Nanofiltration, in concept and operation, is much the same as reverse osmosis. The key difference is the degree of removal of monovalent ions such as chlorides. Reverse osmosis removes the monovalent ions at 98-99% level at 200 psi. Nanofiltration membranes’ removal of monovalent ions varies between 50% to 90% depending on the material and manufacture of the membrane. For this reason, there is a variety of Nanofiltration membranes available. Each type is particularly suited to a certain application and may not be acceptable to a different application. Nanofiltration membranes and systems are used for water softening, food and pharmaceutical applications.
Nanofiltration is a relatively recent membrane process used most often with low total dissolved solids water such as surface water and fresh groundwater, with the purpose of softening (polyvalent cation removal) and removal of disinfection by-product precursors such as natural organic matter and synthetic organic matter.
Nanofiltration is also becoming more widely used in food processing applications such as dairy for simultaneous concentration and partial (monovalent ion) demineralisation.
While nanofiltration is used for the removal of other substances from a water source, it is also commonly used for the desalination of water. As seen in a recent study in South Africa, tests were run using polymeric nanofiltration in conjunction with reverse osmosis to treat brackish groundwater. These tests produced potable water, but reverse osmosis removed a large majority of solutes. This left the water void of any essential nutrients (calcium, magnesium ions, etc.), placing the nutrient levels below that of the required World Health Organization standards. This means nutrients should be added back to bring te water back to the standards levels for drinking water. Nanofiltration methods remove fewr solutes, so may avoid the need to remineralize the water.
Nano-Filtration System Technical Specifications
- Flow Rates of 50 – 2400 gpm
- Product and Concentrate Flowmeters
- Solid State Controller
- PLC (AB) controller
- Low Suction Pressure Switch and Shutoff
- High Pressure Speed Switch and Shutoff
- Liquid-Filled Pressure Gauges for the Pumps, Discharge, Membrane, Secondary Feed, Permeate and Concentrate Pressure Gauges
- High Product Conductivity Monitor
- Product Storage Level Connection and Shutoff
- 5 Micron Pre-Filter
- Flush system
- Conductivity Analyzer
- Digital Totalizing Flow Meters
- Stainless Pump
- Chemical Feed
- Stainless piping
- Stainless frame
- Low Suction Pressure
- High Product Conductivity
- High Tank Level
- High Permeate Flow
- Low Concentrate Flow
The NANO-350 System is a reverse osmosis module designed for large industrial applications. Each NANO module utilizes 8 inch diameter spiral wound membranes, housed in fiberglass vessels producing a capacity of 50 – 2400 G.P.M. The modular design allows for easy expansion. The NANO-350 is a free standing system designed and engineered for ease of maintenance and operation. Solid state controls provide continuous monitoring of all critical parameters. In addition the system will automatically stop the system when conditions are not within preset limits, i.e. low suction pressure, high product conductivity. Instrumentation includes liquid-filled pressure gauges; product and concentrate flow meters; and a conductivity meter to measure product water quality.
Pumps are selected according to the number of NANO-350 modules. The pumps are stainless steel centrifugal type with integral 3- phase, 60hz or 50hz, (optional) TEFC (totally enclosed fan cooled optional) motors.
REVERSE OSMOSIS SYSTEM
|Unitized Frame Mounted||Yes|
|Design Flow Per Pump||80 – 3000 gpm|
|Design Discharge Pressure.||100.0 – 1100.0 psi|
|Number of Pumps||1 – 3|
|Pump Construction||Stainless Steel|
|Pump Mounting||Close Coupled|
|Pump Suction/Discharge Size||2 – 8″ Flange|
|Motor Horsepower||20 – 200 HP TEFC|
|Magnetic Starter With Heater Coils||NEMA 4 Enclosure|
|Manifold Suction/Discharge||2 – 8″ inch|
|Suction Valve Type||Ball Valve|
|Discharge Valve Type||Stainless Ball Valve|
|Discharge Check Valve Type||Ball|
|Pressure Gauges||6 Each, SS 316|
|Low Pressure Switch||1 Each, SS 316|