 0.12 m3 h−1 showed the best performance of NH4-N removal and the higher total nitrogen removal efficiency through SND with appropriate DO level of ~0.5 mg DO L−1. The air-diffuser position at one third from the bottom of the reactor resulted in better nitrogen removal than at the bottom position. Consequently, nitrogen in MCW with a low C/N ratio of 2.15 was successfully removed without the addition of external carbon sources.

Combined carbon and nitrogen removal from acetonitrile using algal-bacterial bioreactors

Energy Technology Data Exchange (ETDEWEB)

Munoz, R.; Jacinto, M.; Guieysse, B.; Mattiasson, B. [Dept. of Biotechnology, Center for Chemistry and Chemical Engineering, Lund Univ., Lund (Sweden)

2005-06-01

When compared with Chlorella vulgaris, Scenedesmus obliquus and Selenastrum capricornutum, C. sorokiniana presented the highest tolerance to acetonitrile and the highest O{sub 2} production capacity. It also supported the fastest acetonitrile biodegradation when mixed with a suitable acetonitrile-degrading bacterial consortium. Consequently, this microalga was tested in symbiosis with the bacterial culture for the continuous biodegradation of acetonitrile at 2 g l{sup -1} in a stirred tank photobioreactor and in a column photobioreactor under continuous illumination (250 {mu}E m{sup -2} s{sup -1}). Acetonitrile removal rates of up to 2.3 g l{sup -1} day{sup -1} and 1.9 g l{sup -1} day{sup -1} were achieved in the column photobioreactor and the stirred-tank photobioreactor, respectively, when operated at the shortest retention times tested (0.4 days, 0.6 days, respectively). In addition, when the stirred-tank photobioreactor was operated with a retention time of 3.5 days, the microbial culture was capable of assimilating up to 71% and nitrifying up to 12% of the NH{sub 4}{sup +} theoretically released through the biodegradation of acetonitrile, thus reducing the need for subsequent nitrogen removal. This study suggests that complete removal of N-organics can be combined with a significant removal of nitrogen by using algal-bacterial systems and that further residual biomass digestion could pay-back part of the operation costs of the treatment plant. (orig.)

Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

DEFF Research Database (Denmark)

Stief, P.

2013-01-01

(mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release...... enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide...... of ammonium from sediments is enhanced more strongly than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna...

Optimization of free ammonia concentration for nitrite accumulation in shortcut biological nitrogen removal process.

Science.gov (United States)

Chung, Jinwook; Shim, Hojae; Park, Seong-Jun; Kim, Seung-Jin; Bae, Wookeun

2006-03-01

A shortcut biological nitrogen removal (SBNR) utilizes the concept of a direct conversion of ammonium to nitrite and then to nitrogen gas. A successful SBNR requires accumulation of nitrite in the system and inhibition of the activity of nitrite oxidizers. A high concentration of free ammonia (FA) inhibits nitrite oxidizers, but unfortunately decreases the ammonium removal rate as well. Therefore, the optimal range of FA concentration is necessary not only to stabilize nitrite accumulation but also to achieve maximum ammonium removal. In order to derive such optimal FA concentrations, the specific substrate utilization rates of ammonium and nitrite oxidizers were measured. The optimal FA concentration range appeared to be 5-10 mg/L for the adapted sludge. The simulated results from the modified inhibition model expressed by FA and ammonium/nitrite concentrations were shown very similar to the experimental results.

Nitrogen and chemical oxygen demand removal from septic tank wastewater in subsurface flow constructed wetlands: substrate (cation exchange capacity) effects.

Science.gov (United States)

Collison, Robert S; Grismer, Mark E

2014-04-01

The current article focuses on chemical oxygen demand (COD) and nitrogen (ammonium and nitrate) removal performance from synthetic human wastewater as affected by different substrate rocks having a range of porosities and cation exchange capacities (CECs). The aggregates included lava rock, lightweight expanded shale, meta-basalt (control), and zeolite. The first three had CECs of 1 to 4 mequiv/100 gm, whereas the zeolite CEC was much greater (-80 mequiv/100 gm). Synthetic wastewater was gravity fed to each constructed wetland system, resulting in a 4-day retention time. Effluent samples were collected, and COD and nitrogen species concentrations measured regularly during four time periods from November 2008 through June 2009. Chemical oxygen demand and nitrogen removal fractions were not significantly different between the field and laboratory constructed wetland systems when corrected for temperature. Similarly, overall COD and nitrogen removal fractions were practically the same for the aggregate substrates. The important difference between aggregate effects was the zeolite's ammonia removal process, which was primarily by adsorption. The resulting single-stage nitrogen removal process may be an alternative to nitrification and denitrification that may realize significant cost savings in practice.

Adsorption Equilibrium and Kinetics of the Removal of Ammoniacal Nitrogen by Zeolite X/Activated Carbon Composite Synthesized from Elutrilithe

Directory of Open Access Journals (Sweden)

Yong Zhang

2017-01-01

Full Text Available Zeolite X/activated carbon composite material (X/AC was prepared from elutrilithe, by a process consisting of carbonization, activation, and subsequent hydrothermal transformation of aluminosilicate in alkaline solution, which was used for the removal of ammoniacal nitrogen from aqueous solutions. Adsorption kinetics, equilibrium, and thermodynamic were studied and fitted by various models. The adsorption kinetics is best depicted by pseudosecond-order model, and the adsorption isotherm fits the Freundlich and Redlich-Peterson model. This explains the ammoniacal nitrogen adsorption onto X/AC which was chemical adsorption in nature. Thermodynamic properties such as ΔG, ΔH, and ΔS were determined for the ammoniacal nitrogen adsorption, and the positive enthalpy confirmed that the adsorption process was endothermic. It can be inferred that ammoniacal nitrogen removal by X/AC composite is attributed to the ion exchange ability of zeolite X. Further, as a novel sorbent, this material has the potential application in removing ammoniacal nitrogen coexisting with other organic compounds from industrial wastewater.

Process for the removal of sulfur oxides and nitrogen oxides from flue gas

International Nuclear Information System (INIS)

Elshout, R.V.

1992-01-01

This patent describes a continuous process for removing sulfur oxide and nitrogen oxide contaminants from the flue gas generated by industrial power plants and boiler systems burning sulfur containing fossil fuels and for converting these contaminants, respectively, into recovered elemental liquid sulfur and nitrogen ammonia and mixtures thereof. It comprises removing at least a portion of the flue gas generated by a power plant or boiler system upstream of the stack thereof; passing the cooled and scrubbed flue gas through an adsorption system; combining a first portion of the reducing gas stream leaving the adsorbers of the adsorption system during regeneration thereof and containing sulfur oxide and nitrogen oxide contaminants with a hydrogen sulfide rich gas stream at a temperature of about 400 degrees F to about 600 degrees F and passing the combined gas streams through a Claus reactor-condenser system over a catalyst in the reactor section thereof which is suitable for promoting the equilibrium reaction between the hydrogen sulfide and the sulfur dioxide of the combined streams to form elemental sulfur

Organics and nitrogen removal from textile auxiliaries wastewater with A2O-MBR in a pilot-scale

International Nuclear Information System (INIS)

Sun, Faqian; Sun, Bin; Hu, Jian; He, Yangyang; Wu, Weixiang

2015-01-01

Highlights: • A pilot-scale A 2 O-MBR system treating textile auxiliaries wastewater was assessed. • Organic matter and recycle ratio strongly affected the performance of the system. • GC/MS analysis found some refractory organics in the MBR permeate. • Combination of organic foulants and inorganic compounds caused membrane fouling. - Abstract: The removal of organic compounds and nitrogen in an anaerobic–anoxic–aerobic membrane bioreactor process (A 2 O-MBR) for treatment of textile auxiliaries (TA) wastewater was investigated. The results show that the average effluent concentrations of chemical oxygen demand (COD), ammonium nitrogen (NH 4 + –N) and total nitrogen (TN) were about 119, 3 and 48 mg/L under an internal recycle ratio of 1.5. The average removal efficiency of COD, NH 4 + –N and TN were 87%, 96% and 55%, respectively. Gas chromatograph–mass spectrometer analysis indicated that, although as much as 121 different types of organic compounds were present in the TA wastewater, only 20 kinds of refractory organic compounds were found in the MBR effluent, which could be used as indicators of effluents from this kind of industrial wastewater. Scanning electron microscopy analysis revealed that bacterial foulants were significant contributors to membrane fouling. An examination of foulants components by wavelength dispersive X-ray fluorescence showed that the combination of organic foulants and inorganic compounds enhanced the formation of gel layer and thus caused membrane fouling. The results will provide valuable information for optimizing the design and operation of wastewater treatment system in the textile industry

The water vapor nitrogen process for removing sodium from LMFBR components

Energy Technology Data Exchange (ETDEWEB)

Crippen, M D; Funk, C W; Lutton, J M [Hanford Engineering Development Laboratory, Richland (United States)

1978-08-01

Application and operation of the Water Vapor-Nitrogen Process for removing sodium from LMFBR components is reviewed. Emphasis is placed on recent efforts to verify the technological bases of the process, to refine the values of process parameters and to ensure the utility of the process for cleaning and requalifying components. (author)

Influence of road salt on the biological removal of nitrogen

OpenAIRE

Eliška Horniaková; Milan Búgel

2007-01-01

Processes occuring in the aeration tank remove nitrogen from the organic substances in wastewater by using the bacterii. Nitrification utilize the metabolism of aerobic bacterii Nitrosomonas, Nitrococus, Nitrospira, Nitrobacter Nitrocystis a Nitrosobolus. Pseudosomonas, Chromobacterium, Denitrobacillus a Micrococus are denitrification anaerobic bacterii. The bacterii are lithotrophic and they are sensitive to pH of wastewater. Chlorine and heavy metals are toxic for these bacterii. For a corr...

Nitrogen removal kinetics in the treatment of landfill leachate by SBR systems

International Nuclear Information System (INIS)

Andreottola, G.; Foladori, P.; Ragazzi, M.

1998-01-01

In this study, laboratory-scale experiments were conducted applying the SBR activated sludge process to leachate from an old MSW landfill operating for 7 years. Due to the fact that old leachate is characterized with a high concentration of ammonia (approximately 1500 mgN/1) and low availability of readily biodegradable organic matter (BOD 5 /COD,06), the aim was to examine the nitrogen removal process and to compare the efficiency of one-stage and two stage systems operating at temperature of 20 C and 12 C. The second alternative SBR configuration is based on the coupling of two SBR reactors: the first one specialized in nitrification and the second one in post-denitrification, with external carbon source addition. By the efficient removal of nitrogen, an on-site pretreatment of leachate allows to comply with the limits required for discharging into sewers or into municipal wastewater treatment plant [it

Forest fuel reduces the nitrogen load - calculations of nitrogen flows

International Nuclear Information System (INIS)

Burstroem, F.; Johansson, Jan.

1995-12-01

Nitrogen deposition in Sweden has increased strongly during recent decades, particularly in southern Sweden. Nitrogen appears to be largely accumulated in biomass and in the soil. It is therefore desirable to check the accumulation of nitrogen in the forest. The most suitable way of doing this is to remove more nitrogen-rich biomass from the forest, i.e., increase the removal of felling residues from final fellings and cleanings. An ecological condition for intensive removal of fuel is that the ashes are returned. The critical load for nitrogen, CL(N), indicates the level of nitrogen deposition that the forest can withstand without leading to ecological changes. Today, nitrogen deposition is higher than the CL(N) in almost all of Sweden. CL(N) is calculated in such a manner that nitrogen deposition should largely be balanced by nitrogen losses through harvesting during a forest rotation. The value of CL(N) thus largely depends on how much nitrogen is removed with the harvested biomass. When both stems and felling residues are harvested, the CL(N) is about three times higher than in conventional forestry. The increase is directly related to the amount of nitrogen in the removed biofuel. Use of biofuel also causes a certain amount of nitrogen emissions. From the environmental viewpoint there is no difference between the sources of the nitrogen compounds. An analysis of the entire fuel chain shows that, compared with the amount of nitrogen removed from the forest with the fuel, about 5 % will be emitted as nitrogen oxides or ammonia during combustion, and a further ca 5 % during handling and transports. A net amount of about 90 % of biomass nitrogen is removed from the system and becomes inert nitrogen (N 2 ). 60 refs, 3 figs, 4 tabs, 11 appendices

Achieving mainstream nitrogen removal through simultaneous partial nitrification, anammox and denitrification process in an integrated fixed film activated sludge reactor.

Science.gov (United States)

Wang, Chao; Liu, Sitong; Xu, Xiaochen; Zhang, Chaolei; Wang, Dong; Yang, Fenglin

2018-07-01

The anaerobic ammonium oxidation (anammox) is becoming a critical technology for energy neutral in mainstream wastewater treatment. However, the presence of chemical oxygen demanding in influent would result in a poor nitrogen removal efficiency during the deammonification process. In this study, the simultaneous partial nitrification, anammox and denitrification process (SNAD) for mainstream nitrogen removal was investigated in an integrated fixed film activated sludge (IFAS) reactor. SNAD-IFAS process achieved a total nitrogen (TN) removal efficiency of 72 ± 2% and an average COD removal efficiency was 88%. The optimum COD/N ratio for mainstream wastewater treatment was 1.2 ± 0.2. Illumina sequencing analysis and activity tests showed that anammox and denitrifying bacteria were the dominant nitrogen removal microorganism in the biofilm and the high COD/N ratios (≥2.0) leaded to the proliferation of heterotrophic bacteria (Hydrogenophaga) and nitrite-oxidizing bacteria (Nitrospira) in the suspended sludge. Network analysis confirmed that anammox bacteria (Candidatus Kuenenia) could survive in organic matter environment due to that anammox bacteria displayed significant co-occurrence through positive correlations with some heterotrophic bacteria (Limnobacter) which could protect anammox bacteria from hostile environments. Overall, the results of this study provided more comprehensive information regarding the community composition and assemblies in SNAD-IFAS process for mainstream nitrogen removal. Copyright © 2018 Elsevier Ltd. All rights reserved.

Removal of nitrogen compounds from Brazilian petroleum samples by oxidation followed by liquid-liquid extraction

Energy Technology Data Exchange (ETDEWEB)

Conceicao, L.; Pergher, S.B.C. [Universidade Regional Integrada do Alto Uruguai e das Misses (URI), Erechim, RS (Brazil). Dept. de Quimica], E-mail: pergher@uricer.edu.br; Oliveira, J.V. [Universidade Regional Integrada do Alto Uruguai e das Misses (URI), Erechim, RS (Brazil). Dept. de Engenharia dos Alimentos; Souza, W.F. [Petroleo Brasileiro S.A. (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

2009-10-15

This work reports liquid-liquid extraction of nitrogen compounds from oxidized and non-oxidized Brazilian petroleum samples. The experiments were accomplished in a laboratory-scale liquid-liquid apparatus in the temperature range of 303 K-323 K, using methanol, n-methyl-2-pyrrolidone (NMP) and N,Ndimethylformamide (DMF), and their mixtures as extraction solvents, employing solvent to sample volume ratios of 1:2, 1:1 and 2:1, exploring up to three separation stages. Results show that an increase in temperature, solvent to oil ratio, and number of equilibrium stages greatly improves the nitrogen removal from the oxidized sample (from 2600 to 200 ppm). The employed oxidation scheme is thus demonstrated to be an essential and efficient step of sample preparation for the selective liquid-liquid removal of nitrogen compounds. It is shown that the use of mixtures of DMF and NMP as well their use as co-solvents with methanol did not prove to be useful for selective nitrogen extraction since great oil losses were observed in the final process. (author)

Control of SHARON reactor for autotrophic nitrogen removal in two-reactor configuration

DEFF Research Database (Denmark)

Valverde Perez, Borja; Mauricio Iglesias, Miguel; Sin, Gürkan

2012-01-01

With the perspective of investigating a suitable control design for autotrophic nitrogen removal, this work explores the control design for a SHARON reactor. With this aim, a full model is developed, including the pH dependency, in order to simulate the reactor and determine the optimal operating...

A robust nitrifying community in a bioreactor at 50°C opens up the path for thermophilic nitrogen removal

NARCIS (Netherlands)

Courtens, E.N.P.; Spieck, E.; Vilchez-Vargas, R.; Bodé, S.; Boeckx, P.; Schouten, S.; Jáuregui, R.; Pieper, D.H.; Vlaeminck, S.E.; Boon, N.

2016-01-01

The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes

Biological phosphorus and nitrogen removal in sequencing batch reactors: effects of cycle length, dissolved oxygen concentration and influent particulate matter.

Science.gov (United States)

Ginige, Maneesha P; Kayaalp, Ahmet S; Cheng, Ka Yu; Wylie, Jason; Kaksonen, Anna H

2013-01-01

Removal of phosphorus (P) and nitrogen (N) from municipal wastewaters is required to mitigate eutrophication of receiving water bodies. While most treatment plants achieve good N removal using influent carbon (C), the use of influent C to facilitate enhanced biological phosphorus removal (EBPR) is poorly explored. A number of operational parameters can facilitate optimum use of influent C and this study investigated the effects of cycle length, dissolved oxygen (DO) concentration during aerobic period and influent solids on biological P and N removal in sequencing batch reactors (SRBs) using municipal wastewaters. Increasing cycle length from 3 to 6 h increased P removal efficiency, which was attributed to larger portion of N being removed via nitrite pathway and more biodegradable organic C becoming available for EBPR. Further increasing cycle length from 6 to 8 h decreased P removal efficiencies as the demand for biodegradable organic C for denitrification increased as a result of complete nitrification. Decreasing DO concentration in the aerobic period from 2 to 0.8 mg L(-1) increased P removal efficiency but decreased nitrification rates possibly due to oxygen limitation. Further, sedimented wastewater was proved to be a better influent stream than non-sedimented wastewater possibility due to the detrimental effect of particulate matter on biological nutrient removal.

Removal of nitrogen and organic matter in a submerged-membrane bioreactor operating in a condition of simultaneous nitrification and denitrification

Directory of Open Access Journals (Sweden)

Izabela Major Barbosa

2016-04-01

Full Text Available This study evaluated the removal of nitrogen and organic matter in a membrane bioreactor system operating in a condition of simultaneous nitrification and denitrification controlled by intermittent aeration. A submerged-membrane system in a bioreactor was used in a pilot scale to treat domestic wastewater. The dissolved oxygen concentration was maintained between 0.5 and 0.8 mg L-1. The concentration of the mixed liquor suspended solids (MLSS in the system ranged from 1 to 6 g L-1. The system efficiency was evaluated by the removal efficiency of organic matter, quantified by Chemical Oxygen Demand (COD, Biochemical Oxygen Demand (BOD5 and Total Organic Carbon (TOC. Nitrogen removal was assessed by quantifying Total Kjeldahl Nitrogen (TKN and ammonia nitrogen. During the system start-up, the removal efficiencies of COD and NTK were around 90% and 80%, respectively. After the simultaneous nitrification and denitrification (SND conditions were established, the removal efficiencies of COD and NTK were 70% and 99%, respectively. These results showed that sewage treatment with the membrane bioreactor (MBR system, operating with simultaneous nitrification and denitrification conditions, was able to remove organic matter and promote nitrification and denitrification in a single reactor, producing a high-quality permeate.

Robust biological nitrogen removal by creating multiple tides in a single bed tidal flow constructed wetland.

Science.gov (United States)

Hu, Yuansheng; Zhao, Yaqian; Rymszewicz, Anna

2014-02-01

Achieving effective total nitrogen (TN) removal is one of the major challenges faced by constructed wetlands (CWs). To address this issue, multiple "tides" were proposed in a single stage tidal flow constructed wetland (TFCW). With this adoption, exceptional TN removal (85% on average) was achieved under a high nitrogen loading rate (NLR) of around 28 g Nm(-2)day(-1), which makes the proposed system an adequate option to provide advanced wastewater treatment for peri-urban communities and rural area. It was revealed that the multiple "tides" not only promoted TN removal performance, but also brought more flexibility to TFCWs. Adsorption of NH4(+)-N onto the wetland medium (during contact period) and regeneration of the adsorption capacity via nitrification (during bed resting) were validated as the key processes for NH4(+)-N conversion in TFCWs. Moreover, simultaneous nitrification denitrification (SND) was found to be significant during the bed resting period. These findings will provide a new foundation for the design and modeling of nitrogen conversion and oxygen transfer in TFCWs. © 2013.

Organics and nitrogen removal from textile auxiliaries wastewater with A{sup 2}O-MBR in a pilot-scale

Energy Technology Data Exchange (ETDEWEB)

Sun, Faqian [Institute of Environmental Science and Technology, Zhejiang University, Hangzhou 310058 (China); Sun, Bin [Institute of Environmental Science and Technology, Zhejiang University, Hangzhou 310058 (China); Shanghai Electric Group Co. Ltd. Central Academe, Shanghai 200070 (China); Hu, Jian; He, Yangyang [Institute of Environmental Science and Technology, Zhejiang University, Hangzhou 310058 (China); Wu, Weixiang, E-mail: weixiang@zju.edu.cn [Institute of Environmental Science and Technology, Zhejiang University, Hangzhou 310058 (China)

2015-04-09

Highlights: • A pilot-scale A{sup 2}O-MBR system treating textile auxiliaries wastewater was assessed. • Organic matter and recycle ratio strongly affected the performance of the system. • GC/MS analysis found some refractory organics in the MBR permeate. • Combination of organic foulants and inorganic compounds caused membrane fouling. - Abstract: The removal of organic compounds and nitrogen in an anaerobic–anoxic–aerobic membrane bioreactor process (A{sup 2}O-MBR) for treatment of textile auxiliaries (TA) wastewater was investigated. The results show that the average effluent concentrations of chemical oxygen demand (COD), ammonium nitrogen (NH{sub 4}{sup +}–N) and total nitrogen (TN) were about 119, 3 and 48 mg/L under an internal recycle ratio of 1.5. The average removal efficiency of COD, NH{sub 4}{sup +}–N and TN were 87%, 96% and 55%, respectively. Gas chromatograph–mass spectrometer analysis indicated that, although as much as 121 different types of organic compounds were present in the TA wastewater, only 20 kinds of refractory organic compounds were found in the MBR effluent, which could be used as indicators of effluents from this kind of industrial wastewater. Scanning electron microscopy analysis revealed that bacterial foulants were significant contributors to membrane fouling. An examination of foulants components by wavelength dispersive X-ray fluorescence showed that the combination of organic foulants and inorganic compounds enhanced the formation of gel layer and thus caused membrane fouling. The results will provide valuable information for optimizing the design and operation of wastewater treatment system in the textile industry.

Towards a plant-wide Benchmark Simulation Model with simultaneous nitrogen and phosphorus removal wastewater treatment processes

DEFF Research Database (Denmark)

Flores-Alsina, Xavier; Ikumi, David; Batstone, Damien

It is more than 10 years since the publication of the Benchmark Simulation Model No 1 (BSM1) manual (Copp, 2002). The main objective of BSM1 was creating a platform for benchmarking carbon and nitrogen removal strategies in activated sludge systems. The initial platform evolved into BSM1_LT and BSM....... This extension aims at facilitating simultaneous carbon, nitrogen and phosphorus (P) removal process development and performance evaluation at a plant-wide level. The main motivation of the work is that numerous wastewater treatment plants (WWTPs) pursue biological phosphorus removal as an alternative...... to chemical P removal based on precipitation using metal salts, such as Fe or Al. This paper identifies and discusses important issues that need to be addressed to upgrade the BSM2 to BSM2-P, for example: 1) new influent wastewater characteristics; 2) new (bio) chemical processes to account for; 3...

Nitrogen removal in Northern peatlands treating mine wastewaters

Science.gov (United States)

Palmer, Katharina; Karlsson, Teemu; Turunen, Kaisa; Liisa Räisänen, Marja; Backnäs, Soile

2015-04-01

Natural peatlands can be used as passive purification systems for mine wastewaters. These treatment peatlands are well-suited for passive water treatment as they delay the flow of water, and provide a large filtration network with many adsorptive surfaces on plant roots or soil particles. They have been shown to remove efficiently harmful metals and metalloids from mine waters due to variety of chemical, physical and biological processes such as adsorption, precipitation, sedimentation, oxidation and reduction reactions, as well as plant uptake. Many factors affect the removal efficiency such as inflow water quality, wetland hydrology, system pH, redox potential and temperature, the nature of the predominating purification processes, and the presence of other components such as salts. However, less attention has been paid to nitrogen (N) removal in peatlands. Thus, this study aimed to assess the efficiency of N removal and seasonal variation in the removal rate in two treatment peatlands treating mine dewatering waters and process effluent waters. Water sampling from treatment peatland inflow and outflow waters as well as pore waters in peatland were conducted multiple times during 2012-2014. Water samples were analysed for total N, nitrate-N and ammonium-N. Additionally, an YSI EXO2 device was used for continuous nitrate monitoring of waters discharged from treatment peatlands to the recipient river during summer 2014. The results showed that the oxic conditions in upper peat layer and microbial activity in treatment peatlands allowed the efficient oxidation of ammonium-N to nitrite-N and further to nitrate-N during summer time. However, the slow denitrification rate restricts the N removal as not all of the nitrate produced during nitrification is denitrified. In summer time, the removal rate of total N varied between 30-99 % being highest in late summer. N removal was clearly higher for treatment peatland treating process effluent waters than for peatland

Removal of nitrogen and phosphorus from dairy wastewater using constructed wetlands systems operating in batch

Directory of Open Access Journals (Sweden)

Ronaldo Rocha Bastos

2012-08-01

Full Text Available This work presents the results of a study conducted for a period of seven months on the effectiveness of constructed wetland systems for the treatment of dairy wastewater aiming at removing, nitrogen and phosphorus. Six experimental systems were assembled with a net volume of 115 L using HDPE tanks, with length/width ratio of 2:1. In three of the systems, gravel 0 was used as substrate, while gravel 0 and sand was used in the three others, in the percentage of 80% and 20%, respectively. The systems were operated in batch cycles of 48 hours, applying 7.5 L of influent per cycle. Four of the experimental units were cultivated, and two kept as controls. The selected species chosen were the macrophytes, Typha domingensis and Hedychium coronarium. The removal efficiency concerning nitrogen compounds showed to be quite promising with values ranging from 29.4 to 73.4%, while phosphorus removal from the beds was lower, reaching efficiencies between 18.61 and 34.3%, considered good values, since the removal of these substances is quite difficult through conventional treatment.

Control of a Biological Nitrogen Removal Process in an Intensified Single Reactor Configuration

DEFF Research Database (Denmark)

Vangsgaard, Anna Katrine; Mauricio Iglesias, Miguel; Gernaey, Krist

2013-01-01

The nitrogen removing granular sludge process is a novel and intensified process. However, its stable operation and control remains a challenging problem. In this contribution, a new process oriented approach is used to develop, evaluate and benchmark control strategies to ensure stable operation...

Deactivation of molybdate catalysts by nitrogen bases

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

1982-10-01

Nitrogen bases present in petroleum deactivate the surface of molybdate catalysts. The detrimental effect is attributed either to interactions of the bases with Lewis sites via unpaired electrons on nitrogen or to their ability to remove proton from the surface. The later effect results in a decrease of concentration of Bronsted sites known to be active in catalytic reactions. This enhances rate of coke forming reactions. Resistence of molybdate catalysts to coke formation depends on the form and redistribution of active ingredients on the surface. This can be effected by conditions applied during preparation and pretreatment of the catalysts. Processing parameters used during catalytic hydrotreatment are also important; i.e., the coke formation is slow under conditions ensuring high rate of removal of basic nitrogen containing compounds.

Efficient Total Nitrogen Removal in an Ammonia Gas Biofilter through High-Rate OLAND

DEFF Research Database (Denmark)

De Clippeleir, Haydée; Courtens, Emilie; Mosquera, Mariela

2012-01-01

Ammonia gas is conventionally treated in nitrifying biofilters; however, addition of organic carbon to perform post-denitrification is required to obtain total nitrogen removal. Oxygen-limited autotrophic nitrification/denitrification (OLAND), applied in full-scale for wastewater treatment, can...... offer a cost-effective alternative for gas treatment. In this study, the OLAND application thus was broadened toward ammonia loaded gaseous streams. A down flow, oxygen-saturated biofilter (height of 1.5 m; diameter of 0.11 m) was fed with an ammonia gas stream (248 ± 10 ppmv) at a loading rate of 0...... at water flow rates of 1.3 ± 0.4 m3 m–2 biofilter section d–1. Profile measurements revealed that 91% of the total nitrogen activity was taking place in the top 36% of the filter. This study demonstrated for the first time highly effective and sustainable autotrophic ammonia removal in a gas biofilter...

A novel approach to enhance biological nutrient removal using a culture supernatant from Micrococcus luteus containing resuscitation-promoting factor (Rpf) in SBR process.

Science.gov (United States)

Liu, Yindong; Su, Xiaomei; Lu, Lian; Ding, Linxian; Shen, Chaofeng

2016-03-01

A culture supernatant from Micrococcus luteus containing resuscitation-promoting factor (SRpf) was used to enhance the biological nutrient removal of potentially functional bacteria. The obtained results suggest that SRpf accelerated the start-up process and significantly enhanced the biological nutrient removal in sequencing batch reactor (SBR). PO4 (3-)-P removal efficiency increased by over 12 % and total nitrogen removal efficiency increased by over 8 % in treatment reactor acclimated by SRpf compared with those without SRpf addition. The Illumina high-throughput sequencing analysis showed that SRpf played an essential role in shifts in the composition and diversity of bacterial community. The phyla of Proteobacteria and Actinobacteria, which were closely related to biological nutrient removal, were greatly abundant after SRpf addition. This study demonstrates that SRpf acclimation or addition might hold great potential as an efficient and cost-effective alternative for wastewater treatment plants (WWTPs) to meet more stringent operation conditions and legislations.

Aeration control by monitoring the microbiological activity using fuzzy logic diagnosis and control. Application to a complete autotrophic nitrogen removal reactor

DEFF Research Database (Denmark)

Boiocchi, Riccardo; Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine

2015-01-01

Complete Autotrophic Nitrogen Removal (CANR) is a novel process where ammonia is converted to nitrogen gas by different microbial groups. The performance of the process can be compromised by an unbalanced activity of the biomass caused by disturbances or non-optimal operational conditions...... microbial groups on the other hand, the diagnosis provides information on: nitritation, nitratation, anaerobic ammonium oxidation and overall autotrophic nitrogen removal. These four results give insight into the state of the process and are used as inputs for the controller that manipulates the aeration...... to the reactor.The diagnosis tool was first evaluated using 100 days of real process operation data obtained from a lab-scale single-stage autotrophic nitrogen removing reactor. This evaluation revealed that the fuzzy logic diagnosis is able to provide a realistic description of the microbiological state...

Nitrous oxide production by lithotrophic ammonia-oxidizing bacteria and implications for engineered nitrogen-removal systems.

Science.gov (United States)

Chandran, Kartik; Stein, Lisa Y; Klotz, Martin G; van Loosdrecht, Mark C M

2011-12-01

Chemolithoautotrophic AOB (ammonia-oxidizing bacteria) form a crucial component in microbial nitrogen cycling in both natural and engineered systems. Under specific conditions, including transitions from anoxic to oxic conditions and/or excessive ammonia loading, and the presence of high nitrite (NO₂⁻) concentrations, these bacteria are also documented to produce nitric oxide (NO) and nitrous oxide (N₂O) gases. Essentially, ammonia oxidation in the presence of non-limiting substrate concentrations (ammonia and O₂) is associated with N₂O production. An exceptional scenario that leads to such conditions is the periodical switch between anoxic and oxic conditions, which is rather common in engineered nitrogen-removal systems. In particular, the recovery from, rather than imposition of, anoxic conditions has been demonstrated to result in N₂O production. However, applied engineering perspectives, so far, have largely ignored the contribution of nitrification to N₂O emissions in greenhouse gas inventories from wastewater-treatment plants. Recent field-scale measurements have revealed that nitrification-related N₂O emissions are generally far higher than emissions assigned to heterotrophic denitrification. In the present paper, the metabolic pathways, which could potentially contribute to NO and N₂O production by AOB have been conceptually reconstructed under conditions especially relevant to engineered nitrogen-removal systems. Taken together, the reconstructed pathways, field- and laboratory-scale results suggest that engineering designs that achieve low effluent aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

The production of cyanobacterial carbon under nitrogen-limited cultivation and its potential for nitrate removal.

Science.gov (United States)

Huang, Yingying; Li, Panpan; Chen, Guiqin; Peng, Lin; Chen, Xuechu

2018-01-01

Harmful cyanobacterial blooms (CyanoHABs) represent a serious threat to aquatic ecosystems. A beneficial use for these harmful microorganisms would be a promising resolution of this urgent issue. This study applied a simple method, nitrogen limitation, to cultivate cyanobacteria aimed at producing cyanobacterial carbon for denitrification. Under nitrogen-limited conditions, the common cyanobacterium, Microcystis, efficiently used nitrate, and had a higher intracellular C/N ratio. More importantly, organic carbons easily leached from its dry powder; these leachates were biodegradable and contained a larger amount of dissolved organic carbon (DOC) and carbohydrates, but a smaller amount of dissolved total nitrogen (DTN) and proteins. When applied to an anoxic system with a sediment-water interface, a significant increase of the specific NO X - -N removal rate was observed that was 14.2 times greater than that of the control. This study first suggests that nitrogen-limited cultivation is an efficient way to induce organic and carbohydrate accumulation in cyanobacteria, as well as a high C/N ratio, and that these cyanobacteria can act as a promising carbon source for denitrification. The results indicate that application as a carbon source is not only a new way to utilize cyanobacteria, but it also contributes to nitrogen removal in aquatic ecosystems, further limiting the proliferation of CyanoHABs. Copyright © 2017. Published by Elsevier Ltd.

Phosphorus and nitrogen removal in waste water at small factory. Shokibo jigyosho ni okeru haisuichu no rin chisso shori gijutsu

Energy Technology Data Exchange (ETDEWEB)

Hirai, M. (National Institute for Resources and Environment, Tsukuba (Japan))

1994-05-25

For the purpose of preventing closed waters from eutrophicating, COD regulations and nitrogen and phosphorus waste water regulations are executed in Japan, but practically applicable techniques for this purpose are a few. Concerning technology for removing nitrogen and phosphorus in waste water, this paper describes the actual situation of two industries, electroplating and alumite processing, and applicable techniques. Among various nitrogen removal methods, the biological treatment method has been used practically in many cases and is applicable to practical use. While there are many kinds of physical and chemical treatment methods, applicable methods are limited. In removing nitrogen, the coagulating sedimentation method with Ca salt, Al salt and Fe salt is effective generally for orthophosphate. At electroplating factories, various forms of phosphorus and nitrogen compounds are used as plating chemicals. In treating waste water containing phosphorus, the coagulating sedimentation method is used most frequently. The oxidation + coagulating sedimentation method, the autolysis + oxidation coagulation method, and the evaporation method are effected, though the examples of their implementation are small in number. 15 tabs.

Incremental design of control system of SHARON-Anammox process for autotrophic nitrogen removal

DEFF Research Database (Denmark)

Mauricio Iglesias, Miguel; Valverde Perez, Borja; Sin, Gürkan

2012-01-01

With the perspective of investigating a suitable control design for autotrophic nitrogen removal, this work explores the control design for a SHARON-Anammox reactor sequence. With this aim, a full model is developed, including the pH dependency, in order to simulate the reactor and determine...

Advances in wastewater nitrogen removal by biological processes: state of the art review

Directory of Open Access Journals (Sweden)

Andrea G. Capodaglio

2016-04-01

Full Text Available The paper summarizes the state-of-the-art of the most recent advances in biological nitrogen removal, including process design criteria and technological innovations. With reference to the Modified Ludzck Ettinger (MLE process (pre-denitrification and nitrification in the activated sludge process, the most common nitrogen removal process used nowadays, a new design equation for the denitrification reactor based on specific denitrification rate (SDNR has been proposed. In addition, factors influencing SDNR (DO in the anoxic reactor; hydrodynamic behavior are analyzed, and technological solutions are proposed. Concerning technological advances, the paper presents a summary of various “deammonification” processes, better known by their patent names like ANAMMOX®, DEMON®, CANON®, ANITA® and others. These processes have already found applications in the treatment of high-strength wastewater such as digested sludge liquor and landfill leachate. Among other emerging denitrification technologies, consideration is given to the Membrane Biofilm Reactors (MBfRs that can be operated both in oxidation and reduction mode.

Energy and chemical efficient nitrogen removal at a full-scale MBR water reuse facility

Directory of Open Access Journals (Sweden)

Jianfeng Wen

2015-02-01

Full Text Available With stringent wastewater discharge limits on nitrogen and phosphorus, membrane bioreactor (MBR technology is gaining popularity for advanced wastewater treatment due to higher effluent quality and smaller footprint. However, higher energy intensity required for MBR plants and increased operational costs for nutrient removal limit wide application of the MBR technology. Conventional nitrogen removal requires intensive energy inputs and chemical addition. There are drivers to search for new technology and process control strategies to treat wastewater with lower energy and chemical demand while still producing high quality effluent. The NPXpress is a patented technology developed by American Water engineers. This technology is an ultra-low dissolved oxygen (DO operation for wastewater treatment and is able to remove nitrogen with less oxygen requirements and reduced supplemental carbon addition in MBR plants. Jefferson Peaks Water Reuse Facility in New Jersey employs MBR technology to treat municipal wastewater and was selected for the implementation of the NPXpress technology. The technology has been proved to consistently produce a high quality reuse effluent while reducing energy consumption and supplemental carbon addition by 59% and 100%, respectively. Lab-scale kinetic studies suggested that NPXpress promoted microorganisms with higher oxygen affinity. Process modelling was used to simulate treatment performance under NPXpress conditions and develop ammonia-based aeration control strategy. The application of the ammonia-based aeration control at the plant further reduced energy consumption by additional 9% and improved treatment performance with 35% reduction in effluent total nitrogen. The overall energy savings for Jefferson Peaks was $210,000 in four years since the implementation of NPXpress. This study provided an insight in design and operation of MBR plants with NPXpress technology and ultra-low DO operations.

Nitrogen and COD removal from domestic and synthetic wastewater in subsurface-flow constructed wetlands.

Science.gov (United States)

Collison, R S; Grismer, M E

2013-09-01

Comparisons of the performance of constructed-wetland systems (CWs) for treating domestic wastewater in the laboratory and field may use pathogen-free synthetic wastewater to avoid regulatory health concerns. However, little to no data are available describing the relative treatment efficiencies of CWs to both actual and synthetic domestic wastewaters so as to enable such comparison. To fill this gap, treatment performances with respect to organics (chemical organic demand; COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) and a similar-strength synthetic wastewater under planted and non-planted subsurface-flow CWs are determined. One pair of CWs was planted with cattails in May 2008, whereas the adjacent system was non-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each CWs, and effluent samples were collected and tested for COD and nitrogen species regularly during four different periods over six months. Overall, statistically significant greater removal of COD (-12%) and nitrogen (-5%) occurred from the synthetic as compared with the domestic wastewater from the planted and non-planted CWs. Effluent BOD5/COD ratios from the synthetic wastewater CWs averaged nearly twice that from the domestic wastewater CWs (0.17 vs 0.10), reflecting greater concentrations of readily degraded compounds. That removal fractions were consistent across the mid-range loading rates to the CWs suggests that the synthetic wastewater can be used in testing laboratory CWs with reasonable success in application of their results to the field.

Improved Eco-Friendly Recombinant Anabaena sp. Strain PCC7120 with Enhanced Nitrogen Biofertilizer Potential▿

Science.gov (United States)

Chaurasia, Akhilesh Kumar; Apte, Shree Kumar

2011-01-01

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields. PMID:21057013

Improved eco-friendly recombinant Anabaena sp. strain PCC7120 with enhanced nitrogen biofertilizer potential.

Science.gov (United States)

Chaurasia, Akhilesh Kumar; Apte, Shree Kumar

2011-01-01

Photosynthetic, nitrogen-fixing Anabaena strains are native to tropical paddy fields and contribute to the carbon and nitrogen economy of such soils. Genetic engineering was employed to improve the nitrogen biofertilizer potential of Anabaena sp. strain PCC7120. Constitutive enhanced expression of an additional integrated copy of the hetR gene from a light-inducible promoter elevated HetR protein expression and enhanced functional heterocyst frequency in the recombinant strain. The recombinant strain displayed consistently higher nitrogenase activity than the wild-type strain and appeared to be in homeostasis with compatible modulation of photosynthesis and respiration. The enhanced combined nitrogen availability from the recombinant strain positively catered to the nitrogen demand of rice seedlings in short-term hydroponic experiments and supported better growth. The engineered strain is stable, eco-friendly, and useful for environmental application as nitrogen biofertilizer in paddy fields.

The regional and global significance of nitrogen removal in lakes and reservoirs

Science.gov (United States)

Harrison, J.A.; Maranger, R.J.; Alexander, Richard B.; Giblin, A.E.; Jacinthe, P.-A.; Mayorga, Emilio; Seitzinger, S.P.; Sobota, D.J.; Wollheim, W.M.

2009-01-01

Human activities have greatly increased the transport of biologically available nitrogen (N) through watersheds to potentially sensitive coastal ecosystems. Lentic water bodies (lakes and reservoirs) have the potential to act as important sinks for this reactive N as it is transported across the landscape because they offer ideal conditions for N burial in sediments or permanent loss via denitrification. However, the patterns and controls on lentic N removal have not been explored in great detail at large regional to global scales. In this paper we describe, evaluate, and apply a new, spatially explicit, annual-scale, global model of lentic N removal called NiRReLa (Nitrogen Retention in Reservoirs and Lakes). The NiRReLa model incorporates small lakes and reservoirs than have been included in previous global analyses, and also allows for separate treatment and analysis of reservoirs and natural lakes. Model runs for the mid-1990s indicate that lentic systems are indeed important sinks for N and are conservatively estimated to remove 19.7 Tg N year-1 from watersheds globally. Small lakes (<50 km2) were critical in the analysis, retaining almost half (9.3 Tg N year -1) of the global total. In model runs, capacity of lakes and reservoirs to remove watershed N varied substantially at the half-degree scale (0-100%) both as a function of climate and the density of lentic systems. Although reservoirs occupy just 6% of the global lentic surface area, we estimate they retain ~33% of the total N removed by lentic systems, due to a combination of higher drainage ratios (catchment surface area:lake or reservoir surface area), higher apparent settling velocities for N, and greater average N loading rates in reservoirs than in lakes. Finally, a sensitivity analysis of NiRReLa suggests that, on-average, N removal within lentic systems will respond more strongly to changes in land use and N loading than to changes in climate at the global scale. ?? 2008 Springer Science

Development of anaerobic ammonium oxidation (anammox) for biological nitrogen removal in domestic wastewater treatment (Case study: Surabaya City, Indonesia)

Science.gov (United States)

Wijaya, I. Made Wahyu; Soedjono, Eddy Setiadi; Fitriani, Nurina

2017-11-01

Domestic wastewater effluent is the main contributor to diverse water pollution problems. The contaminants contained in the wastewater lead the low quality of water. The presence of ammonium and nitrate along with phosphorus are potentially cause eutrophication and endanger aquatic life. Excess nutrients, mostly N and P is the main cause of eutrophication which is result in oxygen depletion, biodiversity reduction, fish kills, odor and increased toxicity. Most of the domestic wastewater in Surabaya City still contains nitrogen that exceeded the threshold. The range of ammonium and orthophosphate concentration in the domestic wastewater is between 6.29 mg/L - 38.91 mg/L and 0.44 mg/L - 1.86 mg/L, respectively. An advance biological nitrogen removal process called anammox is a sustainable and cost effective alternative to the basic method of nitrogen removal, such as nitrification and denitrification. Many research have been conducted through anammox and resulted promisingly way to remove nitrogen. In this process, ammonium will be oxidized with nitrite as an electron acceptor to produce nitrogen gas and low nitrate in anoxic condition. Anammox requires less oxygen demand, no needs external carbon source, and low operational cost. Based on its advantages, anammox is possible to apply in domestic wastewater treatment in Surabaya with many further studies.

Advanced treatment technique for swine wastewater using two agents: Thermally polymerized amorphous silica and hydrated lime for color and phosphorus removal and sulfur for nitrogen removal.

Science.gov (United States)

Hasegawa, Teruaki; Kurose, Yohei; Tanaka, Yasuo

2017-10-01

The efficacy of advanced treatment of swine wastewater using thermally polymerized, modified amorphous silica and hydrated lime (M-CSH-lime) for color and phosphorus removal and sulfur for nitrogen removal was examined with a demonstration-scale treatment plant. The color removal rate was approximately 78% at M-CSH-lime addition rates of > 0.055 wt/v%. The PO43--P removal rate exceeded 99.9% with > 0.023 wt/v%. pH of the effluent from the M-CSH-lime reactor increased with the addition rate till a maximum value of 12.7, which was effective in disinfection. The recovered M-CSH-lime would be suitable as a phosphorus fertilizer because the total P 2 O 5 content was approximately 10%. The nitrogen oxide (NOx-N) removal rate by sulfur denitrification increased to approximately 80% when the NOx-N loading rate was around 0.1 kg-N/ton-S/day. It was suggested that the combination of the two processes would be effective in the advanced treatment of swine wastewater. © 2017 Japanese Society of Animal Science.

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

Completely autotrophic nitrogen removal, coupling aerobic and anaerobic ammonium oxidation, can be achieved via redox stratified biofilms growing on gas-permeable membranes. These sequential reactions are mediated by aerobic and anaerobic ammonium oxidizing bacteria (AOB and AnAOB). The major...

Nitrogen removal and water microbiota in grass carp culture following supplementation with Bacillus licheniformis BSK-4.

Science.gov (United States)

Liang, Quan; Zhang, Xiaoping; Lee, Khui Hung; Wang, Yibing; Yu, Kan; Shen, Wenying; Fu, Luoqin; Shu, Miaoan; Li, Weifen

2015-11-01

This experiment was designed to study the effects of Bacillus licheniformis BSK-4 on nitrogen removal and microbial community structure in a grass carp (Ctenopharyngodon idellus) culture. The selected strain Bacillus licheniformis BSK-4 significantly decreased nitrite, nitrate and total nitrogen levels in water over an extended, whereas increased ammonia level. Pyrosequencing showed that Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes were dominant in grass carp culture water. Compared with the control group, the number of Proteobacteria and Firmicutes were increased, while Actinobacteria and Bacteroidetes decreased in treatment group. At the genus level, some genera, such as Bacillus, Prosthecobacter, Enterococcus, etc., appear only in the treatment, while many other genera exist only in the control group; Lactobacillus, Luteolibacter, Phenylobacterium, etc. were increased in treatment group compared to those in control group. As above, the results suggested that supplementation with B. licheniformis BSK-4 could remove some nitrogen and cause alterations of the microbial composition in grass carp water.

[Effect of Elodea nuttallii-immobilized Nitrogen Cycling Bacteria on Nitrogen Removal Mechanism in an Inflow River, Gonghu Bay].

Science.gov (United States)

Han, Hua-yang; Li, Zheng-kui; Wang, Hao; Zhu, Qian

2016-04-15

Undisturbed sediment cores and surface water from Qinshui River in Gonghu Bay were collected to carry out a simulation experiment in our laboratory. The remediation effect of Elodea nuttallii-Immobilized Nitrogen Cycling Bacteria (INCB) was applied in the polluted inflow river. The denitrification rate, ANAMMOX rate and nitrogen microorganism diversity were measured by ¹⁵N isotope pairing technology and high-throughput sequencing technology based on 16S rRNA. The TN, NH₄⁺-N, NO₃⁻-N concentrations were reduced by 72.03%, 46.67% and 76.65% in the treatment with addition of Elodea nuttallii and INCB in our laboratory experiment. Meanwhile, denitrification bacteria and ANAMMOX bacteria had synergistic effect with each other. The denitrification and ANAMMOX rates were increased by 165 µmol (m² · h)⁻¹ and 269.7 µmol · (m² · h)⁻¹, respectively. The diversities of denitrification and ANAMMOX bacteria also increased in our experiment. From the level of major phylum, Proteobacteria, Planctomycetes, Acidobbacteria and Bacteroidetes all increased significantly. The results showed that the Elodea nuttallii-INCB assemblage technology could increase the bio-diversity of nitrogen cycling bacteria and promote the ability of nitrogen removal in Qinshui River.

Specific ability of sulfur-ligands on removal of 203Hg-labeled organomercury from hemoglobin in comparison with nitrogen-ligands

International Nuclear Information System (INIS)

Hojo, Yasuji; Sugiura, Yukio; Tanaka, Hisashi

1975-01-01

Removal of 203 Hg-labeled organomercurials, bound to sulfhydryl groups of hemoglobin, by various chelating agents was investigated by the use of equilibrium dialysis. Organomercurials employed were chlormerodrin, methylmercury, ethylmercury and phenylmercury compounds. Higher and more specific effects of the sulfur-ligands, such as penicillamine and glutathione, on removal of organomercurial were found as compared with those of the nitrogen-ligands such as EDTA, glycine and polymethylenediamines. Linear correlation was observed between the degree of organomercury elimination from hemoglobin and the stability constant (log K 1 ) of 1:1 organomercury complex in both the sulfur- and nitrogen-ligand systems and at the same value of log K 1 , the elimination-effect of sulfur-ligands was extremely greater than that of the nitrogen-ligands. The relationship between the average percentage of removal and the Taft's polar substituent constant of organic moiety of the metal was also linear among the organomercury compounds other than chlormerodrin. The average removal percentage by sulfur-ligands increased in the order, ethylmercury>methylmercury>phenylmercury, while that of the nitrogen-ligands was not different among the organomercurials investigated. In addition, direct ligand-exchange reaction between hemoglobin-SH and the ligand coordinating-atom (S or N) against organomercurials rather than Ssub(N2) reaction via the ternary complex, hemoglobin-S-RHg-ligand, is postulated. (auth.)

Effect of nitrogen doping on titanium carbonitride-derived adsorbents used for arsenic removal

Energy Technology Data Exchange (ETDEWEB)

Han, Jisun [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Soonjae [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Choi, Keunsu [Computational Science Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Jinhong [Samsung Electronics Co.Ltd.,(Maetan dong) 129, Samsung-ro Yeongtong-gu, Suwonsi, Gyeonggi-do 443-742, Repubilc of Korea (Korea, Republic of); Ha, Daegwon [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, Chang-Gu [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); An, Byungryul [Department of Civil Engineering, Sangmyung University, Cheonan, Chungnam 31066 (Korea, Republic of); Lee, Sang-Hyup [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Mizuseki, Hiroshi, E-mail: mizuseki@kist.re.kr [Computational Science Research Center, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Choi, Jae-Woo, E-mail: plead36@kist.re.kr [Center for Water Resource Cycle Research, Korea Institute of Science and Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Department of Energy and Environmental Engineering, University of Science and Technology (UST), Daejeon 305-350 (Korea, Republic of); Kang, Shinhoo, E-mail: shinkang@snu.ac.kr [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2016-01-25

Highlights: • The N-doping can improve the As adsorption performance of carbon-based materials. • The material features high micro- and small meso-pores with exceptional surface area. • Pyrrolic N atoms distributed uniformly on the micropores act as adsorption sites. • The synthesis temperature affected pore properties and surface functional groups. - Abstract: Arsenic in water and wastewater is considered to be a critical contaminant as it poses harmful health risks. In this regard, to meet the stringent regulation of arsenic in aqueous solutions, nitrogen doped carbon-based materials (CN) were prepared as adsorbents and tested for the removal of arsenic ion from aqueous solutions. Nitrogen-doped carbon (CNs) synthesized by chlorination exhibited well-developed micro- and small meso-pores with uniform pore structures. The structure and characteristics of the adsorbents thus developed were confirmed by field-emission scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. Among the CNs developed, CN700 exhibited high adsorption capacity for arsenic (31.08 mg/g). The adsorption efficiency for arsenic ion was confirmed to be affected by pyrrolic nitrogen and micro-pores. These results suggest that CNs are useful adsorbents for the treatment of arsenic, and in particular, CN700 demonstrates potential for application as an adsorbent for the removal of anionic heavy metals from wastewater and sewage.

Selecting appropriate forms of nitrogen fertilizer to enhance soil arsenic removal by Pteris vittata: a new approach in phytoremediation.

Science.gov (United States)

Liao, Xiao-Yong; Chen, Tong-Bin; Xiao, Xi-Yuan; Xie, Hua; Yan, Xiu-Lan; Zhai, Li-Mei; Wu, Bin

2007-01-01

Certain plant species have been shown to vigorously accumulate some metals from soil, and thus represent promising and effective remediation alternatives. In order to select the optimum forms of nitrogen (N) fertilizers for the arsenic (As) hyperaccumulator, Pteris vittata L., to maximize As extraction, five forms of N were added individually to different treatments to study the effect of N forms on As uptake of the plants under soil culture in a greenhouse. Although shoot As concentration tended to decrease and As translocation from root to shoot was inhibited, overall As accumulation was greater due to higher biomass when N fertilizer was added. Arsenic accumulation in plants with N fertilization was 100-300% more than in the plants without N fertilization. There were obvious differences in plant biomass and As accumulation among the N forms, i.e., NH4HCO3, (NH4)2S04, Ca(NO3)2, KNO3, urea. The total As accumulation in the plants grown in As-supplied soil, under different forms of N fertilizer, decreased as NH4HCO3>(NH4)2S04 > urea > Ca(NO3)2 >KNO3>CK. The plants treated with N and As accumulated up to 5.3-7.97 mg As/pot and removed 3.7-5.5% As from the soils, compared to approximately 2.3% of As removal in the control. NH4+ -N was apparently more effective than other N fertilizers in stimulating As removal when soil was supplied with As at initiation. No significant differences in available As were found among different forms of N fertilizer after phytoremediation. It is concluded that NH4+ -N was the preferable fertilizer for P. vittata to maximize As removal.

Nitrogen removal capacity and bacterial community dynamics of a Canon biofilter system at different organic matter concentrations.

Science.gov (United States)

García-Ruiz, María J; Maza-Márquez, Paula; González-López, Jesús; Osorio, Francisco

2018-02-01

Three Canon bench-scale bioreactors with a volume of 2 L operating in parallel were configured as submerged biofilters. In the present study we investigated the effects of a high ammonium concentration (320 mgNH 4 + · L -1 ) and different concentrations of organic matter (0, 100 and 400 mgCOD·L -1 ) on the nitrogen removal capacity and the bacterial community structure. After 60 days, the Canon biofilters operated properly under concentrations of 0 and 100 mgCOD·L -1 of organic matter, with nitrogen removal efficiencies up to 85%. However, a higher concentration of organic matter (400 mgCOD·L -1 ) produced a partial inhibition of nitrogen removal (68.1% efficiency). The addition of higher concentrations of organic matter a modified the bacterial community structure in the Canon biofilter, increasing the proliferation of heterotrophic bacteria related to the genera of Thauera, Longilinea, Ornatilinea, Thermomarinilinea, unclassified Chlorobiales and Denitratisoma. However, heterotrophic bacteria co-exist with Nitrosomonas and Candidatus Scalindua. Thus, our study confirms the co-existence of different microbial activities (AOB, Anammox and denitrification) and the adaptation of a fixed-biofilm system to different concentrations of organic matter. Copyright © 2017 Elsevier Ltd. All rights reserved.

Waste water treatment plants with removal of nitrogens and phosphorous; Planta de tratamiento de aguas residuales con eliminacion de fosforo y nitrogeno

Energy Technology Data Exchange (ETDEWEB)

Kroiss, H.

1996-10-01

Wherever waste water is discharged into a receiving water of a sensitive area the treatment efficiency has to be increased beyond the removal of easily biodegradable carbonaceous compounds (BOD{sub 5}). The main requirements are then the removal of nitrogens and phosphorous compounds in order to prevent eutrophication in the receiving water. With these requirements a much better removal of carbonaceous matter is achieved too. One of this prerequisites for nitrogen removal is the nitrification process wich removes ammonia toxicity from the waste water. The removal of ammonia from the waste water can easily be monitored by the treatment plant operators and can be classified as the best indicator for a stable high treatment efficiency for every waste water.

Investigation on thiosulfate-involved organics and nitrogen removal by a sulfur cycle-based biological wastewater treatment process.

Science.gov (United States)

Qian, Jin; Lu, Hui; Cui, Yanxiang; Wei, Li; Liu, Rulong; Chen, Guang-Hao

2015-02-01

Thiosulfate, as an intermediate of biological sulfate/sulfite reduction, can significantly improve nitrogen removal potential in a biological sulfur cycle-based process, namely the Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI(®)) process. However, the related thiosulfate bio-activities coupled with organics and nitrogen removal in wastewater treatment lacked detailed examinations and reports. In this study, S2O3(2-) transformation during biological SO4(2-)/SO3(2-) co-reduction coupled with organics removal as well as S2O3(2-) oxidation coupled with chemolithotrophic denitrification were extensively evaluated under different experimental conditions. Thiosulfate is produced from the co-reduction of sulfate and sulfite through biological pathway at an optimum pH of 7.5 for organics removal. And the produced S2O3(2-) may disproportionate to sulfide and sulfate during both biological S2O3(2-) reduction and oxidation most possibly carried out by Desulfovibrio-like species. Dosing the same amount of nitrate, pH was found to be the more direct factor influencing the denitritation activity than free nitrous acid (FNA) and the optimal pH for denitratation (7.0) and denitritation (8.0) activities were different. Spiking organics significantly improved both denitratation and denitritation activities while minimizing sulfide inhibition of NO3(-) reduction during thiosulfate-based denitrification. These findings in this study can improve the understanding of mechanisms of thiosulfate on organics and nitrogen removal in biological sulfur cycle-based wastewater treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced Biological Phosphorus Removal : Metabolic Insights and Salinity Effects

NARCIS (Netherlands)

Welles, L.

2015-01-01

Enhanced biological phosphorus removal (EBPR) is a biological process for efficient phosphate removal from wastewaters through intracellular storage of polyphosphate by polyphosphate-accumulating organisms (PAO) and subsequent removal of PAO from the system through wastage of sludge. In comparison

Liquid nitrogen enhancement of alpha particle tracks in a polycarbonate detector

International Nuclear Information System (INIS)

Pilione, L.J.

1977-01-01

Makrofol-E polycarbonate detectors were exposed to 1 to 3 MeV alpha particles and subsequently immersed in liquid nitrogen for various periods of time. The influence of the liquid nitrogen on the track recording properties of the detector has been found by measuring the track densities and diameters. Track densities increase with immersion time with a maximum gain of approximately 9% after 1200 min in liquid nitrogen. Track enhancement decreases with waiting time between the end of alpha particle exposure and the beginning of liquid nitrogen immersion. Track diameters decrease with time after passage of the particles and this process is accelerated by immersion in liquid nitrogen. (author)

Optimized biological nitrogen removal of high-strength ammonium wastewater by activated sludge modeling

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Abdelsalam Elawwad

2018-09-01

Full Text Available Wastewater containing high ammonium concentrations is produced from various industrial activities. In this study, the author used a complex activated sludge model, improved by utilizing BioWin© (EnviroSim, Hamilton, Canada simulation software, to gain understanding of the problem of instability in biological nitrogen removal (BNR. Specifically, the study focused on BNR in an industrial wastewater treatment plant that receives high-strength ammonium wastewater. Using the data obtained from a nine-day sampling campaign and routinely measured data, the model was successfully calibrated and validated, with modifications to the sensitive stoichiometric and kinetic parameters. Subsequently, the calibrated model was employed to study various operating conditions in order to optimize the BNR. These operating conditions include alkalinity addition, sludge retention time, and the COD/N ratio. The addition of a stripping step and modifications to the configuration of the aerators are suggested by the author to increase the COD/N ratio and therefore enhance denitrification. It was found that the calibrated model could successfully represent and optimize the treatment of the high-strength ammonium wastewater.

Enhanced Biological Phosphorus Removal: Metabolic Insights and Salinity Effects

OpenAIRE

Welles, L.

2015-01-01

Enhanced biological phosphorus removal (EBPR) is a biological process for efficient phosphate removal from wastewaters through intracellular storage of polyphosphate by polyphosphate-accumulating organisms (PAO) and subsequent removal of PAO from the system through wastage of sludge. In comparison to physical and chemical phosphorus removal processes, the biological process has several advantages such as high removal efficiency, low cost, and no chemical sludge production, but disturbances an...

Study of nitrogen injection to enhance forced convection for gas fast reactors

International Nuclear Information System (INIS)

Tauveron, N.; Dor, I.; Bentivoglio, F.

2011-01-01

Highlights: → The present study concerns the use of blowers in case of nitrogen injection. It is a well-known fact that heavier gases (than helium) enhance natural circulation. The use of such heavier gases (nitrogen is considered here) can also enhance forced convection. → A specific work on the impact of the use of alternative gas on blower behaviour is presented. → These developments are used in a simplified system analysis and in a complete transient behaviour analysis in depressurised situations computed with the CATHARE2 code. - Abstract: In the frame of the international forum GenIV, the gas fast reactor is considered as a promising concept, combining the benefits of fast spectrum and high temperature, using helium as coolant. In the current preliminary viability GFR studies safety system relies on blowers in case of depressurised conditions. The present study concerns the use of blowers in case of nitrogen injection. It is a well-known fact that heavier gases (than helium) enhance natural circulation. The use of such gases (nitrogen is considered) can also enhance forced convection. A specific work on the impact of the use of alternative gas on blower behaviour is presented. Transient behaviours in depressurised situations are computed with the CATHARE2 code and analyzed.

Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

Science.gov (United States)

Stief, P.

2013-12-01

Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are important mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macrofauna stimulates microbial nutrient dynamics through different types of animal-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen (mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release of ammonium from sediments is enhanced more strongly than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna on benthic microbes apparently has small or neutral effects on nitrogen cycling. Animal-microbe symbioses provide abundant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies reveal that ecosystem engineering, grazing, and symbioses of benthic macrofauna significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and

New approaches to improve the removal of dissolved organic matter and nitrogen in aquaculture

DEFF Research Database (Denmark)

von Ahnen, Mathis

further due to the lack of cost-effective and easy applicable treatment methods for removing dissolved N and OM. The purpose of this PhD thesis was to assess the problem of removing dissolved N and OM in the context of the large differences in system intensity between farms, and to devise new, simple...... at increasing long-term waste loadings. The second part examined the potential of using anoxic denitrifying woodchip bioreactors for removal of nitrate from aquaculture effluent (Paper III-V). Investigations within the first part showed that the effectiveness of biofilters, as determined by their areal removal......-term biofilter loading up to a certain threshold. The latter indicated that the removal capacity of biofilters operated at lower loadings is easily exceeded, and that they may not respond very well to sudden increases in total ammonia nitrogen (TAN) concentrations. In the second part of the thesis, a field study...

Hydrogen Peroxide Enhances Removal of NOx from Flue Gases

Science.gov (United States)

Collins, Michelle M.

2005-01-01

Pilot scale experiments have demonstrated a method of reducing the amounts of oxides of nitrogen (NOx) emitted by industrial boilers and powerplant combustors that involves (1) injection of H2O2 into flue gases and (2) treatment of the flue gases by caustic wet scrubbing like that commonly used to remove SO2 from combustion flue gases. Heretofore, the method most commonly used for removing NOx from flue gases has been selective catalytic reduction (SCR), in which the costs of both installation and operation are very high. After further development, the present method may prove to be an economically attractive alternative to SCR.

Model evaluation of temperature dependency for carbon and nitrogen removal in a full-scale activated sludge plant treating leather-tanning wastewater.

Science.gov (United States)

Görgün, Erdem; Insel, Güçlü; Artan, Nazik; Orhon, Derin

2007-05-01

Organic carbon and nitrogen removal performance of a full-scale activated sludge plant treating pre-settled leather tanning wastewater was evaluated under dynamic process temperatures. Emphasis was placed upon observed nitrogen removal depicting a highly variable magnitude with changing process temperatures. As the plant was not specifically designed for this purpose, observed nitrogen removal could be largely attributed to simultaneous nitrification and denitrification presumably occurring at increased process temperatures (T>25 degrees C) and resulting low dissolved oxygen levels (DO<0.5 mgO2/L). Model evaluation using long-term data revealed that the yearly performance of activated sludge reactor could be successfully calibrated by means of temperature dependent parameters associated with nitrification, hydrolysis, ammonification and endogenous decay parameters. In this context, the Arrhenius coefficients of (i) for the maximum autotrophic growth rate, [image omitted]A, (ii) maximum hydrolysis rate, khs and (iii) endogenous heterotrophic decay rate, bH were found to be 1.045, 1.070 and 1.035, respectively. The ammonification rate (ka) defining the degradation of soluble organic nitrogen could not be characterized however via an Arrhenius-type equation.

Model-based optimization biofilm based systems performing autotrophic nitrogen removal using the comprehensive NDHA model

DEFF Research Database (Denmark)

Valverde Pérez, Borja; Ma, Yunjie; Morset, Martin

Completely autotrophic nitrogen removal (CANR) can be obtained in single stage biofilm-based bioreactors. However, their environmental footprint is compromised due to elevated N2O emissions. We developed novel spatially explicit biochemical process model of biofilm based CANR systems that predicts...

Nitrogen removal and nitrous oxide emission in surface flow constructed wetlands for treating sewage treatment plant effluent: Effect of C/N ratios.

Science.gov (United States)

Li, Ming; Wu, Haiming; Zhang, Jian; Ngo, Huu Hao; Guo, Wenshan; Kong, Qiang

2017-09-01

In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (N 2 O) emission, the effect of influent C/N ratios on nitrogen removal and N 2 O emission in surface flow constructed wetlands (SF CWs) for sewage treatment plant effluent treatment was investigated in this study. The results showed that nitrogen removal and N 2 O emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH 4 + -N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low N 2 O emission (8.2mg/m 2 /d) and the percentage of N 2 O-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how N 2 O fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancing the biological nitrogen fixation of leguminous crops ...

African Journals Online (AJOL)

Legumes have the ability to establish a symbiotic interaction with soil bacteria, collectively termed as rhizobia. These bacteria can enhance growth and development of associated crops by transferring atmospheric nitrogen into a form that is available for plant growth or by improving nutrient uptake through modulation of ...

Effectiveness of liquid organic-nitrogen fertilizer in enhancing ...

African Journals Online (AJOL)

The ever increasing price of nitrogenous (N) fertilizers coupled with the deleterious effects of imbalanced N fertilizers on the environment necessitates the enhancement of N use efficiency of plants. The objectives of this study were to: (1) Evaluate the uptake of selected nutrients due to application of liquid organic-N ...

Microwave plasma-assisted photoluminescence enhancement in nitrogen-doped ultrananocrystalline diamond film

Directory of Open Access Journals (Sweden)

Yu Lin Liu

2012-06-01

Full Text Available Optical properties and conductivity of nitrogen-doped ultrananocrystal diamond (UNCD films were investigated following treatment with low energy microwave plasma at room temperature. The plasma also generated vacancies in UNCD films and provided heat for mobilizing the vacancies to combine with the impurities, which formed the nitrogen-vacancy defect centers. The generated color centers were distributed uniformly in the samples. The conductivity of nitrogen-doped UNCD films treated by microwave plasma was found to decrease slightly due to the reduced grain boundaries. The photoluminescence emitted by the plasma treated nitrogen-doped UNCD films was enhanced significantly compared to the untreated films.

Internal nitrogen removal from sediments by the hybrid system of microbial fuel cells and submerged aquatic plants.

Directory of Open Access Journals (Sweden)

Peng Xu

Full Text Available Sediment internal nitrogen release is a significant pollution source in the overlying water of aquatic ecosystems. This study aims to remove internal nitrogen in sediment-water microcosms by coupling sediment microbial fuel cells (SMFCs with submerged aquatic plants. Twelve tanks including four treatments in triplicates were designed: open-circuit (SMFC-o, closed-circuit (SMFC-c, aquatic plants with open-circuit (P-SMFC-o and aquatic plants with closed-circuit (P-SMFC-c. The changes in the bio-electrochemical characteristics of the nitrogen levels in overlying water, pore water, sediments, and aquatic plants were documented to explain the migration and transformation pathways of internal nitrogen. The results showed that both electrogenesis and aquatic plants could facilitate the mineralization of organic nitrogen in sediments. In SMFC, electrogenesis promoted the release of ammonium from the pore water, followed by the accumulation of ammonium and nitrate in the overlying water. The increased redox potential of sediments due to electrogenesis also contributed to higher levels of nitrate in overlying water when nitrification in pore water was facilitated and denitrification at the sediment-water interface was inhibited. When the aquatic plants were introduced into the closed-circuit SMFC, the internal ammonium assimilation by aquatic plants was advanced by electrogenesis; nitrification in pore water and denitrification in sediments were also promoted. These processes might result in the maximum decrease of internal nitrogen with low nitrogen levels in the overlying water despite the lower power production. The P-SMFC-c reduced 8.1%, 16.2%, 24.7%, and 25.3% of internal total nitrogen compared to SMFC-o on the 55th, 82th, 136th, and 190th days, respectively. The smaller number of Nitrospira and the larger number of Bacillus and Pseudomonas on the anodes via high throughput sequencing may account for strong mineralization and denitrification in the

Phospholipase Dε enhances Braasca napus growth and seed production in response to nitrogen availability.

Science.gov (United States)

Lu, Shaoping; Yao, Shuaibing; Wang, Geliang; Guo, Liang; Zhou, Yongming; Hong, Yueyun; Wang, Xuemin

2016-03-01

Phospholipase D (PLD), which hydrolyses phospholipids to produce phosphatidic acid, has been implicated in plant response to macronutrient availability in Arabidopsis. This study investigated the effect of increased PLDε expression on nitrogen utilization in Brassica napus to explore the application of PLDε manipulation to crop improvement. In addition, changes in membrane lipid species in response to nitrogen availability were determined in the oil seed crop. Multiple PLDε over expression (PLDε-OE) lines displayed enhanced biomass accumulation under nitrogen-deficient and nitrogen-replete conditions. PLDε-OE plants in the field produced more seeds than wild-type plants but have no impact on seed oil content. Compared with wild-type plants, PLDε-OE plants were enhanced in nitrate transporter expression, uptake and reduction, whereas the activity of nitrite reductase was higher under nitrogen-depleted, but not at nitrogen-replete conditions. The level of nitrogen altered membrane glycerolipid metabolism, with greater impacts on young than mature leaves. The data indicate increased expression of PLDε has the potential to improve crop plant growth and production under nitrogen-depleted and nitrogen-replete conditions. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

Enhanced Nutrients Removal Using Reeds Straw as Carbon Source in a Laboratory Scale Constructed Wetland

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Tong Wang

2018-05-01

Full Text Available The low carbon/nitrogen (C/N ratio and high nitrate content characteristics of agricultural runoff restricted the nitrogen removal in constructed wetlands (CWs. To resolve such problems, the economically- and easily-obtained Phragmites Australis (reeds litters were applied and packed in the surface layer of a surface flow CW as external carbon sources. The results demonstrated that the introduction of the reeds straw increased the C concentration as a result of their decomposition during the CW operation, which will help the denitrification in the ensuing operation of an entire 148 days. The total nitrogen (TN and Chemical Oxygen Demand (COD ( in the effluent reached the peak level of 63.2 mg/L and 83 mg/L at the fourth and the second day, respectively. Subsequently, the pollutants in the CW that were filled with straw decreased rapidly and achieved a stable removal after 13 days of operation. Moreover, the present study showed that the N removal efficiency increased with the increase of the hydraulic retention time (HRT. Under the HRT of four days, the CW presented 74.1 ± 6%, 87.4 ± 6% and 56.0 ± 6% removal for TN, NO3-, and TP, respectively.

Temporary storage or permanent removal? The division of nitrogen between biotic assimilation and denitrification in stormwater biofiltration systems.

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Emily G I Payne

Full Text Available The long-term efficacy of stormwater treatment systems requires continuous pollutant removal without substantial re-release. Hence, the division of incoming pollutants between temporary and permanent removal pathways is fundamental. This is pertinent to nitrogen, a critical water body pollutant, which on a broad level may be assimilated by plants or microbes and temporarily stored, or transformed by bacteria to gaseous forms and permanently lost via denitrification. Biofiltration systems have demonstrated effective removal of nitrogen from urban stormwater runoff, but to date studies have been limited to a 'black-box' approach. The lack of understanding on internal nitrogen processes constrains future design and threatens the reliability of long-term system performance. While nitrogen processes have been thoroughly studied in other environments, including wastewater treatment wetlands, biofiltration systems differ fundamentally in design and the composition and hydrology of stormwater inflows, with intermittent inundation and prolonged dry periods. Two mesocosm experiments were conducted to investigate biofilter nitrogen processes using the stable isotope tracer 15NO3(- (nitrate over the course of one inflow event. The immediate partitioning of 15NO3(- between biotic assimilation and denitrification were investigated for a range of different inflow concentrations and plant species. Assimilation was the primary fate for NO3(- under typical stormwater concentrations (∼1-2 mg N/L, contributing an average 89-99% of 15NO3(- processing in biofilter columns containing the most effective plant species, while only 0-3% was denitrified and 0-8% remained in the pore water. Denitrification played a greater role for columns containing less effective species, processing up to 8% of 15NO3(-, and increased further with nitrate loading. This study uniquely applied isotope tracing to biofiltration systems and revealed the dominance of assimilation in stormwater

Respiration and nitrogen assimilation: targeting mitochondria-associated metabolism as a means to enhance nitrogen use efficiency.

Science.gov (United States)

Foyer, Christine H; Noctor, Graham; Hodges, Michael

2011-02-01

Considerable advances in our understanding of the control of mitochondrial metabolism and its interactions with nitrogen metabolism and associated carbon/nitrogen interactions have occurred in recent years, particularly highlighting important roles in cellular redox homeostasis. The tricarboxylic acid (TCA) cycle is a central metabolic hub for the interacting pathways of respiration, nitrogen assimilation, and photorespiration, with components that show considerable flexibility in relation to adaptations to the different functions of mitochondria in photosynthetic and non-photosynthetic cells. By comparison, the operation of the oxidative pentose phosphate pathway appears to represent a significant limitation to nitrogen assimilation in non-photosynthetic tissues. Valuable new insights have been gained concerning the roles of the different enzymes involved in the production of 2-oxoglutarate (2-OG) for ammonia assimilation, yielding an improved understanding of the crucial role of cellular energy balance as a broker of co-ordinate regulation. Taken together with new information on the mechanisms that co-ordinate the expression of genes involved in organellar functions, including energy metabolism, and the potential for exploiting the existing flexibility for NAD(P)H utilization in the respiratory electron transport chain to drive nitrogen assimilation, the evidence that mitochondrial metabolism and machinery are potential novel targets for the enhancement of nitrogen use efficiency (NUE) is explored.

Aerobic and heterotrophic nitrogen removal by Enterobacter cloacae CF-S27 with efficient utilization of hydroxylamine.

Science.gov (United States)

Padhi, Soumesh Kumar; Tripathy, Swetaleena; Mohanty, Sriprakash; Maiti, Nikhil Kumar

2017-05-01

Heterotrophic bacterium, Enterobacter cloacae CF-S27 exhibited simultaneous nitrification and aerobic denitrification in presence of high concentration of hydroxylamine. With the initial nitrogen concentration of 100mgL -1 h -1 , ammonium, nitrate and nitrite removal efficiencies were 81%, 99.9% and 92.8%, while the corresponding maximum removal rates reached as high as 11.6, 15.1 and 11.2mgL -1 h -1 respectively. Quantitative amplification by real time PCR and enzyme assay demonstrated that hydroxylamine reductase gene (hao) is actively involved in hetrotrophic nitrification and aerobic denitrification process of Enterobacter cloacae CF-S27. PCR primers were designed targeting amplification of hao gene from diversified environmental soil DNA. The strain Enterobacter cloacae CF-S27 significantly maintained the undetectable amount of dissolved nitrogen throughout 60days of zero water exchange fish culture experiment in domestic wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen Removal in a Full-Scale Domestic Wastewater Treatment Plant with Activated Sludge and Trickling Filter

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Davood Nourmohammadi

2013-01-01

Full Text Available During the last decade, more stringent effluent requirements concerning the nutrients effluent values have been imposed by legislation and social concern. In this study, efficiency of total nitrogen removal in activated sludge and trickling filter processes (AS/TF was investigated in Tehran North wastewater treatment plant. Biological system in this site was included, anoxic selector tank, aeration tank, final sedimentation, and trickling filter. A part of treated wastewater before chlorination was mixed with supernatant of dewatered sludge and fed to the trickling filter. Supernatant of dewatered sludge with high concentration of NH4-N was diluted by treated wastewater to provide complete nitrification in trickling filter Produced nitrate in trickling filter was arrived to the anoxic tank and converted to nitrogen gas by denitrification. According to the study result, low concentration of organic carbone and high concentration of NH4-N led to nitrification in TF, then nitrate denitrification to nitrogen gas occurred in selector area. NH4-N concentration decreased from 26.8 mg/L to 0.29 mg/L in TF, and NO3-N concentration increased from 8.8 mg/L to 27 mg/L in TF. Consequently, the total nitrogen decreased approximately to 50% in biological process. This efficiency has been observed in returned flow around 24% from final sedimentation into TF. It was concluded that, in comparison with biological nutrient removal processes, this process is very efficient and simple.

Nitrogen and COD Removal from Septic Tank Wastewater in Subsurface Flow Constructed Wetlands: Plants Effects.

Science.gov (United States)

Collison, R S; Grismer, M E

2015-11-01

We evaluated subsurface flow (SSF) constructed wetland treatment performance with respect to organics (COD) and nitrogen (ammonium and nitrate) removal from domestic (septic tank) wastewater as affected by the presence of plants, substrate "rock" cation exchange capacity (CEC), laboratory versus field conditions and use of synthetic as compared to actual domestic wastewater. This article considers the effects of plants on constructed wetland treatment in the field. Each constructed wetland system was comprised of two beds (2.6 m long by 0.28 m wide and deep filled with ~18 mm crushed lava rock) separated by an aeration tank connected in series. The lava rock had a porosity of ~47% and a CEC of 4 meq/100 gm. One pair of constructed wetland systems was planted with cattails in May 2008, while an adjacent pair of systems remained un-planted. Collected septic tank or synthesized wastewater was allowed to gravity feed each constructed wetland system and effluent samples were regularly collected and tested for COD and nitrogen species during four time periods spanning November 2008 through June 2009. These effluent concentrations were tested for statistical differences at the 95% level for individual time periods as well as the overall 6-month period. Organics removal from domestic wastewater was 78.8% and 76.1% in the planted and un-planted constructed wetland systems, respectively, while ammonium removal was 94.5% and 90.2%, respectively. Similarly, organics removal from the synthetic wastewater of equivalent strength was 88.8% and 90.1% for planted and un-planted constructed wetland systems, respectively, while ammonium removal was 96.9% and 97.3%, respectively.

Innovative process scheme for removal of organic matter, phosphorus and nitrogen from pig manure

DEFF Research Database (Denmark)

Karakashev, Dimitar Borisov; Schmidt, Jens Ejbye; Angelidaki, Irini

2008-01-01

blanket (UASB) reactor, partial oxidation), nitrogen (oxygen-limited autotrophic nitrification-denitrification, OLAND) and phosphorus (phosphorus removal by precipitation as struvite, PRS) from pig manure were tested. Results obtained showed that microfiltration was unsuitable for pig manure treatment....... PRS treated effluent was negatively affecting the further processing of the pig manure in UASB, and was therefore not included in the final process flow scheme. In a final scheme (PIGMAN concept) combination of the following successive process steps was used: thermophilic anaerobic digestion...... with sequential separation by decanter centrifuge, post-digestion in UASB reactor, partial oxidation and finally OLAND process. This combination resulted in reduction of the total organic, nitrogen and phosphorus contents by 96%, 88%, and 81%, respectively....

High temperature fluidized bed zero valent iron process for flue gas nitrogen monoxide removal

International Nuclear Information System (INIS)

Cheng, C.Y.; Chen, S.S.; Tang, C.H.; Chang, Y.M.; Cheng, H.H.; Liu, H.L.

2008-01-01

Nitrogen oxides (NO x ) are generated from a variety of sources, and are critical components of photochemical smog. Zero valent iron (ZVI) has been used to remove NO x in a number of studies. The ZVI process requires no extra chemicals or catalysts. In this study, a fluidized ZVI process for removing NO x from flue gases was proposed. The study examined the effects of temperature, ZVI dosage and influent NO concentrations, and observed the kinetic effects between the fluidized ZVI and NO x . A life cycle analysis of the process was also provided. The parametric analysis was conducted in a series of column studies using a continuous emissions monitoring system. Minimum fluidization velocity equations were provided, and the drag coefficient was determined. Capacities of ZVI for NO removal at different temperatures were calculated. Results of the study suggested that temperature, influent concentrations, and flow rates all influenced kinetic coefficients. Different temperatures resulted in different rates of NO removal. It was concluded that between 673 K and 773 K, almost complete NO removals were achieved. 14 refs., 2 tabs., 9 figs

Potential coupling effects of ammonia-oxidizing and anaerobic ammonium-oxidizing bacteria on completely autotrophic nitrogen removal over nitrite biofilm formation induced by the second messenger cyclic diguanylate.

Science.gov (United States)

Wang, Chao; Liu, Sitong; Xu, Xiaochen; Zhao, Chuanqi; Yang, Fenglin; Wang, Dong

2017-05-01

The objective of this study was to investigate the influence of extracellular polymeric substance (EPS) on the coupling effects between ammonia-oxidizing bacteria (AOB) and anaerobic ammonium-oxidizing (anammox) bacteria for the completely autotrophic nitrogen removal over nitrite (CANON) biofilm formation in a moving bed biofilm reactor (MBBR). Analysis of the quantity of EPS and cyclic diguanylate (c-di-GMP) confirmed that the contents of polysaccharides and c-di-GMP were correlated in the AOB sludge, anammox sludge, and CANON biofilm. The anammox sludge secreted more EPS (especially polysaccharides) than AOB with a markedly higher c-di-GMP content, which could be used by the bacteria to regulate the synthesis of exopolysaccharides that are ultimately used as a fixation matrix, for the adhesion of biomass. Indeed, increased intracellular c-di-GMP concentrations in the anammox sludge enhanced the regulation of polysaccharides to promote the adhesion of AOB and formation of the CANON biofilm. Overall, the results of this study provide new comprehensive information regarding the coupling effects of AOB and anammox bacteria for the nitrogen removal process.

Reducing nitrogen export from the corn belt to the Gulf of Mexico: agricultural strategies for remediating hypoxia

Science.gov (United States)

McLellan, Eileen; Robertson, Dale M.; Schilling, Keith; Tomer, Mark; Kostel, Jill; Smith, Douglas G.; King, Kevin

2015-01-01

SPAtially Referenced Regression on Watershed models developed for the Upper Midwest were used to help evaluate the nitrogen-load reductions likely to be achieved by a variety of agricultural conservation practices in the Upper Mississippi-Ohio River Basin (UMORB) and to compare these reductions to the 45% nitrogen-load reduction proposed to remediate hypoxia in the Gulf of Mexico (GoM). Our results indicate that nitrogen-management practices (improved fertilizer management and cover crops) fall short of achieving this goal, even if adopted on all cropland in the region. The goal of a 45% decrease in loads to the GoM can only be achieved through the coupling of nitrogen-management practices with innovative nitrogen-removal practices such as tile-drainage treatment wetlands, drainage–ditch enhancements, stream-channel restoration, and floodplain reconnection. Combining nitrogen-management practices with nitrogen-removal practices can dramatically reduce nutrient export from agricultural landscapes while minimizing impacts to agricultural production. With this approach, it may be possible to meet the 45% nutrient reduction goal while converting less than 1% of cropland in the UMORB to nitrogen-removal practices. Conservationists, policy makers, and agricultural producers seeking a workable strategy to reduce nitrogen export from the Corn Belt will need to consider a combination of nitrogen-management practices at the field scale and diverse nitrogen-removal practices at the landscape scale.

Efficacy of reactive mineral-based sorbents for phosphate, bacteria, nitrogen and TOC removal--column experiment in recirculation batch mode.

Science.gov (United States)

Nilsson, Charlotte; Lakshmanan, Ramnath; Renman, Gunno; Rajarao, Gunaratna Kuttuva

2013-09-15

Two mineral-based materials (Polonite and Sorbulite) intended for filter wells in on-site wastewater treatment were compared in terms of removal of phosphate (PO4-P), total inorganic nitrogen (TIN), total organic carbon (TOC) and faecal indicator bacteria (Escherichia coli and Enterococci). Using an innovative, recirculating system, septic tank effluent was pumped at a hydraulic loading rate of 3000 L m(2) d(-1) into triplicate bench-scale columns of each material over a 90-day period. The results showed that Polonite performed better with respect to removal of PO4-P, retaining on average 80% compared with 75% in Sorbulite. This difference was attributed to higher CaO content in Polonite and its faster dissolution. Polonite also performed better in terms of removal of bacteria because of its higher pH value. The total average reduction in E. coli was 60% in Polonite and 45% in Sorbulite, while for Enterococci the corresponding value was 56% in Polonite and 34% in Sorbulite. Sorbulite removed TIN more effectively, with a removal rate of 23%, while Polonite removed 11% of TIN, as well as TOC. Organic matter (measured as TOC) was accumulated in the filter materials but was also released periodically. The results showed that Sorbulite could meet the demand in removing phosphate and nitrogen with reduced microbial release from the wastewater treatment process. Copyright © 2013 Elsevier Ltd. All rights reserved.

Use of bioreactor landfill for nitrogen removal to enhance methane production through ex situ simultaneous nitrification-denitrification and in situ denitrification.

Science.gov (United States)

Sun, Xiaojie; Zhang, Hongxia; Cheng, Zhaowen

2017-08-01

High concentrations of nitrate-nitrogen (NO 3 - -N) derived from ex situ nitrification phase can inhibit methane production during ex situ nitrification and in situ denitrification bioreactor landfill. A combined process comprised of ex situ simultaneous nitrification-denitrification (SND) in an aged refuse bioreactor (ARB) and in situ denitrification in a fresh refuse bioreactor (FRB) was conducted to reduce the negative effect of high concentrationsof NO 3 - -N. Ex situ SND can be achieved because NO 3 - -N concentration can be reduced and the removal rate of ammonium-nitrogen (NH 4 + -N) remains largely unchanged when the ventilation rate of ARB-A2 is controlled. The average NO 3 - -N concentrations of effluent were 470mg/L in ex situ nitrification ARB-A1 and 186mg/L in ex situ SND ARB-A2. The average NH 4 + -N removal rates of ARB-A1 and ARB-A2 were 98% and 94%, respectively. Based on the experimental data from week 4 to week 30, it is predicted that NH 4 + -N concentration in FRB-F1 of the ex situ nitrification and in situ denitrification process would reach 25mg/L after 63weeks, and about 40weeks for the FRB-F2 of ex situ SND and in situ denitrification process . Ex situ SND and in situ denitrification process can improve themethane production of FRB-F2. The lag phase time of methane production for the FRB-F2 was 11weeks. This phase was significantly shorter than the 15-week phases of FRB-F1 in ex situ nitrification and in situ denitrification process. A seven-week stabilizationphase was required to increase methane content from 5% to 50% for FRB-F2. Methane content in FRB-F1 did not reach 50% but reached the 45% peak after 20weeks. Copyright © 2017 Elsevier Ltd. All rights reserved.

Plasma-assisted nitrogen doping of VACNTs for efficiently enhancing the supercapacitor performance

Energy Technology Data Exchange (ETDEWEB)

Mashayekhi, Alireza; Hosseini, Seyed Mahmoud [University of Tehran, Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of); Hassanpour Amiri, Morteza; Namdar, Naser [University of Tehran, Thin Film and Nano-electronics Laboratory, Nano-electronics Centre of Excellence, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of); Sanaee, Zeinab, E-mail: z.sanaee@ut.ac.ir [University of Tehran, Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of)

2016-06-15

Nitrogen doping of vertically aligned carbon nanotubes (VACNTs) using plasma-enhanced chemical vapour deposition has been investigated to improve the supercapacitance performance of CNTs. Incorporating electrochemical measurements on the open-ended nitrogen-doped CNTs, showed the achievement of 6 times improvement in the capacitance value. For nitrogen-doped CNTs on silicon substrate, specific capacitance of 60 F g{sup −1} was obtained in 0.5 M KCl solution, with capacity retention ratio above 90 % after cycled at 0.1 A g{sup −1} for 5000 cycles. Using this sample, a symmetric supercapacitance was fabricated which showed the power density of 37.5 kW kg{sup −1}. The facile fabrication approach and its excellent capacitance improvement, propose it as an efficient technique for enhancing the supercapacitance performance of the carbon-based electrodes.

Outcompeting nitrite-oxidizing bacteria in single-stage nitrogen removal in sewage treatment plants: a model-based study.

Science.gov (United States)

Pérez, Julio; Lotti, Tommaso; Kleerebezem, Robbert; Picioreanu, Cristian; van Loosdrecht, Mark C M

2014-12-01

This model-based study investigated the mechanisms and operational window for efficient repression of nitrite oxidizing bacteria (NOB) in an autotrophic nitrogen removal process. The operation of a continuous single-stage granular sludge process was simulated for nitrogen removal from pretreated sewage at 10 °C. The effects of the residual ammonium concentration were explicitly analyzed with the model. Competition for oxygen between ammonia-oxidizing bacteria (AOB) and NOB was found to be essential for NOB repression even when the suppression of nitrite oxidation is assisted by nitrite reduction by anammox (AMX). The nitrite half-saturation coefficient of NOB and AMX proved non-sensitive for the model output. The maximum specific growth rate of AMX bacteria proved a sensitive process parameter, because higher rates would provide a competitive advantage for AMX. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simultaneous improvement of waste gas purification and nitrogen removal using a novel aerated vertical flow constructed wetland.

Science.gov (United States)

Zhang, Xinwen; Hu, Zhen; Ngo, Huu Hao; Zhang, Jian; Guo, Wenshan; Liang, Shuang; Xie, Huijun

2018-03-01

Insufficient oxygen supply is identified as one of the major factors limiting organic pollutant and nitrogen (N) removal in constructed wetlands (CWs). This study designed a novel aerated vertical flow constructed wetland (VFCW) using waste gas from biological wastewater treatment systems to improve pollutant removal in CWs, its potential in purifying waste gas was also identified. Compared with unaerated VFCW, the introduction of waste gas significantly improved NH 4 + -N and TN removal efficiencies by 128.48 ± 3.13% and 59.09 ± 2.26%, respectively. Furthermore, the waste gas ingredients, including H 2 S, NH 3 , greenhouse gas (N 2 O) and microbial aerosols, were remarkably reduced after passing through the VFCW. The removal efficiencies of H 2 S, NH 3 and N 2 O were 77.78 ± 3.46%, 52.17 ± 2.53%, and 87.40 ± 3.89%, respectively. In addition, the bacterial and fungal aerosols in waste gas were effectively removed with removal efficiencies of 42.72 ± 3.21% and 47.89 ± 2.82%, respectively. Microbial analysis results revealed that the high microbial community abundance in the VFCW, caused by the introduction of waste gas from the sequencing batch reactor (SBR), led to its optimized nitrogen transformation processes. These results suggested that the VFCW intermittently aerated with waste gas may have potential application for purifying wastewater treatment plant effluent and waste gas, simultaneously. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nitrogen removal and nitrate leaching for forage systems receiving dairy effluent.

Science.gov (United States)

Woodard, Kenneth R; French, Edwin C; Sweat, Lewin A; Graetz, Donald A; Sollenberger, Lynn E; Macoon, Bisoondat; Portier, Kenneth M; Wade, Brett L; Rymph, Stuart J; Prine, Gordon M; Van Horn, Harold H

2002-01-01

Florida dairies need year-round forage systems that prevent loss of N to ground water from waste effluent sprayfields. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentrations in soil water below the rooting zone for two forage systems during four 12-mo cycles (1996-2000). Soil in the sprayfield is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzipsamment). Over four cycles, average loading rates of effluent N were 500, 690, and 910 kg ha(-1) per cycle. Nitrogen removed by the bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (BR) during the first three cycles was 465 kg ha(-1) per cycle for the low loading rate, 528 kg ha(-1) for the medium rate, and 585 kg ha(-1) for the high. For the corn (Zea mays L.)-forage sorghum [Sorghum bicolor (L.) Moench]-rye system (CSR), N removals were 320 kg ha(-1) per cycle for the low rate, 327 kg ha(-1) for the medium, and 378 kg ha(-1) for the high. The higher N removals for BR were attributed to higher N concentration in bermudagrass (18.1-24.2 g kg(-1)) than in corn and forage sorghum (10.3-14.7 g kg(-1)). Dry matter yield declined in the fourth cycle for bermudagrass but N removal continued to be higher for BR than CSR. The BR system was much more effective at preventing NO3(-)-N leaching. For CSR, NO3(-)-N levels in soil water (1.5 m below surface) increased steeply during the period between the harvest of one forage and canopy dosure of the next. Overall, the BR system was better than CSR at removing N from the soil and maintaining low NO3(-)-N concentrations below the rooting zone.

Enhanced nitrogen removal in single-chamber microbial fuel cells with increased gas diffusion areas

KAUST Repository

Yan, Hengjing; Regan, John M.

2012-01-01

significantly increased the ammonia and COD removal rates (by up to 115% and 39%), ammonia removal efficiency (by up to 134%), the cell voltage and cathode potentials, and the power densities (by a factor of approximately 2). When the COD/N ratio was lowered

Potential of duckweed (Lemna minor) for removal of nitrogen and phosphorus from water under salt stress.

Science.gov (United States)

Liu, Chunguang; Dai, Zheng; Sun, Hongwen

2017-02-01

Duckweed plays a major role in the removal of nitrogen (N) and phosphorus (P) from water. To determine the effect of salt stress on the removal of N and P by duckweed, we cultured Lemna minor, a common species of duckweed, in N and P-rich water with NaCl concentrations ranging from 0 to 100 mM for 24 h and 72 h, respectively. The results show that the removal capacity of duckweed for N and P was reduced by salt stress. Higher salt stress with longer cultivation period exerts more injury to duckweed and greater inhibition of N and P removal. Severe salt stress (100 mM NaCl) induced duckweed to release N and P and even resulted in negative removal efficiencies. The results indicate that L. minor should be used to remove N and P from water with salinities below 75 mM NaCl, or equivalent salt stress. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nitrogen removal in a single-chamber microbial fuel cell with nitrifying biofilm enriched at the air cathode

KAUST Repository

Yan, Hengjing; Saito, Tomonori; Regan, John M.

2012-01-01

biofilm MFCs had lower Coulombic efficiencies (up to 27%) than the control reactor (up to 36%). The maximum total nitrogen removal efficiency reached 93.9% for MFCs with the DEA binder. The DEA binder accelerated nitrifier biofilm enrichment on the cathode

Abnormal contrast enhancement after the removal of meningioma

Energy Technology Data Exchange (ETDEWEB)

Soutsu, M; Hashimoto, T; Yamaguchi, Y; Sekino, H; Nakamura, N [Jikei Univ., Tokyo (Japan). School of Medicine

1980-12-01

Since the introduction of Computerized Tomography (CT) in August, 1976, we have had experience with 20 patients with meningioma. In 10 patients out of the 20, the tumors were removed totally and examined by contrast-enhanced CT pre- and postoperatively. In spite of the total removal of the tumor, however, 5 patients showed an unexpected abnormal enhancement at the operated site after the infusion of a contrast material. These changes were relatively intense, so it was suspected that there were residual tumors. Comparing these 5 cases with the remaining 5 that had no postoperative enhancement, the former cases were shown by operative and angiographical findings to have more adhesion and connecting vessels between tumor and cortex. Since such a postoperative abnormal enhancement is seen along the corticotomy or retracted area after operations for and aneurysm or another lesion, damaged brain tissue was though to be the probable reason for this enhancement. Moreover, the circulatory change caused by cutting the connecting vessels between tumor and cortex was considered to be another reason for the enhancement. This mechanism was also considered to be one reason for the post-meningioma syndrome by El-Banhawy. These postoperative enhancements decreased in density and became obscure within 4 or 8 weeks. Any reappearance of such changes after that period should be examined, carefully to determine whether or not it marks a recurrent tumor.

Treatment of Alkaline Stripped Effluent in Aerated Constructed Wetlands: Feasibility Evaluation and Performance Enhancement

Directory of Open Access Journals (Sweden)

Keli He

2016-09-01

Full Text Available Ammonium stripping has gained increasing interest for nitrogen recovery in anaerobically digested effluents. However, the stripped effluents often still do not meet discharge standards, having high pH and residual pollutants. Constructed wetlands (CWs are an easy to operate ecosystem and have a long history of application in treatment of wastewaters with extreme pH, such as acid mine drainage. However, knowledge of the mechanistic details involved in the use of CWs to treat high alkaline drainage, such as stripped effluent, is insufficient. This study explored the feasibility and effectiveness of using three sub-surface horizontal flow CWs to treat high alkaline stripped effluent (pH > 10. Two intensification strategies—intermittent aeration and effluent recirculation—were evaluated to enhance nitrogen depuration performance. The results show that the treatment of alkaline stripped effluent is feasible due to the high buffering capacity of the wetlands. Effluent recirculation combined with intermittent artificial aeration improves nitrogen removal, with 71% total nitrogen (TN removal. Ammonia volatilization from the surface of the wetlands in high alkaline conditions only contributed to 3% of the total removed ammonium. The microbial abundance and activity had significant diversity for the various enhancement strategies used in the constructed wetland systems. Anammox is an important process for nitrogen removal in CWs treating alkaline stripped effluent, and possible enhancements of this process should be investigated further.

Control of SHARON reactor for autotrophic nitrogen removal in two-reactor configuration

DEFF Research Database (Denmark)

Valverde Perez, Borja; Mauricio Iglesias, Miguel; Sin, Gürkan

2012-01-01

With the perspective of investigating a suitable control design for autotrophic nitrogen removal, this work explores the control design for a SHARON reactor. With this aim, a full model is developed, including the pH dependency, in order to simulate the reactor and determine the optimal operating...... conditions. Then, the screening of controlled variables and pairing is carried out by an assessment of the effect of the disturbances based on the closed loop disturbance gain plots. Two controlled structures are obtained and benchmarked by their capacity to reject the disturbances before the Anammox reactor....

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...... continuous aeration, could remove more than 5.5 g N/m2/day (at loads up to 8 g N/m2/day) by controlled variation of sequential aeration regimes. Daily averaged ratios of the surficial loads of O2 (oxygen) to NH4+ (ammonium) (LO2/LNH4) were close to 1.73 at this optimum. Real-time quantitative PCR based on 16...

Microbial removal of fixed nitrogen in an oceanic oxygen minimum zone

DEFF Research Database (Denmark)

Dalsgaard, Tage; Thamdrup, Bo; Revsbech, Niels Peter

We quantified the removal of fixed nitrogen as N2 production by anammox and N2 and N2O production by denitrification over a distance of 1900 km along the coast of Chile and Peru, using short-term incubations with 15N-labeled substrates. The eastern tropical South Pacific (ETSP) holds an oxygen...... and that denitrification is needed for the mineralization of organic matter and production of NH4+ for anammox. Our data from frequent sampling along a 1900 km cruise track parallel to the coast of Chile and Peru show that denitrification does indeed occur, but less frequent and at higher rates than anammox...

Immobilized periphytic cyanobacteria for removal of nitrogenous compounds and phosphorus from shrimp farm wastewater

OpenAIRE

BANERJEE, SANJOY; KHATOON, HELENA; SHARIFF, MOHAMED; YUSOFF, FATIMAH

2015-01-01

Cyanobacteria can be used to remove nitrogenous compounds from wastewater, but a major bottleneck in the process is the separation of cyanobacterial biomass from the treated water discharge, which may cause eutrophication. The current study assessed the suitability of three periphytic cyanobacteria (Geitlerinema sp., Gloeotrichia sp., and Lyngbya sp.) isolated from shrimp ponds. These cyanobacteria were immobilized by self-adhesion to polyvinyl chloride sheets, forming mats, and were screened...

A fuzzy-logic based diagnosis and control of a reactor performing complete autotrophic nitrogen removal

DEFF Research Database (Denmark)

Mauricio Iglesias, Miguel; Vangsgaard, Anna Katrine; Gernaey, Krist

2013-01-01

Diagnosis and control modules based on fuzzy set theory were tested for novel bioreactor monitoring and control. Two independent modules were used jointly to carry out first the diagnosis of the state of the system and then use transfer this information to control the reactor. The separation in d...... autotrophic nitrogen removal process. The whole module is evaluated by dynamic simulation....

Nitrogen removal process optimization in New York City WPCPS: a case study of Wards Island WPCP.

Science.gov (United States)

Ramalingam, K; Fillos, J; Musabyimana, M; Deur, A; Beckmann, K

2009-01-01

The New York City Department of Environmental Protection has been engaged in a continuous process to develop a nitrogen removal program to reduce the nitrogen mass discharge from its water pollution control plants, (WPCPs), from 49,158 kg/d to 20,105 kg/d by the year 2017 as recommended by the Long Island Sound Study. As part of the process, a comprehensive research effort was undertaken involving bench, pilot and full scale studies to identify the most effective way to upgrade and optimize the existing WPCPs. Aeration tank 13 (AT-13) at the Wards Island WPCP was particularly attractive as a full-scale research facility because its aeration tank with its dedicated final settling tanks and RAS pumps could be isolated from the remaining treatment facilities. The nitrogen removal performance of AT-13, which, at the time, was operated as a "basic step feed BNR Facility", was evaluated and concurrently nitrification kinetic parameters were measured using in-situ bench scale experiments. Additional bench scale experiments provided denitrification rates using different sources of carbon and measurement of the maximum specific growth rate of nitrifying bacteria. The combined findings were then used to upgrade AT-13 to a "full" BNR facility with carbon and alkalinity addition. This paper will focus on the combined bench and full scale results that were the basis for the consequent upgrade.

Effect of Nitrogen Oxides on Elemental Mercury Removal by Nanosized Mineral Sulfide.

Science.gov (United States)

Li, Hailong; Zhu, Lei; Wang, Jun; Li, Liqing; Lee, Po-Heng; Feng, Yong; Shih, Kaimin

2017-08-01

Because of its large surface area, nanosized zinc sulfide (Nano-ZnS) has been demonstrated in a previous study to be efficient for removal of elemental mercury (Hg 0 ) from coal combustion flue gas. The excellent mercury adsorption performance of Nano-ZnS was found to be insusceptible to water vapor, sulfur dioxide, and hydrogen chloride. However, nitrogen oxides (NO X ) apparently inhibited mercury removal by Nano-ZnS; this finding was unlike those of many studies on the promotional effect of NO X on Hg 0 removal by other sorbents. The negative effect of NO X on Hg 0 adsorption over Nano-ZnS was systematically investigated in this study. Two mechanisms were identified as primarily responsible for the inhibitive effect of NO X on Hg 0 adsorption over Nano-ZnS: (1) active sulfur sites on Nano-ZnS were oxidized to inactive sulfate by NO X ; and (2) the chemisorbed mercury, i.e., HgS, was reduced to Hg 0 by NO X . This new insight into the role of NO X in Hg 0 adsorption over Nano-ZnS can help to optimize operating conditions, maximize Hg 0 adsorption, and facilitate the application of Nano-ZnS as a superior alternative to activated carbon for Hg 0 removal using existing particulate matter control devices in power plants.

Enhanced DOC removal using anion and cation ion exchange resins.

Science.gov (United States)

Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

2016-01-01

Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. Published by Elsevier Ltd.

Removal of selected nitrogenous heterocyclic compounds in biologically pretreated coal gasification wastewater (BPCGW) using the catalytic ozonation process combined with the two-stage membrane bioreactor (MBR).

Science.gov (United States)

Zhu, Hao; Han, Yuxing; Ma, Wencheng; Han, Hongjun; Ma, Weiwei

2017-12-01

Three identical anoxic-aerobic membrane bioreactors (MBRs) were operated in parallel for 300 consecutive days for raw (R 1 ), ozonated (R 2 ) and catalytic ozonated (R 3 ) biologically pretreated coal gasification wastewater (BPCGW) treatment. The results demonstrated that catalytic ozonation process (COP) applied asa pretreatment remarkably improved the performance of the unsatisfactory single MBR. The overall removal efficiencies of COD, NH 3 -N and TN in R 3 were 92.7%, 95.6% and 80.6%, respectively. In addition, typical nitrogenous heterocyclic compounds (NHCs) of quinoline, pyridine and indole were completely removed in the integrated process. Moreover, COP could alter sludge properties and reshape microbial community structure, thus delaying the occurrence of membrane fouling. Finally, the total cost for this integrated process was estimated to be lower than that of single MBR. The results of this study suggest that COP is a good option to enhance pollutants removal and alleviate membrane fouling in the MBR for BPCGW treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

A modified UCT method for biological nutrient removal: configuration and performance.

Science.gov (United States)

Vaiopoulou, E; Aivasidis, A

2008-07-01

A pilot-scale prototype activated sludge system is presented, which combines both, the idea of University of Cape Town (UCT) concept and the step denitrification cascade for removal of carbon, nitrogen and phosphorus. The experimental set-up consists of an anaerobic selector and stepwise feeding in subsequent three identical pairs of anoxic and oxic tanks. Raw wastewater with influent flow rates ranging between 48 and 168 l d(-1) was fed to the unit at hydraulic residence times (HRTs) of 5-18 h and was distributed at percentages of 60/25/15%, 40/30/30% and 25/40/35% to the anaerobic selector, 2nd and 3rd anoxic tanks, respectively (influent flow distribution before the anaerobic selector). The results for the entire experimental period showed high removal efficiencies of organic matter of 89% as total chemical oxygen demand removal and 95% removal for biochemical oxygen demand, 90% removal of total Kjeldahl nitrogen and total nitrogen removal through denitrification of 73%, mean phosphorus removal of 67%, as well as excellent settleability. The highest removal efficiency and the optimum performance were recorded at an HRT of about 9h and influent flow rate of 96 l d(-1), in which 60% is distributed to the anaerobic selector, 25% to the second anoxic tank and 15% to the last anoxic tank. Consequently, the plant configuration enhanced removal efficiency, optimized performance, saved energy, formed good settling sludge and provided operational assurance.

Biological nitrogen removal from sewage via anammox: Recent advances.

Science.gov (United States)

Ma, Bin; Wang, Shanyun; Cao, Shenbin; Miao, Yuanyuan; Jia, Fangxu; Du, Rui; Peng, Yongzhen

2016-01-01

Biological nitrogen removal from sewage via anammox is a promising and feasible technology to make sewage treatment energy-neutral or energy-positive. Good retention of anammox bacteria is the premise of achieving sewage treatment via anammox. Therefore the anammox metabolism and its factors were critically reviewed so as to form biofilm/granules for retaining anammox bacteria. A stable supply of nitrite for anammox bacteria is a real bottleneck for applying anammox in sewage treatment. Nitritation and partial-denitrification are two promising methods of offering nitrite. As such, the strategies for achieving nitritation in sewage treatment were summarized by reviewing the factors affecting nitrite oxidation bacteria growth. Meanwhile, the methods of achieving partial-denitrification have been developed through understanding the microorganisms related with nitrite accumulation and their factors. Furthermore, two cases of applying anammox in the mainstream sewage treatment plants were documented. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biosurfactant-enhanced removal of phenanthrene from soil

NARCIS (Netherlands)

Noordman, WH; Ji, W; Brusseau, ML; Janssen, DB

1997-01-01

The possibility to use rhamnolipid biosurfactants for enhancing the elution of phenanthrene from a soil column was tested. Removal of 90% of the phenanthrene was achieved in a 3.6-fold shorter time period when the feed solution contained 500 mg/L rhamnolipid compared to treatment without

Extending the benchmark simulation model no2 with processes for nitrous oxide production and side-stream nitrogen removal

DEFF Research Database (Denmark)

Boiocchi, Riccardo; Sin, Gürkan; Gernaey, Krist V.

2015-01-01

In this work the Benchmark Simulation Model No.2 is extended with processes for nitrous oxide production and for side-stream partial nitritation/Anammox (PN/A) treatment. For these extensions the Activated Sludge Model for Greenhouse gases No.1 was used to describe the main waterline, whereas...... the Complete Autotrophic Nitrogen Removal (CANR) model was used to describe the side-stream (PN/A) treatment. Comprehensive simulations were performed to assess the extended model. Steady-state simulation results revealed the following: (i) the implementation of a continuous CANR side-stream reactor has...... increased the total nitrogen removal by 10%; (ii) reduced the aeration demand by 16% compared to the base case, and (iii) the activity of ammonia-oxidizing bacteria is most influencing nitrous oxide emissions. The extended model provides a simulation platform to generate, test and compare novel control...

CO{sub 2} removal potential of carbons prepared by co-pyrolysis of sugar and nitrogen containing compounds

Energy Technology Data Exchange (ETDEWEB)

Arenillas, A.; Drage, T.C.; Smith, K.; Snape, C.E. [University of Nottingham, Fuel Science Group, School of Chemical, Environmental and Mining Engineering, University Park, Nottingham NG7 2RD (United Kingdom)

2005-08-15

The nitrogen enrichment of active carbons is reported to be effective in enhancing the specific adsorbate-adsorbent interactions for CO{sub 2}. In this work, nitrogen-enriched carbons were prepared by co-pyrolysis of sugar and a series of nitrogen compounds with different nitrogen functionalities. The results show that although the amount of nitrogen incorporated to the final adsorbent is important, the N-functionality seems to be more relevant for increasing CO{sub 2} uptake. Thus, the adsorbent obtained from urea co-pyrolysis presents the highest nitrogen content but the lowest CO{sub 2} adsorption capacity. However, the adsorbent obtained from carbazole co-pyrolysis, despite the lower amount of N incorporated, shows high CO{sub 2} uptake, up to 9wt.%, probably because the presence of more basic functionalities as determined by XPS analysis.

Biological nitrogen removal using soil columns for the reuse of reclaimed water: Performance and microbial community analysis.

Science.gov (United States)

Sun, Jiaji; Chen, Lei; Rene, Eldon R; Hu, Qian; Ma, Weifang; Shen, Zhenyao

2018-07-01

The main aim of this study was to remove nitrogen compounds from reclaimed water and reuse the water in semi-arid riverine lake systems. In order to assess the nitrogen removal efficiencies in different natural environments, laboratory scale column experiments were performed using sterilized soil (SS), silty clay (SC), soil with submerged plant (SSP) and biochar amendment soil (BCS). The initial concentration of NO 3 - -N and the flow rate was maintained constant at 15 mg L -1 and 0.6 ± 0.1 m d -1 , respectively. Among the tested columns, both SSP and BCS were able to achieve NO 3 - -N levels <0.2 mg L -1 in the treated reclaimed water. The results from bacterial community structure analysis, using 454 pyrosequencing of 16s rRNA genes, showed that the dominant denitrifier was Bacillus at the genera level. Copyright © 2018 Elsevier Ltd. All rights reserved.

Artificial intelligence models for predicting the performance of biological wastewater treatment plant in the removal of Kjeldahl Nitrogen from wastewater

Science.gov (United States)

Manu, D. S.; Thalla, Arun Kumar

2017-11-01

The current work demonstrates the support vector machine (SVM) and adaptive neuro-fuzzy inference system (ANFIS) modeling to assess the removal efficiency of Kjeldahl Nitrogen of a full-scale aerobic biological wastewater treatment plant. The influent variables such as pH, chemical oxygen demand, total solids (TS), free ammonia, ammonia nitrogen and Kjeldahl Nitrogen are used as input variables during modeling. Model development focused on postulating an adaptive, functional, real-time and alternative approach for modeling the removal efficiency of Kjeldahl Nitrogen. The input variables used for modeling were daily time series data recorded at wastewater treatment plant (WWTP) located in Mangalore during the period June 2014-September 2014. The performance of ANFIS model developed using Gbell and trapezoidal membership functions (MFs) and SVM are assessed using different statistical indices like root mean square error, correlation coefficients (CC) and Nash Sutcliff error (NSE). The errors related to the prediction of effluent Kjeldahl Nitrogen concentration by the SVM modeling appeared to be reasonable when compared to that of ANFIS models with Gbell and trapezoidal MF. From the performance evaluation of the developed SVM model, it is observed that the approach is capable to define the inter-relationship between various wastewater quality variables and thus SVM can be potentially applied for evaluating the efficiency of aerobic biological processes in WWTP.

Electron spin contrast of Purcell-enhanced nitrogen-vacancy ensembles in nanodiamonds

Science.gov (United States)

Bogdanov, S.; Shalaginov, M. Y.; Akimov, A.; Lagutchev, A. S.; Kapitanova, P.; Liu, J.; Woods, D.; Ferrera, M.; Belov, P.; Irudayaraj, J.; Boltasseva, A.; Shalaev, V. M.

2017-07-01

Nitrogen-vacancy centers in diamond allow for coherent spin-state manipulation at room temperature, which could bring dramatic advances to nanoscale sensing and quantum information technology. We introduce a method for the optical measurement of the spin contrast in dense nitrogen-vacancy (NV) ensembles. This method brings insight into the interplay between the spin contrast and fluorescence lifetime. We show that for improving the spin readout sensitivity in NV ensembles, one should aim at modifying the far-field radiation pattern rather than enhancing the emission rate.

Enhanced Removal of Nutrients and Trace Organics from Urban Runoff with Novel Capture, Treatment, and Recharge Systems

Science.gov (United States)

Ashoori, N.; Planes, M. T.; Lefevre, G.; Sedlak, D.; Luthy, R. G.

2017-12-01

Rapid population growth, urban sprawl and impact of climate change are forcing water-stressed areas to rely on new local sources of water supply. Under this scenario, reclamation of stormwater runoff has emerged as a source for irrigation and replenishing drinking-water groundwater reservoirs. However, urban stormwater can be a significant source of pollutants, including nutrients and organic compounds. In order to overcome the stormwater treatment system limitations, this project has developed a pilot-scale column system for passive treatment of infiltrated water using low-cost, low-energy geomedia. The objective was to provide guidance on the design and operation of systems for controlling nutrient and trace organic contaminant releases to surface waters. The work comprised of replicate column studies in the field to test stormwater treatment modules with various media, such as woodchips and biochar, using urban runoff from a watershed in Sonoma, California. Woodchip bioreactors host an endemic population of microorganisms that can be harnessed to biologically degrade nitrate. The columns amended with biochar enhance removal of organic pollutants present in stormwater through physicochemical processes (i.e., adsorption onto biochar) and biodegradation in the column through increasing retention time. The field columns were conditioned with stormwater for eight months before being spiked weekly with 50 ppb of representative trace organics. The key finding was the successful field demonstration of a novel treatment system for both the removal of nitrate and trace organics. Nitrogen removal was successful in all columns for the thirteen month experiment due to the woodchips being an effective source of carbon for denitrifying microorganisms to convert nitrate to nitrogen gases. As for the trace organics experiments, the results highlight an overall attenuation of the studied trace organic compounds by the columns containing woodchip and biochar throughout the five

Fe-Mn bi-metallic oxides loaded on granular activated carbon to enhance dye removal by catalytic ozonation.

Science.gov (United States)

Tang, Shoufeng; Yuan, Deling; Zhang, Qi; Liu, Yameng; Zhang, Qi; Liu, Zhengquan; Huang, Haiming

2016-09-01

A Fe-Mn bi-metallic oxide supported on granular activated carbon (Fe-Mn GAC) has been fabricated by an impregnation-desiccation method and tested in the catalytic ozonation of methyl orange (MO) degradation and mineralization. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations revealed that Fe-Mn oxides were successfully loaded and uniformly distributed on the GAC, and nitrogen adsorption isotherms showed that the supported GAC retained a large surface area and a high pore volume compared with the pristine GAC. The catalytic activity was systematically assessed by monitoring the MO removal efficiencies at different operational parameters, such as catalyst dosage, initial solution pH, and ozone flow rate. The Fe-Mn GAC exhibited better catalytic activity relative to ozone alone and GAC alone, improving the TOC removal by 24.5 and 11.5 % and COD removal by 13.6 and 7.3 %, respectively. The reusability of the hybrid was examined over five consecutive cyclic treatments. The Fe-Mn GAC catalytic activity was only a slight loss in the cycles, showing good stability. The addition of Na2CO3 as hydroxyl radicals (•OH) scavengers proved that the catalytic ozonation mechanism was the enhanced generation of •OH by the Fe-Mn GAC. The above results render the Fe-Mn GAC an industrially promising candidate for catalytic ozonation of dye contaminant removal.

An operational protocol for facilitating start-up of single-stage autotrophic nitrogen-removing reactors based on process stoichiometry

DEFF Research Database (Denmark)

Mutlu, Ayten Gizem; Vangsgaard, Anna Katrine; Sin, Gürkan

2013-01-01

Start-up and operation of single-stage nitritation–anammox sequencing batch reactors (SBRs) for completely autotrophic nitrogen removal can be challenging and far from trivial. In this study, a step-wise procedure is developed based on stoichiometric analysis of the process performance from...

454-Pyrosequencing analysis of bacterial communities from autotrophic nitrogen removal bioreactors utilizing universal primers : Effect of annealing temperature

NARCIS (Netherlands)

Gonzalez-Martinez, A.; Rodriguez-Sanchez, A.; Rodelas, B.; Abbas, B.A.; Martinez-Toledo, M.V.; Van Loosdrecht, M.C.M.; Osorio, F.; Gonzalez-Lopez, J.

2015-01-01

Identification of anaerobic ammonium oxidizing (anammox) bacteria by molecular tools aimed at the evaluation of bacterial diversity in autotrophic nitrogen removal systems is limited by the difficulty to design universal primers for the Bacteria domain able to amplify the anammox 16S

Nitrogen removal through N cycling from sediments in a constructed coastal marsh as assessed by 15N-isotope dilution.

Science.gov (United States)

Ro, Hee-Myong; Kim, Pan-Gun; Park, Ji-Suk; Yun, Seok-In; Han, Junho

2018-04-01

Constructed coastal marsh regulates land-born nitrogen (N) loadings through salinity-dependent microbial N transformation processes. A hypothesis that salinity predominantly controls N removal in marsh was tested through incubation in a closed system with added- 15 NH 4 + using sediments collected from five sub-marshes in Shihwa marsh, Korea. Time-course patterns of concentrations and 15 N-atom% of soil-N pools were analyzed. Sediments having higher salinity and lower soil organic-C and acid-extractable organic-N exhibited slower rates of N mineralization and immobilization, nitrification, and denitrification. Rates of denitrification were not predicted well by sediment salinity but by its organic-C, indicating heterotrophic denitrification. Denitrification dominated N-loss from this marsh, and nitrogen removal capacity of this marsh was estimated at 337 kg N day -1 (9.9% of the daily N-loadings) considering the current rooting depth of common reeds (1.0 m). We showed that sediment N removal decreases with increasing salinity and can increase with increasing organic-C for heterotrophic denitrification. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nitrogen fate model for gas-phase ammonia-enhanced in situ bioventing

International Nuclear Information System (INIS)

Marshall, T.R.

1995-01-01

Subsurface bioremediation of contaminants is sometimes limited by the availability of nitrogen. Introduction of gaseous ammonia to the subsurface is a feasible and economical approach to enhance biodegradation in some environments. A gaseous nutrient source may be a practical option for sites where surface application of liquid nutrients is not possible, such as sites with shallow groundwater or sites with surface operations. A conceptual nitrogen fate model was developed to provide remediation scientists and engineers with some practical guidelines in the use of ammonia-enhanced bioventing. Ammonia supplied to the subsurface dissolves readily in soil moisture and sorbs strongly to soil particles. The ammonium ion is the preferred nutrient form of many microorganisms. Some of the ammonia will be converted to nitrate by ammonia-oxidizing organisms. Field monitoring data from an operating ammonia-enhanced bioventing remediation site for diesel fuel contamination are presented. Conservative additions of ammonia promoted appreciable increases in evolved carbon dioxide and rate of oxygen utilization. An overabundance of added ammonia promoted formation of methane from likely anaerobic hydrocarbon degradation in the presence of nitrate as the electron acceptor

Nitrogen removal from sludge digester liquids by nitrification/denitrification or partial nitritation/anammox: environmental and economical considerations.

Science.gov (United States)

Fux, C; Siegrist, H

2004-01-01

In wastewater treatment plants with anaerobic sludge digestion, 15-20% of the nitrogen load is recirculated to the main stream with the return liquors from dewatering. Separate treatment of this ammonium-rich digester supernatant significantly reduces the nitrogen load of the activated sludge system. Two biological applications are considered for nitrogen elimination: (i) classical autotrophic nitrification/heterotrophic denitrification and (ii) partial nitritation/autotrophic anaerobic ammonium oxidation (anammox). With both applications 85-90% nitrogen removal can be achieved, but there are considerable differences in terms of sustainability and costs. The final gaseous products for heterotrophic denitrification are generally not measured and are assumed to be nitrogen gas (N2). However, significant nitrous oxide (N2O) production can occur at elevated nitrite concentrations in the reactor. Denitrification via nitrite instead of nitrate has been promoted in recent years in order to reduce the oxygen and the organic carbon requirements. Obviously this "achievement" turns out to be rather disadvantageous from an overall environmental point of view. On the other hand no unfavorable intermediates are emitted during anaerobic ammonium oxidation. A cost estimate for both applications demonstrates that partial nitritation/anammox is also more economical than classical nitrification/denitrification. Therefore autotrophic nitrogen elimination should be used in future to treat ammonium-rich sludge liquors.

The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: a review of a recent development.

Science.gov (United States)

Vymazal, Jan

2013-09-15

The hybrid systems were developed in the 1960s but their use increased only during the late 1990 s and in the 2000s mostly because of more stringent discharge limits for nitrogen and also more complex wastewaters treated in constructed wetlands (CWs). The early hybrid CWs consisted of several stages of vertical flow (VF) followed by several stages of horizontal flow (HF) beds. During the 1990 s, HF-VF and VF-HF hybrid systems were introduced. However, to achieve higher removal of total nitrogen or to treat more complex industrial and agricultural wastewaters other types of hybrid constructed wetlands including free water surface (FWS) CWs and multistage CWs have recently been used as well. The survey of 60 hybrid constructed wetlands from 24 countries reported after 2003 revealed that hybrid constructed wetlands are primarily used on Europe and in Asia while in other continents their use is limited. The most commonly used hybrid system is a VF-HF constructed wetland which has been used for treatment of both sewage and industrial wastewaters. On the other hand, the use of a HF-VF system has been reported only for treatment of municipal sewage. Out of 60 surveyed hybrid systems, 38 have been designed to treat municipal sewage while 22 hybrid systems were designed to treat various industrial and agricultural wastewaters. The more detailed analysis revealed that VF-HF hybrid constructed wetlands are slightly more efficient in ammonia removal than hybrid systems with FWS CWs, HF-VF systems or multistage VF and HF hybrid CWs. All types of hybrid CWs are comparable with single VF CWs in terms of NH4-N removal rates. On the other hand, CWs with FWS units remove substantially more total nitrogen as compared to other types of hybrid constructed wetlands. However, all types of hybrid constructed wetlands are more efficient in total nitrogen removal than single HF or VF constructed wetlands. Copyright © 2013 Elsevier Ltd. All rights reserved.

Simultaneous removal of carbon and nitrogen by mycelial pellets of a heterotrophic nitrifying fungus-Penicillium sp. L1.

Science.gov (United States)

Liu, Yuxiang; Hu, Tingting; Zhao, Jing; Lv, Yongkang; Ren, Ruipeng

2017-02-01

A novel heterotrophic nitrifying fungus, defined as Penicillium sp. L1, can form mycelial pellets in liquid medium in this study. The effects of inoculation method, C/N ratio, initial pH, and temperature were gradually evaluated to improve the simultaneous removal of total nitrogen (TN) and chemical oxygen demand (COD) in wastewater by Penicillium sp. L1. Results showed that compared with spore inoculation, 48 h pellet inoculum could significantly increase the pellet size (from about 1.5 mm to 3.2 mm) and improve the removal capability, particularly for COD removal (from less than 50-86.20%). The removal efficiencies of TN and COD reached 98.38% (from 136.01 mg/L to 2.20 mg/L) and 92.40% (from 10,720 mg/L to 815 mg/L) under the following conditions: C/N 36, pH 3, 30°C, and inoculation with 48 h pellets. The pellet diameter reached 4.8 mm after 4-day cultivation. In this case, Penicillium sp. L1 removed TN from 415.93 mg/L to 43.39 mg/L, as well as COD from 29,533 mg/L to 8850 mg/L. Overall, the results indicated that the pellet size was closely related to the pollutant-removal ability of Penicillium sp. L1. Furthermore, mycelial pellets (4.8 mm, dead) only adsorbed 38.08% TN (from 125.45 mg/L to 77.78 mg/L), which indicated that adsorption did not play a major role in the nitrogen-removal process. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Nitrogen and carbon export from urban areas through removal and export of litterfall

International Nuclear Information System (INIS)

Templer, Pamela H.; Toll, Jonathan W.; Hutyra, Lucy R.; Raciti, Steve M.

2015-01-01

We found that up to 52 ± 17% of residential litterfall carbon (C) and nitrogen (N; 390.6 kg C and 6.5 kg N ha −1  yr −1 ) is exported through yard waste removed from the City of Boston, which is equivalent to more than half of annual N outputs as gas loss (i.e. denitrification) or leaching. Our results show that removing yard waste results in a substantial decrease in N inputs to urban areas, which may offset excess N inputs from atmospheric deposition, fertilizer application and pet waste. However, export of C and N via yard waste removal may create nutrient limitation for some vegetation due to diminished recycling of nutrients. Removal of leaf litter from residential areas disrupts nutrient cycling and residential yard management practices are an important modification to urban biogeochemical cycling, which could contribute to spatial heterogeneity of ecosystems that are either N limited or saturated within urban ecosystems. - Highlights: • We monitored yard waste bags for one complete fall yard waste collection season. • 52% of residential litterfall C and N is exported annually from the City of Boston. • Litterfall export may create nutrient limitation hotspots in urban ecosystems. • C and N export through litterfall collection modifies urban biogeochemical cycling. - Litterfall removal leads to C and N export from urban ecosystems and disrupts nutrient cycling, showing that this activity is an important modification to urban biogeochemical cycling

Molecular nitrogen fixation and nitrogen cycle in nature

Energy Technology Data Exchange (ETDEWEB)

Virtanen, A I

1952-01-01

The origin of nitrogen oxides in the atmosphere is discussed. Evidently only a small proportion of the nitrate-and nitrite-nitrogen found in the precipitation is formed through electric discharges from molecular nitrogen, photochemical nitrogen fixation being probably of greater importance. Formation of nitrate nitrogen through atmospheric oxidation of nitrous oxide (N/sub 2/O) evaporating from the soil is also considered likely. Determination of nitrogen compounds at different altitudes is indispensable for gaining information of the N/sub 2/-fixation in the atmosphere and, in general, of the origin of nitrogen oxides and their decomposition. International cooperation is needed for this as well as for the quantitative determination of the nitrogen compounds removed from the soil by leaching and brought by waters into the seas.

Ammonium Nitrogen Removal from Urea Fertilizer Plant Wastewater via Struvite Crystal Production

Science.gov (United States)

Machdar, I.; Depari, S. D.; Ulfa, R.; Muhammad, S.; Hisbullah, A. B.; Safrul, W.

2018-05-01

Elimination of ammonium concentration from urea fertilizer plant wastewater through struvite crystal (NH4MgPO4.6H2O) formation by adding MgCl2, KH2PO4, and KOH were studied. This method of elimination has two benefits, namely, reducing ammonium nitrogen content in the wastewater, as well as production of a valuable material (struvite crystal). Struvite is known as a slow-release fertilizer and less soluble. This report presents the ammonium removal efficiencies during struvite formation. The growth of struvite production under different molar ratios of Mg2+:NH4 +:PO4 3- and solution pH is also discussed. To find the efficiencies and measure the growth rates, lab-scale experiments were conducted in a batch crystallizer-reactor. SEM, XRD, and FTIR observation were also applied to investigate the characteristics of struvite. The reactant molar ratios of Mg2+:NH4 +:PO4 3- of 1.2:1:1, 1:1:1.2, and 1:1:1 were evaluated. Each of the molar ratios was treated at the solution pH of 8, 9, and 10. It was found that, the highest ammonium removal efficiency was 94.7% at the molar ratio of 1.2:1:1 and pH of 9. Primarily, the growth rate of struvite formation complied with a first-order kinetic model. The rate constants (k1) were calculated to be 2.6, 4.3, and 5.0 h-1 for solution pH of 8, 9, and 10, respectively. The findings of the study provide suggestion for an alternative sustainable recovery of ammonium nitrogen content in a urea fertilizer plant effluent.

Denitrifying capabilities of Tetrasphaera and their contribution towards nitrous oxide production in enhanced biological phosphorus removal processes.

Science.gov (United States)

Marques, Ricardo; Ribera-Guardia, Anna; Santos, Jorge; Carvalho, Gilda; Reis, Maria A M; Pijuan, Maite; Oehmen, Adrian

2018-06-15

Denitrifying enhanced biological phosphorus removal (EBPR) systems can be an efficient means of removing phosphate (P) and nitrate (NO 3 - ) with low carbon source and oxygen requirements. Tetrasphaera is one of the most abundant polyphosphate accumulating organisms present in EBPR systems, but their capacity to achieve denitrifying EBPR has not previously been determined. An enriched Tetrasphaera culture, comprising over 80% of the bacterial biovolume was obtained in this work. Despite the denitrification capacity of Tetrasphaera, this culture achieved only low levels of anoxic P-uptake. Batch tests with different combinations of NO 3 - , nitrite (NO 2 - ) and nitrous oxide (N 2 O) revealed lower N 2 O accumulation by Tetrasphaera as compared to Accumulibacter and Competibacter when multiple electron acceptors were added. Electron competition was observed during the addition of multiple nitrogen electron acceptors species, where P uptake appeared to be slightly favoured over glycogen production in these situations. This study increases our understanding of the role of Tetrasphaera-related organisms in denitrifying EBPR systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of process costs for small-scale nitrogen removal from natural gas. Topical report, January 1989-December 1989

International Nuclear Information System (INIS)

Echterhoff, L.W.; Pathak, V.K.

1991-08-01

The report establishes the cost of producing pipeline quality gas on a small scale from high nitrogen subquality natural gas. Three processing technologies are evaluated: cryogenic, Nitrotec Engineering Inc.'s pressure swing adsorption (PSA), and lean oil absorption. Comparison of the established costs shows that the cryogenic process exhibits the lowest total plant investment for nitrogen feed contents up to about 22%, above which the PSA process exhibits the lowest investment cost. The lean oil process exhibits the highest total plant investment at the 25% nitrogen feed studied. Opposite to the total plant investment for the cryogenic process, the total plant investment for the PSA process decreases with increasing nitrogen content primarily due to increasing product gas compression requirements. The cryogenic process exhibits the lowest gas processing costs for the nitrogen content range under study. However, the difference between the gas processing costs for the PSA and cryogenic processes narrows as the nitrogen content approaches 15-25%. The lean oil gas processing cost is very high compared to both the cryogenic and PSA processes. The report verifies that nitrogen removal from natural gas is expensive, especially for small-scale applications, and several avenues are identified for improving the cryogenic and PSA technologies

Enhanced nitrogen deposition over China

Energy Technology Data Exchange (ETDEWEB)

Liu, Xuejun; Zhang, Ying; Han, Wenxuan; Tang, Aohan; Shen, Jianlin; Cui, Zhenling; Christie, Peter; Zhang, Fusuo [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Vitousek, Peter [Department of Biology, Stanford University, Stanford, California 94305 (United States); Erisman, Jan Willem [VU University Amsterdam, 1081 HV Amsterdam (Netherlands); Goulding, Keith [The Sustainable Soils and Grassland Systems Department, Rothamsted Research, Harpenden AL5 2JQ (United Kingdom); Fangmeier, Andreas [Institute of Landscape and Plant Ecology, University of Hohenheim, 70593 Stuttgart (Germany)

2013-02-28

China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P < 0.001) between the 1980s (13.2 kilograms of nitrogen per hectare) and the 2000s (21.1 kilograms of nitrogen per hectare). Nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s, before the introduction of mitigation measures. Nitrogen from ammonium (NH4+) is the dominant form of N in bulk deposition, but the rate of increase is largest for deposition of N from nitrate (NO3-), in agreement with decreased ratios of NH3 to NOx emissions since 1980. We also find that the impact of N deposition on Chinese ecosystems includes significantly increased plant foliar N concentrations in natural and semi-natural (that is, non-agricultural) ecosystems and increased crop N uptake from long-term-unfertilized croplands. China and other economies are facing a continuing challenge to reduce emissions of reactive nitrogen, N deposition and their negative effects on human health and the environment.

Selection of controlled variables in bioprocesses. Application to a SHARON-Anammox process for autotrophic nitrogen removal

DEFF Research Database (Denmark)

Mauricio Iglesias, Miguel; Valverde Perez, Borja; Sin, Gürkan

Selecting the right controlled variables in a bioprocess is challenging since the objectives of the process (yields, product or substrate concentration) are difficult to relate with a given actuator. We apply here process control tools that can be used to assist in the selection of controlled var...... variables to the case of the SHARON-Anammox process for autotrophic nitrogen removal....

Effect of application rates and media types on nitrogen and surfactant removal in trickling filters applied to the post-treatment of effluents from UASB reactors

International Nuclear Information System (INIS)

Almeida, P. G. S. de; Taveres, F. v. F.; Chernicharo, C. A. I.

2009-01-01

Tricking filters are a very promising alternative for the post treatment of effluents from UASB reactors treating domestic sewage,especially in developing countries. Although a fair amount of information is already available regarding organic mater removal in this combined system, very little is known in relation to nitrogen and surfactant removal in trickling filters post-UASB reactors. Therefore, the purpose of this study was to evaluate and compare the effect evaluate and compare the effect of different application rates and packing media types on trickling filters applied to the post-treatment of effluents from UASB reactors, regarding the removal of ammonia nitrogen and surfactants. (Author)

Effect of application rates and media types on nitrogen and surfactant removal in trickling filters applied to the post-treatment of effluents from UASB reactors

Energy Technology Data Exchange (ETDEWEB)

Almeida, P. G. S. de; Taveres, F. v. F.; Chernicharo, C. A. I.

2009-07-01

Tricking filters are a very promising alternative for the post treatment of effluents from UASB reactors treating domestic sewage,especially in developing countries. Although a fair amount of information is already available regarding organic mater removal in this combined system, very little is known in relation to nitrogen and surfactant removal in trickling filters post-UASB reactors. Therefore, the purpose of this study was to evaluate and compare the effect evaluate and compare the effect of different application rates and packing media types on trickling filters applied to the post-treatment of effluents from UASB reactors, regarding the removal of ammonia nitrogen and surfactants. (Author)

Sulfonamide antibiotic removal and nitrogen recovery from synthetic urine by the combination of rotating advanced oxidation contactor and methylene urea synthesis process.

Science.gov (United States)

Fukahori, S; Fujiwara, T; Ito, R; Funamizu, N

2015-01-01

The combination of nitrogen recovery and pharmaceutical removal processes for livestock urine treatment were investigated to suppress the discharge of pollutants and recover nitrogen as resources. We combined methylene urea synthesis from urea and adsorption and photocatalytic decomposition of sulfonamide antibiotic using rotating advanced oxidation contactor (RAOC) contained for obtaining both safe fertilizer and reclaimed water. The methylene urea synthesis could recover urea in synthetic urine, however, almost all sulfonamide antibiotic was also incorporated, which is unfavorable from a safety aspect if the methylene urea is to be used as fertilizer. Conversely, RAOC could remove sulfonamide antibiotic without consuming urea. It was also confirmed that the methylene urea could be synthesized from synthetic urine treated by RAOC. Thus, we concluded that RAOC should be inserted prior to the nitrogen recovery process for effective treatment of urine and safe use of methylene urea as fertilizer.

454-Pyrosequencing Analysis of Bacterial Communities from Autotrophic Nitrogen Removal Bioreactors Utilizing Universal Primers: Effect of Annealing Temperature.

Science.gov (United States)

Gonzalez-Martinez, Alejandro; Rodriguez-Sanchez, Alejandro; Rodelas, Belén; Abbas, Ben A; Martinez-Toledo, Maria Victoria; van Loosdrecht, Mark C M; Osorio, F; Gonzalez-Lopez, Jesus

2015-01-01

Identification of anaerobic ammonium oxidizing (anammox) bacteria by molecular tools aimed at the evaluation of bacterial diversity in autotrophic nitrogen removal systems is limited by the difficulty to design universal primers for the Bacteria domain able to amplify the anammox 16S rRNA genes. A metagenomic analysis (pyrosequencing) of total bacterial diversity including anammox population in five autotrophic nitrogen removal technologies, two bench-scale models (MBR and Low Temperature CANON) and three full-scale bioreactors (anammox, CANON, and DEMON), was successfully carried out by optimization of primer selection and PCR conditions (annealing temperature). The universal primer 530F was identified as the best candidate for total bacteria and anammox bacteria diversity coverage. Salt-adjusted optimum annealing temperature of primer 530F was calculated (47°C) and hence a range of annealing temperatures of 44-49°C was tested. Pyrosequencing data showed that annealing temperature of 45°C yielded the best results in terms of species richness and diversity for all bioreactors analyzed.

Biological nitrogen and carbon removal in a gravity flow biomass concentrator reactor for municipal sewage treatment.

Science.gov (United States)

Scott, Daniel; Hidaka, Taira; Campo, Pablo; Kleiner, Eric; Suidan, Makram T; Venosa, Albert D

2013-01-01

A novel membrane system, the Biomass Concentrator Reactor (BCR), was evaluated as an alternative technology for the treatment of municipal wastewater. Because the BCR is equipped with a membrane whose average poresize is 20 μm (18-28 μm), the reactor requires low-pressure differential to operate (gravity). The effectiveness of this system was evaluated for the removal of carbon and nitrogen using two identical BCRs, identified as conventional and hybrid, that were operated in parallel. The conventional reactor was operated under full aerobic conditions (i.e., organic carbon and ammonia oxidation), while the hybrid reactor incorporated an anoxic zone for nitrate reduction as well as an aerobic zone for organic carbon and ammonia oxidation. Both reactors were fed synthetic wastewater at a flow rate of 71 L d(-1), which resulted in a hydraulic retention time of 9 h. In the case of the hybrid reactor, the recycle flow from the aerobic zone to the anoxic zone was twice the feed flow rate. Reactor performance was evaluated under two solids retention times (6 and 15 d). Under these conditions, the BCRs achieved nearly 100% mixed liquor solids separation with a hydraulic head differential of less than 2.5 cm. The COD removal efficiency was over 90%. Essentially complete nitrification was achieved in both systems, and nitrogen removal in the hybrid reactor was close to the expected value (67%). Copyright © 2012 Elsevier Ltd. All rights reserved.

Exhaustive Conversion of Inorganic Nitrogen to Nitrogen Gas Based on a Photoelectro-Chlorine Cycle Reaction and a Highly Selective Nitrogen Gas Generation Cathode.

Science.gov (United States)

Zhang, Yan; Li, Jinhua; Bai, Jing; Shen, Zhaoxi; Li, Linsen; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

2018-02-06

A novel method for the exhaustive conversion of inorganic nitrogen to nitrogen gas is proposed in this paper. The key properties of the system design included an exhaustive photoelectrochemical cycle reaction in the presence of Cl - , in which Cl· generated from oxidation of Cl - by photoholes selectively converted NH 4 + to nitrogen gas and some NO 3 - or NO 2 - . The NO 3 - or NO 2 - was finally reduced to nitrogen gas on a highly selective Pd-Cu-modified Ni foam (Pd-Cu/NF) cathode to achieve exhaustive conversion of inorganic nitrogen to nitrogen gas. The results indicated total nitrogen removal efficiencies of 30 mg L -1 inorganic nitrogen (NO 3 - , NH 4 + , NO 3 - /NH 4 + = 1:1 and NO 2 - /NO 3 - /NH 4 + = 1:1:1) in 90 min were 98.2%, 97.4%, 93.1%, and 98.4%, respectively, and the remaining nitrogen was completely removed by prolonging the reaction time. The rapid reduction of nitrate was ascribed to the capacitor characteristics of Pd-Cu/NF that promoted nitrate adsorption in the presence of an electric double layer, eliminating repulsion between the cathode and the anion. Nitrate was effectively removed with a rate constant of 0.050 min -1 , which was 33 times larger than that of Pt cathode. This system shows great potential for inorganic nitrogen treatment due to the high rate, low cost, and clean energy source.

Optimization aspects of the biological nitrogen removal process in a full-scale twin sequencing batch reactor (SBR) system in series treating landfill leachate.

Science.gov (United States)

Remmas, Nikolaos; Ntougias, Spyridon; Chatzopoulou, Marianna; Melidis, Paraschos

2018-03-29

Despite the fact that biological nitrogen removal (BNR) process has been studied in detail in laboratory- and pilot-scale sequencing batch reactor (SBR) systems treating landfill leachate, a limited number of research works have been performed in full-scale SBR plants regarding nitrification and denitrification. In the current study, a full-scale twin SBR system in series of 700 m 3 (350 m 3 each) treating medium-age landfill leachate was evaluated in terms of its carbon and nitrogen removal efficiency in the absence and presence of external carbon source, i.e., glycerol from biodiesel production. Both biodegradable organic carbon and ammonia were highly oxidized [biochemical oxygen demand (BOD 5 ) and total Kjehldahl nitrogen (TKN) removal efficiencies above 90%], whereas chemical oxygen demand (COD) removal efficiency was slightly above 40%, which is within the range reported in the literature for pilot-scale SBRs. As the consequence of the high recalcitrant organic fraction of the landfill leachate, dissimilatory nitrate reduction was restricted in the absence of crude glycerol, although denitrification was improved by electron donor addition, resulting in TN removal efficiencies above 70%. Experimental data revealed that the second SBR negligibly contributed to BNR process, since carbon and ammonia oxidation completion was achieved in the first SBR. On the other hand, the low VSS/SS ratio, due to the lack of primary sedimentation, highly improved sludge settleability, resulting in sludge volume indices (SVI) below 30 mL g -1 .

A robust nitrifying community in a bioreactor at 50 °C opens up the path for thermophilic nitrogen removal.

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Courtens, Emilie Np; Spieck, Eva; Vilchez-Vargas, Ramiro; Bodé, Samuel; Boeckx, Pascal; Schouten, Stefan; Jauregui, Ruy; Pieper, Dietmar H; Vlaeminck, Siegfried E; Boon, Nico

2016-09-01

The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes eliminate nitrogen from wastewaters. Although thermophilic nitrifiers have been separately enriched from natural environments, no bioreactors are described that couple these processes for the treatment of nitrogen in hot wastewaters. Samples from composting facilities were used as inoculum for the batch-wise enrichment of thermophilic nitrifiers (350 days). Subsequently, the enrichments were transferred to a bioreactor to obtain a stable, high-rate nitrifying process (560 days). The community contained up to 17% ammonia-oxidizing archaea (AOAs) closely related to 'Candidatus Nitrososphaera gargensis', and 25% nitrite-oxidizing bacteria (NOBs) related to Nitrospira calida. Incorporation of (13)C-derived bicarbonate into the respective characteristic membrane lipids during nitrification supported their activity as autotrophs. Specific activities up to 198±10 and 894±81 mg N g(-1) VSS per day for AOAs and NOBs were measured, where NOBs were 33% more sensitive to free ammonia. The NOBs were extremely sensitive to free nitrous acid, whereas the AOAs could only be inhibited by high nitrite concentrations, independent of the free nitrous acid concentration. The observed difference in product/substrate inhibition could facilitate the development of NOB inhibition strategies to achieve more cost-effective processes such as deammonification. This study describes the enrichment of autotrophic thermophilic nitrifiers from a nutrient-rich environment and the successful operation of a thermophilic nitrifying bioreactor for the first time, facilitating opportunities for thermophilic nitrogen removal biotechnology.

The effects of antecedent dry days on the nitrogen removal in layered soil infiltration systems for storm run-off control.

Science.gov (United States)

Cho, Kang-Woo; Yoon, Min-Hyuk; Song, Kyung-Guen; Ahn, Kyu-Hong

2011-01-01

The effects of antecedent dry days (ADD) on nitrogen removal efficiency were investigated in soil infiltration systems, with three distinguishable layers: mulch layer (ML), coarse soil layer (CSL) and fine soil layer (FSL). Two sets of lab-scale columns with loamy CSL (C1) and sandy CSL (C2) were dosed with synthetic run-off, carrying chemical oxygen demand of 100 mg L(-1) and total nitrogen of 13 mg L(-1). The intermittent dosing cycle was stepwise adjusted for 5, 10 and 20 days. The influent ammonium and organic nitrogen were adsorbed to the entire depth in C1, while dominantly to the FSL in C2. In both columns, the effluent ammonium concentration increased while the organic nitrogen concentration decreased, as ADD increased from 5 to 20 days. The effluent of C1 always showed nitrate concentration exceeding influent, caused by nitrification, by increasing amounts as ADD increased. However, the wash-out of nitrate in C1 was not distinct in terms of mass since the effluent flow rate was only 25% of the influent. In contrast, efficient reduction (>95%) of nitrate loading was observed in C2 under ADD of 5 and 10 days, because of insignificant nitrification in the CSL and denitrification in the FSL. However, for the ADD of 20 days, a significant nitrate wash-out appeared in C2 as well, possibly because of the re-aeration by the decreasing water content in the FSL. Consequently, the total nitrogen load escaping with the effluent was always smaller in C2, supporting the effectiveness of sandy CSL over loamy FSL for nitrogen removal under various ADDs.

Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

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X. Yang

2010-10-01

Full Text Available We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades

Nitrogen and Phosphorus Removal in the Recirculating Aquaculture System with Water Treatment Tank containing Baked Clay Beads and Chinese Cabbage

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Aeknarin Thanakitpairin

2014-01-01

Full Text Available This research aims to describe the nitrogen and phosphorus removal in Recirculating Aquaculture System (RAS by crop plants biomass production. The 3 experiment systems consisted of 1 treatment (fish tank + baked clay beads + Chinese cabbage and 2 controls as control-1 (fish tank only and control-2 (fish tank + baked clay beads, were performed. With all experimental RAS, Nile tilapia (Oreochromis niloticus was cultured at 2 kg/m3 density. The baked clay beads (8-16 mm in diameter were filled as a layer of 10 cm in the water treatment tank of control-2. While in the treatment tank, Chinese cabbage (Brassica pekinensis was planted at 334 plants/m2 in baked clay beads layer. During 35 days of experiment, the average fish wet-weight in control-1, control-2 and treatment systems increased from 16.31±1.49, 15.18±1.28 and 11.31±1.49 g to 29.43±7.06, 28.65±3.12 and 27.20±6.56 g, respectively. It was found that the growth rate of 0.45±0.15 g-wet weight/day in a treatment tank was higher than in those 2 controls, which were rather similar at 0.37±0.16 and 0.38±0.05 g-wet weight/day, respectively. The fish survival rate of all experimental units was 100%. The average Chinese cabbage wet-weight in treatment system increased from 0.15±0.02 g to 1.00±0.38 g. For water quality, all parameters were within the acceptable range for aquaculture. The assimilation inorganic nitrogen in a treatment tank showed a slower rate and lower nitrite accumulation relative to those in control tanks. The nitrogen and phosphorus balance analysis illustrated that most of the nitrogen and phosphorus input in all systems was from feed (82-87% and 21-87% while at the final day of experiments, nitrogen and phosphorus in tilapia culture revealed at 15-19% and 4-13%. The accumulation of nitrogen and phosphorus in the water, up to 56% and 70%, was found in control-1 while water in the tank with baked clay beads had substantial lower nitrogen and phosphorus concentration. The

Enhanced removal of Methylene Blue by electrocoagulation using iron electrodes

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Mohamed S. Mahmoud

2013-06-01

Full Text Available The removal of pollutants from effluents by electrocoagulation has become an attractive method in recent years. The study deals with the enhancement of removal of Methylene Blue dye by using an electromagnetic field during the electrocoagulation process. Effects of electrolyte concentration, dye concentration, intensity and the direction of the electromagnet on the decolorization efficiency have been investigated. The formed ferric hydroxide flocs trap colloidal particles and make solid–liquid separation easier during the next stage. The electrocoagulation stages must be optimized in order to design an economically feasible process. The results showed that the optimum electrolysis was 10–20 min at a current density of 8 mA/cm2, while the optimum concentration of the electrolyte (NaOH was found to be 2 wt.% when the dye concentration was 50 mg/L. The utilization of an electromagnetic field enhanced the dye removal due to the induced motion of paramagnetic ions inside the solution. The power consumption required to remove the dye was reduced by 45% in the case of applying an electromagnetic field.

Enhancement of root growth and nitrogen fixation in Trigonella by UV-exclusion from solar radiation.

Science.gov (United States)

Sharma, Sonika; Guruprasad, K N

2012-12-01

A field experiment was conducted to study the impact of solar UV on root growth and nitrogen fixation in Trigonella foenum-graecum. Plants were grown in iron mesh cages covered with polyester filters that could specifically cut off UV-B (280-315 nm) or UV-A + B (280-400 nm) part of the solar spectrum. The control plants were grown under a polythene filter transmissible to UV. Root biomass, number of nodules and nodule fresh weight were enhanced after exclusion of solar UV. Nitrogenase activity was significantly enhanced by 120% and 80% in the UV-B and UV-A + B excluded plants respectively. Along with nitrogenase there was concomitant increase in leghemoglobin and hemechrome content in the nodules after exclusion of solar UV. These components of sunlight limits nitrogen fixation and their elimination can enhance nitrogen fixation with agricultural advantages like reduction in the use of fertilizers. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Reactor performance in terms of COD and nitrogen removal and bacterial community structure of a three-stage rotating bioelectrochemical contactor

KAUST Repository

Sayess, Rassil R.; Saikaly, Pascal; El-Fadel, Mutasem E.; Li, Dong; Semerjian, Lucy A.

2013-01-01

contactor (referred to as RBC-MFC unit) integrating MFC with RBC technology was constructed for simultaneous removal of carbonaceous and nitrogenous compounds and electricity generation from a synthetic medium containing acetate and ammonium. The performance

Removal of carbon, nitrogen and phosphorus from the separated liquid phase of hog manure by the multi-zone BioCAST technology.

Science.gov (United States)

Yerushalmi, Laleh; Alimahmoodi, Mahmood; Afroze, Niema; Godbout, Stephane; Mulligan, Catherine N

2013-06-15

The removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) at concentrations of 960 ± 38 to 2400 ± 96 mg/L, 143 ± 9 to 235 ± 15 mg/L and 25 ± 2 to 57 ± 4 mg/L, respectively, from the separated liquid phase of hog manure by the multi-zone BioCAST technology is discussed. Despite the inhibitory effect of hog waste toward microbial activities, removal efficiencies up to 89.2% for COD, 69.2% for TN and 47.6% for TP were obtained during 185 d of continuous operation. The free ammonia inhibition was postulated to be responsible for the steady reduction of COD and TP removal with the increase of TN/TP ratio from 3.6 to 5.8. On the contrary, the increase of COD/TN ratio from 4.8 to 14.1 improved the removal of all contaminants. Nitrogen removal did not show any dependence on the COD/TP ratio, despite the steady increase of COD and TP removal with this ratio in the range of 19.3-50.6. The removal efficiencies of organic and inorganic contaminants increased progressively owing to the adaptation of microbial biomass, resulting from the presence of suspended biomass in the mixed liquor that circulated continuously between the three zones of aerobic, microaerophilic and anoxic, as well as the attached biomass immobilized inside the aerobic zone. Copyright © 2013 Elsevier B.V. All rights reserved.

Environmental Modeling, The Buffer Priority layers for Nitrogen Removal identify priority forest/grass buffer sites by subwatershed. Land use, hydrology, soil, and landscape characteristics were analyzed to rank opportunities with high nitrogen removal potential., Published in 2014, Smaller than 1:100000 scale, Maryland Department of Natural Resources (DNR).

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NSGIC Education | GIS Inventory — Environmental Modeling dataset current as of 2014. The Buffer Priority layers for Nitrogen Removal identify priority forest/grass buffer sites by subwatershed. Land...

Myriophyllum aquaticum Constructed Wetland Effectively Removes Nitrogen in Swine Wastewater

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Haishu Sun

2017-10-01

Full Text Available Removal of nitrogen (N is a critical aspect in the functioning of constructed wetlands (CWs, and the N treatment in CWs depends largely on the presence and activity of macrophytes and microorganisms. However, the effects of plants on microorganisms responsible for N removal are poorly understood. In this study, a three-stage surface flow CW was constructed in a pilot-scale within monospecies stands of Myriophyllum aquaticum to treat swine wastewater. Steady-state conditions were achieved throughout the 600-day operating period, and a high (98.3% average ammonia removal efficiency under a N loading rate of 9 kg ha-1 d-1 was observed. To determine whether this high efficiency was associated with the performance of active microbes, the abundance, structure, and interactions of microbial community were compared in the unvegetated and vegetated samples. Real-time quantitative polymerase chain reactions showed the abundances of nitrifying genes (archaeal and bacterial amoA and denitrifying genes (nirS, nirK, and nosZ were increased significantly by M. aquaticum in the sediments, and the strongest effects were observed for the archaeal amoA (218-fold and nirS genes (4620-fold. High-throughput sequencing of microbial 16S rRNA gene amplicons showed that M. aquaticum greatly changed the microbial community, and ammonium oxidizers (Nitrosospira and Nitrososphaera, nitrite-oxidizing bacteria (Nitrospira, and abundant denitrifiers including Rhodoplanes, Bradyrhizobium, and Hyphomicrobium, were enriched significantly in the sediments. The results of a canonical correspondence analysis and Mantle tests indicated that M. aquaticum may shift the sediment microbial community by changing the sediment chemical properties. The enriched nitrifiers and denitrifiers were distributed widely in the vegetated sediments, showing positive ecological associations among themselves and other bacteria based on phylogenetic molecular ecological networks.

Sulfonamide antibiotic removal and nitrogen recovery from synthetic urine by the combination of rotating advanced oxidation contactor and methylene urea synthesis process

OpenAIRE

Fukahori, S.; Fujiwara, T.; Ito, R.; Funamizu, N.

2015-01-01

The combination of nitrogen recovery and pharmaceutical removal processes for livestock urine treatment were investigated to suppress the discharge of pollutants and recover nitrogen as resources. We combined methylene urea synthesis from urea and adsorption and photocatalytic decomposition of sulfonamide antibiotic using rotating advanced oxidation contactor (RAOC) contained for obtaining both safe fertilizer and reclaimed water. The methylene urea synthesis could recover urea in synthetic u...

Underestimated effects of sediments on enhanced startup performance of biofilm systems for polluted source water pretreatment.

Science.gov (United States)

Lv, Zheng-Hui; Wang, Jing; Yang, Guang-Feng; Feng, Li-Juan; Mu, Jun; Zhu, Liang; Xu, Xiang-Yang

2018-02-01

In order to evaluate the enhancement mechanisms of enhanced startup performance in biofilm systems for polluted source water pretreatment, three lab-scale reactors with elastic stereo media (ESM) were operated under different enhanced sediment and hydraulic agitation conditions. It is interesting to found the previously underestimated or overlooked effects of sediment on the enhancement of pollutants removal performance and enrichment of functional bacteria in biofilm systems. The maximum NH 4 + -N removal rate of 0.35 mg L -1 h -1 in sediment enhanced condition was 2.19 times of that in control reactor. Sediment contributed to 42.0-56.5% of NH 4 + -N removal and 15.4-41.2% of total nitrogen removal in different reactors under different operation conditions. The enhanced hydraulic agitation with sediment further improved the operation performance and accumulation of functional bacteria. Generally, Proteobacteria (48.9-52.1%), Bacteroidetes (18.9-20.8%) and Actinobacteria (15.7-18.5%) were dominant in both sediment and ESM bioiflm at  phylum level. The potentially functional bacteria found in sediment and ESM biofilm samples with some functional bacteria mainly presented in sediment samples only (e.g., Genera Bacillus and Lactococcus of Firmicutes phylum) may commonly contribute to the removal of nitrogen and organics.

Removal of halogenated emerging contaminants from water by nitrogen-doped graphene decorated with palladium nanoparticles: Experimental investigation and theoretical analysis.

Science.gov (United States)

Li, Lei; Gong, Li; Wang, Yi-Xuan; Liu, Qi; Zhang, Jie; Mu, Yang; Yu, Han-Qing

2016-07-01

The removal performance and mechanisms of halogenated emerging contaminants from water by palladium decorated nitrogen-doped graphene (Pd/NG) were investigated in this study. For comparison, three catalysts of Pd/NG, palladium decorated graphene (Pd/G) and commercial Pd/C were initially explored to degrade tetrabromobisphenol A (TBBPA). After that, the influence of various environmental parameters on TBBPA removal by the Pd/NG catalyst was evaluated. Moreover, both Langmuir-Hinshelwood model and density functional theory (DFT) were adopted to theoretically elucidate the adsorption and the activation of TBBPA on the catalyst. The results show that the apparent rate constant of TBBPA dehalogenation was increased by 26.7% and 39.0% in the presence of the Pd/NG catalyst compared to the Pd/G and Pd/C ones. Higher temperature, catalyst dosage and alkaline conditions resulted in the enhancement of TBBPA dehalogenation by the Pd/NG catalyst, while humic acid in the solution had a negatively effect on the transformation of TBBPA. The corresponding rate constant value exhibited a 2.1- and 1.8-fold increase with the rise of temperature from 298 to 328 K and initial pH from 6.5 to 9.0, respectively. On the contrary, the rate constant was decreased by 78.9% in the presence of 15 mg L(-1) humic acid. Theoretical analysis revealed that both adsorption and activation processes of TBBPA on the Pd/NG catalyst were enhanced through the N doping into graphene framework. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous nitrogen and organics removal using membrane aeration and effluent ultrafiltration in an anaerobic fluidized membrane bioreactor

KAUST Repository

Ye, Yaoli; Saikaly, Pascal; Logan, B.E.

2017-01-01

Dissolved methane and a lack of nutrient removal are two concerns for treatment of wastewater using anaerobic fluidized bed membrane bioreactors (AFMBRs). Membrane aerators were integrated into an AFMBR to form an Aeration membrane fluidized bed membrane bioreactor (AeMFMBR) capable of simultaneous removal of organic matter and ammonia without production of dissolved methane. Good effluent quality was obtained with no detectable suspended solids, 93±5% of chemical oxygen demand (COD) removal to 14±11 mg/L, and 74±8% of total ammonia (TA) removal to 12±3 mg-N/L for domestic wastewater (COD of 193±23 mg/L and TA of 49±5 mg-N/L) treatment. Nitrate and nitrite concentrations were always low (< 1 mg-N/L) during continuous flow treatment. Membrane fouling was well controlled by fluidization of the granular activated carbon (GAC) particles (transmembrane pressures maintained <3 kPa). Analysis of the microbial communities suggested that nitrogen removal was due to nitrification and denitrification based on the presence of microorganisms associated with these processes.

Simultaneous nitrogen and organics removal using membrane aeration and effluent ultrafiltration in an anaerobic fluidized membrane bioreactor

KAUST Repository

Ye, Yaoli

2017-08-03

Dissolved methane and a lack of nutrient removal are two concerns for treatment of wastewater using anaerobic fluidized bed membrane bioreactors (AFMBRs). Membrane aerators were integrated into an AFMBR to form an Aeration membrane fluidized bed membrane bioreactor (AeMFMBR) capable of simultaneous removal of organic matter and ammonia without production of dissolved methane. Good effluent quality was obtained with no detectable suspended solids, 93±5% of chemical oxygen demand (COD) removal to 14±11 mg/L, and 74±8% of total ammonia (TA) removal to 12±3 mg-N/L for domestic wastewater (COD of 193±23 mg/L and TA of 49±5 mg-N/L) treatment. Nitrate and nitrite concentrations were always low (< 1 mg-N/L) during continuous flow treatment. Membrane fouling was well controlled by fluidization of the granular activated carbon (GAC) particles (transmembrane pressures maintained <3 kPa). Analysis of the microbial communities suggested that nitrogen removal was due to nitrification and denitrification based on the presence of microorganisms associated with these processes.

Modeling phytoremediation of nitrogen-polluted water using water hyacinth (Eichhornia crassipes)

Science.gov (United States)

Mayo, Aloyce W.; Hanai, Emmanuel E.

2017-08-01

Water hyacinth (Eichhornia crassipes) has a great potential for purification of wastewater through physical, chemical and biological mechanisms. In an attempt to improve the quality of effluents discharged from waste stabilization ponds at the University of Dar es Salaam, a pilot plant was constructed to experiment the effectiveness of this plants for transformation and removal of nitrogen. Samples of wastewater were collected and examined for water quality parameters, including pH, temperature, dissolved oxygen, and various forms of nitrogen, which were used as input parameters in a kinetic mathematical model. A conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The results show that total nitrogen was removed by 63.9%. Denitrification contributed 73.8% of the removed nitrogen. Other dominant nitrogen removal mechanisms are net sedimentation and uptake by water hyacinth, which contributed 16.7% and 9.5% of the removed nitrogen, respectively. The model indicated that in presence of water hyacinth biofilm about 1.26 g Nm-2day-1 of nitrogen was removed. However, in the absence of biofilm in water hyacinth pond, the permanent nitrogen removal was only 0.89 g Nm-2day-1. This suggests that in absence of water hyacinth, the efficiency of nitrogen removal would decrease by 29.4%.

Influence of road salt on the biological removal of nitrogen

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Eliška Horniaková

2007-10-01

Full Text Available Processes occuring in the aeration tank remove nitrogen from the organic substances in wastewater by using the bacterii. Nitrification utilize the metabolism of aerobic bacterii Nitrosomonas, Nitrococus, Nitrospira, Nitrobacter Nitrocystis a Nitrosobolus. Pseudosomonas, Chromobacterium, Denitrobacillus a Micrococus are denitrification anaerobic bacterii. The bacterii are lithotrophic and they are sensitive to pH of wastewater. Chlorine and heavy metals are toxic for these bacterii. For a correct grow, reproduction and metabolism, temperature above 10 ºC is needed but the ideal temperature is from 20 to 30 ºC. An intensive cold reduces or even stops the activity of bacterii.Cold road salt flow to a sewage and then to the aeration basin. Many of nitrification microorganisms dead because their cells lyse and their content flow into the tank. NaCl is toxic for bacterii. From aeration basin a high amount of N-NH4 flows out. The sludge may be a slightly flocculate and the effluent water may be turbid

454-Pyrosequencing Analysis of Bacterial Communities from Autotrophic Nitrogen Removal Bioreactors Utilizing Universal Primers: Effect of Annealing Temperature

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Alejandro Gonzalez-Martinez

2015-01-01

Full Text Available Identification of anaerobic ammonium oxidizing (anammox bacteria by molecular tools aimed at the evaluation of bacterial diversity in autotrophic nitrogen removal systems is limited by the difficulty to design universal primers for the Bacteria domain able to amplify the anammox 16S rRNA genes. A metagenomic analysis (pyrosequencing of total bacterial diversity including anammox population in five autotrophic nitrogen removal technologies, two bench-scale models (MBR and Low Temperature CANON and three full-scale bioreactors (anammox, CANON, and DEMON, was successfully carried out by optimization of primer selection and PCR conditions (annealing temperature. The universal primer 530F was identified as the best candidate for total bacteria and anammox bacteria diversity coverage. Salt-adjusted optimum annealing temperature of primer 530F was calculated (47°C and hence a range of annealing temperatures of 44–49°C was tested. Pyrosequencing data showed that annealing temperature of 45°C yielded the best results in terms of species richness and diversity for all bioreactors analyzed.

In Situ Denitrification and Biological Nitrogen Fixation Under Enhanced Atmospheric Reactive Nitrogen Deposition in UK Peatlands

Science.gov (United States)

Ullah, Sami; Saiz Val, Ernesto; Sgouridis, Fotis; Peichl, Matthias; Nilsson, Mats

2017-04-01

Dinitrogen (N2) and nitrous oxide (N2O) losses due to denitrification and biological N2 fixation (BNF) are the most uncertain components of the nitrogen (N) cycle in peatlands under enhanced atmospheric reactive nitrogen (Nr) deposition. This uncertainty hampers our ability to assess the contribution of denitrification to the removal of biologically fixed and/or atmospherically deposited Nr in peatlands. This uncertainty emanates from the difficulty in measuring in situ soil N2 and N2O production and consumption in peatlands. In situ denitrification and its contribution to total N2O flux was measured monthly between April 2013 and October 2014 in peatlands in two UK catchments. An adapted 15N-Gas Flux method1 with low level addition of 15N tracer (0.03 ± 0.005 kg 15N ha-1) was used to measure denitrification and its contribution to net N2O production (DN2O/TN2O). BNF was measured in situ through incubation of selected sphagnum species under 15N2 gas tracer. Denitrification2 varied temporally and averaged 8 kg N-N2 ha-1 y-1. The contribution of denitrification was about 48% to total N2O flux3 of 0.05 kg N ha-1 y-1. Soil moisture, temperature, ecosystem respiration, pH and mineral N content mainly regulated the flux of N2 and N2O. Preliminary results showed suppression of BNF, which was 1.8 to 7 times lower in peatland mosses exposed to ˜15 to 20 kg N ha-1 y-1 Nr deposition in the UK than in peatland mosses in northern Sweden with background Nr deposition. Overall, the contribution of denitrification to Nr removal in the selected peatlands was ˜50% of the annual Nr deposition rates, making these ecosystems vulnerable to chronic N saturation. These results point to a need for a more comprehensive annual BNF measurement to more accurately account for total Nr input into peatlands and its atmospheric loss due to denitrification. References Sgouridis F, Stott A & Ullah S, 2016. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to

Removal of arsenic from contaminated water using coagulation enhanced microfiltration

International Nuclear Information System (INIS)

Volchek, K.; Velicogna, D.; Dumouchel, A.; Wong, W.P.; Brown, C.E.

2002-01-01

Results of an innovative arsenic removal process were presented. The process is based on a combination of coagulation and microfiltration processes. Coagulation-Enhanced Microfiltration (CEMF) may eventually become a full-scale commercial technology. This study focused on the process with respect to groundwater treatment because of the importance of arsenic contamination in drinking water. Most experiments were bench-scale using tap water spiked with arsenic. Ferric chloride, which is commonly used in arsenic removal processes was also added. In addition, some tests were conducted on actual arsenic-contaminated water from the effluent treatment plant of a former mining site in Ontario. Results indicate a high arsenic removal efficiency in both spiked and actual water solutions. The microfiltration significantly reduced the level of arsenic in the treatment. This paper described the characteristics of membrane separation. It also presented information regarding chemically enhanced membrane filtration and coagulation-enhanced microfiltration. Bench-scale tests were conducted with both tubular membranes and with immersed capillary membranes. The effect of iron to arsenic ratios on the effectiveness of the system was also tested. It was recommended that future research should include a field study of the process on a pilot-scale to optimize process parameters and to accurately determine the cost of the process. 16 refs., 8 tabs., 9 figs

Enhancement of biodegradation of crude petroleum-oil in contaminated water by the addition of nitrogen sources.

Science.gov (United States)

Mukred, A M; Hamid, A A; Hamzah, A; Yusoff, W M Wan

2008-09-01

Addition of nitrogen sources as supplementary nutrient into MSM medium to enhance biodegradation by stimulating the growth four isolates, Acinetobacter faecalis, Staphylococcus sp., Pseudomonas putida and Neisseria elongata isolated from petroleum contaminated groundwater, wastewater aeration pond and biopond at the oil refinery Terengganu Malaysia was investigated. The organic nitrogen sources tested not only supported growth but also enhances biodegradation of 1% Tapis crude oil. All four isolates showed good growth especially when peptone was employed as the organic nitrogen compared to growth in the basal medium. Gas chromatography showed that more then 91, 93, 94 and 95% degradation of total hydrocarbon was observed after 5 days of incubation by isolates Pseudomonas putida, Neisseria elongate, Acinetobacter faecalis and Staphylococcus sp., respectively.

Adsorptive Removal of Nitrate from Aqueous Solution Using Nitrogen Doped Activated Carbon.

Science.gov (United States)

Machida, Motoi; Goto, Tatsuru; Amano, Yoshimasa; Iida, Tatsuya

2016-01-01

Activated carbon (AC) has been widely applied for adsorptive removal of organic contaminants from aqueous phase, but not for ionic pollutants. In this study, nitrogen doped AC was prepared to increase the adsorption capacity of nitrate from water. AC was oxidized with (NH 4 ) 2 S 2 O 8 solution to maximize oxygen content for the first step, and then NH 3 gas treatment was carried out at 950°C to aim at forming quaternary nitrogen (N-Q) species on AC surface (Ox-9.5AG). Influence of solution pH was examined so as to elucidate the relationship between surface charge and adsorption amounts of nitrate. The results showed that Ox-9.5AG exhibited about twice higher adsorption capacity than non-treatment AC at any initial nitrate concentration and any equilibrium solution pH (pH e ) investigated. The more decrease in pH e value, the more adsorption amount of negatively charged nitrate ion, because the surface charge of AC and Ox-9.5AG could become more positive in acidic solution. The oxidation and consecutive ammonia treatments lead to increase in nitrogen content from 0.35 to 6.4% and decrease in the pH of the point of zero charge (pH pzc ) from 7.1 to 4.0 implying that positively charged N-Q of a Lewis acid was created on the surface of Ox-9.5AG. Based on a Langmuir data analysis, maximum adsorption capacity attained 0.5-0.6 mmol/g of nitrate and adsorption affinity was 3.5-4.0 L/mmol at pH e 2.5 for Ox-9.5AG.

Macrophyte presence is an indicator of enhanced denitrification and nitrification in sediments of a temperate restored agricultural stream

Science.gov (United States)

Stream macrophytes are often removed with their sediments to deepen stream channels, stabilize channel banks, or provide habitat for target species. These sediments may support enhanced nitrogen processing. To evaluate sediment nitrogen processing, identify seasonal patterns, and...

Enhanced removal of Methylene Blue by electrocoagulation using iron electrodes

OpenAIRE

Mohamed S. Mahmoud; Joseph Y. Farah; Taha E. Farrag

2013-01-01

The removal of pollutants from effluents by electrocoagulation has become an attractive method in recent years. The study deals with the enhancement of removal of Methylene Blue dye by using an electromagnetic field during the electrocoagulation process. Effects of electrolyte concentration, dye concentration, intensity and the direction of the electromagnet on the decolorization efficiency have been investigated. The formed ferric hydroxide flocs trap colloidal particles and make solid–liqui...

Enhancing arsenic removal from groundwater at household level with naturally occurring iron

Directory of Open Access Journals (Sweden)

Anitha Kumari Sharma

2016-06-01

Full Text Available A supply of drinking water low in Arsenic (As prevents arsenic poisoning. The presence of high concentrations of iron (Fe in groundwater under the alluvial plains of the large rivers in Southeast Asia is a prerequisite for the simple removal of As. This study investigated the mechanisms and possibilities for enhancing As removal with naturally occurring Fe in a reliable, low cost and sustainable way. The results of the study show that As removal with Fe is greatly enhanced by the addition of an oxidizing agent (preferably KMnO4 immediately after the pumping of groundwater. Further enhancement of As removal in the presence of Fe can be achieved by adding a small volume of a concentrated basic solution of MnO4- and AlO2-, which has a combined oxidation, coagulation and buffering capacity. Best results were obtained when this solution was mixed with the groundwater immediately after its pumping until a pale pink color appeared. Maximum required reaction time was 10 minutes and subsequent filtration of the water was able to reduce the As concentration to near zero. Concentrations of MnO4- and AlO2- can be varied in the solution to achieve sufficient As removal to suit different Fe/As ratios and the presence of interfering co-occurring anions.

Nitrogen and Organics Removal during Riverbank Filtration along a Reclaimed Water Restored River in Beijing, China

Directory of Open Access Journals (Sweden)

Weiyan Pan

2018-04-01

Full Text Available Reclaimed water has been widely used to restore rivers and lakes in water scarce areas as well as in Beijing municipality, China. However, refilling the rivers with reclaimed water may result in groundwater pollution. A three-year field monitoring program was conducted to assess the effect of a riverbank filtration (RBF system on the removal of nitrogen and organics from the Qingyang River of Beijing, which is replenished with reclaimed water. Water samples from the river, sediment, and groundwater were collected for NO3-N, NH4-N, and chemical oxygen demand (COD was measured. The results indicate that about 85% of NO3-N was removed from the riverbed sediments. Approximate 92% of NH4-N was removed during the infiltration of water from river to aquifer. On average, 54% of COD was removed by RBF. The attenuation of NO3-N through RBF to the groundwater varied among seasons and was strongly related to water temperature. On the other hand, no obvious temporal variability was identified in the removal of COD. These results suggest that the RBF system is an effective barrier against NO3-N, NH4-N and COD in the Qingyang River, as well as those rivers with similar geological and climatic conditions refilled with reclaimed water.

Inside Story of Gas Processes within Stormwater Biofilters: Does Greenhouse Gas Production Tarnish the Benefits of Nitrogen Removal?

Science.gov (United States)

Payne, Emily G I; Pham, Tracey; Cook, Perran L M; Deletic, Ana; Hatt, Belinda E; Fletcher, Tim D

2017-04-04

Stormwater biofilters are dynamic environments, supporting diverse processes that act to capture and transform incoming pollutants. However, beneficial water treatment processes can be accompanied by undesirable greenhouse gas production. This study investigated the potential for nitrous oxide (N 2 O) and methane (CH 4 ) generation in dissolved form at the base of laboratory-scale stormwater biofilter columns. The influence of plant presence, species, inflow frequency, and inclusion of a saturated zone and carbon source were studied. Free-draining biofilters remained aerobic with negligible greenhouse gas production during storm events. Designs with a saturated zone were oxygenated at their base by incoming stormwater before anaerobic conditions rapidly re-established, although extended dry periods allowed the reintroduction of oxygen by evapotranspiration. Production of CH 4 and N 2 O in the saturated zone varied significantly in response to plant presence, species, and wetting and drying. Concentrations of N 2 O typically peaked rapidly following stormwater inundation, associated with limited plant root systems and poorer nitrogen removal from biofilter effluent. Production of CH 4 also commenced quickly but continued throughout the anaerobic interevent period and lacked clear relationships with plant characteristics or nitrogen removal performance. Dissolved greenhouse gas concentrations were highly variable, but peak concentrations of N 2 O accounted for nitrogen load. While further work is required to measure surface emissions, the potential for substantial release of N 2 O or CH 4 in biofilter effluent appears relatively low.

Nitrogen removal and recovery from lagoon-pretreated swine wastewater by constructed wetlands under sustainable plant harvesting management.

Science.gov (United States)

Luo, Pei; Liu, Feng; Zhang, Shunan; Li, Hongfang; Yao, Ran; Jiang, Qianwen; Xiao, Runlin; Wu, Jinshui

2018-06-01

A series of three-stage pilot-scale surface flow constructed wetlands (CWs) planted with Myriophyllum aquaticum were fed with three strengths of lagoon-pretreated swine wastewater to study nitrogen (N) removal and recovery under sustainable plant harvesting management. The CWs had mean removal efficiency of 87.7-97.9% for NH 4 + -N and 85.4-96.1% for total N (TN). The recovered TN mass via multiple harvests of M. aquaticum was greatest (120-222 g N m -2  yr -1 ) when TN concentrations were 21.8-282 mg L -1 . The harvested TN mass accounted for 0.85-100% of the total removal in the different CW units. Based on mass balance estimation, plant uptake, sediment storage, and microbial removal accounted for 13.0-55.0%, 4.9-8.0%, and 33.0-67.5% of TN loading mass, respectively. The results of this study confirm that M. aquaticum is appropriate for the removal and recovery of nutrients in CW systems designed for treating swine wastewater in conjunction with sustainable plant harvesting strategies. Copyright © 2018 Elsevier Ltd. All rights reserved.

Engineering Surfaces for Enhanced Nucleation and Droplet Removal During Dropwise Condensation

Science.gov (United States)

Dutta, Sanmitra; Khan, Sameera; Anand, Sushant

2017-11-01

Condensation plays critical role in numerous industrial applications, such as condensers, HVAC,etc In the most applications, fast formation (i.e. high nucleation) and subsequent removal of water droplets is critical for enhancing the efficiencies of their associated systems. Significant focus has been placed on the aspect of droplet removal from surfaces. This has led to, development of superhydrophobic surfaces with special textures on which droplets are self-removed after coalescence. However,because of their inherent low surface energy, nucleation energy barriers are also high on such surfaces. In contrast to conventional superhydrophobic surfaces, here we show that surfaces can be engineered such that the simultaneous benefits of high nucleation rates and fast droplet removal can be obtained during the condensation process.These benefits are obtained by impregnating a superhydrophobic surface with an oil that despite its defect-free interface provides low nucleation energy barrier during condensation. At the same time, the oil facilitates high droplet shedding rates by providing a lubricating layer below the droplets due to which droplets have negligible contact angle hysteresis. We provide a guide to choose oils that lead to enhanced nucleation, and provide experimental evidence supporting the proposed guide. We discuss the importance of different oil properties in affecting the droplet growth and subsequent removal of water droplets.

Effects of Selected Root Exudate Components on Nitrogen Removal and Development of Denitrifying Bacteria in Constructed Wetlands

Directory of Open Access Journals (Sweden)

Hailu Wu

2017-06-01

Full Text Available Root exudates, particularly low molecular weight carbon (LMWC substrates, are major drivers of bacterial diversity and activity in the rhizosphere environment. However, it is not well understood how specific LMWC compounds—such as organic acids, soluble sugars, and amino acids—influence the community structures of denitrifying bacteria or if there are specific functions of LMWC substrates that preferentially respond to nitrogen (N removal in constructed wetlands (CWs. To address these knowledge gaps, we added mixtures of artificial exudates to CW microcosms containing N pollutant. N removal efficiency was observed over a 48-h experimental period, and at the end of the experiment, DNA was extracted from microbial samples for assessment of the bacterial community. The removal efficiencies of TN for the exudates treatments were higher than for control groups by 47.1–58.67%. Organic acid and soluble sugar treatments increased N removal, while amino acids were negative to N removal. The microbial community was changed when artificial exudates were added, but there were no significant relationships between LMWC compounds and bacterial community composition. These results indicate that although the responses of community structures of denitrifying bacteria to LMWC additions are still uncertain, there is evidence for N removal in response to exudate additions across LMWC types.

Benchmarking Biological Nutrient Removal in Wastewater Treatment Plants

DEFF Research Database (Denmark)

Flores-Alsina, Xavier; Gernaey, Krist; Jeppsson, Ulf

2011-01-01

This paper examines the effect of different model assumptions when describing biological nutrient removal (BNR) by the activated sludge models (ASM) 1, 2d & 3. The performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) benchmark wastewater treatment plant...

Nitrogen Retention in Coastal Marine Sediments—a Field Study of the Relative Importance of Biological and Physical Removal in a Danish Estuary

DEFF Research Database (Denmark)

Laurentius Nielsen, Søren; Risgaard-Petersen, Nils; Banta, Gary

2017-01-01

The aim of this study was to elucidate the relative importance of physical versus biological loss processes for the removal of microphytobenthic (MPB) bound nitrogen in a coastal environment at different times of the year via a dual isotope labeling technique. We used 51Cr, binding to inorganic...... were able to discern the relative importance of physical and biological processes. The isotope marking was supplemented with measurements of sediment chlorophyll biomass and oxygen fluxes, allowing us to evaluate MPB biomass as well as primary production vs. respiration in the sediment. In spring...... was physically dominated due to low MPB biomasses and activity combined with a significant storm event. Our data support the hypothesis that the relative balance between physical and biological processes in determining retention and removal of MPB-bound nitrogen changes seasonally....

Reduction of nitrogen: Finnish state of the art

International Nuclear Information System (INIS)

Maekelae, Markku

1987-01-01

In Finland nitrogen has been considered of importance as a limiting growth factor in some coastal areas and heavily polluted lakes. For the present, however, the usefulness of nitrogen removal in municipal wastewater treatment has not beep clear enough and requirements concerning removal of total nitrogen have not been set. The need for nitrogen removal depends mainly on the local conditions. On the coastal regions, nitrogen removal should be started first in the biggest of those municipalities which are loading the Gulf of Finland and the Archipelago Sea. The city of Helsinki has to be prepared for nitrogen removal before the end of the next decade. The adverse effects of ammonia are apparent in many inland water courses. In recent years reduction of ammonia nitrogen in wastewater treatment has been required in some cases, mainly in order to prevent oxygen depletion caused by nitrification in receiving waters. Other important reasons for ammonia reduction have been the adverse effects of ammonia in water supply and the toxic effects of molecular ammonia on fish. In practice, ammonia removal has been performed by nitrification in connection with the activated sludge process. The choice of process combinations and design values have always been based on pilot plant or full scale experiments. In order to reach a sludge retention time long enough during the cold season, the design values of sludge load have been 0.06-0.08 kg BOD 7 /kg MLSS·d in combined carbon oxidation and nitrification processes. At new nitrification plants, denitrification has been used for diminishing the operation costs. (author)

Role of iron catalyst impregnated by solvent swelling method in pyrolytic removal of coal nitrogen

Energy Technology Data Exchange (ETDEWEB)

Hayashi, J.; Kusakabe, K.; Morooka, S.; Nielsen, M.; Furimsky, E. [Kyushu University, Fukuoka (Japan). Dept. of Chemical Science and Technology

1995-11-01

Organometallic iron precursors, ferrocene and ferric acetate, were impregnated into Illinois No. 6 (IL), Wyoming (WY) and Yallourn (YL) coals by solvent swelling technique in THF, ethanol, and a THF/ethanol binary solvent. Then iron-impregnated coals were pyrolyzed in a flow of helium at atmospheric pressure in a fixed bed and a thermobalance. Conversion of coal nitrogen to N{sub 2} was 20, 38 and 30% respectively, for original IL, WY, and YL coals. Iron formed from both precursors lowered the onset temperature of N{sub 2} evolution by 20-100{degree}C. When ferrocene was impregnated in coals at a concentration of 1.7-1.8 wt% as Fe, nitrogen conversion was increased to 52, 71 and 68% for IL, WY and YL coals, respectively. Ferric acetate impregnated into IL coal from THF/ethanol solution increased the nitrogen conversion much more than that from ethanol solution. The expansion of microporous coal structure by the swelling was essential for better dispersion of the catalyst precursor. The evolution of HCN as well as NH{sub 3} was effectively suppressed above 600{degree}C by the presence of iron but not influenced significantly by combinations of catalyst precursors and solvents. The increase in N{sub 2} yield was compensated by the decrease in nitrogen emitted as HCN and NH{sub 3} and in tar and char. The increase in CO evolution from the iron-impregnated IL coal at 600-800{degree}C was explained by catalytic rearrangement of aromatic structure of char, accompanying the removal of nitrogen as N{sub 2}. In a range of 600-750{degree}C, the evolution of CO as well as N{sub 2} from the other coals increased remarkably with a significant decrease in CO{sub 2} gasification in char microproes. 32 refs., 9 figs., 3 tabs.

Nitrogen Removal Characteristics of Pseudomonas putida Y-9 Capable of Heterotrophic Nitrification and Aerobic Denitrification at Low Temperature

Directory of Open Access Journals (Sweden)

Yi Xu

2017-01-01

Full Text Available The cold-adapted bacterium Pseudomonas putida Y-9 was investigated and exhibited excellent capability for nitrogen removal at 15°C. The strain capable of heterotrophic nitrification and aerobic denitrification could efficiently remove ammonium, nitrate, and nitrite at an average removal rate of 2.85 mg, 1.60 mg, and 1.83 mg NL−1 h−1, respectively. Strain Y-9 performed nitrification in preference to denitrification when ammonium and nitrate or ammonium and nitrite coexisted in the solution. Meantime, the presence of nitrate had no effect on the ammonium removal rate of strain Y-9, and yet the presence of high concentration of nitrite would inhibit the cell growth and decrease the nitrification rate. The experimental results indicate that P. putida Y-9 has potential application for the treatment of wastewater containing high concentrations of ammonium along with its oxidation products at low temperature.

Hybrid disposal systems and nitrogen removal in individual sewage disposal systems

Energy Technology Data Exchange (ETDEWEB)

Franks, A.L.

1993-06-01

The use of individual disposal systems in ground-water basins that have adverse salt balance conditions and/or geologically unsuitable locations, has become a major problem in many areas of the world. There has been much research in design of systems for disposal of domestic sewage. This research includes both hybrid systems for disposal of domestic sewage. This research includes both hybrid systems for disposal of the treated waste in areas with adverse geologic conditions and systems for the removal of nitrogen and phosphorus prior to percolation to the ground water. This paper outlines the history of development and rationale for design and construction of individual sewage disposal systems and describes the designs and limitations of the hybrid and denitrification units. The disposal systems described include Mounds, Evapotranspiration and Evapotranspiration/Infiltration systems. The denitrification units include those using methanol, sulfur and limestone, gray water and secondary treated wastewater for energy sources.

Potential and costs of carbon dioxide removal by enhanced weathering of rocks

Science.gov (United States)

Strefler, Jessica; Amann, Thorben; Bauer, Nico; Kriegler, Elmar; Hartmann, Jens

2018-03-01

The chemical weathering of rocks currently absorbs about 1.1 Gt CO2 a-1 being mainly stored as bicarbonate in the ocean. An enhancement of this slow natural process could remove substantial amounts of CO2 from the atmosphere, aiming to offset some unavoidable anthropogenic emissions in order to comply with the Paris Agreement, while at the same time it may decrease ocean acidification. We provide the first comprehensive assessment of economic costs, energy requirements, technical parameterization, and global and regional carbon removal potential. The crucial parameters defining this potential are the grain size and weathering rates. The main uncertainties about the potential relate to weathering rates and rock mass that can be integrated into the soil. The discussed results do not specifically address the enhancement of weathering through microbial processes, feedback of geogenic nutrient release, and bioturbation. We do not only assess dunite rock, predominantly bearing olivine (in the form of forsterite) as the mineral that has been previously proposed to be best suited for carbon removal, but focus also on basaltic rock to minimize potential negative side effects. Our results show that enhanced weathering is an option for carbon dioxide removal that could be competitive already at 60 US  t-1 CO2 removed for dunite, but only at 200 US  t-1 CO2 removed for basalt. The potential carbon removal on cropland areas could be as large as 95 Gt CO2 a-1 for dunite and 4.9 Gt CO2 a-1 for basalt. The best suited locations are warm and humid areas, particularly in India, Brazil, South-East Asia and China, where almost 75% of the global potential can be realized. This work presents a techno-economic assessment framework, which also allows for the incorporation of further processes.

Enhanced coagulation for turbidity and Total Organic Carbon (TOC) removal from river Kansawati water.

Science.gov (United States)

Narayan, Sumit; Goel, Sudha

2011-01-01

The objective of this study was to determine optimum coagulant doses for turbidity and Total Organic Carbon (TOC) removal and evaluate the extent to which TOC can be removed by enhanced coagulation. Jar tests were conducted in the laboratory to determine optimum doses of alum for the removal of turbidity and Natural Organic Matter (NOM) from river water. Various other water quality parameters were measured before and after thejar tests and included: UV Absorbance (UVA) at 254 nm, microbial concentrations, TDS, conductivity, hardness, alkalinity, and pH. The optimum alum dose for removal of turbidity and TOC was 20 mg/L for the sample collected in November 2009 and 100 mg/L for the sample collected in March 2010. In both cases, the dose for enhanced coagulation was significantly higher than that for conventional coagulation. The gain in TOC removal was insignificant compared to the increase in coagulant dose required. This is usual for low TOC (TOC need to be tested to demonstrate the effectiveness of enhanced coagulation.

Study of Modern Nano Enhanced Techniques for Removal of Dyes and Metals

Directory of Open Access Journals (Sweden)

Samavia Batool

2014-01-01

Full Text Available Industrial effluent often contains the significant amount of hexavalent chromium and synthetic dyes. The discharge of wastewater without proper treatment into water streams consequently enters the soil and disturbs the aquatic and terrestrial life. A range of wastewater treatment technologies have been proposed which can efficiently reduce both Cr(VI and azo dyes simultaneously to less toxic form such as biodegradation, biosorption, adsorption, bioaccumulation, and nanotechnology. Rate of simultaneous reduction of Cr(VI and azo dyes can be enhanced by combining different treatment techniques. Utilization of synergistic treatment is receiving much attention due to its enhanced efficiency to remove Cr(VI and azo dye simultaneously. This review evaluates the removal methods for simultaneous removal of Cr(VI and azo dyes by nanomicrobiology, surface engineered nanoparticles, and nanophotocatalyst. Sorption mechanism of biochar for heavy metals and organic contaminants is also discussed. Potential microbial strains capable of simultaneous removal of Cr(VI and azo dyes have been summarized in some details as well.

Effect of phosphorus on biodiesel production from Scenedesmus obliquus under nitrogen-deficiency stress.

Science.gov (United States)

Chu, Fei-Fei; Chu, Pei-Na; Shen, Xiao-Fei; Lam, Paul K S; Zeng, Raymond J

2014-01-01

In order to study the effect of phosphorus on biodiesel production from Scenedesmus obliquus especially under nitrogen deficiency conditions, six types of media with combinations of nitrogen repletion/depletion and phosphorus repletion/limitation/depletion were investigated in this study. It was found that nitrogen starvation compared to nitrogen repletion enhanced biodiesel productivity. Moreover, biodiesel productivity was further strengthened by varying the supply level of phosphorus from depletion, limitation, through to repletion. The maximum FAMEs productivity of 24.2 mg/L/day was obtained in nitrogen depletion with phosphorus repletion, which was two times higher than that in nutrient complete medium. More phosphorus was accumulated in cells under the nitrogen starvation with sufficient phosphorus condition, but no polyphosphate was formed. This study indicated that nitrogen starvation plus sufficient P supply might be the real "lipid trigger". Furthermore, results of the current study suggest a potential application for utilizing microalgae to combine phosphorus removal from wastewater with biodiesel production. Copyright © 2013 Elsevier Ltd. All rights reserved.

Long term effects of cerium dioxide nanoparticles on the nitrogen removal, micro-environment and community dynamics of a sequencing batch biofilm reactor.

Science.gov (United States)

Xu, Yi; Wang, Chao; Hou, Jun; Wang, Peifang; Miao, Lingzhan; You, Guoxiang; Lv, Bowen; Yang, Yangyang; Zhang, Fei

2017-12-01

The influences of cerium dioxide nanoparticles (CeO 2 NPs) on nitrogen removal in biofilm were investigated. Prolonged exposure (75d) to 0.1mg/L CeO 2 NPs caused no inhibitory effects on nitrogen removal, while continuous addition of 10mg/L CeO 2 NPs decreased the treatment efficiency to 53%. With the progressive concentration of CeO 2 NPs addition, the removal efficiency could nearly stabilize at 67% even with the continues spike of 10mg/L. The micro-profiles of dissolved oxygen, pH, and oxidation reduction potential suggested the developed protection mechanisms of microbes to progressive CeO 2 NPs exposure led to the less influence of microenvironment, denitrification bacteria and enzyme activity than those with continuous ones. Furthermore, high throughput sequencing illustrated the drastic shifted communities with gradual CeO 2 NPs spiking was responsible for the adaption and protective mechanisms. The present study demonstrated the acclimated microbial community was able to survive CeO 2 NPs addition more readily than those non-acclimated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Upgrading of the symbiosis of Nitrosomanas and anammox bacteria in a novel single-stage partial nitritation-anammox system: Nitrogen removal potential and Microbial characterization.

Science.gov (United States)

Liu, Yuan; Niu, Qigui; Wang, Shaopo; Ji, Jiayuan; Zhang, Yu; Yang, Min; Hojo, Toshimasa; Li, Yu-You

2017-11-01

A novel single-stage partial nitritation-anammox process equipped with porous functional suspended carriers was developed at 25°C in a CSTR by controlling dissolved oxygen <0.3mg/L. The nitrogen removal performance was almost unchanged over a nitrogen loading rate ranging from 0.5 to 2.5kgNH 4 + -N/m 3 /d with a high nitrogen removal efficiency of 81.1%. The specific activity of AOB and anammox bacteria was of 3.00g-N/g-MLVSS/d (the suspended sludge), 3.56g-N/g-MLVSS/d (the biofilm sludge), respectively. The results of pyrosequencing revealed that Nitrosomonas (5.66%) and Candidatus_Kuenenia (4.95%) were symbiotic in carriers while Nitrosomonas (40.70%) was predominant in the suspended flocs. Besides, two specific types of heterotrophic filamentous bacteria in the suspended flocs (Haliscomenobacter) and the functional carrier biofilm (Longilinea) were shown to confer structural integrity to the aggregates. The novel single-stage partial nitritation-anammox process equipped with functional suspended carriers was shown to have good potential for the nitrogen-rich wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comprehensive evaluation of nitrogen removal rate and biomass, ethanol, and methane production yields by combination of four major duckweeds and three types of wastewater effluent.

Science.gov (United States)

Toyama, Tadashi; Hanaoka, Tsubasa; Tanaka, Yasuhiro; Morikawa, Masaaki; Mori, Kazuhiro

2018-02-01

To assess the potential of duckweeds as agents for nitrogen removal and biofuel feedstocks, Spirodela polyrhiza, Lemna minor, Lemna gibba, and Landoltia punctata were cultured in effluents of municipal wastewater, swine wastewater, or anaerobic digestion for 4 days. Total dissolved inorganic nitrogen (T-DIN) of 20-50 mg/L in effluents was effectively removed by inoculating with 0.3-1.0 g/L duckweeds. S. polyrhiza showed the highest nitrogen removal (2.0-10.8 mg T-DIN/L/day) and biomass production (52.6-70.3 mg d.w./L/day) rates in all the three effluents. Ethanol and methane were produced from duckweed biomass grown in each effluent. S. polyrhiza and L. punctata biomass showed higher ethanol (0.168-0.191, 0.166-0.172 and 0.174-0.191 g-ethanol/g-biomass, respectively) and methane (340-413 and 343-408 NL CH 4 /kg VS, respectively) production potentials than the others, which is related to their higher carbon and starch contents and calorific values. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Population dynamics in wastewater treatment plants with enhanced biological phosphorus removal operated with and without nitrogen removal

DEFF Research Database (Denmark)

Lee, N.; Jansen, J.l.C.; Aspegren, H.

2002-01-01

belonged to the β Proteobacteria, whereas the rest of the clusters belonged either to the Actinobacteria or to the α Proteobacteria. The relative abundance of Rhodocyclus-related bacteria in the activated sludge varied significantly in both systems during the whole period (from 6 to 18% in BNP, and from 4...... Proteobacteria (part of them Rhodocyclus-related, the identity of the rest unknown) and the Actinobacteria. However, not all of the Rhodocyclus-related bacteria showed 33Pi uptake. The P removal in the investigated plants is thus believed to be mediated by a mixed population consisting of a part...... of the Rhodocyclus-related bacteria, the Actinobacteria and other, yet unidentified bacteria....

Synergistic effects of non-thermal plasma-assisted catalyst and ultrasound on toluene removal.

Science.gov (United States)

Sun, Yongli; Zhou, Libo; Zhang, Luhong; Sui, Hong

2012-01-01

A wire-mesh catalyst coated by La0.8Sr0.2MnO3 was combined with a dielectric barrier discharge (DBD) reactor for toluene removal at atmospheric pressure. It was found that toluene removal efficiency and carbon dioxide selectivity were enhanced in the catalytic packed-bed reactor. In addition, ozone and nitrogen monoxide from the gas effluent byproducts decreased. This is the first time that ultrasound combined with plasma has been used for toluene removal. A synergistic effect on toluene removal was observed in the plasma-assisted ultrasound system. At the same time, the system increased toluene conversion and reduced ozone emission.

Removal of organic substances and oxidation of ammonium nitrogen by a down-flow hanging sponge (DHS) reactor under high salinity conditions.

Science.gov (United States)

Uemura, Shigeki; Suzuki, Saori; Abe, Kenichi; Kubota, Keiichi; Yamaguchi, Takashi; Ohashi, Akiyoshi; Takemura, Yasuyuki; Harada, Hideki

2010-07-01

A down-flow hanging sponge (DHS) reactor, constructed by connecting three identical treatment units in series, was fed with highly saline artificial coke-plant wastewater containing 1400 mg L(-1) of phenol in terms of chemical oxygen demand (COD) and 500 mg-NL(-1) of ammonium nitrogen. The COD was removed by the 1st unit, achieving 92% removal at an average COD loading rate of 3.0 kg-COD m(-3)d(-1) for all units, with oxidation of ammonium nitrogen occurring primarily in the two downstream units. Microbial assays of the different units of the reactor revealed greater numbers of nitrifying bacteria in the 2nd and 3rd units than in the 1st unit, corresponding with the observed ammonium oxidation pattern of the reactor. These findings suggest that a succession of microflora was successfully established along the DHS. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level

International Nuclear Information System (INIS)

Wu, Yi-Ting; Yu, Yi-Hui; Nguyen, Van-Huy; Lu, Kung-Te; Wu, Jeffrey Chi-Sheng; Chang, Luh-Maan; Kuo, Chi-Wen

2013-01-01

Graphical abstract: We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. -- Highlights: • The combination of optical fiber and honeycomb significantly enhanced the performance of VOCs photodegradation. • The removal efficiency of m-xylene is enhanced to 96.5% as compared to 22.0% for UV irradiation alone. • Fiber-illuminated honeycomb reactor is the first step toward an industrial-scale technology on the removal of xylene. -- Abstract: The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO 2 photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO 2 selectivity. Interestingly, Mn-TiO 2 in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future

Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level

Energy Technology Data Exchange (ETDEWEB)

Wu, Yi-Ting [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Yu, Yi-Hui [Department of Civil Engineering, National Taiwan University, Taipei 106, Taiwan (China); Nguyen, Van-Huy [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan (China); Lu, Kung-Te [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Wu, Jeffrey Chi-Sheng, E-mail: cswu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Luh-Maan [Department of Civil Engineering, National Taiwan University, Taipei 106, Taiwan (China); Kuo, Chi-Wen [Taiwan Semiconductor Manufacturing Company, Hsinchu 30078, Taiwan (China)

2013-11-15

Graphical abstract: We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. -- Highlights: • The combination of optical fiber and honeycomb significantly enhanced the performance of VOCs photodegradation. • The removal efficiency of m-xylene is enhanced to 96.5% as compared to 22.0% for UV irradiation alone. • Fiber-illuminated honeycomb reactor is the first step toward an industrial-scale technology on the removal of xylene. -- Abstract: The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO{sub 2} photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO{sub 2} selectivity. Interestingly, Mn-TiO{sub 2} in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future.

Denitrification, anammox and fixed nitrogen removal in the water column of a tropical great lake

Science.gov (United States)

Darchambeau, François; Roland, Fleur; Crowe, Sean A.; De Brabandere, Loreto; Llirós, Marc; Garcia-Armisen, Tamara; Inceoglu, Ozgul; Michiels, Céline; Servais, Pierre; Morana, Cédric D. T.; Bouillon, Steven; Meysman, Filip; Veuger, Bart; Masilya, Pascal M.; Descy, Jean-Pierre; Borges, Alberto V.

2013-04-01

If rates of microbial denitrification in aquatic systems are poorly constrained, it is much more the case for tropical water bodies. Lake Kivu [2.50° S 1.59° S, 29.37° E 28.83° E] is one of the great lakes of the East African Rift. It is an oligotrophic lake characterized by anoxic deep waters rich in dissolved gases (methane and carbon dioxide) and nutrients, and by well oxygenated and nutrient-depleted surface waters. During the seasonally stratified rainy season (October to May), a nitrogenous zone characterized by the accumulation of nitrite (NO2-) and nitrate (NO3-) is often observed in the lower layer of the mixolimnion. It results from nitrification of ammonium released by decaying organic matter. With the seasonal uplift of the oxygen minimum zone, the nitrogenous zone becomes anoxic and might be the most preferential area for fixed nitrogen (N) removal in Lake Kivu. Our work aimed at identifying and quantifying the processes of N losses by denitrification and/or anammox in the nitrogenous zone of the Lake Kivu water column. During 5 sampling campaigns (March 2010, October 2010, June 2011, February 2012 and September 2012), isotopic labelling experiments were used to quantify denitrification and anammox rates along vertical profiles at two pelagic stations of the main lake. Moreover, N2:Ar ratios were estimated during the September 2012 campaign, and 16S rDNA pyrosequencing was used to describe bacterial community composition during the last 2 campaigns. No bacteria related to organisms performing anammox was observed and labelling experiments failed to detect anammox at any locations and any depths. In Lake Kivu, denitrifying bacteria were mainly related to Denitratisoma and Thiobacillus genus. Significant denitrification rates were observed at several occasions, especially under the oxic-anoxic interface in the bottom of the nitracline. The annual average denitrification rate was estimated at ~150 μmoles N m-2 d-1. Denitrification was not the only

A new mathematical model for nitrogen gas production with special emphasis on the role of attached growth media in anammox hybrid reactor.

Science.gov (United States)

Tomar, Swati; Gupta, Sunil Kumar

2015-11-01

The present study emphasised on the development of new mathematical models based on mass balance and stoichiometry of nitrogen removal in anammox hybrid reactor (AHR). The performance of AHR at varying hydraulic retention times (HRTs) and nitrogen loading rates (NLRs) revealed that nitrogen removal efficiency (NRE) increases with increase in HRT and was found optimal (89 %) at HRT of 2 days. Mass balance of nitrogen revealed that major fraction (74.1 %) of input nitrogen is converted into N2 gas followed by 11.2 % utilised in biomass synthesis. Attached growth media (AGM) in AHR contributed to an additional 15.4 % ammonium removal and reduced the sludge washout rate by 29 %. This also enhanced the sludge retention capacity of AHR and thus minimised the formation of nitrate in the treated effluent, which is one of the bottlenecks of anammox process. Process kinetics was also studied using various mathematical models. The mass balance model derived from total nitrogen was found most precise and predicted N2 gas with least error (1.68 ± 4.44 %). Model validation for substrate removal kinetics dictated comparatively higher correlation for Grau second-order model (0.952) than modified Stover-Kincannon model (0.920). The study concluded that owing to features of high biomass retention, less nitrate formation and consistently higher nitrogen removal efficiency, this reactor configuration is techno-economically most efficient and viable. The study opens the door for researchers and scientists for pilot-scale testing of AHR leading to its wide industrial application.

Nitrogen removal and nitrate leaching for two perennial, sod-based forage systems receiving dairy effluent.

Science.gov (United States)

Woodard, Kenneth R; French, Edwin C; Sweat, Lewin A; Graetz, Donald A; Sollenberger, Lynn E; Macoon, Bisoondat; Portier, Kenneth M; Rymph, Stuart J; Wade, Brett L; Prine, Gordon M; Van Horn, Harold H

2003-01-01

In northern Florida, year-round forage systems are used in dairy effluent sprayfields to reduce nitrate leaching. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentration below the rooting zone for two perennial, sod-based, triple-cropping systems over four 12-mo cycles (1996-2000). The soil is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzip-samment). Effluent N rates were 500, 690, and 910 kg ha(-1) per cycle. Differences in N removal between a corn (Zea mays L.)-bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (CBR) and corn-perennial peanut (Arachis glabrata Benth.)-rye system (CPR) were primarily related to the performance of the perennial forages. Nitrogen removal of corn (125-170 kg ha(-1)) and rye (62-90 kg ha(-1)) was relatively stable between systems and among cycles. The greatest N removal was measured for CBR in the first cycle (408 kg ha(-1)), with the bermudagrass removing an average of 191 kg N ha(-1). In later cycles, N removal for bermudagrass declined because dry matter (DM) yield declined. Yield and N removal of perennial peanut increased over the four cycles. Nitrate N concentrations below the rooting zone were lower for CBR than CPR in the first two cycles, but differences were inconsistent in the latter two. The CBR system maintained low NO3(-)-N leaching in the first cycle when the bermudagrass was the most productive; however, it was not a sustainable system for long-term prevention of NO3(-)-N leaching due to declining bermudagrass yield in subsequent cycles. For CPR, effluent N rates > or = 500 kg ha(-1) yr(-1) have the potential to negatively affect ground water quality.

Predicting Bacteria Removal by Enhanced Stormwater Control Measures (SCMs) at the Watershed Scale

Science.gov (United States)

Wolfand, J.; Bell, C. D.; Boehm, A. B.; Hogue, T. S.; Luthy, R. G.

2017-12-01

Urban stormwater is a major cause of water quality impairment, resulting in surface waters that fail to meet water quality standards and support their designated uses. Fecal indicator bacteria are present in high concentrations in stormwater and are strictly regulated in receiving waters; yet, their fate and transport in urban stormwater is poorly understood. Stormwater control measures (SCMs) are often used to treat, infiltrate, and release urban runoff, but field measurements show that the removal of bacteria by these structural solutions is limited (median log removal = 0.24, n = 370). Researchers have therefore looked to improve bacterial removal by enhancing SCMs through alterations in flow regimes or adding geomedia such as biochar. The present research seeks to develop a model to predict removal of fecal indicator bacteria by enhanced SCMs at the watershed scale in a semi-arid climate. Using the highly developed Ballona Creek watershed (290 km2) located in Los Angeles County as a case study, a hydrologic model is coupled with a stochastic water quality model to predict E. coli concentration near the outfall of the Ballona Creek, Santa Monica Bay. A hydrologic model was developed using EPA SWMM, calibrated for flow from water year 1998-2006 (NSE = 0.94; R2 = 0.94), and validated from water year 2007-2015 (NSE = 0.90; R2 = 0.93). This bacterial loading model was then linked to EPA SUSTAIN and a SCM bacterial removal script to simulate log removal of bacteria by various SCMs and predict bacterial concentrations in Ballona Creek. Preliminary results suggest small enhancements to SCMs that improve bacterial removal (<0.5 log removal) may offer large benefits to surface water quality and enable communities such as Los Angeles to meet their regulatory requirements.

Enhanced nitrogen selectivity for nitrate reduction on Cu–nZVI by TiO{sub 2} photocatalysts under UV irradiation

Energy Technology Data Exchange (ETDEWEB)

Krasae, Nalinee, E-mail: k_nalinee@kkumail.com [Department of Chemical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Chemical Kinetics and Applied Catalysis Laboratory (CKCL), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Wantala, Kitirote, E-mail: kitirote@kku.ac.th [Department of Chemical Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Chemical Kinetics and Applied Catalysis Laboratory (CKCL), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand); Research Center for Environmental and Hazardous Substance Management (EHSM), Faculty of Engineering, Khon Kaen University, Khon Kaen 40002 (Thailand)

2016-09-01

Highlights: • Photocatalytic process has been enhancing the nitrate removal over Cu–nZVI/TiO{sub 2}. • Highly nitrogen selectivity more than 80% over Cu–nZVI/TiO{sub 2}. • Nitrate removal can be reacted in neutral pH of solutions. - Abstract: The aims of this work were to study the effect of Cu–nZVI with and without TiO{sub 2} on nitrate reduction and to study the pathway of nitrate reduction utilizing to nitrogen gas. The chemical and physical properties of Cu–nZVI and Cu–nZVI/TiO{sub 2} such as specific surface area, crystalline phase, oxidation state of Cu and Fe and morphology were determined by N{sub 2} adsorption–desorption Brunauer–Emmett–Teller (BET) analytical technique, X-ray diffraction (XRD), X-ray Absorption Near Edge Structure (XANES) technique and Transmittance Electron Microscopy (TEM). The full factorial design (FFD) was used in this experiment for the effect of Cu–nZVI with and without TiO{sub 2}, where the initial solution pH was varied at 4, 5.5, and 7 and initial nitrate concentration was varied at 50, 75, and 100 ppm. Finally, the pathway of nitrate reduction was examined to calculate the nitrogen gas selectivity. The specific area of Cu–nZVI and Cu–nZVI/TiO{sub 2} was found to be about 4 and 36 m{sup 2}/g, respectively. The XRD pattern of Fe{sup 0} in Cu–nZVI was found at 45° (2θ), whereas Cu–nZVI/TiO{sub 2} cannot be observed. TEM images can confirm the position of the core and the shell of nZVI for Fe{sup 0} and ferric oxide. Cu–nZVI/TiO{sub 2} proved to have higher activity in nitrogen reduction performance than that without TiO{sub 2} and nitrate can be completely degraded in both of solution pH of 4 and 7 in 75 ppm of initial nitrate concentration. It can be highlighted that the nitrogen gas selectivity of Cu–nZVI/TiO{sub 2} greater than 82% was found at an initial solution pH of 4 and 7. The main effects of Cu–nZVI with and without TiO{sub 2} and the initial nitrate concentration on nitrate

[Identification and Nitrogen Removal Characteristics of a Heterotrophic Nitrification-Aerobic Denitrification Strain Isolated from Marine Environment].

Science.gov (United States)

Sun, Qing-hua; Yu, De-shuang; Zhang, Pei-yu; Lin, Xue-zheng; Li, Jin

2016-02-15

A heterotrophic nitrification-aerobic denitrification strain named y5 was isolated from marine environment by traditional microbial isolation method using seawater as medium. It was identified as Klebsiella sp. based on the morphological, physiological and 16S rRNA sequence analysis. The experiment results showed that the optimal carbon resource was sodium citrate; the optimal pH was 7.0; and the optimal C/N was 17. The strain could use NH4Cl, NaNO2 and KNO3 as sole nitrogen source, and the removal efficiencies were77.07%, 64.14% and 100% after 36 hours, respectively. The removal efficiency reached 100% after 36 hours in the coexistence of NH4Cl, NaNO2 and KNO3. The results showed that the strain y5 had independent and efficient heterotrophic nitrification and aerobic denitrification activities in high salt wastewater.

Bioprocesses for removal of carbon dioxide and nitrogen oxide by microalgae for the utilization of gas generated during coal burning

Energy Technology Data Exchange (ETDEWEB)

Morais, Michele Greque de; Costa, Jorge Alberto Vieira [Fundacao Universidade Federal do Rio Grande, Rio Grande (Brazil)

2008-07-01

The aim of this work was to study the removal of CO{sub 2} and NO by microalgae and to evaluate the kinetic characteristics of the cultures. Spirulina sp. showed {mu}{sub max} and X{sub max} (0.11 d{sup -1}, 1.11 g L{sup -1} d{sup -1}) when treated with CO{sub 2} and NaNO{sub 3}. The maximum CO{sub 2} removal was 22.97% for S. obliquus treated with KNO{sub 3} and atmospheric CO{sub 2}. The S. obliquus showed maximum NO removal (21.30%) when treated with NO and CO{sub 2}. Coupling the cultivation of these microalgae with the removal of CO{sub 2} and NO has the potential not only to reduce the costs of culture media but also to offset carbon and nitrogen emissions. 19 refs., 3 figs., 2 tabs.

A system for removing both oxygen and nitrogen from a rare gas-hydrocarbon mixture

International Nuclear Information System (INIS)

Dijkman, W.H.

1989-01-01

A study has been made how to remove nitrogen from a mixture of a rare gas and a hydrocarbon in addition to the removal of oxygen, H 2 O and gaseous oxides. The purpose was to find a simple method for the purification of drift-chamber gases in a recirculation system. Such a method would reduce the operating costs of the large detectors presently constructed for LEP. A promising technique has been developed. First results of a chemical reactor using the novel technique are presented. The N 2 content of Ar/air mixtures containing up to 28% air could be reduced to a level of 20 ppm at a flow rate of 0.11 m 3 /h (200 ppm at 1.0 m 3 /h); and the O 2 content to 30 and 300 ppm respectively. Water and gaseous oxides concentrations were always below 5 ppm. Some of the practical problems still to be solved are discussed and suggestions are given for further development and applications. The method can in principle be of more general use. (orig.)

Catalytic pleat filter bags for combined particulate separation and nitrogen oxides removal from flue gas streams

International Nuclear Information System (INIS)

Park, Young Ok; Choi, Ho Kyung

2010-01-01

The development of a high temperature catalytically active pleated filter bag with hybrid filter equipment for the combined removal of particles and nitrogen oxides from flue gas streams is presented. A special catalyst load in stainless steel mesh cartridge with a high temperature pleated filter bag followed by optimized catalytic activation was developed to reach the required nitrogen oxides levels and to maintain the higher collection efficiencies. The catalytic properties of the developed high temperature filter bags with hybrid filter equipment were studied and demonstrated in a pilot scale test rig and a demonstration plant using commercial scale of high temperature catalytic pleated filter bags. The performance of the catalytic pleated filter bags were tested under different operating conditions, such as filtration velocity and operating temperature. Moreover, the cleaning efficiency and residual pressure drop of the catalyst loaded cartridges in pleated filter bags were tested. As result of theses studies, the optimum operating conditions for the catalytic pleated filter bags are determined. (author)

Forest fuel reduces the nitrogen load

International Nuclear Information System (INIS)

Lundborg, A.

1993-03-01

A study of the literature was made on the basis of the following hypothesis: ''If nitrogen-rich felling residues are removed from the forest, the nitrogen load on the forest ecosystem is decreased and the risk of nitrogen saturation also decreases''. The study was designed to provide information on how the nitrogen situation is influenced if felling residues are removed from nitrogen-loaded forests and used as fuel. Felling residues release very little nitrogen during the first years after felling. They can immobilize nitrogen from the surroundings, make up a considerable addition to the nitrogen store in the soil, but also release nitrogen in later stages of degradation. The slash has an influence on the soil climate and thus on soil processes. Often there is an increase in the mineralization of litter and humus below the felling residues. At the same time, nitrification is favoured, particularly if the slash is left in heaps. Felling residues contain easily soluble nutrients that stimulate the metabolization of organic matter that otherwise is rather resistant to degradation. The slash also inhibits the clear-cut vegetation and its uptake of nitrogen. These effects result in increased leaching of nitrogen and minerals if the felling residues are left on the site. (99 refs.)

Energy saving processes for nitrogen removal in organic wastewater from food processing industries in Thailand.

Science.gov (United States)

Johansen, N H; Suksawad, N; Balslev, P

2004-01-01

Nitrogen removal from organic wastewater is becoming a demand in developed communities. The use of nitrite as intermediate in the treatment of wastewater has been largely ignored, but is actually a relevant energy saving process compared to conventional nitrification/denitrification using nitrate as intermediate. Full-scale results and pilot-scale results using this process are presented. The process needs some additional process considerations and process control to be utilized. Especially under tropical conditions the nitritation process will round easily, and it must be expected that many AS treatment plants in the food industry already produce NO2-N. This uncontrolled nitrogen conversion can be the main cause for sludge bulking problems. It is expected that sludge bulking problems in many cases can be solved just by changing the process control in order to run a more consequent nitritation. Theoretically this process will decrease the oxygen consumption for oxidation by 25% and the use of carbon source for the reduction will be decreased by 40% compared to the conventional process.

Biostimulation strategies to enhance manganese removal in drinking water biofilters

DEFF Research Database (Denmark)

Breda, Inês Lousinha Ribeiro; Ramsay, Loren; Søborg, Ditte

to national drinking water criteria. The period during which virgin filter media matures into a fully functional biofilter is designated as the start-up period. The duration of a start-up for efficient manganese removal varies from weeks to more than a year. The aim of this study was to investigate...... growth and activity of specific bacteria. Biostimulation of virgin media to enhance initial manganese removal using different amendments strategies is possible especially in the early stages of filter development whereas autocatalytic processes appear to become dominant with time. The complex...

Comparison of nitrogen removal rates and nitrous oxide production from enriched anaerobic ammonium oxidizing bacteria in suspended and attached growth reactors.

Science.gov (United States)

Panwivia, Supaporn; Sirvithayapakorn, Sanya; Wantawin, Chalermraj; Noophan, Pongsak Lek; Munakata-Marr, Junko

2014-01-01

Attached growth-systems for the anaerobic ammonium oxidation (anammox) process have been postulated for implementation in the field. However, information about the anammox process in attached growth-systems is limited. This study compared nitrogen removal rates and nitrous oxide (N2O) production of enriched anammox cultures in both suspended and attached growth sequencing batch reactors (SBRs). Suspended growth reactors (SBR-S) and attached growth reactors using polystyrene sponge as a medium (SBR-A) were used in these experiments. After inoculation with an enriched anammox culture, significant nitrogen removals of ammonium (NH4 (+)) and nitrite (NO2 (-)) were observed under NH4 (+):NO2 (-) ratios ranging from 1:1 to 1:2 in both types of SBRs. The specific rates of total nitrogen removal in SBR-S and SBR-A were 0.52 mg N/mg VSS-d and 0.44 mg N/mg VSS-d, respectively, at an NH4 (+):NO2 (-) ratio of 1:2. N2O production by the enriched anammox culture in both SBR-S and SBR-A was significantly higher at NH4 (+):NO2 (-) ratio of 1:2 than at NH4 (+):NO2 (-) ratios of 1:1 and 1:1.32. In addition, N2O production was higher at a pH of 6.8 than at pH 7.3, 7.8, and 8.3 in both SBR-S and SBR-A. The results of this investigation demonstrate that the anammox process may avoid N2O emission by maintaining an NH4 (+):NO2 (-) ratio of less than 1:2 and pH higher than 6.8.

New perspectives for the petroleum industry. Bioprocesses for the selective removal of sulphur, nitrogen and metals

International Nuclear Information System (INIS)

Zerlia, T.

2000-01-01

Fuel biocatalytic conversion is a process that removes, through selective enzyme-catalyzed reactions, sulphur, nitrogen and metals. The mild operating conditions, the specificity of reactions and the quality of coproducts (particularly the organo sulphur compounds, a source for the petrochemical industry) are just a few of the attractive aspects of this new technology which could open a new world of possibilities in the technology and in the environmental impact of fuels. The paper shows the state-of-the-art of the research and applications of bioprocesses to the petroleum field [it

The origin of the enhanced performance of nitrogen-doped MoS_2 in lithium ion batteries

International Nuclear Information System (INIS)

Liu, Qiuhong; Weijun, Xia; Wu, Zhenjun; Huo, Jia; Liu, Dongdong; Wang, Shuangyin; Wang, Qiang

2016-01-01

MoS_2 with a similar layered structure to graphene has been widely applied in various areas including lithium ion batteries. However, low conductivity, capacity fading and poor rate performance are still the main challenges for MoS_2 anode materials. In this work, for the first time, we prepared nitrogen-doped MoS_2 (N-MoS_2) nanosheets through a simple two-step method involving the preparation of MoS_2 with defects by the hydrothermal method, followed by sintering in a NH_3 atmosphere. Our electrochemical characterizations and density functional theory calculations demonstrated that nitrogen doping could enhance the electron conductivity and showed higher specific capacity than pristine MoS_2 as anode materials of lithium ion batteries, which can be attributed to the faster transportation of electrons and ions because of nitrogen doping. This work helps us understand the origin of the enhanced performance of N-doped MoS_2 in lithium ion batteries. (paper)

Assessment of the nutrient removal effectiveness of floating treatment wetlands applied to urban retention ponds.

Science.gov (United States)

Wang, Chih-Yu; Sample, David J

2014-05-01

The application of floating treatment wetlands (FTWs) in point and non-point source pollution control has received much attention recently. Although the potential of this emerging technology is supported by various studies, quantifying FTW performance in urban retention ponds remains elusive due to significant research gaps. Actual urban retention pond water was utilized in this mesocosm study to evaluate phosphorus and nitrogen removal efficiency of FTWs. Multiple treatments were used to investigate the contribution of each component in the FTW system with a seven-day retention time. The four treatments included a control, floating mat, pickerelweed (Pontederia cordata L.), and softstem bulrush (Schoenoplectus tabernaemontani). The water samples collected on Day 0 (initial) and 7 were analyzed for total phosphorus (TP), total particulate phosphorus, orthophosphate, total nitrogen (TN), organic nitrogen, ammonia nitrogen, nitrate-nitrite nitrogen, and chlorophyll-a. Statistical tests were used to evaluate the differences between the four treatments. The effects of temperature on TP and TN removal rates of the FTWs were described by the modified Arrhenius equation. Our results indicated that all three FTW designs, planted and unplanted floating mats, could significantly improve phosphorus and nitrogen removal efficiency (%, E-TP and E-TN) compared to the control treatment during the growing season, i.e., May through August. The E-TP and E-TN was enhanced by 8.2% and 18.2% in the FTW treatments planted with the pickerelweed and softstem bulrush, respectively. Organic matter decomposition was likely to be the primary contributor of nutrient removal by FTWs in urban retention ponds. Such a mechanism is fostered by microbes within the attached biofilms on the floating mats and plant root surfaces. Among the results of the four treatments, the FTWs planted with pickerelweed had the highest E-TP, and behaved similarly with the other two FTW treatments for nitrogen removal

Significantly improving trace thallium removal from surface waters during coagulation enhanced by nanosized manganese dioxide.

Science.gov (United States)

Huangfu, Xiaoliu; Ma, Chengxue; Ma, Jun; He, Qiang; Yang, Chun; Jiang, Jin; Wang, Yaan; Wu, Zhengsong

2017-02-01

Thallium (Tl) is an element of high toxicity and significant accumulation in human body. There is an urgent need for the development of appropriate strategies for trace Tl removal in drinking water treatment plants. In this study, the efficiency and mechanism of trace Tl (0.5 μg/L) removal by conventional coagulation enhanced by nanosized manganese dioxide (nMnO 2 ) were explored in simulated water and two representative surface waters (a river water and a reservoir water obtained from Northeast China). Experimental results showed that nMnO 2 significantly improve Tl(I) removal from selected waters. The removal efficiency was dramatically higher in the simulated water, demonstrating by less than 0.1 μg/L Tl residual. The enhancement of trace Tl removal in the surface waters decreased to a certain extent. Both adjusting water pH to alkaline condition and preoxidation of Tl(I) to Tl(III) benefit trace Tl removal from surface waters. Data also indicated that competitive cation of Ca 2+ decreased the efficiency of trace Tl removal, resulting from the reduction of Tl adsorption on nMnO 2 . Humic acid could largely low Tl removal efficiency during nMnO 2 enhanced coagulation processes. Trace elemental Tl firstly adsorbed on nMnO 2 and then removed accompanying with nMnO 2 settling. The information obtained in the present study may provide a potential strategy for drinking water treatment plants threatened by trace Tl. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced removal of radioactive particles by fluorocarbon surfactant solutions

International Nuclear Information System (INIS)

Kaiser, R.; Harling, O.K.

1993-08-01

The proposed research addressed the application of ESI's particle removal process to the non-destructive decontamination of nuclear equipment. The cleaning medium used in this process is a solution of a high molecular weight fluorocarbon surfactant in an inert perfluorinated liquid which results in enhanced particle removal. The perfluorinated liquids of interest, which are recycled in the process, are nontoxic, nonflammable, and environmentally compatible, and do not present a hazard to the ozone layer. The information obtained in the Phase 1 program indicated that the proposed ESI process is technically effective and economically attractive. The fluorocarbon surfactant solutions used as working media in the ESI process survived exposure of up to 10 Mrad doses of gamma rays, and are considered sufficiently radiation resistant for the proposed process. Ultrasonic cleaning in perfluorinated surfactant solutions was found to be an effective method of removing radioactive iron (Fe 59) oxide particles from contaminated test pieces. Radioactive particles suspended in the process liquids could be quantitatively removed by filtration through a 0.1 um membrane filter. Projected economics indicate a pre-tax pay back time of 1 month for a commercial scale system

Nitrogen-removal performance and community structure of nitrifying bacteria under different aeration modes in an oxidation ditch.

Science.gov (United States)

Guo, Chang-Zi; Fu, Wei; Chen, Xue-Mei; Peng, Dang-Cong; Jin, Peng-Kang

2013-07-01

Oxidation-ditch operation modes were simulated using sequencing batch reactors (SBRs) with alternate stirring and aerating. The nitrogen-removal efficiencies and nitrifying characteristics of two aeration modes, point aeration and step aeration, were investigated. Under the same air-supply capacity, oxygen dissolved more efficiently in the system with point aeration, forming a larger aerobic zone. The nitrifying effects were similar in point aeration and step aeration, where the average removal efficiencies of NH4(+) N were 98% and 96%, respectively. When the proportion of anoxic and oxic zones was 1, the average removal efficiencies of total nitrogen (TN) were 45% and 66% under point aeration and step aeration, respectively. Step aeration was more beneficial to both anoxic denitrification and simultaneous nitrification and denitrification (SND). The maximum specific ammonia-uptake rates (AUR) of point aeration and step aeration were 4.7 and 4.9 mg NH4(+)/(gMLVSS h), respectively, while the maximum specific nitrite-uptake rates (NUR) of the two systems were 7.4 and 5.3 mg NO2(-)-N/(gMLVSS h), respectively. The proportions of ammonia-oxidizing bacteria (AOB) to all bacteria were 5.1% under point aeration and 7.0% under step aeration, and the proportions of nitrite-oxidizing bacteria (NOB) reached 6.5% and 9.0% under point and step aeration, respectively. The dominant genera of AOB and NOB were Nitrosococcus and Nitrospira, which accounted for 90% and 91%, respectively, under point aeration, and the diversity of nitrifying bacteria was lower than under step aeration. Point aeration was selective of nitrifying bacteria. The abundance of NOB was greater than that of AOB in both of the operation modes, and complete transformation of NH4(+) N to NO3(-)-N was observed without NO2(-)-N accumulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Improved removal performance and mechanism investigation of papermaking wastewater treatment using manganese enhanced Fenton reaction.

Science.gov (United States)

Wang, Yingcai; Wang, Can; Shi, Shuai; Fang, Shuai

2018-06-01

The effects of Mn(II) on Fenton system to treat papermaking wastewater and the mechanism of Mn(II) enhanced Fenton reaction were investigated in this study. The chemical oxygen demand (COD) removal efficiency was enhanced in the presence of Mn(II), which increased by 19% compared with that of the Fenton system alone. The pseudo-first order reaction kinetic rate constant of Mn(II)/Fenton system was 2.11 times higher than that of Fenton system. 67%-81% COD were removed with the increasing Mn(II) concentration from 0 to 0.8 g/L. COD removal efficiency was also enhanced in a wider pH range (3-7), which indicated the operation parameters of Fenton technology could be broadened to a milder condition. The study of the mechanism showed that Mn(II) participated in the oxidation and coagulation stages in Fenton system. In the oxidation stage, Mn(II) promotes the production of HO 2 •/ O 2 • - , then HO 2 •/ O 2 • - reacts with Fe(III) to accelerate the formation of Fe(II), and finally accelerates the production of HO•. Meantime MnMnO 3 and Fe(OH) 3 forms in the coagulation stage, facilitating the removal of suspended substances and a large amount of COD, which enhances the overall COD removal of papermaking wastewater. This study provided a detailed mechanism to improve practical applications of Fenton technology.

Nitrogen removal and intentional nitrous oxide production from reject water in a coupled nitritation/nitrous denitritation system under real feed-stream conditions.

Science.gov (United States)

Weißbach, Max; Thiel, Paul; Drewes, Jörg E; Koch, Konrad

2018-05-01

A Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) was performed over five months to investigate the performance and dynamics of nitrogen elimination and nitrous oxide production from digester reject water under real feed-stream conditions. A 93% conversion of ammonium to nitrite could be maintained for adapted seed sludge in the first stage (nitritation). The second stage (nitrous denitritation), inoculated with conventional activated sludge, achieved a conversion of 70% of nitrite to nitrous oxide after only 12 cycles of operation. The development of an alternative feeding strategy and the addition of a coagulant (FeCl 3 ) facilitated stable operation and process intensification. Under steady-state conditions, nitrite was reliably eliminated and different nitrous oxide harvesting strategies were assessed. Applying continuous removal increased N 2 O yields by 16% compared to the application of a dedicated stripping phase. These results demonstrate the feasible application of the CANDO process for nitrogen removal and energy recovery from ammonia rich wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Improving the biological nitrogen removal process in pharmaceutical wastewater treatment plants: a case study.

Science.gov (United States)

Torrijos, M; Carrera, J; Lafuente, J

2004-04-01

The Biological Nitrogen Removal (BNR) process of some pharmaceutical wastewater treatment plants has important operational problems. This study shows that, in order to solve these problems, the design of industrial BNR processes should start by analysing three key parameters: the characteristics of the wastewater load, the determination of the maximum TKN removal rate and the detection of toxic or inhibitory compounds in the wastewater. A case study of this analysis in pharmaceutical wastewater is presented here. In this case, the conventional TKN analytical method does not make an accurate characterisation of the wastewater load because it measures a concentration of 100 mg TKN l(-1) whereas the real concentration, determined with a modified TKN analytical method, is 150-500 mg TKN l(-1). Also, the TKN removal of the treatment system is insufficient in some periods because it falls below legal requirements. This problem might be a consequence of the wrong characterisation of wastewater during the design process. The maximum TKN removal at 27 degrees C (24 mg N g VSS(-1) d(-1) or 197 mg N l(-1) d(-1)) was evaluated in a pilot-scale plant. This value is six times greater than the average NLR applied in the full-scale plant. Finally, some of the components of the wastewater, such as p-phenylenediamine, might have inhibitory or toxic effects on the biological process. P-phenylenediamine causes a large decrease in the nitrification rate. This effect was determined by respirometry. This methodology shows that the effect is mainly inhibitory with a contact time of 30 min and if the contact time is longer, 14 hours, a toxic effect is observed.

Active removal of ibuprofen by Money plant enhanced by ferrous ions.

Science.gov (United States)

Chehrenegar, Behdad; Hu, Jiangyong; Ong, Say Leong

2016-02-01

In this study, the removal of ibuprofen (IBP), a pharmaceutical compound, from aqueous media by Money plant (Epipremnum aureum) was investigated. The effect of ferrous iron (Fe(2+)) on enhancing the IBP removal rate was also analyzed. The first-order removal rate constants showed higher values for lower IBP initial concentrations in the range of 0.20-0.28 d(-1) for an initial concentration of 125 μg L(-1) to 0.03-0.13 d(-1) for an initial concentration of 1000 μg L(-1). Introducing ferrous iron to the aqueous media enhanced the first-order removal rate constant up to 6.5 times in a 3 d time period. Along with the removal of IBP from the media, the endogenous concentration of H2O2 also decreased presumably by the production of hydroxyl radical (·OH). Reduction in the endogenous H2O2 concentration was recorded to be 38% and 98% in the absence and presence of Fe(2+) respectively in the first day and the H2O2 level remained considerably low until day 7 which then gradually increased slightly. Simultaneous reduction of IBP and endogenous H2O2 concentration could be due to the reaction of IBP with ·OH and presumably ·OH production itself accelerated via Fenton reaction. In addition, presence of sodium bicarbonate (NaHCO3) as ·OH scavenger in the system showed reduction of first-order removal rate constant from 1.30 d(-1) to 0.07 d(-1) which could be a possible evidence of biological advanced oxidation process which is believed to play an important role in phytoremediation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Microbial nitrate removal in biologically enhanced treated coal gasification wastewater of low COD to nitrate ratio by coupling biological denitrification with iron and carbon micro-electrolysis.

Science.gov (United States)

Zhang, Zhengwen; Han, Yuxing; Xu, Chunyan; Ma, Wencheng; Han, Hongjun; Zheng, Mengqi; Zhu, Hao; Ma, Weiwei

2018-04-21

Mixotrophic denitrification coupled biological denitrification with iron and carbon micro-electrolysis (IC-ME) is a promising emerging bioprocess for nitrate removal of biologically enhanced treated coal gasification wastewater (BECGW) with low COD to nitrate ratio. TN removal efficiency in R1 with IC-ME assisted was 16.64% higher than R2 with scrap zero valent iron addition, 23.05% higher than R3 with active carbon assisted, 30.51% higher than R4 with only active sludge addition, 80.85% higher than R5 utilizing single IC-ME as control. Fe 2+ generated from IC-ME decreased the production of N 2 O and enriched more Nitrate-reducing Fe(Ⅱ) oxidation bacteria (NRFOB) Acidovorax and Thiobacillus, which could convert nitrate to nitrogen gas. And the presence of Fe 3+ , as the Fe 2+ oxidation product, could stimulate the growth of Fe(III)-reducing strain (FRB) that indicated by redundancy analysis. Microbial network analysis demonstrated FRB Geothrix had a co-occurrence relationship with other bacteria, revealing its dominant involvement in nitrate removal of BECGW. Copyright © 2018 Elsevier Ltd. All rights reserved.

Achieve efficient nitrogen removal from real sewage in a plug-flow integrated fixed-film activated sludge (IFAS) reactor via partial nitritation/anammox pathway.

Science.gov (United States)

Yang, Yandong; Zhang, Liang; Cheng, Jun; Zhang, Shujun; Li, Baikun; Peng, Yongzhen

2017-09-01

This study tested the feasibility of plug-flow integrated fixed-film activated sludge (IFAS) reactor in applying sewage partial nitritation/anammox (PN/A) process. The IFAS reactor was fed with real pre-treated sewage (C/N ratio=1.3) and operated for 200days. High nitrogen removal efficiency of 82% was achieved with nitrogen removal rates of 0.097±0.019kgN/(m 3 ·d). Therefore, plug-flow IFAS reactor could be an alternative to applying sewage PN/A process. Besides, it was found that the stability of sewage PN/A process was significantly affected by residual ammonium. Nitrate accumulated in effluent and PN/A performance deteriorated when residual ammonium was below 1mg/L. On the contrary, long-term stable PN/A operation was achieved when residual ammonium was over 3mg/L. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of nitrogen compounds from gasification gas by selective catalytic or non-catalytic oxidation; Typpiyhdisteiden poisto kaasutuskaasusta selektiivisellae katalyyttisellae ja ei-katalyyttisellae hapetuksella

Energy Technology Data Exchange (ETDEWEB)

Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

1996-12-01

In gasification reactive nitrogenous compounds are formed from fuel nitrogen, which may form nitrogen oxides in gas combustion. In fluidized bed gasification the most important nitrogenous compound is ammonia (NH{sub 3}). If ammonia could be decomposed to N{sub 2} already before combustion, the emissions if nitrogen oxides could be reduced significantly. One way of increasing the decomposition rate of NH{sub 3} could be the addition of suitable reactants to the gas, which would react with NH{sub 3} and produce N{sub 2}. The aim of this research is to create basic information, which can be used to develop a new method for removal of nitrogen compounds from gasification gas. The reactions of nitrogen compounds and added reactants are studied in reductive atmosphere in order to find conditions, in which nitrogen compounds can be oxidized selectively to N{sub 2}. The project consists of following subtasks: (1) Selective non-catalytic oxidation (SNCO): Reactions of nitrogen compounds and oxidizers in the gas phase, (2) Selective catalytic oxidation (SCO): Reactions of nitrogen compounds and oxidizers on catalytically active surfaces, (3) Kinetic modelling of experimental results in co-operation with the Combustion Chemistry Research Group of Aabo Akademi University. The most important finding has been that NH{sub 3} can be made to react selectively with the oxidizers even in the presence of large amounts of CO and H{sub 2}. Aluminium oxides were found to be the most effective materials promoting selectivity. (author)

Nitrogen and phosphorus removal coupled with carbohydrate production by five microalgae cultures cultivated in biogas slurry.

Science.gov (United States)

Tan, Fen; Wang, Zhi; Zhouyang, Siyu; Li, Heng; Xie, Youping; Wang, Yuanpeng; Zheng, Yanmei; Li, Qingbiao

2016-12-01

In this study, five microalgae strains were cultured for their ability to survive in biogas slurry, remove nitrogen resources and accumulate carbohydrates. It was proved that five microalgae strains adapted in biogas slurry well without ammonia inhibition. Among them, Chlorella vulgaris ESP-6 showed the best performance on carbohydrate accumulation, giving the highest carbohydrate content of 61.5% in biogas slurry and the highest ammonia removal efficiency and rate of 96.3% and 91.7mg/L/d respectively in biogas slurry with phosphorus and magnesium added. Additionally, the absence of phosphorus and magnesium that can be adverse for biomass accumulation resulted in earlier timing of carbohydrate accumulation and magnesium was firstly recognized and proved as the influence factor for carbohydrate accumulation. Microalgae that cultured in biogas slurry accumulated more carbohydrate in cell, making biogas slurry more suitable medium for the improvement of carbohydrate content, thus can be regarded as a new strategy to accumulate carbohydrate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Non-tumor enhancement at the surgical margin on CT after the removal of brain tumors

International Nuclear Information System (INIS)

Adachi, Michito; Hosoya, Takaaki; Yamaguchi, Kohichi; Yamada, Kiyotada

1992-01-01

Marginal enhancement is occasionally seen at the surgical margin on CT after the total removal of brain tumors. This enhancement disappears in due time, and therefore we call it non-tumor enhancement. It is often difficult, however, to differentiate non-tumor enhancement from tumor recurrence. In this study, we attempted to determine the characteristics of non-tumor enhancement. The subjects of the study consisted of 15 patients with astrocytoma and one with metastatic tumor in whom sequential CT scans had been performed after total removal of the tumor. Based on the observation of these sequential CT scans, the characteristics of non-tumor enhancement were presumed to be as follows: (1) In four cases, enhancement at the surgical margin persisted more than four months after surgery and then disappeared. Therefore, these cases were considered non-tumor enhancement. Prolonged duration of enhancement such as that in these cases is not necessarily due to recurrence. Marginal enhancement within 3 mm in thickness and with a well-demarcated border like that of a flax is likely to be non-tumor enhancement. (author)

Short communication Biological removal of nitrogen species from ...

African Journals Online (AJOL)

The gravel-packed column reactor was found to be unsuitable for the removal of nitrate in the configuration used (maximum 15% removal efficiency). The critical parameters for denitrification are nitrate concentration, temperature, influent flow rate and mean cell retention time. Nitrate removal did not meet the expectations ...

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra

Directory of Open Access Journals (Sweden)

Oriol Gonzalez

2016-10-01

Full Text Available We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal, results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

Enhanced detection of nitrogen dioxide via combined heating and pulsed UV operation of indium oxide nano-octahedra.

Science.gov (United States)

Gonzalez, Oriol; Roso, Sergio; Vilanova, Xavier; Llobet, Eduard

2016-01-01

We report on the use of combined heating and pulsed UV light activation of indium oxide gas sensors for enhancing their performance in the detection of nitrogen dioxide in air. Indium oxide nano-octahedra were synthesized at high temperature (900 °C) via vapour-phase transport and screen-printed onto alumina transducers that comprised interdigitated electrodes and a heating resistor. Compared to the standard, constant temperature operation of the sensor, mild heating (e.g., 100 °C) together with pulsed UV light irradiation employing a commercially available, 325 nm UV diode (square, 1 min period, 15 mA drive current signal), results in an up to 80-fold enhancement in sensitivity to nitrogen dioxide. Furthermore, this combined operation method allows for making savings in power consumption that range from 35% to over 80%. These results are achieved by exploiting the dynamics of sensor response under pulsed UV light, which convey important information for the quantitative analysis of nitrogen dioxide.

Temporal dependence of the enhancement of material removal in femtosecond-nanosecond dual-pulse laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Scaffidi, Jon; Pearman, William; Carter, J. Chance; Colston, Bill W. Jr.; Angel, S. Michael

2004-01-01

Despite the large neutral atomic and ionic emission enhancements that have been noted in collinear and orthogonal dual-pulse laser-induced breakdown spectroscopy, the source or sources of these significant signal and signal-to-noise ratio improvements have yet to be explained. In the research reported herein, the combination of a femtosecond preablative air spark and a nanosecond ablative pulse yields eightfold and tenfold material removal improvement for brass and aluminum, respectively, but neutral atomic emission is enhanced by only a factor of 3-4. Additionally, temporal correlation between enhancement of material removal and of atomic emission is quite poor, suggesting that the atomic-emission enhancements noted in the femtosecond-nanosecond pulse configuration result in large part from some source other than simple improvement in material removal

Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

Energy Technology Data Exchange (ETDEWEB)

Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Cheng, Q.J. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Chen, X. [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Ostrikov, K., E-mail: kostya.ostrikov@csiro.au [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia)

2011-09-22

Highlights: > A new and custom-designed bias-enhanced hot-filament chemical vapor deposition system is developed to synthesize vertically aligned carbon nanotubes. > The carbon nanotubes are later treated with nitrogen plasmas. > The electron field emission characteristics of the carbon nanotubes are significantly improved after the nitrogen plasma treatment. > A new physical mechanism is proposed to interpret the improvement of the field emission characteristics. - Abstract: The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 {mu}A/cm{sup 2}) achieved at a low applied field (3.50 V/{mu}m) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.

Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

International Nuclear Information System (INIS)

Wang, B.B.; Cheng, Q.J.; Chen, X.; Ostrikov, K.

2011-01-01

Highlights: → A new and custom-designed bias-enhanced hot-filament chemical vapor deposition system is developed to synthesize vertically aligned carbon nanotubes. → The carbon nanotubes are later treated with nitrogen plasmas. → The electron field emission characteristics of the carbon nanotubes are significantly improved after the nitrogen plasma treatment. → A new physical mechanism is proposed to interpret the improvement of the field emission characteristics. - Abstract: The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 μA/cm 2 ) achieved at a low applied field (3.50 V/μm) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.

Nitrogen Transformation and Microbial Spatial Distribution in Drinking Water Biofilter

Science.gov (United States)

Qian, Yongxing; Zhang, Huining; Jin, Huizheng; Wu, Chengxia

2018-02-01

Well understanding the rule of nitrogen mutual transformation in biofilters is important for controlling the DBPs formation in the subsequent disinfection process. Ammonia nitrogen removal effect and nitrogen transformation approach in biofilter of drinking water was researched in the study. The biofilter removed ammonia of 48.5% and total phosphorus of 72.3%. And the removal rate of TN, NO3 --N, DON were 37.1%, 33.1%, 46.9%, respectively. Biomass and bioactivity of different depth of the biofilter were determined, too. The overall distribution of biomass showed a decreasing trend from top to bottom. The bioactivity in lower layer gradually increased. Especially the bioactivity of heterotrophic microorganisms showed a gradual increase trend. The amount of the nitrogen loss was 3.06mg/L. Non-nitrification pathway of “nitrogen loss” phenomenon in biofilter might exist assimilation, nitrification and denitrification in autotrophic.

Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes

Science.gov (United States)

Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C.; Shimoni, Olga; Aharonovich, Igor

2015-03-01

Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07510b

NOx removal enhancement by a Jerks - and - Jumps type electrode in a dielectric barrier discharge

International Nuclear Information System (INIS)

Mercado-Cabrera, A; Villar, E L del; Valencia-Alvarado, R; Lopez-Callejas, R; Barocio, S R; Pena-Eguiluz, R; Munozoz-Castro, A; Jaramillo-Sierra, B; Piedad-Beneitez, A de la

2008-01-01

In this study, the electrode surface of a NOx removal treatment reactor has been modified in order to reduce its electric potential level and, at the same time, to increase its removal capacity by generating a cold plasma using a non-homogenous electric field on the electrode surface. This electric field has been achieved by means of a jerks and jumps-like electrode profile. The other electrode conserves the original flat form. Then, experiments on the removal of NOx were carried out in this 22.4 cm 3 reactor. Concentrations of 30-80 μmol/mol of NOx in nitrogen were used with 1 SLPM flows. The exhaust gases were analysed as well as characterised by gas chromatography and mass spectrometry. Additional experiments were also carried out in a second reactor of the same reaction volume but where two conventional flat and parallel electrodes were used, in order to compare the results. The NO removal efficiency in the two flat electrode case approached 87% while ∼98% in the jerks and jumps reactor

Relative importance of plant uptake and plant associated denitrification for removal of nitrogen from mine drainage in sub-arctic wetlands.

Science.gov (United States)

Hallin, Sara; Hellman, Maria; Choudhury, Maidul I; Ecke, Frauke

2015-11-15

Reactive nitrogen (N) species released from undetonated ammonium-nitrate based explosives used in mining or other blasting operations are an emerging environmental problem. Wetlands are frequently used to treat N-contaminated water in temperate climate, but knowledge on plant-microbial interactions and treatment potential in sub-arctic wetlands is limited. Here, we compare the relative importance of plant uptake and denitrification among five plant species commonly occurring in sub-arctic wetlands for removal of N in nitrate-rich mine drainage in northern Sweden. Nitrogen uptake and plant associated potential denitrification activity and genetic potential for denitrification based on quantitative PCR of the denitrification genes nirS, nirK, nosZI and nosZII were determined in plants growing both in situ and cultivated in a growth chamber. The growth chamber and in situ studies generated similar results, suggesting high relevance and applicability of results from growth chamber experiments. We identified denitrification as the dominating pathway for N-removal and abundances of denitrification genes were strong indicators of plant associated denitrification activity. The magnitude and direction of the effect differed among the plant species, with the aquatic moss Drepanocladus fluitans showing exceptionally high ratios between denitrification and uptake rates, compared to the other species. However, to acquire realistic estimates of N-removal potential of specific wetlands and their associated plant species, the total plant biomass needs to be considered. The species-specific plant N-uptake and abundance of denitrification genes on the root or plant surfaces were affected by the presence of other plant species, which show that both multi- and inter-trophic interactions are occurring. Future studies on N-removal potential of wetland plant species should consider how to best exploit these interactions in sub-arctic wetlands. Copyright © 2015 Elsevier Ltd. All rights

Enhancing Nitrogen Availability, Ammonium Adsorption-Desorption, and Soil pH Buffering Capacity using Composted Paddy Husk

Science.gov (United States)

Latifah, O.; Ahmed, O. H.; Abdul Majid, N. M.

2017-12-01

Form of nitrogen present in soils is one of the factors that affect nitrogen loss. Nitrate is mobile in soils because it does not absorb on soil colloids, thus, causing it to be leached by rainfall to deeper soil layers or into the ground water. On the other hand, temporary retention and timely release of ammonium in soils regulate nitrogen availability for crops. In this study, composted paddy husk was used in studies of soil leaching, buffering capacity, and ammonium adsorption and desorption to determine the: (i) availability of exchangeable ammonium, available nitrate, and total nitrogen in an acid soil after leaching the soil for 30 days, (ii) soil buffering capacity, and (iii) ability of the composted paddy husk to adsorb and desorb ammonium from urea. Leaching of ammonium and nitrate were lower in all treatments with urea and composted paddy husk compared with urea alone. Higher retention of soil exchangeable ammonium, available nitrate, and total nitrogen of the soils with composted paddy husk were due to the high buffering capacity and cation exchange capacity of the amendment to adsorb ammonium thus, improving nitrogen availability through temporary retention on the exchange sites of the humic acids of the composted paddy husk. Nitrogen availability can be enhanced if urea is amended with composted paddy husk.

Facile fabrication of palladium-ionic liquids-nitrogen-doped graphene nanocomposites as enhanced electro-catalyst for ethanol oxidation

Science.gov (United States)

Li, Shuwen; Yang, Honglei; Ren, Ren; Ma, Jianxin; Jin, Jun; Ma, Jiantai

2015-10-01

The palladium-ionic liquids-nitrogen-doped graphene nanocomposites are facile fabricated as enhanced electro-catalyst for ethanol oxidation. First, the ionic liquids functionalized nitrogen-doping graphene nanosheets (PDIL-NGS) with few layers is synthesized through a facile and effective one-pot hydrothermal method with graphene oxide as raw material, urea as reducing-doping agents and ionic liquids (ILs) derived from 3,4,9,10-perylene tetracarboxylic acid as functional molecules. The results of systematic characterization reveal that the PDIL molecules not only can functionalize NGS by π-π stacking with no affecting the nitrogen doping but also prevent the agglomeration of NGS. More importantly, the processing performance and the property of electron transfer are remarkably enhanced duo to introducing a large number of ILs groups. Then, the enhanced electrocatalytic Pd nanoparticles are successfully anchored on PDIL-NGS by a facile and surfactant-free synthetic technique. As an anode catalyst, the novel catalyst exhibits better kinetics, more superior electrocatalytic performance, higher tolerance and electrochemical stability than the other catalysts toward ethanol electrooxidation, owing to the role of PDIL molecules. Therefore, the new catalyst is believed to have the potential use for direct alcohol fuel cells in the future and the functionalized NGS is promising useful materials applied in other fields.

Nitrogen Removal in a Horizontal Subsurface Flow Constructed Wetland Estimated Using the First-Order Kinetic Model

Directory of Open Access Journals (Sweden)

Lijuan Cui

2016-11-01

Full Text Available We monitored the water quality and hydrological conditions of a horizontal subsurface constructed wetland (HSSF-CW in Beijing, China, for two years. We simulated the area-based constant and the temperature coefficient with the first-order kinetic model. We examined the relationships between the nitrogen (N removal rate, N load, seasonal variations in the N removal rate, and environmental factors—such as the area-based constant, temperature, and dissolved oxygen (DO. The effluent ammonia (NH4+-N and nitrate (NO3−-N concentrations were significantly lower than the influent concentrations (p < 0.01, n = 38. The NO3−-N load was significantly correlated with the removal rate (R2 = 0.96, p < 0.01, but the NH4+-N load was not correlated with the removal rate (R2 = 0.02, p > 0.01. The area-based constants of NO3−-N and NH4+-N at 20 °C were 27 ± 26 (mean ± SD and 14 ± 10 m∙year−1, respectively. The temperature coefficients for NO3−-N and NH4+-N were estimated at 1.004 and 0.960, respectively. The area-based constants for NO3−-N and NH4+-N were not correlated with temperature (p > 0.01. The NO3−-N area-based constant was correlated with the corresponding load (R2 = 0.96, p < 0.01. The NH4+-N area rate was correlated with DO (R2 = 0.69, p < 0.01, suggesting that the factors that influenced the N removal rate in this wetland met Liebig’s law of the minimum.

Simulation of Nitrogen and Phosphorus Removal in Ecological Ditch Based on EFDC Model

Science.gov (United States)

Li, S. M.; Wang, X. L.; Zhou, Q. Y.; Han, N. N.

2018-03-01

Agricultural non-point source pollution threatens water quality and ecological system recently. To control it, the first and most important task is to control the migration and transformation of nitrogen and phosphorus in the agricultural ditches. An ecological ditch was designed, and according to the design a pilot device was built, the mechanism of N and P removal in ditches under the collaboration of aquatic organisms-hydraulic power was studied through the dynamic and static experiments, in order to find out the specific influences of different environmental factors such as influent concentration, influent flow and water level. The transport and diffusion of N and P in the ditch was simulated by a three dimensional water quality model EFDC, the simulation results and the experimental data were compared. The average relative errors of EFDC model simulated results were all less than 15%, which verified the reliability of the model.

Citric-acid preacidification enhanced electrokinetic remediation for removal of chromium from chromium-residue-contaminated soil.

Science.gov (United States)

Meng, Fansheng; Xue, Hao; Wang, Yeyao; Zheng, Binghui; Wang, Juling

2018-02-01

Electrokinetic experiments were conducted on chromium-residue-contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. The results showed that electrokinetic remediation removal efficiency of chromium from chromium-contaminated soil was significantly enhanced with acidizing pretreatment. The total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] removal rate of the group acidized by citric acid (0.9 mol/L) for 5 days was increased from 6.23% and 19.01% in the acid-free experiments to 26.97% and 77.66% in the acidification-treated experiments, respectively. In addition, part of chromium with the state of carbonate-combined will be converted into water-soluble state through acidification to improve the removal efficiency. Within the appropriate concentration range, the higher concentration of acid was, the more chromium was released. So the removal efficiency of chromium depended on the acid concentration. The citric acid is also a kind of complexing agent, which produced complexation with Cr that was released by the electrokinetic treatment and then enhanced the removal efficiency. The major speciation of chromium that was removed from soils by acidification-electrokinetics remediation was acid-soluble speciation, revivification speciation and oxidation speciation, which reduced biological availability of chromium.

Enhanced photosynthetic capacity increases nitrogen metabolism through the coordinated regulation of carbon and nitrogen assimilation in Arabidopsis thaliana.

Science.gov (United States)

Otori, Kumi; Tanabe, Noriaki; Maruyama, Toshiki; Sato, Shigeru; Yanagisawa, Shuichi; Tamoi, Masahiro; Shigeoka, Shigeru

2017-09-01

Plant growth and productivity depend on interactions between the metabolism of carbon and nitrogen. The sensing ability of internal carbon and nitrogen metabolites (the C/N balance) enables plants to regulate metabolism and development. In order to investigate the effects of an enhanced photosynthetic capacity on the metabolism of carbon and nitrogen in photosynthetically active tissus (source leaves), we herein generated transgenic Arabidopsis thaliana plants (ApFS) that expressed cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphosphatase in their chloroplasts. The phenotype of ApFS plants was indistinguishable from that of wild-type plants at the immature stage. However, as plants matured, the growth of ApFS plants was superior to that of wild-type plants. Starch levels were higher in ApFS plants than in wild-type plants at 2 and 5 weeks. Sucrose levels were also higher in ApFS plants than in wild-type plants, but only at 5 weeks. On the other hand, the contents of various free amino acids were lower in ApFS plants than in wild-type plants at 2 weeks, but were similar at 5 weeks. The total C/N ratio was the same in ApFS plants and wild-type plants, whereas nitrite levels increased in parallel with elevations in nitrate reductase activity at 5 weeks in ApFS plants. These results suggest that increases in the contents of photosynthetic intermediates at the early growth stage caused a temporary imbalance in the free-C/free-N ratio and, thus, the feedback inhibition of the expression of genes involved in the Calvin cycle and induction of the expression of those involved in nitrogen metabolism due to supply deficient free amino acids for maintenance of the C/N balance in source leaves of ApFS plants.

On the `hysteresis` effect in the biological nitrogen removal :theory and full scale experimental evaluation; Sul fenomeno di `isteresi` nella rimozione biologica dell`azoto: concettualizzazione teorica e valutazione sperimentale a scala reale degli effetti

Energy Technology Data Exchange (ETDEWEB)

Tatano, F. [Politecnico di Milano, Milan (Italy). Dip. di Ingegneria Idraulica, Ambientale e del Rilevamento

1996-07-01

The wastewater treatments plants localized in the Ruhr River (Germany), generally present a typical wastewater temperature variation curve during the winter period. These temperature changes produce specific effects on the nitrogen removal efficiencies in the activated sludge systems. The so called `hysteresis` phenomenon is responsible for these effects. The paper deals with some simplified theoretical considerations and with a full scale experimental evaluations of the effects caused by the hysteresis phenomenon in the biological nitrogen removal.

Ammonium removal using algae-bacteria consortia: the effect of ammonium concentration, algae biomass, and light.

Science.gov (United States)

Jia, Huijun; Yuan, Qiuyan

2018-04-01

In this study, the effects of ammonium nitrogen concentration, algae biomass concentration, and light conditions (wavelength and intensity) on the ammonium removal efficiency of algae-bacteria consortia from wastewater were investigated. The results indicated that ammonium concentration and light intensity had a significant impact on nitrification. It was found that the highest ammonia concentration (430 mg N/L) in the influent resulted in the highest ammonia removal rate of 108 ± 3.6 mg N/L/days, which was two times higher than the influent with low ammonia concentration (40 mg N/L). At the lowest light intensity of 1000 Lux, algae biomass concentration, light wavelength, and light cycle did not show a significant effect on the performance of algal-bacterial consortium. Furthermore, the ammonia removal rate was approximately 83 ± 1.0 mg N/L/days, which was up to 40% faster than at the light intensity of 2500 Lux. It was concluded that the algae-bacteria consortia can effectively remove nitrogen from wastewater and the removal performance can be stabilized and enhanced using the low light intensity of 1000 Lux that is also a cost-effective strategy.

Restoration and Purification of Dissolved Organic Nitrogen by Bacteria and Phytoremediation in Shallow Eutrophic Lakes Sediments

Science.gov (United States)

Li, Xin; Yue, Yi

2018-06-01

Endogenous organic nitrogen loadings in lake sediments have increased with human activity in recent decades. A 6-month field study from two disparate shallow eutrophic lakes could partly reveal these issues by analysing seasonal variations of biodegradation and phytoremediation in the sediment. This paper describes the relationship between oxidation reduction potential, temperature, microbial activity and phytoremediation in nitrogen cycling by calculation degradative index of dissolved organic nitrogen and amino acid decomposition. The index was being positive in winter and negative in summer while closely positive correlated with biodegradation. Our analysis revealed that rather than anoxic condition, biomass is the primary factor to dissolved organic nitrogen distribution and decomposition. Some major amino acids statistics also confirm the above view. The comparisons of organic nitrogen and amino acid in abundance and seasons in situ provides that demonstrated plants cue important for nitrogen removal by their roots adsorption and immobilization. In conclusion, enhanced microbial activity and phytoremediation with the seasons will reduce the endogenous nitrogen loadings by the coupled mineralization and diagenetic process.

Modeling Nitrous Oxide Production during Biological Nitrogen Removal via Nitrification and Denitrification: Extensions to the General ASM Models

DEFF Research Database (Denmark)

Ni, Bing-Jie; Ruscalleda, Maël; Pellicer i Nàcher, Carles

2011-01-01

on N2O production from four different mixed culture nitrification and denitrification reactor study reports. Modeling results confirm that hydroxylamine oxidation by ammonium oxidizers (AOB) occurs 10 times slower when NO2– participates as final electron acceptor compared to the oxic pathway. Among......Nitrous oxide (N2O) can be formed during biological nitrogen (N) removal processes. In this work, a mathematical model is developed that describes N2O production and consumption during activated sludge nitrification and denitrification. The well-known ASM process models are extended to capture N2O...

A comparative investigation on the effects of nitrogen-doping into graphene on enhancing the electrochemical performance of SnO2/graphene for sodium-ion batteries.

Science.gov (United States)

Xie, Xiuqiang; Su, Dawei; Zhang, Jinqiang; Chen, Shuangqiang; Mondal, Anjon Kumar; Wang, Guoxiu

2015-02-21

SnO2/nitrogen-doped graphene nanohybrids have been synthesized by an in situ hydrothermal method, during which the formation of SnO2 nanocrystals and nitrogen doping of graphene occur simultaneously. The as-prepared SnO2/nitrogen-doped graphene nanohybrids exhibit enhanced electrochemical performance for sodium-ion batteries compared to SnO2/graphene nanocomposites. A systematic comparison between SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart as anode materials for sodium-ion batteries has been conducted. The comparison is in a reasonable framework, where SnO2/nitrogen-doped graphene nanohybrids and the SnO2/graphene counterpart have the same SnO2 ratio, similar SnO2 crystallinity and particle size, close surface area and pore size. The results clearly manifest that the improved electron transfer efficiency of SnO2/nitrogen-doped graphene due to nitrogen-doping plays a more important role than the increased electro-active sites within graphene network in enhancing the electro-activity of SnO2/nitrogen-doped graphene nanohybrids compared to the SnO2/graphene counterpart. In contrast to the previous reports which often ascribe the enhanced electro-activity of nitrogen-doped graphene based composites to two nitrogen-doping effects (improving the electron transfer efficiency and increasing electro-active sites within graphene networks) in one single declaration, this work is expected to provide more specific information for understanding the effects of nitrogen-doping into graphene on improving the electrochemical performance of graphene based composites.

Full scale experimental assessment of reliability of steady state design criteria of activated sludge process with biological nitrogen removal and chemical phosphorus removal; Verifica sperimentale a scala reale di criteri di dimensionamento dei sistemi a fanghi attivi per la rimozione dei nutrienti

Energy Technology Data Exchange (ETDEWEB)

Tatano, F. [Politecnico di Milano, Milan (Italy). Dip. di Ingegneria Idraulica, Ambientale e del Rilevamento, Sez. Ambientale

1996-06-01

The biological phase of a wastewater treatment plant situated in the Ruhr River Region (Germany), has been monitored for about one year. The collected experimental data have been elaborated in this paper with the objective of an assessment of the reliability of some recent steady-state design criteria of the activated sludge process with biological nitrogen removal and chemical phosphorus removal.

A wooded riparian strip set up for nitrogen removal can affect the water flux microbial composition

Directory of Open Access Journals (Sweden)

Mizanur Md. Rahman

2014-02-01

Full Text Available This research is part of a project aimed at verifying the potential of a specifically assessed wooded riparian zone in removing excess of combined nitrogen from the Zero river flow for the reduction of nutrient input into Venice Lagoon. Specific objectives were pursued to determine seasonal fluctuations of the microbial populations from the input water to a drainage ditch, conveying back the flux into the river after passing through the soil of the wooded riparian strip. The bacterial communities were determined by combined approaches involving cultivation, microscopic methods and DNA based techniques to determine both culturable and total microbial community in water. The results indicate that the size of the bacterial population, including the culturable fraction, increases from the river to the drainage ditch especially on the warm season. The multiple approach here adopted enabled also to demonstrate that the special condition created in the buffer strip supports the development and the metabolism of the microbial community. The nature of the bacterial population, in terms of phylotypes distribution, was investigated by 16S rDNA analysis indicating that the most represented genera belong to Gamma-proteobacteria, which is known to include an exceeding number of important pathogens. In spring, the effect of the buffer strip seems to significantly reduce such a sub-population. The changes observed for the total bacterial community composition become much evident in summer, as revealed by both denaturing gradient gel electrophoresis cluster analysis and by the diversity index calculation. The hydraulic management coupled to the suspension of farming practices and the development of the woody and herbaceous vegetation resulted in a condition suitable for the containment of undesired microbiota (mainly during the spring season while continuing to support denitrification activity (especially throughout the summer as verified by the total nitrogen

Cost-effectiveness of nitrogen mitigation by alternative household wastewater management technologies.

Science.gov (United States)

Wood, Alison; Blackhurst, Michael; Hawkins, Troy; Xue, Xiaobo; Ashbolt, Nicholas; Garland, Jay

2015-03-01

Household wastewater, especially from conventional septic systems, is a major contributor to nitrogen pollution. Alternative household wastewater management technologies provide similar sewerage management services but their life cycle costs and nitrogen flow implications remain uncertain. This paper addresses two key questions: (1) what are the total costs, nitrogen mitigation potential, and cost-effectiveness of a range of conventional and alternative municipal wastewater treatment technologies, and (2) what uncertainties influence these outcomes and how can we improve our understanding of these technologies? We estimate a household nitrogen mass balance for various household wastewater treatment systems and combine this mass balance with life cycle cost assessment to calculate the cost-effectiveness of nitrogen mitigation, which we define as nitrogen removed from the local watershed. We apply our methods to Falmouth, MA, where failing septic systems have caused heightened eutrophication in local receiving water bodies. We find that flushing and dry (composting) urine-diversion toilets paired with conventional septic systems for greywater management demonstrate the lowest life cycle cost and highest cost-effectiveness (dollars per kilogram of nitrogen removed from the watershed). Composting toilets are also attractive options in some cases, particularly best-case nitrogen mitigation. Innovative/advanced septic systems designed for high-level nitrogen removal are cost-competitive options for newly constructed homes, except at their most expensive. A centralized wastewater treatment plant is the most expensive and least cost-effective option in all cases. Using a greywater recycling system with any treatment technology increases the cost without adding any nitrogen removal benefits. Sensitivity analysis shows that these results are robust considering a range of cases and uncertainties. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Novel chitosan/PVA/zerovalent iron biopolymeric nanofibers with enhanced arsenic removal applications.

Science.gov (United States)

Chauhan, Divya; Dwivedi, Jaya; Sankararamakrishnan, Nalini

2014-01-01

Enhanced removal application of both forms of inorganic arsenic from arsenic-contaminated aquifers at near-neutral pH was studied using a novel electrospun chitosan/PVA/zerovalent iron (CPZ) nanofibrous mat. CPZ was carefully examined using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), atomic fluorescence spectroscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). Application of the adsorbent towards the removal of total inorganic arsenic in batch mode has also been studied. A suitable mechanism for the adsorption has also been discussed. CPZ nanofibers mat was found capable to remove 200.0±10.0 mg g(-1) of As(V) and 142.9±7.2 mg g(-1) of As(III) from aqueous solution of pH 7.0 at ambient condition. Addition of ethylenediaminetetraacetic acid (EDTA) enabled the stability of iron in zerovalent state (ZVI). Enhanced capacity of the fibrous mat could be attributed to the high surface area of the fibers, presence of ZVI, and presence of functional groups such as amino, carboxyl, and hydroxyl groups of the chitosan and EDTA. Both Langmuir and Freundlich adsorption isotherms were applicable to describe the removal process. The possible mechanism of adsorption has been explained in terms of electrostatic attraction between the protonated amino groups of chitosan/arsenate ions and oxidation of arsenite to arsenate by Fentons generated from ZVI and subsequent complexation of the arsenate with the oxidized iron. These CPZ nanofibrous mats has been prepared with environmentally benign naturally occurring biodegradable biopolymer chitosan, which offers unique advantage in the removal of arsenic from contaminated groundwater.

An efficient strategy for enhancing traffic capacity by removing links in scale-free networks

International Nuclear Information System (INIS)

Huang, Wei; Chow, Tommy W S

2010-01-01

An efficient link-removal strategy, called the variance-of-neighbor-degree-reduction (VNDR) strategy, for enhancing the traffic capacity of scale-free networks is proposed in this paper. The VNDR strategy, which considers the important role of hub nodes, balances the amounts of packets routed from each node to the node's neighbors. Compared against the outcomes of strategies that remove links among hub nodes, our results show that the traffic capacity can be greatly enhanced, especially under the shortest path routing strategy. It is also found that the average transport time is effectively reduced by using the VNDR strategy only under the shortest path routing strategy

Benchmarking biological nutrient removal in wastewater treatment plants: influence of mathematical model assumptions

DEFF Research Database (Denmark)

Flores-Alsina, Xavier; Gernaey, Krist V.; Jeppsson, Ulf

2012-01-01

This paper examines the effect of different model assumptions when describing biological nutrient removal (BNR) by the activated sludge models (ASM) 1, 2d & 3. The performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) benchmark wastewater treatment plant...

Combined organic matter and nitrogen removal from a chemical industry wastewater in a two-stage MBBR system.

Science.gov (United States)

Cao, S M S; Fontoura, G A T; Dezotti, M; Bassin, J P

2016-01-01

Pesticide-producing factories generate highly polluting wastewaters containing toxic and hazardous compounds which should be reduced to acceptable levels before discharge. In this study, a chemical industry wastewater was treated in a pre-denitrification moving-bed biofilm reactor system subjected to an increasing internal mixed liquor recycle ratio from 2 to 4. Although the influent wastewater characteristics substantially varied over time, the removal of chemical oxygen demand (COD) and dissolved organic carbon was quite stable and mostly higher than 90%. The highest fraction of the incoming organic matter was removed anoxically, favouring a low COD/N environment in the subsequent aerobic nitrifying tank and thus ensuring stable ammonium removal (90-95%). However, during pH and salt shock periods, nitrifiers were severely inhibited but gradually restored their full nitrifying capability as non-stressing conditions were reestablished. Besides promoting an increase in the maximum nitrification potential of the aerobic attached biomass from 0.34 to 0.63 mg [Formula: see text], the increase in the internal recycle ratio was accompanied by an increase in nitrogen removal (60-78%) and maximum specific denitrification rate (2.7-3.3 mg NOx(-)--N). Total polysaccharides (PS) and protein (PT) concentrations of attached biomass were observed to be directly influenced by the influent organic loading rate, while the PS/PT ratio mainly ranged from 0.3 to 0.5. Results of Microtox tests showed that no toxicity was found in the effluent of both the anoxic and aerobic reactors, indicating that the biological process was effective in removing residual substances which might adversely affect the receiving waters' ecosystem.

Interaction of nitrogen with vacancy defects in N+-implanted ZnO studied using a slow positron beam

International Nuclear Information System (INIS)

Chen, Z.Q.; Maekawa, M.; Kawasuso, A.; Suzuki, R.; Ohdaira, T.

2005-01-01

ZnO crystals were implanted with N + , O + , and Al + , and co-implanted with O + /N + and Al + /N + ions. Positron annihilation measurements indicate introduction of vacancy clusters upon implantation. In the N + -implanted and Al + /N + co-implanted samples, these vacancy clusters are only partially annealed at 800 deg. C, as compared with their entire recovery in the O + - and Al + -implanted samples at 800-900 deg. C, suggesting a strong interaction between nitrogen and vacancy clusters. However, in the O + /N + co-implanted sample, most vacancy clusters disappear at 800 deg. C. Probably oxygen scavenges nitrogen to enhance the annealing of the vacancy clusters. Upon further annealing at 1000-1100 deg. C, nitrogen also forms stable complexes with thermally generated vacancies. These nitrogen-related vacancy complexes need high-temperature annealing at 1200-1250 deg. C to be fully removed

Process for separating nitrogen from methane using microchannel process technology

Science.gov (United States)

Tonkovich, Anna Lee [Marysville, OH; Qiu, Dongming [Dublin, OH; Dritz, Terence Andrew [Worthington, OH; Neagle, Paul [Westerville, OH; Litt, Robert Dwayne [Westerville, OH; Arora, Ravi [Dublin, OH; Lamont, Michael Jay [Hilliard, OH; Pagnotto, Kristina M [Cincinnati, OH

2007-07-31

The disclosed invention relates to a process for separating methane or nitrogen from a fluid mixture comprising methane and nitrogen, the process comprising: (A) flowing the fluid mixture into a microchannel separator, the microchannel separator comprising a plurality of process microchannels containing a sorption medium, the fluid mixture being maintained in the microchannel separator until at least part of the methane or nitrogen is sorbed by the sorption medium, and removing non-sorbed parts of the fluid mixture from the microchannel separator; and (B) desorbing the methane or nitrogen from the sorption medium and removing the desorbed methane or nitrogen from the microchannel separator. The process is suitable for upgrading methane from coal mines, landfills, and other sub-quality sources.

Experimental study of nitrogen oxide absorption by a liquid nitrogen tetroxide flow

International Nuclear Information System (INIS)

Verzhinskaya, A.B.; Saskovets, V.V.; Borovik, T.F.

1984-01-01

The system of N 2 O 4 based coolant regeneration needs productive and efficient absorbers, providing effective production of nitrogen oxide, decreasing upon NPP operation at the expense of radiation-thermal decomposition. The experimental istallation flowsheet for studying the nitrogen oxide absorbtion by liquid nitrogen tetroxide is given. The experiments have been carried out in removable test sections, looked like helical tubes with internal steam-and-liquid mixture flow and external water cooling. Six test sections with variable geometry factors have been manufactured. The plotted results of the experiments are given as dependences of extraction level and mass transfer volumetric coefficients on the geometry factor, pressure and Froude number

Experimental study of nitrogen oxide absorption by a liquid nitrogen tetroxide flow

Energy Technology Data Exchange (ETDEWEB)

Verzhinskaya, A B; Saskovets, V V; Borovik, T F

1984-01-01

The system of N/sub 2/O/sub 4/ based coolant regeneration needs productive and efficient absorbers, providing effective production of nitrogen oxide, decreasing upon NPP operation at the expense of radiation-thermal decomposition. The experimental istallation flowsheet for studying the nitrogen oxide absorbtion by liquid nitrogen tetroxide is given. The experiments have been carried out in removable test sections, looked like helical tubes with internal steam-and-liquid mixture flow and external water cooling. Six test sections with variable geometry factors have been manufactured. The plotted results of the experiments are given as dependences of extraction level and mass transfer volumetric coefficients on the geometry factor, pressure and Froude number.

Contaminant removal performances on domestic sewage using modified anoxic/anaerobic/oxic process and micro-electrolysis.

Science.gov (United States)

Zhou, Jun; Gao, Jingqing; Liu, Yifan; Xiao, Shuai; Zhang, Ruiqin; Zhang, Zhenya

2013-01-01

The objective of this study was to enhance removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) from domestic sewage in a sequencing batch reactor with added new materials. A modified anoxic/anaerobic/oxic (MAAO) process, integrating a micro-electrolysis (ME) bed in an anoxic tank, and complex biological media (CBM) in anoxic, anaerobic and oxic tanks to treat domestic sewage, and their performances were investigated. The MAAO system was operated at controlled hydraulic retention time (HRT) of 8 h and mixed liquor recirculation (MLR) at 75%. The results showed that the MAAO system could effectively remove COD, TN and TP with average rates of 93%, 80% and 94%, respectively, in March, and 94%, 76% and 91%, respectively, in August. In this system, TP was primarily removed from the anoxic tank regardless of the operational conditions; removal contribution ratios to TP of the anoxic tank reached 56% both in March and August, indicating that the ME bed can effectively enhance phosphorus removal. TN was primarily removed from the anoxic and anaerobic tanks; removal contribution ratios to TN of anoxic and anaerobic tanks reached 36-38% and 37-38%, respectively. The oxic tank had the highest share of COD removal (56% both in March and August) in the removal of phosphorus. The outflow concentrations of COD, TN and TP were 3-46, 7-14 and 0.3-0.5 mg/L, respectively, in March, and 26-49, 9-15 and 0.04-0.1 mg/L, respectively, in August. COD and TN removal performances indicated that the innovative materials of the ME bed and CBM can effectively enhance COD and TN removal.

Nitrogen deposition does not enhance Sphagnum decomposition.

Science.gov (United States)

Manninen, S; Kivimäki, S; Leith, I D; Leeson, S R; Sheppard, L J

2016-11-15

Long-term additions of nitrogen (N) to peatlands have altered bryophyte growth, species dominance, N content in peat and peat water, and often resulted in enhanced Sphagnum decomposition rate. However, these results have mainly been derived from experiments in which N was applied as ammonium nitrate (NH4NO3), neglecting the fact that in polluted areas, wet deposition may be dominated either by NO3(-) or NH4(+). We studied effects of elevated wet deposition of NO3(-) vs. NH4(+) alone (8 or 56kgNha(-1)yr(-1) over and above the background of 8kgNha(-1)yr(-1) for 5 to 11years) or combined with phosphorus (P) and potassium (K) on Sphagnum quality for decomposers, mass loss, and associated changes in hummock pore water in an ombrotrophic bog (Whim). Adding N, especially as NH4(+), increased N concentration in Sphagnum, but did not enhance mass loss from Sphagnum. Mass loss seemed to depend mainly on moss species and climatic factors. Only high applications of N affected hummock pore water chemistry, which varied considerably over time. Overall, C and N cycling in this N treated bog appeared to be decoupled. We conclude that moss species, seasonal and annual variation in climatic factors, direct negative effects of N (NH4(+) toxicity) on Sphagnum production, and indirect effects (increase in pH and changes in plant species dominance under elevated NO3(-) alone and with PK) drive Sphagnum decomposition and hummock C and N dynamics at Whim. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of novel control strategies for single-stage autotrophic nitrogen removal: A process oriented approach

DEFF Research Database (Denmark)

Vangsgaard, Anna Katrine; Mauricio Iglesias, Miguel; Gernaey, Krist

2014-01-01

operation and rejection of disturbances. Three novel control strategies were developed, evaluated, and benchmarked against each other: a feedforward control (control structure 1 – CS#1), a rule-based feedback control (CS#2), and a feedforward–feedback controller, in which the feedback loop updates the set......The autotrophic nitrogen removing granular sludge process is a novel and intensified process. However, its stable operation and control remain a challenging issue. In this contribution, a process oriented approach was used to develop, evaluate and benchmark novel control strategies to ensure stable...... point of the feedforward loop (CS#3). The CS#1 gave the best performance against disturbances in the ammonium concentration, whereas the CS#2 provided the best performance against disturbances in the organic carbon concentration and dynamic influent conditions. The CS#3 rejected both disturbances...

Recent developments in the biochemistry and ecology of enhanced biological phosphorus removal

NARCIS (Netherlands)

Kortstee, GJJ; Appeldoorn, KJ; Bonting, CFC; van Niel, EWJ; van Veen, HW

Most of the genes encoding the enzymes involved in polyP synthesis and degradation and in phosphate transport have been studied in various Gram-negative bacteria. Progress has also been made in studying the biochemical mechanisms underlying the process of enhanced biological phosphorus removal

Recent developments in the biochemistry and ecology of enhanced biological phosphorus removal

NARCIS (Netherlands)

Kortstee, G.J.J.; Appeldoorn, K.J.; Bonting, C.F.C.; Niel, van E.W.J.; Veen, van H.W.

2000-01-01

Most of the genes encoding the enzymes involved in polyP synthesis and degradation and in phosphate transport have been studied in various Gram-negative bacteria. Progress has also been made in studying the biochemical mechanisms underlying the process of enhanced biological phosphorus removal

Using one filter stage of unsaturated/saturated vertical flow filters for nitrogen removal and footprint reduction of constructed wetlands.

Science.gov (United States)

Morvannou, Ania; Troesch, Stéphane; Esser, Dirk; Forquet, Nicolas; Petitjean, Alain; Molle, Pascal

2017-07-01

French vertical flow constructed wetlands (VFCW) treating raw wastewater have been developed successfully over the last 30 years. Nevertheless, the two-stage VFCWs require a total filtration area of 2-2.5 m 2 /P.E. Therefore, implementing a one-stage system in which treatment performances reach standard requirements is of interest. Biho-Filter ® is one of the solutions developed in France by Epur Nature. Biho-Filter ® is a vertical flow system with an unsaturated layer at the top and a saturated layer at the bottom. The aim of this study was to assess this new configuration and to optimize its design and operating conditions. The hydraulic functioning and pollutant removal efficiency of three different Biho-Filter ® plants commissioned between 2011 and 2012 were studied. Outlet concentrations of the most efficient Biho-Filter ® configuration are 70 mg/L, 15 mg/L, 15 mg/L and 25 mg/L for chemical oxygen demand (COD), 5-day biological oxygen demand (BOD 5 ), total suspended solids (TSS) and total Kjeldahl nitrogen (TKN), respectively. Up to 60% of total nitrogen is removed. Nitrification efficiency is mainly influenced by the height of the unsaturated zone and the recirculation rate. The optimum recirculation rate was found to be 100%. Denitrification in the saturated zone works at best with an influent COD/NO 3 -N ratio at the inflet of this zone larger than 2 and a hydraulic retention time longer than 0.75 days.

Effect of salinity on N₂O production during shortcut biological nitrogen removal from landfill leachate.

Science.gov (United States)

Liu, Mu; Liu, Tiantian; Peng, Yongzhen; Wang, Shuying; Xiao, Han

2014-05-01

Three identical SBR adapted to different salinity were applied to investigate the characteristics of the treatment performance and N2O production [Formula: see text] during shortcut biological nitrogen removal from landfill leachate under various operating parameters. Increase of salinity might deteriorate the activity of the microorganisms leading to the increase of [Formula: see text] , however, the system could be gradually adapted to the inhibition and alleviate the detrimental effect to some extent. The system acclimated to high salinity provided better performance under high salinity shock and a lower possibility of [Formula: see text] , while a sudden decrease in salinity can cause a temporary increase in [Formula: see text] . High salinity strengthened the influence of high ammonia nitrogen concentration and low DO concentration on [Formula: see text] while the strengthening effect was unconspicuous at high DO concentration. The anoxic phase did not produce a significant amount of N2O even at the lowest C/N ratio of 0.5 and was less susceptible to salinity. Characterization of the biomass composition using fluorescence in situ hybridization analysis confirmed that the relative proportion of Nitrosomonas europaea was increased with the increase of the salinity, which may be an important factor for the strengthening effect of salinity on [Formula: see text] . Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Quantitative evaluation of enhanced laser tattoo removal by skin optical clearing

Directory of Open Access Journals (Sweden)

Caihua Liu

2015-05-01

Full Text Available Lasers have been widely used for tattoo removal, but the limited light penetration depth caused by high skin scattering property restricts the therapeutic outcome of deep tattoo. Skin optical clearing method, by introducing optical clearing agent (OCA into skin, has shown some improvement in the effect of laser tattoo removal. In this study, the enhanced laser tattoo removal has been quantitatively assessed. OCA was applied to the skin of tattoo animal model and Q-switched Nd:YAG laser (1064 nm irradiation was used to remove the tattoo. The skin evaluation instrument (Mexameter probe, MPA580 was applied to measure the content of tattoo pigment before and after laser treatment, and then the clearance rate of pigment was calculated. Further, Monte Carlo (MC method was utilized to simulate the effect of skin optical clearing on light transmission in tattoo skin model. By comparing the pigment change of tattoo areas respectively treated with OCA plus laser and single laser, it was found that pigment clearance of the former tattoo area was increased by 1.5-fold. Further, the MC simulation verified that the reduced light scattering in skin could increase the effective dose of luminous flux reaching to the deep tattoo regions. It can be concluded from both experiment and theoretical simulations that skin optical clearing technique could improve the outcome of laser tattoo removal, which should be beneficial for clinical laser tattoo removal and other laser pigment elimination.

Photocatalytic enhancement of cesium removal by Prussian blue-deposited TiO2.

Science.gov (United States)

Kim, Hyuncheol; Kim, Minsun; Kim, Wooyul; Lee, Wanno; Kim, Soonhyun

2018-06-19

After the Fukushima nuclear accident, tremendous efforts were made to treat radiocesium, radiostrontium, and other radioactive materials. For the first time, we demonstrate that a TiO 2 photocatalyst can significantly enhance Cs adsorption by Prussian blue-deposited TiO 2 (PB/TiO 2 ) under UV irradiation. In this study, we synthesized PB/TiO 2 using the photodeposition method. After the Cs ions were adsorbed on the PB/TiO 2 in darkness, we then exposed the PB/TiO 2 to UV light irradiation. This resulted in a further increase in Cs ion adsorption of more than 10 times the amount adsorbed in darkness. This photocatalytic-enhanced adsorption of Cs ions was not observed on PB mixed with SiO 2 , nor under visible light irradiation. We investigated the effects of PB concentration, PB/TiO 2 concentration, and gas purging on both dark and photocatalytic-enhanced adsorption of Cs ions by PB/TiO 2 . Based on the results, we suggest that the photocatalytic-enhanced adsorption of Cs ions on PB/TiO 2 is due to photocatalytic reduction of PB, which leads to additional adsorption of Cs ions. The change in solution color before and after the reaction, and the change in solution pH in the dark and during UV irradiation strongly support this suggestion. The photocatalytic-enhanced adsorption of Cs ions was equivalent during radioactive 137 Cs removal, indicating important applications for pollutant removal from contaminated water. Copyright © 2018 Elsevier B.V. All rights reserved.

The short-term effects of prescribed burning on biomass removal and the release of nitrogen and phosphorus in a treatment wetland.

Science.gov (United States)

White, J R; Gardner, L M; Sees, M; Corstanje, R

2008-01-01

Nutrient removal by constructed wetlands can decline over time due to the accumulation of organic matter. A prescribed burn is one of many management strategies used to remove detritus in macrophyte-dominated systems. We quantified the short-term effects on effluent water quality and the amount of aboveground detritus removed from a prescribed burn event. Surface water outflow concentrations were approximately three times higher for P and 1.5 times higher for total Kjeldhal nitrogen (TKN) following the burn event when compared to the control. The length of time over which the fire effect was significant (P burn, however, much of the live vegetation was converted to standing dead material. These results demonstrate that a prescribed burn can significantly decrease the amount of senescent organic matter in a constructed wetland. However, short-term nutrient releases following the burn could increase effluent nutrient concentrations. Therefore, management strategies should include hydraulically isolating the burned area immediately following the burn event to prevent nutrient export.

Biological Nutrient Removal in Compact Biofilm Systems

NARCIS (Netherlands)

Bassin, J.P.

2012-01-01

The removal of nutrients such as nitrogen and phosphorus from both domestic and industrial wastewaters is imperative since they potentially harm the environment. One of the main consequences of excessive availability of nitrogen and phosphorus in aquatic ecosystems (freshwater, marine and estuarine)

Is nitrogen the next carbon?

Science.gov (United States)

Battye, William; Aneja, Viney P.; Schlesinger, William H.

2017-09-01

Just as carbon fueled the Industrial Revolution, nitrogen has fueled an Agricultural Revolution. The use of synthetic nitrogen fertilizers and the cultivation of nitrogen-fixing crops both expanded exponentially during the last century, with most of the increase occurring after 1960. As a result, the current flux of reactive, or fixed, nitrogen compounds to the biosphere due to human activities is roughly equivalent to the total flux of fixed nitrogen from all natural sources, both on land masses and in the world's oceans. Natural fluxes of fixed nitrogen are subject to very large uncertainties, but anthropogenic production of reactive nitrogen has increased almost fivefold in the last 60 years, and this rapid increase in anthropogenic fixed nitrogen has removed any uncertainty on the relative importance of anthropogenic fluxes to the natural budget. The increased use of nitrogen has been critical for increased crop yields and protein production needed to keep pace with the growing world population. However, similar to carbon, the release of fixed nitrogen into the natural environment is linked to adverse consequences at local, regional, and global scales. Anthropogenic contributions of fixed nitrogen continue to grow relative to the natural budget, with uncertain consequences.

Enhancing mercury removal across air pollution control devices for coal-fired power plants by desulfurization wastewater evaporation.

Science.gov (United States)

Bin, Hu; Yang, Yi; Cai, Liang; Yang, Linjun; Roszak, Szczepan

2017-10-09

Desulfurization wastewater evaporation technology is used to enhance the removal of gaseous mercury (Hg) in conventional air pollution control devices (APCDs) for coal-fired power plants. Studies have affirmed that gaseous Hg is oxidized and removed by selective catalytic reduction (SCR), an electrostatic precipitator (ESP) and wet flue gas desulfurization (WFGD) in a coal-fired thermal experiment platform with WFGD wastewater evaporation. Effects of desulfurization wastewater evaporation position, evaporation temperature and chlorine ion concentration on Hg oxidation were studied as well. The Hg 0 oxidation efficiency was increased ranging from 30% to 60%, and the gaseous Hg removal efficiency was 62.16% in APCDs when wastewater evaporated before SCR. However, the Hg 0 oxidation efficiency was 18.99% and the gaseous Hg removal efficiency was 40.19% in APCDs when wastewater evaporated before ESP. The results show that WFGD wastewater evaporation before SCR is beneficial to improve the efficiency of Hg oxidized and removed in APCDs. Because Hg 2+ can be easily removed in ACPDs and WFGD wastewater in power plants is enriched with chlorine ions, this method realizes WFGD wastewater zero discharge and simultaneously enhances Hg removal in APCDs.

Plant species richness enhances nitrogen retention in green roof plots.

Science.gov (United States)

Johnson, Catherine; Schweinhart, Shelbye; Buffam, Ishi

2016-10-01

Vegetated (green) roofs have become common in many cities and are projected to continue to increase in coverage, but little is known about the ecological properties of these engineered ecosystems. In this study, we tested the biodiversity-ecosystem function hypothesis using commercially available green roof trays as replicated plots with varying levels of plant species richness (0, 1, 3, or 6 common green roof species per plot, using plants with different functional characteristics). We estimated accumulated plant biomass near the peak of the first full growing season (July 2013) and measured runoff volume after nearly every rain event from September 2012 to September 2013 (33 events) and runoff fluxes of inorganic nutrients ammonium, nitrate, and phosphate from a subset of 10 events. We found that (1) total plant biomass increased with increasing species richness, (2) green roof plots were effective at reducing storm runoff, with vegetation increasing water retention more than soil-like substrate alone, but there was no significant effect of plant species identity or richness on runoff volume, (3) green roof substrate was a significant source of phosphate, regardless of presence/absence of plants, and (4) dissolved inorganic nitrogen (DIN = nitrate + ammonium) runoff fluxes were different among plant species and decreased significantly with increasing plant species richness. The variation in N retention was positively related to variation in plant biomass. Notably, the increased biomass and N retention with species richness in this engineered ecosystem are similar to patterns observed in published studies from grasslands and other well-studied ecosystems. We suggest that more diverse plantings on vegetated roofs may enhance the retention capacity for reactive nitrogen. This is of importance for the sustained health of vegetated roof ecosystems, which over time often experience nitrogen limitation, and is also relevant for water quality in receiving waters

Enhancing the biodegradation of oil in sandy sediments with choline: A naturally methylated nitrogen compound

International Nuclear Information System (INIS)

Mortazavi, Behzad; Horel, Agota; Anders, Jennifer S.; Mirjafari, Arsalan; Beazley, Melanie J.; Sobecky, Patricia A.

2013-01-01

We investigated how additions of choline, a naturally occurring methylated nitrogen-containing compound, accelerated hydrocarbon degradation in sandy sediments contaminated with moderately weathered crude oil (4000 mg kg −1 sediment). Addition of lauroylcholine chloride (LCC) and tricholine citrate (TCC) to oil contaminated sediments resulted in 1.6 times higher hydrocarbon degradation rates compared to treatments without added choline derivatives. However, the degradation rate constant for the oil contaminated sediments amended with LCC was similar to that in contaminated sediments amended with inorganic nitrogen, phosphorus, and glucose. Additions of LLC and TCC to sediments containing extensively weathered oil also resulted in enhanced mineralization rates. Cultivation-free 16S rRNA analysis revealed the presence of an extant microbial community with clones closely related to known hydrocarbon degraders from the Gammaproteobacteria, Alphaproteobacteria, and Firmicutes phyla. The results demonstrate that the addition of minimal amounts of organic compounds to oil contaminated sediments enhances the degradation of hydrocarbons. -- Highlights: •Aerobic degradation of weathered crude oil in sandy sediments was determined. •The effect of input of choline on degradation rates was determined. •16S rRNA clone library analyses were used to examine the microbial phylogeny. •The bacterial community was consisted of clones related to hydrocarbon degraders. •Hydrocarbon degradation in sandy sediments was accelerated by addition of choline. -- Choline, a naturally occurring methylated nitrogen-containing compound, accelerated hydrocarbon degradation in sandy sediments by an extant microbial community

Problems of Nitrogen at Central Municipal Water Works in Ostrava

Directory of Open Access Journals (Sweden)

Praus Petr

2003-09-01

Full Text Available Nitrogen is very important nutrient and must be removed during wastewater treatment process. The presented article describes the situation of nitrogen removal at the Central Municipal Water Works in Ostrava. At present, this biological sewage plant operates with only 45% nitrogen removal efficiency. The current three corridor denitrification-nitrification (D-N system is planed to be reconstructed. One of several solution is modification of the activation tank into four step D-N system that could be completed by postdenitrification in the redundant clarifiers.In this paper the analytical methods, used for determination of nitrogen compounds in waste waters, are described as well. Only sufficiently precise and accurate methods must be selected and that is why the standardized or fully validated procedures are preferred. Laboratory results are used for monitoring of treatment process and for making of important technological decisions. For this purpose, introduction of the quality control and quality assurance system into laboratory practise is desired.

Habitat Management: A Tool to Modify Ecosystem Impacts of Nitrogen Deposition?

Directory of Open Access Journals (Sweden)

S.A. Power

2001-01-01

Full Text Available Atmospheric nitrogen deposition has been shown to affect both the structure and the function of heathland ecosystems. Heathlands are semi-natural habitats and, as such, undergo regular management by mowing or burning. Different forms of management remove more or less nutrients from the system, so habitat management has the potential to mitigate some of the effects of atmospheric deposition. Data from a dynamic vegetation model and two field experiments are presented. The first involves nitrogen addition following different forms of habitat management. The second tests the use of habitat management to promote heathland recovery after a reduction in nitrogen deposition. Both modelling and experimental approaches suggest that plant and microbial response to nitrogen is affected by management. Shoot growth and rates of decomposition were lowest in plots managed using more intensive techniques, including mowing with litter removal and a high temperature burn. Field data also indicate that ecosystem recovery from prolonged elevated inputs of nitrogen may take many years, or even decades, even after the removal of plant and litter nitrogen stores which accompanies the more intensive forms of habitat management.

Microalgal bacterial flocs treating paper mill effluent: A sunlight-based approach for removing carbon, nitrogen, phosphorus, and calcium.

Science.gov (United States)

Van Den Hende, Sofie; Rodrigues, André; Hamaekers, Helen; Sonnenholzner, Stanislaus; Vervaeren, Han; Boon, Nico

2017-10-25

Treatment of upflow anaerobic sludge blanket (UASB) effluent from a paper mill in aerated activated sludge reactors involves high aeration costs. Moreover, this calcium-rich effluent leads to problematic scale formation. Therefore, a novel strategy for the aerobic treatment of paper mill UASB effluent in microalgal bacterial floc sequencing batch reactors (MaB-floc SBRs) is proposed, in which oxygen is provided via photosynthesis, and calcium is removed via bio-mineralization. Based on the results of batch experiments in the course of this study, a MaB-floc SBR was operated at an initial neutral pH. This SBR removed 58±21% organic carbon, 27±8% inorganic carbon, 77±5% nitrogen, 73±2% phosphorus, and 27±11% calcium. MaB-flocs contained 10±3% calcium, including biologically-influenced calcite crystals. The removal of calcium and inorganic carbon by MaB-flocs significantly decreased when inhibiting extracellular carbonic anhydrase (CA), an enzyme that catalyses the hydration and dehydration of CO 2 . This study demonstrates the potential of MaB-floc SBRs for the alternative treatment of calcium-rich paper mill effluent, and highlights the importance of extracellular CA in this treatment process. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectroscopic properties of nitrogen doped hydrogenated amorphous carbon films grown by radio frequency plasma-enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Hayashi, Y.; Yu, G.; Rahman, M. M.; Krishna, K. M.; Soga, T.; Jimbo, T.; Umeno, M.

2001-01-01

Nitrogen doped hydrogenated amorphous carbon thin films have been deposited by rf plasma-enhanced chemical vapor deposition using CH 4 as the source of carbon and with different nitrogen flow rates (N 2 /CH 4 gas ratios between 0 and 3), at 300 K. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using different spectroscopic techniques, such as, Raman spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, electron spin resonance (ESR), photoluminescence (PL) and spectroscopic ellipsometry (SE). Raman spectroscopy and IR absorption reveal an increase in sp 2 -bonded carbon or a change in sp 2 domain size with increasing nitrogen flow rate. It is found that the configuration of nitrogen atoms incorporated into an amorphous carbon network gradually changes from nitrogen atoms surrounded by three (σ bonded) to two (π bonded) neighboring carbons with increasing nitrogen flow rate. Tauc optical gap is reduced from 2.6 to 2.0 eV, and the ESR spin density and the peak-to-peak linewidth increase sharply with increasing nitrogen flow rate. Excellent agreement has been found between the measured SE data and modeled spectra, in which an empirical dielectric function of amorphous materials and a linear void distribution along the thickness have been assumed. The influence of nitrogen on the electronic density of states is explained based on the optical properties measured by UV-VIS and PL including nitrogen lone pair band. [copyright] 2001 American Institute of Physics

Lead (II) removal from natural soils by enhanced electrokinetic remediation.

Science.gov (United States)

Altin, Ahmet; Degirmenci, Mustafa

2005-01-20

Electrokinetic remediation is a very effective method to remove metal from fine-grained soils having low adsorption and buffering capacity. However, remediation of soil having high alkali and adsorption capacity via the electrokinetic method is a very difficult process. Therefore, enhancement techniques are required for use in these soil types. In this study, the effect of the presence of minerals having high alkali and cation exchange capacity in natural soil polluted with lead (II) was investigated by means of the efficiency of electrokinetic remediation method. Natural soil samples containing clinoptilolite, gypsum and calcite minerals were used in experimental studies. Moreover, a sample containing kaolinite minerals was studied to compare with the results obtained from other samples. Best results for soils bearing alkali and high sorption capacity minerals were obtained upon addition of 3 mol AcH and application of 20 V constant potential after a remediation period of 220 h. In these test conditions, lead (II) removal efficiencies for these samples varied between 60% and 70% up to 0.55 normalized distance. Under the same conditions, removal efficiencies in kaolinite sample varied between 50% and 95% up to 0.9 normalized distance.

Rapid estimation of organic nitrogen in oil shale wastewaters

Energy Technology Data Exchange (ETDEWEB)

Jones, B.M.; Harris, G.J.; Daughton, C.G.

1984-03-01

Many of the characteristics of oil shale process wastewaters (e.g., malodors, color, and resistance to biotreatment) are imparted by numerous nitrogen heterocycles and aromatic amines. For the frequent performance assessment of waste treatment procsses designed to remove these nitrogenous organic compounds, a rapid and colligative measurement of organic nitrogen is essential.

Instability of biological nitrogen removal in a cokes wastewater treatment facility during summer

International Nuclear Information System (INIS)

Kim, Young Mo; Park, Donghee; Lee, Dae Sung; Park, Jong Moon

2007-01-01

Failure in nitrogen removal of cokes wastewater occurs occasionally during summer season (38 deg. C) due to the instability of nitrification process. The objective of this study was to examine why the nitrification process is unstable especially in summer. Various parameters such as pH, temperature, nutrients and pollutants were examined in batch experiments using activated sludge and wastewater obtained from a full-scale cokes wastewater treatment facility. Batch experiments showed that nitrification rate of the activated sludge was faster in summer (38 deg. C) than in spring or autumn (29 deg. C) and the toxic effects of cyanide, phenol and thiocyanate on nitrification were reduced with increasing temperature. Meanwhile, experiment using continuous reactor showed that the reduction rate in nitrification efficiency was higher at 38 deg. C than at 29 deg. C. In conclusion, the instability of full-scale nitrification process in summer might be mainly due to washing out of nitrifiers by fast growth of competitive microorganisms at higher temperature under increased concentrations of phenol and thiocyanate

Advances in algal-prokaryotic wastewater treatment: A review of nitrogen transformations, reactor configurations and molecular tools.

Science.gov (United States)

Wang, Meng; Keeley, Ryan; Zalivina, Nadezhda; Halfhide, Trina; Scott, Kathleen; Zhang, Qiong; van der Steen, Peter; Ergas, Sarina J

2018-07-01

The synergistic activity of algae and prokaryotic microorganisms can be used to improve the efficiency of biological wastewater treatment, particularly with regards to nitrogen removal. For example, algae can provide oxygen through photosynthesis needed for aerobic degradation of organic carbon and nitrification and harvested algal-prokaryotic biomass can be used to produce high value chemicals or biogas. Algal-prokaryotic consortia have been used to treat wastewater in different types of reactors, including waste stabilization ponds, high rate algal ponds and closed photobioreactors. This review addresses the current literature and identifies research gaps related to the following topics: 1) the complex interactions between algae and prokaryotes in wastewater treatment; 2) advances in bioreactor technologies that can achieve high nitrogen removal efficiencies in small reactor volumes, such as algal-prokaryotic biofilm reactors and enhanced algal-prokaryotic treatment systems (EAPS); 3) molecular tools that have expanded our understanding of the activities of algal and prokaryotic communities in wastewater treatment processes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes.

Science.gov (United States)

Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C; Shimoni, Olga; Aharonovich, Igor

2015-03-21

Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.

Anammox-based technologies for nitrogen removal: Advances in process start-up and remaining issues.

Science.gov (United States)

Ali, Muhammad; Okabe, Satoshi

2015-12-01

Nitrogen removal from wastewater via anaerobic ammonium oxidation (anammox)-based process has been recognized as efficient, cost-effective and low energy alternative to the conventional nitrification and denitrification processes. To date, more than one hundred full-scale anammox plants have been installed and operated for treatment of NH4(+)-rich wastewater streams around the world, and the number is increasing rapidly. Since the discovery of anammox process, extensive researches have been done to develop various anammox-based technologies. However, there are still some challenges in practical application of anammox-based treatment process at full-scale, e.g., longer start-up period, limited application to mainstream municipal wastewater and poor effluent water quality. This paper aimed to summarize recent status of application of anammox process and researches on technological development for solving these remaining problems. In addition, an integrated system of anammox-based process and microbial fuel cell is proposed for sustainable and energy-positive wastewater treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enhanced apatite formation on Ti metal heated in PO2-controlled nitrogen atmosphere.

Science.gov (United States)

Hashimoto, Masami; Hayashi, Kazumi; Kitaoka, Satoshi

2013-10-01

The oxynitridation of biomedical titanium metal under a precisely regulated oxygen partial pressure (PO2) of 10(-14)Pa in nitrogen atmosphere at 973 K for 1 h strongly enhanced apatite formation compared with that on Ti heated in air. The factors governing the high apatite-forming ability are discussed from the viewpoint of the surface properties of Ti heated under a PO2 of 10(-14)Pa in nitrogen atmosphere determined from X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and zeta potential measurements. Nitrogen (N)-doped TiO2 (interstitial N) was formed on pure Ti heated under a PO2 of 10(-14)Pa in nitrogen atmosphere at 973 K. The XPS O1s main peak shifted toward a lower binding energy upon heating under a PO2 of 10(-14)Pa. This shift may be due to the formation of oxygen vacancies. This Ti surface had a positive zeta potential of approximately 20 mV. According to time-of-flight secondary ion mass spectroscopy results, PO4(3-) ions were predominantly adsorbed on Ti soaked in simulated body fluid (SBF) after heat treatment, followed by calcium ions. It was concluded that the apatite formation kinetics can be described using the Avrami-Erofeev equation with an Avrami index of n=2, which implies the instantaneous nucleation of apatite on the surface of Ti soaked in SBF after heat treatment at 973 K under a PO2 of 10(-14)Pa. Copyright © 2013 Elsevier B.V. All rights reserved.

Effective removal of trace thallium from surface water by nanosized manganese dioxide enhanced quartz sand filtration.

Science.gov (United States)

Huangfu, Xiaoliu; Ma, Chengxue; Ma, Jun; He, Qiang; Yang, Chun; Zhou, Jian; Jiang, Jin; Wang, Yaan

2017-12-01

Thallium (Tl) has drawn wide concern due to its high toxicity even at extremely low concentrations, as well as its tendency for significant accumulation in the human body and other organisms. The need to develop effective strategies for trace Tl removal from drinking water is urgent. In this study, the removal of trace Tl (0.5 μg L -1 ) by conventional quartz sand filtration enhanced by nanosized manganese dioxide (nMnO 2 ) has been investigated using typical surface water obtained from northeast China. The results indicate that nMnO 2 enhanced quartz sand filtration could remove trace Tl(I) and Tl(III) efficiently through the adsorption of Tl onto nMnO 2 added to a water matrix and onto nMnO 2 attached on quartz sand surfaces. Tl(III)-HA complexes might be responsible for higher residual Tl(III) in the effluent compared to residual Tl(I). Competitive Ca 2+ cations inhibit Tl removal to a certain extent because the Ca 2+ ions will occupy the Tl adsorption site on nMnO 2 . Moreover, high concentrations of HA (10 mgTOC L -1 ), which notably complexes with and dissolves nMnO 2 (more than 78%), resulted in higher residual Tl(I) and Tl(III). Tl(III)-HA complexes might also enhance Tl(III) penetration to a certain extent. Additionally, a higher pH level could enhance the removal of trace Tl from surface water. Finally, a slight increase of residual Tl was observed after backwash, followed by the reduction of the Tl concentration in the effluent to a "steady" state again. The knowledge obtained here may provide a potential strategy for drinking water treatment plants threatened by trace Tl. Copyright © 2017. Published by Elsevier Ltd.

Optimization of operation conditions for the startup of aerobic granular sludge reactors biologically removing carbon, nitrogen, and phosphorous.

Science.gov (United States)

Lochmatter, Samuel; Holliger, Christof

2014-08-01

The transformation of conventional flocculent sludge to aerobic granular sludge (AGS) biologically removing carbon, nitrogen and phosphorus (COD, N, P) is still a main challenge in startup of AGS sequencing batch reactors (AGS-SBRs). On the one hand a rapid granulation is desired, on the other hand good biological nutrient removal capacities have to be maintained. So far, several operation parameters have been studied separately, which makes it difficult to compare their impacts. We investigated seven operation parameters in parallel by applying a Plackett-Burman experimental design approach with the aim to propose an optimized startup strategy. Five out of the seven tested parameters had a significant impact on the startup duration. The conditions identified to allow a rapid startup of AGS-SBRs with good nutrient removal performances were (i) alternation of high and low dissolved oxygen phases during aeration, (ii) a settling strategy avoiding too high biomass washout during the first weeks of reactor operation, (iii) adaptation of the contaminant load in the early stage of the startup in order to ensure that all soluble COD was consumed before the beginning of the aeration phase, (iv) a temperature of 20 °C, and (v) a neutral pH. Under such conditions, it took less than 30 days to produce granular sludge with high removal performances for COD, N, and P. A control run using this optimized startup strategy produced again AGS with good nutrient removal performances within four weeks and the system was stable during the additional operation period of more than 50 days. Copyright © 2014 Elsevier Ltd. All rights reserved.

Preparation of nitrogen-doped cotton stalk microporous activated carbon fiber electrodes with different surface area from hexamethylenetetramine-modified cotton stalk for electrochemical degradation of methylene blue

Directory of Open Access Journals (Sweden)

Kunquan Li

Full Text Available Cotton-stalk activated carbon fibers (CSCFs with controllable micropore area and nitrogen content were prepared as an efficient electrode from hexamethylenetetramine-modified cotton stalk by steam/ammonia activation. The influence of microporous area, nitrogen content, voltage and initial concentration on the electrical degradation efficiency of methylene blue (MB was evaluated by using CSCFs as anode. Results showed that the CSCF electrodes exhibited excellent MB electrochemical degradation ability including decolorization and COD removal. Increasing micropore surface area and nitrogen content of CSCF anode leaded to a corresponding increase in MB removal. The prepared CSCF-800-15-N, which has highest N content but lowest microporous area, attained the best degradation effect with 97% MB decolorization ratio for 5 mg/L MB at 12 V in 4 h, implying the doped nitrogen played a prominent role in improving the electrochemical degradation ability. The electrical degradation reaction was well described by first-order kinetics model. Overall, the aforesaid findings suggested that the nitrogen-doped CSCFs were potential electrode materials, and their electrical degradation abilities could be effectively enhanced by controlling the nitrogen content and micropore surface area. Keywords: Cotton stalk, Nitrogen content, Electrode, Surface area, Methylene blue

Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with metal-phenolic networks

OpenAIRE

Bray, Kerem; Previdi, Rodolfo; Gibson, Brant C.; Shimoni, Olga; Aharonovich, Igor

2015-01-01

Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and biolabeling. In this work we demonstrate a robust approach to surface functionalize individual nanodiamonds with metal-phenolic networks that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation suppr...

System for removing contaminated surface layers

International Nuclear Information System (INIS)

Yoshikawa, Kozo.

1987-04-01

The object of the present invention is to offer a new type of useful decontamination system, with which the contaminated surface layers can be removed effectively by injection of such solid microparticles. Liquid carbon dioxide is passed from a liquid carbon dioxide tank via the carbon dioxide supply line into the system for injecting solid carbon dioxide particles. Part of the liquid carbon dioxide introduced into the system is converted to solid carbon dioxide particles by the temperature drop resulting from adiabatic expansion in the carbon dioxide expansion space of the injection system. The solid carbon dioxide particles reach the injection nozzle, which is connected through the expansion space. The carbon dioxide microparticles are further cooled and accelerated by nitrogen gas injected from the nitrogen gas nozzle at the tip of the nitrogen gas supply line, which is connected to a liquid nitrogen tank. The cooled and accelerated solid carbon dioxide microparticles are injected from the injection nozzle for the solid carbon dioxide and directed against the contaminated surface to be cleaned, and, as a result, the surface contamination is removed

Combined metals and EDTA control: An integrated and scalable lipid enhancement strategy to alleviate biomass constraints in microalgae under nitrogen limited conditions

International Nuclear Information System (INIS)

Singh, Poonam; Guldhe, Abhishek; Kumari, Sheena; Rawat, Ismail; Bux, Faizal

2016-01-01

Highlights: • A. obliquus showed highest lipid productivity amongst all seven microalgal strains. • Combined metals stress eased the constraint of low biomass under limited nitrogen. • Combined metals stress enhanced the overall lipid productivity (1.99 fold). • EDTA addition further improved the lipid productivity (2.18 fold). • This strategy showed 2.08 fold increase in lipid productivity at 3000 L cultivation. - Abstract: The commercial realization of microalgal biodiesel production necessitates substantial impulsion towards development of strategies to improve lipid yields upstream. Nitrogen stress is the most widely used lipid enhancement strategy; yet, it is associated with compromised biomass productivity. In this novel approach, combined effect of metals and EDTA on lipid productivity of Acutodesmus obliquus was investigated under nitrogen limited conditions. The effect of metal concentrations, individually and in combination, on microalgal lipids and biomass production is a scarcely exploited area. Combined metal stress alleviates the constraint of low biomass production under nitrogen limitation and improved the overall lipid productivity. Highest lipid productivity of 73.23 mg L"−"1 d"−"1 was achieved with a combination of iron 9 mg L"−"1, magnesium 100 mg L"−"1 and calcium 27 mg L"−"1 at limited nitrogen (750 mg L"−"1). This was 1.72 fold higher than nitrogen stress alone and 1.99 fold higher than BG11 medium. Iron was found to be most significantly influencing metal followed by magnesium in response surface methodology data analysis. The enhanced photosynthetic performance and chlorophyll content further confirmed the significant impact of iron and magnesium on the microalgal biomass. The addition of EDTA to the optimised metal combination further improved the lipid productivity to 80.23 mg L"−"1 d"−"1 (2.18 fold). At 3000 L open cultivation pond this strategy has resulted in an increase of 2.08 fold in lipid productivity

Phosphorous removal from aqueous solution can be enhanced through the calcination of lime sludge.

Science.gov (United States)

Bal Krishna, K C; Niaz, Mohamed R; Sarker, Dipok C; Jansen, Troy

2017-09-15

Water treatment plants generate an enormous amount of the sludge which is normally treated as waste. In the recent past, many investigations have been focused on developing an economical adsorbent using water treatment sludge to remove phosphorous (P) from aqueous solutions. However, the great extents of the studies have been limited in the use of alum- and iron-based sludges. This study, therefore, investigated the P removal performance of the calcined lime sludge. Calcined lime sludge at 700 °C significantly enhanced the P removal efficiency whereas marginal improvement was noted when the sludge calcined at 400 °C was tested. With increase P removal efficiency, final pH values of the solution also significantly increased. P removal efficiency of the calcined sludge decreased with increasing the initial P concentrations. However, the removal efficiency could be improved by increasing the weight of the sludge. Further analysis demonstrated that P removal trend followed both pseudo-second order and diffusion-chemisorption kinetics signifying the P removal is potentially due to a multi-mechanistic reaction in which, the process is controlled by intra-particle diffusion followed by chemisorptions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancement of plaque removal by baking soda toothpastes from less accessible areas in the dentition.

Science.gov (United States)

Thong, S; Hooper, W; Xu, Y; Ghassemi, A; Winston, A

2011-01-01

To determine if baking soda toothpastes are relatively more effective than non-baking soda toothpastes in promoting plaque removal from less accessible sites in the dentition. Several single-brushing comparisons of baking soda and non-baking soda toothpastes for their overall ability to remove plaque have been published. In this study, individual comparisons of these published data, comparing the plaque removal performance of baking soda and non-baking soda toothpastes at various sites in the dentition, were examined to see if there were any site-dependant performance trends. The site-specific single-brushing data were then combined and analyzed in two ways. Meta-analyses of the clinical studies were performed to compare baking soda's relative plaque removal advantage at various sites in the mouth using paired t-testing at p baking soda toothpastes were graphically compared with plaque index reductions due to brushing with non-baking soda dentifrices. The percent relative plaque removal advantage for baking soda toothpastes at various sites were plotted against the reduction in plaque index due to brushing with non-baking soda toothpastes. Individual comparisons showed that brushing with the toothpastes containing baking soda generally removed significantly more plaque from each site than brushing with toothpastes without baking soda. The relative efficacy advantage for baking soda toothpastes was consistently higher at sites where the non-baking soda toothpastes removed less plaque. Meta-analytical comparisons confirmed baking soda toothpastes to be relatively more effective in enhancing plaque removal from sites where less plaque was removed compared to brushing with non-baking soda toothpastes (p baking soda toothpastes' relative plaque removal advantage could be seen to increase hyperbolically with decreasing plaque removal by the non-baking soda toothpastes with which they were compared. We presuppose that the reason less plaque is removed by non-baking soda

Biofilter design for effective nitrogen removal from stormwater - influence of plant species, inflow hydrology and use of a saturated zone.

Science.gov (United States)

Payne, Emily G I; Pham, Tracey; Cook, Perran L M; Fletcher, Tim D; Hatt, Belinda E; Deletic, Ana

2014-01-01

The use of biofilters to remove nitrogen and other pollutants from urban stormwater runoff has demonstrated varied success across laboratory and field studies. Design variables including plant species and use of a saturated zone have large impacts upon performance. A laboratory column study of 22 plant species and designs with varied outlet configuration was conducted across a 1.5-year period to further investigate the mechanisms and influences driving biofilter nitrogen processing. This paper presents outflow concentrations of total nitrogen from two sampling events across both 'wet' and 'dry' frequency dosing, and from sampling across two points in the outflow hydrograph. All plant species were effective under conditions of frequent dosing, but extended drying increased variation between species and highlighted the importance of a saturated zone in maintaining biofilter function. The saturated zone also effectively treated the volume of stormwater stored between inflow events, but this extended detention provided no additional benefit alongside the rapid processing of the highest performing species. Hence, the saturated zone reduced performance differences between plant species, and potentially acts as an 'insurance policy' against poor sub-optimal plant selection. The study shows the importance of biodiversity and inclusion of a saturated zone in protecting against climate variability.

Isotope studies on the comparative efficiency of nitrogenous sources

Energy Technology Data Exchange (ETDEWEB)

Dev, G; Rennie, D A [Saskatchewan Univ., Saskatoon (Canada). Dept. of Soil Science

1979-03-01

In a growth chamber experiment with /sup 15/N-labelled potassium nitrate, ammonium sulphate and urea at 75 and 150kg nitrogen/ha and ammonium nitrate at 150kg nitrogen/ha, nitrogen application produced significant responses of dry matter yield and total nitrogen uptake by shoot and root of barley in chernozemic dark brown Elstow silt loam and deep black Hoey clay soil. Total nitrogen removal per pot and isotope-derived criteria, viz. percentage nitrogen derived from fertilizer, 'A' value and percentage fertilizer nitrogen utilization, indicated that potassium nitrate was the most efficient and urea the least.

Factoring stream turbulence into global assessments of nitrogen pollution.