Applying ultrasound plus electrokinetics to enhance sludge dewatering

Abstract

Most sludges are dewatered using mechanical dewatering systems that can bring the weight percentage of the sludge solids up to a maximum of about 40 TS%. This study examined a new way to enhance pressure-filter dewatering by adding ultrasound and electrokinetics. The ultrasound adds a “stripping action” to free up bound water, and the electrokinetics adds a “pumping action” to push the freed-up water out of the sludge. This new enhanced dewatering process specifically targets bio and sewage sludges. The development work reported here, however, makes use of a sludge surrogate to determine (1) how to best optimize the enhanced dewatering process, and (2) just how much more water can be economically removed. The results demonstrated a substantial dewatering improvement to 55 TS%. A follow-up paper will demonstrate how this optimized ultrasound- and electrokinetics-enhanced dewatering process performs with bio and sewage sludges.