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
Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional method for nitrogen removal,is studied in this paper.In order to find the suitable conditions of this process...Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional method for nitrogen removal,is studied in this paper.In order to find the suitable conditions of this process,a mixed flow activated sludge system under low oxygen concentration is investigated,and some key control parameters are exam-ined for nitrogen removal from synthetic wastewater.The results show that SND is accessible when oxygen concentra-tion is 0.3-0.8 mg/L.The nitrogen removal rate can be obtained up to 66.7%with solids retention time(SRT)of 45 d,C/N value of 10,and F/M ratio of 0.1 g COD/(g MLSS·d).Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.展开更多
The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled co...The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled conditions to proliferate the nitrifiers. Heterotrophic nitrifying bacteria were isolated from the system in which the efficiency of total nitrogen(TN) removal was up to 80%. Since no autotrophic ammonium and nitrite oxidizers could be detected by fluorescence in situ hybridization(FISH), oxidized-N production was unlikely to be catalyzed by autotrophic nitrifiers during the heterotrophic nitrifiers' isolation in this study. The batch test results indicate that the isolated heterotrophic bacteria were able to nitrify. After 3 weeks incubation, the efficiencies of the COD removal by the three isolated bacterial strains B1, B2, and B3 were 52 6%, 71 7%, and 77 7%, respectively. The efficiencies of the TN removal by B1, B2, and B3 were 35 6%, 61 2% and 68 7%, respectively.展开更多
A Florida wastewater treatment facility studied how Simultaneous Nitrification Denitrification (SND) coupled with traditional nitrogen removal would be used to meet the state’s current advanced wastewater treatment n...A Florida wastewater treatment facility studied how Simultaneous Nitrification Denitrification (SND) coupled with traditional nitrogen removal would be used to meet the state’s current advanced wastewater treatment nutrient criterion. This study examined the effect of these combined processes on the fate and transport of the nitrogen species during the treatment process. The effectiveness of nitrogen removal within the full scale sequential batch reactor system (SBR) and the extent of SND compared to nitrification and denitrification in the nitrogen removal process was also evaluated. Finally, the overall performance of the municipal wastewater treatment facility utilizing these combined processes was evaluated. Overall, this application reduced the total nitrogen to almost 6% of the permitted concentration of 3.0 mg/L. The combination of both processes also resulted in an actual ?concentration 93.7% lower than the acceptable theoretical ?concentration, which also resulted in effluent Total Inorganic Nitrogen nearly 80% lower than the permitted 3.0 mg/L effluent concentration. Further, the process produced a composite Total Nitrogen concentration that was 74% lower than the permitted concentration. This coupling of SND with traditional nitrogen removal resulted in a highly effective process to reduce nitrogen in the municipal wastewater effluent which is also attractive for potential implementation due to the low cost expenditure incurred in its utilization.展开更多
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...
文摘Simultaneous nitrification and denitrification(SND),which is more economical compared with the tradi-tional method for nitrogen removal,is studied in this paper.In order to find the suitable conditions of this process,a mixed flow activated sludge system under low oxygen concentration is investigated,and some key control parameters are exam-ined for nitrogen removal from synthetic wastewater.The results show that SND is accessible when oxygen concentra-tion is 0.3-0.8 mg/L.The nitrogen removal rate can be obtained up to 66.7%with solids retention time(SRT)of 45 d,C/N value of 10,and F/M ratio of 0.1 g COD/(g MLSS·d).Theoretical analysis indicates that SND is a physical phenomenon and governed by oxygen diffusion in flocs.
文摘The study presented the method for isolating the heterotrophic nitrifiers and the characterization of heterotrophic nitrification. Continuous tests via a membrane bioreactor (MBR) were operated under the controlled conditions to proliferate the nitrifiers. Heterotrophic nitrifying bacteria were isolated from the system in which the efficiency of total nitrogen(TN) removal was up to 80%. Since no autotrophic ammonium and nitrite oxidizers could be detected by fluorescence in situ hybridization(FISH), oxidized-N production was unlikely to be catalyzed by autotrophic nitrifiers during the heterotrophic nitrifiers' isolation in this study. The batch test results indicate that the isolated heterotrophic bacteria were able to nitrify. After 3 weeks incubation, the efficiencies of the COD removal by the three isolated bacterial strains B1, B2, and B3 were 52 6%, 71 7%, and 77 7%, respectively. The efficiencies of the TN removal by B1, B2, and B3 were 35 6%, 61 2% and 68 7%, respectively.
文摘A Florida wastewater treatment facility studied how Simultaneous Nitrification Denitrification (SND) coupled with traditional nitrogen removal would be used to meet the state’s current advanced wastewater treatment nutrient criterion. This study examined the effect of these combined processes on the fate and transport of the nitrogen species during the treatment process. The effectiveness of nitrogen removal within the full scale sequential batch reactor system (SBR) and the extent of SND compared to nitrification and denitrification in the nitrogen removal process was also evaluated. Finally, the overall performance of the municipal wastewater treatment facility utilizing these combined processes was evaluated. Overall, this application reduced the total nitrogen to almost 6% of the permitted concentration of 3.0 mg/L. The combination of both processes also resulted in an actual ?concentration 93.7% lower than the acceptable theoretical ?concentration, which also resulted in effluent Total Inorganic Nitrogen nearly 80% lower than the permitted 3.0 mg/L effluent concentration. Further, the process produced a composite Total Nitrogen concentration that was 74% lower than the permitted concentration. This coupling of SND with traditional nitrogen removal resulted in a highly effective process to reduce nitrogen in the municipal wastewater effluent which is also attractive for potential implementation due to the low cost expenditure incurred in its utilization.
