Slow densification of mature fine tailings (MFT) is one of the major challenges in reduction of tailings inventory, pore-water recovery and reclamation of tailings for oil sands industry. Bio-densification is a new treatment method in which densification of tailings is accelerated through microbiological activity. Two-meter columns were installed to study effect of microbial activity on consolidation of MFT. Gas production and changes in concentration of ions due to microbial activity are recognized as two important parameters in settling rate of bio-activated tailings. Therefore, effects of these parameters on consolidation characteristics of tailings are studied. Effect of bicarbonate ions on settling was investigated based on a series of experiments on bitumen-free MFT which was synthesized through separation process. Two models have been developed based on finite strain theory to describe consolidation of saturated and gassy slurries. These equations are solved by COMSOL Multiphysics to predict the experimental observations.