Tower reactors for bioconversion of lignocellulosic material

• US 5,733,758 A
• Filed: 01/10/1997
• Issued: 03/31/1998
• Est. Priority Date: 01/10/1997
• Status: Expired due to Term

• Current Assignee: Abengoa Bioenergy New Technologies, Inc. (Abengoa SA)
• Original Assignee: Quang A Nguyen
• Inventors: Nguyen, Quang A.
• Primary Examiner(s): Lilling, Herbert J.
• Application Number:
  US08/780,943
• Time in Patent Office: 445 Days
• Field of Search: 435/161, 435/163, 435/162, 435/165, 435/300
• US Class Current: 435/162
• 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 21/16 Solid state fermenters, e.g. for koji production
• CPC Class Codes: C12M 21/18 Apparatus specially designed for the use of free, immobilized or carrier-bound enzymes
• CPC Class Codes: C12M 27/02 Stirrer or mobile mixing elements
• CPC Class Codes: C12M 41/22 in contact with the bioreactor walls
• CPC Class Codes: C12M 45/09 by enzymatic treatment
• CPC Class Codes: C12M 47/06 Hydrolysis; Cell lysis; Extraction of intracellular or cell wall material lysis of microorganisms C12N1/06; extracting or separating nucleic acids from biological samples C12N15/1003
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

An apparatus for enzymatic hydrolysis and fermentation of pretreated lignocellulosic material, in the form of a tower bioreactor, having mixers to achieve intermittent mixing of the material. Precise mixing of the material is important for effective heat and mass transfer requirements without damaging or denaturing the enzymes or fermenting microorganisms. The pretreated material, generally in the form of a slurry, is pumped through the bioreactor, either upwards of downwards, and is mixed periodically as it passes through the mixing zones where the mixers are located. For a thin slurry, alternate mixing can be achieved by a pumping loop which also serves as a heat transfer device. Additional heat transfer takes place through the reactor heat transfer jackets.

Claims

1. A method for converting pretreated lignocellulosic material to ethanol comprising using tower bioreactors connected in series and having a first mixer, a first mixing zone, a second mixer, a second mixing zone, a third mixer, a third mixing zone, a first hydrolysis section, a second hydrolysis section, and an SSF section, and carrying out the following steps in the order given:

(1) pumping lignocellulosic material into the first mixing zone of a tower bioreactor with the first mixer;

(2) adding cellulase enzymes and nutrients to the lignocellulosic material in the first mixing zone to make a slurry;

(3) mixing the slurry with the first mixer for a period of time sufficient to thoroughly blend the material with enzyme and nutrients;

(4) discontinuing mixing the slurry;

(5) allowing the slurry to move from the first mixing zone into the first hydrolysis section;

(6) maintaining the slurry in the first hydrolysis zone at a temperature which will permit the enzymes to hydrolyze the cellulose contained in the lignocellulosic material to form glucose;

(7) mixing the slurry with the first mixer for a period of time sufficient to thoroughly blend the slurry;

(8) discontinuing mixing the slurry;

(9) allowing the slurry to move forward in the first hydrolysis section for about two hours to about three hours;

(10) pumping the slurry from the first hydrolysis section into the second hydrolysis section;

(11) mixing the slurry with the second mixer for a period of time sufficient to thoroughly blend the slurry;

(12) discontinuing mixing the slurry;

(13) allowing the slurry to move forward in the second hydrolysis section for about two hours to about three hours, or until the desired degree of hydrolysis is achieved;

(14) pumping the slurry from the second hydrolysis section into a third mixing zone;

(15) cooling the slurry in the third mixing zone to a temperature which will permit fermentation of the glucose to ethanol by fermentation organisms;

(16) adding fermentation organisms to the slurry;

(17) mixing the slurry with the third mixer which pushes the slurry forward into the first SSF section;

(18) discontinuing mixing the slurry;

(19) maintaining the slurry in the SSF section at a temperature which will permit both enzymatic hydrolysis of the cellulose and fermentation of sugar to occur;

(20) allowing the slurry of material to move forward in the SSF section for about three hours to about eight hours, or until the desired degree of cellulose hydrolysis and ethanol fermentation has taken place; and

(21) recovering the ethanol.

2. The method according to claim 1 wherein the slurry of lignocellulosic material is greater than 10 wt % undissolved solids and step 9 is about two to about three hours.

3. The method according to claim 1 wherein the slurry of lignocellulosic material is between about 5 and 10 wt % undissolved solids and step 9 is about three to five hours.

4. The method according to claim 1 wherein the slurry of lignocellulosic material is less than about 5 wt % undissolved solids and step 9 is about three to five hours.

5. The method according to claim 1, wherein the lignocellulosic material contains starch.

6. A method for converting pretreated lignocellulosic material to ethanol comprising using at least one tower bioreactor having at least one mixer, at least one mixing zone, at least one hydrolysis section, and at least one SSF section, and carrying out the following steps in the order given:

(1) pumping lignocellulosic material into the mixing zone of a tower bioreactor with the mixer;

(2) adding cellulase enzymes and nutrients to the lignocellulosic material in the mixing zone to make a slurry;

(3) mixing the slurry with the mixer for a period of time sufficient to thoroughly blend the material with enzyme and nutrients;

(4) discontinuing mixing the slurry;

(5) allowing the slurry to move from the mixing zone into the hydrolysis section;

(6) maintaining the slurry in the hydrolysis section at a temperature which will permit the enzymes to hydrolyze the cellulose contained in the lignocellulosic material to form glucose;

(7) mixing the slurry with the mixer for a period of time sufficient to thoroughly blend the slurry;

(8) discontinuing mixing the slurry;

(9) allowing the slurry to move forward in the hydrolysis section until the desired degree of hydrolysis is achieved;

(10) pumping the slurry from the hydrolysis section into the SSF section;

(11) cooling the slurry in the SSF section to a temperature which will permit fermentation to occur;

(12) adding fermentation organisms to the slurry;

(13) mixing the slurry and the fermentation organisms until blended;

(14) discontinuing mixing the slurry;

(15) maintaining the slurry in the SSF section at a temperature which will permit both enzymatic hydrolysis of the cellulose and fermentation to occur;

(16) allowing the slurry of material to move forward in the SSF section until the desired degree of cellulose hydrolysis and ethanol fermentation has taken place; and

(17) recovering the ethanol.