Carbon cycling/potable water

• Materials recycling in an ecosystem

  1. Living things take in elements from environment

  2. Turn elements into complex compounds

  3. Elements passed along food chains

  4. Elements recycled as waste and decomposed
• Potable water

  Water that is safe for humans to drink
• Potable water is not pure water because it almost always contains dissolved impurities
• For water to be potable, it must have sufficiently low levels of dissolved salts and microbes
• Producing potable water in the UK

  1. Fresh water is filtered

  2. Fresh water is sterilised, commonly with chlorine, ozone or UV light
• Distillation

  A way to make potable water from seawater
• Reverse osmosis

  An alternative way to desalinate seawater, more energy efficient than distillation
• Large amounts of waste water are continuously produced from domestic, industrial and agricultural uses
• Waste water has to be treated before it can safely be returned to the environment
• Treating waste water

  1. Filtration to remove large solids

  2. Flocculation to clump fine particles which then settle as sludge

  3. Filtration again

  4. Chlorination to kill microorganisms