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examBoard: Cambridge
examType: IGCSE
lessonTitle: Landfill Management
Landfills are engineered sites where waste is disposed of by burial. Despite efforts to reduce waste through recycling and reuse, landfills remain an important part of waste management systems worldwide. Proper landfill management is crucial to minimise environmental impacts and protect human health.
Key Definitions:
Sanitary landfills are engineered with protective bottom liners, leachate collection systems and gas management. These are the modern standard in developed countries.
Bioreactor landfills actively promote microbial processes to accelerate waste decomposition by adding liquids and air.
Landfill sits at the bottom of the waste hierarchy:
Modern landfills are carefully designed to prevent pollution and minimise environmental impacts. Key design elements include:
Multiple layers of clay and synthetic materials (like HDPE) create a barrier to prevent leachate from contaminating groundwater. A typical liner includes:
Systems of pipes and drainage layers collect leachate that forms as water passes through waste. This is then:
Networks of pipes extract methane and other gases produced by decomposing waste. These gases can be:
Landfills can cause several environmental problems if not properly managed. Understanding these impacts helps us develop effective mitigation strategies.
Impact: Leachate can contaminate groundwater and surface water with heavy metals, organic compounds and other pollutants.
Mitigation: Liner systems, leachate collection and treatment, regular groundwater monitoring and buffer zones around landfills.
Impact: Landfill gases contribute to climate change (methane is 25 times more potent than CO₂), create odours and can cause health issues.
Mitigation: Gas collection systems, flaring or energy recovery, daily cover of waste and odour management plans.
Impact: Habitat destruction, disruption to wildlife and potential toxic effects on plants and animals.
Mitigation: Ecological surveys before site selection, buffer zones, habitat creation and progressive restoration.
Impact: Noise, traffic, visual intrusion and potential reduction in property values.
Mitigation: Screening with trees, restricted operating hours, designated transport routes and community engagement.
Pitsea Landfill in Essex operated for over 100 years before closing in 2016. It demonstrates successful landfill management and restoration:
This case demonstrates how proper management and restoration can transform a waste disposal site into a valuable ecological resource.
Leachate management is one of the most critical aspects of landfill operation. If not properly controlled, leachate can cause serious water pollution.
Leachate typically contains:
The exact composition varies depending on waste type, age and climate.
Common leachate treatment approaches include:
Landfill gas (LFG) is produced when organic waste decomposes in anaerobic conditions. It typically consists of about 50% methane and 50% carbon dioxide, with trace amounts of other gases.
Landfill gas can be a valuable energy resource:
The UK has over 450 landfill gas energy projects, generating enough electricity to power over 1 million homes.
Typical gas collection systems include:
Once a landfill reaches capacity, it must be properly closed and restored. This process involves several steps to ensure long-term environmental protection and create beneficial after-uses.
A multi-layer cap typically includes:
Common after-uses include:
Long-term monitoring includes:
While landfills will continue to play a role in waste management, their importance is diminishing as we move towards more sustainable approaches.
The circular economy approach aims to eliminate waste by keeping materials in use through:
This approach could significantly reduce the need for landfills in the future.
New technologies are changing waste management:
The UK has made significant progress in reducing landfill use:
This demonstrates how policy tools can effectively change waste management practices and reduce environmental impacts.
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