Waste water treatment produces sewage sludge and liquid effluent, which must be processed before disposal or reuse.
State the name of the process that separates waste water into liquid effluent and solid sewage sludge.
Table 1 shows information about how processed solid sewage sludge was disposed of in a country in 2005 and 2020.
Table 1
| Year | Used as fertiliser (millions of kg) | Sent to landfill (millions of kg) | Incinerated (millions of kg) | Other methods (millions of kg) | Total (millions of kg) |
|---|---|---|---|---|---|
| 2005 | 520 | 250 | 110 | 320 | 1200 |
| 2020 | 1280 | 15 | 310 | 45 | 1650 |
Calculate the percentage of processed solid sewage sludge that was sent to landfill in 2005.
Give your answer to 3 significant figures.
Describe the biological treatments used to process:
Suggest one reason why the total mass of sewage sludge increased between 2005 and 2020, and two reasons why the proportion sent to landfill decreased dramatically over the same period.
11 exam-style questions on AQA GCSE Chemistry 10.1 Using the Earth's resources and obtaining potable water, covering 10.1.1 Using the Earth's resources and sustainable development, 10.1.2 Potable water, 10.1.3 Waste water treatment, and 10.1.4 Alternative methods of extracting metals (HT only). Each one has a worked solution and a mark scheme showing where the marks go.