preview

Anaerobic Hydrocarbons Biodegradation in Oil Sands Tailings

INTRODUCTION

Alberta is a major oil and natural gas producer in Canada. In Alberta, it is estimated that the oil sands reserves contain 1.7 trillion barrels of bitumen in place 1. There are four major companies that are currently mining the oil sands in Northern Alberta namely, Syncrude Canada Ltd., Albian Sands Energy Inc., Suncor Energy Inc., and Canadian Natural Resources Ltd. Syncrude Canada Ltd. (from now on will be referred as Syncrude), Suncor Energy Inc. and Canadian Natural Resources Ltd. utilize naphtha as diluent solvent to extract bitumen from the oil sands whereas Albian Sands Energy Inc. (from now on will be referred as Albian) use short n-alkanes or paraffins as solvent diluents to extract the bitumen from the oil sands. The bitumen from the sand are extracted using a warm-water extraction process in Syncrude which processes oil sand together with oil sand slurry (Camp 1977). Bitumen that has been mined are very viscous, so a diluent solvent such as naphtha or other low molecular weight hydrocarbons is required to extract the bitumen from the oil sand slurry 2. The resulting by-products from the extraction processes, which contained a mixture of process water, sand, clays, unrecovered bitumen and diluent solvent, are pumped into settling basins (Camp 1977; MacKinnon 1989). For every 4 m3 of tailing wastes, 1 m3 extraction of oil sands is being produced 3.

The tailings mainly consist of about 45% water and 55% solids (Penner 2006). The unrecovered bitumen accounts for approximately 0.5% of the tailings (Penner 2006). The consolidations of the tailings take place slowly until it reaches 20% solids after which, the densification rate is much slower and take few years to reach 25% to 30% solids (MacKinnon, 1989; Pen...

... middle of paper ...

..., M.D., and Fedorak, P.M. 2005. Naphthenic acids in athabasca oil sands tailings waters are less biodegradable than commercial naphthenic acids. Environ. Sci. Technol. 39(21):8388-8394.

Siddique, T., Fedorak, P.M., and Foght, J.M. 2006. Biodegradation of short-chain n-alkanes in oil sands tailings under methanogenic conditions. Environ. Sci.Technol. 40(17): 5459-5464.

Siddique, T., Fedorak, P.M., Mackinnon, M.D., and Foght, J.M. 2007. Metabolism of BTEX and naphtha compounds to methane in oil sands tailings. Environ. Sci.Technol. 41(7): 2350-2356.

Siddique T, Penner T, Semple K, and Foght JM. 2011. Anaerobic biodegradation of longer-chain n-alkanes coupled to methane production in oil sands tailings. Environ.Sci. Technol. 45(13):5892-5899.

Penner, T. J. 2006. Molecular Analysis of Microbial Populations in Oil Sands Tailings. M.Sc. thesis, University of Alberta.
Get Access