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Cheap, simple technique turns seawater into drinking water

  • Many old timers have handled heavy hemp rope. That rope was worse than any sand paper one might buy. I hope hemp toilet tissue does not have that same characteristic. It would be very deep cleaning when the howling stopped. glorybe2
  • uhhhh, the water is still evaporated? This can’t be significantly less energy demanding process than RO?


  • The salts extracted from the brine should be re purposed, e.g. incorporated in building materials, …

    Fretting Freddy the Ferret pressing the Fret

  • The idea that returning minerals, extracted by the process of desalination, to the sea is “pollution” is a no brainer. After all, every cloud that forms has temporarily increased the mineral concentration of the ocean, only for it to be restored when the resulting rain finds its way back again. The same applies to any other water extracted from the sea. Similarly, the notion that the higher boiling point of salt water contributes, significantly, to the energy required for evaporative desalination is also mistaken. The extra two or so degrees at which seawater boils requires less than 0.4% of the energy needed to overcome the latent heat of evaporation. Indeed, this is the main justification for reverse osmosis desalination: that it extracts the minerals without having to provide the energy needed for evaporation.


  • How about an aqueduct with 2 parallel channels or troughs covered with a black A-frame roof running East-West from a salty coastline; the Southern channel is filled with seawater, the sun heats the black roof and evaporates the seawater; the water vapor is cooled by the shaded Northern side and condenses, falling into the Northern trough. A wind or solar powered pump keeps the Southern channel filled to the optimum level with seawater.


  • The use of electric power for heat or pressure is usually far more optional than is implied here. How is vaporization different than boiling? Is sub-atmospheric pressure used? Is “only way” now synonymous with “cheapest way?”

    Bob Stuart

  • Commenters deploring over-pop are just uninformed or witless. The (only) accurate projections are the low fertility ones, and they show a peak at 8bn in about 2045, declining thereafter.

    Brian H

  • recently they found that sea water in an area of the Mediterranean was was being filtered through porous rocks effectively filtering out the salt and surfacing as fresh water. Would it be so difficult to recreate this around the world, let gravity provide the energy to filter out the salt.

    Gavin Roe

  • A lack of fresh water is not a problem but over population and that needs to faced, the sooner the better. If a cheap desalination system is found it will, as Mac MacDougal correctly points out, very quickly be exploited to the hilt: more population, more pollution and further in the red.


  • Desalination is the only answer to the great masses of idiot humans congregating on our coastlines and inter-tidal zones, worldwide, like NYC, LA, London, Tokyo, Hong Kong, Capetown and Rio De Janeiro, as these are now stealing water that we need to feed the rest of our population, if we hope to avoid a very bloody crisis, when nations, and perhaps even States in the USA, will actually go to war over the growing shortage of freshwater, and the food shortages that will come with that. Mac, nothing stops humans from ‘breeding’, you are proof of that! Your argument is totally illogical! If humans are actually the only real problem, as you seem to suggest, then, please, do us all a favor and make yourself one less of us. Better yet, convince a bunch of your brainless political compatriots to check out with you! What makes you think that you have more right to clean air, pure water and the basics of life than the next idiot? We are soon to have 9.5 billion people to sustain on this planet and we are going to need much more pure freshwater to do that. The only alternative is mass murder, in one form, or another! Don, just as saltwater freezes at a lower temperature, it also boils at a higher temp than freshwater, thus requires more energy to distill, which is still the best way to make pure H2O. This also yields a more useful form of saline effluent than RO. For all those concerned about the saline discharge, see the end of this post. I have already solved that problem, years ago. Ezeflyer is right. No energy is more abundant in a desert than solar energy, as there are very few clouds. It is hard to beat the economy of one roll of black polymer film, lining a central dirty/saltwater canal, and one roll of clear plastic film stretched over a peaked frame over that, with each eave of that roof film terminating in another smaller, lined canal, for catching the distilled water, on each side of the dirty water canal. Just 3 plowed furrows, the center one twice as wide as the two outer ones, two rolls of plastic film, one black, one clear, and some sticks or tubing to peak the roof, a few small round pebbles, string and stakes, to tension the roof, and you have a massive solar still! Nothing, however, is more energy efficient than a saline-resistant plant with a deep tap root for desalinating water, as they have their own built in water pump! Plant tamarind and olive trees, hemp and Sunroot, and Buffalo grass, to make the deserts bloom! And, yes, Mishap, hemp paper would be better and cheaper than wood fiber for making the filter membrane. We, then, must make mortar-free inter-locking building blocks for our desert-dwelling populations, from the salt, as there is not sufficient market for it in household use, nor as a nutrient for animal husbandry, tho’ the blocks also serve that latter purpose.


  • I’m afraid I see desalination as a problem, not a solution. If it were confined to emergency situations, I would support it. But I know humans and technology; if large-scale desalination becomes economically feasible, then one great obstacle to overpopulation–and one great restraint on reckless exploitation of existing fresh water resources–will disappear. And then what?

    Mac McDougal

  • The Dead Sea is around 1,400 feet below sea level, highly saline and currently suffering from decreasing in volume and area.

    A hydroelectric system running from the Gulf of Aqaba to the Dead Sea would produce large quantities of energy, much of which could be used for reverse osmosis – a field in which Israel leads the World – so disposal of the salt-enriched brine would not be a problem.

    Unfortunately, that would require the local Arabs to put aside their enmity of Israel, so that scheme is a non-starter.


  • I came up with a similar idea about 12 years ago and was laughed at with claims it would never work. Basically I suggested, filtering the sea water and then distilling it, in the same way they make moonshine. And then filter through carbon filters. I presume there would be a slight salty taste, but that could be removed in the same way a water softener removes it…


  • As previous comments indicated, this article makes no sense at all without more information.

    These filters work how long, separating how much salt and other pollutants?

    What is to be done with the filter material when it is saturated?

    Can it be cleaned? Is there a recommended method of disposal?

    Perhaps all the salt should be returned to the ocean? Perhaps the filter material makes some sort of nutrient for ocean farming? Perhaps if washed with ocean water it can be reused?

    Too many unanswered questions. What is the comparison of CO2 footprint for manufacturing the filter material and its disposal with standard desalination for the same amount of purified water?

    Without these answers, the article is just a bit of sensationalism, devoid of actual meaning.


  • Live aboard sailboats have emergency seawater stills that use sunlight to evaporate pure water from seawater. Pure water condenses on a plastic cover and runs down the sides to be collected. Egypt has plenty of sun.


  • Seems promising. Bedouins used to use dried camel poop for cooking fires, so I suppose the same could be used to evaporate water, though it would need an awful lot of it for today’s populations. Some prairie grasses can provide large quantities of burnable biomass, and can also feed camels, so, some of the water could be diverted to either one, maybe. Salt residue could possibly be packaged and sold as ‘sea-salt,’ rich in trace elements.


  • I don’t understand how a lower concentration of salt makes vaporization easier, and that seems to be the idea.

    I have been searching for a reasonably priced solar still for two, without success. We use filters which cost $500/year. A solar still would be more work, but with a better product if we could find one at a low enough cost to test and discard if it doesn’t work out.

    Don Duncan

  • It is silly to say it is LESS energy without actually providing numbers. It cannot be cleaner unless salt and other pollution have some place to be dumped. Also FIRE is not clean as electric pump.

    Raven Bo

  • So, the brine winds up ON LAND?!? How is that better than mixing it back into the sea? More work needed on this problem.


  • An effective and efficient way to make seawater suitable for our consumption is the challenge of our times. This method shows merit, and we hope for its success further on down the road of development.

    The membrane can be used in very remote situations using fire to vaporize the water.

    Unfortunately, trees aren’t very common in the middle east, so we are still left with the obstacle of energy usage. The filtration concept does show promise though. Finding a way to zap the water without using gobs of energy is the key.


  • If it works with wood fibers then wouldn’t it be even cheaper to use Hemp? It has so many possible uses and it ‘wood’ save more trees. I can’t wait for Hemp toilet paper! LMAO


Source: Cheap, simple technique turns seawater into drinking water

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