Accelerated consolidation of oil sands tailings using an anaerobic bioreactor

Anaerobic Microbial Activity May Affect Development and Sustainability of End-Pit Lakes: A Laboratory Study of Biogeochemical Aspects of Oil Sands Mine Tailings

“…Another significant impact of microbial activity in amended FFT columns is transport of residual bitumen from FFT through transient channels to the cap water surface, as previously documented. ,, Although the mass of released bitumen could not be quantified in the current study, we observed transport of bitumen from FFT to cap water during CH 4 ebullition in amended columns (both intact and monitored), producing layers of floating bitumen associated with gas bubbles (Figure B). In contrast, no bitumen was released to the cap water of unamended FFT columns (Figure A).…”

“…Similar pockmarks have also been seen at the surface of the FFT–water interface at BML . Our previous column studies captured this phenomenon in highly amended FFT by time-lapse video photography . In our columns, turbidity developed slowly but persistently at 10 °C and quickly but transiently at 20 and 30 °C where the onset of CH 4 flux in A20-M and A30-M columns correlated well with the turbidity peaks (650 and 450 NTU, respectively) in the cap water of those columns.…”

Nutrient Impacts on Biogenic Chemical Flux in an End Pit Lake Reclamation Scenario

“…The first commercial demonstration of EPL known as Base Mine Lake (∼8 km 2 surface area) was established in 2013 by capping FFT with a mixture of oil sands process-affected water plus freshwater from a nearby creek to evaluate its performance. , Field measurements and thermodynamic and transport modeling indicated that gas ebullition at Base Mine Lake enhanced chemical mass transport from the underlying tailings to the water cap. , FFT harbors indigenous microbial communities , that anaerobically metabolize residual diluent hydrocarbons to produce CH 4 . − Laboratory studies evidence three key geochemical, geotechnical, and hydrological changes in FFT: (1) methanogenesis produces CH 4 creating gas ebullition that physically disturbs the FFT and the solid-water interface (mud line), (2) it increases porewater ionic strength by transforming (dissolving and precipitating) minerals (iron oxides and carbonates) in FFT, and (3) it increases dewatering and consolidation of FFT by altering the porewater and FFT solid-phase chemistry. − Transformation of minerals under methanogenic conditions can mobilize mineral-associated trace elements such as vanadium­(V), arsenic (As), cobalt (Co), nickel (Ni), and strontium (Sr) in the FFT porewater . The major drivers of flux of chemical constituents from underlying FFT to cap water in Base Mine Lake are (1) advective transport due to upward movement of expressed porewater by settling of FFT, which is declining with the decreasing settling rate of FFT, (2) diffusion of dissolved constituents across the concentration gradient between the FFT and cap water interface, which will increase in importance as a mode of chemical mass transport with continued freshwater inputs, and (3) CH 4 ebullition enhancing chemical mass transport through continuous physical mixing, which is likely to decline over time due to microbial depletion of labile residual hydrocarbons in FFT.…”