Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Destruction of hazardous or toxic waste
Reexamination Certificate
1999-11-15
2002-08-13
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Destruction of hazardous or toxic waste
C435S262500, C423SDIG001, C210S610000, C588S253000, C405S129950
Reexamination Certificate
active
06432693
ABSTRACT:
BACKGROUND
1. Field of the Invention
This invention discloses the formulation and use of advanced solid-media chemical compositions designed and intended to enhance the removal of halogenated organic contaminants and the oxidized forms of inorganic contaminants from industrial wastes, soils, sediments, sludges, ground waters, surface waters, and the like. In particular, this invention provides an improved means of promoting the anaerobic, biologically mediated degradation, transformation and/or detoxification of a broad range of recalcitrant and/or hydrophobic halogenated organic and inorganic contaminants in the environment, including, but not limited to, organochlorine pesticides such as DDT and toxaphene, arsenic and/or arsenate-based pesticides, polychlorinated biphenyls (PCBs), dioxins, halogenated organic solvents such as perchloroethylene, trichloroethylene, trichloroethane and freon, and toxic inorganic contaminants such as cyanide, hexavalent chromium and the oxidized forms of other toxic heavy metals. This invention provides improved means for (i) promoting the solid-phase extraction of recalcitrant, hydrophobic contaminants from contaminated media and enhancing the bioavailability and biogeochemical reactivity of such contaminants, (ii) creating, enhancing and maintaining both strongly anaerobic and highly reducing conditions favorable to the biodegradation, dehalogenation, transformation and/or detoxification of these contaminants by naturally occurring microorganisms, (iii) providing a source of complex anaerobic electron acceptors, and nutrients to promote the growth of these contaminant-degrading microorganisms, and (iv) providing sources of inoculum of different types of naturally occurring microorganisms which act to directly undertake or indirectly promote the biodegradation, dehalogenation, transformation, and/or detoxification of these contaminants. This invention specifically reveals a cost-effective and relatively simple to use improved inorganic composition, and methods for its use thereof, that is designed to promote one or more of the aforementioned processes in the treatment of environmental contamination.
2. Description of Prior Art
Soil and ground-water pollution caused by chemical contaminants released into the environment is a well documented, world-wide problem. Such chemical contamination is associated with many different types of industrial activities conducted over the last two centuries. Common environmental contaminants include several different types and forms of petroleum hydrocarbons, halogenated organic compounds including solvents (e.g., tetra- and trichloroethene, methylene chloride), pesticides (e.g., DDT and toxaphene), polychlorinated biphenyls (i.e., PCBs) and heavy metals and other inorganic contaminants such as cyanides. The available toxicological data indicates that many of these contaminants, (in particular many of the halogenated organic compounds), are either carcinogenic or potentially carcinogenic to both man and animals. In addition, the available environmental and ecological data have shown that many of these contaminants tend to persist in the environment for long time periods and, consequently, they tend to accumulate in the tissues of biological organisms up the food chain. The long-term stability and extremely slow degradation of many such environmental contaminants presents a substantial, long-term hazard to human health and the environment throughout the industrialized world.
Many of the so-called conventional methods for the remediation or clean-up of chemically contaminated wastes, waters, soils and sediments have generally involved either the physical removal of the contaminated media or the simple mass transfer of the contaminants from one media (e.g., soil) to another (e.g., air). In general, such physical-treatment technologies do not involve the chemically and/or biologically mediated breakdown, transformation or detoxification of the contaminants. Two of the most common categories of physical environmental remediation technologies are the excavation of contaminated soils and the pumping and subsequent treatment of contaminated ground water. The excavation of contaminated soils is often followed by their disposal in a landfill, which can pose a potential long-term risk to the environment. Many ground-water pump-and-treat processes involve the simple mass-transfer or “stripping” of the contaminants from the water into the air. Another common physical-treatment method involves the use of granular activated carbon (GAC) reactors to treat chemically contaminated waters. When contaminated water is passed through a GAC reactor, the contaminants are physically adsorbed onto the carbon particles, thereby producing another contaminated media which requires subsequent disposal and/or treatment. Each of these physical-treatment technologies share the same disadvantage—i.e., they do not reduce the actual amount or toxicity of the chemical contaminants, but rather they simply move the contamination from one place to another or from one media to another.
Another well-known physical treatment process which involves the thermal treatment or incineration of the contaminated materials can be an effective albeit expensive means of breaking down the molecular structure of the contaminants into non-hazardous products. For example, high-temperature incineration is known to be effective for the treatment of materials containing pesticides and PCBS. Thermal-treatment methods require the use of sophisticated and operation-and-maintenance-intensive equipment, the costs of which are passed on to industry in the form of expensive unit costs for soil treatment. In addition, because thermal-treatment processes are rarely, if ever, one-hundred-percent effective in the destruction of the contaminants, they can produce atmospheric emissions of contaminants or the toxic by-products of contaminants. For example, the incomplete incineration of PCBs can produce dioxins, which in turn are significantly more toxic than their “parent” PCB compounds.
A third category of environmental-remediation treatment technologies, bioremediation, involves the use of microorganisms to convert chemical compounds into innocuous or less harmful chemical compounds. Bioremediation technologies generally have lower costs associated with their use and implementation than do the competing physical technologies. Bioremediation technologies are also more adaptable to different types of contamination problems and variations in field conditions than are physical-treatment technologies.
The most promising bioremediation technologies provide the additional capability of treating contaminated media in-situ, i.e., in place, without the need for ground-water pumping or soil excavation. Current trends in bioremediation technology indicate that the most technically feasible and commercially successful bioremediation technologies are those which utilize indigenous or “native” contaminant-degrading bacteria (CDB), fungi and other microorganisms which are naturally present in the contaminated media. The presence of CDB in many different types of environments has been extensively reported in the scientific literature. There is an extensive body of prior art literature and patents concerning various means of using both aerobic and anaerobic CDB (as well as engineered or cultured bacteria) to biodegrade organic contaminants in water, soil and industrial wastes. For example, it has been reported that native Alcaligenes spp., Pseudomonas spp., and Enterobacter spp. can degrade a number of pesticides and polychlorinated biphenyls (Nadeau et al., 1994
, Applied and Environmental Microbiology
; Aislabie et al., 1997
, New Zealand Journal of Agricultural Research
; Galli et al., 1992
, Pseudomonas: Molecular Biology and Biotechnology
). Given the significant advantages of using native microorganisms versus the need to introduce cultured or engineered microorganisms, methods which involve the use of artificially introduced microorganisms (e.g., U.S. Pat. No. 5,932,472) are declining in favor
Geovation Technologies, Inc.
Redding David A.
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