Safe reuse of wastewater: Effect of disinfection methods on microbial community

Abstract

Performic acid (PFA), a new generation of disinfectant, has shown outstanding performance for wastewater treatment. However, the effect of PFA on wastewater microbial community changes as well as the differences in comparison to the commonly disinfectants used are poorly documented. We provide an overview of the PFA effect and that of chlorine and UV, two commonly used disinfectants, on microbial community diversity and structure. The study was performed using wastewaters from three municipal wastewater treatment plants (WWTPs) processed by activated sludge, lagoon and reed beds, and biofilter. We focused on disinfection of pathogen microorganisms, identifying sensitive and resistant bacteria to disinfectants that can serve as biomarkers for evaluating the disinfectant performances. As well, we investigated the modifications of microbial functions after treatment by functional predictive analysis. The more efficient E. coli inactivation was obtained with initial concentration of 4 mg/L of PFA with 15 min disinfectant contact time that achieved 95.71–99.99% inactivation efficiency. Although the origin of wastewater was the main factor determining the microbial community diversity and composition, the microbial communities were specific to the disinfectant used. Linear discriminant analysis Effect Size (LEfSe) identified 18 and 10 biomarkers, including pathogenic microorganisms affiliated to Chromobacterium, Flavobacterium, Aeromonas, Enterobacteriaceae, Escherichia_Shigella and Fusobacteriaceae, which were sensitive to PFA, while being resistant to chlorine and/or UV. Consistently, the predicted bacterial functional patterns diverged according to the wastewater origin and the disinfectant used. Pathogen microorganisms were more sensitive to PFA than the other treatments, demonstrating its potential for implementing a safe reuse of wastewater.