Swiss Federal Institute of Technology Zurich Safety and Environmental Technology Group
Stefanie Hellweg, Gabor Doka, Thomas Hofstetter, and Konrad Hungerbühler
International Waste Management and LCASession BPrague, April 15-16, 2004
Life-Cycle Inventory model for Life-Cycle Inventory model for the thermal treatment of the thermal treatment of municipal solid waste municipal solid waste
The goal was to provide an LCI model for the thermal treatment of waste (different technologies).
Incineration plant
Collection/transport
Landfills
EmissionsResources
Waste disposal (1 kg MSW)Energy generation
Ancillaries
Municipal solid waste (MSW)
H O C S N Pb Cd Hg ...
Safety and Environmental Technology Group
Transfer coefficients were defined for the waste-input related emissions of the incineration process and landfills.
Safety and Environmental Technology Group
Four different landfill models:
• Short-term model: based on measurements• Medium-term model: based on leaching tests• Long-term time-dependent model:
geochemical simulations
EXAMPLE: modern grate (S,Cu)
Burnable waste fraction (g/kg)
S 0.33Cu 0.011
Transfer coefficients (%) Flue Slag Other Waste
gas resid. water
S 0.2 55.4 37.3 7.1Cu 0.0 80.1 19.9 0.0
Output (g/kg) Flue Slag Other Waste
gas resid. water
S 7*10-4 0.18 0.12 0.023Cu 0 0.009 0.002 0
* =
Application: The choice of the landfill model determines the overall impact potential of the system waste incineration.
Modern grate incineratorwithout with with with with ther-residue mecha- thermal thermal mal slag recycling nical slag slag filter ash + filter ash
treatm. treatm. treatm. treatment
Thermo-selectwith me-tal recy-cling
VS-Process without with ther-residue mal filterrecycling ash treat-ment
Grate without proper flue gas cleaning1 2 3 4 5 6 8
0
1000
2000
3000
4000
5000
Sw
iss
eco
po
ints
(U
BP
) / k
g w
aste
Landfill models: Short-term Medium/Long-term Long-term
Obsolete Current Current + new New integrated technologies
Safety and Environmental Technology Group
Safety and Environmental Technology Group
Results and Conclusions
• An LCI model was developed for the thermal treatment of solid waste (different technologies).
• User input data comprise composition of waste, technology specification, energy efficiency, and transport distances.
• Application: Comparison of the disposal of different materials, of thermal technologies, and of waste management scenarios
• Different landfill models are provided, which consider different time horizons. The choice of landfill model is a value-based decision.
• Case study results show that the choice of time horizon has a crucial influence on the results.
BACK-UP Slides
Landfill model: A one-dimensional transport and reaction model was used to simulate the pH development and the emission concentrations of a slag landfill as a function of time (slag from grate incineration).
Slag
Rainwater
Subsoil
Leachate
Gruppe für Umwelt und Sicherheitstechnologie
0
1
2
3
4
5
6
0 25000 50000 75000 100000 125000
0
2
4
6
8
10
0 25000 50000 75000 100000 125000
pH
val
ue
-8
-7
-6
-5
-4
Cd2+
Pb2+ Al3+
Cu2+
Ca2+
Zn2+
Al3+
Pb2+
Cu2+
-9
-3
Time (years)
Heavy metal concentrations in the leachate surpass the quality goals of the Swiss Water Protection Law.
Lo
g t
ota
l d
isso
lved
co
nce
ntr
atio
n
(mo
l /
l)
0
3E-13
6E-13
0 250,000 500,000
0
3E-12
6E-12
9E-12
0 250,000 500,000
The temporal occurrence of emissions to the groundwater depends on the site of the landfill.
0
1E-15
2E-15
3E-15
0 10,000 20,000
02E-144E-14
6E-148E-14
0 10,000 20,000
Cd2+, site A
Cd2+, site B
Cu2+, site A
Cu2+, site B
To
ns
/ yea
r /
k g w
a st e
Time (years)
To
ns
/ yea
r /
k g w
a st e
Time (years)
-600
-400
-200
0
200
400
600
800
1000
1200
UBP / kg waste
Moderner Rost (1998)ohne mit mit mit mit them.Rück- mecha- therm. therm. Schlacken stands- nischer Schlacken FA und FA- recycling Behandl. Behandl. Behandl. Behandl.
Thermo-selectmit Metall-recycling
VS-Prozess ohne mit therm.Rück- FA-stands- Behand-.recycling lung
Rostohne WRR
WRR: Weitergehende Rauchgasreinigung, FA: Filterasche
Veraltete aktuelle und neue neue integrierte Technologien
Luftemi-ssionen
Wasser-emissionen
Energie: Gas, CH Elektrizität
Energie: Öl, EU Elektrizität
Infra-struktur
Trans-port
Betriebs-mittel
Die Umweltauswirkungen des Verbrennungsprozesses sind mit denen eines europäischen Kraftwerks vergleichbar.
Application II: The goal was to identify and compare key environmental problems of waste management scenarios.
Status QuoWaste is either recycled/composted or burned in grate incineration plants.
Maximum RecyclingRecycling/composting is increased to a feasible maximum.
End-of-PipeAll municipal solid waste is incinerated in grate incineration plants.
Technological InnovationAll municipal solid waste is treated in new thermal plants.
Safety and Environmental Technology Group
Scenario Technological Innovation has the lowest overall impact on the environment.
0
0.01
0.02
0.03
0.04
0.05
0.06
Status Quo MaximumRecycling
End-of-Pipe TechnologicalInnovation
Eco
-indi
cato
r 99
poi
nts Waste
incineration
Materialrecycling
Energyproduction
Production ofnew materials
Safety and Environmental Technology Group
0
1
Recycling + energy Recycling + energy New thermal process + new material
Grate incine-ration + new material
Different energy mix
No credit for avoided fertilizer
Material recycling and new technologies generally score better than conventional end-of-pipe treatment (Eco-indicator 99, per kg material).
Safety and Environmental Technology Group
Relative impact
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