Water treatment processes

Question 1

sedimentation

Answer 1

water remains static to let suspended solids e.g silt to settle

Question 2

screening

Answer 2

metal grills / meshes
removes suspended solids e.g vegetation, plastics

Question 3

aeration

Answer 3

bubbles of air / water sprays
aerate the water to increase dissolved oxygen content
removes odour and some insoluble metals

Question 4

flocculation

Answer 4

removes clay particles by neutralising electrostatic charge

Question 5

filtration

Answer 5

filters used to removed remaining suspended solids and bacteria
through sand and gravel layers

Question 6

activated carbon filters

Answer 6

remove organic chemicals e.g pesticides that absorb onto carbon granules/ particles

Question 7

sterilisation

Answer 7

addition of chlorine, ozone or UV light sterilises water and kills pathogens

Question 8

pH control

Answer 8

adding crushed lime or chlorine

Question 9

fluoridation

Answer 9

improves dental health

Question 10

ion exchange

Answer 10

toxic metal ions adsorb onto polymer beads
also produces softer water

Question 11

reverse osmosis

Answer 11

filtered at high pressure through partially permeable membrane - spenny

Question 12

distillation

Answer 12

water boiled, stream produced is condensed and collected