Working Principles And Operating Procedures Of Fermentation Tanks

I. Working Principles of Fermentation Tanks

The core principle of a fermentation tank is to provide microorganisms with a suitable growth environment, enabling them to carry out specific metabolic activities and thereby produce the substances we require. Taking the common liquid deep-tank fermenter as an example, its primary principles are based on the following aspects:

1. Maintenance of a Sterile Environment

Fermentation processes demand an extremely high level of sterility to prevent contamination by unwanted microorganisms, which could compromise the fermentation results. Fermentation tanks feature a sealed design and employ methods such as steam sterilization to thoroughly sterilize the tank vessel, piping, and internal components prior to fermentation, thereby ensuring the purity of the fermentation environment.

2. Temperature Control

The growth and metabolism of microorganisms are highly sensitive to temperature. Different microorganisms possess specific optimal temperature ranges for growth; for instance, the optimal temperature for yeast fermentation to produce alcohol typically falls between 25°C and 30°C. Fermentation tanks are equipped with temperature control systems that utilize structures such as jackets or internal coils. By circulating a thermal medium (e.g., hot water) or a cooling medium (e.g., cold water) through these structures, the system regulates the temperature inside the tank, ensuring it remains consistently within the optimal temperature range for microbial growth.

3. Aeration and Agitation

For aerobic fermentation processes, an adequate supply of oxygen is critical. This is achieved by introducing sterile air into the fermentation tank and utilizing an agitation device to disperse the air into minute bubbles, thereby increasing the gas-liquid contact area and satisfying the microorganisms' oxygen requirements. Furthermore, agitation ensures the uniform distribution of nutrients throughout the fermentation broth, facilitating full contact between the microorganisms and the nutrient components; it also aids in heat dissipation, preventing localized overheating within the tank. 4. pH Adjustment

The metabolic activities of microorganisms can cause fluctuations in the pH of the fermentation broth; however, maintaining an appropriate pH level is a prerequisite for the normal growth and metabolism of these microorganisms. Fermentation tanks are typically equipped with pH monitoring and control systems capable of automatically adding acid or alkali solutions to make adjustments whenever the pH value deviates from the preset range.

II. Fermentation Tank Operation Procedures

1. Equipment Preparation

Before utilizing a fermentation tank, a comprehensive inspection of the equipment must be conducted to ensure that all components are intact, pipeline connections are secure, and there are no leaks. Sensors for parameters such as temperature, pH, and dissolved oxygen should be checked to verify proper functionality and subsequently calibrated. In strict accordance with standard operating procedures, the fermentation tank and associated pipelines must undergo thorough cleaning and sterilization; methods such as high-temperature steam sterilization or chemical sterilization may be employed.

2. Culture Medium Preparation and Inoculation

Based on the specific requirements of the fermentation process, the culture medium must be prepared with precision to ensure that its nutritional composition adequately meets the growth and metabolic needs of the microorganisms. The prepared culture medium is then transferred into the fermentation tank using aseptic techniques. Under sterile conditions, an appropriate volume of microbial seed culture is introduced into the tank; the specific inoculation volume should be determined based on the particular fermentation process and the characteristics of the microorganisms being used.

3. Fermentation Process Control

Once the fermentation process has commenced, all relevant parameters must be monitored closely. Adjustments to parameters—such as temperature, aeration rate, and agitation speed—should be made based on the observed microbial growth status and the progression of the fermentation. For instance, during the initial phase of fermentation, when microbial growth is vigorous and oxygen demand increases, the aeration rate and agitation speed may be appropriately increased. As the fermentation proceeds, the accumulation of metabolic products may cause shifts in pH levels, necessitating timely pH adjustments. Periodic sampling and analysis of the fermentation broth are essential for monitoring indicators such as microbial concentration, substrate consumption, and product formation, thereby enabling timely adjustments to the fermentation conditions.

4. Fermentation Completion and Downstream Processing

When the fermentation process has reached its intended objective or endpoint, the process is terminated. The fermentation broth is then transferred via sterile pipelines to downstream processing equipment—such as separation and purification systems—for further processing. The fermentation tank must subsequently undergo cleaning and disinfection to prepare it for the next fermentation run. Finally, any generated waste gas or wastewater must be treated appropriately to ensure compliance with environmental protection regulations.

III. Conclusion

A thorough understanding of both the underlying principles and the operational methods of fermentation tanks is the key to achieving efficient and stable fermentation production. Rooted in the fundamental design principles of the equipment, we strictly control every stage of the operational process to ensure that microorganisms grow and metabolize within an optimal environment, thereby providing high-quality fermentation products to various industries.