On the capacity of ozonation to remove antimicrobial compounds, resistant bacteria and toxicity from urban wastewater effluents

The degradation of erythromycin (ERY) and ethylparaben (EtP) in urban wastewater effluents at low concentration level during ozonation was investigated under different experimental conditions. Both substrates were rapidly eliminated within 2 min at low ozone dose of 0.3 mg L−1 and the experimental data were well fitted in the pseudo-first-order kinetic model. The ratio of HO•- and O3-exposure (Rct) at the inherent pH was found to be 1.9 × 10−8 . The degradation of ERY and EtP was pronounced at pH 8 compared to acidic pH conditions, while the degradation rate of both substrates was found to be matrix- depended. It was also shown that both O3- and HO•-mediated pathways are involved in the degradation of EtP, whereas the saturated-rich structure of ERY renders it O3- recalcitrant. Under the optimum O3 dose, the BrO3− concentration was found to be lower than 10 gL−1. Five and fifteen transformation products were elucidated during ERY and EtP oxidation, respectively. The root and shoot inhibition can be attributed to the oxidation products formed upon dissolved effluent organic matter transformation. Escherichia coli harbouring resistance to ERY survived ozonation better than EtP-resistant E. coli. However, neither ERY- nor EtP-resistant E. coli were detected after 15 min of ozonation.his work was carried out in the framework of the KOΥΛTOΥPA/ВENS/0412/24 research project 'Closing Gaps of Knowledge with respect to Advanced Chemical Oxidation Processes for the Removal of Contaminants of Emerging Concern (GAPS)', implemented within the national framework program for research, technological development and innovation 'DESMH 2009–2010'. Nireas-IWRC (NEA ΥΠOΔOMH/ΣTPATH/0308/09) was co-financed by the Republic of Cyprus and the European Regional Development Fund through the Research Promotion Foundation of Cyprus. The authors would like to acknowledge the COST-European Cooperation in Science and Technology Action ES1403: New and emerging challenges and opportunities in wastewater reuse (NEREUS), for stimulating the work implemented in the manuscript