Electodeionization apparatus and method

DETAILED DESCRIPTION The present invention provides a method and apparatus capable of continuously producing water of up to about 10 meg-ohm cm quality or higher over long periods of time while avoiding serious reduction of ion exchange resin performance and avoiding the build-up of particulates and scale within the electrodeionization apparatus.
The apparatus includes a plurality of electrodeionization compartments whose thickness, width and configuration are controlled and which contain ion exchange materials such as beads, fibers or the like.
The electrodeionization ion depleting compartments wherein liquid is depleted of ions are formed from a spacer having a hollow central portion divided by ribs or the like to define subcompartments.
The ion exchange resin beads within the subcompartments are retained in the subcompartments by bonding or physically restraining a cationic permeable membrane to one surface of the depleting compartments and to the ribs and bonding or physically restraining an anionic permeable membrane to the opposing surface of the depleting compartment to the ribs, thereby to define the subcompartments.
The concentration compartments into which ions migrate from the depleting compartments are free of ion exchange beads.
The electrodeionization apparatus can comprise a single stage or a plurality of stages in series wherein the process voltage can be controlled independently in each stage, if desired.