Production of high purity water using reverse osmosis
First Claim
1. A process for purifying water by removing dissolved materials therefrom, the process capable of producing purified water having a resistivity in the range of 4 to 10 megohm-cm or greater, comprising the steps of:
- (a) providing a water feed stream to be purified;
(b) adjusting the pH of the water feed stream to a basic water solution having a pH in the range of 7.5 to 10.5 in order for a first weakly ionized material comprised of carbon dioxide to become ionized in a basic solution;
(c) introducing said basic water solution to a high pressure side of a first reverse osmosis membrane;
(d) passing water through said first reverse osmosis membrane to provide a first retentate having ions therein from said first weakly ionized material concentrated therein and a first permeate depleted of ions from said first weakly ionized material;
(e) adjusting the pH of said first permeate to an acidic water solution in order for a second weakly ionized material comprised of ammonia to become ionized in an acidic solution;
(f) transferring said acidic water solution to the high pressure side of a second reverse osmosis membrane; and
(h) further purifying said acidic water solution by passing at least a portion thereof through said second reverse osmosis membrane to provide a second retentate containing ions of said second weakly ionized material ionized in said acidic solution and a second permeate, the second permeate having high resistivity.
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Accused Products
Abstract
A process for purifying water by removing dissolved materials therefrom, the process capable of producing purified water having a resistivity in the range of 2 to 10 megohm-cm. The process comprises providing a water feed stream to be purified and adjusting the pH of the water feed stream to a basic water solution to drive the equilibrium of a first weakly ionized material to become ionized in the basic solution. The basic water solution is introduced to a high pressure side of a first reverse osmosis membrane module and water is passed through the first reverse osmosis membrane to provide a first retentate having ions therein from the first weakly ionized material concentrated therein and a first permeate depleted in ions from the first weakly ionized material. The pH of the first permeate is adjusted to an acidic water solution to drive the equilibrium of a second weakly ionized material to become ionized in an acidic solution. The acidic water solution is transferred to the high pressure side of a second reverse osmosis membrane and the acidic water solution is purified by passing at least a portion thereof through the second reverse osmosis membrane to provide a second retentate containing ions of the second weakly ionized material ionized in the acidic solution and provide a second permeate depleted in the ions from the second weakly ionized material, the second permeate having a resistivity in the range of 1 to greater than 10 megohm-cm.
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Citations
18 Claims
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1. A process for purifying water by removing dissolved materials therefrom, the process capable of producing purified water having a resistivity in the range of 4 to 10 megohm-cm or greater, comprising the steps of:
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(a) providing a water feed stream to be purified; (b) adjusting the pH of the water feed stream to a basic water solution having a pH in the range of 7.5 to 10.5 in order for a first weakly ionized material comprised of carbon dioxide to become ionized in a basic solution; (c) introducing said basic water solution to a high pressure side of a first reverse osmosis membrane; (d) passing water through said first reverse osmosis membrane to provide a first retentate having ions therein from said first weakly ionized material concentrated therein and a first permeate depleted of ions from said first weakly ionized material; (e) adjusting the pH of said first permeate to an acidic water solution in order for a second weakly ionized material comprised of ammonia to become ionized in an acidic solution; (f) transferring said acidic water solution to the high pressure side of a second reverse osmosis membrane; and (h) further purifying said acidic water solution by passing at least a portion thereof through said second reverse osmosis membrane to provide a second retentate containing ions of said second weakly ionized material ionized in said acidic solution and a second permeate, the second permeate having high resistivity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A process for purifying water by removing dissolved materials therefrom, the process capable of producing purified water having a resistivity in the range of 4 to 10 megohm-cm or greater, comprising the steps of:
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(a) providing a water feed stream to be purified; (b) adjusting the pH of the water feed stream to a basic water solution in order for a first weakly ionized material comprised of carbon dioxide to become ionized in a basic solution; (c) introducing said basic water solution to a high pressure side of a first reverse osmosis membrane; (d) passing water through said first reverse osmosis membrane to provide a first retentate having ions therein from said first weakly ionized material concentrated therein and a first permeate depleted of ions from said first weakly ionized material; (e) adjusting the pH of said first permeate to an acidic water solution having a pH in the range of 5 to 7 in order for a second weakly ionized material comprised of ammonia to become ionized in an acidic solution; (f) transferring said acidic water solution to the high pressure side of a second reverse osmosis membrane; and (h) further purifying said acidic water solution by passing at least a portion thereof through said second reverse osmosis membrane to provide a second retentate containing ions of said second weakly ionized material ionized in said acidic solution and a second permeate, the second permeate having high resistivity. - View Dependent Claims (11)
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12. A process for purifying water by removing dissolved materials therefrom, the process capable of producing purified water having a resistivity in the range of 4 to 10 megohm-cm or greater, comprising the steps of:
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(a) providing a water feed stream to be purified; (b) adjusting the pH of the water feed stream to a basic water solution having a pH in the range of 8 to 9.5 in order for a first weakly ionized material comprised of carbon dioxide to become ionized in a basic solution; (c) introducing said basic water solution to a high pressure side of a first reverse osmosis membrane; (d) passing water through said first reverse osmosis membrane to provide a first retentate having ions therein from said first weakly ionized material concentrated therein and a first permeate depleted of ions from said first weakly ionized material; (e) adjusting the pH of said first permeate to an acidic water solution having a pH in the range of 5.0 to 7 in order for a second weakly ionized material comprised of ammonia to become ionized in an acidic solution; (f) transferring said acidic water solution to the high pressure side of a second reverse osmosis membrane; and (h) further purifying said acidic water solution by passing at least a portion thereof through said second reverse osmosis membrane to provide a second retentate containing ions of said second weakly ionized material ionized in said acidic solution and a second permeate, the second permeate having high resistivity.
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13. In a process for purifying a water feed stream by removing dissolved materials therefrom, including weakly ionized material using reverse osmosis membranes, the process capable of producing purified water having a resistivity in the range of 4 to 10 megohm-cm, the improvement wherein:
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(a) the water feed stream is provided as a basic water solution in order for a first weakly ionized material comprised of carbon dioxide to become ionized in a basic solution; (b) introducing said basic water solution to a high pressure side of a first reverse osmosis membrane; (c) passing water through said first reverse osmosis membrane to provide a first retentate having ions therein from said first weakly ionized material concentrated therein and a first permeate depleted of ions from said first weakly ionized material; (d) adjusting the pH of said first permeate to an acidic water solution in order for a second weakly ionized material comprised of ammonia to become ionized in an acidic solution; (e) transferring said acidic water solution to the high pressure side of a second reverse osmosis membrane; and (f) further purifying said acidic water solution by passing at least a portion thereof through said second reverse osmosis membrane to provide a second retentate containing ions of said second weakly ionized material ionized in said acidic solution and a second permeate, the second permeate having high resistivity. - View Dependent Claims (14, 15, 16, 17)
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18. In a process for purifing a water feed stream by removing dissolved materials therefrom, including weakly ionized material using reverse osmosis membranes, the process capable of producing purified water having a resistivity in the range of 4 to 10 megohm-cm, the improvement wherein:
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(a) the water feed stream is provided as a basic water solution in the range of 8 to 9.5 in order for a first weakly ionized material comprised of carbon dioxide to become ionized in a basic solution; (b) introducing said basic water solution to a high pressure side of a first reverse osmosis membrane; (c) passing water through said first reverse osmosis membrane to provide a first retentate having ions therein from said first weakly ionized material concentrated therein and a first permeate depleted of ions from said first weakly ionized material; (d) adjusting the pH of said first permeate to an acidic water solution having a pH in the range of 5 to 7 in order for a second weakly ionized material comprised of ammonia to become ionized in an acidic solution; (e) transferring said acidic water solution to the high pressure side of a second reverse osmosis membrane; and (f) further purifying said acidic water solution by passing at least a portion thereof through said second reverse osmosis membrane to provide a second retentate containing ions of said second weakly ionized material ionized in said acidic solution and a second permeate, the second permeate having high resistivity.
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Specification