Uv Disinfection of Treated Wastewater Effluent: Influence of Color, Reactivation and Regrowth of Coliform Bacteria

Disinfection is a very important unit process to deactivate coliform bacteria in treated wastewater. However, regrowth potential of coliform bacteria raises human health and safety concerns associated with reuse of treated wastewater in various applications. Both post chlorination and post UV disinfection regrowth have been reported in the literature. In view of increasing use of recycled wastewater for reuse, it is necessary to address this phenomenon from both technical and regulatory standpoints. A case study of fecal coliform regrowth in a full scale operating plant is reported here. This is expected to aid in further understanding of the phenomenon and its causes so that proper technology may be selected on a case by case basis in the design of treatment plants. The results demonstrated that effectiveness of UV disinfection system is largely compromised by the presence of residual organics and color in the treated effluent.