Microwave enhanced advanced oxidation treatment of municipal wastewater sludge

Three sludge types (primary sludge, secondary sludge, and anaerobic digested sludge) and centrate produced from a local municipal wastewater treatment plant were treated by the microwave enhanced advanced oxidation process. All sludge types exhibited a certain degree of solids solubilization and phosphorus release, as well as altered physical properties after the treatment. The extent of treatment was influenced by the inherent characteristics of sludge itself, besides the treatment process conditions, such as temperature and hydrogen peroxide dosage. The microwave enhanced advanced oxidation process was very effective for the treatment of all types of sludge for purpose of solids solubilisation, and nutrients release for resource recovery. Very high soluble chemical oxygen demand concentrations (62%) and total suspended solids reduction (75%) were obtained in the treated secondary sludge conducted in the pilot-scale continuous-flow system. The microwave enhanced advanced oxidation treatment system shall be used for treating both primary and secondary sludge, and therefore, the system shall be installed in the treatment train after an aerobic biological treatment system, and before an anaerobic digestion system to gain the maximum process efficiency.