Sustainable Landfills: The Future of Land Disposal of Municipal Solid Waste (MSW)

1. Sustainable Landfills: The Future of Land Disposal of Municipal Solid Waste (MSW) Patrick Hettiaratchi Associate Professor, Department of Civil Engineering & CEERE ( Center for Environmental Engineering Research & Education) Faculty of Engineering, University of Calgary Chair, Environmental Engineering Division (EED), Canadian Society for Civil Engineering (CSCE) April 17, 2003 Presentation to CSCE – Calgary Section

2. Sustainable Landfills Landfills that are designed and constructed to achieve Sustainable Development (SD), or …… designed and constructed using SD principles Sustainable Development is “development that meets the needs of the present without compromising the ability of future generations to meet their own needs (1987 UN Commission on SD; Bruntland Report)” Sustainable Development is “Common-Sense”

3. Sustainable Development & Engineering SD is Common-Sense ……. Engineering is “common-sense application of technology to meet human needs (current and future)” Engineers have no choice, but to apply SD principles in their practice • Sustainable Infrastructure • Sustainable Transportation • Sustainable Landfills

4. Reduce Reuse Sustainable Landfills Landfills…… …… designed and constructed using SD principles SD Principles…. Recycle (or recovery of Recyclables) Recovery (of Energy and Compost) Current Landfilling Practice…. • Is this Sustainable? • Are we applying SD principles in Landfill development now? (you be the judge…..)

5. But, still common practice in most developing countries!!!!! Open Dumps, Sanitary Landfills and Sustainable Landfills:a Natural Progression?? Past: We started with Open Dumps…….. (until someone showed that it is not a good practice)

6. Today: We have converted Open Dumps to Sanitary Landfills ….. Conventional “dry-tomb type” Sanitary Landfills are designed and constructed to eliminate problems associated with “Open Dumps”

7. “Dry Tomb” landfill • Leachate can contaminate Groundwater (unseen) or Surface Water (obvious) Area A Area B Working Face (Area D) Area C • Prevention of GW contamination with bottom liner systems Stream X-section along the length of the landfill Problem: Landfill Leachate • Leachate is “garbage juice” or an aqueous liquid produced within the landfill

8. Final cover Daily cover Intermediate cover Landfill Construction

9. Leave it Alone !!!!! R I P

10. Liability associated with landfill gas: • Landfill gas contains CH4 and CO2 (both are GHGs) 1/3 of anthropogenic CH4 in USA come from Landfills • If gas is extracted (for energy recovery)…. Possible to minimize concerns • In most cases, gas production is low; not economical to extract methane gas for energy recovery • Gas can be a major hazard (Ecuador example) Problems with the Dry-tomb Sanitary Landfillling Approach • Un-sustainable???Loss of Space…. Need to find new space every few years (Toronto, Edmonton) • Long-term liability: Need to monitor potential impact for a long- time (until waste stability is achieved)

11. X-section along the transverse direction Zambisa Landfill (Quito, Ecuador)

12. X-section along the transverse direction Zambisa Landfill (Quito, Ecuador)

13. Sustainable Landfill The Concept: • Holistic approach (not “piece-meal”) • Increase biological activity in landfill cell; possible to extract large quantities of gas in a short period of time • Stabilize the waste quickly (Anaerobic and Aerobic) • “Mine” the cell, and extract recyclables & compost • Reuse space

14. Sustainable Landfill Anaerobic Reactor

16. Sustainable Landfill Aerobic Reactor

17. Sustainable Landfill Operation (Calgary Biocell Concept) Anaerobic Year 1 Anaerobic Year 2 Mining/ Space Recovery Year 6 Anaerobic Year 3 Aerobic Year 5 Aerobic Year 4

18. What We Want….. What We Get Problems to Resolve Moisture Distribution Within the Cell

19. Leachate Pools: Created by “over-zealous” Leachate Recirculation

20. Problems to Resolve Surface Gas Emissions • Could occur during construction of the biocell (may take 1 or 2 years to completely fill a cell) • Significant quantities can escape from surface even with a gas capture system example: Loma Los Colorados Landfill, Chile

21. Loma Los Colorados Landfill, Chile

22. Loma Los Colorados (contd…) Gas Wells

23. Landfill Gas Incinerator CH4 burned= 85 tonnes/year (or 330 m3/d)

24. Loma Los Colorados Bioreactor Landfill Landfill Methane Budget: Total CH4 emitted/burned = 17,040 tonnes/year (exclude “leachate pool” emissions) More than 75% of the “produced methane gas” escapes across the cover soil (worth about $3 million/year in the “open Carbon market”)

25. Calgary Sustainable Biocell • Pilot Project (1 hectare: 50,000 tonnes of waste) • Partners/Participants: City of Calgary, University of Calgary and Stantech Consultants • Mitigation Measures: • Biocap, or Methane Oxidation Layer (MOL), to control methane gas emissions during construction and operation

26. CO 2 CH & CO Oxidation In landfill cover (Methanotrophs) Emissions Commercial 4 2 Emissions Recovery CH & CO 4 2 Generation CH & CO Lateral 4 2 Migration Landfill Bio-Caps or MOLs • A new concept • Use a naturally occurring bacteria to convert methane

27. Biofiltration of CH4 Microbially mediated oxidation of CH4 is carried out by methanotrophic bacteria (Methylomonas methanica)

28. CH4 Oxidation in Landfill Caps

29. Conclusions • Waste disposal has progressed from “open dumps” (in the past) to “sanitary landfills” (in the present). Sustainable Landfills could be the future. • Sustainable landfilling follows a holistic approach. It is consistent with the “current thinking” (in terms of SD). • Technical challenges need to be overcome, before Sustainable Landfill concept could be universally applied. • Civil Engineers should take a lead to role to ensure SD principles are adopted in the practice of land disposal. Thank You!