Microbial Cometabolic Degradation Study Of 2, 4-dinitrotoluene

In this paper, the aerobic biodegradation of 2,4-DNT was investigated using a high effective Gram-positive degrading strain, which was isolated by microbiological culture techniques. The results showed that the degrading bacteria could not use 2,4-DNT as the sole nitrogen source. The optimized conditions for 2,4-DNT degradation were that the temperature was 30℃, pH value was neutral to slightly alkaline and the initial concentration of 2,4-DNT was 50mg/L. The addition of glucose greatly enhanced the biodegradation of 2,4-DNT. The degradation rate could reach 75% when the ratio of the concentration of glucose and 2,4-DNT was 4:1. Particularly, the degradation rate could be increased to 90% by adding 0.6g/L anhydrous ethanol into the substrate. The mechanism analyse showed that the degradation process of 2,4-DNT followed the first order reaction kinetics and could be well described with the Andrews equation even when co-metabolic substrates existed in the medium. The mineralization of 2,4-DNT could reach 53.2%. HPLC analysis found that there were two main intermediate metabolites whose polarity were greater than 2,4-DNT, during the degradation of 2,4-DNT. It suggested that a nitro group might remove from the 2,4-DNT, or the nitro group of 2,4-DNT appeared to convert into other groups. Results from the present study can help to provide a theoretical and experimental basis to biological treatment of 2,4-DNT wasterwater.