气水比对A/O-BF处理低碳氮比农村生活污水脱氮的影响

为揭示好氧段气水比对缺氧/好氧生物滤池（Anoxic/Oxic Biofilter，A/O-BF）脱氮的影响机理，采用A/O-BF处理低碳氮比农村生活污水，结合实时荧光定量聚合酶链式反应技术，对比研究了好氧段气水比为4：1、2：1和1：1时A/O-BF的脱氮效能和微生物群落变化特征.结果表明：当气水比为4：1时，A/O-BF的氨氮（NH₄⁺-N）和总氮（TN）平均去除率分别为99.0%和75.9%；当气水比降至2：1时，NH₄⁺-N的平均去除率（99.5%）基本维持不变，而TN去除率有所提高（79.5%）；当气水比再降至1：1时，两者的平均去除率分别下降至92.0%和71.7%.气水比由4：1降至2：1时，好氧段中硝化菌脱氮功能基因amoA和Nitrospira 16S rDNA的拷贝数并无明显变化，为同一数量级，但缺氧段中4个反硝化菌脱氮功能基因（narG、nosZ、nirS和nirK）拷贝数却明显升高0~1个数量级；当气水比由2：1降至1：1时，好氧段中两个硝化菌脱氮功能基因拷贝数均下降1个数量级，但缺氧段中反硝化菌脱氮功能基因拷贝数无明显变化，除narG基因外均处于同一数量级.综上所述，2：1为A/O-BF处理低碳氮比农村生活污水脱氮的最佳气水比.

Effects of air-water ratio on the nitrogen removal of A/O-BF for the treatment of rural domestic sewage with low C/N ratio

To reveal the influence of air-water ratio in the oxic column on the nitrogen removal of anoxic/oxic biofilter (A/O-BF), the nitrogen removal capacity and microbial communiy characteristics of A/O-BF for the treatment of rural domestic sewage with low C/N ratio at 4:1, 2:1 and 1:1 air-water ratio were investigated. The results are as follows: the average ammonium nitrogen (NH₄⁺-N) and total nitrogen (TN) removal efficiency were 99.0% and 75.9% at 4:1 air-water ratio. When the air-water ratio reduced to 2:1, the average NH₄⁺-N removal efficiency kept stable (99.5%), and the TN removal efficiency increased to 79.5%. At 1:1 air-water ratio, both of NH₄⁺-N and TN removal efficiency decreased significantly, i.e. 92.0% and 71.7%. When the air-water ratio reduced from 4:1 to 2:1, the copy numbers of nitrifying functional genes, i.e. amoA, and Nitrospira 16S rRNA genes did not change obviously and in the same order of magnitude, but the copy numbers of four denitrifying functional genes (narG, nosZ, nirS, and nirK), increased significantly by 0~1 order of magnitude. At 1:1 air-water ratio, the copy numbers of both nitrifying functional genes decreased by one order of magnitude, while those of the denitrifying functional genes (except for the narG gene) were in the same order of magnitude. Therefore, 2:1 is recommended as the optimum air-water ratio for the nitrogen removal from rural domestic sewage with low C/N ratio by A/O-BF.