Operational Parameters Effect on the Treatment of Oil-in-Water Emulsion by Electrocoagulation Process

 Bensadok Kenza, Gousmi Nawel, Houari Boumediene University of Sciences and Technology, Algiers, Algeria

The cutting fluids are used in particular during mechanical operations of cutting and shaping metals. With the use, these fluids lose their properties and effectiveness and need to be replaced periodically. The generated oily wastewaters contain stable oil-in-water emulsions and are very charged in surface-active agents and organic pollutants. In order to reduce the impact of their discharge, an appropriate treatment of these wastewaters is necessary. Electrocoagulation (EC) has the potential to be competitive with respect to both economical and environmental criteria for treatment of wastewater and other related water management issues.

This study is mainly focused on the EC treatment of cutting oil emulsions (1 % in v/v) for investiga­tion of the effect of the main operating parameters, e.g., initial pH, current density, supporting electrolyte concentration and electrolysis time. Turbidity and COD values were used to evaluate the EC progress and the removal efficiency. For all cases, two phases were observed during the discontinuous treatment: (i) a reactive phase for which the treatment efficiency increases regularly with time; (ii) a steady phase for which further Al electrode dissolution has no effect on the treatment efficiency. Also, the optimum current density, initial pH and electrolysis time were 100 mA/cm², 7 and 45 min, respectively. For these condi­tions, the treatment efficiency and the energy consumption were, respectively, 90 % and 0.057 kWh/kg of COD removal.