Removal and distribution of antibiotics and resistance genes in conventional and advanced drinking water treatment processes

With the extensive detection of antibiotics and antibiotic resistance genes (ARGs) in drinking water treatment plants, the safety of drinking water has received increased attention. Therefore, the distribution and removal of antibiotics and ARGs in drinking water systems require further investigation. In this study, nine typical antibiotics, nine ARGs, and one integron in two drinking water plants were investigated by high pressure liquid chromatography with tandem mass spectrometry and real-time quantitative polymerase chain reaction analyses. Sulfonamides were the dominant antibiotic in the two drinking water treatment plants (WP-A and WP-B). The removal effect of advanced water treatment on total antibiotic concentration was significantly higher than that of conventional treatment. Sul gene was the dominant gene in the raw water of the two plants. After undergoing different treatment units, the finished water in WP-A and WP-B exhibited Sul gene concentrations of 54.06 genes/mL and 67.9 genes/mL, respectively. In the conventional treatment process, adding a sand filtration unit before the flocculation unit can improve the removal efficiency of antibiotics and ARGs. In the advanced treatment process, the post ozonization unit using the strong oxidation of O3 could effectively remove antibiotics and ARGs. Although the activated carbon unit can effectively remove antibiotics, the removal effect of ARGs is poor. Chlorination has a poor effect on the removal of antibiotics, but it can effectively remove ARGs. This study can provide a basis for understanding the fate of antibiotics and ARGs in drinking water systems.