Environment

Cheap, simple technique turns seawater into drinking water​

Cheap, simple technique turns ...
Researchers in Cairo have invented a cheap, simple way to turn seawater into drinking water
Researchers in Cairo have invented a cheap, simple way to turn seawater into drinking water
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Researchers in Cairo have invented a cheap, simple way to turn seawater into drinking water
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Researchers in Cairo have invented a cheap, simple way to turn seawater into drinking water

Researchersfrom the University of Alexandria have developed a cheaper, simplerand potentially cleaner way to turn seawater into drinking water thanconventional methods.

Thiscould have a huge impact on rural areas of the Middle East and NorthAfrica, where access to clean water is a pressing issue if socialstability and economic development is to improve.

Rightnow, desalinating seawater is the only viable way to provide water togrowing populations, and large desalination plants are now a fact oflife in Egypt and other Middle Eastern countries.

Mostof these plants rely on a multi-step process based on reverseosmosis, which requires expensive infrastructure and large amounts ofelectricity. These plants release large quantities of highlyconcentrated salt water and other pollutants back into the seas andoceans as part of the desalination process, creating problems formarine environments.

That’swhy the race is on to find a cheaper, cleaner and moreenergy-efficient way of desalinating sea water.

Ina paper published last month in the journal, Water Science & Technology, researchers Mona Naim, Mahmoud Elewa, Ahmed El-Shafei and Abeer Moneer announced that they have developed a new way topurify sea water using materials that can be manufactured easily andcheaply in most countries, and a method that does not rely onelectricity.

Thetechnology uses a method of separating liquids and solids calledpervaporation. Pervaporation is a simple, two-step process – thefirst step involves filtering the liquid through a ceramic orpolymeric membrane, while the second step requires vaporizing andcollecting the condensed water. Pervaporation is faster, cleaner andmore energy efficient than conventional methods, not least becausethe heat required for the vaporization stage does not necessarilyhave to be electrically generated.

Pervaporationis not new – it has been in use for many years. But the membraneused in step one has been expensive and complicated to manufacture.

Thebreakthrough in this research is the invention of a newsalt-attracting membrane embedded with cellulose acetate powder foruse in step one of the pervaporation process. Cellulose acetatepowder is a fiber derived from wood pulp and is, according to theresearchers, cheap and easy to make in any laboratory.

Accordingto the paper, the membrane can quickly desalinate highly concentratedseawater and purify even badly contaminated seawater. It can also beused to capture pollutants and salt crystals to minimize pollution ofthe environment. The membrane can be used in very remote situationsusing fire to vaporize the water.

Theresearchers have yet to prove the commercial viability of theproduct, but if they can, it could be a promising alternative fordeveloping countries where water and electricity is a scarceresource.

Source:SciDev

22 comments
mishap
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
owlbeyou
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.
Raven Bo
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.
piperTom
So, the brine winds up ON LAND?!? How is that better than mixing it back into the sea? More work needed on this problem.
Mac McDougal
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?
Catweazle
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.
JohnPilgrim
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...
jjgg38
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.
ezeflyer
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.
Nik
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.