Nanofiltration selection for NOM removal: pilot and full-scale operation

Abstract

Belgium is increasingly encountering drinking water problems because of resource scarcity and because of the quality of surface water from rivers and canal, which are often highly degraded. High organic matter concentrations are found and treated water has non-satisfying organic contents. This has a direct impact on THM formation and bacteria regrowth in the supply network. With more and more stringent regulations, organic matters concentration level in drinking water must be reduced. Nanofiltration (NF) is a suitable method for organic matter removal with reduction efficiency sometimes higher than 90 % (Orecki et al. 2004). It can be more effective than conventional technologies like activated carbon adsorption (Coté et al. 1996). This is a reason for upgrading old treatment plants by using NF treatment as a polishing step. Two drinking water treatment plants located in Eupen and La Gileppe in Belgium needed to be upgraded. These both plants treat surface water from dams and are equipped with a conventional clarification. A pilot study was carried out to compare different treatment files to remove Total Organic Carbon (TOC) and Biologically Degradable Organic Carbon (BDOC). NF process has been finally chosen. The aim of the paper is to report and discuss data supporting the choice of NF from pilot scale study and next full-scale performances of both upgraded drinking water treatment plants. The whole demonstrates the interest of NF as a suitable technology organic matter removal.