Enzyme Applications in Pulp and Paper:
An Introduction to Applications
Dr. Richard Venditti
Associate Professor - Director of Graduate Programs
Department of Wood and Paper Science
Biltmore Hall Room 1204
Raleigh NC 27695-8005
Tel. (919) 515-6185 Fax. (919) 515-6302
Email: [email protected]
Slides courtesy of Phil Hoekstra.
Endo-Beta 1,4 Xylanase
Enzymes
• Are proteins that catalyze chemical
reactions
• Biological cells need enzymes to
perform needed functions
• The starting molecules that enzymes
process are called substrates and
these are converted to products
Endo-Beta 1,4 Xylanase
Cellulase enzyme which acts on cellulose
substrate to make product of glucose.
Endo-Beta 1,4 Xylanase
Enzymes
• Are extremely selective for specific
substrates
• Activity affected by inhibitors, pH,
temperature, concentration of substrate
• Commercial enzyme products are typically
mixtures of different enzymes, the
enzymes often complement the activity of
one another
Endo-Beta 1,4 Xylanase
Types of Enzymes in Pulp and
Paper and Respective Substrates
•
•
•
•
•
•
•
Amylase --- starch
Cellulase --- cellulose fibers
Protease --- proteins
Hemicellulases(Xylanase) ---hemicellulose
Lipase --- glycerol backbone, pitch
Esterase --- esters, stickies
Pectinase --- pectins
Endo-Beta 1,4 Xylanase
Enzyme Applications
in Pulp and Paper
•
•
•
•
•
•
•
•
•
•
Treat starches for paper applications
Enhanced bleaching
Treatment for pitch
Enhanced deinking
Treatment for stickies in paper recycling
Removal of fines
Reduce refining energy
Cleans white water systems
Improve softness in tissue
Clean outs
Endo-Beta 1,4 Xylanase
Starch Conversion for Surface
Coatings
• Amylases are used to cleave starch
molecules to reduce the viscosity
• Used for surface sizing and for starch in
coatings
• Not used for dry strength agent additive
Endo-Beta 1,4 Xylanase
Bleaching
• Hemicellulases (xylanases) are used to
cleave hemicelluloses in fiber, making the
bleaching process more effective
• May be able to reduce bleaching
chemicals by up to 30%
• Can improve brightness
Endo-Beta 1,4 Xylanase
Pitch treatment
• Lipases used to control pitch in pulping
processes
• Converts tri-glycerides to fatty acids which
are more stable in water, won’t deposit as
much
Endo-Beta 1,4 Xylanase
CH2 –--------- CH –---------CH2
O
O
Triglycerides
O
Ester-Bonds
C=O
(CH2)15 CH3
C=O
C=O
(CH2)15 CH3 (CH2)15 CH3
glycerol
CH2 –--------- CH –---------CH2
│
OH
OH
OH
Fatty acids
OH
│
C=O
│
(CH2)15 CH3
Endo-Beta 1,4 Xylanase
Deinking
• Paper recycling inks and stickies attach to fibers
at the surface of the fibers, stuck to microfibrils
• Cellulase and hemicellulase enzymes hydrolyze
these microfibrils, releasing the adhesives
• Esterases help breakdown ink particles
• Enzyme assisted DI reported to remove 30-60%
more toners
• Enzyme assisted DI reported to improve
brightness by 4-5 points
Endo-Beta 1,4 Xylanase
Control and Removal Methods
for Stickies
– Use of environmentally benign adhesive (recyclable
adhesive)
– Avoidance: Control of recovered paper quality
– Mechanical removal: screening and water clarification
– Chemical control: polymers surfactants, others
– Passivation with inorganics
– Enzyme hydrolysis
– Physical adsorption to paper fibers: retention
– Dispersion
– Protection: treatment of equipment to limit deposits
– Mill shut down for clean-up
Endo-Beta 1,4 Xylanase
CLASSIFICATION OF STICKIES
PRIMARY
(Formed in
pulper)
SECONDARY
(Change in
environment, pH,
temp., etc.)
Endo-Beta 1,4 Xylanase
MACRO VS MICRO
STICKIES
Macrostickies
Retained on 6-cut
(0.15 mm) slotted
screen*
Microstickies
Accepted by 6-cut
(0.15 mm) slotted
screen*
Endo-Beta 1,4 Xylanase
* Trend is towards 0.10 mm or 0.075 mm slotted screen
Stickies Control
• Microstickies in dilution water recirculate
back into the systems
• Microstickies agglomerate under shear
and pH changes and contribute to
macrostickies, secondary stickies
• Reducing microstickies will make a
significant impact on macrostickies
• Ability to measure both micro and macro is
important
Endo-Beta 1,4 Xylanase
Endo-Beta 1,4 Xylanase
Without Proper Water Clarification (<20% reduction):
“ re-introduction of stickies”
Endo-Beta 1,4 Xylanase
Enzymes as stickies treatment
• Esterases used to break ester bonds in
polymers used in toners and adhesives
• Improved paper cleanliness
• Less deposits, less clean up on PM
• Can be used as substitute for talc or
solvent based dispersants
Endo-Beta 1,4 Xylanase
- (CH2 – CH - CH2 – CH - CH2 – CH )n -
PVAc
O
O
O
Ester-Bonds
C=O
C=O
C=O
CH3
CH3
CH3
PVAlcohol
Acetic acid
- (CH2 – CH )- CH2 – CH - CH2 – CH )n │
OH
OH
OH
OH
│
C=O
│
CH3
Endo-Beta 1,4 Xylanase
polyvinyl acetate
-(-CH2CH-)nOCOCH3
Hydrophobic
Surface
without Esterase
with Esterase
Agglomerates of PVAc
polyvinyl alcohol + acetic acid
-(-CH2CH-)nOH + CH3COOH
OH
OH
OH
OH
OH
OH
HO
OH
OH
OH
OH
HO
OH
HO
OH
HO
OH
OH
OH
OH
OH
OH
OH
OH
OH
HO
OH
OH
OH
OH
OH
OH
OH
OH
OH
HO
OH
HO
OH
OH
OH
OH
OH
OH
HO
OH
HO
OH
Polyvinyl alcohol
OH
Hydrophilic
Endo-Beta 1,4 Xylanase
Impact on stickies chemistry
• Optimyze has two impacts on stickies
– Cleaves ester bonds to reduce size of stickies
– Surfaces on smaller stickies are converted to
alcohol groups
• Alcohol groups are less tacky
• Alcohol groups are polar, which allow DAF
polymers to grab onto them for removal
Endo-Beta 1,4 Xylanase
Electron micrographs
Untreated
Treated
Endo-Beta 1,4 Xylanase
Optimyze Plus 735 trial data
stickies transfer on reel samples
during Optimyze Plus 735 evaluation
140
PPM
1
BLX dosage
120
stickies
1.2
count
0.8
100
80
0.6
60
0.4
40
0.2
20
0
2/12
BL X 13064 d o sag e (lb /t)
160
0
3/4
3/24
4/13
5/3
5/23
Endo-Beta 1,4 Xylanase
Caustic replacement:
neutral deinking for newsprint deinking
• Caustic is used in pulping recycled fibers
to swell fibers, improving paper making
potential
• Cellulase enzymes can be used in
conjunction with or as a substitute for the
caustic to swell fibers
• Neutral deinking has some advantages
including less COD in the white water,
lower costs
Endo-Beta 1,4 Xylanase
Decrease energy in refining
• Cellulase enzymes cause partial
depolymerization of cellulose and swelling
of fibers, more flexible fibers
• Reduction of fines
• Improves efficiency of refining, can
decrease energy consumption or obtain
improved strength at higher freeness
• Often better runnability or less dryer
energy required
Endo-Beta 1,4 Xylanase
Fibrillation
3/3/2010
Endo-Beta 1,4 Xylanase
Fiber Modification
• Enzymes can assist this de-lamination
process
• Conditions fiber for refining
• Reduces refining energy
• Changes the refining curve
• Old rules do not apply
• Laboratory Testing
Endo-Beta 1,4 Xylanase
Case History
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MILL:
FIBER:
GRADE:
GOAL:
• METHODS:
Quebec
Recycled/Softwood Kraft
Napkin
Increase tensile strength to
middle of specification, reduce
kraft fiber usage
Treated MOW stock at the pulper
with 0.5 to 1.0 kg/tonne BZM 2545,
about 3 hours of contact time
Endo-Beta 1,4 Xylanase
Machine Trial of Buzyme 2545
in Napkin grade
45
275
40
270
35
265
25
260
20
15
Tensile Strength
Kraft Usage (%)
30
SWK Usage
Tensile
255
10
250
5
0
245
Pre-trial
Trial
Endo-Beta 1,4 Xylanase
Machine Trial of Buzyme 2545
in Napkin grade
25
300
250
20
15
150
10
Tensile Strength
Kraft Usage (%)
200
SWK Usage
Tensile
100
5
50
0
0
Pre-trial
Trial
Refining energy reduced
Endo-Beta 1,4 Xylanase
Results: Machine Trial of Buzyme 2545
in Napkin grade
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•
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Reduced kraft from 40% to 0% of furnish
Increased tensile to a “comfortable” range
Refining energy reduced 14%
Drainage is better, but cannot take
advantage of it, due to drive limitations
Endo-Beta 1,4 Xylanase
Hydrolysis of fines
• Fines build up in water loop in PM and
cause drainage, formation and paper
properties problems
• Cellulase enzymes hydrolyze these fines,
making them soluble, improving PM ops
• Can run PM faster (up to 10% faster in
some cases?)
Endo-Beta 1,4 Xylanase
Softness in tissue
• Cellulase enzymes improve softness by
hydrolyzing cellulose in fibers, creating
weak spots in fibers, making fibers flexible
• Softness increases of up to 25%
• P&G has several patents, some donated
to NCSU
Endo-Beta 1,4 Xylanase
Case History
•
•
•
•
MILL:
FIBER:
GRADE:
GOAL:
• METHODS:
Quebec
95% SWD/5% Recycled Fiber
Premium Bath
Reduce refining energy, increase
softness and bulk, maintain
tensile
Treated stock at the pulper with
0.5 to 1.0 kg/tonne BZM 2545,
about 3 hours of contact time
Endo-Beta 1,4 Xylanase
Bulk vs. Tensile
Buzyme 2535 vs. Glyoxylated Polyacrylamide
11
Average Bulk to Tensile
Increase of 3.5%
B/BW
10
9
8
7
12
14
16
18
20
GMT/BW
Buzyme 2535
Gloxylated PAM
Linear (Buzyme 2535)
Linear (Gloxylated PAM) Endo-Beta 1,4 Xylanase
22
Results
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Shut down refiners
Maintained tensile
Bulk/basis weight increased by avg. of 3.5%
Able to reduce BWT due to increase in tensile
Machine speed increase of 100 FPM, due to
better drainage
Endo-Beta 1,4 Xylanase
ROI for Fiber Modification
• Reduction in refiner energy
• Less fines generation
– Better drainage
– Softer feel
– Less dusting
– Cleaner white water
• Reduction in starch or CMC
• Fiber substitution
– Could use more MOW, less virgin
Endo-Beta 1,4 Xylanase
Improved biodegradability of pulp
mill waste water
• Cellulases and Hemicellulases used to
degrade cellulose and other high
molecular weight polymers
• COD/BOD ratio of domestic sewage 2:1
• COD/BOD ratio of paper mill waste water
up to 5:1
• Hydrolysis of cellulose fines by enzymes
to lower molecular weight sugars that are
more biodegradable
Endo-Beta 1,4 Xylanase
Clean Ups / Boil Outs
• Amylase to treat starch deposits in clean
ups of starch preparation/application
equipment
• Protease used as biodispersants or
enzyme boil-outs, cleave protein
molecules in deposits and solubilize
deposits
Endo-Beta 1,4 Xylanase
Summary
• Enzymes are green chemicals that can
improve operations in pulp and paper
• Wide variety of enzymes, must be
applied with understanding of how they
work
• Several widely accepted applications,
starch, bleaching, clean ups
• Future: high valued functionalized fibers,
improved pulping, specialized paper
properties, conversion of wastes to
fermentable sugars.
Endo-Beta 1,4 Xylanase