When it comes to industrial and municipal water purification, nanofiltration (NF) membranes such as the NF270 and NF90 by DuPont FilmTec™ are two of the most widely used options. Both are designed to remove organic matter and reduce hardness, but their performance and applications differ significantly.
This article will help you understand the key differences between NF270 and NF90 membranes, so you can choose the right one for your specific water treatment system.
What Is NF270 Membrane?
The NF270 membrane is a loose nanofiltration membrane developed by DuPont (formerly Dow FilmTec™). It is designed for high permeability, partial softening, and selective ion rejection-ideal for applications where complete desalination is unnecessary.
Key Specifications of NF270:
Salt Rejection: 20–50% (moderate desalination)
Sulfate Rejection: Up to 97%
TOC / THM Precursor Removal: ≈98%
Operating Pressure: 0.5–2.0 MPa (low energy consumption)
Membrane Material: Aromatic polyamide thin-film composite
pH Range for Cleaning: 1–12
The NF270-4040 and NF270-8040 models are the most common sizes, suitable for industrial water reuse, municipal wastewater treatment, food & beverage production, and groundwater purification.
Because it allows monovalent ions such as Na⁺ and Cl⁻ to pass while rejecting multivalent ions (e.g., SO₄²⁻, Ca²⁺, Mg²⁺), NF270 provides partial softening and energy savings up to 40% compared to reverse osmosis (RO) systems.
👉 Learn more about our NF270-4040 product page and NF270-8040 product page for full specifications and case studies.
What Is NF90 Membrane?
The NF90 membrane is a tight nanofiltration membrane-closer to reverse osmosis in performance. It is designed for higher desalination rates and low total dissolved solids (TDS) production water.
Key Specifications of NF90:
Salt Rejection: 85–95%
Sulfate Rejection: >99%
Operating Pressure: 0.8–2.5 MPa
TOC Removal: 97–99%
Material: Polyamide thin-film composite
pH Range for Cleaning: 1–12
The NF90-4040 and NF90-8040 are ideal for:
Drinking water purification
Pharmaceutical-grade water systems
Desalination pretreatment
Food and beverage industries requiring low-salt water
In short, the NF90 membrane provides tighter separation, resulting in softer and lower-TDS product water, but typically consumes slightly more energy than NF270.
👉 Explore the NF90-4040 membrane product page and NF90-8040 membrane product page for detailed performance data and energy-saving configurations.
NF270 vs NF90: Key Differences
| Feature | NF270 Membrane | NF90 Membrane |
|---|---|---|
| Manufacturer | DuPont FilmTec™ | DuPont FilmTec™ |
| Membrane Type | Loose nanofiltration | Tight nanofiltration |
| Salt Rejection | 20–50% | 85–95% |
| Sulfate Rejection | ≈97% | >99% |
| Organic Removal (TOC, THM) | ≈98% | ≈99% |
| Operating Pressure | 0.5–2.0 MPa | 0.8–2.5 MPa |
| Water Permeability | Higher flux, more permeate | Lower flux, higher purity |
| Water Softening | Partial softening (keeps some minerals) | Full softening |
| Ideal Applications | Industrial reuse, F&B, agriculture | Potable water, pharma, desalination |
| Energy Consumption | 30–40% lower | Slightly higher |
When to Choose Each:
- Choose NF270 if your goal is organic matter removal, low energy cost, and partial softening.
- Choose NF90 if your priority is maximum salt rejection and high-purity water production.
Many water treatment plants even combine NF270 and NF90 membranes in multi-stage systems-using NF270 in the first stage for bulk organic removal and NF90 in the second for final polishing.
Common Sizes of NF270 and NF90 Membranes
Both NF270 and NF90 membranes are available in standard 4-inch and 8-inch sizes, making them compatible with most commercial and industrial pressure vessels.
| Model | Size (inch) | Membrane Area | Typical Flow Rate | Application |
|---|---|---|---|---|
| NF270-4040 | 4 × 40 | 85 ft² (7.9 m²) | ~2,100 GPD | Pilot plants, small industrial systems |
| NF270-8040 | 8 × 40 | 365 ft² (34 m²) | ~10,000 GPD | Municipal / large industrial |
| NF90-4040 | 4 × 40 | 85 ft² (7.9 m²) | ~1,800 GPD | Drinking water, lab use |
| NF90-8040 | 8 × 40 | 365 ft² (34 m²) | ~9,000 GPD | Full-scale water treatment |
Real Wastewater Application: Comparative Performance of NF270 and NF90 Membranes
To better understand how NF270 and NF90 membranes perform beyond laboratory conditions, several studies have compared their behavior in real secondary effluents - such as urban sewage and meat processing wastewater.
The results highlight significant differences in desalination performance, fouling behavior, and cleaning efficiency.
1. Salt Rejection and Desalination Rate
Both NF270 and NF90 membranes demonstrate excellent removal of organic matter, with TOC concentrations in permeate water below 2 mg/L.
However, NF90 shows a much higher desalination capability, achieving >96% salt rejection in different wastewater types.
In contrast, NF270 achieves 54% desalination for municipal secondary effluent and 36% for meat processing wastewater.
This confirms that NF270 is more suitable for partial softening or organic-focused applications, while NF90 excels when high-purity water is required.
2. Membrane Fouling Behavior
The degree of membrane fouling varies significantly:
- NF270 experiences a flux decline >60%, indicating higher fouling susceptibility.
- NF90 shows only 9–16% flux attenuation under similar conditions.
Meat processing wastewater causes more fouling than urban sewage due to higher organic load.
This suggests that while NF270 offers higher permeability, its open structure makes it more vulnerable to fouling, especially in high-organic industrial wastewater.
3. Membrane Resistance Analysis
Resistance components in fouled membranes include:
- Intrinsic membrane resistance (Rm)
- Adsorption resistance (Ra)
- Surface gel resistance (Rc)
Among these, Rm accounts for the largest portion of total resistance.
However, the Ra and Rc fractions are higher in NF270 membranes than in NF90, showing that NF270 membranes accumulate more surface fouling and adsorbed organic matter.
4. Type of Pollutants
After treatment of real effluents, both NF270 and NF90 membranes exhibit mixed inorganic and organic fouling.
- Inorganic fouling is more severe in meat-processing wastewater.
- Organic fouling is mainly due to soluble microbial products (SMP) and amino acids.
Humic and fulvic acids, on the other hand, play a minor role in membrane fouling.
5. Cleaning Performance
Different cleaning agents show distinct effects:
- Alkaline cleaning solutions are most effective for removing organic fouling.
- Acidic solutions perform better against inorganic scaling.
- Deionized water flushing provides moderate improvement.
In practice, the best cleaning strategy is to use alkaline cleaning as the primary method and acid cleaning as a supplementary step.
This dual cleaning approach significantly restores membrane flux, particularly for NF270 membranes.
Benefits of Nanofiltration (NF) Technology
After comparing NF270 and NF90 membranes, it's also important to understand why nanofiltration membranes are widely used in modern water treatment systems.
- Selective Filtration: NF membranes separate ions and organic molecules based on charge and size, providing targeted removal of contaminants.
- Divalent Ion Removal: Efficiently removes calcium and magnesium, reducing water hardness and scaling.
- Organic Matter Control: Eliminates colorants, humic acids, and organic carbon, ensuring clear, safe water.
- Lower Energy Demand: Operates at lower pressure than RO systems, reducing energy costs by up to 30–40%.
- Wide Application Range: Used in water treatment, food & beverage processing, pharmaceuticals, and industrial separation.
- Balanced Performance: Offers high permeability with selective rejection, achieving both efficiency and cost-effectiveness.
Comparison Conclusion
Both NF270 and NF90 membranes are top-performing nanofiltration products from DuPont FilmTec™, but they serve different water treatment goals:
- NF270 → High flux, low energy, moderate salt rejection
- NF90 → High rejection, low TDS, high-purity output
Choosing the right one depends on whether you prioritize energy efficiency or maximum purification.
For professional guidance and quotation, contact:
📧 sales@ink-blue.com
📱 WhatsApp: +86-18302940580
🏢 Xi'an Ink-blue Environmental Protection Technology Co., Ltd.
References
- "According to DuPont FilmTec™ datasheets, the NF270-4040 membrane achieves 20–50% salt rejection while removing over 98% TOC (DuPont, 2023)…"
- "Studies show that NF90 experiences much lower flux decline compared with NF270 when treating secondary effluent (Ahn et al., 2019)…"
- "NF membranes are widely applied in municipal water treatment to comply with THM regulations (EPA, 2022)…"
- "EPA Stage 2 Disinfectants and Disinfection Byproducts Rule (D/DBP)"
