Spacer geometry and particle deposition in spiral wound membrane feed channels A.I. Radu a,b,* , M.S.H. van Steen a , J.S. Vrouwenvelder a,b,c , M.C.M. van Loosdrecht a , C. Picioreanu a a Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands b Wetsus, Centre of Excellence for Sustainable Water Technology, Agora 1, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands c King Abdullah University of Science and Technology, Water Reuse and Desalination Center, Thuwal, Saudi Arabia article info Article history: Received 4 December 2013 Received in revised form 22 June 2014 Accepted 30 June 2014 Available online 9 July 2014 Keywords: Membrane fouling Hydrodynamics Microsphere Particle tracking Desalination abstract Deposition of microspheres mimicking bacterial cells was studied experimentally and with a numerical model in feed spacer membrane channels, as used in spiral wound nano- filtration (NF) and reverse osmosis (RO) membrane systems. In-situ microscopic observa- tions in membrane fouling simulators revealed formation of specific particle deposition patterns for different diamond and ladder feed spacer orientations. A three-dimensional numerical model combining fluid flow with a Lagrangian approach for particle trajectory calculations could describe very well the in-situ observations on particle deposition in flow cells. Feed spacer geometry, positioning and cross-flow velocity sensitively influenced the particle transport and deposition patterns. The deposition patterns were not influenced by permeate production. This combined experimental-modeling approach could be used for feed spacer geometry optimization studies for reduced (bio)fouling. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Membrane processes play an important role in drinking and industrial water production. Membranes can be used to remove a wide range of contaminants, from colloids and suspended matter (with microfiltration, MF and ultrafiltration, UF) to ionic species (with nanofiltration, NF and reverse osmosis, RO). A common issue in membrane separation is the accumulation of fouling material at the feed side membrane surface. Particulate and colloidal matter with size ranging from nm to mm, together with microbial cells and organic macromole- cules can be encountered in the NF/RO feed water and deposit to the membrane surface (Yiantsios et al., 2005; Tang et al., 2011). While MF/UF pretreatment may be more effective than conventional granular media filtration (GMF) in pre- venting particles of different kinds from entering the NF/RO, microorganisms from the feed water have been reported to be present in the NF/RO even after UF pretreatment (Bereschenko et al., 2007). * Corresponding author. Address: Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Tel.: þ31 15 2781482; fax: þ31 15 2782355. E-mail addresses: A.I.Radu@tudelft.nl (A.I. Radu), M.S.H.vanSteen@student.tudelft.nl (M.S.H. van Steen), J.S.Vrouwenvelder@tudelft. nl (J.S. Vrouwenvelder), M.C.M.vanLoosdrecht@tudelft.nl (M.C.M. van Loosdrecht), C.Picioreanu@tudelft.nl (C. Picioreanu). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/watres water research 64 (2014) 160 e176 http://dx.doi.org/10.1016/j.watres.2014.06.040 0043-1354/© 2014 Elsevier Ltd. All rights reserved.