The main body of the fermenter is made of stainless steel, usually with a turbine agitator. The connection between the stirring shaft and the tank should be aseptically sealed. There is an air distributor or nozzle at the bottom of the fermenter tank, and the sterile air passing through the air filter is blown into the culture solution from a porous tube with a diameter of several millimeters. The stirrer is driven to rotate at a certain speed by the stirring motor placed on the top of the tank, and the swollen air is broken into small bubbles by the liquid vortex and shear force generated by the stirring turbine, which are evenly dispersed in the culture medium. In this way, the oxygen required for cell growth is provided, and the concentration of the culture medium is uniform at the same time.
The fermenters we use generally consist of the following five systems:
1. The mechanical stirring system of the fermentation
Tank is one of the main features of the aeration stirring tank. The power provided by the mechanical stirring system is the basic guarantee for the mass transfer, heat transfer, mixing and uniform distribution of the suspended matter in the mechanical stirring tank. The design and selection of the stirring device must be comprehensively considered to meet the above requirements and reduce the cost and power consumption.
The mechanical stirring system consists of a motor, a gearbox, a stirring shaft, a stirring paddle, a shaft seal and a baffle.
2. Ventilation system of the fermentation tank The ventilation
System is composed of a sterile air preparation system, an air distribution device and an outlet gas sterilization system. The sterile air preparation system is a relatively independent complex system.
The sterile air required for cell growth and metabolism is introduced into the tank through an air distribution pipe. The air distribution pipe is generally located directly below the lowermost stirring paddle. In order to ensure the dispersion of air bubbles, annular air distribution pipes with small holes are often used, and the diameter of the ring is generally equal to the diameter of the stirring paddle. In a large ventilated stirring tank, the shear force near the tip of the stirring paddle is very large, which is generally sufficient to fully break the air bubbles. Systems sometimes employ single-hole tubes that open downwards.
3. The temperature control system of the fermentation tank
In order to ensure the appropriate temperature for cell growth and metabolism, the temperature control system is also necessary for the aeration and stirring tank. The temperature control system consists of temperature measuring electrodes, heat exchange devices and corresponding control devices. Since both biological reactions and mechanical agitation are exothermic processes, most biological reaction systems require cooling during operation, and the culture medium after in-situ sterilization requires rapid cooling.
4. The pH value of the fermenter and the dissolved oxygen measurement and control system
Have the optimum pH value for cell growth, so it is necessary to detect and control the pH of the culture medium.
The pH control system consists of pH electrodes, acid and alkali storage tanks, acid or alkali resistant pipes and pumps, and corresponding control systems. According to the actual needs of different biological reaction systems, only acid or alkali system can be added, or both can be provided. During fed-feed culture, feeding through carbon sources or/and nitrogen sources can also play a role in adjusting pH.
5. The defoaming system of the fermentation tank
The defoaming system is very important to the aerobic fermentation process. The liquid filling volume of the aeration mixing tank generally cannot exceed 70-80% of the container volume. On the one hand, this is because the liquid level will rise after ventilation; more importantly, the reserved space can prevent the foam from rushing out of the tank immediately. body, providing a buffer time for the elimination of foam. Generally, for systems that are more prone to foaming, the less liquid is required. There is an additional paddle on top of the vented agitator, called a defoaming paddle, whose function is to mechanically eliminate foam. In most cases, the defoaming paddle alone is not enough to destroy all the foam in time, so it is usually necessary to further defoam by adding a chemical defoamer.
The above is about the following five systems of fermentation tanks. One of the following five systems is indispensable. Bioreactek is a manufacturer specializing in the development and production of fermentation tanks. The company has a group of professional technical teams, which are professionally customized for you. Please feel free to inquire at any time.