Removal Of Fluorine From Drinking Water By Enhanced Coagulation

This paper introduced the properties of fluorine, fluorine pollution source, hazards andcurrent pollution Situation in our country，and the removal technologies are reviewed at homeand abroad. To deepen the understanding of the mechanism of coagulation fluoride removal,.different coagulant effect of fluoride removal and its influencing factors were investigated.Firstly, aluminum sulfate as the coagulant，the effect of factors （coagulant dosage, pH value,turbidity, interfering ions and the initial concentration of fluoride） on the removal of fluoride inthe simulation of groundwater using aluminum sulfate was investigated by the method ofenhanced coagulation. The results show that the effect on removing fluorine using aluminumsulfate is better than ferric chloride, coagulant dosage and pH value are very two essential factorsfor the removal of fluoride using aluminum sulfate, especially when the pH value is about5.8;The effect of the removal of fluoride using aluminum sulfate is not evident as the turbidityincreases by the cause of kaolin: the effect of fluoride removal is worsen with the introduction ofHCO₃^-, while SO₄^2-and Cl^-disturbances are relatively small; Additionally, the preliminary studyon coagulation defluoridation mechanism using aluminum sulfate is performed.Secondly, the fluoride removal process by means of the polymer coagulants（polyaluminium chloride, polyaluminium ferric chloride and polymeric ferric sulfate） wasstudied comprehensively reference to aluminum sulfate, and the effect of factors,such ascoagulant dosage, pH value, turbidity, interfering ions and the initial concentration of fluoride,were investigated. The results prove that the effect of fluoride removal of the polymer coagulantsare more stable than traditional aluminum sulfate, but the former need a larger dosage to achievethe better effect of fluoride removal, especially when the initial concentration of the raw waterfluoride is higher. This will lead to additional economic burden in consideration of the actualoperating costs. So it requires combine with the characteristics of the coagulant to carry out thefluoride removal experiment, especially the research for coagulation mechanism of fluorideremoval.