Fig. 4From: Formations of calcium carbonate minerals by bacteria and its multiple applicationsImpermeability tests. a A plastic pipette (25 ml) was used as a column, b sand slurry (50 g) was packed into the column, c cell suspension (10 ml) was passed through each column and flow-through was reloaded once, d crystal violet (2 ml) was dropped into a packed sand column to measure the migration distance (Source from Kang et al. 2014b)Back to article page