water as a resource: potable and waste water

Question 1

what is potable water

Answer 1

it is water that is safe for humans to drink

Question 2

is potable water pure and why

Answer 2

it is not pure and it has low levels of dissolved substance/salt in it.

pure water bad for human cells- osmosis, so low level impurity good.

pH potable water not 7

Question 3

where do the dissolved minerals come from

Answer 3

they come from the rain

Question 4

3 sources of freshwater

Answer 4

underground aquifers
lakes
rivers

Question 5

3 steps for producing potable water

Answer 5

1. an appropriate source of freshwater is selected
2. the water is passed through filter beds to remove insoluble solids of varying size
3. water sterilised to kill microbes

Question 6

3 types of steriliser

Answer 6

1. chlorine
2. ozone
3. ultraviolet light

Question 7

how to obtain water if freshwater supplies limited

Answer 7

desalination is required.

by distillation OR membrane processes (reverse osmosis)

expensive process as very energy intensive

Question 8

where does our waste water come from

Answer 8

urban lifestyle and industrial action

Question 9

why do sewage, agricultural, industrial waste need to be treated

Answer 9

contain microbes, chemicals and harmful organic matter

Question 10

process of sewage treatment

Answer 10

1. filtration, screening and grit removed
2. sedimentation causes less dense to rise and dense to sink. leads to solid sludge and liquid effluents

3a. sludge is anaerobically (no o2) digested and broken down by bacteria and nat gas (CH4) and fertiliser produced

3b. effluent aerobically (with o2) digested and broken down by bacteria and then the water is sterilised and released back into environment.