Oil-polluted bilge water is difficult to treat, especially in large scale, due to its high salinity, complicated composition and toxicity. To improve the efficacy of ballast bilge water treatment, an artificial bacterial consortium including nine petroleum degrading strains previously screened from petroleumpolluted ocean waters was applied as bioaugmentation agent. A trial run was firstly completed in a 500 L tank, following which a second run was carried out in a specially designed 600 L bioreactor. The total petroleum hydrocarbons were analyzed to evaluate the efficacy of treatment. Moreover, potential changes in the structure of bacterial consortia during treatment were monitored with denaturing gradient gel electrophoresis and Illumina HiSeq 2000 sequencing. In the first trial run, the oil-removal efficiency was approximately 70%, while in the second run performed in specially designed bioreactor, the efficiency of oil degradation was increased to over 90%. In both runs, the artificial bacterial consortium was reconstituted during the acclimation process immediately before the treatment, and then stabilized and predominated by three strains, Marinobacter hydrocarbonoclasticus, Acinetobacter venetianus, and Alcanivorax dieselolei, throughout the following several months of treatment. Overall, this work suggests that bioaugmentation with the artificial bacterial consortium composed of hydrocarbon-degrading strains could provide a promising solution to the treatment of oil-polluted ballast bilge water in large scale.