Bilge　water　is　a　complex　oily　wastewater　that　may　contain　a　variety　of　contaminants　and　salts.　Electrocoagulation　(EC)　recently　emerged　as　an　efficient　process　for　bilge　water　treatment,　but　its　energy　cost　and　lifespan　are　primary　challenges.　This　study　compared　the　oil　removal　and　energy　consumption　of　both　DC　and　AC　powered　EC　units　and　investigated　the　effects　of　salinity　for　the　first　time.　Different　current　densities,　voltages,　and　operation　modes　(constant　current　and　constant　voltage)　were　investigated　to　understand　the　electrochemical　kinetics　of　high　salinity　bilge　water.　Results　showed　that　both　DC　and　AC　power　sources　satisfied　the　oil　reduction　requirement　with　over　99%　oil　removal　and　a　high　current　density　was　found　to　be　more　efficient　in　oil　removal.　High　salinity　(e.g.　35　g　L-1)　could　slightly　improve　demulsification　during　electrocoagulation　by　reducing　the　zeta　potential.　Different　frequencies　(0.25,　0.5　and　1　Hz)　of　AC　power　were　applied　to　EC　units　and　it　was　found　that　a　low　frequency　was　more　efficient　for　oil　removal.　The　results　also　showed　that　a　constant　AC　was　more　efficient　in　maintaining　the　same　performance　with　a　less　energy　cost　increment　than　the　DC　mode.