Sulfate removal from the sea by anion exchange process combined with k₂ so₄ precipitation

Sulfates can be removed from seawater by weak base anion exchanger which is regenerated with concentrated potassium chloride solution. The potassium sulfate was removed from the regeneration solution by adding solid KCl, which reduced the solubility of K₂ SO₄ causing its precipitation. 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 the regeneration solution to 55°C. After the regeneration solution exited the column, it was cooled to achieve maximum precipitation of the K₂ SO₄ . The weight of the K₂ SO₄ obtained was about the same as that of the KCl used for regeneration. The concentration of sulfate in seawater was reduced from 34 mM to less than 15 mM. To produce one ton of potassium sulfate about 250 tons of seawater is needed. The volume of the solution disposed of to the drain approached zero.