A chemical, microbiological and (eco)toxicological scheme to understand the efficiency of UV-C/H2O2 oxidation on antibiotic-related microcontaminants in treated urban wastewater

Abstract An assessment comprising chemical, microbiological and (eco)toxicological parameters of antibiotic-related microcontaminants, during the application of UV-C/H2O2 oxidation in secondary-treated urban wastewater, is presented. The process was investigated at bench scale under different oxidant doses (0–50 mg L−1) with regard to its capacity to degrade a mixture of antibiotics (i.e. ampicillin, clarithromycin, erythromycin, ofloxacin, sulfamethoxazole, tetracycline and trimethoprim) with an initial individual concentration of 100 μg L−1. The process was optimized with respect to the oxidant dose. Under the optimum conditions, the inactivation of selected and antibiotic resistant bacteria (ARB) (i.e. faecal coliforms, total enterococci, Pseudomonas spp. and total heterotrophs), and the reduction of the abundance of selected antibiotic resistance genes (ARGs) (e.g. blaOXA, qnrS, sul1, tetM) were investigated. Also, phytotoxicity against three plant species, ecotoxicity against Daphnia magna, genotoxicity, oxidative stress and cytotoxicity were assessed. Apart from chemical actinometry, computational fluid dynamics (CFD) modelling was applied to estimate the fluence rate. For the given wastewater quality and photoreactor type used, 40 mg L−1 H2O2 were required for the complete degradation of the studied antibiotics after 18.9 J cm−2. Total bacteria and ARB inactivation was observed at UV doses