Treatment of phenol in the organic solutions by a hybrid partition and biodegradation process with two-phase dispersions

A combined process of partition and two-phase biodegradation was proposed to treat phenol in organic solution by Pseudomonas putida BCRC 14365 in aqueous mineral salt medium at 30°C in an agitated vessel equipped with a six-blade disk turbine. Kerosene was selected as the organic solvent because of its non-biodegradability and suitable partition coefficient for phenol (0.35). The initial cell concentration in mineral salt medium was fixed at 25 g/m³. The effect of initial phenol concentration in the organic solution (300-2500 g/m³) on phenol removal and cell growth was experimentally examined. Under the conditions studied, phenol could be completely removed from the organic solution and biodegraded in the cell medium within 78 h even though the initial phenol concentration was high up to 1800 g/m³. A simple model that combines steady mass-transfer equations and dynamic growth kinetics of suspended cells was proposed to follow the whole treatment process. The mass transfer characteristics between organic/aqueous dispersions were first determined by measuring the fluxes of simple diffusion of acetic acid and iodine. The proposed model was shown to satisfactorily describe the process as long as phenol concentration in the cell medium did not exceed the toxicity limit of P. putida cells in freely suspended condition.