Removal of TNT and RDX from water and soil using iron metal

Contaminated water and soil at active or abandoned munitions plants is a serious problem since these compounds pose risks to human health and can be toxic to aquatic and terrestrial life. Our objective was to determine if zero-valent iron (Fe-0) could be used to promote remediation of water and soil contaminated with 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). As little as 1% Fe-0 (w/v) removed 70 mg TNT litre(-1) from aqueous solution within 8 h and removed 32 mg RDX litre(-1) within 96 h. Treating slurries (1:5 soil:water) of highly contaminated soil (5200 mg TNT and 6400 mg RDX kg(-1) soil) from the for mer Nebraska Ordnance Plant (NOP) with 10% Fe-0 (w/w soil) reduced CH3CN-extractable TNT and RDX concentrations below USEPA remediation goals (17.2 mg TNT and 5.8 mg RDX kg(-1)). Sequential treatment of a TNT-contaminated solution (70 mg TNT litre(-1) spiked with C-14-TNT) with Fe-0 (5% w/v) followed by H2O2 (1% v/v) completely destroyed TNT and removed about 94% of the C-14 from solution, 48% of which was mineralized to (CO2)-C-14 within 8 h. Fe-0-treated TNT also was more susceptible to biological mineralization. Our observations indicate that Fe-0 alone, Fe-0 followed by H2O2, or Fe-0 in combination with biotic treatment can be used for effective remediation of munitions-contaminated water and soil. (C) 1997 Elsevier Science Ltd.