JPH05137563A - Algae culture device - Google Patents

Abstract

(57) [Summary] [Structure] A vertically-arranged cylindrical culture tank 1 is provided with a reflux pipe 12, a gas-liquid separation chamber 18 is provided at the top of the reflux pipe, and the culture tank top and the gas-liquid separation chamber are piped. To communicate with. Further, a pipe 15 connects the side wall of the bottom of the culture tank and the bottom of the reflux pipe. A liquid feed pump 16 was attached in the middle of the pipe so that the culture liquid from which air bubbles were separated in the gas-liquid separation chamber was horizontally pressed into the culture tank from the side wall at the bottom of the culture tank by the liquid feed pump. [Effect] Since the culture solution is uniformly stirred, and the amount of aeration can be minimized to reduce foaming, high-concentration culture can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for culturing microalgae such as chlorella and spirulina.

[0002]

2. Description of the Related Art Microalgae such as chlorella and spirulina are rich in proteins, fats and oils, vitamins and other physiologically active substances, and are therefore useful as raw materials for health foods, feeds, feeds and the like. In recent years, large-scale culture of chlorella or the like that absorbs carbon dioxide by carbon assimilation has also attracted attention as a means for fixing carbon dioxide, which causes global warming. Therefore, there have been many proposals for a culture apparatus for microalgae such as Chlorella, and the main ones are as follows. Open pond culture method Open circulation culture method Open channel culture method Glass flat bottle culture method Vertical cylindrical culture method

Among these, the open type which allows large-scale culture has a drawback that other algae are apt to be mixed and various bacteria are easily contaminated, and the quality and yield of the harvested algae are not stable. In addition, in the culturing method using sunlight, in order to widen the light-receiving surface, the culture device must be expanded in the horizontal direction, but since the light-receiving surface cannot be made larger than the installation area of the culture device, large-scale culture is possible. To do that requires a vast site. Aseptic culture is possible with the culture method using a glass flat bottle, but mass culture is not possible.

The vertical cylindrical culture method uses a cylindrical culture tank made of a light-transmissive material such as glass or acrylic resin, and blows air containing carbon dioxide gas from the bottom of the culture tank to generate carbon dioxide necessary for carbon assimilation. The cells are supplemented with gas, while the alga is cultivated while being illuminated by a light source (including sunlight) placed inside or outside the tank. This method has the features that it can be mass-cultured and that it is unlikely to be contaminated with heterologous algae and other bacteria. In this culturing method, the air blown from the bottom of the culturing tank also acts as bubbles to stir the culturing solution in the process of rising in the culturing solution to make uniform the illuminance and other culturing conditions. The bubbles also serve as a light guide in the culture solution having a high concentration of algal cells, and help the light to reach algal cells far from the light source. However, the algal cell concentration is about 2 g /
When the culture is performed at a high concentration of 1 or more, the reach of light in the culture solution becomes extremely short, and the illuminance becomes insufficient even 2 to 3 cm ahead of the light source.

Further, in high-concentration culture, the viscosity of the culture solution increases due to the polysaccharides discharged from the algal cells to the outside of the cells, and agglomerates of algal cells tend to be generated in the portion where the culture solution tends to settle. And
When this develops, it causes problems such as uneven stirring and blockage of the pipe at an accelerating rate, which lowers productivity. If the amount of aeration is increased in order to solve these problems, algae adhere to and accumulate on the tank wall of the gas phase portion of the upper part of the culture tank, and if left unattended, the yield will be reduced, so frequent cleaning is required. In addition, increased air flow causes significant water evaporation and foaming. Foaming is particularly severe in culture, although polysaccharides such as spirulina and porphyridium are markedly discharged, and algal cells are discharged from the culture tank together with bubbles, which causes a decrease in yield and contamination.

[0006]

Therefore, the present invention can give a uniform light-receiving opportunity to the algal bodies in the culture solution even with the minimum aeration amount, and there is a fear of occurrence of troubles due to foaming or agglomeration of algal bodies. It is an object of the present invention to provide an algae culturing apparatus for a vertical cylindrical culturing method which is stable and capable of stable culturing and has good productivity.

[0007]

According to the present invention, a cylindrical culture tank made of a transparent material is vertically arranged, and a means for aerating the culture tank from the bottom to the culture tank is attached to the culture tank, and the diameter is smaller than that of the culture tank. The reflux tube consisting of the cylindrical body of is arranged vertically in the culture tank,
A gas-liquid separation chamber was provided at the top of the reflux tube, and the culture tank top and the gas-liquid separation chamber were connected by a pipe, the bottom wall of the culture tank and the reflux tube bottom were connected by a pipe, and a liquid feed pump was attached in the middle of the pipe. It is characterized by

[0008]

The culture device of the present invention is used in a state where the whole culture tank is filled with the culture solution under aeration and agitation and no gas phase remains in the upper part of the culture tank. In this state, light is emitted from a light source installed in the surroundings or in the tank, air is blown from the bottom of the tank, and the liquid-feeding pump between the bottom of the culture tank and the reflux tube is operated to perform the culture. Gas-liquid separation chamber →
Circulate through the route of reflux tube → culture tank. Since the circulating culture solution is horizontally pushed into the tank from the side wall at the bottom of the culture tank by the liquid feed pump, the culture solution at the bottom of the culture tank is violently disturbed without causing a stagnant portion, and thus the algal cells precipitate and form clumps. It does not form. The culture solution is sufficiently agitated by the cooperative action of the forced circulation / agitation by the liquid delivery pump and the agitation action by aeration, and the alga body is given an opportunity to receive light evenly and rapidly grows.

The air that has been blown from the bottom of the culture tank and has risen in the culture solution as bubbles enter the gas-liquid separation chamber together with the culture solution from the top of the culture tank. The gas-liquid separation chamber has an upper part communicating with the atmosphere through an exhaust pipe and a lower part communicating with a reflux pipe, and is connected to the culture tank at approximately the middle of the exhaust pipe connecting portion and the reflux pipe connecting portion.
The bubble-containing culture solution entered here flows toward the reflux tube,
During that time, the bubbles float and are destroyed, so that they are separated from the bubbles. The air that has been broken and collected in the gas phase portion of the gas-liquid separation chamber is discharged into the atmosphere through the exhaust pipe. The gas-liquid separation chamber shall have sufficient space for air bubble separation, but when the foaming of the culture solution is not so remarkable, a “chamber” made of a special material is not provided as the gas-liquid separation chamber and the top of the reflux pipe is used for it. It can also be used.

The culture solution circulates between the culture tank and the gas-liquid separation chamber as described above, but does not come into contact with the dirty ambient air. This enables stable algae growth in a clean environment. In this device, the light source is arranged outside the culture tank or installed inside the culture tank. A light source may be installed both inside and outside the culture tank. As a light source installed in the culture tank, a single-ended type fluorescent lamp is suitable, and only the light emitting portion of this fluorescent lamp is immersed in the culture solution. This illumination system has a feature that the light emitted from the fluorescent lamp illuminates 100% of the culture solution and is utilized for carbon assimilation of algae at a high utilization rate. In the daytime, it is possible to reduce the electricity cost for lighting by injecting sunlight from the culture vessel tank wall and turning off or dimming the fluorescent lamp.

[0011]

EXAMPLE In the example shown in FIG. 1, a culture tank 1 has a bottom plate 2 of a closed structure in which both ends of an upright acrylic resin cylinder are closed, and a diffuser plate 3 for aeration and a temperature control member. The water passage 4 is fixed. The diffuser plate 3 is made of porous ceramics and is connected to the air supply device 6 by a pipe 5. The air supply device 6 includes a compressor 7 for air pressure feeding, a carbon dioxide gas cylinder 8 for supplying carbon dioxide gas, a flow rate control device 9 for adjusting the amount of ventilation, an air filter 10 for cleaning ventilation, etc. It is possible to supply the air having a raised level to the diffuser plate 3 at a constant flow rate.

The water pipe 4 is a water supply device 11 whose temperature can be adjusted.
Is supplied to the water supply device 11 to supply cold water or hot water having a constant temperature to cool or warm the culture solution and maintain the culture solution temperature at a suitable value. Immediately next to the culture tank 1, there is a reflux pipe 12 which stands upright in parallel with the culture tank 1. The reflux pipe 12 is located at a position higher than the top top plate 13 of the culture tank 1 and between the top plate 13 and the top plate 13. Are connected by a pipe 14. A pipe 15 is provided between the reflux tube 12 and the bottom of the culture tank 1.
a and 15b are connected, and a liquid feed pump 1 is provided between them.
6 is installed. In the pipe 14, a thick pipe 17 having substantially the same diameter as that of the reflux pipe 12 is used in the connection portion with the reflux pipe 12, and the pipe 17 and the reflux pipe 12 at the pipe 17 mounting portion constitute a gas-liquid separation chamber 18. is doing. Reflux tube 12
The pipe constituting the above is an exhaust pipe 19 in a portion above the gas-liquid separation chamber 18, and the vicinity of the tip is bent in the horizontal direction to prevent suspended dust from entering.

A pipe 20 for supplying a fresh culture liquid is connected to the reflux pipe 12, and the pipe 20 is connected to a culture liquid storage tank 22 via a pump 21.
Culture medium discharge port 23 for taking out the culture medium after the culture is completed
Are connected to the bottom plate 3 of the culture tank. The culture tank 1 further includes a single-ended type fluorescent lamp 25 for illuminating the inside of the culture tank, and a base portion 26.
It is fixed to the top plate 13 in an upright state with the above. The base portion 26 is connected to a power source via a ballast 27. Next, a cyanobacterium / spirulina culture experiment conducted using this culture device will be described. The culture conditions are as follows.

Cultivation tank: Acrylic resin cylindrical culture tank having an inner diameter of 11 cm and a volume of 7,500 ml Reflux tube: inner diameter of 3 cm, length of 1.2 m, volume of 700 ml Refluxing amount: about 200 ml / min Culture solution temperature: 35 ° C. Illumination: 96 W Two single-ended gold fluorescent lamps (illuminance in the center of the culture tank: approx. 40 klux) Initial algal cell concentration: 0.8 g / l Aeration rate: 500 ml / min Carbon dioxide concentration of blown air: 0.2%

The media used: SOT medium; composition below _{NaHCO 3 1680mg K 2 HPO 4 50mg} NaNO 3 250mg K 2 SO 4 100mg NaCl 100mg MgSO 4 · 7H 2 O 20mg CaCl 2 · 2H 2 O 4mg FeSO 4 · 7H 2 O 1mg Na ₂ EDTA ・ 2H ₂ O 8mg A ₅ Metal mixture 0.1 ml Distilled water 99.9 ml A ₅ Metal mixture H ₃ BO ₃ 286 mg MnSO ₄・ 7H ₂ O 250 mg ZnSO ₄・ H ₂ O 22.2 mg CuSO ₄・ 5H ₂ O 7.9 mg Na ₂ MoO ₄ 2.1mg Distilled water 100ml

Culture was continued for 4 days while collecting and analyzing 10 ml of the culture solution once a day. As a comparative example, a culture experiment was performed in the same manner as in FIG. 1 except that a reflux tube was not attached and the same culture conditions were used except for the reflux conditions. In the comparative example, it was observed that the agglomerates of algal cells were precipitated at the bottom of the culture tank, but in the examples, this was not the case, and the culture solution was uniformly stirred and kept in a fluidized state until the end. In addition, in the examples, gas-liquid separation was smoothly performed in the gas-liquid separation chamber even at the end of culture when the algal cell concentration reached 7 g / l. The experimental results are shown in Table 1. The algal cell concentration and the production amount are both dry matter equivalent values.

[0017]

[Table 1]

[0018]

As described above, the inside of the culture tank is filled with the culture solution and agitated by aeration so that bubble destruction is caused in a gas-liquid separation chamber separate from the culture tank, and bubbles are further generated in the gas-liquid separation chamber. According to the apparatus of the present invention in which the separated culture solution is horizontally press-fitted from the side wall of the culture tank bottom to stir the culture solution at the bottom of the culture tank, a large excess of air exceeding the amount required for carbon dioxide gas replenishment is provided. Even if you do not expect a stirring effect by blowing in, algae do not stick to the wall of the culture tank or settle at the bottom of the culture tank, so high-concentration culture that was not possible with conventional equipment of this kind It is possible, and the substantial capacity of the culture tank is increased, and extremely efficient culture can be performed. In addition, since the amount of aeration may be small, even when culturing algae that easily foams, there is no difficulty in foam breaking, and culture management is easy.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

1: Culture tank 2: Bottom plate 3: Diffuser plate 4: Water pipe 6: Air supply device 12: Reflux pipe 16: Liquid feed pump 18: Gas-liquid separation chamber 19: Exhaust pipe 25: Fluorescent lamp

Claims (1)

[Claims] 1. A cylindrical culture tank made of a transparent material is vertically arranged, and a means for ventilating the culture tank from the bottom to the culture tank is attached to the culture tank, and a reflux tube made of a tubular body having a diameter smaller than that of the culture tank is provided. Arranged vertically in the culture tank, a gas-liquid separation chamber is provided at the top of the reflux tube, the culture tank top and the gas-liquid separation chamber are connected by a pipe, and the culture tank bottom side wall and the reflux tube bottom are connected by a pipe and the pipe An algae culturing device, which is equipped with a liquid feed pump in the middle.