Optimization of biological nutrient removal in a pilot plant UCT-MBR treating municipal wastewater during start-up (original) (raw)
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Bioresource Technology, 2010
The performance of an MBR pilot plant for biological nutrient removal was evaluated during 210 days of operation. The set point values for the internal recycles were determined in advance with the use of an optimisation spreadsheet based on the ASM2d model to optimise the simultaneous removal of C, N and P. The biological nutrient removal (BNR) efficiencies were high from the start of operation with COD and N removal efficiencies of 92 ± 6% and 89 ± 7, respectively. During the course of the experiment P removal efficiencies increased and finally a P-removal efficiency of 92% was achieved. The activity of poly-phosphate accumulating organisms (PAOs) and denitrifying poly-phosphate accumulating organisms (DPAOs) increased and the specific phosphate accumulation rates after 150 days of operation amounted to 13.6 mg P g À1 VSS h À1 and 5.6 mg P g À1 VSS h À1 , for PAOs and DPAOs, respectively.
Bioresource Technology, 2009
The performance of a pilot-scale biological nutrient removal process has been evaluated for 336 days, receiving the real municipal wastewater with a flowrate of 6.8 m 3 /d. The process incorporated an intermittent aeration reactor for enhancing the effluent quality, and a nitrification reactor packed with the porous polyurethane foam media for supporting the attached-growth of microorganism responsible for nitrification. The observation shows that the process enabled a relatively stable and high performance in both organics and nutrient removals. When the SRT was maintained at 12 days, COD, nitrogen, and phosphorus removals averaged as high as 89% at a loading rate of 0.42-3.95 kg COD/m 3 d (corresponding to average influent concentration of 304 mg COD/L), 76% at the loading rate of 0.03-0.27 kg N/m 3 d (with 37.1 mg TN/L on average), and 95% at the loading rate of 0.01-0.07 kg TP/m 3 d (with 5.4 mg TP/L on average), respectively.
MATEC Web of Conferences
Water utilities, commercial and industrial establishments are required to upgrade or install new treatment systems to comply with the revised effluent standards issued by the Department of Environment and Natural Resources – Environment Management Bureau (DENR – EMB) which now includes removal and monitoring of nutrients (nitrogen and phosphorus components). One solution is to utilize a biological nutrient removal technology (BNRT) system capable of removing nutrients from sewage. The on-going study aims to investigate the performance of the pilot-scale system in the removal of nutrients from sewage. The designed pilot-scale anaerobic-anoxic-oxic (A2O) process with a total hydraulic retention time of 8.37 hrs. was operated in an existing sewage treatment plant (STP). System modification was adapted to ensure continuous operation. Dissolved oxygen (DO) and temperature of each compartment were evaluated after 45 days of system modification. The DO of the anaerobic and oxic compartment...
Comparative Assessment of a Novel MBR and A2O for Biological Nutrient Removal
Proceedings of the Water Environment Federation, 2008
A comparative study between two biological nutrient removal (BNR) systems i.e. one employing membranes and the other conventional A2O system was conducted at the hydraulic retention time (HRT) and solids retention time (SRT) of 8 h and 10 d respectively using synthetic wastewater (SWW) and municipal wastewater (MWW) which contains 30% of the volatile fatty acid (VFA) of the SWW. Achieved COD, N and P removal efficiencies for the MBR were 95-98, 72-75 and 70-91%, respectively, compared to 95-98, 70-76 and 70-77% for the A2O. It was confirmed that the primary factor governing P removal is VFA concentration. Accordingly, the contribution of denitrifying phosphorus accumulating organisms (DPAOs) to P removal was greatly hampered. However, the impact of an intermediate clarifier P removal in the MBR was significant for both SWW and MWW runs.
Water science and technology : a journal of the International Association on Water Pollution Research, 2002
In this paper the advantages and disadvantages of denitrifying PAOs (polyphosphate accumulating organisms) in conventional BNRAS (biological nutrient removal activated sludge) and external nitrification BNRAS (ENBNRAS) systems are evaluated, with experimental data exhibiting a range of anoxic P uptake from low (<10%) to very high (>60%). The results indicate that the specific denitrification rate of the PAOs on internally stored PHB COD is about 1/5th of that of the "ordinary" heterotrophic organisms on SBCOD, and the PAOs contribute little (maximum 20%) to the denitrification in BNRAS systems even when the anoxic P uptake is high (60% of the total P uptake). Considering the unpredictable nature of anoxic P uptake and the reduction in BEPR it causes compared with aerobic P uptake BEPR, it is concluded that anoxic P uptake does not add a significant advantage to the BNR system.
Effect of solids retention time and wastewater characteristics on biological phosphorus removal
Water science and technology : a journal of the International Association on Water Pollution Research, 2002
The paper deals with the effect of wastewater, plant design and operation in relation to biological nitrogen and phosphorus removal and the possibilities to model the processes. Two Bio-P pilot plants were operated for 2.5 years in parallel receiving identical wastewater. The plants had SRT of 4 and 21 days, the latter had nitrification and denitrification. The plant with 4 days SRT had much more variable biomass characteristics, than the one with the high SRT. The internal storage compounds, PHA, were affected significantly by the concentration of fatty acids or other easily degradable organics in the wastewater, and less by the plant lay-out. The phosphorus removal is mainly dependent on availability in the wastewater of fatty acids but also by the suspended solids in the effluent, which is higher in the plant with nitrification-denitrification, probably due to a higher SVI or denitrification in the settler. The addition of glucose to the influent seems to have an effect on the pe...
Biological Nutrient Removal in Municipal Wastewater Treatment: New Directions in Sustainability
Journal of Environmental Engineering, 2012
To control eutrophication in receiving water bodies, biological nutrient removal (BNR) of nitrogen and phosphorus has been widely used in wastewater treatment practice, both for the upgrade of existing wastewater treatment facilities and the design of new facilities. However, implementation of BNR activated sludge AS systems presents challenges attributable to the technical complexity of balancing influent chemical oxygen demand (COD) for both biological phosphorus (P) and nitrogen (N) removal. Sludge age and aerated/unaerated mass fractions are identified as key parameters for process optimization. Other key features of selected BNR process configurations are discussed. Emerging concerns about process sustainability and the reduction of carbon footprint are introducing additional challenges in that influent COD, N, and P are increasingly being seen as resources that should be recovered, not simply removed. Energy recovery through sludge digestion is one way of recovering energy from influent wastewater but which presents a specific challenge for BNR: generation of sidestreams with high nutrient and low COD loads. Technologies designed specifically to treat these side-stream loads are overviewed in this paper. Finally, relatively high levels of nitrous oxide emissions, a powerful greenhouse gas, have been shown to occur in the BNR process under certain conditions, particularly in the presence of high nitrite concentrations. The advantages of using process modeling tools is discussed in view of optimizing BNR processes to meet effluent requirements and to meet goals of sustainability and reducing carbon footprints.
Water Environment Research, 2009
In this study, biological treatment performances of two parallel treatment lines operating with and without primary sedimentation were investigated. The research was carried out in a large-scale enhanced biological phosphorus removal (EBPR) process. Influent and effluent of treatment lines were characterized continuously during the study. In addition, anaerobic anoxic and aerobic EBPR activities were investigated by batch tests using fresh activated sludge samples. All of the environmental and operational conditions of the treatment lines were statistically compared. Evaluation of effluent compositions indicated that EBPR performances of treatment lines were significantly different. Results of the research also indicated that settling characteristics of the activated sludge process could be improved significantly with increasing particulate biodegradable organic compound (pbCOD) loading rate. Batch test results revealed that anaerobic, anoxic, and aerobic biochemical reaction rates of activated sludge cultivated on increased pbCOD loading rate were significantly higher compared to activated sludge cultivated on soluble substrate forms. Water Environ. Res., 81, 886 (2009).
Effects of MCRT on Enhanced Biological Phosphorus Removal
Water Science and Technology, 1992
This paper presents the results of full scale experimental investigations into the fate of phosphorus in the Hyperion Treatment Plant, City of Los Angeles, CA, USA. For almost three decades, the activated sludge process, operated at standard rate has exhibited enhanced biological phosphate removal accompanied by initial anaerobic phosphate release and subsequent aerobic phosphate uptake. In 1989 when high rate treatment was initiated the enhanced phosphate removal and accompanying initial anaerobic phosphate release decreased and finally was eliminated. Phosphorus in the secondary effluent increased from 0.4 to 3.1 mg/l as the MCRT decreased from 3.1 to 1.5 days. Of added interest was the accompanying decrease in struvite (MgNH4PO4.6H2O(s)) build-up in the sludge dewatering processes downstream of the anaerobic digesters.