1. 2011‐08‐01
PULP AND PAPER SLUDGE AS A
BINDER AND FORMALDEHYDE
SCAVENGER IN MEDIUM-
MEDIUM-
DENSITY FIBERBOARD
Sébastien Migneault (Laval University)
Ahmed Koubaa (University of Québec in Abitibi-Témiscamingue)
Bernard Riedl (Laval University)
Hamid Nadji (Laval University)
j ( y)
James Deng (FPInnovations - Forintek Division)
Tony Zhang (FPInnovations - Forintek Division)
FPS 65th International Convention, Portland OR, June 2011
BACKGROUND
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2. 2011‐08‐01
PULP AND PAPER SLUDGE
Primary sludge (PS): solid matter removed in
primary water treatment process
PS contains wood fibers, inorganics, others
Secondary sludge (SS): solid matter obtained
after secondary treatment, or biological
treatment
Main organic components of SS: microbial
extracellular polymeric substances (EPS), non-
(EPS) non
biodegraded materials, microbial cell biomass,
others (Bitton 2005)
EPS is rich in proteins
ADHESIVES FOR MDF
Urea-formaldehyde (UF) resin widely used for
medium-density fiberboard (MDF)
y ( )
Increasing demand for environmentally friendly
products
Severe legal restrictions on formaldehyde
(HCHO) emissions from wood products
Wood composites were glued with protein-
protein
based adhesives in early 1900s until 1960s
SS contains proteins…
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3. 2011‐08‐01
ADHESIVE PROPERTIES OF SS
Pulp
100%PS
80%PS+20%SS
60%PS+40%SS
(Zerhouni 2010)
ADHESIVE PROPERTIES OF SS
(Geng et al 207b)
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4. 2011‐08‐01
PREVIOUS STUDIES
Recent studies have proposed recycling PS as a
fiber source for wood-based panels
p
Davis et al 2003
Geng et al 2006, 2007a
Migneault et al 2010
Taramian et al 2007
Minimum industry quality requirements are
often satisfied
Always a reduction in panel quality when
sludge is added in panels
PREVIOUS STUDIES
2.0 50
Pa)
Pa)
40
Bending MOR (MP
IB strength (MP
1.5 R² = 0.8367
30
1.0
20
0.5
10 R² = 0.8445
0.0 0
0 10 20 30 40 0 10 20 30 40
Ash content (%) Ash content (%)
(Migneault et al 2010)
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5. 2011‐08‐01
OBJECTIVES
OBJECTIVES
Study the adhesive properties of SS
Evaluate the potential of SS as a bonding
agent and HCHO scavenger in MDF
Better understand the relationship
between sludge characteristics and panel
properties
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6. 2011‐08‐01
MATERIAL AND
METHODS
SLUDGE COLLECTION, REFINING,
AND CHARACTERIZATION
PS and SS collected from 3 pulp & paper mills
1. Thermomechanical (TMP)
( )
2. Chemico-thermomechanical (CTMP)
3. KRAFT
Production based on chips from commercial eastern
softwood species : spruce, balsam fir, pine (SFP)
Sludge mixed at three SS:PS ratio : 1:9, 2:8, 3:7
corresponding to 10% SS, 20% SS, 30% SS content
SS SS
Refined in TMP disc refiner and dried to 3% MC
Sludge characterized for chemical composition and
buffering capacity
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7. 2011‐08‐01
BONDING PROPERTIES OF SUDGE
Sludge samples were hot-pressed and characterized to
evaluate the adhesive properties of SS
Binderless sludge panels (no fibers, no resin, only PS
and SS)
Factorial plan: the 3 pulping processes and the 3 SS:PS
ratios
Density of 1100 kg/m³ and 210°C for 8 minutes
( p
(optimized in Geng et al. 2006)
g )
Samples tested for internal bond (IB) strength and
thickness swell (TS)
Bonding mechanisms were studied using FTIR, XPS
and chemical composition of sludge
MDF PROCESSING AND
CHARACRTERIZATION
Panels processing
Sludge and wood fibers (1:1), UF resin, wax
(1:1) resin
Fibers: TMP white birch (underutilized species)
Sludge from 2 mills: TMP, CTMP (KRAFT rejected)
UF content reduced from 12% to 8% and replaced by
SS as a binder (5%SS to 15%SS)
Panel characterization
Internal bond (IB) strength (ASTM D 1037)
Thickness swell (ASTM D 1037)
Formaldehyde (HCHO) emissions (ASTM D 5582)
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8. 2011‐08‐01
RESULTS
Part 1: Bonding properties of sludge
(binderless sludge panels)
PICTURES OF SLUDGE
Photos of refined and dried sludge (15X)
TMP CTMP KRAFT
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10. 2011‐08‐01
XPS BEFORE vs. AFTER PRESSING
High resolution carbon peak
C1 : Unoxidized carbon atom (ie C-C, C-H), mainly lignin and extractives
C2 : Carbon with one bonded oxygen (ie C-O), mainly carbohydrates
C3 : Carbon with two bonds with oxygen (ie O C O C O) mainly carbohydrates
O-C-O, C=O),
C1 (69%)
C1 (51%)
C2 (24%)
C2 (39%)
Intensity
Intensity
C3 (4,0%)
C3 (7,1%)
I
283 285 287 289 283 285 287 289
Binding energy (eV) Binding energy (eV)
RESULTS
Part 2: Medium-density fiberboards (MDF)
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11. 2011‐08‐01
HCHO EMISSION LEVELS
0.35
0.30
HCHO (µg/L)
0.25
0.20
0.15
0.10
0.05
0.00
Control TMP CTMP Control TMP CTMP
Low SS High SS
Normal UF Reduced UF
IB STRENGTH
2.0
Pa)
IB strength (MP
1.6
16
1.2
0.8
0.4
B
0.0
Control TMP CTMP Control TMP CTMP
Low SS High SS
Normal UF Reduced UF
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12. 2011‐08‐01
THICKNESS SWELL
30
Thickness swell (%)
25
20
15
10
5
0
Control TMP CTMP Control TMP CTMP
Low SS High SS
Normal UF Reduced UF
PH AND BUFFER CAPACITY
10
Alkaline buffering capacity
8 (mmol per 100 g sample)
pH
5.8 5.8
6 5.2
4.9
3.9
4
2
0
Low High Low High Birch
TMP CTMP fibers
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13. 2011‐08‐01
CONCLUSIONS
PS contains fibers
SS has adhesive properties
SS can be used as HCHO scavenger in MDF
The bonding effect of SS in MDF (i.e. when
combined with UF) was lower then expected
because of high pH and buffering capacity
(need for further research)
SS negatively impacted panels TS (need for
further research)
Thank you
Questions?
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