(1) Separate ultrasonic treatment of sludge can improve sludge dewatering. When the ultrasonic frequency is 20 Hz and the power is 60 W, the optimum action time is 20 s.
(2) Ultrasonic and CGG are combined to condition the sludge, and the dewatering property of the sludge is improved to some extent. When the dosage of CGG was 900 mg/L, the sludge dewatering was better, and the CST decreased from 470 s to 76 s of the original sludge; the centrifugal moisture content of the sludge decreased from 88.3% of the original sludge to 75.3%.
(3) Ultrasonic and composite flocculant (CGG+PAM) were combined to condition the sludge, and the dewatering property of the sludge was significantly improved.
When the dosages of CGG and PAM were 300 and 120 mg/L, respectively, the CST was 18 s, and the sludge moisture content reached 58.8%, which improved the sludge dewatering property and saved the flocculant usage.