1. Research Fellow, Institute of Environmental Engineering, ETH Zurich, Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland (corresponding author).
2. Assistant Professor, Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da vinci 32, 20133 Milan, Italy.
3. Professor, Institute of Environmental Engineering, ETH Zurich, Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland.