Electrokinetic treatment of high saline petrochemical wastewater: Evaluation and scale-up

High total dissolved solids (TDS) wastewater containing high amounts of organics with toxic and recalcitrant characteristics is a major concern in some petrochemical industries. This study was designed to evaluate a novel electrokinetic process for chemical oxygen demand (COD) removal. The removal of COD was carried out in some batch experiments in lab scale and effect of experimental factors such as the pH, current intensity, time, electrodes distances and TDS on the COD removal was evaluated. Also scale-up of the process was done in order to evaluate energy consumption. The obtained findings indicated that best conditions for COD removal were achieved in pH 5, current intensity of 0.5 A and electrodes distance of 2 cm. Pseudo-first-order kinetic model with rate constant of 0.0093 min^-1 and significant coefficient of correlation (R²) 0.948 was the best fitted with experimental results. Energy consumption was 32 KWh.m^-3 while 80 fold scaling up the reactor resulted in lower energy consumption of 2.1 KWh.m^-3. Biodegradability improvement confirmed by BOD₅/COD, average oxidation state (AOS) and carbon oxidation state (COS) indicators, Also GC chromatogram of the raw and treated wastewater showed removal and/or degradation of recalcitrant organics to more degradable and simpler compounds.