EP0251691A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Effluent treatment
Assignee: Water Research Commission
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Filing: 1987-06-24
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Granted: —
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Expires: 2007-06-24
Abstract
Abstract A method of treating an organic material such as textile fibres with an alkali metal hydroxide solution including the steps of: (i) contacting the organic material with the hydroxide solution to produce an effluent comprising an alkali metal hydroxide solution which contains multivalent ions and soluble and insoluble organic and inorganic matter; (ii) reducing the pH of the effluent to a value in the range 7 to 9 by contacting with an acid gas; (iii) filtering the solution from step (ii) to remove suspended insoluble matter having a size greater than 0,1 microns. (iv) filtering the filtrate from step (iii) to remove multivalent ions and organic matter having a molecular mass greater than about 300 daltons; (v) providing an electrochemical cell in which an anode compartment is separated from a cathode compartment by a cation selective membrane; (vi) passing the filtrate from step (iv) into the anode compartment of the electrochemical cell; (vii) passing an electrical current through the cell causing alkali metal ions to pass through the cation selective membrane and alkali metal hydroxide to be produced in the cathode compartment and the acid gas to be produced in the anode compartment; (viii) returning the alkali metal hydroxide to step (i); and (ix) using the acid gas produced in the cathode compartment for reducing the pH of the effluent in step (ii).
Inventors
- 👤 Christopher Andrew Buckley
- 👤 Alison Elizabeth Simpson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 20:16
CPC Classifications
B; B01; B01D; B01D61/00; B01D61/02; B01D61/027; B01D36/00; C; C02; C02F; C02F1/00; C02F1/44; C02F1/441; C02F1/66; C02F9/00; C02F1/46; C02F1/469; C02F1/72; C02F1/76; C02F2103/00; C02F2103/26; C02F2103/28; C02F2103/30; C02F2103/32
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
174 words
A method of treating an alkali metal salt or hydroxide solution which contains multivalent ions, and soluble and insoluble organic and inorganic matter including the steps of: (i) if the solution has a pH greater than 9, bringing the pH of the solution to a pH in the range 7 to 9; (ii) filtering the solution from step (i) to remove suspended insoluble matter having a size greater than 0,1 microns; (iii) filtering the filtrate from step (ii) to remove multivalent ions and orgnic matter having a molecular mass greater than about 300 daltons; (iv) providing an electrochemical cell in which an anode compartment is separated from a cathode compartment by a cation selective membrane; (v) passing the filtrate from step (iii) into the anode compartment of the electrochemical cell; and (vi) passing an electrical direct current through the cell to cause alkali metal ions to pass through the cation selective membrane and alkali metal hydroxide to be produced in the cathode compartment and an acidic component to be produced in the anode compartment.
Claim 2
Independent Claim
174 words
A method of treating an alkali metal salt or hydroxide solution which contains multivalent ions, and soluble and insoluble organic and inorganic matter including the steps of: (i) if the solution has a pH greater than 9, bringing the pH of the solution to a pH in the range 7 to 9; (ii) filtering the solution from step (i) to remove suspended insoluble matter having a size greater than 0,1 microns; (iii) filtering the filtrate from step (ii) to remove multivalent ions and orgnic matter having a molecular mass greater than about 300 daltons; (iv) providing an electrochemical cell in which an anode compartment is separated from a cathode compartment by a cation selective membrane; (v) passing the filtrate from step (iii) into the anode compartment of the electrochemical cell; and (vi) passing an electrical direct current through the cell to cause alkali metal ions to pass through the cation selective membrane and alkali metal hydroxide to be produced in the cathode compartment and an acidic component to be produced in the anode compartment.
Claim 3
Dependent Claim
37 words
A method according to claim 1 wherein the solution has a pH of greater than 9 and it is treated with an acid gas to reduce its pH to a value in the range 7 to 9.
Claim 4
Dependent Claim
13 words
A method according to claim 2 wherein the acid gas is carbon dioxide.
Claim 5
Dependent Claim
12 words
A method according to claim 2 wherein the acid gas is chlorine.
Claim 6
Independent Claim
20 words
A method according to any one of the preceding claims wherein the filtration used in step (ii) is cross-flow microfiltration.
Claim 7
Independent Claim
20 words
A method according to any one of the preceding claims wherein the filtration method used in step (iii) is nanofiltration.
Claim 8
Independent Claim
22 words
A method according to any one of the preceding claims wherein the multivalent ions in the solution include magnesium and calcium ions.
Claim 9
Independent Claim
20 words
A method according to any one of the preceding claims wherein the solution is a solution of alkali metal hydroxide.
Claim 10
Independent Claim
220 words
A method of treating an organic material with an alkali metal hydroxide solution including the steps of: (i) contacting the organic material with the hydroxide solution to produce an effluent comprising an alkali metal hydroxide solution which contains multivalent ions and soluble and insoluble organic and inorganic matter; (ii) reducing the pH of the effluent to a value in the range 7 to 9 by contacting it with an acid gas; (iii) filtering the solution from step (ii) to remove suspended insoluble matter having a size greater than 0.1 microns. (iv) filtering the filtrate from step (iii) to remove multivalent ions and organic matter having a molecular mass greater than about 300 daltons; (v) providing an electrochemical cell in which an anode compartment is separated from a cathode compartment by a cation selective membrane; (vi) passing the filtrate from step (iv) into the anode compartment of the electrochemical cell; (vii) passing an electrical current through the cell causing alkali metal ions to pass through the cation selective membrane and alkali metal hydroxide to be produced in the cathode compartment and the acid gas to be produced in the anode compartment; (viii) returning the alkali metal hydroxide to step (i); and (ix) using the acid gas produced in the cathode compartment for reducing the pH of the effluent in step (ii).
Claim 11
Independent Claim
220 words
A method of treating an organic material with an alkali metal hydroxide solution including the steps of: (i) contacting the organic material with the hydroxide solution to produce an effluent comprising an alkali metal hydroxide solution which contains multivalent ions and soluble and insoluble organic and inorganic matter; (ii) reducing the pH of the effluent to a value in the range 7 to 9 by contacting it with an acid gas; (iii) filtering the solution from step (ii) to remove suspended insoluble matter having a size greater than 0.1 microns. (iv) filtering the filtrate from step (iii) to remove multivalent ions and organic matter having a molecular mass greater than about 300 daltons; (v) providing an electrochemical cell in which an anode compartment is separated from a cathode compartment by a cation selective membrane; (vi) passing the filtrate from step (iv) into the anode compartment of the electrochemical cell; (vii) passing an electrical current through the cell causing alkali metal ions to pass through the cation selective membrane and alkali metal hydroxide to be produced in the cathode compartment and the acid gas to be produced in the anode compartment; (viii) returning the alkali metal hydroxide to step (i); and (ix) using the acid gas produced in the cathode compartment for reducing the pH of the effluent in step (ii).
Claim 12
Dependent Claim
13 words
A method according to claim 9 wherein the acid gas is carbon dioxide.
Claim 13
Dependent Claim
12 words
A method according to claim 9 wherein the acid gas is chlorine.
Claim 14
Independent Claim
21 words
A method according to any one of claims 9 to 11 wherein the filtration used in step (iii) is cross-flow microfiltration.
Claim 15
Independent Claim
21 words
A method according to any one of claims 9 to 12 wherein the filtration method used in step (iv) is nanofiltration.
Claim 16
Independent Claim
23 words
A method according to any one of claims 9 to 13 wherein the multivalent ions in the effluent include magnesium and calcium ions.
Claim 17
Independent Claim
19 words
A method according to any one of claims 9 to 14 wherein the alkali metal hydroxide is sodium hydroxide.
References Cited (Backward Citations)
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