Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Destruction of hazardous or toxic waste
Reexamination Certificate
2000-01-28
2002-06-11
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Destruction of hazardous or toxic waste
C435S262000, C210S610000, C210S747300
Reexamination Certificate
active
06403364
ABSTRACT:
FIELD OF THE INVENTION
Chemical contamination of the environment associated with many different types of industrial activities conducted over the last two centuries is a well documented, world-wide problem. 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 (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. Hence, there has been and continues to be a great need for improved methods for the remediation of contamination in the environment.
This invention discloses the formulation, manufacture and use of advanced solid-media chemical compositions designed and intended to enhance the biologically mediated removal ad of recalcitrant contaminants from hazardous and industrial wastes, and contaminated environmental media such as soils, sediments, sludges, surface waters, and the like. In particular, this invention provides improved means for the clean-up of contaminated sediments present in environmental settings which are difficult (if not impossible) to treat, such as the contaminated sediments present beneath streams, rivers, lakes, ponds, oceans, estuaries, bays, harbors, canals, lagoons and the like.
DESCRIPTION OF PRIOR ART
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. One of the most common categories of physical environmental remediation technologies for the treatment of contaminated sediments located beneath rivers, streams, lakes, and the like is dredging followed by their disposal in a landfill, which can pose a potential long-term risk to the environment. Each of the 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 pesticide's 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 within both the scientific and engineering communities. Recent trends in the art and literature acknowledge a growing understanding of the use of anaerobic biological processes in the treatment of many different types of contaminants that are otherwise recalcitrant under aerobic conditions. In particular, trends in the art reflect a growing understanding of the need and importance of achieving and maintaining anaerobic conditions and other factors which favor the biologically mediated reduction, biodegradation, transformation and/or detoxification of recalcitrant organic and inorganic contaminants in the environment.
The current understanding reflected by the art is that the recalcitrant nature of many halogenated organic contaminants, polynuclear aromatic hydrocarbons (PAHs), other heavy (i.e., high-molecular weight) hydrocarbons, and the like is related to the hydrophobic nature and extremely low solubilities of the contaminants. Consequently, the “bioavailability” of these contaminants, i.e., their availability to biological degradation processes mediated by microorganisms, is extremely limited under most environmental conditions. The prior art describes the use of chemical methods (e.g., Szejtli, et al., U.S. Pat. No. 5,425,881) and thermal methods (e g., Rothmel, et al., U.S. Pat. No. 5,567,324) to increase bioavailability. For a number of chemically complex hydrophobic chlorinated organic compounds, such as pesticides and PCBs, the prior art has suggested that the higher molecular weight (i.e., more chlorinated) compounds can not be practically biodegraded and thus bioremediation techniques have been all but abandoned with respect to the treatment of such compounds in the environment. For example, through laboratory and pilot-scale experiments directed at the investigation of bioremediation processes on Hudson River sediments contaminated with PCBs, General Electric (GE) researchers determined that the PCBs associated with the sediments consiste
Beisner William H.
Geovation Consultants Inc.
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