REMEDIATION OF PETROLEUM IMPACTED SOILS IN FUNGAL COMPOST BIOREACTORS

The ability of the white rot fungus Phanerochaete chrysosporium to enhance the biotransformation of benzo(a)pyrene (B(a)P) in contaminated soils was evaluated in compost bioreactors. RadiolabelledC-14 and chemical mass balances were used to evaluate: 1) rate of disappearance of test compound; 2) mineralization; 3) formation of bound contaminant residue; and 4) treatment costs. Mineralization of B(a)P was found to be insignificant over the duration of test period. Moreover, no radioactivity was recovered in volatile organic traps indicating that transformation of B(a)P resulted in chemicals intermediates that remained associated witfi the compost matrix. Bound contaminant residue formation was found to be the major mechanism of B(a)P removal accounting for nearly 100% of the contaminant loss from the solvent extract (methylene chloride/acetone). A maximum rate of bound contaminant removal of 1.36 mg B(a)P/Kg soil-day was estimated in fungal inoculated system over the first thirty days of treatment. This was significantly different from the maximum rate of bound residue formation estimated in the noninoculated systems (0.83 mg B(a)P/Kg soil-day) over the same time period. After thirty days, the rate of bound residue formation decreased to near zero in the inoculated system while remaining constant in the noninoculated reactors. The decrease in bound residue formation coincided with decline in benzo(a)pyrene removal. Data suggest that fungal activity may have been reduced over time by nutrient limitation.