Abstract: For municipal wastewater treatment, a continuous anoxic/aerobic system (A/O) combined with flow separate filler was developed to investigate nitrogen removal performance. A/O was running stably for 113 days under oxygen-enriched condition (dissolved oxygen, DO>1.5 mg·L^-1). Removal of ammonia nitrogen and total nitrogen reached 50%, while nitrite and nitrate were not accumulating during the stable process. Simultaneous nitrification and denitrification was obvious in the aerobic zone. 16S rDNA results showed that functional bacterias were aerobic denitrifying bacteria (ADB) in the biofilm of the aerobic zone, and FISH results showed the activities of ADB along the aerobic zone. Aerobic denitrification was the main form of simultaneous nitrification and denitrification in the system, consuming nitrite and nitrate from nitrification. A nitrogen removal pathway model via simultaneous nitrification and denitrification in the biofilm under oxygen-rich water environment was established.

Key words: anoxic/aerobic system, biofilm, simultaneous nitrification and denitrification, aerobic denitrification, molecular biology

摘要： 基于添加流离填料的连续流A/O生物膜反应器，研究城市污水生物脱氮特征。系统在富氧条件（溶解氧大于1.5 mg·L^-1）下连续运行113 d，氨氮和总氮去除率均稳定在50%。系统稳定运行阶段好氧区和出水均无亚硝酸盐或硝酸盐积累现象，表现出良好的同步硝化反硝化特征。16S rDNA分析表明，实现这一现象的主要功能细菌为好氧区存在的好氧反硝化菌；FISH分析表明，不同好氧区的好氧反硝化菌的活性和相对数量不同。结果证明系统内发生的同步硝化反硝化主要由好氧反硝化作用实现，硝化反应产生的硝酸盐类物质得到去除。根据试验结果与微生物学分析，提出了在富氧水环境中通过同步硝化反硝化途径脱氮的生物膜模型。

关键词: A/O系统, 生物膜, 同步硝化反硝化, 好氧反硝化, 分子生物学