Ultrasonic pretreatment for Enhancing Sludge disintegration and Resource Utilization: A mini review

As a byproduct of sewage treatment plants, sludge presents dual characteristics of “resource” and “pollution”. While it enriches nutrients from wastewater, it also contains a portion of toxic substances. Moreover, when the organic matter content of sludge is low, it affects the efficiency of resource utilization and energy recovery (sludge digestion efficiency, energy consumption of incineration systems). Developing new physicochemical-biological combined pretreatment to enhance the dissolution of organic matter in sludge (sludge disintegration) and reduce the solid content of sludge is a crucial step to improve sludge dewaterability and digestibility. Ultrasonic, as a novel sludge pretreatment technology, gains the advantages of being environmentally sustainable, efficient, and easily operable. It can disrupt sludge flocs, alter microbial activity, release intracellular organic matter, and be used in combination with other pretreatment processes. This article summarizes the mechanism of ultrasonic pretreatment of sludge and its research progress in improving sludge dewaterability and digestibility, providing a new perspective for the application of ultrasound in sludge resource utilization