Patent ID: 7344629

Claim:
An apparatus to treat an influent solution comprising ions to obtain a selectable ion concentration in a resultant effluent solution, the apparatus comprising: (a) an electrochemical cell comprising: (i) a housing comprising first and second electrodes; (ii) a water-splitting ion exchange membrane between the first and second electrodes, the membrane comprising (i) a cation exchange surface facing the first electrode, and (ii) an anion exchange surface facing the second electrode; and (iii) an influent solution inlet and an effluent solution outlet with a solution channel therebetween, the solution channel allowing the influent solution to flow past both the anion and cation exchange surfaces of the water-splitting ion exchange membrane and thereby form the effluent solution; and (b) a variable voltage supply capable of maintaining the first and second electrodes at a plurality of selectable voltage levels during an ion exchange stage such that each selectable voltage level has a different magnitude and provides a different ion concentration range in the effluent solution.