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

Abstract

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 TM , 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 TM pretreated 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

High pressure homogenization and temperature phased anaerobic digestion for enhanced biogas conversion from municipal waste sludge

“…Under mesophilic digestion, HPH+TPAD systems achieved 18.8% improvement while HPH prior to single-stage digestion and TPAD system showed similar improvement in VS reduction with 12.7% and 12% increase over control. Mesophilic HPH system achieved 12.7% higher VS removal compare to the controls which is in agreement with a previous study conducted by Sandino et al (2010). The authors reported 13.0% improvements in VS removals over the control at for and HPH pretreated mesophilic digester fed with mixed sludge at 7 d SRT.…”

“…TWAS at higher concentrations could achieve significant reduction in electrical energy consumption as well as total input energy requirement. At full-scale applications, a TWAS with TS concentration of 6 to 10% was reported to be processed by a HPH system without major limitation (Sandino et al 2010). For example, a TS concentration of 7.5% could reduce the total input energy from 4.46 to 2.20 GJ/tonne TCOD fed (about 51% less).…”

“…Another mechanical pretreatment technique, called high pressure homogenization (HPH), has been reported as a less energy intensive process and can bring improvement in anaerobic digestion performance (CH2M HILL 2005). A recent study by Sandino et al (2010) with demonstration-scale HPH plant showed that HPH pretreatment was able to enhance the biogas production by 11 to 18% over conventional mesophilic mixed sludge digestion at SRTs between 7 to 20 days. Though combination of two or more different pretreatments is not something new, very few studies have been reported to combine pretreatments with TPAD system.…”