Sequential ¹O₂ and Chlorine-Radical Oxidation in an Electrofiltration System Enables Cost-Effective Control of...

Chlorine-based advanced oxidation processes (AOPs) offer promise for controlling antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs), yet their performance is often constrained by extracellular polymeric substance (EPS) barriers, reactive species (RSs) scavenging, and oxidative stress-induced resilience. Here, we employed an electrofiltration system incorporating electrically induced pH stratification to efficiently activate NaClO/H₂O₂, thereby establishing a sequential oxidation regime that begins with an early ¹O₂-dominated stage followed by a chlorine radical-dominated stage. The system achieved complete ARB inactivation (≥7.33 log) and efficient ARG degradation (≥99.3%) within 10 min and effectively suppressed ARB regrowth, horizontal ARG transfer, and disinfection byproduct (DBP) generation. Steady-state probe analyses, quenching experiments, and phosphorescence emission detection indicated that early-stage ¹O₂ selectively disrupted external cell structures while suppressing oxidative stress defenses, whereas subsequent accumulation of chlorine radicals enabled rapid and irreversible ARG degradation. The system maintained robust performance in treating real hospital wastewater (HW) and significantly reduced both concentration-time (CT) requirements and specific energy consumption (SEC) for ARG degradation compared with other advanced disinfection processes. These results demonstrate a practical and low-energy strategy for controlling antibiotic resistance through reactive-species-transition-driven disinfection.