Vegetable oils as NAPLs in two phase partitioning bioreactors for the degradation of anthracene by laccase

• Vegetable oils were effective as NAPLs in two phase partitioning bioreactors (TPPB).
• Pomace olive oil led to higher removal of anthracene than sunflower or silicone oils.
• Laccase stability was higher in presence of vegetable oils than in silicone oil.
• Addition of O2 and mediator by pulses improved anthracene oxidation rate.
• Anthracene partition led to a better knowledge of the mechanisms involved in a TPPB.

The enzymatic degradation of anthracene by the laccase-mediator system in two phase partitioning bioreactors (TPPB) with sunflower oil and pomace olive oil used as non-aqueous phase liquid (NAPL) was proposed. Triton X-100 (1% v:v) was added as surfactant to increase interfacial area and thus, to improve mass transfer. The highest oxidation of anthracene was obtained with pomace olive oil as NAPL. Furthermore, the influence of several factors such as oxygen level, mediator concentration and laccase addition were investigated to maximize the removal of anthracene. Both dissolved oxygen and 1-hydroxybenzotriazole (HBT) concentrations were found to be limiting the rate and extension of the process. The strategy of their addition in pulses led to total removal after 48 h with a high conversion rate of anthracene: 30.3 μmol/LR h. Experimental data were modeled according to pseudo-first order kinetics with a rate constant (k) of 170.7 h−1 and the overall mass transfer coefficient (KLa) was estimated in 1573.1 h−1. This study suggests the potential application of TPPB with oxidative enzymes as a suitable treatment alternative for the recovery of vegetable oils contaminated with hydrophobic pollutants.