Swiss Federal Institute of Technology Zurich Safety and Environmental Technology Group Stefanie Hellweg, Gabor Doka, Thomas Hofstetter, and Konrad Hungerbühler International Waste Management and LCA Session B Prague, April 15-16, 2004 Life-Cycle Inventory model for the thermal treatment of municipal solid waste Life-Cycle Inventory model for the thermal treatment of municipal solid waste

The goal was to provide an LCI model for the thermal treatment of waste (different technologies). Incineration plant Collection/ transport Landfills Emissions Resources 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) S0.33 Cu0.011 Transfer coefficients (%) Flue Slag Other Waste gasresid.water S Cu Output (g/kg) Flue Slag Other Waste gasresid.water S7* Cu * =

Application: The choice of the landfill model determines the overall impact potential of the system waste incineration. Modern grate incinerator without with withwith with ther- residuemecha-thermalthermalmal slag recyclingnical slagslag filter ash+ filter ash treatm.treatm.treatm.treatment Thermo- select with me- tal recy- cling VS-Process withoutwith ther- residue mal filter recyclingash treat- ment Grate without proper flue gas cleaning Swiss ecopoints (UBP) / kg waste Landfill models: Short-termMedium/Long-termLong-term Obsolete Current Current + new New integrated technologies 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

Cd 2+ Pb 2+ Al 3+ Cu 2+ Ca 2+ Zn 2+ Al 3+ Pb 2+ Cu Time (years) Heavy metal concentrations in the leachate surpass the quality goals of the Swiss Water Protection Law. Log total dissolved concentration (mol / l)

The temporal occurrence of emissions to the groundwater depends on the site of the landfill. Cd 2+, site A Cd 2+, site B Cu 2+, site A Cu 2+, site B Tons / year / kg waste Time (years) Tons / year / kg waste Time (years)

UBP / kg waste Moderner Rost (1998) ohnemitmitmitmit them. Rück-mecha-therm.therm.Schlacken stands-nischerSchlacken FAund FA- recyclingBehandl.Behandl.Behandl. Behandl. Thermo- select mit Metall- recycling VS-Prozess ohnemit therm. Rück- FA- stands-Behand-. recyclinglung Rost ohne 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 Quo Waste is either recycled/composted or burned in grate incineration plants. Maximum Recycling Recycling/composting is increased to a feasible maximum. End-of-Pipe All municipal solid waste is incinerated in grate incineration plants. Technological Innovation All 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. Safety and Environmental Technology Group

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