The diagram shows part of a sewage-treatment system used before treated water enters a river beside a town. Untreated sewage can contain bacteria from human...
Question 1 Report
The diagram shows part of a sewage-treatment system used before treated water enters a river beside a town. Untreated sewage can contain bacteria from human faeces.
(a) Name the process labelled X that separates solid material from sewage by allowing it to sink. [1]
(b) Describe why releasing untreated sewage into the river could increase the spread of diseases. [2]
(c) Explain why removing bacteria from sewage protects people who use the river water downstream. [2]
(d) Complete the sentence: A disease-causing microorganism is called a __________. [1]
Answer Details
(a) Process X is sedimentation, also called settling [1]. Solid material sinks to the bottom of the tank.
(b) Untreated sewage may contain pathogens, including bacteria from faeces [1]. These can contaminate river water and enter people through drinking, food prepared with the water, or contact with the water [1].
(c) Removing bacteria means fewer pathogens remain in the water [1]. People using river water downstream are therefore less likely to become infected and develop disease [1].
(d) A disease-causing microorganism is a pathogen [1].
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