CN110938533B - Bioreactor for microalgae facultative growth mode culture and working method thereof - Google Patents

Abstract

The invention relates to a bioreactor for cultivating microalgae in a facultative growth mode and a working method thereof, wherein the bioreactor mainly comprises a reaction tank, a diversion tank is arranged below the reaction tank, and the bottom of the reaction tank is communicated and connected with the diversion tank through a transparent glass column pipe; the transparent glass column tube comprises a middle glass column tube and an outer glass column tube, an axial flow paddle which pushes water flow in the middle glass column tube to flow towards one end of the diversion tank when the middle glass column tube rotates is arranged in the middle glass column tube, and the axial flow paddle is fixed on the rotating shaft and is in transmission connection with the motor. The working method comprises the following steps: introducing microalgae liquid into the reaction tank through the inoculation port, starting the motor, driving the axial flow paddle to push the culture solution in the middle glass column tube to flow into the flow guide tank from the reaction tank, supplying oxygen to the interior of the tube through the middle gas-liquid jet device, improving the content of dissolved oxygen in the culture solution, and then flowing back into the reaction tank through the outer glass column tube by the flow guide tank, circulating in the way, and simultaneously, matching the LED lamp to illuminate the outer glass column tube to meet the requirement of microalgae facultative growth on illumination, thereby realizing the facultative culture of microalgae.

Description

Bioreactor for cultivation of microalgae in facultative growth mode and working method thereof

technical field

The invention relates to the field of microalgae cultivation, and relates to a bioreactor for microalgae facultative growth mode cultivation and a working method thereof.

Background technique

Microalgae is a kind of tiny organisms that can rely on photosynthesis for growth. It is rich in protein, chlorophyll, carotenoids, vitamins and other nutrients. It is widely used in biomedicine, food and food additives, feed and animal health care, aquatic products farming and other industries. The vast majority of microalgae can use light energy and organic carbon sources (chemical energy) to grow at the same time, which is called facultative growth, also known as mixed trophic growth. In general, the facultative growth rate of most microalgae is the sum of their photoautotrophic and chemoheterotrophic growth rates. The facultative culture mode of microalgae has the advantages of fast growth rate, high biomass concentration, and high production efficiency. However, the facultative culture mode of microalgae has not been widely promoted and applied at present. The main reason is the lack of a A bioreactor suitable for the facultative cultivation of microalgae.

At present, there are mainly three types of bioreactors used for facultative culture of microalgae: 1) small-scale (about 5L or 10L) transparent glass fermenter; 2) adding lamp tubes inside the stainless steel fermenter; 3) stainless steel fermenter Holes on the surface (transparent glass installed, external lights added). The problem of above-mentioned three kinds of devices is: the scale of the first type reactor is too small, is generally used in laboratory scale, can't be used as large-scale production equipment; The high temperature and high pressure conditions during sterilization (high temperature 115-121°C, high pressure 1.1kg/cm ² ), considering the safety of the fermenter, there is a problem of limited number of lamps, which makes the illumination area (or illumination volume) in the fermentation tank insufficient , it is difficult to meet the growth needs of microalgae; the third type is to open holes on the surface of the stainless steel fermenter, install a transparent glass sight glass, and install lights externally. There are also rigidity and safety requirements for the fermentation tank sterilization, the number of holes Limited, so that the light area in the fermenter is insufficient. Since the facultative growth of photosynthetic microalgae requires light conditions and a sterile culture environment at the same time, and the light area cannot be too small (because the light decays exponentially in the algae liquid, a larger light area is required to ensure that the microalgae are in the facultative culture process. Therefore, there is currently no culture device that is very suitable for efficient facultative culture of microalgae and is easy to scale up.

In addition, in order to obtain active substances in microalgae, it is necessary to switch between multiple growth modes during the culture of microalgae. For example, in order to allow Chlorella to accumulate lutein, a heterotrophic-photoautotrophic tandem mode is usually used. The heterotrophic mode (fermentation) quickly obtains a large amount of chlorella biomass, and then uses light for photoautotrophy, so that the algal cells can quickly synthesize and accumulate lutein. Since the above-mentioned second and third types add light to the inside and outside of the fermenter respectively, they cannot supplement light in a large area, and insufficient light makes it impossible for microalgae to induce the synthesis of lutein. Therefore, there is currently no bioreactor device capable of large-scale application that can switch microalgae between multiple growth modes.

In view of the above situation, it is necessary to design a reactor device that can efficiently cultivate microalgae and can switch growth modes according to the needs of microalgae growth.

Contents of the invention

In order to overcome the above-mentioned deficiencies, the purpose of the present invention is to provide a kind of bioreactor and working method thereof for microalgae facultative growth model cultivation to the art, so that it can solve the problem of the existing similar reactor facultatively cultivating microalgae with relatively low efficiency. Low, and it is inconvenient to switch the growth mode according to the needs of microalgae growth, and it is not easy to scale up and apply technical problems. Its purpose is achieved through the following technical solutions.

A bioreactor used for cultivating microalgae in a facultative growth mode. The main body of the bioreactor is a reaction tank, and an inoculation port and an exhaust pipe are arranged on the top of the reaction tank. The key point of its structure is that a diversion tank is set under the reaction tank, and the bottom of the diversion tank is provided with a discharge and sewage outlet. The inner cavity of the flow tank is communicated through a transparent glass column tube; the transparent glass column tube includes a middle glass column tube and an outer glass column tube uniformly distributed in a ring along the circumference of the middle glass column tube, wherein the middle glass column tube is connected to the center of the bottom of the reaction tank and the guide tube. The center of the top of the flow tank is connected, and the middle glass column tube is equipped with an axial flow paddle that pushes the water in the middle glass column tube to flow toward one end of the diversion tank when rotating. The axial flow paddle is fixed on the rotating shaft, and the rotating shaft extends to the top of the reaction tank to drive and connect the motor. Through the above structure, the bioreactor is divided into the upper reaction tank and the lower transparent glass column tube. Using the light transmittance of the transparent glass column tube and coordinating with the axial flow paddles in the middle glass column tube, it not only has a large illumination area , to meet the needs of microalgae growth for light energy, and at the same time have good fluid mixing and mass transfer performance, so that the microalgae in the bioreactor can form a circulating flow among the reaction tank, transparent glass column tube, and diversion tube. Meet the requirements of facultative culture of microalgae, effectively improve the growth rate of microalgae and increase output.

The middle glass column tube is composed of an upper section and a lower section, the upper end of the upper section communicates with the center of the bottom of the reaction tank, the lower end of the lower section communicates with the center of the top of the diversion tank, and the upper section and the lower section communicate through a gas-liquid jet device connection, the gas-liquid jet device is provided with a jet channel with a diameter smaller than the diameter of the intermediate glass column tube, and a vent hole is provided on the wall of the jet channel, and the vent hole is externally connected to a gas supply device. Through this structure, it is beneficial to enhance the gas-liquid mass transfer coefficient in the reactor, and significantly increase the dissolved oxygen content in the culture medium without increasing the rotation speed and ventilation of the stirring paddle, so as to meet the oxygen demand of high-density growth of microalgae , to increase the concentration of microalgae culture.

Both the upper end and the lower end of the gas-liquid jet device form flange joints, and the lower end of the upper section and the upper end of the lower section of the intermediate glass column tube are provided with flange ends corresponding to the flange joints of the gas-liquid jet device. An elastic gasket is placed between the joint and the flange end to form a fixed connection through bolts and nuts; the wall of the jet channel of the gas-liquid jet device is equipped with at least three ventilation holes along the circular direction, and the outer surface of the jet channel is provided with conduction holes. The annular pipelines of each ventilation hole are externally connected to the gas supply equipment through the ventilation pipelines. With this structure, the installation of the gas-liquid jet device is facilitated, and the gas supply effect is better.

Both the bottom of the reaction tank and the top of the diversion tank are provided with flange joints connected to the corresponding transparent glass column tubes, and both ends of the transparent glass column tubes are provided with flange ends connected to the flange joints. An elastic gasket is placed between the ends of the flanges to form a fixed connection through bolts and nuts. Through this structure, the transparent glass column tube, the reaction tank and the draft tube have a certain expansion and contraction ability, so that it can effectively cope with the high temperature expansion state when the bioreactor is subjected to steam high temperature sterilization, and ensure the safety of use.

An elliptical arc inner cavity is formed in the diversion tank to ensure the smoothness of the diversion in the diversion tube, reduce resistance, and reduce the proportion of dead zones (areas where microalgae are easy to deposit).

The periphery of the bioreactor is evenly distributed with LED lamps for supplementing light to the outer glass column tube and the middle glass column tube. Through the LED light, the microalgae in the transparent glass column tube can be supplemented with light in time in an environment with insufficient light, so as to ensure the growth efficiency of the microalgae.

The outer surface of the guide tank is provided with a heat exchange jacket for heat exchange with the inside of the guide tank. Through this structure, the external cold and heat exchange medium flows into the heat exchange jacket, thereby forming effective heat exchange in the draft tube, which is beneficial to maintaining a reasonable temperature inside the bioreactor.

The reaction tank is provided with a temperature sensor, a pH sensor, and a dissolved oxygen sensor for respectively monitoring temperature, pH value, and dissolved oxygen value. Therefore, real-time monitoring of the internal environment and the cultivation process of the bioreactor is facilitated, and operating conditions and processes are adjusted in time.

There are at least four outer glass column tubes, and there are distances between adjacent outer glass column tubes and between the outer glass column tubes and the middle glass column tubes. Easy installation, maintenance and cleaning operations through reasonable clearance.

The working method of the bioreactor for microalgae facultative growth mode cultivation is as follows: the microalgae seed liquid is passed into the reaction tank from the inoculation port through the flame inoculation method or the pressure difference inoculation method of the inoculation tank, the motor is turned on, and the motor drives the shaft The flow paddle pushes the culture solution in the middle glass column tube to flow from the reaction tank to the diversion tank, and after passing through the middle gas-liquid jet device, the gas-liquid jet device supplies oxygen to the middle glass column tube to increase the dissolved oxygen content in the culture solution. Then the diversion tank flows back into the reaction tank through the outer glass column tube, and the cycle is like this; when the external light is insufficient, the external glass column tube is illuminated by the auxiliary LED lamp to meet the light requirements of the facultative growth of microalgae To realize the synthesis of light-induced bioactive substances in algae cells, and realize the facultative culture of microalgae in the bioreactor by the above method.

The overall structure of the present invention is relatively compact and reasonable, safe and reliable in use, suitable for facultative cultivation of microalgae, and the growth mode can be switched according to the growth needs of microalgae, so that the growth rate of microalgae is high, the bioconcentration is high, and the output is high. The method realizes the scale-up and application of microalgae cultivation, and is suitable for use as a bioreactor for microalgae cultivation, or as a structural improvement of similar reactors.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention, and part is cut-away among the figure.

Fig. 2 is a schematic diagram of the structure of the distribution state of the outer glass column tube and the inner glass column tube relative to the bottom of the reaction tank according to the present invention.

Fig. 3 is that the outer glass column tubes of Fig. 2 are increased from four to eight.

Fig. 4 is a schematic cross-sectional structure diagram of the gas-liquid jet device of the present invention, in which A-A cross-section is made in the figure.

Fig. 5 is a schematic diagram of the cross-sectional structure of A-A in Fig. 4

The serial numbers and names in the figure are: 1. reaction tank, 101, inoculation port, 102, exhaust pipe, 103, spare port, 2, middle glass column tube, 201, upper section, 202, lower section, 3, outer glass column tube, 4. Diversion tank, 401. Discharge and sewage outlet, 5. Heat exchange jacket, 6. Axial flow paddle, 7. Rotating shaft, 8. Motor, 9. Air-liquid jet device, 901. Ventilation duct, 10. Temperature sensor , 11, pH sensor, 12, dissolved oxygen sensor, 13, elastic gasket, 14, LED light.

detailed description

Now in conjunction with accompanying drawing, the present invention will be further described.

As shown in Fig. 1, Fig. 2, Fig. 4, and Fig. 5, the main body of this bioreactor is a reaction tank 1 made of stainless steel, and the top of the reaction tank is provided with an inoculation port 101 and a spare port 103 for feeding, and for discharging Gas exhaust pipe 102, the exhaust pipe is provided with an exhaust valve. The bottom of the reaction tank is provided with a stainless steel diversion tank 4 with an elliptical arc inner cavity. The bottom of the diversion tank is provided with a discharge and sewage outlet 401. A diaphragm valve is arranged below the discharge and sewage outlet, which is closed in the initial state. The bottom of the reaction tank and the diversion tank are connected through a transparent glass column tube resistant to high temperature and high pressure. The transparent glass column tube is made of quartz glass tube or high borosilicate glass tube. A flange joint that is docked with the corresponding transparent glass column tube. Both ends of the transparent glass column tube are provided with flange ends connected to the flange joint. An elastic gasket 13 is placed between the flange joint and the flange end. A fixed connection is formed by bolts and nuts. Through the above connection, the inner cavity of the reaction tank and the inner cavity of the diversion tank are communicated through the transparent glass column tube. The transparent glass column tube includes an intermediate glass column tube 2 and four outer glass column tubes 3 uniformly distributed in a circular shape along the circumference of the intermediate glass column tube. The tubes are spaced apart to facilitate disassembly, maintenance or cleaning operations. The middle glass column tube is composed of an upper section 201 and a lower section 202. The upper end of the upper section communicates with the center of the bottom of the reaction tank, the lower end of the lower section communicates with the center of the top of the diversion tank, and the upper section and the lower section are connected through a gas-liquid jet device 9. The gas-liquid jet device is a stainless steel sleeve structure. The upper and lower ends of the gas-liquid jet device form flange joints. The middle part is equipped with a jet channel with a diameter smaller than the diameter of the middle glass column tube. The flange joints at both ends connect to the jet channel in the middle. Tapered gradient. The wall of the jet channel is evenly distributed along the ring with three ventilation holes 902, and the outer surface of the wall of the jet channel is welded with an annular pipeline 903 leading to each ventilation hole. The device supplies sterile air to the air-liquid jet device. The lower end of the upper section and the upper end of the lower section of the middle glass column tube are provided with flange ends that are fixedly connected to the flange joints of the gas-liquid jet device. An elastic gasket is placed between the flange joints and the flange ends, and the bolts and nuts are passed through Form a permanent connection.

The upper section 201 of the above-mentioned middle glass column tube 2 is provided with an axial flow paddle 6 that pushes the culture solution in the middle glass column tube to flow toward one end of the diversion tank 4 when rotating. 7. The rotating shaft extends to the top of the reaction tank to drive and connect to the motor 8. The top of the reaction tank is provided with a shaft positioning seat for piercing and positioning and rotating the rotating shaft, and a motor bracket for fixedly connecting the motor.

In order to timely supplement light to the microalgae in the transparent glass column tube in an environment with insufficient light, LED lamps 14 for supplementing light on the outer glass column tube 2 and the middle glass column tube 1 are evenly distributed around the periphery of the bioreactor. LED lights are placed as needed and can be removed when not needed.

In order to facilitate the detection of the cultivation environment in the bioreactor and to adjust the temperature inside the bioreactor, a temperature sensor 10, a pH sensor 11, and a dissolved oxygen sensor are installed in the reaction tank 1 to monitor the temperature, pH value, and dissolved oxygen value respectively. 12. The outer surface of the diversion tank 4 is provided with a heat exchange jacket 5 for heat exchange with the interior of the diversion tank. In this way, the external cold and heat exchange medium flows into the heat exchange jacket to form an effective heat exchange in the draft tube and realize the adjustment of the internal temperature.

The working method of the bioreactor for microalgae facultative growth mode cultivation is:

First, the bioreactor is cleaned, the pH sensor 11, the dissolved oxygen sensor 12 and the temperature sensor 10 are calibrated and installed, and the inorganic salts and organic carbon sources (such as Glucose) and other nutrients and water are formulated into the medium with the concentration required for the growth of microalgae. Close all valves except the exhaust valve installed on the exhaust pipe 102, and directly feed steam through the heat exchange jacket 5, so that the temperature of the culture medium rises to about 90-100°C; then open the ventilation duct 901 and the sewage drain Feed port 401, and steam is passed into the bioreactor through the ventilation duct and the sewage discharge port, so that the temperature of the medium rises to 121 ° C, and the high temperature is maintained for 20 minutes for steam disinfection. Add cooling water to cool down to the temperature required for the growth of microalgae (generally 25-35°C).

Then, turn on the external auxiliary LED lamp 14 to illuminate the outer glass column tube 3 (the number and light intensity of the LEDs are adjusted according to the growth conditions of the microalgae), so as to meet the needs of the growth of the microalgae. Pass the microalgae species into the reaction tank 1 through the inoculation port 101, turn on the motor 8, and the motor drives the axial flow paddle 6 to push the water in the middle glass column tube 2 to flow from the reaction tank to the diversion tank 4, and pass through the middle gas-liquid After the jet device 9, the gas-liquid jet device supplies oxygen to the middle glass column tube, so that the culture medium can obtain sufficient dissolved oxygen, and then the diversion tank passes through the outer glass column tube 3 to return to the upper reaction tank to achieve sufficient mixing , to facilitate the growth of microalgae and the absorption of nutrients. The flow circulation of the above-mentioned medium realizes efficient facultative culture of microalgae, thereby increasing the growth rate of microalgae and increasing the yield. When the cultivation is completed, turn off the motor, and open the diaphragm valve of the discharge outlet at the bottom of the diversion tank to realize the discharge operation.

As shown in FIG. 3 , the number of outer glass column tubes 3 can also be set to other numbers, such as eight, as required. The bioreactor can be enlarged by increasing the diameter of the glass tube column, the height of the glass tube column and the number of the glass tube column, so as to solve the problem of difficult enlargement of the bioreactor. The above content is intended to illustrate the technical means of the present invention, but not to limit the technical scope of the present invention. Those skilled in the art make obvious improvements or replacements to the present invention in combination with the existing common knowledge, such as changing the size and material of the reaction tank, the middle glass column tube, the outer glass column tube, the diversion tank, etc., all fall within the scope of the claims of the present invention within the scope of protection.

Claims (8)

1. A bioreactor for microalgae facultative growth mode cultivation, the main body of the bioreactor is a reaction tank (1), and the top of the reaction tank is provided with an inoculation port (101) and an exhaust pipe (102); It is characterized in that a diversion tank (4) is set under the reaction tank (1), and a discharge outlet (401) is provided at the bottom of the diversion tank, and the bottom of the reaction tank and the diversion tank are connected through a transparent glass column tube, That is, the inner cavity of the reaction tank and the inner cavity of the diversion tank are connected through a transparent glass column tube; the transparent glass column tube includes a middle glass column tube (2) and an outer glass column tube (3) that is uniformly distributed in a ring along the circumference of the middle glass column tube , wherein the middle glass column tube is connected with the bottom center of the reaction tank and the top center of the diversion tank, and the middle glass column tube is provided with an axial flow paddle (6) that pushes the fluid in the middle glass column tube to flow toward one end of the diversion tank when rotating, and the axial flow The paddle is fixed on the rotating shaft (7), and the rotating shaft extends to the top of the reaction tank to drive and connect the motor (8); the middle glass column tube is composed of an upper section (201) and a lower section (202), and the upper end of the upper section is connected to the center of the bottom of the reaction tank. The lower end of the lower section is connected to the center of the top of the diversion tank, and the upper section and the lower section are connected through a gas-liquid jet device (9). The inner diameter of the gas-liquid jet device is smaller than the diameter of the middle glass column tube. The jet channel, the wall of the jet channel is provided with vent holes, and the vent holes are externally connected to the gas supply equipment; the periphery of the bioreactor is evenly distributed with LED lights (14) for supplementing the light of the outer glass column tube and the middle glass column tube . 2. The bioreactor for microalgae facultative growth mode cultivation according to claim 1, characterized in that the upper and lower ends of the gas-liquid jet device (9) form flange joints, and the middle glass column The lower end of the upper section and the upper end of the lower section of the pipe (2) are provided with flange ends corresponding to the flange joints of the gas-liquid jet device, and an elastic gasket (13) is placed between the flange joints and the flange ends. Bolts and nuts form a fixed connection; the wall of the jet channel of the gas-liquid jet device is provided with at least three ventilation holes (902) along the circular direction, and the outer surface of the jet channel is provided with an annular pipeline (903) leading to each ventilation hole. The pipeline is externally connected to the gas supply equipment through a ventilation pipeline (901). 3. The bioreactor for microalgae facultative growth mode cultivation according to claim 1, characterized in that the bottom of the reaction tank (1) and the top of the diversion tank (4) are equipped with corresponding transparent glass columns The flange joints where the pipes are connected, the two ends of the transparent glass column tube are provided with flange ends connected to the flange joints, and an elastic gasket (13) is placed between the flange joints and the flange ends, and then the bolts, The nut forms a fixed connection. 4. The bioreactor for cultivating microalgae in a facultative growth mode according to claim 1, characterized in that an elliptical arc inner cavity is formed in the diversion tank (4). 5. The bioreactor for microalgae facultative growth mode cultivation according to claim 1, characterized in that the outer surface of the diversion tank (4) is provided with a heat exchanger for forming heat exchange with the inside of the diversion tank. Thermal jacket (5). 6. The bioreactor for microalgae facultative growth mode cultivation according to claim 1, characterized in that the reaction tank is equipped with temperature sensors (10), pH Sensor (11), dissolved oxygen sensor (12). 7. The bioreactor for cultivating microalgae in facultative growth mode according to claim 1, characterized in that there are at least four outer glass column tubes (3), and there are between adjacent outer glass column tubes And there is a distance between the outer glass column tube and the middle glass column tube (2). 8. A working method of the bioreactor used for microalgae facultative growth pattern cultivation as claimed in claim 1, characterized in that the working method is: the microalgae seed liquid is inoculated by flame inoculation mode or inoculation tank pressure difference The method is to pass the inoculation port (101) into the reaction tank (1), turn on the motor (8), and the motor drives the axial flow paddle (6) to push the culture medium in the middle glass column tube (2) to flow from the reaction tank to the flow tank (4 ), after passing through the middle gas-liquid jet device (9), the gas-liquid jet device supplies oxygen to the middle glass column tube to increase the dissolved oxygen content in the culture medium, and then the diversion tank passes through the outer glass column tube (3) Backflow into the reaction tank, so that the cycle is continuous; when the external light is insufficient, the auxiliary LED lamp (14) is used to supplement the light on the external glass column tube to meet the needs of microalgae for the facultative growth of light, and to realize the algal cell growth. Internal light induces the synthesis of biologically active substances, and the facultative culture of microalgae in the bioreactor is realized by the above method.

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