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

Graduation date: 1994

Chlorine has been used extensively as an industrial compound for synthesis of innumerable commercial product, including bleaches, organic diluents, adhesives, dust reducing agents, cutting oils, disinfectants, and monomers for plastics, pharmaceuticals, and pesticides. Despite societal contribution of chlorinated chemicals, there have recent suggestion by some environmental associations and scientists to ban the industrial use of chlorine. After their release into environment, organochlorine pollutants are stable and resistant to chemical and biodegradation and preferentially accumulation in the sequence food chain. / As a detoxification hydrodechlorination (HDC) reactions change neither the thermodynamics of the reaction nor the equilibrium composition. Also, there is no possibility of producing hazard by-product such as polychlorodibenzodioxins and polychlorodibenzofuran. / Liquid phase hydrodechlorination of 4-chlorophenols was studied over the temperature range from room temperature (R.T) to 80°C using various Nickel catalysts and active hydrogen sources. Raney Nickel system converted 4-chlorophenol to ~49 mol% of phenol and ~34 mol% cyclohexanol at R.T. and proved to be more reactive than Ni0 and Ni-Fe. The HDC system with borohydrides as hydrogen source achieved hydrodechlorination at lower temperature than the system with molecular hydrogen. Ni-Al proved to be reactive for hydrogenolysis in the presence of borohydride at R.T. A somewhat surprising temperature dependence of Ni-Al mediated HDC in absence of H2 and borohydride was absented. Optimization with Ni-Al under mild condition was performed using central composite design (CCD). Optimal condition for maximum phenol production was predicted to be 80°C, for 11 h with 30 mg of catalyst. 98 mol% phenol is produced under this condition. / A continuous stream of pentachlorophenol (PCP, 0.5 mg/min) in mixture of supercritical carbon dioxide (scCO2) and hydrogen was hydrodechlorinated by a heated column of gamma-alumina supported palladium (5 % w/w). Dechlorination efficiencies and time to reach equilibrium were influenced appreciable by the temperature and substrate delivery rate. The product from reaction at 210°C, 2000 psi accounted for 92 mol% phenol and 2.3 mol% cyclohexanone. The temperature was maintained at 210°C while the pressure and content of H2 in the gas mixture was changed to 1000 ~ 2000 psi, 5 % and 16 % (v/v) H2/CO2. The production of phenol and cyclohexanone was greater at higher pressures (2000 psi.) with the formation of methoxy-cyclohexane. The content of H2 in the gas mixture was not appreciable influenced the product distribution.

Thesis (Ph. D.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 145-150). Also available via the World Wide Web.

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Graduation date: 1999

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Thesis (M.S.)--University of Michigan, 1973.

Thesis (M.S.)--University of Michigan, 1973.