Nanofiltration NF System

The basic principle of nanofiltration membrane technology is to use pressure to separate soluble ions from water through a semipermeable membrane. Unlike dead-end filters, nanofiltration membranes utilize different hydraulic properties, also known as cross-flow filtration.

Most nanofiltration membranes are composite materials supported by a polymer matrix and adopt a spiral design, rather than a flat or tubular structure. Currently, the predominant model in industrial applications is the spiral structure. To gain a deeper understanding of nanofiltration systems, you need to know the following information.

Similar to reverse osmosis (RO), nanofiltration systems recycle a certain percentage of the feed water, which differs from ultrafiltration (UF). Most nanofiltration membranes utilize a spiral wound structure.

FupengWater is a leading global supplier of industrial and commercial nanofiltration systems with over 20 years of experience specializing in removing impurities from water. Our nanofiltration systems ensure clean drinking water for a wide range of applications in the water treatment industry. View our range of nanofiltration systems for commercial sites and industrial plants to meet your water treatment needs.

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In the water treatment industry, nanofiltration (NF) serves as a bridge between ultrafiltration (UF) and reverse osmosis (RO) membranes. It is sometimes referred to as loose or low-rejection RO membranes. Because NF membrane pore sizes range from 0.01 to slightly less than 0.001, it can also be referred to as tight ultrafiltration (UF). Generally speaking, NF membrane systems allow more salt to pass than RO membranes. Furthermore, NF membrane elements can produce the same water output as RO systems at 50% to 70% of the applied pressure.

In some applications, a 75% salt rejection is more advantageous than a 95% to 99% rejection, especially when using half the energy. Unlike reverse osmosis (RO) membrane elements, the performance of NF membrane elements offered by various membrane manufacturers varies significantly. For reverse osmosis (RO) membrane elements, any model with a sodium chloride rejection rate below 99.5%, especially for seawater, is considered inferior. However, for nanofiltration (NF) membrane elements, any model with a sodium chloride rejection rate of 40% or higher is considered suitable. NF membranes are also called "softening" membranes because, while their salt rejection rates may be 80% or lower, their hardness rejection rates are often well above 90%.

Other applications of nanofiltration include

• Heavy metal removal from wastewater

• Pesticide removal from groundwater

• Laundry wastewater recycling

• Water softening

• Nitrate removal

Q&A

What is a nanofiltration membrane?

Nanofiltration membranes are used to filter low-total dissolved solids (TDS) water, removing organic matter and softening the water. Nanofiltration technology is used in numerous water and wastewater treatment industries, effectively removing ions and organic matter. Nanofiltration technology is also often used as a pretreatment for reverse osmosis (RO). In addition to water purification, nanofiltration membranes are also used in food, beverage, and pharmaceutical production.

What's the Difference Between Nanofiltration and Reverse Osmosis?

While nanofiltration and reverse osmosis systems are similar in design and operational purpose, there are some significant differences between the two. The main difference is that nanofiltration is less rigorous than reverse osmosis. Nanofiltration operates at lower feed water pressures and cannot effectively remove singly charged ions from water like reverse osmosis membranes.

While reverse osmosis systems can remove up to 99% of chloride and sodium, nanofiltration membranes typically only remove 50% to 80%. This percentage depends on the membrane material type and manufacturing process. However, because nanofiltration effectively removes multiply charged ions, it is a preferred method for removing hardness from water without compromising total dissolved solids (TDS) as reverse osmosis does.

Nanofiltration (NF) Application Examples

Applications	Permeate	Concentration	Benefits of NF
Whey/Whey Permeate	Brackish Wastewater	Desalted Whey Concentrate	Allows for lactose and whey protein concentrate recovery and salt reduction
Textiles	Dyes	Water, Salt, BOD, COD, and Color	NF is used to desalinate dyes, resulting in higher-value products
Alkaline Cleaning Solutions	Alkaline Cleaning Solutions	BOD, COD, Suspended Solids, Alkaline Cleaners	Allows for recovery of alkaline cleaning solutions, reducing cleaning chemical costs
Acidic Solution Recycling	Acidic Solutions	BOD, COD, Calcium, Suspended Solids, Acidic Water	Allows for recovery of acidic solutions, reducing cleaning chemical costs
Water	Softened Water	Hard Water	Drinking Water Production Softened water reduces scaling of equipment and heat exchange surfaces
Antibiotics	Salty Waste	Desalination and Concentration of Antibiotics	NF Production of High-Value Pharmaceutical Products

FupengWater's nanofiltration is a membrane filtration process most commonly used for low-total dissolved solids water, such as surface water and fresh groundwater, to soften water (remove multivalent cations) and remove disinfection byproduct precursors, such as natural and synthetic organic matter. Nanofiltration is also increasingly used in food processing applications, such as dairy, for simultaneous concentration and partial (monovalent ion) desalination.

FupengWater offers a full range of standard and fully customizable nanofiltration systems, all designed using advanced 3D computer modeling and process design software to provide precise and customized solutions.

Operating Specifications

• Maximum Inlet Water Temperature: 42°C

• Inlet Water Pressure: 20 to 50 psi

• Operating Pressure: 80 to 125 psi

• H₂S Must Be Removed

• Turbidity Must Be Removed

• Maximum Iron Content: 0.05 ppm

• Feed Water TDS: 0 to 1,000 ppm

• Upgrading Equipment for Higher TDS

• Anti-scaling Agent Required for Hardness Above 1 GPG

• pH Tolerance: 3 to 11

• Maximum Silica Tolerance: 60 ppm @ 60% Recovery

• Operating at Higher TDS by Reducing Recovery

Standard Features and Available Options

• Powder-coated Carbon Steel Frame

• 8-inch TFC Spiral Wound Membrane

• Stainless Steel Multistage Pump with TEFC Motor

• Fiberglass Membrane Housing

• 5 Micron Cartridge Pre-Filter

• 460V/3ph/60Hz Power Requirements

• Microprocessor-Based Control Panel

• Programmable Time Delays and Setpoints

• Status Indicator

• Motor Starter

• NEMA 12 Enclosure

• Low-Pressure Switch

• High-Pressure Switch

• Filling Pressure Gauge

• Permeate Conductivity Monitor

• Permeate and Concentrate Flow Meters

• Remote Monitoring/Control Options

• Feed Water Conductivity Monitor

• Membrane Cleaning Skid

• Hourly Automatic Flush

• Feed/Permeate Mixing

• 220V or 380-415V/3ph/50 or 60Hz

• Product Tank Level Switch

• Feed pH Controller with Sensor

• Feed ORP Controller with Sensor

• Flow Totalizer

• Chemical Metering System

• Media and Iron Pre-Filtration System

• UV Sterilization System

• Water Softener

• Post-RO System

• Containerized NF System

Nanofiltration is also increasingly common in food processing applications, such as textile wastewater treatment and dairy processing, for simultaneous concentration and partial (monovalent ion) desalination.