Environment

MIT tech could let desalination plants use their own brine waste

MIT tech could let desalinatio...
An existing desalination plant in Hamburg, Germany
An existing desalination plant in Hamburg, Germany
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An existing desalination plant in Hamburg, Germany
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An existing desalination plant in Hamburg, Germany
A diagram depicting how the process could be incorporated into a desalination plant
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A diagram depicting how the process could be incorporated into a desalination plant

When salt is removed from seawater in desalination plants, the byproduct is – not surprisingly – a lot of highly-concentrated salty brine. Ordinarily, this is just dumped back into the sea, which can harm the environment. Thanks to a new treatment process, however, that brine could actually be used to desalinate more water.

Developed by a research team at MIT, the proprietary system incorporates what are described as "well-known and standard chemical processes." These include a nanofiltration process to initially remove unwanted compounds from the brine, followed by one or more stages of electrodialysis. As a result, the brine is converted into useful chemicals such as sodium hydroxide.

More commonly known as caustic soda, sodium hydroxide is often utilized to change the acidity of seawater entering desalination plants, which in turn helps to prevent fouling of the filtration membranes that are used to remove the salt. Ordinarily, plant operators have to buy the chemical. With the MIT system, though, they would be able to produce even more than they need, on-site. The excess could then be sold for use in other applications.

Other chemicals that could be produced from the brine include hydrochloric acid, sales of which would likewise be a source of revenue. And as an added bonus, the scientists suggest that plants could save money by no longer needing to pump their brine out into the ocean.

Plans now call for the technology to be trialled and refined in a prototype desalination plant, with an eye toward ultimately reducing the system's equipment costs and power requirements.

A paper on the research was recently published in the journal Nature Catalysis.

Source: MIT

5 comments
fb36
Imagine a future that, there is no drought, water shortage anywhere in the world, anymore! Because, ocean water desalinated @ massive scales/amounts & pumped everywhere needed (using a global pipeline network)! (This would also mean any deserts can be turned to agricultural fields or forests!) (For that future, fusion power would be needed, for sure, because electricity produced from solar & wind would never be enough!)
highlandboy
There is no free lunch. Just as desalination plants require massive amounts of electricity, so this process to turn NaCl + H2O into NaOH + HCl will require large amounts of power. OK if all the power is from cheep renewable sources, but otherwise an expensive option.
Douglas Bennett Rogers
A cool Earth is characterized by desert, be it ice or sand. Hot sand is the main way of transferring heat to space. Plants trap infrared as heat of vaporization. Photovoltaics are very inefficient and thermalize large amounts of solar radiation. Space based solar could reject most of the waste heat in space. In the near term, fuel cells, especially stationary one, could retain all of the carbon and water exhaust. Working fusion, or even fusion-fission reactors would grossly change the landscape.
EZ
Call me nuts but I believe the technology is already here--but hidden by black budget project controllers. It was know by Tesla and other scientists but snatched up by the "Elite" (those with the money) and locked away forever so we have to burn oil and destroy our environment. As Ben Rich said in his famous speech, "We have the technology to send ET home. . . but you'll never see it. . . it would take an 'Act of God' to make it available to the public." Some paraphrasing but accurate in meaning.
Observer101
Two things... One is that the "brine concentrate" could be sold to states, counties and cities to be used for "salting the roadways" or pre-treating the roads before storms...Who knows, maybe someday they can install large "sprinklers" along major highways, to salt the roads before, during and after storms, eliminating the need for trucks to carry and dispense the brine.... Second, why not utilize the SOLAR/SALT storage plants to "power the desalination and conversion plants? It's my understanding that these large systems can generate massive amounts of heat and energy...