Synergistic elimination of antibiotic resistance genes and tetracycline antibiotics in wastewater via a Z-scheme Bi2WO6/g-C3N4 heterojunction: degradation pathways and mechanism

Abstract

Antibiotics and antibiotic resistance genes (ARGs) pose a serious threat to ecosystems and human health. Photocatalytic technology is a hotspot in the pollutant purification. A novel Z-scheme Bi₂WO₆/g-C₃N₄ heterojunction was successfully synthesized and demonstrated exceptional photocatalytic efficacy illuminated by visible light, effectively degrading three different tetracycline antibiotics, and it more over demonstrated impressive effectiveness in ARGs from secondary effluent. The removal rates for 16S rRNA, intI1, tetA, tetC, sulI and sulII were notably high, with reductions of 3.04 log, 2.88 log, 3.15 log, 3.68 log, 2.71 log and 2.64 log, respectively. And the removal of DOC in secondary effluents is of great significance for reducing ARGs. h⁺ and ˙O₂⁻ were validated to be primary active substances for removing TCs and ARGs in the process. Active species can directly destroy the structure of microbial cells and cause DNA damage. 16S rRNA, intI1 and DOC were significant positive correlations with ARGs. The migration pathway of photogenerated carriers on the surface of Z-scheme heterojunction and photocatalytic degradation mechanism for removing TCs and ARGs were also studied. Finally, degradation byproducts, process and pathways of TC were investigated. This study presents a novel strategy for efficiently removing TCs and ARGs, thereby mitigating the spread of them.