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Chlorine, Hydrogen Peroxide, Hydrogen-Ion Concentration, Oxidation-Reduction, Ultraviolet Rays, Waste Water, Endocrine Disruptors analysis, Endocrine Disruptors toxicity, Water Pollutants, Chemical analysis, and Water Pollutants, Chemical toxicity
Extensive use of endocrine disruptor compounds (EDCs) and their release through various pathways into the environment are emerging environmental concerns. In this context, H 2 O 2 and chlorine UV-based treatments were carried out to evaluate their efficiency in the removal of the bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) at 100 μg L -1 from ultrapure water and from wastewater treatment plants (WWTP). Photolysis was performed under different irradiation sources, i.e. UVC and UVA. The effect of H 2 O 2 (3 and 30 mg·L -1 ), free chlorine concentrations (1 and 2 mg·L -1 ) and pH (5, 7 and 9) were also investigated. Toxicity (Raphidocelis subcapitata) and estrogenic activity (yeast estrogen screen - YES assay) were assessed during the processes. Compound removal at optimal operating parameters reached 100% after 15 and 2 min for UVC/H 2 O 2 (pH 9 and 3 mg L -1 of H 2 O 2 ), and UVC/Cl (pH 9 and 2 mg L -1 of chlorine), respectively. Total organic carbon (TOC) removal achieved 37% and 45% for the H 2 O 2 and Cl-UV based process, respectively. The in vitro YES assay indicated that the formed by-products were non-estrogenic compounds, while the toxicity evaluation revealed high cell growth inhibition due to UVC/Cl byproducts. During the UV-based processes, 30 transformation products (TPs) were identified, in which three new chlorinated TPs from E2 and EE2 may be responsible for toxicity effects. EDC degradation by UV/Cl is faster than by UV/H 2 O 2 , although chlorinated toxic byproducts were also formed during the UV/Cl process.
(Copyright © 2020 Elsevier B.V. All rights reserved.)
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