Basic Functions Of A Fermenter For Microbial Or Animal Cell Culture

The main function of a fermenter is to provide a controlled environment for the growth of microorganisms or animal cells, to obtain a desired product. In designing and constructing a fermenter a number of points must be considered:

1. The vessel should be capable of being operated aseptically for a number of days and should be reliable in long-term operation and meet the requirements of containment regulations.

2. Adequate aeration and agitation should be provided to meet the metabolic requirements of the micro-organism. However, the mixing should not cause damage to the organism.

3. Power consumption should be as low as possible.

4. A system of temperature control should be provided.

5. A system of pH control should be provided.

6. Sampling facilities should be provided.

7. Evaporation losses from the fermenter should not be excessive.

8. The vessel should be designed to require the minimal use of labour in operation, harvesting, cleaning and maintenance.

9. Ideally the vessel should be suitable for a range of processes, but this may be restricted because of containment regulations.

10. The vessel should be constructed to ensure smooth internal surfaces, using welds instead of flange joints whenever possible.

11. The vessel should be of similar geometry to both smaller and larger vessels in the pilot plant or plant to facilitate scale-up.

12. The cheapest materials which enable satisfactory results to be achieved should be used.

13. There should be adequate service provisions for individual plants (see Table 7.1).

The first two points are probably the most critical. It is obvious from the above points that the design of a fermenter will involve co-operation between experts in microbiology, biochemistry, chemical engineering, mechanical engineering and costing. Although many dif-

Table 7.1. Service provisions for a fermentation plant

Compressed air

Sterile compressed air (at 1.5 to 3.0 atmospheres) Chilled water (12 to 15°) Cold water (4°) Hot water

Steam (high pressure) Steam condensate Electricity Stand-by generator Drainage of effluents Motors

Storage facilities for media components Control and monitoring equipment for fermenters Maintenance facilities Extraction and recovery equipment Accessibility for delivery of materials Appropriate containment facilities

Aseptic inoculation pipe

Aseptic inoculation pipe

Fermenter Diagram
Fig. 7.1. Diagram of a fermenter with one multi-bladed impeller.

ferent types of fermenter have been described in the literature, very few have proved to be satisfactory for industrial aerobic fermentations. The most commonly used ones are based on a stirred upright cylinder with sparger aeration. This type of vessel can be produced in a range of sizes from one dm3 to thousands of dm3. Figures 7.1 and 7.2 are diagrams of typical mechanically agitated and aerated fermenters with one and three multi-bladed impellers respectively. Tables 7.2 and 7.3 give geometrical ratios of various of the dimensions which have been quoted in the literature for a variety of sizes of vessel.

Inner Structure Fermenter

Sterile air line

Air sparger

Sterile air line

Air sparger

Fig. 7.2. Diagram ot a fermenter with three multi-bladed impellers.

At this stage the discussion will be concerned with stirred, aerated vessels for microbial cell culture. More varied shapes are commonly used for alcohol, biomass production, animal cell culture and effluent treatment and will be dealt with later in this chapter.

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  • T
    How aeration is provided in the fermenter?
    5 years ago
  • karolin
    How to design sparger?
    5 years ago

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