Endogenous chloride ions induced HClO generation for synchronous oxidation disinfection: Performance and mechanism

Previous studies have developed numerous peroxymonosulfate (PMS) activation technologies and demonstrated remarkable decontamination efficiency for emerging contaminants represented by antibiotics in aqueous environments. However, most research has focused on investigating the decontamination effect and mechanisms using simulated solutions prepared with pure water, lacking in-depth exploration of actual wastewater treatment efficacy and mechanisms. In this study, practical aquaculture wastewater from a shrimp culture farm was selected, innovatively leveraging its high salinity characteristics to reveal the endogenous Cl − /PMS self-activation pathway for hypochlorous acid (HClO) generation. Results show that the inherent chloride and cobalt ions in the wastewater react with PMS to form active species, achieving sulfamethoxazole (SMX) degradation efficiency that surpasses systems with externally added catalysts. Through radical quenching experiments, specific probes, and electron paramagnetic resonance technology, the active species in the endogenous substances/PMS system were identified as HClO and Co(IV) = O, with contribution ratios determined to be about 80 % and 20 % respectively. Combined with density functional theory calculations and intermediate analysis, the Cl − mediated PMS activation pathway and SMX degradation intermediate formation routes were elucidated. Finally, the system also enabled synchronous removal of antibiotic-resistant bacteria (ARBs). This study provides new insights into utilizing endogenous pollutants and mechanistic interpretation during PMS-based treatment of practical wastewater, and develops a new idea of “waste treats waste” strategies.