Culture device

Abstract

To provide a culture apparatus in which microalgae do not accumulate on the inner bottom surface of the containment section. [Solution] The culture apparatus 10 comprises a containment section 20 capable of containing culture solution CS and microalgae, a guide section 40 for guiding culture gas G, and a gas supply section 30 for supplying culture gas G to the culture solution CS. The supply pipe section 36 constituting the gas supply section 30 has a main pipe section 362 extending along the depth direction of the containment section 20 and a sub-pipe section 363 extending along a protruding direction intersecting the depth direction. The outlet 38 formed in the sub-pipe section 363 is located below the lower end 43 of the guide section and is formed in a portion of the sub-pipe section 363 that protrudes in the protruding direction from the lower end 43 of the guide section.

Description

Technical Field

[0001] The present disclosure relates to a culture device for culturing microalgae.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2024-68690 discloses a culture device for culturing microalgae. This culture device includes a storage unit for storing a culture solution and microalgae, a guide unit provided in the storage unit, and a gas supply pipe for discharging culture gas to the guide unit. The lower end of the gas supply pipe is curved so as to face the lower end of the guide unit. The lower end of the gas supply pipe has a discharge port, and the lower end of the guide unit has a receiving port.

[0003] The discharge port and the receiving port face each other, and the culture gas discharged from the discharge port quickly passes through the receiving port and rises along the guide unit toward the liquid surface of the culture solution. Due to such a flow of the culture gas, as shown in FIG. 1 of Japanese Unexamined Patent Application Publication No. 2024-68690, convection occurs in the culture solution.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The relative density of microalgae is greater than that of the culture solution. Therefore, microalgae tend to settle in the storage unit. When microalgae accumulate on the inner bottom surface of the storage unit, it is not easy to lift the accumulated microalgae from the inner bottom surface even if convection occurs in the culture solution.

[0006] The present disclosure aims to solve the above-described problems.

Means for Solving the Problems

[0007] An aspect of the present disclosure is a culture apparatus for culturing microalgae in a culture medium, comprising: a containment section capable of containing the culture medium and the microalgae; a guide section extending within the containment section along the depth direction of the containment section and guiding the culture gas supplied into the containment section; and a gas supply section supplying the culture gas to the guide section, wherein the gas supply section has a supply pipe section through which the culture gas flows and an outlet for discharging the culture gas from the supply pipe section, the supply pipe section having a main pipe section extending along the depth direction of the containment section and a sub-pipe section protruding from the lower end of the main pipe section, which is the lower end of the main pipe section in the depth direction, and extending along a protruding direction intersecting the depth direction, and the outlet is formed in the sub-pipe section in a portion located below the lower end of the guide section, which is the lower end of the guide section in the depth direction, and protruding from the lower end of the guide section in the protruding direction. [Effects of the Invention]

[0008] According to this disclosure, it is possible to suppress the sinking of microalgae in the region below the lower end of the guide portion in the depth direction of the containment portion. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of the culture apparatus. [Figure 2] Figure 2 is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 3 is a cross-sectional view of the main part of the culture apparatus. [Figure 4] Figure 4 is a cross-sectional view of the main part of a culture apparatus according to a comparative embodiment. [Modes for carrying out the invention]

[0010] In the following, "culture gas" refers to gas containing carbon dioxide, which is useful for photosynthesis in microalgae. A specific example of culture gas is air. The culture gas may also be exhaust gas discharged from a factory's exhaust line.

[0011] Figure 1 is a schematic diagram of the culture apparatus 10. The culture apparatus 10 includes a housing section 20. In the illustrated example, one housing section 20 is shown, but there may be two or more housing sections 20.

[0012] The containment section 20 is made of, for example, a flexible bag material. In this case, the containment section 20 is supported by a support frame (not shown). The containment section 20 is positioned upright, for example, so that the depth direction (D direction) of the culture medium CS coincides with the vertical direction. Alternatively, the containment section 20 is positioned at an inclination so that the depth direction of the culture medium CS is inclined with respect to the vertical direction. An opening 22 is formed at the upper end of the containment section 20. The opening 22 may be sealed. The containment section 20 may also be a box made of a rigid, non-flexible transparent resin.

[0013] The storage section 20 extends along the direction of arrangement (X direction) described later. The storage section 20 has a bottom 24. The bottom 24 has an inner bottom surface 25 facing the inside of the storage section 20. The storage section 20 further has a side 26 located at one end in the X direction and a side 28 located at the other end in the X direction. The side 26 is the leftmost part in Figure 1, and the side 28 is the rightmost part in Figure 1.

[0014] The containment section 20 contains the culture medium CS and microalgae. The containment section 20 is a culture tank for culturing microalgae. A specific example of the culture medium CS is water. It is preferable that phosphorus, nitrogen, potassium, etc. are added to the culture medium CS. A specific example of microalgae is the "Honda DREAMO strain" deposited with the Patent Organism Depositary Center of the National Institute of Technology and Evaluation. The address of the Patent Organism Depositary Center of the National Institute of Technology and Evaluation is Room 120, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture. The deposit date for the Honda DREAMO strain was April 22, 2016, and the deposit number is FERM BP-22306.

[0015] The containment section 20 may be surrounded by a water reservoir (not shown). Water is stored in the water reservoir. The water is a cooling medium for cooling the culture medium CS inside the containment section 20. The water reservoir and the containment section 20 are each formed from a light-transmitting material. Therefore, light irradiated from outside the water reservoir passes through the water reservoir and the containment section 20 and reaches the inside of the containment section 20.

[0016] The culture apparatus 10 is equipped with a plurality of guide sections 40 that guide the culture gas G to the surface of the culture medium CS. The plurality of guide sections 40 are spaced apart from each other and arranged in a line along the direction (X direction). Hereinafter, in order to facilitate the distinction between the plurality of guide sections 40, an example will be given in which there are four guide sections 40, and the guide section 40 located at the far left of Figure 1 will be referred to as the first guide section 40a. In Figure 1, the guide section 40 located to the right of the first guide section 40a will be referred to as the second guide section 40b, and the guide section 40 located to the right of the second guide section 40b will be referred to as the third guide section 40c. Furthermore, the guide section 40 located to the right of the third guide section 40c will be referred to as the fourth guide section 40d.

[0017] The configuration of the first guide section 40a will now be described. The first guide section 40a has a main body section 42. The main body section 42 extends along the depth direction of the housing section 20. When the depth direction coincides with the vertical direction, the extension direction of the first guide section 40a is the vertical direction. When the depth direction is inclined with respect to the vertical direction, the extension direction of the first guide section 40a is a direction that intersects with respect to the vertical direction. The lower end of the main body section 42 in the depth direction is the lower end of the guide section 43. The upper end of the main body section 42 in the depth direction is the upper end of the guide section 44. A horizontal guide section projecting horizontally may be provided at the upper end of the main body section 42.

[0018] As shown in Figure 2, the main body 42 has a first wall portion 421, a second wall portion 422, and a third wall portion 423. The first wall portion 421 and the third wall portion 423 are spaced apart with the second wall portion 422 in between and face each other. In the illustrated example, the first wall portion 421 and the third wall portion 423 are parallel to each other. The first wall portion 421 and the third wall portion 423 may be non-parallel to each other. Note that Figure 1 shows a cross-section with the first wall portion 421 cut off.

[0019] As shown in FIG. 1, an opening 461 is formed at the lower end 43 of the guide portion, and an opening 462 is formed between the first wall portion 421 and the third wall portion 423. The opening 462 extends from the lower end 43 of the guide portion to the upper end of the main body portion 42. The inlet 46 is formed by the opening 461 and the opening 462.

[0020] The inlet 46 faces the side portion 28 of the accommodating portion 20. In other words, the inlet 46 faces the second wall portion 422 of the second guide portion 40b. Since the first guide portion 40a has the first wall portion 421, the second wall portion 422, the third wall portion 423, and the inlet 46, when the first guide portion 40a is cut along the horizontal direction as shown in FIG. 2, the cross-sectional shape of the first guide portion 40a is U-shaped. As shown in FIG. 1, the opening at the upper end 44 of the guide portion of the first guide portion 40a is the insertion port 48.

[0021] The first guide portion 40a configured as described above is supported by a support frame via, for example, a hook member (not shown). Alternatively, the first guide portion 40a is welded to the inner surface of the accommodating portion 20.

[0022] The second guide portion 40b to the fourth guide portion 40d have the same configuration as the first guide portion 40a. Therefore, in the second guide portion 40b to the fourth guide portion 40d, the same reference numerals are given to the same components as those in the first guide portion 40a, and detailed descriptions thereof are omitted. The inlets 46 of each of the second guide portion 40b to the fourth guide portion 40d open facing the inner bottom surface 25 and the side portion 28 of the accommodating portion 20.

[0023] The culture device 10 includes a gas supply unit 30. The gas supply unit 30 has a gas supply source 32, a supply pipe portion 36, and an exhaust port 38. The gas supply source 32 is, for example, a compressor 34. The compressor 34 obtains compressed air from the atmosphere, for example, and sends this compressed air as the culture gas G to the supply pipe portion 36. The compressor 34 may compress the exhaust gas from the factory to obtain compressed exhaust gas and send this compressed exhaust gas as the culture gas G to the supply pipe portion 36. Alternatively, the gas supply source 32 may be a cylinder filled with compressed air or carbon dioxide gas.

[0024] The supply pipe section 36 has a base pipe section 361, a plurality of main pipe sections 362, and a plurality of sub-pipe sections 363. An on-off valve 52 is provided in the base pipe section 361. The opening and closing operation of the on-off valve 52 is controlled by the control unit 50.

[0025] Multiple main pipe sections 362 are connected to the compressor 34 via a base pipe section 361. The number of multiple main pipe sections 362 is, for example, the same as the number of guide sections 40.

[0026] Multiple main pipe sections 362 extend along the depth direction of the housing section 20. In the illustrated example, each main pipe section 362 is inserted into the main body section 42 of each guide section 40. Alternatively, the main pipe section 362 may be brought into contact with the outer surface of the second wall section 422. The lower end of the main pipe section 362 in the depth direction is the main pipe section lower end 365. The main pipe section lower end 365 is located below the guide section lower end 43 in the depth direction. That is, the main pipe section lower end 365 is closer to the inner bottom surface 25 than the guide section lower end 43.

[0027] The sub-pipe section 363 is connected to the lower end 365 of the main pipe section and protrudes along a projection direction (P direction) that intersects with the depth direction. In the illustrated example, the projection direction is from side section 26 to side section 28 and is approximately parallel to the inner bottom surface 25 and the alignment direction (X direction). Therefore, the sub-pipe section 363 is bent at approximately 90° relative to the main pipe section 362. As a result, the main pipe section 362 and the sub-pipe section 363 form an approximately L-shape. However, it is not essential that the projection direction is parallel to the inner bottom surface 25, nor is it essential that the intersection angle of the sub-pipe section 363 with respect to the main pipe section 362 is 90°. The sub-pipe section 363 is located slightly above the inner bottom surface 25.

[0028] In the embodiment shown in Figure 2, the protruding length of the sub-pipe section 363 is smaller than the depth-direction length of the main pipe section 362. In the protruding direction, the protruding tip of the sub-pipe section 363 (the end facing the side section 28) is located beyond the lower end 43 of the guide section.

[0029] Refer to Figure 3 for an explanation of the protrusion amounts of each part. In Figure 3, L1 is the distance from the lower end 43 of the guide section to the lower end of the sub-pipe section 363. A suitable range for L1 is 1 cm to 5 cm, and an even more suitable range is 2 cm to 4.5 cm. However, L1 is not limited to this numerical range. L2 is the distance from the end of the lower end 365 of the main pipe section facing the side section 28 to the protruding tip of the sub-pipe section 363. L2 is set according to the internal dimensions of the housing section 20 and the dimensions in the direction of alignment (X direction) of the guide sections 40.

[0030] Let L3 be the distance from one end of the lower end 43 of the guide section (the end facing the side section 28) in the alignment direction to the protruding tip of the sub-tube section 363. Preferably, L3 is approximately twice or more the dimension of the lower end 43 of the guide section in the direction along the alignment direction (X direction). However, L3 is not limited to this length. Let H be the distance from the inner bottom surface 25 to the lower end of the sub-tube section 363. Preferably, H is as small as possible.

[0031] The outlet 38 is formed in the sub-tube section 363. The outlet 38 opens, for example, at the protruding tip of the sub-tube section 363, facing in the direction of protrusion (side portion 28). In this case, the outlet 38 is located below the lower end 43 of the guide section and closer to the side portion 28 than the lower end 43 of the guide section. However, the position where the outlet 38 is formed is not limited to the protruding tip of the sub-tube section 363. The position where the outlet 38 is formed is any portion of the sub-tube section 363 that is located below the lower end 43 of the guide section and protrudes in the direction of protrusion from the lower end 43 of the guide section. Also, the outlet 38 may face the inner bottom surface 25 or the liquid surface of the culture medium CS.

[0032] Next, a method for culturing microalgae using the culture apparatus 10 will be described. For the sake of brevity, the following description will focus on a configuration in which the gas supply source 32 is a compressor 34, as shown in Figure 1, and compressed air is supplied as the culture gas G.

[0033] First, microalgae and culture solution CS are transferred from a recovery tank (not shown) to the storage unit 20. Specifically, the control unit 50 opens the on-off valve 52 and energizes a pump (not shown). When it is detected that a predetermined amount of microalgae and culture solution CS has been stored in the storage unit 20, the control unit 50 closes the on-off valve 52 and stops the pump (not shown). This stops the transfer of microalgae and culture solution CS from the recovery tank to the storage unit 20.

[0034] Next, the control unit 50 energizes the compressor 34. This supplies compressed air to each main pipe section 362 via the base pipe section 361 of the supply pipe section 36. The compressed air that has flowed through each main pipe section 362 moves to each sub-pipe section 363 and is then discharged as culture gas G from each outlet 38 into the culture medium CS in the containment section 20. The direction of discharge of the culture gas G from each outlet 38 is toward the side section 28.

[0035] As shown in Figure 1, the bubbles of culture gas G discharged toward the side portion 28 quickly change direction and rise toward the liquid surface of the culture medium CS. The bubbles flow into the main body portion 42 of each guide portion 40 from the receiving port 46 (particularly the opening 462). Consequently, the culture medium CS surrounding the bubbles is taken into the main body portion 42 from the receiving port 46. The culture medium CS inside the main body portion 42 then rises along the main body portion 42.

[0036] Referring to Figure 1, the section between the side portion 26 and the first guide portion 40a will be explained as an example. A portion of the culture medium CS is guided by the main body portion 42 in the first guide portion 40a, rises within the main body portion 42 together with air bubbles, and reaches the upper end 44 of the guide portion. Next, the culture medium CS flows out from the portion located at the upper end 44 of the guide portion in the receiving port 46 toward the second guide portion 40b. The culture medium CS that has flowed out from within the main body portion 42 moves toward the second guide portion 40b. That is, the direction of travel of the culture medium CS is changed from the depth direction (D direction) to the alignment direction (X direction).

[0037] The culture medium CS directed toward the second guide section 40b comes into contact with the second wall 422 of the main body section 42 in the second guide section 40b. The culture medium CS descends along the second wall 422. Since the main tube section 362 is inserted into the main body section 42 of the second guide section 40b, obstruction of the flow of the culture medium CS descending along the second wall 422 by the main tube section 362 is avoided.

[0038] The descending culture medium CS changes direction to move along the inner bottom surface 25. Near the protruding tip of the sub-tube section 363, the culture gas G discharged from the outlet 38 toward the side section 28 comes into contact with the culture medium CS. The culture gas G (bubbles) quickly changes direction in the same manner as above and rises toward the liquid surface of the culture medium CS. This imparts an upward flow force to the flow of the culture medium CS moving along the inner bottom surface 25. The flow of the culture medium CS enters the main body section 42 of the first guide section 40a together with the culture gas G and rises along the main body section 42.

[0039] As described above, small convection currents are generated between the first guide section 40a and the second guide section 40b, as indicated by arrow A in Figure 1. Similarly, small convection currents are generated between the second guide section 40b and the third guide section 40c. Small convection currents are also generated between the third guide section 40c and the fourth guide section 40d, and furthermore, small convection currents are generated between the fourth guide section 40d and the inner surface of the side section 28 of the housing section 20.

[0040] The combination of four small convection currents generates a large convection current within the containment section 20, as indicated by arrow B. Since each of the first guide sections 40a to the fourth guide section 40d is equipped with a first wall section 421 and a third wall section 423, leakage of the culture gas G and culture medium CS that have entered the main body section 42 from the sides of each main body section 42 is prevented. As a result, a large convection current can be generated effectively.

[0041] The culture medium CS in the containment section 20 is agitated by small and large convection currents. As a result, the carbon dioxide contained in the culture gas G diffuses throughout the culture medium CS in the containment section 20 and dissolves sufficiently in the culture medium CS. During cultivation, the microalgae fix a large amount of carbon dioxide based on their active photosynthesis. This consumes the carbon dioxide.

[0042] Incidentally, microalgae tend to sink along downward currents in small convection currents. Microalgae also tend to sink in the culture medium CS due to their own weight. However, as shown in Figure 1, the culture medium CS that has descended along the second guide section 40b then moves towards the first guide section 40a along the inner bottom surface 25. The same is true for the culture medium CS that has descended along the second guide section 40b, the third guide section 40c, and the fourth guide section 40d.

[0043] In other words, by positioning the outlet 38 below the lower end 43 of the guide section and protruding in a direction (for example, in the direction of alignment) from the lower end 43 of the guide section, small and large convection currents pass directly above the inner bottom surface 25. If microalgae accumulate on the inner bottom surface 25, the flow of culture medium CS passing directly above the inner bottom surface 25 comes into contact with the microalgae. This causes the microalgae to be broken down. The broken-down microalgae then diffuse within the culture medium CS. In this way, the accumulation of microalgae on the inner bottom surface 25 is suppressed. Therefore, the microalgae in the containment section 20 can be evenly involved in photosynthesis. Moreover, the stirring by small and large convection currents also suppresses the aggregation of microalgae within the containment section 20.

[0044] For comparison, the culture apparatus 100 shown in Figure 4 will be described. Note that components identical to those shown in Figures 1 and 2 are given the same reference numerals. In this culture apparatus 100, a straight tube section 360 is used instead of the main tube section 362 and the sub-tube section 363. In the depth direction (direction D), the lower end 367 of the straight tube section 360 is located above the lower end 43 of the guide section. The straight tube section 360 does not have a tube section corresponding to the sub-tube section 363 connected to it, and the outlet 38 formed in the straight tube section 360 opens toward the inner bottom surface 25.

[0045] A portion of the culture gas G (compressed air) discharged from the outlet 38 of the straight pipe section 360 flows out of the main body section 42 through the opening 461 at the lower end 43 of the guide section, and then quickly changes direction toward the surface of the culture medium CS. This culture gas G may cause a flow (reverse flow S) to be generated in the culture medium CS between the second guide section 40b and the third guide section 40c, rising toward the surface and flowing into the space between the first guide section 40a and the second guide section 40b.

[0046] When this situation occurs, the reverse flow S obstructs the flow descending along the second guide section 40b. As a result, the force of the small convection between the first guide section 40a and the second guide section 40b weakens. Consequently, the force of the large convection also weakens. Therefore, it is not easy to agitate the culture medium CS in the containment section 20 with small and large convection.

[0047] Moreover, the distance from the outlet 38 to the inner bottom surface 25 is relatively large, and the culture gas G is discharged into the main body 42 of the guide section 40. In this case, the small convection between the first guide section 40a and the second guide section 40b descends along the second guide section 40b, changes direction to face the alignment direction, and then begins to rise at a position relatively far from the lower end 43 of the guide section. Therefore, the flow of the small convection that faces the alignment direction flows at a position far from the inner bottom surface 25. Consequently, the flow of the large convection that faces the alignment direction also flows at a position far from the inner bottom surface 25.

[0048] For the reasons stated above, in the region ER, which is closer to the inner bottom surface 25 than the lower end 43 of the guide section, it is not easy for small or large convection currents to push out microalgae. Therefore, there is a concern that microalgae deposits RA will form on the inner bottom surface 25 in the culture device 100.

[0049] In other words, as shown in Figure 1, by forming an outlet 38 in the sub-tube section 363 at a portion located below the lower end 43 of the guide section and protruding in a direction beyond the lower end 43 of the guide section, it is possible to suppress the accumulation of microalgae on the inner bottom surface 25. As a result, the microalgae can be effectively utilized. In other words, microalgae can be cultivated evenly within the containment section 20.

[0050] This embodiment provides the following effects.

[0051] As described above, the discharge port 38 is formed in the sub-pipe section 363 in a portion that is located below the lower end 43 of the guide section and protrudes in a direction beyond the lower end 43 of the guide section.

[0052] This prevents microalgae from settling below the lower end 43 of the guide section (for example, near the inner bottom surface 25) in the depth direction of the containment section 20. Therefore, microalgae can be cultivated evenly within the containment section 20. In other words, microalgae can be effectively utilized.

[0053] The secondary pipe section 363 is bent at approximately 90° relative to the main pipe section 362. As a result, convection is easily generated in the culture medium CS within the containment section 20.

[0054] The sub-tube section 363 extends along the inner bottom surface 25 of the containment section 20. As a result, the convection of the culture medium CS passes near the inner bottom surface 25. Since microalgae near the inner bottom surface 25 are moved by the convection, the accumulation of microalgae on the inner bottom surface 25 of the containment section 20 is suppressed.

[0055] The outlet 38 is formed in the sub-pipe section 363 at a position facing the protruding direction (direction P). As a result, convection is easily generated in the culture medium CS as the culture gas G rises toward the guide section 40.

[0056] The guide portion 40 has an inlet 46 on its side that extends along the depth direction (direction D). Therefore, the cross-section of the guide portion 40 cut along the horizontal direction is U-shaped.

[0057] With this configuration, convection flows easily from the inlet 46 into the inside of the guide section 40. Therefore, it is easy to cause the convection to rise along the guide section 40.

[0058] The main tube section 362 is inserted into the guide section 40. This prevents the main tube section 362 from obstructing the convection of the culture medium CS generated in the containment section 20.

[0059] The following additional information is disclosed regarding the above embodiments.

[0060] (Note 1) The culture apparatus (10) of the present disclosure is a culture apparatus for culturing microalgae in a culture medium (CS), comprising: a containment section (20) capable of containing the culture medium and the microalgae; a guide section (40) extending along the depth direction (D) of the containment section and guiding the culture gas (G) supplied into the containment section; and a gas supply section (30) supplying the culture gas to the guide section, wherein the gas supply section comprises a supply pipe section (36) through which the culture gas flows and a discharge section for discharging the culture gas from the supply pipe section. The supply pipe section has an outlet (38) and a main pipe section (362) that extends along the depth direction of the housing section and a sub-pipe section (363) that protrudes from the lower end (365) of the main pipe section, which is the lower end of the main pipe section in the depth direction, and extends along a protruding direction (P) that intersects with the depth direction, and the discharge port is formed in the sub-pipe section in a portion that is located below the lower end (43) of the guide section, which is the lower end of the guide section in the depth direction, and that protrudes from the lower end of the guide section in the protruding direction.

[0061] In the depth direction, the culture gas is discharged into the culture medium below the lower end of the guide section. Therefore, the convection of the culture medium generated within the containment section can flow below the lower end of the guide section. This flow suppresses the sedimentation of microalgae in the region below the lower end of the guide section.

[0062] (Note 2) In the culture apparatus described in Appendix 1, the secondary tube may be bent at approximately 90° relative to the main tube.

[0063] This configuration makes it easier for convection to occur in the culture medium within the containment section.

[0064] (Note 3) In the culture apparatus described in Appendix 1 or 2, the sub-tube portion may extend along the inner bottom surface (25) of the housing portion.

[0065] In this case, the convection of the culture medium passes near the inner bottom surface, which can suppress the accumulation of microalgae on the inner bottom surface.

[0066] (Note 4) In the culture apparatus described in any one of the appendices 1 to 3, the outlet may be formed in the sub-tube section at a position facing the direction of protrusion.

[0067] The culture gas, initially discharged in the direction of protrusion, quickly changes direction to rise towards the liquid surface. This rise in culture gas easily generates convection in the culture medium.

[0068] (Note 5) In the culture apparatus described in any one of the appendices 1 to 4, the guide portion has an inlet (46) on the side extending along the depth direction into which the culture medium can flow, and the cross-section obtained by cutting the guide portion along a horizontal direction perpendicular to the depth direction may be U-shaped.

[0069] With this configuration, convection flows easily from the inlet into the guide section. Therefore, the convection easily rises along the guide section.

[0070] (Note 6) In the culture apparatus described in Appendix 5, the main tube portion may be inserted inside the guide portion.

[0071] This configuration prevents the main tubing from obstructing the convection of the culture medium generated within the containment section.

[0072] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the intent of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0073] 10...Culture apparatus 20...Storage section 25...Inner bottom surface 30...Gas supply section 36…Supply pipe section 38…Discharge port 40... Guide section 42... Main body section 43...Lower end of guide section 46...Inlet 362…Main pipe part 363…Sub-pipe part 365...Lower end of main pipe 421...First wall part 422...Second wall part 423...Third wall part CS...Culture medium G...Culture gas

Claims

1. A culture apparatus for culturing microalgae in a culture medium, A containment section capable of containing the culture solution and the microalgae, A guide portion extends within the containment portion along the depth direction of the containment portion and guides the culture gas supplied into the containment portion, A gas supply unit that supplies the culture gas to the guide unit, Equipped with, The gas supply unit has a supply pipe through which the culture gas flows, and an outlet for discharging the culture gas from the supply pipe. The supply pipe section comprises a main pipe section extending along the depth direction of the housing section, and a sub-pipe section protruding from the lower end of the main pipe section, which is the lower end of the main pipe section in the depth direction, and extending along a protruding direction that intersects with the depth direction. The culture apparatus wherein the discharge port is formed in the sub-tube portion, located below the lower end of the guide portion in the depth direction and protruding in the protruding direction from the lower end of the guide portion.

2. A culture apparatus according to claim 1, wherein the sub-tube portion is bent at approximately 90° relative to the main tube portion.

3. A culture apparatus according to claim 1, wherein the sub-tube portion extends along the inner bottom surface of the housing portion.

4. A culture apparatus according to claim 3, wherein the outlet is formed in the sub-tube portion at a position facing the protruding direction.

5. A culture apparatus according to claim 1, wherein the guide portion has an inlet on a side portion extending along the depth direction into which the culture medium can flow, and the cross-section obtained by cutting the guide portion along a horizontal direction perpendicular to the depth direction is U-shaped.

6. A culture apparatus according to claim 5, wherein the main tube portion is inserted into the inside of the guide portion.

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