Water in the Desert: Sea Water Desalination

Oceans and seas are the largest reservoirs of water on the Earth, making up 97% of the total amount of water worldwide. In order to exploit this enormous potential to obtain drinking water and water for industrial use, worldwide efforts are underway to find new processes and methods. According to the German Desalination Society (Deutsche MeerwasserEntsalzung e.V.), there are around 12,000 major sea water desalination plants in operation, which in total produce approximately 36 million cubic meters of drinking water each day, and a sharp upward trend continues to be evident.

The Gulf states, in particular, suffer from an extreme lack of water and have long been unable to obtain sufficient supplies from their groundwater reservoirs. They have therefore been using sea water desalination to produce drinking water and industrial water for decades. Desalination works according to standard thermal principles: sea water is heated until it reaches boiling point and evaporates, at which point the salt irons dissolved in the water such as sodium and chloride are left behind in the brine. The hot steam is then cooled and condensed into fresh water. However, this process has some significant disadvantages, not least the fact that it uses so much energy. Despite a whole host of recovery technologies, it is often simply not financially viable, especially for countries that lack energy resources.

That is why a combination of ultrafiltration and reverse osmosis is an excellent alternative for the future. The initial cleaning of the sea water is efficiently performed by means of ultrafiltration, while the actual desalination process is effected using reverse osmosis. According to information from the German Desalination Society (Deutsche MeerwasserEntsalzung e.V.), the falling cost of this technology and the low amounts of energy it requires mean that reverse osmosis is set to represent a proportion of around 80% of sea water desalination in around 15 years time, with the corresponding potential for ultrafiltration that this implies. And it is not only existing plants that will be upgraded: For many countries, the combination of ultrafiltration and reverse osmosis will represent their first opportunity to carry out sea water desalination.

Sea water reference projects