JPH06133757A - Device for photosynthetic reaction of fine alga - Google Patents

Abstract

PURPOSE:To reduce a site area and convert a photosynthetic reaction tank into a small size by forcibly circulating a nutrient solution in the photosynthetic reaction tank tall in the vertical direction at a high speed and blowing CO2 gas into the reaction tank from its bottom. CONSTITUTION:A nutrient solution is forcibly circulated in a photosynthetic reaction tank 1 tall in the vertical direction at a high speed, and light is uniformly irradiated on algae. A nutrient solution is well supplied to the algae to improve the rate of the photosynthetic reaction. A separation plate 2 is disposed to facilitate the circulation of the nutrient solution and a CO2-containing gas is blown into the culture solution from the lower part of the reaction tank to facilitate the dissolution of CO2 gas.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photosynthetic reaction device for microalgae.

[0002]

2. Description of the Related Art A conventional method and apparatus for producing microalgae will be described with reference to FIG. Conventionally photosynthetic reaction tank 1
The culture solution 3 and a small amount of seed microalgae 4 are introduced by a supply liquid pump 14 into the inside, and the photosynthetic reaction is progressed by receiving sunlight from the surface of the photosynthesis reaction tank 1 to grow the microalgae 4. . Carbon dioxide (CO ₂ ) required for photosynthesis is dissolved in the culture solution 3 in the reaction tank 1 from the blower 18 through the air diffuser 19, and the mixing and stirring of the culture solution is performed by the stirrer 13, usually with a blade. The water wheel (paddle feel) of is used. If the microalgae 4 grows, the collection pump 1
In step 6, the produced algal cells are collected. Since the produced algal cells are collected together with the culture solution, a so-called semi-continuous operation method in which only the culture solution 3 is replenished by the supply solution pump 14 in the amount, or a continuous operation method in which continuous supply and extraction are performed is adopted. .
As shown in FIG. 4, the prior art photosynthetic reaction tank 1 has a structure with a shallow water depth (usually 20 to 50 cm) and a large surface area, and the stirring and mixing method of the culture solution 3 is performed by the above paddle feel. However, the stirring speed is slow and is about 10 to 20 cm per second. In addition, in FIG. 4, 21 shows a photosynthesis reaction part.

[0003]

As described above, the prior art is a photosynthesis reaction tank having a shallow water depth and a large surface area exposed to light. The growth (production) of microalgae is as shown in the following reaction formula:
The basic reaction is to obtain solar energy (visible light with a wavelength of 400 to 700 nm) from carbon dioxide (CO ₂ ) and water (H ₂ O) to synthesize sugar (C ₆ H ₁₂ O ₆ ), from which alga is produced. It is synthesized. 6CO ₂ + 6H ₂ O → C ₆ H ₁₂ O ₆ + 6O ₂ ↑
(In the presence of light)

When the alga body divides and proliferates, it impedes the transmission of light into water and the photosynthetic reaction does not proceed. Therefore, the photosynthetic reaction tank can not deepen the water depth,
There is no choice but to use a shallow water depth that allows light to pass through, and a large-area photosynthetic reaction tank is required when producing a large amount of microalgae, which requires a huge site area.

In view of the above-mentioned state of the art, the present invention aims to provide a photosynthetic reaction tank for microalgae which has a structure with a large depth of water and whose site area can be reduced.

[0006]

The present invention provides (1) a vertically tall photosynthetic reaction tank having means for supplying a culture solution and seed microalgae and means for recovering grown microalgae, and the reaction. A stationary or movable separator that divides the tank into upper and lower parts with one end opened, means for transferring the lower culture solution directly or through a weir, and CO _{2 in the} lower culture solution A photosynthetic reaction device for microalgae, comprising a means for supplying a contained gas. (2) The photosynthetic reaction device for microalgae according to (1) above, wherein the separator is an inclined separator whose angle can be changed arbitrarily. Is.

In the apparatus of the present invention, the surface area exposed to light is constant, and the reaction section for performing photosynthesis is the same as or has a shallower water depth than the conventional one, but the entire reaction vessel has a tall shape in the vertical direction exposed to light. The photosynthetic reaction is carried out on the surface portion of this reaction tank, but the culture solution in the lower tank portion is sent to this surface portion to forcibly circulate the liquid in the upper layer portion and the lower layer portion. In order to facilitate the circulation of the culture solution, a plate which also serves as the bottom of the photosynthetic reaction section is arranged at the upper part. As a result, the flow rate of the culture solution flowing through the photosynthesis reaction section is increased, and the culture solution in the lower layer is frequently replaced. The circulation flow velocity is faster than that in the case of the conventional technique and rapid stirring is performed, and for example, it is preferable to set the speed to 1 m / sec or more. Furthermore, it is preferable that the upper bottom plate is provided with a protrusion so that the structure disturbs the flow as much as possible.

[0008]

[Function] When the surface area of the photosynthetic reaction tank is constant, the amount of solar energy applied to the photosynthetic reaction tank is constant. Light is efficiently supplied without waste.

Further, since CO ₂ is blown from the bottom of the deep photosynthesis reaction tank, the rising distance of the blown CO ₂ gas bubbles is long (the rising time is also long), so that the dissolution efficiency of CO ₂ gas is high. The utilization efficiency of CO ₂ is improved. In addition, by disturbing the culture solution involved in the photosynthetic reaction of the upper layer at a high flow rate, the contact between the microalgae and the culture solution is performed with high efficiency.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIG. The photosynthetic reaction tank 1 is filled with the culture solution 3 and the microalga 4 is present. The upper and lower parts of the photosynthesis reaction tank 1 are separated by the separator plate 2, and the culture solution 3 is circulated by the submersible pump 10 driven by the motor 11. CO ₂ is blown into the photosynthesis reaction tank 1 by the blower 18 through the air diffuser 19. The photosynthesis reaction section 21 has a shallow water depth, and the liquid flow velocity in this section is high. The drive device 30 is for moving the position of the separator 2 up and down.

(Embodiment 2) Another embodiment of the present invention will be described with reference to FIG. The weir 25 is installed together with the separating plate 2, and the culture solution 3 is sent to the weir 25 by the pump 12 so that the overflowing culture solution 3 flows through the photosynthesis reaction section 21 and returns to the photosynthesis reaction tank 1 again. The separator 2 is preferably installed horizontally or slightly inclined so that the culture solution can easily flow. The culture solution supply line 15 has a pump 16 for collecting the produced algal cells.
It is for supplying the same amount when pulled out.

(Embodiment 3) Still another embodiment of the present invention will be described with reference to FIG. FIG. 3 shows an apparatus of Example 2 (FIG. 2)
2 and the same parts as those in FIG. 2 are denoted by the same reference numerals. In the apparatus of this embodiment, the separator 2 is largely tilted so that the culture solution 3 circulated by the pump 12 is rapidly dropped through the weir 25. The separator 2 extends along the illustrated fixed wall 55. The wall elevating device 51 allows the movable wall 56 to move up and down, and the angle adjusting device 50 changes the separator 2. With this configuration, the photosynthesis reaction section 21
Not only can the liquid of the culture be greatly disturbed and the thickness of the culture liquid can be reduced, but also the light irradiation area of the photosynthesis reaction section (per installation area of the reaction tank 1) depending on the position of sunlight.
Can be increased. In addition, in FIG. 3, 17 is a discharge line, from which microalgae and culture liquid that have grown are collected.

[0013]

The device of the present invention has the following effects. (1) The photosynthetic reaction rate is increased by the forced circulation of the culture solution at a high flow rate, and as a result, the photosynthetic reaction tank can be downsized. (2) Since it is a deep reactor, the installation area is small,
Also, since CO ₂ is blown from the bottom of the culture solution at a deep water depth, C
O ₂ dissolution efficiency is high.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of a photosynthetic reaction tank for microalgae of the present invention.

FIG. 2 is an explanatory view of another embodiment of the photosynthetic reaction tank for microalgae of the present invention.

FIG. 3 is an explanatory view of still another embodiment of the photosynthetic reaction tank for microalgae of the present invention.

FIG. 4 is an explanatory diagram of one mode of a conventional photosynthesis reaction tank for microalgae.

Claims (2)

[Claims] 1. A culture solution and a seed microalgae are supplied.
Vertical method with means and means for collecting grown microalgae
A photosynthetic reaction tank that is taller than the other
Stationary or movable separator that opens at the end and divides, lower part
Transfer the culture solution to the upper part of the separator directly or through a weir.
CO in the culture solution in the lower part ₂Supply containing gas
Light of microalgae characterized by comprising means for
Synthetic reactor. 2. The photosynthetic reaction device for microalgae according to claim 1, wherein the separator is an inclined separator whose angle can be arbitrarily changed.