1. Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, Amsterdam, GE 1090, The Netherlands
2. KWR Water Research Institute, P.O. Box 1072, Nieuwegein, BB 3430, The Netherlands
3. Centre for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Ghent University, Frieda Saeysstraat 1, Gent 9052, Belgium