Experimental Study and Mathematical Modeling of Enhanced Biological Phosphorus Removal Using Glucose as the Dominant Substrate PDF Download
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Author: Parnian Izadi
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Languages : en
Pages : 0
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Enhanced Biological Phosphorus Removal (EBPR), as a promising technology, has been implemented in many wastewater treatment plants (WWTP) worldwide, with high efficiency in phosphorus removal performance. In a well-operated EBPR, lower operational cost, reduced sludge production, and lower environmental impacts are achievable. Yet, with the proven capability of EBPR in efficient phosphorus removal, disturbance and periods of unexplained insufficient phosphorus removal have been detected in real WWTP in different cases due to loss of PAO biomass under presumed favorable conditions for EBPR. These complications may lead to process upset, system failure, and violation of discharge regulations. Disruption in process performance may originate from several external factors such as heavy rainfall, excessive nitrate loading to the anaerobic reactor, excessive aeration of activated sludge, or it may be a result of PAOs competition with other groups of microorganisms such as glycogen accumulating organisms (GAO). Therefore, the key in reaching low P-effluent levels is to optimize the operation and minimize the effect of inefficient factors. This Ph.D. study has focused on aeration as a crucial operational factor in the EBPR process in sequential batch reactor (SBR) systems. EBPR aerobic P-uptake, anaerobic P-release, and carbon storage of phosphorus accumulating organisms (PAOs) are closely related to oxygen mass transfer. The study is oriented to different aspects of aeration, addressing aeration concentration (dissolved oxygen (DO) concentration), aeration duration (aerobic hydraulic retention time (HRT)), and aeration pattern (continuous/intermittent). The performance of EBPR in SBRs under various aeration strategies was investigated for different DO concentrations (0.4-4 mg/L), HRT (120-320 minute), and aeration patterns of continuous and intermittent (25 to 50 minute on/off intermittent aeration/non-aeration intervals). Moreover, this study investigated the effect of reaching micro-aeration with adaptation strategies on EBPR performance. The development of steady and instant-DO reduction in different aeration strategies was studied in batch tests with enriched PAOs at different DO levels. Subsequently, comparative modeling using calibrated BioWin software was implemented for SBRs to predict the nutrient removal performance by changing DO concentration and the aerobic-HRT and understanding the effect of parameters on treatment performance to improve operation and control.
Author: Damir Brdanovic
Publisher: CRC Press
ISBN: 1000657981
Category : Science
Languages : en
Pages : 272
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This text looks at different effects on the process of biological phosphorus removal. Topics include: biological phosphorus removal processes; process and molecular ecological studies; and the effect of potassium limitation on biological phosphorus removal.
Author: Francisco Javier Rubio Rincon
Publisher: CRC Press
ISBN: 135164808X
Category : Technology & Engineering
Languages : en
Pages : 293
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The enhanced biological removal of phosphorus (EBPR) is a popular process due to high removal efficiency, low operational costs, and the possibility of phosphorus recovery. Nevertheless, the stability of the EBPR depends on different factors such as: temperature, pH, and the presence of toxic compounds. While extensive studies have researched the effects of temperature and pH on EBPR systems, little is known about the effects of different toxic compounds on EBPR. For example, sulphide has shown to inhibit different microbial activities in the WWTP, but the knowledge about its effects on EBPR is limited. Whereas the sulphide generated in the sewage can cause a shock effect on EBPR, the continuously exposure to sulphide potentially generated in WWTP can cause the acclimatization and adaptation of the biomass. This research suggests that sulphate reducing bacteria can proliferate in WWTP, as they are reversibly inhibited by the recirculation of sludge through anaerobic-anoxic-oxic conditions. The research enhances the understanding of the effect of sulphide on the anaerobic-oxic metabolism of PAO. It suggests that the filamentous bacteria Thiothrix caldifontis could play an important role in the biological removal of phosphorus. It questions the ability of PAO to generate energy from nitrate respiration and its use for the anoxic phosphorus uptake. Thus, the results obtained in this research can be used to understand the stability of the EBPR process under anaerobic-anoxic-oxic conditions, especially when exposed to the presence of sulphide.
Author: Rogelio Ernesto Zuniga Montanez
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Category :
Languages : en
Pages :
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Municipal wastewater contains a number of constituents that can have detrimental effects if discharged to receiving water bodies. Phosphorus (P) is of specific interest as a limiting nutrient in aquatic ecosystems that can cause eutrophication. In enhanced biological phosphorus removal (EBPR), polyphosphate accumulating organisms (PAOs) store excess P intracellularly. To achieve this accumulation, the organisms are exposed consecutively to anaerobic and either aerobic or anoxic conditions. During the anaerobic phase, PAOs consume and store organic carbon with P release, followed by the aerobic/anoxic phase during which the stored carbon is oxidized and P is taken up and stored as polyphosphate. PAOs are not the only bacteria that can thrive under these cyclic conditions and they face competition from glycogen accumulating organisms (GAOs). The latter have a similar metabolism but do not accumulate P. Most research to date has focused on the use of certain volatile fatty acids (VFAs) as carbon sources and on process conditions at temperatures common in temperate climates. Much remains unknown about the potential of EBPR in tropical regions and the suitability of other carbon substrates to drive the accumulation of phosphate. The purpose of this dissertation is to contribute to the understanding of EBPR at high temperatures and with unconventional carbon sources. Three different studies were designed and conducted with the following aims: (a) to evaluate the long-term EBPR stability and key microbial community in a wastewater treatment plant (WWTP) designed to achieve P removal in Singapore, (b) to study the process efficiency, biochemical transformations and organisms involved in a laboratory-scale EBPR reactor fed by alternating the substrates acetate and glutamate, and (c) to assess the potential of using unconventional carbon sources for EBPR by testing glutamate and glucose as alternating substrates at the laboratory-scale. The research included experiments at the full- and laboratory-scale, all at a mean temperature of 30 °C. Sustained observations in all three studies served to uncover the biochemical and microbial community dynamics. In the full-scale study, I conducted a yearlong evaluation of the EBPR activity at a WWTP that had been retrofitted to facilitate EBPR in Singapore. A mean P removal efficiency of 90 % was observed throughout the sampling period, similar to temperate climate installations and contrary to earlier reports that EBPR was not feasible at high temperatures. The main PAOs present in the reactor were Tetrasphaera, Candidatus Accumulibacter (Accumulibacter) and Dechloromonas, with mean relative abundances of 1.53, 0.43 and 0.69 %, respectively. The PAO community underwent changes during the surveyed period, with a marked transition from a Tetrasphaera-dominated community to a more even one. The link between PAOs and the P released in the anaerobic compartment was supported by a statistically significant correlation between the relative abundance of these organisms and the measured P concentrations. GAOs and PAOs coexisted without compromising the EBPR activity. In one of the laboratory-scale studies, glutamate and acetate were alternated as the carbon source for a reactor operated at 30 °C. Complete and stable P removal was achieved with a predominantly glutamate-containing feed, after modifying operating parameters commonly used in VFA-fed systems to a COD/P ratio of 40:1 mg COD/mg P and a cycle duration of 8 h. Long-term EBPR with a feed dominated by glutamate in a laboratory-scale reactor has not been previously reported. The P and carbon cycling patterns were different for glutamate and acetate. Reduced P release and polyhydroxyalkanoate (PHA) accumulation happened when glutamate was fed, but not with acetate, where glutamate appeared to be stored as an unidentified non-PHA compound or as different compounds. The PAO Accumulibacter and the GAO Candidatus Competibacter (Competibacter) remained the only known EBPR bacteria during the period of good EBPR performance, at similar relative abundances. A canonical correlation analysis revealed that the relative abundance of some non-PAO organisms correlated more strongly with variables that denoted good EBPR activity than did the abundance of any of the known PAOs. In the last study, a laboratory-scale sequencing batch reactor was used to test the EBPR potential of glutamate and glucose as alternating carbon sources in a high temperature process. The recommended influent COD/P ratio and batch duration for VFA-fed systems were unsuccessful. After modifications, COD/P ratios of 20:1 and 40:1 mg COD/ mg P resulted in complete P removal, but only in the short term. The EBPR stoichiometry with these two carbon substrates differed from that of VFA-fed systems. For both, lower P and PHA cycling was observed, and intracellular carbon storage compounds that were not PHA appeared to contribute to P cycling, as shown from carbon balances. A very diverse EBPR community was present in the reactor, including Accumulibacter, Tetrasphaera and Dechloromonas PAOs, and Competibacter, Defluviicoccus, Micropruina and Kineosphaera GAOs. Most of these organisms have not been reported before in laboratory-scale EBPR reactors operated at high temperatures. The work presented in this dissertation expands the understanding of EBPR by showing that the process is possible and stable in full-scale treatment plants at high temperature, with removal efficiencies similar to those observed in temperate climates. In addition, it was shown that unconventional carbon sources, specifically, glutamate and glucose, do participate in EBPR and that complete and stable phosphorus removal can be achieved with glutamate as dominant substrate at high temperature. A core PAO and GAO community was present in the three systems, where the interactions among members were more complex than previously considered, including competition, coexistence and succession events. The results obtained from this work enhance our fundamental knowledge of EBPR as an industrial process, as well as the metabolic diversity, niches and dynamics of PAOs and GAOs. The study outcomes can inform design and operational strategies at full-scale treatment plants. Lastly, the consideration of both high temperatures and unconventional carbon sources for EBPR is expected to aid in the development of more efficient treatment processes.
Author: Chang Hoon Ahn
Publisher:
ISBN:
Category :
Languages : en
Pages : 302
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Author: R. Ramadori
Publisher: Elsevier
ISBN: 1483160599
Category : Technology & Engineering
Languages : en
Pages : 405
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Biological Phosphate Removal from Wastewaters contains the proceedings of an International Association on Water Pollution Research and Control Specialized Conference held in Rome, Italy on September 28-30, 1987. Contributors review advances that have been made in the removal of biological phosphates from wastewaters, both at the fundamental scientific level and in the practical application of the process. Topics range from the fundamental microbiology and biochemistry of the enhanced biological removal of phosphate to the practical full-scale plant experiences with phosphorus removal and sludge handling from such processes. This text is comprised of 43 chapters; the first of which describes the utilization of polyphosphate as an energy reserve in Acinetobacter sp. and activated sludge. Attention then turns to metabolic control in polyphosphate-accumulating bacteria and its role in enhancing biological phosphate removal. The biochemistry and energetics of biological phosphorus removal are also considered. The next section is devoted to process modeling and includes chapters that explore the kinetics of biological excess phosphorus removal; factors affecting anaerobic stabilization during biological phosphorus removal; and the behavior of magnesium in biological phosphate removal. In the next section, bench/pilot-scale studies are presented; one of which investigated the reduction of returned phosphorus from a sludge treatment process. The book concludes with a discussion on phosphate removal mechanisms and pilot- and full-scale experiences. This book will be of interest to students, practitioners, and policymakers in water pollution control.
Author: Taylor & Francis Group
Publisher:
ISBN: 9781138373433
Category :
Languages : en
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Author: Liang-Ming Whang
Publisher:
ISBN:
Category :
Languages : en
Pages : 256
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