Enhanced hexane biodegradation in a two phase partitioning bioreactor: Overcoming pollutant transport limitations

The use of an organic solvent can allow to increase the mass transfer, and thereby biodegradation, of hydrophobic gaseous pollutants. The biodegradation of hexane by a Pseudomonas aeruginosa strain was thus optimized in a two phase partitioning bioreactor (TPPB). Silicone oil was first selected among various organic solvents based on its biocompatibility and resistance to P. aeruginosa and its high affinity for hexane (air-organic partitioning of 0.0034). A silicone oil based TPPB was then compared with a conventional biofilter packed with foamed glass beads for the removal of hexane. The use of silicone oil significantly improved the process performance, allowing removal efficiencies (RE) and elimination capacities (EC) of 70 ± 5% and 135±17 g mreactor−3 h−1, respectively, which were approximately five times higher than those in a similar system deprived from organic phase. When a conventional packed-bed biofilter was used, the average RE and EC achieved were 7 ± 4% and 12±7 g mreactor−3 h−1, respectively. This study therefore confirms the potential of TPPBs for enhancing the transport and subsequent biodegradation of poorly soluble gaseous contaminants.