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.