Effect of ultrasonic specific energy on waste activated sludge solubilization and enzyme activity

Abstract

The effect of ultrasonic specific energy on waste activated sludge (WAS) solubilization and enzyme activity was investigated in this study. Experimental results showed that the increase of ultrasonic specific energy in the range of 0 - 90000 kJ/kg dried sludge (DS) benefited WAS particle size reduction and the solubilization of organic matter in WAS. The changes of ultrasonic specific energy also gave impact on the activities of hydrolytic enzymes (protease, α-glucosidase, acid and alkaline phosphatase) which were related to the hydrolysis of protein and carbohydrate in WAS. Further investigation revealed that the activities of four hydrolytic enzymes reached the highest at the specific energy of 30000 kJ/kg DS with the disintegration degree of 38.2%. Also, the releases of soluble ammonia and phosphorus was studied during the ultrasonic treatment of WAS.   Key words: Waste activated sludge (WAS), ultrasonic, solubilization, disintegration degree, enzyme activity.