Bioremediation strategies for Naphthenic acids in Alberta Oil-sands mine Tailings ponds

The province of Alberta, in Canada, has the 4^th most abandon petroleum deposits in the world.  The majority of the oil is in ‘tar-sands’ deposits found close to the earth’s surface, which allows for surface mining.   The process used to release the bitumen (heavy oil) from the sand results in large quantities of a waste product known as tailings, which major fractions are mature fine tailings (MFT), oil sands process water (OSPW), and coke.  The OSPW is collected in tailings ponds, and the water is highly toxic to most organisms. The principle component of this toxicity is a vast group of alkyl-substituted acyclic and cyclo-aliphatic carboxylic acids known as naphthenic acids (NAs). Bioremediation through either anaerobic or aerobic microbial degradation of the NAs is a promising proposed solution to reduce the toxicity of the OSPW prior to environmental release. My research group hypothesized that the difficulties to bioremediation of the NAs may be overcome by the use of selected enriched multispecies community biofilms, which then can be used on traditional support material in a ‘water treatment plant’ style reactor. Using a biofilm-culturing device designed by the Calgary Biofilm research group we successfully cultured a microbial community with NA degrading properties from OSPW and MFT sources.  This community was then cultured on fluidized bioreactor supports and shown to degrade a mixture of NA’s for ex situ remediation.  We then followed this up using biochar as a support material for in situ remediation. The success of mixed species communities versus individual isolates will also be highlighted in this presentation.