Extran™ Ultrafiltration Technology:

Separation Dynamics Inc. specializes in membrane filtration and filtration of industrial waste water.  We manufacture a proven and dependable Ultrafiltration system, based on our innovative cellulose membrane technology called Extran™, which was originally developed by Johnson & Johnson for kidney dialysis.  This patented Ultrafiltration membrane efficiently removes emulsified oils from process solutions, without fouling, and returns water and soluble cleaners, for reuse or discharge to the sewer.

The Extran™ membrane is a hollow fiber type membrane made of the most hydrophilic industrial membrane material available today, regenerated curprammonium cellulose. Pure cellulose, as a membrane, is extremely versatile. The material is resistant to most organic solvents and has the unique characteristic that oils and hydrocarbons will not foul the membrane or stick to its surface. The membrane is temperature resistant up to 180 degrees Fahrenheit and can be used in pH ranges between 2 - 12.5.

Unlike many conventional ultrafiltration membranes, Extran™ has no definable surface pores to pass permeate and therefore does not require cleaning to offset pore plugging; instead, it works by a solution diffusion mechanism. Due to the naturally hydrophilic nature of the cellulose, water is highly attracted to the membrane material, and will diffuse into and through it.  Water and water-soluble constituents diffuse through the membrane as permeate while insoluble oils and hydrocarbons are naturally rejected by the smooth cellulose surface.

The Extran™ membrane module consists of thousands of hollow cellulose fibers contained in a CPVC housing.  The individual fibers have an inside diameter of 400 microns and a wall thickness of about 40 microns.  Contaminated feedwater is prefiltered, then circulated through the lumens of the fibers and the purified water diffuses through the walls, while insoluble contaminants (including emulsified oils) are rejected by the membrane and thus exits the fibers.