Effect of Microwave, Microwave Peroxide, Ultrasound, Protease Pretreatment on Secondary Sludge Solubilization and Anaerobic Digestion

Several innovative pretreatment technologies were used in this study, including microwave irradiation, the microwave/hydrogen peroxide process, ultrasounication, protease enzymatic treatment, and a combination of ultrasound with protease treatment. They were calibrated to a similar specific energy level so that comparison could be made base on energy cost. Anaerobic digestion of the pretreated sludge feeds was conducted at both mesophilic and thermophilic temperature. Two levels of organic loading were used to evaluate the impact of pretreatment on digestion. Reaction kinetics was investigated, and correlation to the sludge solubilization parameters was made.