1. Department of Civil and Environmental Engineering, University of California at Davis Davis, CA 95616, USA
2. Bureau of Sewerage, Tokyo Metropolitan Government 2-8-1 Nishi-Shinjuku, Shinjuku, Tokyo 163-01, Japan
3. Sewage Works Bureau, Fukuoka City, 8-1, Tenjin 1-chome Chuo-ku, Fukuoka 810, Japan