Occurrence, fate and removal of organic UV filters in wastewater treatment plants: Challenges and perspectives

Organic UV filters (OUVFs) are widely incorporated in sunscreens, cosmetics, and industrial materials, yet their persistence, bioaccumulation potential, and toxicity have raised growing environmental concerns. While most of the research studies has examined OUVFs contamination in marine and surface water ecosystems, the specific role of wastewater treatment plants (WWTPs) as point sources has not been comprehensively reviewed. This study addresses that gap by synthesizing data from 2014 to 2024 on OUVFs occurrence, fate, and removal in WWTPs worldwide. Reported influent concentrations of key compounds, such as benzophenone-3 (BP-3) and octocrylene (OC), range from a few ng/L to several µg/L. Removal efficiencies are highly variable, spanning from negative values (reflecting transformation, desorption, or sampling uncertainty) to nearly complete elimination. Conventional treatments, including activated sludge and biological nutrient removal, often show inconsistent and limited effectiveness for hydrophobic or recalcitrant OUVFs. In contrast, advanced processes such as reverse osmosis, ozonation, and advanced oxidation typically achieve removal rates above 80–90%, although higher operational and energy requirements compared to conventional treatments. Beyond quantifying concentrations and efficiencies, WWTPs are represented as quantifiable and critical emission points of OUVFs, rather than passive treatment systems. This study provides the first global synthesis of the last decade linking compound-specific behavior with treatment technology performance. The present review highlights major knowledge gaps, including the lack of systematic data on transformation products, insufficient understanding of intermediate degradation mechanisms, and striking regional disparities in regulatory frameworks.