Biologically Mediated Reductive Transformation of Ordnance Related Compounds by Mixed Aquifer Culture Using Acetate as the Sole Carbon Source: Laboratory Treatability Studies for Field Demonstration

Abstract

A series of column studies, with site-specific groundwater and aquifer material, were performed to evaluate the reductive biotransformation potential of different carbon sources (electron donors), and to assess the effects of aquifer temperature and the coexistence of inorganic electron acceptors on biologically induced reductive transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). All the carbon sources (acetate, ethanol, and soluble starch) studied achieved the necessary reducing conditions conducive for RDX biodegradation; however, only the addition of acetate did not exhibit any toxic effects. Lower temperatures significantly reduced the biological activity of an RDX-degrading mixed culture. The first-order biodegradation rate coefficients for RDX at 15, 10, and 5°C were 3.72, 2.35, and 1.46 per day, respectively. The calculated activation energy for RDX was