Fresh water, increasingly demanded by a growing global population, is becoming increasingly scarce in some parts of the world where the shortfalls are getting worse. For a long time, rainfall, rivers and aquifers have not been sufficient to quench human thirst. More and more water is being treated all over the world: if it is pumped into the sea (61% of the total), in a river or in brackish areas (29%), while the amount of recycled water after use increases. From the Maldives of Singapore, a dozen states use more water from the factory than from any source.
In total, about 95 million cubic meters are desalted daily in 177 countries, mainly for human consumption (62.3%), but also for industry (30.2%), energy and, in the lower part, agriculture . And these volumes are increasing rapidly, thanks in particular to the technological progress made, especially since 2000, which has made the sector less energetic. The reverse osmosis is by far the most used process: it is in 84% of the operating plants that provide 65.5 million meters3 / Day.
Rejected in the environment
But if this bill is falling, the environmental cost follows the opposite trend: the volume of brine loaded with various chemicals is 50% higher than the total amount of desalinated water. The University of the United Nations warns, in a study published Monday, January 14, on the huge amount of material returned to the environment, downloaded directly into the ocean, in particular, or after treatment. There would be enough to cover Florida with a 30.5 cm thick hypersal layer with what is released in a year, notes in its presentation. The importance of these versions is widely underestimated.
The production of 15,900 currently operating desalination plants would amount to 141.5 million cubic meters of brine a day (51.7 billion cubic meters per year), reveals this international team of researchers (Institute for Water, Environment and health of the United Nations University, Canada, Wageningen University, the Netherlands, and Gwangju Institute of Science and Technology, Republic of Korea, whose work is published in the journal Total environmental science (Elsevier, 2019).