Modelling of hydrodynamic characteristics in anaerobic baffled reactors: A systematic review

Anaerobic baffled reactors (ABRs), as a form of anaerobic digestion technology, have gained attention due to their potential to enhance bioenergy production and improve wastewater treatment efficiency. However, significant gaps remain in understanding the intricate flow patterns and biochemical interactions and optimising ABR design and operation. Recent advancements in Computational Fluid Dynamics (CFD) techniques, such as turbulence, have contributed to more accurate simulations of these processes in ABRs. Nevertheless, critical gaps in current modelling approaches necessitate an up-to-date systematic literature review. This paper aims to identify trends, advances, and challenges in the numerical and physical modelling of ABRs. Using Scopus and Engineering Village databases, articles published between 1990 and 2024 were selected based on relevance to ABR modelling, specifically those utilising CFD and statistical models.
The analysis revealed significant trends and limitations in current research methodologies. It was found that 75 % of the studies employed multi-chamber reactors with vertical baffles and used low-concentration wastewater to validate their models, which may limit the applicability of findings to situations involving high-concentration wastes. Despite the prevalence of these settings, only 25 % of the studies made significant changes to the experimental models, suggesting a potential area for enhancement in reactor optimisation. Additionally, 50 % of the studies employed CFD to investigate hydrodynamic modelling without considering integrated biochemical reactions. This highlights a significant gap in using advanced modelling techniques to explore biological and chemical processes. The insights gained from this review can enhance the understanding of physical mechanisms in ABR technology and identify critical research challenges.