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Desalination: no silver bullet

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Desalination plant UN University Institute for Water, Environment and Health

As the world’s driest countries turn to desalination technology to quench their thirst for fresh water, a new environmental problem is growing: what to do with the brine created from treating sea water?


According to a recent report titled, “UN Warns of Rising Levels of Toxic Brine as Desalination Plants Meet Growing Water Needs”, by the UN University Institute for Water, Environment and Health, for every litre of fresh water produced, a desalination plant produces about 1.5 litres of brine.

With nearly 16,000 plants worldwide, primarily in the Middle East and North Africa, the need for water is growing. But even more so is the amount of brine being produced and sent back to the sea untreated.

Fifty-five percent of the world’s brine is produced in just four countries: Saudi Arabia, United Arab Emirates, Kuwait and Qatar, according to research from the report.

Problems from untreated brine

Dumping consistent quantities of untreated brine now poses a new environmental problem.

The report cites major risks to ocean life and marine ecosystems as the salinity of the surrounding water increases.

Edwards Jones, lead author of the paper says high salt content and low dissolved oxygen levels can have “profound impacts on benthic [deep sea level] organisms” which can result in ecological effects seen through the food chain.

Of course, the salinity concentration varies according to the body of water, Jones adds. For example brine dumped back into the Arabian Gulf or the Red Sea has a greater negative impact than in the Pacific Ocean which is a much larger body of water.

With more than half the world's brine coming from four Gulf countries, it’s clear that a different approach is needed in the region.

Economic opportunities

Rather than returning the brine to the sea, Jones says it can be used to create economic opportunities" while minimising the negative environmental impacts – the main purpose of the report.

In an email to RFI, he reiterates potential applications in aquaculture noted in the paper, such as “irrigation of specific (salt-tolerant) crops, and commercial metal/salt recovery”.

But he explains that such technologies are still considered “relatively immature and typically expensive.”

Giulio Boccaletti, chief strategy officer for Water at The Nature Conservancy, says to desalinate one cubic metre of water (1,000 litres) “requires between two and three kilowatt-hours” of energy.

That explains why “desalination alone is so expensive, because [...] a good chunk of the cost to produce desalination is, in fact, the energy used,” Boccaletti tells RFI.

And in many of the countries the cost is funded by fossil fuels.

Better options?

Desalination remains one of, if not the most expensive form of obtaining fresh water, however it remains an “extremely important technology for meeting demand – particularly in countries with limited access to conventional fresh water resources,” says Jones.

“Continued improvements in membrane technologies, energy recovery systems, and coupling desalination plants with renewable energy sources provide opportunities for reducing the amount of energy required for the process – and also reducing the economic costs of desalination,” he adds.

“Desalination is sometimes treated as a silver bullet,” but it is not the case, according to Boccaletti. He says many people assume, once dependence on fossil fuels is removed from equation, that the situation will improve immensely, and green sources, such as the sun, will be able to provide energy for desalination.

But no matter now cheap desalination becomes, Boccaletti says it will never solve the problem of society's massive reliance on water for irrigation and food growth purposes – which counts for around 98 percent of usage.

People must start looking at the overall landscape and alternative means of conserving and harvesting – perhaps through river conservation, or re-using water.

The UN report serves as a reminder that while desalination has helped many countries overcome initial supply problems, it is ultimately unsustainable as a primary source of water.