Modeling and scaleup of reverse osmosis separation

Over the past years reverse osmosis has become a commercially attractive microsolute separation process. This success is largely due to the development of new and more reliable polymeric membrane materials and of novel module configurations. Flat-sheet membrane units are preferred for laboratory experiments to determine the intrinsic membrane properties with respect to permeate flux and separation efficiency. These units are not expensive and allow different membrane sheets to be tested with the same unit because of the easy membrane replacement. The industrial use of these units is excluded due to the low membrane surface area to volume ratio. The separation characteristics of reverse osmosis also depend to a large extent on the geometry of the membrane elements and the associated hydrodynamic phenomena. Hence, residence time distribution experiments have been performed on industrial-scale spiral-wound modules to study the flow regime. The detailed results of these experiments are reported elsewhere, and...