MASS-TRANSFER, FLUID-FLOW AND MEMBRANE-PROPERTIES IN FLAT AND CORRUGATED PLATE HYPERFILTRATION MODULES

Concentration polarization, decreasing the efficiency in membrane separation processes, can be reduced by increasing mass transfer between membrane surface and bulk of the feed stream. Analogous to techniques used in plate heat exchangers, efforts have been made to enhance mass transfer in a plate hyperfiltration module by using a corrugated membrane instead of a flat one. The corrugations are pressed into an originally flat membrane. These corrugations have an influence not only on the mass transfer, but also on such membrane properties as salt and water permeability. Corrugations enhance mass transfer in a more effective way than increase of flow rate does. The effect of the corrugations on membrane properties shows a large spread. For corrugated membranes prepared by our group, flux increases of 100% at almost the same or even slightly higher retentions have been obtained.