Change characteristics, bacteria host, and spread risks of bioaerosol ARGs/MGEs from different stages in sewage and sludge treatment process.

The spread of antibiotic resistance genes (ARGs) in the atmospheric environment has seriously threatened human health. Wastewater treatment plants (WWTPs) are an important source of aerosol ARGs. A large WWTP, including sewage treatment process (SWP) and sludge treatment process (SDP), was selected in North China for sampling in this study. The content of ARGs, mobile genetic elements (MGEs), and bacterial genera in sewage/sludge and aerosols from different process stages was detected. The possible correlation between ARGs/ MGEs and bacteria was analyzed. The risk of antibiotic-resistant bacteria was evaluated and the diffusion of ARGs/MGEs was simulated. The results showed that the concentration of ARGs/MGEs varied as the process progressed, and which in the aeration tank was relatively high. The ARGs/MGEs content in SWP aerosol (8.35-163.27 copies/m) was higher than that in SDP (5.52-16.36 copies/m). The main ARGs/MGEs detected in SWP aerosol were tnpA-05, tnpA-04, and ermF, while the main ARGs/MGEs detected in SDP aerosol were sul1, ermF, and blaPAO. ARGs were positively correlated with most bacteria and Escherichia coli with ARGs carries higher cytotoxicity. ARGs/MGEs mainly diffused towards the southeast, which may cause harm to urban residents with the diffusion of aerosols. This study provides clues and theoretical basis for preventing the hazards of ARGs from WWTP sources.