Redução de estrona de esgoto doméstico em wetland construído de fluxo vertical com fundo saturado seguido de adsorção como etapa de polimento

Abstract

Steroid hormones are constantly excreted by humans and reach surface waters through the discharge of domestic effluents. Although found in low concentrations in waters, can cause tissues, organs and cells damage of humans, aquatic organisms and wildlife. Among these, estrone (E1) has a high potential for endocrine disruption and is found in greater concentration in the environment due to its high persistence. Traditional wastewater treatment methods are unable to completely remove these micropollutants. Thus, due to the growing concern with water quality and public health, constructed wetlands (CWs) are being increasingly used for the decentralized wastewater treatment due to their economic and operational advantages over conventional treatment. But, when the sewage contains persistent organic pollutants, it is important to perform a final polishing of this effluent, such as the application of the adsorption with the use of powdered activated carbon (PAC). Both CWs and adsorption are technologies that present simplicity, low operating and maintenance costs and high efficiency rates for removing emerging pollutants, considerably reducing the availability of these species in the environment. Thus, the main objective of this work was the evaluation of the performance of the treatment vertical flow constructed wetland with saturated layer at the bottom followed by the adsorption operation as a polishing stage in the reduction of E1 from domestic wastewater. Quali-quantitative analyzes of raw and treated sewage samples in the CW and chemical and physical characterizations of the adsorbent were carried out. Through the experimental design CCD 2 3 , the effects of the variation of pH, temperature and adsorbent dosage on the TOC adsorption capacity was examined. The optimal condition for E1 reduction was determined from the TOC quantitation analysis. E1 reduction was analyzed using the UHPLC-MS technique. The results showed that the vertical flow constructed wetland with saturated layer at the bottom achieved removal efficiencies of 98.7% COD, 98.5% TSS and 80.39% TN, and that this final effluent of pilot system can be released into Brazilian´s natural water bodies and used for class B reuse activities. PAC showed amorphous, micro and mesoporous structure and a surface area of 617.35 m2 g -1 . Through the CCD 2 3 , it was possible to optimize the operational conditions. The optimal point was at pH= 12, temperature = 25ºC and PAC dosage = 1.1 g L-1 , achieving a removal efficiency of TN equivalent to 100% in the time of 180 minutes. The UHPLC-MS analysis showed that in the time of 30 minutes of adsorption there was a 100% reduction of E1 in the final effluent. Therefore, the combined process can be an excellent alternative for treatmet wastewater containing steroids.