Bioremediation of soil contaminated with explosives in Louisiana Army Ammunition Plant, Minden, Louisiana

Two bioremediation methods, namely, soil slurry reactor and land farming technique were evaluated for the treatment of soil contaminated with explosives in Louisiana Army Ammunition Plant, Minden, Louisiana.   The soil had a high concentration of 2,4,6-trinitrotoluene (TNT) of 10,000 mg/kg of soil and medium level contamination of RDX 1,900 mg/kg and HMX 900 mg/kg of soil.  The results indicated that soil slurry reactor under co-metabolic condition with molasses as co-substrate removed TNT more efficiently than land farming method.  TNT removal efficiency was 99% in soil slurry reactor compared to 82% in land farming after 182 days.  HMX and RDX were also removed from the soil in both methods, but the removal efficiency was low.  The radiolabeled study showed that soil microbes mineralize TNT. The mass-balance of TNT indicated 23.5% of TNT was mineralized to CO₂, 22.6% was converted to biomass, and 52.3% was converted to various TNT intermediates in the soil slurry reactor.  Both methods maintained high bacterial population fairly well.  The results of this bench-scale study are promising with regard to transferring the technology to full-scale application at this site.