A simple model to predict the removal of oil suspensions from water using the electrocoagulation technique

A simple model has been developed to predict the removal of hydrocarbon fractions from wastewater using sacrificial Al anodes. The model was successfully applied to the interpretation of experimental data obtained in a laboratory electrochemical cell operated in a batchwise manner. The adsorption equilibrium of organic matter on Al hydroxide was modelled using three equations, with the best results obtained using a Langmuir-type equation. The model was able to describe the effects of current density and pollutant concentration on the efficiency of wastewater treatment. Different values were obtained for the parameters depending on the nature of the hydrocarbon suspension. Aluminium hydroxide showed a far higher affinity for the oil/kerosene suspension but exhibited a higher capacity to remove heavy oil suspensions. The removal rates of pollutants were found to depend on the initial concentration and the current density. When the current density was sufficient to destabilise the emulsion, the zeta potential of the clear fraction measured at pH 7.0 became positive. This change was also characterised by a significant reduction in turbidity. Furthermore, the application of higher current densities did not allow further treatment of the water. However, the efficiency of emulsion destabilisation was found to depend on the concentration and current densities that were too low were ineffective. (c) 2005 Elsevier Ltd. All rights reserved.