alternative, still little discussed in literature, and should be studied
in oil refineries. Biosurfactants are molecules with chemical
properties similar to surfactants, frequently obtained by microbial
means. The interest in these substances has increased mainly
because they are considered environmentally compatible, since
they have low toxicity and are biodegradable [9,10]. In wastewater
treatment, biosurfactant can be used to reduce coalescence,
disintegrate biological flakes and allow more cells to have access
to oxygen in aerobic biological processes, thus improving the
treatment efficiency [11]. However, depending on the concentration,
biosurfactants can inhibit cell growth or act as biocides [12].
Studies have shown that rhamnolipid-type biosurfactants have
biocidal and inhibitory effect on algae and may even affect cell
organelles [13]. The effect of biosurfactants as microbial growth
inhibitor or biocide has been very little studied and there are no
reports in literature about their use in wastewater treatment
systems in order to reduce sludge generation by changing
microbial metabolism