Pilot-scale treatment of RDX-contaminated soil with zerovalent iron

S. D. Comfort, P. J. Shea, T. A. Machacek, T. Satapanajaru

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Soils in Technical Area 16 at Los Alamos National Laboratory (LANL) are severely contaminated from past explosives testing and research. Our objective was to conduct laboratory and pilot-scale experiments to determine if zerovalent iron (Fe0) could effectively transform RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) in two LANL soils that differed in physicochemical properties (Soils A and B). Laboratory tests indicated that Soil A was highly alkaline and needed to be acidified [with H2SO 4, Al2(SO4)3, or CH3COOH] before Fe0 could transform RDX. Pilot-scale experiments were performed by mixing Fe0 and contaminated soil (70 kg), and acidifying amendments with a high-speed mixer that was a one-sixth replica of a field-scale unit. Soils were kept unsaturated (soil water content = 0.30-0.34 kg kg-1) and sampled with time (0-120 d). While adding CH 3COOH improved the effectiveness of Fe0 to remove RDX in Soil A (98% destruction), CH3COOH had a negative effect in Soil B. We believe that this difference is a result of high concentrations of organic matter and Ba. Adding CH3COOH to Soil B lowered pH and facilitated Ba release from BaSO4 or BaCO3, which decreased Fe 0 performance by promoting flocculation of humic material on the iron. Despite problems encountered with CH3COOH, pilot-scale treatment of Soil B (12 100 mg RDX kg-1) with Fe0 or Fe0 + Al2(SO4)3 showed high RDX destruction (96-98%). This indicates that RDX-contaminated soil can be remediated at the field scale with Fe0 and soil-specific problems (i.e., alkalinity, high organic matter or Ba) can be overcome by adjustments to the Fe0 treatment.

Original languageEnglish (US)
Pages (from-to)1717-1725
Number of pages9
JournalJournal of Environmental Quality
Volume32
Issue number5
DOIs
StatePublished - 2003

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Management, Monitoring, Policy and Law

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