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Mao, Yanping, i 毛艷萍. "Biological removal of phosphorus and nitrogen from wastewater : new insights from metagenomic and metatranscriptomic approaches". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206323.
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Yan, Qingmei, i 嚴慶梅. "Biological nitrogen removal of saline wastewater by ammoniumoxidizers". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42182116.
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Chen, Wen, i 陳雯. "A membrane bioreactor(MBR) for an innovative biological nitrogen removal process". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557959.
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楊龍元 i Lung-yuen Christopher Yeong. "Removal of wastewater cod and nitrogen using fibrous packing media". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31210636.
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Cao, Keping. "Simultaneous Removal of Carbon and Nitrogen by Using a Single Bioreactor for Land Limited Application". Thesis, Water Resources Research Center, University of Hawaii at Manoa, 1998. http://hdl.handle.net/10125/22230.
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An Entrapped-Mixed-Microbial-Cell (EMMC) process was investigated for its simultaneous removal of carbon and nitrogen in a single bioreactor with the influent COD/N ratio varying from 4 to 15 and influent alkalinity of 140 mg CaCO3/L and 230 mg CaCO3/L. The reactor was operated with alternate schedules of intermittent aeration. Two different sizes of carriers (10 * 10 * 10 mm3 and 20 * 20 * 20 mm3) were studied.
The medium carrier (10 * 10 * 10 mm3) system presents higher nitrogen removal and COD removal compared to the large carrier system. The nitrogen removal efficiency is related to the ratio of COD/N in the influent. With the increase of the COD/N ration in the influent, the nitrogen removal efficiency is increased.
The average reductions of nitrogen were over 92% and the average reductions of SCOD and BOD5 are over 95% and 97%, respectively, in the medium carrier system. This is operated at the HRT of 12 hours and 0.5 hour aeration and 2 hours of non-aeration, and the COD/N ratio of 15 in the influent. Changing alkalinity from 140 to 230 mg CaCO3/L has no effect in both large and medium carriers for the nitrogen removal efficiency.
The pH, oxidation – reduction potential (ORP) and dissolved oxygen (DO) were used to monitor the biological nitrogen removal. It was found that the ORP (range from -100 to 300 mV) can be used to provide better effluent quality measured as total-nitrogen of less than 10 mg/L. Also, the impact of influent COD/N ratio on the effluent quality (measured as Inorg.-nitrogen) for the EMMC process is very important.
Compared to other two compact biological wastewater treatment processes, membrane bioreactor (MBR) and moving bed biofilm reactor (MBBR), the EMMC process with the intermittent aeration has higher removal efficiencies of carbon and nitrogen, easier operation, lower O&M cost, lower energy requirement, and more compact. The total cost requirement is less than $3.27 per 1000 gallons (3.785 m 3) of treated settled domestic sewage per day. It is apparent that the EMMC process is technically feasible for the simultaneous removal of carbon and nitrogen under the operation on a schedule of intermittent aeration and suitable to be used for replacement or upgrading of existing treatment plant at land limited area.
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Clayton, John Andrew. "Denitrification kinetics in biological nitrogen and phosphorus removal activated sludge systems". Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/21139.
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In order to size the anoxic reactors in nutrient (N and P) removal activated sludge plants, it is essential to know the denitrification kinetics that are operative in such systems. To date, denitrification kinetics have been accurately defined only for systems that remove N alone; little research has been performed on denitrification in N and P removal plants.
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黃金華 i Kam-wah Wong. "Deritrification in the activated sludge process with controlled anoxicconditions in the aeration tank". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31208423.
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Hijazi, Amal. "Nitrogen and phosphorus transformations in fixed-film biofilters subjected to aeration/no-aeration cycles". Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36070/6/36070_Digitised_Thesis.pdf.
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Despite recent developments in fixed-film combined biological nutrients removal (BNR) technology; fixed-film systems (i.e., biofilters), are still at the early stages of development and their application has been limited to a few laboratory-scale experiments. Achieving enhanced biological phosphorus removal in fixed-film systems requires exposing the micro-organisms and the waste stream to alternating anaerobic/aerobic or anaerobic/anoxic conditions in cycles. The concept of cycle duration (CD) as a process control parameter is unique to fixed-film BNR systems, has not been previously investigated, and can be used to optimise the performance of such systems. The CD refers to the elapsed time before the biomass is re-exposed to the same environmental conditions in cycles.
Fixed-film systems offer many advantages over suspended growth systems such as reduced operating costs, simplicity of operation, absence of sludge recycling problems, and compactness. The control of nutrient discharges to water bodies, improves water quality, fish production, and allow water reuse. The main objective of this study was to develop a fundamental understanding of the effect of CD on the transformations of nutrients in fixed-film biofilter systems subjected to alternating aeration I no-aeration cycles A fixed-film biofilter system consisting of three up-flow biofilters connected in series was developed and tested. The first and third biofilters were operated in a cyclic mode in which the biomass was subjected to aeration/no-aeration cycles. The influent wastewater was simulated aquaculture whose composition was based on actual water quality parameters of aquacuture wastewater from a prawn grow-out facility. The influent contained 8.5 - 9:3 mg!L a111monia-N, 8.5- 8.7 mg/L phosphate-P, and 45- 50 mg!L acetate. Two independent studies were conducted at two biofiltration rates to evaluate and confirm the effect of CD on nutrient transformations in the biofilter system for application in aquaculture: A third study was conducted to enhance denitrification in the system using an external carbon- source at a rate varying from 0-24 ml/min. The CD was varied in the range of0.25- 120 hours for the first two studies and fixed at 12 hours for the third study.
This study identified the CD as an important process control parameter that can be used to optimise the performance of full-scale fixed-film systems for BNR which represents a novel contribution in this field of research. The CD resulted in environmental conditions that inhibited or enhanced nutrient transformations. The effect of CD on BNR in fixed-film systems in terms of phosphorus biomass saturation and depletion has been established. Short CDs did not permit the establishment of anaerobic activity in the un-aerated biofilter and, thus, inhibited phosphorus release.
Long CDs resulted in extended anaerobic activity and, thus, resulted in active phosphorus release. Long CDs, however, resulted in depleting the biomass phosphorus reservoir in the releasing biofilter and saturating the biomass phosphorus reservoir in the up-taking biofilter in the cycle. This phosphorus biomass saturation/depletion phenomenon imposes a practical limit on how short or long the CD can be. The length of the CD should be somewhere just before saturation or depletion occur and for the system tested, the optimal CD was 12 hours for the biofiltration rates tested.
The system achieved limited net phosphorus removal due to the limited sludge wasting and lack of external carbon supply during phosphorus uptake. The phosphorus saturation and depletion reflected the need to extract phosphorus from the phosphorus-rich micro-organisms, for example, through back-washing. The major challenges of achieving phosphorus removal in the system included: (I) overcoming the deterioration in the performance of the system during the transition period following the start of each new cycle; and (2) wasting excess phosphorus-saturated biomass following the aeration cycle. Denitrification occurred in poorly aerated sections of the third biofilter and generally declined as the CD increased and as the time progressed in the individual cycle. Denitrification and phosphorus uptake were supplied by an internal organic carbon source, and the addition of an external carbon source (acetate) to the third biofilter resulted in improved denitrification efficiency in the system from 18.4 without supplemental carbon to 88.7% when the carbon dose reached 24 mL/min The removal of TOC and nitrification improved as the CD increased, as a result of the reduction in the frequency of transition periods between the cycles. A conceptual design of an effective fixed-film BNR biofilter system for the treatment of the influent simulated aquaculture wastewater was proposed based on the findings of the study.
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Guo, Lei. "Optimization of BNR from wastewater using SBR and A²O processes". Thesis, University of Macau, 2011. http://umaclib3.umac.mo/record=b2493027.
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Hanson, Carter Curtis. "Temporal effect on nitrogen removal in a subsurface flow constructed wetland". Virtual Press, 1996. http://liblink.bsu.edu/uhtbin/catkey/1027117.
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A subsurface flow constructed wetland planted with the common reed (Phragmites australis) and softstem bulrush (Scirpus validus) was built in East Central Indiana. The objective of this study was to determine if temperature had an effect on nitrogen (N) removal from the wetland. The research was conducted from the first week of October 3, 1995 to the first week in December 5, 1995 why the wetland froze. Water samples were taken from 5 samplings sites in the system. Each sample was analyzed for organic-N, ammonia, nitrate, and total-N. In the system statistically significant amounts of organic-N, nitrate, and total-N were removed. Ammonia lever reductions, however, were not significant. Organic-N had a mean removal of 37% (8 mg/1) 'Nitrate had a mean removal of 96% (2.3 mg/1). Total-N removal over the sampling period averaged 30% (12 mg/1). The N results were regressed against air and wastewater temperatures. Wastewater temperature was more important because it had a direct impact can the plants and microbes in the system. Warmer temperatures sustained a higher metabolism for the biota in the system. Air temperature had an indirect impact on efficiency of N removal from the wastewater flowing through the wetland. The primary impact .: f the air temperature was on water temperature which then affected the metabolism of or a nc ns in the wetland cell. Greater removal efficiencies were seen during high temperature periods and lower removal efficiencies were noted when the temperatures were low.Department of Natural Resources and Environmental Management
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朱潔嫻 i Kit-han Kristin Chu. "Biotreatment of waste water by Pistia stratiotes L. and its application in agriculture". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31214058.
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Schultz, Paul Eaton. "Nitrogen removal and biomass production from a harvested and unharvested scirpus wetland". Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1048389.
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A subsurface flow constructed wetland was built at the Wastewater Treatment Plant in Muncie, Indiana, in May, 1995. In May, 1996, this wetland was divided into two equal cells and planted with Scirpus validus vahl (softstem bulrush). Samples were collected from July 30, 1996, through October 22, 1996. This study had two objectives. The first was to determine if harvesting the aboveground biomass of the Scirpus would affect the wetland's ability to remove nitrogen from the wastewater. The second objective of this study was to determine if harvesting the bulrush twice during a growing season would substantially increase the annual biomass production. Water was collected from four locations in each cell and analyzed for organic nitrogen, ammonical nitrogen, nitrate, and total nitrogen. The concentration of each nitrogen parameter was significantly reduced between the inlet and well 1 in each cell of the wetland. There were no significant reductions in nitrogen concentration in subsequent sampling locations. There were also no significant differences between the two wetland cells.Department of Natural Resources and Environmental Management
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Degen, Marcia J. "Denitrification in low pressure distribution onsite wastewater disposal systems". Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/29272.
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Zhang, Zhenhua. "Plant growth and nutrient removal in simulated secondary-treated municipal wastewater in wetland microcosmos". University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0141.
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[Truncated abstract] The use of constructed wetlands for tertiary purification of municipal wastewater has received increasing attention around the world because direct discharge of secondary-treated municipal wastewater to water bodies has caused eutrophication. Plant species selection and vegetation management may enhance nutrient removal efficiency in constructed wetlands. However, there is a lack of knowledge on the relations between plant growth and nutrient removal efficiency in constructed wetlands. The objective of this study is to better understand how plant growth and resource allocation are influenced by nutrients in wastewater and how nutrient removal efficiencies are affected by plant species and vegetation management. The preliminary experiment was conducted to select macrophytes, especially ornamental species, to grow in the wastewater in the wetland microcosms. Ten plant species, comprising six ornamental species: Alocasia macrorrhiza, Canna indica, Iris louisiana, Lythrum sp., Zantedeschia aethiopica, Zantedeschia sp., and four sedge species: Baumea articulate, Baumea juncea, Carex tereticaulis and Schoenoplectus validus, were planted in the wetland microcosms and fed a simulated wastewater solution in the concentrations similar to the secondary-treated municipal wastewater. C. indica has shown vigorous and healthy growth, and a relatively high potential of rooting-zone aeration and nutrient removal efficiency. B. articulata and S. validus also showed relatively high nutrient removal efficiency. ... The high nutrient availability and optimum N/P ratio were required for stimulating plant growth, resulting in allocation of more resources to above-ground tissues compared to below-ground parts, and enhancing nutrient removal efficiency. Nutrient removal efficiencies were significantly influenced by growth of C. indica and S. validus, nutrient loading rates and N/P ratios in the wastewater. The nutrient uptake kinetics of C. indica and S. validus were investigated to elucidate the differences in nutrient uptake between species. Wetland plant species have shown differential nutrient uptake efficiency and different preferences for inorganic N source, with C. indica preferring NO3-N and S. validus preferring NH4-N. C. indica had greater capacity than S. validus to take up PO4-P when the concentration of PO4-P in the solution was relatively low, whereas S. validus was more capable than C. indica to take up NO3-N when the concentration of NO3-N in the solution was relatively low. The PO4-P uptake capacity was higher in younger than older plants. Overall, the study has suggested that different plant species have differential capacity to take up nutrients. In addition to nutrient uptake, plants have significant other roles in terms of nutrient removal from the wastewater (such as leaking oxygen into the rhizosphere in which oxidation of substances like ammonia can occur). The properly high nutrient availability and optimum N/P ratio are required to stimulate the plant growth, resulting in enhancing the treatment performance in the wetlands. These findings have important implications for improving our ability to engineer ecological solutions to the problems associated with nutrient-rich wastewater.
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Kasmuri, Norhafezah. "The removal of ammonia-nitrogen and degradation of 17α-ethynylestradiol and mestranol using partial fixed bed continuous reactor (PFBR) and moving bed continuous reactor (MBBR)". Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42223.
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Effective treatment of wastewater is an important process in reducing the environmental impact of industry and human activity. Although conventional water treatment systems can adequately remove the principle components of waste (i.e. substances that can be represented the majority of biological and chemical oxygen demand) several materials are poorly or slowly removed. Tertiary treatment polishing processes are therefore required to remove these contaminants to ensure complete wastewater treatment. This thesis reports investigations made using film reactors that are used to remove recalcitrant materials such as ammonia- nitrogen and endocrine disrupters that although present in low concentrations, if left untreated can have a strong impact on the environment. Film reactors potentially offer several process advantages over conventional activated sludge treatments systems as they allow very long residence time and contact with high concentrations of fixed microbes with the low concentrations of pollutants so enhancing kinetic performance and efficiency of the process. Two reactor configurations, a partial fixed bed (PFBR) and moving bed biofilm reactors (MBBR) were investigated. A thirty liter reactor with a working volume of 16 liters was constructed and contained fixed microbial films on either free suspended or fixed beds plastic packing (K2 AnoxKaldnes). The investigation of ammonia-nitrogen oxidation showed that after a suitable acclimation period (2 weeks) that ammonia was oxidise rapidly reducing the feed concentrations of 35 mg/L to < 2 mg/L in the effluent. To assess the performance for ammonia-nitrogen removal the reactors operated for long periods (up to 3 months) with continuous feed using the reactor in either PFBR or MBBR modes in addition of 17alpha-ethynylestradiol (EE2) and mestranol (MeEE2), the endocrine disrupting compounds commonly found in municipal wastewater. These substances is derived from a synthetic hormones if found in the natural environment can reduced the productivity of the fish as this can cause feminization in aquatic organisms with disastrous consequences on fish populations. The MBBR and PFBR systems were used to investigate the co-metabolism of ammonia-nitrogen, 17alpha-ethynylestradiol (EE2) and mestranol from model waste water feed containing 35 mg/L of ammonia-nitrogen and 100 mug/L of 17alpha-ethynylestradiol (EE2) and mestranol (MeEE2). A kinetic analysis of the systems were made and for the PFBR reactor, the specific growth rate, mumax of 7.092 d-1 with saturation constants, Ks of 1.574 mg/L. The kinetic analysis for the MBBR system was 6.329 d-1 for the mumax with the K.S of 0.652 mg/L. When the PFBR was used removal of EE2 represents 70% MeEE2 was removed. MBBR were shown to be more effective and efficient in removing ammonia-nitrogen reducing the levels under good conditions to > 2 mg/L while the PFBR could also achieve 2 mg/L. The MBBR system was also more competent in the removal of 17alpha-ethynylestradiol (EE2) and mestranol compared to PFBR. This work demonstrates that there are considerable advantages to using thin film reactors as polishing step for the tertiary treatment of waste waters when to compared to other processes in reducing the inorganic pollutants as endocrine disrupting compounds. The significance of these results is discussed in this context.
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McMillan, Morgan. "Biological treatment of source separated urine in a sequencing batch reactor". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96047.
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Thesis (MScEng) -- Stellenbosch University, 2014.ENGLISH ABSTRACT: Urine contains up to 80% of nitrogen, 50 % of phosphates and 90 % of potassium of the total load in domestic wastewater but makes up less than 1% of the total volume (Larsen et al., 1996). The source separation and separate treatment of this concentrated waste stream can have various downstream advantages on wastewater infrastructure and treated effluent quality. The handling of undiluted source separated urine however poses various challenges from the origin onward. The urine has to be transported to a point of discharge and ultimately has to be treated in order to remove the high loads of organics and nutrients. Wilsenach (2006) proposed onsite treatment of source separated urine in a sequencing batch reactor before discharging it into the sewer system. This study focused on the treatment of urine in a sequencing batch reactor (SBR) primarily for removal of nitrogen through biological nitrification-denitrification. The aim of the study was to determine nitrification and denitrification kinetics of undiluted urine as well as quantification of the stoichiometric reactions. A further objective was to develop a mathematical model for nitrification and denitrification of urine using experimental data from the SBR. The SBR was operated in 24 hour cycles consisting of an anoxic denitrification phase and an aerobic nitrification phase. The sludge age and hydraulic retention time was maintained at 20 days. pH was controlled through influent urine during volume exchanges. Undiluted urine for the study was obtained from a source separation system at an office at the CSIR campus in Stellenbosch. Conditions in the reactor were monitored by online temperature, pH and ORP probes. The OUR of the system was also measured online. One of the main challenges in the biological treatment of undiluted urine was the inhibiting effect thereof on nitrification rate. The anoxic mass fraction was therefore limited to 17 % in order to allow longer aerobic phases and compensate for the slow nitrification rates. Volume exchanges were also limited to 5% of the reactor volume in order to maintain pH within optimal range. Samples from the reactor were analysed for TKN, FSA-N, nitrite-N, nitrate-N and COD. From the analytical results it was concluded that ammonia oxidising organisms and nitrite oxidising organism were inhibited as significant concentrations of ammonia-N and nitrite-N were present in the effluent. It was also concluded that nitrite oxidising organisms were more severely inhibited than ammonia oxidising organisms as nitrate-N was present in very low concentrations in the effluent and in some instances not present at all. Ultimately the experimental system was capable of converting 66% of FSA-N to nitrite- N/nitrate-N of which 44% was converted to nitrogen gas. On average 48% of COD was removed. A mathematical model was developed in spreadsheet form using a time step integration method. The model was calibrated with measured online data from the SBR and evaluated by comparing the output with analytical results. Biomass in the model was devised into three groups, namely heterotrophic organisms, autotrophic ammonia oxidisers (AAO) and autotrophic nitrite oxidisers (ANO). It was found that biomass fractionation into these three groups of 40% heterotrophs, 30% AAO and 30% ANO produced best results. The model was capable of reproducing the general trends of changes in substrate for the various organism groups as well as OUR. The accuracy of the results however varies and nearexact results were not always achievable. The model has some imperfections and limitations but provides a basis for future work.
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Tugtas, Adile Evren. "Effect of Nitrate Reduction on the Methanogenic Fermentation: Process Interactions and Modeling". Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-01122007-155216/.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007.Sotira Yiacoumi, Committee Member ; Patricia Sobecky, Committee Member ; Ching-Hua Huang, Committee Member ; Dr. Spyros Pavlostathis, Committee Chair ; Frank Loeffler, Committee Member.
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Ferro, Thayse Nathalie. "Remoção de matéria carbonácea, nitrogenada e fosfatada em um sistema anaeróbio-aeróbio-anóxico (AOA) submetido a variações de cargas orgânicas e hidráulicas". Universidade Tecnológica Federal do Paraná, 2018. http://repositorio.utfpr.edu.br/jspui/handle/1/3117.
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Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do ParanáNo Brasil, as estações de tratamento de esgoto têm suas configurações baseadas em processos anaeróbios seguidos ou não de pós tratamento, normalmente aeróbio. Estas configurações apresentam limitações como baixa eficiência de remoção de nutrientes. Assim, ao considerar aspectos técnicos, pretende-se avaliar a eficiência de remoção da matéria carbonácea, nitrogenada e fosfatada, em sistema de tratamento combinado anaeróbio (22,1 L), aeróbio (19,9 L) e anóxico (17,4 L) (AOA), tratando esgoto sintético. Anéis corrugados de Policloreto de Polivinila (PVC) foram utilizados como material suporte para fixação da biomassa. O comportamento do sistema foi avaliado em quatro etapas distintas, nas quais foram analisadas a influência da adição de carbono no reator anóxico e da redução do Tempo de Detenção Hidráulica (θh) nos reatores anaeróbios e aeróbios. O desempenho do sistema foi estudado por meio de perfis de amostragem temporal com determinação dos parâmetros físicoquímicos temperatura do líquido (TL), pH, alcalinidade total (AT), alcalinidade a bicarbonato (AB), ácidos voláteis (AV), oxigênio dissolvido (OD), potencial de oxirredução (REDOX), turbidez (UNT), demanda química de oxigênio (DQO) nitrogênio total kjeldahl (NTK), nitrogênio amoniacal (N-NH4 + ), nitrito (N-NO2 - ), nitrato (N-NO3 - ) e fósforo total (P-PO4 -3 ), em amostras do afluente e efluente de cada reator coletadas em intervalos de 3 h durante 24 h. Na Etapa 1 foram obtidas eficiências de remoção de matéria carbonácea, nitrogenada e fosfatada de 97%, 57% e 50%, respectivamente, para o sistema operado com θh de 8 h para o reator anaeróbio, 7,3 h para o reator aeróbio e 6,4 h para o reator anóxico. Na Etapa 2 com adição de 20% da vazão afluente de esgoto bruto (fonte de carbono) e manutenção dos valores de θh, as eficiências de remoção de carbono e nitrogênio total foram de 95% e 55%, não sendo reportada eficiência de remoção de fósforo. Na Etapa 3 com a retirada da fonte de carbono e redução do θh nos reatores anaeróbio e aeróbio para 4 h, foram obtidas eficiências de remoção de 96% de matéria carbonácea, 51% de nitrogênio total e 40% de fósforo. Na Etapa 4 com manutenção do θh de 4 h para o reator anaeróbio, 7,3 h para o reator aeróbio e 6,4 h para o reator anóxico, as eficiências de remoção resultaram em 97% de matéria carbonácea, 43% de nitrogênio total e 41% de fósforo. Com o estudo cinético foi possível verificar que a redução da relação C/N influenciou positivamente o desempenho dos microrganismos nitrificantes e desnitrificantes. Por fim, conclui-se que o sistema AOA apresentou eficiência de remoção de matéria carbonácea superior ao limite exigido na legislação e proporcionou remoção simultânea de nitrogênio e fósforo.
In Brazil, sewage treatment plants have their configurations based on anaerobic processes followed or not by post-treatment, usually aerobic. These configurations have limitations such as low nutrient removal efficiency. Thus, when considering technical aspects, it was intended to evaluate the efficiency of removal of carbonaceous, nitrogenous and phosphate in an anaerobic (22.1 L), aerobic (19.9 L) and anoxic (17.4 L) (AOA) treating synthetic wastewater. Polyvinyl chloride corrugated rings (PVC) were used as support material for biomass fixation. The behavior of the system was evaluated in four different stages in order to analyze the influence of the addition of carbon in the anoxic reactor and the reduction of Hydraulic Retention Times (θh) in the anaerobic and aerobic reactors. The performance of the system was studied by means of temporal sampling profiles with determination of the physicchemical parameters temperature, pH, alkalinity total (AT) and bicarbonate (AB), volatile acids (VA), dissolved oxygen (OD), oxidation potential (REDOX), turbidity (UNT), chemical oxygen demand (COD), total nitrogen kjeldahl (NTK), ammoniac nitrogen (N-NH4 + ), nitrite (N-NO2 - ), nitrate (N-NO3 - ), and total phosphorus (P-PO4 -3 ) in samples of the influent and effluent from each reactor collected at intervals of 3 h for 24 h. In Stage 1, the removal efficiency of 97%, 57% and 50% of carbonaceous, nitrogenous and phosphate matter was obtained for the system operated with θh of 8 h for the anaerobic reactor, 7.3 h for the aerobic reactor and 6.4 h for the anoxic reactor. In Stage 2 with the addition of 20% of the raw sewage inflow (carbon source) and maintenance of the θh values, the carbon and total nitrogen removal efficiencies were 95% and 55%, with no reported removal efficiency phosphor. In Stage 3, with the removal of the carbon source and reduction of the θh in the anaerobic and aerobic reactors for 4 h, removal efficiencies of 96% of carbonaceous matter, 51% of total nitrogen and 40% of phosphorus were obtained. In Stage 4 with the maintenance of the θh of 4 h for the anaerobic reactor, 7.3 h for the aerobic reactor and 6.4 h for the anoxic reactor, the removal efficiencies resulted in 97% of carbonaceous matter, 43% of total nitrogen and 41% phosphorus. With the kinetic study, it was possible to verify that the reduction of the C/N positively influenced the performance of the nitrifying and denitrifying microorganisms. Finally, it can be concluded that the AOA system presented removal efficiency of carbonaceous matter higher than the limit required by the legislation and provided simultaneous removal of nitrogen and phosphorus.
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Vargas, Lara Jose Maria. "Identificação de modelos para controle preditivo : aplicação a uma planta de lodos ativados". [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260341.
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Orientador: Basilio Ernesto de Almeida MilaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
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Resumo: Este trabalho trata da síntese de um controlador preditivo adaptativo, baseado em modelos reduzidos obtidos mediante identificação orientada para controle preditivo. A metodologia proposta envolve duas áreas importantes para o sucesso do experimento de identificação. Na primeira, projeto de sinais de excitação, é mostrado como sinais de excitação pseudo-aleatórios multi-níveis podem ser projetados para atender com eficácia requisitos que sinais de excitação relevantes para controle devem satisfazer. Na segunda, modelagem de preditores, é abordada a modelagem por identificação de preditores de horizonte estendido. O objetivo central da metodologia proposta é o controle da remoção de matéria nitrogenada de uma planta de tratamento de esgotos por lodos ativados com pré-desnitrificação. A metodologia é aplicada para controlar a concentração de amônia mediante o controle do set-point de oxigênio dissolvido. A metodologia também é aplicada para o controle da concentração de nitrato no reator desnitrificante. Os controladores são avaliados em um estudo de simulação, mostrando a eficácia da metodologia proposta para o controle das concentrações de amônia e nitrato
Abstract: This work deals with the synthesis of an adaptive predictive controller, based on reduced models obtained via identification oriented to predictive control. The methodology proposed involves two important areas for the success of the identification experiment. In the first one, excitation signal design, it is shown how pseudo-random multilevel signals can be designed to effectively satisfy the requirements that excitation signals relevant for control should satisfy. In the second, predictor modelling, the identification of long-range horizon predictors is approached. The main objective of the proposed methodology is the control of the nitrogen removal in an predenitrifying activated sludge wastewater treatment plant. This methodology is applied to control the ammonium concentration in the denitrifying reactor. The controllers are evaluated in a simulation study, showing the effectiveness of the proposed methodology to control ammonium and nitrate concentrations
Doutorado
Automação
Doutor em Engenharia Elétrica
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Yan, Qingmei. "Biological nitrogen removal of saline wastewater by ammonium oxidizers". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42182116.
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Yeong, Lung-yuen Christopher. "Removal of wastewater cod and nitrogen using fibrous packing media /". [Hong Kong : University of Hong Kong], 1991. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13193429.
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Chen, Wen. "A membrane bioreactor(MBR) for an innovative biological nitrogen removal process". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557959.
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Copp, John B. "COD balances in biological nutrient (nitrogen and phosphorus) removal activated sludge systems /". *McMaster only, 1998.
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Sun, Feiyun, i 孙飞云. "A membrane bioreactor (MBR) for a biological nutrient removal system: treatment performance, membrane foulingmechanism and its mitigation strategy". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44903856.
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Morrison, Kirk Murray. "An assessment of the potential for biological phosphorus removal in Canadian wastewater treatment plants". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28507.
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This thesis assesses the potential for enhanced biological phosphorus (Bio-P) removal in Canadian wastewater treatment plants. Retrofit designs incorporating Bio-P removal were prepared for nine wastewater treatment plants across Canada, and were compared against chemical phosphorus removal technologies. Incremental capital and operating costs were calculated and internal rates of return (IRR's) for the capital investment required to install the Bio-P removal facilities were calculated. Based on these results, an assessment of the potential use for the technology in Canada is made.
Of the nine plants studied, results indicate that Bio-P removal is economically superior to chemical phosphorus removal for the Calgary Bonnybrook, Edmonton Gold Bar, Saskatoon Mclvor Weir and Regina wastewater treatment plants. In general, Bio-P removal appears to offer significant economic advantages to
plants located in Alberta and Saskatchewan because of the high
cost of phosphorus removal chemicals in these provinces. The
present low cost of phosphorus removal chemicals in Ontario and
Quebec likely limits the viability of Bio-P removal to large (greater than 300,000 m³/d), suitably configured plants. In British Columbia, where Bio-P removal is presently used in the Okanagan Valley, the absence of widespread provincial phosphorus removal standards makes future Bio-P installations unlikely. The potential for Bio-P removal in Manitoba, the Maritimes and the Yukon and Northwest Territories is again limited by the absence of phosphorus removal standards in these parts of Canada.
Results also indicate that the use of an anoxic/anaerobic/ aerobic process in the bioreactor, in conjunction with primary sludge fermentation through gravity thickening, is very applicable to Canadian plants and offers potential capital and operating cost savings relative to other Bio-P processes. The common practice of anaerobic sludge digestion, combined with sludge dewatering and land application, was found to be unfavourable from a Bio-P perspective unless the resulting supernatant/filtrate streams can be re-used or disposed of outside of the mainstream treatment process.
Through the preparation of the retrofit designs, it was
determined that certain aspects of Bio-P technology require additional research in order to optimize treatment plant design.
These include kinetic modelling; short SRT Bio-P removal; the
anorexic/anaerobic/aerobic process; the use of gravity thickening
for primary sludge fermentation; and phosphorus release during anaerobic digestion.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Lindawati. "Operational strategies for optimal carbon, nitrogen and phosphorus removal using sequencing batch reactor /". View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CENG%202004%20LINDAW.
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Zhao, Kang, i 趙鈧. "An iron-facilitated chemical and biological process for phosphorus removal and recovery during wastewater treatment". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196027.
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Phosphorus (P) is an important pollutant of concern in wastewater that causes eutrophication and algal blooms in water body. On the other hand, P is a valuable natural resource for agricultural and industrial use. With the rapid depletion of mineral phosphorus on earth, there is a need to recover phosphorus from wastewater. In this study, a new chemical and biological process facilitated with iron dosing has been developed for P removal and recovery during wastewater treatment. The system consists of a main stream identical to the conventional activated sludge process in an aerobic sequencing batch reactor (SBR) for P removal and a side stream of sludge recirculation through an anaerobic SBR (AnSBR) for P release and recovery from the P-rich sludge.
In the aerobic SBR treating a synthetic domestic wastewater, Fe(III) (FeCl3) was dosed to remove P by precipitation and adsorption. Fe(III) dosing at a Fe/P molar ratio of 1.5:1 could reduce the P concentration from more than 10 mg/L to below 1 mg/L in the final effluent. Compared to other dosing periods, dosing Fe(III) right before the SBR settling could achieve the best result in sludge flocculation and P removal. Meanwhile, organic removal was well maintained as 90% of the chemical oxygen demand (COD) was degraded in the aerobic SBR. In the AnSBR, phosphate precipitated with ferric iron in the sludge was released owing to microbial Fe(III) reduction, and a positive correlation was found between the phosphate and ferrous iron concentrations in the sludge suspension. Chemical tests showed that significant P release from Fe(III)-P occurred only if the acidic condition and the reducing condition were combined. For the AnSBR sludge, a higher organic loading, lower pH and higher biomass concentration resulted in a higher level of Fe(III) reduction and P release. Organic acidogenesis prevailed in the reactor and lowered the pH to ~4.5, which facilitated the P release from the solid phase into the liquid phase. With a solids retention time (SRT) of 10 days, the anaerobic supernatant contained a phosphate concentration of up to 70 mg/L, while the settled sludge was returned to the aerobic SBR. The phosphate could be readily recovered from the supernatant with Fe-induced precipitation by aeration and pH adjustment, and the overall P recovery could be achieved at about 70%. In addition to the treatment performance, the speciation of P in the aerobic sludge and the anaerobic sludge also was investigated. A significant change in the immediately available P and the redox-sensitive P was found in the sludge through the aerobic-anaerobic cycle. Such chemical transformation is believed to be crucial to the P removal and recovery during the wastewater treatment process.published_or_final_version
Civil Engineering
Master
Master of Philosophy
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凌偉忠 i Wai-chung Jackson Ling. "Biological nutrient removal in sequencing batch reactors using fibrouspacking medium". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31213388.
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Lee, N. P. (Nelson Paul). "The affect of anaerobic volume reduction on the University of Cape Town (UCT) biological phosphorus removal process". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29631.
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The objective of this research was to optimize the bio-P process as applied to a weak sewage with respect to HRT in each of the process zones. This goal was to be achieved by changing the HRT of the various zones with all other operating characteristics being held constant.
The experimental work during this study involved two initially identical process trains operated in the University of Cape Town (UCT) mode. The aerobic zones of both trains were divided into four equal sized complete-mix cells to allow observations of phosphate uptake and poly-β-hydroxyalkanoate (PHA) consumption under aerobic conditions. After steady-state was established, the anaerobic HRT was reduced to 50% of the original value in the experimental module by reducing the anaerobic reactor volume. At the same time, the mixed liquor of both trains was drained, mixed and reapportioned to the two processes, thereby assuring equivalent starting conditions.
Results of this study showed that both processes performed identically prior to the anaerobic HRT change. After the anaerobic HRT change, there was a forty day period where P removal and effluent P were the same in both process trains. This was so, even though the anaerobic P release was considerably less in the experimental module. Subsequently, a change in influent sewage type corresponded to a change in P removal and effluent P in the two process trains. An examination of the process parameters showed that the anoxic zone of the experimental module, after the anaerobic HRT change and the sewage change, consistently removed less P or released more P than
in the control module. As a result, the control module out-performed the experimental module. Batch tests and tests to better characterize the influent sewage were then conducted in an attempt to determine the reasons for the different P removal characteristics.
Under the test conditions, it appeared that the original anaerobic HRT was excessive. This was preferable to an insufficient anaerobic HRT, such as in the experimental module, however. The anoxic zone may have been too large, too small or just right for optimum P removal depending on the influent sewage characteristics. Optimizing the bio-P process by reducing the aerobic zone HRT appeared to have the greatest potential.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Casher, Thomas Christopher. "Biological excess phosphorus removal under high rate operating conditions in a suspended growth treatment process". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29464.
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The primary objective of this research was to determine if efficient biological phosphorus removal could be established under low sludge retention time of 2 days and a nominal hydraulic retention time of 4 to 6 hours. The two-stage Phoredox process was selected because of the practical application of retrofitting high rate treatment plants to achieve bio-P removal without the additional tankage required for an anoxic section and the additional expense of a recycle system.
It has been shown that nitrate recycled into the anaerobic reactor impacts on bio-P removal and the two-stage Phoredox process provides no control over nitrates entering the anaerobic reactor. Therefore a secondary objective of this research was to determine if a low sludge retention time mode of operation could be used as an effective way to prevent nitrification in the activated sludge treatment process.
Another objective was to observe mixed liquor settling characteristics of the two-stage Phoredox process operated under high rate conditions.
A pilot scale two-stage Phoredox activated sludge treatment process operating under high rate conditions was used to meet these objectives. The desired bio-P removal biomass was not observed under SRT operating conditions of 2, 3 and 5 days. Partway into the research a sludge bulking condition developed which was identified as filamentous
growth. On two occasions this severe filamentous growth resulted in the process failing and the system being restarted.
On one occasion after the system was restarted using a seed sludge from a three-stage Phoredox pilot plant, a bio-P removal biomass was present. This condition only lasted for a short period and ended as filamentous growth began to become dominant. The process failed because of this phenomenon.
The system was restarted using a seed sludge and again filamentous growth dominated. Chlorine addition was found to be the only method to control this phenomenon and was continued to the end of the research. The desired bio-P removal biomass was not observed even during the last period of the research when the SRT was increased to 8 days.
During this research a stable bio-P removal biomass was not established. For a short period a bio-P removal biomass was present but failed to persist. Nitrification never became established at any time. Sludge settleability was poor due to filamentous growth which developed partway into the research and was present throughout the remainder of the study. Chlorine addition was the only method found that remedied this settling problem.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Brannan, Kenneth P. "Substrate stabilization in the anaerobic stage of a biological phosphorus removal system". Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49992.
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Zeng, Raymond Jianxiong. "The role of intracellular storage products in biological nutrient removal /". St. Lucia, Qld, 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16445.pdf.
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Shetty, Ameesha R. "Metal anion removal from wastewater using chitosan in a polymer enhanced diafiltration system". Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050406-115241/.
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Mann, Robert A., of Western Sydney Hawkesbury University i Faculty of Science and Technology. "Phosphorus removal by constructed wetlands : substratum adsorption". THESIS_FST_XXX_Mann_R.xml, 1996. http://handle.uws.edu.au:8081/1959.7/333.
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The phosphorus removal characteristics of several gravel-based constructed wetland systems (CWSs) in the treatment of secondary sewage effluent was studied.Investigations were conducted on water quality parameters (redox potential, pH, dissolved oxygen and temperature) which affect phosphorus adsorption to substrata.Laboratory phosphorus adsorption experiments on Richmond CWS gravel substrata, a gravel used in Griffith CWS trials and a locally available soil, Hawkesbury sandstone, involved ion-exchange experiments and calculation of Langmuir and Freundlich adsorption isotherms and column adsorption/desorption trials.Six steelworks by-products were investigated in laboratory studies, to determine their potential for use as phosphorus adsorbers in a CWS: granulated blast furnace slag(GBF), blast furnace slag(BF), steel slag(SS), fly ash(FA), bottom ash(BA) and coal wash(CW).The ability to adsorb phosphorus was then correlated to the chemical attributes of each substratum.Of the six steelworks by-products screened in laboratory-based studies as substrata for P removal in a CWS, BF and SS slags showed the most potential due to their high phosphorus adsorption capacity and useable matrix size.Further research is recommended to evaluate the sustainability of using slags for P removal (as well as other contaminants present in wastewater), using full scale CWSs, which should include an evaluation of any likely environmental impacts using leachability and toxicity studies.Doctor of Philosophy (PhD)(Environmental Science)
35
Rubidge, Gletwyn Robert. "Evaluation and optimization of selected methods of arsenic removal from industrial effluent". Thesis, Port Elizabeth Technikon, 2004. http://hdl.handle.net/10948/230.
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This research was directed at reducing arsenic levels in the effluents generated at the Canelands facility that manufactures monosodium methyl arsenate. Two effluent streams containing arsenic have to be considered, a raw water stream that is treated on site and a brine stream that is disposed of by sea outfall. Removal of arsenate from aqueous media by coagulation was investigated and models were developed describing selected variables that influence the removal of the arsenate. Three coagulant systems were investigated, namely aluminium(III) coagulation, iron(III) coagulation and binary mixtures of aluminium(III) and iron(III). Researchers have studied individual aluminium (III) sulphate and iron(III) chloride coagulation. No detailed research and modelling had, however, been carried out on the use of binary mixtures of aluminium (III) sulphate and iron (III) chloride coagulation of aqueous arsenate, nor had individual aluminium(III) sulphate and iron(III) chloride coagulation of arsenate been modelled at relatively high arsenate concentrations. The models that were generated were validated statistically and experimentally. The variables investigated in the aluminium(III) model included initial arsenate concentration, pH, polymeric flocculent concentration, aluminium(III) concentration and settling time. The variables modelled in the iron(III) coagulation were initial arsenate concentration, pH, polymeric flocculent concentration, and iron(III) to arsenic mole ratio. The modelling of the binary coagulant system included initial arsenate concentration, pH, iron (III) concentration, aluminium(III) concentration, and flocculent concentration as variables. The most efficient arsenic removal by coagulation was iron(III), followed by the binary mixture of aluminium(III) and iron(III) and the weakest coagulant was aluminium(III) sulphate. Scale-up coagulations performed on real raw water samples at a 50 litre volume showed that iron(III) was the most efficient coagulant (on a molar basis) followed closely by the binary mixture, while aluminium(III) coagulation was considerably weaker. The residual arsenic levels of the iron(III) and the binary coagulation systems met the effluent discharge criteria, but the aluminium coagulation system did not. Leaching tests showed that the iron(III) sludge was the most stable followed by the sludge of the binary mixture and the aluminium(III)-based sludge leached arsenic most readily. Settling rate studies showed that the flocs of the iron(III) coagulations settled the fastest, followed by binary mixture flocs and the aluminium flocs settled the slowest. The flocs of the binary mixture had the lowest volume, followed by the iron(III) flocs, while the aluminium(III) flocs were the most voluminous. Based on current operations of the raw water treatment plant the aluminium(III)-based coagulation is the most cost efficient. Given a relative costing of 1.00 for the aluminium(III) coagulation, the iron(III) chloride-based coagulation would be 2.67 times more expensive and the equimolar binary mixed aluminium(III)/iron(III) system would be 1.84 times the cost of aluminium(III) coagulation.
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Cronje, Martin. "Investigation of electrochemical combustion plant for rural water disinfection and industrial organic effluent removal". Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16292.
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Thesis (MScIng)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: Recent years have seen the development of various treatment methods for the purification of industrial waste waters due to the increased demand for reduced pollutant effluents. Aqueous waste streams containing toxic organic compounds are of special interest, since conventional treatment methods such as biological waste treatment can not always be used. Other popular treatment methods are often ineffective. Catalytic oxidation of organic wastes has been investigated since the 1960s with varying degrees of success. A major problem associated with this method is the high temperatures and pressures required to improve the activation energies involved. Electrochemical oxidation has become a popular method in the literature of treating these wastes, since the applied voltage determines the activation energy, and therefore the process can often be performed at ambient conditions. This thesis investigates the capability of a unique reactor system in the treatment of these wastes. The reactor utilises proton-exchange membrane technology to eliminate the requirement of conductivity in treated waste streams; thus the membrane serves as a solid electrolyte. The reactor system has therefore been referred to as a solid-polymer-electrolyte reactor. Novel metal oxide anodes are responsible for the oxidation of the organic molecules. These metal oxide catalysts show promise in the treatment of a wide variety of organic wastes. A SnO2 catalyst doped with ZrO2 is used as anode in this study. Dopants are added to the catalyst to improve properties such as catalytic activity and conductivity. Kinetic data was obtained on a wide range of values for the chosen experimental parameters (current density and flow rate). Phenol, an organic molecule often referred to in the literature as model contaminant due to its resistance to oxidation,was also used as contaminant in this study. The use of the reactor system in the disinfection of water containing selected pathogens, were included in the experimental work. This kinetic data served in the development of a simple model of the process, and provided the basis for a full analysis regarding potential scale-up and economic feasibility. A requirement of the study was the accurate determination of the various oxidation breakdown products of phenol. This led to the refinement of an HPLC analytical method in order to quantitatively determine these products. The full analysis showed that the current reactor system would not be economically viable — mainly due to very long reactor lengths required for the complete removal of all organic material. Both mass transfer and charge transfer at the chosen experimental conditions influenced the electrochemical oxidation of phenol. High pressure drops, causing low flow rates in the reactor, accounted for this because of the narrow flow channels required in the reactor. Some catalyst deactivation was also suspected to affect the overall reaction, but the full extent of the deactivation was not investigated thoroughly. There is still room for improvement in the electrochemical oxidation of organic wastes. The design of the flow channels, a factor that was not investigated, can significantly improve efficiency. Another aspect that was not investigated was the catalyst type. The catalyst has been identified in the literature as the main contributing factor to the success of the oxidation reaction. A wide variety of metal oxide catalysts are currently being researched and may improve the kinetics of the process even further. Further improvement needs to be made on the membrane/electrode assembly to improve current density distribution. Every improvement of the process in terms of the reactor design and catalyst will impact on the economics of the process, thus making the process more competitive with current treatment technologies.
AFRIKAANSE OPSOMMING: In die afgelope paar dekades, is daar ’n wye verskeidenheid metodes ontwikkel wat gebruik kan word om industri¨ele afvoer strome te behandel. Hierdie ontwikkeling het plaasgevind as gevolg van die verhoogde eis aan skoner afvoerstrome. Wateragtige afvoerstrome wat organiese verbindings bevat, is van besonderse belang omdat hierdie tipe strome soms besonders moeilik kan wees om te behandel. Gebruiklike metodes is in die meeste gevalle ongeskik vir behandelings-doeleindes. Katalitiese oksidasie is sedert die 1960’s gebruik, maar hierdie prosesse benodig dikwels ho¨e drukke en temperature om suksesvol te wees. Elektrochemiese oksidasie het intussen ’n populˆere behandelingsmetode geword, aangesien die aktiveringsenergie vir die oksidasieproses hoofsaaklik afhanklik is van die aangewende potensiaal en dus kan die proses by atmosferiese toestande gebruik word. In hierdie tesis word die geskiktheid van ’n unieke reaktorstelsel vir water-suiwering ondersoek. Die reaktor gebruik ’n proton-uitruilings-membraan om die behoefte vir konduktiwiteit in die water uit te skakel. Die membraan dien dus as ’n tipe soliede elektroliet en as gevolg hiervan word na die reaktorstelsel verwys as ’n soliede-polimeer-elektroliet reaktor. Nuwe metaal-oksied anodes word in die reaktor gebruik aangesien hulle belowende resultate toon in die oksidasie van organiese verbindings. In die navorsing, is ’n SnO2 katalis wat klein hoeveelhede ZrO2 bevat gebruik. Oksiede soos ZrO2 word dikwels gebruik om die aktiwiteit en konduktiwiteit van hierdie kataliste te bevorder. Kinetiese data is oor ’n wye bereik van parameter waardes ingesamel. Die hoof parameters in die eksperimentele werk was stroom digtheid en vloeitempo. Fenol, ‘n komponent wat volgens die literatuur in hierdie tipe van werk gebruik word, isas die besoedelende komponent gekies. Die doeltreffendheid van die reaktor in die ontsmetting van water, wat met ’n verskeidenheid skadelike mikro-organismes besmet is, is ook getoets. ‘n Eenvoudinge model is opgestel m.b.v. die kinetiese data, waarna ’n volledige analise met betrekking tot grootskaalse bedryf en ekonomiese uitvoerbaarheid gedoen is. ‘n Vereiste van die studie was om die konsentrasie van die afbreek-produkte van die oksidasie akkuraat vas te stel. As gevolg hiervan is ‘n ho¨e-druk-vloeistofchromatografie analitiese metode verfyn. Die analise het getoon dat die reaktorstelsel nie ekonomies sou wees nie. Een van die hoofredes hiervoor is die onrealistiese reaktorlengtes wat benodig sou word. Resultate het getoon dat die reaksie deur beide massa-oordrag en lading-oordrag be¨ınvloed word. Ho¨e drukvalle in die reaktor wat gelei het tot lae vloeitempo’s was hiervoor verantwoordelik. Die deaktivering van die katalis be¨ınvloed waarskynlik die reaksie, maar die deaktiveringsverskynsel is nie ten volle ondersoek nie. Die reaktorstelsel kan verder verbeter word deur verskeie elemente van die reaktor te ondersoek. Die ontwerp van die vloeikanale in die reaktor is nie ondersoek nie en kan die werksverrigting van die reaktor verhoog. Uit die literatuur is gevind dat die tipe metaaloksied wat as katalis gebruik word, die reaksie direk be¨ınvloed. Dus kan navorsing wat tans op die kataliste gedoen word nuwe kataliste na vore bring wat meer doeltreffend sal wees. Laastens, is die huidige membraan/elektrode samestelling nog oneffektief en kan die reaktor-opstelling dus nog verbeter word. Elke verbetering wat op die bogenoemde faktore van die reaktor ontwerp verkry word, sal die ekomoniese uitvoerbaarheid van die proses be¨ınvloed. So, sal die proses al meer kompeterend met huidige behandelingsmetodes word.
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Lau, Yip Hang. "Maximization of treatment capacity of a full-scale biological nitrogen removal plant through model simulation and full-scale stress test /". View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202005%20LAU.
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Caglia, Stefania. "Nitrogen Removal in the Pilot Plant ITEST (Increased Technology in Sewage Treatment)". Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171846.
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Regions with a cold winter, as in the Baltic countries, have a problem to meet the nitrogen requirement in the Urban Wastewater Treatment Directive 98/15/EC. Especially in the winter season, the temperature of the influent wastewater could arrive also below 10°C and this delays the biological processes that takes place in the wastewater treatment. With the decrease of the temperature, the efficiency of nitrogen removal in the system decreases and leads to a high nitrogen loading in the effluent. The ITEST (Increased Technology and Efficiency in Sewage Treatment) project situated in Hammarby Sjöstadsverk in Stockholm has as its main aim to enhance nitrogen removal, thereby increasing the temperature in the incoming wastewater. The pilot plant ITEST is comprised of two treatment lines, one works with natural temperature influent and the other works at the temperature of 20 °C. In order to warm the incoming water a heating system, using waste heat, is used, leading to save energy. The two test lines were compared analyzing different parameters from January to May 2013. Total nitrogen, nitrate-nitrogen and ammonium-nitrogen concentrations were measured in the incoming water and in the effluent from the two treatment lines. Hence, the efficiency of the nitrogen removal was compared between the reference and the temperature line. In the period where the system was well functioning, the results show a nitrogen efficiency with a maximum of 92 % of removal of total nitrogen for the temperature line compared to only 65 % for the reference line. In the period where the system did not have any troubles the total nitrogen is under 10 mg/l, which is the limit of total nitrogen discharges specified in the Directive. Instead, for the sludge volume and the suspended solids any particular difference can be noticed from the two lines of treatment. In conclusion, in the temperature line can be noticed a great efficiency in nitrogen removal compared to the reference line.
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Pokethitiyook, Prayad. "Nitrate utilization as the final electron acceptor in a biological phosphorus removal system". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040836/.
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Cameron, Kimberley A. "The efficiency and mechanisms for pollutant removal in biological wastewater treatment systems /". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33724.
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The research project was initiated to refine the knowledge available on the treatment of rural municipal wastewater by constructed wetlands. Field and laboratory studies were conducted to determine the treatment capacity of a constructed wetland system and to determine a substrate that would be most efficient as a phosphorus adsorption filter. The wetland system consisted of three free-water surface cells, three blast furnace slag filters and a vegetated filter strip, treating municipal wastewater. Bimonthly water samples at the inlet and outlet of each component of the wetland system were analysed for biochemical oxygen demand, nitrate and nitrite, ammonia and ammonium, total Kjeldahl nitrogen, total suspended solids, total phosphorus, ortho-phosphate, fecal coliforms and E. coli. Phosphorus and nitrogen concentrations were determined in the sediment, plant tissue and water column of the free-surface wetland cells. The free-surface wetland cells achieved removals as follows: ammonia and ammonium (52%), total Kjeldahl nitrogen (37%), total suspended solids (93%), total phosphorus (90%) and ortho-phosphate (82%). The vegetated filter strip achieved removals as follows: ammonia and ammonium (28%), total Kjeldahl nitrogen (11%), total suspended solids (22%), total phosphorus (5%) and ortho-phosphate (0%). The slag filters reduced total phosphorus by more than 99%. Phosphorus adsorption measurements were conducted on slag, calcite and shale. Slag was found to be the most effective at removing phosphate.
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Pattarkine, Vikram Madhao. "The role of metals in enhanced biological phosphorus removal from wastewater". Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08082007-120247/.
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Scott, Daniel. "Biological Nitrogen Removal in a Gravity Flow Biomass Concentrator Reactor". University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1298323356.
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McClintock, Samuel Alan. "Effects of temperature and mean cell residence time on the performance of high-rate biological nutrient removal processes". Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-08252008-162825/.
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Beard, Kelly Marie. "Role of oxidants in the removal of iron and organics from Harwood's Mill Reservoir". Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/104292.
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Lee, Samuel H. "The influence of nitrogen and sludge age change in reactor performance and biopolymer production in activated sludge". Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91041.
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This study investigated the influence of nitrogen and sludge age change in reactor performance and biopolymer production in activated sludge systems. The qualitative and quantitative analyses of the naturally occurring biopolymers were performed and the results were correlated to sludge a settling characteristic and effluent quality.
In order to obtain the sludge samples for the analyses, two completely mixed, continuous flow activated sludge systems were maintained during this research. Raw wastewater from the Celanese Fiber Plant located at Narrows, Virginia was utilized as the influent. Nitrogen was added in the feed solution as ammonium sulfate. The sludge age was changed from ten to five days for both systems.
Biopolymers were extracted from the sludge floc matrix using pH-adjustment technique followed by centrifugation. The total biopolymer contents were analyzed for protein and carbohydrate concentrations. High molecular weight biopolymers were also analyzed following gel filtration. The sludge settling characteristics were measured in terms of Sludge Volume Index and effluent quality in terms of effluent turbidity.
The results indicated that the relationship between total biopolymer concentrations and sludge settling characteristics is culture specific. No consistent relationship was observed between total biopolymer concentrations and effluent turbidity and/or SVI.
Additional nitrogen in a reactor system promoted production of high protein content biopolymers. However, no significant improvement in effluent quality of the reactor was noticed by the additional nitrogen. Deficiency of nitrogen in a reactor system promoted the production of high carbohydrate content biopolymers. The high concentration of carbohydrate biopolymers seemed to correspond directly to the high effluent turbidity.M.S.
46
Hughes, Leonie. "Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures". Thesis, Hughes, Leonie ORCID: 0000-0001-6496-988X (2008) Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures. PhD thesis, Murdoch University, 2008. https://researchrepository.murdoch.edu.au/id/eprint/674/.
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Nitrogen removal from wastewater is important for the revention of significant health and environmental impacts such as eutrophication. Nitrogen removal is achieved by the combined action of nitrification and denitrification. Nitrification is performed by autotrophic, slow growing microorganisms that require oxygen and are inhibited in the presence of denitrifiers when oxygen and COD are available due to competition for oxygen. Denitrification however, performed by relatively fast growing heterotrophic bacteria, is inhibited by oxygen and requires COD. This implies that nitrification and denitrification are mutually exclusive. The supply of oxygen to a fresh wastewater, high in ammonia and COD, causes waste of both oxygen and COD. Conservation of COD is therefore critical to efficient wastewater treatment. The approach investigated in this study to achieve complete nitrogen removal was to physically separate the nitrification and denitrification biomasses into separate bioreactors, supplying each with appropriate conditions for growth and activity.
A storage driven denitrification sequencing batch biofilm reactor (SDDR) was established which exhibited a high level of COD storage (up to 80% of influent COD) as poly-B-hydroxybutyrate capable of removing >99% of nitrogen from wastewaters with a C/N ratio of 4.7 kg COD/kg N–NO3 –. The SDDR was combined in sequential operation with a nitrification reactor to achieve complete nitrogen removal. The multiple stage, multiple biomass reactor was operated in sequence, with Phase 1 - COD storage in the storage driven denitrification biofilm; Phase 2 - ammonia oxidation in the nitrification reactor; and Phase 3 - nitrate reduction using the stored COD in the storage driven denitrification reactor. The overall rate of nitrogen removal observed was up to 1.1 mmole NH3 L–1 h–1 and >99% of nitrogen could be removed from wastewaters with a low C/N ratio of 3.9 kg COD/kg N–NH3.
The multiple stage, multiple biomass system was limited in overall nitrogen removal the reduction in pH caused by nitrification. A parallel nitrification-denitrificatio (PND) reactor was developed in response to the pH control issue. The PND reactor was operated with Phase 1 – COD storage in the storage driven denitrification biofilm and Phase 2 – simultaneous circulation of reactor liquor between the denitrification and nitrification biofilms to achieve complete nitrogen removal and transfer of protons. The PND reactor performed competitively with the multistage reactor (removal of >99% nitrogen from wastewaters with feed ratios of 3.4 kg COD/kg N–NH3) without the need for addition of buffering material to oderate the pH.
47
Hughes, Leonie. "Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures". Hughes, Leonie (2008) Multistage and multiple biomass approaches to efficient biological nitrogen removal using biofilm cultures. PhD thesis, Murdoch University, 2008. http://researchrepository.murdoch.edu.au/674/.
Pełny tekst źródłaStreszczenie:
Nitrogen removal from wastewater is important for the revention of significant health and environmental impacts such as eutrophication. Nitrogen removal is achieved by the combined action of nitrification and denitrification. Nitrification is performed by autotrophic, slow growing microorganisms that require oxygen and are inhibited in the presence of denitrifiers when oxygen and COD are available due to competition for oxygen. Denitrification however, performed by relatively fast growing heterotrophic bacteria, is inhibited by oxygen and requires COD. This implies that nitrification and denitrification are mutually exclusive. The supply of oxygen to a fresh wastewater, high in ammonia and COD, causes waste of both oxygen and COD. Conservation of COD is therefore critical to efficient wastewater treatment. The approach investigated in this study to achieve complete nitrogen removal was to physically separate the nitrification and denitrification biomasses into separate bioreactors, supplying each with appropriate conditions for growth and activity.
A storage driven denitrification sequencing batch biofilm reactor (SDDR) was established which exhibited a high level of COD storage (up to 80% of influent COD) as poly-B-hydroxybutyrate capable of removing >99% of nitrogen from wastewaters with a C/N ratio of 4.7 kg COD/kg N–NO3 –. The SDDR was combined in sequential operation with a nitrification reactor to achieve complete nitrogen removal. The multiple stage, multiple biomass reactor was operated in sequence, with Phase 1 - COD storage in the storage driven denitrification biofilm; Phase 2 - ammonia oxidation in the nitrification reactor; and Phase 3 - nitrate reduction using the stored COD in the storage driven denitrification reactor. The overall rate of nitrogen removal observed was up to 1.1 mmole NH3 L–1 h–1 and >99% of nitrogen could be removed from wastewaters with a low C/N ratio of 3.9 kg COD/kg N–NH3.
The multiple stage, multiple biomass system was limited in overall nitrogen removal the reduction in pH caused by nitrification. A parallel nitrification-denitrificatio (PND) reactor was developed in response to the pH control issue. The PND reactor was operated with Phase 1 – COD storage in the storage driven denitrification biofilm and Phase 2 – simultaneous circulation of reactor liquor between the denitrification and nitrification biofilms to achieve complete nitrogen removal and transfer of protons. The PND reactor performed competitively with the multistage reactor (removal of >99% nitrogen from wastewaters with feed ratios of 3.4 kg COD/kg N–NH3) without the need for addition of buffering material to oderate the pH.
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Ashworth, Robert Frederick. "The factors determining nitrogen removal from sewage using a gravel bed hydroponic treatment system". Thesis, University of Portsmouth, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305673.
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Hart, Vincent S. "An examination of biological phosphorus removal using bacterial counting and poly-β-hydroxybutyrate analysis in batch and continuous flow systems". Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/40652.
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The objective of this study was to examine excess biological phosphorus removing bacterial populations and their substrate utilization mechanisms. This study was a smaller part of a overall study of temperature effects upon excess biological phosphorus removal.
Bacterial populations in both a continuous flow UCT (University of Cape Town) system and batch reactors were examined by direct counting using a well known staining procedure (Neisser staining), and a microscopic counting method developed by Cech and Hartman (1993). Substrate utilization was examined using PHB (Poly-β -Hydroxybutyrate - an internal substrate storage product) analysis by gas chromatography to supplement COD and acetate measurements.
The results showed that Poly-P bacterial counts were significantly greater at a 5 day sludge age compared to a 10 day sludge age. It was noted from microscopic observations that the size of the poly-phosphate granules in the bacteria seemed to be a better indicator of system performance than the actual counts. It also was observed that the 'G' bacteria first described by Cech and Hartman (1993) were abundant at the 10 day sludge age but completely absent at the 5 day sludge age.
PHB storage occurred in both the anaerobic zone and the first aerobic tank, and PHB utilization was seen in the subsequent aerobic tanks of the UCT system. The formation of PHB in the first aerobic reactor when no substrate was available supports the Mino (1987) model for excess biological phosphorus removal.
In batch studies, substrate storage release were demonstrated in the aerobic zone. This explained why when acetate was present in the aerobic zone net phosphorus uptake didn't occur until all the acetate was utilized.
When the temperature was lowered in the UCT system nitrification ceased. This resulted in soluble COD breakthrough into the aerobic zone, which stimulated filamentous growth, and eventually caused a lack of PHB formation. All of these factors contributed to a loss of excess biological phosphorus removal at the low temperature.Master of Science
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Abu-Ghararah, Ziad. "The effect of influent organic compounds on the performance of biological nutrient removal systems". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/77907.
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The main objective of the research was to investigate the effect of influent organic compounds on the performance of biological nutrient removal system. To carry out the investigation, a pilot plant system was designed and constructed. The system was operated as a UCT process at an influent flow rate of 0.15 liters/minute and a sludge age of 13 days. The influent wastewater was domestic sewage. Excess biological phosphorus removal and steady-state conditions were established before making experimental measurements, or adding supplemental substrate. The effects of separate addition of formic, acetic, propionic, butyric, isobutyric, valeric, and isovaleric acid, plus glucose, addition on phosphorus release under anaerobic conditions, and phosphorus uptake under aerobic conditions, were studied. The effects of the organic acid additions on the removal of nitrogen and COD, and changes in SOUR, MLVSS, and metals such as iron, magnesium, calcium and potassium, were also studied. In all experiments, the specific substrate was added continuously to the first anaerobic reactor for three days at an influent concentration of 100 mg COD/liter. Samples were collected from each reactor at the end of the addition period and analyzed for orthophosphate, nitrate, nitrite, sulfate, volatile fatty acids, COD, MLVSS, pH and metals. All added substrates, except formic acid and dextrose, caused significant increases in phosphorus release in the anaerobic stage, and phosphorus uptake, in the aerobic stage, and consequently, an increase in phosphorus removal efficiency. The molar ratios of phosphorus release to volatile fatty acid added obtained for propionic acid, acetic acid, butyric acid, and valeric acid were 0.44, 0.77, 0.78, and 1.72 respectively. However, on a COD basis, the greatest ratios of mg phosphorus released to mg COD utilized was produced by the addition of acetic acid (0.37) and valeric acid (0.19). It was also found that the branched organic acids, isobutyric and isovaleric, caused more phosphorus release in the anaerobic stage and better phosphorus removal efficiencies as compared with the nonbranching forms of the same organic acids. The molar ratios of phosphorus release for these two acids were 0.8 and 2.3, respectively, and on a COD basis were 0.16 and 0.25. For engineering applications, it is suggested by this research that at least 20 mg COD equivalent of acetic acid is needed for the removal of I mg phosphorus. The results obtained by this investigation were consistent with the hypothesis proposed by Marais et al., 1983. The most recent biochemical models, proposed by Comeau et al., 1986 and Wentzel et al., 1986, were also tested using the data collected in the present investigation. Both models, in most cases, overestimated the ratios of phosphorus release to volatile fatty acid utilized. A speculative model for anaerobic metabolism by poly-p bacteria of volatile fatty acids which contain both odd and even numbers of carbon atoms was proposed.
All added substrates produced no effect on both COD and TKN removals. Metal releases were found to correlate with the amount of phosphorus release.Ph. D.