Bound Residue Formation in PAH Contaminated Soil Composting Using Phanerochaete Chrysosporium

Authors:
  • XQXiujin Qiu
    Xiujin Qiu
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Abstract
The degradation rate of benzo[a]pyrene (B[a]P), a 5-ring PAH compound, was significantly enhanced in fungal (Phanerochaete chrysosporium) enriched soil composting microcosm reactors over that observed in unamended soil systems. The maximum B[a]P removal rate was 1.1 μg/g-soil-day with fungal inoculation compared to 0.24 μg/g-soil-day without fungal inoculation for a silt loam Kidman soil. Mass balance considerations suggested that the enhanced removal of B[a]P resulted in the formation of bound contaminant carbon residues in soil. A maximum bound residue formation rate of 0.37 μg/g-soil-day was estimated in fungal inoculated microcosms. This was significantly different from the zero rate under natural soil conditions. The observed B[a]P mineralization rates were less affected by fungal activity than was B[a]P removal. Degradation of B[a]P resulted in humification (i.e. polymerization) of most of contaminant carbon rather than conversion to CO2. The fraction of contaminant carbon that was humified compared to that which was mineralized was dependent on soil type. A multi-compartment structural activity model has been developed to illustrate the overall degradation of B[a]P during soil composting.

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