1. TAUW Infra Consult, P.O. Box 479, 7400 AL Deventer, The Netherlands
2. Department of Environmental Engineering, Technical University of Denmark, Building 115. DK-2800 Lyngby, Denmark
3. Organisation for Sewage Works New Technology, Ikebukuro Chitose Building, Nishiikebukoro 1-22-8, Toshimaku, Tokyo 171. Japan