METHOD AND APPARATUS FOR DESALINATION

• US 20100089756A1
• Filed: 12/16/2009
• Published: 04/15/2010
• Est. Priority Date: 09/20/2006
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC (Xylem, Inc.)
• Original Assignee: Siemens Water Technologies Corp (Siemens AG)
• Inventors: Jha, Anil, Ganzi, Gary C., Wilkins, Frederick C.
• Granted Patent: US 8,182,693 B2
• Time in Patent Office: Days
• US Class Current: 204/638
• CPC Class Codes: B01D 2317/025 Permeate series
• CPC Class Codes: B01D 61/027 Nanofiltration
• CPC Class Codes: B01D 61/147 Microfiltration
• CPC Class Codes: B01D 61/422 Electrodialysis
• CPC Class Codes: B01D 61/48 having one or more compartments filled with ion-exchange material , e.g. electrodeionisation
• CPC Class Codes: B01D 61/58 Multistep processes
• CPC Class Codes: C02F 1/42 by ion-exchange ion-exchange in general B01J
• CPC Class Codes: C02F 1/442 by nanofiltration
• CPC Class Codes: C02F 1/444 by ultrafiltration or microfiltration
• CPC Class Codes: C02F 1/4693 electrodialysis
• CPC Class Codes: C02F 1/4695 electrodeionisation
• CPC Class Codes: C02F 2103/08 Seawater, e.g. for desalination
• CPC Class Codes: Y02A 20/124 Water desalination
• CPC Class Codes: Y02A 20/131 Reverse-osmosis
• CPC Class Codes: Y02W 10/33 using wind energy
• CPC Class Codes: Y02W 10/37 using solar energy

Abstract

A method and apparatus for purifying water are provided. A feed water such as seawater can be fed to a filter such as a microporous or nanofiltration membrane to produce a permeate that can, in turn, be fed to an electrodeionization system to produce fresh water.

Claims

1. A method of purifying water comprising:

providing a feed water comprising greater than about 1,000 ppm total dissolved solids to a nanofiltration device to produce a first filtrate reduced in total dissolved solids; and

feeding the first filtrate to an electrodeionization device to produce a second filtrate comprising less than about 1,000 ppm total dissolved solids and a boron content of less than about 0.5 ppm.

2. The method of claim 1 wherein the feed water is seawater, brackish water or oil field recovery water.

3. The method of claim 1 wherein greater than about 90% of any multivalent ions are removed by the nanofiltration device.

4. The method of claim 1 wherein the nanofiltration device is operated at an upstream pressure of less than about 600 psi.

6. The method of claim 1 that consumes energy an overall rate of less than about 7 kwh/kgal.

7. The method of claim 1 wherein the second filtrate comprises less than or equal to about 500 ppm total dissolved solids.

5. (canceled)

8. An apparatus for desalinating seawater comprising:

a nanofiltration device; and

an electrochemical device in fluid communication with the nanofiltration device, the electrochemical device having dilution cells with a thickness of less than about 10 mm.

9. The apparatus of claim 8 further comprising a pretreatment device positioned upstream of the nanofiltration device, the pretreatment device selected from the group consisting of a bed filter, a microfilter, a crossflow microfilter, a settling tank, and an aerator.

23. The apparatus of claim 8, wherein the electrochemical device comprises an electrodeionization apparatus.

10. (canceled)

11. (canceled)

12. A method of treating seawater to reduce total dissolved solids comprising:

treating the seawater in a water treatment apparatus while applying energy in an amount less than about 7 kwh/kgal of filtrate to the apparatus to produce a filtrate comprising less than about 1,000 ppm total dissolved solids.

13. The method of claim 12 wherein the water treatment apparatus comprises a nanofiltration device and an electrodeionization device.

14. The method of claim 13 wherein the filtrate comprises total dissolved solids in a range of from about 230 ppm to about 500 ppm.

15. A method of treating seawater comprising:

reducing a concentration of one or more non-monovalent species from the seawater in a first stage comprising at least one of a nanofiltration device and ultrafiltration device; and

reducing a concentration of one or more monovalent species from the seawater in a second stage to produce water having a TDS of less than about 1,000 ppm,

wherein the first and second stages are operated at a net energy consumption rate of less than about 7 kwh/kgal of product water.

16. The method of claim 15, wherein the first stage comprises a nanofiltration device.

17. The method of claim 16, wherein the second stage comprises an electrodeionization device.

18. The method of claim 17, further comprising mixing a concentrate stream from the electrodeionization device with the seawater upstream of the first stage.

19. A method of treating water having dissolved species therein comprising:

reducing a concentration of monovalent dissolved species from the water to produce a byproduct and a first partially treated water stream;

reducing a concentration of divalent dissolved species from the first partially treated water stream to produce a second partially treated water stream; and

reducing a concentration of dissolved species from the second partially treated water stream to less than about 1,000 ppm in an electrodeionization device.

20. The method of claim 19, wherein the act of reducing the concentration of monovalent dissolved species comprises utilizing an electrodialysis device.

21. The method of claim 20, wherein the act of reducing the concentration of divalent dissolved species comprises utilizing a cation exchange column.

22. The method of claim 21, further comprising regenerating the cation exchange column with the byproduct stream.