Method and apparatus for treatment of feedwaters by membrane separation under acidic conditions

• US 7,320,756 B2
• Filed: 05/06/2002
• Issued: 01/22/2008
• Est. Priority Date: 05/05/2001
• Status: Expired due to Fees

• Current Assignee: Debasish Mukhopadhyay
• Original Assignee: Debasish Mukhopadhyay
• Inventors: Mukhopadhyay, Debasish
• Primary Examiner(s): FORTUNA, ANA M
• Application Number:
  US10/140,445
• Publication Number:
  US 20020166823A1
• Time in Patent Office: 2,087 Days
• Field of Search: 210650-653, 210638-639, 210/661, 210/900, 210/663, 210/660, 210/641, 210/748, 210/759, 210/760
• US Class Current: 210/652
• CPC Class Codes: B01D 2311/04 Specific process operations in the feed stream; Feed pretreatment
• CPC Class Codes: B01D 2311/18 pH control
• CPC Class Codes: B01D 2311/2649 Filtration
• CPC Class Codes: B01D 61/026 comprising multiple reverse osmosis steps
• CPC Class Codes: B01D 61/04 Feed pretreatment
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: Y10S 210/90 Ultra pure water, e.g. conductivity water

Abstract

A process for treatment of water via membrane separation equipment. A feedwater is maintained or adjusted to a pH of 4.3 or lower, and fed to a membrane separation system. In this manner, species such as TOC become more ionized, and (a) their rejection by the membrane separation process is significantly increased, and (b) their solubility in the reject stream from the membrane process is significantly increased. Passage TOC through the membrane is significantly reduced. A recovery ratio of eighty percent (80%) or higher is achievable with most feedwaters, while simultaneously achieving a substantial reduction in cleaning frequency of the membrane separation equipment. The method is particularly useful for the preparation of high purity water.

Claims

1. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce

(i) a high solute containing reject stream, and

(ii) a low solute containing product stream;

(d) wherein feedwater stream comprises a total organic carbon (TOC) constituent, and wherein said total organic carbon (TOC) constituent is effectively removed from said product stream; and

(e) wherein said total organic carbon (TOC) constituent comprises one or more nonionizable species, and wherein said one or more non-ionizable species are selected from the group consisting of (a) isopropyl alcohol, and (b) acetone.

2. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream;

(d) wherein feedwater stream comprises a total organic carbon (TOC) constituent, and wherein said total organic carbon (TOC) constituent is effectively removed from said product stream;

(e) wherein said total organic carbon (TOC) constituent in said product stream is approximately 10 percent or less of the concentration of such total organic carbon (ICC) constituent in said feedwater stream; and

(f) wherein said total organic carbon (TOC) constituent comprises one or more nonionizable species, and wherein said one or more nonionizable species are selected from the group consisting of (a) isopropyl alcohol, and (b) acetone.

3. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations;

(b) pretreating said feedwaifer stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream; and

(d) wherein said feedwater stream comprises ammonium ions, and wherein said product stream contains approximately eight (8) percent or less of the ammonium ion concentration present in said feedwater stream.

4. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations and at least one total organic carbon (TOC) constituent, said total organic carbon (TOC) constituent comprising isopropyl alcohol or acetone;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream;

(d) said process further comprising (i) adding either ferrous or ferric ions to said feedwater stream before feed to said reverse osmosis membrane separation equipment, as reactants to facilitate removal of total organic carbon (TOC) constituents, and (ii) adding hydrogen peroxide to said feedwater stream at any point before feed to said reverse osmosis membrane separation equipment.

5. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations and at least one total organic carbon (TOC) constituent, said total organic carbon (TOC) constituent comprising isopropyl alcohol or acetone;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream; and

(d) wherein said feedwater stream comprises a total organic carbon (TOC) constituent, and said process further comprises ozonation of said feedwater stream with an ozone containing gas, and wherein said total organic carbon (TOC) constituent is effectively eliminated from said product stream.

6. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations and at least one total organic carbon (TOC) constituent, said total organic carbon (TOC) constituent comprising isopropyl alcohol or acetone;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without(i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream; and

(d) wherein said feedwater stream comprises a total organic carbon (TOC) constituent, and wherein said process further comprises ozonation of said product water stream with an ozone containing gas, and wherein said total organic carbon (TOC)constituent is effectively eliminated from said product stream.

7. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide andlor solutes therein, said solutes comprising cations and at least one total organic carbon (TOC) constituent, said total organic carbon (TOC) constituent comprising isopropyl alcohol or acetone;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream;

(d) said process further comprising an oxidant removal pretreatment step and one or more additional pretreatment processes, to assure at least some free mineral acidity, and wherein said pretreatment steps are selected from the group consisting of (i) media filtration, (ii) cartridge filtration, (iii) ultrafiltration, (iv) nanofiltration, (v) degasification, and (vi) oxygen removal; and

(e) wherein said pretreatment process of oxidant removal comprises the addition of sodium meta-bisulfite to said feedwater.

8. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream;

(d) wherein said membrane separator comprises a loose reverse osmosis membrane;

(e) wherein feedwater stream comprises a total organic carbon (TOC) constituent, and wherein said total organic carbon (TOC) constituent is effectively removed from said product stream; and

(f) wherein said total organic carbon (TOC) constituent comprises one or more nonionizable species, and wherein said one or more nonionizable species are selected from the group consisting of (a) isopropyl alcohol, and (b) acetone.

9. A process for treatment of a feedwater stream in reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment comprising at least one unit having a reverse osmosis membrane separator, to produce a low solute containing product stream and a high solute containing reject stream, said process comprising:

(a) providing a feedwater stream containing carbon dioxide and/or solutes therein, said solutes comprising cations;

(b) pretreating said feedwater stream by controlling the pH to about 4.3 or lower, to assure at least some free mineral acidity in the pretreated feedwater at the point of feed to said reverse osmosis membrane separation equipment, without (i) removal of substantially all cations present in said feedwater stream, or (ii) removal of carbon dioxide;

(c) passing the resultant pretreated feedwater through said reverse osmosis membrane separation equipment, said reverse osmosis membrane separation equipment substantially resisting passage of at least some dissolved species therethrough, to concentrate said pretreated feedwater to said preselected concentration factor, to produce (i) a high solute containing reject stream, and (ii) a low solute containing product stream;

(d) wherein said membrane separator comprises a loose reverse osmosis membrane;

(e) wherein feedwater stream comprises a total organic carbon (TOC) constituent, and wherein said total organic carbon (TOC) constituent is effectively removed from said product stream;

(f) wherein said total organic carbon (TOC) constituent in said product stream is approximately 10 percent or less of the concentration of such total organic carbon (TOC) constituent in said feedwater stream; and

(g) wherein said total organic carbon (TOC) constituent comprises one or more nonionizable species, and wherein said one or more nonionizable species are selected from the group consisting of (a) isopropyl alcohol, and (b) acetone.