UV and simulated solar photodegradation of 17α-ethynylestradiol in secondary-treated wastewater by hydrogen peroxide or iron addition

Abstract

•EE2 degradation in wastewater under UVC or simulated solar light was studied.•The effect of several operating parameters on process efficiency was investigated.•Estrogenicity in wastewater matrices is not completely removed upon EE2 elimination.•The formation of transformation products (TPs) was followed by UPLC–MS/MS.•EE2 degradation pathways during UVC/H2O2 or solar/Fe2+ treatment were proposed.

The extensive use of estrogens and their release, through various pathways, into the environment, constitutes an emerging environmental problem that poses serious threats onto public health. In this work the efficiency of UVC/H2O2 and solar/Fe2+ treatment to degrade 17α-ethynylestradiol (EE2) in environmentally relevant concentrations of 100μg/L in secondary-treated wastewater matrices was investigated. Also, photolytic treatment was performed under different irradiation sources, namely UVC, UVA and simulated solar light. The effect of H2O2 (0–20mg/L) and Fe2+ (0–15mg/L) concentration was investigated and, at optimal operating parameters, EE2 removal was 100% after 15min of UVC/H2O2 treatment, while EE2 removal reached 86% after 60min of solar/Fe2+ treatment. In addition, the effect of water matrix and pH was studied. Total organic carbon (TOC) and yeast estrogen screening (YES) measurements showed the formation of stable intermediate products during EE2 treatment and an attempt to elucidate the reaction pathways and mechanisms through the identification of transformation products (TPs) by means of UPLC–MS/MS was made. Several TPs, including quinone methide and 1,2-quinone derivatives, were identified and competing pathways were suggested, in which hydroxylation, alkylation, dealkylation, demethylation and dehydroxylation, amongst others were described as major transformation mechanisms.