Biodegradation of 2,4- and 2,6-diaminotoluene by acclimated bacteria

The degradation of an effluent containing a mixture of 2,4- and 2,6-diaminotoluene (DAT) was studied. Biodegradation was found to occur to a great extent only in the presence of acclimated microorganisms and under aerobic conditions. The amount of biodegradable DAT was highly dependent on the quantity of microorganisms inoculated. Inhibition was observed at high DAT concentrations. A batch activated sludge system, using activated carbon as “synthetic sludge”, was tested in order to improve the degradation yield. Studies on different effluents, containing from 300 to 1600 mg/l DAT, showed that biodegradation percentages were improved over all the studied concentration range using activated carbon, whereas inhibition was lowered at high concentrations. Only one bacterial strain, identified as Pseudomonas aeruginosa which uses DAT as the sole carbon source, was isolated from the crude inoculum. This result suggests that this strain is responsible for the biodegradation observed. As far as the scope of this study is concerned, we noticed that this strain did not use the amino group of DAT as nitrogen source.