Accelerated consolidation of oil sands tailings using an anaerobic bioreactor

Abstract

Bitumen extraction from oil sands ores generates enormous volumes of fluid tailings in on-site repositories where slow consolidation of suspended solids and porewater recovery hamper tailings reclamation. Here, we demonstrate proof-of-concept where mature fine tailings (MFT) amended with hydrolyzed canola meal incubated in an anaerobic stirred tank reactor (STR) for 8 weeks stimulated indigenous microbes and subsequently accelerated consolidation and porewater recovery in columns and methane (CH4) production in sealed microcosms. Compared to untreated MFT, 5 weeks of STR treatment enhanced consolidation (solids increased from 23.2 to 39.4 wt%) and expression of porewater (four-fold more porewater in one-third the time), and up to 30-fold more CH4. The microbial community shifted towards diverse fermentative taxa and different methanogens. This approach suggests a potential technology to reduce tailings pond volumes and increase water use efficiency, decreasing freshwater demand in the bitumen extraction process while converting low-value substrate to CH4 for on-site utilization.