Wastewater treatment from the biodiesel production using waste cooking oil by electrocoagulation: a multivariate approach

This study mainly focuses on the process of electrocoagulation (EC) for the wastewater treatment from biodiesel production using waste cooking oil. The effects of current density, initial pH and electrolysis time on the EC process using aluminum (Al) and iron (Fe) electrodes were investigated for removal of chemical oxygen demand (COD). The COD removal efficiencies were found to be 62.7% and 63.4% at optimum conditions for Al (current density: 43 mA/cm 2 , pH: 5, time: 21 min) and Fe (current density: 47 mA/cm 2 , pH: 7.7, time: 30 min) electrodes, respectively. At these optimum conditions, the removal efficiencies of oil & grease, total phosphorus (TP), orthophosphate (PO4-P) and total suspended solids (TSS) were determined respectively to be above 89.9%, 98.9%, 99.5%, 86.7% for Al electrodes and 90.8%, 98.5%, 97.6%, 89.6% for Fe electrodes. Total operating costs were also found to be 6.43 €/m 3 and 7.01 €/m 3 for Al and Fe electrodes, respectively. The results indicate that the EC process using both types of electrodes seems to ensure an efficient treatment of biodiesel wastewater in terms of oil & grease and TP.