Patent ID: 8404094

Claim:
An electrodeionization apparatus comprising: a. an anode chamber 201 , including an anode therein; b. a cathode chamber 206 , including a cathode therein, wherein an electric field is formed as a result of a voltage applied between the anode and the cathode; c. an anion membrane 202 contiguous with the anode chamber 201 ; d. a dual layer depletion chamber comprising; i. an anion exchange material layer 203 contiguous with the anion membrane 202 , the anion exchange material layer including therein anion exchange materials; ii. a composite anion-cation exchange material layer 204 contiguous with the anion exchange material layer 203 , the composite anion-cation exchange material layer including therein one of a mixed ion exchange material, or a doped anion exchange material, or a doped cation exchange material; iii. wherein an interface between the anion exchange material layer 203 and the composite anion-cation exchange material layer 204 is substantially transverse to the applied electric field, and a fluid flow inlet and outlet are positioned so that a direction of fluid flow through the apparatus is parallel to the applied electric field; and e. a cation membrane 205 contiguous with the composite anion-cation exchange material layer 204 of the dual layer depletion chamber and contiguous with the cathode chamber 206 .