Waste water treatment — AQA GCSE Chemistry
Test yourself on Waste water treatment with AQA GCSE practice questions.
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Waste water treatment explained
Urban living and industry generate waste water from homes, businesses and factories.
Read the full explanation
Domestic waste water includes water from sinks, baths, toilets and washing machines, while industrial processes may add chemicals, oils or other pollutants. If this water were released untreated, it could harm aquatic life, spread disease and pollute rivers, lakes and groundwater. Treatment removes solids, organic matter and harmful microorganisms before the water is returned to the environment. A typical treatment sequence includes screening to remove large objects, sedimentation to settle suspended solids, and biological or chemical treatment to break down organic matter and reduce harmful microbes. The treated water must meet environmental standards before release.
Your focus
- Identify sources of waste water from urban lifestyles and industrial processes.
- Explain why waste water must be treated before release into the environment.
- Describe the main stages of waste water treatment and what each stage removes.
Waste water treatment exam tips
Marking Points
- State that urban lifestyles produce domestic waste water from homes and that industrial processes produce waste water containing a range of pollutants.
- Explain that untreated waste water can harm the environment by causing disease, deoxygenating water or introducing toxic substances.
- Describe the purpose of treatment as removing solids, organic matter and harmful microbes before release.
- Outline a treatment sequence such as screening, sedimentation and biological treatment, linking each stage to what it removes.
- Recognise that treated water must meet environmental standards before being released into rivers or the sea.
Examiner Tips
- 💡Use the phrase 'before being released into the environment' to show you understand the purpose of treatment.
- 💡When describing treatment, name the stage and state what it removes, for example 'screening removes large solid objects'.
- 💡Link environmental harm to specific effects, such as harmful microbes causing disease or organic matter reducing oxygen levels in water.
Common Mistakes
- Thinking all waste water is sewage; the correction is to recognise that industrial waste water may contain different pollutants such as chemicals and oils.
- Believing treatment simply dilutes waste; the correction is that treatment removes or breaks down pollutants rather than just diluting them.
- Confusing waste water treatment with potable water treatment; the correction is that waste water treatment aims to make water safe for release, while potable water treatment aims to make water safe to drink.