Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving viable micro-organism
Reexamination Certificate
1998-10-15
2001-09-25
Marx, Irene (Department: 1651)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving viable micro-organism
C435S262500, C435S245000, C435S252100, C435S244000
Reexamination Certificate
active
06294351
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to biochemical transformation of solid carbonaceous material by a process of depolymerizing, desulfurizing and demineralizing using modified strains of thermophilic bacteria. More specifically, the present invention provides a process of treating an aqueous slurry of solid carbonaceous material, such as coal, with a culture of thermophilic bacteria which have been modified through challenge growth processes to be suitable for microbially enhanced oil recovery. Some of these bacteria were further adapted to grow on coal under challenged growth conditions and then utilized for biochemical transformation of solid carbonaceous material.
Coal is a solid carbonaceous material which is one of the most abundant fossil energy resources accessible to mankind. In terms of environmental protection, coal combustion is associated with significant problems, such as sulfur and nitrogen oxides emission, and the production of toxic metal containing ash. However, coal can be treated prior to combustion in a manner which reduces sulfur and ash contents. The treated product becomes a more suitable feedstock for combustion, liquefaction and gasification processes.
Sulfur appears in coal in three basic forms: as sulfates, pyrites and organic sulfur. Of the three forms, sulfates are the least significant, comprising less than 0.5 weight percent of coal. Pyritic and organic sulfur, however, may each constitute as much as 3.5 weight percent of the coal or from 40% weight to 60% weight of the total sulfur content, respectively. Thus, it is apparent that removal of an effective portion of inorganic and organic sulfur content prior to coal combustion could substantially reduce the emission of sulfur oxides into the atmosphere.
By organic sulfur is meant sulfur which is chemically bound within the coal matrix. Organic sulfur is present in four major forms. These are mercaptans or thiols, sulfides, disulfides and aromatic ring sulfur as exemplified by the thiophene system.
In the past, attempts have been made to alleviate the environmental problems associated with the combustion of coal. A number of processes for the treatment of coal ranging from ash and pyrite reduction to organic sulfur removal and coal liquefaction have been reported. These processes include numerous physical and mechanical techniques such as heavy media separation, elective agglomeration, flotation, jigging, magnetic, separation, leaching and hydrosulfurization. Problems associated with these developing technologies include reproductivity, slow kinetics and scale-up difficulties.
The removal of inorganic sulfur from pyrite is relatively easily accomplished by treatment with dilute nitric acid. The removal of organic sulfur, however, has not met with the same success. In recent years in order to obtain cleaner coal, coal has been subjected to biochemical processes wherein inorganic sulfur and minerals are removed through the action of several microorganisms belonging to the Thiobacillus, Sulfolobus and Pseudomonas Clostridium species. For example, U.S. Pat. No. 4,632,906 to Kopacz discloses a process for biodesulfurization by contacting carbonaceous material with Bacillus Sulfasportate of ATCC No. 39909. A mutant of the family Bacillaceae, this microorganism grows in a range between 15° C. to 30° C. and is not a thermophile. The background of the invention of the '906 disclosure describes Sulfolobus Acidocaldarius, a thermophilic sulfur and iron oxidizing microorganism which is a facultative autotroph. This organism has been used for removal of primarily pyritic sulfur from coal.
U.S. Pat. No. 4,206,288 to Detz et al. discloses a process for removal of pyritic sulfur from coal by microbial desulfurization of coal slurry with iron and sulfur oxidizing microorganisms selected from the
Thiobacillus ferooxidans
species. The microorganisms described in the '288 disclosure must be kept in a range of about 10° C. to 35° C. and are not thermophilic as required by the process of the present invention. Thus, they cannot be used at elevated temperatures.
U.S. Pat. No. 4,562,156 to Isbister et al. describes a mutant microorganism Pseudomonas sp. CB1 (ATCC 39381) used in the removal of organic sulfur compounds from carbonaceous materials including coal. In addition, the '156 disclosure describes other genera of microorganisms such as Arthrobacter and Acinetobacter used for microbiological treatment of petroleum and coal. These microorganisms are not thermophiles because they cannot grow at 41° C.
Generally, the microorganisms described in the above disclosures are not resistant to challenged environments, namely those including elevated temperatures, pressures, low pH, high levels of salinity and toxic metals. Frequently, it has been found more economical to process coal under elevated temperatures and pressures. Moreover, many types of coal have high toxic metal content which can kill many strains of bacteria even those which have been previously environmentally challenged.
Accordingly, there is a need in the art of biochemical transformation of solid carbonaceous materials for microorganisms which can depolymerize, desulfurize and/or demineralize solid carbonaceous material such as coal under environmentally challenged conditions.
It is therefore, an object of the present invention to provide modified thermophilic bacteria which are useful for the biochemical transformation of coals in a challenged environment.
SUMMARY OF THE INVENTION
The present invention, which addresses the needs of the prior art, provides a method of biochemically transforming complex macromolecular compounds found in solid carbonaceous materials, such as coal. More specifically, coal is treated with a biological treatment medium including strains of bacteria which have been metabolically weaned under challenged conditions to metabolize the complex macromolecular compounds found in coal thus providing a solid carbonaceous material which has been depolymerized, desulfurized and/or demineralized.
The biological treatment medium is prepared by nutritionally stressing thermophilic microorganisms to metabolize initially a non-solid carbonaceous material, such as crude oil at a desired temperature, pressure, pH and salinity.
The strains which survive in the presence of crude oil are then subjected to further challenge by selection under more extreme conditions. The selection process proceeds by the removal of the more easily metabolizable carbon sources while stepwise increasing the temperature, pressure, salinity and pH. The resulting modified or metabolically weaned thermophilic bacteria exhibit different chemical and biochemical properties than the thermophilic bacterial strains initially isolated from unique geothermal locations in the South Pacific and North America. Microorganisms which survive essentially on oil under extreme conditions of temperature, pressure, salinity and pH include Achromobacter sp. BNL-4-23 (ATCC 55021),
Sulfalobus solfataricus
BNL-TH-29 (ATCC 55022),
Sulfalobus solfataricus
BNL-TH-31 (ATCC 55023),
Sulfolobus acidocaldarius
BNL-TH-1 (ATCC 35091), Pseudomonas sp. BNL-4-24 (ATCC 55024),
Leptospirillum ferrooxidans
BNL-5-30 (ATCC 53992),
Leptospirillum ferrooxidans
BNL-5-31 (ATCC 53993),
Acinetobacter calcoaceticus
BNL4-21 (ATCC 53996), Arthrobacter sp. BNL4-22 (ATCC 53997).
The microorganisms which can feed on essentially crude oil are then isolated and are further nutritionally stressed to metabolize complex macromolecular compounds found in solid carbonaceous material such as coal. The nutritional stressing on a coal substrate is also conducted stepwise under challenged growth conditions including a temperature range from about 40° C. to about 85° C. reaction range pressure range from about ambient pressure to about 2500 p.s.i., a pH range from about 2 to about 10, a salinity range from about 1.5 weight % to about 35 weight % and a toxic metal concentration from about 0.01 weight % to about 10 weight %.
Microorganisms which can survive essentially on solid carbonaceo
Lin Mow S.
Premuzic Eugene T.
Bogosian Margaret C.
Brookhaven Science Associates LLC
Marx Irene
LandOfFree
Biochemical transformation of solid carbonaceous material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Biochemical transformation of solid carbonaceous material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biochemical transformation of solid carbonaceous material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2446877