Lime Treatment of 2,4,6-Trinitrotoluene Contaminated Soils: Proof of Concept Study

Abstract

Many active and formerly used Federal facilities contain areas where surface and subsurface unsaturated zone soils are contaminated with explosives. Currently there is no in situ treatment for stabilization, isolation, or remediation of soils impacted by military operations or manufacturing in support of military operations. The objective of the present work was to evaluate in situ lime treatment of TNT in soil. Bench scale studies were conducted using explosives-contaminated soil to determine the impact of mixing regimes and soil moisture content on TNT degradation using lime treatment. Various amounts of mixing and moisture were applied to replicate systems and analyzed for residual TNT and transformation products over time. Based on observations from the initial study, a follow-on bench scale experiment was conducted to assess the long-term rate and extent of TNT degradation using topical lime application. Results indicated that moderate lime application, consistent with agricultural standards, was sufficient for sustained treatment applications and 25 to 30 percent moisture content optimized TNT degradation kinetics. The present work clearly demonstrated that TNT could be degraded from contaminated soil by treatment with hydroxide ions in aqueous solution and by topical application of commercial grade lime in a static or mixed system. By assessing the effects of parameters critical to successful technology transfer, this effort provides an innovative technique for preventing the migration of surface and near surface soil contamination by TNT, which acts as a source zone for groundwater contamination on DoD testing and training ranges.