Computational fluid dynamics (CFD) modeling applied to biological wastewater treatment systems: An overview of strategies for the kinetics integration

Abstract

Kinetics and CFD modeling is widely used for the study of biological treatment systems. This work reviews publications from 2006 to 2023 and compares the strategies applied to integrate the fluid dynamics and kinetics modeling. The identified strategies are grouped into three categories: a) the CFD coupled with the kinetics: mostly prohibitive in terms of its computational cost unless severe simplifications are imposed at the expense of the validity of the results; b) the CFD uncoupled from the kinetics: less computationally expensive, nonetheless, not suitable for real-time simulations. In this category, the time-step sub-cycling strategy is recommended for design modeling purposes; and c) the modeling with indirect coupling: using a CFD-based compartmental model, can get an accurate integration of the kinetics and fluid dynamics with the least computational cost. This strategy is a feasible option for real-time applications.