The waste hierarchy
Big idea: The waste hierarchy prioritises prevention over treatment. The best waste is waste that is never created.
The hierarchy (most to least preferred)
- 1. Prevention/Reduce: Avoid creating waste in the first place — best option
- 2. Reuse: Use items again for same or different purpose
- 3. Recycle: Process materials into new products
- 4. Recovery: Extract energy from waste (incineration with energy recovery)
- 5. Disposal: Landfill or incineration without energy recovery — last resort
The hierarchy emphasises that preventing waste is always better than managing it. Even recycling uses energy and resources — reduction is superior.
Applying the hierarchy
- Reduce: Buy less, choose products with less packaging, avoid single-use items
- Reuse: Repair items, donate, buy second-hand, refillable containers
- Recycle: Separate recyclables, support recycled-content products
- The 3Rs (or 5Rs): Reduce, Reuse, Recycle (+ Refuse, Rot/compost)
Exam tip: IB favours evaluation of strategies, not listing. Explain WHY the hierarchy is ordered this way (environmental impact, resource use, energy) and evaluate each levels effectiveness.
Circular economy and policy tools
Big idea: The circular economy aims to eliminate waste entirely by designing products for longevity and material recovery.
Linear vs circular economy
Linear economy (current)
- Take → Make → Dispose
- Resources extracted, used once, discarded
- Generates waste at every stage
- Depletes natural resources
Circular economy (goal)
- Reduce → Reuse → Recycle → Regenerate
- Materials kept in use as long as possible
- Waste = food for another process
- Mimics natural cycles
Policy tools for waste management
- Extended producer responsibility (EPR): Manufacturers responsible for end-of-life management
- Landfill taxes: Make disposal more expensive, incentivise alternatives
- Plastic bag bans/taxes: Reduce single-use plastic consumption
- Deposit-return schemes: Incentivise return of bottles and cans
- Pay-as-you-throw: Charge households by waste volume, incentivise reduction
- Education and awareness: Change consumer behaviour
Design for sustainability
- Design for durability: Products that last longer
- Design for repair: Easy to fix, spare parts available
- Design for disassembly: Easy to separate materials for recycling
- Design for recyclability: Use materials that can be recycled
- Eliminate toxic materials: Avoid substances that contaminate recycling streams
Exam tip: The circular economy is a systems-thinking concept. Explain how it connects to sustainability, resource management, and different EVSs (especially ecocentric views).
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IB-style question — Waste management strategies [6]
Greenhaven has launched a waste programme: kerbside recycling collections, a 'repair café' grant scheme, and a target to send zero waste to landfill by 2032. Evaluate whether this programme is likely to achieve long-term sustainability. [6]
How to answer it, step by step
- Strengths
• Kerbside collection lifts recycling rates
• Repair scheme cuts waste at source (reduce/reuse) - Weaknesses + judgement
• 2032 target ignores current landfill build-up; recycling needs end-markets
• End with a reasoned overall verdict on sustainability
Final answer
Evaluate (6) = balance strengths against weaknesses then give a clear conclusion; the final judgement mark is lost if you only list points without deciding.