Document Type

Thesis

Date of Award

1-31-1992

Degree Name

Master of Science in Environmental Science - (M.S.)

Department

Chemical Engineering, Chemistry and Environmental Science

First Advisor

Piero M. Armenante

Second Advisor

Gordon Lewandowski

Third Advisor

David Kafkewitz

Abstract

The white rot fungus Phanerochaete chrysosporium has been shown in the past to effectively degrade a number of chlorinated aromatic compounds. Previous investigators (Eaton, D. C., "Mineralization of Polychlorinated Biphenyls by Phanerochaete chrysosporium, a Lignolytic Fungus", Enz. Microb. Technol., 7, 194-196 (1985); Bumpus, J. A., Tien, M., Wright, D., and Aust, S. D., "Oxidation of Persistent Environmental Pollutants by White Rot Fungus", Science, 228, 1434-1436 (1985)) have also claimed that this fungus is capable of mineralizing polychlorinated biphenyls (PCBs) in submerged cultures under stationary conditions. Therefore, the objective of this work was to study the biodegradation activity of the fungus in soils contaminated with PCBs. The results obtained so far indicate however that no significant degradation of PCBs in contaminated soil or sand occurs. Several types of experiments were conducted in which different parameters were varied: type of PCBs, amount and type of inoculum, type of solid support matrix, and concentration of some key nutrients. In most of the experiments, the amount of PCB recovered from the soil after the exposure to the fungus was lower than the initial amount. However, the relative concentrations of the PCBs congeners before and after the fungal treatment was the same in both cases. Since biodegradation typically results in the attack on some preferential congeners of the PCB mixture rather than a uniform, across-the-board mineralization, the results obtained so far appear to indicate that the fungus does not biodegrade PCBs. Furthermore, experiments in which the fungus was exposed to soil contaminated with 2,4,6-trichlorophenol (TCP), used as control experiments, showed that, in sand, this compound was degraded, whereas under the same conditions, PCBs would not undergo any degradation at all. In similar experiments conducted in soil, no degradation of PCBs was detected, but it is difficult to determine if degradation of TCP had occurred.

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