2.3 - How can water supply be managed sustainably?

Recycling 'Grey water'
1. Grey water is slightly contaminated water - free from faecal matter, grease and solids - only slight bacterial contamination
2. Used in places where water is reasonably clean to begin with - not polluted with chemicals
  1. Domestic grey water can be pumped straight back into homes if collected separately from black water
    1. Not safe to drink this water!
3. Purification (by mechanical or biological means) can make grey water drinkable
  1. Most grey water is easier to treat than 'black water' - less contaminants
4. Ecological benefits
  1. Lower fresh water extractoin
  2. Less impact from treatment infrastructure
  3. Topsoil nitrification
  4. Reduced energy use and chemical pollution
  5. Groundwater can recharge
  6. Increased plant growth
  7. Reclamation of nutrients
5. Disadvantages
  1. Potential pollution risk if not reused correctly
  2. Increased health risks
  3. Has plumbing requirements - complex system
  4. Continuous maintenance
6. Case study: Aquaco, UK
  1. Company which delivers grey water
NEWater, Singapore
1. Water produced by Singapore's public utilities board
2. Treated sewage water - purified using dual membrane and ultra-violet tech + conventional water treatment
3. Drinkable water + consumed by humans
4. However is mostly used in industry requiring high amounts of water
5. Currently produces 50% of daily water needs
  1. Hopes to reach 100% by 2060
Desalinisation in Saudi Arabia
1. Total cost of producing 1m cubed of fresh water from the sea = $.5 to $1.5 for 1000 litres
2. With pop of 7 billion - can provide over 10 litres of clean water a day for 1 cent
  1. It is sustainable - but only to those who can afford it!
3. Saudi Arabia environment
  1. Harsh, dry desert - great temp extremes
  2. Largest country in world without a permanent river
    1. Main source = aquifers
  3. Plentiful in petroleum, natural gas, iron ore, gold and copper
4. Fresh water withdrawal in 2000
  1. Total = 17km cubed per yr
    1. 10% domestic
    2. 1% industrial
    3. 89% agric
  2. 2.4km cubed of renewable water resources
  3. World's largest producer of desalinated water
  4. Saline Water Conversion Corporation
    1. 3 million m cubed per day
      1. 70% of the water used in Saudi Arabian cities
5. Economic impact
  1. Expensive - £3.8 billion
    1. Cannot be acquired easily by LEDCs
    2. High transport costs
6. Enviro impact
  1. Salt solution extracted - considered industrial waste - cannot go back into sea
  2. Reverse osmosis occuring

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2.3 - How can water supply be managed sustainably?

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