Identifying fouling events in a membrane-based drinking water treatment process using principal component analysis of fluorescence excitation-emission matrices Ramila H. Peiris a , Cynthia Halle ´ b , Hector Budman a , Christine Moresoli a , Sigrid Peldszus b , Peter M. Huck b , Raymond L. Legge a, * a Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada b NSERC Chair in Water Treatment, Department of Civil and Environmental Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada article info Article history: Received 25 May 2009 Received in revised form 10 September 2009 Accepted 14 September 2009 Published online 19 September 2009 Keywords: Principal component analysis Fluorescence spectroscopy Membrane fouling Drinking water treatment Nanofiltration Ultrafiltration abstract The identification of key foulants and the provision of early warning of high fouling events for drinking water treatment membrane processes is crucial for the development of effective countermeasures to membrane fouling, such as pretreatment. Principal foulants include organic, colloidal and particulate matter present in the membrane feed water. In this research, principal component analysis (PCA) of fluorescence excitation-emission matrices (EEMs) was identified as a viable tool for monitoring the performance of pre- treatment stages (in this case biological filtration), as well as ultrafiltration (UF) and nanofiltration (NF) membrane systems. In addition, fluorescence EEM-based principal component (PC) score plots, generated using the fluorescence EEMs obtained after just 1 hour of UF or NF operation, could be related to high fouling events likely caused by elevated levels of particulate/colloid-like material in the biofilter effluents. The fluores- cence EEM-based PCA approach presented here is sensitive enough to be used at low organic carbon levels and has potential as an early detection method to identify high fouling events, allowing appropriate operational countermeasures to be taken. ª 2009 Elsevier Ltd. All rights reserved. 1. Introduction Membrane treatment of surface and ground water by means of ultrafiltration (UF) and nanofiltration (NF) is increasingly being used as an option for the production of drinking water. However, implementation of these membrane-based processes for drinking water treatment is often constrained due to fouling, which may be caused by organic, inorganic, colloidal and particulate matter. In drinking water UF and NF applications, natural organic matter (NOM) is considered to be the major membrane foulant (Saravia et al., 2006; Jermann et al., 2007). NOM consists of a complex mixture of humic and fulvic acids, proteins, and carbohydrates of various molecular size and functional groups (Her et al., 2003). Characterization of membrane foulant fractions in NOM such as humic substances (HS) and biopolymers (protein and polysaccharides) is indispensable for understanding membrane fouling and for the development of fouling control strategies (Amy, 2008). Application of fluorescence spectroscopy as a tool for characterizing NOM is well documented (Coble et al., 1990; * Corresponding author. Fax: þ519 746 4979. E-mail address: rllegge@engmail.uwaterloo.ca (R.L. Legge). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/watres 0043-1354/$ – see front matter ª 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.watres.2009.09.036 water research 44 (2010) 185–194