CFD Modelling of Particle Transport and Biological Reactions in a Mixed Wastewater Treatment Vessel

The biological reactions utilised to remove pollutants from the wastewater occur primarily within socalled bio-catalytic particles. These biocatalysts are suspended and subsequently transported, along with soluble reactants, through the reactor vessels. The transport of particles and reactants, and the resulting pollutant removal rates, are governed by the hydrodynamics, which is determined by the reactor design. Current methods of designing treatment vessels are largely based on empirical and heuristic techniques. This makes it difficult to predict how vessel design (e.g. size and position of inlets, baffles or mixers) affects hydrodynamics, hence overall performance. Computational Fluid Dynamics (CFD) provides a method for prediction of the effect these features have on the hydrodynamics from a fundamental level. The CFD model developed here couples hydrodynamics with scalar transport equations that predict particle and reactant transport. Comparison of the CFD model with an extensive set of point velocity measurements and tracer studies is made.