Re-mineralization of desalinated water using a mixture of CO2 and H2SO4

Abstract

The corrosive tendency of desalinated water is commonly controlled by dosing acid to water flowing through a packed bed of limestone as to make it slightly supersaturated with respect to calcium carbonate. Acidification is achieved by dosage of either carbonic acid or sulfuric acid. Design models for re-mineralization in packed bed contactors are well established. Reduction of the carbon dioxide consumption required for re-mineralization, may be achieved by partial replacement with sulfuric acid, while maintaining the regulation stipulating a ratio of 1.3 to 2.0 between the equivalent alkalinity and calcium concentrations. The objective of this work was to extend the established kinetic model based on a single acid dissolution to the case of dissolution by a mixture of carbon dioxide and sulfuric acid. The derived model predicts the molar ratio of bicarbonate to calcium, in the product water, as a function of the molar ratio between the two acids. Experimental and predicted dissolution profiles are shown to be in very good agreement.