US EPA

5068000 

Technical Report 

Use of the Fungus Exophiala lecanii-corni to Degrade a Mixture of VOCs 

Woertz, JR; Kinney, KA 

2000 

GRA and I 

e 2 

Stricter regulations on volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) have increased the demand for more efficient abatement technologies. One promising technology for removing VOCs from polluted gas streams is biofiltration, a process in which contaminated air is passed through a biologically active bed. Although bioreactors containing bacteria have been employed to treat waste streams contaminated with VOCs, they are generally only practical for removing low concentrations of VOCs. In this study, a strain of the dimorphic black yeast Exophiala lecanii-corni, which has been shown to degrade high concentrations of toluene in a bioreactor, was evaluated for its ability to degrade a variety of VOCs, both individually and in mixtures. The fungus was found to be able to use toluene, ethyl benzene, methyl propyl ketone, n-butyl acetate, and ethyl ethoxypropionate as sole sources of carbon and energy; however, E. lecanii-corni was unable to degrade either xylene or benzene. When mixtures of chemicals were added to cultures of E. lecanii-corni, the fungus again degraded all of the chemicals except xylene and benzene. In separate experiments to determine the effects of nitrogen availability and pH on the fungus' degradation ability, it was observed that VOC degradation was inhibited when no supplemental nitrogen was added to the nutrient medium and when the pH of the medium was less than 3. These preliminary studies indicate that E. Lecanii-corni would be a feasible organism to use in biofiltration due to its ability to degrade a wide range of VOCs, even under harsh environmental conditions.