Why is waste placed in cells and covered daily?

Cells keep the working area small and let each section be sealed when full. Daily cover of soil or other material reduces litter, odour, vermin and rainwater entry.

How is landfill gas collected and used?

Perforated wells drilled into the waste draw gas out under suction. The gas fuels engines that generate electricity, or is flared if it cannot be used.

Why is flaring landfill gas better than releasing it?

A flare burns methane to carbon dioxide and water. Carbon dioxide is a far weaker greenhouse gas than methane, so the overall climate impact falls.

CCEA A-Level Environmental Technology 3930

Fossil Fuels

Topic overview Coal, oil and gas in modern society Reserves, lifespan and accessibility Fossil fuel combustion and the IPCC evidence Carbon trading schemes Fossil fuel demand, emerging economies and fuel security Environmental impacts of fossil fuel use

Global Action on Energy Conservation and Climate Change

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Macrogeneration

Topic overview Conservation of energy and the simple generator Thermal power stations and steam turbines Direct and indirect renewable electricity Electricity transmission through the National Grid Smart grids and interconnectors Combined heat and power

Microgeneration

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Energy From Wind

Topic overview Horizontal and vertical axis wind turbines Kinetic energy, wind power and the Betz limit Power curves, rated output and energy losses Swept area, blade length and turbine mass Air density, hub height and turbine siting Power control, yawing and survival speed Choosing a location for a commercial wind farm

Energy From the Sun

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Energy From Biomass

Topic overview Defining biomass and its main categories Energy crops grown for biomass Advantages and disadvantages of biomass fuel Combustion, woodchip and fuel quality Gasification and syngas Biogas and commercial anaerobic digesters

Energy Storage

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Plastics for the Future

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Renewable Energy Investigations

Topic overview Desktop research on renewable energy technologies Choosing an investigation and its variables Apparatus and risk assessment for energy practicals Accuracy and reliability of energy measurements Presenting and analysing energy data Evaluating a method and site-based recommendations

Sustainable Development

Topic overview Population growth and demand for resources The I = PAT equation and the role of technology Ecological footprints, carbon footprints and One Planet Living

Waste Management

Topic overview Landfill dependence and the landfill tax Waste types, priority waste streams and EU directives The waste management hierarchy Recycling at a Materials Recovery Facility Landfill decomposition, methane and leachate Engineered landfill: dry tomb and bioreactor designs

Waste to Energy Technologies

Topic overview Embodied energy Incineration with energy recovery Digester design: solids content, residence time and staging Stages of anaerobic digestion and biogas CHP Composting and catering waste

Land Contamination and Remediation

Topic overview Contaminated land, risk and traditional remediation Bioremediation principles and bioreactor systems Micro-organisms that degrade named pollutants Bioremediation benefits and genetically engineered microbes Phytoremediation of metals and other elements Phytoextraction with Indian mustard and alpine pennycress Biohydrometallurgy and phytomining of ores

Hydrogen Fuel Cells

Topic overview Hydrogen as a fuel: properties and storage Hydrogen production: steam reforming, electrolysis and photocatalysis How a fuel cell works and the PEM cell Alkaline, phosphoric acid, molten carbonate and solid oxide fuel cells Fuel cell applications and the challenges of hydrogen

Transport System Challenges

Topic overview Four key challenges for future transport New vehicle technologies and their infrastructure Bioethanol production and the heat energy of ethanol Biodiesel and the biofuel debate Strategies to reduce transport demand

Energy Performance of Buildings

Topic overview Energy conservation and residents' behaviour Insulation, air tightness and glazing U-values and the heat flow equation The zero carbon homes hierarchy BREEAM, the Code and upgrading existing homes

Emerging Technologies

Topic overview Tidal stream and tidal barrage power Wave energy converters Environmental impacts of wave and tidal energy Smart materials and smart systems Carbon capture and storage Geo-engineering, direct air capture and bio-photovoltaics

Sustainable Urban and Rural Communities

Topic overview Energy and buildings in sustainable urban developments Transport, waste and brownfield sites Water, drainage and urban green space Energy, water and waste for isolated rural dwellings Local food and communication technology in rural areas

The Code for Sustainable Homes

Topic overview Purpose, levels and assessment of the Code Energy, carbon dioxide and water categories Materials, surface water run-off and waste categories Pollution, health and wellbeing, management and ecology categories Measuring the performance of an existing building Performance profiles, improvements and evaluation

Waste Management

Engineered landfill: dry tomb and bioreactor designs

3 things to know
A2 1

Overview

Liners, leachate collection and treatment, cells and daily cover, gas collection, flaring and energy use, borehole monitoring, and the dry tomb and bioreactor designs compared.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

How does a modern engineered landfill differ from an old dump?

Key term

Describe the lining system of an engineered landfill.

Key term

How is leachate collected and treated in an engineered landfill?

Questions from this subtopic

Each one with the model answer underneath.

1
How does a modern engineered landfill differ from an old dump?
Model answer
An engineered landfill contains its waste within a lined, capped cell and collects its gas and leachate. An old dump let leachate and gas escape freely into the surroundings.
2
Describe the lining system of an engineered landfill.
Model answer
A composite liner combines a compacted clay layer with a high-density polyethylene (HDPE) membrane. The liner stops leachate escaping into the ground and groundwater.
3
How is leachate collected and treated in an engineered landfill?
Model answer
A gravel drainage layer and perforated pipes above the liner carry leachate to a sump. The leachate is pumped out and treated on site or at a sewage works.
4
Why is waste placed in cells and covered daily?
Model answer
Cells keep the working area small and let each section be sealed when full. Daily cover of soil or other material reduces litter, odour, vermin and rainwater entry.
5
How is landfill gas collected and used?
Model answer
Perforated wells drilled into the waste draw gas out under suction. The gas fuels engines that generate electricity, or is flared if it cannot be used.
6
Why is flaring landfill gas better than releasing it?
Model answer
A flare burns methane to carbon dioxide and water. Carbon dioxide is a far weaker greenhouse gas than methane, so the overall climate impact falls.

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Fossil Fuels

Global Action on Energy Conservation and Climate Change

Macrogeneration

Microgeneration

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