Enhanced removal of ciprofloxacin and associated antibiotic-resistant genes from wastewater using a biological aeration filters in combination with Fe3O4-modified zeolite

The release of antibiotics into the water environment through sewage discharge is a significant environmental concern. In the present study, we investigated the removal of ciprofloxacin (CIP) in simulated sewage by biological aeration filter (BAF) equipped with Fe3O4-modified zeolite (Fe3O4@ZF). Fe3O4@ZF was prepared with the impregnation method, and the Fe3O4 particles were successfully deposited on the surface of ZF in an amorphous form according to the results of XPS and XRD analysis. The modification also increased the specific surface area (from 16.22 to 22 m(2)/g) and pore volume (from 0.0047 to 0.0063 cm(3)/g), ultimately improving the adsorption efficiency of antibiotics. Fe3O4-modified ZF could improve the treatment performance significantly, and the removal efficiency of CIP in BAF-Fe3O4@ZF was 79 +/- 2.4%. At a CIP influent concentration of 10 mg/L, the BAF-Fe3O4@ZF reduced the relative abundances of antibiotic-resistant genes (ARGs) int, mexA, qnrB, and qnrS in the effluent by 57.16, 39.59, 60.22, and 20.25%, respectively, which may effectively mitigate the dissemination risk of ARGs. The modification of ZF increased CIP-degrading bacteria abundance, such as Rhizobium and Deinococcus-Thermus, and doubled bacterial ATP activity, promoting CIP degradation. This study offers a viable, efficient method to enhance antibiotic treatment and prevent leakage via sewage discharge.