In the field of modern biomanufacturing, with the continuous development of biotechnology and bioengineering technology, the fermentation process has gradually evolved from traditional empirical operation to high-precision, automation and large-scale production. As core production equipment, bioreactors and fermenters not only undertake key tasks such as microbial culture, cell expansion and metabolite production, but their supporting fermentation systems have also gradually formed a highly integrated engineering system. In this system, fluid conveying equipment—especially various types of pumps—play a vital role. Whether it is medium delivery, feeding control, circulating heat exchange, aseptic transfer, or CIP/SIP cleaning, none can do without reasonably selected and configured pump equipment.
This paper analyzes the common types, application functions and engineering selection strategies of pumps in fermenter systems, focusing on the application characteristics and applicable scenarios of centrifugal pumps, rotary pumps, diaphragm pumps and sanitary centrifugal pumps in bioreactors and fermentation systems.
1. Functional Positioning of Pump Equipment in Fermentation Systems
In a complete fermentation system, a pump is not only a simple conveying tool, but also an important component to ensure process stability and aseptic safety. Its main functions include:
1.1 Medium Delivery and Feeding Control
In batch or continuous fermentation processes, it is necessary to accurately deliver the basal medium, carbon source, nitrogen source and inducer to the bioreactor at a set flow rate.
1.2 Material Circulation and Heat Exchange
Some large-scale bioreactors require external circulation heat exchange or homogenization treatment, with pumps serving as the power source for circulation.
1.3 Aseptic Transfer and Harvest
The transfer of fermentation broth to downstream separation equipment, such as centrifuges or membrane filtration systems, must ensure no pollution and low shear.
1.4 Conveying for Cleaning and Sterilization Systems
The circulating delivery of CIP cleaning fluid and SIP steam systems has high requirements for the temperature and corrosion resistance of pumps.
1.5 Conveying of High-Viscosity or Solid-Containing Materials
Fungal fermentation or high-density culture often forms high-viscosity systems, which require specially structured pumps to achieve stable delivery.
Therefore, pumps in the fermentation system are not only related to conveying efficiency, but also directly affect cell activity, product yield and the aseptic grade of the system.
2. Common Types and Application Characteristics of Pumps in Fermenter Systems
2.1 Centrifugal Pumps
Centrifugal pumps are the most widely used power pumps in fermentation systems. Their working principle is to generate centrifugal force through the rotation of impellers, which flings the liquid from the center to the outer edge to form pressure delivery.
Main Characteristics:
- Simple structure, large flow rate and stable operation
- Suitable for low-viscosity liquids
- Easy maintenance and low cost
- Continuous flow with small pulsation
Typical Applications:
- Medium delivery
- Cooling water circulation
- CIP cleaning fluid circulation
- External circulation heat exchange systems
In the supporting systems of large-scale bioreactors, centrifugal pumps are often used for the delivery of liquids that do not directly contact fermentation materials or have low shear sensitivity. However, their disadvantages are also obvious: weak conveying capacity for high-viscosity or solid-containing materials, and high-speed shear may damage cells.
2.2 Sanitary Centrifugal Pumps
Sanitary centrifugal pumps are high-cleanliness equipment specially designed for the bioengineering and pharmaceutical industries on the basis of traditional centrifugal pumps. Their internal structure adopts a dead-angle-free design, and the materials meet the standards for food or pharmaceutical contact.
Main Characteristics:
- High surface finish to reduce microbial adhesion
- Enable in-place cleaning (CIP) and in-place sterilization (SIP)
- Leak-proof sealing structure
- Compliance with GMP sanitary specifications
Typical Applications:
- Aseptic medium delivery
- Fermentation broth transfer
- Discharging of bioreactors
- Aseptic circulation systems
In modern biotechnological production, sanitary centrifugal pumps have become standard equipment, especially widely used in the production of antibiotics, enzymes, vaccines and recombinant proteins.
2.3 Rotary Pumps (Positive Displacement Rotary Pumps)
Rotary pumps are positive displacement pumps that form a closed cavity through the intermeshing of two or more rotors to push materials from the inlet to the outlet.
Main Characteristics:
- Low-shear delivery
- Suitable for high-viscosity materials
- Capable of conveying particle-containing or cell suspensions
- Stable flow rate and reversible delivery
Typical Applications:
- Delivery of high-density fermentation broth
- Transfer of fungal or filamentous fungal culture broth
- Feeding of high-viscosity nutrient solutions
- Delivery of downstream concentrated liquids
In some bioreactors, especially in fermentation processes with gradually increasing viscosity (such as polysaccharide, protein or cell culture), rotary pumps can effectively avoid shear damage to cell structures.
2.4 Diaphragm Pumps
Diaphragm pumps realize liquid suction and discharge by changing the cavity volume through the reciprocating motion of a flexible diaphragm. Their most prominent feature is the complete isolation between the conveying medium and the driving structure.
Main Characteristics:
- Fully sealed with no risk of leakage
- Capable of conveying corrosive liquids
- Strong self-priming capacity
- Enabling dry running
- Obvious pulsating flow
Typical Applications:
- Small-dose feeding systems
- Dosing of acid and alkali solutions
- Delivery of aseptic additives
- Transfer of hazardous or volatile liquids
In bioreactors with precise feeding control, diaphragm pumps are often used as metering and conveying equipment, especially suitable for micro-addition systems.
3. Comparison of the Process Roles of Different Pumps in Bioreactors
From a bioengineering perspective, the selection of different pumps directly affects the physiological environment of the fermentation process:
|
Pump Type |
Shear Intensity |
Viscosity Adaptability |
Aseptic Control |
Applicable Scenarios |
|
Centrifugal Pump |
Medium |
Low |
General |
Large-flow circulation |
|
Sanitary Centrifugal Pump |
Medium |
Low |
High |
Aseptic delivery |
|
Rotary Pump |
Low |
High |
High |
High-viscosity fermentation broth |
|
Diaphragm Pump |
Low |
Medium |
High |
Precision feeding |
In animal cell culture or the fermentation of shear-sensitive microorganisms, low-shear delivery is particularly critical, so rotary pumps or diaphragm pumps are more advantageous.
4. Core Engineering Principles for Pump Selection in Fermentation Systems
4.1 Selection Based on the Characteristics of Fermentation Medium
- Low-viscosity liquids: Prioritize centrifugal pumps or sanitary centrifugal pumps
- High-viscosity systems: Prioritize rotary pumps
- Particle- or mycelium-containing materials: Low-shear positive displacement pumps
- Corrosive media: Diaphragm pumps or corrosion-resistant materials
4.2 Selection Based on Aseptic Grade Requirements
In the production of pharmaceutical biotechnology:
- Must be capable of CIP/SIP
- Dead-angle-free structure
- Reliable sealing
- High surface finish
Sanitary centrifugal pumps or sanitary rotary pumps are usually selected for such applications.
4.3 Selection Based on Shear Sensitivity
Animal cells, plant cells or fragile strains are extremely sensitive to mechanical shear, and high-speed impeller structures should be avoided.
Preferred Options:
- Rotary pumps
- Low-speed positive displacement pumps
- Flexible diaphragm pumps
4.4 Selection Based on Flow and Pressure Requirements
- Large flow rate and low pressure: Centrifugal pumps
- Small flow rate and high precision: Diaphragm pumps
- Stable volume delivery: Rotary pumps
4.5 Selection Based on the Level of System Automation
Modern fermentation systems are usually integrated with PLC or DCS, and pumps need to have the following features:
- Variable frequency speed regulation
- Flow feedback
- Automatic interlocking
- Remote control
5. The Impact of Bioengineering Scale-Up on Pump Selection
From laboratory bioreactors to industrial-scale bioreactors, scale-up significantly changes fluid characteristics:
- Increased viscosity
- Enhanced gas-liquid mass transfer
- Accumulated heat increase
- Extended conveying distance
Therefore, the pump type used in small-scale tests is often not suitable for industrial production, and it is necessary to re-conduct hydrodynamic calculations and evaluate conveying capacity.
6. Future Development Trends
With the upgrading of the biotechnology industry, pump equipment for fermentation systems is showing the following trends:
1. Higher sanitary grade
2. Lower shear design
3. Intelligent flow control
4. Online condition monitoring
5. Modular installation structure
At the same time, new magnetic drive seal-less pumps and single-use pump systems have also gradually entered the field of bioengineering.
7. Conclusion
In the operation system of modern bioreactors and fermenters, pumps have transformed from auxiliary equipment into key units affecting fermentation efficiency and product quality. Centrifugal pumps, sanitary centrifugal pumps, rotary pumps and diaphragm pumps each have structural advantages and process adaptability, and comprehensive selection should be made based on the characteristics of fermentation medium, aseptic requirements, shear sensitivity and system scale.
Scientific and reasonable pump configuration can not only improve the operational stability of the fermentation system, but also reduce the risk of pollution, protect cell activity, and improve the overall production efficiency of bioengineering. With the development of high-end biomanufacturing in the future, pump equipment will continue to evolve in the direction of intellectualization, sanitation and precise control, becoming an important engineering foundation for promoting the upgrading of the biotechnology industry.