RDX degradation using an integrated Fe(0)-microbial treatment approach

RDX is a persistent and highly mobile groundwater contaminant that represen ts a major remediation challenge at numerous munitions manufacturing and lo ad-assemblage-package facilities. This work presents proof of concept that permeable reactive iron barriers might be a viable approach to intercept an d degrade RDX plumes. Specifically, RDX was rapidly reduced in aquifier mic rocosms amended with Fe(0) powder, and in flow-through columns packed with steel wool. The rate and extent of RDX degradation in microcosms was enhanc ed by anaerobic bacteria that feed on cathodic hydrogen (i.e., H-2 produced during anaerobic Fe(0) corrosion by water). Apparently, the hydrogenotroph ic consortium that exploits Fe(0) corrosion as a metabolic niche participat ed in the further degradation of heterocyclic intermediates produced by the reaction of RDX with Fe(0). Reductive treatment of RDX with Fe(0) also red uced its toxicity to microorganisms and enhanced its subsequent biodegradab ility under either anaerobic or anaerobic conditions. Therefore, a combined or sequential Fe(0)-biological treatment approach mig ht improve treatment efficiency.