REMEDIATING TNT-CONTAMINATED SOIL BY SOIL WASHING AND FENTON OXIDATION

Past disposal practices at munitions production facilities have genera ted numerous hectares of TNT-contaminated soil. We previously showed t hat Fenton oxidation could destroy TNT in soil and water. Our objectiv e was to determine the potential of combining Fenton oxidation with so il washing to remediate TNT-contaminated soil and to test whether plan ts could be established on washed soil. Aqueous soil washing effective ly reduced CH,CN-extractable TNT concentrations but large volumes of w ater were required to meet remediation goals. This volume was reduced when the wash water temperature was increased to 45 degrees C. Complet e destruction of TNT in wash solutions was achieved by Fenton oxidatio n with greater than 40% mineralized. Combining soil washing with phyto remediation will require plant establishment on the washed soil. We ob served no significant reduction in tall fescue (Festuca arundinacea Sc hreb.) germination or early seedling development in contaminated soil following two wash cycles (soil:H2O, 1:5). This corresponded to reduci ng CH3CN-extractable soil concentrations from 499 mg TNT kg(-1) to app roximately 72 mg TNT kg(-1). Our results indicate Fenton oxidation can be combined with soil washing for effective abiotic remediation of TN T-contaminated soils. Washed soils may be planted to tall fescue, demo nstrating the potential of combining soil washing, Fenton oxidation an d phytoremediation into an integrated treatment train for TNT-contamin ated sites. (C) 1997 Elsevier Science B.V.