What is potable water
Water that is safe to drink
What is the difference between potable water and pure water
Potable water contains low levels of dissolved salts and microbes
How is potable water produced
- choose an appropriate source of fresh water
- pass water through filter beds
- use sterilising agents to sterilise the water
What are some examples of sterilising agents
Chlorine, ultraviolet, ozone
What is desalination
The removal of salts from water
How does desalination work
- water is passed through a semi permeable membrane at a high pressure
- the membrane allows water to pass but blocks salt
This is also called reverse osmosis
What is the disadvantage of desalination
Requires a lot of energy
Explain the steps to sewage treatment
- screening and grit removal to remove large particles
- sedimentation forms sewage sludge and effluent (the liquid)
- the sewage sludge is digested anarobically by specific bacteria
- the effluent is treated with aerobic biological treatment
How is sewage sludge digested?
Anarobically
How is effluent from sedimentation treated
Aerobic biological treatment
How does phytoming extract copper
Uses plants to absorbe metal compounds
The plants are harvested then burned to proceed ash that contained metal compounds
How is bioleaching used to extract copper
- uses bacteria to produce leachate solutions that contained metal metal compounds
What are the 4 stages considered in life cycle assessments
- extracting and processing raw materials
- manufacturing and packaging
- use and operation during its lifetime
- disposal at the end of its life
How are raw materials obtained from the earth
Quarrying and mining
What is corrosion , give an example
The destruction of materials by chemical reactions with substances in the environment
E.g rusting
What are the conditions needed for rusting
Air and water
How can corrosion be prevented
Applying a coating that acts as a barriers such as
coating in aluminium oxide
Greasing
Electroplating
What is bronze an alloy of
Copper and tin
What is brass an alloy of
Copper and wind
What if gold jewellery often alloyed with
Silver, copper or zinc
What is steel an alloy of
Iron and other metals such as carbon
What are the advantages of low carbon steel
Softer and more easily shaped
What are the advantages and disadvantages of high carbon steel
It is harder but more brittle
What is stainless steel made of
Steel, chromium and nickel
