Since the ammonia in the effluent of the tradi-tional water purification process could not meet the supply demand,the advanced treatment of a high concentration of NH4+-N micro-polluted source water by biological acti...Since the ammonia in the effluent of the tradi-tional water purification process could not meet the supply demand,the advanced treatment of a high concentration of NH4+-N micro-polluted source water by biological activated carbon filter(BACF)was tested.The filter was operated in the downflow manner and the results showed that the remov-ing rate of NH_(4)^(+)-N was related to the influent concentration of NH_(4)^(+)-N.Its removing rate could be higher than 95%when influent concentration was under 1.0 mg/L.It could also decrease with the increasing influent concentration when the NH_(4)^(+)-N concentration was in the range from 1.5 to 4.9 mg/L and the dissolved oxygen(DO)in the influent was under 10 mg/L,and the minimum removing rate could be 30%.The key factor of restricting nitrification in BACF was the influent DO.When the influent NH_(4)^(+)-N concentration was high,the DO in water was almost depleted entirely by the nitrifying and hetetrophic bacteria in the depth of 0.4 m filter and the filter layer was divided into aerobic and anoxic zones.The nitrification and degradation of organic matters existed in the aerobic zone,while the denitrification occurred in the anoxic zone.Due to the limited carbon source,the denitrifica-tion could not be carried out properly,which led to the accu-mulation of the denitrification intermediates such as NO_(2)^(−).In addition to the denitrification bacteria,the nitrification and the heterotrophic bacteria existed in the anoxic zone.展开更多
A novel full scale modified A2O （anoxic/anaerobic/aerobic/pre-anoxic）-membrane bioreactor （MBR） plant combined with the step feed strategy was operated to improve the biological nutrient removal （BNR） from low C...A novel full scale modified A2O （anoxic/anaerobic/aerobic/pre-anoxic）-membrane bioreactor （MBR） plant combined with the step feed strategy was operated to improve the biological nutrient removal （BNR） from low C/N ratio municipal wastewater in Southern China. Transformation of organic carbon, nitrogen and phosphorus, and membrane fouling were investigated. Experimental results for over four months demonstrated good efficiencies for chemical oxygen demand （COD） and NH4^＋-N removal, with average values higher than 84.5%and 98.1%, re-spectively. A relatively higher total nitrogen （TN） removal efficiency （52.1%） was also obtained at low C/N ratio of 3.82, contributed by the configuration modification （anoxic zone before anaerobic zone） and the step feed with a distribution ratio of 1：1. Addition of sodium acetate into the anoxic zone as the external carbon source, with a theoretical amount of 31.3 mg COD per liter in influent, enhanced denitrification and the TN removal efficiency in-creased to 74.9%. Moreover, the total phosphate （TP） removal efficiency increased by 18.0%. It is suggested that the external carbon source is needed to improve the BNR performance in treating low C/N ratio municipal waste-water in the modified A^2O-MBR process.展开更多
The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal （BNR） from municipal wastewater in a...The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal （BNR） from municipal wastewater in anaerobic- anoxic-aerobic sequencing batch reactors （SBRs）. Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound （sodium acetate） served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-13-hydroxyalkanoates （PHAs）, and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating or- ganisms （PAOs） and denitrifying phosphorus accumulating organisms （DPAOs） demonstrated that the proportion of DPAOs to PAOs reached 62.6% （Day 86） and 61.8% （Day 65） when using cassava stillage and its anaerobic fer- mentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates （NURs） of the cassava by-products were in the range of 5.49-5.99 g N/（kg MLVSS.h） （MLVSS is mixed liquor volatile suspended solids） and 6.63-6.81 g N/（kg MLVSS.h）, respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes.展开更多
文摘Since the ammonia in the effluent of the tradi-tional water purification process could not meet the supply demand,the advanced treatment of a high concentration of NH4+-N micro-polluted source water by biological activated carbon filter(BACF)was tested.The filter was operated in the downflow manner and the results showed that the remov-ing rate of NH_(4)^(+)-N was related to the influent concentration of NH_(4)^(+)-N.Its removing rate could be higher than 95%when influent concentration was under 1.0 mg/L.It could also decrease with the increasing influent concentration when the NH_(4)^(+)-N concentration was in the range from 1.5 to 4.9 mg/L and the dissolved oxygen(DO)in the influent was under 10 mg/L,and the minimum removing rate could be 30%.The key factor of restricting nitrification in BACF was the influent DO.When the influent NH_(4)^(+)-N concentration was high,the DO in water was almost depleted entirely by the nitrifying and hetetrophic bacteria in the depth of 0.4 m filter and the filter layer was divided into aerobic and anoxic zones.The nitrification and degradation of organic matters existed in the aerobic zone,while the denitrification occurred in the anoxic zone.Due to the limited carbon source,the denitrifica-tion could not be carried out properly,which led to the accu-mulation of the denitrification intermediates such as NO_(2)^(−).In addition to the denitrification bacteria,the nitrification and the heterotrophic bacteria existed in the anoxic zone.
基金Supported by the National Water Pollution Control and Management(2008ZX07316-002)the University of Macao Research Committee(RG067/09-10S/SHJ/FST)
文摘A novel full scale modified A2O （anoxic/anaerobic/aerobic/pre-anoxic）-membrane bioreactor （MBR） plant combined with the step feed strategy was operated to improve the biological nutrient removal （BNR） from low C/N ratio municipal wastewater in Southern China. Transformation of organic carbon, nitrogen and phosphorus, and membrane fouling were investigated. Experimental results for over four months demonstrated good efficiencies for chemical oxygen demand （COD） and NH4^＋-N removal, with average values higher than 84.5%and 98.1%, re-spectively. A relatively higher total nitrogen （TN） removal efficiency （52.1%） was also obtained at low C/N ratio of 3.82, contributed by the configuration modification （anoxic zone before anaerobic zone） and the step feed with a distribution ratio of 1：1. Addition of sodium acetate into the anoxic zone as the external carbon source, with a theoretical amount of 31.3 mg COD per liter in influent, enhanced denitrification and the TN removal efficiency in-creased to 74.9%. Moreover, the total phosphate （TP） removal efficiency increased by 18.0%. It is suggested that the external carbon source is needed to improve the BNR performance in treating low C/N ratio municipal waste-water in the modified A^2O-MBR process.
基金supported by the National Water Pollution Control and Management of Major Special Science and Technology Foundation(No.2011ZX07303-001),China
文摘The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal （BNR） from municipal wastewater in anaerobic- anoxic-aerobic sequencing batch reactors （SBRs）. Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound （sodium acetate） served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-13-hydroxyalkanoates （PHAs）, and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating or- ganisms （PAOs） and denitrifying phosphorus accumulating organisms （DPAOs） demonstrated that the proportion of DPAOs to PAOs reached 62.6% （Day 86） and 61.8% （Day 65） when using cassava stillage and its anaerobic fer- mentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates （NURs） of the cassava by-products were in the range of 5.49-5.99 g N/（kg MLVSS.h） （MLVSS is mixed liquor volatile suspended solids） and 6.63-6.81 g N/（kg MLVSS.h）, respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes.
