CN114276922A - A kind of shallow liquid layer quasi-static microalgae culture system and using method - Google Patents

Abstract

The invention discloses a shallow liquid layer quasi-static microalgae culture system and a use method thereof, wherein the shallow liquid layer quasi-static microalgae culture system comprises the following steps: the culture tank is used for containing microalgae and a culture solution; the exchange column is communicated with the culture tank through a first connecting pipe and is used for accommodating a culture solution, and one end of the first connecting pipe, which extends into the exchange column, is provided with a liquid level height adjusting part; the pipeline circulating driving structure comprises a second connecting pipe, a third connecting pipe and a first pump, wherein one end of the second connecting pipe is communicated with the exchange column, the other end of the second connecting pipe is communicated with one end of the third connecting pipe, the other end of the third connecting pipe is communicated with the culture tank, and the first pump is arranged on the second connecting pipe; the gas mixing device is communicated with the bottom of the exchange column through a fourth connecting pipe; the temperature adjusting device is used for adjusting the temperature of the culture solution in the exchange column; and the light supplementing device is positioned beside the culture tank and used for supplementing light for the microalgae in the culture tank. The invention has the characteristics of water saving and energy saving, and can be applied to the industrial production of microalgae and various fields of carbon neutralization.

Description

A kind of shallow liquid layer quasi-static microalgae culture system and using method

technical field

The present application relates to the field of microalgae biotechnology, and in particular, to a quasi-static microalgae culture system in a shallow liquid layer and a method for using the same.

Background technique

Microalgae is a general term for a class of microorganisms that contain chlorophyll a and can perform photosynthesis. The cells usually contain high value-added products such as protein, oil, polyunsaturated fatty acids, polysaccharides, natural pigments, and vitamins. Therefore, they have extremely high value and are used in food. It has been widely used in industries such as feed, cosmetics, etc., and has potential application prospects in carbon neutral fields such as biological carbon sequestration, sewage treatment (pollution reduction and carbon reduction), biofuel, bioplastic and biofertilizer production.

There are more than 20,000 species of microalgae known at present, but few of them have been industrialized. The bottleneck restricting the microalgae industry is the poor economy caused by the low utilization rate of light energy and the low cultivation efficiency. The photobioreactor is an important basis for microalgae cultivation. At present, photobioreactors mainly include open type (runway pool, round pool, etc.) and closed type (tube type, horizontal tube type, flat type, hanging bag type, etc.) two kinds. However, they all have the disadvantages of low cell density, low productivity, and water and energy consumption. The low density will inevitably result in a large volume of production water, which will increase the energy consumption and cost of recovery. Water consumption, especially a large amount of fresh water, causes waste of culture medium and water resources on the one hand, and pollutes the surrounding receiving water bodies on the other hand. Although the closed reactor can increase the cell density, it has the problems of difficulty in scale-up and high cost. Therefore, the efficiency of photoautotrophic culture of microalgae needs to be improved to further reduce the production cost.

SUMMARY OF THE INVENTION

The purpose of the embodiments of the present application is to provide a quasi-static microalgae culture system in a shallow liquid layer and a method for using the same, so as to solve the technical problems of insufficient single cell light reception, low algal cell yield, water consumption and energy consumption existing in the related art .

According to a first aspect of the embodiments of the present application, there is provided a quasi-static microalgae cultivation system in a shallow liquid layer, comprising:

Cultivation tank, used to accommodate microalgae and culture medium;

an exchange column, which is communicated with the culture tank through a first connecting pipe, and is used for accommodating the culture liquid, and one end of the first connecting pipe extending into the exchange column is provided with a liquid level height adjusting member;

The pipeline circulation drive structure includes a second connecting pipe, a third connecting pipe and a first pump, one end of the second connecting pipe is communicated with the exchange column, and the other end is communicated with one end of the third connecting pipe , the other end of the third connecting pipe is communicated with the culture tank, and the first pump is arranged on the second connecting pipe;

a gas mixing device, communicated with the bottom of the exchange column through a fourth connecting pipe;

a temperature adjusting device for adjusting the temperature of the culture solution inside the exchange column; and

A supplementary light device, located beside the cultivation tank, is used for supplementing light to the microalgae in the cultivation tank.

Further, the upper end of the exchange column is cylindrical, and the lower end is conical.

Further, a liquid replenishing device is also included, and the liquid replenishing device communicates with the exchange column through a fifth connecting pipe.

Further, the rehydration device includes:

a first rehydration tank for replenishing sterile water, and

The second liquid replenishment tank used for supplementing the culture medium, wherein one end of the fifth connecting pipe is communicated with the first liquid replenishment tank and the second liquid replenishment tank respectively, and the other end is connected to the exchange column.

Further, a liquid collecting device is also included, and the liquid collecting device includes:

a first collection tank for collecting supernatant;

a sixth connecting pipe, one end of which is communicated with the first liquid collecting tank, and the other end is connected at the connection between the second connecting pipe and the third connecting pipe;

The second pump and the first valve are arranged on the sixth connecting pipe, and the second pump and the first valve are arranged in parallel;

A second collection tank for collecting concentrated algal liquid;

a seventh connecting pipe, one end of which is communicated with the second liquid collecting tank, and the other end is connected at the connection between the second connecting pipe and the third connecting pipe; and

The second valve is arranged on the seventh connecting pipe.

Further, the gas mixing device includes:

_CO2 source and air source, and

The mixer is communicated with the CO ₂ source and the air source respectively, and communicates with the bottom of the exchange column through the fourth connecting pipe after mixing the two.

Further, the supplementary light device includes:

light stand, and

A light source mounted on the light stand.

Further, the temperature adjustment device includes:

an exchange coil disposed within the exchange column; and

a heat exchanger, communicated with the exchange coil.

Further, it also includes: a sensor installed on the exchange column.

According to a second aspect of the embodiments of the present application, there is provided a method for using the above-mentioned shallow liquid layer quasi-static microalgae culture system, including:

Step S1. configure a culture medium in the rehydration device, add a culture system, and form a shallow liquid layer;

Step S2. Inoculate algal cells into the culture tank of the culture system;

Step S3. Let stand first to realize algal cell sedimentation, let the algal cells adhere to the bottom surface of the culture tank and stand for culture;

Step S4. start the first pump, the clear liquid flows into the culture tank through the second connecting pipe and the third connecting pipe to realize quasi-static cultivation, and the ventilation in the exchange column is realized by the gas mixing device to realize the analysis of carbon supplement and oxygen, and adjust the light supplement device;

Step S5. to the end of the culture, first collect the supernatant to the first collection tank, then collect the shallow algal mud in the culture tank to the second collection tank, and the collected supernatant is pumped to the culture system by the second, Part of the algal cells contained therein are used as the inoculum to start the first pump and continue to cultivate;

The above steps S3 to S5 are repeated, and the volume of the reaction system is supplemented with the medium in the liquid replenishing device as needed.

The technical solutions provided by the embodiments of the present application may include the following beneficial effects:

Compared with the prior art, the present invention realizes a shallow liquid layer by flexibly adjusting the liquid level height, avoids the problem that the conventional shallow liquid layer is easily evaporated and dried up, realizes automatic liquid replenishment and maintains the liquid level depth, and realizes the growth of microalgae in the culture tank. Shallow liquid layer cultivation saves water and medium, and at the same time, it can achieve primary concentration after cultivation, save the cost of recovery, realize gas-liquid mass transfer, dissolve CO ₂ and analyze oxygen, realize heat exchange, and maintain the temperature of the culture medium. No stirring device is required, energy is saved, and algal cells are quasi-statically cultured. The nutrient supply to algal cells and the exchange of metabolites are realized through the flow of clear liquid, and the growth environment of algal cells is maintained. By coupling the pH to the aeration system, _CO replenishment is achieved while a stable pH is achieved. It realizes stable automatic control, and is equipped with automatic monitoring of temperature, pH and dissolved oxygen, monitoring the culture environment at any time and making appropriate adjustments, which is conducive to the realization of factory and automatic culture. Improve control accuracy. The production time is not affected by seasons, weather, day and night, the exposure intensity of microalgae is controllable, the growth efficiency of microalgae is greatly improved, and it has broad prospects in microalgae carbon fixation and microalgae industrial production.

To sum up, the technical solutions provided by the embodiments of the present application may include the following beneficial effects: (1) improving the yield of algal cells; (2) facilitating the concentration and harvesting of algal liquid; (3) enabling continuous industrialization and automation (4) The culture medium can be reused, saving water and energy.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not limiting of the present application.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

FIG. 1 is a schematic structural diagram of a shallow liquid layer quasi-static microalgae culture system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of the assembly of the first connecting pipe and the elbow according to the embodiment of the present invention, wherein (a) is a front view, (b) is a left view, and (c) is a top view.

Fig. 3 is the effect of the depth of the shallow liquid layer on the final cell density and the yield per unit area in Examples 1-4 of the present invention.

The reference numbers in the figure are:

1. Cultivation tank;

2. Exchange column;

3. Liquid replenishing device; 31. First liquid replenishing tank; 32. Second liquid replenishing tank; 33. Flow control valve.

4. Liquid collecting device; 41. The first liquid collecting tank; 42, The second liquid collecting tank; 43, The sixth connecting pipe; 44, The first valve; 45, The second pump; 46, The second valve; 47, The first Seven connecting pipes;

5. Gas mixing device; 51. _CO2 source; 52. Air source; 53. Mixer;

6. Lighting device; 61. Lamp stand; 62. Light source;

7. The first connecting pipe; 71. The liquid level height adjustment piece;

8. The fifth connecting pipe;

9. Pipeline circulation drive structure; 91. The second connecting pipe; 92. The third connecting pipe; 93. The first pump

10. The fourth connecting pipe;

11. Exchange coils;

12, sensor; 121, temperature probe; 122, pH probe; 123, dissolved oxygen electrode; 124, liquid level electrode.

Detailed ways

Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. Where the following description refers to the drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the illustrative examples below are not intended to represent all implementations consistent with this application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as recited in the appended claims.

The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application and the appended claims, the singular forms "a," "the," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It will also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited by these terms. These terms are only used to distinguish the same type of information from each other. For example, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information without departing from the scope of the present application. Depending on the context, the word "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determining."

In the photobioreactor, the light-harvesting characteristics and self-shading effect of microalgal cells that can perform photosynthesis cause the algal fluid to have significant light attenuation characteristics, and the penetration of light in it is poor. Exponential decay trends, especially for large-volume photobioreactors, where most of the microalgae are usually in a light-limited state, with low utilization of light energy and stunted growth. The conventional solution is to increase the mixing to promote the circulation of algal cells in the light and dark interval to achieve uniform light reception. However, when the water body is large, in order to maintain uniform mixing, a large amount of power consumption is required, and the density of algae cells is usually low, so the mixing of a very small proportion of microalgae has to be achieved by mixing a large volume of water body, and the vast majority of what is done is done. Part of it is "useless work". In addition, a considerable number of microalgae, especially those without cell walls or flagellated microalgae, are sensitive to shear force, and increasing mixing will affect the viability of microalgae.

On the other hand, the growth of microalgae depends on the water environment. Nutrients and CO ₂ need to rely on the flow and mass transfer of the water body to realize the material exchange between the algal cells and the culture environment. The algal cells also need a buffer system and an osmotic environment to maintain their own shape and ensure The normal progress of intracellular biochemical reactions. Based on the above characteristics, some studies have proposed new culture methods such as semi-dry attachment. However, if dehydration occurs, the growth and division of algal cells will be stagnant or even die. In addition, the surface moisture is easily caused by factors such as evaporation. It is beneficial to the steady-state culture of algal cells.

To sum up, the inventors believe that the core of microalgae culture is to increase the light-receiving area and enhance the availability of light energy to a single cell. The lower dissolved oxygen concentration ensures the water environment for microalgae cultivation to achieve sufficient supply of other nutrients. For the optimization of photobioreactors, improving the light-receiving area/volume ratio is the key.

Example 1:

Referring to FIG. 1 , an embodiment of the present invention provides a quasi-static microalgae culture system in a shallow liquid layer. The system may include: a culture tank 1, an exchange column 2, a gas mixing device 5, a pipeline circulation drive structure 9, and a temperature adjustment device and fill light device 6.

The culture tank 1 is used to accommodate microalgae and culture solution; specifically, the culture tank 1 can be a horizontally placed cuboid container (length, width and height are respectively 100cm×100cm×10cm, which can be fixed by a bracket with a height of 100cm. .

The exchange column 2 is communicated with the culture tank 1 through a first connecting pipe 7 for accommodating the culture liquid, and accelerating heat and mass transfer by bubbling, and the first connecting pipe 7 extends into the exchange column 2 There is a liquid level height adjusting member 71 at one end; the depth of the shallow liquid layer in the culture tank 1 can be adjusted by adjusting the angle of the liquid level height adjusting member 71 at the end of the first connecting pipe 7, generally maintaining the culture tank The shallow liquid layer in 1 has a depth of 1 cm and below. Specifically, the liquid level height adjusting member 71 can be an elbow, or can be a telescopic assembly formed by a plurality of tubes nested in sequence, and the height can be adjusted through expansion and contraction; this example is taken as an example, referring to FIG. 2 , the elbow It is screwed to one end of the first connecting pipe 7, and the depth of the shallow liquid layer in the culture tank 1 can be adjusted by adjusting the rotation angle.

The upper end of the exchange column 2 is cylindrical, and the lower end is conical. Specifically, the exchange column 2 is cylindrical, with a height of 120 cm, an outer diameter of 14 cm, a wall thickness of 5 mm, a cone-shaped bottom, and a cone height of 15 cm. The exchange column 2 is fixed by a bracket.

The pipeline circulation driving structure 9 includes a second connecting pipe 91, a third connecting pipe 92 and a first pump 93. One end of the second connecting pipe 91 is communicated with the exchange column 2, and the other end is connected with the third connecting pipe 91. One end of the connecting pipe 92 is connected to each other, the other end of the third connecting pipe 92 is connected to the culture tank 1 , and the first pump 93 is arranged on the second connecting pipe 91 . By activating the first pump 93 , the culture fluid can be circulated through the exchange column 2 , the second connection pipe 91 , the third connection pipe 92 , the culture tank 1 , the first connection pipe 7 and the exchange column 2 in sequence.

Also include a liquid replenishing device 3, the liquid replenishing device 3 is communicated with the exchange column 2 through the fifth connecting pipe 8, and is mainly used to supply the exchange column 2 with water lost due to evaporation or supplementary culture medium, and can also be used. After the replacement, proceed to the next replenishment culture.

Specifically, the rehydration device 3 may include: a first rehydration tank 31 for supplementing sterile water, and a second rehydration tank 32 for supplementing culture medium, wherein one end of the fifth connecting pipe 8 is respectively connected to the The first liquid replenishment tank 31 is communicated with the second liquid replenishment tank 32 , and the other end is connected to the exchange column 2 . Further, in order to better control the amount of replenishment, flow control valves may be installed in the first fluid replenishment tank 31 and the second fluid replenishment tank 32 .

A liquid collecting device 4 is also included, and the liquid collecting device 4 is used for harvesting at the end of the cultivation and reuse of the supernatant after harvesting, and is not activated during the normal cultivation operation.

Specifically, the liquid collecting device 4 includes: a first liquid collecting tank 41, a second liquid collecting tank 42, a sixth connecting pipe 43, a first valve 44, a second pump 45, a second valve 46, and a seventh connecting pipe 47. The first collecting tank 41 is used to collect the supernatant; one end of the sixth connecting pipe 43 is communicated with the first collecting tank 41 , and the other end is connected between the second connecting pipe 91 and the third connecting pipe 92 . connection; the second pump 45 and the first valve 44 are arranged on the sixth connecting pipe 43, and the second pump 45 and the first valve 44 are arranged in parallel; the second liquid collecting tank 42 is used to collect concentrated algal liquid; the seventh One end of the connecting pipe 47 is connected to the second liquid collecting tank 42 , and the other end is connected to the connection between the second connecting pipe 91 and the third connecting pipe 92 ; the second valve 46 is arranged on the seventh connecting pipe 47 superior.

During normal cultivation, the second pump 45 , the first valve 44 and the second valve 46 are closed, and the first pump 93 is opened. When the clear liquid is collected to the first liquid collecting tank 41 , the second pump 45 and the second valve 46 are closed, and the first valve 44 and the first pump 93 are opened. When the concentrated algal liquid is collected to the second liquid collection tank 42, the concentrated algal liquid is transferred to the exchange column 2 through the first connecting pipe 7, the first valve 44 and the second pump 45 are closed, and the first pump 93 and the second valve 46 are opened. . When the clear liquid collected in the first liquid collection tank 41 needs to be returned to the culture system due to recycling, close the first valve 44, the second valve 46 and the first pump 93, open the second pump 45 until the delivery is completed, and then close the second valve. Pump 45. The direction of the arrow shown in the figure is the delivery direction of the pump. The gas mixing device 5 is communicated with the bottom of the exchange column 2 through the fourth connecting pipe 10, and the gas mixing device 5 is used to realize the stable supply of carbon source CO ₂ , and the CO ₂ and air are mixed to reach the set volume. Then, the culture medium was passed into it to improve the dissolution rate and utilization rate of CO ₂ .

Specifically, the gas mixing device 5 includes: a CO ₂ source 51, an air source 52 and a mixer 53, and the mixer 53 is communicated with the CO ₂ source 51 and the air source 52 respectively, and the two are mixed and passed through The fourth connecting pipe 10 communicates with the bottom of the exchange column 2 . The CO ₂ source 51 and the air source 52 are mixed by the mixer 53 to adjust and control a reasonable CO ₂ concentration ratio, which is preferably 2.5%.

The supplementary light device 6 is located beside the culture tank 1 and is used for supplementing light to the microalgae in the culture tank 1 .

Specifically, the supplementary light device 6 includes: a lamp frame 61 and a light source 62 mounted on the lamp frame 61 . Further, the light intensity of the light source 62 is 20-400 μmol photons m ^-2 s ^-1 .

Specifically, the light source 62 can be an LED lamp or the like, and the light intensity is preferably 50 μmol photons m ^-2 s ^-1 .

The temperature adjustment device is used to adjust the temperature of the culture liquid inside the exchange column, and specifically, the temperature adjustment device may include an exchange coil 11 and a heat exchanger.

The exchange coil 11 is arranged in the exchange column 2, and the heat exchanger communicates with the exchange coil. Further, the diameter of the exchange coil 11 is 1 cm, the diameter of the spiral is 12 cm, the spacing between the spirals is 2 mm, and the height of the coil is 40 cm. The exchange coil 11 is a copper tube, and its inlet and outlet are connected to a heat exchanger (not shown), and the heat exchange is realized by the flow of heat transfer medium water (hot water or ice water) in the tube, so that the temperature of the culture solution is constant. At 25 ~ 28 ℃.

In order to monitor the cultivation process parameters (temperature, pH, dissolved oxygen, liquid level, etc.) online in real time, the microalgae cultivation system further includes: a sensor 12 installed on the exchange column 2 .

In this example, the sensor 12 may include a temperature probe 121 for detecting the temperature of the culture solution in the exchange column 2, a pH probe 122 for detecting the pH value of the culture solution in the exchange column 2, and a pH probe 122 for detecting the pH value of the culture solution in the exchange column 2. The dissolved oxygen electrode 123 for dissolved oxygen in the culture solution in the exchange column 2 and the liquid level electrode 124 for detecting the liquid level of the culture solution in the exchange column 2 are provided.

Further, the temperature probe 121 can be used for feedback control of the exchange coil 11; the pH probe 122 and the dissolved oxygen electrode 123 can be used for feedback control of the gas mixing device 5; the liquid level electrode 124 can be used for feedback The rehydration device 3 is controlled.

The culturing tank 1 and the exchange column 2 are made of high light-transmitting plexiglass material, which is convenient for observation on the one hand, and light-transmitting on the other hand, so as to facilitate photosynthesis.

The embodiment of the present invention also provides a method for using a quasi-static microalgae cultivation system in a shallow liquid layer, the method may include:

S1. configure a culture medium in the rehydration device 3, add a culture system, and form a shallow liquid layer;

S2. inoculate algal cells into the culture tank 1 of the culture system;

S3. First let stand to achieve algal cell sedimentation, let the algal cells adhere to the bottom surface of the culture tank 1 and stand for culture;

S4. start the first pump 93, the clear liquid flows into the culture tank 1 through the second connecting pipe 91 and the third connecting pipe 92 to realize quasi-static culture, and the gas mixing device 5 is ventilated into the exchange column 2 to realize the analysis of carbon supplementation and oxygen, Adjust the supplementary light device 6;

S5. To the end of the cultivation, first collect the supernatant to the first liquid collection tank 41 , and then collect the shallow algal sludge in the culture tank 1 to the second liquid collection tank 42 . The collected supernatant is sent to the culture system by the second pump 45, and the part of the algal cells contained therein is used as the inoculum, and the first pump 93 is started to continue the culture;

The above steps S3 to S5 are repeated, and the volume of the reaction system is supplemented with the medium in the liquid replenishing device 3 as needed.

The working principle of the embodiment of the present invention is: using the sedimentation characteristics of algal cells combined with their growth characteristics, most of the algal cells stay at the bottom of the culture tank 1 first, and the culture clear liquid containing the culture medium circulates in the entire reactor, The relative movement between the algal cells and the culture solution is formed, the exchange of nutrients and metabolites is realized, and the liquid environment for the growth of algal cells is maintained. utilization rate. The specific operation process is:

By adding filter-sterilized medium into the culture tank 1 and the exchange column 2, and by adjusting the height of the first connecting pipe 7 in the vertical direction of the exchange column 2, the liquid level in the culture tank 1 is maintained The depth is 10mm and below, inoculate the algal cells at a volume ratio of 10% and let stand for 12h, and then start the first pump 93 (at this time, the second pump 45 is stopped, the first valve 44 and the second valve 46 are closed), so that the supernatant is Circulate between the culture tank 1 and the exchange column 2, the liquid replenishing device 3 is coupled with the monitoring of the liquid level electrode 124, when the liquid level is lower than the set value, add sterile water until the liquid level reaches the set value, the gas mixing device 5 Coupled with pH electrode monitoring, when the pH value is higher than the set value, start aeration until the pH drops to the set value ± 0.5, and automatically cultivate until the algal cell concentration increases slowly, adjust the elbow port downward, and open the first The valve 44 collects the clear liquid in the exchange column 2 and the culture tank 1 through the first liquid collection tank 41, then closes the first valve 44, starts the second valve 46, and cleans the part of the algal sludge attached to the culture tank 1 and exchanges it through the valve 44. The column 2 and the second connecting pipe 91 are collected in the second collecting tank 42, then the first pump 93 and the second valve 46 are closed, and the supernatant in the first collecting tank 41 is transferred to the culture through the second pump 45 Tank 1 and exchange column 2. Then turn off the second pump 45, start and continue the circulatory culture via the first pump 93, the liquid level electrode 124 gives a replenishment signal, open the flow control valve, and replenish the microalgae culture medium to the entire culture system until the set liquid level. Start the first pump 93 and the supplementary light device 6 to start a new round of cultivation.

The flow of the heat transfer medium in the heat exchanger and the circulating coil is coupled with the electrical signal of the temperature electrode. When the temperature is higher than the set value, the circulation of the cooling liquid is started to achieve cooling. Once the set temperature value is reached, the cooling is stopped. fluid circulation. When the microalgae culture system is placed in a lower temperature environment, when the temperature is lower than the set value, the circulation of the thermal fluid is started to realize the temperature rise, and once the set temperature value is reached, the circulation of the thermal fluid is stopped.

The microalgae cultivation process using the shallow liquid layer quasi-static microalgae cultivation system according to the embodiment of the present invention mainly includes three steps: pre-cultivation preparation, cultivation and post-cultivation treatment, wherein the pre-cultivation preparation includes a reactor (including pipelines) , pumps and valves) sterilization, preparation of a specific volume of culture medium according to the recipe, autoclave sterilization or filtration sterilization, culture includes inoculation, process automatic control and sample detection, post-culture treatment mainly includes algal liquid (pulp) collection Collection, supernatant reuse and other steps.

For the determination methods of dry cell weight and algal cell number described in this specification, please refer to relevant textbooks and published literature materials. More specifically, dry cell weight was determined by weight difference method; cell number was obtained by hemocytometer method.

Comparative Example 1

Select the exchange column 2 in embodiment 1 (a cylinder made of high light-transmitting plexiglass material, height 120cm, outer diameter 14cm, wall thickness 5mm, the bottom is a cone, the cone height is 15cm, the exchange column 2 is fixed by the bracket, and the sensor 12 includes A temperature probe 121, a pH probe 122, a dissolved oxygen electrode 123 and a liquid level electrode 124, an exchange coil 11 is provided in the exchange column 2, the pipe diameter is 1 cm, the spiral diameter is 12 cm, the spiral spacing is 2 mm, and the coil height is 40 cm) as a control A column reactor was used, the volume of the reactor liquid was 10L, and the light intensity on the surface of the reactor was 50 μmol photons m ^-2 s ^-1 , and freshwater Chlorella vulgaris was cultivated in this reactor. 1. The difference is that the bubble culture is started immediately after inoculation. After 4 days of culture, the algal cell density was 1.25 g L ^-1 , and the cell yield was 0.24 g L ^-1 d ^-1 .

Comparative Example 2

The culture tank 1 in Example 1 (a horizontally placed rectangular parallelepiped container (length, width and height respectively 100cm×100cm×10cm)) was selected as the control reactor, and the connection hole between it and the exchange column 2 was closed. Keeping the culture liquid level at 10mm, the reactor filling volume at 10L, and the light intensity on the surface of the reactor at 50μmol photons m ^-2 s ^-1 , the freshwater chlorella Chlorella vulgaris was cultured statically in the reactor. See Example 1 for the culture medium. Immediately after inoculation, stationary culture was started. The amount of evaporated water was supplemented every day, and the initial pH of the culture solution was 7.5 by aeration. The pH was not adjusted during the culture process, and the room temperature was maintained at 28±1°C. After 4 days of culture, the algal cell density was 0.55g L ^-1 , and the cell yield was 0.06g L ^-1 d ^-1 , the yield per unit area is 0.63 gm ^-2 d ^-1 .

Comparative Example 3

Select a conventional experimental runway pool (size: the length, width and height of the main body are 140cm x 50cm x 40cm respectively, there is a partition in the middle along the length direction, a web wheel stirring paddle is installed on one side of the partition, and the two ends of the runway pool are semi-circular; material: PP ) as a comparative reactor, in which the freshwater Chlorella vulgaris was cultured, and the culture medium was BG-11 medium with NaNO ₃ as the nitrogen source. The liquid level height is 20cm, the liquid filling volume is 180L, and the stirring speed is 15rpm, so that the average overall flow rate of the culture solution is about 0.05ms ^-1 , and the upper part is filled with light, so that the light intensity at the liquid level is 50μmol photons m ^-2 s ^-1 , and the seeding density is 0.3 g L ^-1 . A mixture of air and carbon dioxide with a volume fraction of 2% CO ₂ was introduced, the ventilation volume was 18L min ^-1 , and the culture temperature was controlled to be 28±1°C. After 7 days of culture, the algal cell density was 0.38 g L ^-1 , the cell yield was 0.011 g L ^-1 d ^-1 , and the unit area yield was 2.94 gm ^-2 d ^-1 .

Example 1

Before use, spray 75% alcohol on the inner surfaces of culture tank 1 and exchange column 2 (amount of 20-30 mL m ^-2 ), then dry it, and then use sodium hypochlorite aqueous solution to immerse and disinfect the reactor and pipeline, with an effective chlorine concentration of 100 ppm , soaking time 1～2h, then add 10～25ppm sodium thiosulfate in the water body for neutralization, until the iodine test paper does not change color, the above water is 0.22μm membrane filtered water. Freshwater Chlorella vulgaris is cultivated in this system, the culture medium is BG-11 medium with NaNO ₃ as nitrogen source, and the medium is configured in the rehydration tank 32 . By adjusting the rotation angle of the left elbow of the connecting pipe, adjust the depth of the liquid level in the culture tank 1 to 5mm, the total liquid volume to 15L (5L in the culture tank 1 and 10L in the exchange column 2), and the seeding density to be 0.3g L ^-1 . After inoculation, the culture tank 1 was left to stand for 12 hours without pump circulation and pH adjustment. Then, the first pump 93 was turned on, the pump flow rate was 400L h ^-1 , and the air containing CO ₂ with a volume fraction of 2.5% carbon dioxide was introduced. Mixed gas, in which air is provided by air compressor, and CO ₂ is provided by liquefied steel cylinder gas, the two are mixed in proportion by gas mixing device 5 and then supplied with gas, the ventilation volume is 2L min ^-1 , pH=7.5±0.5, control The incubation temperature was 28±1°C. After culturing for 4 days, adjust the liquid level to adjust the elbow downward, first recover the clear liquid (13L) to the liquid collection tank 41, and then collect the attached algal sludge to obtain concentrated algal slurry (2L) to the liquid collection tank 42. The final cell density reached 23.6 g L ^-1 , and the cell density in the supernatant was 0.7 g L ^-1 , so the equivalent cell volume density was 3.75 g L ^-1 , and the area yield was 12.95 gm ^-2 d ^-1 . During the experiment, the daily evaporation was about 1L, and sterile water was automatically replenished from the liquid replenishment tank 31 through the liquid level electrode 124 and its feedback control system. Due to the constant indoor temperature, the heat exchange coil 11 was not used in this example.

Example 2

The configuration of the culture system and the culture method were the same as those in Example 1. Others remain unchanged. By adjusting the rotation angle of the elbow at the end of the first connecting pipe 7, the depth of the liquid level in the culture tank 1 is adjusted to 10mm, and the liquid filling volume is 20L (10L in the culture tank 1 and 10L in the exchange column 2). ), observe the culture results, collect the clear liquid (18L) after the culture, and then collect the attached algal mud to obtain concentrated algal pulp (2L), the final density of algal cells in the algal pulp reaches 32.5g L ^-1 , and the cell density in the clear liquid is 0.1 g L ^-1 , so the equivalent cell volume density is 3.34 g L ¹ and the area yield is 15.2 gm ^-2 d ^-1 .

Example 3

The configuration of the culture system and the culture method were the same as those in Example 1. Others remain unchanged. By adjusting the rotation angle of the elbow at the end of the first connecting pipe 7, the depth of the liquid level in the culture tank 1 is adjusted to 15mm, and the liquid filling volume is 25L (15L in the culture tank 1 and 10L in the exchange column 2). ), observe the culture results, collect the clear liquid (23L) after the culture, then collect the attached algal mud to obtain the concentrated algal slurry (2L), the final density of algal cells in the algal pulp reaches 30.7g L ^-1 , and the cell density in the clear liquid is 0.1 g L ^-1 , so the equivalent cell volume density is 2.55 g L ^-1 , and the area yield is 14.05 gm ^-2 d ^-1 .

Example 4

The configuration of the culture system and the culture method were the same as those in Example 1. Others remain unchanged. By adjusting the rotation angle of the elbow at the end of the first connecting pipe 7, the liquid level depth in the culture tank 1 is adjusted to 30mm, and the liquid filling volume is 40L (30L in the culture tank 1 and 10L in the exchange column 2). ), observe the culture result, collect clear liquid (38L) after culture, collect the attached algal mud to obtain concentrated algal pulp (2L), the final density of algal cells in the algal pulp is 20.8g L ^-1 , and the cell density in the clear liquid is 0.1 g L ^-1 , so the equivalent cell volume density is 1.14 g L ^-1 , and the area yield is 8.35 gm ^-2 d ^-1 .

Example 5

The configuration of the culture system and the culture method were the same as those in Example 1. Others remain unchanged. By adjusting the rotation angle of the elbow at the end of the first connecting pipe 7, the liquid level depth in the culture tank 1 is adjusted to 60mm, and the liquid filling volume is 70L (60L in the culture tank 1 and 10L in the exchange column 2). ), observe the culturing results, collect clear liquid (68L) after culturing, then collect the attached algal mud to obtain concentrated algal slurry (2L), the final density of algal cells in the algal pulp is 13.2g L ^-1 , and the cell density in the clear liquid is 0.05 g L ^-1 , so the equivalent cell volume density is 0.43 g L ^-1 , and the area yield is 2.20 gm ^-2 d ^-1 . It was observed that the color of the algal fluid was significantly different from Examples 1 to 4, showing a tan color.

Example 6

The culture system is shown in Figure 1. The culture tank 11 is a horizontally placed cuboid container (length, width and height are respectively 300cm×300cm×10cm), and the material used is 10mm thick high light-transmitting plexiglass, which passes through an aluminum alloy bracket with a height of 100cm. For fixing, the exchange column 2 is a cylinder made of high light-transmitting plexiglass, with a height of 120cm, an outer diameter of 40cm, a wall thickness of 5mm, and a tapered bottom. , dissolved oxygen electrode 123 and liquid level electrode 124, the exchange column 2 is provided with an exchange coil 11, the pipe diameter is 1cm, the spiral diameter is 36cm, the spiral spacing is 2mm, and the coil height is 40cm. and the second liquid replenishment tank 32, wherein the first liquid replenishment tank 31 is filled with sterile water, and the second liquid replenishment tank 32 is filled with culture medium; the liquid collection device includes the first liquid collection tank 41 and the second liquid collection tank 42, wherein the first liquid collection tank 42 The tank 41 is mainly used for collecting supernatant liquid, and the second liquid collecting tank 42 is mainly used for collecting concentrated algal liquid. The gas mixing device 5 adjusts the mixing ratio of CO ₂ and air and adjusts the flow of the two to control a reasonable CO ₂ concentration ratio of 2%, and the ventilation volume is 0.2vvm. There are 9 rows of LED light racks 61 placed nearby, the light intensity is adjustable, and the light intensity on the surface of the culture tank 1 is controlled to be 50 μmol photons m ^-2 s ^-1 .

Before use, spray 75% alcohol on the inner surfaces of culture tank 1 and exchange column 2 (amount of 20-30 mL m ^-2 ), then dry it, and then use sodium hypochlorite aqueous solution to immerse and disinfect the reactor and pipeline, with an effective chlorine concentration of 100 ppm , soaking time 1～2h, then add 10～25ppm sodium thiosulfate in the water body for neutralization, until the iodine test paper does not change color, the above water is 0.22μm membrane filtered water. In this system, freshwater Chlorella vulgaris is cultivated, and the culture medium is BG-11 medium with NaNO ₃ as a nitrogen source, and the medium is configured in the second replenishment tank 32 . The total liquid volume was 180 L (90 L in each of the culture tank 1 and the exchange column 2), and the seeding density was 0.3 g L ^-1 . After inoculation, the culture tank 1 was left to stand for 12 hours without pump circulation and pH adjustment, and then the first pump 93 was turned on, the pump flow rate was 4000L h ^-1 , and the air containing carbon dioxide with a volume fraction of 2% CO ₂ was introduced Mixed gas, in which the air is provided by the air compressor, and the CO ₂ is provided by the ^liquefied steel cylinder gas. The two are mixed in proportion by the gas mixing device 5 and then supplied to the gas. The incubation temperature was 28±1°C. After culturing for 4 days, open the first valve 44, adjust the liquid level and adjust the elbow to face down, first recover the clear liquid (about 160L) to the first liquid collection tank 41, and then collect the attached algal sludge to obtain concentrated algal slurry (20L). In the second liquid collection tank 42, the final density of algal cells in the algal pulp reaches 30.2 g L ^-1 , and the cell density in the supernatant is 0.1 g L ^-1 , so the equivalent cell volume density is 3.44 g L ^-1 , and the area yield is 15.7 gm ^{- 2d -1} . During the experiment, the daily evaporation was about 10L, and sterile water was automatically added from the first replenishment tank 31 through the liquid level electrode 124 and its feedback control system. The experimental season was autumn. The heat exchanger is connected to the exchange coil 11 for maintaining the culture temperature.

Example 7

The configuration of the culture system and the culture method were the same as those in Example 2. Others remained unchanged, the pump was changed to a circulating pump with a flow rate of 4000L h ^-1 , which significantly shortened the circulation period of the culture supernatant, and the culture results were observed. First recover the clear liquid (about 18L), and then collect the attached algal mud to obtain concentrated algal slurry (2L). The final density of algal cells in the algal slurry reaches 28.5g L ^-1 , and the cell density in the clear liquid is 0.25gL ^-1 , so it is equivalent to The cell volume density was 3.07 g L ^-1 and the area yield was 13.88 gm ^-2 d ^-1 .

Example 8

The configuration of the culture system is the same as that of Example 2. For the culture method, refer to Example 2. In this system, Nannochloropsis sp. was cultured, and the culture medium was an improved ASW medium with sodium nitrate as the nitrogen source. The initial seeding density was 0.3 g L ^-1 , the culture temperature was controlled at 25±1°C, and the culture light intensity was adjusted to 100 μmol photons m ^-2 s ^-1 . After culturing for 4 days, open the first valve 44, adjust the liquid level and adjust the elbow to face down, first recover the clear liquid (about 18L), then collect the attached algal sludge to obtain concentrated algal slurry (2L), and the final density of algal cells in the algal slurry is 25.8 g L ^-1 was reached, the cell density in the supernatant was 0.3 g L ^-1 , so the equivalent cell volume density was 2.85 g L ^-1 , and the area yield was 12.75 gm ^-2 d ^-1 .

Example 9

The culture system and method are the same as those in Example 7. The recovered 18L supernatant is circulated back to the culture system through the pump, and 2L of initial culture medium is added through the second rehydration tank 32. After standing for 12h, the first pump 93 is started, and the flow rate is 400L h ^-1 , and the culture is continued to control. The incubation temperature was 25±1°C. After culturing for 4 days, open the first valve 44, adjust the liquid level and adjust the elbow to face down, first recover the clear liquid (about 18L), then collect the attached algal sludge to obtain concentrated algal slurry (2L), and the final density of algal cells in the algal slurry is 20.8 g L ^-1 was reached, the cell density in the supernatant was 0.35 g L ^-1 , so the equivalent cell volume density was 2.40 g L ^-1 , and the area yield was 10.48 gm ^{- 2} d ^-1 .

Example 10

The configuration of the culture system is the same as that of Example 2, and the culture method is with reference to Example 2. In this system, microalgae with flagella are cultivated, and marine microalgae ball Isochrysis galbana is selected, and the nutrient solution is f/ 2 Seawater culture medium, seawater salinity 36‰. The light intensity was controlled at 20 μmol photons m ^-2 s ^-1 and the culture temperature was controlled at 25±1°C. The initial number of cells in culture is 1.5×10 ⁶ cells mL ^-1 . After 7 days of culture, open the first valve 44 , adjust the liquid level and adjust the elbow to face down, first recover the supernatant (about 18L), and then collect the attached algal mud to obtain concentrated Algal pulp (2L), the final density of algal cells in the algal pulp reaches 90.5×10 ⁶ cells mL ^-1 , and the cell density in the supernatant is 2.0×10 ⁶ cells mL ^-1 , so the equivalent volume of cells is 10.85×10 ⁶ cells mL -1 ^{- 1} , the biomass was 7.23 times the initial inoculum. Microscopic observation showed that the cell morphology was intact, most of the cells still had flagellar structure, and a small part formed spore state.

Example 11

The configuration of the culture system is the same as that of Example 2, and the culture method refers to Example 2. In this system, the freshwater diatom Navicula that is easily attached is cultured, and the culture medium is CSI culture with calcium nitrate and potassium nitrate as nitrogen sources and sodium silicate added. base. The light intensity was controlled at 20 μmol photons m ^-2 s ^-1 and the culture temperature was controlled at 25±1°C. The initial number of cells in culture was 1.2×10 ⁶ cellsmL ^-1 . After 7 days of culture, open the first valve 44 , adjust the liquid level and adjust the elbow to face down, first recover the supernatant (18.8L), and then collect the attached algal mud to obtain concentrated algae Plasma (1.2L), the final density of algal cells in the algal plasma reaches 155×10 ⁶ cells mL ^-1 , and the cell density in the supernatant is 0.2×10 ⁶ cells mL ^-1 , so the equivalent volume of cells is 9.5×10 ⁶ cells mL -1 ^{. 1} , the biomass was 7.9 times the initial inoculum. Microscopic observation showed that the cell morphology was intact.

The above are some of the embodiments disclosed in the present invention, which will now be analyzed and discussed in conjunction with specific implementations. Comparative analysis of the results of Examples 1 to 5 (see Figure 3 for details) shows that the depth of the shallow liquid layer significantly affects the application effect of the culture system and method disclosed in the present invention, and the preferred depth is 5 mm to 60 mm, more preferably 10 mm to 10 mm 15mm, the final cell density decreased with depth, with a significant dilution effect, and the 10mm group had the highest yield per unit area. The liquid level in the culture tank 1 is shallow, and the analysis of the photosynthetic oxygen production of microalgae in the shallow liquid layer is more convenient and fast. However, the fluidity of the water body is poor, and the overall flow cannot be formed. In some areas, only diffusion, CO ₂ and nutrients There is a dead zone in the transport of , so the growth is partially blocked. On the contrary, if the liquid level in the culture tank 1 is too deep, under the condition of similar pump flow rate, the renewal rate of the water body in the tank will be low, the removal of metabolic waste will be hindered, and the heat and mass transfer efficiency will be greatly reduced. Therefore, it is necessary to control the liquid level depth of the shallow liquid layer to realize the renewal and mass transfer of the microalgae culture environment. In contrast to the traditional type of runway pool (Comparative Example 3), the liquid level depth is usually 15-30 cm. In order to promote heat and mass transfer, a stirring paddle is required to promote the overall flow of the water body, and the relative motion between the algae and the water body is still poor. It only relies on sedimentation and turbulence to achieve, but due to the large water body, there is only obvious turbulence near the stirring paddle, so the overall mixing effect is not good.

The results of Example 2 and Comparative Examples 1 and 2 show that: a surprising result of the present invention is that if the exchange column or static culture is implemented alone, the yield of algal cells is low, while the combination of the two can significantly reduce the yield of algal cells. Increase algal cell productivity. Although the column reactor has uniform mixing, the light attenuation is extremely serious with the increase of the diameter, so the production efficiency decreases significantly with the increase of the column diameter. However, by using it as an exchange column, rather than as the main site of photosynthesis, it can take advantage of its advantages of good mass transfer and heat transfer. The culture tank 1 is used as the main site of photosynthesis, which increases the light area and reduces the mutual occlusion between algae. The algae layer in the shallow liquid layer is also millimeter-level, which is within the range of light penetration, so the light-receiving ability of single cells is significantly improved. . At the same time, it can also be seen that if it is only left to stand (Comparative Example 2), due to the limited mass transfer and heat transfer, the cell growth is also limited, and the environment for cell growth, especially CO ₂ and nutrients, need to be continuously supplied, and the culture The pH of microalgae needs to be maintained within a reasonable range. If it is only statically cultured, the pH of the culture solution can be as high as 10.0 and above, which is obviously not conducive to the expansion of microalgae. Therefore, it is necessary to continuously maintain a good water environment for microalgae cultivation.

From the analysis and comparison of the results of Example 6 and Comparative Example 3, it can be seen that although the two have the same liquid filling volume, the system and method disclosed in the present invention have significant advantages, and the yield per unit area is 3.05 times that of the former. As mentioned above, the main purpose of increasing the liquid level depth in the racetrack pool is to facilitate stirring to form mixing. The purpose of the method disclosed in the present invention is to realize the relative movement of the algae body and the culture water body, so as to achieve the purpose of sufficient exchange. In contrast, although both are open reactors, the system and method disclosed in the present invention does not require a high-power stirring device, but only requires a low-power transfer pump (low lift, small flow), thus saving a lot of energy consumption. , while being more secure. At the same time, the results of Example 6 show that the volume enlargement of the photobioreactor of the present invention is feasible. Under the condition that the light-receiving area is increased by 9 times, the yield per unit area of 15.7 gm ^-2 d ^-1 even exceeds that of Example 2. Medium and small reaction system. In addition, it is also shown that the culture system of the present invention can be enlarged by free combination between the culture tank 1 and the exchange column 2, and the combination includes the series or parallel connection of the culture tank 1 and the series or parallel connection of the exchange column 2.

The comparison between the results of Example 7 and Example 2 shows that increasing the pump flow rate fails to significantly increase the cell mass and the cell yield per unit area, indicating that the flow rate in Example 2 is set within a reasonable range, and the normal growth of microalgae can be achieved. Supply of required nutrients and removal of metabolic wastes. At the same time, it is also shown that in order to realize the stable operation of the photobioreactor system of the above area, superfluous liquid replacement and flow are not required. Indicates a match between flow and culture system.

The results of Examples 8 and 9 show that another significant advantage of the culture system and method of the present invention is that the harvested supernatant can be reused for secondary culture, and the rate of decrease of the yield per unit area is very small. The ratio and composition of the medium have changed significantly compared with the initial stage, and the system can still promote the growth of microalgae and the adequate intake of nutrient elements. Conventional microalgae culture requires the algal liquid to be harvested and reused. If flocculation and other methods are used, the residual flocculant in the supernatant will inhibit cell growth and thus limit the recycling of supernatant liquid. If high-speed centrifugation is used, strong shearing Often, some cells are broken, resulting in a large change in the composition of the clear liquid, and cell debris will also affect the next batch of culture, and the intracellular organic matter dissolves into the clear liquid to easily breed bacteria, fungi and other microorganisms, thereby affecting the microalgae. Growth and product accumulation, so the present invention makes full use of the sedimentation characteristics of the algae to achieve the first separation of the algae and the clear liquid, and the cells in the clear liquid are usually newly divided small cells, which are more active and therefore more active. Conducive to subsequent secondary cultivation.

Embodiments 8, 10 and 11 verify the application of the shallow liquid layer quasi-static culture system and method disclosed in the present invention in the cultivation of other microalgae (covering freshwater and seawater algae, flagellates and dinoflagellates, benthic diatoms), Compared with the existing publicly available data, the cell yield of the cultured microalgae of the invention is higher, and can be used for the culture of bait microalgae, and the biomass can reach 7-8 times of the initial inoculation amount after culture. It is illustrated that the present invention has extremely wide practical value.

To sum up, through a series of comparative studies and compared with the existing publicly available data, the present application has innovated the microalgae cultivation system and method, the system and method have the advantages of high productivity, water saving and energy saving, continuous characteristics of production. It is explained that the application of the present invention can be implemented industrially, so it has extremely wide practical value.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention. , any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are all within the protection scope of the claims of the present invention for which the application is pending.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (10)

1. a shallow liquid layer quasi-static microalgae culture system, is characterized in that, comprises: Cultivation tank, used to accommodate microalgae and culture medium; an exchange column, which is communicated with the culture tank through a first connecting pipe, and is used for accommodating the culture liquid, and one end of the first connecting pipe extending into the exchange column is provided with a liquid level height adjusting member; The pipeline circulation drive structure includes a second connecting pipe, a third connecting pipe and a first pump, one end of the second connecting pipe is communicated with the exchange column, and the other end is communicated with one end of the third connecting pipe , the other end of the third connecting pipe is communicated with the culture tank, and the first pump is arranged on the second connecting pipe; a gas mixing device, communicated with the bottom of the exchange column through a fourth connecting pipe; a temperature adjusting device for adjusting the temperature of the culture solution inside the exchange column; and A supplementary light device, located beside the culture tank, is used for supplementing light to the microalgae in the culture tank. 2 . The quasi-static microalgae cultivation system in a shallow liquid layer according to claim 1 , wherein the upper end of the exchange column is cylindrical, and the lower end is conical. 3 . 3 . The quasi-static microalgae cultivation system in a shallow liquid layer according to claim 1 , further comprising a liquid replenishing device, and the liquid replenishing device is communicated with the exchange column through a fifth connecting pipe. 4 . 4. The quasi-static microalgae cultivation system of a shallow liquid layer according to claim 3, wherein the infusion device comprises: a first rehydration tank for replenishing sterile water, and The second liquid replenishment tank used for supplementing the culture medium, wherein one end of the fifth connecting pipe is communicated with the first liquid replenishment tank and the second liquid replenishment tank respectively, and the other end is connected to the exchange column. 5. The quasi-static microalgae cultivation system in a shallow liquid layer according to claim 1, further comprising a liquid collecting device, the liquid collecting device comprising: a first collection tank for collecting supernatant; a sixth connecting pipe, one end of which is communicated with the first liquid collecting tank, and the other end is connected at the connection between the second connecting pipe and the third connecting pipe; The second pump and the first valve are arranged on the sixth connecting pipe, and the second pump and the first valve are arranged in parallel; A second collection tank for collecting concentrated algal liquid; a seventh connecting pipe, one end of which is communicated with the second liquid collecting tank, and the other end is connected at the junction of the second connecting pipe and the third connecting pipe; and The second valve is arranged on the seventh connecting pipe. 6. The quasi-static microalgae cultivation system in a shallow liquid layer according to claim 1, wherein the gas mixing device comprises: _CO2 source and air source, and The mixer is communicated with the CO ₂ source and the air source respectively, and communicates with the bottom of the exchange column through the fourth connecting pipe after mixing the two. 7. The quasi-static microalgae culture system of a shallow liquid layer according to claim 1, wherein the supplementary light device comprises: light stand, and A light source mounted on the light stand. 8. The quasi-static microalgae cultivation system in a shallow liquid layer according to claim 1, wherein the temperature adjusting device comprises: an exchange coil disposed within the exchange column; and A heat exchanger is communicated with the exchange coil. 9 . The quasi-static microalgae cultivation system in a shallow liquid layer according to claim 1 , further comprising: a sensor installed on the exchange column. 10 . 10. the using method of a kind of shallow liquid layer quasi-static microalgae culture system according to claim 5, is characterized in that, comprising: Step S1. configure a culture medium in the rehydration device, add a culture system, and form a shallow liquid layer; Step S2. Inoculate algal cells into the culture tank of the culture system; Step S3. Let stand first to realize algal cell sedimentation, let the algal cells adhere to the bottom surface of the culture tank and stand for culture; Step S4. Start the first pump, the clear liquid flows into the culture tank through the second connecting pipe and the third connecting pipe to realize quasi-static culture, and ventilate the exchange column through the gas mixing device to realize the analysis of carbon supplementation and oxygen, and adjust the supplementary light device; Step S5. to the end of the culture, first collect the supernatant to the first collection tank, then collect the shallow algal mud in the culture tank to the second collection tank, and the collected supernatant is pumped to the culture system by the second, Part of the algal cells contained therein are used as the inoculum to start the first pump and continue to cultivate; The above steps S3 to S5 are repeated, and the volume of the reaction system is supplemented with the medium in the liquid supplement device as needed.

Images