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Problem in a nutshell

Science turns inedible pecan parts into useful filter

An expanded Web version of segments seen on CNN
pecans May 21, 1997
Web posted at: 4:45 p.m. EDT (2045 GMT)

From Correspondent Ann Kellan

(CNN) -- They're used in everything from ice cream to candy, and consumers can't seem to scoop up enough of them. The popularity of pecans is good news to producers and processors, but they would be even happier if there were more ways to use the inedible half of each crop: the shells.

In New Mexico -- the nation's biggest producer of pecans after Georgia and Texas -- people are paying lots of money to get rid of the shells. For example, New Mexico's Sun Diamond Pecan Processing plant produces between 35,000 and 40,000 pounds of pecan shells a day during its peak season.

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CNN's Ann Kellan reports -
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While some of these shells become ground cover along roadways, farms, even in gardens, thousands of pounds of the shells are taking up space in landfills.

Now, researchers at a small lab at New Mexico State University believe they're on the trail of a new and cost-efficient way to use shells -- as an activated carbon filter.


"By treating them chemically and thermally, you can get these materials to absorb certain chemicals out of the water, to remove organics and heavy metals," said David Rockstraw, a researcher at New Mexico State.icon (119K/10 sec. AIFF or WAV sound)

Rockstraw said pecan shells appear to hold several advantages over other activated carbons. They're cheaper to make, because it takes less energy and lower temperatures to grind and convert them into activated carbon. And, when blue dye is poured through the pecan shell charcoal filter, it does a better job of absorbing dyes from water.

David Rockstraw talks about the effect of temperature on pecan shells
movie icon (349K/10 sec. QuickTime movie)

El Paso, Texas-based International Garment Processors, which stone-washes blue jeans for major manufacturers, may be the first to test the new pecan shell charcoal filter.

"Denim is made rigid in the mills so it'll be easier in the sewing factory -- so it won't crumple," said Cesar Viramontes of International Garment.icon (94K/8 sec. AIFF or WAV sound)


But most consumers like to wear softer jeans -- that's why they're stone-washed. Real stones -- pumice, actually -- are used in the wash to give jeans that lived-in look.

But washing blue jeans gobbles up lots of water and dyes the water blue.

"Being in the desert, water is a precious commodity, and our industry is the biggest user in El Paso," said Viramontes. "And most of it goes down the drain, down the sewer, back to the water treatment plants."icon (102K/8 sec. AIFF or WAV sound)

International Garment already uses blue-jean water,water after it's biologically treated in holding ponds, to irrigate its alfalfa and pistachio fields.

But if it can find a cost-effective way to use this pecan-shell filter to take the blue out of blue-jean water, the company could potentially save thousands of dollars and millions of gallons of water a year.

The company is funding a trial run at the plant. If it works, it will prove that the odd coupling of pecan shells and blue jeans is actually a perfect fit.


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