The addition of exogenously supplied hydrogen stimulates PCP reductive
dechlorination and increases bacterial growth. While research focuses mainly on
pure cultures, few exist capable of aryl reductive dechlorination, and few markers
exist to identify reductively dechlorinating bacteria within mixed cultures.
Furthermore, most active bioremediation projects stimulate mixed cultures of native
biota. This work describes a method to estimate reductively dechlorinating bacterial
growth within a mixed soil culture under controlled environmental conditions.
The experiments discussed in this paper were performed in a fed-batch
reactor. The reactor was operated in a way to maintain environmental conditions
such as pH, E[subscript H], headspace concentration, and temperature constant while substrate
is allowed to degrade without the corruption of additional changes. Substrate
utilization and cell growth were examined under an array of environmental
conditions.
This dissertation examined the correlation between hydrogen concentration
and the growth rate of reductively dechlorinating bacteria. Under low hydrogen
partial pressures, between 9.4 x 10������ and 2.9 x 10������ atm, the growth rate of
reductively dechlorinating bacteria increased as predicted by dual Monod kinetics
with respect to hydrogen and chlorophenol concentration; however, studies showed
that the relationship was more complex. At higher concentrations of hydrogen, the
observed growth rate of reductively dechlorinating bacteria declined. A dual Monod
kinetics model with hydrogen substrate inhibition approximates experimental data.
Reductive dechlorination of 2,3,4,5-tetrachlorophenol and 3,4,5-trichlorophenol were also studied. Pentachlorophenol reductive dechlorination
primarily produces 3,4,5-trichlorophenol via 2,3,4,5-tetrachlorophenol. The
reductive dechlorination of 2,3,4,5-tetrachlorophenol parallels that of
pentachlorophenol, and the estimated growth rates based on pentachlorophenol and
2,3,4,5-tetrachlorophenol are very similar. Reductive dechlorination of 3,4,5-trichlorophenol was catalyzed by the PCP reductively dechlorinating bacterial
culture after a lag period. 3,4,5-Trichlorophenol was not maintained for extended
periods, and multiple additions of 3,4,5-trichlorophenol did not result in measurable
growth. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33245 |
| Date | 31 October 2000 |
| Creators | Lotrario, Joseph Bryce |
| Contributors | Woods, Sandra L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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