Canada has the world's largest oil sands reservoirs. Surface mining and subsequent caustic hot water extraction of bitumen lead to an enormous quantity of tailings (volumetric ratio bitumen:water = 9:1). Due to the zero-discharge approach and the persistency of the complex matrix, oil producers are storing oil sands tailings in vast ponds in Northern Alberta. Oil sands tailings are comprised of sand, clay and process-affected water (OSPW). OSPW contains an extremely complex matrix of organic contaminants (e.g., naphthenic acids (NAs), residual bitumen, and polycyclic aromatic hydrocarbons (PAHs)), which has proven to be toxic to a variety of aquatic species. Biodegradation, among a variety of examined methods, is believed to be one of the most cost effective and practical to treat OSPW. A number of studies have been published on the removal of oil sands related contaminants using biodegradation-based practices. This review focuses on the treatment of OSPW using various bioreactors, comparing bioreactor configurations, operating conditions, performance evaluation and microbial community dynamics. Effort is made to identify the governing biotic and abiotic factors in engineered biological systems receiving OSPW. Generally, biofilms and elevated suspended biomass are beneficial to the resilience and degradation performance of a bioreactor. The review therefore suggests that a hybridization of biofilms and membrane technology (to ensure higher suspended microbial biomass) is a more promising option to remove OSPW organic constituents.
Bibliographical noteFunding Information:
The authors acknowledge financial support provided by research grants from the Helmholtz-Alberta Initiative (Theme 5) through the Alberta Environment and Parks' ecoTrust Program, NSERC CRD program, Napier-Reid (Y.L. and M.G.E.D.), and Meidensha Corporation (Y.L. and M.G.E.D.), and funding through an NSERC Industrial Research Chair Program in Oil Sands Tailings Water Treatment (M.G.E.D.) through the support by Syncrude Canada Ltd. , Suncor Energy Inc. , Shell Canada , Canadian Natural Resources Ltd. , Total E&P Canada Ltd., EPCOR Water Services , IOWC Technologies Inc. , Alberta Innovates - Energy and Environment Solution , and Alberta Environment and Parks . The authors would also extend our gratitude to financial support through the Alberta Innovate-Technology Futures (AITF) Graduate Scholarship (J.X.), Dr. Donald R. Stanley Graduate Scholarship (J.X.), the China Scholarship Council (CSC) Award of Excellence (J.X.), the Award of Distinction for Studying-Abroad Students from Xinjiang (J.X.), the postdoctoral fellowship by Natural Sciences and Engineering Research Council of Canada (NSERC) (J.X.), and CSC Scholarship (C.H.).
© 2018 Elsevier B.V.
- Acid extracted fraction
- Microbial community
- Naphthenic acids
- Recalcitrant organic contaminants