A bioreactor is a device that enables biological reactions. Bioreactors have plant cell bioreactor, algae bioreactor, mammalian cell bioreactor etc. If the product is to be fermented well, the process parameters must be strictly controlled. Today we will talk about temperature control and PH value control.
1. Bioreactor temperature control
Bioreactor temperature will affect the rate of the enzyme reaction and the solubility of oxygen in the culture medium during the fermentation process, which is closely related to the growth of the bacteria, the synthesis of antibiotics and the dissolved oxygen. Bioreactor temperature control mainly includes the control of heating and cooling. The heating capacity is calculated by the process. The cooling capacity refers to the cooling capacity required after heating or sterilization and under the specified cooling time.
Bioreactor temperature control consists of a heater and cooling water solenoid valve. When the temperature in the fermentation tank is lower (or higher) than a certain set value, the system will automatically turn on the heater (or cooling water solenoid valve).
Only by calculating the length of the pipeline, medium pressure and pressure loss, can the diameter of the heat exchange tube be determined, and then the diameter of the control valve can be determined. The diameter of the control valve is based on the control fluctuation of the culture temperature as the main parameter. If the control fluctuation amount of the culture temperature is used as a parameter to calculate, the opening degree of 60% to 80% can often be set as a stable value. To take into account the sterilization heating time, the value can be lower, and the fluctuation of the culture temperature control will be larger.
In a temperature control system with a hot and cold jacket, if the above-mentioned process parameters are calculated properly, the parameter control is relatively accurate, and the process parameters can be obtained by the calculation of the soaring curve or the empirical method. In the tank temperature control that takes into account both cultivation and sterilization, PID automatic control is used, and the fluctuation control range of the cultivation temperature is ±0.1 °C.
2. Bioreactor pH value control
The pH of the fermentation broth is a comprehensive reflection of the acidity and alkalinity of various biochemical reactions during the fermentation process.
There are two forms of pH value feeding: flow addition and dropwise addition. The pH control and feeding system is mainly composed of a peristaltic pump (or other conveying system) and a weighing system.
In addition to the weighing system, these control systems are greatly affected by the pressure difference between bio-fermenters, including the pressure changes caused by the liquid level. The weighing system is also affected by the fluctuation of the liquid level, so it depends on fermenter size, the ratio of diameter to height and the usage.
At present, the pH control device consists of an acid addition peristaltic pump and an alkali addition peristaltic pump. When the pH value is higher than the set value, the system automatically starts the acid-adding peristaltic pump, and feeds the acid liquid to the fermentation tank in a time-proportional manner until the set value. When the pH is less than the set value, start the alkali peristaltic pump for adjustment.