U.S. patent application number 12/022831 was filed with the patent office on 2008-12-04 for continuous counter-current organosolv processing of lignocellulosic feedstocks.
This patent application is currently assigned to Lignol Innovations Ltd.. Invention is credited to Alex Berlin, Gordon Gjennestad, Christer Hallberg, John Ross MacLachlan, Donald O'Connor, Edward Kendall Pye, Michael Rushton.
Application Number | 20080299629 12/022831 |
Document ID | / |
Family ID | 40074487 |
Filed Date | 2008-12-04 |
United States Patent
Application |
20080299629 |
Kind Code |
A1 |
Hallberg; Christer ; et
al. |
December 4, 2008 |
CONTINUOUS COUNTER-CURRENT ORGANOSOLV PROCESSING OF LIGNOCELLULOSIC
FEEDSTOCKS
Abstract
A modular process for organosolv fractionation of
lignocellulosic feedstocks into component parts and further
processing of said component parts into at least fuel-grade ethanol
and four classes of lignin derivatives. The modular process
comprises a first processing module configured for
physico-chemically digesting lignocellulosic feedstocks with an
organic solvent thereby producing a cellulosic solids fraction and
a liquid fraction, a second processing module configured for
producing at least a fuel-grade ethanol and a first class of novel
lignin derivatives from the cellulosic solids fraction, a third
processing module configured for separating a second class and a
third class of lignin derivatives from the liquid fraction and
further processing the liquid fraction to produce a distillate and
a stillage, a fourth processing module configured for separating a
fourth class of lignin derivatives from the stillage and further
processing the stillage to produce a sugar syrup.
Inventors: |
Hallberg; Christer;
(Vancouver, CA) ; O'Connor; Donald; (Delta,
CA) ; Rushton; Michael; (West Vancouver, CA) ;
Pye; Edward Kendall; (Vancouver, CA) ; Gjennestad;
Gordon; (Vancouver, CA) ; Berlin; Alex;
(Burnaby, CA) ; MacLachlan; John Ross; (Burnaby,
CA) |
Correspondence
Address: |
FASKEN MARTINEAU DUMOULIN, LLP
2900 - 550 Burrard Street
VANCOUVER
BC
V6C 0A3
CA
|
Assignee: |
Lignol Innovations Ltd.
|
Family ID: |
40074487 |
Appl. No.: |
12/022831 |
Filed: |
January 30, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12016932 |
Jan 18, 2008 |
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12022831 |
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11839378 |
Aug 15, 2007 |
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12016932 |
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60941220 |
May 31, 2007 |
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Current U.S.
Class: |
435/161 ;
530/500 |
Current CPC
Class: |
C08L 5/04 20130101; C12M
21/12 20130101; D21H 17/00 20130101; C12M 21/04 20130101; C12M
45/09 20130101; C12P 7/00 20130101; Y02E 50/16 20130101; C02F 11/04
20130101; B01D 3/14 20130101; C08H 8/00 20130101; Y02W 10/23
20150501; C12P 5/023 20130101; Y02E 50/17 20130101; Y02E 50/343
20130101; C08H 6/00 20130101; C12P 7/40 20130101; C07H 19/00
20130101; C12M 45/06 20130101; C12P 7/08 20130101; Y02E 50/30
20130101; C08L 3/02 20130101; Y02E 50/10 20130101; C12M 45/02
20130101; C12P 7/10 20130101; C12P 19/14 20130101; B01D 11/0226
20130101; C02F 3/34 20130101; C13K 1/02 20130101; C12P 7/54
20130101; Y02W 10/20 20150501; B01D 3/002 20130101; B01D 11/0288
20130101; C12M 45/04 20130101 |
Class at
Publication: |
435/161 ;
530/500 |
International
Class: |
C12P 7/06 20060101
C12P007/06; C08L 97/00 20060101 C08L097/00 |
Claims
1. A modular process for organosolv fractionation of a
lignocellulosic feedstock into component parts and further
processing of said component parts; the modular process comprising:
a first processing module provided with a first series of steps for
receiving, physically screening, and physico-chemically digesting a
lignocellulosic feedstock with an organic solvent separately
provided thereto thereby extracting component parts therefrom, and
separating said component parts into a cellulosic solids fraction
and a first liquid fraction; a second processing module provided
with a second series of steps for producing at least a fuel-grade
ethanol and a plurality of a first class of lignin derivatives from
said cellulosic solids fraction; a third processing module provided
with a third series of steps comprising at least a first step for
separating the first liquid fraction into a second solids fraction
comprising a plurality of a second class of lignin derivatives and
a first filtrate, a second step for separating the first filtrate
into a third solids fraction comprising a plurality of a third
class of lignin derivatives and a second filtrate, and a third step
for separating furfurals from said second filtrate, a fourth step
for recovering a portion of the organic solvent from the second
filtrate by distillation thereby producing a first stillage; and a
fourth processing module provided with a fourth series of steps for
separating the first stillage into at least an acetic
acid-containing liquid fraction, a plurality of a fourth class of
lignin derivatives, a lipophylic extractives fraction, a
monosaccharide sugar syrup, and a solid waste material.
2. A modular process according to claim 1, additionally provided
with a fifth processing module comprising an anaerobic digestion
module configured for processing at least one of the liquid
fraction, the sugar syrup, and the waste material separated in the
fourth processing module, into at least a collectable biogas and a
liquid effluent.
3. A modular process according to claim 1, wherein the organic
solvent comprises at least one solvent selected from the group
containing short-chain alcohols and ketones.
4. A modular process according to claim 3, wherein the organic
solvent comprises at least one short-chain alcohol selected from
the group containing methanol, ethanol, butanol, propanol, and
aromatic alcohols.
5. A modular process according to claim 3, wherein the organic
solvent comprises at least acetone.
6. A modular process according to claim 1, wherein the first
processing module is configured to continuously receive, physically
process, and physico-chemically digest a lignocellulosic feedstock
thereby continuously producing the cellulosic solids fraction and
the first liquid fraction.
7. A modular process according to claim 6, wherein the first series
of steps comprises steps for physically separating
non-lignocellulosic materials from the lignocellulosic feedstock,
delivering said lignocellulosic feedstock into a first end of a
heatable and pressurizable digestion vessel, said vessel heated and
pressurized, conveying said lignocellulosic feedstock to about a
second end of the digestion vessel, commingling said
lignocellulosic feedstock with said organic solvent and producing
therefrom the cellulosic solids fraction and the first liquid
fraction, discharging the solids fraction from about the second end
of the digestion vessel, and discharging the first liquid fraction
from about the first end of the digestion vessel.
8. A modular process according to claim 7, wherein the
lignocellulosic feedstock is commingled with the organic solvent by
a method selected from the group containing one of: (a) a first
method comprising counterflowing the organic solvent from about the
second end to about the first end the digestion vessel, and (b) a
second method comprising re-circulating the organic solvent
therewithin and about the digestion vessel.
9. A modular process according to claim 7, wherein the first series
of steps additionally comprises steps for first controllably
saturating the lignocellulosic feedstock with a heated organic
solvent for a selected period of time, and then for controllably
removing the heated organic solvent from the lignocellulosic
feedstock prior to delivering said lignocellulosic feedstock into
about the first end of the digestion vessel
10. A modular process according to claim 1, wherein the second
series of steps comprises steps for controllably reducing the
viscosity of the cellulosic solids fraction, controllably digesting
the reduced-viscosity cellulosic solids fraction to produce a
second liquid fraction comprising at least soluble sugars,
controllably fermenting the second liquid fraction to produce a
beer therefrom, distilling the beer to produce and separate a
fuel-grade ethanol and a second stillage therefrom, and separating
the first class of lignin derivatives from said second
stillage.
11. A modular process according to claim 10, herein the second
series of steps additionally comprises a step for adding an enzyme
preparation configured for controllably digesting the
reduced-viscosity cellulosic solids fraction, said enzyme
preparation comprising at least one enzyme selected from the group
consisting of endo-.beta.-1,4-glucanases, cellobiohydrolases,
cellulases, hemicellulases, .beta.-glucosidases,
.beta.-xylosidases, xylanases, .alpha.-amylases, .beta.-amylases,
pullulases, and esterases.
12. A modular process according to claim 10, wherein the second
series of steps additionally comprises a step for adding an
inoculum preparation configured for controllably fermenting the
second liquid fraction, the inoculum preparation comprising at
least one microbial strain selected from a group containing yeast
strains, fungal strains and bacterial strains.
13. A modular process according to claim 12, herein the inoculum
preparation comprises at least one microbial strain selected from a
group containing naturally occurring and genetically engineered
Saccharomyces spp. strains, Pichia spp. strains, Aspergillus spp.
strains, Trichoderma spp. strains, Escherichia coli strains,
Zymomonas spp. strains, Clostridium spp. strains, and
Corynebacterium spp. strains.
14. A modular process according to claim 10, wherein said digestion
step and said fermentation step are concurrently performed within a
single vessel.
15. A modular process according to claim 10, wherein said
de-lignified second stillage is used to controllably reduce the
viscosity of the cellulosic solids fraction.
16. A modular process according to claim 1, wherein the third
series of steps additionally comprises steps for controllably
intermixing at least a portion of the recovered organic solvent
with a portion of the fuel-grade ethanol produced by the second
series of steps, and then recycling the intermixed recovered
organic solvent and fuel-grade ethanol into the first processing
module.
17. A modular process according to claim 1, additionally provided
with a sixth processing module comprising a fermentation module
configured for receiving, fermenting and distilling therein said
monosaccharide sugar syrup, and for separating therefrom a
distillate comprising at least 1,3-propanediol and a stillage
comprising at least lactic acid.
18. A modular process according to claim 2, wherein the anaerobic
digestion module comprises a first step of biologically liquifying
said solid waste material thereby producing a third liquid
fraction, a second step of biologically acidifying the third liquid
fraction thereby producing a liquid organic acid stream therefrom,
a third step of biologically acetifying the liquid organic stream
thereby producing at least acetic acid, and a fourth step of
biologically producing at least a biogas and a liquid effluent from
said acetic acid.
19. A modular process according to claim 18, wherein: (a) the first
step is additionally provided with an inoculation step wherein an
inoculum comprising at least one microbial strain selected from a
group containing at least naturally occurring and genetically
engineered Enterobacter sp., is controllably commingled with said
solid waste material; (b) the second step is additionally provided
with an inoculation step wherein an inoculum comprising at least
one microbial strain selected from a group containing at least
naturally occurring and genetically engineered Bacillus sp.,
Lactobacillus sp. and Streptococcus sp., is controllably commingled
with said third liquid fraction; (c) the third step is additionally
provided with an inoculation step wherein an inoculum comprising at
least one microbial strain selected from a group containing at
least naturally occurring and genetically engineered Acetobacter
sp., Gluconobacter sp., and Clostridium sp., is controllably
commingled with said liquid organic acid stream; and (d) the fourth
step is additionally provided with an inoculation step wherein an
inoculum comprising at least one microbial strain selected from a
group containing at least naturally occurring and genetically
engineered Methanobacteria sp., Methanococci sp., and Methanopyri
sp., is controllably commingled with said at least acetic acid.
20. A modular process according to claim 18, wherein a portion of
the liquid monosaccharide sugar syrup produced in the fourth
processing module is controllably delivered to the second step of
the anaerobic digestion module for acidification therein.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of our prior application
Ser. No. 12/016,932 filed Jan. 18, 2008 currently pending, and
claims the benefit of application Ser. Nos. 11/839,378 filed Aug.
15, 2007 and 60/941,220 filed May 31, 2007.
FIELD OF THE INVENTION
[0002] This invention relates to fractionation of lignocellulosic
feedstocks into component parts. More particularly, this invention
relates to processes, systems and equipment configurations for
recyclable organosolv fractionation of lignocellulosic material for
continuous controllable and manipulable production and further
processing of lignins, monosaccharides, oligosaccharides,
polysaccharides and other products derived therefrom.
BACKGROUND OF THE INVENTION
[0003] Industrial processes for production of cellulose-rich pulps
from harvested wood are well-known and typically involve the steps
of physical disruption of wood into smaller pieces and particles
followed by chemical digestion under elevated temperatures and
pressures to dissolve and separate the lignins from the constituent
cellulosic fibrous biomass. After digestion has been completed, the
solids comprising the cellulosic fibrous pulps are separated from
the spent digestion liquids which commonly referred to as black
liquors and typically comprise organic solvents, solubilized
lignins, solid and particulate monosaccarides, oligosaccharides,
polysaccharides and other organic compounds released from the wood
during the chemical digestion. The cellulosic fibrous pulps are
typically used for paper manufacturing while the black liquors are
usually processed to remove the soluble lignins after which, the
organic solvents are recovered, purified and recycled. The lignins
and remaining stillage from the black liquors are typically handled
and disposed of as waste streams.
[0004] During the past two decades, those skilled in these arts
have recognized that lignocellulosic materials including gymnosperm
and angiosperm substrates (i.e., wood) as well as field crop and
other herbaceous fibrous biomass, waste paper and wood containing
products and the like, can be potentially fractionated using
biorefining processes incorporating organosolv digestion systems,
into multiple useful component parts that can be separated and
further processed into high-value products such as fuel ethanol,
lignins, furfural, acetic acid, purified monosaccharide sugars
among others (Pan et al., 2005, Biotechnol. Bioeng. 90: 473-481;
Pan et al., 2006, Biotechnol Bioeng. 94: 851-861; Berlin et al.,
2007, Appl. Biochem. Biotechnol. 136-140:267-280; Berlin et al.,
2007, J. Chem. Technol Biotechnol. 82: 767-774). Organosolv pulping
processes and systems for lignocellulosic feedstocks are well-known
and are exemplified by the disclosures in U.S. Pat. Nos. 4,941,944;
5,730,837; 6,179,958; and 6,228,177. Although it appears that
biorefining using organosolv systems has considerable potential for
large-scale fuel ethanol production, the currently available
processes and systems are not yet economically feasible because
they require expensive pretreatment steps and currently produce
only low-value co-products (Pan et al., 2006, J. Agric. Food Chem.
54: 5806-5813; Berlin et al., 2007, Appl. Biochem. Biotechnol.
136-140:267-280; Berlin et al., 2007, J. Chem. Technol Biotechnol.
82: 767-774).
SUMMARY OF THE INVENTION
[0005] The exemplary embodiments of the present invention relate to
systems, processes and equipment configurations for receiving and
controllably commingling lignocellulosic feedstocks with
counter-flowing organic solvents while providing suitable
temperature and pressure conditions for fractionating the
lignocellulosic feedstocks into component parts which are then
subsequently separated. The separated component parts are further
selectively, controllably and manipulably processed.
[0006] According to one exemplary embodiment of the present
invention, there is provided a modular processing system for
receiving therein and fractionating a lignocellulosic feedstock
into component parts, separating the component parts into at least
a solids fraction and a liquids fraction, and then separately
processing the solids and liquids fractions to further produce
useful products therefrom. Suitable modular processing systems of
the present invention comprise at least: [0007] a first module
comprising a plurality of equipment configured for: (a) receiving
and processing lignocellulosic fibrous feedstocks, then (b)
commingling under controlled temperature and pressure conditions
the processed feedstocks with suitable solvents configured for
physico-chemically disrupting the lignocellulosic feedstock into a
solids fraction comprising mostly cellulosic pulps and a liquid
fraction comprising spent solvents containing therein at least
lignins, lignin-containing compounds, monosaccharides,
oligosaccharides and polysaccarides, dissolved and suspended solids
comprising hemicelluloses and celluloses and other organic
compounds, and (c) providing a first output stream comprising the
solids fraction and a second output stream comprising the liquids
fraction; [0008] a second module comprising a plurality of
equipment configured for: (d) receiving and controllably adjusting
the viscosity of the solids fraction, (e) commingling the
adjusted-viscosity solids fraction with suitable enzymes selected
for saccharification of the cellulosic pulps into a liquid stream
comprising monosaccharides and/or oligosaccharides (f) commingling
the monosaccharides and/or oligosaccharides liquid stream with
suitable fermenting microorganisms for production of an ethanol
stream therefrom, (g) refining the ethanol to produce at least a
fuel grade ethanol stream and de-alcoholized solvent stream, (h)
further processing the de-alcoholized solvent-stillage stream to
precipitate and separate a first lignin fraction therefrom, and (i)
recycling the de-lignified de-alcoholized solvent stream for
controllably adjusting the viscosity of fresh solids fraction
coming into the second module from the first output stream of the
first module; [0009] a third module comprising a plurality of
equipment configured for (j) receiving the liquids fraction from
the first module and controllably intermixing a supply of water
with the liquids fraction thereby precipitating a second lignin
fraction therein, (k) separating the second lignin fraction from
the liquids fraction thereby producing a liquid filtrate, (l)
refining the liquid filtrate in a distillation tower thereby by
capturing at least firstly, a portion of the suitable solvents
commingled with the lignocellulosic feedstock in the first module,
secondly, a furfural fraction, and thirdly, a stillage fraction,
(m) controllably recharging the captured portion of the suitable
solvents with a portion of the fuel ethanol produced in the second
module; and [0010] a fourth module comprising a plurality of
equipment configured for receiving the stillage fraction from the
third module and separating therefrom at least acetic acid
condensate, sugar syrups, a third lignin fraction, and a
semi-solid/solid waste material.
[0011] According to one aspect, the plurality of equipment in the
first module is configured to continuously receive and convey
therethrough in one direction a lignocellulosic feedstock ending
with the discharge of a cellulosic solids fraction, while
concurrently counterflowing a selected suitable solvent through the
equipment in an opposite direction to the conveyance of the
lignocellulosic feedstock ending in a discharge of a spent solvents
liquid fraction.
[0012] According to another aspect, the plurality of equipment in
the first module is configured to receive a batch of a
lignocellulosic feedstock and to continuously cycle therethrough a
selected suitable solvent therethrough until a suitable solids
fraction is produced from the batch of lignocellulosic
feedstock.
[0013] According to yet another aspect, the plurality of equipment
in the second module is configured to sequentially: (a) receive and
reduce the viscosity of the cellulosic solids fraction discharged
from the first module, then (b) progressively saccharify the
cellulosic solids into suspended solids, dissolved solids,
hemicelluloses, polysaccharides, oligosaccharides thereby producing
a liquid stream primarily comprising monosaccharides, (c) ferment
the liquid stream, (d) distill and refine the fermentation beer to
separate the beer into at least a fuel-grade ethanol and/or other
fuel alcohols such as butanol, and a stillage stream, (e) delignify
the stillage stream, and (f) recycle the delignified stillage
stream for reducing the viscosity of fresh incoming cellulosic
solids fraction discharged from the first module.
[0014] According to a further aspect, the plurality of equipment in
the second module may be optionally configured to sequentially: (a)
receive and reduce the viscosity of the cellulosic solids fraction
discharged from the first module, then (b) concurrently saccharify
the cellulosic solids into monosaccharides while fermenting the
monosaccharides in the same vessel, (c) distill and refine the
fermentation beer to separate the beer into at least a fuel-grade
ethanol and a stillage stream, (d) de-lignify the stillage stream,
and (f) recycle the de-lignified stillage stream for reducing the
viscosity of fresh incoming cellulosic solids fraction discharged
from the first module.
[0015] According to another aspect, the modular processing system
of the present system may be additionally provided with a fifth
module comprising an anaerobic digestion system provided with a
plurality of equipment configured for receiving the
semi-solid/solid waste material from the fourth module, then
liquifying and gasifying the waste material for the production of
methane, carbon dioxide, and water.
[0016] According to another exemplary embodiment of the present
invention, there is provided processes for fractionating a
lignocellulosic feedstock into component parts. First, foreign
materials exemplified by gravel and metal are separated using
suitable means, from the incoming lignocellulosic material. An
exemplary separating means is screening. If so desired, the
screened lignocellulosic feedstock may be further screened to
remove fines and over-size materials. Second, the screened
lignocellulosic feedstock are controllably heated for example by
steaming after which, the heated lignocellulosic feedstock is
de-watered and then pressurized. Third, the heated and de-watered
lignocellulosic feedstock is commingled and then impregnated with a
suitable organic solvent. Fourth, the commingled lignocellulosic
feedstock and organic solvent are controllably cooked within a
controllably pressurized and temperature-controlled system for a
selected period of time. During the cooking process, lignins and
lignin-containing compounds contained within the commingled and
impregnated lignocellulosic feedstock will be dissolved into the
organic solvent resulting in the cellulosic fibrous materials
adhered thereto and therewith to disassociate and to separate from
each other. The cooking process will also release monosaccharides,
oligosaccharides and polysaccarides and other organic compounds for
example acetic acid, in solute and particulate forms, from the
lignocellulosic materials into the organic solvents. Those skilled
in these arts refer to such organic solvents containing therein
lignins, lignin-containing compounds, monosaccharides,
oligosaccharides and polysaccarides and other organic compounds, as
"black liquors" or "spent liquors".
[0017] According to one aspect, controllably counter-flowing the
organic solvent against the incoming lignocellulosic feedstock
during the cooking causes turbulence that facilitates and speeds
the dissolution and disassociation of the lignins and
lignin-containing components from the lignocellulosic feedstock.
However, it is within the scope of this invention to alternatively
provide turbulence during the cooking process with a controllable
flow of organic solvent directed in the same direction as the flow
of lignocellulosic feedstock, i.e., a concurrent flow, thereby
controllably intermixing the solvent and lignocellulosic feedstock
together. It is also within the scope of this invention to
controllably partially remove the organic solvent during the
cooking process and to replace it with fresh organic solvent.
[0018] According to another aspect, the lignocellulosic feedstock
may comprise at least one of physically disrupted angiosperm,
gymnosperm, field crop fibrous biomass segments exemplified by
chips, saw dust, chunks, shreds and the like. It is within the
scope of this invention to provide mixtures of physically disrupted
angiosperm, gymnosperm, field crop fibrous biomass segments.
[0019] According to yet another aspect, the lignocellulosic
feedstock may comprise at least one of waste paper, wood scraps,
comminuted wood materials, wood composites and the like. It is
within the scope of this invention to intermix lignocellulosic
fibrous biomass materials with one or more of waste paper, wood
scraps, comminuted wood materials, wood composites and the
like.
[0020] According to a further aspect, the liquor to wood ratio,
operating temperature, solvent concentration and reaction time may
be controllably and selectively adjusted to produce pulps and/or
lignins having selectable target physico-chemical properties and
characteristics.
[0021] According to another exemplary embodiment of the present
invention, there are provided processes and systems for separating
the disassociated cellulosic fibers i.e., pulp, from the black
liquors, and for further and separately processing the pulp and the
black liquors. The separation of pulp and black liquors may be done
while the materials are still pressurized from the cooking process
or alternatively, pressure may be reduced to about ambient pressure
after which the pulp and black liquors are separated.
[0022] According to one aspect, the cellulosic fibrous pulp is
recoverable for use in paper making and other such processes.
[0023] According to another aspect, there are provided processes
and systems for further selectively and controllably processing the
cellulosic pulps produced as disclosed herein. The pH and/or the
consistency of the recovered pulp may be adjusted as suitable to
facilitate the hydrolysis of celluloses to monosaccharides, i.e.,
glucose moieties in hydrolysate solutions. Exemplary suitable
hydrolysis means include enzymatic, microbial, chemical hydrolysis
and combinations thereof.
[0024] According to yet another aspect, there are provided
processes and systems for producing ethanol from the monosaccarides
hydrolyzed from the cellulosic fibrous pulp, by fermentation of the
hydrolysate solutions. It is within the scope of this invention to
controllably provide inocula comprising one or more selected
strains of Saccharomyces spp. to facilitate and enhance the rates
of fermentation and/or fermentation efficiencies and/or
fermentation yields.
[0025] According to a further aspect, there are provided processes
and systems for concurrently saccharifying and fermenting the
cellulosic pulps produced as disclosed herein. It is within the
scope of the present invention to controllably hydrolyze the
cellulosic fibrous pulps into monosaccharides by providing suitable
hydrolysis means exemplified by enzymatic, microbial, chemical
hydrolysis and combinations thereof, while concurrently and
controllably fermenting the monosaccharide moieties produced
therein. It is within the scope of this invention to controllably
provide inocula comprising one or more selected strains of
Saccharomyces spp. to facilitate and enhance the rates of
concurrent fermentation and/or fermentation efficiencies and/or
fermentation yields.
[0026] According to a further aspect, there are provided processes
and systems for further processing the ethanol produced from the
fermentation of the hydrolysate solutions. Exemplary processes
include concentrating and purifying the ethanol by distillation,
and de-watering or dehydration by passing the ethanol through at
least one molecular sieve.
[0027] According to a further exemplary embodiment of the present
invention, there are provided processes and systems for recovering
lignins and lignin-containing compounds from the black liquors. An
exemplary process comprises cooling the black liquor immediately
after separation from the cellulosic fibrous pulp, in a plurality
of stages wherein each stage, heat is recovered with suitable
heat-exchange devices and organic solvent is recovered using
suitable solvent recovery apparatus as exemplified by evaporation
and cooling devices. The stillage, i.e., the cooled black liquors
from which at least some organic solvent has been recovered, are
then further cooled, pH adjusted (e.g. increasing acidity) and then
rapidly diluted with water to precipitate lignins and
lignin-containing compounds from the stillage. The precipitated
lignins are subsequently washed at least once and then dried.
[0028] According to one aspect, the de-lignified stillage is
processed through a distillation tower to evaporate remaining
organic solvent, and to concurrently separate and concentrate
furfural. The remaining stillage is removed from the bottom of the
distillation tower. It is within the scope of the present invention
to optionally divert at least a portion of the de-lignified
stillage from the distillation tower input stream into the ethanol
production stream for producing ethanol therefrom. Alternatively or
optionally, at least a portion of the remaining stillage removed
from the bottom of the distillation tower may be diverted into the
ethanol production stream for producing ethanol therefrom.
[0029] According to another aspect, the stillage recovered form the
bottom of the solvent recovery column, is further processed by: (a)
decanting to recover complex organic extractives as exemplified by
phytosterols, oils and the like, and then (b) evaporating the
decanted stillage to produce (c) a stillage evaporate/condensate
comprising acetic acid, and (d) a stillage syrup containing therein
dissolved monosaccharides. The stillage syrup may be decanted to
recover (e) novel previously unknown low molecular weight lignins.
The decanted stillage syrup may be optionally evaporated to recover
dissolved sugars.
[0030] It is within the scope of this invention to further process
the recovered organic solvent by purification and concentration
steps to make the recovered organic solvent useful for recycling
back into continuous incoming lignocellulosic feedstock.
[0031] According to one aspect, an organic solvent is intermixed
and commingled with the lignocellulosic feedstock for a selected
period of time to pre-treat the lignocellulosic feedstock prior to
commingling and impregnation with the counter-flowing (or
alternatively, concurrently flowing) organic solvent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The present invention will be described in conjunction with
reference to the following drawings in which:
[0033] FIG. 1 is a schematic flowchart of an exemplary embodiment
of the present invention of a modular continuous counter-flow
system for processing a lignocellulosic feedstock;
[0034] FIG. 2 is a schematic flowchart of the system from FIG. 1
additionally provided with a device for optionally diverting the
sugar output stream to (a) the fuel ethanol production module, and
(b) an anaerobic digestion module;
[0035] FIG. 3 is schematic flowchart showing an alternative
configuration of the fuel ethanol production module for concurrent
saccharification and fermentation processes within a single
vessel;
[0036] FIG. 4 is a schematic flowchart of an exemplary anaerobic
digestion module suitable for cooperating with the modular
continuous counter-flow system of the present invention for
processing a lignocellulosic feedstock;
[0037] FIG. 5 is a schematic flowchart of a continuous counter-flow
processing system of the process re-configured into a batch
through-put system;
[0038] FIG. 6 is a schematic flowchart showing an alternative
configuration for the batch throughput system shown in FIG. 5;
[0039] FIG. 7 shows plots illustrating the simultaneous
saccharification and fermentation (SSF) of organosolv-pretreated
aspen (Populus tremuloides) chips: (a) % theoretical yield of
ethanol produced from the resultant aspen pulps vs. time, and (b)
the ethanol concentration in beers vs. time, produced during SSF of
the aspen pulps;
[0040] FIG. 8 shows plots illustrating the SSF of
organosolv-pretreated British Columbian beetle-killed lodgepole
pine (Pinus contorta) chips: (a) % theoretical yield of ethanol
produced from the resultant beetle-killed lodgepole pine pulps vs.
time, and (b) the ethanol concentration in beers vs. time, produced
during SSF of the resultant beetle-killed lodgepole pine pulps;
and
[0041] FIG. 9 shows plots illustrating the simultaneous
saccharification and fermentation (SSF) of organosolv-pretreated
wheat straw and switchgrass lignocellulosic feedstocks: (a) %
theoretical yield of ethanol produced from the resultant cellulosic
pulps vs. time, and (b) the ethanol concentration in beers vs.
time, produced during SSF of the cellulosic pulps.
DETAILED DESCRIPTION OF THE INVENTION
[0042] Exemplary embodiments of the present invention relate to
systems, processes and equipment configurations for receiving and
controllably commingling lignocellulosic feedstocks with
counter-flowing organic solvents, thereby fractionating the
lignocellulosic feedstocks into component parts which are then
subsequently separated. The separated component parts are further
selectively, controllably and manipulably processed. The exemplary
embodiments of the present invention are particularly suitable for
separating out from lignocellulosic feedstocks at least four
structurally distinct classes of lignin component parts with each
class comprising multiple derivative lignin compounds, while
concurrently providing processes for converting other component
parts into at least fuel-grade ethanol, furfurals, acetic acid, and
monosaccharide and/or oligosaccharides sugar streams.
[0043] An exemplary modular processing system of the present
invention is shown in FIG. 1 and generally comprises four modules
A-D wherein the first module A is configured for receiving and
processing lignocellulosic feedstocks into a solids fraction and a
liquids fraction, the second module B is configured for receiving
the solids fraction discharged from the first module A and
producing therefrom at least a fuel ethanol output stream 100 and a
first class of lignin derivatives 120 referred to hereafter as a
medium molecular weight lignin (i.e., MMW lignin), the third module
C is configured for receiving the liquid fraction from the first
module A and separating out at least a second class of lignin
derivatives 170 referred to hereafter as high molecular weight
lignins (i.e., HMW lignins), after which the filtrate is separated
into at least recyclable distilled solvent, furfurals 190, and a
stillage, and the fourth module D is configured for receiving and
separating the stillage from the third module C into at least
acetic acid 210, a third class of lignin derivatives 230 referred
to hereafter as low molecular weight lignins (i.e., LMW lignins), a
sugar syrup stream 247 from which is decanted and separated a
fourth class of lignin derivatives 245 referred to hereafter as
very-low molecular weight lignins (i.e., VLMW lignins), and a
semi-solid/solid waste material 226.
[0044] The first module A as exemplified in FIG. 1 is provided with
a bin 10 configured for receiving and temporarily storing
lignocellulosic feedstocks while continually discharging the
feedstock into a conveyance system provided with a separating
device 20 configured for removing pebbles, gravel, metals and other
debris. A suitable separating device is a screening apparatus. The
separating device 20 may be optionally configured for sizing the
lignocellulosic feedstock into desired fractions. The processed
lignocellulosic feedstock is then conveyed with a first auger
feeder 30 into a first end of a digestion/extraction vessel 40 and
then towards the second end of the digestion/extraction vessel 40.
The vessel 40 is provided with an inlet approximate the second end
for receiving a pressurized stream of a suitable heated
digestion/extraction solvent which then counterflows against the
movement of the lignocellulosic feedstock through the vessel 40
thereby providing turbulence and commingling of the solvent with
the feedstock. Alternatively, the inlet for receiving the
pressurized stream of heated digestion/extraction solvent may be
provided about the first end of the digestion/extraction vessel 40
or further alternatively, interposed the first and second ends of
the digestion/extraction vessel 40. It is suitable to use organic
solvents for the processes of the present invention. Exemplary
suitable organic solvents include methanol, ethanol, propanol,
butanol, acetone, and the like. If so desired, the organic solvents
may be additionally controllably acidified with an inorganic or
organic acid. If so desired, the pH of the organic solvents may be
additionally controllably manipulated with an inorganic or organic
base. The vessel 40 is controllably pressurized and temperature
controlled to enable manipulation of pressure and temperature so
that target cooking conditions are provided while the solvent is
commingling with the feedstock. Exemplary cooking conditions
include pressures in the range of about 15-30 bar (g), temperatures
in the range of about 120-350.degree. C., and pHs in the range of
about 1.5-5.5. During the cooking process, lignins and
lignin-containing compounds contained within the commingled and
impregnated lignocellulosic feedstock will be dissolved into the
organic solvent resulting in the cellulosic fibrous materials
previously adhered thereto and therewith to disassociate and to
separate from each other. Those skilled in these arts will
understand that in addition to the dissolution of lignins and
lignin-containing polymers, the cooking process will release
monosaccharides, oligosaccharides and polysaccharides and other
organic compounds for example acetic acid, furfural,
5-hydroxymethyl furfural (5-HMF), other organic acids such as
formic and levulinic acids in solute and particulate forms, from
the lignocellulosic materials into the organic solvents. Those
skilled in these arts refer to such organic solvents containing the
lignins, lignin-containing compounds, monosaccharides,
oligosaccharides, polysaccharides, hemicelluloses and other organic
compounds extracted from the lignocellulosic feedstock, as "black
liquors" or "spent liquors". The disassociated cellulosic fibrous
materials released from the feedstock are conveyed to the second
end of the vessel 40 where they are discharged via a second auger
feeder 50 which compresses the cellulosic fibrous materials into a
solids fraction, i.e., a pulp which is then conveyed to the second
module B. The black liquors are discharged as a liquid fraction
from about the first end of the digestion/extraction vessel 40 into
a pipeline 47 for conveyance to the third module C.
[0045] The second module B is provided with a mixing vessel 60
wherein the viscosity of solids fraction, i.e., pulp discharged
from the first module A is controllably reduced to a selected
target viscosity, by commingling with a recovered recycled solvent
stream delivered by a pipeline 130 from a down-stream component of
module B. The reduced viscosity pulp is then transferred to a
digestion vessel 70 where a suitable enzymatic preparation is
intermixed and commingled with the pulp for progressively breaking
down the cellulosic fibers, suspended solids and dissolved solids
into hemicelluoses, polysaccharides, oligosaccharides and
monosaccharides. A liquid stream comprising these digestion
products is transferred from the digestion vessel 70 to a
fermentation vessel 80 and is commingled with a suitable microbial
inocula selected for fermentation of hexose and pentose
monosaccharides in the liquid stream thereby producing a
fermentation beer comprising at least a short-chain alcohol
exemplified by ethanol, residual sediments and lees. The
fermentation beer is transferred to a first distillation tower 90
for refining by volatilizing then distilling and separately
collecting from the top of the distillation tower 90 at least a
fuel-grade ethanol which is transferred and stored in a suitable
holding container 100. The remaining liquid stillage is removed
from the bottom of distillation tower 90 to equipment 110
configured to precipitate and separate MMW lignins which are then
collected and stored in a suitable vessel 120 for further
processing and/or shipment. It is within the scope of the present
invention to heat the stillage and flash it with cold water to
facilitate precipitation of the MMW lignins. The de-lignified
stillage may then be controllably recycled from equipment 110 via
pipeline 130 to the mixing vessel 60 for reducing the viscosity of
fresh incoming pulp from the first module A.
[0046] Suitable enzyme preparations for addition to digestion
vessel 70 for progressively breaking down cellulosic fibers into
hemicelluloses, polysaccharides, oligosaccharides and
monosaccharides may comprise one or more of enzymes exemplified by
endo-.beta.-1,4-glucanases, cellobiohydrolases,
.beta.-glucosidases, .beta.-xylosidases, xylanases,
.alpha.-amylases, .beta.-amylases, pullulases, esterases, other
hemicellulases and cellulases and the like. Suitable microbial
inocula for fermenting pentose and/or hexose monosaccharides in
fermentation vessel 80 may comprise one or more suitable strains
selected from yeast species, fungal species and bacterial species.
Suitable yeasts are exemplified by Saccharomyces spp. and Pichia
spp. Suitable Saccharomyces spp are exemplified by S. cerevisiae
such as strains Sc Y-1528, Tembec-1 and the like. Suitable fungal
species are exemplified by Aspergillus spp. and Trichoderma spp.
Suitable bacteria are exemplified by Escherichia coli, Zymomonas
spp., Clostridium spp., and Corynebacterium spp. among others,
naturally occurring and genetically modified. It is within the
scope of the present invention to provide an inoculum comprising a
single strain, or alternatively a plurality of strains from a
single type of organism, or further alternatively, mixtures of
strains comprising strains from multiple species and microbial
types (i.e. yeasts, fungi and bacteria).
[0047] The black liquors discharged as a liquid fraction from the
digestion/extraction vessel 40 of third module A, are processed in
module C to recover at least a portion of the digestion/extraction
solvent comprising the black liquors, and to separate useful
components extracted from the lignocellulosic feedstocks as will be
described in more detail below. The black liquors are transferred
by pipeline 47 into a heating tower 140 wherein they are first
heated and then rapidly mixed (i.e., "flashed") and commingled with
a supply of cold water thereby precipitating HMW lignins from the
black liquor. The precipitated HMW lignins are separated from the
water-diluted black liquor by a suitable solids-liquids separation
equipment 150 as exemplified by filtering apparatus, hydrocyclone
separators, centrifuges and other such equipment. The separated HMW
lignins are transferred to a lignin drier 160 for controlled
removal of excess moisture, after which the dried HMW lignins are
transferred to a storage bin 170 for packaging and shipping.
[0048] The de-lignified filtrate fraction is transferred from the
separation equipment 150 to a second distillation tower 180 for
vaporizing, distilling and recovering therefrom a short-chain
alcohol exemplified by ethanol. The recovered short-chain alcohol
is transferred to a digestion/extraction solvent holding tank 250
where it may, if so desired, be commingled with a portion of
fuel-grade ethanol produced in module B and drawn from pipeline 95,
to controllably adjust the concentration and composition of the
digestion/extraction solvent prior to supplying the
digestion/extraction solvent via pipeline 41 to the
digestion/extraction vessel 40 of module A. It is within the scope
of the present invention to recover furfurals from the de-lignified
filtrate fraction concurrent with the vaporization and distillation
processes within the second distillation tower, and transfer the
recovered furfurals to a storage tank 190. An exemplary suitable
process for recovering furfurals is to acidify the heated
de-lignified filtrate thereby condensing furfurals therefrom. It is
within the scope of the present invention to supply suitable liquid
bases or acids to controllably adjust the pH of the de-lignified
filtrate fraction. Suitable liquid bases are exemplified by sodium
hydroxide. Suitable acids are exemplified by sulfuric acid.
[0049] The stillage from the second distillation tower is
transferred to the fourth module D for further processing and
separation of useful products therefrom. The hot stillage is
transferred into a cooling tower 200 configured to collect a
condensate comprising acetic acid which is then transferred to a
suitable holding vessel 210. The de-acidified stillage is then
transferred to a stillage processing vessel 220 configured for
heating the stillage followed by flashing with cold water thereby
precipitating LMW lignins which are then separated from a sugar
syrup stream, and a semi-solid/solid waste material discharged into
a waste disposal bin 226. The LMW lignins are transferred to a
suitable holding container 230 for further processing and/or
shipment. The sugar syrup stream, typically comprising at least one
of xylose, arabinose, glucose, mannose and galactose, is passed
through a decanter 240 which separates VLMW lignins from the sugar
syrup stream thereby purifying the sugar syrup stream which is
transferred to a suitable holding tank 247 prior to further
processing and/or shipping, The VLMW lignins are transferred to a
suitable holding tank 245 prior to further processing and/or
shipping.
[0050] FIG. 2 illustrates exemplary modifications that are suitable
for the modular lignocellulosic feedstock processing system of the
present invention.
[0051] One exemplary embodiment includes provision of a
pre-treatment vessel 25 for receiving therein processed
lignocellulosic feedstock from the separating device 20 for
pre-treatment prior to digestion and extraction by commingling and
saturation with a heated digestion/extraction solvent for a
suitable period of time. A suitable supply of digestion/extraction
solvent may be diverted from pipeline 41 by a valve 42 and
delivered to the pre-treatment vessel 25 by pipeline 43. Excess
digestion/extraction solvent is squeezed from the processed and
pre-treated lignocellulosic feedstock by the mechanical pressures
applied by the first auger feeder 30 during transfer of the
feedstock into the digestion/extraction vessel 40. The extracted
digestion/extraction solvent is recyclable via pipeline 32 back to
the pre-treatment vessel 25 for commingling with incoming processed
lignocellulosic feedstock and fresh incoming digestion/extraction
solvent delivered by pipeline 43. Such pre-treatment of the
processed lignocellulosic feedstock prior to its delivery to the
digestion/extraction vessel 40 will facilitate the rapid absorption
of digestion/extraction solvent during the commingling and cooking
process and expedite the digestion of the lignocellulosic feedstock
and extraction of components therefrom.
[0052] Another exemplary embodiment illustrated in FIG. 2 provides
a second diverter valve 260 interposed the sugar syrup stream
discharged from the decanter 240 in module D. In addition to
directing the sugar stream to the sugar stream holding tank 240,
the second diverter valve 260 is configured for controllably
diverting a portion of the liquid sugar stream into a pipeline 270
for delivery into the fermentation tank 80 in module B. Such
delivery of a portion of the liquid sugar stream from module D will
enhance and increase the rate of fermentation in tank 80 and
furthermore, will increase the volume of fuel-grade ethanol
produced from the lignocellulosic feedstock delivered to module
A.
[0053] Another exemplary embodiment illustrated in FIG. 2 provides
an optional fifth module E comprising an anaerobic digestion system
configured to receive semi-solid/solid wastes from the stillage
processing vessel 220 and optionally configured for receiving a
portion of the sugar syrup stream discharged from the stillage
processing vessel 220. An exemplary anaerobic digestion system
comprising module E of the present invention is illustrated in FIG.
3 and generally comprises a sludge tank 310, a vessel 320
configured for containing therein biological acidification
processes (referred to hereinafter as an acidification vessel), a
vessel 330 configured for containing therein biological
acetogenesis processes (referred to hereinafter as an acetogenesis
vessel), and a vessel 340 configured for containing therein
biological processes for conversion of acetic acid into biogas
(referred to hereinafter as a biogas vessel). The semi-solid/solid
waste materials produced in the stillage processing vessel 220 of
module C are transferred by a conveyance apparatus 225 to the
sludge tank 310 wherein anaerobic conditions and suitable
populations of facultative anaerobic microorganisms are maintained.
Enzymes produced by the facultative microorganisms hydrolyze the
complex organic molecules comprising the semi-solid/solid waste
materials into soluble monomers such as monosaccharides, amino
acids and fatty acids. It is within the scope of the present
invention to provide if so desired inocula compositions for
intermixing and commingling with the semi-solid/solid wastes in the
sludge tank 310 to expedite the hydrolysis processes occurring
therein. Suitable hydrolyzing inocula compositions are provided
with at least one Enterobacter sp. A liquid stream containing
therein the hydrolyzed soluble monomers is transferred into the
acidification vessel 320 wherein anaerobic conditions and a
population of acidogenic bacteria are maintained. The
monosaccharides, amino acids and fatty acids contained in the
liquid stream received by the acidification vessel 320 are
converted into volatile acids by the acidogenic bacteria. It is
within the scope of the present invention to provide if so desired
acidification inocula compositions configured for facilitating and
expediting the production of solubilized volatile fatty acids in
the acidification tank 320. Suitable acidification inocula
compositions are provided with at least one of Bacillus sp.,
Lactobacillus sp. and Streptococcus sp. A liquid stream containing
therein the solubilized volatile fatty acids is transferred into
the acetogenesis vessel 330 wherein anaerobic conditions and a
population of acetogenic bacteria are maintained. The volatile
fatty acids are converted by the acetogenic bacteria into acetic
acid, carbon dioxide, and hydrogen. It is within the scope of the
present invention to provide if so desired inocula compositions
configured for facilitating and expediting the production of acetic
acid from the volatile fatty acids delivered in the liquid stream
into in the acetogenesis vessel 330. Suitable acetification inocula
compositions are provided with at least one of Acetobacter sp.,
Gluconobacter sp., and Clostridium sp. The acetic acid, carbon
dioxide, and hydrogen are then transferred from the acetogenesis
vessel 330 into the biogas vessel 340 wherein the acetic acid is
converted into methane, carbon dioxide and water. The composition
of the biogas produced in the biogas vessel 330 of module E will
vary somewhat with the chemical composition of the lignocellulosic
feedstock delivered to module A, but will typically comprise
primarily methane and secondarily CO.sub.2, and trace amounts of
nitrogen gas, hydrogen, oxygen and hydrogen sulfide. It is within
the scope of the present invention to provide if so desired
methanogenic inocula compositions configured for facilitating and
expediting the conversion of acetic acid to biogas. Suitable
methanogenic inocula compositions are provided with at least one of
bacteria are from the Methanobacteria sp., Methanococci sp., and
Methanopyri sp. The biogas can be fed directly into a power
generation system as exemplified by a gas-fired combustion turbine.
Combustion of biogas converts the energy stored in the bonds of the
molecules of the methane contained in the biogas into mechanical
energy as it spins a turbine. The mechanical energy produced by
biogas combustion, for example, in an engine or micro-turbine may
spin a turbine that produces a stream of electrons or electricity.
In addition, waste heat from these engines can provide heating for
the facility's infrastructure and/or for steam and/or for hot water
for use as desired in the other modules of the present
invention.
[0054] However, a problem with anaerobic digestion of
semi-solid/solid waste materials is that the first step in the
process, i.e., the hydrolysis of complex organic molecules
comprising the semi-solid/solid waste materials into a liquid
stream containing soluble monomers such as monosaccharides, amino
acids and fatty acids, is typically lengthy and variable, while the
subsequent steps, i.e., acidification, acetification, and biogas
production proceed relatively quickly in comparison to the first
step. Consequently, such lengthy and variable hydrolysis in the
first step of anaerobic may result in insufficient amounts of
biogas production relative to the facility's requirements for power
production and/or steam and/or hot water. Accordingly, another
embodiment of the present invention, as illustrated in FIGS. 2 and
3, controllably provides a portion of the sugar syrup stream
discharged from the stillage processing vessel 220 of module D, to
the acidification tank 320 of module E to supplement the supply of
soluble monosaccharides hydrolyzed from semi-solid/solid materials
delivered to the sludge tank 310. Thus, the amount of biogas
produced by module E of the present invention can be precisely
manipulated and modulated by providing a second diverter 260
interposed the sugar syrup discharge line from stillage processing
vessel 220, to controllably divert a portion of the sugar syrup
into pipeline 275 for transfer to the acidification vessel 320.
[0055] Another exemplary embodiment of the present invention is
illustrated in FIG. 4 and provides an optional vessel 280 for
module B, wherein vessel 280 is configured for receiving the
reduced viscosity pulp from mixing vessel 60 (FIG. 2) and for
concurrent i.e., co-saccharification and co-fermentation therein of
the reduced-viscosity solids fractions. Those skilled in these arts
will understand that such co-saccharification and co-fermentation
processes are commonly referred to as "simultaneous
saccharification and fermentation" (SSF) processes, and that vessel
280 (referred to hereinafter as a SSF vessel) can replace digestion
vessel 70 and fermentation vessel 80 from FIG. 2. It is suitable to
provide a supplementary stream of sugar syrup into the SSF vessel
280 via pipeline 270 from the second diverter valve 260 (FIGS. 2
and 4) to controllably enhance and increase the rate of
fermentation in the SSF vessel 280.
[0056] Another exemplary embodiment of the present invention is
illustrated in FIG. 5 and provides an alternative first module AA,
for communication and cooperation with modules B and C, wherein the
alternative first module AA (FIG. 5) is configured for receiving,
processing and digestion/extraction of batches of a lignocellulosic
feedstock, as compared to module A which is configured for
continuous inflow, processing and digestion/extraction of a
lignocellulosic feedstock (FIG. 1). As shown in FIG. 5, one
exemplary embodiment for batch digestion/extraction of a
lignocellulosic feedstock comprises a batch digestion/extraction
vessel 400 interconnected and communicating with a
digestion/extraction solvent re-circulating tank 410 and a solvent
pump 420. A batch of lignocellulosic feedstock is loaded into a
receiving bin 430 from where it is controllably discharged into a
conveyance system provided with a screening device 440 configured
for removing pebbles, gravel, metals and other debris. The
screening device 440 may be optionally configured for sizing the
lignocellulosic feedstock into desired fractions. The processed
lignocellulosic feedstock is then conveyed with a third auger
feeder 450 into a first end of the batch digestion/extraction
vessel 400. The digestion/extraction solvent re-circulating tank
410 is configured to receive a suitable digestion/extraction
solvent from the digestion/extraction solvent holding tank 250 of
module B via pipeline 41. The digestion/extraction solvent is
pumped via solvent pump 420 into the batch digestion/extraction
vessel 400 wherein it controllably commingled, intermixed and
circulated through the batch of lignocellulosic feedstock contained
therein. The batch digestion/extraction vessel 400 is controllably
pressurized and temperature controlled to enable manipulation of
pressure and temperature so that target cooking conditions are
provided while the solvent is commingling and intermixing with the
feedstock. Exemplary cooking conditions include pressures in the
range of about 15-30 bar(g), temperatures in the range of about
120.degree.-350.degree. C., and pHs in the range of about 1.5-5.5.
During the cooking process, lignins and lignin-containing compounds
contained within the commingled and impregnated lignocellulosic
feedstock will be dissolved into the organic solvent resulting in
the cellulosic fibrous materials adhered thereto and therewith to
disassociate and to separate from each other. Those skilled in
these arts will understand that in addition to the dissolution of
lignins and lignin-containing polymers, the cooking process will
release monosaccharides, oligosaccharides and polysaccharides and
other organic compounds for example acetic acid, in solute and
particulate forms, from the lignocellulosic materials into the
organic solvents. It is suitable to discharge the
digestion/extraction solvent from the batch digestion/extraction
vessel 400 through pipeline 460 during the cooking process for
transfer via pipeline 460 back to the digestion/extraction solvent
re-circulating tank 410 for re-circulation by the solvent pump 420
back into the batch digestion/extraction vessel 400 until the
lignocellulosic feedstock is suitable digested and extracted into a
solids fraction comprising a viscous pulp material comprising
dissociated cellulosic fibers, and a liquids fraction, i.e., black
liquor, comprising solubilized lignins and lignin-containing
polymers, hemicelluloses, polysaccharides, oligosaccharides,
monosaccharides and other organic compounds in solute and
particulate forms, from the lignocellulosic materials in the spent
organic solvents. It is within the scope of the present invention
to withdraw a portion of the re-circulating digestion/extraction
solvent from the solvent re-circulating tank 410 via pipeline 465
for transfer to the heating tower 140 in module C, and to replace
the withdrawn portion of re-circulating digestion/extraction
solvent with fresh digestion/extraction solvent from the
digestion/extraction solvent holding tank 250 of module B via
pipeline 41, thereby expediting the digestion/extraction processes
within the batch digestion/extraction vessel 400. After
digestion/extraction of the lignocellulosic feedstock has been
completed, the solids fraction comprising cellulosic fibre pulp is
discharged from the batch digestion/extraction vessel 400 and
conveyed to the mixing vessel 60 in module B wherein the viscosity
of the solids fraction, i.e., pulp discharged from the first module
AA, is controllably reduced to a selected target viscosity by
commingling and intermixing with de-lignified stillage delivered
via pipeline 130 then be controllably recycled from
de-lignification equipment 110 of module B after which the
reduced-viscosity pulp is further processed by saccharification,
fermentation and refining as previously described. The black liquor
is transferred from the digestion/extraction solvent re-circulating
tank 410 via pipeline 465 to the heating tower 140 in module C for
precipitating lignin therefrom and further processing as previously
described.
[0057] A suitable exemplary modification of the batch
digestion/extraction module component of the present invention is
illustrated in FIG. 6, wherein a pre-treatment vessel 445 is
provided for receiving therein processed lignocellulosic feedstock
from the screening device 440 for pre-treatment prior to conveyance
to the batch digestion/extraction vessel 400, by commingling and
saturation with a digestion/extraction solvent for a suitable
period of time. A suitable supply of digestion/extraction solvent
may be diverted from pipeline 41 by a valve 42 (shown in FIG. 2)
and delivered to the pre-treatment vessel 445 by pipeline 43.
Excess digestion/extraction solvent is squeezed from the processed
and pre-treated lignocellulosic feedstock by the mechanical
pressures applied by the third auger feeder 450 during transfer of
the feedstock into the batch digestion/extraction vessel 400. The
extracted digestion/extraction solvent is recyclable via pipeline
455 back to the pre-treatment vessel 445 for commingling with
incoming processed lignocellulosic feedstock and fresh incoming
digestion/extraction solvent delivered by pipeline 43. Such
pre-treatment of the processed lignocellulosic feedstock prior to
its delivery to the batch digestion/extraction vessel 400 will
facilitate the rapid absorption of digestion/extraction solvent
during the commingling and cooking process and expedite the
digestion of the lignocellulosic feedstock and extraction of
components therefrom.
[0058] The systems, methods and processes for fractionating
lignocellulosic feedstocks into component parts which are then
subsequently separated are described in more detail in the
following examples with a selected hardwood and a selected softwood
species. The following examples are intended to be exemplary of the
invention and are not intended to be limiting.
EXAMPLE 1
[0059] Representative samples of whole logs of British Columbian
aspen (Populus tremuloides) (.about.125 years old) were collected.
After harvesting, logs were debarked, split, chipped, and milled to
a chip size of approximately .ltoreq.10 mm.times.10 mm.times.3 mm.
Chips were stored at room temperature (moisture content at
equilibrium was .about.10%). The aspen chips were
organosolv-pretreated in aqueous ethanol (50% w/w ethanol) with no
addition of exogenous acid or base, in a 2-L Parr.RTM. reactor
(Parr is a registered trademark of the Parr Instrument Company,
Moline, Ill., USA). Duplicate 200 g (ODW) samples of the aspen
chips, designated as ASP1, were cooked at 195.degree. C. for 60
min. The liquor:wood ratio was 5:1 weight-based. After cooking, the
reactor was cooled to room temperature. Solids and the spent liquor
were then separated by filtration. Solids were intensively washed
with a hot ethanol solution (70.degree. C.) followed by a tap water
wash step. The moisture content of the washed pulp was reduced to
about 40% with the help of a hydraulic press (alternatively a screw
press can be used). The washed pulp was homogenized and stored in a
fridge at 4.degree. C. The chemical composition (hexose, pentose,
lignin content) of washed and unwashed pulps was determined
according to a modified Klason lignin method derived from the
Technical Association of Pulp and Paper Industry (TAPPI) standard
method T222 om-88 (TAPPI methods in CD-ROM, 2004, TAPPI Press).
Liquids were analyzed for carbohydrate degradation products
(furfural, 5-hydromethylfurfural), acids, and oligo- and
monosaccharides according to standard procedures established by the
National Renewable Energy Laboratory (NREL, Golden, Colo., USA).
The resulting data were used to calculate overall lignin and
carbohydrate recoveries and process mass balance. The carbohydrate
composition and overall carbohydrate recoveries from the raw and
pretreated aspen chips are shown in Table 1. 222.2 g (oven-dried
weight, odw) of ASP1 pulp were recovered after batch organosolv
processing of 400 g of aspen wood chips (55.6% pulp yield)
containing mainly fermentable-into-ethanol carbohydrates. Pentoses
and hexoses were partially degraded resulting in 0.71 g Kg.sup.-1
of furfural and 0.06 g Kg.sup.-1 of 5-HMF, respectively. The
different classes of lignins recovered from the pulp and liquors
are shown in Table 2.
TABLE-US-00001 TABLE 1 Carbohydrate content of raw and pretreated
aspen chips (ASP1 pretreatment conditions) and overall carbohydrate
recovery Raw Pretreated Feedstock Raw Feedstock Output
Carbohydrates Recovery chips Input Pulp Liquor Total Soluble
Insoluble Total Component (%) (g) (g) (g) (g) (%) (%) (%) Arabinan
0.44 1.75 0.04 0.17 0.21 9.69 2.53 12.23 Galactan 0.43 1.71 0.16
0.26 0.42 15.16 9.07 24.23 Glucan 48.76 195.03 185.40 0.32 185.72
0.16 95.06 95.23 Xylan 16.44 65.75 17.60 8.70 26.30 13.23 26.77
40.00 Mannan 1.48 5.92 4.62 0 4.62 0 78.02 78.02 Total: 67.55
270.16 207.82 9.45 217.27
TABLE-US-00002 TABLE 2 Lignin input in raw aspen chips and lignin
fractions recovered after organosolv pretreatment (ASP1
pretreatment conditions) Raw Pretreated Pretreated Feedstock
Feedstock Feedstock Input Solids Output Liquids Output Component
(g) (odw, g) (odw, g) Raw lignin (AIL + ASL) 91.35 -- --
Self-precipitated lignin (MMW) -- -- 9.60 Precipitated lignin*
(LMW) -- -- 32.12 Very low molecular wt. lignin (VLMW) -- -- 11.72
Residual lignin (HMW) -- 11.33 -- Total: 91.35 11.33 53.44
*recovered from the liquor by precipitation with water;
AIL--acid-insoluble lignin; ASL--acid-soluble lignin
[0060] The potential of the washed pulp for production of ethanol
was evaluated in 100-mL Erlenmeyer flasks. The pH of the washed
pulp was first adjusted with a water ammonia solution to pH 5.50,
then placed into Erlenmeyer flasks and resuspended in distilled
water to a total reaction weight of 100 g (including the yeast and
enzyme weight, the final reaction volume was .about.100 mL) and a
final solids concentration of 16% (w/w). The ethanol production
process was run according to a simultaneous saccharification and
fermentation scheme (SSF) using a commercial Trichoderma reesei
fungal cellulase preparation Celluclast.RTM. 1.5 L (Celluclast is a
registered trademark of Novozymes A/S Corp., Bagsvaerd, Denmark) at
15 FPU g.sup.-1 glucan supplemented with a commercial
beta-glucosidase preparation (30 CBU g.sup.-1 glucan) and a
ethanologenic yeast, Saccharomyces cerevisiae strain Y-1528
(available from the Agricultural Research Service, United States
Department of Agriculture, Peoria, Ill., USA) at 10 g/L dry cell
wt. capable of fermenting all hexoses. The mixture was incubated at
36.degree. C., 150 rpm for 48 h. Samples were taken for ethanol
analysis by gas chromatography at 0, 24, 36, and 48 h. The ethanol
yield obtained was 39.40% theoretical ethanol yield based on
initial hexose input. The final ethanol beer concentration was
3.26% (w/w) (FIGS. 7a and 7b).
EXAMPLE 2
[0061] Duplicate 200-g samples of the wood chips prepared in
Example 1, designated as ASP2, were used for this study. The aspen
chips were organosolv-pretreated in aqueous ethanol (50% w/w
ethanol) with no addition of exogenous acid or base, in a 2-L
Parr.RTM. reactor. Duplicate 200 g (ODW) samples of aspen chips
were cooked at 195.degree. C. for 90 min. The liquor:wood ratio was
5:1 (w:w). After cooking, the reactor was cooled to room
temperature. Solids and liquids were then separated by filtration.
Solids were intensively washed with a hot ethanol solution
(70.degree. C.) followed by a tap water wash step. The moisture
content of the washed pulp was reduced to about 40% with the help
of a hydraulic press (alternatively a screw press can be used). The
washed pulp was homogenized and stored in a fridge at 4.degree. C.
The chemical composition (hexose, pentose, lignin content) of raw
chips, washed, and unwashed pulps was determined according to a
modified Klason lignin method derived from the Technical
Association of Pulp and Paper Industry (TAPPI) standard method T222
om-88 (TAPPI methods in CD-ROM, 2004, TAPPI Press). Liquids were
analyzed for carbohydrate degradation products (furfural,
5-hydromethylfurfural), acids, and oligo- and monosaccharides
according to standard procedures established by the National
Renewable Energy Laboratory (NREL, Golden, Colo., USA). The
resulting data were used to calculate overall carbohydrate and
lignin recoveries and process mass balance. The carbohydrate
composition and overall carbohydrate recoveries from the raw and
pretreated aspen chips are shown in Table 3. 230.2 g (odw) of pulp
were recovered after batch organosolv processing of 400 g of aspen
wood chips (57.6% pulp yield), and comprised mainly
fermentable-into-ethanol carbohydrates. Pentoses and hexoses were
partially degraded resulting in 0.53 g Kg.sup.-1 of furfural and
0.05 g Kg.sup.-1 of 5-HMF, respectively. The lignin content in the
raw aspen chips and overall lignin recovery after pretreatment are
shown in Table 4.
TABLE-US-00003 TABLE 3 Carbohydrate content of raw and pretreated
aspen chips (ASP2 pretreatment conditions) and overall carbohydrate
recovery Raw Pretreated Feedstock Raw Feedstock Output
Carbohydrates Recovery chips Input Pulp Liquor Total Soluble
Insoluble Total Component (%) (g) (g) (g) (g) (%) (%) (%) Arabinan
0.44 1.75 0 0.22 0.22 12.54 0.00 12.54 Galactan 0.43 1.71 0 0.21
0.21 12.25 0.00 12.25 Glucan 48.76 195.03 194.50 0.37 194.87 0.19
99.73 99.92 Xylan 16.44 65.75 14.80 6.76 21.56 10.28 22.51 32.79
Mannan 1.48 5.92 4.07 0.34 4.41 5.74 68.78 74.52 Total: 67.55
270.16 213.37 7.9 221.27
TABLE-US-00004 TABLE 4 Lignin input in raw aspen chips and lignin
fractions recovered after organosolv pretreatment (ASP2
pretreatment conditions) Raw Pretreated Pretreated Feedstock
Feedstock Feedstock Input Solids Output Liquids Output Component
(g) (odw, g) (odw, g) Raw lignin (AIL + ASL) 91.35 -- --
Self-precipitated lignin (MMW) -- -- 9.14 Precipitated lignin*
(LMW) -- -- 43.09 Very low molecular wt. lignin (VLMW) -- -- 12.60
Residual lignin (HMW) -- 7.32 -- Total: 91.35 7.32 64.83 *recovered
from the liquor by precipitation with water; AIL--acid-insoluble
lignin; ASL--acid-soluble lignin
[0062] Production of ethanol from the washed pulp was evaluated in
100-mL Erlenmeyer flasks. The experiments in Erlenmeyer flasks were
run as follows. The pH of the washed pulp was adjusted with a water
ammonia solution to pH 5.50, then placed into Erlenmeyer flasks and
resuspended in distilled water to a total reaction weight of 100 g
(including the yeast and enzyme weight, the total reaction volume
was .about.100 mL) and a final solids concentration of 16% (w/w).
The ethanol process was run according to a SSF using a commercial
Trichoderma reesei fungal cellulase preparation Celluclast.RTM. 1.5
L at 15 FPU g.sup.-1 glucan supplemented with a commercial
beta-glucosidase preparation (30 CBU g.sup.-1 glucan) and an
ethanologenic yeast, Saccharomyces cerevisiae strain Y-1528 at 10
g/L dry cell wt. capable of fermenting all hexoses. The mixture was
incubated at 36.degree. C., 150 rpm for 48 h. Samples were taken
for ethanol analysis by gas chromatography at 0, 24, 36, and 48 h.
The ethanol yield obtained was 79.30% theoretical ethanol yield
based on initial hexose input. The final ethanol beer concentration
was 6.33% (w/w) (FIGS. 7a and 7b).
EXAMPLE 3
[0063] Duplicate 200-g samples of the wood chips prepared in
Example 1, designated as ASP3, were used for this study. The aspen
chips were organosolv-pretreated in aqueous ethanol (50% w/w
ethanol) with no addition of exogenous acid or base, in a 2-L
Parr.RTM. reactor. The duplicate samples of aspen chips were cooked
in duplicate at 195.degree. C. for 120 min. The liquor:wood ratio
was 5:1 (w:w). After cooking, the reactor was cooled to room
temperature. Solids and liquids were then separated by filtration.
Solids were intensively washed with a hot ethanol solution
(70.degree. C.) followed by a tap water wash step. The moisture
content of the washed pulp was reduced to about 40% with the help
of a hydraulic press (alternatively a screw press can be used). The
washed pulp was homogenized and stored in a fridge at 4.degree. C.
The chemical composition (hexose, pentose, lignin content) of raw
chips, washed, and unwashed pulps was determined according to a
modified Klason lignin method derived from the Technical
Association of Pulp and Paper Industry (TAPPI) standard method T222
om-88. Liquids were analyzed for carbohydrate degradation products
(furfural, 5-hydromethylfurfural), acids, and oligo- and
monosaccharides according to standard procedures established by the
National Renewable Energy Laboratory. The resulting data were used
to calculate overall carbohydrate and lignin recoveries and process
mass balance. The carbohydrate composition and overall carbohydrate
recoveries from the raw and pretreated aspen chips are shown in
Table 5. 219.9 g (odw) of pulp were recovered after batch
organosolv processing of 400 g of aspen wood chips (54.98% pulp
yield) containing mainly fermentable-into-ethanol carbohydrates.
Pentoses and hexoses were partially degraded resulting in 0.92 g
Kg.sup.-1 of furfural and 0.08 g Kg.sup.-1 of 5-HMF, respectively.
The lignin contents in raw aspen chips and overall lignin recovery
after pretreatment are shown in Table 6.
[0064] Production of ethanol from the washed pulp was evaluated in
100-mL Erlenmeyer flasks. The experiments in Erlenmeyer flasks were
run as follows. The pH of the washed pulp was adjusted with a water
ammonia solution to pH 5.50, placed into Erlenmeyer flasks and
resuspended in distilled water to a total reaction weight of 100 g
(including the yeast and enzyme weight, the total reaction volume
was .about.100 mL) and a final solids concentration of 16% (w/w).
The ethanol process was run according to a SSF scheme using a
commercial Trichoderma reesei fungal cellulase preparation
Celluclast.RTM. 1.5 L at 15 FPU g.sup.-1 glucan supplemented with a
commercial beta-glucosidase preparation (30 CBU g.sup.-1 glucan)
and an ethanologenic yeast, Saccharomyces cerevisiae strain Y-1528
at 10 g/L dry cell wt. capable of fermenting all hexoses. The
mixture was incubated at 36.degree. C., 150 rpm for 48 h. Samples
were taken for ethanol analysis by gas chromatography at 0, 24, 36,
and 48 h. The ethanol yield obtained was 79.00% theoretical ethanol
yield based on initial hexose input. The final ethanol beer
concentration was 6.60% (w/w) (FIGS. 7a and 7b).
TABLE-US-00005 TABLE 5 Carbohydrate content of raw and pretreated
aspen chips (ASP3 pretreatment conditions) and overall carbohydrate
recovery Raw Pretreated Feedstock Raw Feedstock Output
Carbohydrates Recovery chips Input Pulp Liquor Total Soluble
Insoluble Total Component (%) (g) (g) (g) (g) (%) (%) (%) Arabinan
0.44 1.75 0 0.10 0.10 5.70 0 5.70 Galactan 0.43 1.71 0 0.15 0.15
8.75 0 8.75 Glucan 48.76 195.03 186.63 0.33 186.96 0.17 95.69 95.86
Xylan 16.44 65.75 12.56 4.03 16.59 6.13 19.10 25.23 Mannan 1.48
5.92 3.50 0.30 3.80 5.06 59.02 64.08 Total: 67.55 270.16 202.69
4.91 207.6
TABLE-US-00006 TABLE 6 Lignin input in raw aspen chips and lignin
fractions recovered after organosolv pretreatment (ASP3
pretreatment conditions) Raw Pretreated Pretreated Feedstock
Feedstock Feedstock Input Solids Output Liquids Output Component
(g) (odw, g) (odw, g) Raw lignin (AIL + ASL) 91.35 -- --
Self-precipitated lignin (MMW) -- -- 0.16 Precipitated lignin*
(LMW) -- -- 40.70 Very low molecular wt. lignin (VLMW) -- -- 11.46
Residual lignin (HMW) -- 6.47 -- Total: 91.35 6.47 52.32 *recovered
from the liquor by precipitation with water; AIL--acid-insoluble
lignin; ASL--acid-soluble lignin
EXAMPLE 4
[0065] Representative samples of British Columbian beetle-killed
lodgepole pine (Pinus contorta) sapwood (.about.120 years old) were
collected. After harvesting, logs were debarked, split, chipped,
and milled to a chip size of approximately .ltoreq.10 mm.times.10
mm.times.3 mm. Chips were stored at room temperature (moisture
content at equilibrium was .about.10%). Duplicate 200-g samples of
these wood chips, designated as BKLLP1, were used for this study.
The chips were organosolv-pretreated in aqueous ethanol (50% w/w
ethanol) with addition of 1.10% (w/w) sulfuric acid, in a 2-L
Parr.RTM. reactor. The chips were cooked in duplicate at
170.degree. C. for 60 min. The liquor:wood ratio was 5:1 (w:w).
After cooking, the reactor was cooled to room temperature. Solids
and liquids were then separated by filtration. Solids were
intensively washed with a hot ethanol solution (70.degree. C.)
followed by a tap water wash step. The moisture content of the
washed pulp was reduced to about 40% with the help of a hydraulic
press (alternatively a screw press can be used). The washed pulp
was homogenized and stored in a fridge at 4.degree. C. The chemical
composition (hexose, pentose, lignin content) of raw chips, washed,
and unwashed pulps was determined according to a modified Klason
lignin method derived from the Technical Association of Pulp and
Paper Industry (TAPPI) standard method T222 om-88. Liquids were
analyzed for carbohydrate degradation products (furfural,
5-hydromethylfurfural), acids, and oligo- and monosaccharides
according to standard procedures established by the National
Renewable Energy Laboratory. The obtained data were used to
calculate overall carbohydrate and lignin recoveries and process
mass balance. The carbohydrate composition and the overall
carbohydrate recoveries from the raw and pretreated beetle-killed
lodgepole pine chips are shown in Table 7. 177.2 g (odw) of pulp
were recovered after batch organosolv processing of 400 g of wood
chips (44.30% pulp yield) containing mainly
fermentable-into-ethanol carbohydrates. Pentoses and hexoses were
partially degraded resulting in 0.72 g Kg.sup.-1 of furfural and
1.78 g Kg.sup.-1 of 5-HMF, respectively. The lignin content in raw
beetle-killed lodgepole pine chips and overall lignin recovery
after pretreatment are shown in Table 8.
TABLE-US-00007 TABLE 7 Carbohydrate content of raw and pretreated
beetle-killed lodgepole pine chips (BKLLP1 pretreatment conditions)
and overall carbohydrate recovery Raw Pretreated Feedstock Raw
Feedstock Output Carbohydrates Recovery chips Input Pulp Liquor
Total Soluble Insoluble Total Component (%) (g) (g) (g) (g) (%) (%)
(%) Arabinan 1.76 7.03 0.05 0.77 0.82 10.96 0.76 11.72 Galactan
2.01 8.05 0.35 1.25 1.60 15.52 4.40 19.92 Glucan 45.55 182.22
150.44 4.37 154.81 2.40 82.56 84.96 Xylan 7.22 28.90 3.58 1.64 5.22
5.68 12.39 18.07 Mannan 11.07 44.29 6.06 0.00 6.06 0.00 13.68 13.68
Total: 67.61 270.49 160.48 8.03 168.51
TABLE-US-00008 TABLE 8 Lignin input in raw beetle-killed lodgepole
pine chips and lignin fractions recovered after organosolv
pretreatment (BKLLP1 pretreatment conditions) Raw Pretreated
Pretreated Feedstock Feedstock Feedstock Input Solids Output
Liquids Output Component (g) (odw, g) (odw, g) Raw lignin (AIL +
ASL) 106.85 -- -- Self-precipitated lignin (MMW) -- -- 0.17
Precipitated lignin* (LMW) -- -- 28.10 Very low molecular wt.
lignin (VLMW) -- -- 13.47 Residual lignin (HMW) -- 15.29 -- Total:
106.85 15.29 41.74 *recovered from the liquor by precipitation with
water; AIL--acid-insoluble lignin; ASL--acid-soluble lignin
[0066] Production of ethanol from the washed pulp was evaluated in
100-mL Erlenmeyer flasks. The experiments in Erlenmeyer flasks were
run as follows. The pH of the washed pulp was adjusted with a water
ammonia solution to pH 5.50, placed into Erlenmeyer flasks and
resuspended in distilled water to a total reaction weight of 100 g
(including the yeast and enzyme weight, the total reaction volume
was .about.100 mL) and a final solids concentration of 16% (w/w).
The ethanol process was run according to a simultaneous
saccharification and fermentation scheme (SSF) using a commercial
Trichoderma reesei fungal cellulase preparation Celluclast.RTM. 1.5
L at 15 FPU g.sup.-1 glucan supplemented with a commercial
beta-glucosidase preparation (30 CBU g.sup.-1 glucan) together with
an ethanologenic yeast, Saccharomyces cerevisiae strain Y-1528 at
10 g/L dry cell wt. capable of fermenting all hexoses. The mixture
was incubated at 36.degree. C., 150 rpm for 48 h. Samples were
taken for ethanol analysis by gas chromatography at 0, 24, 36, and
48 h. The ethanol yield obtained was 60.50% theoretical ethanol
yield based on initial hexose input. The final ethanol beer
concentration was 7.18% (w/w) (FIGS. 8a and 8b).
EXAMPLE 5
[0067] Duplicate 200-g samples British Columbian beetle-killed
lodgepole pine (Pinus contorta), designated as BKLLP2, of the chips
prepared for the study described in the Example 4, were
organosolv-pretreated in aqueous ethanol (50% w/w ethanol) with
addition of 1.10% (w/w) sulphuric acid, in a 2-L Parr.RTM. reactor.
Duplicate 200-g (ODW) samples of chips were cooked at 175.degree.
C. for 60 min. The liquor:wood ratio was 5:1 (w:w). After cooking,
the reactor was cooled to room temperature. Solids and liquids were
then separated by filtration. Solids were intensively washed with a
hot ethanol solution (70.degree. C.) followed by a tap water wash
step. The moisture content of the washed pulp was reduced to about
40% with the help of a hydraulic press (alternatively a screw press
can be used). The washed pulp was homogenized and stored in a
fridge at 4.degree. C. The chemical composition (hexose, pentose,
lignin content) of raw chips, washed, and unwashed pulps was
determined according to a modified Klason lignin method derived
from the Technical Association of Pulp and Paper Industry (TAPPI)
standard method T222 om-88. Liquids were analyzed for carbohydrate
degradation products (furfural, 5-hydromethylfurfural), acids, and
oligo- and monosaccharides according to standard procedures
established by the National Renewable Energy Laboratory. The
resulting data were used to calculate overall carbohydrate and
lignin recoveries and process mass balance. The carbohydrate
composition and the overall carbohydrate recoveries from the raw
and pretreated beetle-killed lodgepole pine chips are shown in
Table 9. 144.4 g (odw) of pulp were recovered after batch
organosolv processing of 400 g of wood chips (36.10% pulp yield)
containing mainly fermentable-into-ethanol carbohydrates. Pentoses
and hexoses were partially degraded resulting in 0.92 g Kg.sup.-1
of furfural and 1.87 g Kg.sup.-1 of 5-HMF, respectively. The lignin
content in raw beetle-killed lodgepole pine chips and overall
lignin recovery after pretreatment are shown in Table 10.
TABLE-US-00009 TABLE 9 Carbohydrate content of raw and pretreated
beetle-killed lodgepole pine chips (BKLLP2 pretreatment conditions)
and overall carbohydrate recovery Raw Pretreated Feedstock Raw
Feedstock Output Carbohydrates Recovery chips Input Pulp Liquor
Total Soluble Insoluble Total Component (%) (g) (g) (g) (g) (%) (%)
(%) Arabinan 1.76 7.03 0.04 0.39 0.43 5.55 0.62 6.17 Galactan 2.01
8.05 0.03 0.79 0.82 9.81 0.36 10.17 Glucan 45.55 182.22 134.08 5.28
139.36 2.90 73.58 76.48 Xylan 7.22 28.90 1.59 0.65 2.24 2.25 5.50
7.75 Mannan 11.07 44.29 2.30 0 2.30 0 5.18 5.18 Total: 67.61 270.49
138.04 7.11 145.15
TABLE-US-00010 TABLE 10 Lignin input in raw beetle-killed lodgepole
pine chips and lignin fractions recovered after organosolv
pretreatment (BKLLP2 pretreatment conditions) Raw Pretreated
Pretreated Feedstock Feedstock Feedstock Input Solids Output
Liquids Output Component (g) (odw, g) (odw, g) Raw lignin (AIL +
ASL) 106.85 -- -- Self-precipitated lignin (MMW) -- -- 0.13
Precipitated lignin* (LMW) -- -- 33.01 Very low molecular wt.
lignin (VLMW) -- -- 11.88 Residual lignin (HMW) -- 7.15 -- Total:
106.85 7.15 45.02 *recovered from the liquor by precipitation with
water; AIL--acid-insoluble lignin; ASL--acid-soluble lignin
[0068] Production of ethanol from the washed pulp was evaluated in
100-mL Erlenmeyer flasks. The experiments were run as follows. The
pH of the washed pulp was adjusted with a water ammonia solution to
pH 5.50, placed into Erlenmeyer flasks and resuspended in distilled
water to a total reaction weight of 100 g (including the yeast and
enzyme weight, the total reaction volume was .about.100 mL) and a
final solids concentration of 16% (w/w). The ethanol process was
run according to a simultaneous saccharification and fermentation
scheme (SSF) using a commercial Trichoderma reesei fungal cellulase
preparation Celluclast.RTM. 1.5 L at 15 FPU g.sup.-1 glucan
supplemented with a commercial beta-glucosidase preparation (30 CBU
g.sup.-1 glucan) and an ethanologenic yeast, Saccharomyces
cerevisiae strain Y-1528 at 10 g/L dry cell wt. capable of
fermenting all hexoses. The mixture was incubated at 36.degree. C.,
150 rpm for 48 h. Samples were taken for ethanol analysis by gas
chromatography at 0, 24, 36, and 48 h. The ethanol yield obtained
was 53.10% theoretical ethanol yield based on initial hexose input.
The final ethanol beer concentration was 7.74% (w/w) (FIGS. 8a and
8b).
EXAMPLE 6
[0069] Duplicate 200-g samples British Columbian beetle-killed
lodgepole pine (Pinus contorta), designated as BKLLP3, chips
prepared for the study described in the Example 4, were
organosolv-pretreated in aqueous ethanol (50% w/w ethanol) with
addition of 1.10% (w/w) sulphuric acid, in a 2-L Parr.RTM. reactor
chips were cooked in duplicate at 180.degree. C. for 60 min. The
liquor:wood ratio was 5:1 (w:w). After cooking, the reactor was
cooled to room temperature. Solids and liquids were then separated
by filtration. Solids were intensively washed with a hot ethanol
solution (70.degree. C.) followed by a tap water wash step. The
moisture content of the washed pulp was reduced to about 40% with
the help of a hydraulic press (alternatively a screw press can be
used). The washed pulp was homogenized and stored in a fridge at
4.degree. C. The chemical composition (hexose, pentose, lignin
content) of raw chips, washed, and unwashed pulps was determined
according to a modified Klason lignin method derived from the
Technical Association of Pulp and Paper Industry (TAPPI) standard
method T222 om-88. Liquids were analyzed for carbohydrate
degradation products (furfural, 5-hydromethylfurfural), acids, and
oligo- and monosaccharides according to standard procedures
established by the National Renewable Energy Laboratory. The
resulting data were used to calculate overall carbohydrate and
lignin recoveries and process mass balance. The carbohydrate
composition and the overall carbohydrate recoveries from the raw
and pretreated beetle-killed lodgepole pine chips are shown in
Table 11. 120.7 g (odw) of pulp was recovered after batch
organosolv processing of 400 g of wood chips (30.18% pulp yield)
containing mainly fermentable into ethanol carbohydrates. Pentoses
and hexoses were partially degraded resulting in 1.47 g Kg.sup.-1
of furfural and 2.17 g Kg.sup.-1 of 5-HMF, respectively. The lignin
content in raw aspen chips and overall lignin recovery after
pretreatment are shown in Table 12.
TABLE-US-00011 TABLE 11 Carbohydrate content of raw and pretreated
beetle-killed lodgepole pine chips (BKLLP3 pretreatment conditions)
and overall carbohydrate recovery Raw Pretreated Feedstock Raw
Feedstock Output Carbohydrates Recovery chips Input Pulp Liquor
Total Soluble Insoluble Total Component (%) (g) (g) (g) (g) (%) (%)
(%) Arabinan 1.76 7.03 0.04 0.22 0.26 3.13 0.52 3.65 Galactan 2.01
8.05 0.33 0.61 0.94 7.57 4.05 11.62 Glucan 45.55 182.22 102.34 6.15
108.49 3.38 56.16 59.54 Xylan 7.22 28.90 2.34 0.41 2.75 1.42 8.10
9.52 Mannan 11.07 44.29 3.86 2.07 5.93 4.67 8.72 13.39 Total: 67.61
270.49 108.91 9.46 118.37
TABLE-US-00012 TABLE 12 Lignin input in raw beetle-killed lodgepole
pine chips and lignin fractions recovered after organosolv
pretreatment (BKLLP3 pretreatment conditions) Raw Pretreated
Pretreated Feedstock Feedstock Feedstock Input Solids Output
Liquids Output Component (g) (odw, g) (odw, g) Raw lignin (AIL +
ASL) 106.85 -- -- Self-precipitated lignin (MMW) -- -- 0.26
Precipitated lignin* (LMW) -- -- 33.64 Very low molecular wt.
lignin (VLMW) -- -- 15.33 Residual lignin (HMW) -- 9.11 -- Total:
106.85 9.11 49.23 *recovered from the liquor by precipitation with
water; AIL--acid-insoluble lignin; ASL--acid-soluble lignin
[0070] Production of ethanol from the washed pulp was evaluated in
100-mL Erlenmeyer flasks. The experiments in Erlenmeyer flasks were
run as follows. The pH of the washed pulp was adjusted with a water
ammonia solution to pH 5.50, placed into Erlenmeyer flasks and
resuspended in distilled water to a total reaction weight of 100 g
(including the yeast and enzyme weight, the total reaction volume
was .about.100 mL) and a final solids concentration of 16% (w/w).
The ethanol process was run according to a SSF scheme using a
commercial Trichoderma reesei fungal cellulase preparation
Celluclast.RTM. 1.5 L at 15 FPU g.sup.-1 glucan supplemented with a
commercial beta-glucosidase preparation (30 CBU g.sup.-1 glucan)
and an ethanologenic yeast, Saccharomyces cerevisiae strain Y-1528
at 10 g/L dry cell wt. capable of fermenting all hexoses. The
mixture was incubated at 36.degree. C., 150 rpm for 48 h. Samples
were taken for ethanol analysis by gas chromatography at 0, 24, 36,
and 48 h. The ethanol yield obtained was 44.60% theoretical ethanol
yield based on initial hexose input. The final ethanol beer
concentration was 7.79% (w/w) (FIGS. 8a and 8b).
EXAMPLE 7
[0071] Representative samples of wheat straw (Triticum sp.) from
Eastern Washington, USA were collected. Wheat straw was cut into
.about.5-cm chips and stored at room temperature (moisture content
at equilibrium was .about.10%). The straw was organosolv-pretreated
in aqueous ethanol (50% w/w ethanol) with no addition of exogenous
acid or base, in a 2-L Parr.RTM. reactor. Duplicate 100-g (ODW)
samples of wheat straw, designated as WS-1, were cooked in
duplicate at 195.degree. C. for 90 min. The liquor:raw material
ratio was 10:1 (w/w). After cooking, the reactor was cooled to room
temperature. Solids and the spent liquor were then separated by
filtration. Solids were intensively washed with a hot ethanol
solution (70.degree. C.) followed by a tap water wash step. The
moisture content of the washed pulp was reduced to about 50% with
the help of a hydraulic press (alternatively a screw press can be
used). The washed pulp was homogenized and stored in a fridge at
4.degree. C. The chemical compositions (hexose, pentose, lignin
content) of washed and unwashed pulps were determined according to
a modified Klason lignin method derived from the Technical
Association of Pulp and Paper Industry (TAPPI) standard method T222
om-88. Liquids were analyzed for carbohydrate degradation products
(furfural, 5-hydromethylfurfural), acids, and oligo- and
monosaccharides according to standard procedures established by the
National Renewable Energy Laboratory. The resulting data were used
to calculate overall carbohydrate and lignin recoveries and process
mass balance. The carbohydrate composition and the overall
carbohydrate recoveries from the raw and pretreated wheat straw are
shown in Table 13. 46.8 g (oven-dried weight, odw) of WS-1 pulp was
recovered after batch organosolv processing of 100 g of wheat straw
(46.8% pulp yield) containing mainly fermentable-into-ethanol
carbohydrates. Pentoses and hexoses were partially degraded
resulting in 0.39 g Kg.sup.-1 of furfural and 0.03 g Kg.sup.-1 of
5-HMF, respectively. The lignin content in raw wheat straw and
overall lignin recovery after pretreatment are shown in Table
14.
TABLE-US-00013 TABLE 13 Carbohydrate content of raw and pretreated
wheat straw chips (WS-1 pretreatment conditions) and overall
carbohydrate recovery Raw Pretreated Feedstock Raw Feedstock Output
Carbohydrates Recovery chips Input Pulp Liquor Total Soluble
Insoluble Total Component (%) (g) (g) (g) (g) (%) (%) (%) Arabinan
3.85 3.85 0.00 0.17 0.17 4.39 0.00 4.39 Galactan 1.16 1.16 0.00
0.19 0.19 16.72 0.00 16.72 Glucan 54.92 54.92 35.47 0.00 35.47 0.00
64.58 64.58 Xylan 27.83 27.83 3.36 2.68 6.03 9.62 12.06 21.67
Mannan 0.53 0.53 0.00 0.08 0.08 15.78 0.00 15.78 Total: 88.30 88.30
38.83 3.12 41.94
TABLE-US-00014 TABLE 14 Lignin input in raw wheat straw chips and
lignin fractions recovered after organosolv pretreatment (WS-1
pretreatment conditions) Raw Pretreated Pretreated Feedstock
Feedstock Feedstock Input Solids Output Liquids Output Component
(g) (odw, g) (odw, g) Raw lignin (AIL + ASL) 17.44 -- --
Self-precipitated lignin (MMW) -- -- 1.7 Precipitated lignin* (LMW)
-- -- 8.4 Very low molecular wt. Lignin (VLMW) -- -- -- Residual
lignin (HMW) -- 4.31 -- Total: 17.44 4.31 10.1 *recovered from the
liquor by precipitation with water; AIL--acid-insoluble lignin;
ASL--acid-soluble lignin
[0072] The potential of the produced washed wheat straw pulp for
production of ethanol was evaluated in 100-mL Erlenmeyer flasks.
The experiments in Erlenmeyer flasks were run as follows. The pH of
the washed pulp was adjusted with a water ammonia solution to pH
5.50, placed into Erlenmeyer flasks and resuspended in distilled
water to a total reaction weight of 100 g (including the yeast and
enzyme weight, the final reaction volume was .about.100 mL) and a
final solids concentration of 16% (w/w). The ethanol process was
run according to a SSF scheme using a commercial Trichoderma reesei
fungal cellulase preparation Celluclast.RTM. 1.5 L at 15 FPU
g.sup.-1 glucan supplemented with a commercial beta-glucosidase
preparation (30 CBU g.sup.-1 glucan) and an ethanologenic yeast,
Saccharomyces cerevisiae strain Y-1528 at 10 g/L dry cell wt.
capable of fermenting all hexoses. The mixture was incubated at
36.degree. C., 150 rpm for 48 h. Samples were taken for ethanol
analysis by gas chromatography at 0, 24, 36, and 48 h. The ethanol
yield obtained was 88.86% theoretical ethanol yield based on
initial hexose input. The final ethanol beer concentration was
6.14% (w/w) (FIGS. 9a and 9b).
EXAMPLE 8
[0073] Representative samples of switchgrass (Panicum virgatum)
from Tennessee, USA were collected. The switchgrass samples were
cut to a particle size of approximately 5 cm and stored at room
temperature (moisture content at equilibrium was .about.10%). The
switchgrass chips were organosolv-pretreated in aqueous ethanol
(50% w/w ethanol) with no addition of exogenous acid or base, in a
2-L Parr.RTM. reactor. Dubplicate 100-g (odw) switchgrass samples
designated as SWG-1, were cooked at 195.degree. C. for 90 min. The
liquor:raw material ratio was 10:1 (w/w). After cooking, the
reactor was cooled to room temperature. Solids and the spent liquor
were then separated by filtration. Solids were intensively washed
with a hot ethanol solution (70.degree. C.) followed by a tap water
wash step. The moisture content of the washed pulp was reduced to
about 50% with the help of a hydraulic press (alternatively a screw
press can be used). The washed pulp was homogenized and stored in a
fridge at 4.degree. C. The chemical composition (hexose, pentose,
lignin content) of washed and unwashed pulps was determined
according to a modified Klason lignin method derived from the
Technical Association of Pulp and Paper Industry (TAPPI) standard
method T222 om-88. Liquids were analyzed for carbohydrate
degradation products (furfural, 5-hydromethylfurfural), acids, and
oligo- and monosaccharides according to standard procedures
established by the National Renewable Energy Laboratory. The
resulting data were used to calculate overall carbohydrate and
lignin recoveries and process mass balance. The carbohydrate
composition and the overall carbohydrate recoveries from the raw
and pretreated switchgrass are illustrated in Table 15. 45.2 g
(oven-dried weight, odw) of SWG-1 pulp was recovered after batch
organosolv processing of 100 g of switchgrass (45.2% pulp yield)
containing mainly fermentable-into-ethanol carbohydrates. Pentoses
and hexoses were partially degraded resulting in 0.917 g Kg.sup.-1
of furfural and 0.21 g Kg.sup.-1 of 5-HMF, respectively. The lignin
content in raw switchgrass and overall lignin recovery after
pretreatment are shown in Table 16.
TABLE-US-00015 TABLE 15 Carbohydrate content of raw and pretreated
switchgrass particles (SWG-1 pretreatment conditions) and overall
carbohydrate recovery Raw Pretreated Feedstock Raw Feedstock Output
Carbohydrates Recovery chips Input Pulp Liquor Total Soluble
Insoluble Total Component (%) (g) (g) (g) (g) (%) (%) (%) Arabinan
3.44 3.44 0.00 0.23 0.23 6.79 0.00 6.79 Galactan 0.93 0.93 0.00
0.18 0.18 19.48 0.00 19.48 Glucan 51.04 51.04 35.88 1.37 37.25 2.68
70.31 72.99 Xylan 26.69 26.69 5.37 3.01 8.39 11.29 20.14 31.43
Mannan 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Total: 82.10 82.10
41.26 4.80 46.05
TABLE-US-00016 TABLE 16 Lignin input in raw switchgrass particles
and lignin fractions recovered after organosolv pretreatment (SWG-1
pretreatment conditions) Raw Pretreated Pretreated Feedstock
Feedstock Feedstock Input Solids Output Liquids Output Component
(g) (odw, g) (odw, g) Raw lignin (AIL + ASL) 18.17 -- --
Self-precipitated lignin (MMW) -- -- 3.00 Precipitated lignin*
(LMW) -- -- 10.6 Very low molecular wt. lignin (VLMW) -- -- --
Residual lignin (HMW) -- 2.67 -- Total: 18.17 2.67 13.60 *recovered
from the liquor by precipitation with water; AIL--acid-insoluble
lignin; ASL--acid-soluble lignin
[0074] The potential of the produced washed switchgrass pulp for
production of ethanol was evaluated in 100-mL Erlenmeyer flasks.
The experiments in Erlenmeyer flasks were run as follows. The pH of
the washed pulp was adjusted with a water ammonia solution to pH
5.50, placed into Erlenmeyer flasks and resuspended in distilled
water to a total reaction weight of 100 g (including the yeast and
enzyme weight, the final reaction volume was .about.100 mL) and a
final solids concentration of 16% (w/w). The ethanol process was
run according to a SSF scheme using a commercial Trichoderma reesei
fungal cellulase preparation Celluclast.RTM. 1.5 L at 15 FPU
g.sup.-1 glucan supplemented with a commercial beta-glucosidase
preparation (30 CBU g.sup.-1 glucan) and an ethanologenic yeast,
Saccharomyces cerevisiae strain Y-1528 at 10 g/L dry cell wt.
capable of fermenting all hexoses. The mixture was incubated at
36.degree. C., 150 rpm for 48 h. Samples were taken for ethanol
analysis by gas chromatography at 0, 24, 36, and 48 h. The ethanol
yield obtained was 82.51% theoretical ethanol yield based on
initial hexose input. The final ethanol beer concentration was
5.97% (w/w) (FIGS. 9a and 9b).
[0075] While this invention has been described with respect to the
exemplary embodiments, those skilled in these arts will understand
how to modify and adapt the systems, processes and equipment
configurations disclosed herein for continuously receiving and
controllably commingling lignocellulosic feedstocks with
counter-flowing organic solvents. Certain novel elements disclosed
herein for processing a continuous incoming stream of
lignocellulosic feedstocks with countercurrent flowing or
alternatively, concurrent flowing organic solvents for separating
the lignocellulosic materials into component parts and further
processing thereof, can be modified for integration into batch
systems configured for processing lignocellulosic materials. For
example, the black liquors produced in batch systems may be
de-lignified and then a portion of the de-lignified black liquor
used to pretreat a new, fresh batch of lignocellulosic materials
prior to batch organosolv cooking, while the remainder of the
de-lignified black liquor is further processed into component parts
as disclosed herein. Specifically, the fresh batch of
lignocellulosic materials maybe controllably commingled with
portions of the de-lignified black liquor for selected periods of
time prior to contacting, commingling and impregnating the batch of
lignocellulosic materials with suitable organic solvents. Also, it
is within the scope of the present invention, to provide turbulence
within a batch digestion system wherein a batch of lignocellulosic
materials is cooked with organic solvents by providing pressurized
flows of the organic solvents within and about the digestion
vessel. It is optional to controllably remove portions of the
organic solvent/black liquors from the digestion vessel during the
cooking period and concurrently introduced fresh organic solvent
and/or de-lignified black liquors thereby facilitating and
expediting delignification of the lignocellulosic materials. It is
also within the scope of the present invention to further process
the de-lignified black liquors from the batch lignocellulosic
digestion systems to separate and further process components parts
exemplified by lignins, furfural, acetic acid, monosaccharides,
oligosaccharides, and ethanol among others.
* * * * *