Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2000-04-18
2001-04-03
Upton, Christopher (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S620000, C210S747300, C210S908000, C210S909000, C435S262500
Reexamination Certificate
active
06210579
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the degradation of pollutants, and more particularly relates to bioremediation of pollutants such as chlorinated aliphatic hydrocarbons using butane-utilizing microorganisms.
BACKGROUND INFORMATION
Chlorinated, volatile, aliphatic hydrocarbons such as trichloroethene (TCE) are the most commonly reported contaminants of groundwater. Through releases of solvents, degreasers and other compounds, chlorinated compound contamination in surface and subsurface environments has reached high levels, and in many areas has seriously jeopardized drinking water aquifers and reservoirs. TCE is a suspected human carcinogen and remains the number one priority pollutant on the National Priority List of the U.S. Environmental Protection Agency.
When the discovery of the magnitude of chlorinated contamination in aquifer systems in the United States, and worldwide, came to light in the early 1980s, few approaches were developed to aggressively remediate the chlorinated contaminated sites. Available remediation methods for subsurface-environments include air sparging of the groundwater and the vacuum extraction of contaminants from the vadose zone. These remedial strategies transfer contamination from the subsurface environment to either the air or to activated carbon which must then be landfilled or incinerated. Landfilling contaminated activated carbon transfers the contamination from one source area to another while incineration is costly and requires considerable energy and costly equipment to completely volatilize organic compounds. Treatment strategies based on oxidation of contaminants that use ultraviolet radiation in combination with a chemical oxidant like hydrogen peroxide are also energy costly and require the injection of expensive chemicals.
Bioremediation is a method of harnessing the ability of microorganisms to degrade toxic pollutants. Anaerobic biodegradation of TCE usually results in the formation of harmful metabolites such as dichloroethylenes and the known carcinogen vinyl chloride.
The ability of aerobic methane-utilizing bacteria to degrade TCE cometabolically is known. However, the use of methane-utilizing bacteria is limited due to the toxic effects of chlorinated hydrocarbons like TCE in rather low concentrations. As disclosed by Broholm et al., “Toxicity of 1,1,1-Trichloroethane and Trichloroethene on a Mixed Culture of Methane-Oxidizing Bacteria”,
Applied and Environmental Microbiology
, Aug. 1990, p. 2488-2493, the toxic effects of trichloroethene become substantial above 6 mg per liter (ppm) in water. In addition, trace amounts of copper have proven to inhibit methane monooxygenase.
The use of methane-utilizing bacteria to degrade TCE is disclosed in several patents. For example, U.S. Pat. No. 5,037,551 to Barkley and U.S. Pat. No. 5,057,221 to Bryant et al. disclose ex-situ bioreactors using a rigid substrate bed to support aerobic methanotrophic microorganisms which degrade halogenated organic compounds. The substrate bed may be made of manufactured solid material, such as activated carbon particles or contoured plastic spheres. In each of these patents, examples are provided wherein methane is supplied to an ex-situ bioreactor to degrade the halogenated organic compounds. In addition, U.S. Pat. No. 5,057,221 includes an example wherein propane is supplied to the bioreactor bed.
U.S. Pat. No. 5,384,048 to Hazen et al. discloses an in-situ groundwater bioremediation apparatus and method using a methane nutrient source. Bioremediation is carried out by periodically injecting nutrient fluid into the contaminant groundwater plume to stimulate the subsurface population of the microorganisms to increase. An oxygenated fluid is also injected into the plume to allow the aerobic microorganisms to break down the contaminants. The particular microorganisms disclosed are indigenous methanotrophs capable of biodegrading TCE by a series of enzymes including methane monooxygenase which are unique to this group of bacteria.
U.S. Pat. No. 5,326,703 to Hazen et al. discloses another in-situ method for biodegrading contaminants such as TCE.
U.S. Pat. No. 5,441,887 to Hanson et al. discloses an ex-situ method for biodegrading halogenated hydrocarbons by soluble methane monooxygenase. In the examples of this patent, methane is used as the food source for the methanotrophic bacteria.
U.S. Pat. No. 4,713,343 to Wilson Jr. et al. discloses a method for to biodegrading halogenated hydrocarbons such as TCE. The method may be performed either in-situ or ex-situ, and uses microorganisms such as methanotrophic bacteria.
U.S. Pat. No. 5,316,940 to Georgiou et al. discloses an ex-situ packed bed bioreactor utilizing a specific mutant methanotrophic bacteria to biodegrade TCE. Methane or methanol is used as the energy source.
U.S. Pat. No. 5,342,769 to Hunter et al. discloses an ex-situ bioremediation method for removing contaminants such as TCE from groundwater. A specific natural methanogenic bacteria is used in the process, along with methane as the food source.
Each of the above-noted patents is incorporated herein by reference.
Despite these bioremediation efforts, a need still exists for the effective degradation of pollutants such as chlorinated aliphatic hydrocarbons. The present invention has been developed in view of the foregoing, and to remedy other deficiencies of the prior art.
SUMMARY OF THE INVENTION
In accordance with the present invention, butane-utilizing organisms are used to degrade pollutants such as chlorinated aliphatic hydrocarbons. Degradation may occur cometabolically or by direct metabolism The butane-utilizing organisms of the present invention may be used for in-situ or ex-situ bioremediation of chlorinated hydrocarbon contaminants contained in air, soil and groundwater waste streams. In addition, salt- and acid-tolerant butane-utilizing bacteria may be used to restore saline and low pH groundwater systems impacted by chlorinated hydrocarbon contamination.
An object of the present invention is to provide an improved method of degrading hydrocarbon pollutants.
Another object of the present invention is to provide a bioremediation method of degrading TCE which utilizes bacteria demonstrating low TCE toxicity.
Another object of the present invention is to provide a method of degrading chlorinated aliphatic hydrocarbons with butane-utilizing bacteria by a cometabolic process.
Another object of the present invention is to provide a method of degrading chlorinated aliphatic hydrocarbons with butane-utilizing bacteria capable of directly metabolizing the hydrocarbon pollutants.
Another object of the present invention is to provide a method of degrading a hydrocarbon pollutant by treating the pollutant with butane-utilizing bacteria in the presence of oxygen for a sufficient time for the butane-utilizing bacteria to degrade the hydrocarbon pollutant.
Another object of the present invention is to provide a method of decontaminating water by treating the water with butane-utilizing bacteria to reduce or eliminate hydrocarbon pollutants contained in the water.
Another object of the present invention is to provide an ex-situ bioremediation apparatus that uses butane-utilizing bacteria and can be easily transported to various bioremediation sites.
These and other objects of the present invention will become more apparent from the following description.
REFERENCES:
patent: 4713343 (1987-12-01), Wilson, Jr. et al.
patent: 5037551 (1991-08-01), Barkley et al.
patent: 5057221 (1991-10-01), Bryant et al.
patent: 5316940 (1994-05-01), Georgiou et al.
patent: 5326703 (1994-07-01), Hazen et al.
patent: 5342769 (1994-08-01), Hunter et al.
patent: 5384048 (1995-01-01), Hazen et al.
patent: 5441887 (1995-08-01), Hanson et al.
patent: 5814514 (1998-09-01), Steffan et al.
Fogel et al., Biodegradation of Chlorinated Ethenes by a Methane-Utilizing Mixed Culture,Applied and Environmental Microbiology,vol. 51, No. 4, pp. 720-724 (Apr. 1986).
Wackett et al., Survey of Microbial Oxygenases: Trichloroethylene Degradation by the Propane-Oxid
Eckert Seamans Cherin & Mellott , LLC
Global BioSciences, Inc.
Towner Alan G.
Upton Christopher
LandOfFree
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