Method for generating methane from a carbonaceous feedstock

Patent metadata

Field	Value
Publication number	US-2016138048-A1
Application number	US-201414540393-A
Country	US
Kind code	A1
Filing date	Nov 13, 2014
Priority date	Nov 13, 2014
Publication date	May 19, 2016
Grant date	—

Abstract

The present invention provides a method for generating methane from a carbonaceous feedstock with simultaneous in situ sequestration of carbon dioxide to afford a biogas comprising at least 85 percent by volume methane, the method comprising anaerobically incubating a particulate additive in contact with a carbonaceous feedstock in a neutral or alkaline aqueous culture medium containing a culture of methanogenic consortia and collecting methane generated therefrom. The additive comprises at least one material selected from a biochar, an ash produced by gasification or combustion of a carbonaceous material, a black carbon soil, and a Terra Preta soil.

First claim

1 . A method for generating a biogas comprising at least 85 percent by volume (vol %) methane from a carbonaceous feedstock, the method comprising the steps of: (a) anaerobically incubating a mixture of the carbonaceous feedstock in a neutral or alkaline aqueous culture medium containing a culture of methanogenic microorganisms and a particulate additive; and (b) collecting biogas generated therefrom; wherein at least a portion of carbon dioxide produced during the incubation reacts with cations provided by the additive to prevent the carbon dioxide from evolving into the gas phase; the additive is present in the culture medium at a concentration of about 5 percent by weight (wt %) to about 40 wt % based on the volatile solid content of the carbonaceous feedstock such that the methane content of the collected biogas is at least 85 vol %, the additive sequesters hydrogen sulfide, the collected biogas has a hydrogen sulfide content of less than about 4 parts per million (ppm) (v/v), and the additive includes alkali metal and alkaline earth metal cations and comprises one or more materials selected from the group consisting of (i) a biochar produced from gasification or pyrolysis of a biomass material, (ii) an ash produced by gasification or combustion of a carbonaceous material, (iii) a black carbon soil, and (iv) a Terra Preta soil.

2 . The method of claim 1 , wherein the additive comprises a potassium concentration of at least about 53,000 parts per million (ppm) (w/w).

3 . The method of claim 2 , wherein the additive has been supplemented with a source of potassium ion to achieve a potassium concentration of at least about 1,000 ppm (w/w) in the culture medium.

4 . The method of claim 1 , wherein the additive comprises sufficient alkaline earth metal ions to provide an alkaline earth metal ion concentration of at least about 1,500 ppm (w/w) in the culture medium.

5 . (canceled)

6 . The method of claim 5 , wherein the collected biogas has a hydrogen sulfide content of less than about 5 parts per billion (ppb)(v/v).

7 . The method of claim 1 , wherein the collected biogas has a methane content of at least about 90 vol %.

8 . The method of claim 1 , wherein the collected biogas has a methane content of at least about 95 vol %.

9 . The method of claim 1 , wherein the additive comprises a biochar of at least one biomass material selected from the group consisting of gymnosperm plant material, angiosperm plant material, agricultural residue, algae, yeast and fungi.

10 . The method of claim 1 , wherein the additive comprises a corn stover biochar.

11 . The method of claim 1 , wherein the additive comprises the ash and the carbonaceous material from which the ash is produced is selected from the group consisting of coal, a biomass material, a tar sand, a municipal solid waste, a leachate from a municipal waste, biosolids from wastewater treatment, and manure.

12 . The method of claim 1 , wherein the carbonaceous feedstock comprises coal.

13 . The method of claim 12 , wherein the coal is high-sulfur coal.

14 . The method of claim 13 , wherein the coal contains heavy metals.

15 . The method of claim 1 , wherein the carbonaceous feedstock comprises tar sand.

16 . The method of claim 1 , wherein the carbonaceous feedstock comprises municipal waste, a leachate from a municipal waste, or a combination thereof.

17 . The method of claim 1 , wherein the carbonaceous feedstock comprises manure, biosolids from wastewater treatment, an agricultural residue, algae, algal residues, or a combination of two or more thereof.

18 . The method of claim 1 , wherein the mixture is incubated at a temperature in the range of about 10° C. to about 65° C.

19 . The method of claim 1 , wherein the culture of methanogenic consortia comprises one or more cultures from a coal bed methane produced water, a manure digester, a municipal waste, an activated sludge from wastewater treatment, or an isolated culture of an individual methanogenic microbial consortia.

20 . The method of claim 1 , wherein the mixture is incubated in a reactor comprising a system to restrict introduction of oxygen and for maintaining an aqueous environment, and is adapted to mix the particulate carbonaceous feedstock with the particulate additive, and the methanogenic microbial consortia, and further includes a collector for collecting the biogas as it evolves.

21 . The method of claim 1 , wherein the aqueous culture medium has a pH in the range of about 6 to about 10.

22 . The method of claim 1 , wherein the additive material comprises porous particles that have a mean pore volume in the range of about 0.01 cm 3 /g to about 1.25 cm 3 /g, and an average pore diameter in the range of about 1 nm to 10 nm.

23 . The method of claim 1 , wherein the mixture is incubated in a coal seam, a coal mine, a large hole or quarry, a wastewater treatment plant, a solid waste digester, an anaerobic digester, an anaerobic reactor or a landfill.

24 . The method of claim 1 , wherein the particulate additive has a mean particle size in the range of about 0.01 mm to about 25 mm.

25 . The method of claim 1 , wherein the carbonaceous feedstock is particulate and has a mean particle size in the range of about 0.01 mm to about 50 mm.

26 . The method of claim 1 , further comprising collecting biosolids from the mixture after incubation, and applying the collected biosolids to soil as a fertilizer or soil amendment.

27 . The method of claim 1 ,wherein the method further comprises collecting biosolids from the mixture after incubation, and applying the collected biosolids to soil as a fertilizer or soil amendment, and wherein the collected biosolids are enriched in Ca, Mg, Fe, P, K and or N relative to biosolids collected from a biomethanation under the same conditions and with the same feedstock, in the absence of the additive.

Assignees

• Uchicago Argonne Llc

Inventors

• Snyder Seth W
• Urgun-Demirtas Meltem
• Shen Yanwen

Classifications

• C12P5/023 Primary

  Methane · CPC title

• B01D2257/304

  Hydrogen sulfide · CPC title

• B01D2258/05

  Biogas · CPC title

• B01D53/0423

  Beds in columns · CPC title

• B01D2256/245

  Methane · CPC title