Ozonation for sustainable sludge management: Advances in reduction, detoxification, stabilization, and resource recovery.

With increasing sludge production, efficient and sustainable treatment technologies are urgently needed. Ozonation has attracted growing attention because of its versatility in sludge reduction, detoxification, stabilization, and resource recovery. This review systematically summarizes the mechanisms and applications of ozonation in sludge treatment, including dewatering and minimization, refractory organic pollutant removal, heavy metal regulation, anaerobic digestion enhancement, composting improvement, and carbon and nutrient recovery. Ozone (O3) disrupts extracellular polymeric substances and microbial cells, releases bound water and intracellular organics, and thus improves dewaterability and promotes sludge reduction. It also degrades persistent organic pollutants and inactivates pathogens, while altering heavy metal speciation and enhancing their potential for subsequent separation and recovery. In addition, ozonation enhances sludge hydrolysis, supports methane production and compost maturation, and facilitates the recovery of soluble carbon sources and nutrients. Despite these advantages, practical application remains constrained by low ozone utilization, mass transfer limitation, incomplete mineralization, and high operating cost. Future efforts should focus on low-cost catalysts, process intensification, and integrated treatment systems. This review provides theoretical support and technical reference for the optimization and engineering application of the innovative ozone-based sludge treatment technology.