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Seawater desalination, a solution to water shortage

11.02.2015

A hundred elephants on a manhole cover: that is the equivalent of the pressure exerted on water to extract the salt. Whereas the development of desalination has long been hampered by the associated financial and energy cost, this is changing with progress in the technique of reverse osmosis and state-of-the-art technologies: desalination plants are now set to be one of the most promising solutions for combating water shortage.

How does desalination work? First, water is pumped into the marine ecosystem. Once the sand and seaweed have been removed, the water is filtered through extremely fine membranes at very high pressure. The extremely salty brine remaining is treated, diluted and returned to the sea, while the pure water is recovered and enriched with mineral salts to make it drinkable.

Reverse osmosis racks at the seawater desalination plant in Llobregat, Spain, constructed by SUEZ ENVIRONNEMENT. © Abacapress / Michel Martinez Boulanin

This solution is contributing to combating water shortage, an issue of critical proportions: by 2030, 3.9 billion people will be living in a situation of severe water shortage. This is all the more alarming given that the countries facing this situation are often those with the fastest growing populations.

One of the most promising solutions lies in the oceans which harbor 97.5% of the earth’s water reserves. Melbourne’s desalination plant, in operation since 2012 and managed by SUEZ ENVIRONNEMENT (Degrémont), is the benchmark in the field: it supplies water to the city’s population with no need to worry about lack of rainfall, while windpower ensures it is self-sufficient in energy.

Around the world, 200 million people are now supplied with desalinated water. In the long run, this process could benefit 40% of world population living less than a hundred kilometres away from sea.