title: Growth and repair potential of three species of bacteria in reclaimed wastewater after UV disinfection.
abstract: OBJECTIVE
  The growth and repair potential of three typical microorganisms in reclaimed water after UV disinfection was investigated to assess the effects of photo-reactivation and dark repair of microorganisms, and the microbial safety of reclaimed water following this procedure.
  
  
  METHODS
  The growth and repair potential of Escherichia coli, a fecal coliform strain and Bacillus subtilis in the effluent of a biological wastewater treatment plant disinfected by a low-pressure UV lamp were investigated.
  
  
  RESULTS
  Any increase in bacterial numbers in the effluent after UV disinfection was due to damage repair. Exposure to photo-reactivating light for 8-10 h after UV irradiation with a dose of 5 mJ/cm(2), the highest percentage of photo-reactivation observed for E. coli and the fecal coliform strain was 29% and 15% respectively. B. subtilis showed little photo-reactivation under these conditions. The percentage of photo-reactivation was related to the UV dose and the photo-reactivating time, and a function was developed to forecast the final concentrations of E. coli and the fecal coliform strain after UV disinfection with possible photo-reactivation.
  
  
  CONCLUSIONS
  Different species of bacteria displayed different responses to UV light and different repair potentials. The repair of indigenous bacteria in wastewater needs to be investigated in future work.
authors: School of Environment, Tsinghua University, Beijing, China.
authors: MeiTing
authors: M
authors: Guo
authors: JingJing
authors: J
authors: Huang
authors: HongYing
authors: H
authors: Hu
authors: WenJun
authors: W
authors: Liu
mesh_terms: D001412:Bacillus subtilis / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000528:radiation effects*; D013997:Time Factors; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D018508:Water Purification