RESUMEN
The removal of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) using sulfate anion radical (SO4â¢-)-based advanced oxidation processes has gained considerable attention recently. However, immense uncertainties persist in technology transfer. Particularly, the impact of dichlorine radical (Cl2â¢-) generation during SO4â¢--mediated disinfection on ARB/ARGs removal remains unclear, despite the Cl2â¢- concentration reaching levels notably higher than those of SO4â¢- in certain SO4â¢--based procedures applied to secondary effluents, hospital wastewaters, and marine waters. The experimental results of this study reveal a detrimental effect on the disinfection efficiency of tetracycline-resistant Escherichia coli (Tc-ARB) during SO4â¢--mediated treatment owing to Cl2â¢- generation. Through a comparative investigation of the distinct inactivation mechanisms of Tc-ARB in the Cl2â¢-- and SO4â¢--mediated disinfection processes, encompassing various perspectives, we confirm that Cl2â¢- is less effective in inducing cellular structural damage, perturbing cellular metabolic activity, disrupting antioxidant enzyme system, damaging genetic material, and inducing the viable but nonculturable state. Consequently, this diminishes the disinfection efficiency of SO4â¢--mediated treatment owing to Cl2â¢- generation. Importantly, the results indicate that Cl2â¢- generation increases the potential risk associated with the dark reactivation of Tc-ARB and the vertical gene transfer process of tetracycline-resistant genes following SO4â¢--mediated disinfection. This study underscores the undesired role of Cl2â¢- for ARB/ARGs removal during the SO4â¢--mediated disinfection process.