Sulfidated nanoscale zero-valent iron is an efficient material for the removal and regrowth inhibition of antibiotic resistance genes

• Published in: Environmental pollution (1987) 2020-08, Vol.263 (Pt B), p.114508-114508, Article 114508
• Main Authors: Zhang, Wen-Zhi, Gao, Jing-Feng, Duan, Wan-Jun, Zhang, Da, Jia, Jing-Xin, Wang, Yu-Wei
• Format: Article
• Language: English
• Subjects: Antibiotic resistance genes; Mobile gene elements; Regrowth; Secondary effluents; Sulfidated nanoscale zero-valent iron
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2020.114508

Antibiotic resistance genes (ARGs) and mobile gene elements (MGEs), the emerging genetic contaminants, are regarded as severe risks to public health for impairing the inactivation efficacy of antibiotics. Secondary effluents from wastewater treatment plants are the hotspots for spreading these menaces. Herein, sulfidated nanoscale zero-valent iron (S-nZVI) was occupied to remove ARGs and MGEs in secondary effluents and weaken the regrowth capacity of their bacterial carriers. The effects of S/Fe molar ratios (S/Fe), initial pH and dosages on 16S rRNA and ARGs removal were also investigated. Characterization, mass balance and scavenging experiments were conducted to explore the mechanisms of the gene removal. Quantitative PCR (qPCR) and high throughput fluorescence qPCR showed more than 3 log unit of 16S rRNA and seven out of 10 ARGs existed in secondary effluent could be removed after S-nZVI treatment. The mechanisms might be that DNA accepted the electron provided by the Fe0 core of S-nZVI after being adsorbed onto S-nZVI surface, causing the decrease of 16S rRNA, ARGs and lost their regrowth capacity, especially for typical MGE (intI1) and further inhibiting the vertical gene transfer (VGT) and intI1-induced horizontal gene transfer (HGT). Fe0 core was oxidized to iron oxides and hydroxides at the same time. High throughput sequencing, network analysis and variation partitioning analysis revealed the complex correlations between bacteria and ARGs in secondary effluent, S/Fe could directly influence ARGs variations, and bacterial genera made the greatest contribution to ARGs variations, followed by MGEs and operational parameters. As a result, S-nZVI could be an available reductive approach to deal with bacteria and ARGs. [Display omitted] •More than 99.98% of 16S rRNA gene could be removed by S-nZVI within 60 min.•Seven out of 10 ARGs could be removed below detection limit after S-nZVI treatment.•The mechanisms of genes removal could be interpreted as adsorption and reduction.•Regrowth of 16S rRNA, ARGs and intI1 was well inhibited after S-nZVI treatment.•S-nZVI could control the spread of ARGs by vertical and horizontal gene transfer. S-nZVI, a material could adsorb and reduce ARGs, provide a reductive way for controlling the ARGs dissemination by VGT and intI1-induced HGT.