Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An （AO）^2 SBR （anaerobic...Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An （AO）^2 SBR （anaerobic-aerobic-anoxic-aerobic sequencing batch reactor） was thereby employed to enrich denitrifying phosphorus removal bacteria for simultaneously removing phosphorus and nitrogen via auoxic phosphorus uptake, Ammonium oxidation was controlled at the first phase of the nitrification process. Nitrite-inhibition batch tests illustrated that nitrite was not an inhibitor to phosphorus uptake process, but served as an alternative electron acceptor to nitrate and oxygen if the concentration was under the inhibition level of 40mg NO2 - N·L^- 1. It implied that in addition to the two well-accepted groups of phosphorus removal bacterium （ one can only utilize oxygen as electron acceptor, P1, while the other can use both oxygen and nitrate as electron acceptor, P2 ）, a new group of phosphorus removal bacterium P3, which could use oxygen, nitrate and nitrite as electron acceptor to take up phosphorus were identified in the test system. To understand （AO）^2 SBR sludge better, the relative population of the different bacteria in this system, plus another A/O SBR sludge （ seed sludge） were respectively estimated by the phosphorus uptake batch tests with either oxygen or nitrate or nitrite as electron acceptor. The results demonstrated that phosphorus removal capability of （AO）^2 SBR sludge had a little degradation after A/O sludge was cultivated in the （AO）^2 mode over a long period of time. However, deuitrifying phosphorus removal bacteria （ P2 and P3 ） was significantly enriched showed by the relative population of the three types of bacteria, which implied that energy for aeration and COD consumption could be reduced in theory.展开更多
Literatures revealed that the electron acceptor-nitrite could be inhibitory or toxic in the denitrifying phosphorus removal process. Batch test experiments were used to investigate the inhibitory effect during the ano...Literatures revealed that the electron acceptor-nitrite could be inhibitory or toxic in the denitrifying phosphorus removal process. Batch test experiments were used to investigate the inhibitory effect during the anoxic condition. The inoculated activated sludge was taken from a continuous double-sludge denitrifying phosphorus and nitrogen removal system. Nitrite was added at the anoxic stage. One time injection and sequencing batch injection were carried on in the denitrifying dephosphorus procedure. The results indicated that the nitrite concentration higher than 30 mg/L would inhibit the anoxic phosphate uptake severely,and the threshold inhibitory concentration was dependent on the characteristics of the activated sludge and the operating conditions; instead,lower than the inhibitory concentration would not be detrimental to anoxic phosphorus uptake,and it could act as good electron acceptor for the anoxic phosphate accumulated. Positive effects performed during the denitrifying biological dephosphorus all the time. The utility of nitrite as good electron acceptor would provide a new feasible way in the denitrifying phosphorus process.展开更多
Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor((AO)2 SBR). The system showed ...Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor((AO)2 SBR). The system showed stable phosphorus and nitrogen removal performance, and average removals for COD, TN and TP were 90%, 91% and 96%, respectively. The conditions of pH 7.5—8.0 and temperature 32℃ were found detrimental to nitrite oxidation bacteria but favorable to ammonia oxidizers, and the corresponding specific oxygen uptake rates(SOUR) for phase 1 and 2 of nitrification process were 0.7 and 15 mgO 2/(gVSS·h) in respect, which led to the nitrite accumulation in aerobic phase of(AO)2 SBR. Respiratory tests showed that 40 mgNO 2-N/L did not deteriorate the sludge activity drastically, and it implied that exposure of sludge to nitrite periodically enabled the biomass to have more tolerance capacity to resist the restraining effects from nitrite. In addition, batch tests were carried out and verified that denitrifying phosphorus accumulation organisms(DPAOs) could be enriched in a single sludge system coexisting with nitrifiers by introducing an anoxic phase in an anaerobic-aerobic SBR, and the ratio of the anoxic phosphate uptake capacity to aerobic phosphate uptake capacity was 45%. It was also found that nitrite(up to 20 mgNO 2-N/L) was not inhibitory to anoxic phosphate uptake and could serve as an electron acceptor like nitrate, but presented poorer efficiency compared with nitrate.展开更多
An anaerobic-oxic(A/O)biological phosphorus removal reactor was operated to study the effect of nitrite on phosphate uptake.The phosphorus uptake profile was determined under different operating conditions.The results...An anaerobic-oxic(A/O)biological phosphorus removal reactor was operated to study the effect of nitrite on phosphate uptake.The phosphorus uptake profile was determined under different operating conditions.The results indicated that in addition to oxygen and nitrate(DPB_(Na),nitrate denitrifying phosphorus removal),to some extent,nitrite could also serve as an electron acceptor to achieve nitrite denitrifying phosphorus removal(DPB_(Ni)).The quantity and rate of phosphorus uptake of DPBNi,however,were evidently lower than that of DPBNa.The experiment results revealed that nitrite would bring toxic action to phosphate-accumulating organisms(PAOs)when NO_(2)^(−)-Ni93.7 mg/L.The nitrite existing in the anoxic reactor made no difference to the quantity and rate of denitrifying phosphorus removal,but it could reduce the consumption of nitrate.Moreover,the data showed that the aerobic phosphate uptake of DPBNi was lower than that of anaerobic phosphorus-released sludge in a traditional A/O process.However,there was not much difference between these two kinds of sludge in terms of the total phosphorus uptake quantity and the effluent quality.展开更多
文摘Characteristics of phosphorus removal bacteria were investigated by using three different types of electron acceptors, as well as the positive role of nitrite in phosphorus removal process. An （AO）^2 SBR （anaerobic-aerobic-anoxic-aerobic sequencing batch reactor） was thereby employed to enrich denitrifying phosphorus removal bacteria for simultaneously removing phosphorus and nitrogen via auoxic phosphorus uptake, Ammonium oxidation was controlled at the first phase of the nitrification process. Nitrite-inhibition batch tests illustrated that nitrite was not an inhibitor to phosphorus uptake process, but served as an alternative electron acceptor to nitrate and oxygen if the concentration was under the inhibition level of 40mg NO2 - N·L^- 1. It implied that in addition to the two well-accepted groups of phosphorus removal bacterium （ one can only utilize oxygen as electron acceptor, P1, while the other can use both oxygen and nitrate as electron acceptor, P2 ）, a new group of phosphorus removal bacterium P3, which could use oxygen, nitrate and nitrite as electron acceptor to take up phosphorus were identified in the test system. To understand （AO）^2 SBR sludge better, the relative population of the different bacteria in this system, plus another A/O SBR sludge （ seed sludge） were respectively estimated by the phosphorus uptake batch tests with either oxygen or nitrate or nitrite as electron acceptor. The results demonstrated that phosphorus removal capability of （AO）^2 SBR sludge had a little degradation after A/O sludge was cultivated in the （AO）^2 mode over a long period of time. However, deuitrifying phosphorus removal bacteria （ P2 and P3 ） was significantly enriched showed by the relative population of the three types of bacteria, which implied that energy for aeration and COD consumption could be reduced in theory.
基金Supported by the Science and Technology Project of Heilongjiang Province (Grant No. GA01C201-03)
文摘Literatures revealed that the electron acceptor-nitrite could be inhibitory or toxic in the denitrifying phosphorus removal process. Batch test experiments were used to investigate the inhibitory effect during the anoxic condition. The inoculated activated sludge was taken from a continuous double-sludge denitrifying phosphorus and nitrogen removal system. Nitrite was added at the anoxic stage. One time injection and sequencing batch injection were carried on in the denitrifying dephosphorus procedure. The results indicated that the nitrite concentration higher than 30 mg/L would inhibit the anoxic phosphate uptake severely,and the threshold inhibitory concentration was dependent on the characteristics of the activated sludge and the operating conditions; instead,lower than the inhibitory concentration would not be detrimental to anoxic phosphorus uptake,and it could act as good electron acceptor for the anoxic phosphate accumulated. Positive effects performed during the denitrifying biological dephosphorus all the time. The utility of nitrite as good electron acceptor would provide a new feasible way in the denitrifying phosphorus process.
文摘Simultaneous biological phosphorus and nitrogen removal with enhanced anoxic phosphate uptake via nitrite was investigated in an anaerobic-aerobic-anoxic-aerobic sequencing batch reactor((AO)2 SBR). The system showed stable phosphorus and nitrogen removal performance, and average removals for COD, TN and TP were 90%, 91% and 96%, respectively. The conditions of pH 7.5—8.0 and temperature 32℃ were found detrimental to nitrite oxidation bacteria but favorable to ammonia oxidizers, and the corresponding specific oxygen uptake rates(SOUR) for phase 1 and 2 of nitrification process were 0.7 and 15 mgO 2/(gVSS·h) in respect, which led to the nitrite accumulation in aerobic phase of(AO)2 SBR. Respiratory tests showed that 40 mgNO 2-N/L did not deteriorate the sludge activity drastically, and it implied that exposure of sludge to nitrite periodically enabled the biomass to have more tolerance capacity to resist the restraining effects from nitrite. In addition, batch tests were carried out and verified that denitrifying phosphorus accumulation organisms(DPAOs) could be enriched in a single sludge system coexisting with nitrifiers by introducing an anoxic phase in an anaerobic-aerobic SBR, and the ratio of the anoxic phosphate uptake capacity to aerobic phosphate uptake capacity was 45%. It was also found that nitrite(up to 20 mgNO 2-N/L) was not inhibitory to anoxic phosphate uptake and could serve as an electron acceptor like nitrate, but presented poorer efficiency compared with nitrate.
基金This work was supported by the High-Tech Research and Development(863)Program of China(Grant No.2003AA601010).
文摘An anaerobic-oxic(A/O)biological phosphorus removal reactor was operated to study the effect of nitrite on phosphate uptake.The phosphorus uptake profile was determined under different operating conditions.The results indicated that in addition to oxygen and nitrate(DPB_(Na),nitrate denitrifying phosphorus removal),to some extent,nitrite could also serve as an electron acceptor to achieve nitrite denitrifying phosphorus removal(DPB_(Ni)).The quantity and rate of phosphorus uptake of DPBNi,however,were evidently lower than that of DPBNa.The experiment results revealed that nitrite would bring toxic action to phosphate-accumulating organisms(PAOs)when NO_(2)^(−)-Ni93.7 mg/L.The nitrite existing in the anoxic reactor made no difference to the quantity and rate of denitrifying phosphorus removal,but it could reduce the consumption of nitrate.Moreover,the data showed that the aerobic phosphate uptake of DPBNi was lower than that of anaerobic phosphorus-released sludge in a traditional A/O process.However,there was not much difference between these two kinds of sludge in terms of the total phosphorus uptake quantity and the effluent quality.
