WATER TREATMENT USING DE-SUPERSATURATION

• US 20080121585A1
• Filed: 11/26/2007
• Published: 05/29/2008
• Est. Priority Date: 11/27/2006
• Status: Abandoned Application

• Current Assignee: CH2M Hill Incorporated (CH2M Hill Companies Limited)
• Original Assignee: CH2M Hill Incorporated (CH2M Hill Companies Limited)
• Inventors: Mavis, James D.
• Application Number:
  US11/945,012
• Publication Number:
  US 20080121585A1
• Time in Patent Office: Days
• US Class Current: 210/652
• CPC Class Codes: B01D 2311/08 Specific process operations in the concentrate stream
• CPC Class Codes: B01D 2311/12 Addition of chemical agents
• CPC Class Codes: B01D 2311/26 Further operations combined with membrane separation processes
• CPC Class Codes: C02F 1/38 by centrifugal separation
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: C02F 1/4693 electrodialysis
• CPC Class Codes: C02F 1/5236 using inorganic agents
• CPC Class Codes: C02F 2101/101 Sulfur compounds
• CPC Class Codes: C02F 2103/023 Water in cooling circuits
• CPC Class Codes: C02F 2103/06 Contaminated groundwater or leachate
• CPC Class Codes: C02F 2103/10 from quarries or from mining activities
• CPC Class Codes: C02F 2305/12 Inert solids used as ballast for improving sedimentation C02F3/1226 takes precedence

Abstract

A method for treating water includes removing a supersaturated sparingly soluble salt via a self-sustaining de-supersaturation process in which the supersaturated water is contacted with a nucleation material that is reused in the process. Supersaturated reject water from reverse osmosis systems may be de-supersaturated, reducing scale formation on downstream water treatment systems and pipelines. The method may be used for treatment of sulfate-contaminated groundwater, and groundwater contaminated via mining and processing of sulfide ores, and in other applications.

Claims

1. A method for treating water, comprising:

performing a first separating step by reverse osmosis or electro dialysis, in a first separating system, to separate first intake water into purified clean water and reject water, with the reject water supersaturated with a dissolved solid;

moving the reject water into a reactor;

de-supersaturating the reject water in the reactor in a self-sustaining de-supersaturation process via the reject water contacting a nucleation material in the reactor;

removing a flow of de-supersaturated water from the reactor;

recovering nucleation material and recycling it to the de-supersaturation reactor to maintain the de-supersaturation process; and

performing a second separating step on the de-supersaturated water by reverse osmosis or electro-dialysis, in a second separating system.

2. The method of claim 1 further comprising adding a scale inhibitor to the de-supersaturated water, before performing the second reverse osmosis step in the second reverse osmosis system.

3. The method of claim 1 further comprising moving the de-supersaturated water into a clarifier, and moving a first flow of the de-supersaturated water from the clarifier to the second reverse osmosis system, and moving a second flow of the de-supersaturated water from the clarifier back to the reactor.

4. The method of claim 1 wherein nucleation material is collected from a first location adjacent to a lower end of the reactor and is returned to the reactor at a second location above the first location.

5. The method of claim 1 further comprising moving the de-supersaturated water into a hydrocyclone, and moving a first flow of the de-supersaturated water from the hydrocyclone to the second reverse osmosis system, and moving a second flow of the de-supersaturated water from the hydrocyclone back to the reactor.

6. The method of claim 1 wherein the reject water is supersaturated with gypsum, calcium carbonate, barium sulfate, silica or other scale-forming substances.

7. The method in claim 1 wherein no scale inhibitor is added to the water, the reactor comprises a single-stage, continuous-flow, stirred-tank reactor, and the concentration of the nucleation material in the water in the reactor is maintained above two percent by weight.

8. The method of claim 1 wherein no scale inhibitor is added to the water, the reactor comprises two or three continuous-flow, stirred-tank reactors, and with the concentration of nucleation material in the water in the stirred-tank reactors maintained below two percent by weight.

9. The method of claim 1 further comprising adding a scale inhibitor to the water;

the reactor is a single-stage continuous-flow, stirred-tank reactor, and the concentration of the nucleation material in the water in the stirred-tank reactor is maintained above 12 percent by weight.

10. The method of claim 1 further comprising adding a scale inhibitor to the water;

the reactor comprises two or three continuous-flow, stirred-tank reactors, and the concentration of the nucleation material in the water in the stirred-tank reactors is maintained below 12 percent by weight.

11. The method of claim 1 wherein the de-supersaturation reactor comprises a packed bed reactor.

12. The method of claim 1 further comprising adding a scale inhibitor to the de-supersaturated water, before performing the second separating step.

13. The method of claim 1 wherein the dissolved solid comprises gypsum, calcium carbonate, barium sulfate, and/or silica.

14. The method of claim 1 wherein reduced scale is formed in a pipe, and the second separating step creates second supersaturated reject water, and further comprising de-supersaturating the second reject water, and then conducting the de-supersaturated reject water through the pipe.

15. A method for treating water, comprising:

performing a first separating step by reverse osmosis or electrodialysis in a first separating system to separate first intake water into purified water and reject water, with the reject water supersaturated with a dissolved solid;

de-supersaturating the reject water by a self-sustaining de-supersaturation process via the reject water contacting a nucleation material;

performing a second operation with the de-supersaturated water to reclaim purified water.

16. A method for treating water containing mine tailings, comprising:

mixing first and second non-supersaturated streams of water in a reactor, with the first stream containing mine tailings and at least a first level of suspended solids, and with the first and second streams forming a supersaturated combination I in the reactor;

substantially continuously de-supersaturating the supersaturated combination in the reactor, with the suspended solids acting as nucleation material, and without recycling precipitated nucleation material to the reactor./

17. A system for treating water, comprising:

a first purification system processing intake water into a purified water stream and a supersaturated reject water stream;

a reactor receiving the supersaturated reject water stream, with the reactor containing a recycled de-supersaturating agent for de-supersaturating the supersaturated reject water in the reactor;

a clarifier receiving the de-supersaturated reject water and separating the de-supersaturated reject water into a first flow and a second flow; and

a second purification system receiving the first flow from the clarifier, and with part of the second flow from the clarifier returned to the reactor.

18. The system of claim 17 wherein the first and second purification systems comprise reverse osmosis systems.

19. A system for treating water, comprising:

a first purification system adapted to process intake water into a purified water stream and a supersaturated reject water stream;

a reactor receiving the supersaturated reject water stream, with the reactor containing a recycled de-supersaturating agent for de-supersaturating the supersaturated reject water in the reactor;

a hydrocyclone receiving the de-supersaturated reject water and separating the de-supersaturated reject water into a first flow and a second flow; and

a second purification system receiving the first flow from the hydrocyclone, and with part of the second flow from the hydrocyclone returned to the reactor.

20. The system of claim 19 with the first and second purification systems comprising reverse osmosis systems.

21. The system of claim 19 with the first and second purification systems comprising electrodialysis or electrodialysis reversal systems.

22. The system of claim 19 with the reactor comprising a stirred tank reactor.

23. The system of claim 19 further comprising a filter positioned to filter the de-supersaturated reject water moving from the clarifier to the second purification system.

24. A system for treating water, comprising:

a first membrane purification system processing intake water into a purified water stream and a supersaturated reject water stream;

a fluidized bed reactor receiving the supersaturated reject water stream, and containing particles reacting with the supersaturated reject water causing a supersaturated dissolved solid in the reject water to precipitate out, leaving the reject water de-supersaturated;

a second membrane purification system receiving the de-supersaturated water from the reactor;

or

a down-stream operation such as conveyance through a pipeline that would otherwise be susceptible to scale formation.