1. Helmholtz Zentrum München, Institute for Groundwater Ecology, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany, Flemish Institute for Technological Research (VITO), Separation and Conversion Technology, Boeretang 200, 2400 Mol, Belgium, Catholic University of Leuven, Division Soil and Water Management, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium and Umwelt-und Ingenieurtechnik GmbH (UIT), Zum Windkanal 21, 01109 Dresden, Germany