Transient CFD modeling of toluene waste gas biodegradation in a gas–liquid–solid three-phase airlift loop reactor by immobilized Pseudomonas putida

The biotreatment of toluene was studied in a gas–liquid–solid three-phase airlift loop reactor (ALR) using the CFD method. A transient 3D CFD model was developed for the simulation including the k–ɛ turbulence model, interphase forces, momentum and mass transfer, bubble coalescence and breakup, and the bioreaction. The validation was done by the liquid phase axial velocity from hydrodynamic experiment and the dissolved toluene and removal efficiency concentrations from the toluene treatment experiment. The CFD simulations agreed well with the experiment data. Hydrodynamics and local dispersions of components in ALR were predicted by the verified model. The rate-limiting step was also discussed by quantitative comparison between mass transfer rate and bioreaction rate. Optimized simulation had been done based on the rate-limiting step and had found that the decreased solid bead diameter could effectively improve the removal efficiency.

• Biodegradation of toluene waste gas by immobilized cells in ALR was simulated.
• The simulation was done by a reliable transient 3D G–S–L 3-phase CFD model.
• The model quantitatively compared mass transfer rate and bioreaction rate.
• Simulated removal efficiency was improved with decreased beads’ diameter.