KR100311057B1 - Photo-bioreactor and method for culturing photosynthetic bacteria using the same - Google Patents

Abstract

The present invention relates to a bioreactor for culturing microorganisms grown by photosynthesis and a method for culturing photosynthetic microorganisms using the same, and an internal cycle type optical organism for solving low light utilization efficiency and temperature control problems, which are the main problems of the photobioreactor. It relates to a reactor and a method of culturing photosynthetic microorganisms using the same.

Conventionally, in the country with four seasons, the internal temperature cannot be maintained according to the external temperature, and thus it is impossible to culture photosynthetic microorganisms.

Therefore, the present invention is to install a heat exchanger in the circulation tube formed inside the vertical tubular reactor for culturing photosynthetic microorganisms to control the internal temperature irrespective of the outside temperature and to configure the photosynthetic microorganisms to circulate, the lower side of the circulation tube It forms a circulation hole so that the photosynthetic microorganism is circulated and installs an air circulation plate formed with a circulation hole in the lower side of the vertical tubular reactor from the outside of the circulation tube so that air is supplied to the wall of the vertical tubular reactor. It is installed at one third of the diameter of the vertical tubular reactor to allow the cultivation of photosynthetic microorganisms regardless of the outside temperature.

Description

Internal Circulation Type Photobioreactor and Culture Method of Photosynthetic Microorganism Using the Same

The present invention relates to a bioreactor for culturing microorganisms grown by photosynthesis and a method of culturing photosynthetic microorganisms using the same, and an internal circulation type optical organism for solving low light utilization efficiency and temperature control problems, which are the main problems of the photobioreactor. It relates to a reactor and a method of culturing photosynthetic microorganisms using the same.

Microalgae cultivation is used to produce useful substances such as feed, food coloring and pharmaceutical raw materials.

Recently, as industrial emission CO ₂ is pointed out as the main culprit of global warming, research is being actively conducted to utilize microalgae to fix CO ₂ .

Currently, the microalgae culture tanks commercialized are all lake-type reactors, which are actually used only in some countries such as the United States, Australia, and Israel, and are difficult to apply in Japan and Korea, where it is difficult to secure a site for reactor installation.

In addition, the temperature suitable for culturing microalgae is about 25 ° C.-35 ° C., and in Korea with four seasons, it is possible to cultivate algae algae for only a few months (early May-early October) during the year.

Research is actively underway to develop reactors that can be used in difficult-to-finish locations (ie, high algal growth rates per unit area).

Vertical tubular reactors with a cylindrical tube vertically have a land area required to produce the same amount of microalgae due to its geometry, which is 1/20 or less compared to that of a lake-type reactor, resulting in high cell productivity per unit area. In countries where there is no idle land, the possibility of commercialization is high.

There are many problems that must be solved in order to install and operate a large scale microalgae culture process outdoors using such a vertical tubular reactor.

First, in the case of outdoor cultivation, the microalgae cultivation temperature changes according to the outside temperature, so the cultivation temperature should be maintained at 25 ° C.-35 ° C., which is suitable for the growth of microalgae.

However, all of the microalgal cultures developed to date are commercially operated only in winter-free regions due to the lack of temperature control.

Application of the currently developed microalgal culture tank is difficult in regions with winters such as Korea.

Second, when the concentration of microalgae in the reactor is increased, the cells inside the reactor have less chance to absorb light than the cells on the outside due to the shadow effect by the cells themselves.

Therefore, designing the reactor so that all microorganisms can be uniformly exposed to light can increase the microalgae productivity of the reactor.

However, until now, as a result of the agitation and stirring of the medium to supply gas, the microalgae cells are randomly exposed to light, and the concentration of the microalgae cells increases to decrease the utilization efficiency of the light. There is a problem.

Therefore, even when the concentration of microalgae is high, in order to improve the light utilization efficiency, all microalgae need a device that can be uniformly exposed to light.

In the conventional tubular reactor, a jacket is attached to the outer wall of the reactor to control the temperature in the reactor, and a method of supplying the jacket with hot / cold water for controlling the temperature is used. Cause There is a problem of reducing the growth rate of photosynthetic microorganisms by reducing the transmittance of light by more than 30%.

The present invention is to install a heat exchanger inside the reactor and to install the air-lift reactor (drught tube) in the form of a tube (drught tube) to circulate the form of the exchanger to the internal temperature regardless of the outside temperature It is possible to increase the growth rate of microalgae more than about 20% compared to the vertical tubular reactor which is not equipped with a circulation tube at the same culture conditions that all weather operation is possible by adjusting to the optimum value.

When microalgae absorb light above a certain intensity, excess light is stored in the body, allowing photosynthesis to continue for a short time even if the light supply is interrupted.

In addition, the intensity of solar light is about 20 times the maximum light intensity that microalgae can digest, so if the microalgae in the reactor is exposed to sunlight for some time and moved to the place where there is no light, surplus stored in the cell without light By utilizing light energy, it can grow with photosynthesis until it uses up the surplus light energy.

Therefore, other cells that have not sufficiently absorbed solar light in the reactor can be exposed to sunlight, thereby increasing the utilization efficiency of light.

The present invention provides a heat exchanger for controlling the temperature of the microorganism culture medium in the reactor so that the temperature in the reactor is maintained at a temperature suitable for the culture of photosynthetic microorganisms.

The present invention is capable of outdoor cultivation regardless of the season in the form of a circulation tube so that the cells can be circulated in the form of a heat exchanger to increase the light utilization efficiency of the cells.

1 is a state diagram of the optical bioreactor of the present invention

Figure 2 is an installation state showing the operating principle of the internal circulation optical bioreactor of the present invention

Degree

Figure 3 is a graph showing the growth rate of the strain in the bubble column reactor and the internal circulation optical bioreactor of the present invention

Figure 4 is a graph recording the temperature of the internal circulation optical bioreactor of the present invention

5 is a graph for the growth test results of the strain using the optical bioreactor outdoors in the winter of the present invention

1: reactor 2: heat exchanger

3: air dispersion plate 4: air inlet

5: constant temperature circulator 6: flow control valve

7: cold, hot water inlet 13: circulation tube

14: circulation hole 15: air injection hole

Microorganisms applicable to the present invention are all photosynthetic microorganisms that require light for metabolic activity, and are not limited to the specific microorganisms exemplified in the present invention.

1 and 2, which are examples of the internal circulation vertical tubular reactor according to the present invention.

In order to increase the chance of exposure to light of the cells in the reactor, a circulation tube 13 was formed to allow microorganisms to circulate in the vertical tubular reactor 1, and a circulation hole 14 was installed at the bottom of the circulation tube 13.

When exposed to light, the carbon dioxide gas is installed at the lower side of the vertical tubular reactor 1 so that the carbon dioxide gas is supplied to the outside of the circulation tube 13 so that the lower side of the circulation tube 13 is blocked and the efficiency of photosynthesis on the outside is provided. In order to raise the air distribution plate (3) having an air inlet (15) was installed to rise along the wall of the vertical tubular reactor (1).

The heat exchanger (2) is installed in the circulation pipe (13), and the inside is hollow, and the cold and hot water outlet (9) of the upper side is installed and connected to the constant temperature circulator (5) and the flow control valve (6) in the constant temperature circulator (5). Connect to the cold, hot water inlet (7) on the lower side.

A thermocouple 8 is installed on the wall of the vertical tubular reactor 1 so as to be connected to the temperature controller 10 and connected to the temperature recorder 11 so that the temperature in the reactor can be controlled by cold and hot water.

According to the present invention having the above configuration, the vertical tubular reactor 1 is supplied to the outside through the air inlet 4 while being supplied to the outside of the circulation pipe 13 by the air inlet 15 of the air distribution plate 3. When exposed to carbon dioxide gas to increase the efficiency of photosynthesis, photosynthetic microorganisms that rise along the walls of the vertical tubular reactor (1) and absorbed enough microorganisms enter the interior from the top of the circulation tube (13).

However, the inside of the circulation tube 13 and the light supply is cut off from the inside, but when exposed to the light it is possible to continue the growth activity using the surplus light energy stored in the cells.

The microalgal cells reaching the lower end of the circulation tube 13 are moved to the outside through the circulation hole 14 to be exposed to sunlight again to absorb the light necessary for growth.

Therefore, all the cells in the vertical tubular reactor (1) is circulated and evenly exposed to light can increase the utilization efficiency of light.

This function is particularly useful when the concentration of microalgal cells is high.

When the concentration of microalgae is 1g / 1, the depth of sunlight can penetrate only about 3 ~ 4cm.

Therefore, the gap between the inner wall of the reactor and the outer wall of the circulation pipe was found to be most suitable when sufficient light was supplied.

In the case of the circulation tube, the growth rate of the microorganism was the highest when the tube was located at 1/3 of the reactor diameter.

Example 1

Chlorella mutant KR-1 (patent pending) isolated from a Pyrex glass 8L vertical tubular reactor (inner diameter 12 cm x height 80 cm) was incubated.

The medium was prepared by dissolving 5 g of KNO ₃ , 2.5 g of MgSO ₄ 7H ₂ O, 1.25 g of KH ₂ PO ₄ , and 1 ml of a trace reagent in 1 L of distilled water.

The trace reagent is 14.5 mg NaFeEDTA, 2.86 mg H ₃ BO ₃ , 2.5 mg MnSO ₄ 7H ₂ O 2.5 mg, 0.222 mg ZnSO ₄ 7H ₂ O, 0.079 mg CuSO ₄ 5H ₂ O, 0.021 mg Na ₂ MoO ₄ in 1 L distilled water. It was prepared by.

5 L of the medium was sterilized in a high pressure sterilizer, placed in a reactor, and incubated by inoculating Chlorella KR-1.

Light was supplied as a fluorescent lamp, the amount of light energy supplied to the reactor was 180 μmol / ㎡-sec, carbon dioxide gas was supplied at 0.3vvm, and the culture medium was maintained at 25 ° C. for 7 days.

The degree of growth of the microorganisms was expressed by a standard curve of absorbance-dry weight based on the dry weight of the cells prepared by separating and harvesting the culture medium and drying at 105 ° C. for 24 hours.

In the case of using the reactor of the present invention, it was about 1.2 times higher than a simple bubble column reactor (bubble column) without an internal circulation tube operated under the same conditions. (See FIG. 3).

Example 2. Temperature Control Experiments of Photobioreactors.

Temperature control experiments were carried out outdoors in winter with 8 L (inner diameter 12 cm × height 80 cm) and 20 L (inner diameter 20 cm × 80 cm) vertical tubular reactors.

Both reactors were able to maintain the temperature in the reactor at 30 ° C.-35 ° C. suitable for microalgae cultivation regardless of the outside temperature by appropriately adjusting the temperature and circulation flow rate of the thermostat. (See FIG. 4).

Example 3 Outdoor Culture Experiments of Photosynthetic Microorganisms in a Photobioreactor.

In winter, chlorella KR-1 was incubated in sunlight using 8 L and 20 L vertical tubular reactors outdoors.

The out-of-composition medium described above was used and 10% CO ₂ gas was supplied at a flow rate of 0.3vvm.

In the same operating conditions, the microorganisms were not grown at all without temperature control, whereas in the 8L and 20L reactors equipped with internal circulation tubes, the cell concentrations at the end of the culture were 3.34g / L and 2.22g / L, respectively. The average cell productivity was 0.39g / L-day and 0.23g / L-day, respectively. (See FIG. 5).

Since the cell productivity was maintained at 25 ° C. in a well-controlled room, the average cell productivity obtained when cultivated was little different from that of 0.404 g / L-day (based on 8 L reactor). Show that you lost.

The present invention is a vertical tube of the microalgae culture reactor to significantly reduce the cross-sectional area required for the installation of the process, as it circulates inside the reactor and rises along the wall of the reactor and absorbs enough light and enters the circulation tube after blocking the light. However, when exposed to light, the surplus light energy stored in the cells can be used to continue the growth activity.

The present invention is to install a heat exchanger to control the internal temperature to a temperature suitable for cultivation, so that outdoor cultivation is possible regardless of the external temperature or season, and greatly improved the applicability of the microalgal culture process.

Claims (4)

A heat exchanger is installed in a circulation tube formed inside a vertical tubular reactor for culturing photosynthetic microorganisms to control the internal temperature regardless of the outside temperature, and to configure the photosynthetic microorganisms to circulate. By forming a circulation hole in the lower side of the circulation tube is configured to circulate photosynthetic microorganisms, An internal circulation vertical optical bioreactor configured to supply air to the walls of the vertical tubular reactor by installing an air dispersion plate having an air inlet formed below the vertical tubular reactor from the outside of the circulation tube. The internal circulation vertical optical bioreactor of claim 1, wherein the circulation tube is configured to maintain a spacing between the reactor inner wall and the outer tube outer wall of 2 to 4 cm. The internal circulation vertical optical bioreactor of claim 1, wherein the circulation tube is installed at one third of the diameter of the vertical tubular reactor. By installing a circulation tube formed with a circulation hole in the lower side inside the vertical tubular reactor, while maintaining a temperature of 25 ~ 30 ℃ by a heat exchanger to supply air from the lower side to allow the microorganisms to circulate the circulation tube to cultivate high concentration of photosynthetic microorganisms Method for culturing photosynthetic microorganisms using an internal circulation vertical optical bioreactor to enable it.