Mass transfer and bioremediation of aromatics from NAPL in a baffled roller bioreactor

A non-aqueous phase liquid (NAPL) containing dissolved naphthalene or phenol was used to simulate water insoluble contaminants which are produced during the processing of oil sands. Mass transfer and biodegradation of organic contaminants in the aqueous phase were studied in a baffled roller bioreactor. Mass transfer of both naphthalene and phenol from NAPL into the aqueous phase was completed in less than 60 min, by which time naphthalene reached its saturation concentration in the aqueous phase and phenol was completely transferred into the aqueous phase. Pseudomonas putida (ATCC 17484) was subsequently used in biodegradation experiments in the baffled bioreactor containing the model NAPL contaminant. The optimum loading of NAPL for biodegradation of naphthalene at 500 mg/L was found to be 40%. High biodegradation rates (136.4 mg/L h for naphthalene and 13.2 mg/L h for phenol based on the working volume of the bioreactor) were achieved. In the case of simultaneous biodegradation of naphthalene and phenol, the highest total biodegradation rate of 102.6 mg/L h was achieved.