Potassium permanganate-based advanced oxidation processes for wastewater decontamination and sludge treatment: A review

[Display omitted] •KMnO4 oxidation can be activated by several strategies.•KMnO4 oxidizes sludge and contaminants via inducing RMnS and free radicals.•Pollutants removal and sludge dewatering can be improved by in-situ produced MnO2.•KMnO4-based AOPs can prominently enhance sludge dewatering and resources recovery.•KMnO4-based AOPs can prevent biogenic sewer corrosion and sludge-induced risks. The wastewater pollution with various contaminants exposure and increased sludge production from municipal wastewater treatment plants (WWTPs) are the two challenges confronted by human beings. Therefore, the pollution control and sludge treatment have gained growing attentions. Potassium permanganate (KMnO4), as a green and non-toxic oxidant, has been largely employed in wastewater and sludge treatments, including pollutants removal, decrement of hazardous gas footprint, and improvement of sludge dewatering and resource recovery ascribed to its strong oxidability and excellent properties, which provides solutions for wastewater decontamination, risk mitigation and sludge recycling. The recent studies of KMnO4-based advanced oxidation processes (AOPs) in terms of wastewater and sludge treatment are comprehensively outlined in this review. Particularly, methods of enhancing KMnO4 oxidation are summarized, and the application and relevant mechanisms of KMnO4-based AOPs in improving contaminants removal, sludge dewatering and resource recovery (i.e., short-chain fatty acids and methane) are illuminated and discussed. Finally, the knowledge gaps and new opportunities of KMnO4-based AOPs in wastewater and sludge fields are prospected. The review can promote an in-depth understanding of KMnO4-based processes and provide a theoretical framework for KMnO4 application in wastewater and sludge managements.