Microbial degradation of 3,4-dichloroaniline sorbed by activated carbon

The availability of 3,4-dichloroaniline (DCA) sorbed by activated carbon to degradative microorganisms was studied. A Paracoccus denitrificans strain capable of growing on medium with DCA as the sole source of energy, carbon, and nitrogen was used in the experiment. The high sorption capacity of all the carbons studied (powdered RS and SKT-6A and granular AG-3) in relation to DCA (350 to 360, 480 to 520, and 540 to 580 mg/g, respectively) was dem onstrated. The sorptive capacity correlated positively with the specific su rface area and the total volume of the sorbent micropores. The bulk of the DCA was reversibly sorbed and amenable to microbial degradation; however, t he degradation rates significantly differed. When RS, SKT and Agrosorb prel iminarily saturated with DCA were incubated in a culture of P. denitrifican s, the bulk of the reversibly sorbed DCA was decomposed tin the absence of the other carbon sources) in 2, 5, and 10 weeks, respectively, after which the process slowed down. At the end of the experiment (29 weeks), 81 to 87% of the DCA underwent full mineralization, which was accompanied by the rel ease of chlorine ions. A small fi action of the xenobiotic (0.8 to 1.9%) re mained a reversibly sorbed fraction (extractable with acetone) and 12 to 17 % of the initial DCA seemed to have been chemically transformed and bound b y carbon. The studied carbons may be used in biological decontamination of chloroaniline-polluted soils to decrease the toxic effect of chloroanilines on microorganisms.