Chemical tailoring of steam to remediate underground mixed waste contaminents

• US 5,986,159 A
• Filed: 09/16/1997
• Issued: 11/16/1999
• Est. Priority Date: 09/16/1997
• Status: Expired due to Fees

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Bruton, Carol J., Udell, Kent S., Aines, Roger D., Carrigan, Charles R.
• Primary Examiner(s): Phasge, Arun S.
• Application Number:
  US08/931,425
• Time in Patent Office: 791 Days
• Field of Search: 588/19, 588/209, 588/213, 588/216, 588/220, 588/230, 405/131, 134/2
• US Class Current: 588/19
• CPC Class Codes: B09C 1/02 Extraction using liquids, e.g. washing, leaching , flotation
• CPC Class Codes: B09C 1/06 thermally
• CPC Class Codes: B09C 1/08 chemically
• CPC Class Codes: B09C 2101/00 In situ
• CPC Class Codes: G21F 9/30 Processing separating different isotopes of the same chemical element B01D59/00

Abstract

A method to simultaneously remediate mixed-waste underground contamination, such as organic liquids, metals, and radionuclides involves chemical tailoring of steam for underground injection. Gases or chemicals are injected into a high pressure steam flow being injected via one or more injection wells to contaminated soil located beyond a depth where excavation is possible. The injection of the steam with gases or chemicals mobilizes contaminants, such as metals and organics, as the steam pushes the waste through the ground toward an extraction well having subatmospheric pressure (vacuum). The steam and mobilized contaminants are drawn in a substantially horizontal direction to the extraction well and withdrawn to a treatment point above ground. The heat and boiling action of the front of the steam flow enhance the mobilizing effects of the chemical or gas additives. The method may also be utilized for immobilization of metals by using an additive in the steam which causes precipitation of the metals into clusters large enough to limit their future migration, while removing any organic contaminants.

Claims

1. A method for in situ decontamination of a subsurface area containing mixed-waste, comprising:

providing a quantity of steam;

chemically tailoring the steam with an additive to form a steam-additive mixture;

pressuring the steam-additive mixture;

injecting the pressurized steam-additive mixture underground and adjacent an area containing the mixed-waste;

directing the pressurized steam-additive mixture through a subsurface area containing the mixed-waste;

providing a subatmospheric extraction means located in spaced relation to the injected steam-additive mixture;

whereby the steam-additive mixture mobilizes at least one of the components in the mixed-waste and such is passed through the subsurface area toward the subatmospheric extraction means for withdrawal from the area containing the mixed-waste.

2. The method of claim 1, wherein the additive mixed with the steam is an additive which has the capability to mobilize at least organic and metallic components of the mixed-waste.

3. The method of claim 2, wherein the mobilization of the metallic component is carried out by solubilizing the metallic component.

4. The method of claim 3, wherein solubilizing the metallic component is carried out by changing oxidation state of the metallic component by changing the Eh or pH of the steam additive mixture.

5. The method of claim 1, wherein the additive mixed with the steam is an additive which has the capability to at least mobilize an organic component of the mixed-waste, and immobilize at least a metallic component of the mixed-waste.

6. The method of claim 5, wherein the immobilization of the metallic component is carried out by precipitation of the metallic component in clusters large enough to limit future migration thereof.

7. The method of claim 1, wherein the additive is a metallic or radionuclide mobilizing additive selected from the group consisting of crown ethers, carboxylic acids, halides and amides and citrate.

8. The method of claim 1, wherein the additive is a gas.

9. The method of claim 8, wherein the gas is an oxidizing or reducing gas.

10. The method of claim 1, wherein the additive is a metallic immobilizing additive selected from the group consisting of H₂, CO, and O₂.

11. A method for in situ decontamination of a contaminated subsurface area containing mixed-waste including organics and metals or radionuclides, comprising:

providing an injection well system comprising at least one injection well located within the contaminated area;

providing at least one extraction well located within the contaminated area and spaced from the at least one injection well;

chemically tailoring the steam with an additive;

concurrently injecting the steam-additive into the injection well system and applying subatmospheric pressure to the extraction well, whereby the steam-additive is pushed and drawn in a substantially horizontal direction through the contaminated subsurface area toward the extraction well and whereby said steam-additive causes mobilization of at least an organic component of the mixed-waste and causes either mobilization or immobilization of at least a metallic or radionuclide component of the mixed-waste;

withdrawing through the extraction well at least the mobilized contaminants; and

ceasing injection of the steam-additive into the injection well system.

12. The method of claim 11, additionally including continuing the application of subatmospheric pressure at the extraction well to withdraw residual steam, water, and mobilized contaminants from the subsurface area.

13. The method of claim 11, additionally providing a plurality of injection wells proximate to the periphery of and/or within said contaminated area.

14. The method of claim 11, additionally including forming the additive to enable mobilization of any organic component in the mixed waste.

15. The method of claim 14, additionally including forming the additive to also enable mobilization of any metal or radionuclide component in the mixed waste.

16. The method of claim 15, wherein mobilization of any metal component in the mixed waste is carried out by solubilizing the metal component.

17. The method of claim 16, wherein solubilizing the metal component is carried out by changing oxidation state of the metal.

18. The method of claim 14, additionally including forming the additive to also enable immobilization of any metal or radionuclide component in the mixed waste.

19. The method of claim 18, wherein immobilization of any metal component in the mixed waste is carried out by precipitation of the metal into clusters.

20. The method of claim 11, wherein the additive is selected from an oxidizing gas and a reducing gas.