COD/TP比及NO_2~--N/TP对短程反硝化聚磷的影响

污水中COD/TP比和NO2--N/TP比对A/A/OSBR反硝化聚磷工艺运行有重要的影响。实验结果表明:随着COD/TP比值的增加,厌氧释磷增加、厌氧释磷速率提高。但当COD/TP比值为28.5时,过剩的碳源进入缺氧段,反硝化菌利用外碳源消耗,抑制了缺氧吸磷过程;当COD/TP比值为21时,合成的PHB不足,缺氧吸磷效率下降,而且长期在较低COD/TP比条件下运行,激发了聚糖菌与聚磷菌的竞争,聚磷菌处于竞争的劣势,反硝化聚磷能力最终消失;当COD/PO43--P为25时,短程反硝化聚磷效果最佳。NO2--N/TP比与COD/TP的比值相关联,在COD/TP=25的条件下,合适的NO2--N/TP比为3。当NO2--N/PO43--P为5时,SBR上一周期剩余的NO2-会影响厌氧释磷过程。当NO2--N/TP为1.8时,NO2-不足,会使反硝化聚磷过程不完全。

Effects of COD/TP Ratio and NO2--N/TP Ratio on the Performance of Denitrifying Phosphorus Removal with Nitrite as Electron Acceptor

A/A/O SBR process was used to treat synthetic domestic wastewater,and effects of COD/TP ratio and NO2--N/TP ratio on the performance of denitrifying phosphorus removal process was investigated. Results indicated that amount and releasing velocity of phosphate in anaerobic zone increased as COD/TP ratio increased,but when ratio of COD/TP was 28.5,surplus carbon sources went into anoxic zone,which resulted in reduction of nitrite by external carbon sources,inhibiting phosphate accumulating in anoxic zone. When ratio of COD/TP was 21,carbon sources were not enough for being turned into PHB,phosphorus removal efficiency in anoxic zone decreased,moreover limited COD loading may surpress the development of polyphosphate accumulating organisms(PAOs) leading to establishment of microbial communities without polyphosphate accumulation. The microbial communities were dominated by glycogen accumulating organisms(GAOs) . When ratio of COD/PO43--P was 25,the performance of A2/O SBR was the best. The appropriate NO2--N/TP ratio in the influent wastewater was related to ratio of COD/TP. On the COD/TP ratio of 25,the optimum ratio of NO2--N/TP was 3. When ratio of NO2--N/TP was 1.8,denitrifying phosphorus removal process ceased,owing to the lack of nitrite. When ratio of NO2--N/PO43--P was 5,phosphorus removal efficiency of the system decreased,because of nitrite in the anaerobic left over by the previous cycle.