REMOVAL OF LEAD AND CHROMIUM FROM SOIL USING BIOSURFACTANTS PRODUCED BY BACTERIAL ISOLATES FROM SPENT LUBRICATING OIL CONTAMINATED SOIL.

Heavy metal removal using direct addition of biosurfactant (Rhamnolipid Bios-40, firmnolipid Bios-30, sulfoglycolipid Bios-25, glycolipopeptide Bios-17 and disulfoglycolipid Bios-12) solutionon heavy metal spiked soils was studied. The heavy metals used were lead and chromium. 500ml of 100ppm of each metal salt solution was applied to 1kg of soil. The remediation potential of the biosurfactants was assessed using atomic absorption spectroscopy (AAS) and changes in pH of the soil after application of the biosurfactants (10mg/ml) to the metal contaminated soil. The results revealed the percentage removal of the metals in the range of 68.05%?95.5% for Lead (Pb) and75.7%?91.0% for Chromium (Cr); Among the biosurfactants used rhamnolipid Bios-40 was most effective with percentage removal of 95.5% and 91.03%, followed by disulfoglycolipid Bios-12 (82.50% and 75.7%) for Pb and Cr respectively. This indicated that the biosurfactants favored mobilization of metals in the order of Pb>Cr. It was further observed that pH of the heavy metal contaminated soil remediated with biosurfactants was low (5.24-6.71 for Pb and 4.57-6.21 for Cr.) as compared to that of unpolluted soil (6.78) indicating high removal of metals from the contaminated soil and effective remediation of metals with the biosurfactants. The results suggest that the biosurfactants are suitable for the remediation of lead and chromium contaminated soil.