Sulfate removal from brackish water using an anion exchanger with recycled regeneration

Abstract: The removal of excess sulfate from brackish water was carried out using a weak anion exchanger that was regenerated with a potassium chloride solution. The potassium sulfate was removed from the regeneration solution by adding solid KCl, which reduces the solubility of K₂SO₄. Dilution of the regenerated solution was substantially reduced by using three displacement solutions with different KCl concentrations. Precipitation of potassium sulfate in the column during regeneration was prevented by heating it to 50–60°C. After the regeneration solution exited the column, it was cooled to achieve maximal precipitation of the K₂SO₄. The weight of the K₂SO₄ obtained was about the same as that of the KCl used for regeneration. The volume of the solution disposed to drain approached zero.