2.3 - How can water supply be managed sustainably?

2.3 - How can water supply be managed sustainably?

1. Recycling 'Grey water'

   • Grey water is slightly contaminated water - free from faecal matter, grease and solids - only slight bacterial contamination
   • Used in places where water is reasonably clean to begin with - not polluted with chemicals
     • Domestic grey water can be pumped straight back into homes if collected separately from black water
       • Not safe to drink this water!
   • Purification (by mechanical or biological means) can make grey water drinkable
     • Most grey water is easier to treat than 'black water' - less contaminants
   • Ecological benefits
     • Lower fresh water extractoin
     • Less impact from treatment infrastructure
     • Topsoil nitrification
     • Reduced energy use and chemical pollution
     • Groundwater can recharge
     • Increased plant growth
     • Reclamation of nutrients
   • Disadvantages
     • Potential pollution risk if not reused correctly
     • Increased health risks
     • Has plumbing requirements - complex system
     • Continuous maintenance
   • Case study: Aquaco, UK
     • Company which delivers grey water

2. NEWater, Singapore

   • Water produced by Singapore's public utilities board
   • Treated sewage water - purified using dual membrane and ultra-violet tech + conventional water treatment
   • Drinkable water + consumed by humans
   • However is mostly used in industry requiring high amounts of water
   • Currently produces 50% of daily water needs
     • Hopes to reach 100% by 2060

3. Desalinisation in Saudi Arabia

   • Total cost of producing 1m cubed of fresh water from the sea = $.5 to $1.5 for 1000 litres
   • With pop of 7 billion - can provide over 10 litres of clean water a day for 1 cent
     • It is sustainable - but only to those who can afford it!
   • Saudi Arabia environment
     • Harsh, dry desert - great temp extremes
     • Largest country in world without a permanent river
       • Main source = aquifers
     • Plentiful in petroleum, natural gas, iron ore, gold and copper
   • Fresh water withdrawal in 2000
     • Total = 17km cubed per yr
       • 10% domestic
       • 1% industrial
       • 89% agric
     • 2.4km cubed of renewable water resources
     • World's largest producer of desalinated water
     • Saline Water Conversion Corporation
       • 3 million m cubed per day
         • 70% of the water used in Saudi Arabian cities
   • Economic impact
     • Expensive - £3.8 billion
       • Cannot be acquired easily by LEDCs
       • High transport costs
   • Enviro impact
     • Salt solution extracted - considered industrial waste - cannot go back into sea
     • Reverse osmosis occuring