Acetate, ethanol, and hydrolysed rice were used as external carbon sources in an ammonium removal process employing immobilised bacteria. The influence of the carbon source on the occurrence of free cells and total ni...Acetate, ethanol, and hydrolysed rice were used as external carbon sources in an ammonium removal process employing immobilised bacteria. The influence of the carbon source on the occurrence of free cells and total nitrogen removal efficiency was examined at C/N ratios of 1.5 (low), 2.5 (medium), and 3.5 (high). At the low C/N ratio, no free cells were found in the reactors and the use of acetate as the carbon source resulted in the highest total nitrogen removal efficiency, followed by ethanol and hydrolysed rice. The occurrence of free cells in reactors fed with acetate and ethanol led to a negligible increase in the total nitrogen removal efficiency with increasing C/N ratio. The results suggest that acetate is the most appropriate carbon source for nitrogen removal and that the number of free cells should be minimized to achieve the highest efficiency during long-term operation.展开更多
Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid （PLA）/ starch blends as carbon source and carrier for fimctional bacteria. The exclusive and interactive influences of operati...Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid （PLA）/ starch blends as carbon source and carrier for fimctional bacteria. The exclusive and interactive influences of operating parameters （i.e., temperature, pH, stirring rate, and PLA-to-starch ratio （PLA proportion）） on nitrification （Y1）, denitrification （Y2）, and COD release rates （Y3） were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous mtnncatlon anti clenltnncatlon. The carbon release rate of the blends was controllable. The sensitivity of Y1, Y2, and Y3 to different operating parameters also differed. The sequence for each response was as follows： for Y1, pH 〉 stirring rate 〉 PLA proportion 〉 temperature; for Y2, PH 〉 PLA proportion 〉.temperature.〉 stirring rate; and for Y3, stirring rate 〉pH 〉 PLA proportion 〉 temperature. In this study, the following optimum conditions were observed： temperature, 32.0℃; pH 7.7; stirring rate, 200.0 r · min^-1 and PLA proportion 0.4. Under these conditions Y1 Y2 and Y3 were 134.0 μg-N·g-blend^-1·h^-1, 160.9μg-N-g-blend^-1·h^-1, and 7.6 × 10^3 μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.展开更多
文摘Acetate, ethanol, and hydrolysed rice were used as external carbon sources in an ammonium removal process employing immobilised bacteria. The influence of the carbon source on the occurrence of free cells and total nitrogen removal efficiency was examined at C/N ratios of 1.5 (low), 2.5 (medium), and 3.5 (high). At the low C/N ratio, no free cells were found in the reactors and the use of acetate as the carbon source resulted in the highest total nitrogen removal efficiency, followed by ethanol and hydrolysed rice. The occurrence of free cells in reactors fed with acetate and ethanol led to a negligible increase in the total nitrogen removal efficiency with increasing C/N ratio. The results suggest that acetate is the most appropriate carbon source for nitrogen removal and that the number of free cells should be minimized to achieve the highest efficiency during long-term operation.
基金This study was supported by the National Natural Science Foundation of China （Grant No. 41505124） and Fundamental Research Funds for the Central Universities （Grant No. FRF-TP- 15 -044A 1）.
文摘Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid （PLA）/ starch blends as carbon source and carrier for fimctional bacteria. The exclusive and interactive influences of operating parameters （i.e., temperature, pH, stirring rate, and PLA-to-starch ratio （PLA proportion）） on nitrification （Y1）, denitrification （Y2）, and COD release rates （Y3） were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous mtnncatlon anti clenltnncatlon. The carbon release rate of the blends was controllable. The sensitivity of Y1, Y2, and Y3 to different operating parameters also differed. The sequence for each response was as follows： for Y1, pH 〉 stirring rate 〉 PLA proportion 〉 temperature; for Y2, PH 〉 PLA proportion 〉.temperature.〉 stirring rate; and for Y3, stirring rate 〉pH 〉 PLA proportion 〉 temperature. In this study, the following optimum conditions were observed： temperature, 32.0℃; pH 7.7; stirring rate, 200.0 r · min^-1 and PLA proportion 0.4. Under these conditions Y1 Y2 and Y3 were 134.0 μg-N·g-blend^-1·h^-1, 160.9μg-N-g-blend^-1·h^-1, and 7.6 × 10^3 μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.
