Developments in computational fluid dynamics-based modeling for disinfection technologies over the last two decades: A review

• We summarize past CFD studies on contactors for disinfection.
• Hydraulic efficiency studies are found to be the most common and successful.
• Challenges existing in disinfection simulation are identified and discussed.
• We find turbulence-chemistry interaction is the most difficult problem to address.
• However current simulation error is mainly due to unresolved flow features.

In the last two decades, Computational Fluid Dynamics (CFD) has shown great potential as a powerful and cost-efficient tool to troubleshoot existing disinfection contactors and improve future designs for water treatment industry. However, numerous challenges in the simulation of water disinfection processes still remain. This review summarizes past CFD studies of the hydraulic and associated disinfection efficiency of disinfection contactors. Hydraulic efficiency studies based on flow and tracer transport simulation were found to be the most common and successful. Challenges existing in flow and disinfection simulation are identified and discussed. These challenges can be overcome via advanced turbulent simulation approaches, such as Large Eddy Simulation and multi-phase resolving simulations. Although turbulence-chemistry interaction is found to be the most challenging problem for proper representation of the reaction system and inactivation kinetics, solutions to this challenge can be overshadowed unless errors induced by unresolved unsteady flow and multi-phase flow are reduced sufficiently.