University of Nebraska, Lincoln, NE, 68583-0915, 402-472-1503
Past disposal practices at munitions production facilities have resulted in numerous acres of soil contaminated with nitroaromatics, particularly 2,4,6-trinitrotoluene (TNT). TNT and its degradates are toxic to biota, and contaminated soils need to be remediated to ensure environmental quality and safety. We previously demonstrated that Fenton oxidation effectively destroyed and mineralized TNT in both pure solution and aqueous extracts of TNT-contaminated soil. Our objectives were to develop practical approaches for remediating TNT-contaminated soils by Fenton oxidation. This was accomplished by proposing three possible remediation schemes. The first considered combining soil washing of TNT-contaminated soils with Fenton oxidation of wash waters. Using this approach, we determined the effects of temperature and humic and fulvic acids on efficiency of TNT removal and destruction. Secondly, we proposed combining soil washing with phytoremediation and determined the phytoxicity of the washed soil to tall fescue (Festuca arundinacea) germination and early development. The third approach considered direct Fenton oxidation of contaminated soil-slurries. Results indicated that aqueous soil washing can effectively reduce CH3CN-extractable TNT concentrations but large H20 volumes are required to meet EPA's remediation goal (17.2 mg TNT kg-1). The volume of H20 required can be reduced if wash water temperature is increased. Fenton oxidation of TNT in contaminated wash water was also demonstrated with greater than 90% mineralization achieved. Addition of humic and fulvic acids to aqueous TNT did not greatly alter the efficiency of destruction and indicates that Fenton oxidation could be effective on a variety of aqueous soil extracts. We also demonstrated that direct Fenton oxidation of soil slurries removed TNT from solution and produced extractable soil concentrations below remediation goals. These results indicate that when Fenton oxidation is combined with soil washing, phytoremediation, or used directly on soil-slurries, it is an effective abiotic remediation treatment for TNT-contaminated soils.
munitions, TNT, Fenton oxidation, remediation
This paper is from the Proceedings of the 10th Annual Conference on Hazardous Waste Research 1995, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.