Computational fluid dynamics applications for wastewater treatment bioreactor: emerging role of the lattice Boltzmann method

Abstract

With the continuous expansion of global urbanization and industrialization, the discharge volume of wastewater has surged sharply, and efficient, stable and low-consumption wastewater treatment (WWT) has become a core link to ensure ecological environment security and sustainable social development, which puts forward higher requirements for the design and performance optimization of WWT bioreactors. In this context, scientific and rational design of WWT systems is particularly critical, as it directly determines the operational stability, treatment efficiency and economic benefits of the entire purification process. Computational fluid dynamics (CFD) has become an essential numerical tool for the design, analysis and optimization of WWT bioreactors. In this review, the research trends of conventional CFD applications are systematically examined, and their evolution from single-phase flow analysis to the integration of mass transfer, multiphase flow modeling and biokinetics is traced. Key achievements in reactor structure optimization, aeration characteristics, mass transfer efficiency, and treatment performance prediction are comprehensively summarized. Meanwhile, the growing demand for precise modeling of microscopic phenomena such as biofilm microstructure, bubble behavior, and micro-floc dynamics has highlighted the need for a new numerical analysis paradigm. The lattice Boltzmann method (LBM) is presented as a compelling alternative. Its fundamental principles and methodological advantages are outlined, particularly in handling complex boundary conditions, simulating multiphase flows, and achieving high parallel efficiency. By reviewing LBM applications in related bioprocesses including hydrogen-producing reactors and cell culture systems, we assess the potential applicability of LBM to WWT bioreactors. Finally, future directions, emerging opportunities, and key challenges that must be addressed for the practical adoption of LBM in WWT bioreactor modeling are discussed. This review is intended to contribute to the advancement of the field by providing a comprehensive perspective on both the achievements of conventional CFD and the promise of LBM in WWT bioreactor simulation.