Using Resources

• Sustainable Development:

  Development that meets the needs of current generations without comprimising the ability of future generations to meet their own needs
• Potable water is produced by...

  • Choosing an appropriate source of fresh water
  • Passing the water through filter beds to remove any solids
  • Sterilising to kill microbes
• Steralising Agents for Potable Water:

  • Chlorine
  • ozone
  • Ultra violet light
• Chlorine gas is toxic so the use has to be heavily monitered
• Ultra violet light to kill microbes avoids the use of chemicals but is more expensive
• Desalination is done by distillation or reverse osmosis but is very expensive
• Reverse Osmosis:

  • Sea water is pushed through a semi-pearmeable membrane under high pressure
  • It only allows the water molecules through
  • The high pressure requires a lot of energy to produce
  • The membranes are expensive
• Urban living and industrial processes create large amounts of waste that need to be treated before being released to the environment
• Sewage and agricultural waste water require the removal of organic matter and harmful microbes
• Industrial waste water may need the removal of organic matter and harmful chemicals
• Sewage treatment:

  • Screening and grit removal
  • Sedimentation to produce sewage sludge and effluent
  • Anaerobic digestion of sewage sludge
  • Aerobic biological treatment of effluent
• New methods of mining avoid the digging, moving, and disposing of large amounts of rock that traditional mining does
• Phytomining uses plants to absorb metal compounds from soil. The plants are harvested and then burned to produce ash that contains the metal compounds
• Bioleeching uses bacteria to produce leachate solutions that contain metal compounds
• Phytomining and Bioleaching need less energy than other methods and works on low concentration ores but takes a long time
• Life Cycle Assesments asses the environmental impact of:

  • Extracting and processing raw materials
  • Manufacturing and packaging
  • Use and operation during lifetime
  • Disposal at the end of its useful life - transport included
• To reduce the use of resources we can recycle, buy less, and reuse what we've already bought
• Advantages of recycling:

  • Less acid rain
  • Metal ore reserves last longer
  • Less energy used in mining
  • Creates local employment
• Disadvantages of recycling:

  • Collection and transport problems
  • Cost of transport
  • Difficult to seperate
• Corrosion is the destruction of metals by chemical reactions with substances in the environment
• Corrosion can be prevented by using a coating that acts as a barrier (greasing, plating, electroplating), These stop air and water coming in contact with the metal
• Some coatings are reactive and may contain an inhibitor or a more reactive metal
• If two metals are in contact the more reactive one will corrode instead of the less reactive one
• Zinc is used to galvanise iron. It creates sacrificial protection as it is more reactive than iron
• Bronze is an alloy of copper and tin. It's used for making statues and decorative objects
• Brass is an alloy of copper and Zinc. Used for producing water taps and door fittings
• Gold used for jewellery is normally an alloy with silver, copper, and zinc
• Pure gold is 24 carats
• 18 carat gold is 75% gold
• Aluminium / magnesium alloys are low density and used in aerospace manufacturing
• Steels are alloys of iron that contain specific amounts of carbon and other metals
• High carbon steel is strong but brittle
• Low carbon steel is softer and more easily shaped
• Stainless steel contains chromium and nickel and is hard and resistant to corrosion
• The properties of polymers depend on what monomers they are made from and the conditions they are made under
• Low density and high density polyethene are produced from ethene under different catalysts and conditions.
• Thermosetting polymers do not melt when heated. The polymer molecules are linked together by strong cross-links.
• Thermosoftening polymers soften when heated and can be remoulded and keep the new shape upon cooling. The molecules are attracted together by weak intermolecular forces
• Most of our glass is soda-lime glass. Made from heating a mixture of sand, sodium carbonate, and limestone.
• Borosilicate glass is made from sand and boron trioxide. It melts at higher temperatures than soda-lime glass.