Abstract: Combining anaerobic-anoxic-oxic reactor with an external nitrification biological aerated filter, the AAO-BAF process was used to treat domestic wastewater. Adjusting the influent COD concentration from 211 to 675 mg·L^-1, the effect of carbon-nitrogen ratio (C/N) on the performance of the AAO-BAF process was investigated. A low or high influent organic concentration had significant effect on the nutrients removal efficiency due to the deficient phosphorus release or nitrate competition in the anoxic zones of the AAO reactor between DPAOs and ordinary heterotrophic organisms. When C/N was between 4 and 7,the average removal efficiencies of COD, TN and PO₄^3- could reach more than 86%, 78% and 90% respectively. Large quantity of residual volatile fatty acid (VFA)would be transferred into the anoxic zones when C/N was very high (such as 9.5), which would cause rapid consumption of NO₃^- by ordinary heterotrophic organisms rather than denitrifying phosphorus accumulating organisms (DPAOs).

Key words: AAO, external nitrification, denitrifying phosphorus removal, domestic wastewater, C/N

摘要： AAO-BAF工艺由厌氧-缺氧-好氧反应器和曝气生物滤池组成,属于外硝化反硝化除磷工艺。以实际生活污水为处理对象,通过调节进水COD浓度(从211 mg·L^-1增加到675 mg·L^-1),研究了进水COD和TN的比(C/N)对AAO-BAF工艺运行性能的影响。结果表明,进水有机物浓度低或高,可以通过限制厌氧释磷量或竞争AAO反应器缺氧区的NO₃^-,从而影响工艺的反硝化除磷效果。当进水C/N大于4,小于7时,AAO-BAF工艺对COD、TN和PO₄^3-的去除率分别可达86%、78%和90%以上。很高的C/N(如9.5)会使缺氧区内存在大量挥发性脂肪酸(VFA),导致普通反硝化菌迅速消耗反硝化聚磷菌(DPAOs)的电子受体NO₃^-。

关键词: AAO, 外硝化, 反硝化除磷, 生活污水, C/N