1. Faculty of Civil Engineering and Geosciences, Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands
2. Royal HaskoningDHV B.V., P.O. Box 1132, 3800 BC Amersfoort, The Netherlands
3. Vitens, P.O. Box 1205, 8001 BE, Zwolle, The Netherlands
4. Sub-Department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands and KWR Watercycle Research Institute, P.O. Box 1072, 4330 BB Nieuwegein, The Netherlands