Remediation of Chromium-Contaminated Soils Using Pseudomonas aeruginosa Strain BS2

The bioremediation of chromium-contaminated soil by a rhamnolipid biosurfactant produced by Pseudomonas aeruginosa strain BS2 has been explored through column studies using uncontaminated soil spiked with toxic concentrations of heavy metals i.e. 1000 mg/kg chromium. Results on removal of chromium from the spiked soil by using di-rhamnolipid and tap water have shown a high potential of di-rhamnolipid in mobilization and decontamination of contaminated soil. Within 36 h of the leaching study, di-rhamnolipid facilitated the removal of chromium 10-13-fold compared to tap water. These results indicated that the specificity of this biosurfactant towards chromium was very high and 92% removal of chromium was observed. Hence, di-rhamnolipid selectively favours mobilization of chromium from contaminated soil. Biosurfactant specificity observed towards a specific metal will help the preferential elution of a specific contaminant using di-rhamnolipid. Leachates collected from chromium-spiked soil column treated with di-rhamnolipid solution had a lower pH (6.60-6.78) than leachates from heavy metal-spiked soil column treated with tap water (pH 6.90-7.25), which showed high dissolution of metal species from the spiked soil, and effective leaching of metals. _____________________________________________________________________________________________________________