Review on endocrine disrupting-emerging compounds in urban wastewater: occurrence and removal by photocatalysis and ultrasonic irradiation for wastewater reuse

Abstract

Because of the vast use of organic chemicals in modern society, almost any wastewater stream from industrial processes or households contains such compounds and disposal without proper treatment will therefore result in exposure to humans and the environment. Some of them may exhibit endocrine disrupting effects (EDCs) and they widely exist in wastewater. The current effluent standards for Urban Wastewater Treatment Plants (UWWTPs) still include the conventional parameters of BOD, COD, pH, suspended solids, nitrogen, phosphorus, total number of E. coli etc. No limits for dangerous substances such as heavy metals or xenobiotic organic compounds exist in many countries. In the framework of the Water Frame Directive (WFD), environmental quality standards including 33 priority pollutants and some other xenobiotics have been proposed by the EU. As a consequence, member states have to establish monitoring programs for a number of priority and emerging pollutants. The integrated use of conventional biological treatment with advanced oxidation processes (AOPs) such as ozone oxidation, photocatalysis, Fenton and Photo-Fenton oxidation have been applied in order to increase the biodegradability and also the detoxification of the effluent streams. The use of AOPs seems to be favorable for reuse applications that require high quality of treated water, like for example groundwater recharge and indirect potable reuse. However, total dissolved solids (TDS) which can be increased if AOPs are applied have to be removed before reuse. This paper aims at providing an updated review on EDCs and their removal by photocatalysis (PC) and ultrasound oxidation (US) from aqueous spiked solutions and wastewater. The recently established reuse limits in Italy are evaluated according to AOPs requirements discussed in this paper.