1. Executive Technical Director, Ruhrverband, Kronprinzenstr. 37, D-45128 Essen, Germany (E-mail: bode@ruhrverband.de)
2. Head of the Division Wastewater Treatment, Construction and Operation, Ruhrverband, Kronprinzenstr. 37, D-45128 Essen, Germany (E-mail: pev@ruhrverband.de)
3. Head of the Department of Public Relations, Ruhrverband, Kronprinzenstr. 37, D-45128 Essen, Germany (E-mail: dal@ruhrverband.de)