Simulation of biological degradation of aromatic amines in river bed sediments.

Testfilter experiments are reported for river Elbe water spiked with aromatic amines in order to determine biodegradation rates. For river Elbe water the mean degradation rate of DOC (C0 = 6.64 mg l-1) was 26.7 +/- 8.8% after 6.8 days. No significant effect on the DOC degradation rate was observed with the addition of aromatic amines. Large differences in the biodegradation behaviour of the aromatic amines were observed: aniline was eliminated within 3 h, whereas the degradation of 2-nitroaniline was only 40% after 14 h effective contact time. Degradation curves were mostly of a simple logarithmic type, demonstrating first-order kinetics. The degradation rate of 2,4,6-trichloraniline increased by a factor of 20 within 6 weeks due to the adaptation of the testfilter biofilm. A linear relationship between available pKa-values and the logarithm of the experimental degradation rates was found. Thus, the results of the testfilter experiments may be extended to the estimation of the biodegradability of non-tested aromatic amines.