Electrochemical oil/water demulsification and purification of bilge water using Pt/Ir electrodes

The electrochemical oil/water demulsification and purification of bilge water were investigated using Pt/Ir electrodes in a batch electrochemical reactor. Bilge water is a corrosive mixture of seawater containing a variety of constituents including cleaning agents, solvents, fuel, lubricating oils and hydraulic oils. It is resulted mainly by the leakage from the machinery and fresh water washdowns, which are allowed to drain to the lowest inner part of the ship's hull. In this study, the influence of operating parameters as bilge water composition, seawater/fresh water composition, current density, and reaction temperature on the removal efficiency of COD, oil/grease and turbidity was analyzed. Experimental results were optimized using response surface methodology in order to maximize the removal rates while minimizing current density and mean energy consumption. The optimized conditions under specified constraints were obtained for the highest desirability at 100% bilge water composition (CODo = 3080 mg/L), 50/50% seawater/fresh water composition, 12.8 mA/cm2 current density and 32 °C reaction temperature. Kinetic studies resulted in first order overall electrochemical conversion rate of pollutants based on COD concentration with the activation energy of 26.2 kJ/mol.