The Airlift External Loop Bioreactor is a high-efficiency reactor that operates without mechanical agitation, relying on gas-liquid density difference to drive circulation through an external loop. The key distinction from internal loop designs is that the circulation channel is positioned outside the main vessel. This configuration offers significant advantages in heat exchange capability and scalability, making it particularly suitable for highly exothermic reactions and viscous systems.
Core Structure
The system consists of a vertical cylindrical main vessel with a sterile gas sparger at the bottom (jet ejector, microporous disc, or ring sparger) and a gas-liquid separation zone with exhaust at the top. An external circulation pipe, independent of the main vessel, forms a complete loop circuit. Jacket or external coil provides temperature control, with online pH, DO, and temperature monitoring. CIP/SIP ports, inoculation, sampling, and discharge connections are included. Optional components include bubble cutters, baffles, heat exchangers integrated into the circulation pipe, and static mixers.
Working Principle
Sterile air is injected at high velocity through the sparger into the bottom of the riser section, creating a gas-liquid mixture with high gas holdup and low density. Driven by kinetic energy and density difference, this mixture rises rapidly through the riser. At the top gas-liquid separation zone, gas is released and degassed liquid returns to the bottom via the downcomer by gravity, where it mixes with incoming air to complete the external loop circulation. This achieves efficient mixing and oxygen mass transfer without any mechanical impeller.
Key Advantages
The external loop design allows convenient installation of heat exchangers on the circulation pipe, making it ideal for highly exothermic reactions and viscous systems. The reactor is easier to scale up than internal loop designs due to flexible pipe sizing and layout. Low shear forces make it suitable for plant cells, animal cells, and filamentous fungi. Fewer sealing points and dead zones compared to mechanically agitated vessels enable more thorough CIP/SIP cleaning.
Limitations
Energy consumption is lower than mechanically agitated vessels but typically slightly higher than internal loop designs of the same specification. External piping adds system resistance and requires more installation space.
Typical Applications
The airlift external loop bioreactor is used in environmental wastewater treatment for high-concentration organic wastewater aerobic treatment, nitrification/denitrification, and algae cultivation. In biomanufacturing, it serves for yeast and single-cell protein production, organic acids, and enzymes. Plant cell culture for secondary metabolite production is also a key application. In chemical and energy sectors, it is used for microalgae cultivation for biodiesel feedstock and gas-liquid absorption reactions.
Manufacturing Expertise and Support
NanJing TianHong Bioengineering Equipment Co., Ltd. holds patents for airlift external loop fermenters and has designed and manufactured units up to 150 m³ for pyruvic acid production. The company's technical team has over 30 years of experience and holds ISO9001 certification, special equipment production licenses, and more than 30 fermentation-related patents. With over 500 fermentation projects completed and 3,000+ bioreactors supplied, the company provides comprehensive engineering support.
Product Specifications
|
Parameter |
Description |
|
Vessel Type |
Vertical cylinder with external circulation pipe |
|
Gas Sparger |
Jet ejector / microporous disc / ring sparger |
|
Heat Exchange |
Jacket or external coil; optional heat exchanger on circulation pipe |
|
Circulation Drive |
Gas-lift driven (no mechanical agitation) |
|
Shear Level |
Low – suitable for shear-sensitive cells |
|
Sterilization |
In-situ steam sterilization (SIP) |
|
Typical Scale |
Laboratory to industrial (150 m³ demonstrated) |
Hot Tags: airlift external loop fermenter, China airlift external loop fermenter manufacturers, suppliers, factory
