Study On The Removal Effects Of Calcium Aluminate On The Sulfate And Fluorine Content Of Underground Water

Groundwater exploitation now is one of the main production and domestic water supply methods around most rural areas and towns in China. Affected by some factors like earth petrochemistry and hydrogeology, the concentration of [SO₄^2-] and [F^-] in groundwater are too high in some part of easy sedimentary area. In the mean while, with the rapid development of mining and coal industry, the concentration of [SO₄^2-] and [F^-] in groundwater are over standard caused by industrial wastewater discharge have been occurred. In view of different water use objects has different demand of water quality parameter limits, and for the sake of achieve a good water society cycle, remove excess [SO₄^2-] and [F^-] in groundwater is essential.This paper used calcium aluminates as material, according to dynamic experiment, the influence of different factors such as dosage, pH, temperature and time on [SO₄^2-] and [F^-] remove in groundwater have been studied, and the corresponding reaction mechanism have been analyzed. The results shows that,(1) Under the level of [SO₄^2-]=300¹000mg/L, when calcium aluminates dosage is 7.5g/L, pH=9, 25℃and stirring time is 30mins, the residual [SO₄^2-] can be stabled at below 250mg/L.(2) Under the level of [F^-]=300¹000mg/L, when calcium aluminates dosage is 5g/L, pH=11, 30℃and adsorption time is more than 2h, the remove rate of [F^-] is over 50%.(3) The particle size of the precipitates which synthesized when calcium aluminates react with SO₄^2- or F^-, and the character of filtering ratio resistance shows, using mud cake filtration can fulfill the final solid-liquid separation in treatment technology. (4) The powder of calcium aluminates is a type of purifying agent which is cheap and efficient, can be used to remove excess [SO₄^2-] and [F^-] in domestic and production wastewater.