冬季低温下MBR与CAS工艺运行及微生物群落特征

研究了在冬季低温条件下,膜生物反应器(MBR)与传统活性污泥法(CAS)工艺运行效果及微生物群落特征的差异,对工艺出水水质和微生物活性进行了分析,并借助454焦磷酸高通量测序法对微生物群落组成和结构进行了解析.结果表明,三套对比工艺(MBR两套:高污泥浓度R1和低污泥浓度R2,CAS工艺R3)的出水总氮平均去除率分别为85.2%、56.1%、58.8%;NH+4-N的平均去除率分别为99.7%、99.7%、59.7%,比硝化速率由大到小依次为R2、R1、R3,比反硝化速率由大到小依次为R3、R1、R2,高浓度MBR污泥具有较好的耐寒特性和氨氮去除效果;从454焦磷酸测序结果看,相似性为97%时,菌群丰富度:R2>R3>R1,多样性:R2>R1>R3;MBR污泥微生物菌群的组成和丰度与CAS系统有较大不同;R1、R2、R3中主要的硝化菌为Nitrospira菌属,总相对度依次为:1.22%、1.64%、0.15%,主要的反硝化菌为Zoogloea菌属、Thauera菌属、Comamonadaceae菌属及Comamonas菌属,总相对丰度依次为:5.8%、4.52%、15.21%;低温环境下,泥龄长、污泥浓度高、TN负荷低的MBR系统有利于硝化、反硝化细菌累积,提升生物脱氮效果.

Diversity of Operation Performance and Microbial Community Structures in MBRs and CAS Processes at Low Temperature

In this paper, the performance of membrane bioreactors (MBR) and conventional activated sludge (CAS) processes at low temperature was investigated by analyzing their effluent quality and microbial viability. 454 high-throughput pyrosequencing was also applied to study the microbial community structures. The results of three systems (two MBRs: R₁ with high sludge concentration, R₂ with low sludge concentration, and one CAS: R₃) showed that the average removal rate of NH₄⁺-N was 99.7%, 99.7% and 59.7%, respectively, and the average removal rate of TN was 85.2%, 56.1% and 58.8%, respectively. R₂ showed the highest specific ammonium uptake rate (SAUR), followed by R₁ and R₃; R₁ showed the highest specific nitrate uptake rate (SNUR), followed by R₂ and R₃. It could be concluded that MBRs with high sludge concentration had a better performance of nitrogen removal under low temperature operation. 454 high-throughput pyrosequencing analysis revealed that the microbial richness was R₂ >R₃ >R₁, and the microbial diversity was R₂ >R₁ >R₃ at 97% sequence identity. The microbial structure and bacterial abundance were quite different between MBR and CAS systems. The dominant nitrifier in this research was Nitrospira, and the total relative abundance of nitrifiers in R₁, R₂, R₃ was 1.22%, 1.64% and 0.15%, respectively. The Zoogloea, Thauera, Comamonadaceae and Comamonas might be the dominant denitrifers in this study, and the total relative abundance of denitrifier in R₁, R₂, and R₃ was 5.8%, 4.52% and 15.21%, respectively. MBR's characteristics of long solid retention time, high sludge concentration and low total nitrogen loading well supported the accumulation of nitrifiers and denitrifiers, and improved the performance of biological nitrogen removal at low temperature.