Accounting for the role of the individual treatment process in WWTPs: Study of four wastewater treatment plants receiving similar influent stream

In this study, four full-scale WWTPs fed with similar influent wastewater and operated with similar parameters were tracked over an 8-month period. The alpha- and beta-diversity analysis indicated the influent has a similar microbial community, but AS and effluent become more diverse. Sloan neutral model fitting indicated stochastic and selective synchrony assembly occurred between influent and activated sludge. SourceTracker analysis revealed that both influent and activated sludge contributed to the effluent microbial community. This stochastic assembly and source linkage could practically result from the constituent microbial consortiums. By contrast, this study also identified a group of unique bacteria, and Partial least squares-discriminant analysis (PLS-DA), Linear discriminant analysis (LDA), and Random Forest (RF) model consistently indicated these unique OTUs contributed to the microbial diversity among WWTPs. The findings suggest that both neutral (e.g. consistent bacteria) and niche (e.g. unique bacteria) theories drove the formation of different microbial signatures in WWTPs.