Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Destruction of hazardous or toxic waste
Reexamination Certificate
1994-10-05
2001-04-03
Gitomer, Ralph (Department: 1623)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Destruction of hazardous or toxic waste
C252S061000, C252S391000
Reexamination Certificate
active
06210955
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for in-situ remediation of contaminated soils by the addition of certain treatment agents, such as chemicals to enhance mass transfer of pollutants from soils and non-aqueous phase liquids and to stimulate bacteria to degrade organic pollutants. More particularly, this invention relates to an improved method for the delivery of chemicals for enhancing bioremediation and for the physico-chemical separation and removal of pollutants from contaminated soil and groundwater whereby the pollutants are desorbed from the soil and non-aqueous phase liquids, such as tar and oil, and are available for biodegradation and/or physical removal from the soil by a mobile foam fluid phase. This invention also relates to a method for enhancing electrokinetic, electromagnetic and radio frequency (RF) in-situ treatment processes for in-situ treatment of inorganic and hydrocarbon pollutants in contaminated soils using foams.
2. Description of Prior Art
The conventional method for chemical enhancement of in-situ treatment of contaminated soils consists of the introduction of chemicals using hundreds of thousands of gallons of water into the soil subsurface using infiltration galleries. The main disadvantage of this technique is that the water carrier stream provides poor penetration into clay lenses and non-aqueous phase liquids and moves in a downward direction, due to gravity, into the underlying groundwater.
Subsurface contamination of soil is typically caused by spills or waste impoundments that have leaked over many years and have been observed at a variety of industry and government-owned facilities. Such sites include abandoned manufactured gas plants which release tars and polynuclear aromatic hydrocarbons (PAH's), creosote treatment sites which release tars, PAH's, and pentachlorophenol, spills at refineries which release oils and PAH's, gas dehydration facilities which release triethylene glycol and benzene, toluene, ethylbenzene and xylene, military bases, and oil and gas production pits. Cleanup of contamination in the deep subsurface, that is 4 or more feet below the surface of the soil, is cost-prohibitive to excavate and difficult to treat without considerable risk to the groundwater. As a result, there is a need to develop low-cost environmentally acceptable approaches for in-situ treatment.
Much work has been done in the past to develop various remediation approaches for the removal of pollutants from the soil subsurface such as in-situ bioremediation which has the potential for destroying pollutants in the subsurface at a low cost, for example, by the introduction of chemical enhancements such as Fenton's Reagent (iron/peroxide) and surfactants which promote biodegradation of pollutants in soils contaminated with non-aqueous phase liquids. In particular, surfactants and Fenton's Reagent are known to enhance the desorption of pollutants from the non-aqueous phase liquids and soil, thereby providing controlled solubilization of the pollutants, making them amenable to biological attack. See, for example, Kelley, R. L. et al., “Field-Scale Evaluation of an Integrated Treatment for Remediation of PAH's in Manufactured Gas Plant Soils,” Institute of Gas Technology, Chicago, Ill.
The use of chemicals to enhance the desorption of pollutants from non-aqueous phase liquids and soil is also described in the literature for in-situ treatment. See, for example, Wunderlich, R. W., “In Situ Remediation of Aquifers Contaminated with Dense Nonaqueous Phase Liquids by Chemically Enhanced Solubilization,”
Journal of Soil Contamination,
1(4):361-37. Enhancement agents include nutrients, such as ammonia and orthophosphate, solvents, such as methanol and ethanol, and microbial cultures. Biological in-situ treatment occurs when nutrients, oxidants and other enhancements are added to the subsurface to stimulate bacteria in the subsurface to degrade organic pollutants. Various types of biological in-situ designs are discussed in the literature, for example Wunderlich et al. cited hereinabove and Sims, J. L. et al., “In Situ Bioremediation of Contaminated Unsaturated Subsurface Soils,” USEPA Engineering Issue No. EPA/540/S-3/501, Robert S. Kerr Environmental Research Laboratory, Ada, Okla. It is believed that the enhancements reported in the literature for soil bioremediation are broadly applicable to the in-situ cleanup of a wide variety of industrial and the government sites. The challenge is in developing a method of delivering the chemical and biological enhancements for in-situ remediation of the subsurface without inadvertently contaminating the underlying groundwater or uncontaminated soils surrounding the contaminated site.
The Sims et al. reference cited hereinabove describes a number of delivery techniques currently in use including gravity infiltration and forced hydraulic delivery, the various designs of which include flooding, ponding, ditches, sprinkler systems, and subsurface injection techniques. All of these conventional methods for delivery of enhancement chemicals to the subsurface pose a considerable risk to groundwater because they involve the gravity flow of hundreds of thousands of gallons of chemical-bearing water streams that can move through contaminated regions of the subsurface, pick up considerable concentrations of pollutants and flow past non-aqueous phase liquids and clay lenses into the underlying and surrounding groundwater aquifers.
The primary problem with water-based delivery systems for chemicals transport in the subsurface is that gravitational forces have a dominating influence over the direction of flow of these fluids, thereby resulting in increased risk to groundwater. In contrast to water-based delivery systems, foam flow in porous media is not dominated by gravity but can be directed in the subsurface by differences of pressure and resistance to flow in the porous media. Aqueous foams are utilized in a number of applications, particularly in petroleum production. These include the use of foam for enhancement of oil recovery and as a selective blocking fluid in heterogeneous reservoirs. Foams are also known to be employed in near-well operations, such as sand clean-out, stimulation and sealing of the formation to control groundwater movement, or losses of injected fluids such as gas in underground gas storage reservoirs. Literature relevant to the application of foams to the recovery of oil from porous media is summarized in Nutt, C. W. et al., “The Influence of Foam Rheology in Enhanced Oil Recovery Operations,” pp. 105-147,
Foams: Physics, Chemistry and Structure,
edited by A. J. Wilson, Spronger-Verlag, New York, N.Y. The technical feasibility of utilizing aqueous foams in porous media to mobilize a type of non-aqueous phase liquid for enhanced oil recovery which is performed more than 3,000 feet below the surface is generally disclosed by this body of literature. See also U.S. Pat. Nos. 5,203,413, 5,076,357, 5,074,358, 4,681,164, 3,953,338, and 3,707,193, all of which generally relate to the use of foams for enhancing oil recovery and/or for treating oil wells.
U.S. Pat. No. 3,822,750 teaches a method and apparatus for cleaning wells by forming a foamy aqueous solution at the bottom of the well and forcing a sand-bearing foamy aqueous solution with oil-bearing sand to the top of the well. U.S. Pat. No. 3,195,634 teaches a fracturing process for treating earth formations containing oil or gas deposits in which a composition comprising liquid carbon dioxide and an aqueous fluid as a fracturing fluid is injected as a liquid into the formation to be treated until maximum penetration has been achieved. Pressure at the well head is maintained until the desired action of the treating fluid in the formation has occurred in which the pressure is relieved causing the liquids previously injected into the formation to flow back into the well, liberating carbon dioxide gas in the formation as well as suspended in the aqueous fluid in the form of bubbl
Gas Research Institute
Gitomer Ralph
Pauley Petersen Kinne & Fejer
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