• oil sands;
  • microbial enhanced oil recovery;
  • water-based extraction processes;
  • wettability;
  • viscosity;
  • asphaltenes

When using the water-based extraction processes (WBEPs) to recover bitumen from the weathered oil sands, very low bitumen recovery arisen from the poor liberation of bitumen from sand grains is always obtained. Application of microbial enhanced oil recovery (MEOR) technology in WBEPs to solve the poor processability of the weathered ore was proposed. It was found that processability of the microbial-treated weathered ore was greatly improved. The improved processability was attributed to the biosurfactants production in the culture solution, alteration of the solids wettability, degradation of the asphaltene component, and the decrease of the bitumen viscosity, which collectively contributed to the bitumen liberation from the surface of sand grains. Although it still has many issues to be solved for an industrial application of the MEOR technology in oil sands separation, it is believed that the findings in this work promote the solution to the poor processability of the weathered ore. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2985–2993, 2014