Treatment of 2,4-Dinitrotoluene Using a Two-Stage System: Fluidized-Bed Anaerobic Granular Activated Carbon Reactors and Aerobic Activated Sludge Reactors

Continuous-flow anaerobic fluidized-bed granular activated carbon bioreactors were used to treat 2,4-dinitrotoluene (2,4-DNT), a compound used in primary propellant production. A synthetic wastewater solution containing 2,4-DNT, ethanol, mineral ether, and a carbonate buffer and another solution containing growth nutrients and vitamins were fed to each of the two bioreactors. The influent ethanol concentrations were varied to determine the effect of ethanol concentration on the extent of 2,4-DNT degradation. The anaerobic bioreactors, when operated under methanogenic conditions with a primary substrate, were able to transform the 2,4-DNT into 2-amino-4-nitrotoluene (2-A-4-NT), 4-amino-2-nitrotoluene (4-A-2-NT), 2,4-diaminotoluene (2,4-DAT), and trace amounts of toluene. During stable operation, for the range of non-zero influent ethanol concentrations evaluated in this study, the majority of the products were identified as 2,4-DAT. Batch activated sludge reactors were used to examine the fate of 2,4-DAT under aerobic conditions. 2,4-DAT (16 mg/L) were mineralized within 9 hours, indicating that a two-stage system may be an effective 2,4-DNT treatment strategy.