Inhibitory Effects of UV-LED Irradiation and Period in Darkness on Photoreactivation of Coliforms in Johkasou Treated Water

With the recent development of ultraviolet light emitting diodes (UV-LEDs), it is now possible to apply UV disinfection, previously used only for medium-to-large sized sewage treatment plants, Johkasou wastewater, a household wastewater system. However, known that coliforms have been inactivated by irradiation regain their activity after sunlight irradiation, etc. Therefore, in small Johkasou, where discharge channels are often open, photorecovery may occur immediately disinfection. no studies conducted investigate disinfection from Johkasou. In this study, relationship between and dose UV-LED effluent was investigated. As result, we identified amount will maximize photoreactivation effect. We also clarified suppressing effect an excessive on phenomenon. Additionally, since confirmed suppressed certain period darkness following considered can be allowing reside currently estimated residence time tank.