chem 2 - water

Question 1

what is desalination

Answer 1

process of removing salt from salt water

Question 2

how to turn fresh water to potable water

Answer 2

1. filtration (removes solids)
2. sterilisation (to kill harmful bacteria, done using chlorine, ozone or UV light)

Question 3

how to turn sea water into potable water (4)

Answer 3

1. desalination
2. distillation or reverse osmosis used to desalinate water
3. filtration
4. sterilisation

Question 4

why isn’t sea water the best way to get potable water

Answer 4

because both distillation and reverse osmosis need lots of energy so is expensive and not practical in large quantities

Question 5

process of treating waste water (6)

Answer 5

1. sewage is screened (removes larger pieces)
2. sedimentation (where it stands in a settlement tank and separates into sludge and effluent)
3. effluent treated with biological aerobic digestion (breaks down organic matter)
4. sludge broken down with anaerobic digestion
5. filtration
6. sterilisation

Question 6

what happens with the sludge that undergoes anaerobic digestion

Answer 6

it releases methane gas, which is used as an energy source
and the rest of the waste is used as a fertiliser

Question 7

which is the best sewage treatment or sea water treatment

Answer 7

waste water since it uses less energy than salt water during desalination