Degradation of 3,4-dichloroaniline in synthetic and industrially produced wastewaters by mixed cultures freely suspended and immobilized in a packed-bed reactor.

Abstract

Degradation of 3,4-dichloroaniline (34DCA) in aqueous solution by undefined cultures of free and immobilized cells was examined. Batch cultures of freely suspended cells and continuous degradation in a packed-bed reactor were studied using both synthetically concocted and industrially produced waste-waters. 34DCA was found to be degraded with a concomitant evolution of chloride ions into the bulk medium. The packed bed reactor with biomass immobilized on celite diatomaceous earth was found to be capable of degrading over 98% of the 34DCA present in a synthetically concocted inlet stream at a concentration of 250 mg l-1. Residence times of less than 4 h were employed, giving an overall volumetric degradation rate for the packed bed of 90 mg l-1 h-1. The industrially produced waste-water contained, in addition to 34DCA, aniline, 4-chloroaniline, 2,3-dichloroaniline (23DCA) and 3,4-dichloronitrobenzene. The biomass enriched on the synthetic 34DCA waste-water was found to be capable of degrading these compounds in addition to 34DCA with the exception of 23DCA. 34DCA degradation efficiencies of over 95% were obtained for the industrial waste-water at reactor residence times of 4.6 h, giving volumetric degradation rates of 24 mg l-1 h-1.