Unraveling the Key Factors Affecting the Bacterial Community and ARGs in Full-Scale Drinking Water Biological Activated Carbon Filters: Enriched Antibiotics

As a conventional adsorption unit, biological activated carbon (BAC) filtration may possess the enrichment risk of emerging contaminants, which is worth investigating in full-scale drinking water treatment plants. This work evaluated the enrichment of antibiotics, heavy metals, and antibiotic resistance genes (ARGs) in full-scale BAC filters and explored the corresponding enrichment mechanisms. The enrichment of antibiotics in BAC filters was observed, with the total contents of 10 detected antibiotics reaching over 400 ng/g. A serious antibiotics leakage of BAC filters was found during the winter with the total concentrations of antibiotics in the water increased from 156.4 ng/L (influent) to 236.5 ng/L (effluent). According to the redundancy analysis and variation partitioning analysis results, the bacterial community of BAC biofilms was significantly affected by the enriched antibiotics in which roxithromycin contributed the most (31.8%). The enriched antibiotics and heavy metals dominantly contributed to the variation of ARGs in BAC with the explanation of 27 and 20%, respectively. This work revealed that the enriched antibiotics were the key factors affecting the bacterial community and ARGs in BAC and provided a theoretical basis for the optimization of BAC-based water treatment processes.