1. Water Environment Research Group, Public Works Research Institute, 1-6 Minamihara, Tsukuba City, Ibaraki, Japan (E-mail: nakada55@pwri.go.jp; komori@pwri.go.jp; ysuzuki@pwri.go.jp)
2. Murata Keisokuki Service Co., Ltd., 15 Akiba town, Totsuka Ward, Yokohama City, Kanagawa, Japan (E-mail: konishi@murata-s.co.jp; houwa@murata-s.co.jp)
3. Kyoto University Graduate School, Research Center for Environmental Quality Management, 1-2 Yumihama Outsu City, Siga, Japan (E-mail: htanaka@biwa.eqc.kyoto-u.ac.jp)