Evolution of Landfill Technology:

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Evolution of Landfill Technology South American
Context
Dr. Patrick Hettiaratchi Department of Civil
Engineering Faculty of Engineering, University
of Calgary Chair, Environmental Engineering
Division (EED), Canadian Society for Civil
Engineering (CSCE) June 22, 2005
University of San Fransisco De Quito Quito,
Ecuador
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Sanitary Landfill Technology
Presentation

• What are sanitary landfills?
• The evolution from open dumps to current
  conventional landfills

• How technology is used to minimize landfill
  problems?
• Future of landfilling bioreactor
  landfills/sustainable landfills??

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History of Landfilling Open Dumping A way of
life.
Past was the accepted way of getting rid of our
waste (until someone showed that it is not a
good practice)
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Open Dumps
are unsightly
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Open Dump near Bangkok, Thailand
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Scavengers in Quito, Ecuador
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Earning a living Quito, Ecuador
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Landfills Produce Leachate or Garbage Juice
The Problem

• Leachate is an aqueous solution containing high
  
• concentrations of inorganic and organic
  pollutants

• Leachate BOD can be as high as 20,000 mg/L
• (compare with domestic sewage BOD of 250 mg/L)

• Leachate can cause Surface-water and
  Groundwater contamination

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Leachate pool.on surface!!!
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• Landfill Technological Solutions
• In 1980s, we converted Open Dumps to Sanitary
  Landfills ..
• Dry-tomb type Sanitary Landfills are designed
  and constructed to eliminate problems with Open
  Dumps

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Approaches to control water contamination

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

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Landfill Construction
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Leave it Alone !!!!!
R I P
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Current Practice of Sanitary Landfill
Engineering in South America

• Excellent leachate escape control Extensive
  use of geo-membrane liner systems with leachate
  collection

• In-adequate leachate production control
  Landfills are kept open for too long

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Sanitary Landfills in South America Leachate
Management Alternatives

• Build smaller cells (smaller area, but deeper),
  close the cell quickly with an evapo-transpirativ
  e cover. Result decrease leachate production
  with time

• Avoid leachate treatment by transporting to a
  nearby sewage treatment plant. Since quantities
  are small, this is viable and cost effective (not
  in Quito .. Combined sewage and leachate
  treatment in Inga???)

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Performance-based Design of Sanitary Landfills
The Common-sense Approach ..

• Performance-based Design Optimal design for a
  defined performance of the landfill components.
• Example Leachate management required only if
  groundwater contamination is unacceptable.
• Sometimes expensive liners may not be required
• Inga in Quito,
• Dona Juana in Bogota
• Loma Los Colorados in Santiago

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Performance-based Design of Landfills The
Common-sense Approach

• Performance-based design is practiced in
• United States (allowed under Sub-title D
  landfill regulations)
• Canada (sometimes known as the natural
  attenuation landfill)

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Performance-based Design of Landfills The
Common-sense Approach
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Other Problems with the Dry-tomb Sanitary
Landfillling Approach

• Un-sustainable??? Loss of Space. Need to find
  new space every few years (Quito, Toronto,
  Edmonton)

• Long-term liability Need to monitor potential
  impact for a long- time (until waste stability is
  achieved)

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Landfill Gas a liability or a resource?

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Zambiza Landfill (Quito, Ecuador)
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Zambiza Landfill (Quito, Ecuador)
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A Case for Landfill Gas Extraction and Energy
Recovery

• 50 of landfill gas is methane

• 1 tonne of MSW produces 150-200 m3 of methane
• based on stoichiometry,
• under ideal conditions
• over a period of time (time period depends on
  rate kinetics)

Landfill Gas is typically extracted using active
systems (passive systems are used primarily to
reduce gas pressure build up more wells are
needed)
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Landfill Gas Extraction and Energy Recovery

• Extraction is feasible in any landfill
• Typical vertical well network

• Networks are designed using
• gas production estimates,
• field testing and
• theoretical calculations (based on radius of
  influence)

• Or on as needed basis using surface
  emission data

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Active Gas Recovery in Loma Los Colorados
Landfill, Chile, Using a Designed Well Network
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Loma Los Colorados Gas Well Network
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A problem with gas extraction in Loma Los
Colorados

• The designed network was not efficient..

• Less than 25 of the gas produced was captured
• based on a methane balance done in 2001.
• Why??
• The landfill was not designed for methane
  recovery
• Use of low permeable daily/intermediate
• cover material

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Experience in Montreal, Canada

• Most wells are installed on as needed basis

• Use a large number of wells, but gas
  collection
• Efficiency is very high.

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Gas wells.everywhere
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Well-head in Montreal landfill
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Energy Recovery Is it Feasible??

• Gas can be extracted from most landfills,
• but sometimes energy recovery may not be
  feasible !!!
• Reason Not economical

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In Chile gas is burned in a Central
Incinerator
CH4 burned 85 tonnes/year (or 330 m3/d)
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In Ecuador wells are fitted with flares.
produce toxic compounds
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Gas Management Other Solutions

• Find a nearby community or industry to use the
  recovered gas directly
• Develop as a CDM project (for Carbon Credits
  under Kyoto Protocol)

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Another Solution..
Design for Gas Extraction and Energy Recovery!!

• Landfill Bioreactor concept
• Leachate is recirculated as a means of enhancing
  rates of reactions within the cell
• Controlled recirculation of leachate will
• increase moisture, nutrients and
• provide a microbial seed for rapid
  biodegradation
• High rates of gas production will enhance
  economics of energy recovery

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Bioreactor Landfill
Anaerobic Reactor
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A Better Solution Sustainable Landfill
Go two steps further

• After the Anaerobic Bioreactor stage, include
• Aerobic Bioreactor stage (in-ground composter)
• Biocell mining stage

• Stabilize the waste quickly (Anaerobic and
  Aerobic)

• Mine the cell, and extract recyclables
  compost

• Reuse the space.

• Holistic approach (not piece-meal)

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Sustainable Landfill
Aerobic Reactor
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Sustainable Landfills Are we there yet???

• Not really..

• Although there are some operating Anaerobic
  Reactors (and a few Aerobic Reactors) around the
  World, no one has tried the sequential operation
  (Sustainable Landfill) yet..

• A number of operational problems needs to be
  resolved before Sustainable Landfills can be
  universally applied.

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Problems to Resolve
Moisture Distribution Within the Cell
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Leachate Pools Created by over-zealous
Leachate Recirculation
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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

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Landfill Bio-Caps or MOLs

• A new concept
• Use a naturally occurring bacteria to convert
  methane

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Biofiltration of CH4
Microbially mediated oxidation of CH4 is carried
out by methanotrophic bacteria
(Methylomonas methanica)
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CH4 Oxidation in Landfill Caps
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Sustainable Landfill Operation (Calgary Biocell
Concept)
Anaerobic Year 2
Anaerobic Year 1
Anaerobic Year 3
Mining/ Space Recovery Year 6
Aerobic Year 5
Aerobic Year 4
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Calgary Sustainable Biocell or LBC

• Pilot Project (1 hectare 50,000 tonnes of waste)

• Partners/Participants City of Calgary,
  University of Calgary and Consultants

• Mitigation Measures

• Biocap, or Methane Oxidation Layer (MOL), to
  control methane gas emissions during
  construction and operation

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LBC Design ..
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LBC Construction
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LBC Filling
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Monitoring/Sensors for Research and LBC Operation

• Temperature
• Settlement (plates at 4 levels)
• Loads (pressure transducers/pressure plates)
• Leachate head (piezometers)
• Moisture in waste (TDR)
• Pore pressure measurements
• Leachate characteristics

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Monitoring/Sensors Settlement
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Monitoring/Sensors Layout
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LBC Current Status

• First lift is being filled with domestic waste
• In early July, the first intermediate biocover
  will be placed
• Sensors are being installed
• Expect to collect settlement data and biocover
  performance data, starting mid-July

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Conclusions

• Waste disposal has progressed from open dumps
  (in the past) to dry-tomb sanitary landfills
  (present).
• Bioreactor Landfills/Sustainable Landfills
  could be the future.
• Sustainable landfilling follows a holistic
  approach. Consider waste as a resource extract
  biogas energy and compost and recyclables, and
  space. It is consistent with the current
  environmental (sustainable development) thinking
  
• Technical challenges need to be overcome,
  before Sustainable Landfill concept could be
  universally applied.

Thank You!