Abstract

Abstract

Discovery of New Oil-Degrading Bacteria with Biosurfactant Production Ability from Oily Tailings Pond Waste, Refinery-Contaminated Soil, Light and Heavy Crude Oils for Remediation of Crude Oil in Water

Mohammad Rahimi, M.A.Sc.
Concordia University, 2019

Contamination of water and soil with crude oil and petroleum compounds frequently occurs. Removal of oil contamination is often not economically feasible by traditional remediation techniques. Therefore, the development of effective, fast, and bio-based remediation methods that can lessen the damaging effects of oil contamination and lower treatment costs are of great importance. Numerous oil-degrading bacteria with biosurfactant production ability have been isolated from oil-related environments. However, less attention has been given to the application of these compounds in the oil-related activities. The objectives of this study were to discover potential oil-degrading bacteria with biosurfactant (BS) production ability with potential application for crude oil bioremediation from oily tailings pond waste, refinery-contaminated soil, light and heavy crude oils by using the enrichment culture technique. The biodegradation tests were conducted in Erlenmeyer flasks containing water (350 mL, pH 7, salinity of 30 ppt) amended with nutrients and crude oil as the only carbon source (2 mL). The contribution of discovered oil-degrading bacteria in the crude oil biodegradation was determined at different periods of biodegradation by analysis of the remaining of total petroleum hydrocarbons using a gas chromatograph (GC-FID). Moreover, the production and properties of produced biosurfactants were assessed through surface tension (ST) and oil-displacement tests. A total of five oil-degrading bacteria species were discovered from oily tailings pond waste (1 species), refinery-contaminated soil (two species), light crude oil (one species) and heavy crude oil (one species). All species showed biosurfactant production ability. The lowest surface tensions of supernatants at the end of the biodegradation period were between 55 mN/m to 40 mN/m. The minimum ST belonged to the BS produced by species discovered from oily tailings pond waste (40 mN/m). Moreover, an average crude oil biodegradation of 70% was obtained with the isolated bacteria from samples following five weeks of incubation. This study confirmed the fast and effective biodegradation of crude oil by the isolated bacteria with the biosurfactant production as the main mechanism of oil uptake.