Ceramic membrane performance in microfiltration of oily wastewater

A large amount of oily wastewaters is generated by industrial sources. Oil-in-water emulsions are the most serious pollutants for which current treatment technologies are often costly and ineffective. In recent years, membrane processes have been applied for oily wastewater treatment. Microfiltration (MF) was successfully used in oil-in-water separations. In this research, investigations were carried out for treatment of an oily wastewater. A tubular ceramic MF (α-Al2O3) system was employed for treatment of a typical oily wastewater comes from API effluent of Tehran refinery. This system could produce a permeate with oil and grease content of 4 mg/L that meets the National Discharge Standard and exhibited TOC removal efficiency higher than 95%. Also, effects of operating parameters such as transmembrane (TMP), cross flow velocity (CFV) and temperature on permeate flux, TOC removal efficiency and fouling resistance (FR) were investigated. The recommended operating conditions are TMP of 1.25 bar, CFV of 2.25 m/s and temperature of 32.5 °C. In this system, backwashing was used to remove oil droplets and particulates that block the membrane pores, and the results showed that backwashing could prevent permeate flux decline significantly. Based on the results, this system was proposed to be replaced with the conventional wastewater treatment method.