All topics › AQA GCSE Chemistry › Waste water treatment10.1.3 Waste water treatmentAQA GCSE Chemistry (8462), Higher tier · Using resources › Earth's resources and potable water
Practise Waste water treatment. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Build a paper on this topic ▶ Watch videos on Waste water treatment (Free Science Lessons on YouTube) · Practise all of Earth's resources and potable water
Quick recall Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Name the process used to break down organic matter in sewage sludge, which also produces methane gas. anaerobic digestion
Which stage happens first: screening, or sedimentation? screening Sample questions Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1 Easy 4 marks
Sewage must be treated before the water can be released into the environment.
(a) Which stage of sewage treatment produces sewage sludge and effluent?one box.[1]
Anaerobic digestion Screening Sedimentation Sterilisation (b) What is removed from sewage during screening?[1]
(c) Name two things that must be removed from sewage and agricultural waste water.[2]
Show the answer and mark scheme (a) Answer: Sedimentation
(b) large objects (e.g. rags, plastics) / grit (c) organic matter harmful microbes Question 2 Medium 5 marks
After screening and grit removal, sewage is left to settle in sedimentation tanks. This produces sewage sludge and effluent.
(a) Describe how the sewage sludge and the effluent are then treated.[2]
(b) Industrial waste water may need extra treatment compared with sewage.[2]
(c) Anaerobic digestion of sewage sludge produces methane.[1]
Show the answer and mark scheme (a) sewage sludge: anaerobic digestion (by bacteria) effluent: aerobic biological treatment (air is bubbled through so bacteria break down organic matter) (b) it may contain harmful chemicals (e.g. toxic metal compounds) which must be removed as well as organic matter before the water is released (c) as a fuel, e.g. to generate electricity / heat for the sewage works Question 3 Hard 6 marks
Urban lifestyles produce large amounts of sewage that must be treated before the water is released into a river.
Describe how sewage is treated so that the water can be released into a river.[6]
Show the answer and mark scheme screening removes large objects such as rags and plastics, and grit is removed sedimentation in tanks: solids settle to form sewage sludge, leaving liquid effluent sewage sludge undergoes anaerobic digestion by bacteria, breaking down organic matter anaerobic digestion produces methane that can be used as a fuel; digested sludge can be used as fertiliser effluent undergoes aerobic biological treatment: air is bubbled through so bacteria break down organic matter organic matter and harmful microbes must be removed before the water is released industrial waste water may also need harmful chemicals to be removed Marked with levels of response: the full level descriptors are in the app.
Related subtopics
Stuck? Get 1-to-1 help. Chhetri Academy tutors GCSE and A level Maths and Science online, with a free 30-minute trial lesson.
Book a free trial