Author(s): Athanasios Angeloudis; Thorsten Stoesser; Roger A. Falconer
Keywords: Contact Tanks; Water Disinfection; CFD; By-Products.; Pathogen Inactivation
Abstract: The performance assessment of water disinfection contact tank (CT) facilities largely relies on Hydraulic Efficiency Indicators (HEIs) extracted from experimentally derived Residence Time Distribution (RTD) curves. This approach has more recently been aided with the application of Computational Fluid Dynamics (CFD) models, which can be calibrated to predict accurately RTDs, enabling the assessment of disinfection facilities prior to their construction. Despite the advances of experimental and computational analyses, the CT design does not directly take into consideration the disinfection chemistry which needs to be optimized process, as long as it relies on HEIs. In this study a three-dimensional steady-state CFD approach is set-up with appropriately selected kinetic models, describing the processes of disinfectant decay, pathogen inactivation and the formation of potentially carcinogenic Disinfection By-Products (DBPs). Initially, the hydraulic performances of three CT designs using experimental and computational data are reviewed. In turn, the same design configurations are tested using numerical techniques, featuring kinetic models that enable the quantification of disinfection operational parameters. Results highlight that the optimization of hydraulic efficiency facilitates more uniform disinfectant contact times, which correspond to greater levels of pathogen inactivation and a more controlled by-product accumulation.