Simulation of fluid and shear stress behaviors in reciprocating membrane bioreactors for fouling control using fluid–structure interaction analysis

In this study, fluid–structure interaction simulations of a reciprocating membrane bioreactor were performed under various conditions. The reactor and membrane module were configured in a reactor-scale. The shear stress on the tensioned membrane is governed by the fluids it repels. With reciprocating speeds of 10, 20, and 30 cm/s, the maximum shear stresses within one cycle were 3.03, 3.74, and 1.14 N/m², respectively. Excessively high speed prevented the fluid from accelerating and dispersing, resulting in a low shear stress. For triangle, sine, and square motions, the maximum shear stresses were 0.92, 3.74 and 4.36 N/m², respectively. This suggests that both acceleration and deceleration in motion are critical for generating high shear stress. When the slack increased from 0 to 0.5 and 1%, the maximum shear stress decreased from 3.74 to 2.11 and 1.2 N/m², respectively, owing to the decrease in membrane tension. The results of this study should be considered when attempting to increase fouling removal effects reciprocating membrane bioreactor.