A control methodology for the feed water temperature to optimize SWRO desalination process using genetic programming Seung Joon Kim a , Sanghoun Oh b , Young Geun Lee a , Moon Gu Jeon b , In S. Kim a,b , Joon Ha Kim a,c,d, * a Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712, Korea b Department of Information and Communications, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712, Korea c Center for Seawater Desalination Plant, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712, Korea d Sustainable Water Resource Technology Center, GIST, Gwangju, 500-712, Korea Tel. 82-62-970-3277, e-mail:joonkim@gist.ac.kr Received 13 November 2008; revised 17 December 2008; accepted 24 December 2008 Abstract This paper presents a novel methodology to determine an optimized control method for feed water temperature in a seawater reverse osmosis (SWRO) desalination process using genetic programming (GP) which is an evolutionary algorithm used to fnd functional forms through training data. Two functional models were determined by GP with operation data collected over four years from Fujairah SWRO plant. The models showed high accuracy (>99.0%) in terms of the average error rate between the observed and the predicted values. The frst model involved the permeate water fow rate with a functional temperature correction factor (TCF), water transfer coefcient, and net driving pressure (NDP) and the second is the salt passage ratio with a functional TCF, salt transfer coefcient, and total dissolved solids (TDS) in the feed. To determine the optimized control of the feed water temperature, a new control methodology with the two functional models was proposed and applied to a simulation of the feed water temperature, which showed better performance in terms of the permeate fow rate. Applying the optimized control of feed water temperatures to a plant under identical operational conditions, it was found that the permeate fow rate could be increased by approximately 900 m 3 /day under a steady condition of 600 ppm in permeate TDS. Keywords: Seawater reverse osmosis (SWRO); Desalination; Temperature correction factor (TCF); Temperature control; Genetic programming (GP); Hybrid system; Multi stage fash (MSF) *Corresponding author. Presented at the 2nd joint workshop between the Center for Seawater Desalination Plant and the European Desalination Society, Gwangju Institute of Science and Technology, Korea, October 8–9, 2008. 0011-9164/09/$– See front matter © 2009 Published by Elsevier B.V. doi:10.1016/j.desal.200 .12.024 Desalination 247 (2009) 1 1 90– 99 8