Title page for ETD etd-12498-13011

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
  • PCBs
  • bioremediation
  • contaminated surface soil
  • methanogenic consortium.
Date of Defense 1997-02-12
Availability unrestricted



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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