Polypropylene module as a new type of tank for rainwater storage and cleaner production: Purification efficacy, bacterial community microecology and potential pathogens characteristics

Abstract

Rainwater recycling is a hot issue in recent years, but polypropylene (PP) module as a new type of rainwater storage facility has not received extensive attention. This study investigated the impact of rainwater pollution level, storage time (ST) and operation mode (alternate replenishment of rainwater and reclaimed water) on the pollutants removal performance and bacterial community characteristics of PP module. Chemical oxygen demand (COD) removal efficiency increased from 24.58%–26.52% to 33.23%–42.23% with prolonged ST. Operation mode changed the purification performance, but the COD removal efficiencies in rainwater and reclaimed water were always above 28% and 42%, respectively. Operation mode exhibited the greatest impact on bacterial community structure, followed by rainwater quality and ST. The bacterial community classification in biofilm was different from that in water, but Klebsiella was always the dominant genus. Conditionally rare and abundant taxa (CRAT) and conditionally rare taxa (CRT) were identified as the hub taxa of biofilm-network and water-network, respectively. The potential pathogens in biofilm exhibited more complex interactions with non-pathogenic taxa than those in water. Klebsiella pneumoniae was the most dominant species and identified as the hub potential pathogen together with Escherichia coli in both networks. Bacterial communities in biofilm and water were significantly correlated with COD removal efficiency. These results elucidate the biological function and risk of PP module, and provide a reference for the optimization and operation management of the rainwater reuse system.