Abstract

Bitumen extraction from oil sands has by-products which discharge to tailings ponds. The by-products called tailings, contains residual hydrocarbons. Also, mature fine tailings (MFT) at the bottom of the tailings ponds are exposed to oxygen depletion. Treatment of residual hydrocarbon leads to significant environmental concerns. Many chemical methods are used to degrade the residual hydrocarbons in addition to biodegradation by exogenous microorganisms and biosurfactant production. However, using the indigenous bacteria and the potential of biosurfactant production under anaerobic condition have been neglected. The objective of this research was to select indigenous bacteria with biosurfactant production potential under anaerobic condition and then add them to the MFT simulated environment to monitor bioremediation of the tailings.
At the first phase, 13 oil degrading indigenous bacteria were isolated from mature fine tailings of oil sands refineries under anaerobic condition. The type of 13 isolates were identified and examined to recognize which one of them could live under anaerobic condition. Seven isolates were grown on LB agar plates, 4 isolates on BH agar plates and 2 isolates on TSB agar plates. Biosurfactant production of isolates were monitored under both aerobic and anaerobic conditions. Also, their optical density, surface tension and biosurfactant production were monitored during the incubation. Eight isolated bacteria were facultative anaerobe or aerotolerant anaerobe which 7 of them could produce biosurfactant under anaerobic condition.
At the second phase of the research, MFT environment conditions were simulated in a SRT (with agitation) and anaerobic bottle (no agitation). Seven potential isolated bacteria which could produce biosurfactant under anaerobic condition, were added to the SRT and the anaerobic bottle to monitor the effect of bacteria to the MFT sample for 8 weeks. Results showed that the isolated bacteria degraded approximately 55% of residual hydrocarbon in the MFT and decrease the surface tension of saturated water from 68 mN/m to 45 mN/m under anaerobic condition. The population of bacteria showed satisfactory resistance in the anaerobic environment which indicates that the
iv
identified isolates can be used in the tailings management methods such as microbial enhanced oil recovery (MEOR).