AWWA ACE99417

The US Environmental Protection Agency Water Treatment Plant (WTP) model was developed in 1992 and used to support the Disinfectants/Disinfection Byproducts Rule Reg/Neg process in 1993-94. However, the current version of the model is limited in several ways. The objectives of this work are to extend the WTP model by adding new algorithms and to verify the model by comparison to data collected for the Information Collection Rule. The following process, inactivation, disinfection byproduct (DBP) formation and disinfectant decay algorithms, that are already part of the WTP model, were modified to reflect the advancements of the last five years: coagulation, softening, granular activated carbon, membranes, Giardia inactivation - high pH and alternative disinfectants, THM formation - total and individual, HAA formation - total (HAA5, HAA6 & HAA9) and individual species, chlorine decay, and chloramine decay. Several new process, inactivation, DBP formation and disinfectant decay algorithms need to be developed to extend the WTP model to more complete coverage of existing treatment practice, as well as extend it to include alternative treatment practices that may be more fully utilized in the future.