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1
Hong, Xiaohong, Liaofan Tang, Haixia Feng, Xiaolei Zhang, and Xianqiong Hu. "Agriculture Waste as Slow Carbon Releasing Source of Mixotrophic Denitrification Process for Treating Low C/N Wastewater." Separations 9, no. 10 (October 21, 2022): 323. http://dx.doi.org/10.3390/separations9100323.
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Mixotrophic denitrification has showed great potential for treating wastewater with a low C/N ratio. Mixotrophic denitrification is the process combining autotrophic denitrification and heterotrophic denitrification in one system. It can compensate the disadvantage of the both denitrifications. Instead of using sodium acetate and glucose as carbon source for the heterotrophic denitrification, agriculture solid wastes including rice straw (RS), wheat straw (WS), and corncob (CC) were employed in this study to investigate their potential as carbon source for treating low C/N wastewater. The carbon releasing pattern of the three carbon rich materials has been studied as well as their capacity in denitrification. The results showed that the highest denitrification occurred in the corncob system which was 0.34 kg N/(m3·d). Corncob was then selected to combine with sulfur beads to build the mixotrophic denitrification system. The reactor packed with sulfur bead on the top and corncob on the bottom achieved 0.34 kg N/(m3·d) denitrification efficiency, which is higher than that of the reactor packed with completely mixed sulfur bead and corncob. The autotrophic denitrification and heterotrophic denitrification were 42.2% and 57.8%, respectively. The microorganisms in the sulfur layer were Thermomonas, Ferritrophicum, Thiobacillus belonging to autotrophic denitrification bacteria. Kouleothrix and Geothrix were mostly found in the corncob layer, which have the function for fiber hydrolysis and denitrification. The study has provided an insight into agriculture solid waste application and enhancement on denitrification of wastewater treatment.
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Xie, Li, Chi Ji, Rui Wang, and Qi Zhou. "Microbial Communities in Anaerobic Acidification-Denitrification and Methanogenesis Process for Cassava Stillage Treatment." Applied Mechanics and Materials 522-524 (February 2014): 573–78. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.573.
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This study investigated operational performance and microbial communities in the integrated acidification-denitrification bioreactor and the followed methanogenesis process. Industrial wastewater, cassava stillage (CS) was used as the carbon source amended with or without nitrate. The results showed that acidification and denitrification could occur simultaneously in a single acidification-denitrification reactor, and denitrificatoin did not suppress the acidogenic activity. Both denitrification and DNRA could contribute to nitrate reduction and proportions of them were about 60% and 40% respectively at the tested condition of COD/NO3-Nof 50. The introduction of nitrate into acidogenic phase did not have any effect on the followed methanogenic process. Microbial communities sampled from two systems were analyzed by culture-independent techniques based on PCR-DGGE. The relative abundance of acid-producing bacteria (primarily Parabacteroides distasonis and Chloroflexi) in the nitrate-amended reactor further confirmed that the addition of nitrate did not suppress the activity of acid-producing bacteria. Bacteria involved in denitrification and DNRA were also detected. The archaeal communities in methanogenic reactors of two systems showed no significant differences. And Methanoculleus and Methanolobus were the dominant bacteria in the culture.
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de Beer, Dirk, Andreas Schramm, Cecilia M. Santegoeds, and Helle K. Nielsen. "Anaerobic processes in activated sludge." Water Science and Technology 37, no. 4-5 (February 1, 1998): 605–8. http://dx.doi.org/10.2166/wst.1998.0726.
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We found anoxic zones in aerated activated sludge flocs, and demonstrated denitrification under normal operating conditions. Sulfate reduction was not found. Micro-environments and microbial conversions in flocs from bulking and non-bulking activated sludge were determined with microsensors for H2S, O2, NO2− and NO3−. Denitrification and sulfate reduction rates were mmeasured with 15N- and 35S-tracer techniques. We showed that under normal reactor conditions (ca. 20% air saturation) anoxic zones develop within flocs allowing denitrification. The denitrification rates amounted to 40% of the rates under anoxic conditions. At 100% air saturation no anoxic zones were found and no denitrification occurred. However, in flocs from bulking sludge (at 20% air saturation) anoxic zones were absent and denitrification did not occur. In bulking sludge only at total anoxia was denitrification found. Confocal microscopy showed that flocs from bulking sludge were much looser than those from non-bulking sludge. The absence of anoxic zones and of denitrification was attributed to the open floc structure, allowing advective oxygen transport. Sulfate reduction was not detected in any of the sludges tested by microsensors or by tracer techniques even under anoxic conditions. this indicates that the sulfur cycle (sulfate reduction and sulfide oxidation) does not play a role in mineralization processes and bulking in activated sludge. Preliminary molecular work (in situ hybridization with the 16S-rRNA probe SRB385) indicated the presence of small amounts of sulfate reducing bacteria in all sludges. Either the probe is not specific or the sulfate reducers present are not active under reactor conditions.
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Saeed, Waleed, Orfan Shouakar-Stash, Andrè Unger, and Warren W. Wood. "Application of Multi-Tracer Methods to Evaluate Nitrate Sources and Transformation in Sabkha Matti (Saudi Arabia)." E3S Web of Conferences 98 (2019): 12018. http://dx.doi.org/10.1051/e3sconf/20199812018.
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An unusually high concentration of nitrate (NO3) ranging between 291 and 6790 mg/L (as N) was observed during a review of solute data for brine samples from the inland Sabkha Matti. A multi-tracer approach considering water chemistry, stable nitrate isotopes (δ15N and δ18O), and the radioactive isotope of hydrogen (tritium, 3H) was utilized to evaluate the nitrate sources and transformation in this hydrogeological setting. The results suggested that the source of the high nitrate levels is related to a leakage from a manure/septic system near the proximal eastern edge of the Sabkha. Moreover, the impact of Sabkha’s characteristics on biological denitrifications was evaluated in this study. The results suggest that denitrification was not a major process in Sabkha Matti. Several factors may contribute to the limitation of denitrification on the brine samples including high dissolved oxygen contents, high salinity and chloride.
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Kuenen, J. Gijs, and Lesley A. Robertson. "Combined nitrification-denitrification processes." FEMS Microbiology Reviews 15, no. 2-3 (October 1994): 109–17. http://dx.doi.org/10.1111/j.1574-6976.1994.tb00129.x.
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Dorias, Bernd, and Peter Baumann. "Denitrification in trickling filters." Water Science and Technology 30, no. 6 (September 1, 1994): 181–84. http://dx.doi.org/10.2166/wst.1994.0267.
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National and international regulations require a minimum nitrogen removal efficiency of 70% in most public sewage treatment plants. Unlike in activated sludge plants, selective denitrification in trickling filters was not possible until now. Therefore the aim was to employ trickling filter plants for selective denitrification, using innovative technology that involved minimum capital expenditure. For selective denitrification, it is necessary to prevent as much as possible the transfer of oxygen into the trickling filter while feeding the nitrate to be removed, a process similar to upstream denitrification in the activated sludge process. In a test operation conducted in several sewage treatment plants for over a year, the new process with selective denitrification in a covered trickling filter has given successful results. The denitrification efficiency of this system is comparable to that of upstream denitrification in the activated sludge process. Thus, selective denitrification in the trickling filter is a practical alternative to other nitrogen removal processes, while maintaining the established advantages offered by the trickling filter process.
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Deng, Weifeng, Litao Wang, Lang Cheng, Wenbo Yang, and Dawen Gao. "Nitrogen Removal from Mature Landfill Leachate via Anammox Based Processes: A Review." Sustainability 14, no. 2 (January 17, 2022): 995. http://dx.doi.org/10.3390/su14020995.
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Mature landfill leachate is a complex and highly polluted effluent with a large amount of ammonia nitrogen, toxic components and low biodegradability. Its COD/N and BOD5/COD ratios are low, which is not suitable for traditional nitrification and denitrification processes. Anaerobic ammonia oxidation (anammox) is an innovative biological denitrification process, relying on anammox bacteria to form stable biofilms or granules. It has been extensively used in nitrogen removal of mature landfill leachate due to its high efficiency, low cost and sludge yield. This paper reviewed recent advances of anammox based processes for mature landfill leachate treatment. The state of the art anammox process for mature landfill leachate is systematically described, mainly including partial nitrification–anammox, partial nitrification–anammox coupled denitrification. At the same time, the microbiological analysis of the process operation was given. Anaerobic ammonium oxidation (anammox) has the merit of saving the carbon source and aeration energy, while its practical application is mainly limited by an unstable influent condition, operational control and seasonal temperature variation. To improve process efficiency, it is suggested to develop some novel denitrification processes coupled with anammox to reduce the inhibition of anammox bacteria by mature landfill leachate, and to find cheap new carbon sources (methane, waste fruits) to improve the biological denitrification efficiency of the anammox system.
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Mikawa, Kazuhiro, Hiroyoshi Emori, Tadashi Takeshima, Eiichi Ishiyama, and Kazuhiro Tanaka. "High rate and compact two-stage post-denitrification process with single-sludge pre-denitrification." Water Science and Technology 34, no. 1-2 (July 1, 1996): 467–75. http://dx.doi.org/10.2166/wst.1996.0405.
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For the sewage treatment plants near rivers and closed water bodies in urbanized areas there is a growing demand for introduction of advanced treatment processes for nitrogen and phosphorus removal for water quality conservation and environmental protection. In order to achieve the total nitrogen content of below 10 mg/L in effluent, a compact single sludge pre-denitrification process by dosing immobilized pellets in the nitrification tank (PEGASUS process) has been already developed (Tanaka et al. 1992). Furthermore, a two-stage PEGASUS process and a PEGASUS process with post-denitrification were developed and investigated for nitrogen removal. Both processes achieved the total nitrogen of less than 5mg/L.
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Zhang, Qian, Xue Chen, Heng Wu, Wandong Luo, Xiangyang Liu, Li Feng, and Tiantao Zhao. "Comparison of Clay Ceramsite and Biodegradable Polymers as Carriers in Pack-bed Biofilm Reactor for Nitrate Removal." International Journal of Environmental Research and Public Health 16, no. 21 (October 29, 2019): 4184. http://dx.doi.org/10.3390/ijerph16214184.
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In recent years, there is a trend of low C/N ratio in municipal domestic wastewater, which results in serious problems for nitrogen removal from wastewater. The addition of an external soluble carbon source has been the usual procedure to achieve denitrification. However, the disadvantage of this treatment process is the need of a closed, rather sophisticated and costly process control as well as the risk of overdosing. Solid-phase denitrification using biodegradable polymers as biofilm carrier and carbon source was considered as an attractive alternative for biological denitrification. The start-up time of the novel process using PCL (polycaprolactone) as biofilm carrier and carbon source was comparable with that of conventional process using ceramsite as biofilm carrier and acetate as carbon source. Further, the solid-phase denitrification process showed higher nitrogen removal efficiency under shorter hydraulic retention time (HRT) and low carbon to nitrogen (C/N) ratio since the biofilm was firmly attached to the clear pores on the surface of PCL carriers and in this process bacteria that could degrade PCL carriers to obtain electron donor for denitrification was found. In addition, solid-phase denitrification process had a stronger resistance of shock loading than that in conventional process. This study revealed, for the first time, that the physical properties of the biodegradable polymer played a vital role in denitrification, and the different microbial compositions of the two processes was the main reason for the different denitrification performances under low C/N ratio.
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Capodaglio, Andrea G., Petr Hlavínek, and Massimo Raboni. "Advances in wastewater nitrogen removal by biological processes: state of the art review." Ambiente e Agua - An Interdisciplinary Journal of Applied Science 11, no. 2 (April 15, 2016): 250. http://dx.doi.org/10.4136/ambi-agua.1772.
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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.
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Gao, Lin, Chen Liu, Mingcong Li, and Xianbiao Lin. "Sediment Nitrate Dissimilatory Reduction Processes along a Salinity Gradient in an Estuarine and Coastal Wetland, China." Journal of Marine Science and Engineering 10, no. 6 (May 31, 2022): 761. http://dx.doi.org/10.3390/jmse10060761.
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Nitrate (NO3−) dissimilatory reduction processes (denitrification, anammox and dissimilatory NO3− reduction to ammonium (DNRA)) in estuarine and coastal ecosystems play a crucial role in regulating reactive nitrogen loadings. However, nitrate reduction process rates and relative proportions along the estuarine salinity gradient remain poorly understood. Here, denitrification, anammox and DNRA were explored simultaneously along a salinity gradient in Yangtze Estuary based on nitrogen isotope-tracing experiments. Measured denitrification, anammox and DNRA process rates were in the range of 2.33–28.21 nmol g−1 h−1, 0.43–1.87 nmol g−1 h−1 and 0.28–0.74 nmol g−1 h−1, respectively, with a large spatio-temporal variation. The changes in these nitrate reduction process rates were mainly affected by the TOC, TN, NH4+ and NOx− concentrations, rather than salinity and related functional gene abundance. Denitrification dominated the total NO3− reduction process (67.52 to 93.85%), while anammox (3.67 to 25.01%) and DNRA (2.48 to 11.21%) also played a substantially important role in nitrate reduction. The proportions of denitrification to gross nitrate reduction in high-salinity areas were generally lower than those in freshwater, but the opposite was true for DNRA. Overall, our study reported the simultaneous observation of nitrate dissimilatory reduction processes along the salinity gradient of the estuary and highlighted that changes in sediment environmental variables affected by human activities can alter the distribution patterns of NO3− reduction processes.
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Xu, Guihua, Cuijie Feng, Fang Fang, Shaohua Chen, Yuanjian Xu, and Xingzu Wang. "The heterotrophic-combined-with-autotrophic denitrification process: performance and interaction mechanisms." Water Science and Technology 71, no. 8 (February 26, 2015): 1212–18. http://dx.doi.org/10.2166/wst.2015.097.
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In this work, the interaction mechanisms between an autotrophic denitrification (AD) and heterotrophic denitrification (HD) process in a heterotrophic-autotrophic denitrification (HAD) system were investigated, and the performance of the HAD system under different S/Ac− molar ratios was also evaluated. The results demonstrated that the heterotrophic-combined-with-autotrophic denitrification process is a promising technology which can remove chemical oxygen demand (COD), sulfide and nitrate simultaneously. The reduction rate of NO3− to NO2− by the HD process was much faster than that of reducing NO2− to N2, while the reduction rate of NO3− to NO2− by the AD process was slower than that of NO2− to N2. Therefore, the AD process could use the surplus NO2− produced by the HD process. This could alleviate the NO2−–N accumulation and increase the denitrification rate. In addition, the inhibition effects of acetate on AD bacteria and sulfide on HD were observed, and the inhibition was compensated by the promotion effects on NO2−. Therefore, the processes of AD and HD seem to react in parallel, without disturbing each other, in our HAD system.
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Tonkovic, Zlatko. "Energetics of enhanced biological phosphorus and nitrogen removal processes." Water Science and Technology 38, no. 1 (July 1, 1998): 177–84. http://dx.doi.org/10.2166/wst.1998.0043.
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Recent advances by researchers with in vivo NMR spectroscopy using labelled isotopes of carbon and phosphorus have elucidated some of the biochemical pathways involved in enhanced biological phosphorus and nitrogen removal processes. This has permitted a greater understanding of carbon and phosphorus cycling within cellular processes. All microbiological processes associated with energy transformations are dependent on enzyme induction. The enhanced phosphorus removal apparatus in certain organisms is dependent on the environmental conditions in order to induce the necessary enzymes. Enzyme expression has been linked to redox potential, which itself is a function of the culture medium and the bioenergetic condition of the cells. Redox balance is coupled to several pathways in the metabolic network of microorganisms. Changes to the redox potential result in shifts in the metabolic pathway utilisation. In the past, nitrification and denitrification have been thought to be strictly aerobic and anoxic processes respectively. Mounting evidence has demonstrated that this classical view of nitrification and denitrification is no longer valid and that other processes can occur such as simultaneous nitrification and denitrification and aerobic denitrification. Enzyme induction plays a very important role in these processes. Attempts have been made in this paper to elucidate the energetics of anaerobic phosphorus release based on cellular composition and various other plant operating parameters. Energetics of the denitrification process including anoxic dephosphatation, aerobic denitrification, with potential reduction in aerobic treatment requirements, are also explored.
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Lv, Shuai-Shuai, Yu Zhang, Hong-Jun Ni, Xing-Xing Wang, Wei-Yang Wu, and Chun-Yu Lu. "Effects of Additive and Roasting Processes on Nitrogen Removal from Aluminum Dross." Coatings 12, no. 6 (May 25, 2022): 730. http://dx.doi.org/10.3390/coatings12060730.
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Taking high nitrogen aluminum dross as the research object, the effects of the additives sodium carbonate and cryolite and the roasting process on the denitrification effect of aluminum dross were studied. The principle of additive denitrification was studied by XRD, SEM and TG-DSC. The experimental results show that sodium carbonate and cryolite can quickly reduce the content of aluminum nitride in aluminum dross. The optimum denitrification process parameters were also obtained simultaneously. When the mass ratio of cryolite to aluminum dross was 0.4, the roasting temperature was 900 °C, and the roasting time was 3 h, the denitrification degree could reach 96.19%. When the mass ratio of sodium carbonate to aluminum dross was 0.8, the roasting temperature was 1000 °C, and the roasting time was 4 h, the denitrification degree could reach 91.32%. This study provides a reference for the non-harmful treatment of high nitrogen aluminum dross.
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Yin, Fang-Fang, and Hui-Fang Guo. "Influence of additional methanol on both pre- and post-denitrification processes in treating municipal wastewater." Water Science and Technology 85, no. 5 (February 16, 2022): 1434–43. http://dx.doi.org/10.2166/wst.2022.060.
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Abstract Changes in functional properties of biological denitrification in the long-term use of methanol were explored in both pre- and post-denitrification processes. The two systems employed were sequencing batch reactor (SBR) using post-denitrification in temporal sequence, and Carrousel oxidation ditch, which was equipped with a separate pre-denitrification zone. In the SBR, stable nitrate reduction rates reached after 37 days elapsed with addition of methanol (TOC/N = 1.4–1.8) at the start of anoxic phase, and specific denitrification rate increased from 0.378 mgNOx-N·(gVSS·h)−1 to 2.406 mgNOx-N·(gVSS·h)−1. Besides, by means of nitrogen uptake rate (NUR) batch tests based on methanol-adapted sludge, the appropriate range of TOC/N ratios for complete denitrification was estimated to be 1.10–2.68. By comparison, the Carrousel oxidation ditch that was fed with methanol in the anaerobic zone took fewer days (29 days) to obtain a constant effluent nitrate. Moreover, the denitrification yield in ditch was elevated from an initial value of 0.082 mgTN/mgCOD to 0.123 mgTN/mgCOD, and the nitrogen removal efficiency reached up to a level of 68%. The focus on denitrification potential with external methanol is valuable to provide information for developing carbon dosage control, as well as predict the nitrate effluent quality of the plant.
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Naqvi, S. W. A. "Denitrification processes in the Arabian Sea." Journal of Earth System Science 103, no. 2 (June 1994): 279–300. http://dx.doi.org/10.1007/bf02839539.
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Sözen, S., N. Artan, D. Orhon, and E. Avcioglu. "Assessment of the denitrification potential for biological nutrient removal processes using OUR/NUR measurements." Water Science and Technology 46, no. 9 (November 1, 2002): 237–46. http://dx.doi.org/10.2166/wst.2002.0248.
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The denitrification potential, a key parameter in nutrient removal activated sludge systems, is mathematically described in terms of mass balance expressions for different carbon sources, namely, easily biodegradable substrate, slowly biodegradable substrate and biomass. Mass balance was derived both for single-anoxic (pre-denitrification) and dual anoxic (Bardenpho) systems. Correction factors for anoxic growth were experimentally determined using respirometry for domestic sewage and meat processing wastewater. The denitrification potential expressions were evaluated for different process configurations such as pre-denitrification, Bardenpho process and University of Cape Town (UCT) process.
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Bailey, Walter, Akile Tesfaye, Jerry Dakita, Michael McGrath, Glenn Daigger, Alex Benjamin, and Thomas Sadick. "Large-scale nitrogen removal demonstration at the blue plains wastewater treatment plant using post-denitrification with methanol." Water Science and Technology 38, no. 1 (July 1, 1998): 79–86. http://dx.doi.org/10.2166/wst.1998.0021.
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The Chesapeake Bay Agreement of 1987 calls for an overall reduction in nutrient loading of forty percent of 1985 levels by the year 2000. Signatories to the agreement include the states located in the Bay's watershed and the District of Columbia. The District's 16.2 m3/sec (370 mgd) Blue Plains Regional Wastewater Treatment Plant is the single, largest point source of nitrogen load to the Bay, discharging approximately 18 metric tons per day. In an effort toward meeting the nitrogen reduction goal, a post-denitrification demonstration study was recently begun to access its potential for long-term implementation. The denitrification demonstration project involves operating half of the nitrification facilities in a nitrification-denitrification mode using methanol as a carbon source for post-denitrification. The other half continues operation in a nitrification-only mode as a control. The post-denitrification process was selected for demonstration because it utilizes existing facilities and may offer substantial long-term cost savings. Objectives of the study are to demonstrate the process without a negative impact on effluent quality, to verify performance and capacity, to determine the stability and limitations of the project, and to compare the process to other nitrogen-removal technologies. Thus far, the process has been successful in removing nitrogen despite problems with phosphorus limitation and with the settling characteristics of the denitrification sludge. It is believed that insufficient phosphorus availability has been responsible for problems associated with settling, sludge yield, methanol use, and denitrification rates. Recently, phosphorus input to the denitrification process has been increased by reducing metal salt addition in upstream processes and preliminary results have been promising. If performance criteria are achieved without sacrificing plant capacity, the process will be continued at full scale.
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Zhang, Shoubin, Wei Sun, Wenhai Jiao, Liping Qiu, Jingxiu Zhong, and Yuze Li. "Research on System Optimizing of AAO-BAF Wastewater Treatment Process." E3S Web of Conferences 53 (2018): 04028. http://dx.doi.org/10.1051/e3sconf/20185304028.
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To meet the more strict discharging standard, some combined processes have emerged to realize denitrification and phosphorus removal of wastewater more efficiently. Among them, AAO-BAF combined process was an efficient one. The AAO-BAF system was composed of AAO reactor and BAF. The AAO process was the main unit to complete phosphorus removal and denitrification. The BAF process, external nitrification unit, was mainly used to provide enough electron acceptor for denitrifying bacteria in AAO reactor, which could enhance the efficiency of denitrification of the whole system. So the system optimizing was essential to AAO-BAF combined process. In this paper, the research progress of AAO-BAF wastewater treatment system was summarized and some system optimizing methods were raised too.
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Qiu, Gao Shun, Ling Feng Qiu, and Yi Ming Chen. "The Realization of Nitrification and Denitrification Processes in Low C/N Sewage." Advanced Materials Research 233-235 (May 2011): 600–603. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.600.
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The influences of HRT, C/N ratio on simultaneous nitrification and denitrification (SND) and the rule of pH in a sequencing batch reactor (SBR) were investigated while treating low C/N synthetic municipal wastewater. The results showed that the function of SND became more outstanding and the removal rate of TN, NH4+-N was improved greatly by lengthening HRT appropriately; when the C/N increased, the denitrification effect of the simultaneous nitrification and denitrification would be improved; .At the same time, the variation of pH value was well related to ammonia oxidation. So that judgment on the ending of nitrification and denitrification could be based on the inflection point on the varied curve of pH, and thus reducing aeration and mixing time for the purpose of energy saving.
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Puznava, N., M. Payraudeau, and D. Thornberg. "Simultaneous nitrification and denitrification in biofilters with real time aeration control." Water Science and Technology 43, no. 1 (January 1, 2001): 269–76. http://dx.doi.org/10.2166/wst.2001.0057.
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The aim of this article is to present a new biological aerated filter (BAF) for nitrogen removal based on simultaneous nitrification and denitrification. Contrary to the systems which integrate both an aerated and a non-aerated zone to allow complete nitrogen removal in one compact or two different units (pre-denitrification and nitrification), this upflow BAF system is based on the principle of simultaneous nitrification and denitrification since the filter is completely aerated. The denitrification process is possible due to the diffusion effect which dominates biofilm processes. The real time aeration control allows us to maintain a low dissolved oxygen value (0.5 to 3 mg O2/l). In this case, the biofilm will not be fully (or less) penetrated with oxygen and denitrification will be carried out in a large part of the biofilm. Therefore, nitrification and denitrification is running simultaneously in different depths of the biofilm. By using 50% less air this BAF gave the same results (less than 20mg TN/l) on pilot plant as a classical nitrification and denitrification BAF (Toettrup et al., 1994). Less recirculation was necessary to achieve the same denitrification.
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Wang, Rong Chang, Shu Peng Si, Dian Hai Yang, and Jian Fu Zhao. "Comparison of A2/O and Membrane Bioreactor Processes for Municipal Wastewater Treatment: Nutrient Removal Performance and Sludge Characteristics." Advanced Materials Research 356-360 (October 2011): 1647–54. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.1647.
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The performance of nitrogen and phosphorus removal was investigated in pilot-scale A2/O, A2/O-MBR and mA2/O-MBR processes for treating municipal wastewater. The results show that these processes had a similar COD and ammonia removal efficiency, but A2/O process had better denitrification efficiency than MBR processes. In order to explain the difference of nitrogen and phosphorus removal performance in the investigated processes, specific oxygen uptake rate (SOUR), specific denitrification rate (SDNR), anaerobic release rate and anoxic and aerobic uptake rate of the activated sludge taken from A2/O and mA2/O-MBR processes were compared. The results show that the activated sludge of mA2/O-MBR process had a higher nitrifying activity in aerobic tank than A2/O process, the denitrifying activity in anoxic tanks were roughly equal and A2/O process had a higher denitrifying phosphorus removal activity in anoxic tank than mA2/O-MBR process.
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Wentzel, M. C., G. A. Ekama, and G. v. R. Marais. "Processes and Modelling of Nitrification Denitrification Biological Excess Phosphorus Removal Systems – A Review." Water Science and Technology 25, no. 6 (March 1, 1992): 59–82. http://dx.doi.org/10.2166/wst.1992.0114.
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This paper reviews developments in modelling the kinetics of activated sludge systems: Completely aerobic nitrification, anoxic/aerobic nitrification denitrification (ND), and anaerobic/anoxic/aerobic nitrification denitrification biological excess phosphorus removal (NDBEPR) systems. The paper highlights the progress in developing a general NDBEPR activated sludge kinetic model – development of polyP organism enhanced cultures, their kinetics, simplification of the kinetics for enhanced cultures under constant flow and load conditions, extension of the simplified model to mixed culture NDBEPR systems under constant flow and load conditions, integration of the polyP organism enhanced culture kinetics with the ND kinetics to give a general NDBEPR kinetic model for cyclic flow and load which incorporates the increased specific denitrification rates observed in NDBEPR systems compared to ND systems. Areas of research that require attention to complete the development of the general NDBEPR kinetic model are identified – denitrification by polyP organisms, calibration and verification of the model for cyclic flow and load, etc.
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McMurray, S. H., R. L. Meyer, R. J. Zeng, Z. Yuan, and J. Keller. "Integration of titrimetric measurement, off-gas analysis and NOx− biosensors to investigate the complexity of denitrification processes." Water Science and Technology 50, no. 11 (December 1, 2004): 135–41. http://dx.doi.org/10.2166/wst.2004.0681.
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The denitrification process, namely the reduction of nitrate (NO3−) to nitrogen gas (N2), often cannot be simply modelled as a single step process. For a more complete and comprehensive model the intermediates, particularly nitrite (NO2−) and nitrous oxide (N2O), need to be investigated. This paper demonstrates the integration of titrimetric measurements and off-gas analysis with on-line nitrite plus nitrate (NOx−) biosensors, highlighting the necessity of measuring process intermediates with high time-scale resolution to study and understand the kinetics of denitrification. Investigation of activated sludge from a full-scale treatment plant showed a significant accumulation of NO2−, which appeared to impact on the overall denitrification rate measured as NOx− reduction or N2 production. A different sludge obtained from a lab-scale bioreactor produced N2O instead of N2 as the end product of denitrification. The two examples both illustrate the complexity of denitrification and stress the need for the more versatile and detailed measurement procedures, as presented in this paper.
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Dinçer, Ali R., and Fikret Kargı. "Kinetics of sequential nitrification and denitrification processes." Enzyme and Microbial Technology 27, no. 1-2 (July 2000): 37–42. http://dx.doi.org/10.1016/s0141-0229(00)00145-9.
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Hilliges, Rita, Eberhard Steinle, and Bernhard Böhm. "Case study on the implementation of deammonification for the process water treatment of Munich WWTPs." Water Science and Technology 65, no. 10 (May 1, 2012): 1895–902. http://dx.doi.org/10.2166/wst.2012.084.
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The two-staged WWTP ‘Gut Grosslappen’ has a capacity of 2 mio. PE. It comprises a pre-denitrification in the first stage using recirculation from the nitrifying second stage. A residual post-denitrification in a downstream sand filter is required in order to achieve the effluent standards. Presently the process water from sludge digestion is treated separately by nitrification/denitrification. Due to necessary reconstruction of the biological stages, the process water treatment was included in the future overall process concept of the WWTP. A case study was conducted comparing the processes nitritation/denitrititation and deammonification with nitrification/denitrification including their effect on the operational costs of the planned main flow treatment. Besides the different operating costs the investment costs required for the process water treatment played a significant role. Six cases for the process water treatment were compared. As a result, in Munich deammonification can only be recommended for long-term future developments, due to the high investment costs, compared with the nitritation/denitritation alternative realizable in existing tanks. The savings concerning aeration, sludge disposal and chemicals were not sufficient to compensate for the additional investment costs. Due to the specific circumstances in Munich, for the time being the use of existing tanks for nitritation/denitritation proved to be most economical.
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Mathioudakis, V. L., and A. Aivasidis. "Effect of temperature on anoxic sulfide oxidation and denitrification in the bulk wastewater phase of sewer networks." Water Science and Technology 59, no. 4 (February 1, 2009): 705–12. http://dx.doi.org/10.2166/wst.2009.017.
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Artificial dosage of nitrate in sewer networks is considered as one of the most effective methods for odor and corrosion control. However, there is limited knowledge on the effect of temperature on the transformations that takes place during anoxic conditions. Thus, two groups of batch experiments were conducted to gain insight in the involved processes in bulk phase of a septic municipal wastewater. It can be concluded that sewer denitrification, in bulk phase, can be simplified in three stages. According to the experimental results, nitrate or nitrite is utilized for autotrophic denitrification with sulfide, while heterotrophic utilization is initiated after the completion of anoxic sulfide oxidation. Moreover, temperature is proved to have a significant impact on sewer denitrification kinetic profile, as it determines the extent of temporal nitrite accumulation. The temperature coefficient of each anoxic process, including sulfide oxidation, nitrate utilization and denitrification/nitrite utilization is experimentally calculated and temperature dependent equations are developed, providing the rate of all anoxic processes in bulk phase of sewer wastewater, in any given temperature.
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He, Zhongwen, Hui Xu, Changlu Zhou, Zhong Xin, Jichang Liu, and Benxian Shen. "A kinetic model for in situ coking denitrification of heavy oil with high nitrogen content based on starch using a structure-oriented lumping method." RSC Advances 8, no. 57 (2018): 32707–18. http://dx.doi.org/10.1039/c8ra05561k.
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In this study, in situ coking denitrification technology was utilized to simplify the entire process by adding an appropriate quantity of denitrification agents to the delayed-coking tower without any further follow-up denitrification process.
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Du, Cong, Chong Wei Cui, Sheng Nan Shi, and Fang Ma. "Identification of a Highly Efficient Aerobic Denitrifying Bacterium in SBR and Denitrification Optimization." Advanced Materials Research 955-959 (June 2014): 376–82. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.376.
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Aerobic denitrification process is attracted more attention to enhance nitrogen removal technology. Aerobic denitrifying bacteria present excelled abilities with fast growth rate and denitrifying speed, though they are not dominant in most practical processes. A high-efficiency strain was enriched in SBR from aerobic activated sludge by the way of intermittent aeration and continuous aeration combination. The strain was determined toPseudomonasstutzeriT13 with ability of TN removal 90% and nitrate removal 97%. The limiting factors for aerobic denitrifying efficiency were optimized to temperature=31°C,pH=7.11 and DO=2.5 mg/L using response surface methodology. A total of 32 genes are related to nitrogen removal in strain T13. And 10 related to nitrate reductase, especially including 3 genes encoding the periplasmic nitrate reductase, playing important role to aerobic denitrification. It gave good understanding to supply effective technological supports for aerobic denitrification process.
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Kresovic, Mirjana, M. Jakovljevic, S. Blagojevic, and Branka Zarkovic. "Nitrogen transformation in acid soils subjected to pH value changes." Archives of Biological Sciences 62, no. 1 (2010): 129–36. http://dx.doi.org/10.2298/abs1001129k.
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The aim of this investigation was to determine which application of fertilizer and lime material does not form toxic quantities of nitrite nitrogen and when the losses by denitrification are the lowest in the examined acid soils. Investigations were performed on pseudogley soils of different acidity. Changes of available nitrogen forms were examined by the method of short-term incubation experiments. Experimental treatments were without the use of mineral fertilizers and with application of (NH4)2SO4 (100 ppm of NO3-N) and KNO3 (100 ppm of NO3-N); with and without addition of Ca(OH)2 (50% of full neutralization and full neutralization). When (NH4)2SO4 was used, nitrites occurred in both examined soils as a result of decelerated nitrification and when KNO3 was added as a result of chemical denitrification. Application of Ca(OH)2 caused the intensification of mineralization, nitrification and biological denitrification processes. When a higher dose of lime material was used (full neutralization), nitrites occurred in larger quantities as a result of the strengthening of nitrification and denitrification processes. Application of a lower lime dose caused nitrite occurrence in smaller quantities. Therefore, in these soils as well as in soils of similar chemical properties, application of lower doses of lime material can be recommended (<50% of full neutralization) as well as the application of ammonium fertilizer, bearing in mind that in such conditions losses of added fertilizer in the denitrification process are reduced and the occurrence of nitrites as an intermediate product of this process is prevented.
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Collivignarelli, C., and G. Bertanza. "Simultaneous Nitrification-Denitrification Processes in Activated Sludge Plants: Performance and Applicability." Water Science and Technology 40, no. 4-5 (August 1, 1999): 187–94. http://dx.doi.org/10.2166/wst.1999.0591.
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This paper deals with the development of technologies aimed to upgrade existing waste water treatment plants, paying attention to high process efficiencies and low costs. We established conditions for good N removal efficiencies in extended aeration activated sludge plants which are not equipped with specific denitrification steps. The experimental process is based on establishing conditions in the biological reactor which allow simultaneous nitrification and denitrification without alternating (in time or in space) anoxic and aerobic phases; the aeration system is controlled by means of dissolved oxygen and/or redox potential measurements. The research was carried out on two real plants (design size: 2,500 p.e. and 440,000 p.e. respectively). The main advantages of this process (even if some aspects are still under investigation) are: total N removal efficiencies similar to a pre-denitrification process, without the need for an anoxic basin and decrease of operating costs (savings in electric energy consumption in particular) due to the low oxygen concentration required in the biological reactor.
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Hao, Lin, and Jiafang Huang. "Effect of Aquaculture Reclamation on Sediment Nitrates Reduction Processes in Mangrove Wetland." Journal of Marine Science and Engineering 10, no. 7 (June 23, 2022): 857. http://dx.doi.org/10.3390/jmse10070857.
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Sediment denitrification, anaerobic ammonium oxidation (anammox), and nitrate dissimilation to ammonium (DNRA) play an important role in controlling the dynamics of nitrates (NOx−) and their fate in estuarine and coastal ecosystems. However, the effects of land-use change on NOx− reduction processes in mangrove sediments are still unclear. Here, we used a mud experiment method combined with a 15N stable isotope tracer method to study the mechanism and ecological environment of the change of land use pattern on the sediment NOx− reduction processes in mangrove wetlands. Our study showed that most physicochemical parameters, NOx− reduction rates, and their gene abundances varied considerably. The denitrification, anammox, and DNRA rates in mangrove sediment cores were in a range of 1.04–4.24 nmol g−1 h−1, 0.14–0.36 nmol g−1 h−1, and 0–2.72 nmol g−1 h−1, respectively. The denitrification, anammox, and DNRA rates in aquaculture sediment cores were in a range of 1.06–10.96 nmol g−1 h−1, 0.13–0.37 nmol g−1 h−1, and 0–1.96 nmol g−1 h−1, respectively. The highest values of denitrification, anammox, DNRA, the contribution of denitrification and DNRA to total NOx− reduction (DEN% and DNRA%), gene abundances (nirS, Amx 16S rRNA, and nrfA), total organic carbon (TOC), total nitrogen (TN), and TOC/TN in sediments were generally found in the top layer (0–5 cm) and then decreased with depth, while the contribution of anammox to total NOx− reduction (ANA%), Fe2+, and Fe2+/Fe3+ were generally increased with sediment depth in both mangrove and aquaculture ecosystems. When mangrove wetlands are transformed into pools, some properties (including TOC, TN, and Fe3+), DNRA rates, DRNA%, and nrfA gene abundances were decreased, while some properties (including NH4+, TOC/TN, Fe2+, and Fe2+/Fe3+), denitrification rates, DEN%, nirS, and ANAMMOX 16S gene abundances were increased. Sediment organic matter (TOC and TN) content and Fe2+ both affected NO3− reduction rates, with organic matter the most prominent factor. Thus, aquaculture reclamation enhances N loss while reducing N retention in sediments of mangrove wetlands, which plays an important role in regulating the source and fate of reactive N in mangrove ecosystems.
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Beliavski, M., I. Meerovich, S. Tarre, and M. Green. "Biological denitrification of brines from membrane treatment processes using an upflow sludge blanket (USB) reactor." Water Science and Technology 61, no. 4 (February 1, 2010): 911–17. http://dx.doi.org/10.2166/wst.2010.613.
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This paper investigates denitrification of brines originating from membrane treatment of groundwater in an upflow sludge blanket (USB) reactor, a biofilm reactor without carrier. A simulated brine wastewater was prepared from tap water and contained a nitrate concentration of 125 mg/l as N and a total salt concentration of about 1%. In order to select for a suitable energy source for denitrification, two electron donors were compared: one promoting precipitation of calcium compounds (ethanol), while the other (acetic acid), no precipitation was expected. After extended operation to reach steady state, the sludge from the two reactors showed very different mineral contents. The VSS/TSS ratio in the ethanol fed reactor was 0.2, i.e., 80% mineral content, while the VSS/TSS ratio in the acetic acid fed reactor was 0.9, i.e., 10% mineral content. In spite of the low mineral content, the sludge from the acetic acid fed reactor showed remarkably excellent granulation and settling characteristics. Although the denitrification performance of the acetic acid fed reactor was similar to that of the ethanol fed reactor, there was a huge difference in the sludge production due to mineral precipitation, with the corresponding negative aspects including increased costs of sludge treatment and disposal and moreover, instability and difficulties in reactor operation (channeling). These arguments make acetic acid a much more suitable candidate for brine denitrification, despite previous findings observed in groundwater denitrification regarding the essential role of a relatively high sludge mineral fraction for stable and effective USB reactor operation. Based on a comparison between two denitrification reactors with and without salt addition and using acetic acid as the electron donor, it was concluded that the reason for the excellent sludge settling characteristics found in the acetic acid fed reactor is the positive effects of higher salinity on granular sludge formation.
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Long, Andrew, Joshua Heitman, Craig Tobias, Rebecca Philips, and Bongkeun Song. "Co-Occurring Anammox, Denitrification, and Codenitrification in Agricultural Soils." Applied and Environmental Microbiology 79, no. 1 (October 19, 2012): 168–76. http://dx.doi.org/10.1128/aem.02520-12.
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ABSTRACTAnammox and denitrification mediated by bacteria are known to be the major microbial processes converting fixed N to N2gas in various ecosystems. Codenitrification and denitrification by fungi are additional pathways producing N2in soils. However, fungal codenitrification and denitrification have not been well investigated in agricultural soils. To evaluate bacterial and fungal processes contributing to N2production, molecular and15N isotope analyses were conducted with soil samples collected at six different agricultural fields in the United States. Denitrifying and anammox bacterial abundances were measured based on quantitative PCR (qPCR) of nitrous oxide reductase (nosZ) and hydrazine oxidase (hzo) genes, respectively, while the internal transcribed spacer (ITS) ofFusarium oxysporumwas quantified to estimate the abundance of codenitrifying and denitrifying fungi.15N tracer incubation experiments with15NO3−or15NH4+addition were conducted to measure the N2production rates from anammox, denitrification, and codenitrification. Soil incubation experiments with antibiotic treatments were also used to differentiate between fungal and bacterial N2production rates in soil samples. Denitrifying bacteria were found to be the most abundant, followed byF. oxysporumbased on the qPCR assays. The potential denitrification rates by bacteria and fungi ranged from 4.118 to 42.121 nmol N2-N g−1day−1, while the combined potential rates of anammox and codenitrification ranged from 2.796 to 147.711 nmol N2-N g−1day−1. Soil incubation experiments with antibiotics indicated that fungal codenitrification was the primary process contributing to N2production in the North Carolina soil. This study clearly demonstrates the importance of fungal processes in the agricultural N cycle.
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Liu, Hengyuan, and Chenhe Zhang. "Effect of current on biofilm-electrode reactor coupled with sulfur autotrophic denitrification process (BER-SAD) for nitrate removal from wastewater." E3S Web of Conferences 267 (2021): 02021. http://dx.doi.org/10.1051/e3sconf/202126702021.
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The biofilm-electrode reactor coupled with sulfur autotrophic denitrification process (BER-SAD) was used to remove nitrate in groundwater, and the effect of current intensity on the denitrification characteristics of the coupled process was explored. Current intensity had a great influence on the denitrification effect of the coupled process, the maximum nitrate removal efficiency of 99.9% and lowest nitrite production were gained under the optimum current density of 100 mA. Moreover, the accumulation concentration of SO42- increased gradually with the increase of current intensity. With the increase of current intensity, the proportion of hydrogen autotrophic denitrification decreased, while the proportion of sulfur autotrophic denitrification increased.
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Jasper, S. E., J. W. Atwater, and D. S. Mavinic. "Influent Constraints on Treatment and Biological Nitrification of Municipal Landfill Leachate." Water Quality Research Journal 20, no. 3 (August 1, 1985): 57–75. http://dx.doi.org/10.2166/wqrj.1985.028.
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Abstract A laboratory-scale treatment process was set up to treat Port Mann Landfill leachate, a high ammonia, low degradable carbon leachate with occasional high metals. A single sludge, nitrification/denitrification system was run for 25 weeks, with methanol added as a carbon source to improve denitrification. The objective of the treatment process was to remove biodegradable carbon and ammonia (feed levels of 25 to 250 mg/L). Carbon removal, including methanol, was adequate at SRT's of 10 days or greater. An SRT of 5 days produced inadequate treatment. Of the metals of concern, all except nickel were concentrated in the biomass. Ammonia removal was inconsistent. Good nitrification occurred at the start of the study but no denitrification occurred until operating conditions were optimized. Both processes deteriorated as the study progressed. The study clearly demonstrated that changing influent characteristics constrained the overall treatment of the leachate.
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Isaacs, S., Terry Mah, and S. K. Maneshin. "Automatic monitoring of denitrification rates and capacities in activated sludge processes using fluorescence or redox potential." Water Science and Technology 37, no. 12 (June 1, 1998): 121–29. http://dx.doi.org/10.2166/wst.1998.0519.
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A novel method is described to automatically estimate several key parameters affecting denitrification in activated sludge processes: the nitrate concentration, the denitrification capacity, and the maximum (substrate unlimited) and actual denitrification rates. From these, the concentration of active denitrifying microorganisms and the quality of available organic substrate pool can be estimated. Additionally, a modification of the method allows the determination of the efficacy of various carbon substrates to enhance denitrification, and this can be used to determine optimal dosing rates of an external carbon source. The method is based on measurements of either fluorescence or redox potential (ORP) in an isolated mini-reactor, the Biological Activity Meter (BAM), situated in the anoxic zone of the wastewater treatment plant. Advantages of the method are that it is in situ, operating at the same temperature as in the measured anoxic zone, requires no pumps or pipes for mixed liquor sampling, consumes little or no reagents, and uses measurement signals which are instantaneous and low maintenance, one of which provides a direct measure of biological activity.
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Teichgräber, Burkhard, and Andreas Stein. "Nitrogen elimination from sludge treatment reject water – comparison of the steam-stripping and denitrification processes." Water Science and Technology 30, no. 6 (September 1, 1994): 41–51. http://dx.doi.org/10.2166/wst.1994.0251.
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Steam stripping and nitrification/denitrification for the elimination of nitrogen from sludge treatment reject water from the Central Sludge Treatment Facilities (CSTF) of the Emschergenossenschaft in Bottrop were tested in half-scale pilot plants. More than 90% efficiency could be achieved with both systems; the nitrification/denitrification process also removed organic nitrogen. Operational experience has shown that full scale application of both systems is possible. The design surface load of the stripping column has been evaluated as 10 m3/(m2*h) and the steam/water ratio as 0.12 t/m3. The nitrification/denitrification process can be designed for 0.07 kgN/(kg MLSS*d) and 1.4 days hydraulic retention time. Total treatment costs are estimated to be between 5 and 7.5 DM/kg N.
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Thu, Vu Phuong. "COMBINATION OF METHANE OXIDATION AND DENITRIFICATION PROCESS IN A TWO-STAGE BIOREACTOR." Vietnam Journal of Science and Technology 54, no. 4B (March 22, 2018): 27. http://dx.doi.org/10.15625/2525-2518/54/4b/12020.
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The importance of a combination of methane oxidation and denitrification processes in a two-stage bioreactor was investigated for the removal of nitrate using methane gas. In the configuration I, methane and oxygen were supplied separately to two columns of the two-stage bioreactor, an oxic column and an anoxic column. The nitrate removal efficiency was around 25 % and nitrite presented in the liquid medium, showing that the denitrification process was not complete. In the configuration II, methane and oxygen were supplied together to one column of the two-stage bioreactor, better results were achieved. Nitrate removal efficiency increased to almost 100 %, no nitrite was found in the liquid medium. The methane oxidation and the denitrification processes seemed to be happened simultaneously in one column of the two-stage bioreactor and demonstrated its advantages. Methane utilized concentration in the medium of the methane oxidation column increased from 1 to 2.1 mg/L, which resulted in more soluble organic carbon was created and supplied for denitrifiers. The C/N utilized ratio was lower in the Configuration II showing that the aerobic methane oxidation coupled to denitrification (AMO-D) achieved higher efficiency when methane and oxygen were supplied together.
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Alyamani, Essam J., Rayan Y. Booq, Ali H. Bahkali, and Sulaiman A. Alharbi. "Effect of Denitrifying Bacterial Biomass and Carbon Sources on Nitrate Removal." Journal of Pure and Applied Microbiology 14, no. 4 (November 4, 2020): 2417–24. http://dx.doi.org/10.22207/jpam.14.4.19.
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Denitrification based on immobilized microbial cellulose may offer an economical replacement for conventional treatment for nitrate removal. The environmental and bacterial biomass may influence the rate of biological denitrification processes. This study aimed to investigate the factors that affect denitrification rates, including carbon sources, pH, and bacterial inoculum. Different inoculum biomass of Pseudomonas aeruginosa and various carbon sources of glucose, sucrose, and cellulose with different concentrations were tested to assimilate 100 mg/L of KNO3 as nitrate source. Additionally, five additional inoculations, five different incubation time, and seven different pH levels were studied. The Pseudomonas aeruginosa isolates used different mineral media with three carbon sources, glucose, sucrose, and cellulose, with different concentrations at different rates to denitrify nitrate. The highest denitrification rate was with glucose after 18 hrs and was after 24 hrs when sucrose and cellulose were used, respectively. The bacterial biomass denitrification level was the highest, between 0.8% and 1% of OD600=1. Nitrate removal by Pseudomonas aeruginosa was the highest at pH 7, 8, and 9. This report suggests that when glucose is used as a carbon source, at neutral to alkaline pH, and 1% of denitrifying bacterial biomass, the highest level of biological denitrification process may be achieved.
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Henze, Mogens, Gert Holm Kristensen, and Rune Strube. "Rate-Capacity Characterization of Wastewater for Nutrient Removal Processes." Water Science and Technology 29, no. 7 (April 1, 1994): 101–7. http://dx.doi.org/10.2166/wst.1994.0318.
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The detailed composition of wastewater has significant impact on the biological wastewater treatment processes. The carbon sources present govern the oxygen uptake rate, the rate of denitrification and the biological phosphorus uptake rate. In this paper, the respiration rate determinations used for the bi- or tri-substrate determinations are coupled to removal capacity in order to develop rate-capacity diagrams, that gives a fuller picture of the wastewater and its influence on the biological processes. The directly degradable carbon source gives high reaction rates, but the concentration and thus the capacity can be very limited. In such a case the overall obtainable removal rate is of more interest than the peak rate. The rate-capacity diagrams are shown for raw, primary settled and primary precipitated wastewater, characterized by detailed investigations of the respiration rates obtainable. It shows the effect of pretreatment not only on the total concentrations in the pre-treated wastewater, but also in the rate-capacity curves for biological denitrification. The rate-capacity curves are in practice coupled to the design and operation of the treatment plant. These two factors determine whether the carbon sources in the influent wastewater are used for denitrification (or biological phosphorus removal), for oxidation with oxygen or for sludge production.
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Wild, D., R. von Schulthess, and W. Gujer. "Synthesis of denitrification enzymes in activated sludge: modelling with structured biomass." Water Science and Technology 30, no. 6 (September 1, 1994): 113–22. http://dx.doi.org/10.2166/wst.1994.0258.
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Three mechanisms are responsible for microbiological elimination processes in activated sludge: the survival of qualified organisms in the ecological selection process, the expression of specific enzymes and the absence of inhibitors limiting enzyme activity. A mathematical model with structured biomass has been formulated to improve the description of data from denitrification experiments. The model includes synthesis and decay of denitrification enzymes and is able to predict nitrate, nitrite and N2O concentrations. Kinetic parameters have been estimated and used to simulate the effect of cell saturation with enzymes in a waste water treatment process. Low dissolved oxygen concentrations in the anoxic reactor reduce the denitrification efficiency equally by inhibiting enzyme activity and enzyme synthesis: at 0.5 gm−3 O2 enzyme decay causes a cell saturation of below 40 %. Enzyme synthesis can take place in the sludge blanket of a secondary sedimentation tank and improve denitrification efficiency. The benefit of modelling with structured biomass is shown. The comprehension of experimental observations has been improved, and plant design and operation can be optimized. However, the multitude of unknown parameters still may restrict the validity of complex models.
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Adouani, Nouceiba, Lionel Limousy, Thomas Lendormi, Eberhard O. Voit, and Olivier Sire. "Simulation of the Denitrification Process of Waste Water with a Biochemical Systems Model: A Non-Conventional Approach." International Journal of Chemical Reactor Engineering 12, no. 2 (December 1, 2014): 683–93. http://dx.doi.org/10.1515/ijcre-2014-0050.
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Abstract Matching experimental and theoretical approaches have often been fruitful in the investigation of complex biological processes. Here we develop a novel non-conventional model for the denitrification of waste water. Earlier models of the denitrification process were compiled by the International Association on Water Quality group. The Activated Sludge Models 1–3, which are the most frequently used all over the world, are presently not adapted towards the integration of both nitrous and nitric oxide emissions during the denitrification process. In the present work, a Generalized Mass Action model, based on Biochemical Systems Theory, was designed to simulate the nitrate reduction observed in specific experimental conditions. The model was implemented and analysed with the software package PLAS. Data from a representative experiment were chosen (T=10°C, pH=7, C/N=3, with acetate as carbon source) to simulate greenhouse NO and N2O gas emissions, in order to test hypotheses about the corresponding bacterial metabolic pathways. The results show that the reduction of nitrate and nitrite is kinetically limiting and that nitrate reduction is limited by diffusion and support that distinct microbial subpopulations are involved in the denitrification pathway, which has consequences for NO emissions.
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Liu, Fu Jun, and Fan Yang. "Pulsed SBR Treatment of Municipal Sewage Denitrification and Experimental Research." Advanced Materials Research 779-780 (September 2013): 1500–1504. http://dx.doi.org/10.4028/www.scientific.net/amr.779-780.1500.
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Pulsed SBR process is a new type of SBR operation mode proposed against the traditional SBR process with poorer denitrification effect. This experiment is carried out at laboratory of sewage treatment, Beijing University of Technology, using real sewage for study, to study denitrification efficiency of pulsed SBR in nitration add raw water - denitrification this repeated and cycled process (with the same amount of water). The experimental results show that the effluent TN is less than 2 mg/L, removal efficiency is more than 96%.Keywords: pulsed SBR; domestic sewage; denitrification; experimental study
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Campos, José Luis, Jacques Dumais, Juan Pablo Pavissich, Oscar Franchi, Dafne Crutchik, Marisol Belmonte, Martín Faúndez, et al. "Predicting Accumulation of Intermediate Compounds in Nitrification and Autotrophic Denitrification Processes: A Chemical Approach." BioMed Research International 2019 (July 7, 2019): 1–9. http://dx.doi.org/10.1155/2019/2051986.
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Nitrification and sulfur-based autotrophic denitrification processes can be used to remove ammonia from wastewater in an economical way. However, under certain operational conditions, these processes accumulate intermediate compounds, such as elemental sulphur, nitrite, and nitrous oxide, that are noxious for the environment. In order to predict the generation of these compounds, an analysis based on the Gibbs free energy of the possible reactions and on the oxidative capacity of the bulk liquid was done on case study systems. Results indicate that the Gibbs free energy is not a useful parameter to predict the generation of intermediate products in nitrification and autotrophic denitrification processes. Nevertheless, we show that the specific productions of nitrous oxide during nitrification, and of elemental sulphur and nitrite during autotrophic denitrification, are well related to the oxidative capacity of the bulk liquid.
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Liu, Feng, Suqin Wang, Xuezhi Zhang, Feiyue Qian, Yaobing Wang, and Yao Yin. "Nitrate Removal from Actual Wastewater by Coupling Sulfur-Based Autotrophic and Heterotrophic Denitrification under Different Influent Concentrations." Water 13, no. 20 (October 16, 2021): 2913. http://dx.doi.org/10.3390/w13202913.
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Contamination of wastewater with organic-limited nitrates has become an urgent problem in wastewater treatment. The cooperating heterotrophic with sulfur autotrophic denitrification is an alternative process and the efficiency has been assessed in many studies treating simulated wastewater under different operating conditions. However, due to the complex and diverse nature of actual wastewater, more studies treating actual wastewater are still needed to evaluate the feasibility of collaborative denitrification. In this study, lab-scale experiments were performed with actual nitrate polluted water of two different concentrations, with glucose and sodium thiosulfate introduced as mixed electron donors in the coupling sulfur-based autotrophic and heterotrophic denitrification. Results showed that the optimum denitrification performance was exhibited when the influent substrate mass ratio of C/N/S was 1.3/1/1.9, with a maximum denitrification rate of 3.52 kg NO3−-N/(m3 day) and nitrate removal efficiency of 93% in the coupled systems. Illumina high-throughput sequencing analysis revealed that autotrophic, facultative, and heterotrophic bacteria jointly contributed to high nitrogen removal efficiency. The autotrophic denitrification maintained as the predominant process, while the second most prevalent denitrification process gradually changed from heterotrophic to facultative with the increase of influent concentration at optimum C/N/S ratio conditions. Furthermore, the initiation of dissimilatory nitrate reduction to ammonium (DNRA) was very pivotal in promoting the entire denitrification process. These results suggested that sulfur-based autotrophic coupled with heterotrophic denitrifying process is an alternative and promising method to treat nitrate containing wastewater.
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Abdul-Talib, S., T. Hvitved-Jacobsen, J. Vollertsen, and Z. Ujang. "Anoxic transformations of wastewater organic matter in sewers – process kinetics, model concept and wastewater treatment potential." Water Science and Technology 45, no. 3 (February 1, 2002): 53–60. http://dx.doi.org/10.2166/wst.2002.0053.
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The sewer is an integral part of the urban wastewater system: the sewer, the wastewater treatment plant and the local receiving waters. The sewer is a reactor for microbial changes of the wastewater during transport, affecting the quality of the wastewater and thereby the successive treatment processes or receiving water impacts during combined sewer overflows. This paper presents the results of studies on anoxic processes, namely denitrification, in the bulk water phase of wastewater as it occurs in sewers. Experiments conducted on 12 different wastewater samples have shown that the denitrification process in the bulk wastewater can be simplified by the reduction of nitrate to nitrogen with significant accumulation of nitrite in the water phase. Utilization of nitrate was observed not to be limited by nitrate for concentrations above 5 gNO3-N/m3. The denitrification rates, under conditions of excess substrate and electron acceptor, were found to be in the range of 0.8-2.0 g NO3-N/(m3h). A discussion on the interaction of the sewer processes and the effects on a downstream located wastewater treatment plant (WWTP) is provided.
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Medici, C., S. Bernal, A. Butturini, F. Sabater, A. J. Wade, and F. Frances. "Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)." Hydrology and Earth System Sciences Discussions 6, no. 5 (September 4, 2009): 5665–703. http://dx.doi.org/10.5194/hessd-6-5665-2009.
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Abstract. The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.
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Medici, C., S. Bernal, A. Butturini, F. Sabater, M. Martin, A. J. Wade, and F. Frances. "Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)." Hydrology and Earth System Sciences 14, no. 2 (February 8, 2010): 223–37. http://dx.doi.org/10.5194/hess-14-223-2010.
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Abstract. The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.
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Verstraete, W., and S. Philips. "Nitrification-denitrification processes and technologies in new contexts." Environmental Pollution 102, no. 1 (1998): 717–26. http://dx.doi.org/10.1016/s0269-7491(98)80104-8.
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