Revealing removal mechanisms of target personal care products in secondary wastewater treatment plants

Personal care products (PCPs) are classified as endocrine-disrupting chemicals (EDCs) with potential health impacts yet achieving their complete removal via conventional treatment methods is challenging. In this study, the removal efficiencies of these PCPs exhibited substantial variations (−5 % to 97 %) across different treatment processes employed at two local wastewater treatment plants (WWTPs). Therefore, gaining insights into the mechanisms involved in their removal during secondary treatment is crucial. This study focused on the removal efficiencies of five commonly detected PCPs, namely benzophenone-3, N,N-diethyl-m-toluidine, octocrylene, homosalate, and triclosan, from the local secondary WWTPs. Our findings highlighted the biological treatment processes as a key step in the removal of these PCPs. Using bioreactors to study the removal mechanisms of PCPs in the activated sludge process indicated that the primary removal mechanisms were biodegradation and adsorption, while volatilization and hydrolysis played a negligible role. The physicochemical properties of PCPs were found to underpin their removal mechanisms and influence their removal efficiencies. The results of this study revealed that aerobic biodegradation of the target PCPs in activated sludge followed a pseudo-first-order kinetic model. The kinetic studies with rate constants ranging from 0.10 h⁻¹ to 0.21 h⁻¹ and R² ranging from 0.942 to 0.980. Additionally, it was suggested that modifying different operational parameters and creating innovative materials could improve the removal effectiveness of PCPs. It underscores the urgent need to finalize disposal policies for high-risk PCPs to efficiently manage their ongoing release into the environment from the source. Copyright © 2024 Elsevier Ltd.