Anaerobic Biodegradation of Linear Model Naphthenic Acid Under Denitrifying Conditions

Abstract

The oils sands have become significant source of energy supply and a major economic driver for Canada. Due to the increase in production of oil, the activity of surface mining to extract oil sand increases. To carry out continuous operation of extracting bitumen from oil sands, industry uses large volumes of freshwater. Generation of produced oil sand process water which has to be treated prior to discharge in environment has become a significant issue of environmental concern. The presence of naphthenic acids was found to be the source of toxicity in the process water associated with oil sands. This together with necessity of sustainable use of water, the need develops for the effective treatment technologies such as bioremediation of process water contaminated with these naphthenic acids. In the present work, anaerobic biodegradation of a linear model naphthenic acid (Octanoic acid) under denitrifying conditions was studied. The microbial culture utilized in the biodegradation of model naphthenic acid compound was already developed in the laboratory and acclimatized to the anaerobic conditions. Octanoic acid was used as the organic substrate and potassium nitrate as electron acceptor in the experiments. The batch and continuous stirred tank bioreactor experiments were performed to evaluate the biokinetics of biodegradation of octanoic acid under denitrifying conditions. In the batch experiments the influence of concentration of octanoic acid and nitrate, and temperature were studied. In the continuous experiments effect of loading rate on removal were observed. Finally, the results revealed the efficient removal of octanoic acid following with the process of denitrification.