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.
Highlights
Incineration, ocean discharge, land application and composting are the common sludge treatments used over the years but no longer reliable due to the economic difficulties and their negative impacts on environment
Physical properties used for evaluation of sludge ultrasonic pretreatment efficiency usually include: particle size reduction, sludge mass reduction, dewaterability, settle-ability, turbidity of sludge, and microscopic examination
Ultrasonic pretreatment is very effective in reducing the particle size of sludge, which is analyzed by different techniques
Summary
Incineration, ocean discharge, land application and composting are the common sludge treatments used over the years but no longer reliable due to the economic difficulties and their negative impacts on environment. Hydrolysis is known as a ratelimiting step, in which the intracellular biopolymers solubilize and convert to the lower molecular weight compounds of sludge. This low rate of microbial conversion requires the pretreatment of sludge, which ruptures the cell wall and facilitates the release of intracellular matter into the aqueous phase to accelerate biodegradability and to enhance the AD. There are some very popular techniques used in sludge pretreatment such as biological, thermal hydrolysis, mechanical, and chemical methods. Biological technique provides a moderate performance increase over mesophilic digestion with moderate energy input. Mechanical treatment methods (ultrasonic pretreatment, lysis-centrifuge, liquid shear, grinding...) provide a moderate performance improvement with moderate electrical input. Chemical treatment methods (oxidation, alkali, acidic pretreatment...) are applied in sludge pre-treatment [1]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
