Using resources

• What is potable water?

  water that is safe to drink
• what is pure water?

  just water molecules
• What is salty water?


  Water molecules with dangerously high levels of salt and can also have high levels of harmful microbes
• What is the name of the process that turns salty water in potable water?

  Desalinisation
• What are the two methods of desalinisation?

  • reverse osmosis
  • Distillation
• What is reverse osmosis?

  Uses membranes to separate the salts dissolved in the water, the water needs to be pressurised, this is an expensive process
• How is potable water produced from fresh water?

  • water is passed through filters to remove large objects
  • water is sterilised to kill any microbes (using UV light, ozone or chlorine)
• Process of treating sewage water

  1. Sewage and grit removal - passed through metal filters to remove large objects

  2. Sedimentation - sewage is left so that solid sediments can settle out of the water, it sinks to the bottom and the liquid sits on top

  3. Effluent - this is the remaining liquid, it has no solid matter but still contains some harmful microorganisms and matter

  4. Aerobic treatment - bacteria is added to the effluent which feeds on the organic matter and the harmful microorganisms, the bacteria break down the matter using aerobic respiration

  5. Bacteria removed - Bacteria settle out of the water

  6. Discharged back into rivers
• What happens to the sludge left over from sewage treatment?

  • sediment that is left after sedimentation is called sludge, this contains organic matter, water, dissolved compounds and small solid particles
  • ANAEROBIC TREATMENT - Bacteria are added to digest the organic matter, this is done with little oxygen
  • BIOGAS - the anaerobic digestion of sludge produces biogas, can be used as fuel
  • The remaining sludge can be dried out and also used as fuel when burnt
• What are two alternative copper extraction methods?

  Phytomining and bioleaching
• What is the process of phytomining?

  1. Grow plants near the metal ore
  2. The plants absorb the metal ions
  3. Harvest and burn plants
  4. The ash contains the metal compound
  5. Process the ash. by electrolysis or displacement with scrap metal
• What is the process of bioleaching?

  1. Grow bacteria near the metal ore
  2. Bacteria produce leachate solutions that contain the metal compound
  3. process the leachate by electrolysis or displacement with scrap metal
• How does low density polyethene form?

  Addition polymerisation reaction of ethene is carried out under high pressure and in the presence of a small amount of oxygen, the branched polymer chains cannot pack together so causing the low density of polymer
• How does high density polyethene form?

  When the addition polymerisation reaction of ethene is carried out using a catalyst at 50C, the polymer chains are straight and can pack tightly together