The ultrafiltration spiral membranes from Alfa Laval are based on a unique construction of either polypropylene or polyester support material in a hygienic full-fit design that provides optimum cleaning conditions. The spiral membranes are available with different ultrafiltration membrane types and in different combinations of length, diameter and feed spacer size
The pores of the membranes used for Alfa Laval ultrafiltration spiral membranes are small, having a cut-off range from 1,000 to 100,000 molecular weight (MWCO), and the applied pressure is relatively low. Salts, sugars, organic acids and smaller peptides pass through the pores of the membrane, whereas proteins, fats and polysaccharides are retained.
Using appropriate ultrafiltration membranes also makes it possible to fractionate a feed stream into two distinct streams, with each stream containing dissolved components with different molecular weights.
The Alfa Laval ultrafiltration spiral membranes are a popular choice for many processes applied in the food, beverage, dairy, biotech and pharmaceutical industries where they are used for product recovery for example of an active from fermentation broth, as well as product purification, fractionation and concentration.
Alfa Laval offers a comprehensive range of spiral membranes with different characteristics and properties.
The ETNA ultrafiltration membrane is made of composite fluoro polymer membrane cast on polypropylene (PP) backing material. The UF-ETNA spiral membrane is available in two types: ETNA01PP and ETNA10PP having a molecular weight cut-off value (MWCO) of 1,000 and 10,000 dalton respectively.
This ultrafiltration membrane is also made of composite fluoro polymer membrane cast on polypropylene backing material. The UF-FS spiral membrane is available as FS40PP with a MWCO value of 100,000 dalton.
This series of ultrafiltration spiral membranes from Alfa Laval is tailor-made for the dairy and beverage industries, but it is also a popular choice for other food, chemical and pharmaceutical applications.
The UF-PE membrane is made of either polysulphone or polyethersulphone membrane on polyester (PET) support material. The UF-PE spiral membrane is available in the following types: GR60PE, GR61PE, GR70PE, GR73PE and GR82PE with MWCO values ranging from 25,000 to 5,000 dalton.
The UF-pHt membrane is characterized by its tolerance towards high pH and temperature. It is made of polysulphone or polyethersulphone membrane cast on polypropylene backing material. The UF-pHt spiral membrane is available in the following types: GR40PP, GR51PP, GR60PP, GR61PP, GR70PP, GR80PP, GR81PP, GR90PP and GR95PP with MWCO values ranging from 100,000 to 2,000 dalton.
UF-pHt series for dairy applications
For dairy applications The UF-pHt spiral membrane is available in the types GR60PP, GR61PP, GR70PP, GR73PP and GR82PP with MWCO values between 20,000 and 5,000 dalton. The spiral membranes of this series are made of polysulphone or polyethersulphone membrane cast on polypropylene backing material. The spiral membranes are tolerant to high temperatures and pH values.
The RC ultrafiltration membrane is made of regenerated cellulose membrane cast on polypropylene support material. The UF-RC spiral membrane is available as RC70PP having a MWCO value of 10,000 dalton.
The UFX-pHt ultrafiltration membranes is also characterized by its ability to tolerant high pH and temperatures. The membrane is made of polysulphone permanently hydrophilic, cast on polypropylene support material. The UF-pHt spiral membrane is available as UFX10 pHt with a MWCO value of 10,000.
- cost-effective operation due to low energy consumption
- long life time compared to traditional dead-end filtration
- cover a broad spectrum of flux properties and pore sizes
- available in different combinations of length, diameter and spacer size
- sanitary design with all materials in compliance with FDA regulations
- same membrane types available as both flat sheet membranes and spiral membranes
- suitable for extensive range of processes
- manufactured by Alfa Laval's own membrane centre
How it works
The basic technology behind membrane filtration involves using a semi-permeable membrane to separate a liquid into two distinct streams.
Pumping this liquid across the surface of the membrane creates a positive trans-membrane pressure that allows any components smaller than the porosity of the membrane to pass through, forming the permeate.
Any components larger than the pore size simply cannot pass through, and remain behind in what is called the retentate. The surface of the membrane is kept free of blockages by the force of the liquid flow moving parallel to the membrane surface.
Spiral membrane construction
A spiral element comprises of a number of membrane 'envelopes' with 2 membrane sheets separated by a permeate spacer mesh, each glued to a central permeate collection tube.
Between each pair of envelopes there is a spacer which creates the feed channel, allowing the feed to flow across the length of the spiral element, whilst the permeate passing through the membrane into the membrane envelope flows in a spiral pattern to the permeate collection tube.
In the illustration above showing the flow pattern in a spiral membrane from Alfa Laval, red represents the feed/retentate. Yellow the permeate.
All materials used for the production of Alfa Laval membranes, in both spiral-wound and flat-sheet designs and configurations, comply with EU Regulation (EC) 1935/2004 and Commission Directive 2002/72/EC as well as FDA regulations (CFR), Title 21. The membranes are thus suitable for use within food and pharmaceutical processing applications.
These compliance also extend to the equipment and fittings related to membrane operations, including items such as plate-and-frame units, element housings and pumps.