C14

• Sustainable development


  Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.
• Finite resource


  A resource that cannot be replaced once it has been used.
• Renewable resource


  A natural resource that can be replaced at the same rate at which the resource is consumed
• Potable water


  Water that is safe to drink (low enough dissolved solids)
• Pure water


  Water containing no other elements or compounds
• Three stages to produce potable water

  Choose a source of fresh water, pass the water through filter beds and then sterilise it
• Three sterilising methods

  Ozone, UV light, Chlorine
• How to obtain potable water if fresh water supplies are limited

  Desalination
• Two methods of desalination

  Distillation or reverse osmosis
• Disadvantage of desalination


  Large energy requirement
• Four stages in waste water treatment

  Screening and grit removal, sedimentation to produce sewage sludge and effluent then anaerobic digestion of sewage sludge and aerobic biological treatment of effluent
• Phytomining


  Uses plants to absorb metal compounds, which are harvested and burned to produce ash that contains metal compounds.
• Bioleaching


  Uses bacteria to produce leachate solutions that contain metal compounds.
• Advantages of phytomining and bioleaching

  Low-grade ores can be used, mining is not required, less waste rock.
• Disadvantages of phytomining and bioleaching

  Very slow (can take years), copper compounds still need to be purified
• Four stages in a Life Cycle Assessment

  Extracting and processing raw materials

  Manufacturing and packaging the product

  Use of the product

  Disposal
• Three ways to reduce the use of resources

  Reduce, reuse and recycle
• What is an ore?

  • A naturally occurring rock or mineral
  • Valuable metal or mineral can be extracted
• What are the three main steps in extracting metals from ores?

  1. Concentration: Increase metal content, remove impurities
  2. Extraction/Reduction: Convert concentrated ore to metal
  3. Refining: Further purify the metal
• What is the purpose of concentration in metal extraction?

  To increase metal content by removing impurities
• What is the role of reduction in metal extraction?

  It removes oxygen from metal oxides in ores
• Why is bioleaching significant?

  It is an environmentally friendlier extraction method
• How is froth flotation used in ore concentration?

  • Separates ore particles from waste rock
  • Exploits differences in surface properties
  • Minerals attach to air bubbles and float
• What is bioleaching?

  Using bacteria to oxidize metal sulfides
• What environmental issues are associated with metal extraction?

  • Habitat destruction
  • Water and air pollution
  • High energy consumption
  • Greenhouse gas emissions
• Why is recycling important in the context of Earth’s resources?

  It conserves natural resources and reduces emissions
• What economic factors affect the extraction of metals from ores?

  Ore grade, costs, market demand, recycling feasibility
• What are some future trends in metal extraction and resource use?

  • Developing greener extraction methods
  • Improving energy efficiency
  • Adopting circular economy models