Culture system

Abstract

To provide a culture system that enables microalgae and a culture solution to be sufficiently agitated.SOLUTION: A culture system (10) includes a culture device (12) that includes a culture tank (20) for culturing microalgae, and a collection device (14) that collects a culture solution (L). The culture tank includes a bottom portion (30) located at the lowest position of the culture tank in the depth direction (X) of the culture tank. The collection device includes a collection tube (50) housed in the culture tank. The collection tube is a tubular body having an internal space. The collection tube includes a bottom side collection portion (62) that extends along the bottom portion of the culture tank. The bottom side collection portion includes an open port (72) formed at a site facing upward in the depth direction of the culture tank.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a culture system capable of culturing microalgae and recovering the cultured microalgae.

Background Art

[0002] Conventionally, efforts aimed at mitigating or reducing the impact of climate change have been continued, and research and development regarding reduction of carbon dioxide emissions have been conducted towards this realization. From this perspective, microalgae have been attracting attention. This is because microalgae consume carbon dioxide through photosynthesis. Therefore, a culture system for culturing microalgae is expected as a system that contributes to mitigating or reducing the impact of climate change.

[0003] As an example of a culture device, the culture device disclosed in Patent Document 1 can be mentioned. This culture device includes a storage part (culture tank) made of a flexible material, a plurality of gas supply parts, and a plurality of guide parts. The flexible material is, for example, a plastic bag described in Patent Document 2.

[0004] In the culture device described in Patent Document 1, the plurality of gas supply parts are provided at the bottom of the storage part. The guide parts are arranged directly above the gas supply parts inside the storage part. The gas supplied from the gas supply parts is guided by the guide parts and rises in the culture solution. Along with this, convection occurs in the culture solution.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Although not particularly shown in the drawings of Patent Document 1, the culture device is provided with a recovery pipe for recovering the cultured microalgae and the culture solution. When gas is supplied from the gas supply unit to the culture solution with the recovery pipe immersed in the culture solution, there is a concern that the convection may be hindered by the recovery pipe.

[0007] An object of the present invention is to solve the above-described problems.

Means for Solving the Problems

[0008] According to an embodiment of the present invention, there is provided a culture system including a culture device including a culture tank for culturing microalgae and a recovery device for recovering the microalgae from the culture tank. The culture tank stores a culture solution and has a bottom portion located at the lowest position in the depth direction of the culture tank and an opening portion located at a higher position than the bottom portion. The culture device includes a gas supply source and a gas supply unit inserted into the culture tank from the opening portion. The gas supply unit has a gas discharge port that opens in the culture solution below in the depth direction and discharges the gas supplied from the gas supply source. The recovery device includes a recovery pipe accommodated in the culture tank and a suction device. The recovery pipe is a cylindrical body having an internal space. When the recovery pipe is immersed in the culture solution in the culture tank, it extends along the bottom portion of the culture tank and has a bottom-side recovery portion located below the gas supply unit in the depth direction. The bottom-side recovery portion has an opening formed at a portion facing the opening portion.

Effects of the Invention

[0009] In the above configuration, the gas discharged into the culture solution below in the depth direction of the culture tank rises upward in the depth direction of the culture tank based on the specific gravity difference from the culture solution. Based on this gas flow, convection occurs in the culture solution in the culture tank. That is, the microalgae and the culture solution flow. Specifically, the microalgae and the culture solution rise together with the gas and then descend. Thereby, the microalgae and the culture solution are agitated.

[0010] Here, the bottom recovery part, which is a part of the recovery pipe, has an opening at a part facing the opening of the culture tank. When the flow of microalgae and the culture solution reaches the bottom recovery part, the flow enters the hollow interior of the bottom recovery part from the opening, and then returns to the culture solution from the hollow interior through the opening. By forming the opening in the bottom recovery part in this way, it is avoided that the flow of microalgae and the culture solution is inhibited by the bottom recovery part. Therefore, the microalgae and the culture solution are sufficiently stirred. For this reason, the cultivation of microalgae is promoted.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0012] FIG. 1 is a schematic system diagram of a culture system 10 according to the present embodiment. The culture system 10 includes a culture device 12 and a recovery device 14.

[0013] Referring to FIGS. 1 and 2, the culture device 12 will be described. The culture device 12 has a culture tank 20 and a water storage tank 22. In this embodiment, the culture tank 20 and the water storage tank 22 are made of a material showing flexibility. As a typical example of the material showing flexibility, linear low density polyethylene (LLDPE) can be mentioned. The culture tank 20 and the water storage tank 22 are, for example, bag-shaped objects. The culture tank 20 and the water storage tank 22 are held by a holding frame 24 at a predetermined installation location.

[0014] Note that the material of the culture tank 20 does not have to be a material showing flexibility. For example, the material of the culture tank 20 may be plastic or glass. The culture device 12 does not have to have the water storage tank 22.

[0015] The bag-shaped culture tank 20 has a bottom portion 30 and four side portions 32a to 32d. The bottom portion 30 is located at the lowest position (the bottommost portion) in the gravitational direction G among all parts of the culture tank 20. The four side portions 32a to 32d are bent substantially perpendicular to the bottom portion 30 and extend upward in the vertical direction. The uppermost portion of the culture tank 20 is an opening 34. Thus, the opening 34 is located at a higher position than the bottom portion 30. The culture tank 20 is formed in a substantially square tube shape by the bottom portion 30, the four side portions 32a to 32d, and the opening 34.

[0016] Hereinafter, the extending direction along the height in the four side portions 32a to 32d is defined as the depth direction X of the culture tank 20. In this embodiment, the depth direction X of the culture tank 20 substantially coincides with the gravitational direction G. Therefore, in this embodiment, the inclination angle of the depth direction X of the culture tank 20 with respect to the gravitational direction G is substantially zero. That is, the culture tank 20 is in an upright posture.

[0017] As can be understood by comparing FIGS. 1 and 2, the length along the horizontal direction of the side portions 32a and 32c is larger than the length along the horizontal direction of the side portions 32b and 32d. Hereinafter, the horizontal direction in which the side portions 32a and 32c extend is called the extending direction Y of the culture tank 20 (see FIG. 1). The side portions 32b and 32d are located at the ends in the extending direction Y of the culture tank 20. Also, the horizontal direction in which the side portions 32b and 32d extend is called the width direction Z of the culture tank 20 (see FIG. 2).

[0018] The interior of the culture tank 20 is a space for accommodating microalgae and the culture solution L. Specific examples of microalgae include "HondaDREAMO strain" deposited at the Patent Biological Depositary Center of the National Institute of Technology and Evaluation. The location of the Patent Biological Depositary Center of the National Institute of Technology and Evaluation is Room 122, 2-5-8 Kazusa Kamashidzu, Kisarazu City, Chiba Prefecture. The deposit date of the HondaDREAMO strain is April 22, 2016, and the deposit number is FERM BP-22306. The culture solution L is typically water.

[0019] The culturing device 12 has a gas supply device 38. As shown in FIG. 1, in this embodiment, the gas supply device 38 includes a gas supply source 40, a gas supply unit 42, and a guide unit 44. The gas supply source 40 is, for example, a tank storing a gas containing carbon dioxide. The gas containing carbon dioxide is, for example, the exhaust gas from a factory. In this embodiment, the gas supply unit 42 includes a first gas supply unit 42a to a fourth gas supply unit 42d, and the guide unit 44 includes a first guide unit 44a to a fourth guide unit 44d.

[0020] The first gas supply unit 42a to the fourth gas supply unit 42d and the first guide unit 44a to the fourth guide unit 44d are inserted into the interior of the culture tank 20. In this embodiment, the first gas supply unit 42a to the fourth gas supply unit 42d and the first guide unit 44a to the fourth guide unit 44d are detachable from the culture tank 20. When recovering the microalgae and the culture solution L from the culture tank 20, the gas supply unit 42 and the guide unit 44 are not required. Therefore, after removing the gas supply unit 42 and the guide unit 44 from the culture tank 20, the microalgae and the culture solution L may be recovered from the culture tank 20. However, it is also possible to recover the microalgae and the culture solution L from the culture tank 20 with the gas supply unit 42 and the guide unit 44 inserted into the culture tank 20.

[0021] The first guide part 44a is adjacent to the side part 32b of the culture tank 20. The second guide part 44b is adjacent to the first guide part 44a with a predetermined interval along the extending direction Y. The third guide part 44c is adjacent to the second guide part 44b with a predetermined interval along the extending direction Y. The fourth guide part 44d is adjacent to the third guide part 44c with a predetermined interval along the extending direction Y. The separation intervals between the first guide part 44a and the second guide part 44b, between the second guide part 44b and the third guide part 44c, and between the third guide part 44c and the fourth guide part 44d are substantially equal to each other. In this embodiment, four first guide parts 44a to fourth guide parts 44d are provided, but the number of guide parts 44 is not limited to four and is appropriately determined according to the volume of the culture tank 20.

[0022] Each of the first guide part 44a to the fourth guide part 44d has a hook part (not shown). By holding the hook part by the holding frame 24, the first guide part 44a to the fourth guide part 44d are positioned at predetermined positions in the culture tank 20.

[0023] When the first guide part 44a to the fourth guide part 44d are viewed from the side part 32a of the culture tank 20, the first guide part 44a to the fourth guide part 44d are substantially inverted L-shaped hollow bodies. In each of the first guide part 44a to the fourth guide part 44d, the lower end and the side part facing the side part 32d of the culture tank 20 are open. Due to this opening, an intake port 46 is formed in each of the first guide part 44a to the fourth guide part 44d. That is, all the intake ports 46 of the first guide part 44a to the fourth guide part 44d face the same direction.

[0024] The first gas supply part 42a to the fourth gas supply part 42d are respectively supported by the first guide part 44a to the fourth guide part 44d. One ends of the first gas supply part 42a to the fourth gas supply part 42d are respectively connected to the gas supply source 40 shown in FIG. 1. The other ends of the first gas supply part 42a to the fourth gas supply part 42d respectively go around into the lower openings of the intake ports 46 of the first guide part 44a to the fourth guide part 44d. Gas discharge ports 48 are respectively formed at the other ends of the first gas supply part 42a to the fourth gas supply part 42d.

[0025] From the gas discharge port 48, the gas supplied from the gas supply source 40 is discharged. The gas discharged from the gas discharge port 48 flows into the first guide part 44a to the fourth guide part 44d through the lower openings of the intake ports 46 of the first guide part 44a to the fourth guide part 44d.

[0026] The inside of the water storage tank 22 is a space for storing the temperature-controlled water C. The temperature-controlled water C cools the culture solution L in the culture tank 20.

[0027] The recovery device 14 includes a recovery pipe 50 and a suction device 51. In this embodiment, the suction device 51 is a two-way pump 52. The two-way pump 52 is connected to the recovery tank 58 via the first liquid delivery pipe 54 and the second liquid delivery pipe 56. The two-way pump 52 is connected to the recovery pipe 50 via the supply and discharge pipe 60.

[0028] The two-way pump 52 sends out the culture solution L in the culture tank 20 to the recovery tank 58 through the recovery pipe 50, the supply and discharge pipe 60, and the first liquid delivery pipe 54. Also, the two-way pump 52 returns the culture solution L in the recovery tank 58 to the culture tank 20 through the second liquid delivery pipe 56, the supply and discharge pipe 60, and the recovery pipe 50. As can be understood from this, the two-way pump 52 serves as both a suction device for sucking the culture solution L in the culture tank 20 and a supply device for sending the culture solution L to the culture tank 20. Further, the recovery pipe 50 is a pipe for recovering the culture solution L from the culture tank 20 and is also a pipe for supplying the culture solution L to the culture tank 20.

[0029] The recovery pipe 50 will be described. As shown in FIG. 1, the recovery pipe 50 has a bottom-side recovery part 62 and a relay part 64. The recovery pipe 50 is a hollow body having an internal space 68. That is, the recovery pipe 50 is a cylindrical body.

[0030] The bottom recovery section 62 is adjacent to the bottom 30 of the culture tank 20 below the lower ends of the first gas supply section 42a to the fourth gas supply section 42d. The bottom recovery section 62 extends along the horizontal extension direction Y of the culture tank 20 at this position. That is, the extension direction of the bottom recovery section 62 is the same as the extension direction Y of the culture tank 20.

[0031] The bottom recovery section 62 has a base end portion 66 connected to the lower end of the relay section 64 and a tip end portion 70 facing the side portion 32b. The base end portion 66 is adjacent to the side portion 32d. The tip end portion 70 is preferably located below the first guide section 44a. In this embodiment, as shown in FIG. 1, the bottom recovery section 62 extends from one end portion (side portion 32d) in the extension direction Y of the culture tank 20 to below the first guide section 44a. The position of the tip end portion 70 is not particularly limited thereto. The position of the tip end portion 70 may be, for example, between the first guide section 44a and the second guide section 44b. The bottom recovery section 62 preferably extends from one end portion (side portion 32d) in the extension direction Y of the culture tank 20 to at least below the second guide section 44b.

[0032] As shown in FIG. 3, in the bottom recovery section 62, an opening 72 is formed at a portion facing the opening 34. The opening 72 extends along the extension direction of the bottom recovery section 62. For this reason, the cross section when the bottom recovery section 62 is viewed along the width direction Z is, for example, a semicircular shape. Through the opening 72, the internal space 68 of the bottom recovery section 62 and the inside of the culture tank 20 communicate with each other.

[0033] The cross section when the bottom recovery section 62 is viewed along the width direction Z is not particularly limited to a semicircular shape. The cross section when the bottom recovery section 62 is viewed along the width direction Z may be, for example, a rectangular shape with an open upper portion like the recovery pipe 55 shown in FIG. 4. Thus, the cross section may be a polygonal shape with an open upper portion. In FIG. 4, the same reference numerals as those of the components shown in FIG. 3 are given for easy understanding.

[0034] As shown in FIGS. 3 and 4, the tip portion 70 is an open end. That is, a terminal hole 74 is formed in the tip portion 70. The terminal hole 74 also communicates the internal space 68 of the bottom-side recovery portion 62 with the inside of the culture tank 20. The opening 72 and the terminal hole 74 are continuous with each other.

[0035] In FIGS. 3 and 4, recovery pipes 50 and 55 are respectively exemplified in which the bottom-side recovery portion 62 and the relay portion 64 are separate members. In the relay portion 64, the bent portion in an L shape may also be a separate member. Further, the recovery pipes 50 and 55 may be a single member in which the bottom-side recovery portion 62 and the relay portion 64 are integrally provided.

[0036] FIG. 5 shows an enlarged view of the bottom portion 30 of the culture tank 20 and the bottom of the water storage tank 22. Note that the line-of-sight direction in FIG. 5 is the direction from the side portion 32b to the side portion 32d. The bottom-side recovery portion 62 has a dimension D1 along the width direction Z. The dimension D1 is equal to the outer diameter of the bottom-side recovery portion 62. Therefore, hereinafter, the dimension D1 is referred to as the outer diameter D1. The first guide portion 44a to the fourth guide portion 44d have a width dimension W1 along the width direction Z. In this aspect, the outer diameter D1 of the bottom-side recovery portion 62 and the width dimension W1 of the first guide portion 44a to the fourth guide portion 44d are substantially equal to each other. However, the outer diameter D1 and the width dimension W1 may be different from each other.

[0037] As shown in FIG. 1, the relay portion 64 is continuous with the proximal end portion 66 of the bottom-side recovery portion 62 in the vicinity of the side portion 32d at the bottom portion 30. The relay portion 64 is continuous so as to bend at about 90° with respect to the bottom-side recovery portion 62. The relay portion 64 further extends along the depth direction X (gravity direction G) of the culture tank 20 adjacent to the side portion 32d of the culture tank 20. Therefore, the recovery pipe 50 has a substantially L shape. A two-way pump 52 (suction device 51) is connected to the relay portion 64 via a supply / discharge pipe 60.

[0038] The relay portion 64 is typically cylindrical. Alternatively, the relay portion 64 may be square tube-shaped. Although not particularly shown, suction holes may be formed in the relay portion 64.

[0039] The recovery pipe 50 is inserted into the interior of the culture tank 20 so as to be insertable and removable, for example. The recovery pipe 50 is operated when recovering microalgae and the culture solution L from the culture tank 20, and is not operated when culturing microalgae in the culture tank 20. However, when culturing microalgae in the culture tank 20, there is no particular need to take out the recovery pipe 50 from the culture solution L.

[0040] The culture system 10 according to this embodiment is basically configured as described above. Next, the operation of the culture system 10 will be described.

[0041] When culturing microalgae, the first guide portion 44a to the fourth guide portion 44d, the first gas supply portion 42a to the fourth gas supply portion 42d, the culture solution L, and microalgae are accommodated inside the culture tank 20. In this embodiment, at this time, the recovery pipe 50 is also accommodated in the culture tank 20.

[0042] Next, the culture solution L stored in the recovery tank 58 is supplied to the culture tank 20 through the recovery pipe 50. In this case, the bidirectional pump 52 is activated. As a result, the culture solution L in the recovery tank 58 flows through the second liquid delivery pipe 56, the supply and discharge pipe 60, and the recovery pipe 50. As described above, an opening 72 and a terminal hole 74 are formed in the bottom-side recovery portion 62 which is a part of the recovery pipe 50. Therefore, the culture solution L that has reached the internal space 68 of the recovery pipe 50 is discharged into the culture tank 20 through the opening 72 and the terminal hole 74. When the tip portion 70 is located at least below the second guide portion 44b, the culture solution L can be supplied to the culture tank 20 substantially evenly.

[0043] Next, gas containing carbon dioxide is supplied from the gas supply source 40 (see FIG. 1). The gas flows through the first gas supply unit 42a to the fourth gas supply unit 42d and is then discharged from the gas outlet 48. The gas forms bubbles 100 near the lower openings of the inlets 46 in the first to fourth guide units 44a to 44d. The inlets 46 also open at positions in the first to fourth guide units 44a to 44d that face the side 32d of the culture tank 20. Therefore, when the bubble 100 rises in the culture solution L while being guided by the first to fourth guide units 44a to 44d, the culture solution L around the bubble 100 is taken in from the side openings of the inlets 46, as shown by arrow S in FIG. 1. As a result, the culture solution L around the bubble 100 is caught up in the bubble 100.

[0044] The culture solution L entrained in the air bubbles 100 rises along the first guide section 44a to the fourth guide section 44d. Thereafter, the direction of travel of the culture solution L and the air bubbles 100 is changed by contacting the ceiling sections of the first guide section 44a to the fourth guide section 44d. That is, the culture solution L and the air bubbles 100 that rose along the first guide section 44a to the third guide section 44c flow toward the second guide section 44b to the fourth guide section 44d, respectively. The culture solution L and the air bubbles 100 that rose along the fourth guide section 44d flow toward the side section 32d of the culture tank 20.

[0045] The culture solution L that has come into contact with the second guide portion 44b to the fourth guide portion 44d descends along the second guide portion 44b to the fourth guide portion 44d. The culture solution L that has come into contact with the side portion 32d of the culture tank 20 descends along the side portion 32d.

[0046] The descending culture solution L advances toward the bottom-side collection part 62. Here, an open port 72 is formed in the bottom-side collection part 62 at a portion facing the opening 34. Therefore, the cross section of the bottom-side collection part 62 as viewed from the width direction Z is substantially semi-cylindrical. Therefore, as shown in FIG. 1 , the culture solution L flows into the internal space 68 of the bottom-side collection part 62 through the open port 72.

[0047] The culture solution L slightly circulates downward in the internal space 68 toward each of the first guide part 44a to the fourth guide part 44d. As described above, in each of the first guide part 44a to the fourth guide part 44d, the culture solution L in the culture tank 20 is taken in through the intake port 46. The culture solution L in the internal space 68 merges with the culture solution L in the culture tank 20 and is taken in from the intake port 46.

[0048] Based on the above phenomenon, as shown by the arrow A in FIG. 1, a small convection occurs between the first guide part 44a and the second guide part 44b. Similarly, small convections also occur between the second guide part 44b and the third guide part 44c, and between the third guide part 44c and the fourth guide part 44d, as shown by the arrow A. A small convection also occurs between the fourth guide part 44d and the side part 32d of the culture tank 20, as shown by the arrow A.

[0049] When the four small convections are combined, a large convection occurs in the culture solution L in the culture tank 20, as shown by the arrow B. Due to the small convection and the large convection, the bubbles 100 diffuse. That is, the carbon dioxide contained in the gas diffuses throughout the culture solution L and is sufficiently dissolved in the culture solution L. Also, due to the small convection and the large convection, the microalgae are agitated. For this reason, the microalgae are prevented from precipitating or aggregating.

[0050] The culture solution L in the culture tank 20 is cooled by the temperature-controlled water C stored in the water storage tank 22. For this reason, an excessive rise in the temperature of the culture solution L is avoided.

[0051] For the above reasons, the microalgae are cultured well throughout the culture tank 20. The microalgae are irradiated with light irradiated to the culture tank 20 during the culture. Along with this, based on the fact that the microalgae actively carry out photosynthesis, carbon dioxide is sufficiently consumed. Note that the light is sunlight or artificial light.

[0052] Thus, even when the bottom-side recovery section 62 is present in the culture tank 20, based on the formation of the opening 72 in the bottom-side recovery section 62, it is possible to cause the culture solution L to convect. That is, according to the present embodiment, it is possible to avoid the convection of the culture solution L being inhibited by the recovery pipe 50. Therefore, it is possible to culture microalgae with the recovery pipe 50 inserted into the culture tank 20.

[0053] After the cultivation of the microalgae is completed, the opening 34 of the culture tank 20 is closed, and the bidirectional pump 52 is activated. Along with this, the culture solution L and the microalgae in the culture tank 20 are sucked into the internal space 68 of the recovery pipe 50. Specifically, the culture solution L and the microalgae flow into the internal space 68 of the recovery pipe 50 from the opening 72 and the end hole 74 formed in the recovery pipe 50. The culture solution L and the microalgae are further sent to the recovery tank 58 via the supply / discharge pipe 60 and the first liquid feed pipe 54.

[0054] As the culture solution L and the microalgae are extracted from the culture tank 20, the pressure (internal pressure) of the culture solution in the culture tank 20 decreases. Since the material of the culture tank 20 has flexibility, the culture tank 20 with the reduced internal pressure contracts due to the external atmospheric pressure.

[0055] When the recovery pipe 50 does not have the bottom-side recovery section 62, as shown in FIG. 6 when looking from the side portion 32b to the side portion 32d, in the culture tank 20, for example, there is a concern that the portion below the fourth guide portion 44d narrows under the pressure of the temperature-adjusting water C in the water storage tank 22. It is difficult for the culture solution L and the microalgae to flow through such a narrowed portion. Therefore, it is also difficult to recover the culture solution L in the culture tank 20.

[0056] In contrast, in the present embodiment, the recovery pipe 50 has a bottom-side recovery portion 62. The outer diameter D1 (dimension in the width direction) of the bottom-side recovery portion 62 is substantially equal to the dimension W1 in the width direction of the first guide portion 44a to the fourth guide portion 44d. Therefore, when the culture tank 20 with reduced internal pressure contracts due to the external atmospheric pressure, as shown in FIG. 7 when viewed from the side portion 32b to the side portion 32d, the bottom-side recovery portion 62 and the first guide portion 44a to the fourth guide portion 44d function as stoppers between the side portion 32a and the side portion 32c. In other words, the bottom-side recovery portion 62 and the first guide portion 44a to the fourth guide portion 44d serve as supports that suppress excessive contraction of the culture tank 20 between the side portion 32a and the side portion 32c. Due to this support, while the culture solution L and the microalgae are being recovered, the side portion 32a and the side portion 32c are separated at a predetermined interval. Therefore, a sufficient amount of the culture solution L and the microalgae can move toward the bottom-side recovery portion 62. For the above reasons, the culture solution L and the microalgae can be smoothly guided into the internal space 68 of the bottom-side recovery portion 62 through the opening 72 and the end hole 74.

[0057] The bottom-side recovery portion 62 extends from the side portion 32b at least below the second guide portion 44b. The bottom-side recovery portion 62 preferably extends from the side portion 32b over the lower part of the first guide portion 44a. Therefore, even though the third guide portion 44c and the fourth guide portion 44d are present in the culture solution L, it is possible to sufficiently recover the culture solution L and the microalgae between the first guide portion 44a and the second guide portion 44b by the bottom-side recovery portion 62. That is, the culture solution L and the microalgae can be recovered substantially evenly throughout the culture tank 20.

[0058] As can be understood from the above, according to the present embodiment, it is possible to extract substantially all of the culture solution L and the microalgae from the culture tank 20 while suppressing the formation of wrinkles in the culture tank 20.

[0059] As the culture tank 20 contracts, the side portions 32a, 32b, and 32c of the culture tank 20 are drawn toward the bottom recovery portion 62. In the present embodiment, the tip 70 of the bottom recovery portion 62 is located below the first guide portion 44a. That is, a clearance is formed between the side portion 32b and the tip 70. Therefore, when the culture tank 20 contracts, contact between the tip 70 and the side portion 32b is avoided. For this reason, it is prevented that the tip 70 pierces through the culture tank 20.

[0060] On the other hand, it is assumed that the side portions 32a and 32c come into contact with the outer surface of the bottom recovery portion 62. Since the bottom recovery portion 62 has a substantially semi-cylindrical shape, there are no corners on the outer surface of the bottom recovery portion 62. For this reason, even when the side portions 32a and 32c come into contact with the outer surface of the bottom recovery portion 62, it is avoided that the bottom recovery portion 62 pierces through the side portions 32a and 32c.

[0061] Also, as the culture tank 20 contracts, it is assumed that the side portions 32a, 32b, and 32d of the culture tank 20 come into contact with the outer surface of the relay portion 64. Here, since the relay portion 64 has a cylindrical shape, there are no corners on the outer surface of the relay portion 64. For this reason, even when the side portions 32a, 32b, and 32d come into contact with the relay portion 64, it is avoided that the relay portion 64 pierces through the side portions 32a, 32b, and 32d.

[0062] The microalgae collected in the collection tank 58 are separated from the culture solution L by a known method such as centrifugation, coagulation separation, or natural sedimentation. The culture solution L remaining in the collection tank 58 is then withdrawn from the bottom of the collection tank 58 and returned to the culture tank 20 via the second liquid delivery pipe 56, the supply and discharge pipe 60, and the collection pipe 50. It is preferable that the culture solution L is returned to the culture tank 20 after its components are adjusted to be suitable for culturing microalgae. Thereafter, the microalgae are cultured in the same manner as described above.

[0063] Thus, by enabling the supply of the culture solution L into the culture tank 20 via the recovery pipe 50, it becomes unnecessary to provide a supply pipe different from the recovery pipe 50 in the culture system 10. Therefore, the configuration of the culture system 10 is simplified. Also, since the same culture solution L can be repeatedly used for culturing, resource conservation can be achieved.

[0064] Moreover, a space is formed below the first guide portion 44a to the fourth guide portion 44d by the bottom-side recovery portion 62. For this reason, the culture solution L can be evenly supplied to the entire culture tank 20.

[0065] Figs. 1 to 7 show an aspect in which the depth direction X of the culture tank 20 substantially coincides with the gravitational direction G. On the other hand, in the culture apparatus 112 shown in Fig. 8, the depth direction X of the culture tank 20 is inclined with respect to the gravitational direction G. Even in this aspect, the same effects as those in the aspect shown in Figs. 1 to 7 can be obtained.

[0066] As described above, the present embodiment is a culture system 10 including a culture apparatus 12 including a culture tank (20) for culturing microalgae, and a recovery apparatus (14) for recovering the microalgae from the culture tank, wherein the culture tank stores a culture solution (L), and has a bottom portion (30) located at the lowest position of the culture tank in the depth direction (X) of the culture tank, and an opening portion (34) located at a higher position than the bottom portion, the culture apparatus has a gas supply source (40) and a gas supply portion (42) inserted into the culture tank from the opening portion, the gas supply portion has a gas discharge port (48) that opens in the culture solution below in the depth direction and discharges the gas supplied from the gas supply source, the recovery apparatus has a recovery pipe (50) housed in the culture tank and a suction device (51), the recovery pipe is a cylindrical body having an internal space (68), the recovery pipe extends along the bottom portion of the culture tank when immersed in the culture solution (L) in the culture tank, and has a bottom-side recovery portion (62) located below the gas supply portion in the depth direction, and the bottom-side recovery portion has an opening (72) formed at a portion facing the opening portion.

[0067] The gas discharged into the culture solution from below in the depth direction of the culture tank rises upward in the depth direction of the culture tank based on the specific gravity difference from the culture solution. Based on this gas flow, convection occurs in the culture solution L in the culture tank. That is, the microalgae and the culture solution flow. Specifically, the microalgae and the culture solution rise together with the gas and then descend. Thereby, the microalgae and the culture solution are stirred.

[0068] Here, the bottom recovery part, which is a part of the recovery pipe, has an opening that opens at a site facing the opening of the culture tank. When the flow of the microalgae and the culture solution reaches the bottom recovery part, the flow enters the internal space of the bottom recovery part from the opening, and then returns from the internal space of the bottom recovery part to the culture tank through the opening.

[0069] As understood from the above, by forming the opening in the bottom recovery part, it is avoided that the flow of the microalgae and the culture solution is inhibited by the bottom recovery part. Therefore, the microalgae and the culture solution are sufficiently stirred. For this reason, the cultivation of microalgae is promoted.

[0070] Moreover, for the above reasons, microalgae can be cultured with the recovery pipe accommodated in the culture tank. Therefore, there is no particular need to take out the recovery pipe from the culture tank every time microalgae are cultured. For this reason, complicated work is unnecessary.

[0071] In the present embodiment, the culture device has a guide part (44) that is inserted into the culture tank from the opening and extends in the depth direction to guide the gas discharged from the gas discharge port, and the bottom recovery part is located below the guide part in the depth direction, and a culture system is disclosed.

[0072] In this configuration, it is possible to define the flow direction of the gas and the flow direction of the culture solution and the microalgae by the guide part. Further, since the bottom recovery part is located below the guide part in the depth direction, it is avoided that the upward movement of the gas in the culture tank is obstructed by the bottom recovery part.

[0073] This embodiment discloses a culture system in which the culture device has a water storage tank (22) that contains temperature - regulating water (C) for regulating the temperature of the culture solution and is adjacent to the culture tank, and the culture tank is made of a material exhibiting flexibility.

[0074] When the culture device has a water storage tank, when collecting (suctioning) the microalgae and the culture solution in the culture tank through a collection part without a bottom - side collection part, there is a concern that a part of the culture tank may collapse due to the pressure of the temperature - regulating water in the water storage tank. In other words, the flow path of the culture solution in the culture solution becomes extremely narrow. It is not easy for the culture solution to pass through a narrow flow path. Therefore, in this case, it is not easy to collect the culture solution and the microalgae.

[0075] On the contrary, according to the above - mentioned configuration, the bottom - side collection part serves as a support for suppressing excessive contraction of the culture tank. That is, the bottom - side collection part functions as a stopper for the culture tank. In this way, the bottom - side collection part supports the inner surface of the culture tank and prevents the culture tank from collapsing. Thereby, in the culture solution, a flow path of the culture solution is ensured. Therefore, it is possible to easily collect the culture solution and the microalgae.

[0076] This embodiment discloses a culture system in which when a direction parallel to the horizontal direction orthogonal to the extending direction of the bottom - side collection part is defined as the width direction (Z), the dimension (D1) in the width direction of the bottom - side collection part is substantially equal to the dimension (W1) in the width direction of the guide part.

[0077] In this case, the guide part functions as a stopper for the culture tank. That is, the guide part supports the inner surface of the culture tank and prevents the culture tank from collapsing. As a result, in the culture solution, a sufficient flow path of the culture solution is ensured. Therefore, it is possible to more easily collect the culture solution and the microalgae.

[0078] In this embodiment, the recovery pipe has a relay part (64) that connects one end of the bottom-side recovery part in the extending direction and the suction device at one end of the culture tank in the extending direction, and extends along the depth direction. The relay part is formed in a cylindrical shape, and the bottom-side recovery part is formed in a semi-circular cross-section by the opening, and a culture system is disclosed.

[0079] Since the bottom-side recovery part has a semi-circular cross-section, there are no corners on the outer surface of the bottom-side recovery part. Therefore, when recovering (suctioning) the culture solution from the culture tank, even if the contracted culture tank comes into contact with the bottom-side recovery part, the bottom-side recovery part is prevented from piercing through the culture tank.

[0080] In this embodiment, the recovery pipe has a relay part (64) that connects one end of the bottom-side recovery part in the extending direction and the suction device at one end of the culture tank in the horizontal extending direction, and extends along the depth direction. The guide part has a first guide part (44a) and a second guide part (44b) arranged adjacent to each other at intervals in the extending direction of the culture tank. The first guide part extends along the depth direction adjacent to the other end of the culture tank in the extending direction, and the second guide part is located between the first guide part and the relay part in the extending direction of the culture tank. The bottom-side recovery part extends from the one end of the culture tank in the extending direction to at least below the second guide part, and a culture system is disclosed.

[0081] The bottom-side recovery part extends from one end of the culture tank in the extending direction to between the first guide part and the second guide part. Therefore, even if another guide part is provided between the second guide part and the relay part, it is easy to recover the culture solution in the culture tank substantially evenly.

[0082] In this embodiment, the bottom-side recovery part extends from the one end of the culture tank in the extending direction to below the first guide part, and a culture system is disclosed.

[0083] In this case, the tip of the bottom-side recovery part is located below the first guide part. Therefore, when the culture tank contracts, the tip of the bottom-side recovery part is prevented from contacting the other end in the extending direction of the culture tank. For this reason, it is possible to prevent the tip of the bottom-side recovery part from piercing through the culture tank.

[0084] This embodiment discloses a culture system capable of supplying the culture solution into the culture tank via the recovery pipe.

[0085] In this case, the recovery pipe also serves as a supply pipe for supplying the culture solution. Therefore, there is no need to separately provide the recovery pipe and the supply pipe inside the culture tank. Therefore, the culture system is simplified. Also, in some cases, the same culture solution can be repeatedly used for culturing. For this reason, resource savings can be achieved. Moreover, inside the culture tank, a sufficient space is formed below the guide part by the bottom-side recovery part. For this reason, it is possible to uniformly supply the culture solution throughout the culture tank.

[0086] Note that the present invention is not limited to the above-described disclosure, and various configurations can be adopted without departing from the gist of the present invention.

Explanation of Reference Numerals

[0087] 10…Culture system 12, 112…Culture device 14…Recovery device 20…Culture tank 22…Water storage tank 30…Bottom 32a~32d…Side parts 34…Opening 38…Gas supply device 40…Gas supply source 42…Gas supply part 44…Guide part 46…Intake port 48…Gas discharge port 50, 55…Recovery pipes 51…Suction device 52…Bidirectional pump 58…Recovery tank 62…Bottom-side recovery part 64…Relay part 68…Internal space 72…Opening 100…Bubble C…Temperature-controlled water L…Culture solution

Claims

1. A culture system comprising a culture device including a culture tank for culturing microalgae and a recovery device for recovering the microalgae from the culture tank, wherein the culture tank contains a culture solution and has a bottom located at the lowest position of the culture tank in the depth direction thereof and an opening located at a higher position than the bottom, the culture device has a gas supply source and a gas supply part inserted into the culture tank from the opening, the gas supply part has a gas discharge port that opens in the culture solution below in the depth direction and discharges the gas supplied from the gas supply source, the recovery device has a recovery pipe accommodated in the culture tank and a suction device, the recovery pipe is a cylindrical body having an internal space, the recovery pipe has a bottom-side recovery part that extends along the bottom of the culture tank when immersed in the culture solution in the culture tank and is located below the gas supply part in the depth direction, the bottom-side recovery part has an opening formed at a site facing the opening, the opening is provided so as to extend along the extending direction of the bottom-side recovery part, and when the bottom-side recovery part is viewed along the width direction, the upper part of the cross section of the bottom-side recovery part is open, the culture system.

2. In the culture system according to Claim 1, the culture device has a guide part that is inserted into the culture tank from the opening, extends in the depth direction, and guides the gas discharged from the gas discharge port, wherein the bottom-side recovery part is located below the guide part in the depth direction, the culture system.

3. In the culture system according to Claim 2, the culture device has a water storage tank that contains temperature-adjusting water for adjusting the temperature of the culture solution and is adjacent to the culture tank, wherein the culture tank is made of a material exhibiting flexibility, the culture system.

4. In the culture system according to Claim 3, when a direction parallel to the horizontal direction orthogonal to the extending direction of the bottom-side recovery part is defined as the width direction, the dimension of the bottom-side recovery part in the width direction is substantially equal to the dimension of the guide part in the width direction, the culture system.

5. In the culture system according to Claim 3, the recovery pipe has a relay part that connects one end in the extending direction of the bottom-side recovery part and the suction device at one end in the extending direction of the culture tank and extends along the depth direction, wherein the relay part is formed in a cylindrical shape. The bottom-side recovery part is a culture system formed in a semi-circular cross-section by the opening. **Claim 6** In the culture system according to claim 3, the recovery pipe connects one end of the extending direction along the horizontal direction in the culture tank to one end of the extending direction of the bottom-side recovery part and the suction device, and has a relay part extending along the depth direction. The guide part has a first guide part and a second guide part arranged adjacent to each other at intervals in the extending direction of the culture tank. The first guide part extends along the depth direction adjacent to the other end of the extending direction of the culture tank. The second guide part is located between the first guide part and the relay part in the extending direction of the culture tank. The bottom-side recovery part is a culture system extending from the one end in the extending direction of the culture tank to at least below the second guide part. **Claim 7** In the culture system according to claim 6, the bottom-side recovery part is a culture system extending from the one end in the extending direction of the culture tank over below the first guide part. **Claim 8** In the culture system according to any one of claims 1 to 7, the culture solution can be supplied into the culture tank through the recovery pipe.

Images