Treatment of Al-Muthanna Petroleum Refinery Wastewater by Electrocoagulation Using a Tubular batch Electrochemical Reactor

Abstract

An electrocoagulation process has been used to eliminate the chemical oxygen demand (COD) from wastewaters discharged from the Al-Muthanna petroleum refinery plant. In this process, a circular aluminum bar was used as a sacrificial anode, and hallow cylinder made from stainless steel was used as a cathode in a tubular batch electrochemical Reactor. Impacts of the operating factors like current density (5-25mAcm-2), NaCl addition at concentrations (0-2g/l), and pH at values (3-11) on the COD removal efficiency were studied. Results revealed that the increase in current density increases the COD removal efficiency, whereas an increase in NaCl concentration results in a decline in the COD removal efficiency. Using a pH value higher or lower than 7 causes a lowering of the COD removal efficiency. A current density of 15mA/cm2, NaCl concentration of 1g/l, and pH value of 7 were found to be the best operating conditions in which COD removal efficiency of 95.3% was achieved at a treatment time 45 minutes with an energy consumption of 27.78kWh/kg COD. Based on these conditions, a COD value of 20 ppm could be obtained, which is below the standard limit for discharging petroleum refinery effluents.