Date of Award

Fall 1992

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering - (Ph.D.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Piero M. Armenante

Second Advisor

Gordon Lewandowski

Third Advisor

Basil Baltzis

Fourth Advisor

Demetri P. Petrides

Fifth Advisor

David Kafkewitz

Abstract

The biodegradation of 2,4,6-trichlorophenol (246-TCP) and 2,4,5-trichiorophenol (245-TCP) by Phanerochaete chrysosporium was studied in batch and in continuous systems. Contrary to most of the previous reports from the literature, this study shows that degradation of both TCPs can occur in the absence of any measurable ligninase activity. The microorganism did not retain its degradative ability for more than about two weeks

In order to better understand the degradation process, the individual contributions of both the biomass and the extracellular proteins were studied separately. The results show that neither the biomass nor the extracellular proteins alone can completely degrade 246-TCP, but both are required for complete degradation to occur. In addition, it was found that the rate of degradation is directly proportional to the concentration of the total extracellular protein produced by the fungus. The extracellular enzyme system (other than ligninase) responsible for degradation has a life time of 32 to 45 hours (depending upon the pH of the system). On the basis of these observations, a reaction scheme for the degradation process is proposed in which 246-TCP is first attacked by an extracellular protein (enzyme) secreted by the fungus, described by a Michaelis-Menten kinetic expression, and then finally degraded by the cell bound protein (enzyme). The kinetic parameters were determined in continuous reactor experiments and successfully tested for other configurations.

Optimal operating parameters were determined for a packed-bed continuous reactor. Degradation of phenol and pentachlorophenol were also studied for comparative purposes.

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