BIOLOGICAL TREATMENT OF TNT-CONTAMINATED SOIL - 1 - ANAEROBIC COMETABOLIC REDUCTION AND INTERACTION OF TNT AND METABOLITES WITH SOIL COMPONENTS

The explosive 2,4,6-trinitrotoluene (TNT), found as a major contaminan t at armament plants from the two world wars, is reduced by a variety of microorganisms when electron donors such as glucose are added. This study shows that the cometabolic reduction of TNT to 2,4,6-triaminoto luene by an undefined anaerobic consortium increased considerably with increasing TNT concentrations and decreased with decreasing concentra tions and feeding rates of glucose. The interactions of TNT and its re duction products with montmorillonitic clay and humic acids were inves tigated in abiotic adsorption experiments and during the microbial red uction of TNT. The results indicate that reduction products of TNT par ticularly hydroxylaminodinitrotoluenes and 2,4,6-triaminotoluene bind irreversibly to soil components, which would prevent or prolong minera lization of the contaminants. Irreversible binding also hinders a furt her spread of the contaminants through soil or leaching into the groun dwater.