Factors Analysis on Ultrasonic Sludge Reduction in Continuous Flow System

In stable continuous flow system (CFS), excess sludge with ultrasonic treatment was returned. The effect of ultrasonic density, ultrasonic time, ultrasonic pulse and recycled ratio of ultrasonic sludge on excess sludge reduction was studied, and effluent water quality and sludge settling ability were determined. Results showed that under ultrasonic density 0.4 W/mL, ultrasonic time 5 min, recycled ratio of ultrasonic sludge 1:24, excess sludge reduction ratio was above 90%, effluent water quality could achieve II-class criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002), SVI was about 100 mL/gMLSS, sludge settled properly. Ultrasonic pulse had hardly any effect on excess sludge reduction.