Desalination produces more toxic waste than clean water

More than 50 billion cubic metres of brine isproduced worldwide every year
More than 50 billion cubic metres of brine is produced worldwide every year

More than 16,000 desalination plants scattered across the globe produce far more toxic sludge than fresh water, according to a first global assessment of the sector's industrial waste, published Monday.

For every litre of fresh water extracted from the sea or brackish waterways, a litre-and-a-half of salty slurry, called brine, is dumped directly back into the ocean or the ground.

The super-salty substance is made even more toxic by the chemicals used in the desalination process, researchers reported in the journal Science of the Total Environment.

Copper and chlorine, for example, are both commonly used.

The amount of brine produced worldwide every year—more than 50 billion cubic metres—is enough to cover the state of Florida, or England and Wales combined, in a 30-centimetre (one-foot) layer of salty slime, they calculated.

"The world produces less desalinated water than brine," co-author Manzoor Qadir, a scientist at the Institute for Water, Environment and Health at United Nations University in Ontario, Canada, told AFP.

"Almost all the brine goes back into the environment, mostly in the ocean."

All that extra salt raises the temperature of coastal waters, and decreases the level of oxygen, which can create "dead zones".

Desalination around the world
Desalination plant production (desalinated water and brine) by region
"It is difficult for aquatic organisms to breathe in these conditions—they need O2 to survive," said Qadir.

More than half of the brine comes from only four countries: Saudi Arabia (22 percent), United Arab Emirates (20.2 percent), Kuwait (6 percent) and Qatar (5.8 percent).

North Africa, the Middle East, and water-starved small island states in the Pacific and elsewhere also rely heavily on desalination to provide safe drinking water, which accounts for nearly two-thirds of consumption.

The rest is used in industry, as a coolant in energy production, and in agriculture.

Around one in four people live in regions where water resources are insufficient during part of the year, and half-a-billion experience water scarcity year round, according to the United Nations.

Water scarcity

Since 2015, the World Economic Forum's annual Global Risk Report has consistently ranked "water crises" as among the global threats—above natural disasters, mass migration and cyber-attacks.

Water scarcity is caused by many things, starting with a global population closing in on eight billion.

More than 90 percent of desalination plants are in wealthy economies
More than 90 percent of desalination plants are in wealthy economies

Major rivers no longer reach the sea, aquifers are being sucked dry, and pollution is tainting water above ground and below.

With climate change, the situation will get worse.

For each degree of global warming, about seven percent of the world's population—half-a-billion people—will have 20 percent less freshwater, according to the Intergovernmental Panel on Climate Change (IPCC).

"Desalination technology has benefited a large number of people," said Qadir. "But we cannot ignore the production of brine, which is going to become an even greater problem in the future."

Industrial-scale technology for removing salt from water has been around since the 1960s. By 1990, there were already 3,000 plants in operation around the globe.

On current trends, the sector will see a total of at least 17,500 plants by 2025, Qadir said, noting that one large plant can produce as much fresh water—and brine—as 200 or 300 small ones.

More than 90 percent of desalination plants are in wealthy economies. This reflects the fact that the technology remains expensive, especially in energy costs.

But it also means that rich nations have the capacity to develop ways to dispose of toxic brine that are less harmful to ocean and land environments, he added.

Some pilot projects have even shown that modified brine can boost yields of certain fish species in aquaculture.


Explore further

UN warns of rising levels of toxic brine as desalination plants meet growing water needs

© 2019 AFP

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Jan 14, 2019
Ship that Sludge to Wild Forests, where More Trees are deemed as a Curse and are causing Wild Fires.

Jan 14, 2019
If they used more solar-still desalination plants then they wouldn't need the extra chemical treatments which carry into the wastewater. And they could produce salt cake, a useful chemical feedstock, if they can find a local market for it.
Brine also contains lithium if they can make an economic extraction.

Jan 14, 2019
A solar still requires enough energy to boil the water, hardly energy efficient, but it might work for small scale requirements.

I'm not a fan of this type of report. It's basically against desalinization which means its a doom and gloom scenario. We're damned if we use desalinization and damned if we don't.

In reality, since the brine is more dense, it hugs the bottom and continues to flow "down hill" until it reaches a depression or it dissipates. Yes we need to be careful about the outflow, but . . .

Jan 15, 2019
A solar still requires enough energy to boil the water, hardly energy efficient, but it might work for small scale requirements.

I'm not a fan of this type of report. It's basically against desalinization which means its a doom and gloom scenario. We're damned if we use desalinization and damned if we don't.

In reality, since the brine is more dense, it hugs the bottom and continues to flow "down hill" until it reaches a depression or it dissipates. Yes we need to be careful about the outflow, but . . .


And so without knowing what effect untold billions of liters of brine will have on whatever ecosystems may or may not exist on the ocean floor that may or may not be important to the rest of life on earth not to mention the oceans in ways we have no idea of even beginning to investigate, you advocate the "dump it out of sight, put it out of mind" approach. Classic.

Jan 15, 2019
Maybe they can put it on a subducting continental shelf. "There, see, it's all gone in 10,000 years!"

Shooting it into the Sun seems too expensive.

Jan 15, 2019
Calling concentrated seawater 'toxic waste' seems a bit dramatic, but I can imagine it really affects an ecosystem. It seems like a simple solution would be to pre-mix this brine with seawater to reduce concentration, and release it over an area instead of in one spot.

Jan 15, 2019
And what actual harm is this release of a bit of saltier water into salty water doing. None actually mentioned amidst the sea of loaded pejoratives.

Jan 15, 2019
Well, exactly the same practice as seen in our love of nuclear power plants.
Researching the salt beds underlying the lithosphere are informative. There is LA here in the US, and under MI. Germany has MILES of salt beds under the country.
There are theories that the Great Pyramid actually funneled energy to the plateau it sits on. One believes water was produced and held. Our past humanity may have coped with excessive water and insufficient water over and over. We refuse to take this at face value.

Jan 15, 2019
And what actual harm is this release of a bit of saltier water into salty water doing. None actually mentioned amidst the sea of loaded pejoratives.


Well, most organisms have a range of saltiness they can tolerate. For instance, freshwater fish cannot live in the ocean, and vice versa. Near the coast there are often variations in salinity, when water evaporates from tidal pools it becomes saltier. This means that species from these tidal pools may have an advantage in the saltier part of the sea, while species not accustomed may die off.

Feb 13, 2019
Piping their hyper-saline outflow ~50 metres from shore, as several plants used to, seems a tad too casual. Running it out to multiple dispersal vents in coastal current zone makes more sense. Feeding it thus to submerged canyon, down, down the continental shelf would be better.

Using the concentrate for industry would be much, much better...

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