Journal of Hazardous Materials 323 (2017) 414–425 Contents lists available at ScienceDirect Journal of Hazardous Materials jo ur nal ho me p ag e: www.elsevier.com/locate/jhazmat On the capacity of ozonation to remove antimicrobial compounds, resistant bacteria and toxicity from urban wastewater effluents I. Michael-Kordatou a , R. Andreou a , M. Iacovou a , Z. Frontistis a,b , E. Hapeshi a , C. Michael a , D. Fatta-Kassinos a,∗ a Department of Civil and Environmental Engineering and Nireas-International Water Research Centre, School of Engineering, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus b Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece h i g h l i g h t s • Erythromycin and ethylparaben were rapidly eliminated within 2 min at low O 3 doses. • 5 Transformation products (TPs) were identified retaining the ERY lactone ring. • EtP structural alterations took place at the ethyl ester chain yielding 15 TPs. • Phytotoxicity can be attributed to the organic matter and its oxidation products. • ERY- and EtP-resistant E. coli were eliminated after 15 min of ozonation. g r a p h i c a l a b s t r a c t a r t i c l e i n f o Article history: Received 14 December 2015 Received in revised form 6 February 2016 Accepted 9 February 2016 Available online 11 February 2016 Keywords: Antimicrobials Bacterial resistance Ozonation Phytotoxicity Transformation products a b s t r a c t 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 O 3 -exposure (R ct ) 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 O 3 - and HO • -mediated pathways are involved in the degradation of EtP, whereas the saturated-rich structure of ERY renders it O 3 -recalcitrant. Under the optimum O 3 dose, the BrO 3 - concentration was found to be lower than 10 g L -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. © 2016 Elsevier B.V. All rights reserved. ∗ Corresponding author. E-mail address: dfatta@ucy.ac.cy (D. Fatta-Kassinos). http://dx.doi.org/10.1016/j.jhazmat.2016.02.023 0304-3894/© 2016 Elsevier B.V. All rights reserved.