生物膜脱氮滤池的微生物群落结构特性

为探究生物膜脱氮滤池脱氮效能差异的微生物因素,设置组1(包括接种污泥、稳定期滤料、反冲洗后滤料微生物变化)和组2(包括反冲洗前滤料、反冲洗后不同时间段滤料微生物变化)两组实验,通过高通量测序,研究不同阶段微生物群落结构、丰度和多样性的分布情况.结果表明:接种污泥与滤料表面微生物群落结构和多样性在门水平下差异不大,但在属水平下差异显著,而相对丰度在两种分类水平下始终差异显著.反冲洗后0～4 h滤料表面微生物的OTU数目、Shannon指数、Chao1指数变化,在滤池30 cm处先升后降,而在60 cm处曲折上升,也即二者的微生物丰度和多样性变化趋势.反冲洗前后Proteobacteria始终占主导地位,相对丰度为79%～90%,Proteobacteria中Betaproteobacteria占主导优势,反冲洗后Betaproteobacteria数量相对减少,后逐渐恢复.总反硝化优势菌属相对丰度在反冲洗1 h后30 cm处由78%左右下降到70%左右,60 cm处由68%左右下降到64%左右,此时出水总氮达到最高值7.7 mg·L~(-1),之后总反硝化优势菌属及出水TN浓度逐渐恢复至正常水平,这种消长变化表明滤池脱氮效果与总反硝化优势菌属相对丰度密切相关,滤池运行状态的改变使得反硝化优势菌属的群落结构差异显著.

Characterisitics of microbial community structure of a denitrification biofilm filter

In order to investigate the effect of microorganisms on nitrogen removal efficiency of a denitrification biofilm filter, two experiments were conducted, i.e., experiment 1 (inoculated sludge, filter media in a stable period and filter media after backwashing) and experiment 2 (the filter media before backwashing and after backwashing at different periods). High-throughput sequencing was applied to analyze the distribution of microbial community structure, abundance and diversity at different stages. There were no differences of the microbial community structure and diversity of the inoculated sludge and filter media at the phylum level. However, a significant difference at the genus level was observed. Meanwhile, the relative abundance was always significant at the two classification levels. In the first four hours after backwashing, the OTU number, Shannon index and Chao1 index of the microbes on the surface of the filter media were increased first and then decreased at 30 cm. In addition, it ascended with an upward tendency at 60 cm. Proteobacteria was dominant before and after backwashing with a relative abundance of 79%~90%. Betaproteobacteria was dominant in Proteobacteria. Its number decreased after backwashing and then recovered gradually. In the first 1 h after backwashing, the relative abundance of the total dominant denitrifiers decreased from 78% to 70% at 30 cm, from 68% to 64% at 60 cm. At the same time, the total nitrogen of the effluent reached to the highest value of 7.7 mg·L^-1. The total dominant denitrifiers and the total nitrogen of the effluent were gradually recovered to its normal level. The results of this study demonstrated that the nitrogen removal efficiency was closely related to the relative abundance of the total dominant denitrifiers. The difference of the community structure of the dominant denitrifiers was due to changes of the operational state of the filter.