Occurrence and fate of steroid hormones in wastewater treatment plants
Various natural chemicals and certain contaminants from industries present an endocrine activity. These substances are likely to act on animal and human endocrine system (deterioration or reproductive functions deficiencies, malignant tumor occurrences, etc). Nowadays, many questions related to these compounds are not resolved and the persistent character of these compounds makes it a major problem for future generations. Furthermore, diverse studies determined that natural estrogens (e.g., estrone, 17β-estradiol and estriol) and synthetic estrogen (17α-ethinylestradiol) are the most estrogenic compounds in wastewater treatment plant effluents. Thus, these estrogens can reach surface water and contaminate it. Indeed, concentrations as low as 0.1 ng/L can induce estrogenic effects in exposed aquatic organisms. This review concentrated on this type of compounds in surface water and wastewater, and a number of treatment processes are discussed with regard to their potential on endocrine disrupting chemicals removal. In the primary treatment effluent, limited removal of estrogens has been observed, while secondary treatment involving activated sludge generally reduces all estrogens effluents concentrations. The advanced processes display a high potential for removing estrogens, although they may produce estrogenic and/or carcinogenic by-products. Enzymatic processes could be an innovative strategy for estrogens removal since they show a high potential to remove aromatic compounds from wastewater.