Evaluation of a Sludge Homogenization Sludge Pre-Conditioning Process for Increased Biogas Cogeneration Potential and Reduced Sludge Yields from Anaerobic Digestion

Recently several technologies and process innovations have been proposed to reduce or eliminate the waste activated sludge (WAS) fraction resulting from treatment, or to render it more amenable to anaerobic digestion, a common sludge stabilization step, in order to maximize biogas production and the corresponding potential for energy cogeneration. Under WERF's 05-CTS-3 Evaluation of Processes to Reduce Activated Sludge Solids Generation and Disposal, data collected from the full-scale demonstration of MicroSludge™, a WAS reduction technology, at the Des Moines Water Reclamation Facility was independently evaluated. Results indicate that sludge pre-treatment ahead of mesophilic anaerobic potential did improve biogas production rates and yields as well as volatile solids reduction under most of the tested conditions. Results also indicated lower odor generation potential for the MicroSludge™ pre-treated sludge before co-digestion of primary and WAS, and an ability to destroy filamentous organisms that could be precursors to foaming problems in anaerobic digesters. However this technology did not have a significant impact on pathogen reduction ahead of the anaerobic digestion process