Enhanced Biodegradation and Fate of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) and Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine (HMX) in Anaerobic Soil Slurry Bioprocess

Abstract

Enhanced Biodegradation and Fate of Hexahydro-1,3,5-Trinitro-1 ,3,5-Triazine (RDX) and Octahydro-1,3,5,7-Tetranitro-1 ,3,5,7-Tetrazocine (HMX) in Abstract: Native soil microbial populations and unadapted municipal anaerobic sludges were compared for nitramine explosive degradation in microcosm assays under various conditions. Microbial populations from an explosive-contaminated soil were only able to mineralize 12% hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX) (at a concentration of 800 mg/kg slurry) or 4% octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazocine (HMX) (at a concentration of 267 mg/kg slurry). In contrast, municipal anaerobic sludges were able to mineralize them to carbon dioxide, with efficiencies of up to 65%. Reduction of RDX and HMX into their corresponding nitroso-derivatives was notably faster than their mineralization. The biodegradation of HMX was typically delayed by the presence of RDX in the microcosm, confirming RDX is used as an electron acceptor preferentially to HMX. The laboratoryscale bioslurry reactor reproduced the results of the microcosm assays, yet with much higher RDX and HMX degradation rates. A radiolabel-based mass balance in the soil slurry indicated that, besides a significant mineralization to carbon dioxide, 25% and 31% of RDX and HMX, respectively, appeared as acetonitrile-extractable metabolites, while the remaining part was incorporated into biomass and irreversibly bound to the soil matrix. About 10% of the HMX derivatives were estimated to be chemically bound to the soil matrix, while for RDX the estimation was nil.

Mechanism of xanthine oxidase catalyzed biotransformation of HMX under anaerobic conditions

“…HMX and its nitroso-derivatives, i.e., octahydro-1-nitroso-3,5,7-trinitro-1,3,5,7-tetrazocine, octahydro-1,3-dinitroso-5,7-dinitro-1,3,5,7-tetrazocine, octahydro-1,5-dinitroso-3,7-dinitro-1,3,5,7-tetrazocine, octahydro-1,3,5-trinitroso-7-nitro-1,3,5, 7-tetrazocine, and octahydro-1,3,5,7-tetranitroso-1,3,5,7-tetrazocine were analyzed by LC/MS as described previously [10,11].…”

“…Hence there is a need for its safe removal from the contaminated sites. Several reports are available regarding biodegradation of HMX under aerobic [8] and anaerobic [9][10][11] conditions. However, no literature is available so far in regard to the enzymatic biotransformation of HMX.…”

Immobilization of Energetics on Live Fire Ranges (CU-1229). Revision 1.0

“…Stimulation of explosives biodegradation in different environments with molasses has been reported previously by several investigators [14,15,[30][31][32][33][34], so its effectiveness in these studies was not surprising. Potato starch and corn starch also have been observed to stimulate significant RDX biodegradation in anaerobic soil-water slurries under anaerobic conditions [35].…”

“…Based on extensive research that has been done on the biodegradation and biotransformation of explosive compounds by bacteria (for review see refs (14, 18, 21)), fungi (5, 6, 12,32,36,40,46) and plants (8, 16,22,30,45), other approaches for remediating explosive compounds-contaminated soils have been developed.…”

Use of BI-Pb-Sn-Cd Alloy in Self-neutralisation Mechanism for Sub-munitions

“…In recent years, chemical decomposition of deactivating an explosive composition using a chemical have been widely reported, which method comprises exposing the explosive composition to a deactivating agent that renders the explosive composition insensitive to detonation [2][3][4][5][6][7] . Bioremediation of explosives has been reported to be a potential alternative remediation technology for explosives [8][9][10][11][12][13][14][15][16][17][18] .…”