饮用水生物处理小试工艺中NH4^＋-N的非硝化去除途径分析

Non-nitrification Pathway for NH_4^+-N Removal in Pilot-Scale Drinking Water Biological Processes

通过计算N和DO的质量平衡,研究饮用水生物处理小试工艺中是否存在NH4+-N的非硝化去除途径,并探讨其可能机制.结果表明,当生物流化床和生物滤池进水NH4+-N浓度大于2 mg/L时,前者进水的NH4+-N、NO2--N和NO3--N之和比出水高出0.91 mg/L,后者理论上消耗的DO比实际多约2.90 mg/L,说明这2种工艺中均有氮亏损现象发生,一部分NH4+-N通过与DO无关的非硝化作用被去除.对非硝化去除途径的分析表明,因为反应器对磷元素和有机物的利用不随氮亏损发生变化,可以排除掉同化作用和反硝化作用;因为反应器进水低碳高氮的特性和NO2--N的积累与发生氮亏损的废水生物处理系统相似,据此提出在生物膜缺氧内部发生、通过短程硝化和厌氧氨氧化的偶联(或OLAND反应)将NH4+-N和NO2--N同时转变为N2脱除的自养脱氮是饮用水生物处理中氮亏损的可能途径.

The non-nitrification pathway for NH4^＋-N removal in pilot-scale drinking water biological treatment processes and its possible mechanism were investigated through calculating N and DO stoichiometric balance.With more than 2mg/L NH4^＋-N in the influent,for the fluidized bed bioreactor（FBBR）,the total of NH4^＋-N,NO2^--N,NO3^--N in the influent was 0.91mg/L higher than that in the effluent,and for the biofilter,its DO consumption was 2.90mg/L less than the stoichiometric amount.The results suggested that nitrogen loss occurred in both reactors and a part of NH4^＋-N was removed through non-nitrification pathway.Because the utilization of phosphorus and organic matters was independent of nitrogen loss,the assimilation and denitrification could be excluded from the possible mechanisms.Because the very low C/N in the influent and the accumulation of NO2^--N in the reactors were similar with the wastewater biological processes,the ＂autotrophic removal of nitrogen＂ was regarded as the most probable non-nitrification pathway.In this mechanism,the couple of short-cut nitrification and ANAMMOX（or OLAND） leading to the transformation of NH4^＋-N and NO2^--N into gaseous N2 was responsible for the nitrogen loss in drinking water biological processes.