Sponge iron(s-Fe°)is a porous metal with the potential to be an electron donor for denitrification.This study aims to evaluate the feasibility of using s-Fe as the substrate of wetland mesocosms.Here,wetland meso...Sponge iron(s-Fe°)is a porous metal with the potential to be an electron donor for denitrification.This study aims to evaluate the feasibility of using s-Fe as the substrate of wetland mesocosms.Here,wetland mesocosms with the addition of s-Fe"particles(CW-Fc)and a blank control group(CW-CK)were established.The NOj-N reduction property and water quality parameters(pH.DO.and ORP)were examined at three COD/N ratios(0.5.and 10).Results showed that the NO3--N removal efficiencies were significantly increased by 6.6 to 58.9%in the presence of s-Fe NH4+-N was mainly produced by chemical denitrification,and approximately 50% of the NO3--N was reduced to N4+-N,at the COD ratio of 0.An increase of the influent COD/N ratio resulted in lower chemical denitrification and higher bio-dcnitrification.Although chemical denitrification mediated by s-Fe led to an accumulation of NH4+-N at COD/N ratios of 0 and 5.the TIN removal efficiencies increased by 4.5#12.4#.Moreover,the effluent pll,DO.and ORP values showed a significant negative correlation with total Fe and Fe(II)(P<0.01).High-throughput sequencing analysis indicated that Trichococctis(77.2%)was the most abundant microorganism in the CW-Fc mcsocosm,while Thauera,Zoogloea.and Herbaspirillum were the primary denitrifying bacteria.The denitrifiers,Simplicispira,IXxhloronwnas,and Denirratisoma.were the dominant bacteria for CW-CK.This study provides a valuable method and an improved understanding of NOj-N reduction characteristics of s-Fc in a wetland mcsocosm.展开更多
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
基金This work was supported by the the National Natural Science Foundation of China(Grant Nos.51679041 and 51909034)the Fundamental Research Funds for the Central Universities(Grant Nos.2232019D3-21 and 2232018D3-22)+3 种基金the China Postdoctoral Science Foundation(No.2018M641894)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(Nos.CUSF-DH-D-2019079 and CUSF-DH-D-2019080)Shanghai Sailing Program(No.19YF1401900)Shanghai Rising-Star Program(No.19QC1401100).
文摘Sponge iron(s-Fe°)is a porous metal with the potential to be an electron donor for denitrification.This study aims to evaluate the feasibility of using s-Fe as the substrate of wetland mesocosms.Here,wetland mesocosms with the addition of s-Fe"particles(CW-Fc)and a blank control group(CW-CK)were established.The NOj-N reduction property and water quality parameters(pH.DO.and ORP)were examined at three COD/N ratios(0.5.and 10).Results showed that the NO3--N removal efficiencies were significantly increased by 6.6 to 58.9%in the presence of s-Fe NH4+-N was mainly produced by chemical denitrification,and approximately 50% of the NO3--N was reduced to N4+-N,at the COD ratio of 0.An increase of the influent COD/N ratio resulted in lower chemical denitrification and higher bio-dcnitrification.Although chemical denitrification mediated by s-Fe led to an accumulation of NH4+-N at COD/N ratios of 0 and 5.the TIN removal efficiencies increased by 4.5#12.4#.Moreover,the effluent pll,DO.and ORP values showed a significant negative correlation with total Fe and Fe(II)(P<0.01).High-throughput sequencing analysis indicated that Trichococctis(77.2%)was the most abundant microorganism in the CW-Fc mcsocosm,while Thauera,Zoogloea.and Herbaspirillum were the primary denitrifying bacteria.The denitrifiers,Simplicispira,IXxhloronwnas,and Denirratisoma.were the dominant bacteria for CW-CK.This study provides a valuable method and an improved understanding of NOj-N reduction characteristics of s-Fc in a wetland mcsocosm.
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...
