ABSTRACT
The disposal of wastewater sludge is one of the important issues associated with wastewater treatment plants (WWTPs). Anaerobic digestion is considered an essential part of modern WWTPs because of its ability to transform organic matter into biogas, thereby reducing the amount of sludge produced meanwhile destroying the pathogens present in the sludge. To accelerate rate-limiting hydrolysis and to enhance biogas production, various thermal-based pretreatment methods have been studied on a lab-scale and full-scale worldwide. As a result of pretreatment, the soluble intracellular material is released into the liquid phase thereby converting the refractory organic material into biodegradable species. The chapter incorporates a review of various thermal-based pretreatment methods including conventional thermal pretreatment, temperature-phased anaerobic digestion (TPAD), thermal hydrolysis, microwave pretreatment, and their conditions to optimize the anaerobic digestion of waste sludge with a focus on maximizing biogas production.
