water treatment

Question 1

list the order or water treatment processes

Answer 1

1) sedimentation
2) screens
3) aeration
4) flocculation
5) filtration
6) activated carbon filters
7) sterilisation

Question 2

outline sedimentation processes

Answer 2

water remains static to let suspended solids such as silts settle to the bottom

Question 3

outline screen processes

Answer 3

metal grills or meshes are used to remove vegetation or little form water flow

Question 4

outline flocculation

Answer 4

electrostatic charges suspending material such as clay, are neutralised by adding flocculants which cause particles to clump together and fall to the bottom of tanks

Question 5

outline filtration

Answer 5

filters are used to remove remaining suspended soils and bacteria by passing water through layers of sand and gravel

Question 6

outline activated carbon filters

Answer 6

particles of activated carbon are used to remove organic chemical such as pesticides which absorb onto the carbon molecules

Question 7

outline sterilisation

Answer 7

addition of chlorine, ozone or exposure to UV light is sued to sterilise pathogens

Question 8

what is fluoridation

Answer 8

the addition of fluoride in some areas to improve dental hygiene

Question 9

what are the techniques to treat salt water

Answer 9

1) reverse osmosis

2) distillation

Question 10

outline reverse osmosis

Answer 10

sea water is passed under high pressures through a partially permeable membrane where salt molecules cant move producing fresh water which is collected

Question 11

outline flash distillation

Answer 11

water is boiled and pressure is reduced, the steam is collected and condensed producing fresh water