Effects of sonication on activated sludge

Abstract Sonication with power levels of 7.5–75 W-min caused disruption of the sludge flocs which increased with the intensity of the power. This caused the filtration characteristics and the quality of the sludge supernatant to deteriorate. There was a clear relationship between the mean particle size and the sonic power, a relationship that could be used to derive values for the floc strength. Sonication also released soluble carbohydrate and protein from the sludge. The way in which this release occurred in the presence of a high-molecular-weight cationic polyelectrolyte suggests that there was a sequential release of different biopolymers from the sludge as the power was increased.