Nano Filtration (NF)
The fundamental principle of Nanofiltration membrane's technology is the use of pressure to separate soluble ions from water through a semi permeable membrane. The membrane operates under a different hydraulic profile, which is also known cross flow filtration, unlike a dead end filter. The predominant model used today for industrial applications is the spiral configuration. Nano Filtration(NF), in water treatment, “bridges” a gap between UF and RO membranes. NF membrane pore size ranges from .01 to a little less than .001. Generally, NF membrane system lets more salt pass than an RO membrane.
In addition, an NF membrane element will produce the same quantity of product at 50 to 70% the applied pressure as an RO water treatment system.
There are applications where a 75% rate of salt rejection is preferable to 95 to 99%, especially when it is achieved using only half of the energy. Unlike with RO membrane elements, the NF offerings of the major membrane manufacturers are quite different in performance from company to company. With RO membrane elements, any model with less than 99.5% sodium chloride rejection, especially with seawater membranes, is considered inferior. In the case of NF, there is a “place” for any membrane with a NaCl rejection rate of 40%, or more.
Nanofiltration has also been called a “softening” membrane as while its salt rejection may be 80% or less, hardness rejection will often remain well over 90%.Like RO, and unlike UF, a Nanofiltration Systems will recover a percentage of the feed water. Most all NF membranes are of a spiral wound configuration.
Other Applications Of Nano-Filtration Are
- The removal of heavy metals from wastewater.
- The removal of pesticides from groundwater.
- Wastewater recycling in laundry facilities.
- Water softening.
- Nitrate removal.
Available Ranges & Models
- Packaged Institutional NF Systems: 0.25 to 1 M3/Hr. Systems.
- Industrial NF Systems: 0.5 to 100 M3/Hr. Systems.
- Waste water NF systems for Zero Liquid Discharge: 1 to 50 M3/Hr. Systems.
Application | Permeate | Concentrate | Benefits of NF |
---|---|---|---|
Whey/Whey Permeate | Salty wastewater | Desalted whey concentrate | Allows the recovery of lactose and whey protein concentrate with reduced salt content |
Textile | Dyes | Water, salts, BOD, COD and color | NF is used to desalt dyes resulting in a higher value product. |
Caustic cleaning solutions | Caustic cleaning solution | BOD, COD, suspended solids, caustic cleaner | Allows caustic cleaning solution to be recycled resulting in reduced cleaning chemical costs |
Recycle of acid solutions | Acid solution | BOD, COD, calcium, suspended solids, acidic water | Allows acid solution to be recycled resulting in reduced cleaning chemical costs |
Water | Softened water | Hard water | Potable water production. Softened water reduces scaling on equipment and heat exchange surfaces |
Antibiotics | Salty waste product | Desalted, concentrated Antibiotics | NF produces high value pharmaceutical products |