WO2010038912A2

WO2010038912A2 - Microalgae culture method and device

Info

Publication number: WO2010038912A2
Application number: PCT/JP2009/067594
Authority: WO
Inventors: 関根敏朗
Original assignee: Sekine Toshirou
Priority date: 2008-10-03
Filing date: 2009-10-05
Publication date: 2010-04-08
Also published as: WO2010038912A3

Abstract

Provided is a method for culturing microalgae such as Chlorella without rotifer predation, and with less expensive facilities. In an open pond method for culturing microalgae, the microalgae are subjected repeatedly during culture to aerobic lighted conditions and anaerobic dark conditions, and after killing water fleas and rotifers this microalgal liquid is supplied to the open pond together with nutrients and diluting water, and the microalgae are cultured under sunlight.

Description

Method and apparatus for culturing microalgae

The present invention relates to a method and apparatus for culturing microalgae.

Conventionally, there is an open pond method as one of the culture methods of microalgae. In the open pond method, microalgae are cultured by irradiation of sunlight in a shallow pond with a water depth of 50 cm or less, which is usually installed outdoors. Open ponds are constantly exposed to other microbial contamination. Since rotifers, especially swimming rotifers, prey on microalgae and have high reproductive power, prevention of damage caused by this rotifer was a major issue for stably and efficiently culturing microalgae.
In view of the above, the inventor has devised a technique for culturing microalgae such as chlorella of Patent No. 3844365 and Patent No. 4038772 to solve this problem. These techniques have made it possible to stably and efficiently culture microalgae in an open pond without using an insecticide.
However, in order to use the produced microalgae for feed and biofuel, there is a drawback that the facility cost is still expensive.

The present invention has been made in view of these points, and an object of the present invention is to provide a method and apparatus for culturing microalgae such as chlorella that are free from rotifer damage and have a lower facility cost.

That is, according to the present invention, firstly, in the method of culturing microalgae in an open pond, a part of the microalgae liquid grown in the open pond is taken out and kept in anaerobic dark conditions, and daphnia and rotifers are killed. A microalgae cultivation method characterized by filling microalgae with nutrients and dilution water in an open pond and cultivating microalgae under sunlight irradiation conditions. Second, culturing microalgae in an open pond In this method, the microalgae are cultured under repeated aerobic and anaerobic dark conditions, and the microalgae liquid in which the daphnia and rotifer are killed is filled in an open pond together with nutrients and diluted water, and is irradiated with sunlight. A method for culturing microalgae, characterized by culturing microalgae under conditions, and thirdly, in a method for culturing microalgae in an open pond, taking out a part of the microalgae grown in the open pond, This is cultured under repeated aerobic and anaerobic dark conditions, and the microalgae liquid that killed Daphnia and rotifers is filled into an open pond together with nutrients and diluted water. And, fourth, in a method for culturing microalgae in an open pond, a plurality of open ponds having approximately the same capacity and the one open pond having approximately the same capacity. A method of cultivating microalgae using a sealed container, wherein the microalgae liquid from one open pond is extracted, stored in a sealed container, kept under anaerobic conditions, and killed daphnia and rotifers. Is a method for cultivating microalgae, characterized by filling the open pond again and allowing the microalgae to grow under solar light irradiation, exterminating operation and proliferating operation repeatedly for a plurality of open ponds, alternately. 5. An apparatus for cultivating microalgae in an open pond, wherein the apparatus contains (a) a plurality of open ponds having substantially the same capacity, and (b) a microalgae solution in each open pond, A closed container with an exhaust device for keeping the liquid under anaerobic dark conditions, and (c) a liquid transfer device for moving the microalgae liquid between the open pond and the closed container, and the number of the open ponds Is a microalgae culture apparatus characterized by having a ratio of 2 to 2 or more of the closed containers.

FIG. 1 is a plan layout view for explaining a first embodiment of the present invention.
FIG. 2 is a plan layout view for explaining a second embodiment of the present invention.
FIG. 3 is a plan layout view for explaining a third embodiment of the present invention.
FIG. 4 is a plan layout view for explaining a fourth embodiment of the present invention.
FIG. 5 is a plan layout view for explaining a fifth embodiment of the present invention.
FIG. 6 is a plan layout view for explaining a sixth embodiment of the present invention.
FIG. 7 is a vertical cross-sectional arrangement diagram for explaining the first and second embodiments.
FIG. 8 is a vertical cross-sectional arrangement diagram for explaining the first and second embodiments.
FIG. 9 is a vertical cross-sectional arrangement diagram for explaining the third, fourth, fifth and sixth embodiments. It is AA longitudinal cross-sectional view of FIG.
FIG. 10 is a vertical cross-sectional arrangement diagram for explaining the third, fourth, fifth and sixth embodiments. It is AA longitudinal cross-sectional view of FIG.
FIG. 11 is a vertical cross-sectional arrangement diagram for explaining the third, fourth, fifth and sixth embodiments. It is a BB longitudinal cross-sectional view of FIG.
FIG. 12 is a plan layout view for explaining a seventh embodiment of the present invention.
13 is a longitudinal sectional view taken along the line CC in FIG.
FIG. 14 is a CC longitudinal sectional view of FIG.
FIG. 15 is a plan layout view for explaining an eighth embodiment of the present invention.
FIG. 16 is a plan layout view for explaining a ninth embodiment of the present invention.
17 is a DD longitudinal sectional view in FIG.
FIG. 18 is a DD longitudinal sectional view in FIG.
FIG. 19 is a DD longitudinal sectional view in FIG.
20 is a DD longitudinal sectional view in FIG.
FIG. 21 is a plan layout view for explaining the tenth embodiment of the present invention.

1 to 12 are open ponds, 13 are flow paths, 14 pipes, 15 are harvesting tanks, 16 are pumps, 17 are pipes, 18 are pipes, 19 are anaerobic tanks, 20 are pipes, 21 are blowers, 22 are pipes, 23 is a mixing tank, 24 is a pipe, 25 is a pipe, 26 is an open pond, 27 is a pipe, 28 is an upstream end, 29 is a downstream end, 30 is a pipe, 31 is an overflow weir, 32 is a continuous culture tank, 33 is Pipe, 34, Pipe, 35, Pipe, 36, Anaerobic dark part, 37, Air diffuser pipe, 38, Pipe, 39, Air layer, 40, Aerobic part, 56, Open pond, 57, Open pond, 58, Open pond 59 is an open pond, 60 is an open pond, 61 is an open pond, 62 is an open pond, 63 is an open pond, 64 is a pipe, 65 is a carbon dioxide gas vent pipe, 66 is a blower, 67 is a carbon dioxide source, and 68 is a diffuser. 69, tube, 70, tube, 71, tube, 72, tube 73,

tube

74, 75 tube, 76 tube, 77 open pond, 78 open pond 79 is an open pond, 80 is an open pond, 81 is a pipe, 82 is a pipe, 83 is a pipe, 84 is a pipe, 85 is a sealed container, 86 is a paddle rotor, V1 is an open / close valve, V2 is an open / close valve, and V3 is an open / close valve V4 is an on-off valve, V5 is an on-off valve, V7 is an on-off valve, V8 is an on-off valve, V9 is an on-off valve, V10 is an on-off valve, V11 is an on-off valve, V12 is an on-off valve, and V13 is an on-off valve. V14 is an on-off valve, V15 is an on-off valve, V16 is an on-off valve, V17 is an on-off valve, V18 is an on-off valve, and a solid line arrow indicates the direction of liquid movement.
Examples and Actions Next, the present invention will be described in more detail based on examples. FIG. 1 is a plan layout view for explaining a first embodiment of the present invention. In this embodiment, there are 12 open ponds. First, the microalgal liquid (hereinafter, algal liquid) in the open pond 1 is guided to the harvesting tank 15 through the flow path 13. A part of the algal liquid is filled into the anaerobic tank 19 through the pipe 18 by the pump 16. Here, the algal liquid is maintained in an anaerobic dark condition, and the algal liquid in which Daphnia and rotifers are killed is sent to the mixing tank 23 via the tube 25. Here, the algal liquid is mixed with nutrient water and dilution water sent through the tube 24. It is appropriate to dilute the algal liquid 10 to 20 times with nutrient water and dilution water. This mixed solution is filled into the open pond 1 through the pipe 14. After that, the microalgae grow by receiving sunlight until harvest. The residual algal liquid in the harvesting tank 15 is sent to a harvesting process (not shown). Thereafter, the same operation is sequentially performed for other algal ponds, and microalgae are cultured in batches. The culture period is suitably 15 to 25 days. The capacity of the anaerobic tank 19 is suitably 5% to 10% of the capacity of one open pond. For one

anaerobic tank

19, 15 to 25 open ponds are appropriate.
FIG. 2 is a plan layout view for explaining a second aspect of the present invention.
In the embodiment of FIG. 1, batch culture was performed sequentially in a plurality of open ponds. In this embodiment, the open pond 26 is constituted by a single water channel, and the microalgae are extruded and cultured in this water channel, which is different from the embodiment of FIG. The mixed liquid adjusted in the same manner as in the first aspect is caused to flow into the upstream end 28 of the water channel through the pipe 27. At the same time, the algal liquid is pushed out from the downstream end 29 through the pipe 30 to the harvest tank 15 through the overflow weir 31. In this way, by periodically introducing the mixed solution into the upstream end 28, the algal solution moves downstream while increasing the concentration of microalgae, finally reaches the harvesting tank 15 and is harvested. The residence time is suitably 15 to 25 days. The capacity of the anaerobic tank 19 is suitably 5% to 10% of the daily harvest. For the anaerobic tank 19, the open pond capacity is suitably 15 to 25 times the daily harvest.
7 and 8 are longitudinal sectional views for explaining the operation in the anaerobic tank. With the valve V1 open, the algal liquid in the harvesting tank 15 is filled into the anaerobic tank 19 through the pipe 18 by the pump 16. Thereafter, the valve V1 is closed. The algae liquid in the anaerobic tank 19 is gradually anaerobic because the supply of oxygen is cut off and oxygen is consumed by the respiration of microorganisms. Usually, dissolved oxygen becomes approximately zero in 1 to 2 hours. Under anaerobic conditions, rotifers and daphnids usually die in 11 to 13 hours, so it is desirable to store the algal fluid in the anaerobic tank 19 for 13 to 15 hours or more. Thereafter, the valve V1, the valve V2 and the valve V3 are opened, and the algae liquid is fed into the mixing tank 23 through the pipe 25 while air is injected by the blower 21 through the pipe 22 and the diffuser pipe 18 and the algae liquid is stirred. send.
FIG. 3 is a plan layout view for explaining a third aspect of the present invention. In this embodiment, microalgae are cultured using an open pond for batch culture and a continuous culture tank 32 for continuous culture. First, in the continuous culture tank 32, microalgae are continuously cultured while aerobic and anaerobic dark conditions are repeated and daphnia and rotifers are killed. A part of the algal liquid is sent from the anaerobic dark part 36 (FIG. 11) to the mixing tank 23 through the tube 25. Here, the algal liquid is mixed with nutrient water and dilution water sent through the tube 24. It is appropriate to dilute the algal liquid 10 to 20 times with nutrient water and dilution water. This mixed solution is filled into the open pond 1 through the pipe 14. After that, the microalgae grow by receiving sunlight until harvest. The algal liquid in the harvesting tank 15 is sent to a harvesting process (not shown). Thereafter, the same operation is sequentially performed for other open ponds, and microalgae are cultured in batches. The culture period is suitably 15 to 25 days. It is appropriate that the capacity of the anaerobic dark portion 36 is approximately equal to the capacity of one open pond. The capacity of the aerobic light part 40 is made substantially equal to the capacity of the anaerobic dark part 36. 15 to 25 open ponds are appropriate for one continuous culture tank 32.
FIG. 4 is a plan layout view for explaining a fourth aspect of the present invention.
In the embodiment of FIG. 3, batch culture was performed sequentially in a plurality of open ponds. In this embodiment, the open pond 26 is constituted by a single water channel, and the microalgae are extruded and cultured in this water channel, which is different from the embodiment of FIG. A mixed liquid similar to that in the third embodiment is caused to flow into the upstream end 28 of the water channel via the pipe 27. At the same time, the algal liquid is pushed out from the downstream end 29 through the pipe 30 to the harvest tank 15 through the overflow weir 31. In this way, by periodically introducing the mixed solution into the upstream end 28, the algal solution moves downstream while increasing the concentration of microalgae, finally reaches the harvesting tank 15 and is harvested. The residence time is suitably 15 to 25 days. It is appropriate that the capacity of the anaerobic dark portion 36 is approximately equal to the daily yield. The capacity of the aerobic light part 40 is made substantially equal to the capacity of the anaerobic dark part 36. A suitable open pond capacity is 15 to 25 times for one continuous culture tank 32.
9, FIG. 10 and FIG. 11 are longitudinal sectional views for explaining the operation in the continuous culture tank 32. FIG. 9 and 11 show culture under daytime aerobic conditions. The blower 21 is operated by closing the valve V5 and opening the valve V4. The algal liquid is irradiated with sunlight while flowing in the water channel. Microalgae absorb light and multiply. FIG. 10 shows the culture under anaerobic dark conditions at night. From the state of FIG. 9, the blower 21 is stopped, the valve 5 is opened, all the algal liquid is stored in the anaerobic dark part 36 through the pipe 35, and the valve V <b> 4 and the valve V <b> 5 are closed. Here, the algal fluid is gradually anaerobic because the supply of oxygen is cut off and oxygen is consumed by the respiration of microorganisms. Usually, dissolved oxygen becomes approximately zero in 1 to 2 hours. Under anaerobic conditions, rotifers and daphnids usually die in 11-13 hours. In the daytime, the valve V4 is opened, the blower 21 is operated, and air is press-fitted through the pipe 34 and the diffuser pipe 37. The algae liquid is pushed out to the aquatic aerobic part 40 while being stirred. Thereafter, air intermittently flows from the lower end of the pipe 35, and an air layer 39 is formed in the pipe 35. As the air layer 39 rises, an upward flow is formed in the pipe 35 and a downward flow is formed in the pipe 38. As a result, the algae liquid moves through the aerobic portion 40 while being stirred and is irradiated with sunlight. In the continuous culture tank 32, these operations are repeated every day. A part of the algae liquid in the anaerobic dark part 36 is extracted, sent to the mixing tank 23 through the tube 25, and used for culture in an open pond. The continuous culture tank 32 is charged with the same amount of diluted water and nutrient as the extracted algal liquid. In this way, microalgae are continuously cultured in the continuous culture tank 32.
FIG. 5 is a plan layout view for explaining a fifth aspect of the present invention. In this embodiment, microalgae are cultured using an open pond for batch culture and a continuous culture tank 32 for continuous culture. First, the algal liquid in the open pond 1 is guided to the harvest tank 15 through the flow path 13. A part of the algae liquid is sent to the continuous culture tank 32 through the pipe 18 by the pump 16. In the continuous culture tank 32, microalgae are continuously cultured while aerobic and anaerobic dark conditions are repeated and daphnia and rotifers are killed. This algal liquid is sent to the mixing tank 23 via the tube 25. Here, the algal liquid is mixed with nutrient water and dilution water sent through the tube 24. It is appropriate to dilute the algal liquid 10 to 20 times with nutrient water and dilution water. This mixed solution is filled in the algal pond 1 through the pipe 14. After that, the microalgae grow by receiving sunlight until harvest. The algal liquid in the harvesting tank 15 is sent to a harvesting process (not shown). Thereafter, the same operation is sequentially performed for other algal ponds, and microalgae are cultured in batches. The culture period is suitably 15 to 25 days.
FIG. 6 is a plan layout view for explaining a sixth aspect of the present invention.
In the embodiment of FIG. 5, batch culture was performed sequentially in a plurality of algae ponds. In this embodiment, the algal pond 26 is composed of one water channel, and the point that the microalgae is extruded and cultured in this water channel is different from the embodiment of FIG. The same mixed liquid as in the fifth aspect is caused to flow into the upstream end 28 of the water channel via the pipe 27. At the same time, the algal liquid is pushed out from the downstream end 29 through the pipe 30 to the harvest tank 15 through the overflow weir 31. In this way, by periodically introducing the mixed solution into the upstream end 28, the algal solution moves downstream while increasing the concentration of microalgae, finally reaches the harvesting tank 15 and is harvested. The residence time is suitably 15 to 25 days.
In open pond culture, predators such as rotifers are carried by insects, birds, winds, etc., invade the open pond and begin to multiply. When continuous culture is performed in the above open pond, predators such as rotifers are always present in the pond and prey on microalgae, so if cloudy or rainy days continue, the growth of microalgae decreases. , All microalgae are preyed at once, and the pond water turns yellow and becomes transparent. When this happens, subsequent continuous culture becomes impossible.
In the present invention, as shown in the above six embodiments, batch culture or extrusion flow culture is performed in an open pond. When batch culture or push-flow culture is performed, the algae liquor in the late stage of cultivation with a high concentration of predators such as rotifers is harvested and does not remain in the pond, so that the situation where all the algal liquor in the pond becomes transparent can be avoided. However, when the initial invasion amount of predators such as rotifers is large, abnormal occurrence of rotifers is accelerated, so it is necessary to shorten the culture period, and it becomes difficult to harvest a higher concentration of algal liquid. In the present invention, since the initial invasion amount of predators such as rotifers can be reduced, the loss of microalgae due to predation can be reduced, the culture period can be lengthened, and a higher concentration of algal liquid can be harvested.
Comparing batch culture and extrusion flow culture, batch culture will harvest all late-stage algae liquids with high concentrations of predators such as rotifers and will not remain in the pond. In extrusion flow culture, most of the late-stage algal fluid with a high concentration of predators such as rotifers is harvested, but some remains, so batch culture is excellent for preventing damage to predators such as rotifers. However, the extrusion flow culture is excellent in that the side wall of the open pond can be reduced, the facility cost is low, and the culture operation such as harvesting and input (algae solution, diluted water, nutrient water) is simple.
Although not shown, stirring of the open pond and supply of carbon dioxide gas are performed as necessary.
As nutrient water, organic wastewater such as domestic wastewater, livestock wastewater, sewage or a synthetic medium is used. As dilution water, tap water, groundwater, river water, brackish water, seawater, etc. are used. In any case, it is desirable to remove those contaminated by predators such as rotifers by filtration or the like.
12 to 14 are views showing a seventh embodiment of the present invention. FIG. 12 is a plan view, and FIGS. 13 and 14 are CC longitudinal sectional views. This aspect shows a case where organic wastewater such as livestock manure is used as a nutrient source. The culture apparatus is composed of 12

open ponds

56, 57, 58, 59, 60, 61, 62, 63, 77, 78, 79, 80 and one closed container 85. Twelve open ponds with an average water depth of approximately 10 cm are connected to the pipe 64 by

pipes

69, 70, 71, 72, 73, 74, 75, 76, 81, 82, 83, 84, respectively. Contacted downward.

Pipes

69, 70, 71, 72, 73, 74, 75, 76, 81, 82, 83, and 84 have on-off valves V6, V7, V8, V9, V10, V11, V12, V13, V14, V15, and V16, respectively. , V17. The airtight tube 85 is provided with an opening for the vent pipe 22, and the vent pipe 22 communicates with the blower 21 via the on-off valve V <b> 2. In addition, an exhaust pipe 20 is provided above the inside of the sealed container 85. The exhaust pipe 20 is provided with an on-off valve V1.
In the daytime, as shown in FIG. 13, twelve open ponds are filled with a microalgae solution, irradiated with sunlight, and allowed to grow microalgae.
At night, as shown in FIG. 14, one of the 12 open ponds, for example, the microalgae fluid of the open pond 56 is stored in the sealed container 85 to kill the predatory microanimals under anaerobic conditions ( Hereinafter, it is abbreviated as night storage.) The next night night storage of the next open pond, for example, the open pond 57, the next day night storage of the open pond 58, the next day night storage of the open pond 59, the next day night storage of the open pond 60, The next day, night storage of the open pond 61, the next day night storage of the open pond 62, the next day night storage of the open pond 63, the next day night storage of the open pond 77, the next day open storage pond. The night storage of 78, the night storage of the open pond 79 the next day, the night storage of the open pond 80 the next day, and the above cycle starting from the night storage of the open pond 57 is repeated again. Thus, the microalgae solution in one open pond is stored at night every 12 days. It is appropriate to perform nighttime storage every 25 days or less. That is, 25 or less open ponds are appropriate for one sealed container.
For example, night storage of the microalgae liquid in the open pond 60 is performed in a state in which the on-off valve V2 is closed, the on-off valve V10 is closed, and the on-off valve V1 is closed. In the morning, the on-off valve 10 is opened, the on-off valve V2 is opened, and the blower 21 is operated to move the microalgae liquid to the open pond 60, and then the on-off valve 10 is closed. During the daytime, microalgae grow by receiving sunlight. At sunset, the on-off valve V1 is opened, the on-off valve 11 is opened, the microalgae liquid in the open pond 61 is stored in the sealed container 85 with a natural drop, and stored at night. After that, it will be stored at night.
The diameters of the

pipes

69, 70, 71, 72, 73, 74, 75, 76, 81, 82, 83, 84, and the pipe 64 should be made as large as possible in order to reduce the flow resistance.
A liquid pump may be used to move the microalgae liquid from the sealed container 85 to each open pond. In this embodiment, it is possible to use air having a low resistance and to use a pipe having a larger diameter, which consumes less energy than a liquid pump. In addition, since the blower is installed away from water and does not come into contact with liquid, it is superior in durability, easy to maintain, and less expensive than liquid pumps.
Each open pond is preferably provided low toward the

pipes

69, 70, 71, 72, 73, 74, 75, 76, 81, 82, 83, and 84, respectively. This makes the flow smooth.
The microalgae solution is withdrawn periodically and the organic wastewater is poured into an open pond while diluting with water as necessary. It is desirable to perform this operation every day. Microalgae grow by absorbing nitrogen source, phosphorus source, BOD source, carbon dioxide gas, etc., derived from organic wastewater.
Also in this embodiment as described above, the outbreak of predatory microanimals can be suppressed, and microalgae can be stably cultured. At the same time, the facility costs are much cheaper than those of Japanese Patent Nos. 3844365 and 4038772.
FIG. 15 is a drawing corresponding to FIG. 12, and is a plan view showing an eighth embodiment of the present invention. This aspect differs from the seventh embodiment in that the open pond is configured as a raceway open pond provided with a paddle rotor 86. During the day, the microalgae fluid in the open pond is caused to flow along the raceway by the paddle rotor 86. This fluid agitation promotes the growth of microalgae. Moreover, sedimentation of easily settleable microalgae can be prevented.
16 to 20 are views showing a ninth embodiment of the present invention. FIG. 16 is a plan view, and FIGS. 17 to 20 are DD longitudinal sectional views. In this embodiment, carbon dioxide is used as a carbon source. The culture apparatus is composed of eight

open ponds

56, 57, 58, 59, 60, 61, 62 and 63, and one sealed container 85. Eight open ponds having an average water depth of about 10 cm are connected to the pipe 64 by

pipes

69, 70, 71, 72, 73, 74, 75, and 76, respectively. The

pipes

69, 70, 71, 72, 73, 74, 75, 76 are provided with on-off valves V6, V7, V8, V9, V10, V11, V12, V13, respectively. The airtight tube 85 is provided with an opening for the vent pipe 22, and the vent pipe 22 communicates with the blower 21 via the on-off valve V <b> 2. In addition, an exhaust pipe 20 is provided above the inside of the sealed container 85. The exhaust pipe 20 is provided with an on-off valve V1. In addition, a carbon dioxide gas vent pipe 65 is provided in the lower part of the sealed container 85, and the carbon dioxide gas vent pipe 65 communicates with the blower 66 via an on-off valve V18. The blower 66 is in communication with a carbon dioxide gas source 67.
In the daytime, as shown in FIG. 17, eight open ponds are filled with a microalgae solution, irradiated with sunlight, and microalgae are grown.
At night, as shown in FIG. 18, the microalgae fluid of one of the eight open ponds, for example, the open pond 56, is stored in the sealed container 85 to kill the predatory microanimals under anaerobic conditions ( Hereinafter, it is abbreviated as night storage.) The next night night storage of the next open pond, for example, the open pond 57, the next day night storage of the open pond 58, the next day night storage of the open pond 59, the next day night storage of the open pond 60, On the next day, the open pond 61 is stored at night, the next day is stored in the open pond 62 at night, and the next day is stored in the open pond 63 at night, and the above cycle starting from the night storage of the open pond 57 is repeated again. . Thus, the microalgae solution in one open pond is stored at night every 8 days.
Furthermore, in this embodiment, carbon dioxide gas is added to the microalgae during the daytime. The microalgae of one open pond is extracted and stored in the sealed container 85, where carbon dioxide gas is added, and the open pond is filled again. The carbon dioxide addition operation is repeatedly performed for a plurality of open ponds, alternately.
The carbon dioxide addition operation will be described in detail. For example, let the state of FIG. 17 be immediately before accommodating the microalgal liquid in the open pond 60 in the airtight container 85. FIG. In the state of FIG. 17, the on-off valve V10 is closed, the on-off valve V2 is closed, the on-off valve V18 is closed, and the on-off valve V1 is closed. From this state, the on-off valve v1 and the on-off valve 10 are opened. The microalgal liquid is stored in the sealed container 85 through the pipe 73 and the pipe 64 (FIG. 18). Thereafter, the on-off valve V18 is opened, the blower 66 is operated, and the carbon dioxide gas from the carbon dioxide source 67 is pressed into the sealed container 85 through the pipe 65 and the air diffuser 68 (FIG. 19). Thereafter, the blower 66 is stopped, the on-off valve V18 is closed, the on-off valve V1 is closed, the on-off valve V2 is opened, and the blower 21 is operated. The microalgal liquid whose carbon dioxide concentration is increased is sent to the open pond 60 through the pipe 64 and the pipe 73 (FIG. 20). Thereafter, the on-off valve V10 is closed (FIG. 17). Next, the same carbon dioxide gas addition operation is performed on the microalgal liquid in the open pond 61. Hereinafter, the same carbon dioxide gas addition operation is performed by circulating in order of the

open ponds

62, 63, 56, 57, 58, 59, 60. Thereafter, this is repeated until sunset. At night, as described above, the microalgae liquid in one open pond is stored at night.
The water depth of the sealed container 85 can be increased as necessary. Efficient carbon dioxide can be added normally at a water depth of 1 to 3 m.
Also in this embodiment, the diameters of the

pipes

69, 70, 71, 72, 73, 74, 75, 76 and the pipe 64 are preferably made as large as possible in order to reduce the channel resistance.
A liquid pump may be used to move the microalgae liquid from the sealed container 85 to each open pond. In this embodiment, it is possible to use air with low resistance, and to use a pipe with a larger diameter, which consumes less energy than a liquid pump. In addition, since the blower is installed away from water and does not come into contact with liquid, it is superior in durability, easy to maintain, and inexpensive as compared with a liquid pump.
Moreover, it is good to provide each open pond low toward the

pipes

69, 70, 71, 72, 73, 74, 75, and 76, respectively. This makes the flow smooth.
In this embodiment, as a nutrient salt source such as nitrogen and phosphorus, a chemical fertilizer aqueous solution, organic waste water, or this secondary treated water, etc. may be used in the same manner as shown in the seventh embodiment.
In this embodiment, one carbon dioxide gas addition operation to the microalgal liquid in each open pond is approximately 10 minutes. The microalgae solution in each open pond is subjected to a carbon dioxide addition operation approximately every 80 minutes. If one carbon dioxide gas addition operation is 5 minutes and each open pond is subjected to the carbon dioxide gas addition operation every 80 minutes, approximately 16 open ponds can be provided for one sealed container 85. is there.
Thus, also in this embodiment, the outbreak of predatory microanimals can be suppressed, and microalgae can be stably cultured. At the same time, the facility costs are much cheaper than those of Japanese Patent Nos. 3844365 and 4038772. Furthermore, the single sealed container 85 can be used for both nighttime storage and efficient carbon dioxide addition operation for suppressing the occurrence of predatory micro-animals, which is economical. Of course, an airtight container for night storage and a container for adding carbon dioxide may be provided separately.
FIG. 21 is a drawing corresponding to FIG. 16 and is a plan view showing a tenth embodiment of the present invention. This aspect is different from the ninth embodiment in that the open pond is configured as a raceway open pond provided with a paddle rotor 86. During the day, the microalgae fluid in the open pond is made to flow along the raceway by the paddle rotor 86. This fluid agitation promotes the growth of microalgae. Moreover, sedimentation of easily settleable microalgae can be prevented.

The rotifer was cultured with Chlorella, and 180 individuals / ml of rotifer was obtained. 200 ml of a 1000-fold dilution of this liquid, 2400 ml of chlorella liquid (2.6 g / l), and 200 ml of nutrient solution were mixed. This was divided into 1400 ml portions. One was placed in a container, sealed, and allowed to stand for 14 hours under anaerobic conditions, to which 10.6 L of water was added, and this was used as Sample A. The other was placed in a container and allowed to stand for 14 hours while ventilating, and 10.6 L of water was added thereto to make Sample B. Sample A and Sample B were placed in containers of 20 cm in length, 40 cm in width, and 20 cm in depth, respectively, and cultured outdoors (installed to prevent rain). Table 1 shows the results. In the sample A in which the chlorella solution containing the rotifer was kept under anaerobic conditions for 14 hours, the rotifer was not damaged. In Sample B, the growth was also slow, and the color of the liquid turned yellow on the 14th day. After that, there was no significant growth of chlorella, and a precipitate was formed.

Effects of the Invention The inventor has devised a technique (Patent No. 3844365, No. 4038772) capable of stably and efficiently cultivating microalgae by suppressing the growth of algae-predatory microanimals such as rotifers without using an insecticide. did. However, this technology requires one anaerobic tank with the same capacity as this open pond for one open pond that is irradiated with sunlight. In the present invention, since the microalgae can be cultured using an open pond 15 to 25 times the conventional anaerobic tank, the facility cost is remarkably reduced. Moreover, damage caused by abnormal breeding of algal predatory microanimals such as rotifers can be avoided without using an insecticide, and microalgae can be stably and efficiently cultured.
Further, in the third to sixth embodiments, since the continuous culture tank 32 is used, it is possible to produce a large amount of a microalgae liquid free from algae predatory microanimals such as rotifers. If there is abnormal breeding of algae-predatory microanimals such as rotifers, the advantage is that all the liquid in the open pond can be removed and cleaned, and a new culture can be started immediately at a high algal concentration using the algae liquid in the continuous culture tank 32. There is.
Furthermore, in the fifth and sixth embodiments, continuous culture is performed in the continuous culture tank 32 using the algae solution in the open pond, so the continuous culture tank 32 is smaller than in the third and fourth embodiments. , Facility costs will be lower.
Furthermore, in the seventh and eighth embodiments, efficient production is possible by a continuous culture method that can maintain a constant algal concentration and can efficiently culture microalgae.
Furthermore, in the ninth and tenth embodiments, efficient production is possible by the continuous culture method that can keep the algal concentration constant and can cultivate microalgae efficiently, and carbon dioxide gas is economical. And can be supplied efficiently.

Claims

In the method of culturing microalgae in an open pond, a part of the microalgae liquid grown in the open pond is taken out, kept in anaerobic dark conditions, and daphnia and rotifers are killed. In addition, a method for culturing microalgae, comprising filling the open pond and culturing the microalgae under sunlight irradiation conditions.
In the method of cultivating microalgae in an open pond, microalgae are cultured under repeated aerobic and anaerobic dark conditions, and the microalgae liquid that kills daphnia and rotifers is released together with nutrients and diluted water. A method for culturing microalgae, comprising filling a pond and culturing microalgae under sunlight irradiation conditions.
In the method of cultivating microalgae in an open pond, a part of the microalgae grown in the open pond was taken out and cultured under repeated aerobic and anaerobic conditions, and the microalgae and rotifer were killed. A method for culturing microalgae, comprising filling an algal liquid with nutrients and dilution water into an open pond and culturing the microalgae under sunlight irradiation conditions.
2. The method of cultivating microalgae according to claim 1, wherein the microalgae is maintained in an anaerobic dark condition by storing the microalgae solution in a sealed container for avoiding contact with the atmosphere.
The microalgae are cultured while repeating aerobic and anaerobic dark conditions by culturing in an open pond during the day and storing in a container for avoiding contact with the atmosphere at night. The method for culturing microalgae according to claim 3.
6. The method for culturing microalgae according to claim 1, wherein the microalgae are cultivated batchwise in an open pond.
6. The method of cultivating microalgae according to claim 1, wherein the microalgae are extruded in an open pond and cultured under flow conditions.
In the method of culturing microalgae in an open pond, a method of culturing microalgae using a plurality of open ponds having approximately the same capacity and a closed container having approximately the same capacity as this one open pond, Remove the microalgae liquid, store it in an airtight container, keep it in anaerobic condition, fill the microalgae liquid that killed Daphnia and rotifer again into the open pond, and grow the microalgae under sunlight irradiation And a method for cultivating microalgae, wherein the multiplication operation is repeatedly performed for a plurality of open ponds while being changed.
In the breeding operation, a container having substantially the same capacity as that of the one open pond, the microalgae of one open pond being extracted from the container for adding carbon dioxide with a carbon dioxide adding device, and the container for adding carbon dioxide 9. The carbon dioxide addition operation for filling the open pond with the microalgae liquid added with carbon dioxide here is repeated for the plurality of open ponds while being alternated. Microalgae culture method.
The airtight container is provided with a carbon dioxide adding device, and the disinfecting operation and the carbon dioxide adding operation are performed in the airtight container with the carbon dioxide adding device. The method for culturing microalgae according to claim 9.
An apparatus for culturing microalgae in an open pond, wherein the apparatus contains (a) a plurality of open ponds of approximately the same capacity, and (b) a microalgae liquid in each open pond, A closed container with an exhaust device for maintaining anaerobic dark conditions, and (c) a liquid transfer device for transferring the microalgal liquid between the open pond and the closed vessel, and the number of the open ponds A microalgae culture apparatus characterized in that the ratio to the number of sealed containers is 2 or more.
12. The microalgae culture according to claim 11, wherein the sealed container is provided below the open pond, and the plurality of open ponds are respectively communicated with the lower part of the sealed container through a pipe provided with an open / close valve. apparatus.
The microalgae culture apparatus according to claim 11 or 12, wherein the sealed container includes a carbon dioxide addition device.
The microalgae culture apparatus according to claim 11, wherein the open pond is a raceway open pond provided with a paddle rotor for allowing microalgae fluid to flow.