Biological Treatment of TNT-Contaminated Soil. 1. Anaerobic Cometabolic Reduction and Interaction of TNT and Metabolites with Soil Components

Abstract

The explosive 2,4,6-trinitrotoluene (TNT), found as a major contaminant 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-triaminotoluene by an undefined anaerobic consortium increased considerably with increasing TNT concentrations and decreased with decreasing concentrations and feeding rates of glucose. The interactions of TNT and its reduction products with montmorillonitic clay and humic acids were investigated in abiotic adsorption experiments and during the microbial reduction of TNT. The results indicate that reduction products of TNT particularly hydroxylaminodinitrotoluenes and 2,4,6-triaminotoluene bind irreversibly to soil components, which would prevent or prolong mineralization of the contaminants. Irreversible binding also hinders a further spread of the contaminants through soil or leaching into the groundwater.

Oxidative Transformation of Aminodinitrotoluene Isomers by Multicomponent Dioxygenases

“…1A) via the sequential addition of three electron pairs to reduce a nitro group to a nitroso group, a hydroxylamino group, and finally an amino group (30). Under strictly anaerobic conditions, all three nitro substituents can be reduced to the amine (5,18). In aerobic systems, partially reduced products accumulate.…”

Bioavailability of water-polluting sulfonoaromatic compounds

“…pNBS by strain S-313, Table 1) is presumably a function of the K m values of this particular set of transport and desulfonation enzymes, so given the wide range of desulfonative organisms found in nature (Dudley and Frost 1994;Kertesz et al 1994b;King and Quinn 1997;Seitz and Leadbetter 1995) together with enrichment cultures involving complete substrate disappearance, other organisms have more suitable desulfonative enzymes. 8-Amino-1,5-naphthalenedisulfonate 100 3.4 8-Amino-1,5-naphthalene diol 3-Amino-1,5-naphthalenedisulfonate 100 3.0 3-Amino-1,5-naphthalene diol 6-Amino-1,3-naphthalenedisulfonate 0 0 3-Amino-2,7-naphthalenedisulfonate 100 3.3 3-Amino-2,7-naphthalene diol a This compound had similar retention time to the 2,7-diol b The mass spectrum supported the presence of a diol, and the 2,7-naphthalene diol is proposed, because only direct substitution of the sulfono group with the hydroxy group has been observed in these reactions (Dudley and Frost 1994;Kertesz et al 1994b;ZuÈ rrer et al 1987) We presume that the formation of these phenols (Table 1) in soil could lead not only to degradation, but also to binding to clay and to humic fractions (Daun et al 1998;Thorn et al 1996) and to polymerisation reactions (Bollag et al 1992). The latter is presumably indicated both in the rapid disappearance of 4-nitrophenol (Table 1) and the product(s) from ACT.…”

“…The latter is presumably indicated both in the rapid disappearance of 4-nitrophenol (Table 1) and the product(s) from ACT. We similarly hypothesise that the stable 2-nitrocresol (Table 1) will be immobilised on clay surfaces, humic materials, possibly via polymerisation after reduction of the nitro group (Bollag et al 1992;Daun et al 1998). All the naphthalene derivatives formed by desulfonation (Table 2) are unstable, so we anticipate that they, too, tend to polymerise or bind or sorb to the soil matrix.…”

Standardisation of a Vapour Generator for Calibration of Environmental Monitoring Instruments

“…The mutagenic and carcinogenic potential of TNT and its congeners have been reported and there is need to clean up these from the environment 5 . It has been observed that TNT, present in wastewater in concentration of 25-80 mgll, lowered the oxygen consumption of the bacteria by 5-30 per cent, possibly because it inhibited their activity.…”