High-rate biodegradation of 3-and 4-nitroaniline

A municipal wastewater biosludge was acclimated to the degradation of 4-nit roaniline (4-NA). The acclimation was achieved by using this compound as th e sole source of nitrogen during the degradation of succinate as the sole s ource of carbon and energy. The acclimated bacteria were able to eliminate and mineralize 4-NA as the sole source of carbon and energy. However, in ba tch tests, the degradation process was somewhat instable and only occurred at comparatively low rates. A continuously operated miniaturized fixed-bed bioreactor was used in order to increase the degradation rates. It was inoc ulated with the acclimated bacteria and fed with 4-NA as the sole substrate . The system enabled high bioconversion efficiency, due to the development of a high biomass concentration of up to 5.45 g SS L-1. At input concentrat ions of 4-NA up to 4.5 mM and a hydraulic retention time of 3.5 hours a hig h degradation rate of 1.1 mmol 4-NA L-1 h(-1) and 90...95 % DOC removal wer e achieved. Partial nitrification, also occurred. After gradual adaptation, the bacteria also degraded 3-NA and 4-NA simultaneously in this system. Ad ditional batch tests showed, that 3-NA can serve as the sole source of carb on, nitrogen and energy. (C) 1999 Elsevier Science Ltd. All rights reserved .