In-depth Analysis of Nanofiltration Salt Separation Technology: Theory, Efficiency, Operating Conditions, Design Selection, and Cleaning & Maintenance

Overall, the comprehensive operating cost per ton of water for a nanofiltration (NF) salt separation unit is approximately ¥20–35 (excluding subsequent evaporation and crystallization). When incorporating an MVR evaporator-crystallizer, the total comprehensive treatment cost per ton of water for the entire zero-liquid-discharge (ZLD) system typically ranges from ¥30 to ¥50. 3. Economic Return Analysis The economic returns of NF-based salt separation stem primarily from three sources: (1) recovery of water resources—permeate reused for circulating cooling water or process water, thereby reducing industrial water procurement costs; (2) recovery of industrial salt products (e.g., NaCl, Na₂SO₄), which can be sold externally or reused internally; and (3) avoidance of hazardous waste disposal costs for mixed salts—the most significant economic driver. Mixed-salt disposal typically costs ¥1,000–3,000 per ton, whereas separated high-purity salts can be sold commercially, yielding substantial net economic benefit through both revenue generation and cost avoidance. Case Study Economics: In the aforementioned coal chemical project treating 360 m³/h, annual external sales revenue from NaCl and Na₂SO₄ crystalline salts totals ~¥1.65 million; using NaCl solution as a resin regeneration agent generates ¥0.25 million annually; and avoided mixed-salt disposal costs translate into an indirect annual benefit of ¥89.52 million. The total annual economic benefit exceeds ¥30 million. The higher the mixed-salt disposal cost, the more pronounced the economic advantage of salt separation. Summary and Outlook At its core, NF-based salt separation relies on precise control of membrane pore structure and surface properties, leveraging combined physical and chemical effects to achieve ion-level selectivity. Engineering success hinges not solely on pursuing ultra-high rejection rates, but rather on matching appropriate membrane types and process parameters to site-specific water quality—achieving optimal balance among salt separation precision, water recovery rate, and operational cost. Recent trends highlight three key development directions: (1) Accelerated domestic membrane substitution—domestic NF salt-separation membranes from companies such as SINOFILM (Time Water) and Haina Environmental Protection have achieved large-scale deployment in flagship projects of China National Coal Group and Sinopec, offering notable price advantages and continuously narrowing performance gaps; (2) Expanded application of high-pressure salt-separation membranes—as ZLD projects demand ever-higher recovery rates, high-pressure NF membranes rated for 8.27 MPa are increasingly adopted in deep-concentration segments of brine streams; and (3) Intelligent operation and maintenance—AI-assisted technologies—including membrane fouling prediction, optimized cleaning scheduling, and adaptive parameter adjustment—are transitioning from laboratory validation to real-world engineering implementation, promising further reductions in O&M costs and extended membrane service life. Finally, returning to engineering practice: NF-based salt separation is not a “plug-and-play” technology. Success requires deep mechanistic understanding and accumulated engineering experience across every stage—from raw water characterization and bench-scale testing, through process design and membrane selection, to long-term operation and maintenance. We hope this article’s theoretical framework and practical insights provide valuable reference for engineers and technical decision-makers engaged in high-salinity wastewater ZLD applications. — End of Article — Appendix: Data Sources and References 1. Technical Guidelines for Nanofiltration–Reverse Osmosis Salt Separation Treatment of Industrial High-Salinity Wastewater 2. Operational data from a petrochemical enterprise’s high-salinity wastewater ZLD salt separation project (50 m³/h, TDS 17,640–24,600 mg/L), Industrial Water Treatment 3. Public reports on the high-salinity wastewater ZLD project of Zhong’an United (coal chemical sector), 360 m³/h 4. Xiong Rihua et al., Salt Separation and Crystallization Processes for High-Salinity Wastewater and Their Technical-Economic Analysis, Beijing Institute of Low-Carbon Clean Energy / State Key Laboratory of Water Resource Protection and Utilization in Coal Mining

How a Strong RO Membrane Brand Name (Trademark) Enhances Professional Credibility and Business Growth for an RO Membrane Company: FILMTEC, the RO Membrane Subsidiary of U.S.-based DuPont

How a Strong RO Membrane Brand Name (Trademark) Enhances Professional Credibility and Business Growth for an RO Membrane Company: FILMTEC, the RO Membrane Subsidiary of U.S.-based DuPont Brand (Trademark): FILMTEC (Fei’oum Taik)—an abbreviation of FILM TECHNOLOGY, meaning “membrane technology.” Company Name: FILMTEC Corporation (U.S.), an RO membrane company headquartered in Minnesota (MN), USA. Parent Company Name: DuPont Polymers Inc. (U.S.), headquartered in Delaware (DE), USA. RO membranes are manufactured and spiral-wound at facilities in the U.S., Saudi Arabia, and Zhejiang Province, China. The Chinese market for RO and nanofiltration (NF) membranes for water treatment exceeds ¥7 billion. FILMTEC Corporation—a subsidiary of U.S.-based DuPont—holds over 40% market share in China. Globally, FILMTEC membranes command over 35% market share, far outpacing competitors and ranking #1 in the RO membrane industry. First-Tier RO Membrane Companies (Highest Tier, Premium Pricing): 1. Brand (Trademark): FILMTEC (Fei’oum Taik)—abbreviation of FILM TECHNOLOGY, meaning “membrane technology.” Company Name: FILMTEC Corporation (U.S.), headquartered in Minnesota (MN), USA. Former Parent Company: The Dow Chemical Company (U.S.), headquartered in Michigan (MI), USA. RO membranes are manufactured and spiral-wound in the U.S., Saudi Arabia, and Zhejiang Province, China. 2. Brand (Trademark): OSMONICS (Aosimosenis)—a near-literal reference to “osmosis,” reflecting the fundamental principle of reverse osmosis membrane operation. Company Name: OSMONICS Inc. (U.S.), headquartered in Minnesota (MN), USA. RO membranes are manufactured and spiral-wound in the U.S. 3. Brand (Trademark): DESAL (Disai’ou)—meaning “desalination,” directly referencing the core function of RO membranes. Company Name: DESAL Inc. (U.S.), a subsidiary of OSMONICS Inc. Headquartered in Minnesota (MN), USA. RO membranes are manufactured and spiral-wound in the U.S. 4. Brand (Trademark): FILMSEP (Feimu Saibo)—abbreviation of FILM SEPARATION, meaning “membrane separation.” Company Name: FILMSEP Inc. (U.S.), headquartered in Minnesota (MN), USA. RO membranes are manufactured and spiral-wound in the U.S. 5. Brand (Trademark): MEMSEP (Meimu Saibo)—abbreviation of MEMBRANE SEPARATION, meaning “membrane separation.”

DuPont Enhances FilmTec Portfolio with Advanced NF Technology

Apr 17, 2026

DuPont Water Solutions launched the FilmTec™ NF270 nanofiltration product to enhance water purification efficiency across industrial sectors. The technology reduces energy and chemical usage while effectively removing contaminants for pharmaceutical and food applications.

MSN

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DuPont Expands FilmTec™ Fortilife™ Portfolio for Advanced ZLD/MLD and Resource Recovery Applications

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