1. Researcher, Dept. of Water Supply Engineering, National Institute of Public Health, 2-3-6 Minami, Wako-shi, Saitama 351-0197 Japan.
2. Professor, Dept. of Chemical Engineering, Waseda Univ., 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan (corresponding author).
3. Associate Professor, Dept. of Civil and Environmental Engineering, Akita National College of Technology, 1-1 Iijima Bunkyo-cho, Akita 011-8511, Japan.
4. President, Center for Environmental Science in Saitama, 914 Kamitanadare, Kisai-machi, Saitama 347-0115, Japan.