Chemical Engineering Department -Faculty of Engineering – University of Al-Qadisiyah-Iraq


The present paper deals with the electrochemical treatment of wastewaters generated from Al-Diwaniyah petroleum refinery plant in a batch electrochemical reactor using stainless steel cathode and porous graphite anode. Effects of operating parameters such as current density (5-25mA/cm2), pH (3-9), addition of NaCl (0-2g/l), and time (20–60min) on the removal efficiency of chemical oxygen demand (COD) were investigated. The results revealed that both pH and NaCl addition have the main effect on the COD removal efficiency confirming that the system was governed by reaction conditions in the bulk of solution not upon the electro oxidation of chloride ion on the surface of the electrode. Parametric optimization was carried out using Response Surface Methodology (RSM) combined with Box–Behnken Design (BBD) to maximize the removal of COD. Under optimized operating conditions of initial pH: 3, current density = 25 mA/cm2, NaCl conc.  = 2g/l, and time = 60 min, the removal efficiency of COD was found to be 98.16% with energy consumption of 9.85 kWh/kgCOD which is relatively lower than the previous works.