Changing the treatment system using any technology can
influence the quality of the final effluent, so any change in plant
operation must be done by ensuring that there will be no harm to
treatment [8]. For the addition of rhamnolipids in activated sludge
systems to actually be used to reduce biomass generation, it must
be ensured that other factors, in addition to COD removal, are not
adversely affected. For instance, it cannot affect nitrification and
cannot contribute to the final toxicity of the effluent, two major
aspects regarding oil refineries wastewater treatment. In the initial
stage of the study, the main focus was to evaluate the possibility of
rhamnolipids application in order to reduce sludge production.
Thus, other factors will be assessed in a further stage of the study.
Literature has reported some sludge production reduction
technologies that increase the quality of the final effluent. For
example, in a treatment system carried out in three stages,
anaerobic, anoxic and aerobic, sludge heat treatment resulted in
28% sludge disposal reduction through partial solubilization of
cells and increased nitrogen removal because the solubilized cell
material was used as a substrate in the anoxic treatment stage [20].