Methods for microbial filtration of fluids
AssigneeThe Regents of the University of California
InventorsMargaret L. Carman, Kenneth J. Jackson, Richard B. Knapp, John P. Knezovich, Nilesh N. Shah, Robert T. Taylor
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Abstract
Novel methods for purifying contaminated subsurface groundwater are disclosed. The method is involves contacting the contaminated subsurface groundwater with methanotrophic or heterotrophic microorganisms which produce contaminant-degrading enzymes. The microorganisms are derived from surface cultures and are injected into the ground so as to act as a biofilter. The contaminants which may be treated include organic or metallic materials and radionuclides.
Claims43
A method for purifying subsurface groundwater to remove certain enzymatically degradable contaminants therefrom, comprising the sequential step of:
- (A) providing a microorganism capable of producing an enzyme which allows the intact resting-state cells to degrade the contaminants;
- (B) growing the microorganisms under conditions which increase the amount and intracellular longevity of the enzyme, to produce an enzyme-enriched intracellular enzyme longevity-enhanced microorganism composition;
- and
- (C) contacting the subsurface groundwater with the enzyme-enriched, intracellular enzyme longevity-enhanced microorganism composition in a resting state;
- wherein the microorganism composition having increased whole-cell contaminant-degrading activity is prepared by the process comprising:
- (a) providing a microorganism capable of producing an enzyme which allows the microorganism in a resting state to enzymatically degrade organic materials;
- (b) providing a cell culture medium by modifying Higgin's minimal nitrate salts medium by omitting CuSO.sub.4.5H.sub.2 O therefrom and adding approximately 2.times. FeSO.sub.4.7H.sub.2 O and approximately 2.times. NaNO.sub.3 thereto;
- (c) batch cultivating said microorganism in said cell culture medium in a stirred bioreactor at a pH in the range of about 6.8 to 7.2 in an atmosphere containing air, methane and CO.sub.2, to increase the amount of said enzyme produced by the microorganism;
- and
- (d) harvesting the enzyme-enriched microorganism composition provided in step (c).
A method for purifying subsurface groundwater to remove certain enzymatically degradable contaminants therefrom, comprising the sequential steps of:
- (A) providing a microorganism capable of producing an enzyme which allows the intact resting-state cells to degrade the contaminants;
- (B) growing the microorganisms under conditions which increase the amount and intracellular longevity of the enzyme, to produce an enzyme-enriched intracellular enzyme longevity-enhanced microorganism composition;
- and
- (C) contacting the subsurface groundwater with the enzyme-enriched, intracellular enzyme longevity-enhanced microorganism composition in a resting state;
- wherein the microorganism composition having increased whole-cell contaminant-degrading activity is prepared by the process comprising:
- (a) providing methanotrophic bacteria of the genus Methylosinus trichosporium Ob3b capable of producing soluble methane monooxygenase;
- (b) providing a cell culture medium by modifying Higgin's minimal nitrate salts medium by omitting CuSO.sub.4.5H.sub.2 O therefrom, adding approximately 2.times. FeSO.sub.4.7H.sub.2 O and approximately 2.times. NaNO.sub.3 thereto, raising the concentration of NaMoO.sub.4.2H.sub.2 O approximately 40-fold to about 16 micromolar, and including NiCl.sub.2 at a concentration of approximately 7.5 micromolar;
- (c) adding approximately 1.times. amounts of FeSO.sub.4.7H.sub.2 O and MgSO.sub.4.H.sub.2 O to the culture medium after about 80 to 100 hours of cell growth;
- (d) batch cultivating said microorganism in said cell culture medium in a stirred bioreactor at a pH in the range of about 6.8 to 7.2 at a temperature approximating 30.degree. C. under an approximately 3:1 v/v 10% CO.sub.2 -containing air:methane mixture, to increase the amount of said enzyme produced by the microorganism;
- (e) further growing the microorganisms until the microorganism has reached a resting state;
- and
- (f) harvesting the enzyme-enriched microorganism composition provided in step (e), whereby catalytically active, washed resting state cells are provided.
Dependencies are inferred from the claim text.