Research on Coagulation/Sedimentation Process for Fluoride Removal in Simulation Wastewater

Experiments were carried out with the simulated fluoride-containing wastewater to study the fluoride removal. The effects on the residual fluoride concentration were investigated using lime-sedimentation and coagulation/sedimentation. The results showed that the fluoride contents were among 30mg/L～50mg/L, with lime alone. The residual fluoride concentrations of 600mg/L, 900mg/L and 1200mg/L solution decreased to below 10mg/L, using Ca(OH)2+FeCl3+PAM. The fluoride concentrations of 300mg/L, 600mg/L, 900mg/L, 1200mg/L fluoride wastewater remained below 10mg/L by Ca(OH)2+PFS+PAM. Comparing two methods, the supernatant was relatively clear with Ca(OH)2+PFS+PAM, which had better settling performance. It suggested PFS and PAM has an important increase effect on the fluoride removal, and the optimum conditions: PFS was 0.1mL, fluoride-calcium ratio was 2:1.15.