某污水厂主流Anammox现象产生的原因探讨

Discussion on Reasons of Mainstream Anammox Phenomenon in a Wastewater Treatment Plant

我国中部某污水厂在原倒置A^2/O工艺的基础上进行提标改造,在缺氧池和厌氧池中投加填料形成A^2/O—IFAS工艺。经过4年半的稳定运行,系统呈现良好的脱氮效果,厌氧池和缺氧池填料出现红色生物膜。研究表明,厌氧池和缺氧池填料生物膜具有厌氧氨氧化(Anammox)活性,采用高通量测序法对生物膜和悬浮污泥进行菌群结构分析,发现属水平上以Candidatus Kuenenia为主的厌氧氨氧化菌(AMX)集中在缺氧池生物膜中,其相对丰度明显高于厌氧池生物膜和悬浮污泥。厌氧池和缺氧池拦网处用于防止填料堵塞、促进流化的局部吹扫曝气使厌氧段/缺氧段系统始终处于低溶解氧(DO)交替变化中,促进了同步硝化反硝化(SND)过程,为AMX的富集提供了基质。传统硝化/反硝化混合菌种与AMX在低DO条件下共存、共生、自然竞争,协同完成脱氮作用。厌氧池/缺氧池吹扫曝气形成的低DO区段和填料的投加促进了主流Anammox现象的产生,成为系统运行稳定的主要原因之一。

A full-scale wastewater treatment plant(WWTP)located in central China was upgraded based on the original inverted A^2/O process,and the A^2/O-IFAS process was formed by introducing carriers in the anaerobic and anoxic tanks.After more than four and a half years of stable operation,the system showed excellent nitrogen removal efficiency,and the reddish biofilm appeared on the carriers in anaerobic and anoxic tanks.The biofilm on the carriers in the anaerobic and anoxic tanks hadAnammox activity.The microbial community composition of biofilm and suspended sludge was analyzed by highthroughput sequencing method.Candidatus Kuenenia,the dominant Anammox bacteria(AMX)at the genus level,was concentrated in the biofilm in the anoxic tank,and its relative abundance was significantly higher than that in the biofilm in the anaerobic tank and suspended sludge.Local aeration under the screens in the anaerobic and anoxic tanks was used to prevent blocking of the carriers and promote fluidization,which made the anaerobic/anoxic system always in alternate change of low dissolved oxygen(DO).It also promoted the simultaneous nitrification and denitrification(SND)process,and provided substrates for AMX.Coexistence,symbiosis and natural competition of traditional nitrifying bacteria and denitrifying bacteria in the suspended sludge and AMX in the biofilm removed nitrogen synergically at low DO.The low DO formed by local aeration and addition of carriers in the anaerobic and anoxic tanks promoted the emergence of mainstream Anammox phenomenon and became one of the main reasons for stable operation of the system.