Activated sludge model (ASM) based modelling of membrane bioreactor (MBR) processes: A critical review with special regard to MBR specificities A. Fenu a, *, G. Guglielmi b,1 , J. Jimenez c , M. Spe`randio d,e,f , D. Saroj g , B. Lesjean h , C. Brepols i , C. Thoeye a , I. Nopens j a Aquafin NV, Department of Research and Products Development, Dijkstraat 8, 2630 Aartselaar, Belgium b Department of Civil and Environmental Engineering, University of Trento, Via Mesiano, 77 e 38100, Trento, Italy c Anjou Recherche, Veolia Eau, Chemin de la Digue, BP 76, 78 603 Maisons Laffitte Cedex, France d Universite´ de Toulouse; INSA, UPS, INP; LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France e INRA, UMR792 Inge´nierie des Syste`mes Biologiques et des Proce´de´s, F-31400 Toulouse, France f CNRS, UMR5504, F-31400 Toulouse, France g Department of Urban Water and Sanitation, UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, Netherlands h Kompetenzzentrum Wasser Berlin, Cicerostr. 24, 10709 Berlin, Germany i Erftverband, Am Erftverband 6, D 50126 Bergheim j BIOMATH, Department of Applied Mathematics, Biometrics and Process Control, Ghent University, Coupure Links 653, 9000 Gent, Belgium article info Article history: Received 7 October 2009 Received in revised form 9 April 2010 Accepted 3 June 2010 Available online 11 June 2010 Keywords: Membrane bioreactors (MBR) Modelling Activated sludge models Kinetic parameters Influent fractionation Soluble microbial products (SMP) Exo polymeric substances (EPS) abstract Membrane bioreactors (MBRs) have been increasingly employed for municipal and indus- trial wastewater treatment in the last decade. The efforts for modelling of such wastewater treatment systems have always targeted either the biological processes (treatment quality target) as well as the various aspects of engineering (cost effective design and operation). The development of Activated Sludge Models (ASM) was an important evolution in the modelling of Conventional Activated Sludge (CAS) processes and their use is now very well established. However, although they were initially developed to describe CAS processes, they have simply been transferred and applied to MBR processes. Recent studies on MBR biological processes have reported several crucial specificities: medium to very high sludge retention times, high mixed liquor concentration, accumulation of soluble microbial products (SMP) rejected by the membrane filtration step, and high aeration rates for scouring purposes. These aspects raise the question as to what extent the ASM framework is applicable to MBR processes. Several studies highlighting some of the aforementioned issues are scattered through the literature. Hence, through a concise and structured overview of the past developments and current state-of-the-art in biological modelling of MBR, this review explores ASMebased modelling applied to MBR processes. The work aims to synthesize previous studies and differentiates between unmodified and modified applications of ASM to MBR. Particular emphasis is placed on influent fractionation, bio- kinetics, and soluble microbial products (SMPs)/exo-polymeric substances (EPS) modelling, * Corresponding author. Tel.: þ32 3450 4511. E-mail addresses: alessio.fenu@aquafin.be (A. Fenu), giuseppe.guglielmi@ing.unitn.it (G. Guglielmi), julie.jimenez@veolia.com (J. Jimenez), mathieu.sperandio@insa-toulouse.fr (M. Spe` randio), d.saroj@unesco-ihe.org (D. Saroj), boris.lesjean@kompetenz- wasser.de (B. Lesjean), christoph.brepols@erftverband.de (C. Brepols), chris.thoeye@aquafin.be (C. Thoeye), ingmar.nopens@ ugent.be (I. Nopens). 1 Present address: E.T.C. Engineering srl, Via Praga, 7, 38121 Trento, Italy. Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/watres water research 44 (2010) 4272 e4294 0043-1354/$ e see front matter ª 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.watres.2010.06.007