Evaluation approaches of sludge ultrasonic pretreatment efficiency: a review

Abstract

Ultrasonic irradiation (US) is a feasible and promising mechanical disruption technique for sludge disintegration, biodegradability acceleration, and anaerobic digestion enhancement. It is clear that many processing factors significantly affect cavitation and consequently the efficiency of sludge pretreatment. Therefore, assessment, comparison, and selection of optimal ultrasonic conditions for actual application of sludge pretreatment are sorely necessary. The objective of this work is to present an extensive review of evaluation approaches of sludge ultrasonic pretreatment efficiency based on physical, chemical, and biological properties of sludge.