Optimization of Energy Consumption of the Ultrasonic Pretreatment on Sludge Disintegration

Abstract

Anaerobic digestion is a widely used method to treat sludge, while its application was limited by its ineffective hydrolysis rate. Ultrasonic pretreatment could enhance the hydrolysis rate of sludge, while the development of ultrasonic had been restricted by the high energy consumption, it was necessary to optimize the energy consumption. Disintegration degree was analysed by the particle size, SCOD increase, soluble proteins and carbohydrates of the sludge before the after the ultrasonic pretreatment, the relationship between the specific energy input and the disintegration degree was discussed. The results showed that after ultrasonic disintegration, the concentration of SCOD, soluble protein and carbohydrate increased with the increase of ultrasonic time and ultrasonic power. High power ultrasonic could effectively disintegrate sludge in a short disintegration time, while low power ultrasonic needed a long time to disintegrate sludge. And under the same specific energy consumption conditions, the combination of lower power density and longer ultrasonic time could obtain better disintegration degree than the combination of higher power density and shorter time. It was confirmed that the energy utilization efficiency of the lower power density and the longer time combination was higher.