A process is proposed for the treatment of a waste oil-in-water (O/W) emulsion generated in an industrial copper-rolling operation. The use of demulsifier agents improves the subsequent treatment by techniques such as ultrafiltration (UF) or evaporation. The effluent COD is reduced up to 50% when the O/W emulsion is treated by UF using a flat 30 nm TiO2 ceramic membrane (Delta P=0.1 MPa) and up to 70% when it is treated by vacuum evaporation, after an emulsion destabilization pretreatment in both cases. Increases in the UF permeate flux and in the evaporation rate are observed when a chemical demulsifier is used in the pretreatment step. A combined process consisting of destabilization/settling, UF, and vacuum evaporation can yield a very high-quality aqueous effluent that could be used for process cooling or emulsion reformulation. (C) 2010 Elsevier B.V. All rights reserved.