Ultra-filtration (UF) is a membrane separation technology that purifies and separates solutions. The
ultrafiltration membrane system is a solution separation device in which an ultrafiltration membrane is
used as a filter medium and a pressure difference on both sides of the membrane is a driving force. The
ultrafiltration membrane only allows the solvent (such as water molecules), inorganic salts and small
molecular organic substances in the solution to pass through, and the macromolecular substances such
as suspended matter, colloid, protein and microorganisms in the solution are intercepted, thereby
purifying or separating.
Ultrafiltration membranes are used extensively in water treatment projects. Ultrafiltration technology plays
an increasingly important role in the fields of reverse osmosis pretreatment, drinking water treatment, and
reuse of water. Ultrafiltration technology plays a key role in the sterilization and turbid removal of alcohol
and beverages, the depyrogenation of pharmaceuticals, and the concentration of foods and
pharmaceuticals.
The form of the ultrafiltration membrane can be divided into two types, a plate type and a tube type. The
tubular ultrafiltration membrane is further classified into hollow fiber, capillary tube and tube type
according to the diameter of the tube. The ultrafiltration membranes used for water treatment on the
market are basically capillary type, and the hollow fiber (inner diameter 0.1-0.5 mm) polyethylene or
polypropylene microporous membrane used in individual projects should actually belong to the
microfiltration membrane.
The assembly of ultrafiltration membrane filaments into a module that can be coupled to an ultrafiltration
system is referred to as an ultrafiltration membrane module. The ultrafiltration membrane modules are
classified into three types: internal pressure type, external pressure type and submerged type. The
driving force of the immersion ultrafiltration membrane filtration is the pressure difference between the
vacuum inside the membrane tube and the atmospheric pressure. For ultrafiltration membranes with high
filtration accuracy, this pressure difference is usually not easy to meet the required filtration driving force,
so the submerged component form is suitable for ultrafiltration membranes or microfiltration membranes
with low filtration precision. When the external pressure type ultrafiltration is used in the forward and
reverse strokes, the flow rate of the liquid on the surface of the membrane is extremely uneven, which
affects the flushing effect on the surface of the membrane. Therefore, the ultrafiltration membrane
commonly used for water treatment or the internal pressure type component structure has advantages.
