Quantificação de hormônios estrógenos em esgoto sanitário por HPLC-UV e avaliação da degradação por processos oxidativos avançados

Abstract

The increasingly constant presence of endocrine disrupting compounds (EDs) in the environment poses a serious risk to aquatic species and public health. Within this class of contaminants stand out the natural estrogen hormones estrone (E1), 17[β]-estradiol (E2) and estriol (E3), and synthetic 17[α]-ethinylestradiol (EE2), which can interfere with the functioning of the endocrine system of living beings. Sanitary sewage is one of the primary sources of these compounds in the aquatic environment, since the conventional treatment used by sewage treatment plants - STPs is designed to remove organic matter and nutrients, not being able to completely remove these micropollutants, making it urgent the need for more efficient treatments. In this scenario, advanced oxidative processes (AOPs) are shown to be interesting alternatives, as they can promote the total or partial degradation of these micropollutants. Thus, this study aimed to evaluate the presence and quantify the estrogen hormones E1, E2, E3 and EE2 present in the effluent treated by the STP in the city of Marmeleiro/PR, as well as evaluating different AOPs, especially photolysis (UV), photolysis with hydrogen peroxide (UV/H2O2), heterogeneous photocatalysis (UV/TiO2) and photo-ozonization (UV/O3) in the degradation of these estrogens. For this purpose, samples were collected from the effluent treated by conventional STP processes, which were characterized in physicochemical and microbiological terms before and after each AOPs. Hormones were determined using high performance liquid chromatography (HPLC) with UV detection. In the photochemical reactions, a discontinuous photoreactor was used, with a UV-C lamp (λ= 254 nm) and a reaction time equal to 60 minutes. The evaluation of the degradation of estrogen hormones by the different AOPs was carried out at an initial concentration of 8 mg L-1 of E1, E2, EE2 and E3. To verify the possible formation of toxic by-products during the reactions, the toxicity of the samples was evaluated from bioassays with Artemia salina L. and Eisenia fétida. The results indicated that all AOPs provided a better quality in the physicochemical and microbiological parameters. The presence of E1, E3 and EE2 was identified in the effluent treated by the STP in a concentration higher than that normally reported in the literature for this type of effluent. The data on the kinetics of hormone degradation fitted the pseudo-first order kinetic model, indicating the following order of efficiency of AOPs in the degradation of UV/O3>UV/TiO2>UV/H2O2>UV, in relation to the degradation of each hormone the kinetic constants were kE1>kEE2>kE2>kE3. In the toxicity evaluation, it was observed that the effluent treated by the STP proved to be toxic to the evaluated bioindicators (A. salina and E. fétida), however, the AOPs reduced this toxicity, indicating that there was no formation of toxic by-products when compared with the initial sample. These results suggest that AOPs, mainly photo-ozonization (UV/O3), can increase the quality of liquid waste from municipal STPs, which can be used as a tertiary treatment, improving their physicochemical, microbiology and removing micropollutants such as the estrogen hormones studied.