Post Disinfection Reactivation and Regrowth of Coliform Bacteria in Treated Wastewater Effluent

Disinfection is a very important unit operation to remove coliform bacteria from 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, which is expected to aid in further understanding of the phenomenon such that proper technology may be selected on a case by case basis in the design of treatment plants.