Desalination produces more toxic waste than clean water

Marlowe HOOD, AFP Yahoo News 15 Jan 19;

Paris (AFP) - 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".

"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.

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.


Too much salt: water desalination plants harm environment: U.N.
Alister Doyle, Reuters Yahoo News 15 Jan 19;

OSLO (Reuters) - Almost 16,000 desalination plants worldwide produce bigger-than-expected flows of highly salty waste water and toxic chemicals that are damaging the environment, a U.N.-backed study said on Monday.

Desalination plants pump out 142 million cubic meters (5 billion cubic feet) of salty brine every day, 50 percent more than previous estimates, to produce 95 million cubic meters of fresh water, the study said.

About 55 percent of the brine is produced in desalination plants processing seawater in Saudi Arabia, the United Arab Emirates and Qatar, according to the study by the U.N. University's Canadian-based Institute for Water, Environment and Health (UNU-INWEH).

The hyper-salty water is mostly pumped into the sea and, over a year, would be enough to cover the U.S. state of Florida with 30 cms (one foot) of brine, it said of the fast-growing and energy-intensive technology that benefits many arid regions.

Brine, water comprising about five percent salt, often includes toxins such as chlorine and copper used in desalination, it said. By contrast, global sea water is about 3.5 percent salt.

Waste chemicals "accumulate in the environment and can have toxic effects in fish", said Edward Jones, the lead author at UNU-INWEH who also works at Wageningen University in the Netherlands.

Brine can cut levels of oxygen in seawater near desalination plants with "profound impacts" on shellfish, crabs and other creatures on the seabed, leading to "ecological effects observable throughout the food chain", he said.

Vladimir Smakhtin, director of UNU-INWEH, said the study was part of research into how best to secure fresh water for a rising population without harming the environment.

LAKES, RIVERS

"There are all sorts of under-appreciated sources of water," he said, ranging from fog harvesting to aquifers below the seabed. The study also involved the Gwangju Institute of Science and Technology in South Korea.

Brine from desalination plants that tap brackish lakes, aquifers or rivers far inland is harder to treat than brine from coastal plants that can be piped into the seas.

Gurpal Toor, a water quality expert at the University of Maryland who was not involved in the study, said brine "could be a serious issue in a small body of water" like an inland lake.

Brine can be used inland for irrigating salt-tolerant crops, for fish farming or to produce table salt, he said.

Alex Drak, an engineer at IDE Technologies in Israel, a leading water treatment firm, said properly processed brine from coastal plants dissolves quickly in the sea.

"We see a lot of marine life, different types of fish, in the vicinity to the discharge point," said Drak, who was not involved in the UNU study.

(Reporting by Alister Doyle, editing by Ed Osmond)