Advanced Oxidation Processes for the Abatement of Emerging Contaminants in Wastewater: A Critical Review of Mechanisms, Applications, and Future Trajectories

The widespread release of synthetic organic compounds, also known as emerging contaminants (ECs), into aquatic environments presents a serious risk to public health and the environment, undermining the effectiveness of traditional wastewater treatment systems. The function of Advanced Oxidation Processes (AOPs) as a key technology for the breakdown of these stubborn micropollutants is critically examined in this thorough review. With an emphasis on the in-situ production of highly reactive oxygen species (ROS), such as hydroxyl and sulfate radicals, which promote non-selective oxidative degradation, we offer a thorough explanation of the physicochemical concepts underlying AOPs. Pharmaceuticals, endocrine disruptors, and per- and polyfluoroalkyl substances (PFASs) are among the major EC classes against which the manuscript methodically assesses the effectiveness, scalability, and limitations of the main AOP classifications, including chemical, photochemical, electrochemical, and catalytic activation methods. A thorough examination of the main technological challenges is provided, including energy intensity, catalyst deactivation, toxic transformation product formation, and economic viability. The review also outlines promising research areas to improve sustainability, such as the use of computational intelligence for process optimization, the rational design of next-generation nanocatalysts, and the synergistic integration with biological treatment and renewable energy. We conclude that a multidisciplinary approach combining materials science, environmental engineering, and green chemistry is essential to moving AOPs from bench-scale innovation to reliable, practical implementation within a circular water economy framework, even though translational challenges still exist.