Culture System

Abstract

To provide a culturing system for culturing microalgae that eliminates the need for a water level sensor to detect the liquid surface of a culturing solution.SOLUTION: A culturing system 10 is equipped with a culturing tank 20 and a supply device 30 for supplying a culturing solution L to the culturing tank. The culturing tank includes a plurality of accommodation sections 22 capable of accommodating the culturing solution. The supply device includes a liquid delivery device 34 for delivering the culturing solution to the plurality of accommodation sections, and supply pipes 38 for supplying the culturing solution to the plurality of accommodation sections, respectively. The culturing system includes first float valves 48 that can open and close the supply pipes. The first float valves each include a first float 50, where the first float moves upward in the depth direction X of the accommodation sections as the liquid surface of the culturing solution rises along the depth direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a culture system for culturing microalgae. [Background technology]

[0002] Efforts aimed at mitigating or reducing the impact of climate change have been ongoing, and research and development into reducing carbon dioxide emissions has been conducted to achieve this. From this perspective, microalgae have attracted attention because they consume carbon dioxide through photosynthesis. Therefore, microalgae cultivation systems are expected to contribute to mitigating or reducing the impact of climate change.

[0003] The culture system includes a tank for storing culture solution, a storage unit that stores the culture solution and microalgae and cultivates the microalgae, and a control unit. The tank and storage unit are connected via a supply pipe. A solenoid valve is provided on the supply pipe. When the culture solution is supplied from the tank to the storage unit, the level of the culture solution in the storage unit is detected by a water level sensor (liquid level indicating regulator) described as prior art in Patent Document 1. The control unit acquires information regarding the level of the culture solution in the storage unit. When the level of the culture solution reaches a water level input in advance to the control unit, the control unit transmits a control signal to close the solenoid valve.

[0004] When a culture system has multiple storage units, the above configuration requires the same number of water level sensors and solenoid valves as the number of storage units. This results in high capital investment. In addition, the need for cables to electrically connect the water level sensors to the control unit and cables to electrically connect the solenoid valves to the control unit makes the wiring of these cables cumbersome.

[0005] In order to eliminate the need for a water level sensor and a solenoid valve, it is conceivable to provide a rotatable U-shaped tube in the storage unit, as proposed in Patent Document 1. According to Patent Document 1, the level of the liquid stored in the storage unit can be changed without using a water level sensor by rotating the U-shaped tube to change the angle of inclination with respect to the vertical direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 1-247077 Summary of the Invention [Problem to be solved by the invention]

[0007] In the technique described in Patent Document 1, the tilt angle of the U-shaped tube needs to be changed manually by an operator, which is cumbersome.

[0008] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0009] According to one embodiment of the present invention, there is provided a culture system comprising a culture tank for culturing microalgae and a supply device for supplying culture solution to the culture tank, wherein the culture tank has a plurality of storage sections capable of storing the culture solution, the supply device has a liquid delivery device that delivers the culture solution to the plurality of storage sections, and a supply pipe that supplies the culture solution delivered from the liquid delivery device to each of the plurality of storage sections, and the culture system has a first float valve that can open and close the supply pipe, and the first float constituting the first float valve moves upward in the depth direction as the liquid level of the culture solution rises along the depth direction of the storage section, thereby blocking the supply pipe. [Effects of the Invention]

[0010] According to the present invention, the first float moves upward and blocks the supply pipe, automatically stopping the supply of culture medium to the storage section. Therefore, the culture system does not require a water level sensor to detect the culture medium level. This allows for reduced capital investment. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a culture system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing a state in which all of the multiple storage units that make up the culture tank are empty. [Figure 3] FIG. 3 is a schematic diagram showing a state in which the supply of culture medium to the storage section has started from the state shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing a state in which the supply of the culture medium has been completed in the most upstream storage section from the state shown in FIG. [Figure 5] FIG. 5 is a schematic diagram showing a state where recovery of the culture medium in the storage section has started from the state shown in FIG. [Figure 6] FIG. 6 is a schematic diagram showing a state after the state shown in FIG. 5 where collection of the culture medium has been completed in the most upstream storage section. [Figure 7] FIG. 7 is a schematic diagram of a culture system in which a plurality of containers are directly connected to one liquid transfer device. DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 is a schematic configuration diagram of a culture system 10 according to this embodiment. In this case, the culture system 10 includes a culture tank 20, a supply device 30, and a recovery device 60. The culture tank 20 has a plurality of storage units 22. Three storage units 22 are shown in FIG. 1 as representative examples. In the following description, to easily distinguish between the three storage units 22, the storage unit 22 located at the leftmost position in FIG. 1 will be referred to as the first storage unit 22a. The storage unit 22 located in the center in FIG. 1 will be referred to as the second storage unit 22b, and the storage unit 22 located at the rightmost position in FIG. 1 will be referred to as the third storage unit 22c.

[0013] However, the configuration shown in Fig. 1 is merely an example. The number of accommodating units 22 may be four or more. That is, one or more additional accommodating units 22 may be provided on the right side in Fig. 1. Alternatively, the culture tank 20 may be configured with two units, the first accommodating unit 22a and the second accommodating unit 22b. However, in the following, to simplify the explanation and make it easier to understand, only the first accommodating unit 22a to the third accommodating unit 22c will be explained.

[0014] Each of the first to third storage sections 22a to 22c is made of a flexible material. A typical example of a flexible material is linear low-density polyethylene (LLDPE). Each of the first to third storage sections 22a to 22c is, for example, bag-shaped. The first to third storage sections 22a to 22c are held by a holding frame (not shown) at a predetermined installation location. Note that if the recovery device 60 is not provided, the material of each of the first to third storage sections 22a to 22c does not have to be a flexible material. In this case, the material may be, for example, plastic or glass.

[0015] A direction from the bottom 24 to the top 26 of the storage section 22 , or the other way around is defined as the depth direction X. The depth direction X of the storage section 22 is, for example, approximately the same as the direction of gravity. In this case, the inclination angle of the depth direction X of the storage section 22 with respect to the direction of gravity is approximately zero. That is, the storage section 22 is in an upright position. The depth direction X of the storage section 22 may intersect with the direction of gravity at a predetermined angle. In this case, the storage section 22 is in an inclined position.

[0016] In a typical example, the volumes of the first to third storage sections 22a to 22c are approximately equal to one another. The depth directions X of the first to third storage sections 22a to 22c are the same. However, the volumes of the first to third storage sections 22a to 22c may be different from one another, and the depth directions X of the first to third storage sections 22a to 22c may also be different from one another.

[0017] The supply device 30 includes a storage tank 32, an outgoing pipe 33, a bidirectional flow pipe 44, a liquid delivery device 34, a base pipe 36, and a supply pipe 38. A culture solution L is stored in the storage tank 32. A typical example of the culture solution L is water. The culture solution L may contain nutrients such as nitrogen, phosphorus, and potassium.

[0018] In this embodiment, the liquid delivery device 34 is composed of a bidirectional pump 40. As will be described later, the bidirectional pump 40 serves both as the liquid delivery device 34 constituting the supply device 30 and as a suction device 62 constituting the recovery device 60.

[0019] One end of the outward pipe 33 is connected to the bottom of the storage tank 32. The other end of the outward pipe 33 is connected to the bidirectional pump 40 via the bidirectional flow pipe 44. One end of the return pipe 64 is connected to a connection point P between the bidirectional flow pipe 44 and the outward pipe 33. In other words, the outward pipe 33 and the return pipe 64 branch off at one end of the bidirectional flow pipe 44. The other end of the return pipe 64 is routed to the upper part of the storage tank 32 and connected to the storage tank 32 at that upper part. A supply valve 46 is provided in the outward pipe 33. A recovery valve 66 is provided in the return pipe 64.

[0020] One end of the connecting pipe 36 is connected to the liquid transfer device 34. The other end of the connecting pipe 36 extends toward the culture tank 20. The supply pipes 38 branch off from the connecting pipe 36 and extend toward each of the first to third accommodation units 22a to 22c. In the following description, the supply pipe 38 extending from the connecting pipe 36 toward the first accommodation unit 22a will be referred to as the first supply pipe 38a. The supply pipe 38 extending from the connecting pipe 36 toward the second accommodation unit 22b will be referred to as the second supply pipe 38b, and the supply pipe 38 extending from the connecting pipe 36 toward the third accommodation unit 22c will be referred to as the third supply pipe 38c.

[0021] The first supply pipe 38a branches off from the main pipe 36 and is inserted into the first storage section 22a from the top 26. The second supply pipe 38b branches off from the main pipe 36 at a location different from that of the first supply pipe 38a and is inserted into the second storage section 22b from the top 26. The third supply pipe 38c branches off from the main pipe 36 at a location different from that of the first supply pipe 38a and the second supply pipe 38b and is inserted into the third storage section 22c from the top 26.

[0022] When the culture solution L is supplied from the storage tank 32 to the culture tank 20, the direction of flow of the culture solution L in the connecting pipe 36 is the direction of arrow A in FIG. 1. Therefore, the first to third containers 22a to 22c are arranged from upstream to downstream in the flow direction of the culture solution L in the connecting pipe 36 when the culture solution L is supplied. That is, the first container 22a is located at the most upstream position, the third container 22c is located at the most downstream position, and the second container 22b is located at the midstream position. Hereinafter, a configuration in which the first container 22a to the third container 22c are arranged from upstream to downstream in the flow direction of the culture solution L and connected to the connecting pipe 36 in sequence is sometimes referred to as a "serial arrangement."

[0023] Each of the first supply pipe 38a to the third supply pipe 38c is provided with a first float valve 48. The first float valve 48 has a first float 50 and a first valve seat 52. The specific gravity of the first float 50 is smaller than that of the culture solution L. When the culture solution L is water, the specific gravity of the first float 50 is smaller than that of water. Therefore, when the culture solution L is contained in the first storage section 22a to the third storage section 22c, the first float 50 is located at the liquid surface of the culture solution L. When the first float 50 reaches its highest position, it abuts against the first valve seat 52. This abutment causes the first float valve 48 to be in a closed state. Accordingly, each of the first supply pipe 38a to the third supply pipe 38c is closed by the first float valve 48.

[0024] In contrast, the first float valve 48 is in an open state when the first float 50 is separated from the first valve seat 52. In this case, the culture solution L can flow through the first supply pipe 38a to the third supply pipe 38c.

[0025] The first float valve 48, which opens and closes as described above, functions as a check valve. Specifically, the first float valve 48 allows the culture solution L to flow from the main pipe 36 toward the first storage section 22a in the first supply pipe 38a. On the other hand, the first float valve 48 prevents the culture solution L from flowing from the first storage section 22a toward the main pipe 36 in the first supply pipe 38a. The same applies to the first float valve 48 provided in the second supply pipe 38b and the first float valve 48 provided in the third supply pipe 38c.

[0026] The recovery device 60 has a recovery pipe 68, a main pipe 36, a suction device 62, a bidirectional flow pipe 44, a return pipe 64, and a storage tank 32. As described above, the suction device 62 is composed of the bidirectional pump 40 and also serves as the liquid delivery device 34 that constitutes the supply device 30. Therefore, the main pipe 36, the suction device 62 (bidirectional pump 40), and the storage tank 32 constitute both the supply device 30 and the recovery device 60. Note that the supply device 30 and the recovery device 60 may be separate devices independent of each other. In this case, for example, the liquid delivery device 34 can be composed of a one-way pump, and the suction device 62 can be composed of another one-way pump.

[0027] The recovery pipe 68 branches off from each of the first supply pipe 38a to the third supply pipe 38c. Hereinafter, the recovery pipe 68 branching off from the first supply pipe 38a will be referred to as the first recovery pipe 68a. Similarly, the recovery pipe 68 branching off from the second supply pipe 38b will be referred to as the second recovery pipe 68b, and the recovery pipe 68 branching off from the third supply pipe 38c will be referred to as the third recovery pipe 68c. The first recovery pipe 68a is routed so as to bypass the first float valve 48 and merges with the first supply pipe 38a. The second recovery pipe 68b and the third recovery pipe 68c are similarly routed so as to bypass the first float valve 48 and merge with the second supply pipe 38b and the third supply pipe 38c, respectively.

[0028] It is not necessary for the first recovery pipe 68a to the third recovery pipe 68c to branch off from the first supply pipe 38a to the third supply pipe 38c, respectively. The first supply pipe 38a to the third supply pipe 38c and the first recovery pipe 68a to the third recovery pipe 68c may be separate pipes that are connected to the main pipe 36 independently of each other.

[0029] Each of the first recovery pipe 68a to the third recovery pipe 68c is provided with a second float valve 70. The second float valve 70 has a second float 72 and a second valve seat 74. The second float 72 is positioned above (at a higher position than) the first float 50. When the first float 50 is at its highest position and the first supply pipe 38a to the third supply pipe 38c are blocked, the second float 72 is positioned above the liquid surface of the culture solution L while abutting against the second valve seat 74. In this case, the second float valve 70 is in a closed state.

[0030] When the culture solution L in the first to third storage sections 22a to 22c is sucked by the suction device 62 (bidirectional pump 40), the second float 72 moves away from the second valve seat 74. In this case, the second float valve 70 is in an open state.

[0031] The second float valve 70, which opens and closes as described above, functions as a check valve. Specifically, the second float valve 70 prevents the culture solution L from flowing from the main pipe 36 toward the first storage section 22a in the first recovery pipe 68a. On the other hand, the second float valve 70 allows the culture solution L to flow from the first storage section 22a toward the main pipe 36 in the first recovery pipe 68a. The same applies to the second float valve 70 provided in the second recovery pipe 68b and the second float valve 70 provided in the third supply pipe 38c.

[0032] Portions of the first supply pipe 38a and the first recovery pipe 68a are exposed from the first storage portion 22a. Similarly, portions of the second supply pipe 38b and the second recovery pipe 68b are exposed from the second storage portion 22b, and portions of the third supply pipe 38c and the third recovery pipe 68c are exposed from the third storage portion 22c. It is not essential to seal the tops 26 of the first storage portion 22a to the third storage portion 22c, but they may be sealed.

[0033] The culture system 10 further includes a control unit 80. The control unit 80 is configured by a processor such as a CPU (Central Processing Unit). That is, the control unit 80 is configured by processing circuitry. The control unit 80 is electrically connected to the supply valve 46, the recovery valve 66, and the bidirectional pump 40.

[0034] The control unit 80 includes a setting unit 82, a timer unit 84, and a comparison unit 86. The setting unit 82 is set with a required time from when the supply of the culture solution L to the empty first to third storage units 22a to 22c begins until all of the first float valves 48 provided on the first to third supply pipes 38a to 38c are closed. The required time can be obtained by conducting a preliminary test. The setting unit 82 also is set with a pressure threshold value related to the discharge pressure of the bidirectional pump 40.

[0035] The timer unit 84 measures the actual elapsed time since the supply of the culture solution L to the empty first to third storage units 22a to 22c started. The comparison unit 86 compares this actual elapsed time with the required time set in the setting unit 82. Alternatively, the comparison unit 86 acquires information on the actual discharge pressure of the bidirectional pump 40 and compares this actual discharge pressure with the pressure threshold set in the setting unit 82.

[0036] The culture system 10 according to this embodiment is basically configured as described above. Next, the operation of the culture system 10 when the culture solution L is supplied to the culture tank 20 will be described.

[0037] FIG. 2 is a schematic diagram showing a state before the culture solution L is supplied to the culture tank 20. FIG. 2 shows a case where the bidirectional pump 40 is stopped and the supply valve 46 and the recovery valve 66 are closed. In this state, the culture solution L in the storage tank 32 is prevented from flowing through the bidirectional flow pipe 44. Therefore, the culture solution L is also prevented from being supplied from the storage tank 32 to the first to third storage units 22a to 22c. Therefore, the first to third storage units 22a to 22c are empty. In each of the first to third storage units 22a to 22c, the first float valve 48 is in an open state with the first float 50 separated from the first valve seat 52, and the second float valve 70 is in a closed state with the second float 72 abutting against the second valve seat 74. The second float 72 descends due to gravity and abuts against the second valve seat 74.

[0038] When supplying the culture solution L from the storage tank 32 to the first to third storage units 22a to 22c, the operator instructs the control unit 80 via an input device (not shown) to "start supplying the culture solution L to the first to third storage units 22a to 22c." For example, the operator turns on the supply start switch. This causes the control unit 80 to open the supply valve 46 and drive the bidirectional pump 40. In this case, the bidirectional pump 40 functions as the liquid delivery device 34 and delivers the culture solution L from the bidirectional flow pipe 44 to the connecting pipe 36. As a result, the culture solution L passes through the outgoing pipe 33, the bidirectional flow pipe 44, and the bidirectional pump 40 and flows into the connecting pipe 36. A timer unit 84 in the control unit 80 starts measuring the actual elapsed time since the start of liquid delivery.

[0039] When the culture solution L flows along the connecting pipe 36 in the direction of arrow A shown in Figures 1 and 2, a portion of the culture solution L flows into the first supply pipe 38a. Because the first float valve 48 provided in the first supply pipe 38a is in an open state, the culture solution L passes through the first float valve 48 and is discharged into the first storage section 22a, as shown in Figure 3. Because the second float valve 70 is in a closed state, the culture solution L is prevented from being supplied to the first storage section 22a via the first recovery pipe 68a.

[0040] A portion of the culture solution L that does not flow into first supply pipe 38a and continues to flow in the direction of arrow A within connecting pipe 36 flows into second supply pipe 38b. Because first float valve 48 provided in second supply pipe 38b is in an open state, the culture solution L passes through first float valve 48 and is discharged into second storage section 22b. Because second float valve 70 is in a closed state, the culture solution L is prevented from being supplied to second storage section 22b via second recovery pipe 68b.

[0041] A portion of the culture solution L that does not flow into second supply pipe 38b but continues to flow through connecting pipe 36 in the direction of arrow A flows into third supply pipe 38c. Because first float valve 48 provided in third supply pipe 38c is in an open state, the culture solution L passes through first float valve 48 and is discharged into third storage section 22c. Because second float valve 70 is in a closed state, the culture solution L is prevented from being supplied to third storage section 22c via third recovery pipe 68c.

[0042] In this embodiment, the first to third storage units 22a to 22c are arranged in series in this order from upstream to downstream in the flow direction of the culture solution L (the direction of arrow A). When all of the first float valves 48 are open, the culture solution L is supplied preferentially to the first storage unit 22a located at the most upstream position, the second storage unit 22b located at the midstream position, and the third storage unit 22c located at the most downstream position. That is, the inflow rate of the culture solution L per unit time into the first storage unit 22a is greater than the inflow rate of the culture solution L per unit time into the second storage unit 22b. The inflow rate of the culture solution L per unit time into the second storage unit 22b is greater than the inflow rate of the culture solution L per unit time into the third storage unit 22c.

[0043] For the reasons described above, the liquid level of the culture solution L rises in the first storage section 22a before it rises in the second storage section 22b, as shown in Figures 3 and 4. Similarly, the liquid level of the culture solution L rises in the second storage section 22b before it rises in the third storage section 22c.

[0044] 4, the first float 50 of the first float valve 48 of the first storage section 22a rises and seats on the first valve seat 52 in a shorter time than the first float valve 48 of the second storage section 22b and the first float valve 48 of the third storage section 22c. That is, the first float valve 48 of the first storage section 22a is closed. Accordingly, the supply of the culture solution L to the first storage section 22a is stopped. In contrast, the first float valve 48 of the second storage section 22b and the first float valve 48 of the third storage section 22c are still open. Therefore, the supply of the culture solution L to the second storage section 22b and the third storage section 22c continues.

[0045] For the reasons described above, the liquid level of the culture solution L rises in the second storage section 22b before it rises in the third storage section 22c. Therefore, the first float valve 48 in the second storage section 22b closes in a shorter time than the first float valve 48 in the third storage section 22c. As a result, the supply of the culture solution L to the second storage section 22b is stopped. However, because the first float valve 48 in the third storage section 22c is still open, the supply of the culture solution L to the third storage section 22c continues.

[0046] Next, the liquid level of the culture solution L rises in the third storage section 22c, and the first float valve 48 closes. As a result, the supply of the culture solution L to the third storage section 22c stops, resulting in the state shown in Figure 1. As a result, the first supply pipe 38a to the third supply pipe 38c switch from an open state to a closed state.

[0047] In the first to third storage units 22a to 22c, the second float valves 70 are positioned above (higher than) the first float valves 48. Therefore, when the culture solution L is supplied to the first to third storage units 22a to 22c, all of the second float valves 70 remain closed. This prevents the culture solution L from being supplied to the first to third storage units 22a to 22c via the first to third recovery pipes 68a to 68c.

[0048] In the preliminary test, the time required from the start of supply of the culture solution L to the culture tank 20 until the first float valve 48 of the third storage section 22c is closed is actually measured. This required time is set in advance in the setting section 82. The comparison section 86 compares the required time set in the setting section 82 with the actual elapsed time measured by the timer section 84. When the required time and the actual elapsed time match, the control section 80 determines that "a predetermined amount of the culture solution L has been stored in each of the first storage section 22a to the third storage section 22c." Next, the control section 80 stops the bidirectional pump 40.

[0049] Here, after all of the first float valves 48 are closed, the actual discharge pressure of the bidirectional pump 40 increases. The comparing unit 86 may compare the actual discharge pressure of the bidirectional pump 40 with a pressure threshold set in the setting unit 82. When the actual discharge pressure reaches the pressure threshold, the control unit 80 determines that "a predetermined amount of culture solution L has been accommodated in each of the first to third accommodation units 22a to 22c." Next, the control unit 80 stops the bidirectional pump 40.

[0050] The comparison of the required time with the actual elapsed time and the comparison of the pressure threshold with the actual discharge pressure may be performed simultaneously. In this case, the control unit 80 stops the bidirectional pump 40 when either the actual elapsed time matches the required time or the actual discharge pressure reaches the pressure threshold. By promptly stopping the bidirectional pump 40 after the supply of the culture solution L to the culture tank 20 has ended in this manner, excessive load on the bidirectional pump 40 is avoided. In addition, the control unit 80 switches the supply valve 46 to a closed state.

[0051] After the culture solution L is placed in the culture tank 20, microalgae are cultured in the culture tank 20. Although not particularly shown, gas is supplied to the culture tank 20 during the culture, and the culture tank 20 is irradiated with light.

[0052] After the cultivation of the microalgae is completed, the culture solution L containing the microalgae is recovered from the culture tank 20 as follows. First, in the state shown in FIG. 1, the operator instructs the control unit 80 via an input device to "start recovery of the culture solution L from the first storage unit 22a to the third storage unit 22c." For example, the operator turns on the recovery start switch. This causes the control unit 80 to open the recovery valve 66 and drive the bidirectional pump 40. In this case, the bidirectional pump 40 functions as the suction device 62 and sucks the culture solution L via the first supply pipe 38a to the third supply pipe 38c.

[0053] In each of the first supply pipe 38a to the third supply pipe 38c, the first float 50 of the first float valve 48 has already risen and is in contact with the first valve seat 52. The direction of suction of the culture solution L from the culture tank 20 is the direction that raises the first float 50. Therefore, while the culture solution L is being suctioned from the culture tank 20, the first float 50 remains in contact with the first valve seat 52 as shown in FIG. 5. That is, the first float valve 48 remains closed. Therefore, the culture solution L is prevented from passing through the first float valve 48.

[0054] On the other hand, the direction of suction of culture solution L from culture tank 20 is a direction that raises second float 72 from second valve seat 74. Therefore, in each of first recovery pipe 68a to third recovery pipe 68c, second float 72 moves away from second valve seat 74 as shown in FIG. 5, and second float valve 70 enters an open state. Accordingly, first recovery pipe 68a to third recovery pipe 68c switch from a closed state to an open state. As a result, the interiors of first storage section 22a to third storage section 22c and connecting pipe 36 are connected via first recovery pipe 68a to third recovery pipe 68c, respectively.

[0055] Therefore, the culture solution L in the first storage section 22a to the third storage section 22c is sucked in. The culture solution L flows through the connecting pipe 36 along the arrow B in Figure 5, then passes through the two-way flow pipe 44 and the return pipe 64 and flows into the storage tank 32. As a result, the culture solution L containing the microalgae is collected in the storage tank 32.

[0056] Of the first to third storage sections 22a to 22c arranged in series, the first storage section 22a is closest to the bidirectional pump 40. Therefore, when all of the first float valves 48 are closed, the culture solution L is preferentially aspirated from the first storage section 22a, the second storage section 22b, and the third storage section 22c in that order. That is, the amount of culture solution L aspirated per unit time in the first storage section 22a is greater than the amount of culture solution L aspirated per unit time in the second storage section 22b. The amount of culture solution L aspirated per unit time in the second storage section 22b is greater than the amount of culture solution L aspirated per unit time in the third storage section 22c.

[0057] For the reasons described above, as shown in Figures 5 and 6, the first accommodating section 22a finishes suction of the culture solution L before the second accommodating section 22b finishes suction of the culture solution L. Similarly, the second accommodating section 22b finishes suction of the culture solution L before the third accommodating section 22c finishes suction of the culture solution L.

[0058] As described above, in this embodiment, the material of the first to third storage sections 22a to 22c is flexible. Therefore, as the collection of the culture solution L from the first to third storage sections 22a to 22c progresses, the first to third storage sections 22a to 22c are pressed by the atmosphere and collapse. That is, the first to third storage sections 22a to 22c contract. Therefore, for example, as shown in FIG. 6, when the suction of the culture solution L in the first storage section 22a is completed, the inside of the first storage section 22a is in a vacuum state (negative pressure). Furthermore, all of the first float valves 48 remain closed. For the above reasons, even if all of the second float valves 70 remain open, the culture solution L is prevented from returning from the first to third recovery pipes 68a to 68c to the first to third storage sections 22a to 22c.

[0059] In this situation, the culture solution L remaining in the second storage section 22b is then collected preferentially over the culture solution L remaining in the third storage section 22c. When the suction of the culture solution L in the second storage section 22b is completed, the inside of the second storage section 22b is in a vacuum state. Therefore, with the second float valve 70 in the second recovery pipe 68b remaining open, the second storage section 22b is pushed by the atmosphere and assumes a collapsed (contracted) shape.

[0060] In this state, the culture solution L remaining in the third storage section 22c is recovered. When the suction of the culture solution L into the third storage section 22c is completed, the inside of the third storage section 22c is in a vacuum state. Therefore, with the second float valve 70 in the third recovery pipe 68c remaining open, the second storage section 22b is pushed by the atmosphere and assumes a collapsed (contracted) shape. This completes the recovery of the culture solution L from the culture tank 20.

[0061] In the preliminary test, the time required from the start of collection of the culture solution L from the culture tank 20 until the third storage section 22c is in a vacuum state may be measured and set in the setting section 82. In this case, the comparison section 86 compares the required time set in the setting section 82 with the actual elapsed time since collection of the culture solution L from the culture tank 20 was started. When the required time and the actual elapsed time match, the control section 80 determines that "collection of the culture solution L from the first storage section 22a to the third storage section 22c has been completed." Next, the control section 80 stops the bidirectional pump 40.

[0062] Furthermore, a pressure threshold value related to the suction pressure of the bidirectional pump 40 may be set in the setting unit 82. In this case, the comparison unit 86 compares the pressure threshold value set in the setting unit 82 with the actual suction pressure of the bidirectional pump 40. When the actual suction pressure reaches the pressure threshold value, the control unit 80 determines that "recovery of the culture solution L from the first to third storage units 22a to 22c has been completed." Next, the control unit 80 stops the bidirectional pump 40.

[0063] The comparison of the required time with the actual elapsed time and the comparison of the pressure threshold with the actual suction pressure may be performed simultaneously. In this case, the control unit 80 stops the bidirectional pump 40 when either the actual elapsed time matches the required time or the actual suction pressure reaches the pressure threshold. By promptly stopping the bidirectional pump 40 after the culture solution L has been collected into the storage tank 32 in this manner, excessive load on the bidirectional pump 40 is avoided. The control unit 80 also switches the collection valve 66 to a closed state.

[0064] The culture system 10 according to this embodiment has the following advantages.

[0065] The culture system 10 includes a culture tank 20 for culturing microalgae, and a supply device 30 for supplying a culture solution L to the culture tank 20. The culture tank 20 has a plurality of storage sections 22 capable of storing the culture solution L.

[0066] The supply device 30 includes a liquid delivery device 34 that delivers the culture solution L to the plurality of storage units 22, and a supply pipe 38 that supplies the culture solution L delivered from the liquid delivery device 34 to each of the plurality of storage units 22. The culture system 10 includes a first float valve 48 that can open and close the supply pipe 38. A first float 50 constituting the first float valve 48 moves upward in the depth direction X as the liquid level of the culture solution L rises along the depth direction X of the storage unit 22. The first float 50 that has moved upward comes into contact with a first valve seat 52, causing the first float valve 48 to close the supply pipe 38.

[0067] As described above, when the culture solution L is supplied to each of the plurality of storage units 22, the first float 50 moves upward as the liquid level of the culture solution L rises. The first float 50, which has moved upward, blocks the supply pipe 38, thereby stopping the supply of the culture solution L to the storage units 22. In this way, with the above configuration, the supply of the culture solution L to the storage units 22 can be automatically stopped without providing a water level sensor that detects the liquid level of the culture solution L. In other words, a water level sensor is not required in the culture system 10. This allows for reduced capital investment.

[0068] The liquid supply device 34 also serves as a suction device 62 that can collect the culture solution L containing microalgae from the multiple storage units 22. In this case, the configuration is simpler than in a culture system that is individually equipped with the liquid supply device 34 and the suction device 62.

[0069] Here, each of the multiple storage sections 22 is made of a flexible material. The culture system 10 has a recovery pipe 68 and a second float valve 70 that can close the recovery pipe 68. The second float 72 that constitutes the second float valve 70 is located above the first float 50 in the depth direction X.

[0070] In this configuration, when the suction device 62 is operated, the culture solution L flows from the storage unit 22 into the recovery pipe 68. The culture solution L pushes the second float 72 upward, causing the second float 72 to move away from the second valve seat 74 and open the second float valve 70. Therefore, the culture solution L flows through the recovery pipe 68 and moves to the storage tank 32. Because the storage unit 22 is made of a flexible material, the culture solution L is recovered from the storage unit 22, creating a negative pressure inside the storage unit 22, causing the storage unit 22 to contract. This negative pressure keeps the first float valve 48 closed. Therefore, the culture solution L that has flowed into the recovery pipe 68 is prevented from returning to the storage unit 22 via the supply pipe 38.

[0071] Furthermore, since the second float valve 70 is kept open by the negative pressure, the culture solution L can be easily collected from all of the storage sections 22.

[0072] The supply device 30 has a main pipe 36 connected to a liquid delivery device 34. Supply pipes 38 branch off from the main pipe 36 and extend toward each of the plurality of storage sections 22.

[0073] With this configuration, the culture solution L can be supplied to all of the storage units 22 using one liquid delivery device 34. In an embodiment in which the liquid delivery device 34 also functions as the suction device 62, the culture solution L can also be collected from all of the storage units 22 using one liquid delivery device 34 (suction device 62). With this configuration, capital investment is lower than in a configuration in which the liquid delivery device 34 and the suction device 62 are individually connected to each of the multiple storage units 22.

[0074] The plurality of storage units 22 are aligned from upstream to downstream in the flow direction (direction of arrow A) of the culture solution L in the connecting pipe 36 when the culture solution L is supplied to the storage units 22. As the flow direction of the culture solution L in the connecting pipe 36 moves from upstream to downstream in the flow direction (direction of arrow A) of the culture solution L, the supply pipes 38 (first supply pipe 38a to third supply pipe 38c) connecting the connecting pipe 36 to each of the plurality of storage units 22 branch out individually.

[0075] When multiple storage units 22 are arranged in series as described above, a storage unit 22 located relatively upstream tends to receive a larger amount of culture solution L per unit time than a storage unit 22 located relatively downstream. Therefore, a storage unit 22 located relatively upstream finishes storing a predetermined amount of culture solution L before a storage unit 22 located relatively downstream finishes storing the predetermined amount of culture solution L. Thereafter, a storage unit 22 located relatively downstream finishes storing the predetermined amount of culture solution L.

[0076] As shown in FIG. 7, in the case of a parallel arrangement in which multiple storage units 22 are directly connected to one liquid delivery device 34 via supply pipes 38, a large discharge pressure (supply pressure) is required because the culture solution L is simultaneously supplied from one liquid delivery device 34 to each of the multiple storage units 22. Therefore, in this case, a large liquid delivery device 34 must be used. In contrast, in the serial arrangement shown in FIGS. 1 to 6, the culture solution L is sequentially supplied from the storage unit 22 located upstream (first storage unit 22a) to the storage unit 22 located downstream (third storage unit 22c) as described above, so there is no need to use a large liquid delivery device 34. This makes it possible to reduce capital investment. However, the present invention also includes the embodiment shown in FIG. 7.

[0077] 7, the number of bidirectional pumps 40 is one. However, the number of bidirectional pumps 40 may be the same as the number of storage portions 22.

[0078] The culture system 10 includes a control unit 80. When the first float 50 blocks the supply pipe 38 and the culture solution L contained in each of the plurality of storage units 22 reaches a predetermined amount, the control unit 80 stops the liquid delivery device 34 if it determines that the predetermined amount of culture solution L has been contained in all of the plurality of storage units 22.

[0079] In this way, when the control unit 80 determines that all of the first float valves 48 are in the closed state, it stops the liquid delivery device 34. This prevents excessive load from being applied to the liquid delivery device 34.

[0080] The setting unit 82 of the control unit 80 presets, for example, the time required from when the supply of the culture solution L by the liquid delivery device 34 starts until a predetermined amount of the culture solution L is stored in all of the plurality of storage units 22. The comparison unit 86 of the control unit 80 stops the liquid delivery device 34 when the actual elapsed time from when the supply of the culture solution L by the liquid delivery device 34 starts matches the required time.

[0081] Alternatively, the control unit 80 acquires information on the actual discharge pressure of the culture solution L in the liquid delivery device 34. The control unit 80 stops the liquid delivery device 34 when the actual discharge pressure increases to a pressure threshold value set in advance in the setting unit 82.

[0082] By using either or both of the above, it is possible to set the timing to stop the liquid delivery device 34 without using a water level sensor. Since a water level sensor is not required, it is possible to reduce the capital investment required for the culture system 10.

[0083] The volumes of the plurality of accommodating sections 22 are substantially the same. The first floats 50 are arranged at the same positions in the depth direction X of the plurality of accommodating sections 22.

[0084] This configuration makes it possible to supply approximately the same amount of culture solution L to each of the plurality of storage sections 22. Therefore, it is possible to make the amount of culture solution L stored in the plurality of storage sections 22 uniform.

[0085] In addition to the above disclosure, the following additional notes are disclosed.

[0086] (Appendix 1) The culture system 10 includes a culture tank 20 for culturing microalgae and a supply device 30 for supplying a culture solution L to the culture tank. The culture tank has a plurality of storage sections 22 capable of storing the culture solution.

[0087] The supply device includes a liquid delivery device (34) that delivers the culture solution to the plurality of storage units, and a supply pipe (38) that supplies the culture solution delivered from the liquid delivery device to each of the plurality of storage units. The culture system includes a first float valve (48) that can open and close the supply pipe. A first float (50) constituting the first float valve moves upward in the depth direction (X) of the storage unit as the liquid level of the culture solution rises along the depth direction. Based on this movement, the first float valve closes the supply pipe.

[0088] The above-mentioned blockage stops the supply of culture medium to the storage section. In this way, with the above-mentioned configuration, the supply of culture medium can be automatically stopped. Therefore, a water level sensor for detecting the liquid level of the culture medium is not required. This allows for reduced capital investment.

[0089] (Appendix 2) In the culture system described in Appendix 1, the liquid delivery device may also serve as a suction device (62) capable of recovering the culture solution from the plurality of storage units. Each of the plurality of storage units may be made of a flexible material. The culture system may include a recovery pipe (68) and a second float valve (70) capable of closing the recovery pipe, and a second float (72) constituting the second float valve may be located above the first float in the depth direction.

[0090] Since the liquid delivery device also functions as a suction device, the configuration is simpler than when the culture system is provided with a liquid delivery device and a suction device separately.

[0091] Furthermore, when the suction device is activated, the second float is pushed up by the culture medium flowing from the storage section into the recovery pipe. As a result, the second float valve opens. Because the storage section is made of a flexible material, the culture medium is extracted from the storage section, creating a negative pressure inside the storage section, causing the storage section to contract. This negative pressure keeps the first float valve closed, preventing the culture medium from returning to the storage section via the supply pipe. Moreover, because the negative pressure keeps the second float valve open, it is easy to recover the culture medium from all of the storage sections.

[0092] (Appendix 3) In the culture system described in Appendix 1 or 2, the supply device may have a connecting pipe (36) connected to the liquid delivery device, and the supply pipe may branch off from the connecting pipe and extend toward each of the multiple storage sections.

[0093] With this configuration, a single liquid delivery device can be used to supply the culture medium to all of the storage units. If the liquid delivery device also functions as a suction device, a single liquid delivery device can be used to collect the culture medium from all of the storage units. In this case, capital investment is lower than in a configuration in which a liquid delivery device and a suction device are connected to each of the multiple storage units.

[0094] (Appendix 4) In the culture system described in Appendix 3, the plurality of storage sections may be arranged along the upstream to downstream direction of the flow direction of the culture medium in the connecting pipe, and the supply pipe connecting the connecting pipe to each of the plurality of storage sections may branch out individually as the supply pipe moves from upstream to downstream in the flow direction of the connecting pipe.

[0095] When multiple storage units are individually connected to one liquid delivery device, the liquid delivery device must output a large supply pressure (discharge pressure). Therefore, in this case, a large liquid delivery device must be used. In contrast, in the above-described arrangement (serial arrangement), the culture medium is sequentially supplied from the storage unit located upstream to the storage unit located downstream, so a large liquid delivery device is not required. This allows for lower capital investment.

[0096] (Appendix 5) In the culture system described in any one of Appendices 1 to 4, the culture system includes a control unit (80), and when the first float blocks the supply pipe and the culture solution contained in each of the plurality of storage units is a predetermined amount, the control unit may stop the liquid delivery device when it determines that the predetermined amount of culture solution has been contained in all of the plurality of storage units.

[0097] When the control unit determines that all of the first float valves are in the closed state, the liquid delivery device is stopped, thereby preventing excessive load from being applied to the liquid delivery device.

[0098] (Appendix 6) In the culture system described in Appendix 5, the control unit may be configured to preset a required time from when the liquid delivery device starts supplying the culture medium until the predetermined amount of the culture medium is stored in all of the plurality of storage units, and the control unit may stop the liquid delivery device when the actual elapsed time from when the liquid delivery device starts supplying the culture medium matches the required time.

[0099] This configuration makes it possible to set the timing for stopping the liquid delivery device without using a water level sensor, which reduces capital investment.

[0100] (Appendix 7) In the culture system described in Appendix 5 or 6, the control unit may acquire information on the supply pressure of the culture medium in the liquid delivery device, and stop the liquid delivery device when the supply pressure rises to a pressure threshold value.

[0101] In this case, the water level sensor is not required, as in the case above, and therefore the investment in equipment can be reduced.

[0102] (Appendix 8) In the culture system described in any one of Appendices 1 to 7, the volumes of the multiple storage sections may be approximately the same, and the first floats may be arranged at the same positions in the depth direction of the multiple storage sections.

[0103] This configuration allows the supply of approximately the same amount of culture medium to each of the plurality of storage units, in other words, it is possible to make the amount of culture medium stored in the plurality of storage units uniform.

[0104] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0105] 10...Cultivation system 20...Cultivation tank 22, 22a to 22c... Storage section 30... Supply device 32...Storage tank 33...Outlet pipe 34...liquid delivery device 36...main pipe 38, 38a to 38c... Supply pipe 40... Two-way pump 44... Two-way flow pipe 46... Supply valve 48...First float valve 50...First float 52...first valve seat 60...recovery device 62...Suction device 64...Return pipe 66... ​​Recovery valve 68, 68a to 68c... Recovery pipes 70...Second float valve 72...Second float 74... Second valve seat 80... Control section 82...Setting section 84...Timer section 86...Comparison section L...Culture solution

Claims

1. A culture system comprising a culture tank for culturing microalgae and a supply device for supplying a culture solution to the culture tank, The culture tank has a plurality of storage sections capable of storing the culture solution, the supply device includes a liquid delivery device that delivers the culture solution to the plurality of storage units, and a supply pipe that supplies the culture solution delivered from the liquid delivery device to each of the plurality of storage units, the culture system includes a first float valve capable of opening and closing the supply pipe, a recovery pipe for recovering the culture solution from each of the plurality of storage units, and a second float valve capable of closing the recovery pipe; a first float constituting the first float valve moves upward in the depth direction as the liquid level of the culture solution rises along the depth direction of the storage section, thereby closing the supply pipe; the liquid delivery device also serves as a suction device capable of recovering the culture solution in the plurality of storage units through the recovery pipe; A culture system, wherein a second float constituting the second float valve is positioned higher than the first float in the depth direction.

2. 2. The culture system according to claim 1, wherein each of the plurality of containers is made of a flexible material.

3. 3. A culture system according to claim 1, wherein the supply device has a connecting pipe connected to the liquid delivery device, and the supply pipe branches off from the connecting pipe and extends toward each of the plurality of storage sections.

4. 4. The culture system according to claim 3, wherein the plurality of storage sections are arranged along the upstream to downstream direction of the flow direction of the culture solution in the connecting pipe, and the supply pipes connecting the connecting pipe and each of the plurality of storage sections branch out individually as they move from upstream to downstream in the flow direction in the connecting pipe.

5. 2. The culture system according to claim 1, further comprising a control unit, wherein when the first float blocks the supply pipe, the culture medium contained in each of the plurality of storage sections is a predetermined amount, and the control unit stops the liquid delivery device when it determines that the predetermined amount of culture medium has been contained in all of the plurality of storage sections.

6. 6. The culture system according to claim 5, wherein a required time from when the supply of the culture medium by the liquid delivery device starts until the predetermined amount of the culture medium is accommodated in all of the plurality of accommodation units is preset in the control unit, The control unit stops the liquid delivery device when an actual elapsed time since the liquid delivery device started to supply the culture medium matches the required time.

7. 6. The culture system according to claim 5, wherein the control unit acquires information on the supply pressure of the culture medium in the liquid delivery device, and stops the liquid delivery device when the supply pressure rises to a pressure threshold value.

8. 2. The culture system according to claim 1, wherein the volumes of the plurality of storage sections are substantially the same, and the first floats are arranged at the same positions in the depth direction of the plurality of storage sections.

Images