US 5,387,271 A · Biological system for degrading nitroaromatics in water and soils

Abstract

Novel methods for biodegrading nitroaromatic compounds present as contaminants in soil or water using microorganisms are disclosed. Water is treatable directly; dry soil is first converted into a fluid medium by addition of water. The preferred method comprises two stages, each employing microorganisms: a fermentative stage, followed by an anaerobic stage. The fermentative stage is rapid, wherein an inoculum of aerobic and/or facultative microorganisms ferments a carbohydrate added to the fluid medium, exhausting the oxygen in the fluid medium and thereby inhibiting oxidative polymerization of amino by-products of the nitroaromatics. In the subsequent anaerobic stage an inoculum of a mixed population of anaerobic microorganisms completes the mineralization of the contaminant nitroaromatics, using the remaining carbohydrate as a carbon and energy source. Preferably, the carbohydrate is a starch and the aerobic and/or facultative microorganisms are amylolytic, which cleave the starch at a moderate rate throughout both stages, ensuring a sustained supply of metabolizable carbohydrate. The microorganisms are preferably selected to be resistant to the types and concentrations of nitroaromatics present as contaminants.

Claims55

Dependent claims

A method for degrading nitroaromatic compounds present as contaminants in a fluid medium to reduce the concentrations of the nitroaromatic compounds in the fluid medium, the method comprising:

(a) adding to the fluid medium an inoculum of carbohydrate-fermentative microorganisms resistant to the types and respective concentrations of contaminant nitroaromatic compounds present in the fluid medium, wherein the carbohydrate-fermentative microorganisms are selected from the group consisting of aerobic and facultative microorganisms Comprising genera selected from the group consisting of Klebsiella, Enterobacter, Lactobacillus, Bacillus, Clostridium, and Pseudonomas, and mixtures thereof;
(b) adding to the fluid medium a carbohydrate fermentable by the carbohydrate-fermentative microorganisms;
(c) maintaining the fluid medium containing said carbohydrate-fermentative microorganisms and carbohydrate under conditions suitable for growth of said carbohydrate-fermentative microorganisms in the fluid medium, accompanied by fermentation by said microorganisms of a portion of said carbohydrate, thereby depleting the concentration of dissolved oxygen in the fluid medium, so as to render the fluid medium anaerobic;
(d) after the fluid medium has been rendered anaerobic, adding to the fluid medium an inoculum of anaerobic microorganisms capable of utilizing the carbohydrate as a carbon and energy source and degrading said nitroaromatic compounds, the anaerobic inoculum being a consortium comprising genera selected from the group consisting of Klebsiella, Enterobacter, Bacteroides, Fusobacterium, Desulfovibrio, Desulfuromonas, Clostridium, Desulfotomaculum, Sporosarcina, Lactobacillus, Bacillus, Clostridium, Pseudomonas, Veillonella, Acidaminococcus, Methanobacterium, Methoanococcus, and Archaeoglobus, and mixtures thereof;
and
(e) maintaining anaerobic conditions in the fluid medium for a time sufficient for the anaerobic microorganisms to degrade the contaminant nitroaromatic compounds.

3 more elements

A method for remediating a soil so as to degrade nitroaromatic compounds present as contaminants in the soil, the method comprising:

(a) adding water to the nitroaromatic-contaminated soil to form an aqueous slurry of the soil;
(b) adding to the slurry an inoculum of fermentative amylolytic microorganisms resistant to the nitroaromatic compounds and concentrations thereof present in the soil, wherein the fermentative amylolytic microorganisms are selected from the group consisting of aerobic and facultative amylolytic microorganisms comprising genera selected from the group consisting of Klebsiella, Enterobacter, Lactobacillus, Bacillus, Clostridium, and Pseudonomas, and mixtures thereof;
(c) adding to the slurry at least one type of starchy carbohydrate hydrolyzable to substituent sugars by said fermentative amylolytic microorganisms;
(d) maintaining the slurry containing said fermentative amylolytic microorganisms and starchy carbohydrate under conditions suitable for growth of said fermentative amylolytic microorganisms in the slurry, accompanied by hydrolysis of the starchy carbohydrate to constituent sugars and metabolism by said fermentative amylolytic microorganisms of a portion of said sugars, thereby rendering the slurry anaerobic;
(e) after the slurry has been rendered anaerobic, adding to the slurry an inoculum of anaerobic microorganisms capable of utilizing as a carbon and energy source said sugars formed in the slurry by the amylolytic microorganisms and capable of degrading said nitroaromatic compounds the anaerobic inoculum being a consortium comprising genera selected from the group consisting Of Klebsiella, Enterobacter, Bacteroides, Fusobacterium, Desulfovibrio, Desulfuromonas, Clostridium, Desulfotomaculum, Sporosarcina, Lactobacillus, Bacillus, Clostridium, Pseudomonas, Veillonella, Acidaminococcus, Methanobacterium, Methoanococcus, and Archaeoglobus, and mixtures thereof;
and
(f) maintaining anaerobic conditions in the slurry for a time sufficient for the anaerobic microorganisms to degrade the nitroaromatic compounds.

4 more elements

A method for treating a soil contaminated with aminoaromatic compounds so as to favor mineralization of the aminoaromatic compounds in the soil over oxidative polymerization of the aminoaromatic compounds, the method comprising:

(a) adding water to the nitroaromatic-contaminated soil to form an aqueous slurry of the soil;
(b) adding to the slurry an inoculum of fermentative amylolytic microorganisms resistant to the aminoaromatic compounds in the soil, where the fermentative amylolytic microorganisms are selected from the group consisting of aerobic and facultative amylolytic microorganisms comprising genera selected from the group consisting of Klebsiella, Enterobacter, Lactobacillus, Bacillus, Clostridium, and Pseudonomas, and mixtures thereof;
(c) adding to the slurry at least one type of starchy carbohydrate hydrolyzable to constituent sugars by said fermentative amylolytic microorganisms;
(d) maintaining the slurry containing said inoculum of fermentative amylolytic microorganisms and starchy carbohydrate under conditions suitable for growth of said fermentative microorganisms in the slurry, accompanied by hydrolysis of the starchy carbohydrate to constituent sugars and metabolism by said microorganisms of a portion of said sugars, thereby depleting the concentration of dissolved oxygen in the slurry so as to render the slurry anaerobic;
(e) after the slurry has been rendered anaerobic, adding to the slurry an inoculum of anaerobic microorganisms capable of utilizing as a carbon and energy source said sugars formed in the slurry by the amylolytic microorganisms and capable of degrading said aminoaromatic compounds, the anaerobic inoculum being a consortium comprising genera selected from the group consisting of Klebsiella, Enterobacter, Bacteroides, Fusobacterium, Desulfovibrio, Desulfuromonas, Clostridium, Desulfotomaculum, Sporosarcina, Lactobacillus, Bacillus, Clostridium, Pseudomonas, Veillonella, Acidaminococcus, Methanobacterium, Methoanococcus, and Archaeoglobus, and mixtures thereof;
and
(f) maintaining anaerobic conditions in the slurry for a time sufficient for the anaerobic microorganisms to degrade the contaminant aminoaromatic compounds.

4 more elements

A two-stage process for treating a fluid medium contaminated with nitroaromatic compounds so as to at least partially degrade and thereby reduce the concentrations of the nitroaromatic compounds in the fluid medium, the process comprising:

(a) a fermentative stage wherein a first inoculum is added to the fluid medium, wherein the first inoculum comprises (1) carbohydrate-fermentative microorganisms resistant to the concentration of nitroaromatic compounds present in the fluid medium, and wherein the carbohydrate-fermentative microorganisms are selected from the group consisting of aerobic and facultative microorganisms comprising genera selected from the group consisting of Klebsiella, Enterobacter, Lactobacillus, Bacillus, clostridium, and Pseudonomas, and mixtures thereof, (2) at least one type of carbohydrate fermentable by said carbohydrate-fermentative microorganisms, and (3) a source of metabolizable nitrogen, after which addition the fluid medium is maintained under conditions suitable for growth of the carbohydrate-fermentative microorganisms in the fluid medium, accompanied by fermentation by said microorganisms of a portion of said carbohydrate, thereby depleting the concentration of dissolved oxygen in the fluid medium so as to render the fluid medium anaerobic;
and
(b) an anaerobic stage after the aerobic stage, in which anaerobic stage is added to the fluid medium a second inoculum, wherein the second inoculum comprises anaerobic microorganisms capable of utilizing said carbohydrate remaining from the aerobic stage as a carbon and energy source and of degrading said nitroaromatic compounds, the second inoculum being a consortium comprising genera selected from the group consisting of Klebsiella, Enterobacter, Bacteroides, Fusobacterium, Desulfovibrio, Desulfuromonas, Clostridium, Desulfotomaculum, Sporosarcina, Lactobacillus,. Bacillus, Clostridium, Pseudomonas, Veillonella, Acidaminococcus, Methanobacterium, Methoanococcus, and Archaeoglobus, and mixtures thereof, after which addition the fluid medium is maintained in an anaerobic condition for a time sufficient for the anaerobic microorganisms to degrade the contaminant nitroaromatic compounds in the fluid medium.

Dependencies are inferred from the claim text.

Biological system for degrading nitroaromatics in water and soils

Life of this patent

Biological system for degrading nitroaromatics in water and soils

Life of this patent

Abstract

Claims55