JP3525282B2 - Chlorella culture method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid medium to be supplied to a chlorella culture solution for a certain period of time under irradiation of sunlight that causes chlorella to undergo photosynthesis (that is, in a natural open culture). TECHNICAL FIELD The present invention relates to a chlorella culture method and device for efficiently culturing chlorella while appropriately controlling the supply amount.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
When culturing chlorella under the irradiation of sunlight that causes chlorella to undergo photosynthesis, separate the culture medium into a basal medium (Basal medium) and a supplemental medium (Feeding medium), and cultivate only a certain amount of basal medium on the first day. , The following day, after chlorella has grown and the concentration of algal cells has started to increase, a liquid supplement medium is gradually fed at a constant flow rate during the day (stop at night), or a method similar to this has been performed. It was

However, in such a conventional culture method, when the medium is insufficient, it cannot be grown at a sufficient rate, and when the medium becomes excessive, the supplied medium becomes useless or due to the excessive medium. Occasionally, the properties of the culture solution, such as pH, became unsuitable for chlorella culture, and in any case, it was not possible to perform the culture sufficiently efficiently.

The present invention has been made in view of the above-mentioned problems existing in the prior art, and its object is to grow by performing photosynthesis while chlorella absorbs nutrients from a culture solution. The amount of medium supplied per unit of time and the amount of medium supplied per unit time correspond well, which may delay the growth of chlorella due to lack of medium or, conversely, cause excessive supply of medium and waste medium supplied. With a small amount, it is possible to efficiently cultivate chlorella, and by supplying an excessive medium, the properties of the culture solution such as pH are prevented from becoming inappropriate for chlorella culture, and a chlorella culture method and It is to provide a chlorella culture device.

[0005]

The method for culturing chlorella of the present invention which achieves the above-mentioned object is to provide chlorella while supplying a liquid medium to a culture solution of chlorella under irradiation of sunlight for causing photosynthesis in the chlorella. In the method of culturing, the intensity of sunlight is detected, and when the detected intensity of sunlight is within a predetermined range, it is detected by increasing or decreasing the medium supply amount per constant time according to the increase or decrease in the intensity of sunlight. When the intensity of sunlight is smaller than the predetermined range, the medium is not substantially supplied, and when the intensity of detected sunlight is larger than the predetermined range, the medium supply amount per constant time is substantially constant, and the predetermined range is , Compensation point for photosynthesis of target chlorella
Characterized by a range between the vicinity and near the optical saturation point
It

Chlorella to be cultivated in the present invention is Chlorella pyrenoidosa species and other chlorella, and is not particularly limited.

The chlorella culture medium usually contains water as a main component. The liquid medium is usually an aqueous solution containing components necessary for the growth of Chlorella.

[0008] The supply of the medium may be continuous, for example, intermittent. The medium to be supplied usually has a constant composition, but when the medium supply amount per constant time is increased or decreased, it is also possible to increase or decrease only the supply amount of one or two or more specific components.

The detection of the intensity of sunlight that causes photosynthesis in the target chlorella can be carried out by appropriately using detection means such as various optical sensors.

When culturing chlorella under irradiation of sunlight that causes photosynthesis in the target chlorella, the intensity of the sunlight is close to the light compensation point for photosynthesis of the target chlorella.
In the vicinity of the light saturation point , that is, within the predetermined range,
When the medium supply amount per constant time is increased or decreased according to the increase or decrease of the intensity of sunlight, the medium is not substantially supplied when the intensity of the sunlight is smaller than the predetermined range, and when the intensity of the sunlight is larger than the predetermined range. , The medium supply amount per constant time is made substantially constant.

Therefore, when the photosynthetic rate is 0 or apparently 0, or the degree of daylight is low or dark, the medium is not substantially supplied. When the intensity of sunlight is close to or higher than the light saturation point, the medium supply amount per constant time is substantially constant. When the intensity of sunlight is between the two, the medium supply amount per fixed time increases or decreases according to the increase or decrease in the intensity of sunlight. Therefore, the medium supply amount per unit time (including the case of not supplying),
The rate at which the target Chlorella absorbs the nutrients in the medium (including the case where it does not absorb) corresponds well.

In carrying out the above-mentioned chlorella culture method, a medium supply means for supplying a liquid medium, a detection means for detecting the intensity of sunlight causing photosynthesis in the target chlorella, and the detection means. Based on the intensity of the sunlight, when the intensity of the sunlight is within a predetermined range, the amount of medium supplied per constant time is increased or decreased according to the increase or decrease of the intensity of the sunlight, and when the intensity of the sunlight is smaller than the predetermined range, When the intensity of the sunlight is larger than the predetermined range without supplying the medium substantially, the medium supply amount control means for making the medium supply amount per constant time substantially constant, and the predetermined range
However, there is light saturation near the light compensation point for photosynthesis of the target chlorella
In the range of between around sum point Ru can be used chlorella culture apparatus according to claim.

The medium supply means can be composed of, for example, an elevated tank for supplying the medium and a supply pipe for supplying the medium from the elevated tank to a culture vessel such as a culture pool.

Various optical sensors or the like can be appropriately used as the detecting means.

The medium supply amount control means includes, for example, a voltage signal processing device for inputting an output voltage signal of an optical sensor for detecting the intensity of sunlight and performing necessary processing such as amplification at a required amplification factor, and a supply pipe. A proportional control valve that is provided and that increases / decreases the flow rate of the medium flowing in the supply pipe by increasing / decreasing the opening degree according to an input voltage signal from the voltage signal processing device can be configured. The voltage signal processing device in this case is
For example, the input voltage is compared with a constant value corresponding to the lower limit of the above-mentioned predetermined range, and when the voltage is lower than the constant value, 0 is output,
If it is higher than a certain value, the voltage obtained by subtracting the certain value is amplified with the required amplification factor, and the voltage thus amplified,
By providing a circuit that outputs the smaller one of the constant voltages corresponding to the upper limit of the predetermined range, the output voltage becomes 0 when the input voltage is equal to or lower than the constant value corresponding to the lower limit of the predetermined range, and When the value is equal to or more than a certain value corresponding to the upper limit of the certain range, a voltage larger than the output obtained by amplifying the certain value may not be output. It is of course possible to use a computer or a microcomputer instead of such a processing circuit to perform the same processing. Then, for example, when the input voltage from the voltage signal processing device is 0, the proportional control valve is set to have an opening of 0, and when the input voltage is a positive value, the proportional control valve is set to have an opening proportional to that. Thereby, when the intensity of sunlight is within a predetermined range, the medium supply amount per constant time is increased or decreased according to the increase or decrease of the intensity of sunlight, and when the intensity of the sunlight is smaller than the predetermined range, the medium is substantially supplied. If the intensity of the sunlight is higher than the predetermined range, the medium supply amount per constant time can be controlled to be substantially constant.
The medium may be supplied continuously or intermittently, for example.

According to this apparatus, when the photosynthetic rate is 0 or apparently 0, or the degree of daylight is weak or dark, the medium is not substantially supplied.
When the intensity of sunlight is close to or higher than the light saturation point, the medium supply amount per constant time is substantially constant. When the intensity of sunlight is between the two, the medium supply amount per fixed time increases or decreases according to the increase or decrease in the intensity of sunlight. Therefore, the medium supply amount per unit time (including the case where it is not supplied) and the speed at which the target chlorella absorbs the nutrients of the medium (including the case where it does not absorb) correspond well.

The chlorella culture device is provided with an incubator for accommodating the culture solution of the target chlorella and culturing the target chlorella, and the medium supply means supplies the medium into the incubator. It is possible (Claim 4).

The incubator can be provided, for example, as a culture pool in a place where the amount of sunlight irradiation is as large as possible.

The light compensation point and the light saturation point relating to the photosynthesis of chlorella are, for example, a light compensation point of 2 klux and a light saturation point of 10 klux, which vary to some extent depending on the conditions such as the temperature of the culture solution . In the chlorella culturing method and the chlorella culturing device of the present invention, the upper limit and / or the lower limit of the above-mentioned predetermined range are set to a light compensation point and / or a light saturation point related to photosynthesis of the target chlorella due to temperature change of the culture solution. Ru can be assumed to be vertically according to the variation.

For example, a computer or a microcomputer can raise or lower the upper limit and / or the lower limit of the above-mentioned predetermined range according to the fluctuation of the light compensation point and / or the light saturation point related to the photosynthesis of the target chlorella due to the temperature change of the culture solution. The optical compensation point and / or the optical saturation point corresponding to the temperature of the culture solution are stored in advance in the storage device, and the output of the temperature sensor for detecting the temperature of the culture solution is stored in A-
This can be realized by reading the optical compensation point and / or the optical saturation point corresponding to the D-converted temperature signal from the storage device and changing the upper limit and / or the lower limit of the predetermined range. A computer or a microcomputer is suitable for using the voltage signal processing device as described above that receives the output voltage signal of the optical sensor and performs processing as the medium supply amount control means.

In this case, the correspondence between the medium supply amount per unit time (including the case where it is not supplied) and the rate at which the target chlorella absorbs the nutrients of the medium (including the case where it is not absorbed) becomes more accurate.

[0022]

[0023]

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a chlorella culture device as an example of an embodiment of the present invention.

This chlorella culture device mainly comprises a medium preparation tank 10, an elevated tank 12 for supplying the medium, a feed pipe 14 for feeding the liquid medium from the medium preparation tank 10 to the elevated tank 12, A pump 16 for pumping the medium through the feed pipe 14 and the elevated tank 12
From the main supply pipe 20 and the branch supply pipe 22 for supplying the culture medium to one or more culture pools 18 (incubator), the self-recording sunshine meter 24, the illuminance conversion automatic proportional controller 26, and the main supply pipe 20. The main opening / closing valve 28, the main flow meter 30 and the proportional control valve 32 provided, the branch opening / closing valve 34 and the branch flow meter 36 provided in each branch supply pipe 22, and the irradiation intensity of sunlight as strong as possible and the irradiation amount as much as possible. It consists of one or more culture pools 18 provided in many places.

The culture medium preparation tank 10 stores the raw materials for preparing the culture medium, and agitates the raw material to prepare the culture medium. The culture medium prepared in the culture medium preparation tank 10 is fed to the elevated tank 12 by the pump 16 at an appropriate time.

The culture medium stored in the elevated tank 12 flows down from the elevated tank 12 through the main supply pipe 20 and the branch supply pipe 22 that branches from the main supply pipe 20 and reaches each culture pool 18. It is supplied to each culture pool 18 containing chlorella and its culture solution. These elevated tank 12, main supply pipe 20 and branch supply pipe 22
It constitutes a medium supply means.

The self-recording sunshine meter 24 is equipped with an optical sensor (detection means) such as a photoelectric plate for detecting the intensity of sunlight in the vicinity of the culture pool 18, and outputs a voltage signal according to the intensity of sunlight. Sunlight conversion automatic proportional controller 26, self-recording sunshine meter 24
Input the output signal from and perform necessary processing such as amplification,
Output to the proportional control valve 32 to control the opening of the proportional control valve 32. The daylight conversion automatic proportional controller 26 and the proportional control valve 32 constitute a medium supply amount control means. In the case of culturing chlorella having a normal composition, the process by the illuminance conversion automatic proportional controller 26 is performed such that the voltage signal input from the self-recording sunshine meter 24 is the light near the light compensation point (for example, 2 klu x) related to photosynthesis of the chlorella to be cultured. When the voltage is less than the voltage corresponding to the intensity, 0 V is output, and in the case of the voltage range corresponding to the light intensity between the vicinity of the light compensation point and the vicinity of the light saturation point (for example, 10 klux), the light compensation point is changed from the input voltage. The voltage obtained by subtracting the voltage corresponding to the light intensity in the vicinity is amplified by the specified amplification factor, and in the case of the voltage corresponding to the light intensity exceeding the light saturation point, the voltage corresponding to the light intensity near the light saturation point. The value obtained by subtracting the voltage corresponding to the light intensity in the vicinity of the light compensation point is amplified by the predetermined amplification factor, that is, a constant voltage is output. When the voltage corresponding to the light intensity near the light compensation point and the voltage corresponding to the light intensity near the light saturation point are set according to the change in conditions such as temperature of the culture solution, Even if the compensation point and the optical saturation point change, it is desirable to make the voltages at the actual optical compensation point and the optical saturation point as close as possible.

The proportional control valve 32 inputs the output voltage of the day-illuminance conversion automatic proportional controller 26 and adjusts the opening of the valve in proportion to the input voltage.

When the intensity of sunlight is less than near the light compensation point, that is, when the photosynthetic rate is 0 or apparently 0, or the irradiation light is weak to such an extent that it is dark or dark, the daylight illuminance conversion automatic proportional control is performed. Output voltage from the device 26 is 0
Since it is V, the proportional control valve 32 is in a closed state. Therefore, the medium does not flow to the branch supply pipe 22 and each culture pool 18
Is not supplied to.

When the intensity of sunlight is between the light compensation point and the light saturation point, the opening of the proportional control valve 32 increases or decreases the output voltage from the day-light illuminance conversion automatic proportional controller 26, that is, the intensity of sunlight. Increase or decrease according to the increase or decrease of. Therefore, the flow rate of the medium supplied to each culture pool 18 via the branch supply pipe 22 also increases / decreases according to the increase / decrease in the intensity of sunlight. Proportional control valve 3
The opening degree of 2 is controlled so that the flow rate of the medium supplied to each culture pool 18 becomes an appropriate amount according to the intensity of sunlight.

When the intensity of sunlight reaches near the light saturation point, the opening degree of the proportional control valve 32 becomes maximum. When the intensity of sunlight exceeds the light saturation point, the proportional control valve 32 remains open even if the intensity of sunlight increases. Keep a degree. Therefore, the flow rate of the medium supplied to each culture pool 18 through the branch supply pipe 22 also maintains a constant value regardless of the increase or decrease in the intensity of sunlight.

As described above, since the medium supply flow rate increases and decreases according to the increase and decrease of the intensity of sunlight, the medium supply amount per constant time and the growth rate of the target chlorella by performing photosynthesis while absorbing nutrients of the medium are: Even when the intensity changes from moment to moment due to changes in the height of the sun or changes in the amount of cloud, such as sunlight, it automatically responds well.

[0035]

[Example] Diameter 40 m (surface area 125
2 culture pools (6 square meters), one with the conventional method described above and the other with the method according to the invention, with a basal medium of the same composition and a feed medium of the same composition (as carbon source). The liquid medium containing acetic acid as a main component) was cultured for 7 days at a culture medium depth of 30 cm.

The results are as follows. (1) 60 kg (weight of chlorella dry powder) seeds used in the culture pool cultured by the conventional method were subtracted to obtain 273 kg (weight of chlorella dry powder) of chlorella. That is, the photosynthetic output was about 31 g / square meter / day.

The total amount of acetic acid (glacial acetic acid) used was 95.
It was 5.5 liters. That is, it was about 3.5 liters / kg of chlorella dry powder. (2) The seed of 60 kg (weight of chlorella dry powder) used in the culture pool cultured by the method of the present invention was subtracted to obtain 360 kg (weight of dry powder of chlorella) of chlorella. That is, the photosynthetic output was about 41 g / square meter / day.

The total amount of acetic acid (glacial acetic acid) used was 100.
It was 8 liters. That is, it was about 2.8 liter / kg of chlorella dry powder.

Thus, culturing by the method of the present invention,
Compared to the conventional culture method, the production of chlorella dry powder increased by about 32% in 7 days, and the glacial acetic acid used to produce 1 kg of chlorella dry powder was saved by about 25%.

[0040]

EFFECTS OF THE INVENTION According to the chlorella culture method of the present invention, the amount of medium supplied per unit time (including the case where it is not supplied)
And the rate at which the target chlorella grows through photosynthesis while absorbing nutrients in the medium (including the case where it does not absorb), the change in the height of the sun and the change in cloud cover from sunrise to sunset like sunlight Because it responds well even when the intensity of irradiation light changes from moment to moment, the growth of chlorella is delayed due to lack of medium, and conversely, excess medium is supplied and the supplied medium is not wasted. , It is possible to efficiently culture Chlorella. Further, it is possible to prevent the properties of the culture solution such as pH from becoming unsuitable for the chlorella culture by supplying the excess medium.

According to the chlorella culture method of claim 2, the medium supply amount per fixed time (including the case where the medium is not supplied)
And the rate at which the target chlorella grows through photosynthesis while absorbing nutrients in the medium (including the case where it does not absorb), the change in the height of the sun and the change in cloud cover from sunrise to sunset like sunlight Since it responds more accurately even when the intensity of the irradiating light changes momentarily, the growth of chlorella is delayed due to lack of medium, or conversely, excess medium is supplied and the supplied medium is wasted. And the chlorella can be cultured more efficiently. Further, by supplying an excessive amount of medium, it is better prevented that the properties of the culture solution such as pH are unsuitable for chlorella culture.

According to the chlorella culture apparatus of the present invention, the medium supply amount per unit time (including the case where the medium is not supplied),
Irradiation occurs when the target chlorella absorbs nutrients in the medium and grows by photosynthesis (including the case where it does not absorb) due to changes in the height of the sun from sunrise to sunset and changes in cloud cover. Even if the intensity of light changes momentarily, it automatically responds well, so the growth of chlorella is delayed due to lack of medium, or conversely, excess medium is supplied and the supplied medium is wasted. The amount of chlorella can be automatically and efficiently cultivated. Further, by supplying the excess medium, it is automatically prevented that the properties of the culture solution such as pH become unsuitable for chlorella culture.

[Brief description of drawings]

FIG. 1 is a schematic view of a chlorella culture device.

[Explanation of symbols]

10 Medium preparation tank 12 elevated tank 14 Feeding pipe 16 pumps 18 culture pool 20 Main supply pipe 22 Branch supply pipe 24 Self-recording sunshine meter 26th Illuminance conversion automatic proportional controller 28 Main on-off valve 30 Main flow meter 32 proportional control valve 34 Branch opening / closing valve 36-branch flow meter

Continuation of the front page (56) Reference JP-A-4-299975 (JP, A) JP-A-8-322553 (JP, A) JP-A-7-184631 (JP, A) JP-A-5-284959 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C12N 1/00-7/08 C12M 1/00-3/10 JSTPlus (JOIS) BIOSIS / WPI (DIALOG) PebMed

Claims (6)

(57) [Claims] 1. A method of culturing chlorella while supplying a liquid medium to a culture solution of the target chlorella under irradiation of sunlight that causes photosynthesis of the target chlorella, which comprises detecting and detecting the intensity of sunlight. When the intensity of the sunlight is within the specified range, the medium supply amount per fixed time is increased / decreased according to the increase / decrease of the intensity of the sunlight, and when the detected intensity of the sunlight is smaller than the specified range, the medium is substantially supplied. If the intensity of the detected sunlight is higher than the above specified range,
The medium supply amount per constant time is substantially constant, and the predetermined range is the light compensation for the photosynthesis of the target chlorella.
A method for culturing chlorella, characterized in that the range is between the vicinity of the point and the vicinity of the light saturation point . 2. The chlorella culture method according to claim 1, wherein the predetermined range is a range between a light compensation point and a light saturation point regarding photosynthesis of the target chlorella. 3. The method according to claim 1, wherein the lower limit and / or the upper limit of the above-mentioned predetermined range is raised or lowered according to the variation of the photocompensation point and / or the light saturation point of the photosynthesis of the target chlorella due to the temperature change of the culture solution. 2. The chlorella culture method described in 2. 4. A medium supply means for supplying a liquid medium, a detection means for detecting the intensity of sunlight that causes photosynthesis in the target chlorella, and based on the intensity of sunlight detected by the detection means, When the intensity of the sunlight is within the predetermined range, the medium supply amount per constant time is increased or decreased according to the increase or decrease of the intensity of the sunlight, and when the intensity of the sunlight is smaller than the predetermined range, the medium is not substantially supplied. When the intensity of the sunlight is larger than the predetermined range, the medium supply amount control means for making the medium supply amount per constant time substantially constant is provided, and the predetermined range is light compensation for photosynthesis of the target chlorella.
A chlorella culture device characterized in that it is a range between the vicinity of the point and the vicinity of the light saturation point . 5. The chlorella culture device according to claim 4, wherein the predetermined range is a range between a light compensation point and a light saturation point regarding photosynthesis of the target chlorella. 6. An incubator for accommodating a culture solution of a target chlorella and culturing the target chlorella, wherein the medium supply means supplies a medium into the incubator.
Or the chlorella culture device according to 5.