F/M对活性污泥微生物生态网络的影响

为深入理解有机负荷率(F/M)对活性污泥(AS)微生物群落的影响,以F/M(以BOD/MLVSS计,下同)设计建议范围0.2～0.5 kg·(kg·d)-1为依据,将采集的AS样品分为3组,运用基于随机矩阵理论(RMT)的网络分析方法,解析了不同F/M条件下的AS微生物生态网络拓扑性质及结构特征.结果表明,较低的F/M...

Impacts of F/M Ratio on Microbial Networks in Activated Sludge

The performance of wastewater treatment plants (WWTPs) mainly relies on the microbial community in activated sludge (AS). The food to microorganisms (F/M) ratio is an important operational parameter, the recommended value of which is between 0.2 and 0.5 kg·(kg·d)^-1. The F/M directly influences microbial growth and metabolism, but how the F/M ratio affects AS microbial networks and the related mechanisms remain unclear. In this study, 63 AS samples with different F/M ratios were analyzed by utilizing a random-matrix-theory based network pipeline. Firstly, all 63 samples were divided into three groups based on their F/M ratios (lower F/M group, normal F/M group, and higher F/M group). The results indicated that the lower F/M decreased microbial diversity and evenness significantly, but the higher F/M had no significant effects on the diversity of the microbial community. All three constructed networks were scale-free, small world, and modular, but network size and complexity were decreased in the lower and higher F/M groups. The network of the normal F/M ratio group was detected with the most nodes, the highest average clustering coefficient, and the shortest geodesic distance. The proportion of positive links was 76.8% when the F/M was within the normal range. On the contrary, 71.1% and 60.0% of positive links were identified when the F/M was below 0.2 and above 0.5 kg·(kg·d)^-1. Moreover, 24 keystones were detected in the normal F/M network, whereas only 4 and 7 keystones were detected in the lower and higher F/M networks. Overall, our results provided clear evidence that the AS microbial community could be more stable and resilient to environmental disturbance when the F/M ratio was between 0.2 and 0.5 kg·(kg·d)^-1.