C14 - The Earth's Resources

• UK Water Purification

  • Filter to remove solid impurities
  • Sterilise using chlorine or UV to kill harmful microorganisms and bacteria
• Hard water has more minerals dissolved in it. Soft water has less minerals dissolved in it.
• Waste water treatment:

  • Screening - removes all of large solids
  • Primary settling tank - water moved around slowly so remaining slowly settles to bottom. Arms at top removes fats and oils.
  • Secondary settlement tank - useful bacteria feed on microorganisms in waste water. Oxygen added to breed useful bacteria
  • Water can be filtered again
• Sludge from waste water treatment stored in silos and can be used as fertilisers on farms. Also biogas can be collected for fuel in the plant.
• Life Cycle Assessment

  • Extracting and processing raw materials
  • Manufacturing and packaging
  • Use and operation during lifetime
  • Disposal at end of useful life
  • Transport and distribution at each stage
• LCAs used to assess the environmental impact of products in each stage of their lives.
• Recycling pros: reduces the amount of waste going to landfill, reduces the amount of raw materials needed to make new products and reduces energy consumption.
• Recycling cons: Energy required to recycle products
• Recycling must be used in conjunction with reducing and reusing.
• Phytomining

  • Plants grown in low grade soil
  • Plants absorb metal ions through roots and concentrate in their cells
  • Plants harvested and burnt
  • Ash left behind contains metal compounds
• Phytomining is slow : reduces need to mine new ore, conserves limited supplies of high-grade ore and reduces amount of rock waste from traditional mining.
• Bioleaching uses certain bacteria to break down low grade ores to create an acidic solution called leachate containing metal ions.
• Bioleaching does not need high temperatures but it produces toxic substances e.g. sulphuric acid which damage the environment.