Presented at the EuroMed 2004 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 Office National de l’Eau Potable, Marrakech, Morocco, 30 May–2 June, 2004. 0011-9164/04/$– See front matter © 2004 Elsevier B.V. All rights reserved Desalination 168 (2004) 265–270 Selection of the most suitable ultrafiltration membrane for water disinfection in developing countries J.M. Arnal, M. Sancho*, G. Verdú, J. Lora, J.F. Marín, J. Cháfer CChemical and Nuclear Engineering Department, Polytechnic University of Valencia, Camino de Vera s/n 46022 Valencia, Spain email: msanchof@iqn.upv.es Received 13 February 2004; accepted 20 February 2004 Abstract One of the most critical problems in developing countries is the lack of drinking water. People in these regions are supplied with surface water, which contains a significant amount of microorganisms that can cause several diseases. In fact, one of the main causes of infantile mortality is the high incidence of diarrhoeic diseases and other illnesses related to impure drinking water. Ultrafiltration (UF) is a pressure-driven membrane process that separates on the basis of size and can remove bacteria and viruses from water. Therefore, UF can be applied for disinfecting water, avoiding some illnesses or epidemics where people consume ultrafiltrated water. The Chemical and Nuclear Engineering Department of the Polytechnic University of Valencia in Spain is working in cooperation with a non-governmental organisation to develop a system to make water drinkable in a region of Ecuador. The system consists of an UF plant with one spiral-wound module, equipped with a pressure pump driven by a petrol engine. Before the application of the process, the UF plant has to be completely tested and fine-tuned in order to assure that it will successfully perform once in Ecuador. One of the stages of these preliminary tests was the selection of the most suitable UF membrane from the point of view of kind of material and cut-off, bearing in mind the following points: quality of ultrafiltrated water, performance conditions, membrane fouling and cleaning and maintenance conditions. This paper describes the preliminary tests carried out with different UF membranes to select the most suitable one for disinfecting surface water. Keywords: Ultrafiltration; Disinfection; Potabilisation; Developing countries 1. Introduction One of the most critical problems in develop- ing countries is the lack of drinking water. As a *Corresponding author. consequence, people in these regions are usually supplied with water from rivers, lakes, etc., which contain a significant amount of microorganisms that can cause several diseases. In fact, one of the main causes of infantile mortality in these regions