Résumé - Abstract:

The management of oil sands tailings has been an ongoing challenge for many years largely due to the presence of fine clay and silt particles in the tailings. These fine particles pose a significant challenge to End Pit Lakes (EPLs), which are expected to be a widely used method of reclaiming oil sands tailings, as surface water turbidity may be detrimental to the development of aquatic ecosystems in EPLs. Laboratory mixing experiments were conducted to investigate the effect of biofilms made up of microbial communities indigenous to tailings on reducing turbidity in EPLs. The impact of biofilm age (10 weeks versus 20 weeks old) on turbidity mitigation was also evaluated. Biofilms were characterized by chlorophyll a extractions, live and dead staining, scanning electron microscopy (SEM), and DNA sequencing. Biofilms formed on the mudline between the tailings and water cap reduced turbidity in the water cap by over 99%, depending on biofilm age and mixing speed. Gas production and lifting resulted in weaker attachment of older biofilms to the mudline and as such, younger biofilms performed better than older biofilms. However, older biofilms still reduced turbidity by 73 to 95%, depending on the mixing speed. These promising findings will inform planning and management decisions for current and future EPLs.

Biographie du présentateur - Biography of the presenter: Heidi Cossey is an Engineer-in-Training (E.I.T.) and a PhD student studying Geoenvironmental Engineering at the University of Alberta. She previously completed her BSc in Civil Environmental Engineering and MSc in Environmental Engineering at the University of Alberta. Before returning to graduate school, Heidi worked as a Remediation E.I.T. focusing on mine waste management. Her PhD research aims to improve mine waste remediation and reclamation methods and requires the integration of geotechnical and environmental engineering, microbiology, and geochemistry. Heidi has won numerous awards for her academic and research capabilities, including the prestigious Vanier Canada Graduate Scholarship.

Language: English

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Ms. Heidi Cossey