Comparing waste-management approaches means judging two or more methods against the same criteria, then reaching a conclusion the data supports. A list of facts about each method is not a comparison.
This lesson is part of environmental sustainability in SPM Science. If the data step is where you stall, read interpreting environmental indicator data first.
What makes a fair comparison?
A fair comparison uses the same criteria for every method and the same amount of waste. Pick the criteria before you write a single sentence about the methods.
| Criterion | Landfill | Incineration | Recycling | Composting |
|---|---|---|---|---|
| Land needed | Large, and it fills up | Small | Small, plus a sorting area | Moderate |
| Volume of waste left | No reduction | Large reduction, ash remains | Reduces what is buried | Reduces food and garden waste |
| Main pollution risk | Leachate and methane | Gases and ash if not controlled | Low, but some processes use energy | Smell and pests if managed badly |
| What is recovered | Nothing | Heat that can make electricity | Materials | Soil improver |
Every cell is a reason you can use. The cells that say “if not controlled” or “if managed badly” remind you that a method’s outcome depends on how it is run.
Worked example: a fictional town
Taman Sinar is an invented town that produces 40 tonnes of household waste a day. The council compares two plans with the same 40 tonnes.
- Plan A: everything goes to a landfill.
- Plan B: sorted recycling and composting divert 35% of the waste, and the rest goes to landfill.
Step 1: calculate the diverted waste. 35% of 40 tonnes is 0.35 × 40 = 14 tonnes a day.
Step 2: calculate what reaches landfill under Plan B. 40 − 14 = 26 tonnes a day.
Step 3: state the comparison. Plan B sends 14 tonnes a day less to landfill than Plan A, so the landfill lasts longer and produces less leachate.
Step 4: state the assumptions. The town produces the same 40 tonnes under both plans, residents sort the waste correctly, and the 35% figure is achieved. If residents sort badly, the saving shrinks.
The assumptions sentence is what separates a full-mark answer from a half-mark one. It shows you know the conclusion depends on conditions.
The mistake that costs marks
The common slip is to write “Plan B is better because recycling is good for the environment”. It names no criterion, uses no number and gives no reason.
A stronger sentence is “Plan B is better on landfill space, because 14 tonnes a day less waste is buried, so the landfill takes longer to fill”. It names the criterion, uses the data and says why that matters.
Check yourself
A second fictional town produces 60 tonnes of waste a day. Its plan diverts 25% through recycling and composting. Calculate the waste sent to landfill each day and state one assumption.
Answer
Diverted waste: 0.25 × 60 = 15 tonnes. Waste to landfill: 60 − 15 = 45 tonnes a day.
Assumption: the town still produces 60 tonnes a day after the plan starts, and the 25% diversion is actually achieved by residents sorting correctly.
What to study next
Move on to evaluating a sustainability proposal, where you judge a single plan instead of comparing two. Then test yourself with the environmental sustainability practice set.
To keep a record of comparison answers that lost marks, use the mistake log and paper-error review. If you want a teacher to work through these answers with you, see online one-to-one Science tuition.