Comprehensive and sludge-free treatment of raw landfill leachate wastewaters using electro-peroxone

Advanced oxidation processes (AOPs) offer a promising strategy for leachate contaminant removal. In this work, electro-peroxone is evaluated first using humic acid and then applied to raw leachates from American and Indian landfills. Its performance is compared with electrolysis and ozonation using a reticulated vitreous carbon (RVC) cathode, while assessing the effects of current, electrode area, aeration rate, and pH on H₂O₂ generation. Quantification of H₂O₂ and •OH shows that electro-peroxone produces the highest •OH levels, identifying it as the most effective pollution-abatement pathway among the tested processes. It is demonstrated for the first time that the RVC electrode electrochemically generates hydroxyl radicals during electrolysis in an ozone- and catalyst-independent manner, while also producing hydroxyl radicals during electro-peroxone, as confirmed by EPR analysis. Additionally, electro-peroxone provides a unified treatment approach that simultaneously removes organics, color, microorganisms, TSS, and turbidity. In the case of both the leachates, a total organic carbon (TOC) degradation of about 70-93 %, a turbidity removal of around 80-97 %, and about 85-99.5 % TSS removal in 480 min, 99.4-99.7 % color removal in 240 min, and around 96-99.93 % disinfection in 180 min was attained. The electro-peroxone system also demonstrated a significant reduction in toxicity after treatment. The particle distribution analysis before and after treatment clearly indicated the reduction in particle size and substantiated the reduction in TSS and turbidity, and increase in soluble TOC. Finally, mechanisms for contaminant abatement and the novel phenomenon of particulate organic matter mineralization are proposed, demonstrating electro-peroxone as a sustainable, chemical-free, zero-sludge treatment option for complex landfill leachates.