The impact of chlorine-assisted backwashing at different operational stages on the operational performance and effluent safety of upflow biological activated carbon filters
This study focused on a laboratory-scale upward-flow bio-activated carbon (BAC) column, systematically comparing three operational strategies: conventional air-water backwashing, chlorine-assisted backwashing during the start-up period, and chlorine-assisted backwashing during the stable operation period. Under long-term operational conditions, the study comprehensively evaluated the effects of different backwashing methods on the removal performance of organic matter and ammonia nitrogen by BAC, surface biomass, and activated carbon adsorption capacity. Additionally, it further analyzed the ecological mechanisms of chlorine-assisted backwashing at different time periods from the perspectives of microbial community structure, assembly mechanisms, and molecular ecological network interactions. Simultaneously, the study systematically assessed the safety of the effluent from biological and chemical risk aspects. The findings provide a theoretical basis and practical reference for optimizing the backwashing process of upward-flow BAC and controlling biological safety risks in drinking water.