Separation Methods for Oily Wastewaters with Focus on Membrane Separation, a Review

Oily wastewaters are generated in many industrial processes, such as petroleum refining, ýpetrochemical and food. These oily wastewaters are mainly in the form of oil-in-water (O/W) ýemulsions. Oil removal requires an understanding of the physical properties and chemical ýcomposition of O/W emulsions. Several properties in the stability of an O/W emulsion should ýbe measured for the selection of the appropriate separation process, specifically, surface ýtension, contact angle, zeta potential and droplet size distribution. Treatment of oily ýwastewaters is performed by a variety of methods and the degree of oil removal depends on ýthe concentration and physical nature of the oil, droplet size and separation techniques. The ýpurpose of this work is to study oil/water system properties, and techniques for removing oil. ýThese techniques include gravity and centrifugal separations, chemical treatment, flotation, ýmembrane processes, evaporation, activated carbon adsorption and biological treatment. At ýlast, treatment costs and hybrid processes will be covered.ý