Chemistry: molecular biology and microbiology – Process of utilizing an enzyme or micro-organism to destroy... – Treating animal or plant material or micro-organism
Reexamination Certificate
2000-03-31
2002-05-14
Beisner, William H. (Department: 1744)
Chemistry: molecular biology and microbiology
Process of utilizing an enzyme or micro-organism to destroy...
Treating animal or plant material or micro-organism
C435S262000, C435S262500
Reexamination Certificate
active
06387691
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to fungal inocula and their use in degrading and bioremediating wood treated with chemical preservatives. More specifically, this invention discloses and claims a fungal inoculum, the method of its preparation, and its use in degrading and bioremediating wood treated with ammoniacal copper quat.
Wood used in the construction of today's decks, docks and buildings, or as utility poles and railroad ties, is typically treated with a chemical preservative to prevent deterioration and extend service life. The chemical preservative used will generally depend upon the intended use of the wood and often includes chemicals such as ammoniacal copper quat (ACQ), chromated copper arsenate (CCA), creosote and pentachlorophenol.
ACQ is a waterborne preservative generally used to treat wood employed as lumber, timber, posts, buildings, foundations, poles or pilings in non-salt water environments. There are basically two types of ACQ preservatives, Type B and Type D, which are composed of a combination of copper oxide, quat as didecyldimethylammonium chloride, and either ammoniacal or amine, respectively. One of the benefits of ACQ is that neither type contains arsenic or chromium and its application provides a clean paintable surface.
Once the ACQ treated wood reaches the end of its useful life, it will likely be collected and stored at landfills or other facilities such that large quantities of waste wood will accumulate at an alarming rate. The collection and storage of such large quantities of waste wood in a single location creates an environment where the contamination of the surrounding soil and groundwater by toxic, environmentally-persistent chemicals is a likely result.
Contamination of soils and groundwater with toxic, environmentally-persistent chemicals is a serious problem. Toxic, environmentally-persistent chemicals are those that are resistant to degradation in the natural environment. As such, these chemicals pose a multi-faceted problem in that as they persist and accumulate in the environment, their toxicity, including in many instances, proven carcinogenicity, presents substantial health risks to both animals and human beings. Environmental contamination from ACQ-treated wood is a specific concern in view of the large volume of ACQ-treated waste wood expected to be removed from service and disposed of in the near future.
The prior art is replete with methods for degrading hazardous chemicals. However, this prior art is generally, and specifically, directed towards halogenated aromatic compounds. Suggested treatment strategies include incineration of the waste, removal and isolation of the contaminated materials, and degradation of the pollutant by bacteria.
All of these strategies suffer from serious deficiencies. Incineration is extremely expensive due to the required energy expense and the necessity of moving the contaminated material to remote locations. Incineration is also impractical because of the large quantities of waste which needs processing. Removal and isolation of the contaminated material is also expensive and does nothing to effect a long-term solution. Degradation of the chemicals using bacteria has also proven ineffective due to the bacteria's specificity for particular chemicals and its sensitivity to the toxic chemicals and environmental conditions.
U.S. Pat. No. 5,476,788 employs another strategy which utilizes an inoculum containing the lignin-degrading fungal species
Phanerochaete chrysosporium, Phanerochaete sordida
, or
Trametes hirsuta
to remediate solid materials, such as soils, sludge, sediments, and debris (e.g., woods), contaminated with pentachlorophenol. The inoculum contains one or more of the fungal strains and a lignocellulosic substrate, i.e., sawdust. In its use, the inoculum is combined with the pentachlorophenol-contaminated material and the entire mixture is aerated and hydrated until the inoculum metabolizes the pentachlorophenol to a less toxic product. Typically, this less toxic product includes pentachloroanisole.
Although the above-identified bioremediation strategy provides a useful means of reducing the pentachlorophenol content in various solid materials, it does not address the concerns associated with other wood preservatives currently used in the world today. Moreover, it fails to provide a working strategy for other types of fungal strains which require a more specific and unique environment to effectively remediate chemical preservatives such as CCA, ACQ, creosote, or pentachlorophenol or degrade wood treated with these chemicals.
BRIEF SUMMARY OF THE INVENTION
The present invention is summarized in that it discloses a fungal inoculum, the method of its preparation, and its use in degrading and/or bioremediating wood treated with the chemical preservative ammoniacal copper quat (ACQ).
The disclosed fungal inoculum generally comprises of at least one ACQ-tolerant fungus, a lignocellulosic substrate, and a nutrient supplement. The ACQ-tolerant fungal strains are preferably selected from the group consisting of
Meruliporia incrassata
(TFFH-294),
Antrodia radiculosa
(MJL-630), and
Antrodia radiculosa
(FP-90949-T). The lignocellulosic substrate is preferably sawdust or wood chips. Other feasible substrates are rice straw, corn stalks, and wheat straw. The nutrient supplement is preferably selected from the group consisting of corn steep liquor, cornmeal and wheatbran.
In one preferred embodiment, the fungal inoculum is prepared by first growing the ACQ-tolerant fungus in dark, aerobic conditions, having a relative humidity and a temperature sufficient to support fungal growth. The fungas is then combined with a homogenous matrix comprising sterile water, the nutrient supplement, and the sterilized lignocellulosic substrate, to form the fungal inoculum. The fungal inoculum is then allowed to mature by exposing the mixture to dark, aerobic conditions, at a relative humidity and in a temperature range sufficient to allow the fungas to reach a confluent growth.
Waste wood containing ACQ is remediated or degraded by inoculating the waste wood in the fungal inoculum. To inoculate the waste wood, the fungal inoculum is first spread over the waste wood until all of the waste wood is covered. The waste wood and fungal inoculum mixture is then aerated and hydrated for a time and under conditions sufficient to allow the inoculum to at least partially remediate the ACQ and/or degrade the waste wood to a desired degradation product. In some instances, the degradation product may be capable of reuse in paper or wood composites, or simply have a reduced volume.
It is an object of the present invention to provide a method for bioremediating and/or degrading chemically treated waste wood to achieve a product having a reduced volume and/or the capacity to be reused as a wood fiber resource.
It is another object of the present invention to provide a fungal inoculum, and a method for preparing said fungal inoculum, which is useful in bioremediating and/or degrading chemically treated waste wood.
It is another object of the present invention to provide a fungal inoculum, and a method for using the fungal inoculum, to degrade and at least partially remediate waste wood chemically treated with ACQ.
One advantage of the present invention is that the ACQ-tolerant fungi utilized do not require genetic alteration to specifically grow in the presence of ACQ. Thus, the introduction of the fungi into the environment provides no new, non-naturally occurring organisms.
Another advantage is that the preparation and use of the fungal inoculum is fairly simple and utilizes agricultural waste products and waste products from saw mills and urban chipping. These products have the additional advantage of providing a quick and low cost food source for the fungus, while having the added effect of stimulating rapid and extensive fungal growth, as well as providing a readily storable and transportable solid matrix.
Another advantage is that the inoculum and its method of use are particularly
Ferge Leslie A.
Illman Barbara L.
Yang Vina W.
Beisner William H.
Fads John D.
Silverstein Mitchell
Stockhausen Janet I.
The United States of America as represented by the Secretary of
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