Hydrophobic Sand Could Combat Desert Water Shortages

February 16, 2009 by Lisa Zyga weblog
Hydrophobic Sand
Researchers in the United Arab Emirates have developed a new kind of hydrophobic sand that could significantly decrease the amount of water required for plant irrigation in desert regions.

(PhysOrg.com) -- Water scarcity is a major problem for people living in desert areas, including much of the Middle East and Africa. According to the United Nations, more than 1.6 million people die every year due to lack of access to clean water.

Researchers at DIME Hydrophobic Materials, a company in the United Arab Emirates (UAE), along with German scientist Helmut F. Schulze, have developed hydrophobic sand using nanotechnology that could combat desertification and encourage plant growth in arid climates.

As DIME engineer Fahd Mohammad Saeed Hareb explains, their idea is to lay a 10-cm layer of waterproof sand beneath desert topsoil. The hydrophobic sand could serve as a water table to stop water from bleeding downward below the plants' roots. Normally, water quickly trickles down through the sand, requiring that farmers water their plants five or six times per day.

With the new layer of hydrophobic sand, farmers would only need to water their plants once per day, decreasing water use by up to 75 percent. Another benefit of the hydrophobic sand is that it prevents underground salt from passing through the plant roots, which can kill the plants.

The DIME researchers aren't revealing the precise nano coating used for their hydrophobic sand for proprietary reasons, calling the top-secret additive SP-HFS 1609. Other forms of hydrophobic sand are already on the market, which are usually coated with water-repellant silicas and used for cleaning up oil spills and other applications.

DIME's hydrophobic coating has been approved by Germany's Federal Environment Agency (FEA), which has issued the product a no-objection certificate declaring it to be ecologically safe. It takes about 30-45 seconds to coat a sand particle, and DIME's manufacturing facility can produce 3,000 tonnes of sand per day.

Other institutions are investigating the hydrophobic sand, including UAE University. For instance, researchers at the university are conducting tests to see if rice - which is usually grown in water-soaked fields - can be successfully grown in desert conditions. In general, their tests have shown that various plants benefit from the hydrophobic sand, such as by growing healthier roots, but the researchers said the tests are only half complete.

As the population increases and rivers run dry, water scarcity is expected to increase over the next decades in desert regions. In the Middle East and North Africa, 85 percent of the water is used for irrigation, so decreasing this requirement could help meet the urban demand and possibly prevent future humanitarian disasters.

via: Xpress

© 2009 PhysOrg.com

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5 / 5 (1) Feb 16, 2009
Wow, first it's selling refrigerators to Eskimos, now it's selling sand to Bedouins [desert dwellers]?

2.8 / 5 (6) Feb 16, 2009
It sounds somewhat similar to the "Magic Sand" toy which has been around for some time except I doubt that Magic Sand is environmentally tested and guaranteed for many years as this stuff is.

It is a great idea. I had always assumed that most of the water lost in those desert irrigation farms was lost to the air rather than downwards. With underground drip irrigation to reduce evaporation, hydrophobic sand to prevent downward loss and biochar like soils to retain water and nutrients, agriculture in arid regions could be made far more productive and less costly. Since there is already agriculture in these areas, like around desert rivers and where coastal waters are near enough for desalination, they might as well get the most out of every drop.

It would even allow irrigation agriculture in the plains of the Euphrates without repeating the cycle which salted the soil their and ended the regions agricultural based power. Water from irrigation seeped down and raised the water table faster than it could drain until it got close enough to the surface for capillary action and evaporation to take over and suck up salts from the earth, concentrating them at the surface. Keep the water at the surface and this doesn't happen - Babylon becomes an agricultural producer for the region once again.

Just... no capturing anyone this time okay guys?
2.2 / 5 (5) Feb 16, 2009
Oh, and the desert reclamation idea mentioned is an interesting application also. Many areas near deserts get heavy rains on occasion but they run off quickly due to the hard packed soil. Some places south of the Sahara have started digging pits, filling them with mulch and covering them with rocks to reduce evaporation. The rains fill the pits and trees planted around them use the water, further shading the pits. The locals then harvest the nuts or whatever.

Use hydrophobic sand to line these so less water escapes downwards, use trenches instead of pits and you have an orchard, or at least a green belt against desert encroachment.
4 / 5 (1) Feb 16, 2009
What are the advantages of hydrophobic sand over, say, the plastic liner material used for the same purpose beneath ponds?
2.4 / 5 (5) Feb 16, 2009
"What are the advantages of hydrophobic sand over, say, the plastic liner material used for the same purpose beneath ponds?"

Good question.

As I understand it the sand will move around an object which punctures it, maintaining a seal. And air collecting beneath the sand will raise through the sand - liners generally just bubble which can damage them. The company actually markets the stuff as an improvement over plastic liners for such landscaping.

I sound like I am a salesman for the stuff but I'm not. Just intrigued about the possibilities. Their website has some interesting video animations but I recommend turning off the music loop. It gets a tad irritating. http://www.dimecr...ome.html
not rated yet Feb 16, 2009
Sounds like it gives the same effect as a chaparral wildfire.
4 / 5 (3) Feb 16, 2009
Then, let's see. Topsoil is generated. Plants with deeper root structure start to penetrate the supersand -- or perhaps it gets broken up by plows. After a few years of weathering and runnoff, little pieces of supersand start leaving the areas -- and migrating to other areas where they choke normal runnoff, killing all the normal deep-rooted plants. There's no easy way to identify the stuff, or to cull it, so the die-off happens at unpredictable rates, in unpredictable places. The sea floor in certain areas becomes smothered with nanoparticles.

Just because "researchers" developed it for one purpose, doesn't mean, as usual, they have any training to understand the broader impact. Get ready, nature, for something to add to plastics that don't disintegrate, drugs entering the water with every toilet flush, radioactive material that won't go away for thousands of years. Another brilliant invention!!
5 / 5 (1) Feb 16, 2009
Like docknowledge mentions above, what happens to the nano particle coating that only took 45 seconds to put on? As a coating it isn't part of the sand particle and could/will rub or fall off.

We need to step back and learn from our past mistakes with chemical runoff from agricultural spraying and fertilizers.

Could natural minerals with the water-proof properties be made into sand like particles instead? Just because nano particles properties meet your needs doesn't mean you should use it if macro-sized natural substances do the same thing...
not rated yet Feb 17, 2009
Fears about technological innovation and that innovation itself must come together to alleviate each other's objections. I think it is time to use the deserts for more that just an empty lifeless area. Solar desalinizations could be done. Let us be careful no matter what we do and how we do it.
2.5 / 5 (2) Feb 17, 2009
There is a technology that will work alone or synergistically with hydrophobic sand to reduce water loss/use. It was developed by AM Nonomura and AA Benson and published in PNAS in 1992 (Oct. I think). It involves the foliar application of a methanol solution containing a safening agent, e.g. glycine, MSG, or similar amino acid, plus nutrients. In plants UNDER STRESS, i.e. water, hi temperature, and/or excessive light, the combination stops down the stomata and reduces photorespiration. This results in; a very significant reduction (greater than 50%) in the amount of irrigation water required, increased growth rate, and better (at least 50%) crop yields.

Much independent work was done in the 90's to test this technology but a large percentage failed to reproduce the same results. This was clearly due to those authors NOT following the protocol defined in the paper.

The methanol technology has advanced but for regions where all three stressors are present, one or 2 applications of a methanol cocktail during a growing season is a very cost effective way of reducing water requirements while enhancing crop yields and crop quality.
1 / 5 (1) Feb 17, 2009
@weewilly et al
Instead of trying to grow food crops by using hydrophobic sand, methanol or other technologies it might be preferable to use the barren land for growing hydrocarbons in botrycoccus algae. Less water is used than in growing food crops (w/o methanol of course). Growing lipids in other strains of algae is not cost effective at this time.
1 / 5 (3) Sep 02, 2009
The coating on the sand degrades in about fifty years if I remember correctly. In agriculture it would be replaced and in desert greening it would only need to last until topsoil and plants were thick enough to stop surface water from bleeding downward as soon as it soaks in. And since it only works as a water barrier when it is collected together, I don't see how it would choke off anything. Plant roots follow moisture so they would not usually enter the stuff and it is layer down in pakages within a membrane like a flat version of a sand bag. It isn't going to get loose and cover the ocean floor in a mere fifty years.

I don't want this to sound snippy but it seems that a lot of times people assume that any objection they can think of to an innovation must be legitimate and that the creators must never have thought of it or tested for it. It's not like they are blanketing the planet with the stuff before so much as testing it.

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