NF membranes remove between 30% and 93% of TDS, depending on membrane type, feedwater quality, and operating Pressure. For brackish water, a well-selected NF membrane typically delivers 43% to 88% TDS rejection.
For high-salinity or industrial streams, a tighter NF membrane under optimised conditions can push beyond 90%.
That is the direct answer. But the number alone does not tell you whether NF is the right choice for your application. This guide covers the science, verified data, real case study results, and a clear decision framework so you can choose the right membrane the first time.
What Is Nanofiltration and How Does It Work?
Nanofiltration is a pressure-driven membrane process. It sits between ultrafiltration (UF) and reverse osmosis (RO) in the filtration spectrum. NF membranes have pore sizes of approximately 0.001 microns, tight enough to block divalent ions such as calcium, magnesium, and sulfate, but permeable enough to let smaller monovalent ions, such as sodium and chloride, pass through partially.
This selective behaviour is what makes NF different from RO. It does not strip everything. It removes the right things.
NF membranes operate at pressures of 5-15 bar (roughly 75–150 psi). That is significantly lower than the 10-70 bar required for RO systems, and it directly affects energy costs.
Jay Water supplies Toray NF Membranes, one of the most widely used NF membrane series in industrial water treatment across India. Toray’s NF product line includes spiral wound elements designed specifically for selective ion rejection, dye removal, and high-fouling feed streams.
NF TDS Removal: Verified Percentages by Application
The range published in peer-reviewed literature and confirmed in field applications is wide. Here is a structured view:
| Feed Water Type | NF TDS Rejection | Source |
| Brackish water (pilot study) | 43.41% | PMC / PubMed Hybrid NF/RO study |
| Tight NF membrane (TW30 at 10 bar) | 93% | Springer Nature, 2025 |
| Two-stage NF flowback water | 73% overall | ScienceDirect, 2022 |
| RO brine concentrate | 79–89% | PMC RO Brine NF study |
| Seawater (modified ceramic NF) | ~30% | ACS Seawater NF study |
| Industrial wastewater (MBR permeate) | 98.22% | MDPI Petroleum industry NF review |
Key takeaway: A single TDS removal figure is not meaningful without knowing the feed water, membrane model, and operating pressure. This is why membrane selection requires a proper water analysis, not a catalogue search.
Ion-Level Rejection Data (Verified)
NF membranes do not reject all ions equally. Here is the rejection order confirmed across studies:
- Calcium sulfate (CaSO₄): 97.4%
- Sodium sulfate (Na₂SO₄): 97.3%
- Magnesium sulfate (MgSO₄): 95.2%
- Magnesium chloride (MgCl₂): 93.4%
- Sodium chloride (NaCl): 79%
This is the core reason NF works so well for hardness removal and scaling control. It targets the ions most responsible for fouling and deposits, while passing a portion of monovalent salts.
Why TDS Removal Varies: The Key Factors?
Results shift based on five variables:
1. Membrane Tightness (MWCO)
Molecular weight cut-off (MWCO) ranges from 150 to 300 Daltons for NF membranes. Tighter membranes (lower MWCO) remove more TDS but reduce permeate flux. Looser membranes give higher flow but lower rejection.
2. Feed Water TDS and Composition
A 3,000 ppm brackish water stream behaves very differently from a 20,000 ppm industrial effluent. High sulfate content improves NF performance; high sodium chloride reduces it.
3. Operating Pressure
Higher Pressure increases TDS rejection up to a point. A 2025 peer-reviewed study published in Discover Applied Sciences (Springer Nature) reported 93% TDS rejection at 10 bar operating pressure using the TW30 NF membrane, with calcium rejection at 96.1% and magnesium at 98.7%. Lower Pressure drops that figure significantly.
4. Temperature
Higher temperatures increase membrane permeability, which can slightly reduce rejection. Systems in hot climates or treating warm effluent need pressure adjustment.
5. Fouling and Membrane Condition
A fouled NF membrane produces inconsistent TDS rejection. This is why ROPUR antiscalants for RO and NF systems are used in well-designed NF plants; they prevent scale formation from calcium carbonate, calcium sulfate, and silica, protecting long-term performance.
NF vs RO: Full Comparison
This comparison covers what most articles miss: energy, pressure, recovery, and the actual cost implications.
| Parameter | Nanofiltration (NF) | Reverse Osmosis (RO) |
| Pore size | ~0.001 microns | ~0.0001 microns |
| Operating pressure | 5–15 bar (75–150 psi) | 10–70 bar (150–1,000+ psi) |
| TDS removal | 30–93% | 95–99%+ |
| Divalent ion rejection | Very high (92–97%) | Near-total (>99%) |
| Monovalent ion rejection | Moderate (20–80%) | Very high (95–99%) |
| Energy consumption | 30–50% lower than RO | Higher scales with salinity |
| Water recovery | Up to 85–90% | Typically 50–75% |
| Best for | Softening, COD/hardness reduction, pretreatment | Full desalination, high-purity water |
Energy is a critical factor for long-running industrial systems. NF operating at 5–15 bar versus RO at 15–70 bar means substantially lower pump load and power consumption.
Independent technical analysis confirms NF consumes 30–50% less energy than RO treating the same feed water, with recovery rates reaching 85–90% when properly designed.
For a detailed breakdown of which technology fits which scenario, see Jay Water’s guide on RO vs NF Membranes.
NF Operating Parameters: What Engineers Need to Know
For system designers and plant engineers, here are the practical parameters for NF membrane design:
- Operating pressure range: 5–15 bar (application-dependent)
- MWCO: 150–300 Daltons (varies by membrane series)
- Typical pore size: 0.001 microns
- Divalent ion rejection: 85–98%
- Monovalent ion rejection: 20–80% (varies significantly)
- Recovery rate: Up to 85–90% with proper pretreatment
- pH range: Typically 2–11 (check specific membrane datasheet)
- Temperature range: 5–45°C
For Toray NF membrane specifications, including flux, rejection rates by ion type, and pressure specifications, Jay Water’s technical team can provide full datasheets from Toray’s NF product range.
When to Choose NF: Industry Decision Guide?
Use this framework to decide if NF is the right membrane for your application.
Choose NF when:
- Feed TDS is 500–5,000 ppm, and full demineralisation is not required
- The primary problem is hardness, scaling, or high divalent ion content
- You need to reduce COD and colour while preserving some dissolved minerals
- Energy cost is a critical factor, and partial TDS reduction meets compliance
- NF-treated water will be reused for cleaning, washing, or process cooling
- You are designing pretreatment for a downstream seawater membrane or high-pressure RO system
Choose RO when:
- Feed TDS exceeds 10,000 ppm, or you are treating seawater
- Near-total salt removal is required (drinking water, pharmaceutical, boiler feed)
- The application demands >95% rejection of monovalent ions
- ZLD (Zero Liquid Discharge) compliance requires maximum concentration
Consider NF + RO hybrid when:
- Feed TDS is 5,000–15,000 ppm, and single-stage RO is expensive to run.
- A peer-reviewed brackish water study confirmed that a hybrid NF/RO system achieved 76.52% TDS rejection, higher than standalone RO (60.26%) and NF (43.41%) alone.
Industry-wise guidance:
| Industry | Recommended Approach |
| Textile / Dye Effluent | NF first for colour and dye rejection, then RO for TDS polishing |
| Pharmaceutical | RO (NF as pretreatment only) |
| Food & Beverage | NF for sugar concentration, colour removal |
| Chemical / Petrochemical | NF for COD-TDS reduction; RO if ZLD required |
| Power Plant Wastewater | NF for hardness reduction before RO |
| Municipal Drinking Water | NF for softening; RO if groundwater TDS >2,000 ppm |
For Toray NF membrane solutions for dye and high-contaminant industrial applications, visit Jay Water’s Toray NF Membrane for Dyes and Other Applications page.
Real-World Applications: Where NF Delivers
Textile Wastewater Treatment
NF membranes are widely used in the textile industry to separate dyes, salts, and organic compounds from effluent, recovering water for reuse while reducing discharge load. Toray NF membranes are specifically designed for this stream, handling high dye concentrations and chemical loadings that would rapidly foul conventional membranes.
Power Plant Scrubber Wastewater
High-TDS scrubber water (up to 12,000 mg/L) with dominant divalent ions responds very well to NF. Studies on NF treatment of power plant wastewater showed 80% water recovery while maintaining over 60% rejection of calcium and chloride.
Seawater Desalination Pretreatment
For seawater membrane systems, NF is used upstream to reduce calcium by up to 75%, magnesium by up to 92%, and organic matter by over 97% before the feed water reaches the high-pressure seawater RO system. This significantly extends RO membrane life and reduces chemical cleaning frequency.
Industrial Effluent Reuse
In feed streams with TDS of 6,000–8,000 ppm, NF-treated permeate can be used directly for industrial cleaning and washing without a further RO step. For higher TDS feed (above 16,500 ppm), the NF permeate is fed into a downstream RO plant for final polishing.
For a full look at Jay Water’s Nanofiltration Membranes and application range, including pharmaceutical, municipal, and food & beverage use cases, see their nanofiltration product page.
Jay Water Case Study: Actual NF Results from the Field
This is real data from a Jay Water installation, not a hypothetical.
Application: Optical Brightening Agent (OBA) manufacturing facility
Challenge: Daily effluent of 300 KLD with COD 5,000 ppm, TDS 20,000 ppm. Conventional biological treatment failed due to high TDS. The RO reject water had a COD too high for a second-stage RO plant.
Jay Water Solution: Integration of Nanofiltration membranes into the existing ETP scheme.
Results achieved:
- COD reduced from 2,500 ppm to below 350 ppm
- Permeate TDS below 500 ppm
- Permeate COD below 50 ppm
- Total reject water volume reduced from 320 KLD to 110 KLD
- System recovery: 75–80%
- Operational cost reduction: 70%
The plant achieved compliance with CETP discharge limits. The NF system required minimal space and was integrated without a full ETP rebuild.
Outcome: The NF-treated water was directly suitable for cleaning applications, while the remaining high-TDS concentrate was sent to the MEE (Multi-Effect Evaporator), ensuring a ZLD-compliant disposal pathway.
This is what NF for COD-TDS Reduction looks like in practice. The performance gap between a generic ETP and a purpose-designed NF system is significant in cost, space, and compliance outcomes.
System Maintenance: Protecting NF Membrane Performance
NF membranes handle difficult feed streams. Scale formation is the primary cause of performance decline over time. Calcium carbonate, calcium sulfate, and silica are the main culprits.
Proper antiscalant dosing significantly extends membrane life and maintains TDS rejection at design levels throughout the operating year. ROPUR antiscalants for RO and NF systems are used in Jay Water’s NF installations certified to NSF and KIWA international standards, and compatible with Toray polyamide NF membranes.
The NF membrane’s hydrophobic, antifouling surface helps with surface chalking and organic deposits. But chemical protection against scaling ions remains essential, especially in industrial streams with high hardness or sulfate levels.
Why Jay Water for NF Membrane Selection?
Jay Water is India’s authorised distributor of Toray membranes, one of the most trusted NF and RO membrane manufacturers globally. Toray has been producing NF membrane elements since 1967 and manufactures under ISO-9001 certification.
Jay Water has installed over 255,500 RO and NF membrane elements across industrial, municipal, and desalination applications in India and internationally. The technical team includes experienced engineers who provide water analysis, membrane sizing, system design, and post-installation support.
This matters for NF selection because the margin between the right membrane and the wrong one at the wrong operating Pressure can be the difference between 50% and 90% TDS rejection on the same feed water.
For full product information, visit the Jay Water Products page. For Toray NF and RO specifications, visit the Toray Membrane Supplier India page.
Conclusion
Nanofiltration TDS reduction ranges from 30% to 93% in real-world applications. The exact figure depends on the membrane model, feed water composition, operating Pressure, and system design.
NF is not a compromise. For hardness removal, COD reduction, dye rejection, and RO pretreatment, it is often the most efficient choice, with 30–50% lower energy consumption than RO and recovery rates of 85–90%.
Choose NF when you need selective salt removal, not total demineralisation. Choose RO when you need near-zero TDS output or are treating seawater. Consider a hybrid NF+RO system when feed TDS is in the 5,000–15,000 ppm range.
If you are evaluating NF for an industrial or municipal application, contact Jay Water for water analysis, membrane sizing, and system design guidance. Any system recommendation should be based on actual feed water data, not estimated TDS figures.
Frequently Asked Questions
How much TDS can a nanofiltration membrane remove?
NF membranes remove between 30% and 93% of TDS depending on membrane type, feed water chemistry, and operating Pressure. Tight NF membranes at 10 bar pressure achieve up to 93% TDS rejection on industrial wastewater. For typical brackish water, published studies have reported rejection rates ranging from 43% to 88%.
Is nanofiltration better than reverse osmosis for TDS removal?
Not always. RO removes over 95–99% of dissolved salts, including both monovalent and divalent ions. NF removes divalent ions very effectively (92–97%) but lets more monovalent ions through. NF is better when selective removal is the goal, particularly for hardness reduction, color removal, and RO pretreatment. RO is better when you need near-total desalination.
What is the operating Pressure for nanofiltration membranes?
NF membranes typically operate at 5–15 bar (75–150 psi). This is significantly lower than that of RO systems, which require 10–70 bar depending on feed salinity. Lower Pressure means lower energy consumption. NF uses 30–50% less energy than RO for equivalent flow rates.
Can NF membranes be used for seawater treatment?
NF membranes are used in seawater applications, primarily as pretreatment before high-pressure seawater RO systems. As a standalone desalination step, NF achieves limited TDS removal (around 30%) on full seawater salinity. Its main value in seawater systems is reducing calcium, magnesium, and organic fouling load on the RO membrane.
What does nanofiltration remove most effectively?
NF membranes remove divalent ions most effectively: calcium sulfate (97.4%), sodium sulfate (97.3%), magnesium sulfate (95.2%), and magnesium chloride (93.4%). They also remove colour, large organic molecules, and most bacteria and viruses. Monovalent ions like sodium chloride are partially retained (around 79%).
When should I use NF instead of RO?
Use NF when the feed TDS is 5,000–8,000 ppm or lower, the primary issue is hardness or divalent ion removal, full demineralisation is not required, or you need cost-efficient pretreatment for a downstream RO system. NF is also preferred when energy costs are critical or when treated water will be reused for industrial washing and cleaning rather than for drinking or pharmaceutical purposes.
How do I protect NF membrane performance over time?
Antiscalant dosing is essential for NF systems handling hard water or high-sulfate streams. Antiscalants prevent scale formation from calcium carbonate, calcium sulfate, and silica on the membrane surface, keeping TDS rejection at design levels and extending membrane life. Regular CIP (clean-in-place) protocols and proper pretreatment also maintain NF performance.
What is the water recovery rate for NF systems?
NF systems can achieve recovery rates of 75–90% with proper pretreatment and antiscalant dosing. This is generally higher than that of standard RO systems, which typically recover 50–75% of the feed water. Higher recovery means less reject volume, an important operational and environmental factor for industrial facilities targeting ZLD compliance.
