Spectroscopic characterisation of dissolved organic matter changes in drinking water treatment: From PARAFAC analysis to online monitoring wavelengths Yulia Shutova a , Andy Baker b , John Bridgeman c , Rita K. Henderson a,d, * a UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia b Connected Waters Initiative Research Centre, The University of New South Wales, Sydney, NSW 2052, Australia c School of Civil Engineering, University of Birmingham, Birmingham, UK d School of Chemical Engineering, The University of New South Wales, Sydney NSW 2052, Australia article info Article history: Received 23 October 2013 Received in revised form 22 January 2014 Accepted 26 January 2014 Available online 7 February 2014 Keywords: Coagulation Dissolved organic carbon Drinking water treatment Fluorescence excitation emission matrix (FEEM) SUVA abstract Organic matter (OM) causes many problems in drinking water treatment. It is difficult to monitor OM concentrations and character during treatment processes due to its complexity. Fluorescence spectroscopy is a promising tool for online monitoring. In this study, a unique dataset of fluorescence excitation emission matrixes (EEMs) (n ¼ 867) was collected from all treatment stages of five drinking water treatment plants (WTPs) situated in diverse locations from subtropical to temperate climate. The WTPs incorporated various water sources, treatment processes and OM removal efficiencies (DOC removal 0%e68%). Despite these differences, four common fluorescence PARAFAC components were identi- fied for characterisation of OM concentration and treatability. Moreover, fluorescence component ratios showed site-specific statistically significant correlations with OM removal, which contrasted with correlations between specific UV absorbance at 254 nm (SUVA) and OM removal that were not statistically significant. This indicates that use of fluorescence spectroscopy may be a more robust alternative for predicting DOC removal than UV spectroscopy. Based on the identified fluorescence components, four optical lo- cations were selected in order to move towards single wavelength online OM monitoring. ª 2014 Elsevier Ltd. All rights reserved. 1. Introduction Over recent decades, researchers have highlighted increasing dissolved organic carbon (DOC) concentrations in fresh water sources in the Northern Hemisphere (Clark et al., 2010; Monteith et al., 2007). These long-term increases, along with seasonal variations and high organic matter (OM) surges during extreme weather events, are presenting challenges during drinking water treatment operation, and particularly process control and optimisation, with respect to ensuring that drinking water quality guidelines are met (Worrall et al., 2002; Matilainen et al., 2011). The OM found in drinking water sources is a heterogeneous mixture of organics of * Corresponding author. Tel.: þ61 293855383. E-mail address: r.henderson@unsw.edu.au (R.K. Henderson). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/watres water research 54 (2014) 159 e169 0043-1354/$ e see front matter ª 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.watres.2014.01.053