Treatment of synthetic petroleum refinery wastewater in a continuous electro-oxidation process

A continuous electrochemical process was investigated for the treatment of synthetic petroleum refinery wastewater. Phenol, crude oil, and kaolin were added in concentrations typical to that found in a refinery wastewater to simulate the soluble, immiscible, and colloidal phases, respectively. Stainless steel (AISI 304) electrodes were used in the electrochemical cell, while an immersed ZW-1 ultrafiltration membrane module was utilized for solid-liquid separation. Different operational conditions were investigated by varying current density and contact time. The optimum current density was noted to be 30 mA cm^-2 with 20 min of contact time. Tap water having a conductivity of 5,000 μ ohm/cm was used as for the preparation of the synthetic wastewater. The results from series of experiments showed that high total dissolved solids (1,300 mg/L) in raw water produced a significant interference in degradation of phenol. However, a removal efficiency of 99 percent was achieved for turbidity, while oil was below the minimum detection limit of 1.4 mg/L for the EPA method 1664 used to detect oil in the treated samples.