Many parts of the world are experiencing severe water stress with limited fresh water supplies. In some parts of the world water use exceeds renewable water capacity – renewable water is defined as surface and underground water supplies that are replenished by rainwater. These regions often use non-renewable ground water supplies, which are also further down and require more energy to exploit, or over-exploit underground aquifers resulting in salt water intrusion. Increased industrialisation and urbanisation has also lead to ground water pollution in some regions.
In some areas, the affects of salt water intrusion are compounded by the impact of anthropogenic-induced climate change. Declining annual rainfall and rising temperatures have resulted in increased evaporation of surface water. The concept of peak renewable water levels has been proposed, with some countries already reaching and exceeding their ecological water limit.
Eighty countries are classified as suffering from severe water shortages, twenty of which are classified as scarcity. According to the UN approximately 1,500 m3 of freshwater per capita per year is needed for unhindered economic development. In Europe alone two water countries have considerably less fresh water than this– Cyprus has 74 and Malta has 979 m3 per capita per year. These and many other countries use or are considering using desalination to meet their fresh water needs – by definition, desalination is the removal of salts from water to produce water with a lower salinity.
There is a growing need for desalinated water from the general public, which has a greater understanding of water issues and often demands high quality potable water. Several industries require ultra pure water produced from desalination, and these industries are growing e.g. pharmaceutical and semi-conductors, and equipment can now measure contaminants at very low concentrations. This is especially pertinent as increasing industrialisation has resulted in higher incidents of water contamination in some parts of the world.
