1. 1) Ministry of Environmental，Uniform drainage standard，http://www.env.go.jp/water/impure/haisui.html
2. 2) Study group on water problem，Actual condition of water pollution，http://mizukk.net/mondai/mondai01-osen/
3. 3) K.Hori, “Application of Biofilms to Green Technology”, MEMBRANE, Vol.42, No.2, pp.54-59(2017).
4. 4) Y．Ogata，“Microorganisms and their use”，Corona Company，pp.5-8(1997).
5. 5) M．Kitagawa，“Characteristics and chronology of development in aerobic bio-treatment technology”，Ebarajihou，No.228(2010-7).