Backwash Efficiency Analysis of Airlift MBR Device Using CFD

Abstract

In this study, an external backwashing experiment of a flat plate membrane in which internal backwashing is impossible is conducted to derive optimal conditions for backwashing. The experiment envisioned the fabrication and process of a flat MBR column combined with the airlift mode. For backwashing, the membrane recovery rate was calculated by performing an experiment with 50 m3/m2/hr, which is the standard amount of backwashing air injected by the Ministry of Environment. After the experiment, the shear force applied to the membrane was measured through the Computational Fluid Dynamics program to calculate the optimal amount of air, so that energy consumption could be minimized. As a result of the backwashing experiment at 50 m3/m2/hr, the flux was 4.489~12.449 L/m2/hr (average 5.916 L/m2/hr) and the membrane recovery rate was 75.3~95.1% (average 89.0%). appear. After shear force analysis through CFD, the results of calculating the membrane recovery rate according to each air inflow rate were 89.0% at 50 m3/m2/hr, 71.2% at 40 m3/m2/hr, 53.4% at 30 m3/m2/hr, and 35.5 % at 20 m3/m2/hr. %, 17.2% at 10 m3/m2/hr is expected to show a membrane recovery rate. As a result, the highest shear force was shown at 50 m3/m2/hr, and it is judged that the highest shear force will be shown when the position of the separator is 45 cm from the bottom of the device. In addition, it seems that the value of shear force is high when the number of air inlets is large.