Ozone micron bubble pretreatment for antibiotic resistance genes reduction in hospital wastewater treatment

Ozone micron bubble (OMB) treatment offers a promising approach to effectively eliminate Antibiotic Resistance Genes (ARGs) from infectious medical wastewater and mitigate the threat of drug resistance transmission. This study evaluated the effectiveness of OMB treatment for reducing ARGs from infectious medical wastewater in laboratory and on-site pilot treatment setups. In part, the presence of antibiotic residues in a hospital wastewater treatment plant (WWTP) and the impact of hospital wastewater on the distribution of ARGs in a wastewater collection system were also investigated. The results of wastewater collection system survey revealed a high prevalence of ARGs in the system, particularly mcr-1, largely originating from medical wastewater discharges. Furthermore, analysis of antibiotic residues in the hospital wastewater treatment system showed significant accumulation, particularly of quinolone antibiotics, in the biomass of the biological oxidation tank, suggesting a potential risk of ARG proliferation within the system. Comparison of wastewater samples from domestic and hospital WWTPs revealed a relatively higher abundance of ARGs in the latter, with differences ranging from 2.2 to sixfold between corresponding locations in the treatment plants. Notably, the biological oxidation unit of both WWTPs exhibited a greater proportion of ARGs among all sampled points, indicating the potential proliferation of ARGs within the biomass of the treatment units. ARG degradation experiments showed that OMB treatment resulted in a significantly lower CT value (9.3 mg O3 L−1 min) compared to ozone coarse bubble treatment (102 mg O3 L−1 min) under identical test conditions. Moreover, the use of OMB on site significantly reduced the accumulation of ARGs in hospital wastewater, underscoring its potential as an effective solution for mitigating ARG spread.