Membrane Filtration for Textile & Dyestuff
In the Textile & Dyestuff industry, membrane filtration has a number of possible applications. The main uses include but are not limited to Dye Desalting & Purification, Effluent Treatment, and Water Reuse.
Membranes are used to concentrate and purify many types of dye which are to be applied aqueously. Membrane filtration is used widely in a variety of process industries, not only for product purification but also for material recovery from waste and for the treatment of effluent prior to final disposal. In dye manufacture and application, like most other processes, there is a continuous search for production methods which will improve product yield and reduce manufacturing costs. Membrane filtration now plays an important part in achieving both of these objectives.
At PCI Membranes, we manufacture membranes, build filtration plants, and are working with a number of dye facilities throughout Europe and Asia.
Some of the reasons PCI Membranes’ customers have chosen to change to their existing UF & NF systems:
- Demand for stable liquid dyes
- Increase in selling price for improved quality product
- Effluent legislation changes
- Effluent charge restructuring
- Bottleneck in capacity
- Future expansion needs – space availability
PCI Membranes for Desalting and Purification
Dye desalting and purification, the process by which impurities are removed to improve the quality of the finished product, is currently one of the largest applications for nanofiltration or tight ultrafiltration technology, especially for reactive dyes. Dye manufacturers are now actively pursuing the desalting of the finished dye prior to spray drying, and membrane filtration provides the ideal method for salt removal. In the opinion of many dye producers, desalting improves the product’s quality and makes spray drying more efficient, because is not blocking the nozzles of the spray drying machines.
Tubular nanofiltration and tight ultrafiltration membranes, using equipment such as our B1 module, are now being applied to dye desalting. A number of membranes can be selected, depending upon the required purification level and the dye type being treated. The following tubular membranes are used in dyestuff applications: : AFC30, AFC40, and ES404.
Spiral-wound membrane elements use similar material to those of tubular construction but in this case, they have a different geometry, namely spiral-wound. The choice between tubular or spiral-wound configuration, either of which can be supplied by PCI Membranes, is almost entirely dependent on the feed material and conditions of operation. If the dye is in solution and is likely to remain soluble during desalting, there is an advantage to using spiral-wound elements as these provide a higher throughput because of their larger surface area per filtration element. However, if solids are present in the feed material or if precipitation of solids is likely, then tubular membranes are recommended. Also, tubular membranes allow for a higher dyestuffs final concentration, thanks to their intrinsically higher yield.
Spiral-wound membrane elements
PCI Membranes for Effluent Treatment & Water Re-use
In many industries, membrane filtration systems are used to recover quantities of the finished product from the waste stream, thereby improving final production yields. Whilst this is sometimes feasible during dye production, where a reactive dye is concerned, the reaction has often occurred by the time the dye has reached the effluent stage of the process. If this is the case, membrane filtration can still be used effectively, but to concentrate waste material prior to the final effluent discharge rather than as part of a product recovery initiative.
During the process of dying a material, large quantities of water are used. In many dye plants it could be viable to recover and reuse the process water, rather than discharging it to waste. Depending upon the process economics of a particular plant, membrane filtration can be employed to remove impurities and purify the water for reuse in the dying production process. Nanofiltration and/or reverse osmosis would normally be used at this point of the production process.
For reverse osmosis, spiral-wound membranes are the ideal choice. FG – SpiraCore® – PENF Membrane Series and FG – SpiraCore® – PEUF-Plus- Membrane Series are highly recommended for the Effluent Treatment & Water Reuse application. Besides, AFC99 or AFC80 membranes from our tubular membranes series represent additional options and are well known for their excellent performance in Effluent Treatment applications.