The Effect of Ultrasonic Waves on Percentage of Solid Content in Dewatering of Excess Biological Sludge

Nowadays, sludge dewatering is one of the most difficult treatment processes in wastewater treatment plants. This subject is an important challenge in decrease of environmental pollutants. The purpose of this study was effect of ultrasonic waves on improve sludge dewatering, increasing solid content of sludge and determine the optimum operating parameters of the ultrasonic method.
An experimental study was carried out as a batch mode. In this research effect of some variables include ultrasound density (watts per ml), Time (minutes) and amount of sonificated sludge (percentage) on the solid content of sludge and sludge dewatering was measured. The solid content of sludge samples in prior to dewatering was 20.3 ± 0.9 percent. Sstatistical analyses were performed using SPSS version 18.
Findings: The experiments determined that the optimum operating parameters are sonification time of 5 minutes, ultrasound density of 1 W/ml, amount of sonificated sludge equal to 15% and a frequency of 20 kHz, which is the amount of solid content of sludge equal to 26.4 percent that is equal to 30 percent increase in dewatering of sludge.
Based on the results of this research, ultrasound waves and micro and nano-bubbles of cavitation could increase the solid content of sludge and improve sludge dewatering process and sludge treatment efficiency.