Flow and fouling visualization in modules having multiple multichannel membranes

Interest in multichannel membrane modules as robust alternatives to single-bore hollow fiber membranes is growing, yet their complex hydrodynamic behavior remains underexplored, particularly in densely packed configurations. In this study, we employed magnetic resonance imaging (MRI) to investigate flow distributions and fouling dynamics in multichannel membrane modules containing one, seven, and nineteen fibers. Under forward permeation at 100 LMH, we observed marked inhomogeneities on both the shell and lumen sides, which became more pronounced at higher packing densities and towards the module outlet. Notably, jet-like flow streams, reverse flows, and localized recirculation zones developed, creating substantial deviations in velocity profiles along the module axis. Fouling experiments with silica particles revealed a disproportionately reduced contribution of inner bore channels, highlighting the vulnerability of certain lumen regions to filter cake formation. Backwashing at 100 LMH and 200 LMH partially alleviated these blockages but also redistributed filter cakes to previously open bore channels. Despite some channels showing improved flux recovery, a subset of fibers remained inaccessible to cleaning due to preferential flow pathways that bypass clogged regions. These findings have important consequences for module design and operation. They underscore the need for precise control over packing density, fiber spacing, and shell connection configuration to minimize maldistribution and optimize overall hydraulic performance. Going forward, deeper investigations into reverse flow phenomena and localized pressure gradients will be critical in guiding next-generation module architectures and fouling mitigation strategies, ultimately enhancing the reliability and efficiency of membrane-based water treatment processes. • The flow inhomogeneity in lumen and shell side increases with the packing density. • At the highest packing density, channeling occurs between the multichannel fibers. • Flow inhomogeneities maximize behind the shell connection during inside-out dead-end permeation. • During filtration, the inner of the seven bore channels has reduced filtercake formation. • After the backwash, some channels reverse their flow direction.