Hydraulic and earth engineering – Soil remediation – In situ contaminant removal or stabilization
Patent
1994-04-04
1997-04-01
Suchfield, George A.
Hydraulic and earth engineering
Soil remediation
In situ contaminant removal or stabilization
405263, B09B 300
Patent
active
056159749
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an oxidation and vacuum extraction process for in situ removal of subsurface contaminants.
BACKGROUND OF THE INVENTION
Sources of subsurface contamination are numerous, for example, leaky underground storage tanks, industrial and manufacturing operations, chemical storage and process areas, chemical spills and waste disposal areas. Among common contaminants from these sources are petroleum hydrocarbons, such as benzene, toluene and xylene, gasoline, diesel, jet fuel and others; chlorinated hydrocarbons, such as trichloroethylene (TCE), tetrachloroethylene (PCE), chlorobenzene and chlorophenols; and other volatile, semi-volatile and non-volatile organic compounds. Once such contaminants are within the vadose zone they can leach down into the groundwater table and become long term sources of groundwater contamination which typically persist for decades. The vadose zone, also known as the zone of aeration, is the unsaturated zone of the soil that is above the groundwater table and the capillary fringe (i.e., the transition zone between the vadose zone and the groundwater table). Typically, the capillary fringe has about a 75% to about a 90% water content and the vadose zone has from about a 30% to about a 50% water content. In order to protect groundwater resources and provide unrestricted use of land and groundwater, clean-up of subsurface contamination is necessary at many sites.
One well known process in the field of subterranean environmental clean-up is the process of vacuum extraction. [See U.S. Pat. No. 4,593,760 by Visser and Malot, issued Jun. 10, 1986, on which a Reexamination Certificate was granted Jun. 20, 1989; and U.S. Pat. No. Reissue 33,102 by Visser and Malot, issued Oct. 31, 1989.] The vacuum extraction process removes volatile and semi-volatile organic compounds, petroleum hydrocarbons, and other liquid contaminants from the vadose zone. In the vacuum extraction process, a subsurface vacuum enhances volatilization of volatile organic compounds in the subsurface, and the vacuum induced air flow removes these volatilized contaminants from contaminated soil.
The vacuum extraction process typically works faster on compounds of higher vapor pressure (i.e., greater than or equal to 1 mm Hg at 20.degree. C.) than those of lower vapor pressure (i.e., less than about 1 mm Hg at 20.degree. C.). Compounds with low vapor pressures have been removed successfully by vacuum extraction, but at a slower removal rate than that of higher vapor pressure volatile organic compounds. In cases where the subsurface is contaminated with a dense non-aqueous phase liquid (DNAPL), such a compound, being more dense than water, tends to sink deep into the subsurface and even into or below the groundwater aquifer. Once the DNAPLs are in or below the groundwater aquifer, they are generally considered untreatable.
Because of its oxidation potential, hydrogen peroxide, and more specifically, the hydroxyl radical, is known to be an effective treatment method for removal of contaminants from soils and waste streams. [See Schneider, D. R. and Billingsley, R. J., "Bioremediation--A Desk Manual for the Environmental Professional," Pudvan Pub. Co., Northbrook, Ill., pp. 60-61 (1990); Watts, R. J., Solomon, W. L., and Udell, M. D., "Treatment of Contaminated Soils Using Catalyzed Hydrogen Peroxide," Dept. of Civil Eng., Washington State Univ. (1990); Watts, R. J., Udell, M. D., Rauch, P. A. and Leung, S. W., "Treatment of Pentachlorophenol-Contaminated Soils Using Fenton's Reagent," Hazardous Waste & Hazardous Materials, Vol. 7, No. 4 (1990); and Watts, R. J., "Hydrogen Peroxide for Physicochemically Degrading Petroleum-Contaminated Soils," Remediation Magazine, pp. 413-425 (1992).] The oxidation potential of hydrogen peroxide is also a well known phenomenon and has been studied since the turn of the century. The basic reaction is the oxidation of an organic molecule, such as a hydrocarbon, phenol or a chlorinated compound, to form a variety of oxidized products. [See Sedlak, D.
REFERENCES:
patent: 4593760 (1986-06-01), Visser
patent: 4915452 (1990-04-01), Dibble
Land Christopher A.
Malot James J.
Oberle Daniel
Papa Louis C.
Pezzullo Joseph A.
Suchfield George A.
Terra Vac, Inc.
LandOfFree
Process for soil decontamination by oxidation and vacuum extract does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for soil decontamination by oxidation and vacuum extract, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for soil decontamination by oxidation and vacuum extract will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-534438