Journal of Membrane Science 281 (2006) 316–324 The Membrane Fouling Simulator: A practical tool for fouling prediction and control J.S. Vrouwenvelder a,∗ , J.A.M. van Paassen b , L.P. Wessels a , A.F. van Dam a , S.M. Bakker b a Kiwa Water Research, Department of Microbiological Water Quality and Health, Groningenhaven 7, P.O. Box 1072, 3430 BB Nieuwegein, the Netherlands b Vitens, P.O. Box 23, 6880 BC Velp, the Netherlands Received 30 December 2005; received in revised form 29 March 2006; accepted 30 March 2006 Available online 18 April 2006 Abstract A tool is developed for the validation of membrane fouling: the Membrane Fouling Simulator (MFS). The MFS uses the same materials as spiral wound reverse osmosis and nanofiltration membranes, has similar dimensions and hydrodynamic behaviour and is equipped with a sight glass. Using the MFS, fouling can be monitored by: (1) operational parameters like pressure drop, (2) non-destructive (visual and microscopic) observations using the window and (3) analysis of coupons sampled from the membrane sheet in the MFS. The major advantages of the MFS are: (i) representativeness of spiral wound membranes and (ii) the small size requiring small amounts of water and chemicals, reducing research costs and enhancing the possibility to test several MFS units in parallel. The MFS can be applied for early warning, characterization of the fouling potential of feed water, comparison of different pre-treatment schemes and for evaluation of fouling control applying different chemicals. The MFS can be used in model studies to develop integrated membrane systems less susceptible to fouling. The MFS is a suited tool for testing newly developed membranes. The first MFS tests showed that the results are representative for membranes used in practice under the same operating conditions. A comparison study of the MFS and spiral wound membrane modules showed the same pressure drop development in time and the same fouling accumulation. © 2006 Elsevier B.V. All rights reserved. Keywords: Drinking water; (Bio)fouling; Cleaning; Nanofiltration; Reverse osmosis; Membrane Fouling Simulator 1. Introduction High pressure membrane filtration processes, reverse osmo- sis (RO) and nanofiltration (NF), produce drinking water of high quality, virtually free of pathogenic micro-organisms and (in)organic pollutants. The global drinking water demand is increasing and also regulations on drinking water quality become stricter. Because of the decreasing costs of membrane applications, an increasingly important role is predicted for membrane filtration in the future [1]. A serious problem in membrane filtration applications is membrane fouling, resulting in an increase of the normalized pressure drop and/or reduction of normalized flux. Such prob- lems cause a significant increase of operational costs – up to ∗ Corresponding author. Present address: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Tel.: +31 58 2846200; fax: +31 58 2846202. E-mail address: hans.vrouwenvelder@wetsus.nl (J.S. Vrouwenvelder). 50% of the total costs [2] – and may endanger the continu- ity of (drinking) water supply. Moreover, fouling will increase the use of cleaning chemicals and consequently introduce a waste problem. The major fouling mechanisms of RO and NF membranes are scaling, particulate and organic fouling and bio- fouling. Scaling by inorganic compounds is usually controlled using a scale-inhibitor, such as a polymer or an acid. Particulate fouling can be controlled by pre-treatment, such as ultrafiltra- tion. Thus, all types of fouling except biofouling and organic fouling – possibly related types of fouling – are controllable. Biofouling is considered the major problem in RO and NF at the moment [3–5]. In practice, the fouling problem may be even more complex because of possible interactions of different foul- ing types. Prevention of membrane fouling requires intensive pre- treatment, increasing the costs of water treatment. Consequently, research into the membrane fouling potential of raw water can be cost effective. But also membrane selection, use of chemicals and cleaning strategies can help to control fouling. 0376-7388/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2006.03.046