Removal of Endocrine Disruptors in Waste Waters by Means of Bioreactors

Abstract

The presence of Endocrine Disrupting Chemicals (EDCs) represents an area of concern in the environmental field. An EDC is defined as “an exogenous substance that causes adverse health effects in an intact organism, or its progeny, in consequence to the induced changes in endocrine functions” (EU Commission, 1996). A large number of chemical compounds have been recognized as EDCs. Among these, natural and synthetic steroid hormones, phytoestrogens, alkylphenols, phthalates, pesticides, surfactants and polychlorinated biphenyls (Soto et al., 1995, Jobling et al., 1995; Routledge & Sumpter, 1997). EDCs are not defined on the basis of their chemical nature, but by their biological effects. They exhibit agonistic or antagonistic properties depending on the kind of interaction with the receptors. As estrogenic receptors have similar structure between different animals, including humans, EDCs can affect the endocrine functions of many living species. The main mechanisms through which they interfere with the endocrine system are: i) the simulation of the activities of physiological hormones, thereby participating in the same reactions and causing the same effects; ii) the inactivation, with competitive action, of hormone receptors and, consequently, the neutralisation of their activity; iii) the interference with the synthesis, transport, metabolism and secretion of natural hormones, altering their physiological concentrations and therefore their corresponding endocrine functions. EDCs enter the environment from a variety of sources, such as effluent discharge pipes, agricultural runoff, landfills, atmospheric deposition and aerosols (Campbell et al., 2006). In particular aquatic ecosystems have been studied for the effect of wastewater treatment plant (WWTP) effluents, which are continuously discharged to the receiving water bodies (Jobling et al., 1998; Routledge et al., 1998; Tilton et al., 2002). Due to their incomplete removal during the waste treatment process, synthetic and natural estrogens are considered as the major responsible for the estrogenic activity associated with WWTP effluents (Gutendorf & Westendorf, 2001). So natural steroid hormones and the synthetic ethynylestradiol, alkylphenols, bisphenol A and phthalates are EDCs identified in sewage effluents (Desbrow