Desalination, de salination

[Michaelangelica]

Another wacky interest of mine.

But living on the second driest continent, already periously short of water, and with another 10 million people on the way in 20 years, (65% more) we need to have a cheap breakthough here soon.

see also salt and water where will is come from in 2050 hypo. threads

also

Solar desalination - Science Links

Centriforce`s Desalination Technology Validated by SGS

MIAMI

--(Business Wire)--

Centriforce Technology Corp. (Pink Sheets:CNFO) announced today that it

completed a performance test coordinated by Industrial Services Division of SGS

North America, Inc., a member of the SGS Group. SGS is recognized as the global

benchmark for testing and certification of new technologies.

 

The performance test showed that Centriforce`s desalination technology was able

to receive normal seawater (35 parts per thousand salt) and transform it to an

almost pure, distilled state (specific gravity of 0.998, conductivity of 456

microS/cm) which may be used for human consumption and other markets that

require potable water.

Centriforce`s Desalination Technology Validated by SGS | Reuters

 

Technology to purify water takes the spotlight and a Jersey twist

MONDAY, 19 OCTOBER 2009 13:18

 

NJIT professor Kamalesh Sirkar honored for his research

 

Using a colander to separate pasta from the water in which it was cooked is a commonplace kitchen experience. But what about the cooking water that usually disappears down the drain? Suppose you had a colander with holes that could not only separate pasta and water, but just as easily remove the salt and starch added to the water in the cooking process - making the water so pure that it would taste great.. . ."

 

The basic principles of membrane separation have been known for a long time. Intestines in animals and humans are semi-permeable membranes, and early experiments to study the process of separation were performed by chemists using samples of animal intestine. However, it wasn't until the early 1960s that the use of membranes for separation applications turned the corner toward practicality when two UCLA researchers fabricated a synthetic membrane from a material similar to plastic.

 

The researchers demonstrated that reverse osmosis achieved with their membrane could reject salt and produce fresh water at a rate sufficient for real-world use.

 

"Today such plants are used in the US," Sirkar said. "But not as much as they could be." He predicted that by 2040, most US water treatment plants will use this technology because of the obvious advantages. "It's a compact technology with relatively low energy consumption that can operate at room temperature for many different applications. It's also a green technology," he said.

 

In Sirkar's NJIT lab, recent groundbreaking work in the field has included a membrane distillation technique that can recover a larger fraction of water from brine than reverse osmosis; a selective protein ultrafiltration method that could rival chromatography as a process for protein purification; and gas permeation membranes that facilitate the separation of carbon dioxide from air by allowing the carbon dioxide to pass through the membrane up to eighteen-thousand times faster than oxygen and nitrogen.

 

— ANDY LAGOMARSINO, NEWJERSEYNEWSROOM.COM

.

http://www.newjerseynewsroom.com/science-updates/technology-to-purify-water-takes-the-spotlight-and-a-jersey-twist

water

membrane

technology

separation

njit

sirkar

membranes

process

applications

work

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carbon

dioxide

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osmosis

researchers

purity

air

protein

reverse

[Michaelangelica]

Saltworks shows off its Thermo-Ionic desalination

 

Saltworks test rig with evaporation pond surrounded by windbreak.

Ben Sparrow and Joshua Zoshi, respectively CEO and president of Saltworks Technologies Inc, showed D&WR a working model of their Thermo-IonicTM desalination system at the recent International Desalination Association World Congress in Dubai.

 

The pair were demonstrating their innovative technology, scaled to a suitcase-sized container, to potential partners in their hotel room.

 

The technology uses salinity gradients and potential differences between three different streams, working off low-temperature energy, such as sunlight or waste heat.

 

The starting point is the concentration of salt water using, say, an open evaporation pond or low-grade heat source, to reach a concentration of 18-20% salt mass. Reject brine can also be used.

 

The main proprietary unit then accepts the concentrated stream and a diluted seawater stream to create an energy transfer while desalinating a third product stream. During passage through the desalting device, the concentrate concentration is decreased while the diluent concentration is increased.

Saltworks shows off its Thermo-Ionic desalination

 

Seawater desalination — SWCC experience and vision

Purchase the full-text article

Mohammad Abdul-Kareem Al-SofiE-mail The Corresponding Author

 

Saline Water Conversion Corporation (SWCC), Research and Development Center (RDC), P.O. Box 8328, Al-Jubail 31951, Saudi Arabia Tel. +966 (3) 361-3713; Fax + 966 (3) 362-1615;

Available online 25 May 2001.

 

Abstract

 

In order to appreciate Mankind's technological advancements, one needs to present a historical overview.

This applies to desalination technology (among all other human developments). Over the millennia, desalination did develop very slowly at the start and then its development started to accelerate. The author has so far traced this technology to as far back as to the third millennium BC. Arabian Peninsula and its surroundings had been the cradle of this, like quite many other, fields of knowledge and technology.

IngentaConnect Seawater desalination - SWCC experience and vision

[JMJones0424]

The main proprietary unit then accepts the concentrated stream and a diluted seawater stream to create an energy transfer

 

This stood out to me as either being something profound, or impossible, but I don't know enough to do more than make an uneducated guess. I can't think of any process that would generate an "energy transfer" without either possibly involving a consumable material (maybe) or bringing the salt concentration of both streams closer to equilibrium (more likely). If the later is the case, then you will be in need of a constant supply of 18-20% salty seawater, which seems like more effort than what you could get from the reaction, unless you have a stream of waste brine from a seawater to freshwater reverse osmosis plant or something similar.

 

Does anyone have any ideas about what processes could be involved? I don't even know where to begin to look.

 

Seawater is on average 3.5% salinity. The only method I know of that doesn't require added energy to concentrate this, evaporation ponds, instead requires huge amounts of land.

 

- intrigued but skeptical

[Michaelangelica]

This stood out to me as either being something profound, or impossible, but I don't know enough to do more than make an uneducated guess.

I can't think of any process that would generate an "energy transfer" without either possibly involving a consumable material (maybe) or bringing the salt concentration of both streams closer to equilibrium (more likely).

I don't understand how the heat transfer in a frig. works let alone the properties of fluids and how to change them.

I have seen that many of the Saudi Arabian de-sal. plants also produce electricity. How is this possible?

 

 

Does anyone have any ideas about what processes could be involved? I don't even know where to begin to look.

I'll look around

[Michaelangelica]

Here are some more links

 

 

. . .

The process begins by spraying seawater into a shallow, black-bottomed pond, where it evaporates, increasing the salt's concentration from 3.5 percent to 20 percent.

 

The concentrated brine (stream 1) is pumped into a desalter along with three other streams (2, 3, 4) of seawater.

Stream 1 is separated from 2 in the desalter by a polystyrene membrane treated to pass only positively charged sodium ions, while 1 is separated from 3 by a membrane selective for negatively charged chloride ions.

The differences in ionic concentrations cause Na-ions in 1 to flow selectively to 2, and Cl-ions to flow from 1 to 3, thus building up their levels in 2 and 3.

Meanwhile, stream 2 is in contact with stream 4 via a Cl-selective membrane, and stream 3 with 4 via a Na-selective membrane.

The higher levels of Na and Cl ions in 2 and 3, respectively, cause them to strip these ions from stream 4, which ends up desalinated, and emerges pure and fresh.

Thermo-ionic desalination system uses solar energy to cut power use by up to 80 percent | Factclipper - Renewable Energy

When you work that lot out please explain it to me!

Current thinking, Oct 29th 2009, The Economist

. . . .

Mr Sparrow and Mr Zoshi, by contrast, reckon they can produce that much fresh water with less than 1 kWh of electricity, and no other paid-for source of power is needed.

 

Their process is fuelled by concentration gradients of salinity between different vessels of brine. These different salinities are brought about by evaporation.

 

The process begins by spraying seawater into a shallow, black-bottomed pond, where it absorbs heat from the atmosphere.

The resulting evaporation increases the concentration of salt in the water from its natural level of 3.5% to as much as 20%. Low-pressure pumps are then used to pipe this concentrated seawater, along with three other streams of untreated seawater, into the desalting unit. As the diagram explains, what Mr Sparrow and Mr Zoshi create by doing this is a type of electrical circuit. Instead of electrons carrying the current, though, it is carried by electrically charged atoms called ions.

Salt is made of two ions: positively charged sodium and negatively charged chloride. These flow in opposite directions around the circuit. Each of the four streams of water is connected to two neighbours by what are known as ion bridges. These are pathways made of polystyrene that has been treated so it will allow the passage of only one sort of ion—either sodium or chloride. Sodium and chloride ions pass out of the concentrated solution to the neighbouring weak ones by diffusion though these bridges (any chemical will diffuse from a high to a low concentration in this way). The trick is that as they do so, they make the low-concentration streams of water electrically charged. The one that is positive, because it has too much sodium, thus draws chloride ions from the stream that is to be purified. Meanwhile, the negative, chloride-rich stream draws in sodium ions. The result is that the fourth stream is stripped of its ions and emerges pure and fresh.

 

It is a simple idea that could be built equally well on a grand scale or as rooftop units the size of refrigerators.

Of course, a lot of clever engineering is involved to make it work, but the low pressure of the pumps needed (in contradistinction to those employed in reverse osmosis) means the brine can be transported through plastic pipes rather than steel ones.

Since brine is corrosive to steel, that is another advantage of Mr Sparrow’s and Mr Zoshi’s technology. Moreover, the only electricity needed is the small amount required to pump the streams of water through the apparatus. All the rest of the energy has come free, via the air, from the sun.

Cheaper desalination: Current thinking | The Economist

[Michaelangelica]

Purifying water

 

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Naomi Fowler reports on a new method of purifying water using sunlight and a catalyst.

 

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Transcript

 

Naomi Fowler: There's no mystery to cleaning up polluted water, we've been doing it for a long time, quite expensively, using UV light. But this system here is quick to build and, because it uses photons from the Sun, it's cheaper to run.

 

Dr Jung: We concentrated on low installation and maintenance costs, of course, because we mainly apply the sun and have much less pump energy, so we save about 90% of the energy. So there, you can have a look at that.

 

Naomi Fowler: Dr Jung is proudly showing me his prototype, six panels that just slot together with rows of clear tubes for the water to run through. It's angled a bit like a sunflower to catch the best of the Sun's rays, even on this cloudy German afternoon.

 

Okay, so tell me how it works.

Purifying water - Science Show - 12 December 2009