METHOD FOR STERILIZING SEWAGE DISPOSAL WATER

PURPOSE:To decolor sewage disposal water and to exhance sterilization effect by preventing ultraviolet rays(UV) from being absorbed in colored substance when the UV irradiates by applying ozone treatment to sewage disposal water at a stage before UV irradiation is applied in equipment in the case the sterilization of the sewage disposal water before discharge is performed by the irradiation of the UV. CONSTITUTION:After sludge 3 is sedimented in a sedimentation basin 2, the supernatant liquid of activated sludge 1 is sent to a UV sterilization tank 4, and it is sterilized by applying the UV irradiation by a UV lamp 5. Displosal water is discharged to a river, etc., as discharge water 6. In such a case, an ozone reaction tank 7 is installed at the front stage of the UV sterilization tank 4. The ozone reaction tank 7 performs the ozone treatment of the disposal water by discharging ozonized air generated by an ozone generator 7A to the disposal water by a duffuser pipe 7B and an unreacting ozone is discharged to the air after being decomposed by an exhaust ozone decomposing tower 7C. The following UV sterilization can be effectively performed by performing the decoloring by the ozone treatment in such way.