Several solid support media are used to attach biofilms in
bioreactors, such as sand, diatomaceous earth, activated carbon,
polyurethane foam and glass. Specially, the presence of
powdered activated carbon (PAC) in the biological treatment
of organic toxic pollutants increases the removal rate. Several
mechanisms have been suggested in these processes, for example,
stimulation of biological activity and bioregeneration of
activated carbon [17e23]. However, a deeper knowledge regarding
the role of solid media on biodegradation of recalcitrant
organic toxics is required.
The objectives of this work are to investigate the effect of
solid media, kaolin, bentonite and activated carbon on a monoazo
dye (Acid Orange 7) biodegradation by three different
bacteria under aerobic conditions and to study the kinetics
and mechanism of the decolorization process. Bacteria will
be inoculated on the solid surface and dye concentration will
be followed in the course of time. Special attention will be
paid to the properties of the solids used for fixation of bacteria.
The azo dye selected for the study was Acid Orange 7 (CI
15510), widely used in textile factories and degraded by these
microorganisms in previous experiments.