Oxalated zero-valent iron catalyzed ozonation for effective removal of antibiotic resistance genes from municipal sewage sludge

Wastewater treatment plants (WWTPs) are hotspots of antibiotic resistance genes (ARGs), and efficient technologies are needed to prevent the enrichment and spread of ARGs in municipal sludge. Herein, we demonstrated that oxalated zero-valent iron (OA-ZVIbm) catalyzed ozonation could effectively remove typical ARGs, tetG and sul1, from municipal sewage sludge, with the total abundance reduced by 3.02 and 2.00 log per gram sludge, respectively, surpassing the O-3 alone and O-3/ZVI(bm) counterparts. Meanwhile, the O-3/OA-ZVI(bm) treatment could simultaneously remove both intracellular and extracellular ARGs from the sludge, moreover, it also eliminated 1.83 log total Class 1 integron (total intI1), thus may suppress the horizontal gene transfer (HGT) potential of ARGs. The good performance of O-3/OA-ZVI(bm) was owing to the FeC2O4 center dot 2H(2)O shell of ZVI, which improved the accessibility of core iron species to catalyze the decomposition of O-3, producing more reactive oxygen species (ROSs) including center dot OH, center dot O-2(-), and O-1(2), for the removal of ARGs. This study provides a new method to control the dissemination of ARGs in sewage sludge.

Automated summary

In this study, oxalated zero-valent iron (OA-ZVIbm) catalyzed ozonation was demonstrated to effectively remove typical antibiotic resistance genes (ARGs) tetG and sul1 from municipal sewage sludge, surpassing the performance of ozone alone and ozone/zero-valent iron counterparts. The treatment also eliminated total Class 1 integron (total intI1) and may suppress the horizontal gene transfer potential of ARGs. The good performance of the treatment was attributed to the FeC2O4 center dot 2H(2)O shell of ZVI, which enhanced the accessibility of core iron species for the decomposition of ozone and the production of reactive oxygen species (ROSs) for ARG removal.