A pilot scale demonstration of a biological permeable barrier was conducted in a pentachlorophenol-contaminated aquifer at a wood preserving facility. A permeable reactor was constructed to fit within a
large diameter well. Arranged in series, a cylindrical reactor 24" x 36" (0.61 x 0.91m) (diameter x height)
was partitioned to provide three biological treatment zones. Pentachlorophenol (PCP) biodegradation was
evaluated under several environmental conditions using a mixed microbial consortium supported on
ceramic saddles. Imitation vanilla flavoring (IVF), a mixture of propylene glycol, guaiacol, ethyl vanillin
and sodium benzoate, served as the electron donor. In the absence of exogenous substrate, PCP was not
degraded in the inoculated permeable barrier. Substrate addition under oxidizing conditions also failed to
initiate PCP removal. Anaerobic conditions however, promoted in-situ PCP degradation. PCP reductive
dechlorination resulted in the transient production of 3,4,5-trichlorophenol through sequential ortho
dechlorinations. Continued carbon reduction at the meta and para positions resulted in 3,4-dichlorophenol
and 3,5-dichlorophenol production. Complete removal of all intermediate degradation products was
observed. Reactor operation was characterized through two independent laboratory and field companion
studies. Experiments were conducted to evaluate (1) the effect of supplemental electron donor
concentration (IVF) and (2) the effect of sulfate, a competitive electron acceptor on PCP reductive
dechlorination. Results from laboratory and field conditions were consistent. (1) In the presence of an
exogenous electron donor, PCP degradation was independent of supplemental donor concentration (10, 25,
50, 100 mg COD/L). However, a comparatively slower rate of PCP degradation was observed in the
absence of electron donor. (2) The presence of sulfate was not inhibitory to PCP degradation. However,
compared to systems evaluated in the absence of sulfate, slower rates of PCP transformation were
observed. Passive operation and low energy requirements, coupled with potential contaminant
mineralization suggest that the biological permeable barrier is a highly effective tool for subsurface
restoration. / Graduation date: 2000
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33489 |
| Date | 05 May 2000 |
| Creators | Cole, Jason David |
| Contributors | Woods, Sandra L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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