JP6988147B2 - Manufacturing method of microorganisms - Google Patents

Description

The present disclosure relates to a method for producing a microorganism that produces a microorganism such as algae.

In recent years, biofuels (hydrocarbons and biodiesel) and algae (particularly microalgae) capable of producing bioactive substances such as astaxanthin have been attracting attention. It is being studied to cultivate a large amount of such algae and use it as an energy alternative to petroleum, or to use it for chemicals, beverages, foods, chemical products and the like.

As a technique for culturing algae, a technique for culturing algae while aerating the culture solution and recovering the floating algae has been developed (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-239746

The technique for recovering microorganisms such as algae that have floated (hereinafter referred to as “floating microorganisms”) as described in Patent Document 1 is a conventional technique in which the entire amount of the culture solution is taken out from the culture tank and the microorganisms are recovered together with the culture solution. Compared with technology, microorganisms can be recovered with energy saving.

However, if the culture is continuously performed and the levitation microorganisms are continuously collected, the microorganisms that cannot be levitation (hereinafter referred to as “unfloating microorganisms”) remain in the culture solution, and the concentration of the unlevitation microorganisms with respect to the levitation microorganisms increases. Unlevitation microorganisms have lower photosynthetic efficiency than levitation microorganisms. Therefore, when the concentration of unfloating microorganisms increases, there is a problem that the culture efficiency of the entire microorganisms decreases.

In view of such problems, it is an object of the present disclosure to provide a method for producing a microorganism capable of recovering the microorganism with energy saving while maintaining the culture efficiency of the microorganism.

In order to solve the above problems, in the method for producing algae according to one aspect of the present disclosure, after supplying gas to the culture solution to cultivate the algae, the supply of the gas is stopped and at least a part of the algae is used. the floated, comprising: a first step of recovering the algae emerged from the culture solution, a second step of recovering the algae remaining in the culture broth after the recovery of algae and the floating, the said In the first step , after supplying gas to the culture solution to cultivate the algae and before recovering the floating algae, the ratio of the floating algae to the algae present in the culture solution is determined. When the ratio of the algae that has been derived and surfaced is equal to or higher than a predetermined threshold, the first step is repeated , and when the ratio of the surfaced algae is less than the threshold value, the first step is performed. After completion , the second step is carried out, and the floating algae recovered in the first step are returned to the culture solution after carrying out the second step.

According to the present disclosure, it is possible to recover microorganisms with energy saving while maintaining the culture efficiency of microorganisms.

It is a figure for demonstrating the culture system. It is a flowchart explaining the flow of process of the manufacturing method of a microorganism.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and the present disclosure is not limited unless otherwise specified. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals, so that duplicate description will be omitted. In addition, elements not directly related to the present disclosure are not shown.

(Culture system 100)
FIG. 1 is a diagram for explaining the culture system 100 of the present embodiment. In FIG. 1 of the present embodiment, the X-axis (horizontal direction), the Y-axis (horizontal direction), and the Z-axis (vertical direction) that intersect vertically are defined as shown in the figure. Further, in FIG. 1, the control flow is shown by a broken line. As shown in FIG. 1, the culture system 100 includes a culture tank 110, an air diffuser 120, a first recovery unit 130, a second recovery unit 140, and a control unit 150.

At least the microorganism and the culture solution are contained in the culture tank 110, and the microorganism is cultured in the culture tank 110. The microorganism cultivated in the culture system 100 of the present embodiment usually has buoyancy and performs photosynthesis. Therefore, in the culture tank 110, a layer of microorganisms is formed on the upper part (near the liquid surface) of the culture solution. The thickness of the layer of microorganisms in the culture tank 110 is, for example, about 2 mm.

Microorganisms are, for example, algae. Here, the algae are, for example, Botryococcus buraniii of the genus Botryococcus, Pseudochoricsis genus Pseudochoricsis genus Pseudochoricystis elypsodidia (Pseudo) Monalanthus Salina), Chlorella prototecoides, Botryococcus sp. , Scenedesmus obliquus, Nannochloris sp. , Dunaliella bardawill (D. Salina), Navicula pelliculosa, Radiosphaera negebensis (Radiosphaera negevensis), Vidalfaella nega liba liba liba liba liba ), Nitzschia palea, Ochromonas dannica, Chlorella pyrenoidosa, Peridinium cincutum, Peridinium cinctum. Ocystis polymorpha), Chlorella limuna spp. , Scenedesmus actus, Scenedesmus spp. , Chlorella mintissima, Prymnesium parvum, Navicula pelliculosa, Scenedesmus dimorphus (Scenedesmus dim) , Chlorella spp. , Euglena gracilis, and Porphyridium cruentum. One or more algae selected from the group.

The air diffuser 120 includes an air diffuser 122 and a blower 124, and supplies a gas useful for culturing microorganisms (a gas serving as a metabolic substrate, for example, a gas containing carbon dioxide) into the culture tank 110. .. The air diffuser pipe 122 is composed of a pipe having a plurality of holes formed therein. The air diffuser 122 is provided near the bottom surface of the culture tank 110. The blower 124 supplies gas to the diffuser tube 122.

The first recovery unit 130 collects floating microorganisms (floating microorganisms). The first collection unit 130 includes, for example, a scraping unit 132, a pipe 134, and a pump 136.

The scraping portion 132 includes a main body portion 132a and an extending portion 132b. The main body portion 132a is a plate member extending in the Y-axis direction along the YZ plane in FIG. 1. The end portion of the main body portion 132a in the Y-axis direction slidably contacts the side surface of the culture tank 110. The lower end of the main body 132a is separated from the bottom surface of the culture tank 110. The extending portion 132b is a plate member extending in the horizontal direction (X-axis direction in FIG. 1) from the lower end of the main body portion 132a. That is, the scraping portion 132 is a member having an L-shaped vertical cross section (XZ cross section in FIG. 1). The scraping portion 132 is arranged in the culture tank 110 so that the microorganism is located above the extending portion 132b.

The scraping portion 132 is moved along the liquid surface of the culture tank 110 in the X-axis direction in FIG. 1 by an actuator (not shown). More specifically, the scraping portion 132 is moved from one end 112 of the culture tank 110 toward the other end 114, or from the other end 114 toward the other end 112.

Prior to the recovery of microorganisms, the scraping portion 132 is arranged on the one end portion 112 side of the culture tank 110. Then, when the microorganisms are sufficiently cultured in the culture tank 110 and the floating microorganisms are attempted to be recovered, the scraping portion 132 is moved from the one end portion 112 to the other end portion 114 by the actuator. Then, the upper layer (layer of floating microorganisms) of the culture solution is scraped by the scraping portion 132, and the floating microorganisms are concentrated on the other end portion 114 side. In addition, by the configuration including the extending portion 132b, it is possible to regulate the wraparound of microorganisms from the lower end of the main body portion 132a to the opposite side in the moving direction due to the movement of the scraping portion 132.

The opening on one end side of the pipe 134 is arranged on the other end 114 side in the culture tank 110, and the opening on the other end side is connected to the pump 136. The opening on one end side of the pipe 134 is arranged at a predetermined depth below the liquid level in the culture tank 110. The predetermined depth is smaller than the maximum thickness of the layer of buoyant microorganisms scraped by the scraping portion 132. The pump 136 sucks the culture solution in which the floating microorganisms are aggregated through the pipe 134. The culture broth containing the floating microorganisms sucked by the pump 136 is sent to the first dehydration treatment facility in the subsequent stage for dehydration treatment. The culture solution is removed (dehydrated) from the floating microorganisms in the first dehydration treatment facility, and the floating microorganisms are further sent to the subsequent treatment facility.

The first dehydration treatment facility includes existing technologies such as a stationary tank, a screen, and a dehydrator. The culture broth recovered in the first dehydration treatment facility is returned to the culture tank 110 or discarded as it is or after being subjected to a predetermined water treatment. The predetermined water treatment is, for example, ozone treatment, chlorine treatment, UV sterilization treatment, activated sludge water treatment, or the like.

Then, when the collection of the floating microorganisms by the pump 136 is completed, the scraping portion 132 is returned to the initial position by the actuator.

The second recovery unit 140 collects the entire amount of the culture solution from the culture tank 110. The second recovery unit 140 includes a pipe 142 and a pump 144. The opening on one end side of the pipe 142 is arranged on the one end 112 side in the culture tank 110, and the opening on the other end side is connected to the pump 144. The opening on one end side of the pipe 142 is arranged near the bottom surface of the culture tank 110. That is, the opening on one end side of the pipe 142 is arranged below the opening on the one end side of the pipe 134. The pump 144 sucks the entire amount of the culture solution through the pipe 142. For example, if the culture solution is sucked by the pump 144 immediately after the recovery of the floating microorganisms by the first recovery unit 130, the unfloating microorganisms remaining in the culture solution will be recovered. The culture broth containing the unfloating microorganisms sucked by the pump 144 is sent to the second dehydration treatment facility in the subsequent stage for dehydration treatment. In the second dehydration treatment facility, the culture solution is removed (dehydrated) from the unfloating microorganisms, and the unfloating microorganisms are further sent to the subsequent treatment facility.

The second dehydration treatment facility includes existing technologies such as a settling separation tank, a screen, and a dehydrator. The culture broth recovered in the second dehydration treatment facility is returned to the culture tank 110 or discarded as it is or after being subjected to the above water treatment.

The control unit 150 is composed of a semiconductor integrated circuit including a CPU (Central Processing Unit). The control unit 150 reads out a program, parameters, and the like for operating the CPU itself from the ROM, and manages and controls the entire culture system 100 in cooperation with the RAM as a work area and other electronic circuits. In the present embodiment, the control unit 150 controls the blower 124, the actuator, and the pump 136, 144. In addition, the control unit 150 derives the levitation rate of microorganisms in the culture solution contained in the culture tank 110. The derivation of the levitation rate by the control unit 150 will be described in detail later.

(Manufacturing method of microorganisms)
Subsequently, a method for producing a microorganism using the culture system 100 will be described. FIG. 2 is a flowchart illustrating a processing flow of the method for producing a microorganism of the present embodiment.

As shown in FIG. 2, the method for producing a microorganism of the present embodiment includes a culture step S110, a levitation rate derivation step S120, a levitation microorganism recovery step S130, a determination step S140, and an unfloating microorganism recovery step S150. .. Hereinafter, each step will be described in detail.

(Culture step S110)
The control unit 150 drives the blower 124 to supply gas to the culture solution contained in the culture tank 110 to cultivate the microorganism.

If the culture solution is not contained in the culture tank 110, the control unit 150 drives a pump (not shown) to introduce the culture solution into the culture tank 110. The culture broth may be the culture broth recovered in the levitation microorganism recovery step S130 or the unfloating microbial recovery step S150, which will be described later, or may be a new culture broth.

When the culture solution is not contained in the culture tank 110, the microorganism to be cultured is introduced into the culture tank 110 in addition to the culture solution. The microorganism to be introduced may be a floating microorganism recovered in the floating microorganism recovery step S130. As a result, the concentration of the floating microorganisms in all the microorganisms in the culture solution can be increased, and the culture efficiency of the microorganisms can be improved.

(Float rate derivation step S120)
After a predetermined culture time elapses, the control unit 150 derives the levitation rate of microorganisms in the culture solution contained in the culture tank 110. The culturing time may be a preset time, or may be determined based on the transition of the weather (sunshine rate) or the like. The levitation rate is the ratio of the levitation microorganisms to the microorganisms present in the culture solution contained in the culture tank 110. Assuming that the amount of floating microorganisms in the culture solution contained in the culture tank 110 is A and the amount of unfloating microorganisms is B, the floating rate F = A / (A + B) × 100 (%) is established. Therefore, the control unit 150 can derive the levitation rate F based on the amount A of the levitation microorganisms and the amount B of the unlevitation microorganisms. The amount A of the floating microorganisms and the amount B of the unfloating microorganisms may be measured by a fractionation method.

(Floating microorganism recovery step S130)
The control unit 150 recovers the floating microorganisms from the culture broth. Specifically, the control unit 150 first stops the blower 124. Then, when a predetermined ascent time has elapsed after the blower 124 is stopped, the control unit 150 drives the actuator to move the scraping unit 132 from the initial position (one end 112 side) to the other end 114 side. Let me. The levitation time is the time from when the blower 124 is stopped until a predetermined ratio (for example, about 90%) of levitation microorganisms ascend to the liquid surface of the culture solution.

When the scraping unit 132 moves to the other end 114 side, the control unit 150 drives the pump 136 to collect the floating microorganisms. The pump 136 is driven for a predetermined time, and when the recovery of the floating microorganisms is completed, the control unit 150 stops the pump 136. Then, the control unit 150 drives the actuator to move the scraping portion 132 from the other end 114 side to the one end 112 side, and returns the scraping portion 132 to the initial position.

(Determining step S140)
The control unit 150 determines whether or not the levitation rate derived in the levitation rate deriving step S120 is equal to or greater than a predetermined threshold value. As a result, when it is determined that the levitation rate is equal to or higher than the threshold value, the control unit 150 repeats the process (first step) from the culture step S110 to the levitation microorganism recovery step S130. On the other hand, when it is determined that the levitation rate is less than the threshold value, the control unit 150 shifts the process to the following unlevitation microorganism recovery step S150 (second step). The threshold value is set based on the minimum levitation rate at which a predetermined amount of levitation microorganisms can be cultivated when the culturing step S110 is performed after the levitation microorganism recovery step S130 is performed.

(Unfloating microorganism recovery step S150)
The control unit 150 drives the pump 144 and collects the entire amount of the culture solution in the culture tank 110. Then, the control unit 150 stops the pump 144 when the collection of the culture solution from the culture tank 110 is completed. Then, the control unit 150 returns the process to the culture step S110.

As described above, the method for producing a microorganism of the present embodiment includes one or a plurality of first steps (culture step S110, levitation rate derivation step S120, levitation microorganism recovery step S130) and a second step (not yet). The levitation microorganism recovery step S150) is alternately repeated.

When the floating microorganisms are recovered by performing only the floating microorganism recovery step S130, substantially a small amount of suction is used as compared with the case where only the unfloating microorganism recovery step S150 is carried out to recover the unfloating microorganisms. Equal amounts of microorganisms can be recovered. Therefore, by carrying out the first step, it becomes possible to recover microorganisms from the culture broth at low energy and low cost.

On the other hand, if only the first step is repeated, the number of floating microorganisms decreases from the culture solution contained in the culture tank 110, and the concentration of the unfloating microorganisms with respect to the floating microorganisms in the culture solution increases. Unfloating microorganisms are farther from the liquid surface than buoyant microorganisms. In addition, the liquid surface is covered with floating microorganisms. For this reason, unlevitation microorganisms have lower photosynthetic efficiency than levitation microorganisms. Therefore, if the concentration of unfloated microorganisms increases, the culture efficiency of the entire microorganisms decreases.

Therefore, by performing the unfloating microorganism recovery step S150, then the unfloating microorganism recovery step S150, and then performing the culture step S110, the unfloating microorganisms can be removed from the culture solution. This makes it possible to reduce the concentration of unfloating microorganisms with respect to the floating microorganisms in the culture solution contained in the culture tank 110. That is, the concentration of floating microorganisms in the culture solution can be increased. Therefore, it is possible to improve the culture efficiency of the entire microorganism by increasing the concentration of the floating microorganism, which has a relatively high efficiency of photosynthesis.

As described above, in the method for producing a microorganism of the present embodiment, by alternately repeating the first step and the second step, it is possible to recover the microorganism with energy saving while maintaining the culture efficiency of the microorganism. It becomes.

Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure. Will be done.

For example, in the above embodiment, the configuration in which the culture system 100 includes the air diffuser 120 has been described as an example. However, as long as the gas can be supplied to the culture tank 110 (culture solution), the configuration of the supply mechanism is not limited. For example, the culture system 100 may be provided with a pressure dissolving device, a stirring device, or the like in place of or in addition to the air diffuser 120.

Further, in the above embodiment, the first recovery unit 130 including the scraping unit 132 has been described as an example. However, the structure of the first recovery unit 130 is not limited as long as the floating microorganisms can be recovered from the culture solution. For example, a configuration in which a culture solution containing floating microorganisms overflows from the culture tank 110, a configuration in which floating microorganisms are collected only by a pump, a skimmer such as a conveyor type, and various existing technologies described in JP-A-2016-82910. Technology can be used.

Further, when carrying out the levitation microorganism recovery step S130, the addition of a flocculant, a pressurized flotation mechanism, or the like may be used to promote the levitation of the levitation microorganism.

Further, in the above embodiment, the configuration in which the second recovery unit 140 recovers the entire amount of the culture solution and recovers the unfloating microorganisms remaining in the culture solution has been described as an example. However, if the second recovery unit 140 can recover the unfloating microorganisms remaining in the culture solution after the floating microorganism recovery step S130 is performed, the second recovery unit 140 does not have to recover the entire culture solution. For example, the second recovery unit may be composed of an existing skimmer that collects activated sludge and a pump that sucks unfloating microorganisms aggregated by the skimmer. In this case, it is preferable to return the levitation microorganisms recovered in the levitation microorganism recovery step S130 to the culture broth after the unfloating microorganisms have been recovered to carry out the culture step S110. As a result, the concentration of the floating microorganisms in all the microorganisms in the culture solution can be increased, and the culture efficiency of the microorganisms can be improved.

Further, in the above embodiment, the configuration in which the control unit 150 determines whether or not to repeat the first step based on the levitation rate has been described as an example. As a result, the concentration of the floating microorganisms in the culture solution contained in the culture tank 110 can be maintained at a predetermined value. However, the number of times the first step is performed may be a predetermined number of times. It should be noted that the more times the first step is performed with respect to the second step, the more energy-saving the microorganisms can be recovered. Further, the smaller the number of times the first step is performed with respect to the second step, the more the culturing efficiency of the microorganism can be improved.

Further, in the above embodiment, the configuration for deriving the levitation rate F based on the amount A of the levitation microorganisms and the amount B of the unlevitation microorganisms has been described as an example. However, when the microorganism is an oil-producing microorganism, the levitation rate can be derived based on the average value of the oil content of all the microorganisms in the culture solution contained in the culture tank 110. For example, the reduction method may be used to derive the average value of the oil content. The higher the oil content, the higher the levitation rate.

Further, when switching from the first step to the second step, the unfloating microbial recovery step S150 may be performed before the levitation microbial recovery step S130.

The present disclosure can be used in a method for producing a microorganism that produces a microorganism such as algae.

S110 culture step (first step)
S130 Floating microorganism recovery step (first step)
S150 Unfloating microorganism recovery step (second step)

Claims (1)

After culturing the algae by supplying gas to the culture solution, the first step to stop the supply of the gas is floated at least a portion of said algae, recovering the algae emerged from the culture broth,
The second step of recovering the algae remaining in the culture solution after collecting the floating algae, and the second step.
Including
The ratio of the floating algae to the algae present in the culture solution after the algae are cultured by supplying gas to the culture solution in the first step and before the floating algae are recovered. Derived,
When the ratio of the surfaced algae is equal to or higher than a predetermined threshold value, the first step is repeated .
When the ratio of the surfaced algae is less than the threshold value, the second step is carried out after the completion of the first step.
A method for producing a microorganism that returns the floating algae recovered in the first step to the culture solution after performing the second step.

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