Background & Objectives: E. coli is an opportunistic and pathogenic bacterium in human. It is a fecal contamination indicator of the water. The aim of this study is to investigate the efficiency of ultra violet radiation in disinfection of E. coli in aquatic environments in a batch system.

  Methods: At first, reactor was designed and made. The effects of pH, exposure time and initial inoculum were studied. Kinetic parameters were obtained by application of zero, first and second - order equations .

  Results: The result showed that removal efficiency decreased with increase of initial inoculum�and the kinetics of disinfection was described by first-order model. The result also showed that removal efficiency augmented with increasing exposure time and pH .

  Conclusion: The results of this study shows that ultra violet radiation can be used as an effective disinfection method for E. coli in aquatic environments.