Background & Objectives: Sludge treatment and dewatering processes in wastewater treatment plants are one of the most important challenges for professionals and officials. The purpose of this study was to determine the effect of low wavelength and high energy ultrasonic waves to improve sludge dewatering properties and the optimum operating parameters of the ultrasonic method.

Methods: In this research variables include ultrasound density (0.375, 0.75, 1, 1.3 and 2.5w/m), time (1, 5, 10, 15 and 30 min), and amount of sonificated sludge (10, 15, 20, 50 and 100%). In this research effect of the variables on capillary suction time (CST) and sludge dewatering capacity were studied.

Results: The experiments determined that the optimum operating parameters as; sonification time=5 minutes, ultrasound density=1 W/ml, and amount of sonificated sludge equal to 15% at frequency of 20 kHz. Under these conditions CST was measured as 86 seconds.

Conclusion: Based on the results of this research, ultrasound waves could improve sludge dewatering process and can increase the treatment rate.