Flocculation and Sedimentation Method for Fluoride Containing Wastewater Treatment

According to the national industrial wastewater discharge standards, the fluoride ion concentration should be less than 10mg/L; For drinking water, the fluoride ion concentration is required to be below 1mg/L. Below, Jiangsu Haipu Functional Materials, a manufacturer of fluorine-containing wastewater treatment, introduces the flocculation and sedimentation method for fluorine-containing wastewater treatment as follows:

The commonly used flocculant for the flocculation precipitation method of fluoride ion wastewater is aluminum salt. After aluminum salt is added to water, the coordination between Al3+and F -, as well as the intermediate products of aluminum salt hydrolysis and the final generated Al (OH) 3 (am), are utilized to remove fluoride ions from water through ligand exchange, physical adsorption, and sweeping of alum flowers. Compared with the calcium salt precipitation method, the aluminum salt flocculation precipitation method has the advantages of less dosage of chemicals, larger processing capacity, and meeting national emission standards after one treatment. Aluminum salts such as aluminum sulfate and polyaluminum have good coagulation removal effects on fluoride ions.

When using aluminum salts, the optimal pH for coagulation is 6.4-7.2, but the dosage is large. Depending on the situation, 150-1000g per m3 of water needs to be added, which will result in a certain amount of dissolved aluminum in the water that is harmful to human health. After using polyaluminum, the dosage can be reduced by about half, and the pH range of flocculation precipitation can be expanded to 5-8. The defluorination effect of polyaluminum is related to its own properties. Polyaluminum with an alkalinity of 75% is the best for defluorination, and the optimal dosage is when the molar ratio of F to Al in water is around 0.7.

The aluminum salt flocculation precipitation method also has obvious disadvantages, such as a small range of use, high fluoride content, excessive use of coagulants, high treatment costs, and a large amount of sludge generated; The removal efficiency of fluoride ions is greatly affected by operational factors such as stirring conditions and settling time, as well as anions such as SO42- and Cl - in the water. The effluent quality is not stable enough, which is related to the insufficient understanding of the coagulation mechanism for fluoride removal. Studying the coagulation mechanism for fluoride removal has significant practical significance.

For more information on fluorine-containing wastewater treatment, please continue to follow the official website of Jiangsu Haipu Functional Materials Co., Ltd., a fluorine-containing wastewater treatment manufacturer.