Conference paper
Part of the NATO Science for Peace and Security Series C: Environmental Security book series (NAPSC)


Oily wastewaters are generated in many industrial processes, such as petroleum refining, petrochemical, food, leather and metal finishing. Fats, oils and greases (FOG’s) present in these wastewaters have to be removed before the water can be reused in a closed-loop process or discharged into the sewer system or to surface waters. These oily waters are mainly in the form of oil-in-water (O/W) emulsions that pose a great problem in facilities attempting to stay in compliance with discharge limits. Emulsion breaking and oil removal require a basic understanding of the physical properties and chemical composition of O/W emulsions. Several properties playing a key role in the stability of an O/W emulsion should be measured for the selection of the appropriate separation process. Only those of industrial relevance will be discussed here, specifically, surface and interfacial tension, contact angle (wetting), zeta potential and droplet size distribution. Treatment of oily wastewaters is performed by a variety of methods and the degree of oil removal depends mainly on the concentration and physical nature of the oil present and its droplet size. The purpose of this work is to study oil/water system characteristics and properties, and techniques for removing oil and grease from industrial wastewaters in analogy with sewage treatment processes. These techniques include gravity and centrifugal separations, chemical treatment, flotation, filtration, membrane processes, evaporation, activated carbon adsorption, biological treatment, and integrated or hybrid processes. Operating parameters, equipment design, treatment costs, range of operation, and the possibility of O/W emulsion reformulation before treatment will also be covered.


Chemical Oxygen Demand Zeta Potential Interfacial Tension Biochemical Oxygen Demand Cetyl Trimethyl Ammonium Bromide 
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© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Department of Chemical Engineering and Environmental TechnologyUniversity of OviedoOviedoSPAIN
  2. 2.Department of Chemical EngineeringUniversity of BurgosBurgosSPAIN

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