Using resources (P2) Flashcards
What is potable water?
Water that is safe to drink
What are the stages of making water potable?
- Choose a good source of fresh water
- Pass water through filter beads to remove materials
- Sterilise the water to kill microbes (use chlorine, ozone or UV light)
What are the 3 ways to sterilise water?
- chlorine
- ozone
- ultra violet light
How can countries where fresh water is scarce make their water potable?
Use salt water and desalinate it
- either distillation
- or reverse osmosis
What are the 2 ways of desalinating salt water?
- distillation
- reverse osmosis
What is reverse osmosis?
passing of water through membranes
Is potable water the same as pure water? and why
No because pure water has no dissolved substances at all whereas potable has low levels of dissolved substances
Why is water sterilised?
to kill microbes
What do distillation and reverse osmosis have in common?
- both reduce levels of dissolved minerals
- both require large amounts of energy which makes them expensive
What is water used for?
- agriculture
- personal hygiene- baths + showers
- flushing toilets + washing clothes
What does waste water contain?
- harmful microorganisms
- organic molecules e.g. urine and feces
Treating waste water process
- Screening- water passed through a mesh to remove solids + pieces of grit
- Sedimentation- sewage settles in a tank - produces solid sludge and liquid effluent
- Liquid effluent undergoes biological aerobic digestion - air is pumped through the liquid to encourage aerobic bacteria to break down the organic matter.
Solid sludge is digested by anaerobic bacteria- the absence of oxygen produces methane which can be used as an energy source. - The liquid effluent can be safely discharged into nearby rivers or the sea and the remaining solid sludge can be used by farmers as fertilisers
What does sedimentation in the process of treating waste water create?
- liquid effluent
- solid sludge
What type of digestion does sludge undergo?
- anaerobic
What type of digestion does effluent undergo.
- aerobic
What are examples of ceramics?
- vase
- kitchen tiles
- wine glass
What are the two types of cermaics?
- glass ceramics
- clay ceramics
what are the two types of glass ceramic?
- soda-lime glass
- borosilicate glass
How are soda-lime glass ceramics made?
- mix together sand, sodium carbonate and limestome
- heat in a furnace until it melts
What is a disadvantage of soda-lime glass?
- relatively low melting point - this limits its uses
How are borosilicate glass ceramics made?
- melting together sand and boron trioxide
What are glass ceramics useful for
- objects that require heating
e.g. kitchenware +labware
What makes borosilicate glass more useful than soda-lime glass?
Higher melting point
How are clay ceramics made?
- clay is a mineral found in the ground
- then when wet it can be shaped
- then heated in a furnace to harden
