Loop fermentors

Keywords. Cellulose, Hemicellulose, LignoceUulose,Yeast, Pretreatment, Simultaneous saccharification and fermentation (SSF), Ethanol, Xylose, Tower fermentor. Air-lift loop fermentor... 

In order to study in situ ethanol production and recovery, Tsao et al. [18] conducted ethanol fermentation in an air-lift loop fermentor with a side arm (ALSA) using CO2 to strip ethanol from the fermentor. Analogous to the traditional air-lift fermentor, the ALSA consists of an inner tube that enhances the mixing and mass transfer characteristics (see Fig. 3 for fermentor configuration... 

Fig. 3. Schematic configuration of an air-lift loop fermentor with a side arm (ALSA) integrated with CO2 stripping of ethanol [18]...

Fig. 11. Air-lift loop fermentor with product recovery system [69]...

As this trend levels off with larger columns, it is recommended that values estimated for a 60 cm column are used. If heat transfer is a problem, then heat transfer coils within the column, or even an external heat exchanger, may become necessary when operating a large, industrial bubble column-type fermentor. Scale-up of an internal loop airlift-type fermentor can be achieved in the same way as for bubble column-type fermentors for external loop airhfts see Section 7.7. 

Russell, . W. F., I. J. Dunn, and H. W. Blanch, "The Tubular Loop Batch Fermentor Basic Concepts," Biotech. Bioeng. 16 (1974) 1261-1272. 

The fermentors are cooled by pump-around loops and external heat exchangers. The total duty required is 9.5 x 106kcal/h. 

Shu (S6) has taken advantage of the dependence of fermentor performance on agitator speed, by setting up a feedback control loop in which the agitator speed is varied automatically so as to cause the broth oxygen uptake to vary with time in a predetermined manner. 

Figure 5.5 Open-loop simulations concentration profiles of substrate and product in the fermentor side for different dilution rates.

Figure 5.6 Open-loop simulation (case 1) concentration profiles of key component, biomass, substrate, product in fermentor, and membrane sides at D, of 0.2 h .

With regard to the fermenters, the most common configurations are membrane recycle fermentor (MRF) and hollow fibre fermentor (HFF). In the MRF the membrane module forms a semi-closed loop with a conventional fermentation vessel the MRF gives much better performance than the HFF, where the microbial cells are loaded onto the shell-side and the feed is pumped through the lumen side. Further advantages of this system are a cell/particulate-free product stream and the reduction of capital costs. Furthermore, in these systems cell growth is a caitical point. 

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