Performance comparison of O₃ and O₃/Peroxymonosulfate (PMS) advanced oxidation processes for the antibiotics removal...

Previous studies have shown that O₃/Peroxymonosulfate (PMS) outperforms O₃ alone in treating refractory pharmaceuticals and personal care products. However, research on the removal of antibiotics using O₃/PMS remains limited, and the effectiveness of this process in removing antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) remains unclear. In this study, the treatment performance of O₃ and O₃/PMS for antibiotic-containing wastewater were comprehensively compared, particularly on the effectiveness of O₃/PMS in inactivating ARB and reducing ARGs abundance compared with O₃. Within 15 min of treatment, O₃/PMS removed up to 52.3 % more targeted antibiotics, 4.8 % more dissolved organic carbon, 2.7 % more UV₂₅₄, and 18.8 % more dissolved organic matter (DOM) than O₃. For ciprofloxacin-resistant and chloramphenicol-resistant bacteria, both O₃ and O₃/PMS showed a continuous decrease in concentration with increasing treatment time. For amoxicillin-resistant, tetracycline-resistant, and sulfamethoxazole-resistant bacteria, O₃ showed an initial increase followed by a subsequent decrease, while O₃/PMS showed a similar trend for tetracycline- and sulfamethoxazole- resistant bacteria, but a continuous decrease for amoxicillin-resistant bacteria. For ARGs, before 8 min, O₃ treatment showed a higher relative abundance of targeted ARGs (0.01-0.31 ARGs/16S rRNA), mainly due to tetQ. After 8 min, O₃/PMS treatment exhibited a higher relative abundance of ARGs/16S rRNA (0.04-0.05), primarily due to floR. At the phylum level, PMS addition increased Bacteroidota abundance while reducing Proteobacteria, Chloroflexota, and Myxococcota_A_473307. At the class level, PMS specifically promoted Alphaproteobacteria and Bacteroidia while inhibiting Gammaproteobacteria and UBA9160. Finally, the acute toxicity of O₃/PMS-treated wastewater was 14.6 % lower than that of O₃-treated wastewater at 2 min. However, after 6 min, the toxicity of O₃/PMS-treated wastewater became significantly higher, with the largest difference (23.6 %) observed at 8 min. The results indicated that O₃/PMS had an advantage over O₃ in removing antibiotics, DOM, and controlling ARB. However, prolonged treatment increased ARGs diversity and concentration compared to O₃ and significantly enhanced the acute toxicity of antibiotic-containing wastewater.