Inactivation of antibiotic resistance genes in municipal wastewater by chlorination, ultraviolet, and ozonation disinfection

Abstract

This study investigated the inactivation of two antibiotic resistance genes (ARGs)-sul1 and tetG, and the integrase gene of class 1 integrons-intI1 by chlorination, ultraviolet (UV), and ozonation disinfection. Inactivation of sul1, tetG, and intI1 underwent increased doses of three disinfectors, and chlorine disinfection achieved more inactivation of ARGs and intI1 genes (chlorine dose of 160 mg/L with contact time of 120 min for 2.98-3.24 log reductions of ARGs) than UV irradiation (UV dose of 12,477 mJ/cm(2) for 2.48-2.74 log reductions of ARGs) and ozonation disinfection (ozonation dose of 177.6 mg/L for 1.68-2.55 log reductions of ARGs). The 16S rDNA was more efficiently removed than ARGs by ozone disinfection. The relative abundance of selected genes (normalized to 16S rDNA) increased during ozonation and with low doses of UV and chlorine disinfection. Inactivation of sul1 and tetG showed strong positive correlations with the inactivation of intI1 genes (for sul1, R (2) = 0.929 with p < 0.01; for tetG, R (2) = 0.885 with p < 0.01). Compared to other technologies (ultraviolet disinfection, ozonation disinfection, Fenton oxidation, and coagulation), chlorination is an alternative method to remove ARGs from wastewater effluents. At a chlorine dose of 40 mg/L with 60 min contact time, the selected genes inactivation efficiency could reach 1.65-2.28 log, and the cost was estimated at 0.041 yuan/m(3).

Removal of Tetracycline and Tetracycline Resistance Genes from Municipal Wastewater in Microcosm Fill-and-Drain Constructed Wetlands

“…The removal effi ciencies of tet genes by our CWs and those of the previous CWs are comparable to the removal effi ciencies of ARGs, such as tetG, by chlorination (3.24 log reductions), ultraviolet (2.48 log reductions), and ozonation (2.55 log reductions) processes 30) . The results clearly indicated that CWs appear to be an advanced treatment process to prevent the discharge of large amount of tet genes from the wastewater treatment plants.…”

Editorial: Antibiotic Resistance in Aquatic Systems

“…Although advanced disinfection facilities can greatly reduce the danger of waterborne diseases (United States Environmental Protection and Agency, 2004), antibiotics and ARGs can still be released to the environment in disinfected effluents (Michael et al, 2013; Rizzo et al, 2013; Berkner et al, 2014; Carey and McNamara). Recent works report the improvement of disinfection in terms of ARG removal (Munir et al, 2011; McKinney and Pruden, 2012; Guo et al, 2013; Yuan et al, 2015; Zhuang et al, 2015). …”

Disinfectant residuals in drinking water systems select for mycobacterial populations with intrinsic antimicrobial resistance

“…The majority of genes associated with this mechanism are dfr and sul genes which are both related to folic metabolism and are widespread in the environment, being predominantly located on plasmids or transposons 66 . It has been observed that the inactivation of ARGs such as sul1 from municipal wastewater is most effective with chlorination, followed by UV and ozonation 67 which could explain the infrequency of detection of these genes in Dis systems. Finally, genes associated with reduced permeability mechanism were only observed under the “loose” sequence similarity threshold for the NonDis samples and only constituted 0.21% of all detected AROs.…”