Treatment of Oily Wastewater by Polyethersulfone (PES) Hollow Fiber Nanostructure Membranes

The oily water from oil refineries and oil distribution centers are one of the most important environmental pollutants in recent decades that make serious damages on the environment. Membrane technology can play an important role in treatment of these kinds of wastewaters as there is no need for chemical addition for breaking the emulsion and the treatment facilities are highly automated. In this research, the performance of different membranes in oily water treatment was reviewed and the performance of nanostructure polyethersulfone (PES) hollow fiber membranes in oil/water separation process was investigated and the effect of operating parameters such as pressure, oil concentration and cross flow velocity of feed on the membrane performance is studied. Increasing the pressure makes higher membrane fouling that reduces the flux of treated water so P = 1 bar, high liquid velocity and low feed concentration were selected as the optimum operating conditions. Membrane surface fouling by oil coarse particles is one of the main problems in membrane processes. Oil particles precipitate on the membrane surface and form second layer on the membrane surface. Second layer formation is leading to flux reduction and enhanced rejection. The effects of membrane fouling at high pressures (2 bar and 3 bar) is quite obvious, so at high pressures the difference in flux with fresh membrane is more evident. All the fabricated PES membranes showed complete separation of oil from water. Therefore, they can effectively be used in oily water treatment.