Type of Document Master's Thesis Author Das, Swati Jr. Author's Email Address PKSWATI@aol.com URN etd-12498-13011 Title Bioremediation of Pcb Contaminated Surface Soil-a Microcosm Study Degree Master of Science Department Crop and Soil Environmental Sciences Advisory Committee
Advisor Name Title Berry, Duane F. Committee Chair Love, Nancy G. Committee Member Zelazny, Lucian W. Committee Member Keywords
- contaminated surface soil
- methanogenic consortium.
Date of Defense 1997-02-12 Availability unrestricted AbstractBIOREMEDIATION OF PCB CONTAMINATED
SURFACE SOIL - A MICROCOSM STUDY
This feasibility study was performed at Virginia Polytechnic Institute and State University
(Blacksburg, VA) in collaboration with BioSystems Technology, Inc. (Blacksburg, VA). In this
study, degradability of PCBs (Aroclor 1242) from an aged surface soil was evaluated using
serum bottle microcosms containing aceticlastic methanogenic consortium, enriched from a
municipal anaerobic digester. Two different experiments, "intermediate feed" and "starve and
feed" were conducted by manipulating the methanogenic consortium with different amounts of
acetate feeding, during 30 days of incubation. Disappearance of Aroclor 1242 in the microcosms
was quantified using gas chromatography (GC). Significant differences in Aroclor 1242 removal
between inoculated and uninoculated (control) microcosms were observed suggesting that the
methanogenic consortium was responsible for Aroclor 1242 disappearance. However, GC-mass
spectrometry (GC-MS) results could not confirm that disappearance of Aroclor 1242 was due to
anaerobic dehalogenation. From another experiment, it was confirmed that removal of Aroclor
1242 was not due to evaporation losses during sample extraction.
Toxicity of an aged Aroclor 1242 contaminated surface soil was evaluated on an aceticlastic
methanogenic consortium, enriched from a municipal anaerobic digester. Microcosms were set
up using different amounts of soil and inoculum. Total gas production in the microcosms was
monitored during 30 days of incubation, using a glass syringe. Total methane production in the
microcosms was quantitated using GC. Toxicity of the soil on the methanogenic inoculum was
determined based on the decreased rate of methane production in the microcosms relative to non-
soil containing controls. Compared to the control, there was reduction in total methane
production in soil containing microcosms. Between 3-27% reduction in total methane
production was noticed in microcosms containing different amounts of soil and consortium.
Reduction in methane production seemed to increase with increasing amount of soil. Whether
this decrease in methane production was due to toxicity of Aroclor 1242 on the methanogenic
consortium or due possibly to the toxicity of trapped oxygen in the soil could not be determined.
The rate of gas production in the soil microcosm was linear.
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