不同外碳源对尾水极限脱氮性能及微生物群落结构的影响

Effects of External Carbon Sources on Ultimate Nitrogen Removal Performance and Microbial Community in Secondary Effluent Treating Process

投加外碳源是污水厂尾水深度脱氮的重要手段.为充分对比多种碳源在极限脱氮条件下的性能及经济性,以及碳源对微生物种群结构的影响,选取甲醇、乙醇、葡萄糖和乙酸钠这4种单碳源,并采用反应速率较高的乙酸钠和乙醇与价格便宜的葡萄糖配制成4种复合碳源进行研究.结果表明,所有系统均能满足出水ρ(NO_(x)^(-)-N)≤1.0mg·L^(-1)的要求.单碳源系统,乙醇反应速率最快,投加量最省,费用最低.复合碳源系统,乙酸钠/葡萄糖(1∶1)在COD/ρ(N)为6时,与乙酸钠/葡萄糖(1∶3)、乙醇/葡萄糖(1∶1)和乙醇/葡萄糖(1∶3)在COD/ρ(N)为9、10和10时的效果相当,且乙酸钠/葡萄糖(1∶1)系统反应速率最快且经济性最好.Illumina MiSeq高通量测序显示,经70 d左右的运行,微生物群落结构发生根本性变化.在与葡萄糖相关的系统,常规脱氮系统不常见的菌门Candidatus Saccharibacteria,丰度从种泥的1.16%提高到47.37%;相应地,在属水平Saccharibacteria_genera_incertae_sedis成为绝对优势菌种.研究结果可为污水厂尾水极限脱氮的碳源选择提供更全面的对比,也为碳源在微生物菌群驯化方面的作用提供更多参考和借鉴.

Adding external carbon sources is an important method for advanced nitrogen removal of secondary effluent in wastewater treatment plants(WWTPs).In order to compare the denitrification performance and economy of different carbon sources sufficiently,as well as the effect of long-term addition of carbon sources on the microbial population structure,four single carbon sources(methanol,ethanol,glucose,and sodium acetate)and four types of composite carbon sources were prepared by mixing sodium acetate and ethanol with a higher reaction rate and cheap glucose.The results showed that the effluentρ(NO_(x)^(-)-N)concentration of all systems was less than 1.0 mg·L^(-1)during the experiment.For single-carbon source systems,ethanol had the fastest denitrification rate,followed by sodium acetate and methanol;that of the glucose was the slowest.In the composite carbon source systems,the sodium acetate/glucose(1∶1)with COD/ρ(N)was 6,which was equivalent to the results of sodium acetate/glucose(1∶3),ethanol/glucose(1∶1),and ethanol/glucose(1∶3)with COD/ρ(N)of 9,10,and 10,respectively.The sodium acetate/glucose(1∶1)system had the fastest reaction rate and the best economy.High-throughput sequencing results showed that after more than 70 days of operation,the structure of the microbial community had changed completely.In the glucose-related system,the abundance of Candidatus Saccharibacteria,which is not popular in typical nitrogen removal systems,increased from 1.16%of seed sludge to 47.37%,and Saccharibacteria_genera_incertae_sedis correspondingly became the dominant community.This study not only provides a more comprehensive comparison for the selection of carbon sources in WWTPs with ultimate nitrogen removal but also provides basic data for the role of carbon sources in the domestication of microbial communities.