Various authors have investigated the pathways of aromatic amine degradation in pure cultures (Meyer et al. 1979; Nortemann et al. 1986; Haug et al. 1991). However, determination of the degree of degradation in mixed cultures is difficult. An auxiliary substrate is usually added to facilitate anaerobic decolorization, often in concentrations (measured as DOC) very much higher than that of the metabolites. Reduction in the effluent DOC is usually not a reliable indication of metabolite degradation. It is possible to follow the metabolites analytically, e.g. with HPLC; however, some of the metabolites are instable in the presence of oxygen and are not measurable for a longer time as a result of auto-oxidation, although no change in the DOC concentration occurs (Sosath and Libra 1997).
Using the commercial preparation of the RB 5 metabolite p-Base (Fig. 9.7c), Soewondo (1997) showed nearly complete mineralization in aerobic batch experiments. The results could be described using Monod kinetics.
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