Endocrine disruptors compounds (EDC) are mostly from anthropogenic source and are characterized by their ability to interfere with the human endocrine system, stimulating functional organism changes and inauspicious effects in their health when exposed to these chemicals. Currently, steroid hormones represent one of the EDC groups with the highest endocrine disruption potential, arising as a concern in terms of environmental effects and consequences to the health of living beings. This group includes natural hormones, for example 17β-estradiol (E2), and synthetic hormones like 17α-ethinylestradiol (EE2). These two specific hormones were included in the EU Watch List along with Water Directive, to promote more and better knowledge that will support the future policies and legislation. Those are mainly excreted through urine and feces, and consequently the wastewater treatment plants are considered the main source of discharge of these compounds. The exposure consequences to E2 and EE2 are described, namely, the feminization of male fish, impact in reproductive function and population decrease. In Human’s these consequences are reflected in the increase of breast, prostate, and ovarian cancer, as well as the decrease of sperm and reproductive system malformations. The conventional wastewater treatment plants weren’t designed to remove these compounds. Some studies showed that their removal from wastewaters is possible and achievable using advanced treatments, such as oxidation processes. Chlorination represents one of the most effective oxidation methods to eliminate E2 and EE2. However, in wastewaters due to the organic matter presence the trihalomethanes formation (extremely carcinogenic) is highly likely. As an alternative to chlorination the use of Peracetic Acid (PAA) was consider. This compound showed to be an efficient option in the wastewater disinfection processes, eliminating most of the harmful microorganisms, and with innocuous and nontoxic by-products, unquestionable advantages to other treatment options. Thus, the main goal of this study was to assess the applicability of PAA in the removal of these estrogenic compounds, E2 and EE2, from wastewaters, namely in a secondary effluent. To accomplish this study several assays were performed where different PAA concentrations (1mg/L, 5mg/L, 10mg/L and 15mg/L) and several contact times (10min, 15min and 20min) were tested. It was also performed a biological assay, complementary, to assess the toxicity potential of both compounds, and their by-products after the PAA application, using Zebra fish (Danio rerio) as a biological model. Biological markers (antioxidant enzymes – GST, CAT and LPO) and endocrine disrupting markers (vitellogenin) were also determined. The results showed that E2 was all removed with a PAA concentration of 15 mg/L and with 20 min of contact time. EE2 was also totally removed with PAA concentrations of 10 mg/L and 15 mg/L and with a contact time of 10 min and 15 min, respectively. The results also showed that the oxidative stress caused by the exposure to E2 and EE2 weren’t statistically representative, although, as expected, the vitellogenin levels had increased, confirming their estrogenic potential. It was also showed that EE2 had a higher estrogenic potential than E2. After PAA treatment, the estrogenic potential decreased substantially, reaching the obtained control assays levels and demonstrating the feasibility of the adopted wastewater treatment solution. This kind of treatment has also the operational advantage of being easily incorporated in the existing wastewater treatment plants with very low investment costs.
6d. Water and sanitation
