Presented at the 2nd Membrane Science and Technology Conference of Visegrad Countries (PERMEA), Polanica Zdroj, Poland, 18–22 September 2005. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved Desalination 198 (2006) 303–309 Application of a dynamic model for predicting flux decline in crossflow ultrafiltration María Cinta Vincent Vela*, Silvia Álvarez Blanco, Jaime Lora García, Enrique Bergantiños Rodríguez Chemical and Nuclear Engineering Department, Polytechnic University of Valencia, C/Camino de Vera s/n 46022 Valencia, Spain Tel. +34 (96) 387-7000, ext. 76383; Fax: +34 (96) 387-7639; email: mavinve@iqn.upv.es Received 3 November 2005; Accepted 22 January 2006 Abstract A semi-empirical crossflow ultrafiltration (UF) model that can predict permeate flux as a function of time for different operating conditions was considered. Model predictions were analysed and compared with the experimental results obtained in a crossflow UF plant under different operating conditions. The crossflow UF experiments were performed under different transmembrane pressures and crossflow velocities. Tubular ceramic membranes supplied by Orelis (France) were used. The molecular weight cut-off of the membranes was 15 kg/mol. They consisted of a TiO 2 –ZrO 2 active layer on a carbon support. Polyethylene glycol with a 35,000 g/mol molecular weight was used as a standard macromolecule in the UF experiments to test the model. A solute concentration of 5 g/L was considered. Model predictions were better for low crossflow velocities. Keywords: Crossflow ultrafiltration; Modelling; Flux decline; Fouling 1. Introduction The non-steady nature of ultrafiltration (UF) processes is caused by fouling of the membranes. The fouling phenomenon is the main limiting factor in the application of membrane tech- *Corresponding author. nologies and is responsible for flux decline. It reduces the permeate production and increases the complexity of membrane processes because the process needs to be frequently stopped for membrane cleaning to reestablish the permeate flux. The high cost of cleaning operations is the main drawback of UF processes [1].