May 24th, 9:08am 0 comments

Small-Scale, Portable, Low-Power Desalination and Water Purification & New LED Device Sheds Light on Aeroponics Industry

A system that’s worth its salt
New approach to water desalination could lead to small, portable units that could be sent to disaster sites or remote locations.
http://web.mit.edu/newsoffice/2010/desalination-0323.html
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A single unit of the new desalination device, fabricated on a layer of silicone. In the Y-shaped channel (in red), seawater enters from the right, and fresh water leaves through the lower channel at left, while concentrated brine leaves through the upper channel.

[No one will ever die of thirst again at (or near the) sea if they have something like this and a solar panel.]

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One of the leading desalination methods, called reverse osmosis, uses membranes that filter out the salt, but these require strong pumps to maintain the high pressure needed to push the water through the membrane, and are subject to fouling and blockage of the pores in the membrane by salt and contaminants. The new system separates salts and microbes from the water by electrostatically repelling them away from the ion-selective membrane in the system — so the flowing water never needs to pass through a membrane. That should eliminate the need for high pressure and the problems of fouling, the researchers say.

The system works at a microscopic scale, using fabrication methods developed for microfluidics devices — similar to the manufacture of microchips, but using materials such as silicone (synthetic rubber). Each individual device would only process minute amounts of water, but a large number of them — the researchers envision an array with 1,600 units fabricated on an 8-inch-diameter wafer — could produce about 15 liters of water per hour, enough to provide drinking water for several people. The whole unit could be self-contained and driven by gravity — salt water would be poured in at the top, and fresh water and concentrated brine collected from two outlets at the bottom.

That small size could actually be an advantage for some applications, Kim explains. For example, in an emergency situation like Haiti’s earthquake aftermath, the delivery infrastructure to get fresh water to the people who need it was largely lacking, so small, portable units that individuals could carry would have been especially useful.

So far, the researchers have successfully tested a single unit, using seawater they collected from a Massachusetts beach. The water was then deliberately contaminated with small plastic particles, protein and human blood. The unit removed more than 99 percent of the salt and other contaminants. “We clearly demonstrated that we can do it at the unit chip level,” says Kim. The work was primarily funded by a grant from the National Science Foundation, as well as a SMART Innovation Centre grant

While the amount of electricity required by this method is actually slightly more than for present large-scale methods such as reverse osmosis, there is no other method that can produce small-scale desalination with anywhere near this level of efficiency, the researchers say. If properly engineered, the proposed system would only use about as much power as a conventional lightbulb [60W].
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New LED Device Sheds Light on Aeroponics Industry
http://www.environmental-expert.com/resultEachPressRelease.aspx?cid=28518&codi=158711
http://www.aerofarms.com/why/technology/

[Nor will those same people at, or near the, sea or any water source ever go hungry again if they have a desalinator/water purifier, solar panels and LED-lit ‘ponics systems.

And if they are nowhere near any water, but have have humidity > 55% and temp of >70F then all they need is an atmospheric water generator, solar panels and LED-lit ‘ponics systems to still eat well.
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Compiled by SpiralMan
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