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Nitrous Oxide Emissions From Wastewater Treatment
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Book Synopsis Aerobic Granular Sludge by : S. Bathe
Download or read book Aerobic Granular Sludge written by S. Bathe and published by IWA Publishing. This book was released on 2005-03-31 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerobic Granular Sludge has recently received growing attention by researchers and technology developers, worldwide. Laboratory studies and preliminary field tests led to the conclusion that granular activated sludge can be readily established and profitably used in activated sludge plants, provided 'correct' process conditions are chosen. But what makes process conditions 'correct'? And what makes granules different from activated sludge flocs? Answers to these question are offered in Aerobic Granular Sludge. Major topics covered in this book include: Reasons and mechanism of aerobic granule formation Structure of the microbial population of aerobic granules Role, composition and physical properties of EPS Diffuse limitation and microbial activity within granules Physio-chemical characteristics Operation and application of granule reactors Scale-up aspects of granular sludge reactors, and case studies Aerobic Granular Sludge provides up-to-date information about a rapidly emerging new technology of biological treatment.
Author :The IWA Task Group on Mathematical Modelling for Design and Operation of Biological Wastewater Treatment Publisher :IWA Publishing ISBN 13 :9781900222242 Total Pages :132 pages Book Rating :4.2/5 (222 download)
Book Synopsis Activated Sludge Models by : The IWA Task Group on Mathematical Modelling for Design and Operation of Biological Wastewater Treatment
Download or read book Activated Sludge Models written by The IWA Task Group on Mathematical Modelling for Design and Operation of Biological Wastewater Treatment and published by IWA Publishing. This book was released on 2000-05-31 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book has been produced to give a total overview of the Activated Sludge Model (ASM) family at the start of 2000 and to give the reader easy access to the different models in their original versions. It thus presents ASM1, ASM2, ASM2d and ASM3 together for the first time. Modelling of activated sludge processes has become a common part of the design and operation of wastewater treatment plants. Today models are being used in design, control, teaching and research. Contents ASM3: Introduction, Comparison of ASM1 and ASM3, ASM3: Definition of compounds in the model, ASM3: Definition of processes in the Model, ASM3: Stoichiometry, ASM3: Kinetics, Limitations of ASM3, Aspects of application of ASM3, ASM3C: A Carbon based model, Conclusion ASM 2d: Introduction, Conceptual Approach, ASM 2d, Typical Wastewater Characteristics and Kinetic and Stoichiometric Constants, Limitations, Conclusion ASM 2: Introduction, ASM 2, Typical Wastewater Characteristics and Kinetic and Stoichiometric Constants, Wastewater Characterization for Activated Sludge Processes, Calibration of the ASM 2, Model Limitations, Conclusion, Bibliography ASM 1: Introduction, Method of Model Presentation, Model Incorporating Carbon Oxidation Nitrification and Denitrification, Characterization of Wastewater and Estimation of Parameter Values, Typical Parameter Ranges, Default Values, and Effects of Environmental Factors, Assumptions, Restrictions and Constraints, Implementation of the Activated Sludge Model Scientific and Technical Report No.9
Book Synopsis N2O and CH4 Emission from Wastewater Collection and Treatment Systems by : Jeff Foley
Download or read book N2O and CH4 Emission from Wastewater Collection and Treatment Systems written by Jeff Foley and published by IWA Publishing. This book was released on 2015-05-15 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a world where there is a growing awareness of the possible effects of human activities on climate change, there is a need to identify the emission of greenhouse gases (GHG) from wastewater treatment plants (WWTPs). As a result of this growing awareness, governments started to implement regulations that require water authorities to report their GHG emissions. With these developments there exists a strong need for adequate insight into the emissions of N2O and CH4. With this insight water authorities would be able to estimate and finally reduce their emissions. The overall objectives of the different research programs performed by partners of the GWRC members WERF (United States of America), WSAA (Australia), CIRSEE-Suez (France) and STOWA (the Netherlands) were: To define the origin of N2O emission. To understand the formation processes of N2O. To identify the level of CH4 emissions from wastewater collection and treatment systems. To evaluate the use of generic emission factors to estimate the emission of N2O from individual plants
Book Synopsis Nitrous Oxide Emissions from Wastewater Treatment Processes and Process Parameters Affecting Emissions by : Shannon Kusaka Cavanaugh
Download or read book Nitrous Oxide Emissions from Wastewater Treatment Processes and Process Parameters Affecting Emissions written by Shannon Kusaka Cavanaugh and published by . This book was released on 2021 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most wastewater treatment plants in the United States must be upgraded to reduce nutrient discharges. These improvements are needed to meet upcoming permit requirements and to prevent negative environmental impacts like eutrophication of receiving water bodies. However, one of the potential side-effects of increased nitrogen removal in wastewater treatment processes is increased nitrous oxide (N2O) emissions from biological nitrification and denitrification. N2O is a greenhouse gas (GHG) approximately 300 times stronger than an equivalent amount of CO2; thus, it is imperative to (1) establish comprehensive methodologies to accurately quantify N2O emissions from full-scale treatment processes and (2) understand the relevant process parameters and microbiology involved in emissions from wastewater treatment. This serves to ultimately minimize emissions (and therefore the carbon footprint) of wastewater treatment plants (WWTPs). To address this, emissions from two wastewater treatment processes were quantified, and relevant process parameters and microbial emission pathways were investigated. While the two treatment systems differ in terms of scale and processes utilized, both are innovative wastewater treatment technologies designed for efficient use of space and nutrient removal. (1) At Brightwater Treatment Plant (Woodinville, WA), aqueous and gaseous N2O monitoring techniques were employed at a full-scale membrane bioreactor (MBR) for 5.5 months. To the knowledge of the investigators, this campaign was the most comprehensive study of a fully covered MBR to date. Emission estimates from both aqueous and gaseous analyzers were compared to determine their reliability, and the average emission factor (using data from both analyzers) was 0.58% of plant influent total Kjeldahl nitrogen (TKN) emitted as N2O-N. Emissions were positively correlated with influent pH, nitrification efficiency, and aeration basin/effluent NH4+and NO3−. They correlated negatively with primary effluent COD:N ratio and effluent pH, signifying that nitrification was likely the dominant N2O-production pathway. (2) A laboratory-scale, aerobic granular sludge (AGS) sequencing batch reactor (SBR) was operated for 11 months to measure N2O emissions with full phosphate removal and simultaneous nitrification-denitrification (SND). The reactor was operated at varying dissolved oxygen (DO) concentrations and with nitrite (NO2−) spikes to investigate the impact of these process parameters on emissions. Increased DO and NO2- concentrations were associated with increased emissions. N2O was minimized at a dissolved oxygen concentration of 1 mg O2 L−1, with an emission factor of 0.18% of oxidized NH3-N emitted as N2O-N. This emission factor is lower than many previously reported factors from AGS reactors. Molecular analyses revealed a population of microbes capable of shortcut nitrogen removal, which is advantageous for wastewater treatment because of decreased oxygen and carbon requirements.
Book Synopsis Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants by : Xinmin Zhan
Download or read book Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants written by Xinmin Zhan and published by IWA Publishing. This book was released on 2018-01-15 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wide adoption of wastewater treatment processes and use of novel technologies for improvement of nitrogen and phosphorus removals from wastewater have been introduced to meet stringent discharge standards. Municipal wastewater treatment plants (MWWTPs) are one of major contributors to the increase in the global GHG emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarizes the recent development in studies of greenhouse gas emissions (N2O, CH4 and CO2) in MWWTPs. It also summarizes the development in life cycle assessment on GHG emissions in consideration of the energy usage in MWWTPs. The strategies in mitigating GHG emissions are discussed and the book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in MWWTPS and industrial wastewater treatment processes. The book is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas of research. It is also a useful reference source for water professionals, government policy makers, and research institutes.
Book Synopsis Real Time Monitoring of Nitrous Oxide Emissions from Wastewater Treatment Processes by Membrane Introduction Mass Spectrometry by : Alexander Sandy Thompson
Download or read book Real Time Monitoring of Nitrous Oxide Emissions from Wastewater Treatment Processes by Membrane Introduction Mass Spectrometry written by Alexander Sandy Thompson and published by . This book was released on 2010 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project investigated membrane introduction mass spectrometry (MIMS) as a real time (on-line) analytical monitoring technique for nitrous oxide gas emissions from processes within a full-scale biological nutrient removal wastewater treatment plant. Experiments have shown that treatment processes including nitrification (aerobic - ammonia to nitrate) and denitrification (anoxic - nitrate to nitrogen gas) can become disrupted resulting in unintended nitrous oxide emissions (N2O). A limited number of studies have been conducted that monitor real time N2O emissions from full-scale treatment bioreactors and there remains significant uncertainty in true emissions. Two real time monitoring experiments (22 hours each) are shown where MIMS was able to track nitrous oxide emissions from the aerobic and anoxic zones of the bioreactor. Concentrations were calculated from response factors obtained using internal standard. Estimated quantities of nitrous oxide emissions under various scenarios and recommendations for future investigations are also provided.
Book Synopsis Nitrous Oxide Emissions from Wastewater Treatment by : Joon Ho Ahn
Download or read book Nitrous Oxide Emissions from Wastewater Treatment written by Joon Ho Ahn and published by . This book was released on 2010 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Verifying Greenhouse Gas Emissions by : National Research Council
Download or read book Verifying Greenhouse Gas Emissions written by National Research Council and published by National Academies Press. This book was released on 2010-07-28 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The world's nations are moving toward agreements that will bind us together in an effort to limit future greenhouse gas emissions. With such agreements will come the need for all nations to make accurate estimates of greenhouse gas emissions and to monitor changes over time. In this context, the present book focuses on the greenhouse gases that result from human activities, have long lifetimes in the atmosphere and thus will change global climate for decades to millennia or more, and are currently included in international agreements. The book devotes considerably more space to CO2 than to the other gases because CO2 is the largest single contributor to global climate change and is thus the focus of many mitigation efforts. Only data in the public domain were considered because public access and transparency are necessary to build trust in a climate treaty. The book concludes that each country could estimate fossil-fuel CO2 emissions accurately enough to support monitoring of a climate treaty. However, current methods are not sufficiently accurate to check these self-reported estimates against independent data or to estimate other greenhouse gas emissions. Strategic investments would, within 5 years, improve reporting of emissions by countries and yield a useful capability for independent verification of greenhouse gas emissions reported by countries.
Book Synopsis Wastewater Engineering by : Metcalf & Eddy Inc
Download or read book Wastewater Engineering written by Metcalf & Eddy Inc and published by . This book was released on 2013-06-01 with total page 1856 pages. Available in PDF, EPUB and Kindle. Book excerpt: This update of a popular book for civil and environmental engineering majors describes the technological and regulatory changes that have occurred over the last ten years in the discipline.
Book Synopsis Nitrous Oxide Emissions from Wastewater Treatment Systems by : John Michael Russell
Download or read book Nitrous Oxide Emissions from Wastewater Treatment Systems written by John Michael Russell and published by . This book was released on 1991 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants by : Xinmin Zhan
Download or read book Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants written by Xinmin Zhan and published by IWA Publishing. This book was released on 2018-01-15 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The wide adoption of wastewater treatment processes and use of novel technologies for improvement of nitrogen and phosphorus removals from wastewater have been introduced to meet stringent discharge standards. Municipal wastewater treatment plants (MWWTPs) are one of major contributors to the increase in the global GHG emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarizes the recent development in studies of greenhouse gas emissions (N2O, CH4 and CO2) in MWWTPs. It also summarizes the development in life cycle assessment on GHG emissions in consideration of the energy usage in MWWTPs. The strategies in mitigating GHG emissions are discussed and the book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in MWWTPS and industrial wastewater treatment processes. The book is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas of research. It is also a useful reference source for water professionals, government policy makers, and research institutes.
Book Synopsis Greenhouse Gas Emissions from Ecotechnologies for Wastewater Treatment by : Juan Pablo Silva Vinasco
Download or read book Greenhouse Gas Emissions from Ecotechnologies for Wastewater Treatment written by Juan Pablo Silva Vinasco and published by CRC Press. This book was released on 2021-02-25 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ecotechnologies for wastewater treatment (EWWT) have been used as a cost-effective alternative to conventional wastewater treatment methods for improving the removal of organic carbon, nutrients and pathogenic microorganisms from wastewater. However, due to biochemical transformations of organic matter and nutrients EWWT are net sources of CO2, CH4 and N2O greenhouse gases (GHGs), which may be transferred into the atmosphere contributing to global warming. Greenhouse Gas Emissions from Ecotechnologies for Wastewater Treatment provides scientific information about greenhouse gas, such as CO2, CH4 and N2O, generation and emissions from different municipal EWWT. The main EWWT considered in this book are anaerobic ponds, facultative ponds, duckweed-based ponds, and a freshwater natural wetland perturbed by anthropogenic activities such as wastewater discharge and nutrients from agricultural run-off. The book includes a full literature review of recent publications about GHGs emissions from EWWT. It also introduces the calculation of GHGs flux using a static chamber technique. Besides, the book presents information on the influence of environmental factors such as temperature, pH, DO, and nutrients on GHG emissions produced in EWWT under tropical conditions. This book will be a useful reference for researches and students interested in the broader area of water and climate change subjects. The publication may also be of interest to policy makers concerned with climate change, water sector planning, and wastewater treatment.
Book Synopsis Efficient Processing of Deep Neural Networks by : Vivienne Sze
Download or read book Efficient Processing of Deep Neural Networks written by Vivienne Sze and published by Springer Nature. This book was released on 2022-05-31 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a structured treatment of the key principles and techniques for enabling efficient processing of deep neural networks (DNNs). DNNs are currently widely used for many artificial intelligence (AI) applications, including computer vision, speech recognition, and robotics. While DNNs deliver state-of-the-art accuracy on many AI tasks, it comes at the cost of high computational complexity. Therefore, techniques that enable efficient processing of deep neural networks to improve key metrics—such as energy-efficiency, throughput, and latency—without sacrificing accuracy or increasing hardware costs are critical to enabling the wide deployment of DNNs in AI systems. The book includes background on DNN processing; a description and taxonomy of hardware architectural approaches for designing DNN accelerators; key metrics for evaluating and comparing different designs; features of DNN processing that are amenable to hardware/algorithm co-design to improve energy efficiency and throughput; and opportunities for applying new technologies. Readers will find a structured introduction to the field as well as formalization and organization of key concepts from contemporary work that provide insights that may spark new ideas.
Book Synopsis N2O and CH4 Emission from Wastewater Collection and Treatment Systems by : Zhiguo Yuan
Download or read book N2O and CH4 Emission from Wastewater Collection and Treatment Systems written by Zhiguo Yuan and published by . This book was released on 2015-05-15 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a world where there is a growing awareness of the possible effects of human activities on climate change, there is a need to identify the emission of greenhouse gases (GHG) from wastewater treatment plants (WWTPs). As a result of this growing awareness, governments started to implement regulations that require water authorities to report their GHG emissions. With these developments there exists a strong need for adequate insight into the emissions of N2O and CH4. With this insight water authorities would be able to estimate and finally reduce their emissions. The overall objectives of the different research programs performed by partners of the GWRC members WERF (United States of America), WSAA (Australia), CIRSEE-Suez (France) and STOWA (the Netherlands) were: To define the origin of N2O emission. To understand the formation processes of N2O. To identify the level of CH4 emissions from wastewater collection and treatment systems. To evaluate the use of generic emission factors to estimate the emission of N2O from individual plants
Book Synopsis Frontiers in Wastewater Treatment and Modelling by : Giorgio Mannina
Download or read book Frontiers in Wastewater Treatment and Modelling written by Giorgio Mannina and published by Springer. This book was released on 2017-05-04 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the latest research advances, innovations, and applications in the field of water management and environmental engineering as presented by leading researchers, engineers, life scientists and practitioners from around the world at the Frontiers International Conference on Wastewater Treatment (FICWTM), held in Palermo, Italy in May 2017. The topics covered are highly diverse and include the physical processes of mixing and dispersion, biological developments and mathematical modeling, such as computational fluid dynamics in wastewater, MBBR and hybrid systems, membrane bioreactors, anaerobic digestion, reduction of greenhouse gases from wastewater treatment plants, and energy optimization. The contributions amply demonstrate that the application of cost-effective technologies for waste treatment and control is urgently needed so as to implement appropriate regulatory measures that ensure pollution prevention and remediation, safeguard public health, and preserve the environment. The contributions were selected by means of a rigorous peer-review process and highlight many exciting ideas that will spur novel research directions and foster multidisciplinary collaboration among different water specialists.
Book Synopsis The Carbon Footprint Analysis of Wastewater Treatment Plants and Nitrous Oxide Emissions from Full-scale Biological Nitrogen Removal Processes in Spain by : Xin Xu (S.M.)
Download or read book The Carbon Footprint Analysis of Wastewater Treatment Plants and Nitrous Oxide Emissions from Full-scale Biological Nitrogen Removal Processes in Spain written by Xin Xu (S.M.) and published by . This book was released on 2013 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a general model for the carbon footprint analysis of advanced wastewater treatment plants (WWTPs) with biological nitrogen removal processes, using a life cycle assessment (LCA) approach. Literature on greenhouse gas (GHG) emissions and LCA are reviewed and the methodology employed in the analysis is discussed. Two selected WWTPs in Madrid, Spain, i.e. La Gavia and Boadilla, are analyzed and the carbon footprints are calculated, using GaBi software by PE-international. In quantifying the N2O emissions from the biological nitrogen removal processes in the WWTPs, huge uncertainty on N2O emission factor is identified and thus a comprehensive study on N2O generation and emission is conducted. Different measurement strategies are investigated and an on-site aqueous N2O measurement is carried out at Boadilla WWTP. Estimation of N2O emission from the plant is given and compared with other calculation results. Recommendations on future measurement campaign are provided at last. The final results have shown that a big portion of the carbon footprints from the WWTPs is from the indirect emissions of CO2, which is caused by the intensive energy consumption. However, the emissions resulting from the N20 in biological nitrogen removal processes cannot be ignored. Depending on different estimation methodologies, and the operational conditions that affect the N2O production, the N2O emission can range from 17% to 38% of the total carbon footprint of the WWTP.
Book Synopsis The Link Between Denitrifying Ecology, Environmental Conditions, and Nitrous Oxide Production in Wastewater Treatment by : Cody Mankelow
Download or read book The Link Between Denitrifying Ecology, Environmental Conditions, and Nitrous Oxide Production in Wastewater Treatment written by Cody Mankelow and published by . This book was released on 2018 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrous oxide (N2O) is a potent greenhouse gas and ozone-depleting compound known to be emitted from wastewater treatment. Emissions of N2O results from the activity of the microorganisms employed in the transformation of reactive nitrogen species (NOx). N2O emissions from wastewater treatment are currently underestimated by United Nations (UN) and the United States (US) Environmental Protection Agency (EPA) guidelines, and treatment plants show differing rates of N2O emissions. Improving our understanding of the mechanisms that drive N2O production and subsequent emissions are essential for its mitigation. N2O is produced by a variety of microbial metabolic pathways; this thesis primarily focuses on N2O production via the denitrification pathway. Denitrification, conducted by heterotrophic bacteria is the Dissimilatory reduction of nitrogen oxides such as nitrate (NO3-) or nitrite (NO2-) to di-nitrogen gas (N2), using carbon as electron donors. The process occurs in a cascade reducing NO3-, to NO2-, nitric oxide (NO), N2O and finally N2. This process is catalyzed by several enzymes including, nitrate reductase (Nar, and Nap), nitrite reductase (Nir) nitric oxide reductase (Nor) and nitrous oxide reductase (NosZ). Denitrification is a widespread trait, and the pathway is encoded by a variety of genes, which produce functionally equivalent enzymes but form differing denitrifying phylogenies. For example, nitrite reductase is encoded by nirS and nirK the genes for the cytochrome-cd1 and copper-based dissimilatory nitrite reductases, respectively, while nitrous oxide reductase is encoded by either the truncated or non-truncated gene nosZII or nosZI respectively. It has been proposed that differences in the microbial population may explain the difference in N2O emission observed between treatment plants. This hypothesis is supported by the recent discovery of non-denitrifying N2O reducing organisms encoded by the gene nosZII. These organisms lack the preceding enzymes of the denitrifying pathway but retain the ability to reduce N2O, they have a high abundance in soils, and nosZII abundance shows a strong correlation with reduced N2O emissions. The understanding of denitrifying microbial ecology and its role in the production of N2O from wastewater treatment is currently limited. The primary aim of this thesis is to address the hypothesis: Denitrifying ecology determines the magnitude and rate of N2O accumulation in Wastewater treatment plant (WWTP) sludge. To address this hypothesis, a stepwise approach has been taken. 1) A survey of the microbial ecology of three New Zealand (NZ) WWTPs was conducted to determine denitrifying ecology by the distribution of denitrifying functional markers (nirS, nirK, nosZI, and nosZII) within each population. The following hypotheses were tested, a) denitrifying populations will differ between WWTPs, and b) Wastewater is a disadvantageous environment for non-denitrifying organisms (nosZII), and they will be under-represented. 2) Using the sludges from the surveyed WWTPs, sludge metabolism was examined under ideal denitrifying conditions for differences in NOx profiles including N2O accumulation. Accumulation of NOx intermediaries was correlated with the relative abundance of denitrifying functional markers, testing the hypotheses c) differing denitrifying populations accumulate different amounts of N2O, and d) N2O accumulation will correlate with non-denitrifying organism abundance. 3) As wastewater treatment plants are not stable environments and can suffer from process perturbations, sludges with now known populations, and NOx profiles under control conditions, were exposed to environmental shocks (pH and nitrite (NO2-). Testing the hypothesis: e) Within a specific range of environmental shock, denitrifying population structure will determine N2O accumulation. Survey of NZ microbial populations supports the hypotheses, showing differing total microbial and denitrifying populations, with low abundance of non-denitrifying N2O reducing organisms(nosZII). Analysis of the relative abundance of denitrifying functional markers suggests NZ WWTPs have a genetic predisposition to N2O emissions. Additional findings include the identification of co-occurring nirK and nirS in the same organisms in each treatment plant and the observation that NZ treatment plants show the opposite trend to most of the literature reports with a markedly dominant nirK over nirS population. Examination of the NOx profiles of the three sludges under ideal denitrifying conditions supports the hypotheses showing differing N2O accumulation in each sludge and increasing abundance of nosZII correlating with a decrease in the maximum N2O concentration. All sludges acclimatized to laboratory conditions quickly accumulating minimal N2O after just four sequence batch cycles. Analysis of changes in the rate of NO3- reduction and the Max N2O accumulation suggests that under stable conditions N2O accumulation will be minimal. Examination of the population's response to environmental shock supports the hypothesis, with different populations accumulating N2O when exposed to different environmental shocks. No population was susceptible to N2O accumulation under all conditions. Populations that exhibited NO2- accumulation were resistant to NO2- shock but more susceptible to changes in pH, while populations exhibiting minimal NO2- accumulation were sensitive to NO2- shock but more resistant to changes in PH accumulation. This research concludes that denitrifying microbial populations determine the accumulation of N2O in response to changes in environmental conditions. Denitrifying populations differ between WWTPs. However, results suggest, irrespective of the denitrifying microbial population's structure, stable conditions will result in minimal N2O accumulation. When exposed to environmental shock differing populations showed susceptibility to accumulated N2O under differing environmental conditions. These results suggest that management of N2O accumulation and subsequent emissions will need to be on a case by case basis. Emissions may be addressed by the introduction of a microbial population less susceptible to the N2O accumulation under the environmental conditions of a given treatment plant. Further research is required to test the feasibility of this management strategy.
