Knowledge Organiser: Recycling
Key Terms
- Recycling: Converting waste into new materials — reduces raw material demand and energy use
- Landfill: Burying waste — produces methane and wastes resources
- Incineration: Burning waste — reduces volume, can generate electricity, but releases CO₂
- Waste hierarchy: Reduce → Reuse → Recycle → Energy recovery → Disposal
Must-Know Facts
- Reduce → Reuse → Recycle (in order of priority — Reduce is most important)
- Aluminium recycling: 95% energy saving; steel: 60%; paper: 40%; glass: 30%
- Recycling uses less energy but is NOT energy-free
- Not all plastics are recyclable — contamination is a major challenge
- Landfill produces methane — a potent greenhouse gas
- Contamination of recycling streams is a major practical challenge
Key Equations
- No calculation equations — evaluative/comparative topic
- Aluminium recycling saves 95% of the energy needed to extract from bauxite ore
- Waste hierarchy (most to least preferred): Reduce → Reuse → Recycle → Energy recovery → Dispose
Common Mistakes
- Saying recycling uses no energy: Recycling uses LESS energy than extracting virgin materials — but it is not energy-free; collection, transport, and processing all require energy
- Saying reusing is better than reducing: In the waste hierarchy, REDUCING consumption is the highest priority — reuse comes second, recycling third
- Forgetting landfill produces greenhouse gases: Organic waste in landfill decomposes anaerobically and produces METHANE — a greenhouse gas ~25× more potent than CO₂
- Saying all materials can be recycled equally easily: Aluminium is easily and economically recycled (95% energy saving); mixed plastics and contaminated materials are much harder and less economically viable to recycle
Memory Aid
- Aluminium — 95% energy saving (best recycler)
- Steel — 60% energy saving
- Paper — 40% energy saving
- Glass — 30% energy saving (least, but still valuable)