Study On Disposing Of High-Fluoride Containing Groundwater

Fluorine is one of the necessary trace elements for human health. The appropriate concentration of fluorine in drinking water is 0.5-1.0mg/L, outside this range will have ill effects. High fluoride containing groundwater is the groundwater which fluoride concentration is higher than national sanitary standard for drinking water (1.0mg/L) and makes people have fluorosis.High fluoride containing groundwater is mainly caused by nature factors and artificial pollution. Except shanghai, high fluoride containing groundwater is all over our country, mostly distribute in northwest, northeast and north china areas, somewhere fluoride concentration is so many times of national sanitary standard for drinking water. Excessive intake of fluorine may not only cause "Dental Fluorosis", "Bone Fluorosis", but also can destroy protoplasm, physical metabolize turbulence. Fluoride also inhibited incretion, blight gonad, adrenal gland and pancreas, even caused cancer and brain damnification. In high fluoride containing groundwater areas, fluoride greatly threaten the health of the local people, which has been one of the main endemic in our country. This issue has caused wide public concern.Now, there have been so many research on fluoride removal from high-fluoride containing wastewater both at home and abroad, which have basically meet the standard for discharge of fluoride(10mg/L). But the study of high fluoride containing groundwater is less which fluoride concentration is lower than wastewater discharge standard and higher than national sanitary standard for drinking water. There is a lack of economical, effective and practicable method for fluoride removal from high fluoride containing groundwater.This paper study on fluoride removal from high fluoride containing groundwater in Jilin Province by calcium oxide sedimentation method and magnesium unite calcium oxide method, offering practicable ways for the treatment of high fluoride containing groundwater.In the research of removing fluoride by calcium oxide sedimentation method, by arranging a series condition experiment, analysis the influencing factors of fluoride removal, discuss the mechanism of fluoride removal. The experimental results showed that, for the fluoride containing groundwater, calcium oxide powder alone failed to effectively remove fluoride when its concentration is lower than 8.0mg/L. The mechanism is Ca²⁺+F=CaF₂↓. Excessive calcium oxide powder dosage might make a great deal of deposit and make the water strong alkaline, fail to meet the national sanitary standard for drinking water. The mechanism is very complex include.In the research on the use of magnesium unite calcium oxide removal fluoride, which get a better result. Use a series condition experiment to analyze the influencing factors of fluoride removal one by one, get the optimum reaction condition: dosing ratio of magnesium flocculants is 0.4%, calcium oxide powder is regulated pH9, at normal temperature, stir 5min. At the optimum reaction condition the fluorine removal rate reach 91%, the concentration of fluorine ion in the groundwater is lower than the national sanitary standard for drinking water. The mechanism of magnesium unite calcium oxide removal fluoride is very perplexing; mainly include adsorption, compound sedimentation and ion-exchange reactions, the absorption isotherm conform to Langmuir adsorption equation as C_e/Q_e=0.1746C_e+0.0394.The research shows that removing fluoride by calcium oxide sedimentation method can't have good result, but use magnesium unite calcium oxide method is effectively. This method, not only effective but also no secondary pollution, is a simple and practicable method.