Problem in a nutshell
Science turns inedible pecan parts into useful filter
May 21, 1997
An expanded Web version of segments seen on CNN
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.
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
"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. (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
(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. (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
"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." (102K/8 sec. AIFF or WAV sound)
International Garment already uses blue-jean 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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