Multifunctional treatment of emerging estrogenic micropollutants: a review of biological, chemical, and physicochemical pathways

The widespread presence of micropollutants in aquatic systems has emerged as a serious concern for aquatic organisms, plants, and humans. Among them, endocrine-disrupting chemicals such as estrone, estradiol, estriol, and ethinylestradiol are predominantly introduced into water bodies via effluents from pharmaceutical, industrial, agricultural, and domestic sources, collectively contributing to total estrogenic activity in affected waters. Although numerous advanced water treatment strategies have been developed in the past, current methodologies often exhibit limited efficacy in complete removal at trace concentrations. In this review, we critically examined the current strategies focused on chemical reactivity, catalysis, redox mechanisms, and physical separations for the removal of estrogenic micropollutants. Recently, the research has been shifted toward hybrid and natural systems, like High-Rate Algal Ponds and Constructed Wetlands that operate via biological and physicochemical pathways. Molecularly Imprinted Polymers offer molecular-level recognition of estrogens, enabling selective sorption based on template-analyte interactions. On the other hand, oxidative degradation methods like Ozonation, Fenton processes, and Advanced Oxidation Processes provide high degradation efficiencies, but raise concerns due to incomplete mineralization and generation of toxic intermediates. The comprehensive study of these comparative methodologies to mitigate emerging estrogenic pollutants will be a step toward building sustainable, effective, and economic wastewater treatment plants to ensure water safety.