Optimization, modeling, and characterization of water treatment sludge modified by ultrasound-assisted acid activation for enhancing of turbidity removal

摘要

The present study aimed to investigate the feasibility of applying recovered water treatment sludge (WTS) as a low-cost coagulant using the acidification/sonification method for turbidity removal. The WTS was completely characterized by BET, XRD FTIR, and FE-SEM observation. The effects of the main variables including WTS dosage (50-250 mg/l), sedimentation time (10-50 min), initial turbidity (10-350 NTU), and pH values (5-9) have been assessed and optimized using central composite design through response surface methodology. The developed empirical model significantly predicts and supports the results. The results showed that the turbidity removal was approximately completed at pH 9, initial turbidity of 350 NTU, and sedimentation time of 10 min by applying 250 mg/l WTS. The turbidity removal at the optimum condition was 85.83%. The results of this study indicated a high potential for recycled WTS as a low-cost coagulant, which can be used in the full-scale application.