Solid waste management – landfill, incineration, recycling and composting
GeographySoils, Biosphere & EnvironmentAges 17–18
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A city produces waste every day: set the rates of prevention, recycling, composting and burning for energy, then run 30 years to watch the landfill fill up and see the methane and leachate it makes and the electricity recovered. A Decay test buries the same items in a compost heap and in a landfill to compare biodegradable and non-biodegradable waste, and a Sorting game routes household waste to the best bin.
Lesson: Solid waste: landfill, incineration, recycling, composting and the waste hierarchy
What it shows
Every city must deal with the waste its people throw away. The waste hierarchy puts prevention and reuse first, then recycling and composting, then burning with energy recovery, and landfill last. In a landfill, food and paper decay without air and make methane, a strong greenhouse gas, while rain seeping through forms leachate that can pollute groundwater unless the site has a liner and collection pipes. Incineration shrinks waste to ash and makes electricity but releases fossil CO₂ from plastics. Biodegradable materials are broken down by microbes; plastics, glass and metals are not. All figures are simplified estimates.
How to use
On City system, set the city, the Waste plan sliders and the landfill, press Run 30 years and switch the graph between Landfill, Greenhouse gases, Leachate and Electricity; each finished run is added to the table. On Decay test, press Run and compare the two panels, then mark each item. On Sorting game, drag each item to a bin or press a bin button and read why.
Parameters you can change
- Screen City system, Decay test, Sorting game
- Population 50–3000 thousand
- Waste per person 0.3–2.5 kg/day
- Population growth 0–4 %/yr
- Waste mix (income level) Low income, Middle income, High income
- Prevention and reuse 0–30 %
- Recycling (paper, plastic, glass, metal) 0–90 %
- Composting of food and garden waste 0–90 %
- Rest burned for energy 0–100 %
- Type Sanitary landfill, Open dump
- Landfill gas captured 0–90 %
- Annual rainfall 200–3000 mm
- Landfill capacity 1–20 million m³
- Compost heap Well kept (moist, turned), Neglected (dry)
Questions to explore
- Which part of the waste plan makes the landfill last longest, and why?
- Why does a banana peel rot in weeks in a compost heap but survive years in a landfill?
- Why should batteries and paint never go into a landfill or an incinerator?
