Characterization of Microbial Communities in Wastewater Treatment Plants Containing Heavy Metals Located in Chemical Industrial Zones

Water pollution caused by heavy metals (HMs) poses a serious risk to human health and the environment and can increase the risk of diabetes, cancer, and hypertension in particular. In this study, two full-scale wastewater treatment plants (WWTPs) in industrial zones in southern China were selected to analyze the microbial community structure, diversity, similarity, and differentiation in the anoxic/oxic (AO) and anoxic/oxic membrane bioreactor (AO-MBR) units under the stress of HMs. High-throughput sequencing showed that microbial diversity and abundance were higher in the AO process than in the AO-MBR process. In the two WWTPs, the common dominant phyla were Proteobacteria and Bacteroidetes, while the common dominant genera were Gemmatimonadaceae, Anaerolineaceae, Saprospiraceae, and Terrimonas. Manganese (Mn) and zinc (Zn) positively correlated with Saccharimonadales, Nakamurella, Micrococcales, and Microtrichales, whereas copper (Cu) and iron (Fe) positively correlated with Longilinea and Ferruginibacter. Additionally, the relative abundances of Chloroflexi, Patescibacteria, and Firmicutes differed significantly (p < 0.05) between the two processes. These results may provide comprehensive outlooks on the characterization of microbial communities in WWTPs, which could also help to reduce the potential environmental risks of the effluent from WWTPs located in industrial zones.