Mohammad Ali Zazouli - Department of Environmental Health Engineering, School of Health, Health Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran
Zabihollah Yousefi - Department of Environmental Health Engineering, School of Health, Mazandaran University of Medical Sciences, Sari, Iran
Esmaeil Babanezhad - Department of Environmental Health Engineering, School of Health, Mazandaran University of Medical Sciences, Sari, Iran
Reza Ali Mohammadpour - Department of Biostatistics, School of Health, Mazandaran University of Medical Sciences, Sari, Iran
Alireza Ala - Corresponding author: Department of Environmental Health Engineering, School of Health, Health Sciences Research Center, Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran

Background: Leachate, containing challenging-to-degrade organic substances and persistent toxins, poses significant environmental concerns. Advanced oxidation processes (AOPs) have emerged as a promising solution for effective leachate treatment. This research provides a comprehensive review of the impact of various AOPs in leachate treatment. Methods: This systematic review was conducted, encompassing commonly used AOPs such as ozone, peroxone, O۳/catalyst, Fenton, photo-Fenton, UV/TiO۲, photolytic persulfate, O۳/UV, and O۳/H۲O۲/ UV. Extensive searches were performed using reputable databases, including EBSCO, PubMed, Web of Science, and Google Scholar. Specific keywords and inclusion/exclusion criteria were applied. Data regarding leachate treatment parameters were meticulously summarized and analyzed using descriptive statistical methods. Results: The efficiency of AOPs in removing leachate organic matter varied, with chemical oxygen demand (COD) removal ranging from ۴۱% to ۸۳% in treatment systems. The order of effectiveness was found to be: O۳/UV/H۲O۲ > photo-Fenton > UV/TiO۲ > Fenton > persulfate (PS) > O۳/UV > O۳/H۲O۲ > O۳/catalyst > ozonation (O۳). The highest COD removal efficiency of ۸۳.۷۵% was achieved using the O۳/UV/H۲O۲ AOP approach. The removal efficiency of color also varied, ranging from ۳۲% to ۱۰۰%, depending on the leachate’s characteristics, concentration, and specific treatment process utilized. Conclusion: AOPs, particularly the hybrid approach using O۳/UV/H۲O۲, significantly enhance waste leachate treatment by effectively degrading persistent organic compounds through the generation of hydroxyl radicals. Further research is required to optimize AOPs and improve their efficiency in waste leachate treatment.

Advanced oxidation processes, Chemical oxygen demand, Hydroxyl radicals, Leachate treatment, Organic compounds