Towards a greener heterogeneous Fenton process for removing emerging contaminants from urban wastewater: a recent short review

Emerging contaminants in urban wastewater, including pharmaceuticals, poly- and perfluoroalkyl substances (PFAS), personal care products, surfactants, and disinfection byproducts, represent an increasing environmental and public health concern because conventional urban wastewater treatment plants (uWWTPs) are unable to remove them efficiently. Among advanced oxidation processes the heterogeneous Fenton process has emerged as a promising alternative due to its ability to operate in some cases at near-neutral pH, minimize ferric sludge generation, enable catalyst recovery and reuse, and achieve efficient degradation of a wide range of emerging contaminants. This short review analyzes recent literature published between 2020 and 2026 to evaluate the current state of heterogeneous Fenton technology for urban wastewater treatment and to identify the main challenges preventing its transition into a truly green technology. The review discusses the occurrence, environmental impacts, and treatment requirements of major groups of emerging contaminants and examines key factors influencing heterogeneous Fenton performance, including contaminant adsorption, effects of scavengers (Cl − and Br − ), catalyst design, catalyst dosage, catalyst size, toxicity of oxidation/degradation byproducts post treatment, scalability of the heterogeneous Fenton process, operational issues related to neutral pH, etc. Based on this analysis, future research priorities are proposed, emphasizing the development of durable catalysts, optimization under real urban wastewater conditions, identify and characterize oxidation/degradation byproducts in the effluent, conduct comprehensive toxicity assessments, evaluate long-term environmental and biological risks under realistic and large-scale treatment conditions, incorporation of life cycle assessment and techno-economic analyses (research gaps), and scale up validation. Addressing these challenges will accelerate the green transition and large-scale implementation of heterogeneous Fenton process as an efficient process for removing emerging contaminants from urban wastewater.