Reduce, reuse and recycle
Three principles guide the sustainable use of materials. Listed in priority order:
- Reduce — use less in the first place.
- Reuse — use the same item again.
- Recycle — convert waste back into raw material.
Reduce
The most effective: avoid using a resource at all.
- Buy fewer things.
- Use thinner packaging.
- Generate electricity efficiently.
Reducing the demand for raw materials is the most direct way to limit environmental impact.
Reuse
- Glass bottles — washed and refilled.
- Refurbished electronics — phones, laptops resold.
- Returnable packaging — supermarket crates.
Reuse keeps materials in their original form so no energy is needed for re-processing.
Recycle
Material is broken down and remade into new products.
Metals (e.g. steel, aluminium, copper)
- Sort into types (often by magnetic separation, density).
- Melt in a furnace.
- Cast into ingots; rolled or shaped into new products.
- Recycling Al uses ~5% of the energy of new extraction.
Glass
- Sort by colour.
- Crush ("cullet"), melt, remould.
Plastics
- Sort by polymer type (challenging — many similar plastics).
- Wash, shred, melt, pellet, remould.
- Some plastics (especially thermosetting) cannot be recycled.
Benefits of recycling
- Less raw material extraction — saves finite resources.
- Less energy than mining + processing virgin material.
- Less waste in landfill or oceans.
- Less CO₂ emissions per kg of product.
- Creates employment in recycling industry.
Challenges
- Sorting is labour-intensive (especially mixed plastics).
- Some materials degrade with each recycle cycle (paper fibres shorten).
- Contamination by food/labels makes some materials hard to recycle.
- Transport to recycling centres has its own emissions.
- Some thermosetting plastics cannot be melted down.
✦Worked example
Compare extraction of new aluminium with recycling.
| Aspect | New | Recycled |
|---|---|---|
| Energy | High (electrolysis at 950 °C) | ~5% of new |
| Raw materials | Bauxite (mined) | Existing Al items |
| Cost | High | Lower |
| CO₂ | High | Much lower |
So recycling is hugely beneficial for Al.
⚠Common mistakes
- Saying recycling is always best — reduce > reuse > recycle.
- Confusing thermosoftening with thermosetting for plastics — only the former can be recycled.
- Ignoring transport emissions in recycling.
- Saying paper can be recycled forever — fibres shorten each time.
Links
Builds on C10.5 (LCA), C2.4 (alloys), C7.7 (polymers). Connects to C10.1 (sustainability).
AI-generated · claude-opus-4-7 · v3-deep-chemistry