Influence of Interfacial Forces on the Mixture Prediction of an Anaerobic Sequencing Batch Reactor (Asbr)

Abstract

-In the operation of bioreactors, the fluid movement promotes mixing between sludge and substrate. The dynamics of this system are complex, and the interaction between the phases is difficult to evaluate accurately. In this work, Computational Fluid Dynamics is applied to simulate a pilot-scale anaerobic sequencing batch reactor, using a three-dimensional, transient and multiphase modeling. Several correlations were applied to estimate the interfacial forces. Results indicate that the use of different coefficients for the drag and lift forces strongly affects the predicted turbulent kinetic energy, and thus the mixture estimation in the bioreactor. The use of the drag as the only interfacial force provided an average turbulent kinetic energy close to the value found using a more complete model. However, the absence of lift and virtual mass forces had a significant impact on the resulting turbulence distribution.

Simulation of two‐phase air–liquid flows in a closed bioreactor loop: Numerical modeling, experiments, and verification

“…Below is the complete system of equations of the mathematical model in accordance with Rosa et al 38 The mass transfer coefficient for bubble flow is the ratio of the specific mass flow of air at the phase interface to the difference in air concentrations at the phase interface and away from it:…”

“…Below is the complete system of equations of the mathematical model in accordance with Rosa et al 38 The mass transfer coefficient for bubble flow is the ratio of the specific mass flow of air at the phase interface to the difference in air concentrations at the phase interface and away from it: $$$$ K=\frac{J_d}{Y_{\mathrm{air},s}-{Y}_{\mathrm{air},b}},\kern0.30em K=\frac{J}{\rho_{LIQ}\left({Y}_S-{Y}_b\right)}=\frac{J_d}{\left({Y}_S-{Y}_b\right)}. $$$$ …”

“…Here, $$$ {C}_{L\mathrm{factor}} $$$ is the model constant, and $$$ \sqrt{S} $$$ is a scalar quantity characterizing the local velocity gradient of the fluid. The expression () is based on the Saffman model 38,39 . The latter multiplier takes into account the particle cloud effect similar to model () for the drag coefficient.…”

“…The expression ( 8) is based on the Saffman model. 38,39 The latter multiplier takes into account the particle cloud effect similar to model ( 6) for the drag coefficient. The lift action begins at a distance of D L from the wall.…”

Hydrodynamics Analysis of Mixing Process in Fermenter

“…Diverse bioreactor designs and impeller types have been offered to optimize mass transfer. Examples of reactor designs include single and multiple impellers, semi-partition bioreactors, single-use bioreactors, and membrane bioreactors [3][4][5][6][7][8]. In addition to the various bioreactor designs, numerous impeller kinds were recommended, using Rushton turbine and counter rotation U-shape impellers [9,10].…”