Biogas production from the pulp and paper production processes - Prof. Jörgen Ejlertsson
1. Biogas from the pulp and paper
industry effluents
Jörgen Ejlertsson R&D Director, VP, Professor
EBA: The Netherlands
October 1st 2014
2. Agenda
● Introduction
● Background
● Partners and the project
● Approaches, assumptions and methods
● Biogas from Mechanical pulp mills effluents
● Overview
● Conclusions
● Biogas from Kraft pulp mill effluents
● Overview
● New approaches
● Conclusion
● Summary
2
3. Scandinavian Biogas in brief
● Founded in December 2005
● Former Prime Minister of Sweden Göran
Persson is Chairman of the Board
● Ability to prove and optimize concepts in
both laboratory, pilot and full scale.
● Head office in Stockholm
● Operations in Sweden and South Korea
● BOO and BOT business model
● 40 employees
3
4. Background: The Swedish pulp & paper industry
● Sweden have about 8% of global pulp production:
● Europe have ~25% global production and Sweden have ~30% of European
pulp production
● Practically the COD/TOC in Swedish effluents could give rise to ~100 Mm3 of
methane – 1000 GWh
● Biogas production today: 85 GWh generated from one plant – sulphite Kraft
pulp
● Very large process volumes with current techniques
● Miss-trust for anaerobic treatment for PPI effluents from the PPI-branch
– activated sludge always works…
● Need of know-how – technique providers as well as PPI personal
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5. Background: The Swedish pulp & paper industry
● Production: mechanical pulp – 12 mills
● Total: 3 600 kton year-1
● Average: 300 kton year-1
● Net sales ~140 MEuro per mill-1 year-1
● Production: Kraft pulp – 25 mills
● Total: 8 200 kton year-1
● Average: 330 kton year-1
● Net sales ~160 MEuro per mill-1 year-1
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Operations at 35 locations
6. Background: Biogas production in Sweden
● 1 600 GWh of biogas was produced 2012
Sewage treatment
Co-digestion
Farm-scale
Industrial
Landfills
Energigas Sverige, 2012
● Practically the Swedish P&P industry could add ~1000 GWh
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7. The project: Establishing biogas production in the
Swedish pulp & paper industry
● Partners
● Linköping University
● Scandinavian Biogas Fuels
● Pöyry Sweden AB
● Pulp & Paper Producers
● Equipment Supplier (UASB using EGSB technique)
● Financing
● Swedish Energy Agency 65%
● Partners 35%
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8. The project: Establishing biogas production in the
Swedish pulp & paper industry
● Research project led by Linköping University, Department of
Thematic Studies
● Prof. Bo Svensson, Ph.D. Annika Björn and
Adj Prof Jörgen Ejlertsson
● Objectives
● Show that methane production is possible from various process
streams at pulp and paper mills
● Reduce the investment cost per produced Nm3 of methane
● Biogas information and awareness to the P&P industry
● Targets:
• 45% of COD in PPI effluents converted to CH4
• 100 Mm3 CH4 from PPI effluents
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9. Current treatment of process water streams at PPI
Process water from factory
Pre-sedimentation Waste activated sludge
Recipient
Fiber sludge
Sludge dewatering
Sludge tank
Bio sludge
Sludge cake to
incineration or compost
Rejected water
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10. Possible treatment of process water streams at PPI
Process water Pre-sedimentation or
from factory
Waste activated sludge
Recipient
Fiber sludge
Sludge dewatering
Sludge tank
Bio sludge
Biogas
Sludge cake to
Incineration or compost
Rejected water
Biogas
UASB
CSTR
Internal substrates:
Methanol
Fibers
CSTR
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11. Possible treatment of process water streams at PPI
Process water Pre-sedimentation or
from factory
Waste activated sludge
Recipient
Fiber sludge
Sludge dewatering
Sludge tank
Bio sludge
Biogas
Sludge cake to
Incineration or compost
Rejected water
Biogas
UASB
CSTR
Internal substrates:
Methanol
Fibers
CSTR
Concentrated process water
streams from factory
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12. Biogas
Completely Stirred
Liquid phase
Tank Reactor (CSTR) with
sludge re-circulation
Assumed techniques
UASB techniques
IC or EGSB- Reactors
Rötkammare substrate
Solid phase
Solids re-circulation
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13. Methods
● Sampling at 7mills and 10 PPI processes
● About 80 wastewater streams were sampled and characterized
● Kraft, CTMP and TMP processes were included
● TOC, COD, Flows, Temperature, pH
● Methane potentials via anaerobic batch digestion assays
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COD kg/m3 (measured)
flöde m3/min
CH4
Yield %
of
theor. (end/max)
D0 EOP D1
Y:-‐83/2 Y 3/4
COD:
0,6 COD 6,2
PM
9
PM7
Yield 21/21 Yield -‐20/56
COD 6,1 Yield 42/42 COD 0,2
Flöde 0,33 COD -‐/3,7 Yield -‐43/13 Flöde 12,77
Flöde 7,50 COD 1,0
flöde 11,17
Yield 13/22 Yield 8/15 1)
After
PM
COD 1,3 COD 1,4 2)
D0
Flöde 23,82 Flöde 16,67 3)
EOP
5
Yield 28/28 4)
COD 3,4 5)
Flöde 30,00 Yield 4/17 6)
Bleaching
Yield 15/22 COD 1,3 7)
Before
presed
COD 1,5 8)
After
presed
Flöde 30 9)
Debarking
10)
Tot
fluting
11)
After
presed
+
bleaching
Debarking
Bleaching
D
(EOP)
D
P
9
TM1
PM8
Presed.
1
PM4
P
Pulping
2
Pulping 1
10
4
7 8
NSSC
leachate
Sodahus
6
11
2 3
14. Methods
● Laboratory reactor tests to identify needs for nutrition additives and
optimize the hydraulic retention time etc.
● Upflow Anaerobic Sludge Bed (UASB) reactors in lab-scale
● Continuous Stirred Tank Reactor (CSTR) sludge recirculation in lab-scale
● Pilot scale UASB (EGSB) at pulp- and paper mills
● Cover variations in the wastewater characteristics
● Minimize storage effects
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15. Agenda
● Introduction
● Background
● Partners and the project
● Approaches, assumptions and methods
● Biogas from mechanical pulp mills
● Overview
● Conclusions
● Biogas from Kraft pulp mill effluents
● Overview
● New approaches
● Conclusion
● Summary
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16. A typical Thermo mechanic pulp mill
Production of pulp: 500 kton year-1
TMP mill Bleaching
Plant
Paper
Machine
WWTP
9.9 ton COD day-1
5.2 GWh CH4 year-1
11 ton COD day-1
8.6 GWh CH4 year-1
38 ton COD day-1
23 GWh CH4 year-1
Total potential:
37 GWh CH4 year-1
Effluent water
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Product
15 000-30 000 m3/d
17. Suggested treatment of (C)TMP process water streams
Process water from factory
Pre-sedimentation Waste activated sludge
Recipient
Fiber sludge
Sludge dewatering
Sludge tank
Bio sludge
Biogas
Sludge cake to
Incineration or compost
Rejected water
Biogas
UASB
CSTR
Other substrates:
External
Concentrated process water
streams from factory
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18. Results so far: 2013-2014 - TMP + CTMP
● Most efficient biogas production obtained by treating
whole effluent using UASB technique
● Total bio-available biogas potential in Sweden:
290 GWh Methane (29 milj Nm3 CH4/y )
● Challenges – changed performance strategy and
addition of extra chemicals/nutriments:
● Bleaching chemicals (H2O2)
● Inhibitory resins from cooking of wood
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19. Agenda
● Introduction
● Background
● Partners and the project
● Approaches, assumptions and methods
● Biogas from mechanical pulp mills
● Overview
● Results and conclusions
● Biogas from Kraft pulp mill effluents
● Overview
● New approaches
● Results and conclusion
● Summary
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20. An average Kraft pulp Mill – soft wood
Production: 330 kton/yr
Pulp mill Bleaching
Plant
Paper
Machine
WWTP
0.6 ton COD/day
0.0 MNm3 CH4/yr
0.7 ton COD/day
0.1 MNm3 CH4/yr
2.2 ton COD/day
pH 10
0.3 MNm3 CH4/yr
0.2 ton COD/day
pH 2
0.0 MNm3 CH4/yr
Effluent
Total potential:
4 GWh CH4 year-1
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20 000-40 000 m3/d
21. Ongoing Research Kraft pulp Mill – new approach
Pulp mill Bleaching
Plant
Paper
Machine
CSTR WWTP Internal
Alternative
Substrates
• Bio sludge
• Condense methanol
• Fibers
Total potential:
25 GWh CH4 year-1
Effluent
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20 000-40 000 m3/d
22. Suggested treatment of Kraft pulp water streams
Process water from factory
Pre-sedimentation Waste activated sludge
Recipient
Fiber sludge
Sludge dewatering
Sludge tank
Bio sludge
Biogas
Sludge cake to
Incineration or compost
Rejected water
Biogas
UASB
CSTR
Other substrates:
Methanol
Fibers
External
Concentrated process water
streams from factory
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23. Results so far: 2013-2014 - Kraft pulp
● Total process flow and some individual effluents to be treated in activated
sludge
● Low concentration (< 1000 mgCOD/L)
● Generally low anaerobic COD/TOC reduction (<20%)
● Strong acid/base effluents
● Ongoing research: to treat mixed concentrated bleach streams prior UASB
● However: Positive results from ongoing research to treat mixed
concentrated bleach streams prior UASB – profitability?
● Condensates, fibrous solids and bio-solids are suitable for biogas
production (CSTR)
● Perform COD reduction in active sludge with aim for high bio-solid
production. Then anaerobic digestion.
● Total bio-available biogas potential in Sweden: 650 GWh/y
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24. Agenda
● Introduction
● Background
● Partners and the project
● Approaches, assumptions and methods
● Biogas from mechanical pulp mills
● Overview
● Results and conclusions
● Biogas from Kraft pulp mill effluents
● Overview
● New approaches
● Results and conclusion
● Summary
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25. Biogas production at PPI – End users
Internal:
● Heat and power
production
● Boilers with environmental
restrictions
● Replacement of fossil fuel
● IR-drying of coating
● Vehicle fuel
● Used for own vehicles
External:
● Vehicle fuel
● Up-graded and sold on the
market
● Raw gas sales to gas
company for upgrading to
vehicle fuel
● Green gas
● Up-graded and injected to
gas grid as green gas
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26. The change in usage of fiber products
– a possibility for biogas at PPI mills? 26
● Decreasing demand of
printing paper leads to
upshift in quality
- Finishing
- Bleaching
- Coating
- Final products
● Resulting in higher load
on current WWTP -
Environmental Demands
27. Establishing biogas production in the Swedish
pulp & paper industry - Concluding remarks
● Anaerobic treatment of effluents from pulp & paper mills is an alternative
to expanding aerobic wastewater treatment plants.
● Different strategies for wastewater treatment and biogas production need
to be followed depending on raw material and production process at the
specific mill
● The methane potential from an average mill is in the range of 10-50 GWh
year-1
● The total methane potential from the Swedish pulp and paper industry is
in the range of 700-1 000 GWh year-1. Of this methane potential approx.
300 GWh year-1 is located at the mechanical pulp and paper mills.
● Pulp & paper mills are located outside traditionally “substrate-rich” areas
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