Remediating TNT-contaminated soil by soil washing and Fenton oxidation

Past disposal practices at munitions production facilities have generated numerous hectares of TNT-contaminated soil. We previously showed that Fenton oxidation could destroy TNT in soil and water. Our objective was to determine the potential of combining Fenton oxidation with soil washing to remediate TNT-contaminated soil and to test whether plants could be established on washed soil. Aqueous soil washing effectively reduced CH3CN-extractable TNT concentrations but large volumes of water were required to meet remediation goals. This volume was reduced when the wash water temperature was increased to 45°C. Complete destruction of TNT in wash solutions was achieved by Fenton oxidation with greater than 40% mineralized. Combining soil washing with phytoremediation will require plant establishment on the washed soil. We observed no significant reduction in tall fescue (Festuca arundinacea Schreb.) germination or early seedling development in contaminated soil following two wash cycles (soil:H2O, 1:5). This corresponded to reducing CH3CN-extractable soil concentrations from 499 mg TNT kg−1 to approximately 72 mg TNT kg−1. Our results indicate Fenton oxidation can be combined with soil washing for effective abiotic remediation of TNT-contaminated soils. Washed soils may be planted to tall fescue, demonstrating the potential of combining soil washing, Fenton oxidation and phytoremediation into an integrated treatment train for TNT-contaminated sites.