10.1.2 Potable Water Flashcards
Potable water
drinkable water containing dissolved substances
Pure water
100% H2O
Waste water
Used water from homes, industry and agriculture
Sea water
Water in seas and oceans
Groundwater and aquifer
Water in underground streams and lakes
Methods of sterilisation (3p)
- ultraviolet
- ozone
- chlorine
Potable water production in the UK
From groundwater / freshwater to potable water
Making potable water from groundwater/freshwater (4p)
Screening: a grid acts like a sieve, removing large insoluble objects
- Sedimentation: small insoluble particles ‘settle out’ of the screened water source
- Filtration: very small, insoluble particles are filtered through increasingly fine layers
-Sterilisation- Microbes (like bacteria) are killed with either chlorine, ultraviolet or ozone
Desalination (2p)
- the process of removing dissolved minerals from water
- used when freshwater is limited (it uses sea water)
- eg. distillation and reverse osmosis
Reverse osmosis
A separation techniques used to obtain pure water from salt water
Reverse osmosis process (2p)
- Salt water is passed through a partially permeable membrane using a powerful pump
- Only the smaller water particles can pass through so the salt is left behind
Simple distillation
- Separation technique involving boiling a liquid mixture then condensing the pure liquid
eg. separating pure water from salt water
What are the two ways of making potable water from salt/sea water? (2p)
- Reverse osmosis
- Distillation
Difference between simple and fractional distillation (2p)
- fractional distillation is used when the components have close boiling points
- simple distillation is used when the boiling points are significantly different
Freshwater
- water with low levels of dissolved substances that collects in the ground and in lakes and rivers
