Study on ultrasonic treatment for municipal sludge

Ultrasonic technique has attracted wide attention due to its advantages of no secondary pollution, high decomposition speed and simple equipment in the treatment of municipal sludge. In this paper, study on ultrasound-chemical treatment for municipal sludge in investigated. Results indicate that ultrasonic waves can destroy sludge floc structure and cell walls, release intracellular organic matter, and accelerate the hydrolysis process; ultrasonic can improve the sedimentation and dewatering performance of sludge; ultrasonic wave can produce a sponge effect on sludge, which makes the water flow through the channel more easily from the wave surface, thereby agglomerating the sludge particles and increasing the particle size; ultrasound can promote coagulation; ultrasound can also improve the activity of excess sludge, and improve the efficiency of anaerobic digestion process and the final biogas production. Ultrasound-Cationic polyacrylamide (CPAM) treatment can undermine the repulsion between particles to a certain extent and destabilizes sludge flocs. In addition, the adsorption and bridging action of the flocculant CPAM further agglomerates the sludge particles, and the water in the sludge is squeezed out to be converted into free water, which further improves the dewatering performance of the sludge, thereby reducing the moisture content of the filter cake.