Life-Cycle Inventory model for the thermal treatment of municipal solid waste

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.


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



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.


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


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).


Relative impact

Documents

Life-Cycle Inventory model for the thermal treatment of municipal solid waste