Simultaneous removal of oxytetracycline and antibiotic-resistant bacteria during ozonation of clarified pharmaceutical wastewater

Sanitation of antibiotics production wastewater using a recognized alternative for disinfection is extremely critical for subsequent use and environmental protection as well. In this study, ozonation was used to treat a real oxytetracycline production wastewater. The experiments were conducted in laboratory scale using an ozonation reactor, which was operated in semi-batch mode. Antibiotics were efficiently degraded from 928 ± 23 to 3.3 ± 0.2 µg/L, corresponding to the removal efficiency of 99.6 % at ozone consumption of 250.7 mg/L. Ozone consumptions of 82.6, 166.4, and 250.7 mg/L significantly (p < 0.01) inactivated bacterial growth by 63.9 %, 94.5 %, and 99.99 %, respectively. Further, the absolute abundances of antibiotic resistance genes (ARGs) were significantly (p < 0.01) decreased and some of the tet genes such as tetC, tetQ, and tetX lied below the detection limit after ozonation. The bacterial community showed various responses to ozone consumptions. Pseudomonas was the most dominant genus in all treatments that gradually decreased (34.07 % to 27.35 %) with the increase of ozone consumption. Overall, the results of this study highlighted that ozonation is an efficient process for treatment of oxytetracycline production wastewater in terms of degradation of antibiotics, removal of ARGs, and inactivation of microorganisms.