Process for purifying water

Abstract

A process is provided for removing ions from water which is passed through an ion depletion compartment of an electrodeionization apparatus. The electrodeionization apparatus contains an ion depletion compartment containing mixed ion exchange resin beads and an ion concentration compartment which may contain ion exchange resin beads in a given separation stage having an anode and a cathode. The anion resin beads and cation resin beads utilized each comprise beams of substantially uniform size. A second liquid is passed through the ion concentration compartment to collect ions under the influence of DC potential which pass from the depletion compartments into the concentration compartments through ion permeable membranes. The electrodeionization apparatus can be operated continuously since resin regeneration is not required.

We claim: 
     
       1. . .The process for purifying water to remove organics and ionic species therein which comprises: passing said water through ion depletion compartments of an electrodeionization apparatus, said electrodeionization apparatus comprising;.!..Iadd.A process for removing organic and ionic species from a liquid which comprises the steps of:   a) providing an electrodeionization apparatus which comprises: i.Iaddend.) a cathode compartment at a first end of . .said.!. .Iadd.the .Iaddend.apparatus,   .Iadd.ii.Iaddend.) an anode compartment at . .an.!. .Iadd.a second .Iaddend.end of . .said.!. .Iadd.the .Iaddend.apparatus opposite . .said.!. .Iadd.the .Iaddend.first end,     . .a plurality of said ion depletion compartments alternating with ion concentration compartments positioned between said cathode compartment and said anode compartment,   an anion permeable membrane and a cation permeable membrane,   said anion permeable membrane and said cation permeable membrane being bonded to a spacer to effect sealing against water leakage between said ion depletion compartment and   each of said ion depletion compartments containing a mixture of anion resin beads of substantially uniform size and cation resin beads of substantially uniform size,.!. .Iadd.iii) at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising a mixture of anion exchange resin beads having a substantially uniform size and cation exchange resin beads having a substantially uniform size positioned between an anion exchange membrane and a cation exchange membrane, the ion depleting and ion concentrating compartments being positioned between the cathode compartment and the anode compartment, wherein the ion concentrating compartments are free of ion exchange resin,     b) passing a first liquid through the ion depleting compartments,   c) simultaneously .Iaddend.passing a second liquid for accepting ions from . .said water,.!. .Iadd.the first liquid .Iaddend.through . .said.!. .Iadd.the .Iaddend.concentration compartments . .while said water is passed through said ion depletion compartments.!.,   .Iadd.d.Iaddend.) applying an electrical voltage between an anode in . .said.!. .Iadd.the .Iaddend.anode compartment and a cathode in . .said.!. .Iadd.the .Iaddend.cathode compartment, and   .Iadd.e.Iaddend.) recovering . .purified water.!. .Iadd.the first liquid .Iaddend.from . .said depletion.!. .Iadd.the depleting .Iaddend.compartment.   
     
     
       2. The process of claim 1 wherein . .the ion exchange comprises a mixture of anion exchange resin beads and cation exchange resin beads and wherein.!. the volume ratio of anion exchange resin beads to cation exchange resin beads in said ion depiction compartments is between 4.0 and 0.5. 
     
     
       3. The process of claim 1 wherein said water is passed through at least two ion depletion compartments in series positioned between said anode and said cathode. 
     
     
       4. . .The process for purifying water to remove organics and ionic species therein which comprises: passing said water through ion depletion compartments of an electrodeionization apparatus comprising,   said electrodeionization apparatus comprising;   a cathode compartment at a first end of said apparatus,   an anode compartment at an end of said apparatus opposite said first end,   a plurality of said ion depletion compartments alternating with ion concentration compartments positioned between said cathode compartment and said anode compartment,.!. .Iadd.The process of claim 1 wherein .Iaddend.   each of . .said.!. .Iadd.the .Iaddend.ion . .depletion.!. .Iadd.depleting .Iaddend.compartments comprising a spacer and a plurality of subcompartments formed by a plurality of ribs extending along the length of each of . .said.!. .Iadd.the .Iaddend.ion . .depletion.!. .Iadd.depleting .Iaddend.compartments each of . .said.!. .Iadd.the .Iaddend.subcompartment . .containing an ion exchange solid composition, each of said subcompartments.!. having a width defined by the distance between . .said.!. .Iadd.the .Iaddend.ribs of between about 0.3 and 4 inches and a thickness between about 0.05 and 0.25 inches. ...!..Iadd., .Iaddend.   . .an anion permeable membrane and a cation permeable membrane,   said anion permeable membrane and said cation permeable membrane being bonded.!. .Iadd.the anion exchange membrane and the cation exchange membrane each being secured .Iaddend.to a spacer to . .effect sealing against water.!. .Iadd.create a seal against liquid .Iaddend.leakage between . .said.!. .Iadd.the .Iaddend.ion . .depletion.!. .Iadd.depleting .Iaddend.compartment . .and   each of said ion depletion compartments containing a mixture of anion resin beads of substantially uniform size and cation resin beads of substantially uniform size,   passing a second liquid for accepting ions from said water, through said concentration compartments while said water is passed through said ion depletion compartments,   applying an electrical voltage between an anode in said anode compartment and a cathode in said cathode compartment, and   recovering purified water from said depletion compartment.!..   
     
     
       5. The process of claim 4 wherein the width of said subcompartment is between about 0.5 and 1.5 inches. 
     
     
       6. The process of claim 4 wherein the thickness of said subcompartment is between about 0.06 and 0.125 inches. 
     
     
       7. The process of claims 4, 5, or 6 wherein . .the ion exchangers comprise a mixture of anion exchange resin beads and cation exchange resin beads and wherein.!. the volume ratio of anion exchange resin beads to cation exchange resin beads in said ion depletion compartments is between 4.0 and 0.5. 
     
     
       8. The process of claim 4 wherein said . .water.!. .Iadd.liquid .Iaddend.is passed through at least two ion depiction compartments in series positioned between said anode and said cathode. . .9. The process of claim 4 wherein said ion concentration compartments contain a mixture or anion exchange beads of substantially uniform size and cation exchange beads of substantially uniform size and wherein electrical voltage supplied to said anode and said cathode is reversed periodically to convert said anode to a second cathode and to convert said cathode to a second anode and to convert said ion depletion compartment to a second ion concentration compartment and to convert said ion concentration compartment to a second ion depiction compartment and recovering a water having low conductivity continuously from said ion depletion compartment and said second ion depiction compartment..!.. .10. The process of claim 8 wherein electrical voltage supplied to said anode and said cathode is reversed periodically to convert said anode to a second cathode and to convert said cathode to a second anode and to convert said ion depletion compartment to a second ion concentration compartment and to convert said ion concentration compartment in a second ion depletion compartment and recovering a water having low conductivity continuously from said ion depiction compartment 
     
     
        and said second ion depiction compartment..!.11. A dual compartment construction adapted to remove ions from a liquid which comprises: an ion depletion compartment and an ion concentration compartment and an odd number of at least three ion permeable membranes,   . .said.!. .Iadd.the .Iaddend.ion permeable membranes comprising anion permeable membranes alternately positioned with respect to cation permeable membranes,   each of . .said.!. .Iadd.the .Iaddend.ion depletion compartments and each of . .said.!. .Iadd.the .Iaddend.ion concentration compartments comprising a spacer and a plurality of ion depletion subcompartments and ion concentration subcompartments,   . .said.!. .Iadd.the .Iaddend.subcompartments being formed by a plurality of ribs extending along the length of each of . .said.!. .Iadd.the .Iaddend.ion depletion compartments and . .said.!. .Iadd.the .Iaddend.ion concentration compartments,   each of . .said.!. .Iadd.the .Iaddend.ion depletion subcompartments and . .said.!. .Iadd.the .Iaddend.ion concentration subcompartments containing a mixture of anion exchange resin beads . .of.!. .Iadd.having a .Iaddend.substantially uniform size and cation exchange resin beads of substantially uniform size,   each of . .said.!. .Iadd.the .Iaddend.ion depletion subcompartments and . .said.!. .Iadd.the .Iaddend.ion concentration subcompartments .Iadd.formed by a plurality of ribs extending along the length of each of the ion depletion compartments, each of the subcompartments .Iaddend.having . .a rib.!. .Iadd.a width .Iaddend.defined by the distance between . .said.!. .Iadd.the .Iaddend.ribs . .or.!. .Iadd.of .Iaddend.between about 0.3 and 4 inches and a thickness between about 0.05 and 0.25 inches wherein the thickness of . .said.!. .Iadd.the .Iaddend.subcompartments is defined by the distance between . .an.!. .Iadd.the .Iaddend.anion permeable membrane and . .a.!. .Iadd.the .Iaddend.cation permeable membrane,   each of . .said.!. .Iadd.the .Iaddend.ion permeable membranes being . .bonded.!. .Iadd.secured .Iaddend.to a spacer and . .said.!. .Iadd.the .Iaddend.ribs within . .a.!. .Iadd.the .Iaddend.spacer such that the anion permeable membrane and .Iadd.the .Iaddend.cation permeable membrane are positioned alternatively along the length of . .said.!. .Iadd.the .Iaddend.dual compartment,   . .means.!. .Iadd.a port .Iaddend.for passing a first liquid to be purified through each ion depletion compartment,   and . .means.!. .Iadd.a port .Iaddend.for passing a second liquid for accepting ions from . .said.!. .Iadd.the .Iaddend.first liquid through   
     
     
        each ion concentration compartment. 12. The construction of claim 11 wherein the width of said subcompartments is between about 0.5 and 1.5 
     
     
        inches. 13. The construction of claim 11 wherein the thickness of said 
     
     
        subcompartments is between about 0.06 and 0.125 inches. 14. The construction of any one of claims 11, 12, or 13 wherein . .the ion exchange composition comprises a mixture of anionic exchange resin beads and cationic exchange resin beads and wherein.!. the volume ratio of . .anionic.!. .Iadd.anion exchange .Iaddend.resin beads to . .cationic.!. .Iadd.cation .Iaddend.exchange resin beads . .and.!. .Iadd.in .Iaddend.said ion depletion compartments and in said ion concentration 
     
     
        compartments is between about 4.0 and 0.5. 15. The process of any one of claims 1,2,3,4,5,6, .Iadd.or .Iaddend.8, . .9 or 10.!. wherein the anion resin beads and the cation resin beads are of substantially equal average 
     
     
        size. 16. The construction of any one of claims 11,12 or 13 wherein the anion resin beads and the cation resin beads are of substantially equal 
     
     
        size. 17. The process of claim 7 wherein the anion resin beads and the 
     
     
        cation resin beads are of substantially equal average size. 18. The construction of claim 14 wherein the anion resin beads and the cation resin beads are of substantially equal size. .Iadd.19. An electrodeionization apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned, between an anion exchange membrane and a cation exchange membrane, wherein the ion exchange resin comprises a mixture of anion exchange resin beads having a substantially uniform size and cation exchange resin beads having a substantially uniform size, and the ion concentrating compartment being 
     
     
        free of ion exchange resin. .Iaddend..Iadd.20.  An electrodeionization apparatus as in claim 19 wherein the volume ratio of anion exchange resin beads to cation exchange resin beads is between about 4.0 and 0.5. .Iaddend..Iadd.21. A process for removing organic and ionic species from a liquid which comprises the steps of: a) providing an electrodeionization apparatus which comprises: i) a cathode compartment at a first end of the apparatus,   ii) an anode compartment at a second end of the apparatus opposite the first end,   iii) at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion concentrating compartment and the ion depleting compartment comprising a mixture of anion exchange resin beads having a substantially uniform size and cation exchange resin beads having a substantially uniform size positioned between an anion exchange membrane and a cation exchange membrane, the ion depleting and ion concentrating compartments being positioned between the cathode compartment and the anode compartment,     b) passing a first liquid through the ion depleting compartments,   c) simultaneously passing a second liquid for accepting ions from the first liquid through the concentration compartments,   d) applying an electrical voltage between an anode in the anode compartment and a cathode in the cathode compartment, and   e) recovering the first liquid from the depleting compartment. .Iaddend..Iadd.22. The process of claim 21 wherein the volume ratio of anion exchange resin beads cation exchange resin beads in said ion concentration compartments and said ion depletion compartments is between 4.0 and 0.5. .Iaddend..Iadd.23. The process of claim 21 wherein said water is passed through at least two ion depletion compartments in series positioned between said anode and said cathode. .Iaddend..Iadd.24. The process of claim 21 wherein each of the ion depleting compartments comprising a spacer and a plurality of subcompartments formed by a plurality of ribs extending along the length of each of the ion depleting compartments each of the subcompartment having a width defined by the distance between the ribs of between about 0.3 and 4 inches and a thickness 0.05 and 0.25 inches,   the anion exchange membrane and the cation exchange membrane each being secured to a spacer to create a seal against liquid leakage between the ion depleting compartments. .Iaddend..Iadd.25. The process of claim 24 wherein the width of said subcompartment is between about 0.5 and 1.5 inches. .Iaddend..Iadd.26. The process of claim 24 wherein the thickness of said subcompartment is between about 0.06 and 0.125 inches. .Iaddend..Iadd.27. The process of claims 24, 25 or 26 wherein the volume ratio of anion exchange resin beads to cation exchange resin beads in said ion concentration compartments and in said ion depletion compartments is between 4.0 and 0.5. .Iaddend..Iadd.28. The process of claim 24 wherein said water is passed through at least two ion depletion compartments in series positioned between said anode and said cathode. .Iaddend..Iadd.29. The process of claim 24 wherein electrical voltage supplied to said anode and said cathode is reversed periodically to convert said anode to a second cathode and to convert said cathode to a second anode and to convert said ion depletion compartment to a second ion concentration compartment and to convert said ion concentration compartment to a second ion depletion compartment and recovering a water having low conductivity continuously from said ion depletion compartment and said second ion depletion compartment. .Iaddend..Iadd.30. The process of claim 28 wherein electrical voltage supplied to said anode and said cathode is reversed periodically to convert said anode to a second cathode and to convert said cathode to a second anode and to convert said ion depletion compartment to a second ion concentration compartment and to convert said ion concentration compartment to a second ion depletion compartment and recovering a water having low conductivity continuously from said ion depletion compartment and said second ion depletion compartment. .Iaddend.