[CPEO-MEF] ORNL system eliminates perchlorate, helps scientists trace source

[CPEO <cpeo@cpeo.org>]

Submitted by Susan Gawarecki loc@icx.net


ORNL system eliminates perchlorate, helps scientists trace source

OAK RIDGE, Tenn., Oct. 20, 2004 -- An award-winning system developed at 
Oak Ridge National Laboratory to clean up perchlorate pollution is now 
also helping scientists determine whether the contamination is natural 
or man-made.

This latter application could be instrumental in tracking environmental 
perchlorate, finding its source and resolving resulting liability 
issues, said ORNL scientist Baohua Gu, who headed development of the 
treatment system.

Perchlorate, or ClO4-, disrupts the thyroid gland that regulates 
metabolism in adults and physical development in children and is 
increasingly being found in soil and water. It is used to make solid 
rocket propellant and explosives but also occurs naturally, as in 
nitrate soils from Chile used to make fertilizers, making the source 
sometimes difficult to trace.

Conventional treatments use tiny resin beads to trap the perchlorate, 
but the spent resin becomes contaminated, and disposal is costly or 
impractical.

The ORNL system removes and breaks down perchlorate into harmless 
chloride and water and recharges the resin so it can be reused many 
times.  The process costs up to 80 percent less than conventional 
methods and is one of R&D Magazine's top 100 inventions for 2004.

But Gu and ORNL colleagues Jusuke Horita and Gilbert Brown along with 
others from Louisiana State University, University of Illinois, and USGS 
have found another benefit: the process of removing perchlorate also 
purifies it, allowing the scientists to isolate trace quantities and 
examine the compound more closely than ever before.

Using isotopic analysis, they compared naturally-occurring perchlorate 
from Chile's Atacama Desert to synthetic or manufactured  samples and 
found the natural type had a much higher value of the oxygen-17 isotope 
(an oxygen atom with 8 protons and 9 neutrons in the nucleus) but a 
lower chlorine-37 value (a chlorine atom with 17 protons and 20 neutrons 
in the nucleus).

A report on the study appears in the current edition of Environmental 
Science and Technology, which is published by the American Chemical Society.

"Isotopic comparison of natural and non-naturally occurring perchlorate 
has not been feasible because of the difficulties in extracting and 
analyzing trace quantities of perchlorate from soil or groundwater that 
contain large quantities of impurities like nitrates and other salt 
deposits," Gu said. "Our findings show that the ORNL treatment system 
provides a tool for the identification and forensics of perchlorate 
contamination in the environment."

ORNL has licensed the resin technology to the Purolite company and the 
regeneration and recovery technology to Calgon Carbon Corporation. The 
system also is being tested at two contaminated sites in California. Gu 
will present findings from those tests at meetings this month with 
municipal water utilities and environmental remediation groups in 
California.

The Environmental Protection Agency proposed one part per billion in 
2002 as the legal limit for perchlorate in drinking water, but that 
standard is under debate, Gu said.

"The presence of natural or atmospheric perchlorate in the environment 
obviously has far-reaching ramifications, ranging from public health 
issues to huge liabilities that could be imposed by agricultural and 
environmental cleanup needs," Gu said. "It recently has been found in 
lettuce and milk, which begs the questions: How is it getting there and 
migrating through the environment? Where is the liability?

"Our technology could have a huge impact on how those questions are 
answered."

ORNL is managed by UT-Battelle for the Department of Energy.


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