JPS642356B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fermenter using flocculating yeast or microbial cells attached to a single substance such as zeodolite or vermiculite.

In this specification, regarding context,
In Figures 2 and 3, the outflow direction of the fermentation liquid, that is, the right side in each figure is referred to as the front for convenience, and the left side is referred to as the rear.

In recent years, ethanol produced from biomass by fermentation has attracted attention as an energy alternative to oil. This reaction produces ethanol and carbon dioxide gas from glucose and other sugars, as shown in the following reaction formula.

C ₆ H ₁₂ O ₆ →2C ₂ H ₅ OH + 2CO _2As is clear from the above equation, increasing the productivity of ethanol inevitably increases the rate of production of carbon dioxide gas, which causes the flocs and carriers of flocculating yeast to increase. The attached bacterial cells rose inside the tank as the generated carbon dioxide bubbles rose, and there was a tendency for them to flow out of the tank. In order to solve such problems, in conventional fermentation tanks, as shown in FIG. As shown in FIG. 2, a method was taken in which the bottomed cylindrical tank body 21 was tilted upward in the forward direction. In addition, in FIGS. 1 and 2, 14 and 24 are raw material supply pipes;
5 and 25 are fermentation liquid outflow pipes, 16 and 26 are gas vent pipes, and 17 and 27 are carbon dioxide gas bubbles.

When flocculating yeast is used as the microorganism in these conventional fermenters, the manner in which the yeast flocculate and the size of the yeast flocs generally depend on the fermentation conditions and the degree of disturbance of the reaction solution due to the generation of carbon dioxide gas. The small yeast flocs rise in the tank along with the generated carbon dioxide gas, and in the fermentation tank shown in FIG. However, in the case of the fermentation tank shown in Fig. 2, the superficial velocity of the gas is small, but in the case of the fermentation tank shown in Fig. 1, Since there is no part corresponding to the sedimentation separation section,
As expected, it was not possible to prevent the yeast floc from flowing out along with the fermentation liquid. In addition, in the case of fermentation using carrier-attached microbial cells, when trying to increase ethanol productivity, the amount of carrier-attached microbial cells flowing out of the tank also increased, although not as much as in the case of the flocculating yeast mentioned above. .

This invention was made in view of the above-mentioned circumstances, and utilizes these advantages by combining conventional fermenters to prevent microorganisms from flowing out of the tank as much as possible and maintain a high concentration of microorganisms in the tank. The object of the present invention is to provide a fermentation tank that can improve ethanol productivity.

The fermentation tank according to the present invention is of a fluidized tank type for continuous fermentation, and as shown in FIG. It is equipped with a buffer 33 for sedimentation and separation of microorganisms.

The bottomed cylindrical tank body 31 may be cylindrical, or
A rectangular tubular shape may also be used. Also, the slope gradient is usually
Although it is approximately 15 degrees with respect to the vertical, this angle is set as appropriate.

A raw material supply pipe 34 is arranged at the bottom of the fermentation tank, and a fermentation liquid outflow pipe 35 is arranged at the front wall of the top 32.
A gas vent pipe 36 is arranged on the top wall. The vertical part 33 is composed of a vertical part 33a and a slope part 33b provided at the lower end of the vertical part 33b with a forward downward slope. There is a small distance between the upper end of the

Carbon dioxide gas bubbles 37 generated by fermentation rise in the tank, but their superficial velocity is kept small.
Therefore, yeast flocs and bacterial cells attached to the carrier become air bubbles 37.
The amount that rises as a result of this is small, and even what rises is mostly settled and separated by the baffle 33 and does not flow out of the tank. In this way, the concentration of microorganisms in the tank is maintained high.

Next, in order to demonstrate the effects of the fermenter of the present invention, examples using the fermenter of the present invention and comparative examples using a conventional fermenter will be described.

Comparative Example 1 Using the fluidized bed type fermentation tank shown in Figure 1, first, 5 wt/vol% of granular vermiculite with an average particle size of 0.4 mm was introduced into the tank as a carrier, and then microbial cells attached to the carrier were added. A preculture solution of Zymomonas mobilis ATCC-10988 was added at a concentration of 10 vol %, and batch culture was performed. After culturing for about 80 hours, use the following medium A.
and B were supplied into the tank at a ratio of A:B=1:9, and continuous fermentation was performed under the following fermentation conditions.

Medium A: Yeast extract 10g/(NH ₄ )SO ₄ 10g/ KH ₂ PO ₄ 10g/ MgCl ₂・6H ₂ O 5g/ MnCl ₂・4H ₂ O 40mg/ ZnSO ₄・7H ₂ O 40mg/ Antifoaming agent 3g/ Medium B: Glucose 167g/ _{FeSO4.7H2O 33mg} /Fermentation conditions: Fermentation temperature 30°C PH 4.5 Ethanol productivity was examined by gradually increasing the supply amount of the medium, that is, gradually increasing the dilution rate. The results are shown in Figure 4. As is clear from the figure, ethanol productivity increased almost linearly up to a dilution rate of 0.3 h ^-1 , but at a dilution rate of 0.4 h ^-1 , the ethanol concentration decreased to about 50 g/ did not increase above about 20 g/h. This was due to the bacterial cells attached to the carrier flowing out of the tank.

Comparative Example 2 Using the fluidized tank type fermenter shown in Figure 1, first,
Batch culture was performed by adding a preculture solution of Saccharomyces uvarum lFO-2018 as a flocculating yeast to the tank at a concentration of 10 vol%. After culturing for about 80 hours, the following media C and D were supplied into the tank at a ratio of C:D=1:1.5,
Continuous fermentation was carried out under the following fermentation conditions.

Medium C: A mixture of 700 g of honey from the Philippines / 7 g of (NH ₄ ) ₂ SO ₄ / 0.5 g of K ₂ S ₂ O ₅ / 2.5 g of antifoaming agent and adjusted to PH4.5 with H ₂ SO ₄ . D: Tap water The relationship between dilution rate and ethanol productivity in this continuous fermentation is shown in Figure 5. As is clear from the figure, the ethanol productivity did not increase above about 7 g/h due to the outflow of flocculating yeast.

Comparative Example 3 The fermentation tank shown in Figure 2 was used as a fermentation tank (tank inner diameter = 80
The same operation as in Comparative Example 1 was repeated, except that the height was 4500 mm, the slope was 15° to the vertical, and the actual volume was approximately 20 mm.

Since the superficial velocity of the generated carbon dioxide gas was significantly reduced, the outflow of the bacterial cells attached to the carriers from the tank was prevented to some extent, but some outflow could not be avoided. Therefore, ethanol productivity did not increase above about 13 g/h.

Comparative Example 4 The same operations as in Comparative Example 2 were repeated, except that the fermenter used in Comparative Example 3 was used as the fermenter.

The sedimentation velocity of flocculating yeast is as low as 0.3 to 0.4 m/sec, so the flow of yeast flocs out of the tank is significant.
Ethanol productivity remained at about 5 g/h.

Example 1 The fermentation vessel used in Comparative Example 1 was tilted at an angle of 15° with respect to the vertical, and the operation of Comparative Example 1 was repeated.

In the case of Comparative Example 1, as mentioned above, dilution rate =
At 0.4 h ^-1 , the ethanol concentration decreased and the ethanol productivity remained at about 20 g/h, but when the fermenter was tilted as described above, the dilution rate =
Even at 0.6 h ^-1 , the ethanol concentration did not decrease, and the ethanol productivity reached about 40 g/h.

Example 2 Except for using the fermenter used in Example 1,
The operation of Comparative Example 2 was repeated.

In this case, the ethanol concentration does not decrease even at a dilution rate of 0.2 h ^-1 , and the alcohol productivity is approximately 14 g/
・It also reached h.

As described above, according to the fermenter of this invention,
Since the tank body is tilted to the required slope, the superficial velocity of carbon dioxide gas generated during fermentation can be reduced, and as a result, yeast flocs and bacterial cells attached to the carrier move inside the tank with carbon dioxide bubbles. This can be suppressed as much as possible, and a baffle is provided at the top of the tank, which allows yeast floes and microbial cells attached to the carrier to settle down, maintaining a high microbial concentration in the tank. Therefore, the productivity of ethanol can be improved.

[Brief explanation of the drawing]

Figures 1 and 2 are vertical sectional views showing a conventional fermenter, Figure 3 is a vertical sectional view showing a fermenter according to the present invention, and Figures 4 and 5 are dilution ratios, ethanol concentrations, and productivity. It is a graph showing the relationship between 31...tank body, 32...top, 33...buttful.

Claims (1)

[Claims] 1 Place the bottomed cylindrical tank body at the required slope,
A fermentation tank equipped with a butthole for sedimentation and separation of microorganisms at the top of the tank.