Treatment of automotive industry oily wastewater by electrocoagulation: statistical optimization of the operational parameters

An electrocoagulation process was used for the treatment of oily wastewater generated from an automotive industry in Medellín (Colombia). An electrochemical cell consisting of four parallel electrodes (Fe and Al) in bipolar configuration was implemented. A multifactorial experimental design was used for evaluating the influence of several parameters including: type and arrangement of electrodes, pH, and current density. Oil and grease removal was defined as the response variable for the statistical analysis. Additionally, the BOD₅, COD, and TOC were monitored during the treatment process. According to the results, at the optimum parameter values (current density = 4.3 mA/cm², distance between electrodes = 1.5 cm, Fe as anode, and pH = 12) it was possible to reach a c.a. 95% oils removal, COD and mineralization of 87.4% and 70.6%, respectively. A final biodegradability (BOD₅/COD) of 0.54 was reached.