Removal of petroleum derivative adsorbed to soil by biosurfactant Rufisan produced by Candida lipolytica

There has been a growing interest in the use of biosurfactants to accelerate the transfer of hydrophobic contaminants and subsequent degradation by microbial cells. The aim of the present study was to investigate the applicability of a yeast biosurfactant, denominated Rufisan, which is reported to have excellent surfactant properties (Rufisan is capable of reducing surface tension of the medium to 25.29 mN/m), in the treatment of contaminants from municipal solid waste contained in soils used as slurry barriers. Rufisan has been characterized as nontoxic and biodegradable. Soils with different granulometries were contaminated in the laboratory with motor oil. Oil removal tests were performed in beakers and packed glass columns. The results demonstrated that the crude Rufisan biosurfactant was able to remove approximately 30% of the motor oil from the soils in the static tests performed in glass columns, whereas the isolated biosurfactant at the critical micelle concentration removed 98% of the oil from beakers in the kinetic assays. Soil type and biosurfactant concentration exerted no influence on the oil removal rate, which suggests the displacement mechanism for the release of oil droplets adsorbed to the soil particles. The present findings demonstrate the potential of this biosurfactant as an adjuvant in environmental decontamination processes of petroleum derivates.