5.14 Desalination
In many parts of the world, surface water or non-saline groundwater stocks are not adequate to satisfy the water demand. While one may immediately think of the Middle East as being one such area, it is less obvious that many islands (e.g. the Canary Isles, Madeira, the Channel Islands) also suffer the same problem. In such circumstances, people have been forced to consider the sea and brackish underground aquifers as water sources. To make these saline waters potable, the salt has first to be removed by desalination. Desalination systems are also used on ships and on offshore oil and gas production platforms as a means of producing potable water. The two major desalination processes used worldwide are multistage flash distillation and reverse osmosis. Other techniques commonly used are electrodialysis and solar distillation, often for small communities.