Bioremediation of diesel oil polluted seawater by a hydrocarbon-degrading bacterial consortium with oleophilic nutrients

Abstract

The use of oleophilic nutrients that contained nitrogen and phosphorus is a valid strategy to enhance bioremediation rate in the open marine environments contaminated with hydrocarbons where the presence of nutrients is limited. The bioremediation effectiveness of the natural oleophilic nutrients (uric acid and soya bean lecithin) and an artificial oleophilic fertilizer prepared in this study were tested with an efficient bacterial consortium. The artificial oleophilic fertilizer was prepared using urea solution, soya bean lecithin, alcohol and oleic acid to form a water-in-oil type microemulsion system. The bioremediation potential of the oil-degrading bacterial consortium and these oleophilic nutrients were implemented by flask-shaking tests and laboratory mesocosm experiments. The diesel oil degradation ratios of the natural oleophilic nutrients and oleophilic fertilizer were up to 73% and 60%, respectively, at the optimal application rate during the shake flask trials. In the mesocosm experiments, the oil concentration of the oleophilic fertilizer + bacterial consortium group was decreased from about 8000 mg/L to 823 mg/L after six days of incubation, and the number of bacteria in the seawater increased from 3 × 104 to 1.8 × 1010 CFU/mL. The combination of these oleophilic nutrients with and the consortium was an effective strategy to enhance bioremediation rate. This method could be exploited further for the development of an effective bioremediation technology for the marine oil pollution.