KR20110024563A - Photobioreactor and microalgae culture method, and microalgae harvesting method by using that - Google Patents

Abstract

PURPOSE: A photoreactor and a method for culturing and collecting micro algae using the same are provided to uniformly disperse microalgae without a separate stirring device. CONSTITUTION: A photoreactor comprises a culture tank(11) of funnel form; a step of gas injection tube(15) which is coupled to the lower end of the culture tank; a step of stopper(13) which is detachable from the upper end of the culture tank; and a gas discharge tube(17) which penetrates through the stopper and is placed inside the culture tank. The gas injection tube is made of silicon. A method for collecting micro algae using the photoreactor comprises: a step of adding a coagulant to the culture medium, and a step of supplying gas source containing carbon source.

Description

Photobioreactor and microalgae culture method, and microalgae harvesting method by using that}

The present invention relates to a photobioreactor and a microalgae cultivation method and harvesting method using the same, and more particularly, a photobioreactor for high-density cultivation and low-cost harvesting of microalgae useful for the reduction of carbon dioxide and production of biodiesel It relates to microalgal culture and harvesting method.

Generally, scenedesmus sp. Is a microalgae that has been widely used for biological removal process of pollutants such as nitrogen, phosphorus and heavy metals in livestock wastewater, and contains abundant proteins, essential amino acids, minerals and essential fatty acids. It is used as a pet food, aquaculture feed additive, and dietary supplement. [Kim, MK, et al., 2007, Enhanced production of Scenedesmus spp. (green microlalgae) using a new medium containing fermented swine wastewater].

In particular, recent studies have shown that Senedmusmus grows well even at high concentrations of carbon dioxide, making it easy to cultivate using flue gas containing high concentrations of carbon dioxide, and not only reduce carbon dioxide emitted into the atmosphere, but also high lipids in the body. It is a microalgae that has attracted much attention as a source of biodiesel due to its ability to accumulate content, and has been a major target of biotechnology research [Morais, MG, et al., 2007, Isolation and selection of microalgae]. from coal fired thermoelectric power plant form biofixation of carbon dioxide].

The growth of Senedmus mousse varies depending on the strain, but it is generally cultivated in ponds and biological wastewater treatment facilities with optimal temperature range of 25-30 ° C, but uniform stirring and smooth gas exchange are not achieved. There is a problem that high density culture is difficult.

Accordingly, the stirring process, which is an essential process when culturing the microalgae, is made by a separate stirring device such as a magnetic stirrer and aberration, and thus, there is a disadvantage in that the production cost of the microalgae increases.

In addition, the cost of harvesting the cultured microalgae accounts for more than one third of the total cost for microalgae production, and it is difficult to simplify complex production processes such as centrifugation and sedimentation. .

The present invention has been invented to solve the above problems, by directly supplying a gas source containing a carbon source of photosynthesis directly to the culture tank to distribute the microalgae evenly by simply aeration without a separate stirring means to facilitate the use of light The purpose of the present invention is to provide a photobioreactor capable of producing microalgae of high concentration culture, a culture method and a harvesting method using the same.

In particular, an object of the present invention is to provide an optical bioreactor for cultivating the sensedus mousse which is a combustion algae resistant microalgae using combustion flue gas as a gas source containing a carbon source of photosynthesis, and a culture method and a harvesting method using the same.

The present invention to achieve the above object is a funnel-shaped culture tank; A gas injection pipe coupled to the lower end of the culture tank; A stopper provided detachably at an upper end of the culture tank; It provides a photobioreactor comprising a; through the stopper one end is a gas discharge pipe disposed in the culture tank.

In addition, the present invention in the microalgae culture method using the photobioreactor,

The microalgae culture method is also provided by supplying a gas source including a carbon source of photosynthesis to the culture fluid to flow upward, and agitating the culture solution mixed with microalgae.

The photobioreactor according to the present invention and the culturing method and harvesting method using the same according to the present invention supply the gas source containing the photosynthetic carbon source directly into the culture tank without any agitation means for culturing the microalgae, and thus, By inducing uniform agitation, the granules are evenly distributed to increase the light utilization efficiency, and the gas exchange is smoothly performed, thereby facilitating the high density cultivation of the microalgae.

In particular, by using combustion flue gas when cultivating microalgae in the genera of Senedesmus, which is resistant to combustion flue gas, the high concentration of carbon dioxide contained in the flue flue gas is used as a carbon source for photosynthesis of the microalgae, thereby reducing carbon dioxide emitted to the atmosphere. There is environmental friendly.

In addition, the present invention by inducing a rapid mixing of the flocculation liquid using the combustion flue gas during the aggregation process for harvesting the microalgae after the completion of the culture, to increase the settling speed of the tank without additional agitation means to quickly and cultured microalgae Can be harvested easily, due to the simplification of the harvesting process has the effect of reducing the production cost of microalgae.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention, as used in the singular and the plural unless the context clearly indicates otherwise.

There may be a plurality of embodiments of the present invention, and overlapping descriptions of the same parts as in the prior art may be omitted.

The present invention relates to a photobioreactor, a cultivation method and a harvesting method using the same, and uniformly stirs the culture solution by aeration using a gas source (hereinafter referred to as a photosynthetic gas source) including a carbon source of photosynthesis, In particular, by using the combustion flue gas containing a high concentration of carbon dioxide to induce uniform agitation of the culture solution, it is possible to cultivate a large density of combustion algae resistant microalgae.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view showing an embodiment of a photobioreactor according to the present invention.

As shown, the photobioreactor according to the present invention is detachably coupled to a funnel-type culture tank 11 in which culture of microalgae immersed in the culture medium is performed, and an upper end of the culture tank 11. It may be configured to include a stopper 13, the gas injection pipe 15 connected to the lower end of the culture tank 11 and the gas discharge pipe 17 is mounted through the stopper 13 in the vertical direction. .

In the present invention, the culture tank 11 is tapered and gradually narrower in diameter toward the lower end, and the gas injection pipe 15 is coupled to the lower end of the culture tank 11 to the gas injection pipe 15. The photosynthetic gas source to be injected is supplied upward and the culture fluid flows upward.

One end of the gas discharge pipe 17 is positioned in the culture tank 11, and the other end is disposed outside the culture tank 11.

In addition, supply means (not shown) and suction means (not shown) for injecting and discharging the photosynthetic gas source into the gas injection pipe 15 and the gas discharge pipe 17 may be separately configured.

In addition, the present invention is to control the amount of photosynthetic gas source injected into the culture tank (11) and at the same time to easily discharge the cultured crude separated in culture and layered from the culture medium, the culture tank (11) and gas A control valve 19 is installed between the injection pipes 15.

Such a photobioreactor (particularly, the culture tank 11) is preferably made of a glass material in order to maximize the transmission of light and to prevent corrosion of the photobioreactor body by strong light.

In the present invention, the gas injection pipe 15 is used not only for the injection of the combustion flue gas but also for harvesting the cultured coarse gas. For the injection of the flue gas and the discharge and harvest of the gas, the gas injection pipe 15 is It is preferably provided with a tube made of silicon.

For example, the photobioreactor according to the present invention has a length of about 470 mm from the stopper 13 to the lower end thereof, and excludes the length of the stopper 13 having a length of 30 mm and the gas injection pipe 15 having a length of 100 mm. The length of the culture tank 11 is 340 mm, the maximum diameter of the upper end of the culture tank 11 is 140 mm, the minimum diameter of the lower end is 5 mm, and the volume can be produced as about 2 liters. In this case the actual usable culture volume is about 1.5 liters.

Hereinafter, the culture method and harvesting method of the microalgae according to the present invention using the photobioreactor configured as described above are as follows.

First, the combustion flue gas is directly injected into the culture tank 11 containing a predetermined amount of culture solution.

At this time, the combustion flue gas is supplied to the upper end from the lower end of the culture tank 11 and flows upward through the gas injection pipe 15 provided at the lower end of the culture tank 11.

Then, by adjusting the opening and closing degree of the control valve 19 can be adjusted the injection pressure or speed of the culture medium supplied.

Then, the culture solution is uniformly agitated by the combustion flue gas passing through the gas injection pipe 15, and the light transmitted to the culture tank is uniformly transmitted to the culture medium through uniform stirring of the culture solution.

Accordingly, high density culture of microalgae is performed without a separate stirring means.

And, in order to harvest the cultured crude, the stopper 13 is detached and injected with a flocculant, and then combustion flue gas is again injected into the culture tank 11 to induce stirring of the flocculant.

Then, by injecting the combustion flue gas, the culture medium and the flocculant are uniformly mixed to increase the settling velocity of the crude body, and finally, the microalgae are separated from the culture medium and collected at the lower end of the culture medium.

Preferably, the coagulant is first injected into the culture tank 11, a combustion flue gas is supplied, the culture medium is agitated, and after a fixed time, a flocculant is added to the culture medium a second time, and the combustion flue gas is again injected to stir the culture solution. Thereby inducing a faster and smoother aggregation reaction.

The collected microalgae are discharged out of the culture tank 11 through the gas injection pipe 15 by the load when the control valve 19 is opened.

Combustion flue gas injected during the culturing and harvesting process of the present invention is naturally discharged to the gas discharge pipe 17, it may be discharged through the suction action of the suction means for the smooth discharge of the flue gas.

In addition, the control valve 19 may be used to adjust the injection amount and discharge (or injection rate and discharge rate) of the combustion exhaust gas supplied to the gas injection pipe 15 and the discharged microalgae.

The microalgae to be cultured according to the present invention is not limited by the type, but contains a high content of lipids, which are considered to be raw materials of the third generation biodiesel, and contains a high concentration of carbon dioxide in a combustion flue gas. It is preferable to use to culture, harvest and produce microalgae of the genus Genesismus resistant.

The microalgae of the combustion flue gas resistance is a microalgae having a high concentration of carbon dioxide resistance, it is possible to grow using carbon dioxide during photosynthesis.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the scope of the present invention is not limited by these examples. In this experiment, a microalgae was used as a fine algae, and photosynthesis gas was used. Combustion flue gas was used as a source.

In addition, Scenedesmus sp. Used in the culture experiment of the genus Sendesmus using a photobioreactor was used by the Korea Institute of Bioscience and Biotechnology.

Example 1

As a culture solution of Senedmusmus was used BG ₁₁ medium of the composition shown in Table 1.

As a cultivation condition of Senedmusmus, the light source was irradiated with a fluorescent lamp from the rear of the main body of the photobioreactor so that the luminous intensity is 150 μmol E / m ² / s, it was carried out in a constant temperature room maintained at about 25 ℃.

As the carbon source of photosynthesis, an actual combustion flue gas containing 5.5% of carbon dioxide was supplied at 0.3 v / v / m and cultured for 8 days.

Comparative Example 1

In order to compare the productivity of the funnel-type photobioreactor according to the present invention, as a photobioreactor for conventional microalgae culture, cultured with the same BG ₁₁ medium as in Example 1 in a glass bottle and a tubular photobioreactor having a volume of 2 L The condition was incubated for 8 days Cenedesmus.

In Example 1 and Comparative Example 1, in the funnel-type photobioreactor and the conventional tubular photoreactor according to the present invention, combustion flue gas is directly applied at the bottom of the photobioreactor body without a separate device (or agitation means) required for stirring. Injected and stirred the snemus mousse, in the case of a glass bottle, the combustion flue gas was directly supplied from the top of the glass bottle body to the bottom of the culture medium using a tube, and the culture solution was stirred using a magnetic stirrer.

Experimental Example 1

In order to compare the culture results of Example 1 and Comparative Example 1, after the senmus mousse harvested in each photobioreactor was dried under the same conditions, the dry weight and productivity of each cendes mousse was compared.

As a result, as shown in Figure 2, the dry weight of the sensedmus cultivated in the funnel-type photobioreactor according to the present invention appeared high from the beginning of the culture, showed excellent high-density culture during the culture period.

Figure 2 is a graph showing the growth curve of the sensedmus cultivated using various types of photobioreactor, Figure 3 is a supply of flue gas to the funnel-type photobioreactor according to the present invention for eight days It is a photograph cultured.

Finally, the dry weight of Sededmus cultivated in the funnel-type photobioreactor was the highest at 1.9 g / L for 8 days, while the dry weight of Sededmus cultivated in the vial and tubular photoreactor was 1.1 g / L, respectively. And 1.0 g / L.

In the productivity of Cedencemus, the funnel-type photobioreactor was about 0.2 g / L / d, which was about twice as high as the 0.1 g / L / d of the vial and tubular photoreactor.

Therefore, it is judged that high density culture of microalgae, especially Cedes mousse, is possible using the funnel-type photobioreactor according to the present invention as compared to the conventional photobioreactor.

Experimental Example 2

The contents of lipids (raw materials of biodiesel) made in the densely-cultured densed mousse of the funnel and tubular photoreactor and the vial were compared.

In order to quantify the lipid content produced in each of the genesis of Senedmusmus, nucleic acid was used as a solvent and extracted for 9 hours using a soxhlet extractor.

Figure 4 is a graph showing the comparison of the content of lipids extracted from the cultured senmus mousse cultured using various types of photobioreactor, it can confirm the lipid content of cultivated senedmus mousse.

As a result, the total lipid content was highest in the fungus-type photobioreactor, Senedmus, 8.7% (w / w) of dry weight, 7.2% (w / w) in the case of Genesmus in glass bottles ) Showed similar results to the funnel-type photobioreactor of the present invention, while it was very low as 3.7% (w / w) for the sensedus cultured in the tubular photoreactor.

And, in the case of Senedmus cultivated in the tubular photobioreactor, the lipid content is very low compared to other photobioreactors, unlike the funnel-type photobioreactor according to the present invention, a wider light than the gas injection pipe is injected combustion gas Due to the lower end (or tubular culture tank) of the bioreactor, the combustion flue gas supplied from the lower end is not evenly delivered, and thus, the tank is accumulated on the side of the photobioreactor main body (or the culture bath) because the agitation of the culture solution is not performed smoothly. The phenomenon occurs, and it is considered that there is a reason why the use of carbon dioxide is relatively low.

This can be estimated from the highest lipid content of Senedmus cultivated in the funnel-type photobioreactor according to the present invention.

As shown in the experimental results of the production and lipid content above, the funnel-type photobioreactor according to the present invention is agitated smoothly by the combustion flue gas supplied into the culture tank of the carbon dioxide and light of It was judged that the utilization efficiency was improved and the high density culture was easy, and the accumulation rate of lipid was also increased.

Example 2

In order to easily and quickly harvest the cultivated Senedus mousse, a coagulant was added to the culture tank of the funnel-type photobioreactor, and then treated with a flue gas to induce a rapid aggregation reaction by uniformly stirring the culture solution.

To this end, 20 ml of CaCl ₂ (5%, w / w) was added as a coagulant to 500 ml of Senedmus mousse culture incubated at 0.72 g / L dry weight in a funnel-type photobioreactor, and 4 L / of combustion flue gas was added. The mixture was supplied at a flow rate of min (8 vvm), stirred for 30 seconds, and allowed to stand for 30 seconds.

2 ml of FeCl ₃ (5%, w / w) was added thereto, and the coagulation reaction was performed using the combustion exhaust gas under the same conditions and procedures.

5a is a photograph of the coagulation reaction after adding the coagulant CaCl ₂ and FeCl ₃ and stirring using the combustion flue gas, although flocs are formed by the coagulant, but the sedimentation time is small. It took a lot of results. Therefore, in order to increase the size of flocs, after coagulation reaction with coagulant, dilution of 1/5 of the stock solution of the biopolymer produced from Paenibacillus polymixa AM9 was added to 10 ml, and the combustion flue gas was 1 L / min (2 vvm) was supplied at a flow rate and stirred for 1 minute.

Figure 5b is a photograph immediately after the addition of the biopolymer after supplying and stirring the combustion flue gas, Figure 5c is after stopping the agitation by the entire combustion flue gas and left standing for 3 minutes to complete the solid with the culture solution by the settling It is a separate picture.

In FIG. 5C, it was observed that the sensedmus in the culture was settled and the culture was transparent as compared with FIG. 3.

Microalgae are generally settled after cultivation to collect the algae by natural sedimentation, but it takes more than 24 hours to harvest the microalgae quickly, whereas the aggregation of the harvesting method according to the present invention Using the microalgae is separated from the culture within 10 minutes can be harvested quickly and simply.

In order to measure the efficiency of the aggregation reaction, the optical density (OD, optical density) of the culture medium before and after the aggregation reaction was measured at a wavelength of 680 nm, and two repeated experiments were performed to increase the accuracy. Coagulation efficiency was calculated by the following formula.

Coagulation efficiency (%) = (OD before reaction-OD after reaction) / OD X 100 before reaction

As a result of the calculation, the flocculation efficiency using combustion flue gas in the photobioreactor of the present invention was very high as 93% or more, and the flocculation harvesting method of the present invention using combustion flue gas can quickly and easily harvest cultured microalgae and produce The process can be simplified.

In addition, by cultivating the sensedus mousse of the combustion algae resistance microalgae using the combustion flue gas, it is possible to reduce the carbon dioxide emitted into the atmosphere by using carbon dioxide as a carbon source of photosynthesis.

As described above, the photobioreactor according to the present invention and the cultivation method and harvesting method using the same according to the present invention is to induce uniform agitation of the culture solution by aeration using a gas such as carbon dioxide or air for the production of general microalgae in addition to the combustion flue gas. It is possible through this, it is possible to enable the production of general microalgae as well as microalgae of combustion exhaust gas resistance.

While the invention has been shown and described with respect to certain preferred embodiments thereof, the invention is not limited to these embodiments, and has been claimed by those of ordinary skill in the art to which the invention pertains. It includes all the various forms of embodiments that can be implemented without departing from the spirit.

1 is a schematic view showing an embodiment of a photobioreactor according to the present invention

Figure 2 is a graph showing the growth curve of Senedmus cultivated using various types of photobioreactor

Figure 3 is a photo of incubating for eight days the sensedmus by supplying the combustion flue gas to the funnel-type photobioreactor according to the present invention

Figure 4 is a graph showing the comparison of the content of lipids extracted from the cinemusmus cultured using various types of photobioreactors

Figure 5 is a photocoagulation reaction using a coagulant and a biopolymer after incubating the sendes mousse in a photobioreactor

<Description of the symbols for the main parts of the drawings>

11: culture tank

13: stopper

15: gas injection pipe

17: gas discharge pipe

19: regulating valve

Claims (8)

Funnel-shaped culture tank (11); A gas injection pipe 15 coupled to the lower end of the culture tank 11; A stopper 13 detachably provided at an upper end of the culture tank 11; A gas discharge pipe 17 penetrating through the stopper 13 and having one end disposed in the culture tank 11; Photobioreactor comprising a. The method according to claim 1, The material of the gas injection pipe 15 is a photobioreactor, characterized in that silicon. The method according to claim 1, Optical bioreactor characterized in that the control valve 19 is further configured between the culture tank (11) and the gas injection pipe (15). The method according to claim 1, The material of the culture tank 11 is a photobioreactor, characterized in that the glass. In the microalgae culture method using the photobioreactor of any one of claims 1 to 4, A microalgal culture method comprising supplying a gas source containing a photosynthetic carbon source to the culture fluid to flow upward, and agitating the culture solution mixed with microalgae. The method according to claim 5, Microalgae culturing method characterized in that the cultivation of Senedus mousse using the combustion exhaust gas as a gas source containing the carbon source of photosynthesis. In the microalgae harvesting method using the photobioreactor of any one of claims 1 to 4, Adding a flocculant to the culture medium in which the microalgae have been cultured; Supplying a gas source including a photosynthetic carbon source to the culture fluid to flow upward; Microalgae harvesting method characterized in that to harvest the microalgae cultured in the photobioreactor including. The method of claim 7, The step of adding the flocculant, After adding a coagulant to the culture as a primary and supplying a gas source containing a photosynthetic carbon source, and after standing for a predetermined time, a coagulant is added to the culture medium a second time and a gas source containing a photosynthetic carbon source is supplied as a secondary solution. Microalgae harvesting method characterized in that the stirring.

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