How to add activated alumina in fluorine removal

- Dec 22, 2020-

XR105 Activated alumina is used to remove fluorine in drinking water. When the arsenic content in the raw water exceeds 0.05 mg/L, the process parameters for fluorine removal should be determined through experiments. For the defluorination process using activated alumina as the filter material, the fluorine content of the raw water in the defluorination filter should be less than 10mg/L, and the suspended solids should not exceed 5mg/L.

    The particle size of activated alumina should not be larger than 2.5mm, generally 0.4~1.5mm. Activated alumina should have sufficient mechanical strength. Before the raw water contacts the filter material, the pH value should be lowered. The lowered value should be determined through technical and economic comparison, and it should generally be adjusted to between 6.0 and 7.0. Raw water can be added with acidic solutions such as sulfuric acid, hydrochloric acid, acetic acid, or carbon dioxide gas to lower the pH value. The dosage should be calculated based on the alkalinity and pH value of the raw water or determined by experiment. The filtration rate of the filter tank can be used in the following two ways: (1) When the pH value of the inlet water of the filter tank is greater than 7.0, the intermittent operation mode should be adopted, and the design filtration rate is 2~3m/h, and the continuous operation time is 4~6h , Intermittent 4~6x. (2) When the pH value of the feed water is less than 7.0, continuous operation can be used, and the filtration rate is 6-10m/h. The flow direction of the raw water through the filter material layer can be bottom-up or top-down. When using sulfuric acid solution to adjust the pH value, the top-down method should be adopted. When carbon dioxide is used to adjust the pH value, the bottom-up approach should be adopted. The fluorine content of the effluent at the end of the fluorine removal cycle of a single filter can be slightly higher than 1mg/L, and the end point fluorine content should be determined according to the mixing adjustment ability, but the fluorine content of the treated water after mixing should not exceed 1.0mg/L. The periodic adsorption capacity of the filter material is mainly selected according to factors such as the fluorine content of the raw water, the pH value, the filtration rate, the thickness of the filter layer, the end point fluorine content and the performance of the filter material. (1) When a sulfuric acid solution is used to adjust the pH to 6.0-6.5, it can generally be 4-5g(F)/kg(Al2O3). (2) When carbon dioxide is used to adjust the pH to 6.5 to 7.0, it can generally be 3 to 4 g(F)/kg (Al2O3).

The thickness of the filter material of a single filter should be adopted according to the following regulations: (1) When the fluorine content of the raw water is less than 4mg/L, the thickness of the filter material should be greater than 1.5m; (2) When the fluorine content of the raw water is 4-10mgL, the thickness of the filter material It should be greater than 1.8m. Note: When sulfuric acid is used to adjust the pH value, the scale is small, and the filtration rate is reduced, the thickness of the filter layer can be reduced to 0.8-1.2m.