Degradation of endocrine disrupting chemicals by ozone/AOPs

The presence of endocrine-disrupting compounds (EDCs) in the aqueous environment is of increasing concern due to their adverse impact on aquatic life, and potential risk to human health. Among the EDCs of concern are steroidal estrogenic hormones such as estrone (E1), 17 beta-estradiol (E2), estriol (E3), and 17 alpha-ethinylestradiol (EE2), which have a high environmental prevalence and strong estrogenic activity. In addition, the extensive use of alkylphenol ethoxylates (APnEOs), bisphenol A (BPA) and phthalate compounds have resulted in an environmental presence at significant concentrations, although they appear to have a lower estrogenic activity than the steroidal hormones. As water and wastewaters are some of the primary routes of exposure to EDCs, it is important to determine at what levels EDCs are found in these media and how these levels may be reduced. Hence, it is necessary to understand the fate of EDCs in conventional water and wastewater treatment plants, as well as the efficacy of more specialized treatment methods, such as adsorption and oxidation. This paper is a summary of the latest information on the degradation of prominent EDCs by ozone and ozone-based advanced oxidation processes (AOPs). From this review, it is clear that ozone and AOPs are effective in degrading these EDCs, with the possible exception of phthalates, which are relatively stable to ozone oxidation. Knowledge of the formation of reaction products from the treatment by ozone and AOPs is relatively poor at present, and particularly for the nonsteroid compounds.