低氨氮污水SNAD工艺启动-运行效能与微生物生态学特性

Start-up of the SNAD process for low ammonia-nitrogen sewage:Operational efficiency and ecological characteristics of microbe.

采用升流式微氧污泥床膜生物反应器(UMSB-MBR)处理低氨氮、低C/N比污水,考察了同步亚硝化-厌氧氨氧化耦合异养反硝化(SNAD)工艺启动过程中的运行效能与微生物生态学特性,结果表明:经过厌氧氨氧化(Anammox)、短程硝化-厌氧氨氧化(PN/A)及SNAD工艺启动3个阶段,各阶段末总氮去除率(NRE)分别可达(80.85±0.81)%,(84.62±0.10)%及(90.01±0.23)%,SNAD工艺启动成功时,COD去除效率(CRE)为(85.04±0.18)%;宏基因组测序结果表明,氨氧化菌(AerAOB)优势菌属Nitrosomonas在PN/A阶段得到富集,且氨氧化功能基因(hao、amo)相对丰度上升;厌氧氨氧化菌(AnAOB)优势菌属由Anammox阶段的Candidatus_Kuenenia转化为SNAD阶段的Candidatus_Brocadia,厌氧氨氧化功能基因(hzs、hdh)呈先下降后上升的趋势,表明AnAOB逐渐适应低DO、低C/N比环境;反硝化菌属Ignavibacterium、unclassified-p-Chloroflexi及反硝化相关基因(narG、narH、nirS、nirK)在SNAD阶段相对丰度较高,表明其在异养脱氮过程中起到重要作用;KEGG氮代谢途径分析表明,系统中脱氮的主要途径归因于在系统内发生的同步亚硝化、厌氧氨氧化以及反硝化反应过程;KEGG代谢通路功能进一步表明,工艺系统启动过程中微生物信号传导与物质交换运输处于较高水平,功能菌之间的协作能力显著加强.

The Up-flow Microaerobic Sludge Blanket(UMSB-MBR)was employed to treat sewage with low ammonia-nitrogen and low C/N ratio,and the operational efficiency of the synchronous nitritation-anammox and denitrification(SNAD)process and the ecological characteristics of microbe were investigated.The results showed that,after start-ups of anammox,partial nitrification-anammox(PN/A)and SNAD processes,the nitrogen removal efficiency(NRE)at the end of each process was(80.85±0.81)%,(84.62±0.10)%and(90.01±0.23)%,respectively;and the COD removal efficiency(CRE)reached(85.04±0.18)%after SNAD process was successfully started up.Metagenomic sequencing results show that Nitrosomonas,the dominant bacteria of AerAOB,was enriched at the PN/A stage,and the relative abundance of ammoxidation functional genes(hao and amo)increased.The dominant genus of AnAOB was shifted from Candidatus_Kuenenia in Anammox process to Candidatus_Brocadia in SNAD process,and the functional genes(hzs and hdh)of anammox decreased first and then increased,indicating that AnAOB gradually adapted to low DO and low C/N ratio.The relative abundance of denitrifying bacteria(Ignavibacterium,unclassified-p-Chloroflexi)and denitrifying related genes(narG、narH、nirS、nirK)were at higher levels during the SNAD process,which proved their important roles in heterotrophic nitrogen removal process.The main nitrogen removal pathways in the system was verified to attribute to the simultaneous nitritation,anammox and denitrification reaction processes.Furthermore,microbial signal transduction and mass exchange and transport were demonstrated to stay at a higher level during the start-up of the system,and the cooperation ability within functional bacteria was significantly enhanced.