Bioremediation of TNT contaminated soil with fungi under laboratory and pilot scale conditions

Abstract

Bioremediation of contaminated soil involves the utilization of innovative technology such as mycoremediation. The capability of fungi to grow in 2,4,6-trinitrotoluene (TNT) contaminated soil, to produce lignin modifying enzymes and to degrade TNT in soil was studied. White-rot fungi, namely Gymnopilus luteofolius, Kuehneromyces mutabilis, and Phanerochaete velutina, were incubated with TNT contaminated non-sterile soil (1000 mg kg−1). All the fungi produced high amounts of manganese peroxidase (MnP) in TNT contaminated soil, but no laccase. The most efficient fungus, P. velutina, degraded 80% of TNT in 2.5 months and was selected for further scale-up experiment with 0.3 t (0.56 m3) of soil and inoculum soil ratio of 1:30. The degradation of TNT was 70% in 49 days, and production of fungal metabolites, namely 4-amino-2,6-diaminotoluene and 2-amino-4,6-diaminotoluene was only 1% of the original TNT concentration. These metabolites were degraded to less than 0.5% during the following 58 days incubation. Fungal remediation process was scaled-up with P. velutina, which tolerated high concentration of TNT and was able to invade the whole mass of soil with only 10 kg of fungal inoculum growing on pine bark. With these parameters the process should be easy to scale-up for soil treatment in field.