AWWA WQTC71469

This powerpoint presentation begins by providing a brief overview of heterotrophic bacteria and its relationship to bulk water. There were two study objectives, the first was to determine the conditions when the presence of bulk water heterotrophic plate count (HPC) bacteria is favored over the presence of biofilm HPC bacteria. Data collection included: biofilm HPC; bulk water HPC; bulk water chlorine; and, bulk water AOC. The effect of chlorine residual on bulk and biofilm bacteria concentration in terms of bacteria counts and ratio is presented, along with the effect of residence time on bulk and biofilm bacteria concentration in terms of ratio. The second study objective was to develop mechanistic models that can simulate how residence time, chlorine concentration, and water velocity influence the fraction of HPC bacteria in biofilms relative to their presence in bulk water. A comparison was done between a completely mixed flow reactor (CMFR) model vs. a plug flow reactor (PFR) model. Includes table, figures.