3.1. Reactor operating principal
The method for the purification of simulated wastewater
was developed on the basis of research on the cleavage of
N=N bonds under microeraphilic condition followed by aerobic
mineralization of simulated wastewater. Haug et al. [26]
have worked on anoxic cleavage and aerobic mineralization
of sulphonated azo dyes Mordent Yellow 3 by a bacterial
consortium. The principle of switching between anaerobic
and aerobic conditions in a bioreactor was used for the treatment
of concentrated reactive dye and the sequence of degradation
of dye molecules during the microaerophlie-aerobic
process is presented in Fig. 3. Accordingly, an investigation
has been made on laboratory scale reactors for decolorization
and degradation of simulated wastewater. Initially the
reactor was loaded several times with fresh media until suffi-
cient growth was achieved. Variation in COD concentration
was determined during the course of experiments. The color
removal efficiency increases with time, indicating that the
reactor was becoming sufficiently mature to decolorize and
degrade the wastewater. Starch was selected as co-substrate
for providing the electrons for the reduction of the wastewater.