Abstract
Environmental pollution caused by petroleum and its derivatives, such as diesel fuel, heavy oil, gasoline, fuel residues, mineral oil and engine oil, is an issue of importance regarding both economic development and ecological restoration. Considerable amounts of petroleum products contaminate groundwater and soil as a consequence of leaks and spills from petroleum refinery processes, oil transportation and storage tanks. While contamination is caused by accidents in some cases, it is often the result of negligent disposal. Biosurfactants have received considerable attention in the field of environmental remediation processes. These substances influence such processes due to their efficacy as dispersion and remediation agents as well as their environmentally friendly characteristics, such as low toxicity and high biodegradability. Thus, this study investigated the potential application of a biosurfactant for enhanced removal capability of motor oil from contaminated sand and water, under laboratory conditions. The biosurfactant was produced by the yeast Candida sphaerica grown in distilled water supplemented with 9% ground nut oil refinery residue and 9% of corn steep liquor, at 28°C during 144h under 200rpm. Bioremediation tests were conducted to examine the effectiveness of the biosurfactant and its isolated microbial producing species in the removal of oil contaminated soil and seawater. The results showed that the presence of the biosurfactant increased the removal rates, acting as an efficient enhancer for hydrocarbon biodegradation.The performance of biosurfactant was excellent, removing 95% of oil at concentration of twice the CMC value. With regard to the removal of oil on seawater, it was observed that removal percentages were around 85%. The biosurfactant was also effective in recovery of up to 80 % motor oil from the walls of beakers and in oil displacement 100% in seawater at twice CMC. These results indicate the potential value of the biosurfactant for application in the oil industry, especially in enhanced oil recovery, tank cleaning and in bioremediation of spills at seas and soils.
