Method for converting biomass to methane

• US 8,993,288 B2
• Filed: 09/19/2013
• Issued: 03/31/2015
• Est. Priority Date: 09/24/2010
• Status: Active Grant

• Current Assignee: Anaergia Inc.
• Original Assignee: Anaergia Inc.
• Inventors: Lewis, F. Michael
• Primary Examiner(s): GITOMER, RALPH J
• Application Number:
  US14/031,758
• Publication Number:
  US 20140024096A1
• Time in Patent Office: 558 Days
• Field of Search: 435/165, 201/2.5, 585/240, 481/275
• US Class Current: 435/165
• CPC Class Codes: C10B 47/44 with conveyor-screws
• CPC Class Codes: C10B 53/02 of cellulose-containing material production of pyroligneous acid C10C5/00
• CPC Class Codes: C10C 5/00 Production of pyroligneous acid distillation of wood, dry distillation of organic wastecarbonisation of wood C10B
• CPC Class Codes: C10J 2200/158 Screws
• CPC Class Codes: C10J 2300/0946 Waste, e.g. MSW, tires, glass, tar sand, peat, paper, lignite, oil shale
• CPC Class Codes: C10J 2300/1681 with biological plants, e.g. involving bacteria, algae, fungi
• CPC Class Codes: C10J 3/007 Screw type gasifiers
• CPC Class Codes: C10L 3/08 Production of synthetic natural gas
• CPC Class Codes: C12M 21/12 for producing fuels or solvents C12M21/04 takes precedence; liquid carbonaceous fuels C10L1/00, solid fuels C10L5/00
• CPC Class Codes: C12M 29/00 Means for introduction, extraction or recirculation of materials, e.g. pumps pumps per se F04B
• CPC Class Codes: C12M 43/00 Combinations of bioreactors or fermenters with other apparatus
• CPC Class Codes: C12P 5/023 Methane
• CPC Class Codes: C12P 7/08 produced as by-product or from waste or cellulosic material substrate
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: C12P 7/14 Multiple stages of fermentation; Multiple types of microorganisms or re-use of microorganisms
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

A method for enhancing the treatment of lignocellulose-containing materials by biotreatment wherein such lignocellulose-containing materials, normally resistant to biotreatment, are first subjected to a low-temperature, long-residence time pyrolysis at about 175° C. to about 325° C. for about 0.1 hour to about 2.0 hours, wherein a substantial portion of the incoming material is distilled into water-soluble compounds amenable to anaerobic biotreatment. Exemplary applications of the method include pyrolytic pre-treatment of wastewater sludges, cellulosic wastes, wood, peat, plant residues, low-grade coal, and the like to enhance methane gas production in anaerobic digestion and/or oxygen-limited or oxygen-starved fermentation to produce ethanol.

Claims

1. A method for converting a wastewater treatment sludge in a biotreatment process to produce a methanaceous fuel gas, comprising:

treating said sludge by way of anaerobic biological treatment step to produce a methanaceous fuel gas and a dewatered solids stream;

subjecting said dewatered solids stream to pyrolysis to produce (a) a pyroligneous liquid containing biotreatable liquid substances, (b) a pyrogas, and (c) pyrosolids including char;

separating said pyrosolids from said pyroligneous liquid and pyrogas; and

subjecting said pyroligneous liquid to said anaerobic biological treatment step to produce additional methanaceous fuel gas.

2. A method in accordance with claim 1, wherein said pyrolysis is conducted at a temperature of between about 175 °

C. and about 325 °

C.

3. A method in accordance with claim 1, wherein said pyrolysis is conducted with a solids residence time of about 0.1 hour and about 2 hours.

4. A method in accordance with claim 1, wherein said pyrolysis is conducted with a solids residence time of about 0.1 hour and about 0.5 hour.

5. A method in accordance with claim 1, wherein said anaerobic biological treatment step is conducted with methanogenic microorganisms.

6. A method in accordance with claim 1, wherein at least a portion of said pyrogas is introduced into said anaerobic biological treatment step.

7. A method in accordance with claim 1, wherein a major portion of said pyrogas is introduced into said anaerobic biological treatment step.

8. A method in accordance with claim 1, wherein said separated pyrosolids are used as an agronomic soil amendment.

9. A method in accordance with claim 1, wherein said method further includes a step of removing toxic substances from said pyroligneous acid before introduction into said biological treatment step.

10. A method in accordance with claim 1, wherein said method includes a further step of adding at least one of a sugar and vitamins and minerals to said biological treatment step.

11. A method in accordance with claim 1, further comprising a step of adding municipal solid waste to said pyrolysis step.

12. A method for treating lignocellulose-containing material, comprising the steps of:

introducing lignocellulose-containing material to an anaerobic biotreatment step wherein methanogenic microorganisms produce a methane-containing biogas and an aqueous stream containing residual biosolids;

dewatering said residual biosolids;

subjecting said residual biosolids materials to a pyrolysis to produce a pyrolysis product comprising a pyrogas;

introducing at least a portion of said pyrogas to said anaerobic biotreatment step, wherein said introduced pyrogas portion mixes with said biogas produced in said anaerobic biotreatment step; and

separating and removing said mixed pyrogas and biogas for use as a fuel gas.

13. A claim in accordance with claim 12, wherein said pyrolysis is conducted at a temperature of about 175 °

C. to about 325 °

C.

14. A claim in accordance with claim 12, wherein said pyrolysis is conducted with a solids residence time of about 0.1 hour to about 2.0 hours.

15. A claim in accordance with claim 12, wherein said pyrolysis is conducted with a solids residence time of about 0.1 hour to about 0.5 hours.