不同C/N进水对微生物群落结构及雌激素去除的影响

Effects of Different Influent C/N Ratios on Microbial Community Structure and Estrogens Removal

该文以实验室内SBR小试试验系统处理不同C/N的人工配水,研究不同C/N进水条件下对COD、NH4+-N、NO2--N和NO3--N等常规污染物及E1、E2和EE2等雌激素去除的影响,并以Miseq高通量测序技术对SBR活性污泥系统中的微生物多样性、群落结构以及功能菌进行了分析。结果表明,COD的去除率随着C/N的不断升高而升高,出水NH4+-N和NO2--N值随着C/N的不断升高而升高,而NO3--N值随着C/N的不断升高而降低。与C/N为2和11的系统相比,C/N为5和8系统中的微生物丰度较高,但优势微生物所占比重较小。从门的分类来看,4个SBR系统中丰度较高的微生物为Proteobacteria、Bacteroidetes、Actinobacteria;从纲的分类来看,丰度较高的微生物为Actinobacteria、α-Proteobacteria、β-Proteobacteria、γ-Proteobacteria和Sphingobacteriia;从属的水平看,Thauera含量最高,Thauer、Tetrasphaera、Ornithinibacter、Micropruina、Candidatus Competibacter、Microlunatus随着C/N的升高而升高,而Tessaracoccus、Candidatus Microthrix、Acidovorax、Arenimonas、Brevundimonas、Ferruginibacter随着C/N的升高而降低。降解雌激素的功能菌种类,E2最多,E1次之,EE2最少。无论进水C/N为多少,对E1和E2的去除率均较高,对EE2的去除率则较低,均在80%以下,随着C/N升高,EE2去除率逐步升高,当C/N为8时,EE2的去除率达到了最高75.69%,当C/N为11时硝化细菌的生长被大幅度地抑制,共代谢作用减弱,EE2去除率有所降低,C/N为8时可能是硝化细菌和异养菌都发挥最大作用的最佳平衡点。

In this study,synthetic wastewater with different influent C/N ratios was treated by sequencing batch reactors(SBRs)to investigate the effects of influent C/N ratios on conventional pollutants and estrogens removal.In addition,microbial diversity,community structure and functional microbes in activated sludge were analyzed by Miseq high-throughput sequencing.The results indicated that the removal efficiency of COD rose with the increase of C/N ratios,and the values of effluent NH4+-N and NO2--N improved,but the values of effluent NO3--N reduced with the increase of C/N ratios.Microbial richness in SBRs with C/N ratios of 5 and 8 was higher than that of SBRs with C/N ratios of 2 and 11,but had rather lower proportion of dominant microorganisms.Illumina sequencing showed that Proteobacteria,Bacteroidetes and Actinobacteria had higher abundance in four SBRs at the level of phylum.And the microorganisms with higher abundance were Actinobacteria,α-Proteobacteria,β-Proteobacteria,γ-Proteobacteria and Sphingobacteriia at the level of class.As for the genus,the content of Thauera was the highest,and the contents of Thauer,Tetrasphaera,Ornithinibacter,Micropruina,Candidatus Competibacter and Microlunatus enhanced with the increase of C/N,while Tessaracoccus,Candidatus Microthrix,Acidovorax,Arenimonas,Brevundimonas and Ferruginibacter decreased with the increase of C/N.There were the most functional bacteria to degrading E2,followed by E1 and EE2.The removal efficiency of E1 and E2 were rather higher no matter what the influent C/N ratios were,while that of EE2 were lower,which were all below 80%.The removal efficiency of EE2 gradually rose with the increase of C/N,and the removal efficiency reached up to 75.69%when C/N ratio was 8.The co-metabolism of nitrifying bacteria was greatly weak due to overwhelmingly suppression by heterotrophic bacteria when influent C/N ratio was 11,then causing the removal efficiency of EE2 reducing in comparison with that of influent C/N ratio 8.Influent C/N ratio of 8 may be the best point of balance of co-metabolic degradation of estrogens by nitrifying bacteria and heterotrophic bacteria.