FATE OF EXPLOSIVES AND THEIR METABOLITES IN BIOSLURRY TREATMENT PROCESSES

Microcosm tests simulating bioslurry reactors with 40% soil content, c ontaining high concentrations of TNT and/or RDX, and spiked with eithe r [C-14]-TNT or [C-14]-RDX were conducted to investigate the fate of e xplosives and their metabolites in bioslurry treatment processes. RDX is recalcitrant to indigenous microorganisms in soil and activated slu dge under aerobic conditions. However, soil indigenous microorganisms alone were able to mineralize 15% of RDX to CO2 under anaerobic condit ion, and supplementation of municipal anaerobic sludge as an exogenous source of microorganisms significantly enhanced the RDX mineralizatio n to 60%. RDX mineralizing activity of microorganisms in soil and slud ge was significantly inhibited by the presence of TNT. TNT mineralizat ion was poor(<2%) and was not markedly improved by the supplement of a erobic or anaerobic sludge. Partitioning studies of [C-14]-TNT in the microcosms revealed that the removal of TNT during the bioslurry proce ss was due mainly to the transformation of TNT and irreversible bindin g of TNT metabolites onto soil matrix. In the case of RDX under anaero bic conditions, a significant portion (35%) of original radioactivity was also incorporated into the biomass and bound to the soil matrix.