UN Warns of Rising Levels of Toxic Brine as Desalination Plants Meet Growing Water Needs


World’s ~16,000 desalination plants discharge 142 million cubic meters of brine daily — 50% more than previously estimated; Enough in a year to cover Florida under a foot (30.5 cm) of brine.

The fast-rising number of desalination plants worldwide — now almost 16,000, with capacity concentrated in the Middle East and North Africa — quench a growing thirst for freshwater but create a salty dilemma as well: how to deal with all the chemical-laden leftover brine.

In a UN-backed paper (“The state of desalination and brine production: A global outlook“), experts estimate the freshwater output capacity of desalination plants at 95 million cubic meters per day — equal to almost half the average flow over Niagara Falls.

For every litre of freshwater output, however, desalination plants produce on average 1.5 litres of brine (though values vary dramatically, depending on the feedwater salinity and desalination technology used, and local conditions). Globally, plants now discharge 142 million cubic meters of hypersaline brine¹ every day (a 50% increase on previous assessments).

That’s enough in a year (51.8 billion cubic meters) to cover Florida under 30.5 cm (1 foot) of brine. The authors, from UN University’s Canadian-based Institute for Water, Environment and Health, Wageningen University, The Netherlands, and the Gwangju Institute of Science and Technology, Republic of Korea, analyzed a newly-updated dataset — the most complete ever compiled — to revise the world’s badly outdated statistics on desalination plants.

And they call for improved brine management strategies to meet a fast-growing challenge, noting predictions of a dramatic rise in the number of desalination plants, and hence the volume of brine produced, worldwide.

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