Simple process for hardening desalinated water with Mg²⁺ ions

A simple easily controlled technique for adding Mg²⁺ ions to desalinated water is described. The Israeli Health Authority recommendation of adding of 20-30 mg/L of Mg²⁺ can be readily met by dissolution of magnesia pellets in a packed bed column. Experimental data are presented showing the effects of the specific flow velocity and CO₂ acidification of the inlet desalinated water on the Mg²⁺ concentration in the product stream leaving the column. Acidification of the inlet feed water is shown to enhance considerably the dissolution process. A kinetic expression is presented enabling full design of a dissolution packed column with nonacidified water.