Large-eddy-simulation of buoyancy-induced mixing for water treatment applications

Large-Eddy Simulation is applied to investigate the turbulent mixing produced by aeration system in wastewater treatment. The solver uses an Eulerian-Lagrangian point-particle model to couple liquid and gas phases. Transport of a passive tracer is simulated to visualize the homogeneity of mixing. The accuracy of the solver predicting the mixing of the tracer time has been validated versus experimental data in a bubble reactor with different diffuser configurations. The mixing induced by bubble screens is simulated and compared - at different flow rates - with that produced by discrete plumes. The results show significant differences in the mixing times and energetic efficiency for different aerator setups.