cell culture,cellculture,sterile equipment,liquid state fermentation,solid state fermentation,bioreactor,fermenter,fermentor bioreacter


 

Micro-giant BioEngineering  2009.06.19

        Process of microbial cultures for aerobic bacteria (some Chief aerobic bacteria, as the metabolic status), rich in a lot of oxygen is often at a certain stage of culture urgent needs, so the control strategy for the high dissolved oxygen (DO CASCADE) Provision Description

As follows: (Note that the phenomenon is often accompanied by a large number of high-density fermentation foaming Foaming of troubled high dissolved oxygen)

 

First, the speed:
        Liquid state fermentation process, the effective agitation can cause the quality can be transmitted quickly and also contains oxygen in the air is dissolved in the fermentation broth extent improve. Too high stirring speed will cause a sharp increase in the shear force (shear force), computer time increase or decrease the speed setting, and wait for a period of time, observed DO values ​​change automatically corrected. And must be accompanied by the speed the lower limit set to define live variable factors be adjusted within a certain range, not unlimited increase or decrease the speed, only in order to meet DO set. However, if the upper limit is reached, not yet improve dissolved oxygen to the expected value of the program by setting automatic transfer to the next control strategies, such automatic transfer control strategy, but the object indirect object, such with "transfer" ; indirect control of the so-called CASCADE.
Second, the ventilation:
        Improve ventilation, tend to be more direct and effective way.But increased to a certain extent, that showed significant slowing down, DO longer increase this to a certain value of the original hardware design of ventilation vvm, consider dispersing ability, bubble residence time, approaches, and body surface area, and other factors alone increaseventilation will have its limits, and easy to fueling the bubble generated become another major troubled projects. Therefore, by setting the upper and lower limits to find the appropriate amount of ventilation, if not yet reached the the DO target value, but can be controlled by "CASCADE" by the next control factor pursuit, so that timely and appropriate.
Third, the tank pressure:
        Increase tank pressure, so that the bubble residence time increased. Tank pressure but often little can change the range (0.1 ~ 0.5kg/cm2), overvoltage adversely the growth of most microorganisms, only> 0.5kg/cm2 above the tank pressure to obvious substantial increase in DO, therefore strategies existing becoming no longer use.
Fourth, oxygen:
        Suitable ventilation mode to "CASCADE" control last accompanied by O2 set, so can be reached on other control factors limit re-launch the Add O2 to achieve effective and energy-saving concept.O2 should be noted that the add sources of pressure setting O2 line shall be a general> Air line 0.2kg/cm2 and shall incorporate a check valve. Pure oxygen can not be directly into the fermentation tank, the gas mixer and the air to be added into a certain proportion of mixed and then enter the tank. Above the slender-slot design with the the aeration ring and decentralized fins (suitable diameter and number of segments) can indeed achieve dissolved oxygen evenly distributed.
 

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