Anaerobic/aerobic composting of 2,4,6-trinitrotoluene- contaminated soil in a reactor system
A compost mixture consisting of 50% 2,4,6-trinitrotoluene (TNT)-contaminated soil, 30% chopped sugar beet, and 20% straw was anaerobically percolated for 19 days with tap water. Thereafter, the water was drained off, and the mixture was aerated for 58 days. The anoxic conditions led to the transformation of 90% of the TNT to monoaminodinitrotoluenes and diaminomononitrotoluenes. In addition to well-known reduction products, three substances with identical UV spectra were generated during this phase. They were identified as 4- acetylamino-2-hydroxylamino-6-nitrotoluene (4-N-AcOHANT), 4- formamido-2-amino-6-nitrotoluene (4-N-FAmANT), and 4- acetylamino-2-amino-6-nitrotoluene (4-N-AcANT). The first two metabolites were degraded under aerobic conditions by 100% and 99.6%, respectively, whereas the concentration of 4-N-AcANT increased during the first 15 days of the aeration. Thereafter, the compound was also degraded by 99.6%. In conclusion, an efficient TNT remediation system is presented that led to the identification of three conjugated TNT metabolites.
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