Landfill and incineration
Big idea: Landfill and incineration are the most common disposal methods globally. Both have significant environmental impacts but can be managed to reduce harm.
Landfill
- How it works: Waste buried in lined pits; covered daily to reduce odour and pests
- Modern landfills: Clay/plastic liners, leachate collection, methane capture
- Advantages: Simple, cheap, can handle mixed waste, methane can generate electricity
- Disadvantages: Land use, leachate contamination risk, methane emissions (GHG), slow decomposition, NIMBY opposition
Leachate is a major pollution risk from landfills. Modern landfills have liners and collection systems, but leaks can occur.
Incineration
- How it works: Waste burned at high temperatures (850-1100°C)
- Waste-to-energy: Heat can generate electricity; 1 tonne waste ≈ 500 kWh
- Advantages: Reduces volume by 90%, destroys pathogens, recovers energy, reduces landfill need
- Disadvantages: Air pollution (dioxins, particulates, heavy metals), ash disposal, high cost, public opposition, reduces recycling incentive
Exam tip: Modern incinerators have pollution controls (scrubbers, filters) that reduce but dont eliminate emissions. Be nuanced in your evaluation.
Recycling and composting
Big idea: Recycling and composting recover value from waste, reducing resource extraction and disposal impacts. However, they face economic and technical limitations.
Recycling
- How it works: Materials collected, sorted, processed into new products
- Commonly recycled: Paper, cardboard, glass, metals (aluminium, steel), some plastics
- Advantages: Reduces resource extraction, saves energy (95% for aluminium), reduces landfill, creates jobs
- Disadvantages: Contamination reduces quality, not all materials recyclable, market volatility, transport emissions, downcycling common
Downcycling = recycling into lower-quality products. Most plastic is downcycled (bottle → fleece → landfill), not truly recycled in a closed loop.
Composting
- How it works: Organic waste decomposed by microorganisms into nutrient-rich compost
- Suitable materials: Food scraps, yard waste, paper, cardboard (not meat/dairy in home composting)
- Advantages: Diverts organic waste from landfill, reduces methane, produces valuable soil amendment, closes nutrient loop
- Disadvantages: Requires space and management, odour if poorly managed, not suitable for all organic waste, slow process
Anaerobic digestion
- How it works: Organic waste broken down without oxygen, producing biogas (methane) and digestate
- Advantages: Captures energy (biogas), handles food waste and manure, reduces GHG emissions
- Disadvantages: High capital cost, requires consistent feedstock, digestate disposal needed
Exam tip: Organic waste in landfills produces methane (potent GHG). Composting and anaerobic digestion avoid this — a key environmental benefit.