Influence of ultrasonic disintegration on the dewaterability of waste activated sludge

Abstract Ultrasound can be used to disintegrate waste activated sludge (WAS), resulting in changes in sludge dewaterability. To observe and explain the change in sludge dewatering properties before and after ultrasonic disintegration, the specific resistance to filtration (SRF), capillary suction time (CST), content of biopolymers (proteins + polysaccharides), and free water in the sludge before and after disintegration were examined. Despite the degradation of extracellular polymeric substances (EPS), the sludge dewatering properties worsened after disintegration. This result is attributed to two changes in the sludge, one being the effect of the water retained by the biopolymers and the other being the adsorption effect of the fine sludge particles for free water. © 2006 American Institute of Chemical Engineers Environ Prog, 2006