Application of Anaerobic and Multiple-Electron-Acceptor Bioremediation to Chlorinated Aliphatic Subsurface Contamination
Principal Investigator
G.F. Parkin, University of Iowa
Goal
The goal of this project is to advance understanding of anaerobic and
mixed-electron acceptor bioremediation of chlorinated aliphatics to a level that
full-scale evaluation of these processes is possible. If successful, field-scale
evaluation of technologies developed in this research will be pursued.
Rationale
The U.S. EPA Hazardous Substance Research Centers and national
agencies such as the Department of Defense and Department of Energy have
identified research on remediation processes for chlorinated
aliphatic-contaminated subsurfaces as a high priority. A promising technique is
use of in situ bioremediation, and full-scale evaluations of this process are
ongoing at trichloroethene-contaminated sites. All of these efforts have focused
on use of aerobic bacteria, particularly methanotrophs. However, several of the
chlorinated aliphatics of greatest concern are not degraded by aerobic bacteria.
Unlike aerobic biological processes, anaerobic biotransformations of all
chlorinated aliphatics occur. This lack of specificity, coupled with the fact
that most contaminated aquifers are anaerobic, may make anaerobic bioremediation
an alternative or supplement to aerobic processes.
Approach
This research will focus on three chlorinated aliphatics that
are not degraded by aerobic bacteria: perchloroethene, 1,1,1-trichloroethane, and
carbon tetrachloride. If successful, field-scale evaluation of technologies
developed in this research will be pursued. In order to accurately assess
potential for anaerobic or combined electron acceptor bioremediation technology,
all experimental systems will be operated under conditions similar to those
observed in contaminated aquifers. Additionally, soil cores will be obtained from
contaminated sites as a source of organisms that are indigenous to contaminated
areas. These cultures may be considerably different than those obtained from
anaerobic digesters and may contain organisms particularly suited for chlorinated
aliphatic degradation.
Status
All the necessary equipment has been updated and all experimental
systems are functioning properly. Preliminary kinetic experiments have been
completed and detailed experiments are continuing. Preliminary studies using only
anaerobic biofilm columns have essentially been completed. Aerobic columns have
been attached to anaerobic columns and chlorinated compounds have been fed to
these systems for more than six months. A change in the anticipated funding has
made it uncertain if the investigators will be able to complete studies on
identification of organisms that are able to convert chlorinated aliphatics to
nonobjectionable products or on the effects of nonaqueous phase chlorinated
aliphatics on the extent of degradation and toxicity. This project is in its
third year.
Clients/Users
Results from this research will be of interest to other researchers, U.S.
Environmental Protection Agency, U.S. Department of Defense, U.S. Department of
Energy, and others.
Keywords
Anaerobic, bioremediation, chlorinated aliphatics, mixed-electron acceptor.
Copyright © Georgia Tech Research Corporation, 1998.
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Make comments to: mark.hodges@gtri.gatech.edu
Last modified on: November 6, 1998.
URL: http://www.hsrc.org/
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