溶解氧对HLB-MR反应器内有机物的生物絮凝影响

为了研究溶解氧（DO）对高负荷生物絮凝-膜反应器（HLB-MR）内有机物生物絮凝规律的影响，采用平行对比实验，考察了不同DO条件下反应器内有机物的生物絮凝效果、胞外聚合物（EPS）含量、金属阳离子浓度和微生物群落结构.结果表明：DO浓度分别为1~2mg/L和6~8mg/L时，HLB-MR反应器的絮凝效率分别为83%和89%，两反应器内上清液的浊度差别也进一步证实，较高的DO浓度下，反应器的生物絮凝效果更好.DO浓度在6~8mg/L时，HLB-MR反应器内结合态EPS和自由态EPS的含量分别为15.64mg/（g·VSS）和8.71mg/L，两者均显著高于DO为1~2mg/L时的11.83mg/（g·VSS）和6.56mg/L，反应器浓缩液中镁和铝的浓度也均明显高于低DO浓度时所对应的值，这说明在高DO条件下，有更多的EPS与金属阳离子结合而固定在污泥基质中，促进了生物絮凝.高通量测序表明，DO浓度分别为1~2mg/L和6~8mg/L时，HLB-MR反应器内细菌的群落结构差异明显，高DO浓度反应器底泥中Actinobacteria和Saccharibacteria的相对丰度较高，可能对生物絮凝有促进作用.

Effect of dissolved oxygen on bioflocculation of organic matter in high loaded bioflocculation membrane reactor

In order to study the effect of dissolved oxygen (DO) on bioflocculation law of organic matter in high loaded bioflocculation membrane reactor (HLB-MR), parallel contrast experiments were conducted to investigate the bioflocculation effect of organic matter, the content of extracellular polymeric substance (EPS), the concentration of metal cations and the microbial community structure under different DO conditions. When the DO concentrations were at 1~2mg/L and 6~8mg/L, the flocculation efficiencies of HLB-MRs were 83% and 89%, respectively. The difference in turbidity of the supernatant in the HLB-MRs further confirmed that the higher DO concentration had induced a better bioflocculation effect. When the DO concentration was at 6~8mg/L, the content of bound EPS and supernatant EPS in the HLB-MR were 15.64mg/(g·VSS) and 8.71mg/L, respectively, both of which were significantly higher than 11.83mg/(g·VSS) and 6.56mg/L at 1~2mg/L of DO concentration, and the concentrations of magnesium and aluminum in the concentrate in the HLB-MR were also significantly higher than those at 1~2mg/L of DO concentration. Under high DO concentration conditions, more EPS are combined with metal cations to be immobilized in the sludge matrix, which promotes bioflocculation. High-throughput sequencing showed that when the DO concentrations were at 1~2mg/L and 6~8mg/L, the community structure of bacteria in the HLB-MRs were significantly different. The relative abundance of Actinobacteria and Saccharibacteria in the sediment of HLB-MR at higher DO concentration were higher, which might promote bioflocculation.