sustainable landfills: the future of land disposal of municipal solid waste (msw)

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

Sustainable Landfills Landfills that are designed and constructed to achieveSustainable Development (SD), or

……… … designed and constructed using SD principlesdesigned and constructed using SD principles

Sustainable Development is Sustainable Development is “development that meets the “development that meets the needs of the presentneeds of the present without compromising the ability of without compromising the ability of

future generationsfuture generations to meet their own needs to meet their own needs (1987 UN (1987 UN Commission on SD; Bruntland Report)”Commission on SD; Bruntland Report)”

Sustainable Development is “Common-Sense”Sustainable Development is “Common-Sense”

Sustainable Development & Engineering Sustainable Development & Engineering

SD is Common-Sense …….SD is Common-Sense …….

Engineers have no choice, but to apply Engineers have no choice, but to apply SD SD principles in their practice principles in their practice Sustainable InfrastructureSustainable Infrastructure

Sustainable TransportationSustainable Transportation

Sustainable Sustainable LandfillsLandfills

Engineering is “common-sense application of Engineering is “common-sense application of technology to meet human needs (current technology to meet human needs (current and future)”and future)”

Sustainable Landfills Landfills…… Landfills……

……… … designed and constructed using SD principlesdesigned and constructed using SD principles

SD Principles….SD Principles….

Current Landfilling Current Landfilling Practice….Practice…. Is this Sustainable? Is this Sustainable? Are we applying SD principles in Landfill development now? Are we applying SD principles in Landfill development now?

(you be the judge…..) (you be the judge…..)

Reduce Reduce ReuseReuse

Recycle (or recovery of Recyclables)Recycle (or recovery of Recyclables)Recovery (of Energy and Compost)Recovery (of Energy and Compost)

Open Dumps, Sanitary Landfills and Open Dumps, Sanitary Landfills and Sustainable Landfills:Sustainable Landfills: a Natural Progression??a Natural Progression??

Past:Past: We started with Open Dumps…….. (until someone showed that it is not a good practice)

ButBut, still common practice in most developing countries!!!!!

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

Prevention of GW contamination with bottom liner systemsPrevention of GW contamination with bottom liner systems

Leachate is “garbage juice” or an aqueous liquid produced within the landfill

X-section along the length of the landfill

Stream

Area A

Area C

Area BWorking Face (Area D)

Leachate can contaminate Groundwater (unseen) or Surface Water (obvious)

““Dry Tomb” landfillDry Tomb” landfill

Problem: Landfill LeachateProblem: Landfill Leachate

Landfill ConstructionLandfill Construction

Final cover

Daily cover

Intermediate cover

Leave it Alone !!!!!Leave it Alone !!!!!

R I PR I P

Problems with the Dry-tomb Sanitary Problems with the Dry-tomb Sanitary Landfillling ApproachLandfillling 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)

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)

Zambisa Landfill (Quito, Ecuador)

X-section along the transverse direction

Zambisa Landfill (Quito, Ecuador)

X-section along the transverse direction

Sustainable LandfillThe Concept:The Concept: Holistic approach (not “piece-meal”)

Stabilize the waste quickly (Anaerobic and Aerobic)

“Mine” the cell, and extract recyclables & compost

Reuse space

Increase biological activity in landfill cell; possible to extract large quantities of gas in a short period of time

Sustainable LandfillSustainable Landfill

Anaerobic ReactorAnaerobic Reactor

Sustainable LandfillSustainable Landfill

Aerobic ReactorAerobic Reactor

AerobicYear 5

AerobicYear 4

AnaerobicYear 3

AnaerobicYear 2

AnaerobicYear 1

Mining/Space Recovery

Year 6

Sustainable Landfill OperationSustainable Landfill Operation(Calgary Biocell Concept)(Calgary Biocell Concept)

Problems to ResolveProblems to Resolve

Moisture Distribution Within the CellMoisture Distribution Within the Cell

What We Want…..

What We Get

Leachate Pools: Leachate Pools: Created by “over-zealous” Leachate RecirculationCreated by “over-zealous” Leachate Recirculation

Problems to ResolveProblems to Resolve

Surface Gas EmissionsSurface 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 witha gas capture systemexample: Loma Los Colorados Landfill, Chile

Loma Los Colorados Landfill, Chile

Disconnected gas wellConnected gas well

25

8

26

1

29

56

2

15

185

31

19

5730

10

9

5

6

4

27

14

7

12

11

16

22

20

24

2313

1721

28

90 metres

Gas Wells

Loma Los Colorados (contd…)

Landfill Gas Incinerator

CH4 burned= 85 tonnes/year (or 330 m3/d)

Total CH4 emitted/burned = 17,040 tonnes/year (exclude “leachate pool” emissions)

Loma Los Colorados Bioreactor LandfillLoma Los Colorados Bioreactor Landfill

More than 75% of the “produced methane gas” escapes More than 75% of the “produced methane gas” escapes across the cover soilacross the cover soil

(worth about $3 million/year in the “open Carbon (worth about $3 million/year in the “open Carbon market”)market”)

Landfill Methane Budget: Landfill Methane Budget:

Calgary Sustainable BiocellCalgary 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

Landfill Landfill Bio-CapsBio-Caps or MOLs or MOLs

A new concept

Use a naturally occurring bacteria to convert methane

CH4 & CO2Generation

CO2Emissions CH4 & CO2

EmissionsCommercialRecovery

CH4 & CO2 LateralMigration

Oxidation In landfill cover (Methanotrophs)

Biofiltration of CH4

Microbially mediated oxidation of CH4 is carried out by methanotrophic bacteria

(Methylomonas methanica)

CHCH44 Oxidation in Landfill Caps Oxidation in Landfill Caps

0

20

40

60

80

100

0 50 100 150 200 250 300

Time (days)

% M

etha

ne O

xidi

zed

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!Thank You!