water

• describe potable water 


  water that is safe to drink but still impure
• give requirements of potable water

  low amount of dissolved substances, no microorganisms and ph between 6.5 and 8.5
• describe process to produce potable water

  1. filtration through mesh and sand and gravel
  2. sterilisation through chlorine, ozone and uv
• describe desalination 


  producing potable water from sea water
• give methods of desalination

  distillation and reverse osmosis
• give sources of waste water

  domestic, agricultural and industrial
• describe process of waste water treatment

  1. screening and grit removal
  2. sedimentation
  3. digestion
• describe sedimentation


  sludge - heavy solid sink to bottom

  effluent - lighter solids float to top
• describe digestion 


  sludge - anaerobic

  effluent - aerobic
• describe products of digestion

  sludge - methane for energy and waste for fertiliser

  effluent - released back to environment