Membrane separation as a pre-treatment process for oily saline water

Oil and gas industry generate large quantities of oily wastewater effluents. This wastewater has a major impact on the environment and human health. Hence, a suitable separation method is applied to treat oily wastewater to not only meet the environmental regulations but also to promote water recycling and desalination. Many studies were performed in the literature to investigate the best technologies for treating oily saline water such as the traditional technique of gravity sedimentation and dewatering. Among all, membrane separation processes have been receiving extra attention in the past decades. This is due to their high separation efficiency, low energy requirements and easy operation. Additional research activities were also directed to utilize membranes in pre-treatment separation processes of oily water ahead of the desalination units. This paper presents a comprehensive review for the recent treatment processes available in the literature for oily wastewater with the concentration on the use of various membranes to accomplish this target. The paper also reviews the recent findings in membranes' development and emerging modification techniques such as interfacial polymerization, nanoparticles incorporation, and surface grafting. A special emphasis was given for ceramic membranes, their operation and their preparation techniques. Moreover, the paper compares and discusses the effect of different operating conditions such as trans-membrane pressure and cross flow velocity on membrane separation performance in oily water.