# US 7,744,760 B2 · Method and apparatus for desalination

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- Number: US 7,744,760 B2
- Document ID: US7744760B2
- Status: Granted
- Kind: B2
- Application number: 11/524,080
- Filed: 2006-09-20
- Published: 2008-03-20
- Granted: 2010-06-29
- Earliest claimed: 2006-09-20
- Assignees: Siemens Water Technologies Corp.
- Inventors: Frederick C. Wilkins; Anil D. Jha; Gary C. Ganzi
- Web page: https://patentgrep.com/patent/US7744760B2

## CPC

- C02F 1/442: {by nanofiltration}
- B01D 61/422: {Electrodialysis}
- B01D 61/58: Multistep processes
- C02F 1/4695: {electrodeionisation}
- B01D 61/027: {Nanofiltration}
- B01D 61/147: {Microfiltration}
- B01D 61/48: having one or more compartments filled with ion-exchange material {, e.g. electrodeionisation}
- B01D 2317/025: Permeate series
- C02F 1/42: by ion-exchange (ion-exchange in general B01J)
- C02F 1/444: {by ultrafiltration or microfiltration}
- C02F 1/4693: {electrodialysis}
- C02F 2103/08: Seawater, e.g. for desalination
- Y02A 20/124: Water desalination
- Y02A 20/131: Reverse-osmosis
- Y02W 10/33: using wind energy
- Y02W 10/37: using solar energy
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## 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 nanofiltration membrane to produce a permeate that can, in turn, be fed to an electrodeionization system to produce fresh water.

## Claims

### Claim 1

A method of reducing total dissolved solids in seawater comprising:
reducing a concentration of dissolved solids in the seawater in a nanofiltration device to produce a first partially treated water;
reducing a concentration of dissolved solids in the first partially treated water in an electrodialysis device to produce a second partially treated water; and
reducing a concentration of dissolved solids in the second partially treated water in an electrodeionization device to produce treated water having less than about 1,000 ppm total dissolved solids and a boron content of less than about 0.5 ppm,
wherein energy consumption to produce the treated water through the nanofiltration device, the electrodialysis device, and the electrodeionization device is less than about 7 kwh/kgal.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

The method of claim 1 wherein the treated water comprises less than about 500 ppm total dissolved solids.

### Claim 4 (depends on 1)

The method of claim 1, further comprising mixing a concentrate stream from the electrodeionization device with the seawater upstream of the nanofiltration device.

### Claim 5 (depends on 1)

The method of claim 1, wherein reducing the concentration of dissolved solids from the first partially treated water comprises producing the second partially treated water from an electrodialysis device having monovalent selective membranes.

### Claim 6 (depends on 1)

The method of claim 1, wherein reducing the concentration of dissolved solids in the seawater in a nanofiltration device comprises reducing a concentration of monovalent species in the seawater stream to produce the first partially treated water product.

### Claim 7 (depends on 1)

The method of claim 1, wherein the treated water has more than about 230 ppm total dissolved solids.