Contamination of soil is one of the main concerns in petroleum industries. Several methods including physical, chemical and biological methods have been developed to remove soil contaminants. None of which seems to be able to effectively prevent the propagation of contaminants towards the ground water.

Biobarrier technology has been shown to be promissing method for such purpose. Drilling shallow injection wells and injecting starved exopolymer-producing bacteria and then nutrients into the drilled wells around the contaminated zone are the sequences of creating an underground biobarrier.

In this paper, the effectiveness of two exopolymer-producing bacteria (i.e. Bacillus licheniformis and Leuconostoc mesenteroides) to construct biobarriers in a sand packed column at different temperatures (25-55°C) and salinities (0-10% w/v of NaCl) are avaluated. The results show that at 40 °C and moderate salt concentrations, B. licheniformis can significantly reduce the soil permeability whereas lower temperatures and salt concentration favor biobarrier formation by L. mesenteroides. For both bacteria, the extreme soil plugs are noticed to be between 72 and 120 hours after injection of the inoculated medium. Furthermore, a 2D glass micromodel is employed to observe the pore-scale development of biobarrier preventing Dense Nonaqueous-Phase Liquids (DNAPLs) migration.

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