U.S. patent application number 14/465177 was filed with the patent office on 2015-03-12 for system for fermentation of biomass for the production of ethanol.
The applicant listed for this patent is POET Research, Inc.. Invention is credited to David Charles Carlson, Neelakantam V. Narendranath.
Application Number | 20150072390 14/465177 |
Document ID | / |
Family ID | 42678602 |
Filed Date | 2015-03-12 |
United States Patent
Application |
20150072390 |
Kind Code |
A1 |
Narendranath; Neelakantam V. ;
et al. |
March 12, 2015 |
SYSTEM FOR FERMENTATION OF BIOMASS FOR THE PRODUCTION OF
ETHANOL
Abstract
A system for fermentation of biomass is disclosed. The system
comprises a method for producing a fermentation product in a
fermentation system from biomass that has been pre-treated and
separated into a first component and a second component. The method
comprises the steps of supplying the first component to the
fermentation system; providing an ethanologen to the fermentation
system; maintaining the first component and ethanologen in the
fermentation system; and recovering the fermentation product from
the fermentation system. A fermentation system configured to
produce a fermentation product from biomass that has been
pre-treated and separated into a first component and a second
component is disclosed. The system comprises a first vessel
configured to receive the first component and an ethanologen and a
second vessel configured to propagate the ethanologen for supply to
the first vessel. A biorefinery for producing a fermentation
product from biomass is also disclosed. The biorefinery comprises a
preparation system to prepare the biomass into prepared biomass; a
pre-treatment system to pre-treat the prepared biomass with a
dilute acid for separation into a first component from which
pentose can accessed for fermentation and a second component from
which hexose can be made available for fermentation; a first
treatment system to treat the first component into a treated first
component by removing removed components from the first component;
a first fermentation system to produce a first fermentation product
from the pentose; a distillation system to recover ethanol from the
first fermentation product; and a treatment system to process
removed components. The biomass comprises lignocellulosic material;
the lignocellulosic material comprises at least one of corn cobs,
corn plant husks, corn plant leaves and corn plant stalks. The
first component comprises pentose; the pentose comprises xylose.
The ethanologen is capable of fermenting xylose into ethanol.
Inventors: |
Narendranath; Neelakantam V.;
(Sioux Falls, SD) ; Carlson; David Charles;
(Yankton, SD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
POET Research, Inc. |
Sioux Falls |
SD |
US |
|
|
Family ID: |
42678602 |
Appl. No.: |
14/465177 |
Filed: |
August 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12717015 |
Mar 3, 2010 |
8815552 |
|
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14465177 |
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61157137 |
Mar 3, 2009 |
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61157140 |
Mar 3, 2009 |
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61157142 |
Mar 3, 2009 |
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Current U.S.
Class: |
435/165 ;
435/289.1; 435/303.1 |
Current CPC
Class: |
Y02E 50/16 20130101;
C12M 21/12 20130101; Y02E 50/17 20130101; C12M 23/58 20130101; C12M
45/02 20130101; C12M 45/04 20130101; C12P 7/10 20130101; Y02E 50/10
20130101; C12M 43/02 20130101 |
Class at
Publication: |
435/165 ;
435/289.1; 435/303.1 |
International
Class: |
C12P 7/10 20060101
C12P007/10; C12M 1/00 20060101 C12M001/00 |
Claims
1-23. (canceled)
24. A fermentation system configured to produce a fermentation
product from biomass that has been pre-treated and separated into a
first component and a second component comprising: a first vessel
configured to receive the first component and an ethanologen; a
second vessel configured to propagate the ethanologen for supply to
the first vessel; wherein the first vessel is configured to
maintain the first component and ethanologen at a temperature of
between about 31 and about 34 degrees Celsius and at a pH of
between about 5.2 and about 5.8 for a time of no less than 18
hours; wherein the biomass comprises lignocellulosic material;
wherein the lignocellulosic material comprises at least one of corn
cobs, corn plant husks, corn plant leaves and corn plant stalks;
wherein the first component comprises pentose; wherein the pentose
comprises xylose.
25. The system of claim 24, wherein the first component comprises a
liquid component of the lignocellulosic material.
26. The system of claim 24, wherein the lignocellulosic material
consists essentially of corn cobs, corn plant husks, corn plant
leaves and corn stalks.
27. The system of claim 24, wherein the ethanologen is an
organism.
28. The system of claim 27, wherein the organism is capable of
fermenting xylose into a fermentation product.
29. The system of claim 28, wherein the fermentation product
comprises ethanol.
30. A biorefinery for producing a fermentation product from biomass
comprising: a preparation system to prepare the biomass into
prepared biomass; a pre-treatment system to pre-treat the prepared
biomass with a dilute acid for separation into a first component
from which pentose can accessed for fermentation and a second
component from which hexose can be made available for fermentation;
a first treatment system to treat the first component into a
treated first component by removing removed components from the
first component; a first fermentation system to produce a first
fermentation product from the pentose by supplying an ethanologen
and maintaining the first component and ethanologen at a
temperature of between about 26 and about 37 degrees Celsius and at
a pH of between, about 4.5 and about 6.0 for a time of no less than
18 hours; a distillation system to recover ethanol from the first
fermentation product; a treatment system to process removed
components; wherein the biomass comprises lignocellulosic material;
wherein the lignocellulosic material comprises at least one of corn
cobs, corn plant husks, corn plant leaves and corn plant
stalks.
31. The biorefinery of claim 30, wherein the pentose comprises
xylose and the first fermentation product comprises a fermentation
product produced by fermentation of xylose.
32. The biorefinery of claim 30, further comprising: a second
treatment system to treat the second component into a treated
second component from which hexose can be accessed for
fermentation; a second fermentation system to produce a second
fermentation product from the hexose by supplying an ethanologen to
ferment the hexose; a distillation system to recover ethanol from
the second fermentation product.
33. The biorefinery of claim 30, wherein the hexose comprises
glucose.
34. The method of claim 30, wherein the first component comprises a
liquid component of the lignocellulosic material.
35. The method of claim 30, wherein the second component comprises
a solids component of the lignocellulosic material.
36. The method of claim 30, wherein the lignocellulosic material
consists essentially of corn cobs, corn plant husks, corn plant
leaves and corn stalks.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to and incorporates
by reference each of the following applications: (a) U.S.
Provisional Application Ser. No. 61/157,140, titled Process for
Fermenting Pentose in Biomass, filed on Mar. 3, 2009; (b) U.S.
Provisional Application Ser. No. 61/157,142, titled Continuous
Fermentation of a Liquid Hydrolysate Containing Pentose, filed on
Mar. 3, 2009; and (c) U.S. Provisional Application Ser. No.
61/157,137, titled Concentration of Pentose Liquor, filed on Mar.
3, 2009.
[0002] The present application relates to and incorporates by
reference the following applications: (a) U.S. Application Serial
No. (Atty. Docket No. P184 1250.1), titled System for Pre-Treatment
of Biomass for the Production of Ethanol, filed on Mar. 3, 2010;
(b) U.S. Application Serial No. (Atty. Docket No. P184 1260.1),
titled System for Treatment of Biomass to Facilitate the Production
of Ethanol, filed on Mar. 3, 2010; and (c) U.S. Application Serial
No. (Atty. Docket No. P184 1270.1), titled System for Management of
Yeast to Facilitate the Production of Ethanol, filed on Mar. 3,
2010.
FIELD
[0003] The present invention relates to a system for fermentation
of biomass in the production of ethanol. The present invention also
relates to a system for fermentation of biomass that has been
pre-treated and separated into a first component and a second
component. The present invention further relates to a system for
fermentation of a first component of biomass using an ethanologen
capable of fermenting xylose into ethanol.
BACKGROUND
[0004] Ethanol can be produced from grain-based feedstocks (e.g.
corn, sorghum/milo, barley, wheat, soybeans, etc.), from sugar
(e.g. from sugar cane, sugar beets, etc.), and from biomass (e.g.
from lignocellulosic feedstocks such as switchgrass, corn cobs and
stover, wood or other plant material).
[0005] Biomass comprises plant matter that can be suitable for
direct use as a fuel/energy source or as a feedstock for processing
into another bioproduct (e.g., a biofuel such as cellulosic
ethanol) produced at a biorefinery (such as an ethanol plant).
Biomass may comprise, for example, corn cobs and stover (e.g.,
stalks and leaves) made available during or after harvesting of the
corn kernels, fiber from the corn kernel, switchgrass, farm or
agricultural residue, wood chips or other wood waste, and other
plant matter (grown for processing into bioproducts or for other
purposes). In order to be used or processed, biomass will be
harvested and collected from the field and transported to the
location where it is to be used or processed.
[0006] In a conventional ethanol plant producing ethanol from corn,
ethanol is produced from starch. Corn kernels are cleaned and
milled to prepare starch-containing material for processing. (Corn
kernels can also be fractionated to separate the starch-containing
material (e.g. endosperm) from other matter (such as fiber and
germ).) The starch-containing material is slurried with water and
liquefied to facilitate saccharification where the starch is
converted into sugar (e.g. glucose) and fermentation where the
sugar is converted by an ethanologen (e.g. yeast) into ethanol. The
product of fermentation (i.e. fermentation product) is beer, which
comprises a liquid component containing ethanol and water and
soluble components, and a solids component containing unfermented
particulate matter (among other things). The fermentation product
is sent to a distillation system. In the distillation system, the
fermentation product is distilled and dehydrated into ethanol. The
residual matter (e.g. whole stillage) comprises water, soluble
components, oil and unfermented solids (i.e. the solids component
of the beer with substantially all ethanol removed that can be
dried into dried distillers grains (DDG) and sold as an animal feed
product). Other co-products, for example syrup (and oil contained
in the syrup), can also be recovered from the stillage. Water
removed from the fermentation product in distillation can be
treated for re-use at the plant.
[0007] In a biorefinery configured to produce ethanol from biomass,
ethanol is produced from lignocellulosic material. Lignocellulosic
biomass typically comprises cellulose, hemicellulose and lignin.
Cellulose (a type of glucan) is a polysaccharide comprising hexose
(C6) sugar monomers such as glucose linked in linear chains.
Hemicellulose is .a branched chain polysaccharide that may comprise
several different pentose (C5) sugar monomers (such as xylose and
arabinose) and small amounts of hexose (C6) sugar monomers in
branched chains.
[0008] The biomass is prepared so that sugars in the
lignocellulosic material (such as glucose from the cellulose and
xylose from the hemicellulose) can be made accessible and fermented
into a fermentation product from which ethanol can be recovered.
After fermentation the fermentation product is sent to the
distillation system, where the ethanol is recovered by distillation
and dehydration. Other bioproducts such as lignin and organic acids
may also be recovered as by-products or co-products during the
processing of biomass into ethanol. Determination of how to more
efficiently prepare and treat the biomass for production into
ethanol will depend upon the source and type or composition of the
biomass. Biomass of different types or from different sources is
likely to vary in properties and composition (e.g. relative amounts
of cellulose, hemicellulose, lignin and other components). For
example the composition of wood chips will differ from the
composition of corn cobs or switchgrass.
[0009] It would be advantageous to provide for a system for
treatment of biomass to facilitate the production of ethanol. It
would also be advantageous to provide for a system to fermenting
biomass for the production of ethanol. It would further be
advantageous to provide for a system that provided one or more of
features to facilitate improvement in the efficiency and yield of
cellulosic ethanol from biomass.
SUMMARY
[0010] The present invention relates to a method for producing a
fermentation product in a fermentation system from biomass that has
been pre-treated and separated into a first component and a second
component. The method comprises the steps of supplying the first
component to the fermentation system; providing an ethanologen to
the fermentation system; maintaining the first component and
ethanologen in the fermentation system at a temperature of between
about 26 and about 37 degrees Celsius and at a pH of between about
4.5 and about 6.0 for a time of no less than 18 hours; and
recovering the fermentation product from the fermentation system.
The ethanologen is supplied to the fermentation system in a
concentration of less than 150 grams of ethanologen on a dry basis
per liter of first component. The biomass comprises lignocellulosic
material; the lignocellulosic material comprises at least one of
corn cobs, corn plant husks, corn plant leaves and corn plant
stalks. The first component comprises pentose; the pentose
comprises xylose. The ethanologen is capable of fermenting xylose
into ethanol.
[0011] The present invention also relates to a fermentation system
configured to produce a fermentation product from biomass that has
been pre-treated and separated into a first component and a second
component. The system comprises a first vessel configured to
receive the first component and an ethanologen and a second vessel
configured to propagate the ethanologen for supply to the first
vessel. The first vessel is configured to maintain the first
component and ethanologen at a temperature of between about 31 and
about 34 degrees Celsius and at a pH of between about 5.2 and about
5.8 for a time of no less than 18 hours. The biomass comprises
lignocellulosic material; the lignocellulosic material comprises at
least one of corn cobs, corn plant husks, corn plant leaves and
corn plant stalks. The first component comprises pentose; the
pentose comprises xylose.
[0012] The present invention further relates to a biorefinery for
producing a fermentation product from biomass. The biorefinery
comprises a preparation system to prepare the biomass into prepared
biomass; a pre-treatment system to pre-treat the prepared biomass
with a dilute acid for separation into a first component from which
pentose can accessed for fermentation and a second component from
which hexose can be made available for fermentation; a first
treatment system to treat the first component into a treated first
component by removing removed components from the first component;
a first fermentation system to produce a first fermentation product
from the pentose by supplying an ethanologen and maintaining the
first component and ethanologen at a temperature of between about
26 and about 37 degrees Celsius and at a pH of between about 4.5
and about 6.0 for a time of no less than 18 hours; a distillation
system to recover ethanol from the first fermentation product; and
a treatment system to process removed components. The biomass
comprises lignocellulosic material; the lignocellulosic material
comprises at least one of corn cobs, corn plant husks, corn plant
leaves and corn plant stalks.
BRIEF DESCRIPTION OF THE FIGURES AND TABLES
[0013] FIG. 1A is a perspective view of a biorefinery comprising a
cellulosic ethanol production facility.
[0014] FIG. 1B is a perspective view of a biorefinery comprising a
cellulosic ethanol production facility and a corn-based ethanol
production facility.
[0015] FIG. 2 is a schematic diagram of a system for receipt and
preparation of biomass for a cellulosic ethanol production
facility.
[0016] FIG. 3 is a schematic block diagram of a system for the
production of ethanol from biomass.
[0017] FIGS. 4A, 4B and 4C are schematic block diagrams of systems
for treatment and processing of components from the production of
ethanol from biomass.
[0018] FIGS. 5A and 5B are schematic diagrams of the process flow
for systems for the production of ethanol from biomass.
[0019] FIG. 6A is a schematic block diagram of apparatus used for
preparation, pre-treatment and separation of biomass.
[0020] FIG. 6B is a perspective view of apparatus used to pre-treat
and separate the biomass.
[0021] FIGS. 7A and 7B are schematic block diagrams of a treatment
system and fermentation system according to an exemplary
embodiment.
[0022] FIG. 8A is a schematic block diagram of a system according
to an exemplary embodiment,
[0023] FIG. 8B is a schematic block diagram of a fermentation
system and treatment system according to an exemplary
embodiment.
[0024] FIGS. 9A and 9B are perspective view of fermentation system
according to exemplary embodiments.
[0025] FIGS. 10A through 10D are diagrams of operating conditions
for the fermentation system according to an exemplary
embodiment.
[0026] FIG. 11 is a graph of results obtained through the use of
the fermentation system according to an exemplary embodiment.
[0027] FIGS. 12A and 12B are a graph of results obtained through
the use of the fermentation system according to an exemplary
embodiment.
[0028] FIGS. 13A and 13B are a graph of results obtained through
the use of the fermentation system according to an exemplary
embodiment.
[0029] FIG. 14 is a graph of results obtained through the use of
the fermentation system according to an exemplary embodiment.
[0030] TABLES 1A and 1B list the composition of biomass comprising
lignocellulosic plant material from the corn plant according to
exemplary and representative embodiments.
[0031] TABLES 2A and 2B list the composition of the liquid
component of pre-treated biomass according to exemplary and
representative embodiments.
[0032] TABLES 3A and 3B list the composition of the solids
component of pre-treated biomass according to exemplary and
representative embodiments.
[0033] TABLES 4 through 7 provide data and results relating to the
use of the fermentation system according to an exemplary
embodiment.
DETAILED DESCRIPTION
[0034] Referring to FIG. 1A, a biorefinery configured to produce
ethanol from biomass is shown.
[0035] According to an exemplary embodiment, the biorefinery is
configured to produce ethanol from biomass in the form of a
lignocellulosic feedstock such as plant material from the corn
plant (e.g. corn cobs and corn stover). Lignocellulosic feedstock
such as lignocellulosic material from the corn plant comprises
cellulose (from which C6 sugars such as glucose can be made
available) and/or hemicellulose (from which C5 sugars such as
xylose and arabinose can be made available).
[0036] As shown in FIG. 1A, the biorefinery comprises an area where
biomass is delivered and prepared to be supplied to the cellulosic
ethanol production facility. The cellulosic ethanol production
facility comprises apparatus for preparation, pre-treatment and
treatment of the biomass into treated biomass suitable for
fermentation into fermentation product in a fermentation system.
The facility comprises a distillation system in which the
fermentation product is distilled and dehydrated into ethanol. As
shown in FIG. 1A, the biorefinery may also comprise a waste
treatment system (shown as comprising an anaerobic digester and a
generator). According to other alternative embodiments, the waste
treatment system may comprise other equipment configured to treat,
process and recover components from the cellulosic ethanol
production process, such as a solid/waste fuel boiler, anaerobic
digester, aerobic digester or other biochemical or chemical
reactors.
[0037] As shown in FIG. 1B, according to an exemplary embodiment, a
biorefinery may comprise a cellulosic ethanol production facility
(which produces ethanol from lignocellulosic material and
components of the corn plant) co-located with a corn-based ethanol
production facility (which produces ethanol from starch contained
in the endosperm component of the corn kernel). As indicated in
FIG. 1B, by co-locating the two ethanol production facilities,
certain plant systems may be shared, for example, systems for
dehydration, storage, denaturing and transportation of ethanol,
energy/fuel-to-energy generation systems, plant management and
control systems, and other systems. Corn fiber (a component of the
corn kernel), which can be made available when the corn kernel is
prepared for milling (e.g. by fractionation) in the corn-based
ethanol production facility, may be supplied to the cellulosic
ethanol production facility as a feedstock. Fuel or energy sources
such as methane or lignin from the cellulosic ethanol production
facility may be used to supply power to either or both co-located
facilities. According to other alternative embodiments, a
biorefinery (e.g. a cellulosic ethanol production facility) may be
co-located with other types of plants and facilities, for example
an electric power plant, a waste treatment facility, a lumber mill,
a paper plant or a facility that processes agricultural
products.
[0038] Referring to FIG. 2, a system for preparation of biomass
delivered to the biorefinery is shown. The biomass preparation
system may comprise apparatus for receipt/unloading of the biomass,
cleaning (i.e. removal of foreign matter), grinding (i.e. milling,
reduction or densification), and transport and conveyance for
processing at the plant. According to an exemplary embodiment,
biomass in the form of corn cobs and stover may be delivered to the
biorefinery and stored (e.g. in bales, piles or bins, etc.) and
managed for use at the facility. According to a preferred
embodiment, the biomass may comprise at least 20 to 30 percent corn
cobs (by weight) with corn stover and other matter. According to
other exemplary embodiments, the preparation system of the
biorefinery may be configured to prepare any of a wide variety of
types of biomass (i.e. plant material) for treatment and processing
into ethanol and other bioproducts at the plant.
[0039] Referring to FIG. 3, a schematic diagram of the cellulosic
ethanol production facility is shown. According to a preferred
embodiment, biomass comprising plant material from the corn plant
is prepared and cleaned at a preparation system. After preparation,
the biomass is mixed with water into a slurry and is pre-treated at
a pre-treatment system. In the pre-treatment system, the biomass is
broken down (e.g. by hydrolysis) to facilitate separation into a
liquid component (e.g. a stream comprising the C5 sugars) and a
solids component (e.g. a stream comprising cellulose from which the
C6 sugars can be made available). The C5-sugar-containing liquid
component (C5 stream) and C6-sugar-containing solids component (C6
stream) can be treated (as may be suitable) and fermented in a
fermentation system. Fermentation product from the fermentation
system is supplied to a distillation system where the ethanol is
recovered.
[0040] As shown in FIGS. 3 and 4A, removed components from
treatment of the C5 stream can be treated or processed to recover
by-products, such as organic acids and furfural. As shown in FIGS.
3 and 4B, removed components from treatment of the C6 stream, such
as lignin or other components, can be treated or processed into
bioproducts or into fuel (such as lignin for a solid fuel boiler or
methane produced by treatment of residual/removed matter such as
acids and lignin in an anaerobic digester). As shown in FIGS. 4A,
4B and 4C, components removed during treatment and production of
ethanol from the biomass from either or both the C5 stream and the
C6 stream (or at distillation) may be processed into bioproducts
(e.g. by-products or co-products) or recovered for use or reuse. As
shown in FIG. 4C, removed components from the distillation system
(such as stillage or removed solids) or from the treatment of the
fermentation product before distillation (e.g. removed solids and
particulate matter, which may comprise residual lignin, etc.) can
be treated or processed into bioproducts or fuel (e.g. methane
produced in an anaerobic digester).
[0041] According to a preferred embodiment, the biomass comprises
plant material from the corn plant, such as corn cobs, husks and
leaves and stalks (e.g. at least upper half or three-quarters
portion of the stalk); the composition of the plant material (i.e.
cellulose, hemicellulose and lignin) will be approximately as
indicated in TABLES 1A and 1B (i.e. after at least initial
preparation of the biomass, including removal of any foreign
matter). According to a preferred embodiment, the plant material
comprises corn cobs, husks/leaves and stalks; for example, the
plant material may comprise (by weight) up to 100 percent cobs, up
to 100 percent husks/leaves, approximately 50 percent cobs and
approximately 50 percent husks/leaves, approximately 30 percent
cobs and approximately 50 percent husks/leaves and approximately 20
percent stalks, or any other combinations of cobs, husks/leaves and
stalks from the corn planta See TABLE 1A. According to an
alternative embodiment, the lignocellulosic plant material may
comprise fiber from the corn kernel (e.g. in some combination with
other plant material). TABLE 1B provides typical and expected
ranges believed to be representative of the composition of biomass
comprising lignocellulosic material from the corn plant. According
to exemplary embodiments, the lignocellulosic plant material of the
biomass (from the corn plant) will comprise (by weight) cellulose
at about 30 to 55 percent, hemicellulose at about 20 to 50 percent,
and lignin at about 10 to 25 percent; according to a particularly
preferred embodiment, the lignocellulosic plant material of the
biomass (i.e. cobs, husks/leaves and stalk portions from the corn
plant) will comprise (by weight) cellulose at about 35 to 45
percent, hemicellulose at about 24 to 42 percent, and lignin at
about 12 to 20 percent. According to a particularly preferred
embodiment, pre-treatment of the biomass will yield a liquid
component that comprises (by weight) xylose at no less than 1.0
percent and a solids component that comprises (by weight) cellulose
(from which glucose can be made available) at no less than 45
percent.
[0042] Referring to FIGS. 5A and 5B, exemplary embodiments of
systems for the production of ethanol from biomass are shown. As
shown in FIGS. 5A and 5B, biomass is pre-treated in a pre-treatment
system and then separated into a liquid component and a solids
component.
[0043] According to a preferred embodiment, in the pre-treatment
system an acid will be applied to the prepared biomass to
facilitate the break down of the biomass for separation into the
liquid component (C5 stream from which fermentable C5 sugars can be
recovered) and the solids component (C6 stream from which
fermentable C6 sugars can be accessed). According to a preferred
embodiment, the acid can be applied to the biomass in a reaction
vessel under determined operating conditions (i.e. acid
concentration, pH, temperature, time, pressure, solids loading,
flow rate, supply of process water or steam, etc.) and the biomass
can be agitated/mixed in the reaction vessel to facilitate the
break down of the biomass. According to exemplary embodiments, an
acid such as sulfuric acid, hydrochloric acid, nitric acid,
phosphoric acid, acetic acid, etc. (or a formulation/mixture of
acids) can be applied to the biomass. According to a particularly
preferred embodiment, sulfuric acid will be applied to the biomass
in pre-treatment.
[0044] The liquid component (C5 stream) comprises water, dissolved
sugars (such as xylose, arabinose and glucose) to be made available
for fermentation into ethanol, acids and other soluble components
recovered from the hemicellulose. (TABLE 2B provides typical and
expected ranges believed to be representative of the composition of
biomass comprising lignocellulosic material from the corn plant.)
According to an exemplary embodiment, the liquid component may
comprise approximately 5 to 7 percent solids (i.e.
suspended/residual solids such as partially-hydrolyzed
hemicellulose, cellulose and lignin). According to a particularly
preferred embodiment, the liquid component will comprise at least 2
to 4 percent xylose (by weight); according to other exemplary
embodiments, the liquid component will comprise no less than 1 to 2
percent xylose (by weight). TABLES 2A and 2B list the composition
of the liquid component of pre-treated biomass (from prepared
biomass as indicated in TABLES 1A and 1B) according to exemplary
and representative embodiments.
[0045] The solids component (C6 stream) comprises water, acids and
solids such as cellulose from which sugar, such as glucose, can be
made available for fermentation into ethanol, and lignin. (TABLE 3B
provides typical and expected ranges believed to be representative
of the composition of biomass comprising lignocellulosic material
from the corn plant.) According to an exemplary embodiment, the
solids component may comprise approximately 10 to 40 percent solids
(by weight) (after separation); according to a particularly
preferred embodiment, the solids component will comprise
approximately 20 to 30 percent solids (by weight). According to a
preferred embodiment, the solids in the solids component comprise
no less than 30 percent cellulose and the solids component may also
comprise other dissolved sugars (e.g. glucose and xylose). TABLES
3A and 3B list the composition of the solids component of
pre-treated biomass (from prepared biomass as indicated in TABLES
1A and 1B) according to exemplary and representative
embodiments.
[0046] During pre-treatment, the severity of operating conditions
(such as pH, temperature and time) may cause formation of
components that are inhibitory to fermentation. For example, under
some conditions, the dehydration of C5 sugars (such as xylose or
arabinose) may cause the formation of furfural and/or
hydroxymethylfurfural (HMF). Acetic acid may also be formed, for
example when acetate is released during the break down of cellulose
in pre-treatment. Sulfuric acid, which may be added to prepared
biomass to facilitate pre-treatment, if not removed or neutralized,
may also be inhibitory to fermentation. According to an exemplary
embodiment, by adjusting pre-treatment conditions (such as pH,
temperature and time), the formation of inhibitors can be reduced
or managed; according to other exemplary embodiments, components of
the pre-treated biomass may be given further treatment to remove or
reduce the level of inhibitors (or other undesirable matter).
[0047] Referring to FIGS. 5A and 5B, after pre-treatment and
separation the C5 stream and the C6 stream are processed
separately; as shown, the C5 stream and the C6 stream may be
processed separately prior to co-fermentation (C5/C6 fermentation
as shown in FIG. 5A) or processed separately including separate
fermentation (separate C5 fermentation and C6 fermentation as shown
in FIG. 5B).
[0048] Treatment of the C5 stream (liquid component) of the biomass
may be performed in an effort to remove components that are
inhibitory to efficient fermentation (e.g. furfural, HMF, sulfuric
acid and acetic acid) and residual lignin (or other matter) that
may not be fermentable from the C5 sugar component so that the
sugars (e.g. xylose, arabinose, as well as other sugars such as
glucose) are available for fermentation. The C5 sugars in the C5
stream may also be concentrated to improve the efficiency of
fermentation (e.g. to improve the titer of ethanol for
distillation).
[0049] Treatment of the C6 stream (solids component) of the biomass
may be performed to make the C6 sugars available for fermentation.
According to a preferred embodiment, hydrolysis (such as enzyme
hydrolysis) may be performed to access the C6 sugars in the
cellulose; treatment may also be performed in an effort to remove
lignin and other non-fermentable components in the C6 stream (or to
remove components such as residual acid or acids that may be
inhibitory to efficient fermentation).
[0050] According to an exemplary embodiment shown in FIG. 5A, after
pre-treatment and separation the C5 stream and the C6 stream can be
treated separately and subsequently combined after treatment (e.g.
as a slurry) for co-fermentation in the fermentation system to
produce a C5/C6 fermentation product from the available sugars
(e.g. xylose and glucose); the C5/C6 fermentation product can
(after treatment, if any) be supplied to the distillation system
for recovery of the ethanol (e.g. through distillation and
dehydration). According to an exemplary embodiment shown in FIG.
5B, the C5 stream and the C6 stream can each be separately
processed through fermentation and distillation (after treatment,
it any) to produce ethanol. According to any preferred embodiment,
a suitable fermenting organism (ethanologen) will be used in the
fermentation system; the selection of an ethanologen may be based
on various considerations, such as the predominant types of sugars
present in the slurry. Dehydration and/or denaturing of the ethanol
produced from the C5 stream and the C6 stream may be performed
either separately or in combination.
[0051] FIG. 6A and 6B show the apparatus used for preparation,
pre-treatment and separation of lignocellulosic biomass according
to an exemplary embodiment. As shown, biomass is prepared in a
grinder (e.g. grinder or other suitable apparatus or mill).
Pre-treatment of the prepared biomass is performed in a reaction
vessel (or set of reaction vessels) supplied with prepared biomass
and acid/water in a predetermined concentration (or pH) and other
operating conditions. As shown in FIG. 6B, the pre-treated biomass
can be separated in a centrifuge into a liquid component (C5 stream
comprising primarily liquids with some solids) and a solids
component (C6 stream comprising liquids and solids such as lignin
and cellulose from which glucose can be made available by further
treatment).
[0052] Referring to FIGS. 7A and 7B, a treatment system and
fermentation system for the liquid component (C5 stream or
hydrolysate) of the pre-treated biomass is shown. As shown in FIG.
7B, according to an exemplary embodiment, the treatment system can
comprise filtration of the C5 stream to remove inhibitors (such as
furfural and acetic acid) and concentration of the C5 stream to
facilitate the efficient fermentation of sugars (e.g. xylose and
glucose). As shown in FIG. 8A, according to an exemplary
embodiment, the fermentation system can comprise the fermentation
of the C5 stream by the application of an ethanologen (i.e. an
organism shown as yeast cells) and agents (such as nutrients) for
the ethanologen to yield a fermentation product.
[0053] According to an exemplary embodiment, the fermentation
product is produced in the fermentation system by application of
the ethanologen to convert the sugars in the C5 stream (hydrolysate
of the pre-treated biomass) into ethanol. According to a preferred
embodiment, the ethanologen for the fermentation system may
comprise an organism (i.e. yeast) selected for efficient
fermentation of the xylose and glucose that is present in the C5
stream. According to a particularly preferred embodiment, the
ethanologen for the C5 stream may be a genetically modified
organism as described in U.S. Pat. No. 7,622,284, assigned to Royal
Nedalco B. V. According to an alternative embodiment, the
ethanologen may comprise a formulation or combination of organisms
(e.g. one type of yeast selected for fermentation of C5 sugars such
as xylose and one type of yeast selected for fermentation of C6
sugars such as glucose). According to exemplary embodiments, the
amount or loading (dose) of ethanologen (i.e. yeast cells) may be
varied in the operation of the fermentation system. Agents supplied
with the ethanologen may include antibiotics, supplemental or
accessory enzymes, urea, salts (such as zinc or magnesium salts),
or other component providing nutritional or other benefit to the
organism.
[0054] Referring to FIGS. 9A and 9B, the fermentation system may
operate in a batch, fed batch, continuous flow, or Other
arrangement. According to an exemplary embodiment, the fermentation
system will comprise at least one fermentation tank. According to
the exemplary embodiment shown in FIG. 9A, the fermentation system
comprises a set of tanks into which the treated C5 stream (i.e.
treated hydrolysate from pre-treated biomass, in a slurry) is
supplied, along with the ethanologen and nutrients (as needed). As
shown in FIGS. 9A and 9B, ethanologen (shown as yeast) is supplied
from a yeast propagation system comprising a tank (maintained under
operating conditions suitable for growth of a suitable quantity of
yeast/organism from seed or source). Fermentation is conducted
under operating conditions selected to facilitate the efficient
conversion of the sugars in the C5 stream/hydrolysate into ethanol.
operating conditions for the fermentation system will comprise
time, temperature, pH, solids loading and ethanologen loading.
[0055] According to an exemplary embodiment using batch
fermentation, as shown in FIG. 9A, the fermentation system
comprises multiple tanks and is configured so that fermentation can
be conducted simultaneously in multiple fermentation tanks. The
slurry (treated hydrolysate/C5 stream), ethanologen and nutrients
will be supplied to each of the fermentation tanks according to a
sequence. Fermentation will be performed for a designated period of
time under the designated operating conditions for each particular
tank; after fermentation has been completed in the particular tank,
the tank will then be emptied of fermentation product and cleaned.
According to a preferred embodiment, one tank will be available to
receive and be filled with slurry as it is produced; fermentation
will be taking place in at least one other tank; and another tank
in which fermentation has been completed may be being emptied and
readied to be filled and used for another fermentation. The
operating conditions for fermentation (as well as samples of the
slurry being fermented) may be monitored and controlled in each
fermentation tank.
[0056] According to an exemplary embodiment using continuous
fermentation, as shown in FIG. 9B, the fermentation system
comprises multiple tanks in a cascade arrangement. The fermentation
system is configured so that the slurry (treated hydrolysate/C5
stream) and ethanologen/nutrients are initially supplied to a first
tank. As fermentation proceeds in the tank, partially-fermented
slurry in the process of being fermented is flowed into the next
tank in sequence; when emptied from the final tank, the slurry has
been completely fermented into fermentation product. The operating
conditions for fermentation (as well as samples of the slurry being
fermented) may be monitored and controlled in each fermentation
tank.
[0057] The fermentation product (which may also be referred to as
beer or fermentation broth, or as comprising beer or fermentation
broth) will comprise ethanol and water, as well as unfermented
matter (e.g. any unfermented sugars) and non-fermentable matter
(e.g. residual lignin and other solids). The fermentation product
will also comprise in the form of particulate matter the
ethanologen (i.e. yeast cells) that was used to produce ethanol, as
well as other components produced by the fermentation system, for
example, such as glycerol (a product of fermentation) and acetic
acid.
[0058] As shown in FIG. 8B, according to an exemplary embodiment, a
treatment system for the fermentation product may also be provided.
The treatment system can comprise separation of the fermentation
product into a liquid component (i.e. a treated fermentation
product, which will comprise substantially ethanol and water) and a
solids component (which will comprise substantially solids matter
such as the ethanologen/yeast cells). According to a preferred
embodiment, as shown in FIG. 8B, the separation of the fermentation
product into the liquid component and solids component can be
performed on a centrifuge; according to other exemplary
embodiments, the separation may be performed in other apparatus (or
other equipment configured to separate solids and liquids). As
shown in FIG. 8B, the solids component from treatment comprising
the yeast cells can be supplied to and re-used in the fermentation
system (i.e. recycled for use in a fermentation tank) along with
additional or fresh yeast cells (if necessary).
[0059] As shown in FIGS. 2, 5A and 5B, the liquid component (or
treated fermentation product) from the treatment system can be
supplied to the distillation system, for distillation and
dehydration to allow recovery of ethanol.
[0060] FIGS. 10A through 10D show operating conditions for subject
parameters of the fermentation system according to an exemplary
embodiment of the system (configured for the fermentation of the
treated liquid component/C5 stream of biomass in the form of corn
cobs and stover, following acid pre-treatment and separation);
operating conditions are shown in the form of nested ranges
comprising an acceptable operating range (the outer/wide range
shown), a preferred operating range (the middle range shown), and a
particularly preferred operating range (the inner/narrow range
shown) for each subject condition or parameter.
[0061] FIG. 10A shows the temperature ranges for operation of a
fermentation system according to exemplary embodiments. According
to an exemplary embodiment, the operating temperature range is
about to about 37 degrees Celsius. According to a preferred
embodiment, the operating temperature is from about 30 to about 34
degrees Celsius. According to a particularly preferred embodiment,
the operating temperature is from about 31 to about 34 degrees
Celsius.
[0062] FIG. 10B shows the pH ranges for operation of a fermentation
system according to exemplary embodiments. According to an
exemplary embodiment, the pH range is about 3.7 to about 6.5.
According to a preferred embodiment, the pH is from about 4.5 to
about 6.0. According to a particularly preferred embodiment, the pH
is from about 5.4 to about 5.6.
[0063] FIG. 10C shows the yeast loading (in grams of dry yeast per
liter of hydrolysate) for operation of a fermentation system
according to exemplary embodiments (for example, a genetically
modified yeast derived from the organism disclosed in U.S. Pat. No.
7,622,284, incorporated by reference, assigned to Royal Nedalco, B.
V.). According to an exemplary embodiment, the yeast loading is
about 0.05 to about 35 grams per liter. According to a preferred
embodiment, the yeast loading is from about 5 to about 20 grams per
liter. According to a particularly preferred embodiment, the yeast
loading is from about 10 to about 15 grams per liter.
[0064] FIG. 10D shows the time for operation of a batch
fermentation system according to exemplary embodiments (excluding
of time to fill and empty the fermentation tank). According to an
exemplary embodiment, the fermentation time is about 12 to 144
hours. According to a preferred embodiment, the fermentation time
is about 18 to 96 hours. According to a particularly preferred
embodiment, the fermentation time is about 24 to 48 hours.
[0065] According to other alternative embodiments, for example,
using a different form or type of biomass or a different
ethanologen, the operating conditions for the fermentation system
may be varied as necessary to achieve efficient fermentation.
[0066] A series of examples were conducted according to an
exemplary embodiment of the fermentation system (as shown in FIGS.
11 through 14) in an effort to evaluate efficacy for fermentation
of sugars from the C5 stream (e.g. liquid component from separation
of pre-treated biomass). The ethanologen used in the examples was a
strain of Saccharomyces cerevisiae yeast altered to convert xylose
and glucose to ethanol (a genetically modified yeast derived from
an organism as described in U.S. Pat. No. 7,622,284 by Royal
Nedalco B. V., for example strain No. RWB218 and strain No.
RN1001). Data from the examples is shown in TABLES 4 through 7. The
biomass comprised corn cobs and stover.
EXAMPLE 1
[0067] The fermentation system was used in Example 1 to evaluate
the effect of ethanologen loading on the efficacy of the
ethanologen in the fermentation of xylose into ethanol, as
indicated in FIG. 11. The ethanologen was yeast (strain No.
RWB218.) A sample was prepared having an initial xylose
concentration of about 4.7 percent (by weight). The sample was
divided into subsamples, which were supplied with a yeast loading
between about 0.05 and 30 grams per liter (of sample) in a
fermentation system to produce a fermentation product. The
fermentation was conducted at approximately 32 degrees Celsius and
approximately pH 5.5 for approximately 48 hours. The subsamples
were analyzed for xylose concentration and ethanol concentration.
It was observed that at least about 5 grams per liter of yeast was
needed for sufficient fermentation of xylose to ethanol under the
operating conditions. The results are shown in FIG. 11 and TABLE
4.
EXAMPLE 2A
[0068] The fermentation system was used in Example 2A to evaluate
the efficacy of the ethanologen in the fermentation of xylose in a
hydrolysate from the liquid component (i.e. C5 stream) of
pre-treated biomass at varying levels of initial loading (i.e.
yeast concentration), as indicated in FIGS. 12A and 12B. The
ethanologen was yeast (strain No. RWB218.) A sample of the
hydrolysate was prepared including about 4.7 percent xylose (by
weight). The sample was divided into subsamples, which were
supplied with a yeast loading between about 0.5 and 30 grams per
liter (of sample) in a fermentation system to produce a
fermentation product. The fermentation was conducted at
approximately 32 degrees Celsius and approximately pH 5.5 for
approximately 72 hours. The subsamples were analyzed for xylose
concentration and ethanol concentration at 24 hours, 48 hours and
about 72 hours (the end of fermentation). It was observed that at
least about 5 grams per liter of yeast was needed for sufficient
fermentation of xylose to ethanol and that efficient fermentation
could be achieved at about 10 grams per liter under the operating
conditions. The results are shown in FIGS. 12A and 12B and TABLES
5A and 5B.
EXAMPLE 2B
[0069] The fermentation system was used in Example 2B to evaluate
the efficacy of the ethanologen in the fermentation of xylose in a
hydrolysate from the liquid component (i.e. C5 stream) of
pre-treated biomass at varying levels of initial loading (i.e.
yeast concentration), as indicated in FIGS. 13A and 13B. The
ethanologen was yeast (strain No. RN1001.) A sample of the
hydrolysate was prepared comprising about 3.1 to 3.2 percent xylose
(by weight) and less than 3800 PPM of acetic acid. The sample was
divided into subsamples, which were supplied with a yeast loading
between about 0.1 and 30 grams per liter (of sample) in a
fermentation system to produce a fermentation product. The
fermentation was conducted at approximately 32 degrees Celsius and
approximately pH 5.5 for approximately 72 hours. The subsamples
were analyzed for xylose concentration and ethanol concentration at
6 hours, 12 hours, 18 hours, 24 hours, 48 hours and about 72 hours
(the end of fermentation). It was observed that at least about 1
gram per liter of yeast was needed for sufficient fermentation of
xylose to ethanol under the operating conditions. The results are
shown in FIGS. 13A and 13B and TABLE 6.
EXAMPLE 3
[0070] The fermentation system was used in Example 3 to evaluate
the effect of xylose concentration on the efficacy (and xylose
tolerance) of the ethanologen in the fermentation of xylose into
ethanol, as indicated in FIG. 14. The ethanologen was yeast (strain
No. RWB218.) A sample was prepared using a sterile medium
comprising 1 gram per liter (of sample) yeast extract and 1 gram
per liter (of sample) soy peptone and an initial yeast loading
(inoculation rate) of about 0.59 grams per liter (of sample). The
sample was divided into subsamples and supplied to a fermentation
system to produce a fermentation product; subsamples were fermented
with initial xylose concentrations between about 2.3 percent and
17.6 percent (by weight). The fermentation was conducted at
approximately 32 degrees Celsius and approximately pH 5.5 for
approximately 72 hours. The subsamples were analyzed for xylose
concentration and ethanol concentration at 72 hours (the end of
fermentation). It was observed that the yeast was able to convert
xylose to ethanol at a xylose concentration at and below
approximately 11.3 percent (by weight), but was no longer efficient
at a xylose concentration at or above approximately 13.6 percent
(by weight) under the operating conditions. The results are shown
in FIG. 14 and TABLE 7.
[0071] The embodiments as disclosed and described in the
application (including the FIGURES and Examples) are intended to be
illustrative and explanatory of the present inventions.
Modifications and variations of the disclosed embodiments, for
example, of the apparatus and processes employed (or to be
employed) as well as of the compositions and treatments used (or to
be used), are possible; all such modifications and variations are
intended to be within the scope of the present inventions.
* * * * *