Removal of phosphorus from aqueous solution by natural calcite
方解石对水中磷的去除效果研究

The characteristics of phosphorus removal by natural calcite (grain size between 60 and 100 meshes) were studied in the laboratory with batch and column experiments. The results showed that the initial pH affected the removal rate of phosphorus by calcite significantly. The removal rate of phosphorus at the concentration of 800 mg/L was highest at initial pH 4.9, and the removal rate was 31%.The further experiments showed that the removal rate increased with phosphorus concentration, and the maximum removal rate was 49% at phosphate concentration of 1 600 mg/L. The analysis of the Ca2+ activity in solution and the XRD diagram showed that the phosphorus removal mechanism was the precipitation of Ca2+ and HPO2-4 under acidic conditions. The dynamic column experiments showed that the removal efficiency of phosphorus was not well at flow rate of 66.85 mL/min and phosphate concentration of 100 mg/L when the calcite was filled 25.4 cm in a column with a diameter of 10 cm. The removal rate arrived 64% in 5 min. The removal efficiency increased by 53% after regeneration of calcite by 3% HCl, and the removal rate kept above 90% in 10 min.