C10 - Using Resources

• We rely on the Earth's resources to meet our basic needs as humans.

  
  

  E.g.

  • Physical needs - for shelter, warmth and transport
  • Bodily needs - for food, water, hygiene and health care.
• People have always used natural resources gathered from the environment. Chemists produce alternatives.
• Finite resources are those that are being used up at a faster rate than they can be replaced.
• Renewable resources are those that can be replaced at the same rate at which they are used up.
• Whenever possible, industries are moving towards renewable resources to conserve finite resources and to improve sustainability.
• Sustainability we can think of as developments that meet the needs of society now, without endangering the ability of future generations to meet their own needs.
• Potable water is water that is safe to drink.
• Potable/Drinking water should have low levels of:

  • Dissolved salts
  • Microbes
• Potable water is NOT pure water
• Potable water is obtained by:

  • Rainwater dissolving some gases from the air as it falls to the ground
• This rainwater collects:

  • Underground - "ground water"
  • in lakes
  • in rivers

  And its called "fresh water"
• Potable water is produced by:

  1. Choosing an appropriate source of fresh water
  2. Passing the water through filter beds (sand and gravel layers remove solid particles)
  3. Sterilising (killing microorganisms)
• What is used for sterilising:

  • Chlorine
  • Ozone
  • Ultraviolet light (UV)

  These are called sterilising agents.
• If fresh water supplies are limited, then we may have to desalinate (remove salt) salty water.
• Desalination is done by:

  1. Distillation
  2. Using membranes e.g. reverse osmosis
• Sewage treatment:

  1. Screening and grit removal
  2. Sedimentation - to produce sewage sludge and effluent
  3. Anaerobic digestion of sewage sludge
  4. Aerobic biological treatment of effluent (Aerobically digested)
• 3 ways of obtaining Potable water:

  1. Fresh water supplies or ground water
  2. Desalination of salty water
  3. Treatment of sewage/agricultural water