1. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, CH-8600 Dübendorf, Switzerland, Intermunicipal Water Company of Veurne-Ambacht (IWVA), Doornpanne 1, B-8670 Koksijde, Belgium, and Aquafin N.V., Dijkstraat 8, B-2630 Aartselaar, Belgium