USOO6143534A United States Patent (19) 11 Patent Number: 6,143,534 Menger et al. (45) Date of Patent: Nov. 7, 2000 54) MICROBIAL PROCESS FOR PRODUCING “The Digestive System”, Ch. Noirot & C. Noirot-Timothee, METHANE FROM COAL p. 49-87. 75 Inventors: William M. Menger; Ernest E. Kern, “Food and Feeding Habits of Termites”, T.G. Wood, Pro both of Houston, Tex.; O. C. Karkalits, duction Ecology of Ants and Termites, pp. 55-58 (1978). Lake Charles, La., Donald L. Wise, "Feeding Relationships and Radioisotope Techniques', Belmont, Mass.; Alfred P. Leuschner; Elizabeth A. McMahan, Biology of Termites, vol. 1, pp. David Odelson, both of Cambridge, 387–406 (1969). Mass.; Hans E. Grethlein, Lansing, Mich. Lee, K. E., “Termites and Soils”, p. 128-145 (1971). Condensed Chemical Dictionary, p. 516, 661, 1974. 73 Assignee: Reliant Energy Incorporated, French et al, Mater Org (Berl) 10(4), 1975. p. 281–288. Houston, TeX. Lee et al., Curr. Microbiol. 15(6), p. 337-342, 1987. 21 Appl. No.: 07/814,078 O'Brien et al, Aust J. Biol. Sci, 35, p. 239-262, 1982. 22 Filed: Dec. 24, 1991 Odelson et al., Appl. Environ. Microbiol. 49(3) p. 614-621, 1985. Related U.S. Application Data Healy et al., App. Envoir. Microbiol., Jul., 1979, Vol. 38, pp. 63 Continuation of application No. 07/686,271, Apr. 15, 1991, 84-89. abandoned, which is a continuation of application No. Colberg et al., App. Envir. Microbiol, 49(2), Feb. 1985, pp. 07/156,532, Feb. 16, 1988, abandoned, which is a continu ation-in-part of application No. 06/693,028, Jan. 22, 1985, 345-349. Pat. No. 4,826,769, and a continuation-in-part of application Cohen et al, App. Envir. Microbiol. 44(1), Jul. 1982, pp. No. 06/816,289, Jan. 6, 1986, Pat. No. 4,845,034. 23-27. (51) Int. Cl. .................................................. C12P 5/02 Benner et al. App. Envir. Microbiol. 47(5), May 1984, pp. 52 U.S. Cl. ....................... 435/167; 435/252.4; 210/603; 998-1004. 48/210 58 Field of Search ................................. 435/167, 252.4; Benner et al, App. Enivr. Microbiol. 50(4), Oct. 1985, pp. 210/603; 48/210, DIG. 6 971-976. 56) References Cited Primary Examiner Irene Marx U.S. PATENT DOCUMENTS Attorney, Agent, or Firm-Bracewell & Patterson, L.L.P. 3,540,983 11/1970 Rose et al. .............................. 435/255 57 ABSTRACT 3,640,846 2/1972 Johnson ............... ... 210/603 3,826,308 7/1974 Compere-Whitney ... ... 435/166 X Lignite is treated with ligninase Source to enhance its 4,187,148 2/1980 Reijoner ............... ... 435/167 X reactivity. In one embodiment, lignite is gasified in a Sub 4,356,269 10/1982 Thomsen et al. ....................... 435/316 terranean reactor by Simultaneous digestion by anaerobic 4,358,537 11/1982 Chynoweth ......................... 435/167 X ligninase producers, Such as termite microflora, and acid 5,670,345 9/1997 Srivastava et al.. formers and methanogens. In another embodiment, the lig nite is treated with ligninase prior to digestion by the acid OTHER PUBLICATIONS formers and methanogens. If desired, the lignite may be “Alkaline Hydrolysis Transformation of Coal', Electric pretreated by alkaline hydrolysis. Power Research Institute Report EPRI AP–4585, Research Project 2655-2 (May 1986). 9 Claims, 8 Drawing Sheets U.S. Patent Nov. 7, 2000 Sheet 1 of 8 6,143,534 STEAM MICROBIAL/ENZYME 12 NOCULANT CRUSHED COAL NUTRENTS ALKAL fC) MAKE-UP WATER O2 PROTEIN 16 SLUDGE BSE 34 CH4, CO2 OTHER GASES HCW U.S. Patent Nov. 7, 2000 Sheet 2 of 8 6,143,534 MICROBAL/ENZYME |NOCULANT NUTRENTS MAKE-UP H2O PROTEIN BROTH 2 N. SEC LE /O2 2 SLUDGE DISPOSAL CRUSHED /O4 RECYCLE H2O COAL CH CO 4. 2 SXYYYYYXyyyyyyyyyyyyyyyyyyyyyy VX3. yyyyyyyyyyyyyY1A SN 3. x S 2 2 2 S SS U.S. Patent Nov. 7, 2000 Sheet 3 of 8 6,143,534 MICROBAL/ENZYME |NOCULANT NUTRIENTS CN, P) SLURRY MILD ALKAL MIXER PRETREATER MAKE-UP ALKAL H2O 15O PROTEIN RECOVERY RECYCLEL SLUDGE DISPOSAL 5'-T-lySTEAM CRUSHED RECYCLE H2O COAL O O GAS -- A-V -F /-y O VXYXXXXXXXXXXXXXXX % U.S. Patent Nov. 7, 2000 Sheet 4 of 8 6,143,534 MICROBAL. NOCULANT SLURRY PLUG - FLOW NUTRENTS (N, P) MIXER ENZYME REACTOR CPACKING SUPPORTED) MAKE-UP BROTH H2O 2O2 2O4 2 N 1 N RECYCLE F H2O 2OO X 2O6 SLUDGE RECYCLE H2O CH4, CO2 SESHED X-ke) 4S L5/-v He TRACE GASES SK WXXXXXYYXXXXXXVXXXX XXXXXXXXXXXXXXXXXXXXXXXX C N ASKW& ----------- - - |- r- . ---. I U.S. Patent Nov. 7, 2000 Sheet 5 of 8 6,143,534 NOCULUM NUTRIENTS (NP) PACKED BED SLURRY ENZYME MIXER SEFEAERMLD ALKAL REACTOR RECYCLE ALKAL 3O4 LIQUID MAKE-UP He O - ra H2O 2 3.O2 soo CRUSHED 6S/STEAM 1316 X SLUDGE COAL s ^ A. O GAS - S ?y WXXXXXXXXXXXXXXX KXXV S 3/O Ss 3. S S &SS s S. SS &&&&&KX&& AW S ... - - - - - - ... --- - - - - - T T U.S. Patent Nov. 7, 2000 Sheet 6 of 8 6,143,534 MICROBAL NO CULANT NP NUTRIENTS PROTEIN SLUDGE ORGANIC SOLUTION GAS 42 58 w y in R *va "VVAYYXXXXVI K (AYX A3 -56RS S. 48V. K.K %X&&&. &&&&&SX&&. l ----|-- l - - - y - it — ------ - - - - ap III. f U.S. Patent Nov. 7, 2000 Sheet 7 of 8 6,143,534 F/G, 8 U.S. Patent Nov. 7, 2000 Sheet 8 of 8 6,143,534 25OO o CONTROL + RAW LIGNTE - TOC - - - CUM, CH4 2OOO 5OO O O O TIME (DAYS) F/G, 9 6,143,534 1 2 MICROBAL PROCESS FOR PRODUCING ing Suitably economic reactors for the conversion of various METHANE FROM COAL substrates into methane. For example, U.S. Pat. No. 4,356, 269 describes a Semisubmerged insulated apparatus which CROSS-REFERENCE TO RELATED has a preheating chamber provided with a heating device, a APPLICATION: gas processing chamber in which the microorganisms are grown, and a storage chamber for spent manure. This is a continuation of co-pending application Ser. No. The anaerobic digestion of a Substrate is typically a 686,271 filed on Apr. 15. 1991, now abandoned, which is is three-Step process in which complex organic materials are a continuation application of Ser. No. 156,532 filed on Feb. converted to the end products of methane and carbon 16, 1988 now abandoned, which is is a continuation-in-part dioxide. In the initial Steps, complex organic molecules are of U.S. patent application Ser. No. 693,028 filed Jan. 22, converted into Substances Such as propionate, butyrate, 1985 now U.S. Pat No. 4,828,769, and U.S. patent applica Valerate, lactate, formate and ethanol, and eventually into tion Ser. No. 816,289 filed Jan. 6, 1986 now U.S. Pat. No. acetate. The organisms responsible for this conversion are 4,845,034, both copending herewith. collectively termed acid formers and may be either anaero FIELD OF INVENTION 15 bic or facultative in nature. The final Step, conversion of acetate to methane and carbon dioxide, is performed by This invention relates to the biochemical reaction of a organisms collectively termed methane formers, or Substrate with microorganisms to produce combustible methanogens, which are strictly anaerobic. Because the gases. More particularly, this invention relates to producing methanogens generally grow more slowly than do the acid fuel gas from lignin Substrates Such as coal using ligninase formers, the final Step of the process is generally considered producing, acid forming and methanogenic microorganisms. the rate limiting Step. Generally, conversion of a complex organic Substrate yields a gas which is typically fifty to BACKGROUND OF THE INVENTION Seventy percent methane and thirty to fifty percent carbon Although the utilization of coal to produce mechanical dioxide. and electrical energy through combustion provides a funda 25 In the biogasification of coal and other Substrates con mental contribution to our energy needs, this technology taining macromolecular Substances, however, the Substrate Suffers certain limitations. These limitations arise through is not readily amenable to digestion by acid formers and concern about the environmental effects of combustion, methanogens. Acid formers are generally unable to convert through inefficiencies and excessive costs involved in trans the high molecular weight Substances, especially those con porting and burning certain coals, and because the universal taining fused aromatics Such as coal, for example, into the technique of Steam generation imposes a localized utiliza lower molecular weight acids required by the methanogens. tion of Steam at the time of generation. These considerations Thus the development of technology for the biogasification have Stimulated much effort to develop processes for the of coal and other macromolecular Substances requires an conversion of coals into fuel gas, a Storable, readily trans acceptable means of treating Such Substrates prior to the ported form of fuel. Gasification of coal can overcome or 35 more familiar digestion with acid formers and methanogens mitigate many of the objections raised, but current gasifi used in the gasification of other less complex Substrates. cation technology is, in turn, not free of problems. Para It has been reported to Subject coal to alkaline hydrolysis mount is the enormous capital cost projected for conven in order to break down the physical and chemical Structure tional coal gasification plants. This cost makes the product of the coal to make it more accessible to microbial action, for gas expensive. The expense is a reflection of the cost of 40 example, to upgrade the coal by biological removal of massive high temperature chemical reaction vessels capable nitrogen and Sulfur contaminants. For instance, it was of withstanding high pressures and the cost of catalytic reported that milled Subbituminous coal was Subjected to reactorS Susceptible to contaminant poisoning. Accordingly, alkaline hydrolysis at 200–300° C.