Application of a CFD Design Approach for Chemical Disinfection Processes

Current approaches for disinfection process design involve application of a C*T (concentration*time) concept or the Integrated Disinfection Design Framework (IDDF) This study demonstrates the application of a new design approach employing computational fluid dynamics (CFD) for optimization of chemical disinfection processes. CFD models were developed to predict flow structure, mass transport, disinfectant decay and microbial inactivation in a continuous-flow contactor. C*T and Giardia log inactivation credits were estimated for the contactor for varying process conditions based on Surface Water Treatment Rule (SWTR) criteria and compared with predicted and experimental Giardia inactivation data. In general, SWTR inactivation credits were much lower than predicted and actual inactivation performance. The CFD based process design approach can be used to reduce required disinfectant doses while still maintaining adequate disinfection, resulting in lower chemical costs and disinfectant by-product formation.