Desalination 203 (2007) 243–255 0011-9164/07/$– See front matter © 2007 Elsevier B.V. All rights reserved Presented at EuroMed 2006 conference on Desalination Strategies in South Mediterranean Countries: Cooperation between Mediterranean Countries of Europe and the Southern Rim of the Mediterranean. Sponsored by the European Desalination Society and the University of Montpellier II, Montpellier, France, 21–25 May 2006. *Corresponding author. Water quality and performance evaluation at seawater reverse osmosis plants through the use of advanced analytical tools Jérôme Leparc a *, Sophie Rapenne a,b , Claude Courties c , Philippe Lebaron c , Jean Philippe Croué b , Valérie Jacquemet a , Greg Turner d a Anjou Recherche – Veolia Water, Chemin de la Digue, 78600 Maisons Laffitte, France Tel. +33 (1) 34 93 31 33; Fax +33 (1) 34 93 31 10; email: jerome.leparc@veolia.com b LCEE/ESIP UMR CNRS 6008, Université de Poitiers, 40 avenue du recteur Pineau, 86022 Poitiers, France c Observatoire Océanologique de Banyuls, Université Pierre et Marie Curie, UMR CNRS No. 7621 and 7628, Rue Fontaulé, 66651 Banyuls-sur-Mer, France d Veolia Water Industrial Outsourcing, Blackwell House, 1 Three Valley Way, Bushey, Herts, United Kingdom Received 2 February 2006; accepted 28 March 2006 Abstract Advanced analytical tools have been developed to allow thorough characterisation of seawater samples from many aspects: (i) inorganic characterisation, (ii) characterisation of the natural organic matter, (iii) quantification of the main algal pigments (chlorophyll, pheophytin), and (iv) enumeration of phytoplankton and bacteria. These analytical tools were used at a seawater reverse osmosis plant in Gibraltar and provided valuable information to quantify the risks of fouling. Indeed, in addition to the measurement of the Silt Density Index (SDI), the results of the advanced analyses provided a detailed characterisation of the raw seawater sources (surface seawater and well seawater) as well as a thorough assessment of the pretreatment performance. Keywords: Reverse osmosis; Desalination; Seawater quality; Natural organic matter; Phytoplankton; Bacteria