The diagram shows a proposed waste system for a district of Stockholm. Food waste is collected separately and sent to an anaerobic digestion plant. The plan...
Question 1 Report
The diagram shows a proposed waste system for a district of Stockholm. Food waste is collected separately and sent to an anaerobic digestion plant. The plant produces biogas for buses and digestate for farms outside the city. Other materials are sorted for recycling, while only a small amount is sent to landfill. Table 1 gives the annual mass of waste collected in 2020 from the district. The council wants to reduce both landfill use and fossil-fuel consumption.
| Waste stream | Mass collected in 2020, tonnes |
|---|---|
| Food waste | 12 400 |
| Paper, glass and metal | 18 600 |
| Residual waste to landfill | 4 100 |
(a) Identify the renewable energy source produced by the digestion plant. [1]
(b) Identify two waste streams in Table 1 that could avoid landfill. [2]
(c) Identify three environmental benefits of the system shown in Fig. 1. [3]
Answer Details
(a) The digestion plant produces biogas. [1]
(b) Food waste can avoid landfill, and paper, glass and metal can avoid landfill through recycling. [2]
(c) The system reduces the amount of waste buried in landfill. It captures methane from food waste for use as biogas, and this biogas can replace some fossil fuel used by buses. Recycling reduces demand for raw materials, while digestate can reduce manufactured fertiliser use. Any three environmental benefits gain credit. [3]
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