I. Working Principle of Fermentation Tanks
The core principle of fermentation tanks is to provide a suitable growth environment for microorganisms, enabling them to carry out specific metabolic activities and produce the substances we need. Taking a common submerged liquid fermentation tank as an example, its main principles are based on the following aspects:
1. Maintaining a Sterile Environment
The fermentation process requires extremely high sterility to prevent contamination by other microorganisms. Fermentation tanks employ a sealed design and undergo thorough sterilization of the tank body, pipes, and internal components before fermentation using methods such as steam sterilization, ensuring a pure fermentation environment.
2. Temperature Control
Microbial growth and metabolism are extremely sensitive to temperature. Different microorganisms have optimal growth temperature ranges; for example, the optimal temperature for yeast fermentation to produce alcohol is typically 25℃-30℃. Fermentation tanks are equipped with a temperature control system that uses a jacket or coil structure to regulate the internal temperature using a circulating heat medium (such as hot water) or a cooling medium (such as cold water), maintaining it within the optimal temperature range for microbial growth.
3. Aeration and Stirring
For aerobic fermentation processes, a sufficient supply of oxygen is crucial. By introducing sterile air into the fermenter and using a stirring device to disperse the air into tiny bubbles, the gas-liquid contact area is increased, thus meeting the oxygen requirements of microorganisms. Stirring also ensures the even distribution of nutrients in the fermentation broth, promoting full contact between microorganisms and nutrients, and aids in heat dissipation, preventing localized overheating.
4. pH Adjustment
The metabolic activities of microorganisms cause changes in the pH value of the fermentation broth, and a suitable pH value is a necessary condition for the normal growth and metabolism of microorganisms. Fermenters are usually equipped with pH detection and control systems that can automatically add acid or alkali solutions to adjust the pH value when it deviates from the set range.
II. Fermenter Operation Process
1. Equipment Preparation Before using the fermenter, a comprehensive inspection of the equipment must be conducted to ensure that all components are intact, pipe connections are tight, and there are no leaks. Check that the temperature, pH, and dissolved oxygen sensors are functioning properly and calibrate them. Thoroughly clean and sterilize the fermenter and related pipes according to the operating procedures, using methods such as high-temperature steam sterilization or chemical sterilization.
2. Culture Medium Preparation and Inoculation
Accurately prepare the culture medium according to the fermentation process requirements, ensuring its nutrient composition meets the needs of microbial growth and metabolism. Transfer the prepared culture medium to the fermenter using aseptic techniques. Under aseptic conditions, inoculate with an appropriate amount of microbial seed culture; the inoculation amount needs to be determined based on the specific fermentation process and microbial characteristics.
3. Fermentation Process Control
After fermentation starts, closely monitor all parameters. Adjust parameters such as temperature, aeration rate, and stirring speed according to microbial growth and fermentation progress. For example, in the early stages of fermentation, microbial growth is vigorous, and oxygen demand increases, so the aeration rate and stirring speed can be appropriately increased. As fermentation progresses, metabolic products accumulate, and the pH value may change, requiring timely pH adjustment. Regularly sample and test the fermentation broth to analyze indicators such as microbial concentration, substrate consumption, and product formation, in order to adjust fermentation conditions promptly.
4. Fermentation Completion and Subsequent Processing
When fermentation reaches the expected goal or endpoint, stop the fermentation process. Transfer the fermentation broth to subsequent processing equipment, such as separation and purification equipment, through aseptic pipelines. Clean and disinfect the fermenter to prepare for the next fermentation. Proper treatment of generated waste gas and wastewater is essential to meet environmental protection requirements.
III. Conclusion A correct understanding of the principles and operation methods of fermenters is crucial for achieving efficient and stable fermentation production. By starting from the equipment's design principles and strictly controlling every aspect of its use, it is possible to ensure that microorganisms grow and metabolize in the optimal environment, providing high-quality fermented products for various industries.