Application of Membrane Separation Technology in the Biopharmaceutical Industry

With the rapid development of the biopharmaceutical industry (the global market size exceeded USD 400 billion in 2024), products such as monoclonal antibodies (mAbs), recombinant proteins, vaccines, and gene therapy drugs have increasingly stringent requirements forhigh-precision separation, low-contamination purification, and retention of active ingredients. Traditional separation processes (such as centrifugation, precipitation, and chromatography) suffer from drawbacks like high energy consumption, chemical reagent residues, and loss of biological activity. In contrast,membrane separation technology, leveraging its core advantages of "molecular-level sieving, physical separation, and low-temperature operation", has become a key process in biopharmaceuticals—covering everything from fermentation broth pretreatment to final product sterility assurance—and is widely applied throughout the entire production process.

I. Fundamentals of Membrane Separation Technology: A "Precision Sieve" for the Biopharmaceutical Industry

Membrane separation technology is a physical separation method based onselectively permeable membranes. Driven by pressure (or concentration difference), it achieves the separation of different molecules through the "pore size sieving" or "charge effect" of the membrane. In the biopharmaceutical field, common membrane types are classified into 4 categories by separation precision, each adapted to different process requirements:

Compared with traditional processes, membrane separation technology requires no chemical reagents, operates at room temperature (25-40℃) throughout the process, maximizes the retention of the activity of biopharmaceutical products, and complies with strict regulatory requirements such as GMP (Good Manufacturing Practice) and FDA (U.S. Food and Drug Administration). It has thus become one of the core technologies for "green production" in biopharmaceuticals.

II. Core Application Scenarios of Membrane Separation Technology in the Biopharmaceutical Industry

Membrane separation technology runs through the entire biopharmaceutical production process—"pretreatment-purification-concentration-sterility-environmental protection"—with different membrane types providing solutions for different process pain points:

1. Fermentation Broth Pretreatment: MF Membranes for Bacteria and Large-Particle Impurity Removal

Core raw materials in biopharmaceuticals (e.g., fermentation broths for mAbs and insulin) contain large amounts of bacteria (e.g.,E. coli, CHO cells), cell debris, and suspended particles. Direct entry into subsequent purification processes would cause chromatography column clogging, resin contamination, and increased production costs.

Solution: Use0.22-1 μm MF membranes(common materials: PVDF, PES—with good acid-base resistance and biocompatibility) for pretreatment. Under low pressure (0.1-0.3 MPa), bacteria and cell debris are retained, while the permeate (containing target products) directly enters the UF purification stage.

Advantages: Replaces traditional centrifugation processes, achieving a bacteria removal rate of ≥99.9%, reducing subsequent resin loss by over 30%, and featuring high operational automation—meeting GMP requirements for "minimizing manual intervention".

Typical Case: In the pretreatment of recombinant human insulin fermentation broth, MF membranes can increase the bacteria removal rate to 99.99% and the permeate clarity to 99%, laying a solid foundation for subsequent UF purification.

2. Target Product Purification: UF Membranes for Molecular-Level Precision Sieving

A core requirement in biopharmaceuticals is the separation of high-purity target products from complex systems (e.g., mAbs have a molecular weight of approximately 150 kDa, while most impurity proteins have a molecular weight of ＜50 kDa). Traditional chromatography processes are costly and time-consuming.

Solution: SelectUF membranesbased on the molecular weight of the target product (e.g., 100 kDa MWCO membranes for mAb purification). Under pressure (0.2-0.5 MPa), the target product is retained, while the permeate (containing impurity proteins, nucleic acids, and small-molecular impurities) is directly discharged or recycled.

Advantages: Enables "one-step purification" with a target product recovery rate of ≥95% and a purity increase of 20-40%. Its energy consumption is only 1/5 of that of chromatography processes, making it suitable for large-scale industrial production.

Typical Case: In mAb production, 100 kDa UF membranes are used to remove impurity proteins and nucleic acids with molecular weights below 50 kDa. Subsequent chromatography only needs to be performed once to meet pharmacopoeia purity requirements, shortening the production cycle by 40%.

3. Feed Solution Concentration and Desalination: NF/RO Membranes for Cost Efficiency

Biopharmaceutical feed solutions (e.g., peptides, antibiotics) typically have low concentrations (1-5%) and high salt contents, requiring concentration to 20-30% to meet subsequent drying or formulation needs. Traditional vacuum evaporation concentration risks damaging active ingredients due to high temperatures.

Solution:

• For concentration needs: UseNF membranes(200-1000 Da MWCO). Under pressure (0.8-1.5 MPa), peptides/antibiotics are retained, water is removed, and the concentration multiple can reach 5-10 times.
• For desalination needs: Adopt the "diafiltration-concentration" mode ("concentration-water dilution-reconcentration"). NF membranes are used to remove over 80% of inorganic salts (e.g., sodium chloride) from the feed solution, avoiding salt interference with subsequent formulation.

Advantages: Operates at room temperature, with an active ingredient retention rate of ≥98%. Its energy consumption is only 1/3 of that of vacuum evaporation, and no chemical reagents are added—meeting the requirements for injectable drugs.

Typical Case: In the concentration of peptide drugs (e.g., growth hormone), NF membranes concentrate the feed solution from 3% to 25% while achieving a desalination rate of 85%. The activity loss is only 1.2%, far lower than the 5-8% loss rate of traditional processes.

4. Sterile Filtration and Final Product Assurance: MF Membranes as the "Last Line of Defense"

Biopharmaceutical final products (e.g., vaccines, injectable mAbs) require absolute sterility (complying with the sterility test requirements of theChinese Pharmacopoeia). Traditional moist heat sterilization damages biological active ingredients and is therefore inapplicable.

Solution: Use0.22 μm sterilizing-grade MF membranes(materials: PTFE, PVDF—with solvent resistance and high-temperature sterilization compatibility). Sterile filtration is performed before final product filling to retain microorganisms such as bacteria, fungi, and spores, achieving a sterilization rate of ≥99.999%.

Advantages: Enables room-temperature sterile filtration without affecting product activity. Membrane modules support in-place sterilization (SIP), meeting GMP's strict requirements for "sterile production".

Typical Case: In COVID-19 vaccine production, 0.22 μm MF membranes are used for final product sterile filtration, achieving a sterilization rate of 99.9999% and a vaccine activity retention rate of ≥99%, ensuring vaccine safety and efficacy.

5. Wastewater Treatment and Resource Recovery: Membrane Technology for Environmental Compliance

Biopharmaceutical wastewater (e.g., fermentation wastewater, cleaning wastewater) contains high-concentration organic matter (COD ＞5000 mg/L) and residual drug components. Direct discharge causes environmental pollution, and traditional biochemical treatment struggles to meet discharge standards.

Solution: Adopt a combined membrane system of "MF + UF + RO". First, MF/UF removes suspended solids and large-molecular organic matter from wastewater. Then, RO membranes perform advanced treatment—the permeate (pure water) can be reused for production cleaning, while the concentrate (high-concentration organic matter) can be incinerated or treated anaerobically.

Advantages: Wastewater reuse rate ≥70%, COD removal rate ≥95%, complying with theDischarge Standard of Water Pollutants for Biopharmaceutical Industry(GB 21907-2008) while reducing the enterprise's fresh water consumption costs.

III. Core Advantages of Membrane Separation Technology Empowering Biopharmaceuticals

Compared with traditional processes such as centrifugation, precipitation, and chromatography, the advantages of membrane separation technology in the biopharmaceutical industry can be summarized as "four highs and two lows":

1. High Activity Retention: Low-Temperature Operation Safeguards Biological Value

Biopharmaceutical products (e.g., proteins, vaccines) are temperature-sensitive. Traditional thermal concentration (60-80℃) causes 10-30% activity loss. Membrane separation technology operates at room temperature throughout the process, with an active ingredient retention rate of ≥95%—especially suitable for high-value products such as mAbs and gene therapy drugs.

2. High Purity Assurance: Molecular-Level Sieving Reduces Impurities

UF/NF membranes enable "precision retention", increasing target product purity by 20-40% and removing over 80% of impurity proteins, nucleic acids, and inorganic salts. This reduces subsequent purification steps and lowers process complexity.

3. High Compliance: Meeting GMP and International Standards

Parts of membrane modules in contact with feed solutions are made of materials such as 316L stainless steel and food-grade PVDF. They support in-place cleaning (CIP) and in-place sterilization (SIP), and can provide complete validation documents (DQ/IQ/OQ/PQ)—meeting regulatory requirements of the FDA, EMA (European Medicines Agency), and other international authorities.

4. High Automation: Reducing Labor and Contamination Risks

Membrane systems support PLC (Programmable Logic Controller) fully automatic control, enabling real-time monitoring of parameters such as pressure, flow rate, and concentration, as well as unattended operation. This reduces contamination risks caused by manual intervention, aligning with the trend of "closed production" in biopharmaceuticals.

5. Low Energy Consumption: Reducing Production Costs

The energy consumption of membrane separation technology is only 1/3-1/5 of that of traditional processes (e.g., UF concentration consumes approximately 0.5 kW·h/m³, while vacuum evaporation consumes approximately 2.5 kW·h/m³). For large-scale production, this can save millions of yuan in annual energy costs.

6. Low Pollution: Green Production Reducing Environmental Pressure

No chemical reagents are added throughout the process, and the wastewater reuse rate is ≥70—reducing pollutant discharge, helping biopharmaceutical enterprises achieve "carbon neutrality" goals, and aligning with national "green manufacturing" policy guidelines.

IV. Key Considerations for Selecting Membrane Separation Technology in the Biopharmaceutical Industry

Despite its significant advantages, biopharmaceutical enterprises need to align membrane separation technology with their specific process requirements during selection to avoid potential risks:

1. Membrane Material Selection: Prioritizing Biocompatibility and Corrosion Resistance

• Membrane materials in contact with injectable drugs must meet USP Class VI biocompatibility requirements (e.g., PVDF, PES, PTFE).
• For acidic/alkaline feed solutions (e.g., fermentation broths with pH 2-10), acid-base resistant membranes should be selected (e.g., PVDF membranes with pH tolerance of 1-14) to prevent impurity leaching caused by membrane degradation.

2. Membrane Fouling Control: Extending Membrane Lifespan and Reducing Costs

Biopharmaceutical feed solutions (e.g., those containing proteins and polysaccharides) are prone to causing membrane fouling, which can be controlled through three measures:

• Pretreatment: First, remove large particles via 5-10 μm precision filtration to reduce membrane clogging.
• Process Design: Adopt "cross-flow filtration" (high-speed flow of feed solution along the membrane surface) to reduce solute adhesion.
• In-Place Cleaning: Regularly clean with acids (citric acid), alkalis (sodium hydroxide), and enzyme preparations to extend membrane lifespan to 2-3 years.

3. Process Customization: Matching Different Drug Production Needs

• For mAb/recombinant protein production: Focus on the combination of "UF purification + NF concentration".
• For vaccine production: The core requirement is "MF sterile filtration", requiring high-flow sterilizing membranes.
• For peptide/antibiotic production: Focus on "NF desalination + concentration" to ensure salt content meets standards.

V. Development Trends of Membrane Separation Technology in the Biopharmaceutical Industry

As biopharmaceuticals move toward "personalized drugs" (e.g., CAR-T cell therapy) and "complex formulations" (e.g., bispecific antibodies, ADC drugs), membrane separation technology continues to evolve, with three key future trends:

1. Development of High-Performance Membrane Materials: Focus on Fouling Resistance and High Flux

R&D directions include:

• Anti-fouling coated membranes (e.g., hydrophilic modified PVDF membranes) to reduce protein adsorption and increase membrane flux by 30%.
• High-temperature/solvent-resistant membranes (e.g., ceramic UF membranes) to meet the high-temperature sterilization needs of gene therapy drugs.
• High-selectivity membranes (e.g., affinity UF membranes) to achieve "one-step capture" of target products, replacing some chromatography processes.

2. Membrane System Integration: Linking with Other Processes to Improve Efficiency

Future membrane systems will integrate with chromatography, chromatography, and continuous production (PAT) technologies to form integrated production lines of "pretreatment-purification-concentration-sterility". Examples include:

• Linkage of "MF + UF + chromatography" to reduce intermediate storage tanks and shorten the production cycle by 50%.
• Integration of online monitoring (PAT) with membrane systems to adjust parameters in real time and ensure product quality stability.

3. Expansion of Application Scenarios: Extending to Cell Therapy and Gene Drugs

In emerging fields such as CAR-T cell therapy and adenovirus vector vaccines, membrane separation technology will be used for:

• Cell washing (removal of medium impurities).
• Virus purification (retention of virus particles, removal of impurity proteins).
• Concentration of gene vectors (e.g., NF concentration of adeno-associated virus (AAV)), promoting the large-scale production of personalized biopharmaceuticals.

Membrane separation technology, with its core advantages of "precision, efficiency, greenness, and compliance", has become a key support for the biopharmaceutical industry's transformation from "traditional production" to "modernization, scale, and high quality". From fermentation broth pretreatment to final product sterility assurance, from reducing production costs to supporting environmental compliance, membrane separation technology is reshaping biopharmaceutical production processes. In the future, with the development of high-performance membrane materials and process integration, membrane separation technology will play a greater role in morespecialized fieldsof biopharmaceuticals (e.g., cell therapy, gene drugs), providing core impetus for the high-quality development of the global biopharmaceutical industry.