Ca2+、Mg2+共存对SBR工艺生物脱氮和微生物群落结构的影响

为了研究共存的硬度金属离子在废水生物处理中的作用,在进水Ca~(2+)为1.1 mmol·L~(-1)的条件下,通过改变Mg~(2+)的浓度,考察Ca~(2+)/Mg~(2+)物质的量比对SBR工艺污染物去除和微生物群落的影响,采用高通量测序技术分析微生物优势种群的变化,以期从微生物角度明确Ca~(2+)、Mg~(2+)共存对生物脱氮的影响机制.结果表明:当Ca~(2+)/Mg~(2+)物质的量比分别为2、1和0.5时,COD去除率由88%分别升高至90%、91%和93%;NH~+_4-N去除率由74%分别升高至91%、93%和96%;TN去除率由44%分别升高至58%、62%和69%.随着进水Ca~(2+)/Mg~(2+)物质的量比的降低,微生物群落的丰富度升高,Ca~(2+)/Mg~(2+)物质的量比为2的微生物群落结构与Ca~(2+)/Mg~(2+)物质的量比为1和0.5的微生物群落结构差异显著.变形菌门、拟杆菌门和放线菌门一直为SBR工艺的优势菌门,有利于有机污染物的去除.参与脱氮过程的Niabella和Dechloromonas在反应器内富集,保证了良好的脱氮效果.Ca~(2+)/Mg~(2+)物质的量比的降低促进了有机物和总氮的去除及微生物多样性的提高.

Effect of the coexistence of Ca2+ and Mg2+ on the biological denitrification and microbial community structure

In order to study the role of co-existence of Ca²⁺/Mg²⁺ in biological wastewater treatment system, the effects of Ca²⁺/Mg²⁺ molar ratio on organics and nutrients removal and microbial community were investigated in SBR process by changing the concentration of Mg²⁺ together with 1.1 mmol·L^-1 of Ca²⁺. The changes of microbial populations were analyzed bthrough high-throughput sequencing in order to identify the influencing mechanism of coexistence of Ca²⁺ and Mg²⁺ on biological denitrification. The results show that when Ca²⁺/Mg²⁺ molar ratios were 2, 1 and 0.5, the removal efficiency of COD increased from 88% to 90%, 91% and 93%; the removal efficiency of NH₄⁺-N increased from 74% to 91%, 93% and 96%; the removal efficiency of TN increased from 44% to 58%, 62% and 69%, respectively. With the decrease of influent Ca²⁺/Mg²⁺ molar ratio, the richness of microbial community increased. The structure of microbial community under Ca²⁺/Mg²⁺ molar ratio of 2 was significantly different from that under Ca²⁺/Mg²⁺ molar ratio of 1 and 0.5. Proteobacteria, Bacteroidetes and Actinobacteria had always been the dominant bacteria in SBR process, which was conducive to the removal of organic pollutants. Niabella and Dechloromonas involved in the denitrification process were enriched in the reactor, and could ensure good denitrification performance. The decrease of Ca²⁺/Mg²⁺ molar ratio promoted the removal of organic compounds and TN and enrich the microbial diversity.