Process for in situ bioremediation of subsurface contaminants

1. A method of stimulating anaerobic degradation of subsurface contaminants, comprising the steps of:

a) vaporizing a liquid electron donor to form an electron donor gas, wherein the electron donor is a liquid at a temperature of 0° C. and a pressure of 1 atmosphere;

b) mixing the electron donor gas with a carrier gas to form a treating gas having an electron donor component; and

c) directing the treating gas to a subsurface injection site that includes at least one perchlorate contaminant;

wherein the treating gas stimulates anaerobic degradation of at least a portion of the perchlorate contaminant.

2. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of an organic acid, an aldehyde, an amine, a ketone, and an ester.

3. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of formic acid, acetic acid, propionic acid, butyric acid, and isomers thereof.

4. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of dimethylamine, diethylamine, ethanolamine, and isomers thereof.

5. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of acetone, methyl ethyl ketone, and ethyl vinyl ketone.

6. The method of claim 1 , wherein the electron donor includes butyl acetate.

7. The method of claim 1 , wherein the electron donor includes ethyl acetate.

8. The method of claim 1 , wherein the electron donor includes an alkene.

9. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of hexene, octene, isoprene, butadiene, and isomers thereof.

10. The method of claim 1 , wherein the electron donor includes an alkyne.

11. The method of claim 1 , wherein the electron donor includes an aromatic hydrocarbon.

12. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of toluene, xylene, cumene, cymene, and isomers thereof.

13. The method of claim 1 , wherein the electron donor includes at least one member of the group consisting of methanol, propanol, butanol, and isomers thereof.

14. The method of claim 1 , wherein the electron donor includes ethanol.

15. The method of claim 1 , wherein the electron donor is heated to form the electron donor gas.

16. The method of claim 1 , further including the step of heating the carrier gas.

17. The method of claim 16 , wherein the heated carrier gas is used to promote vaporization of the liquid electron donor.

18. The method of claim 1 , wherein subsurface injection site includes groundwater.

19. The method of claim 18 , wherein the subsurface injection site includes perched water.

20. The method of claim 1 , wherein the subsurface injection site includes soil.

21. The method of claim 20 , wherein the soil is in the vadose zone.

22. The method of claim 1 , wherein the subsurface injection site is at least 5 feet below ground surface.

23. The method of claim 1 , wherein the subsurface injection site is at least 20 feet below ground surface.

24. The method of claim 1 , wherein the electron donor gas is directed to more than one subsurface injection site.

25. The method of claim 1 , wherein the amount of electron donor gas mixed with the carrier gas is controlled to prevent condensation of the electron donor component from the treating gas.

26. The method of claim 1 , further including a step of controlling the partial pressure of the electron donor component to prevent the partial pressure from exceeding the saturation vapor pressure of the electron donor at subsurface conditions, thereby preventing condensation of the electron donor component from the treating gas.

27. The method of claim 1 , wherein the carrier gas includes at least one member of the group consisting of steam, air, carbon dioxide, nitrogen, argon, and gas extracted from the subsurface.

28. The method of claim 1 , wherein the carrier gas is substantially devoid of oxygen.

29. The method of claim 1 , wherein the carrier gas includes water vapor.

30. The method of claim 1 , further including a step of directing water vapor to the subsurface site.

31. A method of stimulating anaerobic degradation of subsurface contaminants, comprising the steps of:

a) vaporizing a liquid electron donor to form an electron donor gas, wherein the electron donor is a liquid at a temperature of 0° C. and a pressure of 1 atmosphere and includes at least one member selected from the group consisting of an aldehyde, an alkene, an alkyne, an amine, an aromatic hydrocarbon, an ester, a ketone, an organic acid, ethyl acetate, methanol, ethanol, propanol, butanol, and isomers thereof;

b) mixing the electron donor gas with a carrier gas to form a treating gas having an electron donor component; and

c) directing the treating gas to a subsurface injection site that includes at least one contaminant;

wherein the treating gas stimulates anaerobic degradation of at least a portion of the contaminant.

32. The method of claim 31 , wherein the contaminant is a nitrate compound.

33. The method of claim 31 , wherein the contaminant is a perchlorate compound.

34. The method of claim 31 , wherein the contaminant is a chlorinated compound.

35. The method of claim 31 , wherein the contaminant is a halogenated organic compound.

36. The method of claim 31 , wherein the electron donor includes at least one member of the group consisting of formic acid, acetic acid, propionic acid, butyric acid, and isomers thereof.

37. The method of claim 31 , wherein the electron donor includes at least one member of the group consisting of dimethylamine, diethylamine, ethanolamine, and isomers thereof.

38. The method of claim 31 , wherein the electron donor includes at least one member of the group consisting of acetone, methyl ethyl ketone, and ethyl vinyl ketone.

39. The method of claim 31 , wherein the electron donor includes ethyl acetate.

40. The method of claim 31 , wherein the electron donor includes at least one member of the group consisting of hexene, octene, isoprene, butadiene, and isomers thereof.

41. The method of claim 31 , wherein the electron donor includes at least one member of the group consisting of toluene, xylene, cumene, cymene, and isomers thereof.

42. The method of claim 31 , wherein the electron donor includes at least one member of the group consisting of methanol, propanol, butanol, and isomers thereof.

43. The method of claim 31 , wherein the electron donor includes ethanol.

44. The method of claim 31 , wherein the electron donor is heated to form the electron donor gas.

45. The method of claim 31 , further including the step of heating the carrier gas.

46. The method of claim 45 , wherein the heated carrier gas is used to promote vaporization of the liquid electron donor.

47. The method of claim 31 , wherein subsurface injection site includes groundwater.

48. The method of claim 47 , wherein the subsurface injection site includes perched water.

49. The method of claim 31 , wherein the subsurface injection site includes soil.

50. The method of claim 49 , wherein the soil is in the vadose zone.

51. The method of claim 31 , wherein the subsurface injection site is at least 5 feet below ground surface.

52. The method of claim 31 , wherein the subsurface injection site is at least 20 feet below ground surface.

53. The method of claim 31 , wherein the electron donor gas is directed to more than one subsurface injection site.

54. The method of claim 31 , wherein the amount of electron donor gas mixed with the carrier gas is controlled to prevent condensation of the electron donor component from the treating gas.

55. The method of claim 31 , further including a step of controlling the partial pressure of the electron donor component to prevent the partial pressure from exceeding the saturation vapor pressure of the electron donor at subsurface conditions, thereby preventing condensation of the electron donor component from the treating gas.

56. The method of claim 31 , wherein the carrier gas includes at least one member of the group consisting of steam, air, carbon dioxide, nitrogen, argon, and gas extracted from the subsurface.

57. The method of claim 31 , wherein the carrier gas is substantially devoid of oxygen.

58. The method of claim 31 , wherein the carrier gas includes water vapor.

59. The method of claim 31 , further including a step of directing water vapor to the subsurface site.

60. A method for stimulating anaerobic degradation of subsurface perchlorate contaminants, comprising the step of directing hydrogen gas to a subsurface site, wherein the subsurface site includes at least one perchlorate contaminant and the hydrogen gas stimulates anaerobic degradation of at least a portion of the perchlorate contaminant.

61. The method of claim 60 , further including the step of mixing the hydrogen gas with a carrier gas before it is directed to the subsurface site.

62. A method of stimulating anaerobic degradation of subsurface perchlorate contamination, comprising the steps of:

a) vaporizing liquid ethanol to form ethanol gas;

b) mixing the ethanol gas with a carrier gas to form a treating gas that includes from about 0.1% to about 2.5% ethanol gas by volume; and

c) directing the treating gas to a subsurface injection site;

wherein the subsurface injection site includes at least one perchlorate contaminant and the treating gas stimulates anaerobic degradation of at least a portion of the perchlorate contamination.

63. A method of stimulating anaerobic degradation of subsurface perchlorate contamination, comprising the steps of:

a) vaporizing liquid methanol to form methanol gas;

b) mixing the methanol gas with a carrier gas to form a treating gas that includes from about 0.1% to about 7% methanol gas by volume; and

c) directing the treating gas to a subsurface injection site;

wherein the subsurface injection site includes at least one perchlorate contaminant and the treating gas stimulates anaerobic degradation of at least a portion of the perchlorate contamination.

64. A method of stimulating anaerobic degradation of subsurface perchlorate contamination, comprising the steps of:

a) vaporizing liquid ethyl acetate to form ethyl acetate gas;

b) mixing the ethyl acetate gas with a carrier gas to form a treating gas that includes from about 0.1% to about 4% ethyl acetate gas by volume; and

c) directing the treating gas to a subsurface injection site;

wherein the subsurface injection site includes at least one perchlorate contaminant and the treating gas stimulates anaerobic degradation of at least a portion of the perchlorate contamination.

65. A method of stimulating anaerobic degradation of subsurface perchlorate contamination, comprising the steps of:

a) vaporizing liquid hexene to form hexene gas;

b) mixing the methanol gas with a carrier gas to form a treating gas that includes from about 0.1% to about 6.5% hexene gas by volume; and

c) directing the treating gas to a subsurface injection site;

wherein the subsurface injection site includes at least one perchlorate contaminant and the treating gas stimulates anaerobic degradation of at least a portion of the perchlorate contamination.