| Title |
Investigation on the repair of indicator microorganisms after UV irradiation for agricultural reuse of secondary effluent |
| Authors |
윤춘경 ( Yun Chun Gyeong ) ; 황하선 ( Hwang Ha Seon ) ; 정광욱 ( Jeong Gwang Ug ) ; 함종화 ( Ham Jong Hwa ) |
| Keywords |
Photoreactivation; Dark repair; UV disinfection; UV dose; Total coliform; Fecal coliform; Escherichia coli |
| Abstract |
A pilot study was performed to examine the repair of indicator microorganisms after UV irradiation for agricultural reuse of reclaimed water. The effluent of biofilter for 16-unit apartment was used as input to the UV disinfection system, and average SS and BOD concentration were 3.4 and 5.9 mg/L, respectively. and the mean level of total coliform was in the range of 1.0×10₄MPN/100mL. Two UV doses of 6 and 16 mW·s/㎠ were applied and microorganism repair was monitored under the dark, photoreactivating light, and sun light. Microorganism repair was observed in the UV dose of 6 mW·s/㎠ , and numbers increased up to 5% at the photoreactivating light and 1 % at the dark. However, microorganisms were inactivated rather than reactivated at the sun light and numbers decreased to non-detectible level in 4 hours. In the case of 16 mW·s/㎠ , microorganism repair was not observed indicating that UV dose might affect the repair process. Therefore, concerns associated with microorganism repair could be controlled by sufficient UV dose application. Agricultural reuse of reclaimed water might be even less concerned due to exposure to the sun light which could further inactivate microorganisms. The pilot study result is encouraging, however, sanitary concern in water reuse is so critical that more comprehensive investigation is recommended. |