Trinitrotoluene removal in a soil slurry and soil box systems by an oil-degrading mixed bacterial culture

Bioremediation of trinitrotoluene (TNT)-contaminated soil has proven difficult due to the low bioavailability of the contaminant and its resistance to biocatalytic attack, causing slow rates of biodegradation. We have previously described a mixed bacterial culture acclimated and maintained on crude oil-containing medium that is capable of high rates of TNT biotransformation activity with low production of metabolites. We investigated the ability of this culture to bioremediate TNT-spiked soil and artifically weathered soil slurry systems, as well as a soil box system. The culture was able to remove up to 302 ppm (mg/l) of TNT within 24 h in a spiked-soil slurry system, which is among the highest rates of TNT removal reported to date. The toxicity of artifically weathered TNT-spiked soil to Vibrio scheri decreased over a period of 39 h from a 15-min EC50 of 15.7 to 32.5 ppm. Preliminary results of a soil box system, in which no agitation was used showed similar TNT removal to the soil slurry system, with 100 ppm TNT being removed within 24 h.