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Klaus, Stephanie Anne. "Intensification of Biological Nutrient Removal Processes." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/103073.
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Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure.
At the beginning of this study, granular sidestream deammonification was becoming well-established in Europe, but there was virtually no experience with startup or operation of these processes in North America. The experience gained from optimization of the sidestream deammonification moving bed biofilm reactor (MBBR) in this study, including the novel pH-based aeration control strategy, has influenced the startup procedure and operation of subsequent full-scale installations in the United States and around the world.
Long startup time remains a barrier to the implementation of sidestream deammonification processes, but this study was the first to show the benefits of utilizing media with an existing nitrifying biofilm to speed up anammox bacteria colonization. Utilizing media with an established biofilm from a mature integrated fixed film activated sludge (IFAS) process resulted in at least five times greater anammox activity rates in one month than virgin media without a preliminary biofilm. This concept has not been testing yet in a full-scale startup, but has the potential to drastically reduce startup time.
False dissolved oxygen readings were observed in batch scale denitrification tests, and it was determined that nitric oxide was interfering with optical DO sensors, a problem of which the sensor manufacturers were not aware. This led to at least one sensor manufacturer reevaluating their sensor design and several laboratories and full-scale process installations were able to understand their observed false DO readings.
There is an industry-wide trend to utilize influent carbon more efficiently and realize the benefits of mainstream shortcut nitrogen removal. The A/B pilot at the HRSD Chesapeake Elizabeth Treatment provides a unique chance to study these strategies in a continuous flow system with real wastewater. For the first time, it was demonstrated that the presence of influent particulate COD can lead to higher competition for nitrite by heterotrophic denitrifying bacteria, resulting in nitrite oxidizing bacteria (NOB) out-selection. TIN removal was affected by both the type and amount of influent COD, with particulate COD (pCOD) having a stronger influence than soluble COD (sCOD). Based on these findings, an innovative approach to achieving energy efficient biological nitrogen removal was suggested, in which influent carbon fractions are tailored to control specific ammonia and nitrite oxidation rates and thereby achieve energy efficiency in the nitrogen removal goals downstream.
Intermittent and continuous aeration strategies were explored for more conventional BNR processes. The effect of influent carbon fractionation on TIN removal was again considered, this time in the context of simultaneous nitrification/denitrification during continuous aeration. It was concluded that intermittent aeration was able to achieve equal or higher TIN removal than continuous aeration at shorter SRTs, whether or not the goal is nitrite shunt. It is sometimes assumed that converting to continuous aeration ammonia-based aeration control (ABAC) or ammonia vs. NOx (AvN) control will result in an additional nitrogen removal simply by reducing the DO setpoint resulting in simultaneous nitrification/denitrification (SND). This work demonstrated that lower DO did not always improve TIN removal and most importantly that aeration control alone cannot guarantee SND. It was concluded that although lower DO is necessary to achieve SND, there also needs to be sufficient carbon available for denitrification.
While the implementation of full-scale sidestream anammox happened rather quickly, the implementation of anammox in the mainstream has not followed, without any known full-scale implementations. This is almost certainly because maintaining reliable mainstream NOB out-selection seems to be an insurmountable obstacle to full-scale implementation. Partial denitrification/anammox was proven to be easier to maintain than partial nitritation/anammox and still provides significant aeration and carbon savings compared to traditional nitrification/denitrification. There is a long-standing interest in combining shortcut nitrogen removal with biological phosphorus removal, without much success. In this study, biological phosphorus removal was achieved in an A/B process with A-stage WAS fermentation and shortcut nitrogen removal in B-stage via partial denitrification.Doctor of Philosophy
When the activated sludge process was first implemented at the beginning of the 20th century, the goal was mainly oxygen demand reduction. In the past few decades, treatment goals have expanded to include nutrient (nitrogen and phosphorus) removal, in response to regulations protecting receiving bodies of water. The only practical way to remove nitrogen in municipal wastewater is via biological treatment, utilizing bacteria, and sometimes archaea, to convert the influent ammonium to dinitrogen gas. Orthophosphate on the other hand can either be removed via chemical precipitation using metal salts or by conversion to and storage of polyphosphate by polyphosphate accumulating organisms (PAO) and then removed in the waste sludge. Nitrification/denitrification and chemical phosphorus removal are well-established practices but utilize more resources than processes without nutrient removal in the form of chemical addition (alkalinity for nitrification, external carbon for denitrification, and metal salts for chemical phosphorus removal), increased reactor volume, and increased aeration energy. Intensification refers to utilizing wastewater treatment processes that decrease chemical and energy demands, increase energy recovery, and reduce the process footprint (or increased capacity in an existing footprint) all while providing the same level of nutrient removal as traditional methods. Shortcut nitrogen removal processes; including nitrite shunt, partial nitritation/anammox, and partial denitrification/anammox, as well as low-carbon biological phosphorus removal, were critically-evaluated in this study with an overall objective of intensification of existing infrastructure. Partial nitritation/anammox is a relatively new technology that has been implemented in many full-scale sidestream processes with high ammonia concentrations, but that has proven difficult in more dilute mainstream conditions due to the difficulty in suppressing nitrite oxidizing bacteria (NOB). Even more challenging is integrating biological phosphorus removal with shortcut nitrogen removal, because biological phosphorus removal requires the readily biodegradable carbon that is diverted. Partial denitrification/anammox provides a viable alternation to partial nitritation/anammox, which may be better suited for integration with biological phosphorus removal.
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Henderson, Courtney Francis Keith. "The Chemical and Biological Mechanisms of Nutrient Removal from Stormwater in Bioretention Systems." Thesis, Griffith University, 2009. http://hdl.handle.net/10072/366977.
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High concentrations of dissolved nutrients in stormwater have been identified as contributing to eutrophication of receiving waterways near urban areas. To reduce dissolved nutrient concentrations in stormwater a range of devices such as wetlands and bioretention systems are used. Bioretention systems are increasingly employed for their supposedly high nutrient removal capacity, however very little is known about their treatment efficiency or the chemical and biological mechanisms controlling their function. This research aimed firstly to test and compare the efficiency of different bioretention system designs for the removal of dissolved nutrients from stormwater, and secondly to investigate the chemical and biological mechanisms responsible for the nutrient removal (sorption, microbial uptake, and plant uptake).
Bioretention mesocosms were built in plastic containers (1 m x 0.5 m x 0.5 m). Three different media treatments were built, representing those most commonly used:
gravel, fine sand and loamy-sand. To assess the nutrient removal capacity of plants, vegetated and unvegetated examples of each media type were made. The mesocosms were regularly irrigated with tap water for six months, and then regularly irrigated with synthetic stormwater for a further six months to ensure that the treatment performance assessed would represent fully established systems. The synthetic stormwater solution was based on field measurements of stormwater, and was made using a combination of inorganic chemicals and organic fertilisers. By incorporating organic carbon and major cations (Ca, Mg, Na, K), the measured treatment performance of the biofilters would be more realistic than previous studies that did not corporate these compounds. Some mesocosms were watered only with tap water so that the effect of frequent fertilisation (enrichment) could be compared. It was expected that vegetated media would enhance nutrient removal directly through plant uptake, and indirectly by stimulating microbial productivity and microbial uptake in the rhizosphere.
Nutrient removal was evaluated by comparing the influent to the effluent. Detention times of 24 and 72 hours were compared to test if longer contact periods resulted in greater nutrient removal. The mesocosms were also flushed with tap water (no nutrients) to determine the proportion of entrained nutrients that might subsequently leach from the media. Vegetated bioretention mesocosms were much more efficient than unvegetated systems at removing total nitrogen (63 – 77 % removal compared to -12 – 25 %) and total phosphorus (85 – 94 % removal compared to 31 – 90 %). The vegetation effect did not improve dissolved organic carbon removal but there was a difference between soil types, with smaller particle size media removing more organic carbon. Enriched mesocosms removed similar quantities of nutrients to non-enriched mesocosms. Extending the detention time from 24 hours to 72 hours slightly increased the removal of total nitrogen from the vegetated mesocosms, but reduced total nitrogen removal from unvegetated mesocosms. When flushed with tap water, inorganic and organic forms of nitrogen and phosphorus leached from the unvegetated mesocosms, but were mostly retained within the vegetated mesocosms...Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Engineering
Science, Environment, Engineering and Technology
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Manyumba, Future. "Biological nutrient removal using a large pilot plant." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434590.
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Hong, Chon Choi. "Effect of chloride on biological nutrient removal from wastewater." Thesis, University of Macau, 2007. http://umaclib3.umac.mo/record=b1636963.
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Moodley, Rajan. "External nitrification in biological nutrient removal activated sludge systems." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/9945.
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Includes bibliography.In conventional nitrification-denitrification biological excess phosphorous removal (NDBEPR) activated sludge systems, such as the UCT system for example, both nitrification and phosphorous uptake (P uptake) occur simultaneously in the, usually large, aerobic reactor. In the UCT system the nitrate load to the anoxic reactor is limited by the a-recycle (i.e. system constraint recycle from the aerobic to the anoxic reactor) and the internal aerobic nitrification performance. The latter process, is mediated by the nitrifiers having a slow growth rate of 0.45/d, governs the sludge age of the biological nutrient removal activated sludge (BNRAS) system and thus results in long (20 - 25 day) sludge ages and large aerobic mass fraction requirements to nitrify completely. However, if stable nitrification could be achieved outside the BNRAS external nitrification (EN) system then nitrification and the suspended solids sludge age become uncoupled allowing greater flexibility into the BNRAS system.
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Sötemann, Sven. "External nitrification in biological nutrient removal activated sludge systems." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/5003.
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Summary in English.Bibliography: leaves 5.1-5.7.
Biological nutrient removal activated sludge (BNRAS) systems have become the preferred treatment system for advanced municipal wastewater treatment in South Africa. They have proven to be cost-effective systems that produce effluents of excellent quality that can be re-introduced to the receiving water bodies without a significant negative impact on the scarce surface water of South Africa. The widespread implementation of the BNRAS system has drawn attention to some of the weaknesses of the system, predominantly (i) the long sludge ages and resulting large biological reactor volumes required for nitrification, (ii) filamentous organism bulking of the sludge that develops in the system, (iii) treatment of the P rich waste sludge from the system and (iv) containment of the large mass of P in the sludge during a failure of the aeration in the system. In order to overcome the first two weaknesses of the system, it is proposed to separate the process of nitrification from the BNRAS mixed liquor and achieve nitrification externally to the BNRAS system.
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Popple, Tina. "The behaviour, fate and removal of pharmaceuticals in biological nutrient removal sewage treatment." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/the-behaviour-fate-and-removal-of-pharmaceuticals-in-biological-nutrient-removal-sewage-treatment(7b67f73d-d777-4a25-9b7b-0ae3edcc58dc).html.
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Pharmaceuticals that are intended for human use are frequently detected in the aquatic environment. This is predominantly from the excretion of pharmaceuticals by patients, in their urine and faeces, which subsequently enter sewage treatment plants. Sewage treatment provides a final opportunity for pharmaceutical removal, prior to discharge into the environment, however, removal is often incomplete. Once in the environment, pharmaceuticals have the potential to cause effects on aquatic organisms. Sewage treatment plants, that are designed to meet statutory discharge consents for nutrients, are increasing in number. These plants, capable of biological nutrient removal, are understudied for the removal efficiencies of pharmaceuticals. This thesis presents research findings on the behaviour, fate and removal of selected pharmaceuticals in a bespoke laboratory rig, and in operational biological nutrient removal sewage treatment plants. Pharmaceuticals possessing a broad range of physical and chemical properties were selected for this research, they included: salicylic acid, caffeine, propranolol, diclofenac and carbamazepine. Sensitive chromatographic methods were developed to quantify the analytes in a laboratory sequencing batch reactor rig and in operational plants. Radiolabelled 14C isotopes of salicylic acid, caffeine, propranolol and diclofenac were dosed into the laboratory rig. The compounds exhibited different behaviours during a simulated sewage treatment process. Salicylic acid and caffeine produced the highest amount of biodegradation, with 25.2% and 14.5% of the radiolabel mineralised to 14CO2 in the rig. However, parent degradation is likely to have been higher, since neither compound could be detected in the effluent by specific chemical analysis. These findings were replicated in the operational sewage treatment plants, with > 97% removal of both pharmaceuticals, in all three plants investigated. Propranolol and diclofenac were less affected by biodegradation processes, and produced 3.7% and 0.2% mineralisation, respectively, in the laboratory rig. Furthermore, 33.8% of the radioactivity associated to 14C propranolol was detected in the rig solids. These compounds showed insignificant removal from two operational plants; 6.8% and 20.9% (propranolol) and -0.9% and -39.4% (diclofenac). Monitoring of operational plants showed that concentrations of propranolol were highest in the activated sludge tanks at all three sites. This supports the findings from the rig, that propranolol interacts with the sludge, which might be more significant in plants with lower sludge wastage rates, such as sequencing batch reactors. This could have implications for the terrestrial environment, and therefore, terrestrial risk assessments should be refined accordingly. Monitoring of the operational sewage treatment plants highlighted the widespread presence, and recalcitrant behaviour, of carbamazepine during biological sewage treatment. Future work should focus on investigating the mechanisms of removal, of this pharmaceutical in the laboratory sequencing batch reactor. This work highlighted the problems biological systems face in effectively removing recalcitrant pharmaceuticals. Advanced wastewater treatment should be considered, if complete removal is desired.
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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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Wong, Chiew Hiet. "Intergrated design of biological nutrient removal systems / by Chiew Hiet Wong." Thesis, The University of Sydney, 2001. https://hdl.handle.net/2123/27929.
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McHarg, Amy Marie. "Optimisation of municipal wastewater biological nutrient removal using computer simulation." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/10479.
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Due to more stringent regulations for secondary municipal wastewater treatment, municipalities are beginning to implement tertiary treatment in their wastewater treatment plants. Tertiary treatment would be the removal of either phosphorous or nitrogen or both from the wastewater before it is discarded from the plant. Biological treatment is becoming an increasingly popular process used to accomplish this extra removal. There are several processes available that will provide acceptable levels of biological nutrient and BOD removal from wastewater. Three well-known processes were considered in this study - the Modified Bardenpho Process, the Modified UCT Process and the A2/O Process. For each of these processes, 2 1evel fractional factorial designs along with least squares analysis were performed in order to determine the optimal operating variables (recycle rates and anaerobic, anoxic and aerobic zone retention times), with respect to the final nitrogen concentration, the final phosphorous concentration and a combination of the final nitrogen and phosphorous concentrations. The analyses were performed at 10°C and 20°C with low, medium and high primary effluent concentrations. Due to the complexity of the processes, lab scale experiments were not feasible. Therefore, a widely accepted calibrated biokinetic model (Activated Sludge Model No 2d) was used in a computer simulation program (GPS-X) to gather the necessary data for analysis. Actual plant data were used to test the validity of the simulation model with respect to organic and nitrogen removal. Using the published kinetic and stoichiometric parameters for both temperature levels, the Activated Sludge Model provided a good estimation of outlet concentration levels. It was found that all three biological nutrient removal (BNR) process were capable of achieving an effluent soluble phosphorous concentration below the required limit of 1 mgP/L at 10 and 20°C with low, medium and high primary effluent concentration when the effluent nitrogen concentration was neglected. Neither the Modified Bardenpho, the Modified UCT nor the A 2/O process were capable of producing an effluent with nitrogen concentrations below the required limit of 5 mgN/L at high primary effluent concentrations. The Modified Bardenpho and the Modified UCT processes were both successful in achieving a combined nitrogen and phosphorous removal below their regulatory limits for low primary effluent concentrations at 10 and 20°C. The Modified Bardenpho process, at 20°C with medium primary effluent concentrations, was found to achieve an effluent with nitrogen and phosphorous concentrations below 5 mgN/L and 1 mgP/L, respectively. After analyzing the effects of individual operating variables, it was found that the anoxic recycle for the Modified UCT process had an insignificant effect on total nitrogen (TN) and soluble phosphorous (sP) removals and did not need to be included in future experimental studies. All of the input variables to the MB and A2/O process proved to be somewhat significant and it is recommended that they be kept within future experimental designs. From this study it was found that both the MB and MUCT process are capable of achieving the TN, sP and cBOD5 removals that ROPEC requires. However only the MB process proved to be a robust system when subjected to storm conditions (i.e., peaks in influent flow rate) with respect to sP and cBOD5 removal. Neither the MB nor the MUCT process provided acceptable TN removals when subjected to storm conditions. It is recommended that ROPEC further evaluate the MB process as a possible means to achieve simultaneous cBOD5, TN and sP removal.
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凌偉忠 and 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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Kavanaugh, Rathi G. "Investigation of bacterial populations in a biological nutrient removal system." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39828.
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Bacterial populations proliferating in a pilot scale biological nutrient removal system (BNR) were studied. The objective of the research was to develop media and methods to identify bacterial populations in BNR systems. Samples were obtained from the last aerobic zone of a University of Cape Town (UCT)-type system. The most probable numbers (MPN) of bacteria in the samples were analyzed in liquid media containing volatile fatty acids as sole sources of carbon. Samples were also transferred to denitrification medium, and MPN's of denitrifiers were recorded. The growth in liquid medium was plated on solid medium. Gram-negative cultures were isolated and identified. The phosphorus-removal capacity of five isolates also was studied.
The results indicated that several different genera of bacteria are involved in the removal of phosphorus in an operating BNR system. Four major groups of phosphorus storing bacteria, Aeromonas/Vibrio, coliforms, Pseudomonas spp and Acinetobacter spp, were recovered. The identification of cultures on denitrification medium also recovered Pseudomonas, Aeromonas, coliforms and Acinetobacter, indicating the overlap in the function of these genera. The phosphorus accumulations in three of the tested cultures showed accumulations in excess of 10 percent.
The MPN's of bacteria in acetate and propionate media obtained using samples from the pilot scale BNR system and a full scale activated sludge system were statistically analyzed. The analyses showed significant differences between MPN in acetate and propionate medium using samples from the BNR system, whereas there were no significant differences in samples from the conventional activated sludge plant. The possibility of the application of these data in process control and modeling is proposed.Ph. D.
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Jensen, Keith R. "Effects of Integrated Fixed Film Activated Sludge on nitrogen removal in biological nutrient removal systems." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01312009-063219/.
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Coma, Bech Marta. "Biological nutrient removal in SBR technology: from floccular to granular sludge." Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/32025.
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Biological nutrient removal has been studied and applied for decades in order to remove nitrogen and phosphorus from wastewater. However, more anthropogenic uses and the continued demand for water have forced the facilities to operate at their maximum capacity. Therefore, the goal of this thesis is to obtain more compact systems for nutrient removal from domestic wastewater. In this sense, optimization and long-term stabilization of high volume exchange ratios reactors, treating higher volumes of wastewater, have been investigated. With the same target, aerobic granular sludge was proposed as a reliable alternative to reduce space and increase loading rates in treatment plants. However, the low organic loading rate from low-strength influents (less than 1 Kg COD•m-3d-1) results in slower granular formation and a longer time to reach a steady state. Because of that, different methodologies and operational conditions were investigated in order to enhance granulation and nutrient removal from domestic wastewater.L’estudi de l’eliminació biològica de nutrients s’ha dut a terme durant dècades. Tot i això, la influencia de l’home i l’augment de la demanda d’aigua han forçat a les instal•lacions a treballar a la seva capacitat màxima. Així, l’objectiu de la tesi és obtenir sistemes més compactes per a l’eliminació de nutrients de les aigües residuals. En aquest sentit, s’ha investigat l’optimització i estabilització de reactors amb alts volums d’intercanvi, tractant més aigua. Amb el mateix objectiu, el fang granular aeròbic va ser proposat com una alternativa fiable per tal de reduir l’espai i incrementar les càrregues de les depuradores. Tot i això, la granulació amb influents de baixa càrrega (menors a 1 Kg dQO•m-3d-1) resulta més lenta i més dificultosa alhora d’obtenir l’estat estacionari. Per aquesta raó es van investigar diferents metodologies i condicions d’operació per tal de millorar la granularció i l’eliminació de nutrients de les aigües urbanes.
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Ling, Wai-chung Jackson. "Biological nutrient removal in sequencing batch reactors using fibrous packing medium /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17489477.
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McCue, Terrence. "EVALUATION OF PREFERMENTATION AS A UNIT PROCESS UPON BIOLOGICAL NUTRIENT REMOVAL INCLUDING BIOKINETIC AND WASTEWATER PARAMETERS." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3031.
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The objective of this dissertation was to provide a controlled comparison of identical continuous flow BNR processes both with and without prefermentation in order to provide a stronger, more quantitative, technical basis for design engineers to evaluate the potential benefits of prefermentation to EBPR in treating domestic wastewater. In addition, the even less understood effect of prefermentation on denitrification kinetics and anoxic phosphorus (P) uptake was studied and quantified. Other aspects of BNR performance, which might change due to use of prefermentation, will also be addressed, including anaerobic stabilization. Potential benefits to BNR processes derived from prefermentation are compared and contrasted with the more well-known benefits of primary clarification. Finally, some biokinetic parameters necessary to successfully model both the activated sludge systems and the prefermenter were determined and compared for the prefermented versus the non-prefermented system. Important findings developed during the course of this dissertation regarding the impact of prefermentation upon the performance of activated sludge treatment systems are summarized below: • For a septic COD-limited (TCOD:TP < 40:1) wastewater, prefermentation was found to enhance EPBR by 27.7% at a statistical significance level of alpha=0.05 (95% confidence level). • For septic P-limited (TCOD:TP > 40:1) wastewaters, prefermentation was not found to improve EBPR at a statistical significance level of alpha=0.05 (95% confidence level). • The increased anaerobic P release and aerobic P uptakes due to prefermentation correlated with greater PHA formation and glycogen consumption during anaerobiosis of prefermented influent. • Improvements in biological P removal of septic, non-P limited wastewater occurred even when all additional VFA production exceeded VFA requirements using typical design criteria (e.g. 6 g VFA per 1 g P removal). • Prefermentation increased RBCOD content by an average of 28.8% and VFA content by an average of 18.8%, even for a septic domestic wastewater. • Prefermentation increased specific anoxic denitrification rates for both COD-limited (14.6%) and P-limited (5.4%) influent wastewaters. This increase was statistically significant at alpha=0.05 for COD-limited wastewater, but not for P-limited wastewater.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering
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Copp, John B. "COD balances in biological nutrient (nitrogen and phosphorus) removal activated sludge systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0022/NQ50987.pdf.
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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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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.
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Puig, Broch Sebastià. "Operation and control of SBR processes for enhanced biological nutrient removal from wastewater." Doctoral thesis, Universitat de Girona, 2008. http://hdl.handle.net/10803/7798.
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In the last decades, the awareness of environmental issues has increased in society considerably. There is an increasing need to improve the effluent quality of domestic wastewater treatment processes. This thesis describes the application of the Sequencing Batch Reactor (SBR) technology for Biological Nutrient Removal (BNR) from the wastewater. In particular, the work presented evolves from the nitrogen removal to the biological nutrient removal (i.e. nitrogen plus phosphorous removal) with special attention to the operational strategy design, the identification of possible reactor cycle controls or the influent composition related to the process efficiency. In such sense, also the use of ethanol as an external carbon (when low influent Carbon:Phosphorus (C:P) or Carbon:Nitrogen (C:N) ratios are presented) are studied as an alternative to maintain the BNR efficiency.
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Punrattanasin, Warangkana. "Investigation of the Effects of COD/TP Ratio on the Performance of a Biological Nutrient Removal System." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36819.
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The laboratory-scale University of Cape Town (UCT) process was designed to investigate the effects of changing COD/TP ratios on the performance of biological nutrient removal (BNR) processes. Specific objectives of the research were to investigate the effects of COD/TP ratio on the rates of phosphorus removal, COD removal, nitrogen removal, PHB utilization and oxygen uptake. The system was fed with municipal wastewater and operated at 20° C. The influent COD concentration was held approximately constant while the phosphorus concentration was varied to obtained the desired COD/TP ratio. Once robust enhanced biological phosphorus removal (EBPR) has been established, the COD/TP ratios of 20, 30, 40 and 60 were investigated.
The COD/TP ratio of the influent wastewater was observed to have a substantial effect upon the performance of the UCT BNR system. The amount of phosphorus removed by the system and the percent phosphorus in the aerobic zone MLVSS decreased as the COD/TP ratio increased. In addition, the amount of phosphorus released in the anaerobic zone per unit of COD removed in the anaerobic zone increased as the COD/TP ratio decreased. From this research, the amount of anaerobic COD removal required to remove 1 mg/L of phosphorus in the aerobic zone approached a minimum value as the COD/TP ratio decreased. It was also shown that PHB production increased as the COD/TP ratio increased. The highest specific oxygen uptake rate was always observed in the second aerobic reactor and tended to increase as the COD/TP ratio increased. However, the changes in the COD/TP ratio did not significant affect COD removal, nitrogen removal and the observed yield coefficient, but did strongly affect the MLSS concentration. The MLSS concentration at the COD/TP ratio of 60 was only 55% of that at the COD/TP ratio of 20. A high level of anaerobic COD removal, an elevated percent phosphorus in the waste activated sludge (WAS) and a high soluble effluent phosphorus concentration can be used as indicators that the system is operating under COD limiting conditions.
Several phenomena were also observed during this research. Firstly, the performance of the UCT BNR system for EBPR was greatly enhanced by reducing the aerobic volume. Secondly, the correlation between non-oxic phosphorus release and the aerobic phosphorus uptake improved when anoxic phosphorus release was taking into consideration. This indicated that the anoxic phosphorus release was not secondary release once the aerobic zone volume was reduced. Finally, no denitrification was observed in the aerobic zone from this study, based on the assumption that 12% of nitrogen was required for bacterial growth.Master of Science
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Yanosek, Kristina Anne. "Enhanced Biological Phosphorus Removal from Dairy Manure to Meet Nitrogen:Phosphorus Crop Nutrient Requirements." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35782.
Full textAbstract:
Over the last two decades, livestock operations have become highly concentrated due to growing trends towards larger, more confined facilities and a decrease in cropland on smaller farms. This has led to greater amounts of excess manure nutrients on farms, increasing the potential for nutrient pollution of water bodies from runoff. The purpose of this study was to determine if enhanced biological phosphorus removal (EBPR) is a viable alternative for managing excess manure nutrients on dairy farms. Assessment of EBPR involved the investigation of various aspects of wastewater treatment modeling and design and farm nutrient management. The fermentation potential (volatile fatty acid (VFA) production) of dairy manure was determined through laboratory analysis to be 15.3% of the total COD. Total VFA production was composed of 57, 23, and 20% acetic, propionic, and butyric acids, respectively. The EBPR component of the BioWin wastewater treatment model was evaluated through a sensitivity analysis. The parameters to which effluent phosphate (PO4) concentration was most sensitive were maximum specific growth rate, growth yield, aerobic PO4 uptake rate per unit poly-b-hydroxybutyrate (PHB) utilized, PHB yield from VFA, PO4 release per unit VFA uptake, and fraction of releasable PO4. An EBPR sequencing batch reactor (SBR) was designed for a dairy farm with 700 lactating cows and 325 ha of corn silage. An economic analysis of EBPR for dairy farms employing P-based manure applications was completed. The cost of hauling excess manure to nutrient deficient farms was the most significant expense in comparing costs of manure management with and without EBPR. For a herd of 700 lactating cows, utilizing EBPR was more economical for farms with 270 ha or less cropland, while EBPR did not offer an economic advantage for farms over 270 ha.Master of Science
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Mellin, Hannu Kaarlo Olavi. "The effect of high temperatures (30 degrees Celsius) on biological nutrient removal performance." Master's thesis, University of Cape Town, 1999. http://hdl.handle.net/11427/21729.
Full textAbstract:
The main objective of this investigation was to evaluate activated sludge biological nutrient removal (BNR) performance at elevated temperatures for possible application of nitrification denitrification (ND) and ND biological excess phosphorus removal (NDBEPR) systems to municipal wastewater treatment in the equatorial and tropical regions or to combined treatment of municipal and anaerobically (thermophilic) pretreated paper and pulp industry wastewaters in the very cold northern forested regions. To accomplish this objective, a ND Modified Ludzack Ettinger (MLE) system and a NDBEPR University of Cape Town (UCT) system were operated at 30°C and 10 days sludge age for a period of 582 days. During the investigation 41 sewage batches, each lasting about two weeks, of real sewage from the Mitchells Plain municipal wastewater treatment plant (Western Cape, South Africa) were fed to the systems. The two systems were sampled and tested ,almost daily for Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN), Free and Saline Ammonia (FSA), nitrate, nitrite, Total Phosphorus, Volatile Settleable Solids (VSS), Total Settleable Solids (TSS), pH, Oxygen Utilization Rate (OUR) and diluted sludge volume index (DSVI) in the influent, anaerobic, anoxic and aerobic reactors and effluent as appropriate. Also, in order to determine the kinetic rates of nitrification, denitrification and readily biodegradable COD (RBCOD) conversion to Volatile Fatty Acids (VF A), aerobic, anoxic and anaerobic batch tests were conducted at 30°C on sludge harvested from the two systems and microscopic examination of the sludges was undertaken every four weeks to identify the filamentous organisms in the systems.
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Mebrahtu, Michael Kidane. "Aerobic digestion of waste activated sludge from biological nutrient removal activated sludge systems." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/5025.
Full textAbstract:
Includes bibliographical references.Waste activated sludge (WAS) is a biological sludge that contains biodegradable and non-biodegradable volatile suspended solids (VSS) and non-volatile inorgainic suspended solids (ISS). Stabilization for safe disposal of the WAS is a process of paramount importance at wastewater treatment plants (WWTPs). Hence, aerobic digestion of the WAS from biological nutrient removal (BNR) activated sludge (AS) systems was carried out under batch conditions to (1) measure changes in nitrogen and phosphorus concentrations in solid and liquid phases during aerobic batch digestion tests (2) simulate the parent system with Activated Sludge Model No. 2 (ASM-2) in AQUASIM computer program to obtain the initial conditions for batch test simulation (3) simulate the batch aerobic digestion process with ASM-2 and compare with experimental data (4) develop VSS-based and total suspended solids (TSS) (with the addition of ISS to the VSS-based) batch reactor and steady state models for aerobic digestion of nitrification denitrification biological excess phosphorus removel (NDBEPR) WAS based on the individual biomass die-off rates of phosphorus accumulating organisms (PAOs) and ordinary heterotrophic organisms (OHOs), and (5) evaluate the ASM-2 simulation results with steady state aerobic batch digestion model.
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Knapp, Leslie Ann. "Study of Process Control Strategies for Biological Nutrient Removal in an Oxidation Ditch." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5249.
Full textAbstract:
Advanced wastewater treatment plants must meet permit requirements for organics, solids, nutrients and indicator bacteria, while striving to do so in a cost effective manner. This requires meeting day-to-day fluctuations in climate, influent flows and pollutant loads as well as equipment availability with appropriate and effective process control measures. A study was carried out to assess performance and process control strategies at the Falkenburg Road Advanced Wastewater Treatment Plant in Hillsborough County, Florida.
Three main areas for control of the wastewater treatment process are aeration, return and waste sludge flows, and addition of chemicals. The Falkenburg AWWTP uses oxidation ditches where both nitrification and denitrification take place simultaneously in a low dissolved oxygen, extended aeration environment. Anaerobic selectors before the oxidation ditches help control the growth of filamentous organisms and may also initiate biological phosphorus removal. The addition of aluminum sulfate for chemical phosphorus removal ensures phosphorus permit limits are met. Wasting is conducted by maintaining a desired mixed liquor suspended solids (MLSS) concentration in the oxidation ditches.
For this study, activated sludge modeling was used to construct and calibrate a model of the plant. This required historical data to be collected and compiled, and supplemental sampling to be carried out. Kinetic parameters were adjusted in the model to achieve simultaneous nitrification-denitrification. A sensitivity analysis found maximum specific growth rates of nitrifying organisms and several half saturation constants to be influential to the model. Simulations were run with the calibrated model to observe relationships between sludge age, MLSS concentrations, influent loading, and effluent nitrogen concentrations.
Although the case-study treatment plant is meeting discharge permit limits, there are several recommendations for improving operation performance and efficiency. Controlling wasting based on a target MLSS concentration causes wide swings in the sludge age of the system. Mixed liquor suspended solids concentration is a response variable to changes in sludge age and influent substrate. Chemical addition for phosphorus removal should also be optimized for cost savings. Finally, automation of aeration control using online analyzers will tighten control and reduce energy usage.
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Lakshminarasimman, Meanakshisek Narasimman. "Evaluating the Fate Mechanisms of Trace Organic Compounds in Biological Nutrient Removal Treatment Systems." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479818400753707.
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Vogts, Michelle. "The removal of nitrogen and phosphorus in anoxic-aerobic digestion of waste activated sludge from biological nutrient removal systems." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24307.
Full textAbstract:
Biological nutrient removal (BNR) activated sludge systems (designed and operated with an additional function of biologically removing nitrogen and phosphorus) produce a waste activated sludge (WAS) that is rich in nitrogen (N) and phosphorus (P). When digested, this nitrogen and phosphorus are released, producing a dewatering liquor high in ammonia or nitrate and phosphate. Not only does this dewatering liquor need to be treated, but the phosphate also precipitates in the digester and surrounding pipework, resulting in loss of digester capacity and pipe blockages. This investigation studies anoxic-aerobic digestion (aerobic digestion with intermittent aeration), as an alternative digestion of BNR WAS. Aerobic digestion is simple to operate – being an extension of the activated sludge process, requiring aeration and limited recycling. This compared with anaerobic digestion which is complex to operate requiring airtight containers with fire risk, heating and much recycling. In anoxic-aerobic digestion, the nitrogen is removed by nitrification-denitrification, which has the added advantages of reducing the digester's oxygen demand and recovering some of the alkalinity lost in nitrification. Phosphate is precipitated in the digester - a convenient location. This results in a digester dewatering liquor low in nitrogen and phosphorus (<5 mgNH₄-N/l, <15 mgNO₃- N/l and 20 to 30 mgPO₄-P/l) that can be returned to the activated sludge plant without overloading it.
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Smith, Shaleena. "Pilot assessment of Novel Membrane Bioreactor Processes - Improvements in Biological Nutrient Removal and Membrane Operation." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3357.
Full textAbstract:
With increasing water reuse applications and upcoming stringent regulations for treated wastewater effluent discharge, wastewater plants need to consider alternative technologies beyond conventional treatment processes. The new regulations, Numeric Nutrient Criteria (NNC), may regulate discharge nitrogen and phosphorus concentrations to as low as 0.5 mg/L as N and 10 μg/L as P respectively. To meet these target requirements, system retrofitting to incorporate chemical or advanced nutrient removal systems possibly with membrane technology will most likely be required. Although microfiltration/ultrafiltration membranes coupled with biological processes, otherwise known as membrane bioreactors (MBR), remove contaminants and suspended solids, nutrient removal is minimal to none. This emphasizes the importance of the biological process in MBRs. This study evaluated and tested the improvement of biological nutrient removal (BNR) in an MBR system which can meet NNC regulations along with the optimization of membrane operation for the reduction of fouling and energy consumption.
A pilot study was conducted at the City of Tampa wastewater treatment plant and was divided into four phases of experimentation using two submerged MBR membranes operated with modified biological configurations. Laboratory analyses and data collection were conducted during the experiments and the performance evaluated for each configuration. System configurations were also optimized throughout each phase of testing for nutrient removal. Important factors used in the development of an appropriate configuration included isolation of the membrane tank from the biological reactors in the design, control of the dissolved oxygen (DO) concentrations or specifically the oxidation reduction potential (ORP) during operation and appropriate internal recirculation rates between the reactors.
The results of this study provided information relevant for the assessment of both the BNR process and membrane performance. Membrane performance data indicated the importance and effect of air scouring (despite energy consumption) on membrane fouling for long-term stable flux operation as well as the cleaning frequency whether chemical enhanced backwash (CEB) or clean-in-place (CIP). This assessment also discussed how BNR systems can be enhanced through the incorporation of important design factors to eliminate the inhibiting factors of nitrogen and phosphorus removal such as dissolved oxygen. One of the biological processes tested in this study achieved effluent nitrogen and phosphorus concentrations below 5 mg/L and 1 mg/L respectively. Although the process tested did not meet NNC criteria, it can be applied with chemical precipitation. This, in turn, can reduce the operating and maintenance (O&M) costs associated with the chemical precipitation of phosphorus.
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Guisasola, i. Canudas Albert. "Modelling biological organic matter and nutrient removal processes from wastewater using respirometric and titrimetric techniques." Doctoral thesis, Universitat Autònoma de Barcelona, 2005. http://hdl.handle.net/10803/5306.
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Feng, Yu. "Investigation of biological nutrient removal from a weak domestic wastewater in a flexible pilot-plant." Thesis, University of Leeds, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435917.
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Hercules, Selwyn Mark. "Full scale demonstration of filamentous bulking control at a biological nutrient removal activated sludge plant." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/5040.
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Sun, Feiyun, and 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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Banihani, Qais Hisham. "ANAEROBIC - AEROBIC TREATMENT OF DOMESTIC SEWAGE." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193820.
Full textAbstract:
Domestic wastewater is the most abundant type of wastewater. Direct discharge of untreated domestic wastewater has environmental and public health risks due to the presence of organics, nutrients and pathogens. Application of anaerobic processes for the treatment of domestic sewage, which at present is largely treated by aerobic processes, has drawn considerable attention recently. Anaerobic processes can be applied for the removal of organic matter (methanogenesis) and nitrogen (anaerobic ammonium oxidation (Anammox)).The toxicity of fluoride to methanogenesis was investigated. The results indicate that acetoclastic were more susceptible to fluoride than hydrogenotrophic methanogens. The concentration of fluoride causing 50% inhibition (IC50) to acetoclastic ranged from 18.1 to 155.7 mg L-1 while for hydrogenotrophic methanogens was > 400.0 mg L-1.The feasibility of a combined system consisting of anaerobic up-flow anaerobic sludge blanket (UASB) followed by aerobic activated sludge (AS) reactor for removal of carbonaceous and nitrogenous contaminants from strong synthetic sewage (2.5 g chemical oxygen demand (COD) L-1) was also studied. The average combined removal of total COD, volatile fatty acids (VFA) and protein was higher than 89.0%, 99.0% and 97.0%; respectively. Extensive nitrification (96.0%) was observed when dissolved oxygen (DO) concentration was > 2.0 mg L-1. In contrast, only partial nitrification occurred when the AS received high organic loads and/or the DO level was below 2.0 mg L-1.The inhibitory effect of nitrite and nitrate on methanogenesis was evaluated. Methanogenic activity was inhibited by the presence of NOx- compounds (i.e., nitrite and nitrate). The inhibition imparted by nitrate was not due to the nitrate itself, but rather to its reduced intermediate, nitrite. The toxicity of NOx- to methanogens was found to be reversible after all the NOx- were reduced during denitrification.Moreover, the development of Anammox enrichment cultures was evaluated. Anammox cultures were successfully developed using sludge samples collected from municipal wastewater treatment plants (WWTPs) as inocula but not from methanogenic granular sludges. Return activated sludge (RAS) collected from WWTP operating for biological nitrogen removal had the highest intrinsic level of Anammox activity. RAS Anammox culture was developed rapidly within 40 days with a doubling time of 6.8 days.
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Brooks, Patrick C. "An investigation of temperature effects on denitrifying bacterial populations in a biological nutrient removal (BNR) system." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-03042009-041300/.
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Browning, Catharine, and n/a. "Nutrient Removal and Plant Growth in a Subsurface Flow Constucted Wetland in Brisbane, Australia." Griffith University. School of Environmental Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040226.092311.
Full textAbstract:
One of the major water quality issues affecting waterways is eutrophication. Controlling the input of nutrients from municipal wastewater treatment plants (WTPs) is a significant step in reducing eutrophication. Tertiary wastewater treatment for water quality improvement in particular Biological Nutrient Removal (BNR) is often expensive to construct with high maintenance costs. Constructed wetlands (CWs) offer an alternative wastewater treatment and have been used successfully worldwide to treat various types of wastewater. This study investigated the effectiveness of the Oxley Creek horizontal subsurface flow (SSF) CW for tertiary municipal wastewater treatment and the suitability of four native macrophyte species, Baumea articulata, Carex fascicularis, Philydrum lanuginosum and Schoenoplectus mucronatus. The investigation consisted of four main components: 1) Plants: monitoring plant establishment, growth, impact of cropping, gravel size, nutrient content and storage for the four macrophyte species trialed; 2) Water quality - effluent treatment: monitoring water quality and quantity entering and leaving the wetland to determine wastewater treatment; 3) Organic matter: accumulation of organic carbon within the wetland cells for the different gravel sizes (5mm and 20mm) and 4) Mass balance: combining nutrient storage by macrophytes with wastewater nutrient removal to determine proportion of nutrient removal by plant uptake. The Oxley horizontal SSF CW is situated at the Oxley Creek WTP in Brisbane (South- East), Queensland, Australia which has a sub-tropical climate. The experimental design involved four different substrate treatments: Cell A new 5mm gravel, Cells B and C old 20mm gravel and Cell D old 5mm gravel. Cells B, C and D had been operational since 1995 whereas Cell A had been in use since 2000. The wetland received secondary treated effluent direct from the Oxley Creek WTP at an average flow rate of 8L/min with a median hydraulic loading rate (HLR) of 0.12m/day and a hydraulic retention time (HRT) of 2 to 3 days. Each cell consisted of three gravel sections (Section 1 to 3) separated by 1m wide open water sections. Gravel Sections 2 and 3 were planted out with the four macrophyte species in October 2000, Section 1 remained unplanted. Plant health and leaf height was monitored to assess plant establishment and growth. Investigations into plant establishment and growth demonstrated that Carex was most suitable. Carex achieved the highest maximum leaf height and was not affected by pests and disease unlike Schoenoplectus and Philydrum. Above ground biomass was cropped in May and August 2001, with biomass of cropped material measured on both occasions. Plant health and re-growth following cropping of above ground biomass in May and August 2001 demonstrated that cropping retarded regrowth of Schoenoplectus and Philydrum. Carex and Baumea recovered quickest following cropping, with Carex achieving leaf height prior to cropping within 6 months. Proportion of biomass contained above and below ground was measured by collecting biomass samples three times over 9 months and dividing into plant components (roots, rhizomes, leaves, flowers and stems). Investigations into the proportion of above and below ground components indicated that >80% of biomass is contained above ground. Therefore cropping above ground biomass would potentially remove a significant proportion of nutrient storage from the CW. The results indicated that the ideal time for cropping was in spring/summer when plants are flowering particularly for Philydrum, whose flowering stems comprised 40% of total plant biomass. Flowering stems of Philydrum could potentially have a commercial use as a cut flower. Nutrient content of the four species in each cell was measured for individual plant components when first planted and after three (summer) and six (autumn) months growth. This was combined with biomass data to quantify nutrient bioaccumulation (nitrogen and phosphorus) by the four species in each cell. In terms of ability to bioaccumulate nitrogen and phosphorus, measurements of nutrient content and storage indicated that all four species were suitable. Nutrient storage was highest for Baumea and Carex. However high nutrient content may make the macrophytes more susceptible to pest and disease attack as found in this study for Philydrum and Schoenoplectus. Nutrient storage was highest in Cell A (new 5mm gravel) as a result of higher biomass achieved in this cell. The cropping and nutrient storage experiments indicated that Carex was the most suitable species for use in SSF CWs. Carex achieved the highest nutrient storage and had the fastest regrowth following cropping. Organic carbon accumulation between gravel particles measured as the proportion of material lost at 500oC was determined for gravel samples collected from each section for all four cells at 10cm depth increments (0-10cm, 10-20cm and 20-30cm). Investigations into organic carbon accumulation within the gravel substrate showed that organic accumulation was higher in the planted sections particularly for cells that had previously been planted with Phragmites australis. Organic accumulation was highest in the top 20cm of the gravel, which can be attributed to litter fall and root material. The effect of gravel size on plant growth, biomass, root depth and organic accumulation was assessed throughout the study. Investigations indicated that gravel size did not appear to affect biomass, maximum root penetration, re-growth following cropping and organic accumulation. Water quality from the inlet and outlet of each cell was measured fortnightly over 12 months (May 2001 to May 2002). Water quantity (HLR) was measured weekly using tipping buckets located at the inlet and outlet of each cell. Water quality and quantity were combined to investigate the nutrient removal efficiency of the wetland. The Oxley wetland was highly effective in reduction of TSS (<2mg/L) and COD (<30mg/L). Principal TSS and COD removal mechanism was physical with the first gravel section acting as a filter removing the majority of particulate material. Average loading rates to the wetland were 7.1 kg/ha/d PO4-P, 14 kg/ha/d NH4-N and 5.4 kg/ha/d NOx-N. Average daily mass removal rates ranged from 7.3 kg/ha NH4-N in Cell D to 4.6 kg/ha in Cell C (i.e. 37%-22% removal efficiency respectively); 5.2 kg/ha NOx-N in Cell C to 1.3 kg/ha in Cell A (i.e. 75%-22% removal efficiency) and 0.8 kg/ha PO4-P in Cell A to 0.1 kg/ha in Cell C (i.e. 10%-1% removal efficiency). Removal efficiency was calculated on a loads basis. Insufficient retention times (2-3 days based on tracer study) and anaerobic conditions (<1mg/L) limited further nitrogen removal. Negligible phosphorus removal for all cells was attributed to short retention time and likelihood of phosphorus adsorption being close to capacity. Investigation into the proportion of nutrient removal attributed to plant uptake demonstrated that nutrient uptake and storage in plant biomass accounted for <12% TN and <5% TP. This research project has provided several useful outcomes that can assist in future guidelines for designing effective SSF CWs in the subtropics/tropics. Outcomes include the importance of maintaining an adequate water level during the initial establishment phase. Maximising effluent treatment by pre-treatment of wastewater prior to entering SSF CWs to enable ammonia to be converted to nitrate and ensuring adequate hydraulic retention time. Carex fascicularis was the most suitable species particularly where harvesting regimes are employed. Philydrum flowering stems could be used as a cut flower in the florist trade.
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Browning, Catharine. "Nutrient Removal and Plant Growth in a Subsurface Flow Constucted Wetland in Brisbane, Australia." Thesis, Griffith University, 2003. http://hdl.handle.net/10072/366348.
Full textAbstract:
One of the major water quality issues affecting waterways is eutrophication. Controlling the input of nutrients from municipal wastewater treatment plants (WTP’s) is a significant step in reducing eutrophication. Tertiary wastewater treatment for water quality improvement in particular Biological Nutrient Removal (BNR) is often expensive to construct with high maintenance costs. Constructed wetlands (CWs) offer an alternative wastewater treatment and have been used successfully worldwide to treat various types of wastewater. This study investigated the effectiveness of the Oxley Creek horizontal subsurface flow (SSF) CW for tertiary municipal wastewater treatment and the suitability of four native macrophyte species, Baumea articulata, Carex fascicularis, Philydrum lanuginosum and Schoenoplectus mucronatus. The investigation consisted of four main components: 1) Plants: monitoring plant establishment, growth, impact of cropping, gravel size, nutrient content and storage for the four macrophyte species trialed; 2) Water quality - effluent treatment: monitoring water quality and quantity entering and leaving the wetland to determine wastewater treatment; 3) Organic matter: accumulation of organic carbon within the wetland cells for the different gravel sizes (5mm and 20mm) and 4) Mass balance: combining nutrient storage by macrophytes with wastewater nutrient removal to determine proportion of nutrient removal by plant uptake. The Oxley horizontal SSF CW is situated at the Oxley Creek WTP in Brisbane (South- East), Queensland, Australia which has a sub-tropical climate. The experimental design involved four different substrate treatments: Cell A new 5mm gravel, Cells B and C old 20mm gravel and Cell D old 5mm gravel. Cells B, C and D had been operational since 1995 whereas Cell A had been in use since 2000. The wetland received secondary treated effluent direct from the Oxley Creek WTP at an average flow rate of 8L/min with a median hydraulic loading rate (HLR) of 0.12m/day and a hydraulic retention time (HRT) of 2 to 3 days. Each cell consisted of three gravel sections (Section 1 to 3) separated by 1m wide open water sections. Gravel Sections 2 and 3 were planted out with the four macrophyte species in October 2000, Section 1 remained unplanted. Plant health and leaf height was monitored to assess plant establishment and growth. Investigations into plant establishment and growth demonstrated that Carex was most suitable. Carex achieved the highest maximum leaf height and was not affected by pests and disease unlike Schoenoplectus and Philydrum. Above ground biomass was cropped in May and August 2001, with biomass of cropped material measured on both occasions. Plant health and re-growth following cropping of above ground biomass in May and August 2001 demonstrated that cropping retarded regrowth of Schoenoplectus and Philydrum. Carex and Baumea recovered quickest following cropping, with Carex achieving leaf height prior to cropping within 6 months. Proportion of biomass contained above and below ground was measured by collecting biomass samples three times over 9 months and dividing into plant components (roots, rhizomes, leaves, flowers and stems). Investigations into the proportion of above and below ground components indicated that >80% of biomass is contained above ground. Therefore cropping above ground biomass would potentially remove a significant proportion of nutrient storage from the CW. The results indicated that the ideal time for cropping was in spring/summer when plants are flowering particularly for Philydrum, whose flowering stems comprised 40% of total plant biomass. Flowering stems of Philydrum could potentially have a commercial use as a cut flower. Nutrient content of the four species in each cell was measured for individual plant components when first planted and after three (summer) and six (autumn) months growth. This was combined with biomass data to quantify nutrient bioaccumulation (nitrogen and phosphorus) by the four species in each cell. In terms of ability to bioaccumulate nitrogen and phosphorus, measurements of nutrient content and storage indicated that all four species were suitable. Nutrient storage was highest for Baumea and Carex. However high nutrient content may make the macrophytes more susceptible to pest and disease attack as found in this study for Philydrum and Schoenoplectus. Nutrient storage was highest in Cell A (new 5mm gravel) as a result of higher biomass achieved in this cell. The cropping and nutrient storage experiments indicated that Carex was the most suitable species for use in SSF CWs. Carex achieved the highest nutrient storage and had the fastest regrowth following cropping. Organic carbon accumulation between gravel particles measured as the proportion of material lost at 500oC was determined for gravel samples collected from each section for all four cells at 10cm depth increments (0-10cm, 10-20cm and 20-30cm). Investigations into organic carbon accumulation within the gravel substrate showed that organic accumulation was higher in the planted sections particularly for cells that had previously been planted with Phragmites australis. Organic accumulation was highest in the top 20cm of the gravel, which can be attributed to litter fall and root material. The effect of gravel size on plant growth, biomass, root depth and organic accumulation was assessed throughout the study. Investigations indicated that gravel size did not appear to affect biomass, maximum root penetration, re-growth following cropping and organic accumulation. Water quality from the inlet and outlet of each cell was measured fortnightly over 12 months (May 2001 to May 2002). Water quantity (HLR) was measured weekly using tipping buckets located at the inlet and outlet of each cell. Water quality and quantity were combined to investigate the nutrient removal efficiency of the wetland. The Oxley wetland was highly effective in reduction of TSS (<2mg/L) and COD (<30mg/L). Principal TSS and COD removal mechanism was physical with the first gravel section acting as a filter removing the majority of particulate material. Average loading rates to the wetland were 7.1 kg/ha/d PO4-P, 14 kg/ha/d NH4-N and 5.4 kg/ha/d NOx-N. Average daily mass removal rates ranged from 7.3 kg/ha NH4-N in Cell D to 4.6 kg/ha in Cell C (i.e. 37%-22% removal efficiency respectively); 5.2 kg/ha NOx-N in Cell C to 1.3 kg/ha in Cell A (i.e. 75%-22% removal efficiency) and 0.8 kg/ha PO4-P in Cell A to 0.1 kg/ha in Cell C (i.e. 10%-1% removal efficiency). Removal efficiency was calculated on a loads basis. Insufficient retention times (2-3 days based on tracer study) and anaerobic conditions (<1mg/L) limited further nitrogen removal. Negligible phosphorus removal for all cells was attributed to short retention time and likelihood of phosphorus adsorption being close to capacity. Investigation into the proportion of nutrient removal attributed to plant uptake demonstrated that nutrient uptake and storage in plant biomass accounted for <12% TN and <5% TP. This research project has provided several useful outcomes that can assist in future guidelines for designing effective SSF CWs in the subtropics/tropics. Outcomes include the importance of maintaining an adequate water level during the initial establishment phase. Maximising effluent treatment by pre-treatment of wastewater prior to entering SSF CWs to enable ammonia to be converted to nitrate and ensuring adequate hydraulic retention time. Carex fascicularis was the most suitable species particularly where harvesting regimes are employed. Philydrum flowering stems could be used as a cut flower in the florist trade.Thesis (Masters)
Master of Philosophy (MPhil)
School of Environmental Engineering
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Brown, Patrick Anderson. "Influence of anaerobic and anoxic hydraulic retention time on biological nutrient removal in a membrane bioreactor." [Ames, Iowa : Iowa State University], 2007.
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Randall, William O. "The Effects of a phosphate detergent ban on a biological nutrient removal plant and anaerobic digester /." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040637/.
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Orman, Gavrielle. "A Study on the Simultaneous Nitrification and Denitrification Process of a Membrane Aerated Bioreactor Augmented by BiOWiSH Aqua." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2092.
Full textAbstract:
Nitrogen pollution is a growing problem that is detrimental to the environment and the economy. Traditional treatment of nitrogen is a multi-stage process, expensive, operationally intensive, and requires large land areas. This research studied the effects of BiOWiSH® Aqua (Aqua), a biological enhancement product, on the simultaneous nitrification and denitrification process in a membrane aerated bioreactor (MABR) to determine if it is a feasible application for wastewater treatment. The MABR used during experimentation was a small-scale batch reactor with a continuous flow of air through a silicone membrane.
The effect of carbon source and concentration on nitrogen removal rates and biomass growth/behavior were determined through a series of laboratory experiments with Aqua and wastewater. With glucose and solely Aqua cultures, average reduction rates in nitrogen concentrations were 1.2 mg-N/L/hour for all C:N ratios investigated. When wastewater was used as the main carbon source, creating a mix of wastewater and Aqua bacteria in the MABR, average reduction rates were 10.9 mg-N/L/hour. A maximum reduction rate of 21.3 mg-N/L/hour occurred at a 2:1 C:N ratio.
This research concluded that pure Aqua cultures are not efficient at removing nitrogen or greatly augment the nitrogen reduction process. MABRs can use the biochemical oxygen demand in wastewater as a useful/viable carbon source. High carbon to nitrogen ratios (C:N ratio of 30:1) did not result in faster nitrogen reduction rates but did experience rapid biofilm growth and death. This shows that high C:N ratios are not an efficient operationally for MABRs due to the excess sludge created. C:N ratios of v approximately 3:1 provided the most consistent nitrogen reduction for both glucose and wastewater. This research concluded that C:N ratios, pH, and oxygen diffusion heavily affect the MABR’s performance. In addition, MABRs can utilize low C:N ratios during treatment, particularly during the treatment of high-strength wastewater.
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Lettie, Lucia. "REMOVAL OF REFRACTORY TKN FROM AN EFFLUENT WASTEWATER USING SODIUM FERRATE." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4326.
Full textAbstract:
This research addresses refractory forms of nitrogen that, even with advanced biological nitrification-denitrification systems are not removed completely from domestic wastewater. TKN (Total Kjeldahl Nitrogen), ammonia plus organic nitrogen, is one of the forms to measure the levels of nitrogen present in effluent wastewaters. Ferrate, a strong oxidant, was used for the treatment of these nitrogen forms with the objective of producing nitrogen compounds that can be removed by subsequent biological processes. Bench-scale experiments were performed on effluent samples taken prior to chlorination from an Orlando, FL wastewater treatment facility, using a biological nutrient removal process. The samples were treated with doses of ferrate ranging from 1 to 50 mg/L as FeO4–2 under unbuffered conditions. TKN removal as high as 70% and COD removal greater than 55% was observed. The TSS production after ferrate treatment was in a range of 12 to 200 mg/L for doses between 10 and 50 mg/L FeO4-2. After an optimum dose of ferrate was determined, three bench-scale reactors were operated under anoxic conditions for 10 to 12 days, two as duplicates containing the treated effluent and one as a control with untreated sample. Two different doses of ferrate were used as optimum dose for these experiments, 10 and 25 mg/L as FeO4-2. The purpose of these reactors was to determine the potential for biological removal of remaining nitrogen after ferrate oxidation of refractory nitrogen. Treated and raw samples were analyzed for Total Kjeldahl Nitrogen (TKN) (filtered and unfiltered), chemical oxygen demand (COD) (filtered and unfiltered), total suspended solids (TSS), nitrate (NO3-N), nitrite (NO2-N), and heterotrophic plate count (HPC). As a result, more than 70% of the soluble TKN was removed by chemical and biological oxidation for a sample treated with a dose of 25 mg/L FeO4-2, and less than 50% when treated with 10 mg/L FeO4-2. For the control samples run parallel to the ferrate treated samples, a maximum of 48% of soluble TKN and a minimum of 12% was removed. A three-log increase was observed in heterotrophic bacteria numbers for both doses during the operation of the reactors. Sodium ferrate was found to be an effective oxidant that can enhance the biodegradability of recalcitrant TKN present in municipal wastewaters. As mentioned before this research was develop using batch reactor units at bench-scale, therefore it is recommended to follow the investigation of the biodegradability of recalcitrant TKN of a ferrate treated sample under continuous flow conditions so that results can be extrapolated to a full-scale treatment facility.M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering
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au, rkurup@murdoch edu, and Rajendra Kurup. "An experimental research on application of sub-surface flow constructed wetlands for meat processing industry effluent treatment and nutrient removal." Murdoch University, 2007. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20070717.142408.
Full textAbstract:
Meat processing industries produce large volumes of high strength wastewater.
Conventional technologies used in Australia and similar countries for treatment of
effluent from meat processing and similar industries, such as wineries and processed
food industry, are treatment ponds with or without a mechanical treatment system.
A properly designed activated sludge treatment system would be capable of biological
removal of phosphorus and nitrogen in addition to BOD5. These systems, however,
require substantial electrical power, skilled operational support and produce large
quantities of biosolids or sludge which require further on-site treatment or off site
disposal. Application of sub-surface flow constructed wetland (SSF-CW) systems could
provide a sustainable solution for treatment of meat processing industry effluent and
other similar high strength wastewaters. There are, however, only very limited studies
on application of SSF-CW for secondary treatment of high strength wastewaters.
Although there have been a number of cases where SSF-CW have been used as the
secondary treatment unit for municipal wastewater, this technology has not still become
a common practice for the same purpose in Australia. Most of the applications are for
either polishing of secondary or tertiary treated municipal wastewater or for greywater
treatment.
This research was funded by National Meat Industry Advisory Council (MINTRAC).
Sustainable wastewater treatment has been taken up as a very important issue by meat
industry. The industry provides Ph.D research scholarships through MINTRAC to
develop new technologies for wastewater treatment and nutrient removal from meat
processing effluent.
The main objective of the research was to develop process engineering design
parameters for sub-surface flow constructed wetland (SSF-CW) with Monto vetiver
(Vetiveria zizanioides recently reclassified as Chrysopogon zizanioides) as the emergent
vegetation for treatment of high strength, nutrient rich wastewater. The study also
investigated the phosphorus retention properties of pea gravel for use in SSF-CW
system as bed media or as an external phosphorus removal system for meat processing
industry effluent. In addition, chemical methods for phosphorus removal from meat
processing industry effluent were also investigated.
The thesis is based on experimental research. The research consisted of three types of
experimental set up; a) using two laboratory experimental SSF-CW reactors (one with
vetiver grass and the other reactor with no vegetation) in a greenhouse with batch
feeding of artificial wastewater that simulates meat industry effluent, b) experiment with
pea gravel of different particle sizes and solutions of different phosphorus (P)
concentrations in a constant temperature room, c) laboratory experiment using actual
meat processing industry effluent with alum and sodium aluminate for P removal.
The structure of the thesis is as follows. Following the Introduction is the section of
Literature Review, then sections on the experiments that follow a journal paper format,
followed by a General Discussion, Conclusions and Recommendations. A list of
references is provided at the end of the thesis.
The literature review section has four chapters (Chapter 2 to Chapter 5). Chapter 2
describes a review of meat processing industry effluent characteristics and current
treatment technologies. Chapter 3 is a critical review of current literature on COD
removal using sub-surface flow constructed wetlands (SSF-CW). Chapter 4 and 5
describe a review of various processes and models on the fate of nitrogen and
phosphorus in SSF-CW system respectively.
Chapters 6 to 10 deal with experimental research part of the thesis. Chapters, 6, 7 and 8
share a common methodology section which is described in Chapter 6. Results of the
batch experiments with the laboratory SSF-CW systems on COD removal, nitrogen
removal and phosphorus retention are discussed in Chapters 6, 7 and 8 respectively.
Chapter 9 explains a detailed experimental study on phosphorus adsorption dynamics of
pea gravel. Chapter 10 discusses the results on experiments using sodium aluminate and
aluminium sulphate for P removal from meat processing industry effluent as an alternate
P removal method for such effluent.
An overview of the major results of the experimental section is discussed in chapter 11,
in the General Discussion section. Conclusions and Recommendations of the research
are provided in Chapter 12.
In this study, it was observed that Monto vetiver grass performed better during
nitrification than in denitrification, where the plant did not survive. Ammonium N
removal followed a first order decay in both vegetated and un-vegetated experimental
SSF-CW system with average removal ranging from 40 to 60 % of the influent.
Denitrification was found to be the pathway for nitrate removal. As long as the carbon
source was available, the denitrification followed a first order exponential decay, with
over 80% of nitrate was removed in 48 hours. Vetiver grass sustained elevated
ammonium levels of approximately 200 mg/L or more, however it was under stress
during denitrification and it eventually died.
The experimental SSF-CW systems with pea gravel as bed media could effectively
retain soluble reactive phosphorus (SRP) in the wetland cells during experiments of
COD reduction and nitrification (with ammonia and high COD input). However, during
denitrification study, both experimental SSF-CW cells did not show significant removal
of SRP from wastewater. The vegetated cell removed nearly 50% of the input SRP,
however, the un-vegetated cell did not show any trend for SRP removal, and in some
cases the effluent SRP was nearly 90% of the input value.
The role of Monto vetiver grass for N and P removal was found to be very minor and
this study concluded that nutrient removal (N & P) by plant uptake could be neglected
in the design of SSF-CW system with Monto vetiver grass.
Adsorption is the major mechanism for P removal from the experimental SSF-CW
systems, where pea gravel was used as bed media. The P adsorption capacity of pea
gravel increased with decrease in particle size. For 16 to 18 mm, the Langmuir
adsorption maximum was 99 mg/kg, whereas for very fine pea gravel powder (<150
ìm) the maximum adsorption observed experimentally was 3950 mg/kg. In a typical
wetland with pea gravel as bed media for meat processing industry, the media would be
capable of P retention for about 2 to 3 years of operation. Supplementary chemical
removal method is needed for sustainable P removal once the adsorption maximum of
wetland cell is reached.
A chemical P removal system using liquid alum and NaOH for pH stabilisation is more
appropriate than sodium aluminate. Application of sodium aluminate for P removal for
meat processing industry effluent is found to be less effective as it would need higher
dosage, longer settling period, coloured supernatant, acid addition for pH adjustment.
Liquid alum application rate is recommended to be between a molar ratio of Al: P of 3
for TP value of <1 mg/L in the treated effluent.
This research study concludes that horizontal flow SSF-CW system with Monto vetiver
grass is suitable for COD removal and nitrification from high strength wastewater.
Current design equation of horizontal flow SSF-CW system is mostly plug flow
exponential decay method, but in this study, it has been concluded that retarded first
order rate constant is the most appropriate design method for horizontal flow SSF-CW
system for COD removal.
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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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Merilles, Kimberly Michelle LaMar. "Effect of Bio-Augmentation Product BiOWiSH® Septic Rescue on the Wastewater Treatment Performance of Residential Septic Tanks." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2003.
Full textAbstract:
Residential septic systems provide reliable wastewater treatment for over 26 million homes and facilities in the United States, and many more worldwide. When properly maintained, these systems are reliable, low-cost, and long-term treatments for residential wastewater. When neglected, septic systems can fail and lead to health concerns and ecological harm to soil and groundwater contamination through the improperly treated wastewater effluent.
This study tested the effect of the bio-augmentation product BiOWiSH® Septic Rescue of BiOWiSH® Technologies International, Inc. (hereafter referred to as BiOWiSH) on the biological treatment of residential septic tanks. BiOWiSH is meant to act as a bio-augmentation product through the addition of a proprietary blend of Bacillus and Lactic Acid producing bacteria. These microbes act as a biocatalyst to enhance and encourage a range of hydrolytic, oxidative, and reductive biochemical reaction and promote digestion of bio solids and ammonification within the septic tanks.
To test the effect of BiOWiSH on the treatment of residential septic tanks, four 32-gallon tanks were constructed and filled with water and primary sludge from the primary clarifier at the San Luis Obispo Water Resource Recovery Facility. Two tanks were dosed with the recommended amount of BiOWiSH; one tank had no additive biological treatment and served as the control; one tank was dosed with RID-X® Septic Maintenance, a leading competitive product (hereafter referred to as RID-X).
Each tank functioned as a plug-flow reactor. Primary sludge and tap water was added daily and effluent was sampled on a daily or weekly basis, based on the parameters being tested. Effluent water samples were tested for removal of ammonia, nitrates, total suspended solids, and biological oxygen demand. Temperature and pH were also recorded. v
These analyses indicated no significant advantage from the addition of BiOWiSH in the reduction of ammonia, total suspended solids, or biological oxygen demand over the control tank or the tank dosed with the RID-X competitive product. Nitrates (in the form of nitrate and nitrite) did not form in any of the tanks.
Future studies are needed to validate these results. Additional studies should include an analysis of experimental time frames, sampling frequency, and testing additional products designed to rescue failed or failing septic systems. BiOWiSH should also be tested further in its potential ability to enhance the biological treatment of septic tank effluent once the wastewater has entered aerobic leach fields.
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Pilson, Richard Adair. "The effect of temperature on denitrification kinetics and biological excess phosphorus removal in nutrient removal activated sludge systems in temperate climates (12°C - 20°C)." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/22577.
Full textAbstract:
Filamentous bulking in nutrient (N & P) removal activated sludge systems is a problem of considerable magnitude - three quarters of 45 plants surveyed were found to have bulking sludges to the extent that sludge settleability (DSVI) was adversely affected. If filamentous organism proliferation could be controlled and thereby sludge settleability improved to below DSVI of 100 ml/g, then with provision for factors such as additional aeration capacity, between 50% and 7 5% more wastewater could be treated in existing nutrient removing activated sludge plants. Anoxic-aerobic (AA) or low F/M filaments appear to proliferate in activated sludge plants that incorporate biological nitrogen removal. From earlier research, Casey et al. (1992a) showed that the cause for AA filament proliferation lay in the denitrification behaviour of the N removal systems. They hypothesized that filamentous and floe-forming organisms have different denitrification behaviour - the former reducing nitrate only as far as nitrite whereas the latter reducing nitrate all the way to nitrogen gas via the denitrification intermediates nitrite, nitric oxide (NO) and nitrous oxide (N₂O). If nitrate and nitrite removal to nitrogen gas is not complete in the anoxic reactor, then, when conditions become aerobic, the accumulated denitrification intermediates, in particular NO, inhibit oxygen uptake in the floc-formers. The filaments do not experience this inhibition because by reducing nitrate only to nitrite, no denitrification intermediates accumulate in their cytoplasmic membrane and consequently they can successfully compete against the floe-formers and proliferate in the N removal systems. If denitrification is complete, no residual intracellular denitrification intermediates remain in the floc-formers. Therefore, when conditions become aerobic, the floc-formers are not inhibited in their oxygen uptake and can successfully compete against the filamentous organisms which cause the bulking.
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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.
Full textAbstract:
[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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Miriyala, Amulya. "Impact of Recirculating Nitrified Effluent on the Performance of Passive Onsite Hybrid Adsorption and Biological Treatment Systems." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7697.
Full textAbstract:
Approximately 25% of households in the U.S. treat their wastewater onsite using conventional onsite wastewater treatment systems (OWTS). These systems typically include a septic tank or a series of septic tanks followed by a soil absorption system. They effectively remove biochemical oxygen demand (BOD), total suspended solids (TSS), fats and grease but are not designed to remove significant amounts of nitrogen. High nitrogen loading to coastal and ground waters can be dangerous to aquatic life and public health. Hence, there is a need for advanced onsite wastewater treatment systems that can effectively remove nitrogen. Making enhanced nitrogen removal for OWTS as our primary goal, a laboratory scale Hybrid Adsorption and Biological Treatment Systems (HABiTS) was developed and upon observation of its effective nitrogen removal capacity, a pilot demonstration study with two side-by-side HABiTS, one with recirculation and one without recirculation (only forward flow) were constructed and tested at the Northwest Regional Water Reclamation Facility in Hillsborough County (Florida).
HABiTS employ biological nitrogen removal and ion exchange for effective nitrogen removal. HABiTS is a two-stage process which uses nitrification for the oxidation of ammonium to nitrate and ion exchange for ammonium adsorption that helps buffer transient loading and also acts as a biofilm carrier in its stage 1 biofilter and it uses tire-sulfur hybrid adsorption denitrification (T-SHAD) in its stage 2 biofilter. These sulfur pellets help promote sulfur oxidation denitrification (SOD) and tire chips are used for nitrate adsorption during transient loading conditions, as biofilm carriers for denitrifying bacteria, and can also be used as organic carbon source to promote heterotrophic denitrification because they leach organic carbon. For this research, HABiTS without recirculation is considered as the control system and the performance of HABiTS with recirculation was tested for its ability to further enhance nitrogen removal from HABiTS.
Nitrified effluent recirculation is a common strategy employed in wastewater treatment for enhanced nitrogen removal. It is the reintroduction of semi-treated wastewater to pass through an anoxic pre-treatment chamber to achieve better quality effluent. Recirculation is said to improve and consistently remove nitrogen at any hydraulic loading rate and/or nitrogen concentration. This is because of the dilution of high BOD septic tank effluent with nitrified effluent which lowers COD:TKN ratio and also improves mass transfer of substrates in the stage 1 biofilter. Recirculation also provides some pre-denitrification in the pre-treatment chamber, thereby reducing nitrogen load on the system.
The HABiTS with recirculation (R) was run at 1:1 ratio of nitrified effluent recirculation rate to the influent flow rate for 50 days, and at 3:1 ratio for the remaining period of this research (200 days). The forward flow system (FF) was run under constant conditions throughout the research and comparisons between the two systems were made for different water quality parameters (pH, DO, conductivity, alkalinity, TSS, chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and various nitrogen species). The final effluent ammonium results showed that the system with recirculation removed consistently > 80% NH4+-N during 1:1 and 3:1 recirculation ratios whereas the forward flow system achieved 57% removal. Further, an average of 81% total inorganic nitrogen (TIN) removal from the system influent was seen in the recirculation system’s final effluent when compared to an average of 55% in forward flow system’s final effluent.
This research explains in detail, the impact of nitrified effluent recirculation on enhanced nitrogen removal in onsite systems and the results presented in this thesis proved that nitrified effluent recirculation provides promising enhanced nitrogen removal in an onsite wastewater treatment system.
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Arakaki, Joelle. "Study of the Effect of BiOWiSH Aqua on Simultaneous Nitrification and Denitrification in a Membrane Aerated Bioreactor." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1893.
Full textAbstract:
This research entails the investigation of the effects of a bioaugmentation product from BiOWiSH® called Aqua, referred to as “Aqua” for the remainder of this paper, on the nitrogen removal rate in a membrane aerated bioreactor (MABR). This research was conducted using a MABR design that consisted of a silicone membrane and continuous flow airline with compressed air. The membrane system was designed to supply oxygen, creating an aerated layer at the membrane-biofilm interface and an anoxic layer at the biofilm-water interface. Laboratory experiments were conducted to compare the nitrogen removal rates of natural bacteria alone to natural bacteria paired with Aqua. However, it was not possible to determine if a difference existed between the nitrogen removal rates of the MABR systems with only natural bacteria versus those with natural bacteria augmented with Aqua. The mean nitrogen removal rate observed when the media in the system reached steady state was 0.39 mg-N/L-hr. with a carbon to nitrogen (C: N) ratio of 12:1. The only increase in the nitrogen removal rate observed was when the C: N ratio was doubled to 24:1 and the nitrogen removal rate increased to 0.56 mg-N/L-hr.
Although it appeared that the Aqua did not have an influence on the nitrogen removal rate in the MABR systems, many other variables still need to be assessed to reach a conclusion. To improve the efficiency of the system more tubing should be added, or the glucose should be removed from the growth media because the maximum O2 mass transfer rate is only enough O2 for nitrification. The addition of glucose at 12:1 ratio increased the O2 demand in the system to be five times greater than the O2 supplied from the silicone tubing. This research determined that use of trace minerals, Aqua dosing method, and Aqua dosing concentration were not contributing factors in nitrogen removal from growth media under the conditions of this experiment.
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Zhao, Hong Wang. "Oxidation-reduction potential and organic carbon sources as two control parameters for simultaneous nitrification and denitrification in biological nutrient removal processes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0002/NQ27274.pdf.
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Murphy, Katelyn. "Comparing the Metcalf and Eddy and UCT steady state guidelines for sizing of biological nutrient removal activated sludge wastewater treatment plants." Master's thesis, Faculty of Engineering and the Built Environment, 2020. http://hdl.handle.net/11427/32851.
Full textAbstract:
This dissertation aims to provide both a qualitative and quantitative comparison of two steady state activated sludge (AS) design guidelines - the University of Cape Town (UCT) guideline used in South Africa and the Metcalf and Eddy (M&E) guideline used in North America and other parts of the world. It looks at the key similarities and differences between the two steady state AS design guidelines and how, under dynamic conditions, a system that is sized using a particular guideline (i) compares to its steady state results and (ii) performs under these dynamic conditions. In order to achieve the aims and objectives of this dissertation, an AS steady state model was created in a Microsoft Excel spreadsheet for the UCT guideline and M&E guideline respectively, and the models were analysed in terms of the key similarities and differences in the design guidelines in terms of inputs, equations, approaches and assumptions used. The results produced from each model were also analysed by setting the influent wastewater characteristics the same for each guideline and then analysing the results. The systems that were sized using the steady state AS models were then input into an AS system dynamic simulation software program, UCTOLD (which predicts virtually identical results as ASM1), together with a full set of diurnal influent data, to predict the behaviour of the system under steady state and dynamic conditions and compare the steady state predictions to those calculated in the steady state models and assess how the steady state model sized systems perform under dynamic loading conditions. The results of the analyses found that the two guidelines are similar in terms of organic material removal, nitrification and the sizing of the secondary settling tank, but differ significantly in the sizing of the anoxic reactor to achieve a certain nitrate removal. The key findings are: (1) Both UCT and M&E guidelines close the COD and N flux balances within 1%. (2) For organics removal only, at the same SRT, sludge production and oxygen demand are about 5% higher and lower respectively for the M&E guideline than the UCT guideline. When a UCT and M&E sized fully aerobic system is simulated with ASM1, this difference is repeated. The UCT guideline results are closely correlated with the ASM1 results but the M&E results deviate from those of ASM1. These differences arise because the M&E guideline assigns different values to the kinetic, stoichiometric and temperature sensitivity constants. If these constants in the M&E guideline are assigned the same values as the UCT guideline, virtually identical results are obtained. (3) For nitrification under fully aerobic conditions, the M&E guideline calculates a slightly shorter minimum aerobic SRT for nitrification than the UCT guideline. Again, the M&E guideline assigns different values to the nitrification kinetic (μAm20, bA20), stoichiometric (YA, Kn20) and temperature sensitivity constants (θμAm, θbA, θKn) than the UCT guideline. The M&E guideline calculates the minimum sludge age for nitrification, Rsm, using a fixed maximum specific growth rate of nitrifiers at 20oC (μAm20) at 0.90 g/(g.d), and after correcting for temperature, DO concentration in the aerobic reactor and assigning a safety factor (Sf = 1.5), the minimum sludge age for nitrification is slightly shorter than for the UCT guideline for a selected maximum specific growth rate of nitrifiers at 20oC (μAm20) of 0.45 g/(g.d) and assigning Sf = 1.25. In the M&E guideline the mass of nitrifiers is added to the reactor MLSS concentration which increases the MLSS mass in the reactor by about 1-3%. This is not done in the UCT guideline to maintain the COD balance for organics removal. At the same SRT in a fully aerobic system (i.e. aerobic SRT = system SRT), the oxygen demand for nitrification is closely similar in the two guidelines. This is because the calculated concentrations of nitrate produced by nitrification (called nitrification capacity Nc in the UCT guideline) are closely similar – the difference in the sludge production of the two guideline make little difference to the N taken up for sludge production. (4) If fully aerobic nitrifying reactors sized with the M&E and UCT guidelines are simulated with ASM1 at the same SRT, the same differences as with organic removal are observed. Hence the main difference in the sizing for nitrification in fully aerobic reactors in the two guidelines is the shorter aerobic SRT for nitrification in the M&E guideline (as a result of the different nitrification kinetics and safety factors) than in the UCT guideline. (5) Significant differences between the two guidelines emerge when adding an anoxic reactor for denitrification, such as for the anoxic aerobic nitrification - denitrification (ND) Modified Ludzack-Ettinger (MLE) system. This is because (5.1) the nitrifiers are assumed to behave differently under anoxic conditions in the two guidelines and (5.2) the effective specific denitrification rates of the OHO biomass in the anoxic reactor are much higher in the M&E guideline than in the UCT guideline. (6) With regard to difference (5.1), in the UCT guideline, the nitrifiers are assumed to grow only in the aerobic reactor but die in both the anoxic and aerobic reactors. In the M&E guideline, the nitrifiers are assumed to die (and grow) only in the aerobic reactor, i.e. they neither grow nor die in the anoxic reactor. Hence in the M&E guideline, the MLE system is sized based on an aerobic SRT, which excludes the mass of sludge in the anoxic reactor as in (3) above, but in the UCT guideline the MLE system is sized based on a system SRT, which includes the mass of sludge in the anoxic reactor. (7) With regard to difference (5.2), the faster specific denitrification rate determined with the M&E guideline yield much smaller anoxic reactors by at least 50% to achieve the same nitrate removal. (8) The consequence of these two differences is that the system SRT of the MLE system determined with the UCT guideline is considerably longer than that determined with the M&E guideline leading to larger anoxic, aerobic and system reactor volumes. This difference widens as the influent TKN/COD concentration ratio increases, i.e. as the concentration of nitrate to be denitrified increases. (9) When simulating the UCT sized MLE systems (under steady state conditions) with ASM1, very similar reactor MLVSS and MLSS concentration, effluent ammonia and nitrate concentrations and total oxygen demands are obtained with ASM1 and the UCT guideline. This indicates that the denitrification kinetics of the UCT guideline are well aligned with ASM1. This is not the case when simulating with ASM1 M&E guideline sized MLE systems under steady state conditions – while the effluent ammonia concentration compares well, the effluent nitrate concentration is far higher (increases from 6 mgNO3-N/l to above 20 mgNO3-N/l). This indicates that even though the denitrification kinetics of the M&E guideline were derived in part from ASM1 simulations, the denitrification kinetics of the M&E guideline are very poorly aligned with ASM1. (10) When the fmanx,M&E of the denitrification MLE system in (9) is increased to fmanx,UCT of 0.318 (but keeping the SRT = SRTsys,M&E) and simulated with ASM1, the effluent nitrate concentrations reduce from around 20 mgNO3-N/ℓ to around 6 mgNO3-N/ℓ, which is aligned with the UCT guideline ASM1 results. (11) The enhanced biological phosphorus removal (EBPR) parts of the UCT and M&E guidelines were not compared. While the EBPR part of the UCT guideline is complete and accounts for the phosphorus accumulating organisms (PAO) and their polyphosphorus content in the VSS and TSS calculations, as well as the differences in the denitrification kinetics in NDEBPR system compared with ND systems, which aligns the UCT NDEBPR guideline with ASM2, this is not the case in the M&E guideline. Because there is insufficient information in the M&E guideline to execute a complete NDEBPR system design calculation, the EBPR parts of the guidelines could not be compared. (12) The M&E overflow rates can be aligned with the UCT 1DFT to determine very similar SST surface areas. The lower resultant reactor MLSS of the M&E sized systems when simulated with ASM1 means that the SSTs will operate at a lower than designed for MLSS and thus under peak conditions (fq is 2.5 or greater) the SST will operate at a higher than permissible overflow rate. This is because the M&E SST sizing procedure does not include a 1DFT flux rating of 0.80 (as the UCT guideline does), which has the effect of increasing the SST surface area estimated by the 1DFT by 25%.
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Van, Lierde Patrick G. "Nucleation, milk and membranes as modifications to enhance biological phosphorus removal in activated sludge." Thesis, Loughborough University, 2015. https://dspace.lboro.ac.uk/2134/16784.
Full textAbstract:
Enhanced biological phosphorus removal (EBPR) was researched from the performance of a modified University of Cape Town (UCT), anaerobic-anoxic/nitrifying-aerobic process. The work focussed on high P influent where milk was compared to carbohydrates as exogenous added carbon and typical settled sewage. The results confirmed that at equal COD load in the influent (minimum COD:P (250:5) ratio for EBPR), milk always provided sufficient soluble substrate than the carbohydrate mix, but also improved the EBPR performance. The laboratory scale treated 10L/day where 2 parallel treatment trains for milk and an equivalent carbohydrate mix as supplement to compare and study the P sequestration from hypothesised P ligands in milk and easily assimilable carbon (AOM) after fermentation for biological P uptake. The aerobic bioreactors used submerged flat sheet membranes (AeMBR) to improve the effluent quality and reduce the suspended solid residues. The results suggested extra benefits from adding calcium chloride (CaCl2) (200 ml at 250 mM/day or 200 mg/L treated) to form P complexes both in the anaerobic and aerobic zones (100 ml CaCl2 250mM/zone/day). To complete P removal a calcium phosphate (CaPO4) further treatment stage (post membrane final effluent (F.E.)) was added for nucleation. The combination of, A2O-N, exogenous carbon and calcium addition improved the performance of the EBPR, and enabled the laboratory units to achieve less than the 1 mg/L P required by the EU Directive. The process was tested at higher than normal P loads (maximum 100 mg/L) (domestic wastewater influent 15 mg/L). Experiments with influent P load ≤ 50mg/L, with 1% milk as AOM were compared to the carbohydrate mix and could remove soluble P to less than 1mg/L above 97% and less than 2 mg/L more than 99% of the in the time respectively. With an influent P load of 60mg/L (maximum 100 mg/L), the soluble P in the F.E. with milk was below 5 mg/L and below 8 mg/L with carbohydrates mix. The results showed that most of the phosphorus was retained by the sludge during the anoxic-aerobic phases. The remaining phosphate in the F.E. was able to pass through AeMBR pore size (0.4 μm) and needed to be chelated by the nucleation process. The results indicated this A2O-N modifications achieved stable nutrient removal and also offered the potential for more sustainable phosphorus recovery. The EBPR without AOM was 25% less efficient compared to milk and never achieved the E.U standard of 1mg/L in final effluent. The flat sheet membrane always achieved a NTU final effluent below 1 and the TOC always greater than 90% removal or less than the EU 125 standard regardless of the feeding COD/P ratio.