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

Abstract

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.

Keywords:

• Electro-oxidation
• Current density
• Stainless steel electrodes
• Petroleum wastewater
• Phenol
• Oil

Ackonwledgment

The authors would like to acknowledge the financial and technical supports provided by King Fahd University of Petroleum and Minerals, Saudi Arabia to conduct the research.