Bioremediation of TNT‐contaminated soil: A laboratory study

Abstract

AbstractThis research presented a bench‐scale investigation of an innovative approach to land farming for the bioremediation of 2,4,6‐trinitrotoluene (TNT)‐contaminated soils. Molasses, which contains sugar, nitrogen, vitamins, and minerals, was used as cosubstrate and this process combines several advantages of conventional land farming with the use of molasses for the biological degradation of TNT and its derivatives. In the optimum treatment, contaminated soil was amended with shredded grass and managed in an operating cycle where it was alternatively flooded with a dilute molasses solution, then drained, passively aerated, and finally tilled when moisture conditions were optimum. Soil TNT concentrations in all treatments receiving molasses were reduced from approximately 4,000‐mg/kg levels initially to less than 100 mg/kg in 12 months, and to less than 1 mg/kg in the optimum treatment in this same time. Concentrations of the primary metabolic intermediates and bacterial populations were also tracked. Radiolabeling studies confirmed that the biomass enhanced by the treatments could mineralize approximately 20% of [14C] from a contaminant spike after 22 d. A shredded grass amendment in the optimum treatment was shown to increase moisture retention during aeration phases. The results of this bench‐scale study are promising with regard to transferring the process to full‐scale applications.