Analysis on a vibration character of hollow fiber membrane bundle in MBR

We have focused on membrane vibration in MBR to find an effective design for the reduction of membrane fouling. In the previous study, we developed a direct measurement method for membrane vibration of a hollow fiber membrane (HFM) using an accelerometer (ACM). In this study, we studied on vibration characters on an HFM bundle in a practical membrane module in MBR using the ACMs in a large transparent water tank. Three ACMs were attached at the middle (P1), top (P2) and bottom (P3) position along a center line in the HFM bundle in which air was supplied from a diffuser below the membrane module with different aeration rates from 0 to 250 L/min. The acceleration of membrane vibration time series for the X-axis direction (left-right displacement) and Z-axis direction (back-front displacement) was recorded at three positions. The average vibration amplitudes of the acceleration along both directions at each position were increased as the aeration rate was increased. The HFM bundle showed a collective vibration with a frequency peak between 0 and 50 Hz. The Z-axis motion character of HFM bundle is regarded as a sheet vibration. The obtained vibration character was useful for the new design of a membrane module in MBR against the membrane fouling.