Regrowth potential of coliforms after UV disinfection of municipal wastewater

Photoreactivation of fecal coliforms and subsequent regrowth was investigat ed in effluents of wastewater treatment plants using ultraviolet light as t he disinfectant. Shielding of bacteria ingested in Daphnia sp in the plant outfalls was shown to be a major contributor to increased fecal coliform, E . coli, fecal streptococci and enterococci after fragmentation of the Daphn ia sp due to normal dieoff. Representative fecal coliform colonies that com prised the regrowth population were identified to species with E. coli, a s mall fraction of the total fecal coliform population.