Biodegradation of tetryl (2,4,6-trinitrophenylmethylnitramine) in a soil-slurry reactor

Abstract

A laboratory study was conducted to determine whether tetryl can be biodegraded by native soil bacteria under soil-slurry conditions with molasses as cosubstrate. A 2-L laboratory reactor was set up with a 15% (weight/volume) slurry of contaminated soil in deionized water. The soil slurry was mixed continuously at 80 r/min. Molasses at 0.3% (volume/volume) was added weekly as a cosubstrate. A no-carbon control reactor was also set up without molasses addition. The concentration of tetryl in the soil was monitored periodically. The results showed 100% removal of tetryl from the soil within 3 months of operation. In the no-carbon control, no significant degradation of tetryl was observed. The gas chromatographic/mass spectrometric analysis of the aqueous phase of the soil slurry showed metabolites identified as trinitro-n-methylaniline, trinitrobenzeneamine, dinitrobenzenediamine, nitroaniline, and aniline. None of these metabolites persisted more than a week after they appeared in the reactor system. The parameters relevant to biodegradation and process control, such as pH, dissolved oxygen, bacterial counts, and metabolites produced in the reactor, are discussed.