Study on the treatment of fluorine-containing wastewater by precipitation-adsorption process

Fluorine-containing wastewater from the Yuncheng Sewage Treatment Plant in Heze City, Shan-dong Province was treated by coagulation and precipitation with poly aluminum sulfate, and CaO chemical precipitation-activated carbon adsorption, with a view to reducing fluoride ions concentration in the wastewater to below the discharge standard. The results showed that the optimum conditions for the coagulation-sedimentation test of poly aluminum sulfate were as follows: the dosage of poly aluminum sulfate 0.3 g/dm3, initial pH value 4.0, the removal rate of fluoride ion in the fluorine-containing wastewater reached 98.46%, and the concentration of fluoride ion was 0.462 mg/ dm3, which reached the discharge standard (1.5 mg/ dm3); The optimum conditions for the CaO chemical precipitation, and lanthanum loaded activated carbon adsorption method were as follows: the amount of CaO 20 g/ dm3, initial pH of the chemical precipitation test 8.0, the dosage of lanthanum loaded activated carbon 10 g/ dm3, and the initial pH of the adsorption test 6.0. At this time, the removal rate of fluoride ions in the fluorine-containing wastewater reached 95.81%, and the concentration of fluoride ions was 1.26 mg/ dm3, which also met the discharge standard.