Isolation of Biosurfactant-Producing Microorganisms and Their Application to Oily Sludge Remediation under Low Temperature Conditions

A series of laboratory experiments were conducted to isolate and screen bacteria from oil contaminated soil. DCPIP assay tests were applied to identify petroleum hydrocarbon fast degraders, and the qualitative modified drop-collapse tests were used to screen biosurfactant-producing microorganisms when they were inoculated to the medium with different carbon sources. 25 of the isolated strains were scored as potential hydrocarbon fast degraders, and 10 isolates were identified as hydrocarbon fast degraders at low temperature (4 degrees C), while 7 isolates were scored as fast degraders at both room temperature and low temperature. In total, 17 bacterial isolates were identified as biosurfactant-producing microorganisms. The isolated strains were then applied to the remediation of refinery oily sludge with high total petroleum hydrocarbon (TPH) concentrations under cold temperature at 4 degrees C, and approximately 10% enhancement was observed in the treatments inoculated with isolated strains. The results also indicated that the isolated strains could be more effective for degrading the complex long-chain hydrocarbons in oily sludge than commercial biosurfactant rhamnolipids.