By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating paramet...By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating parameters of the combined process. The process involved advantages and shortages of SBR and CW. Under normal temperature, the 3rd cycle (SBR’s operation cycle is 8 h: inflow for 1 h, limited aeration for 3 h, sediment for 1 h, outflow for 1 h, and idling for 2 h; CW’s hydraulic retention time (HRT) is 24.8 h and hydraulic loading is 24.5 m3/m2 d) was the best cyclic mode. The effluents can meet the standard GB/T18921-2002: "The reuse of urban recycling water: water quality standard for scenic environment use". In the 3rd cycle, the efficiency of CW was the maximum, and energy consumption of SBR was the minimum. Under the condition of low dissolved oxygen, the removing efficiency of chemical oxygen demand (COD) and ammonia was not affected obviously. Simultaneously, nitrification and denitrification phenomena occured and phosphorus was absorbed obviously.展开更多
Wastewater treatment is a complicated dynamic process affected by microbial, chemical and physical factors. Faults are inevitable during the operation of modified sequencing batch reactors(MSBRs) because of the uncert...Wastewater treatment is a complicated dynamic process affected by microbial, chemical and physical factors. Faults are inevitable during the operation of modified sequencing batch reactors(MSBRs) because of the uncertainty of various factors. Abnormal MSBR results require fault diagnosis to determine the cause of failure and implement appropriate measures to adjust system operations. Bayesian network(BN) is a powerful knowledge representation tool that deals explicitly with uncertainty. A BN-based approach to diagnosing wastewater treatment systems based on MSBR is developed in this study. The network is constructed using the knowledge derived from literature and elicited from experts, and it is parametrized using independent data from a pilot test.A one-year pilot study is conducted to verify the diagnostic analysis. The proposed model is reasonable, and the diagnosis results are accurate. This approach can be applied with minimal modifications to other types of wastewater treatment plants.展开更多
In order to improve the nitrogen removal efficiency and save operational cost,the feasibility of the alternating aerobic-anoxic process(AAA process)applied in a sequencing batch reactor(SBR)system for nitrogen removal...In order to improve the nitrogen removal efficiency and save operational cost,the feasibility of the alternating aerobic-anoxic process(AAA process)applied in a sequencing batch reactor(SBR)system for nitrogen removal was investigated.Under sufficient influent alkalinity,the AAA process did not have an advantage over one aerobic-anoxic(OAA)cycle on treatment efficiency because microorganisms had an adaptive stage at the alternating aerobic-anoxic transition,which would prolong the total cycling time.On the contrary,the AAA process made the system control more complicated.Under deficient influent alkalinity,when compared to OAA,the AAA process improved treatment efficiency and effluent quality with NH4+-N in the effluent below the detection limit.In the nitrification,the average stoichiometric ratio between alka-linity consumption and ammonia oxidation is calculated to be 7.07 mg CaCO_(3)/mg NH4+-N.In the denitrification,the aver-age stoichiometric ratio between alkalinity production and N_(3)^(−)-N reduction is about 3.57 mg CaCO(3)/mg NO_(3)^(−)-N.As a result,half of the alkalinity previously consumed during the aerobic nitrification was recovered during the subsequent anoxic denitrification period.That was why the higher treat-ment efficiency in the AAA process was achieved without the supplement of bicarbonate alkalinity.If the lack of alkalinity in the influent was less than 1/3 of that needed,there is no need for external alkalinity addition and treatment efficiency was the same as that under sufficient influent alkalinity.Even if the lack of alkalinity in the influent was more than 1/3 of that needed,the AAA process was an optimal strategy because it reduced the external alkalinity addition and saved on operational cost.展开更多
基金Funded by Sustainable Water Management Improves Tomorrow’s City’s Health (SWITCH018530)
文摘By combining sequencing batch reactor (SBR) activated sludge process and constructed wetland (CW), this study is to achieve the domestic wastewater treatment. Our purpose was to determine the optimum operating parameters of the combined process. The process involved advantages and shortages of SBR and CW. Under normal temperature, the 3rd cycle (SBR’s operation cycle is 8 h: inflow for 1 h, limited aeration for 3 h, sediment for 1 h, outflow for 1 h, and idling for 2 h; CW’s hydraulic retention time (HRT) is 24.8 h and hydraulic loading is 24.5 m3/m2 d) was the best cyclic mode. The effluents can meet the standard GB/T18921-2002: "The reuse of urban recycling water: water quality standard for scenic environment use". In the 3rd cycle, the efficiency of CW was the maximum, and energy consumption of SBR was the minimum. Under the condition of low dissolved oxygen, the removing efficiency of chemical oxygen demand (COD) and ammonia was not affected obviously. Simultaneously, nitrification and denitrification phenomena occured and phosphorus was absorbed obviously.
基金the Foundation of State Key Laboratory of Ocean Engineering of Shanghai Jiao Tong University(No.GKZD010071)
文摘Wastewater treatment is a complicated dynamic process affected by microbial, chemical and physical factors. Faults are inevitable during the operation of modified sequencing batch reactors(MSBRs) because of the uncertainty of various factors. Abnormal MSBR results require fault diagnosis to determine the cause of failure and implement appropriate measures to adjust system operations. Bayesian network(BN) is a powerful knowledge representation tool that deals explicitly with uncertainty. A BN-based approach to diagnosing wastewater treatment systems based on MSBR is developed in this study. The network is constructed using the knowledge derived from literature and elicited from experts, and it is parametrized using independent data from a pilot test.A one-year pilot study is conducted to verify the diagnostic analysis. The proposed model is reasonable, and the diagnosis results are accurate. This approach can be applied with minimal modifications to other types of wastewater treatment plants.
基金This work was supported by the National Nature Science Foundation of China(Grant No.50608001)Beijing Education Committee(Grant No.KM200710005014).
文摘In order to improve the nitrogen removal efficiency and save operational cost,the feasibility of the alternating aerobic-anoxic process(AAA process)applied in a sequencing batch reactor(SBR)system for nitrogen removal was investigated.Under sufficient influent alkalinity,the AAA process did not have an advantage over one aerobic-anoxic(OAA)cycle on treatment efficiency because microorganisms had an adaptive stage at the alternating aerobic-anoxic transition,which would prolong the total cycling time.On the contrary,the AAA process made the system control more complicated.Under deficient influent alkalinity,when compared to OAA,the AAA process improved treatment efficiency and effluent quality with NH4+-N in the effluent below the detection limit.In the nitrification,the average stoichiometric ratio between alka-linity consumption and ammonia oxidation is calculated to be 7.07 mg CaCO_(3)/mg NH4+-N.In the denitrification,the aver-age stoichiometric ratio between alkalinity production and N_(3)^(−)-N reduction is about 3.57 mg CaCO(3)/mg NO_(3)^(−)-N.As a result,half of the alkalinity previously consumed during the aerobic nitrification was recovered during the subsequent anoxic denitrification period.That was why the higher treat-ment efficiency in the AAA process was achieved without the supplement of bicarbonate alkalinity.If the lack of alkalinity in the influent was less than 1/3 of that needed,there is no need for external alkalinity addition and treatment efficiency was the same as that under sufficient influent alkalinity.Even if the lack of alkalinity in the influent was more than 1/3 of that needed,the AAA process was an optimal strategy because it reduced the external alkalinity addition and saved on operational cost.
