Environmental Technology

[Aimee Houghton <aimeeh@igc.org>]

Via the Sierra Club

FOR RELEASE: MONDAY, OCTOBER 17, 1994

 WATER WEEDS: EXPERIMENTAL CLEANUP TOOL

 How to get rid of soil contamination from trinitrotoluene (TNT) wastes at
old munitions sites? Weed it out. That's the promising technique being tested
by the U.S. Environmental Protection Agency's (EPA) Office of Research and
Development (ORD).

 The experimental process developed by scientists from ORD's Athens (Ga.)
Environmental Research Laboratory uses common pond weeds to transform TNT in
contaminated soil into non-hazardous materials through enzyme reactions.

 With support from the interagency Strategic Environmental Research and
Development Program (whose participants include the Departments of Defense and
Energy, and EPA), ORD has moved the process on a fast track from bench study to
pilot-scale field research.

 The plants, which include stonewort, hornwort, and parrot feather, contain
enzymes called nitro-reductase that react with the nitro group on the TNT
molecule. After these enzymes break the compound down into triaminotoluene,
another enzyme called laccase oxidizes the triaminotoluene rapidly into
biodegradable materials.

 In a scaled-up pilot study, researchers created an artificial pond
containing contaminated soil, and added parrot feather to the water. In-situ
remediation at a hazardous waste site would involve the same process on a larger

scale. In the pilot, the treatment successfully reduced saturated TNT levels in

the water from 128 parts per million (the water solubility of TNT under the
conditions of the test) to below the limit at which the compound is detectable
(10 parts per billion) in about three days.

 To identify the right plants for the job, the researchers used a simple
test called an immuno-specific assay. They mashed different types of common
aquatic plants, extracted liquid from each sample, and added the individual
extracts to a clear solution containing an antibody that reacts chemically with
nitro-reductase. The researchers were able to determine which extracts
contained the enzyme by seeing which ones turned the solution blue.

 An EPA patent is pending on the cleanup process, and other scientists are
pursuing further research to apply the technique to treatment of chlorinated
solvents and other organic pollutants.

 (For further information, contact Lee Wolfe, Research Chemist, Athens
Environmental Research Laboratory, ORD, (706)546-3429.)

 ENERGY-EFFICIENCY SEEN IN POSSIBLE CFC ALTERNATIVES

 In Europe, some refrigerator manufacturers have begun to use hydrocarbon
mixtures as coolants to replace chlorofluorocarbons, which have been linked with

stratospheric ozone depletion. In the U.S., interest is growing but
manufacturers and consumers have questions: Do these mixtures perform well? Do

they pose concerns about flammability?

 As part of its ongoing research on potential CFC alternatives (EPA Science
Notes, April 1992), ORD's Air and Energy Engineering Research Laboratory is
addressing these questions. In recent tests, scientists found that two mixtures

of isobutane and propane in refrigerators cooled just as well as the widely used

chlorofluorocarbon CFC-12, and consumed 3 percent less energy. The mixtures
contained, respectively, 60 percent isobutane and 40 percent propane, and 70
percent isobutane and 30 percent propane.

 The laboratory also is assessing whether, with the addition of flame-
suppressing fluoroiodocarbons, the mixtures become less flammable with no
reduction in performance. This research is continuing.

 (For further information, contact Evelyn Baskin, Air and Energy Engineering

Research Laboratory, ORD, (919)541-2429.)

 MEETINGS

November 7-10: Second Annual Health Effects Research Laboratory Symposium:
Chemical Mixtures and Quantitative Risk Assessment, Research Triangle Park, N.C.

(Contact: RSD Conference Coordinator, Health Effects Research Laboratory, U.S.
Environmental Protection Agency, Mail Drop 70, Research Triangle Park, N.C.
27711.)