Modelling techniques for chemical disinfection reactors: from IDDF to CFD

Abstract

Disinfection process plays a crucial role in water and wastewater treatment and an important tool to support design and optimization of this unit is process modeling, based on a conventional approach, as Integrated Disinfection Design Framework (IDDF), or an emerging advanced approach, as Computational Fluid Dynamics (CFD). In the present work, the two modeling techniques, IDDF and CFD, were applied to the modeling at pilot scale of an open chicane reactor, their performances in disinfection process description were compared and a sensitivity analysis on the fundamental operating and kinetic parameters was carried out. The first part of the work focused on the proper application of the two modeling techniques, using available experimental data for calibration purposes, while in the second part, the two modeling techniques were compared. Both the approaches proved to be effective tools if reliable experimental data are available, being essential for model calibration and proper application. The choice of the most suitable approach is not univocal, but it is basically related to the aim of the work and to the availability of computational resources. A simplified approach as IDDF proved to be an effective tool to estimate the phenomena involved in sodium hypochlorite decay, disinfection performance and disinfection by-products formation, but it neglects any information about local effects, unlike CFD, being their identification crucial to determine and quantify possible sources of non-ideality.