Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal(BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, a...Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal(BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic(A2 /O). The ASM2 d implemented on the platform of WEST2011 software and the Bio Win activated sludge/anaerobic digestion(AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2 d parameters(the reduction factor for denitrification(η NO3, H), the maximum growth rate of heterotrophs( μ H), the rate constant for stored polyphosphates in PAOs(q pp), and the hydrolysis rate constant(k h)) were adjusted. Whereas three Bio Win parameters(aerobic decay rate(b H), heterotrophic dissolved oxygen(DO) half saturation(K OA), and Y P /acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations(ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen(N-NO3), total nitrogen(TN), and total phosphorus(TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand(COD) to total Kjeldahl nitrogen(TKN) ratio(COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.展开更多
Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the effect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor...Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the effect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor. Results showed that at substrate COD/N of 5, organic and nitrogen could be eliminated simultaneously, and COD removal degree, nitrification and denitrification efficiency reached 85%, 93% and 92%, respectively. With increasing substrate COD/N ratios, the specific oxygen utilization rates of nitrifying bacteria in biofilm were found to decrease, indicating that nitrifying population became less dominant. At substrate COD/N ratio of 6, excessive heterotrophs inhibited the activity of nitrifying bacteria greatly and thus led to poor nitrification process. With the help of fluorescence in situ hybridization （FISH）, Nitrosomonas and Nitrosospira were identified as dominant ammonia-oxidizing bacteria in the biofilm at substrate COD/N of 0, whereas only Nitrosospira were detected in the biofilm at COD/N ratio of 5. Nitrospira were present as dominant nitrite-oxidizing bacteria in our study. Confocal laser scanning microscopy images revealed that at substrate COD/N ratio of 0 nitrifying bacteria existed throughout the biofilm and that at COD/N ratio of 5 they were mainly distributed in the inner layer of biofilm.展开更多
The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membra...The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...展开更多
To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. A...To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. Acetate,propionate and a mixture of acetate and propionate at a ratio of 3 ∶ 1( COD basis) was used as carbon sources with the COD / P of 20,15,10 and 5. 0 g COD /gP,respectively. The minimum COD / P ratios for complete P removal were found to be 8. 24 g COD /gP for acetate,11. 40 g COD /gP for propionate and9. 10 g COD /gP for the 3 ∶ 1 mixture of acetate and propionate. Converted to a mass basis,all three cases had a very similar ratio of 7. 7 g VFA /gP,which represented a useful guide for operation of EBPR plants to identify possible shortages in VFAs. The trend in PHV accumulation during the anaerobic period along with the decrease of COD / P ratios suggested that,PAOs may use the TCA pathway for anaerobic VFA uptake to maintain the required NADH production with reduced glycogen degradation. During the aerobic phase,the glycogen pool was reduced but remained enough compared to the requirement for anaerobic VFA uptake,and the synthesis and degradation of glycogen was not the inhibition factor of PAOs.展开更多
In order to investigate the change of ecological characteristics due to the decrease of COD/SO_4^(2-) ratio during sulfate reduction, continuous-flew tests were conducted in an acidogenic sulfate-reducing reactor with...In order to investigate the change of ecological characteristics due to the decrease of COD/SO_4^(2-) ratio during sulfate reduction, continuous-flew tests were conducted in an acidogenic sulfate-reducing reactor with molasses wastewater as sole organic carbon source and sodium snlfate as electron acceptor, and the change of pH value, oxidation reduction potential (ORP), volatile fat acids (VFAs), alkalinity (ALK) and the predominant populations with COD/SO_4^(2-) ratio decreasing from 4.2 to 2.0 were investigated. The experimental results demonstrated that, with decreasing COD/SO_4^(2-) ratio, ORP and ALK increased, pH value decreased, and the proportion of acetic acid in terminal products decreased significantly, and a stable -type microbial community with high COD/SO_4^(2-) ratio was converted into a sub -stable -type one with low COD/SO_4^(2-) ratio.展开更多
基金Supported by the College of Scientific Innovation Significant Cultivation Fund Financing Projects(No.708047)the Key Special Program for the Pollution Control(No.2012ZX07101-003)+1 种基金the National Natural Science Foundation of China(No.51208173)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal(BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic(A2 /O). The ASM2 d implemented on the platform of WEST2011 software and the Bio Win activated sludge/anaerobic digestion(AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2 d parameters(the reduction factor for denitrification(η NO3, H), the maximum growth rate of heterotrophs( μ H), the rate constant for stored polyphosphates in PAOs(q pp), and the hydrolysis rate constant(k h)) were adjusted. Whereas three Bio Win parameters(aerobic decay rate(b H), heterotrophic dissolved oxygen(DO) half saturation(K OA), and Y P /acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations(ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen(N-NO3), total nitrogen(TN), and total phosphorus(TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand(COD) to total Kjeldahl nitrogen(TKN) ratio(COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.
基金supported by the National Science Council of China (No.50578023)
文摘Two parallel carbon-membrane aerated biofilm reactors were operated at well-defined conditions to investigate the effect of substrate COD/N ratios on the performance and microbial community structure of the bioreactor. Results showed that at substrate COD/N of 5, organic and nitrogen could be eliminated simultaneously, and COD removal degree, nitrification and denitrification efficiency reached 85%, 93% and 92%, respectively. With increasing substrate COD/N ratios, the specific oxygen utilization rates of nitrifying bacteria in biofilm were found to decrease, indicating that nitrifying population became less dominant. At substrate COD/N ratio of 6, excessive heterotrophs inhibited the activity of nitrifying bacteria greatly and thus led to poor nitrification process. With the help of fluorescence in situ hybridization （FISH）, Nitrosomonas and Nitrosospira were identified as dominant ammonia-oxidizing bacteria in the biofilm at substrate COD/N of 0, whereas only Nitrosospira were detected in the biofilm at COD/N ratio of 5. Nitrospira were present as dominant nitrite-oxidizing bacteria in our study. Confocal laser scanning microscopy images revealed that at substrate COD/N ratio of 0 nitrifying bacteria existed throughout the biofilm and that at COD/N ratio of 5 they were mainly distributed in the inner layer of biofilm.
文摘The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...
基金Sponsored by the National Natural Science Foundation of China(Grant No.51278143,51408162)the Postdoctoral Foundation of China(Grant No.2013M530161)
文摘To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. Acetate,propionate and a mixture of acetate and propionate at a ratio of 3 ∶ 1( COD basis) was used as carbon sources with the COD / P of 20,15,10 and 5. 0 g COD /gP,respectively. The minimum COD / P ratios for complete P removal were found to be 8. 24 g COD /gP for acetate,11. 40 g COD /gP for propionate and9. 10 g COD /gP for the 3 ∶ 1 mixture of acetate and propionate. Converted to a mass basis,all three cases had a very similar ratio of 7. 7 g VFA /gP,which represented a useful guide for operation of EBPR plants to identify possible shortages in VFAs. The trend in PHV accumulation during the anaerobic period along with the decrease of COD / P ratios suggested that,PAOs may use the TCA pathway for anaerobic VFA uptake to maintain the required NADH production with reduced glycogen degradation. During the aerobic phase,the glycogen pool was reduced but remained enough compared to the requirement for anaerobic VFA uptake,and the synthesis and degradation of glycogen was not the inhibition factor of PAOs.
基金Sponsored by the National Natural Science Foundation of China(Grant No. 50208006)the Scientific Research Foundation of Harbin Institute of Technology(Grant No. HIT. 2001.51)
文摘In order to investigate the change of ecological characteristics due to the decrease of COD/SO_4^(2-) ratio during sulfate reduction, continuous-flew tests were conducted in an acidogenic sulfate-reducing reactor with molasses wastewater as sole organic carbon source and sodium snlfate as electron acceptor, and the change of pH value, oxidation reduction potential (ORP), volatile fat acids (VFAs), alkalinity (ALK) and the predominant populations with COD/SO_4^(2-) ratio decreasing from 4.2 to 2.0 were investigated. The experimental results demonstrated that, with decreasing COD/SO_4^(2-) ratio, ORP and ALK increased, pH value decreased, and the proportion of acetic acid in terminal products decreased significantly, and a stable -type microbial community with high COD/SO_4^(2-) ratio was converted into a sub -stable -type one with low COD/SO_4^(2-) ratio.
