In this study, a rhamnolipid biosurfactant-producing strain. Pseudomonas aeruginosa F-2, was used to recover oil from refinery oily sludge in laboratory and pilot-scale experiments. The optimum values of carbon to nitrogen ratio, temperature, sludge-water ratio and inoculum size for oil recovery were determined as 10.35 degrees C, 1:4 and 4%, respectively. An oil recovery of up to 91.5% was obtained with the equipping of draft tubes during the field pilot-scale studies. The results showed that strain F-2 has the potential for industrial applications and may be used in oil recovery from oily sludge. (C) 2012 Elsevier Ltd. All rights reserved.