Removal of Steroid Hormones Mixture by Drinking Water Treatment Residuals: Evaluating Mechanisms and Potential for Wastewater Reuse

Abstract

The presence of anthropogenic contaminants, known as emerging pollutants (EPs), poses a major challenge for wastewater treatment. In line with the European Union’s vision for water recycling, efforts have focused on developing more sustainable advanced treatment technologies. To achieve this, circular economy principles can be applied by repurposing waste from other sectors. Consequently, drinking water treatment residuals (DWTR), by-products of drinking water treatment plants (DWTP), have emerged as promising, low-cost adsorbents for the removal of EPs in wastewater treatment. This study assessed the adsorption, in aqueous solution, of a mixture of three steroid hormones: estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2), while also providing proof-of-concept insights using real wastewater. The adsorption process was evaluated by analysing the underlying mechanisms involved, with a focus on dosage, kinetics, and isotherm adsorption studies. The results showed that DWTR reached a maximum adsorption capacity of approximately 4 mg EPs/g DWTR within 24 h, suggesting potential compatibility with WWTP hydraulic retention times. In real wastewater (0.5 µg/L of E1, E2, and EE2), removal efficiency exceeded 50% for all compounds, confirming its potential for reuse and its effectiveness in reducing estrogenicity in wastewater. These findings suggest that DWTR could serve as an effective adsorbent for EP removal in wastewater, contributing to the United Nations Sustainable Development Goals and to circular economy principles within the water sector.

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