Note: Descriptions are shown in the official language in which they were submitted.
CA 02804661 2013-01-31
ENZYMATIC TREATMENT OF WOOD CHIPS
Field of the Invention
The invention relates to enzymatic pretreatment of wood chips to improve the
chips for downstream processing, such as lowered energy consumption during
refining
of the chips.
Background
Wood pulps are generally produced through multistep processes. Initially, logs
can be subjected to grinding in which the logs are forced against a rotating
abrasive
stone which separates the fibers from the log and also the wood cell matrix.
In a refining
process, wood chips are fed between two metal discs, with at least one disc
rotating. In
both cases, essentially all of the constituents of wood are retained in the
pulp that is
eventually produced. Such pulp contains fiber bundles, fiber fragments and
whole
fibers. A lack of uniformity of pulp and constituents and the presence of
lignin in the pulp
give it certain desirable qualities, such as yield, paper bulk and opacity as
well as good
printability. The pulp also has less desirable properties for some paper
types, such as
low strength, relatively coarse surface and a lack of durability.
Chips to be refined can be destructured and impregnated with chemicals or
enzymes prior to further mechanical treatment. This can help increase pulp
quality or
reduce energy consumption. These methods create slightly different pulps and
also vary
with the species of wood species, quality of the wood, processing conditions
and the
amount of energy applied. Various forms exist: thermomechanical pulping (TMP),
refiner pulping, stone groundwood pulping, etc.
Chip "destructuring" is usually carried out in the first stage refiner where
it occurs
in combination with some fiber fibrillation. The difficulty of clearly
separating these two
steps can lead to an unnecessary increase in energy while no significant gain
in pulp
properties is obtained. Several pieces of equipment have been developed to
overcome
these drawbacks. US Patent No. 5,813,617 of Toma, for example, describes one
such
device. Other devices incorporate compressive forces along with the
destructuring
shear forces. These compressive forces along with the accompanied
decompression
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can be used to enhance the penetration of chemicals or enzymes for
impregnation prior
to refining.
In TMP, steam is added to the chips being refined to facilitate pulping and
lower
electricity consumption. Steam is also produced during refining and heat
recovery
systems can help recoup some of the energy cost of the process. The electric
motors
used to operate these refiners require very large amounts of power. The TMP
process
generally involves several refining stages to produce a desirable pulp.
However, only a
small portion of the energy used in each refining stage is actually used to
separate and
develop the fibers. Screening is used after or between refining stages to
separate
adequately refined fibers from longer, coarser fibers. These tougher fibers
are sent to
"rejects" refiners for further development. Depending on the quality of
refining, the
amount of rejects needing additional refining can and usually is significant.
Woody biomass used in these mechanical pulping processes contains cellulose,
hemicelluloses, lignin and extractives in varying amounts throughout the
ultrastructure
of its fibers. These various components act in conjunction to give these
substrates
mechanical strength and resistance to degradation. By selectively removing or
altering
certain components, it is possible to reduce the amount of energy required to
separate
and refine these fibers. The patent literature describes various approaches
using
different enzyme mixtures. For example US Patent Publication No. 2005/0000666,
of
Taylor et al., describes the use of mannanase and xylanase. Certain treatments
have
been found to significantly impact paper strength properties which have
limited their
applications. United States Patent No. 5,865,949, of Pere et al., describes a
process
using an enzyme mixture containing endoI3-glucanase (EG), a limited mannanase
and
cellobiohydrolase (CBH) activity which reduces the negative effects on paper
strength.
United States Patent No. 6,099,688, of Pere et al., describes the use of
isolated
cellobiohydrolase to increase the amount of relative amorphousness of the
cellulose
within the fibers. This process is said to cause even less damage to paper
properties.
International patent publication No. WO 97/40194, of Eachus et al., 'suggests
changing the structure or the composition of the wood by adding to compressed
chips
fungal or bacterial cultures or products, such as enzymes obtained from them,
by
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means of pressure. The purpose of the compression is to make cracks and
fractures in
the wood. When the chips are released from the compression, microbes of their
products, while the chips expand, are absorbed by the structures of the wood
partially
by the virtue of negative pressure, partially by the capillary action. The use
of lipolytic,
proteolytic, linginolytic, cellulolytic and hemicellulolytic enzymes is
mentioned. The
patent specification describes the absorption of the enzyme preparation
Clariant
Cartazyme HS Tm into the compressed chips after releasing the pressure. Liquid
was
removed after the treatment, and mechanical pulp was prepared from the chips.
In that
case, the amount of energy consumed was 7.5% less than in the case of chips
that
were treated with a buffer only. In another test, the enzyme preparations
Clariant
Cartazyme NS Tm and Sigma porcine pancreas Lipase L-3126 were used. In that
case,
the amount of energy consumed was 12.5% less than when treated with a buffer
only.
A more recent pre-treatment of chips using an enzyme preparation containing
cellobiohydrolase and endoglucanase was suggested by Pere in United States
Patent
Publication No. 2007/0151683. Here again, it was said to be preferable to
carry out the
enzymatic treatment by compressing the chips and by bringing the compressed
chips in
a liquid phase into contact with the enzyme composition to absorb the enzyme
composition into the chips. The process is said to be useful for reducing the
specific
energy consumption (SEC) of mechanical pulp and to improve the technical
properties
of the fibers.
Summary
The invention provides a method for preparing mechanical pulp. The method
includes: (i) exposing compressed wood chips to an enzymatic solution
comprising an
endoglucanase (EG) and a cellobiohydrolase (CBH), wherein the ratio of
enzymatic
activity of EG:CBH is at least 3, and permitting the wood chips to decompress.
The
product of step (I) can be refined for further processing in the production
e.g. of pulp for
the manufacture of paper products.
The enzymatic activity of the CBH in the enzymatic solution is typically at
least
0.5 FPU per gm of wood chips. The dry weight of the wood substrate can be
measured
according to standard T 258 om-06. It is possible use CBH in an amount that
provides
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greater activity e.g., in a range from 0.5 to 200 FPU, or 1 to 150 FPU, or 5
to 150, or 10
to 150, or 20 to 150, or 30 to 150, or 40 to 150, or 50 to 150, or 70 to 150,
or 100 to 150
FPU, or 50 to 130 FPU, or 50 to 110 FPU per gram of wood chips etc., or the
activity
can be about any of the foregoing values. A preferred range is between 0.1 and
5 FPU
6 per gm of wood chips.
In embodiments, the enzymatic solution also contains a hemicellulase,
typically
the enzymatic activity of the hemicellulase being at least 1.5 times the
activity of the
CBH. A preferred hemicellulase is a mannanase (MAN).
As described in the examples, wood chips can be exposed to the enzymatic
solution for sufficient time to reduce energy consumption during subsequent
refining of
the wood chips to pulp in which the freeness of the pulp (CSF) obtained is
reduced by at
least 5% in comparison to the freeness of pulp obtained by refining chips
which have
not been exposed to the enzymatic solution. The energy reduction can be at
least 5%,
but can be greater e.g., at least 6%, at least 7%, at least 8%, at least 9%,
at least 10%,
at least 11 /0 or at least 12%, or can be about any of these amounts.
Suitable enzymatic activity is provided by EG, CBI-1, and MAN classified as EC
3.2.1.6, EC 3.2.1.91, and EC 3.2.1.78, respectively.
Enzymatic activity of the EG can be at least 1850 CMCU per gm of wood chips
and/or MAN is at least 250 1U per gm of wood chips.
The enzymatic solution can contain enzymatic protein having of between
0.02mg/g to 20mg/g of the wood chips.
Wood chips can be softwood, for example, Black Spruce, Picea mariana, used in
the examples described below. The chips can be made up of from 38 to 52% by
weight
cellulose, from 20 to 30% by weight lignin, from 20 to 30% by weight
hemicellulose. The
hemicellulose component can be from 15 to 20% mannans by total weight of the
wood
chips and from 15 to 20% xylans by total weight of the wood chips.
In preferred embodiments, the wood chips are destructured wood chips having
an average weight per chip in the range of from 0.8 to 2g.
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The method can include the step of compressing wood chips to form the
compressed wood chips that are to be permitted to be decompressed while
exposed to
the enzymatic solution.
The wood chips can be subjected to steaming prior to being compressed.
Wood chips having an average size of, prior to compression, between 15 to
35mm long by 15 to 35 mm wide and between 2 to 8 mm thick are suitabte.
Compressing the wood chips can include subjecting the chips to a pressure in
the range of from 50 to 600 atm. A preferred minimum pressure is 100atm.
In an embodiment, wood chips are compressed by at least 10% of their
uncompressed volume.
Compression of the wood chips can be accomplished through the use of e.g.,
screw clamp, or press or, a hydraulic press. Compression can include the chips
to
pressure for a period of between 10 minutes and 5 hours. In many cases, 10 to
30
minutes is acceptable.
Compression of the wood chips can be conducted prior to exposing of the
compressed wood chips to the enzymatic solution or in the presence of the
enzymatic
solution.
Decompression can take place at atmospheric pressure in an aqueous solution
for a period of time in which a final consistency in the range of from 0.3 to
30% is
reached, preferably a range of from 5 to 15%.
Refining the wood chips that have been enzymatically treated can be conducted
to obtain a mechanical wood pulp having a drainability of at least 100 ml CSF.
The method can also include chipping raw wood material to form wood chips
which can then be compressed and destructured for enzymatic treatment.
An embodiment of the invention is also a method for treating wood chips for
eventual use in preparing mechanical pulp e.g., refining. In this sense, the
embodiment
can be regarded as a method for preparing feedstock for a mechanical pulping
process.
The method includes exposing compressed wood chips to an enzymatic solution
comprising an endoglucanase (EG) and a cellobiohydrolase (CBH), wherein the
ratio of
enzymatic activity of EG:CBH is at least 3. Other features associated with the
enzymatic
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treatment, described above, and below in connection with the examples, can of
course
be included in this treatment.
Downstream processing can include subjecting treated wood chips to mechanical
pulping, which can be a thermomechanical refining process or a
chemithermomechanical refining process. A paper product can be manufactured
downstream, be it in a separate mill or as part of an in-line process.
So, an aspect of the present invention is a method for reducing the amount of
energy required to refine destructured chips by treating said chips with an
enzymatic
solution containing a plurality of enzymes and optionally stabilizer
compound(s) during
decompression. This solution can be a combination of CBH, EG, mannanase and
stabilizer agents and surfactants containing mainly propylene glycol,
glycerol, sorbitol
and to a lesser degree proxel, potassium sorbate and ethoxylated fatty
alcohols. The
enzymatic treatment can be carried out at process temperatures of from 20 C.
to 80 C.,
for example between 40 C. and 60 C. The enzymatic treatment can be carried out
at a
pH of from about 2 to about 10. The treatment time can be from 30 minutes to
10 hours.
Other temperatures, pHs and or times can be used.
The reduction in energy can be manifest as reduced energy consumption during
primary, secondary, tertiary, reject, post-refining or other mechanical
treatment used to
obtain a desired final pulp from a destructured wood chip that has been
treated with the
enzyme solution prior to refining.
The enzyme solution used herein preferably possesses the following relative
activities: the EG should have a 10 fold greater activity than the CBH and the
mannanase should have a 2 fold greater activity than the CBH. This enzyme
solution is
available commercially from Novozymes under the name Celluclast 1.51.Tm.
Methods of refining chips with lower energy requirements to obtain a desirable
degree of refining are set forth herein. Methods for refining the chips
wherein the
refining process includes mechanical destructuring including compression and
decompression, of wood chips followed by treatment of the obtained
destructured chips
with a complex enzyme mixture are presented, wherein the resultant pulp and/or
paper
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products have maintained tensile strength, improved optical properties and
slightly
reduced tear index as compared to untreated pulps or products therewith.
Pulp and paper products made therefrom having maintained tensile strength,
improved optical properties and slightly reduced tear strength are provided.
Pulp and
papers made therefrom which require less energy to produce are provided.
it is to be understood that both the foregoing general description and the
following detailed description are exemplary and explanatory only and are only
intended
to provide a further explanation of the present invention as claimed
Brief Description of the Drawings
Embodiments illustrating the invention and establishing feasibility of various
aspects thereof are described below with reference to the accompanying
drawings, in
which:
Figure 1 is a bar graph showing the amount of sugars released per gram of oven
dried chips (OD) into the liquor after a 1 hour enzyme hydrolysis (5FPU/g OD
Celluclast
1.5LTm) at different compression conditions;
Figure 2 is a bar graph showing freeness (CSF) after a 1 hour enzyme
hydrolysis
(5FPU/g OD Celluclast 1.5LTm) at different compression conditions; and
Figure 3 is a bar graph showing specific energy consumption (SEC) during
laboratory scale refining of wood chips that had been compressed at different
conditions
and subjected to enzyme hydrolysis (10FPU/g OD Celluclast 1.5L'Im) for one
hour
during decompression i.e., at atmospheric pressure.
Detailed Description
The present invention relates to a method of refining chips into pulps,
wherein
the method includes the use of an enzyme mixture containing celluloses and
hemicellulase. Treatment with this solution following chip destructuring,
compression
and decompression prior to the entire refining process from primary,
secondary, reject
to post refining can reduce the energy required to reach a given degree of
refining. This
enzyme mixture is to contain a significant EG activity, a marked mannanase
activity and
a CB H activity that is lower than the first two but not negligible.
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As used herein, an endo-13-glucanase is preferably a cellulase classified as
EC
3.2.1.6 ¨ endo-1,3(4)- j3 -glucanase. This enzyme is preferably capable of
endohydrolysis of 1,3- or 1,4-linkages in f3 -D-glucans when the glucose
residue whose
reducing group is involved in the linkage to be hydrolysed is itself
substituted at C-3.
This hydrolysis cleaves the O-glycosyl bond of the cellulose backbone.
As used herein, a "mannanase" is preferably a hemicellulase classified as EC
3.2.1.78, and called endo-1,4-13 -mannosidase. Mannanase includes 13 -
mannanase,
endo-1,4-mannanase, and galactomannanase. Mannanase is preferably capable of
catalyzing the hydrolysis of 1,4- (3 -D-mannosidic linkages in mannans,
including
glucomannans, galactomannans and galactoglucomannans. Mannans are
polysaccharides primarily or entirely composed of D-mannose units.
As used herein, a cellobiohydrolase is preferably a cellulase classified as EC
3.2.1.91 and called cellulose 1,4-13 -cellobiosidase (non-reducing end). This
enzyme
produces the hydrolysis of (1-04)-f3-D-glucosidic linkages in cellulose and
cellotetraose,
releasing cellobiose from the non-reducing ends of the chains
EG activity can be determined following the carboxymethyl cellulose (CMC)
method described in Measurement of Cellulose Activities by T.K Ghose (Pure &
Appl.
Chem. Vol 69, No. 2, pp. 257-268, 1987). The amount of reducing sugars
released from
enzymatic hydrolysis of a 2% solution of a well characterized CMC is used to
determine
the enzymes EG activity. Sugar concentration is determined by the well known
DNS
method described by G.L. Miller (Analytical Chem., No. 31, p.426, 1959).
CBH activity can be determined following the filter paper assay method
described
in Measurement of Cellulase Activities by T.K. Ghose (Pure & Appl. Chem. Vol
69, No.
2, pp. 257-268, 1987). The amount of reducing sugars released from enzymatic
hydrolysis of Whatman No. 1 filter paper strip of known size is used to
determine the
enzymes CBH activity. Sugar concentration is determined by the well known DNS
method described by G.L. Miller (Analytical Chem., No. 31, p.426, 1959).
Mannanase activity can be determined following the method describer by M.
Ratto and K. Poutanen (Biotechnology Letters, No 9, pp-661-664, 1988). The
amount of
reducing sugars released from enzymatic hydrolysis of a 0.5% solution of
locust bean
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gum is used to determine the enzymes mannanase activity. Sugar concentration
is
determined by the well known DNS method described by G.L. Miller (Analytical
Chem.,
No. 31, p.428, 1959).
An enzyme solution containing EG, C81-Iand mannanase activities in the correct
6 ratios is commercially available from Novozymese under the name
Celluclast 1.5LTM.
This solution contains between 40mg and 50mg of total protein per millilitre
of solution.
When kept at between 0 C and 25 C, the solution is stable and its activity is
maintained
for about 18 months. Storage at higher temperatures will reduce this effective
storage
time.
The enzyme solution can vary slightly in ratio of activities which still give
the
desired energy reductions and paper qualities. The amount of total protein in
the correct
ratio should be between 0.02kg and 5kg per metric ton of oven dried wood. This
amount
of total protein can vary depending on the type of woody substrate being used,
for
example virgin hardwood kraft, virgin softwood kraft, recycled pulp,
groundwood, refiner
groundwood, pressurized refiner groundwood, thermomechanical,
chemithermomechanical or a mixture thereof; or the species of wood which makes
up
this substrate, for example Populus sp., Acer sp., Picea sp., Abies sp., Pinus
sp.,
Conium sp., etc.
The destructured chips of the present invention can be treated with one or
more
other components, including polymers such as anionic and non-ionic polymers,
clays,
other fillers, dyes, pigments, defoamers, microbiocides, pH adjusting agents
such as
alum or hydrochloric acid, other enzymes, and other conventional papermaking
or
processing additives. These additives can be added before, during or after
introduction
of the enzyme solution. The enzyme solution can be added, and is preferably
added to
the papermaking pulp before the addition of coagulants, fiocculants, fillers
and other
conventional and non-conventional papermaking additives, including additional
enzymes.
The destructured chips can be any conventional softwood or hardwood species
used in mechanical pulp production, such as spruce, fir, hemlock, aspen,
acacia, birch,
beech, eucalyptus, oak and other softwood and hardwood species. The
destructured
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chips can contain cellulose fibers at a concentration of at 35% by weight
based on the
oven dried solids content of the wood. The final pulp can be, for example,
virgin pulp
(e.g. spruce, fir, pine, eucalyptus, and include virgin hardwood or virgin
softwood),
hardwood kraft, softwood kraft, recycled pulp, groundwood, refiner groundwood,
pressurized refiner groundwood, thermomechanical, chemithermomechanical or
mixtures thereof.
According to various embodiments, the papermaking system can include chip
handling equipment with a chip destructuring device which is capable of
destructuring
and compressing wood chips, a primary refiner, a secondary refiner, a screen,
a mixer,
a latency and/or blend chest, and papermaking equipment, for example, screens.
The
papermaking system can also include metering devices for providing a suitable
concentration of the enzyme composition or other additives to the flow of
pulp. Valving,
pumps, and metering equipment as known to those skilled in the art can also be
used
for introducing various additives described herein to the pulp.
According to one embodiment, the enzyme solution can be added to the chips
before or during destructuring, compression or preferably immediately after
compression ends and decompression begins, added to pulp after the pulp leaves
the
first refiner (also known as the primary refiner) during the refining process.
For example,
the enzyme solution can be added before the second refiner (also known as the
secondary refiner), after the second refiner, before the screen, after the
screen, before
the mixer, after the mixer, before the latency and/or blend chest, to the
latency and/or
blend chest. For example, the enzyme solution can be added after the second
refiner,
between the screen and the mixer, or after the mixer. Other additives as
described can
be added to the papermaking system as known to those skilled in the art.
The destructured chips can be treated with the enzyme solution when the chips
are at a temperature of from 10*C. to about 75 C., from about 30 C. to about
70 C., or
from about 40 C. to about 65 C. The chips can be at a pH of from 2 to 10, from
about 4
to 7, or from 4.5 to 5.5. A treatment time can be from 10 minutes to about 10
hours,
from about 30 minutes to about 5 hours or from 1 hours to 2 hours.
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The enzyme treatment is carried out before, during or immediately after the
destructuring process, but before completion of the refining process. The
enzyme
treatment is carried out on "destructured wood chips". "Destructured wood
chips"' refers
to a woody material used as the raw material of the mechanical pulp, which has
been
subjected to at least one mechanical destructuring process step. The term
destructured
wood chips therefore encompasses, e.g. chips of various sizes, compressed and
uncompressed destructured wood chips, matchsticks and fiber bundles.
Preferably, the
enzyme treatment is carried out on destructured wood chips. More preferably
the
enzyme solution is carried out on destructured wood chips during decompression
of the
chips.
In another embodiment, the enzyme solution can be added during the chip
handling prior to destructuring. As an example, the enzyme solution can be
added after
chip washing at the chip bin. In this embodiment, the chips are treated and
directed to a
destructuring device before compression-decompression prior to a primary
refiner. The
pulp is then refined to desired specifications before being returned to the
papermaking
system stream.
The introduction of the enzyme solution can be made at one or more points and
the introduction can be continuous, semi-continuous, batch, or combinations
thereof.
According to various embodiments, the chip to liquor ratio can be about 1 to
20, 1
to 10, or 1 to 5.
Various ranges of components such as enzymatic activities, times, pressures,
and values of such are described herein. It is to be understood that
additional
combinations of such ranges and values are also disclosed by such
descriptions. As a
general example, a range of from 2 to 5 describes values of about 2 and about
5; values
of about 2, 3, 4 and 5 describes ranges of 2 to 5, 3 to 4, 2 to 4, etc.
Chips processed as described herein can exhibit maintained tensile strength,
while suffering some loss of tear strength. Paper products made from the pulp
also
maintain tensile strength while losing some tear strength. The addition of the
enzyme
solution creates fiber weaknesses which allow the formation of shorter fibers
but also
enhance fiber fibrillation which is why tear is affected while tensile
strength is
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maintained. Fines production increases, thus lowering freeness at a given
specific
energy of refining SEC. The addition of the enzyme solution to chips reduces
the
amount of SEC needed to obtain a desired level of freeness.
A pulp produced by the methods described herein can be used in the production
of paper products, including, for example, cardboard, paper towels, newspaper,
and
hygiene products. The methods described herein can also be suitable for
textile
manufacturing.
EXAMPLES
Example 1 - Enzymatic activities
The commercial enzyme product, Celluclast 1.5LTm, was tested for several
enzymatic activities and was found to have several different types of
activities. The
following table list all relevant and significantly measurable activities and
protein
concentration.
Carboxymethyl cellulase (CMC) activity, equivalent to endo-f3-glucanase
activity,
was determined following the CMC method described in Measurement of Cellulase
Activities by T.K. Ghose (Pure & Appl. Chem. Vol 69, No. 2, pp. 257-268,
1987). The
amount of reducing sugars released from enzymatic hydrolysis of a 2% solution
of a
well characterized CMC during a 30.0 minute hydrolysis at pH 4.8 and 50 C is
used to
determine the enzymes EG activity. Sugar concentration is determined by the
well
known 3,5-dinitrosalicylic acid (DNS) solution method described by GI. Miller
(Analytical Chem., No. 31, p.426, 1959). The addition of the DNS solution to
the
hydrolysis filtrate stops the reaction. The mixture was boiled for 5.0 minutes
to allow for
color formation. After cooling, the absorbency is measured at 540nm and the
concentration is determined against a standard curve.
Mannanase activity was determined following the method describer by M. Ratto
and K. Poutanen (Biotechnology Letters, No 9, pp-661-664, 1988). The amount of
reducing sugars released from enzymatic hydrolysis of a 0.5% solution of
locust bean
gum during a 30.0 minute hydrolysis at pH 4.8 and 50 C is used to determine
mannanase activity. Sugar concentration is determined by the well known DNS
method
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described by G.L. Miller (Analytical Chem., No. 31, p.426, 1959) and described
thoroughly above.
Filter paper activity, equivalent to CBH activity, was determined following
the filter
paper assay method described in Measurement of Cellulase Activities by T.K.
Chose
(Pure & Appl. Chem. Vol 69, No. 2, pp. 257-268, 1987). This method uses the
amount
of reducing sugars released from enzymatic hydrolysis of Whatman No. 1 filter
paper
strip of known size during a 30.0 minute hydrolysis at pH 4.8 and 50 C to
determine the
enzymes CBH activity. Sugar concentration is determined by the well known DNS
method described by G.L. Miller (Analytical Chem., No. 31 , p.426, 1959) and
described
thoroughly above.
Protein concentration was determined using the Bradford assay. Bradford assay
kits purchased from Sigma-Aldrich were used. This well known method uses the
binding
of protein with a solution of Coomassie Blue which allows calorimetric
determination of
protein concentration based on a standard curve produced using bovine serum
albumin.
Absorbency is measured at 595nm.
Measured parameters of Celluclast
Parameter Value Unit
Endo-I3-glucanase 1860 CMCitYll
Mannanase activity 285 lUiml
Cellobiohydrolase 150 FPU/ml
Total protein 43 .4 mg/ml
Example 2 - Sugars released
The enzyme solution was added to destructured chips (200 g ODP) using the
solutions filter paper activity as a dosage indicator. Different compression
conditions at
5FPU/g OD (10 and 20 minutes held under compression) and controls were done in
duplicate and measured in duplicate for a total of four data sets. Hydrolysis
was carried
out at a consistency of 10%, a temperature of 50 C and a time of 1 hour. After
which,
the samples were filtered and the filtrate was treated using the well known
3,5-
dinitrosalicylic acid (DNS) solution method described by G.L. Miller
(Analytical Chem.,
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Na. 31, p.426, 1959). The addition of the DNS solution to the hydrolysis
filtrate stops the
reaction. The mixture was boiled for 5.0 minutes to allow for color formation.
After
cooling, the absorbency is measured at 540nm and the concentration is
determined
against a standard curve. This is also shown in Figure 1.
Sugars released during lab-scale compression testing 5FPUig OD Celluclast
151.TM
T reatment Sugars released into Standard
deviation
!jam (meg ()DPI (rnaki ODP)
Destructured chips 0 compression
0.08
OFPU/g OD(- control)
Destructured chips 0 compression
2.27 0.31
5FPU/g OD( control)
Destructured chips 10 minutes
2.80 0.24
compression 5FPU/g OD
Destructured chips 20 minutes
3.03 0.41
compression 5FPU/g OD
Example 3 - Freeness
The enzyme solution was added to destructured chips (200 g ODP) using the
solutions filter paper activity as a dosage indicator. Different compression
conditions at
5FPU/g OD (10 and 20 minutes held under full compression) and a control were
done in
duplicate. Hydrolysis was carried out at a consistency of 10%, a temperature
of 50 C
and a time of '1 hour. After this treatment, chips were dewatered to 20%
consistency
and refined in three stages using a KRK refiner with disc gaps of 0.5,0.3 and
0.15mm.
Refined pulp was collected and moisture was checked prior to measuring
Canadian
Standard Freeness (CSF). Results are shown in the following table and Figure
2.
Freeness of pulp treated with Celluclast 1.5L.TM trials before refining
Treatment CSF(mi) Standard deviation (ml)
Destructured chips 0 compression
182 3
OFPU/g OD(- control)
Destructured chips 0 compression
176 4
5FPU/g OD(+ control)
Destructured chips 10 minutes
160 2
compression 5FPU/g OD
Destructured chips 20 minutes 169 3
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CA 02804661 2013-01-31
compression 5FPU/g OD
Example 4 - Energy savings
The enzyme solution was added to destructured chips (200 g ODP) using the
solutions filter paper activity as a dosage indicator. Different compression
conditions at
10FPU/g OD (10 and 20 minutes held under full compression) and a control were
done
in duplicate. Hydrolysis was carried out at a consistency of 10%, a
temperature of 50 C
and a time of 1 hour. After this treatment, chips were dewatered to 20%
consistency
and refined in three stages using a KRK refiner with disc gaps of 0.5, 0.3 and
0.15mm
and a control were done in duplicate. Energy consumption was monitored with an
online
monitor and networked computer. Results are shown in the following table and
in Figure
3.
Specific energy consumption (SEC) obtained during refining of destructured
wood chips treated with Celluclast" 1.51-
T Net SEC Standard
EneroV
reatment
average (kWh/0 deviation (kWh/t) savings (%)
Destructured chips 0
compression OFPU/g OD 3018.5 0 0
(- control)
Destructured chips 0
compression 10FPU/g OD 3046 53.0 +0.91
(+ control)
Destructured chips 10 minutes
2671 102.5 -11.5
compression 10FPU/g OD
Destructured chips 20 minutes
2673.5 99.0 -4.8
compression 10FPU/g OD
* No-load energy consumption (3 minutes of warm up energy was calculated to be
0.12456 kWh) was subtracted from the meter reading to give the net energy
consumption
All patents, applications and publications mentioned above and throughout this
disclosure are incorporated in their entirety by reference herein.
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