Estimation device and estimation method

Abstract

To provide an estimation device capable of performing estimation of algae concentration in a culture solution.SOLUTION: An estimation device (8) comprises a CO2 supply control mechanism (81) that controls supply of CO2 to a culture solution containing algae and stored in a vessel, a calculation unit (831) that calculates an amount of CO2 supplied by the CO2 supply control mechanism, and an estimation unit (832) that estimates a concentration of algae in the culture solution based on the CO2 supply amount calculated by the calculation unit.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an estimation device and an estimation method for estimating the concentration of algae in a culture solution. [Background technology]

[0002] Patent Document 1 discloses a tubular closed-system photobioreactor unit equipped with a series of devices necessary for culturing photosynthetic products such as microalgae. The photobioreactor unit includes a reactor made of a glass tube, a circulation tank that stores and circulates a culture solution containing algae in the reactor, and a pump that pressure-feeds the culture solution from the circulation tank to the reactor. The circulation tank is equipped with a carbon dioxide supply unit that supplies the carbon dioxide necessary for algae cultivation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7219841 Summary of the Invention [Problem to be solved by the invention]

[0004] In the photobioreactor unit disclosed in Patent Document 1, as the concentration of photosynthates in the culture solution increases, the amount of carbon dioxide consumed by photosynthesis increases, making carbon dioxide more likely to become insufficient. Therefore, it is desirable to know the concentration of photosynthates in the culture solution. However, providing a sensor for measuring the concentration of photosynthates in the photobioreactor unit increases the costs of manufacturing and maintaining the photobioreactor unit.

[0005] An object of one aspect of the present invention is to provide an estimation device or the like that can estimate the concentration of algae in a culture solution. [Means for solving the problem]

[0006] In order to solve the above problems, an estimation device according to one embodiment of the present invention includes a CO2 supply control mechanism that controls the supply of CO2 to a culture solution containing algae stored in a container, a calculation unit that calculates the amount of CO2 supplied by the CO2 supply control mechanism, and an estimation unit that estimates the concentration of the algae in the culture solution based on the amount of CO2 supplied calculated by the calculation unit.

[0007] Furthermore, an estimation method according to one aspect of the present invention includes a CO2 supply control step of controlling the supply of CO2 to a culture solution containing algae stored in a container, a calculation step of calculating the amount of CO2 supply in the CO2 supply control step, and an estimation step of estimating the concentration of the algae in the culture solution based on the amount of CO2 supply calculated in the calculation step. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to realize an estimation device or the like that can estimate the concentration of algae in a culture solution. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of an algae culture apparatus according to a first embodiment of the present invention. [Figure 2] 2 is a view of the part surrounded by dotted line A1 in the algae culture apparatus shown in FIG. 1, viewed from the positive direction of the Z axis. [Figure 3] 1 is a block diagram showing an example of a configuration of a main part of an estimation device according to a first embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing an example of control of CO2 supply to a culture solution by a CO2 supply control unit. [Figure 5] 10 is a graph showing an example of the correlation between CO2 supply time and OD value. [Figure 6] 3 is a flowchart showing an example of an estimation method executed by the estimation device according to the first embodiment of the present invention. [Figure 7] FIG. 10 is a block diagram showing an example of a configuration of a main part of an estimation device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Embodiment 1] Hereinafter, one embodiment of the present invention will be described in detail.

[0011] <Configuration of Algae Cultivation Device 1> FIG. 1 is a cross-sectional view showing an example of the configuration of an algae culture apparatus 1 according to a first embodiment of the present invention. In FIG. 1, the extension direction of the container 6 is the X-axis direction, the direction perpendicular to the ground on which the algae culture apparatus 1 is installed is the Z-axis direction, and the direction perpendicular to both the X-axis direction and the Z-axis direction is the Y-axis direction. The X-axis and Z-axis directions are also perpendicular to each other. The algae culture apparatus 1 is installed outdoors and is an apparatus for cultivating algae using a container 6. As shown in FIG. 1, the algae culture apparatus 1 includes a container 2, a control panel 3, a tank 4, a pump 5, a container 6, and an estimation device 8.

[0012] The container 2 is a storage unit that houses a control panel 3, a tank 4, and a pump 5. The control panel 3 stores a control unit 83 and a memory unit 84 of the estimation device 8, and controls each unit of the algae culture device 1. The control unit 83 and the memory unit 84 of the estimation device 8 may be provided outside the control panel 3, or may be a server. The tank 4 is a storage unit that stores the culture solution, and is connected to the pump 5 via a pipe P1 and to the vessel 6 via a pipe P3. The tank 4 is supported by a support unit 41.

[0013] The pump 5 circulates the culture solution in the vessel 6. By circulating the culture solution in the vessel 6 with the pump 5, it is possible to reduce the settling of algae contained in the culture solution inside the vessel 6. The pump 5 is connected to the vessel 6 via a pipe P2. A portion of each of the pipes P2 and P3 is disposed inside an opening formed in the container 2.

[0014] <Configuration of Container 6> FIG. 2 is a view of the portion of the algae culture device 1 shown in FIG. 1 surrounded by dotted line A1, viewed from the positive direction of the Z axis. As shown in FIG. 2, the container 6 is tubular and U-shaped, and has extensions 61, 62 and a connection 63. The container 6 is made of a light-transmitting material and stores a culture solution containing algae. This allows sunlight L to be efficiently irradiated onto the algae inside the container 6. Note that the container 6 is not limited to being tubular and U-shaped, and may be, for example, a rectangular parallelepiped shape.

[0015] The container 6 is a closed container in which the inside of the container 6 is sealed so that the culture solution inside the container 6 is not exposed to the air outside the container 6. The container 6 is supported by a support part 7. Sunlight L is irradiated onto the algae contained in the culture solution stored in the container 6.

[0016] The extension portion 61 is tubular, and the X-axis negative side of the extension portion 61 is connected to the pipe P2, and the X-axis positive side of the extension portion 61 is connected to the connection portion 63. The connection portion 63 connects the extension portion 61 and the extension portion 62, thereby forming a U-shape in the container 6. The culture medium flows inside the connection portion 63.

[0017] The extension portion 62 is tubular, and the negative side of the X-axis of the extension portion 62 is connected to the pipe P3, and the positive side of the X-axis of the extension portion 62 is connected to the connection portion 63. The extension portions 61 and 62 are arranged side by side in the Y-axis direction. As shown by the arrows in FIG. 2 , the culture solution flows from the inside of the pipe P2 to the inside of the extension portion 61, and then from the inside of the extension portion 61 to the inside of the extension portion 62 via the inside of the connection portion 63. The culture solution also flows from the inside of the extension portion 62 to the inside of the pipe P3.

[0018] <Configuration of Estimation Device 8> 3 is a block diagram showing an example of a configuration of a main part of the estimation device 8 according to the first embodiment of the present invention. As shown in FIG. 3, the estimation device 8 includes a CO2 supply control mechanism 81, a pH sensor 82, a control unit 83, and a storage unit 84.

[0019] The CO2 supply control mechanism 81 controls the supply of CO2 to the culture solution containing algae stored in the container 6. For example, the algae culture device 1 may include a CO2 tank (not shown) for storing CO2, and may also include a pipe PG that can connect the pipe P2 to the CO2 tank, as shown in Figure 1. In this case, the CO2 supply control mechanism 81 is, for example, a valve provided in the pipe PG.

[0020] When the CO2 supply control mechanism 81 is in the open state, CO2 is supplied from the CO2 tank to the culture solution in the pipe P2 via the pipe PG. Note that the pipe PG is not limited to one that can communicate between the pipe P2 and the CO2 tank, and may be one that can communicate between the tank 4 or the container 6 and the CO2 tank, for example.

[0021] The pH sensor 82 detects the pH of the culture solution. Any known sensor can be used as the pH sensor 82, without any particular limitation. In FIG. 1, the pH sensor 82 is disposed in the tank 4. However, the location of the pH sensor 82 is not limited thereto, and the sensor may be disposed, for example, in the container 6 or in the pipe P3.

[0022] The control unit 83 controls the operation of the estimation device 8. As shown in FIG.

[0023] The calculation unit 831 calculates the amount of CO2 supplied by the CO2 supply control mechanism 81. For example, if the flow rate of CO2 is constant when the CO2 supply control mechanism 81 supplies CO2, the calculation unit 831 calculates the amount of CO2 supply as the product of the time during which the CO2 supply control mechanism 81 supplies CO2 and the flow rate of CO2 per unit time.

[0024] The estimation unit 832 estimates the concentration of algae in the culture solution based on the amount of CO2 supply calculated by the calculation unit 831. Algae grow by photosynthesis using the CO2 in the culture solution. Therefore, the amount of CO2 supply to the culture solution has a positive correlation with the concentration of algae in the culture solution, as long as it does not significantly deviate from the amount of CO2 expected to be consumed by the algae through photosynthesis. An example of the correlation between the amount of CO2 supply and the concentration of algae will be described later. Therefore, the estimation unit 832 can estimate the concentration of algae in the culture solution based on the amount of CO2 supply.

[0025] The CO2 supply control unit 833 acquires a signal indicating the pH of the culture solution from the pH sensor 82. Furthermore, the CO2 supply control unit 833 controls the amount of CO2 supplied by the CO2 supply control mechanism 81 so that the pH of the culture solution detected by the pH sensor 82 falls within a certain range.

[0026] When the pH of the culture solution is within a certain range, the amount of CO2 dissolved in the culture solution can be considered to be approximately constant. In this case, the amount of CO2 supplied to the culture solution can be considered to be close to the amount of CO2 consumed by the algae. Therefore, the amount of CO2 supplied has a stronger correlation with the algae concentration, and the accuracy with which the estimation unit 832 estimates the algae concentration in the culture solution can be improved.

[0027] Specifically, the CO2 supply control unit 833 sets the pH at which the amount of dissolved CO2 in the culture solution is maximized as a target value, and controls the amount of CO2 supplied so that the pH of the culture solution detected by the pH sensor 82 falls within a certain range based on the target value. The target pH value may be, for example, 7.4, but is not necessarily limited to this. The CO2 supply control unit 833 may also control the amount of CO2 supplied so that the pH of the culture solution falls within a range of ±0.1 of the target value, for example, but is not necessarily limited to this.

[0028] By controlling the CO2 supply amount as described above by the CO2 supply control unit 833, the amount of CO2 dissolved in the culture solution can be increased. Furthermore, the amount of CO2 supplied to the culture solution can be made closer to the amount of CO2 consumed by the algae. This can further improve the accuracy with which the estimation unit 832 estimates the concentration of algae in the culture solution. Furthermore, increasing the amount of CO2 dissolved in the culture solution can promote the growth of algae in the culture solution.

[0029] More specifically, the CO2 supply control unit 833 may supply CO2 intermittently when the pH of the culture solution detected by the pH sensor 82 is equal to or higher than a target value. Furthermore, the CO2 supply control unit 833 stops the supply of CO2 when the pH of the culture solution detected by the pH sensor 82 is lower than the target value. When supplying CO2 intermittently, the CO2 supply control unit 833 may, for example, continuously supply CO2 for 30 seconds and then stop the supply of CO2 for 1 to 2 minutes. However, the time allocation when the CO2 supply control unit 833 intermittently supplies CO2 is not limited to this.

[0030] By controlling the CO2 supply control unit 833 as described above, fluctuations in the pH of the culture solution are gradual. In particular, by intermittently supplying CO2 when the pH of the culture solution is above the target value, the drop in the pH of the culture solution is gradual. This prevents the pH of the culture solution from significantly overshooting or undershooting the target value. This prevents the algae from being affected by the pH of the culture solution becoming too high or too low, and promotes algae growth.

[0031] The memory unit 84 is a storage device that stores information necessary for control by the control unit 83. The memory unit 84 stores, for example, the correlation between the amount of CO2 supply and the concentration of algae. However, the memory unit 84 is not essential for the estimation device 8. If the estimation device 8 does not include the memory unit 84, the estimation device 8 may be communicably connected to an external storage device that stores information necessary for control by the control unit 83.

[0032] <Supply of CO2 FIG. 4 is a diagram showing an example of control for supplying CO2 to the culture solution by the CO2 supply control unit 833. In FIG. 4, reference numeral 401 is a graph showing the pH of the culture solution, and reference numeral 402 is a graph showing the state of supply of CO2 to the culture solution. In FIG. 4, the horizontal axis indicates the elapsed time in both of reference numerals 401 and 402. The vertical axis indicates the pH of the culture solution in reference numeral 401 and indicates the ON / OFF of the supply of CO2 in reference numeral 402.

[0033] In the example shown in FIG. 4, the target value of the pH of the culture solution was set to 7.4. In the initial state where the CO2 supply control unit 833 started the control for supplying CO2 to the culture solution, the pH of the culture solution was less than 7.4. Therefore, the CO2 supply control unit 833 set the supply of CO2 to OFF in the initial state. As time passed, CO2 in the culture solution was consumed by the photosynthesis of algae, and the pH of the culture solution increased.

[0034] When the pH of the culture solution became equal to or higher than 7.4, the CO2 supply control unit 833 supplied CO2 intermittently. As a result, the increase in the pH of the culture solution became gentle and then turned to a decrease. When the pH of the culture solution became less than 7.4, the CO2 supply control unit 833 stopped the supply of CO2. As a result, the decrease in the pH of the culture solution became gentle and then turned to an increase.

[0035] As shown in FIG. 4, according to the above-described control for supplying CO2 to the culture solution by the CO2 supply control unit 833, the fluctuation in the pH of the culture solution was gentle. Therefore, it can be said that the CO2 supply control unit 833 was able to prevent the pH of the culture solution from greatly overshooting and undershooting the target value. [[ID=十七]]

[0036] <CO2 Supply and OD Value Fig. 5 is a graph showing an example of the correlation between CO2 supply time and OD value. In Fig. 5, the horizontal axis represents elapsed time, the right vertical axis represents the integrated value of CO2 supply time, and the left vertical axis represents OD value. Also in Fig. 5, reference numeral 501 represents a graph showing the integrated value of CO2 supply time, and reference numeral 502 represents a graph showing OD value. Note that in this embodiment, for example, the OD value (optical density) represents the concentration of algae.

[0037] In the example shown in Fig. 5, the flow rate of CO2 is constant when the CO2 supply control mechanism 81 supplies CO2. Therefore, the amount of CO2 supplied is proportional to the integrated value of the CO2 supply time. Also, in the example shown in Fig. 5, the CO2 supply control unit 833 controls the amount of CO2 supplied by the CO2 supply control mechanism 81 so that the pH of the culture solution falls within a certain range. Therefore, the pH of the culture solution can be considered to be approximately constant.

[0038] In this case, as shown in Figure 5, the CO2 supply rate had a strong correlation with the algae concentration. In particular, the correlation between the CO2 supply rate and the algae concentration was significant in the range where the OD value was 0.5 or less. Therefore, by determining the correlation between the CO2 supply rate and the algae concentration in advance using a spectrophotometer or the like, the estimation unit 832 can estimate the algae concentration based on the CO2 supply rate.

[0039] <Effects> As described above, in the algae culture apparatus 1, the concentration of algae can be estimated by the estimation device 8. Therefore, a sensor for measuring the concentration of algae is not required. This eliminates the expense of the sensor, thereby reducing the cost of the algae culture apparatus 1. Furthermore, since maintenance of the sensor is not required, the labor required for maintenance of the algae culture apparatus 1 can be reduced. Therefore, the manufacturing and maintenance costs of the algae culture apparatus 1 can be reduced.

[0040] <Estimation method> 6 is a flowchart showing an example of an estimation method executed by the estimation device 8. In the estimation method, the CO2 supply control unit 833 controls the supply of CO2 to the culture solution (S1, CO2 supply control step). At this time, as described above, the CO2 supply control unit 833 may control the amount of CO2 supplied so that the pH of the culture solution falls within a certain range.

[0041] In parallel with the control of the CO supply amount by the CO supply control unit 833, the calculation unit 831 calculates the CO supply amount (S2, calculation step). Thereafter, the estimation unit 832 estimates the concentration of algae in the culture solution based on the CO supply amount calculated in the calculation step (S3, estimation step).

[0042] <Modification> The estimation device 8 may further include a notification device (not shown) that notifies at least one of the calculation result by the calculation unit 831 and the estimation result by the estimation unit 832. The notification device is, for example, a display device that is provided on the control panel 3 and displays at least one of the calculation result and the estimation result. The display device that shows the calculation result is, for example, a counter that shows the integrated value of the CO2 supply time. Note that the estimation device 8 may be communicably connected to an external notification device that notifies at least one of the calculation result and the estimation result.

[0043] The algae culture device 1 may further include a light-shielding member (not shown) that covers the container 6. The light-shielding member is a light-shielding sheet that blocks sunlight L irradiating the container 6. The light-shielding member is provided so as to cover the container 6 from above. The light-shielding member is supported by supports (not shown) that are provided around the container 6 and the support 7. The light-shielding member is installed manually, but is not limited to this. For example, the light-shielding member may be installed in an opening / closing mechanism (not shown) that can open and close the light-shielding member.

[0044] The control unit 83 may further include an opening / closing control unit (not shown) that controls the opening / closing mechanism. For example, when CO2 supply starts, the opening / closing control unit controls the opening / closing mechanism to cause the shading member to block sunlight L. The opening / closing control unit may also control the opening / closing mechanism to cause the shading member to stop blocking sunlight L when the integrated value of CO2 supply time reaches a preset value. This makes it possible to appropriately adjust the amount of sunlight L irradiated onto the algae according to the amount of CO2 supply, and promotes algae cultivation without causing photoinhibition such as color change or aggregation in the algae due to sunlight L.

[0045] [Embodiment 2] Other embodiments of the present invention will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0046] Fig. 7 is a block diagram showing an example of the configuration of the main parts of an estimation device 8A according to embodiment 2 of the present invention. As shown in Fig. 7, the estimation device 8A differs from the estimation device 8 in that it includes a control unit 83A instead of the control unit 83. The control unit 83A further includes a pump control unit 834 in addition to the configuration of the control unit 83.

[0047] The pump control unit 834 controls the operation of the pump 5. Specifically, the pump control unit 834 switches between a first operation control in which the pump 5 is operated to flow the culture solution through the container 6 at a first flow rate, and a second operation control in which the pump 5 is operated to flow the culture solution through the container 6 at a second flow rate that is slower than the first flow rate. The first flow rate may be, for example, 0.15 m / s or more, and the second flow rate may be, for example, less than 0.15 m / s.

[0048] This makes it possible to suppress the precipitation of algae while suppressing the power consumption of the pump 5, compared to when the pump control unit 834 always performs the first operation control. It also makes it possible to suppress the stress on the algae caused by the flow of the culture solution in the container 6 by the pump 5. Furthermore, it is possible to reduce the temperature rise of the culture solution caused by the operation of the pump 5, and it is also possible to reduce the impact of the temperature rise of the culture solution on the algae.

[0049] The pump control unit 834 adjusts the time for performing the first operation control and the time for performing the second operation control based on the algae concentration estimated by the estimation unit 832. The settling rate of algae increases as the algae concentration increases. Therefore, from the perspective of suppressing algae settling, the pump control unit 834 may adjust the time for performing the first operation control and the time for performing the second operation control based on the algae concentration estimated by the estimation unit 832.

[0050] Specifically, for example, when the algae concentration is equal to or greater than a predetermined value, the pump control unit 834 sets the ratio of the time for which the first operational control is performed to the time for which the second operational control is performed to a first ratio. Furthermore, when the algae concentration is less than a predetermined value, the pump control unit 834 sets the ratio of the time for which the first operational control is performed to the time for which the second operational control is performed to a second ratio that is smaller than the first ratio. This makes it possible to further suppress algal precipitation while efficiently suppressing stress on the algae caused by the flow of culture solution, power consumption of the pump, and temperature rise of the culture solution.

[0051] [Software implementation example] The functions of the estimation device 8, 8A (hereinafter referred to as the "device") can be realized by a program for causing a computer to function as the device, and a program for causing a computer to function as each control block of the device (particularly each part included in the control unit 83, 83A).

[0052] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0053] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0054] Furthermore, some or all of the functions of the control blocks can be realized by logic circuits. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of the control blocks can also be realized by, for example, a quantum computer.

[0055] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0056] 8,8A Estimation device 81 CO2 supply control mechanism 82 pH sensor 831 Calculation Unit 832 Estimation Department 833 Supply control section 834 Pump control unit

Claims

1. CO2 is added to the culture solution containing algae stored in the container. ２ Controlling the supply of CO ２ a supply control mechanism; The CO ２ CO supply control mechanism ２ a calculation unit that calculates a supply amount; The CO calculated by the calculation unit ２ and an estimation unit that estimates the concentration of the algae in the culture solution based on the supply amount.

2. a pH sensor for detecting the pH of the culture solution; The CO 2 is added so that the pH of the culture solution detected by the pH sensor is within a certain range. ２ CO supply control mechanism ２ CO supply control ２ The estimation device according to claim 1 , further comprising a supply control unit.

3. The CO ２ The supply control unit controls the CO ２ The pH of the culture solution detected by the pH sensor is set to a target value at which the amount of dissolved CO is maximized, and the pH of the culture solution detected by the pH sensor is set to a target value within a certain range based on the target value. ２ 3. The estimation device according to claim 2, wherein the supply amount is controlled.

4. The CO ２ The supply control unit When the pH of the culture solution detected by the pH sensor is equal to or higher than the target value, ２ is supplied intermittently, When the pH of the culture solution detected by the pH sensor is lower than the target value, ２ 4. The estimation device according to claim 3, wherein the supply of the signal is stopped.

5. a pump control unit that controls the operation of a pump that circulates the culture solution in the container; The pump control unit a first operation control for operating the pump so as to cause the culture solution to flow through the container at a first flow rate; and a second operation control that operates the pump so as to flow the culture solution through the container at a second flow rate that is slower than the first flow rate.

6. The estimation device described in claim 5, characterized in that the pump control unit adjusts the time for executing the first operation control and the time for executing the second operation control based on the concentration of the algae estimated by the estimation unit.

7. CO2 is added to the culture solution containing algae stored in the container. ２ Controlling the supply of CO ２ a supply control step; The CO ２ CO in the supply control step ２ a calculation step of calculating a supply amount; The CO calculated in the calculation step ２ and estimating the concentration of the algae in the culture solution based on the supply amount.

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