Abstract: An electrically driven membrane process apparatus is provided comprising a first spacer having a perimeter having a surface with an inner peripheral edge defining an opening, and a recess formed on the inner peripheral edge, and an ion exchange membrane having an outer edge fitted within the recess. The spacer can further comprise a plurality of bosses and an ion exchange membrane having a corresponding plurality of apertures for receiving the bosses. The spacer can include a plastic mesh consisting essentially of polypropylene or polyethylene, and a perimeter surrounding the plastic mesh, the perimeter comprising material selected from the group consisting of thermoplastic vulcanizates and thermoplastic elastomeric olefins. The spacer can have an upstanding seal member depending therefrom, received by groove within a corresponding frame member. A second spacer is also provided having a continuous flange depending from its surface and surrounding a throughbore, for pinching a portion of the first spacer.

Abstract: An electrically driven membrane process apparatus is provided comprising a first spacer having a perimeter having a surface with an inner peripheral edge defining an opening, and a recess formed on the inner peripheral edge, and an ion exchange membrane having an outer edge fitted within the recess. The spacer can further comprise a plurality of bosses and an ion exchange membrane having a corresponding plurality of apertures for receiving the bosses. The spacer can include a plastic mesh consisting essentially of polypropylene or polyethylene, and a perimeter surrounding the plastic mesh, the perimeter comprising material selected from the group consisting of thermoplastic vulcanizates and thermoplastic elastomeric olefins. The spacer can have an upstanding seal member depending therefrom, received by groove within a corresponding frame member. A second spacer is also provided having a continuous flange depending from its surface and surrounding a throughbore, for pinching a portion of the first spacer.

Abstract: The invention provides a method and apparatus for electrodeionizing water, whereby the water to be purified is passed through diluting compartments in an electrodeionization unit having an anode compartment at one end of the unit and a cathode compartment at the other end of the unit, and a plurality of diluting compartments alternating with concentrating compartments defined by anion and cation exchange membranes. Each of the diluting compartments contains ion exchange material. Importantly, the ion exchange material comprises at least one mixed bed phase of anion exchange material and cation exchange material and at least one single phase, adjacent to the mixed bed phase, of anion exchange material or cation exchange material, or anion exchange and cation exchange material.

Abstract: A method and apparatus is provided for inhibiting scaling in an electrodeionization system and, more particularly, for increasing tolerance to hardness in the feed water to an electrodeionization unit by inhibiting precipitation of scale-forming metallic cations contained in the feed water and thereby increasing efficiencies of the electrodeionization system. Water to be purified is passed through an electrodeionization unit in which the flow in the diluting compartment is countercurrent to the flow in the concentrating compartment. This is to impede the migration of scale-forming metallic cations from the diluting compartment, through the cation exchange membrane, into the concentrating compartment and towards the concentrating compartment side of the anion exchange membrane, thereby preventing scale formation on the anion exchange membrane.

Abstract: A method and apparatus for inhibiting scaling in an electrodeionization system or in a combined reverse osmosis/electrodeionization system for water treatment and, more particularly, for increasing tolerance to hardness in the feed water to an electrodeionization unit to inhibit precipitation of metal cations contained in the feed water and for increasing efficiency of the electrodeionization system. Water to be purified is passed through a electrodeionization unit in which a concentrate stream recycling through concentrating compartments and anode and cathode compartments contains effective amounts of an antiscalant to inhibit precipitation of scale. One or more preliminary reverse osmosis units in series with the electrodeionization unit preferably receives a portion of the antiscalants in the concentrate stream. The antiscalant in the water fed to the reverse osmosis unit can be supplemented and adjusted.