Iron-driven removal of antibiotic resistance genes in wastewater treatment plants: Mechanisms, performance, and prediction

Antibiotic resistance genes (ARGs) in wastewater treatment plants (WWTPs) pose a significant threat to environmental and public health. Iron-based materials have been shown to enhance ARG removal through multiple pathways, but their efficiency, underlying mechanisms, and operational feasibility remain insufficiently characterized. In this study, we collected 2586 records from 41 studies encompassing 92 ARG subtypes and evaluated Fe-driven ARG removal across diverse reaction systems. Feature analysis identified initial pH, reaction system, sequence size, residence time, and Fe dosage as key determinants of removal efficiency. Mechanistic analysis revealed four major pathways: reactive oxygen species oxidation, inhibition of horizontal and vertical gene transfer, microbial community modulation, adsorption/reduction, flocculation. Nationwide predictions for 166 WWTPs in China indicated Fe(IV) achieved the highest removal efficiencies, whereas Fe(III) provided the most favorable balance among predicted removal performance, reagent cost, and engineering maturity. However, the findings are most applicable to Chinese WWTP conditions, and the full-scale application of Fe(IV) requires cautious interpretation. This study provides a quantitative framework for Fe-based ARG removal and supports region-specific optimization strategies to reduce ARG dissemination while maintaining economic and operational feasibility.