Two-stage biotransformation of 2,4,6-trinitrotoluene

TNT is the explosive most widely used by the military, but current technologies for treating munitions production wastewater are costly and produce a secondary waste, spent GAC. Bioremediation holds promise as a more effective and less costly treatment strategy. An anaerobic fluidized-bed granular activated carbon (GAC) bioreactor in series with an activated sludge reactor was used to treat 2,4,6-trinitrotoluene (TNT). A wastewater solution of 100 mg/L 2,4,6-TNT, as well as carbonate buffer and nutrient solutions, were fed to the anaerobic reactor. Ethanol and ammonia were supplied for microbial growth at 540 mg/L and 20 mg/L, respectively. The mixed anaerobic culture completely transformed the TNT to unknown products. Attempts to detect these products by gas chromatography (GC) and high-performance liquid chromatography (HPLC) were unsuccessful. The effluent from this reactor was treated further in an activated sludge system. The TNT transformation products were partially oxidized in the aerobic stage, resulting in recovery of 91% of the total influent nitrogen as ammonia, nitrate, and biomass. This corresponds to recovery of 82% of influent TNT nitrogen.