Using Resources

• Potable water is water that is safe to drink
• Finite resources have a limited supply and will eventually run out
• Finite resources from the Earth, oceans and atmosphere are processed to provide energy and materials
• Potable water is not ‘pure’ because it contains dissolved substances, athough to be safe it must have sufficiently low levels of dissolved salts and microbes
• Potable water using fresh water:

  • an appropriate source of fresh water is selected (rain provides water with low levels of dissolved substances and this collects in the ground/rivers/lakes)
  • the water is passed through filter beds to remove different sized insoluble solids the water is then sterilised, to kill microbes (sterilising agents include: ozone, UV light or chlorine
• Potable water using sea water:

  • can be done by distillation
  • OR can be done using processes with membranes (e.g. reverse osmosis)
  • BOTH are very expensive
• How quality water is produced:

  • Water is passed through a mesh screen to remove large bits e.g twigs or grit
  • Chemicals are added to make solids and microbes stick together to form sediment and sink
  • There is then anaerobic digestion of sewage sludge
  • The water is then sterilised with chlorine to kill any microbes left.
• it is relatively cheaper and easier to obtain potable water from groundwater and wastewater than salt water, although seawater is a plentiful raw material, so is good for countries with little fresh water
• ways of extracting copper from low-grade ores include phytomining, and bioleaching
• Phytomining uses plants to absorb metal compounds. Plants are harvested and then burned to produce ash that contains metal compounds
• Bioleaching uses bacteria to produce leachate solutions that contain metal compounds
• copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis
• life cycle assessments are carried out to assess the environmental impact of products in stages
• stages of LCA:

  • extracting and processing raw materials
  • manufacturing and packaging
  • use and operation during its lifetime
  • Disposal at the end of its useful life, including transport and distribution at each stage
• Reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, use of energy sources, waste and environmental impacts
• Some products, such as glass bottles, can be reused
• Metals can be recycled by melting and recasting or reforming into different products