Desalination 206 (2007) 61–68 0011-9164/07/$– See front matter © 2007 Elsevier B.V. All rights reserved Presented at EuroMed 2006 conference on Desalination Strategies in South Mediterranean Countries: Cooperation between Mediterranean Countries of Europe and the Southern Rim of the Mediterranean. Sponsored by the European Desalination Society and the University of Montpellier II, Montpellier, France, 21–25 May 2006. *Corresponding author. Utilization of a shear induced diffusion model to predict permeate flux in the crossflow ultrafiltration of macromolecules M. Cinta Vincent Vela a *, Silvia Álvarez Blanco a , Jaime Lora García a , José M. Gozálvez-Zafrilla a , Enrique Bergantiños Rodríguez b a Chemical and Nuclear Engineering Department, Polytechnic University of Valencia, C/Camino de Vera s/n 46022 Valencia, Spain Tel. +34 (96) 3877000 Ext. 76383; Fax +34 (96) 3877639; email: mavinve@iqn.upv.es b Chemical Engineering Department, Polytechnical Institute José A. Echeverría, Ave. 114, No. 11901, Havana, Cuba Received 29 January 2006; accepted 1 March 2006 Abstract In this paper a shear-induced diffusion model is used to predict permeate flux decline with time in the ultrafiltration of macromolecules. The results estimated by the model were compared with the experimental results obtained in a pilot plant. Tubular ZrO 2 –TiO 2 ceramic membranes with a molecular weight cut-off of 15 kDa (Orelis, France) were used. The fouling experiments were performed with 5 g/L PEG (35000 Da molecular weight) aqueous solutions at different transmembrane pressures and crossflow velocities. Flux decline was predicted without the utilization of empirical parameters dependent on the operating conditions. Good predictions were obtained for all time scales in the case of low crossflow velocities. For high crossflow velocities, the results predicted by the model were good only for long time scales. Keywords: Crossflow ultrafiltration; Modelling; Macromolecules, Fouling 1. Introduction Ultrafiltration (UF) is a membrane technique that has a lot of industrial applications, such as wastewater treatment, chemicals processing, food processing, biotechnology, etc [1]. A major limit- ing phenomenon in UF technology is the fouling of the membrane [2]. Fouling of the membranes is noticeable when there is a decline in flux with