1. Institute of Environmental Engineering, ETH Zurich, Wolfgang-Pauli-Strasse 15, 8093 Zurich, Switzerland, Agrosphere ICG-IV, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany, Waterworks Zurich, Hardhof 32, 8064 Zurich, Switzerland, and TK Consult, Seefeldstrasse 285, 8008 Zurich, Switzerland