Biodegradation of polycyclic aromatic hydrocarbons in a two-liquid-phase system

The use of a two-liquid-phase system consisting of silicone oil and water for biodegrading polycyclic aromatic hydrocarbons (PAHs) was investigated. Biomass determinations indicated that the cells were mainly growing at the silicon oil-water interface. In shaken and aerated systems with PAHs and inoculum, 97% and 80%, respectively, of the total biomass was attached to the silicone phase. PAH concentrations in the silicon phase dropped by a factor 2 to 100 when microorganisms were present. Biodegradation rates in these systems varied from 3.6 to 5 mg PAH-C/L reactor{center_dot}d. In the shaken systems at 28 C, the measured CO{sub 2} production rate was equal to 9.1 mg CO{sub 2}/L reactor{center_dot}d and corresponded to a 50% conversion to CO{sub 2}. In the aerated systems at 10 C, however, only 25% of the PAH-C was converted to CO{sub 2}, resulting in a CO{sub 2} production rate of 0.5 mg CO{sub 2}/L reactor{center_dot}d.