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A study on the functions of volatile fatty acids and ph on enhanced biological phospate removalLiu, Yan Hua 01 April 2001 (has links)
No description available.
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The effects of a reduced cycle duration in enhanced biological phosphorus removal sequencing batch reactorsCruz Lasso de la Vega, Rodrigo Melchor 01 January 2004 (has links)
No description available.
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Substrate stabilization in the anaerobic stage of a biological phosphorus removal systemBrannan, Kenneth P. January 1986 (has links)
Ph. D. / incomplete_metadata
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The effect of influent organic compounds on the performance of biological nutrient removal systemsAbu-Ghararah, Ziad January 1988 (has links)
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.
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Optimization of BNR from wastewater using SBR and A²O processesGuo, Lei January 2011 (has links)
University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering
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Municipal wastewater characterization : application of denitrification batch tests.Naidoo, Valerie. January 1999 (has links)
The biological treatment of wastewater has evolved significantly from simple single sludge systems
practicing organic carbon removal to ones which now include either nitrification/denitrification (N/DN)
and / or phosphorus (P) removal. The inclusion of more biological processes have increased the
complexity of current wastewater systems which has subsequently led to the development of more
complex mathematical models. The operation of plants can be assessed and improved by the use of
mathematical modelling tools which require accurate input data. Thus, knowledge of the wastewater
characteristics is an important step towards the optimum modelling, design and operation of present and
future plants. However, for these tools to be effective, the input data needs to be accurate which is
dependent on the current methods used to determine them.
Wastewater is a complex substrate consisting of compounds of differing biodegradability. Biokinetically,
these compounds have been divided into readily biodegradable (RBCOD), slowly biodegradable
(SBCOD) and unbiodegradable substrate groups. Compounds with intermediate biodegradability i.e.
compounds which fall between the RBCOD and SBCOD groups, have been termed readily hydrolyzable
organic substrates (RHCOD). The organic matter is discussed in terms of chemical oxygen demand
(COD). The readily biodegradable and readily hydrolyzable COD fractions of wastewater can be
determined by respirometric tests such as the oxygen utilization rate (OUR) and nitrate-N utilization rate
(NUR) tests.
The principal aim of this project was to investigate the NUR test as a tool for wastewater characterization
and to study denitrification kinetics in batch reactors. In addition, an experimental readily biodegradable
substrate, acetate, was used to determine the reliability of the NUR tests. Acetate was also used to
ascertain utilization profiles and rates of a typical readily biodegradable substrate during denitrification.
Biodegradable COD characterizations with enhanced biological phosphorus removal (EBPR) sludges
were also investigated to determine the impact of anoxic phosphorus removal on NUR tests. The results
obtained from the numerous NUR tests added to the undestanding of the NUR test.
Samples from 22 wastewater treatment plants were tested, most of which were located in France. Four
South African plants were also tested. Data obtained from the NUR tests were used to calculate the
RBCOD and RHCOD fractions. The SBCOD, however, could not be determined directly from the 6 h
NUR batch tests. The readily biodegradable COD (RBCOD) fractions ranged between 7 and 25 % of the
total COD concentration of raw wastewater, with majority of those results falling within the 10-20 % (of
the total COD) range. The results also showed that the initial rapid rate associated with readily
biodegradable COD utilization was sometimes followed by a short intermediate phase (i.e. short duration,
2 to 3 h). The intermediate fraction was found to range between 5 and 29 % of the total COD
concentration and was classed as a readily hydrolyzable COD component of raw wastewater since the
magnitude of the RHCOD fraction was too small to be classed as slowly biodegradable COD which
comprises approximately 30 to 60 % of the total COD found in raw wastewaters. The variability of the
RHCOD fractions suggests that this fraction is either very variable or that the NUR test does adequately
or accurately characterize it. Another possibility is that the RHCOD (or second biodegradable fraction)
calculated from the NUR test is a component of the RBCOD of the influent wastewater. In this case, the
bacteria may have used some of the RBCOD directly for energy and accumulated or stored the rest as
part of a survival mechanism which allows them to be more competitive under dynamic operating
conditions. Once the readily biodegradable COD becomes limiting, the bacteria will use the accumulated
or stored compounds. This hypothesis is substantiated by tests done with acetate as substrate.
An intermediate phase was also observed when acetate was the sole substrate. Thus, it was possible with
the 3-phase profiles to calculate a second biodegradable fraction. Results suggest that a significant part of
the added acetate (as COD) was stored and the second phase is in fact an 'apparent or residual' phase
brought about by the consumption of the stored or accumulated acetate products. This is suggested in two
ways: (1) the calculation of the yield coefficient is lower and closer to the 0.5 mg/l values, cited in the
literature, when the COD calculated from phases 1 and 2 are considered, and (2) the acetate mass
balances were found to be approximately 100 % when phases 1 and 2 were used to calculate the amount
of acetate utilized under anoxic conditions.
The results obtained with sodium acetate as a readily biodegradable substrate were used to formulate
several conclusions on acetate utilization during denitrification. Firstly, from acetate mass balances it was
found that acetate may be used exclusively for denitrification (100 % acetate was accounted for). In this
case, the sludge contains a significant proportion of denitrifiers and little or no polyphosphate
accumulating organisms. This observation was made only when non-EBPR (enhanced biological
phosphorus removal) sludges were used. Secondly, acetate mass balances which were found to be < 100
% suggest that acetate could be used for denitrification and the production of storage products like
polyhydroxyalkanoates (PHA's). These sludges probably contained a higher proportion of polyphosphate
accumulating organisms which competed for the available acetate in the bulk liquid. This observation
was made for both EBPR and non-EBPR sludges. Thirdly, acetate could be used for denitrification by
denitrifiers and for polyhydroxyalkanoate synthesis by denitrifying polyphosphate accumulating
organisms. The stored PHA's in the denitrifying polyphosphate accumulating organisms are subsequently
utilized during denitrification. This secondary utilization is manifested in the second denitrification phase
and is supported by the observation of phosphorus uptake. These results showed that wastewaters high in
volatile fatty acids (VFA's) were also subject to denitrifying polyphosphate accumulating organism
activity even though the sludge was sampled from non enhanced biological phosphorus removal systems
(non EBPR).
Several of the NOx profiles revealed either 2 or 3 rates due to the control of the substrate to biomass ratio
(S/X: :<_0.1 mgO2 / mgO2). Majority of the samples (i.e. 85%) tested produced initial maximum specific
denitrification rates (k1) between 3 and 6 mgN/gVSS.h. The intermediate denitrification rate (k2) was
found to vary between 2 and 3 mgN/gVSS.h. Denitrification rates (k3) obtained from utilization of
influent and. endogenous slowly biodegradable COD (SBCOD) varied between 1.0 and 1.5 mgN/gVSS.h.
This latter rate is significantly higher than the endogenous denitrification rates cited in the literature. One
of the reasons for these higher rates could be be linked to the the reuse of stored or accumulated products
by the microorganisms.
In addition, a comparative study on RBCOD determination of wastewaters with enhanced biological
phosphorus removal and non-EBPR sludges. It was found that the RBCOD values derived by NUR tests
with EBPR sludge were consistently lower (4 to 5 %) than those with non-EBPR sludge. Thus, the NUR
tests with EBPR sludge resulted in a 4 to 5 % underestimation of the RBCOD fraction of raw
wastewaters. This loss in RBCOD to polyphosphate accumulating organisms appears to be linked to the
influent raw wastewater acetate concentration.
These tests showed that the RBCOD fraction could be adequately characterized using the NUR method.
The accuracy of the tests appears to be compromised when enhanced biological phosphorus removal
sludges are used in the NUR tests. Moreover, it was found that non-EBPR sludges can also consume
some of the acetate that is present in the system for the production and replenishment of storage
compounds. Fortunately, for the wastewaters tested, the acetate component of the RBCOD fraction was
small and therefore, did not significantly affect the results. Mechanisms such as substrate accumulation
and storage may also impact on substrate removal and hence, the determination of the readily
biodegradable COD concentration of municipal wastewaters. Thus, while the results showed that the
NUR is a useful characterization tool for wastewaters, it will continue to be a more tedious
characterization tool than the oxygen utilization rate test, until a suitable nitrate/nitrite electrode is
developed to automate the test. / Thesis (Ph.D.)-University of Natal, Durban, 1999.
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The effects of a phosphate detergent ban on a biological nutrient removal plant and anaerobic digesterRandall, William O. 12 March 2009 (has links)
This study investigated the effects of the detergent phosphorus ban implemented on January 1, 1988 in Virginia, on the treatment streams of the York River Wastewater Treatment Plant, a biological nutrient removal (BNR) system. Evaluation of the available historical data indicated that the influent phosphorus load entering the plant in the post-ban period had decreased 27% compared to the pre-ban period. The influent phosphorus concentration had decreased 29% from the pre- to the post-ban period. No definitive conclusion could be reached concerning the effects of the influent phosphorus decrease on the treatment efficiency due to operational changes which occurred at the time of the ban implementation. The combination of operational changes and the phosphorus ban resulted in 54% and 59% decreases in the effluent phosphorus load and concentration, respectively.
Measurements and modelling of the anaerobic digester contents indicated that several minor changes had occurred in the digester which may be attributable to the phosphorus ban, but the equilibria of the digester regarding phosphorus compounds had not been dramatically altered. This was primarily due to improved operation of the clarifiers and sludge thickeners, which delivered Similar phosphorus loads to the digester in the pre- and post-ban periods. / Master of Science
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Remoção de matéria carbonácea, nitrogenada e fosfatada em um sistema anaeróbio-aeróbio-anóxico (AOA) submetido a variações de cargas orgânicas e hidráulicas / Carbon, nitrogen and phosphorus removal of anaerobic-aerobic-anoxic system (AOA) submitted to variation of organic and hydraulic loadsFerro, Thayse Nathalie 02 March 2018 (has links)
Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / No 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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