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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9. 2011‐08‐01
BINDERLESS SLUDGE SAMPLES
2.0
es
ative propertie
TMP
1.8
CTMP
IB
1.5 KRAFT
1.3
1.0
Rela
0.8 TS
0.5
0 10 20 30 40
SS content (%)
CORRELATIONS
2.0 2.0
TMP TMP
1.6 CTMP 1.6 CTMP
IB strenght (MPa)
IB strenght (MPa)
KRAFT KRAFT
1.2 1.2
0.8 0.8
0.4
04 0.4
04 R
R² = 0.7473
R² = 0 9115
0.9115
0.0 0.0
0.0 0.3 0.6 0.9 1.2 1.5 20 23 26 29 32
Nitrogen content (%) Lignin content (%)
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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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