How can we deal with the waste we produce in a more sustainable way?
Waste management and the waste hierarchy (reduce, reuse, recycle); methods of disposal and their impacts (landfill, incineration); recycling and composting; and the problem of pollution from waste.
An SQA National 5 Environmental Science answer on waste management and recycling, covering the waste hierarchy of reduce, reuse and recycle, methods of disposal such as landfill and incineration and their impacts, composting, and the environmental problem of pollution from waste such as plastics.
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What this dot point is asking
The SQA wants you to describe the waste hierarchy (reduce, reuse, recycle), explain methods of waste disposal such as landfill and incineration and their environmental impacts, describe recycling and composting, and explain the problem of pollution from waste, including plastics.
The waste hierarchy
The most important idea is the waste hierarchy, which ranks ways of managing waste from most to least sustainable.
Reduce comes first because preventing waste avoids using any raw materials, energy or water to make something that is never produced, and there is nothing to collect or process. Each step down the hierarchy uses more resources, so disposal in landfill is the least sustainable option.
Methods of disposal and their impacts
Landfill buries waste in the ground.
- Disadvantages. It takes up land; rotting waste releases methane (a greenhouse gas); liquid (leachate) can pollute soil and groundwater; and much waste, especially plastic, stays in the ground for a very long time.
Incineration burns waste.
- Advantage. It reduces the volume of waste and can recover energy as heat to generate electricity.
- Disadvantages. It releases carbon dioxide and can release other air pollutants, and it destroys materials that could have been reused or recycled.
Both landfill and incineration sit low in the hierarchy, which is why reducing, reusing and recycling are preferred.
Recycling and composting
- Recycling processes used materials (such as glass, metal, paper and some plastics) into new products. It saves raw materials and usually less energy than making products from scratch, and it reduces what goes to landfill. It still uses energy to collect, transport and reprocess, so it ranks below reduce and reuse.
- Composting lets decomposers break down food and garden waste into a useful soil improver. It diverts biodegradable waste from landfill (where it would release methane) and returns nutrients to the soil, linking waste management to the nutrient cycle.
Pollution from waste
Waste that is not managed becomes pollution. A major problem is plastic: it is durable and does not biodegrade, so it builds up in the environment and especially in the oceans, where it harms wildlife (animals swallow it or become entangled) and breaks into microplastics that spread through food chains. Reducing plastic use, reusing and recycling, and disposing of waste responsibly all help cut this pollution.
Examples in context
Example 1. Composting kitchen waste. Putting vegetable peelings and garden cuttings in a compost bin lets decomposers turn them into compost over months. The compost enriches the soil, and the waste avoids landfill, where it would have released methane, showing how composting links waste management to nutrient cycling.
Example 2. Plastic in the ocean. Plastic litter washed into the sea does not biodegrade; it accumulates, is eaten by seabirds and marine animals, and breaks into microplastics that enter food chains. This illustrates why reducing and properly disposing of plastic waste is a key sustainability issue.
Try this
Q1. State the order of the top three steps of the waste hierarchy, from best to worst. [1 mark]
- Cue. Reduce, then reuse, then recycle.
Q2. Give one environmental disadvantage of disposing of waste in landfill. [2 marks]
- Cue. It releases methane (a greenhouse gas) and leachate that can pollute soil and groundwater, takes up land, and plastics persist for a very long time.
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA N5 style4 marksDescribe the waste hierarchy and explain why reducing waste is preferable to recycling it.Show worked answer →
A 4-mark answer needs the hierarchy plus the reason reduce beats recycle, so plan two description marks and two explanation marks.
The waste hierarchy ranks ways of dealing with waste from best to worst: reduce (make less waste in the first place), reuse (use items again), recycle (process materials into new products), then recover energy, and finally dispose (landfill) as the last resort.
Reducing waste is preferable to recycling because it prevents the waste and the use of resources at the start: no raw materials, energy or water are used to make something that is never produced, and there is nothing to collect, transport and process. Recycling still uses energy and resources to collect and reprocess materials, so it is better than disposal but not as good as not creating the waste at all.
Markers reward setting out the hierarchy in order and explaining that reducing avoids resource and energy use that recycling still requires.
SQA N5 style3 marksCompare landfill and incineration as methods of waste disposal, giving one disadvantage of each.Show worked answer →
This is a compare question, so cover both methods and give a clear disadvantage of each.
Landfill buries waste in the ground. Disadvantage: it takes up land, can release methane (a greenhouse gas) and leachate that can pollute soil and groundwater, and the waste, especially plastic, can remain for a very long time.
Incineration burns waste. Disadvantage: it releases carbon dioxide and can release other air pollutants, and it destroys materials that could have been reused or recycled, though it can recover some energy as heat.
A further mark could note that both are low in the waste hierarchy and that reducing, reusing and recycling are preferable.
Markers reward a valid disadvantage of each method and a clear comparison.
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