Applying ultrasound plus electrokinetics to enhance sludge dewatering
Arup Ratan Dey, Andrei Nekrasevits, R. Scott Semken, Aki Mikkola, Tuomas Sihvonen
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.