CN112300923A

CN112300923A - Pipeline type photobioreactor for culturing microalgae in multiple nutrition modes and use method thereof

Info

Publication number: CN112300923A
Application number: CN202011464685.7A
Authority: CN
Inventors: 孙中亮; 梁信志
Original assignee: Xinyang Biyuan Biotechnology Co Ltd
Current assignee: Xinyang Biyuan Biotechnology Co Ltd
Priority date: 2020-12-14
Filing date: 2020-12-14
Publication date: 2021-02-02

Abstract

The invention discloses a pipeline type photobioreactor for culturing microalgae in a multi-nutrition mode, which comprises a plurality of groups of reaction units and circulating units; the reaction unit comprises a front row of transparent pipelines and a rear row of transparent pipelines; the circulating unit comprises a buffer tank and a circulating pump; the buffer tank comprises a tank body, a cover body and a heating jacket; a heating device is also arranged in the heating jacket; a pH sensor and a temperature sensor are arranged in the tank body; a discharge main pipe is arranged at the bottom of the tank body and is communicated with an inlet of the circulating pump, an outlet pipeline of the circulating pump is divided into a feeding branch, and the feeding branch is communicated with a feeding hole of the reaction unit; a material collecting pipeline is arranged on each feeding branch; the discharge port of each reaction unit is communicated with the circulating main pipe through a discharge pipeline; the circulating main pipe is communicated with the buffer tank; the discharge main pipe is also provided with discharge branch pipes; the cover body is provided with a breather valve, an inoculation port, a carbon dioxide pipeline, a nutrient salt supplementing pipeline and a turbidity testing pipeline; the turbidity test pipeline is communicated with a turbidity detection device.

Description

Pipeline type photobioreactor for culturing microalgae in multiple nutrition modes and use method thereof

Technical Field

The invention belongs to the technical field of microalgae culture, and particularly relates to a pipeline type photobioreactor for culturing microalgae in a multi-nutrition mode and a using method thereof.

Background

Microalgae are a class of photoautotrophic microorganisms, and a few species of algae can also be metabolized heterotrophically. Algae cells contain abundant nutrients and are widely developed into health-care foods, medicines, beauty products and the like, and for example, algae oil DHA is forcibly added into infant milk powder as a dietary nutritional supplement. However, the current microalgae have limited productivity, which limits their wider application. Among them, the low microalgae cultivation density and low active substance content are the main reasons of insufficient productivity. In the traditional microalgae culture process, the concentration of algae cells cannot reach a higher level due to the influence of factors such as temperature, illumination, nutritive salt and the like, for example, the density of chlorella cultured in a large scale is only 1 gram (dry basis)/liter under photoautotrophic conditions. Heterotrophic culture is to add organic carbon sources such as glucose and the like into an autotrophic culture medium on the basis of domestication of algae seeds, and to perform fermentation production under aseptic conditions, and the density of the heterotrophic cultured chlorella can reach 50 grams (dry medium)/liter according to literature reports. However, the content of active substances in the chlorella cells is reduced due to the absence of illumination, and the content of carotenoids in the heterotrophically cultured chlorella is only 50% under the autotrophic culture condition, and the content of polyunsaturated fatty acids is also greatly reduced. How to increase the content of active substances while realizing high-density culture, that is, how to increase the yield of target products in the whole culture process is a bottleneck of the development of the microalgae industry. When the haematococcus pluvialis is produced on a large scale, part of enterprises adopt a two-stage culture mode, namely, firstly, the haematococcus pluvialis is heterotrophically cultured in a fermentation tank to improve the cell density of the haematococcus pluvialis, and secondly, culture solution is diluted in a pipeline reactor to be subjected to illumination culture so as to induce the synthesis of astaxanthin.

Disclosure of Invention

The invention aims to provide a pipeline type photobioreactor for culturing microalgae in a multi-nutrition mode, which can realize autotrophic culture, heterotrophic culture and mixotrophic culture of the microalgae and can effectively solve the problems in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme: a pipeline type photobioreactor for culturing microalgae in a multi-nutrition mode comprises a plurality of groups of reaction units and circulation units, wherein the reaction units and the circulation units are arranged on different heights of a pipe frame; each reaction unit comprises a front row of transparent pipelines and a rear row of transparent pipelines, the front row of transparent pipelines and the rear row of transparent pipelines are same in number and are arranged in a staggered mode, and the front row of transparent pipelines and the rear row of transparent pipelines are communicated in sequence through bent pipes to form spiral pipelines;

the circulating unit comprises a buffer tank and a circulating pump; the buffer tank comprises a tank body, a cover body detachably connected with the tank body and a heating jacket arranged outside the tank body; the heating jacket is provided with an inlet and an outlet of a heating medium, and a heating device is also arranged in the heating jacket; a pH sensor and a temperature sensor are arranged in the tank body; a discharge main pipe is arranged at the bottom of the tank body and is communicated with an inlet of the circulating pump, an outlet pipeline of the circulating pump is divided into a plurality of feeding branches with the same number as that of the reaction units, and the feeding branches are communicated with feeding holes of the reaction units; each feeding branch is provided with a material collecting pipeline; the discharge hole of each reaction unit is communicated with a circulation main pipe through a discharge pipeline; the circulating main pipe is communicated with the buffer tank; the discharge main pipe is also provided with a discharge branch pipe for discharging the buffer tank;

the cover body is provided with a breather valve, an inoculation port, a carbon dioxide pipeline for supplementing carbon dioxide, a nutrient salt supplementing pipeline for supplementing nutrient salt and a turbidity test pipeline; one end of the turbidity test pipeline, which is positioned outside the tank body, is communicated with a turbidity detection device.

Further, the turbidity detecting device comprises a diaphragm pump and a turbidity detecting box; the turbidity test pipeline is communicated with an inlet of the diaphragm pump, an outlet of the diaphragm pump is communicated with the turbidity detection box, and a turbidity sensor is arranged in the turbidity detection box; and a material returning pipeline is arranged between the turbidity detection box and the circulating main pipe.

Further, the carbon dioxide pipeline is communicated with a carbon dioxide pressure gas source arranged in the cabinet; the nutrient salt supplementing pipeline is respectively communicated with outlet pipelines of a first peristaltic pump, a second peristaltic pump, a third peristaltic pump, a fourth peristaltic pump and a fifth peristaltic pump in the cabinet; the inlet pipelines of the first peristaltic pump, the second peristaltic pump, the third peristaltic pump, the fourth peristaltic pump and the fifth peristaltic pump are respectively communicated with the storage tank of the nitrogen source, the storage tank of the phosphorus source, the storage tank of the calcium source, the storage tank of the trace elements and the storage tank of the vitamins, and the storage tanks are arranged in the cabinet.

Furthermore, a first LED lamp is arranged at the central part of the lower surface of the cover body; an external LED light source is arranged between the front row of transparent pipelines and the back row of transparent pipelines on the pipe frame or at the rear side of the transparent pipelines, the external LED light source comprises a plurality of groups of LED lamp groups arranged at different heights, and each LED lamp group comprises a second LED lamp, a third LED lamp and a fourth LED lamp which are sequentially arranged on the pipe frame from top to bottom; the first LED lamp and the second LED lamp are white LED lamp tubes, the third LED lamp is a red LED lamp tube, and the fourth LED lamp is a blue LED lamp tube; the external LED light sources are parallel to the transparent pipelines and are respectively arranged in one-to-one correspondence with the transparent pipelines; the light intensity ranges of the first LED lamp, the second LED lamp, the third LED lamp and the fourth LED lamp are 0-20000 LUX.

Furthermore, a steam pipeline and a flushing pipeline are also arranged on the circulating main pipe; and a circulating pump bypass pipeline is arranged between the inlet and the outlet of the circulating pump.

Further, the device also comprises a control unit; the control unit comprises an upper computer, a PLC (programmable logic controller), a pH sensor, a temperature sensor, a heating device and a turbidity sensor; the upper computer is provided with a human-computer interaction operation interface and a control program and is in bidirectional connection with the PLC; the input end of the PLC controller is respectively electrically connected with the output ends of the pH sensor, the turbidity sensor and the temperature sensor, and the output end of the PLC controller is respectively electrically connected with the air inlet electromagnetic valve arranged on the carbon dioxide pipeline, the first peristaltic pump, the second peristaltic pump, the third peristaltic pump, the fourth peristaltic pump, the fifth peristaltic pump, the heating device and the first LED lamp, the second LED lamp, the third LED lamp and the fourth LED lamp.

The invention also aims to provide a using method of the pipeline type photobioreactor for culturing the microalgae in the multi-nutrition mode, wherein the using method is any one of autotrophic culture, mixotrophic culture or heterotrophic culture of the microalgae; the method comprises the following specific steps: the autotrophic culture comprises reactor sterilization, autotrophic culture medium preparation, algae seed inoculation, algae seed culture, algae liquid collection and reactor cleaning; the mixotrophic culture comprises reactor sterilization, mixotrophic culture medium preparation, culture medium sterilization, culture medium cooling, algae seed inoculation, algae seed culture, algae liquid harvesting and reactor cleaning; the heterotrophic culture comprises reactor sterilization, heterotrophic culture medium preparation, culture medium sterilization, culture medium cooling, algae seed inoculation, algae seed culture, algae liquid harvesting and reactor cleaning;

the reactor sterilization comprises buffer tank sterilization and reaction unit sterilization; sequentially introducing steam into the buffer tank from the circulation main pipe through a steam pipeline, introducing the steam into the transparent pipelines of the reaction units from the discharge pipelines of the reaction units, and discharging the steam and the condensate out of the buffer tank and the reaction units from the discharge branch pipes and the material collecting pipelines respectively to finish the sterilization operation of the reactor;

the preparation of the autotrophic medium comprises the following steps: firstly, ultrafiltration water obtained by filtering tap water through a 0.1-micron ultrafiltration membrane is added into a buffer tank from an inoculation port, and the ultrafiltration water and nutrient salts required by cultured algae seeds are added;

the mixotrophic culture medium configuration comprises the following steps: adding tap water into the buffer tank through the inoculation port, adding nutrient salt required by the cultured algae seeds from the inoculation port, and finally adding glucose from the inoculation port according to the proportion of adding 10g of glucose into each liter of solution;

the heterotrophic culture medium configuration comprises the following steps: adding tap water into the buffer tank through the inoculation port, adding nutrient salt required by the cultured algae seeds from the inoculation port, and finally adding glucose from the inoculation port according to the proportion of adding 20g of glucose into each liter of solution;

the culture medium sterilization comprises the following steps: starting a circulating pump during sterilization to enable the culture medium to circulate between the reaction unit and the buffer tank so as to ensure that the temperature in the culture medium is uniform, heating the culture medium to be more than 90 ℃ through a heating medium, and maintaining for more than 30min to finish the sterilization of the culture medium;

the culture medium cooling comprises the following steps: discharging the heating medium in the heating jacket, introducing cooling water, keeping the circulating pump on, and cooling the culture medium when the temperature of the culture medium is reduced to below 30 ℃;

the inoculation of the algal species comprises the following steps: then, disinfecting the inoculation port by using alcohol, igniting the inoculating loop, opening the inoculation port, and adding seed liquid to be inoculated into the buffer tank from the inoculating loop to finish the inoculation operation;

the algae seed culture comprises the following steps: firstly, regulating and controlling the light intensity of a first LED lamp and an external LED light source through a PLC (programmable logic controller); keeping the circulating pump running to make the liquid continuously circulate between the reaction unit and the buffer tank, and controlling the flow rate of the algae liquid to be 30-50 cm/s; meanwhile, a pH value required by algae culture is set through a human-computer interaction operation interface, and when the pH value is higher than a set value, the PLC controls to open an air inlet electromagnetic valve to supplement carbon dioxide into the buffer tank; when the pH value is lower than a set value, closing the air inlet electromagnetic valve; calculating the change of the turbidity value every day according to the numerical value acquired by the turbidity sensor, and controlling a first peristaltic pump, a second peristaltic pump, a third peristaltic pump, a fourth peristaltic pump and a fifth peristaltic pump by using a PLC (programmable logic controller) so as to control the supply of a nitrogen source, a phosphorus source, a calcium source, trace elements and vitamins in the buffer tank; when the cell concentration of the microalgae is detected, finishing the culture step when the cell concentration of the microalgae is detected to be unchanged for two consecutive days;

the algae liquid harvesting comprises full harvesting or sectional harvesting; the steps of all the harvesting are as follows: stopping the circulating pump, opening the discharge branch pipes to collect the algae liquid in the buffer tank, and opening the material collection pipelines to collect all the algae liquid in each reaction unit; the step of sectional recovery is as follows: stopping the circulating pump, opening the discharge branch pipes to collect the algae liquid in the buffer tank, opening the material collection pipeline to collect the algae liquid in the reaction units, and simultaneously leaving the algae liquid in at least one reaction unit as seed liquid; after the segmented harvesting, cleaning and sterilizing the buffer tank and the harvested reaction unit when the next culture is carried out, completing the step of configuring the culture medium in the buffer tank again, completing the step of sterilizing the culture medium in the buffer tank, and then, not needing to inoculate new algae seeds, and entering a new round of microalgae culture step after the step of cooling the culture medium is completed; when the algae liquid is collected, the flow rate of the algae liquid is low, and pressurized air can be introduced from a steam pipeline to increase the collection speed of the algae liquid;

the reactor cleaning comprises the following steps: tap water is connected from the flushing pipeline, the tap water is sequentially led into the buffer tank from the circulating main pipe and led into the transparent pipelines of the reaction units from the discharge pipelines of the reaction units, and the tap water is respectively discharged out of the buffer tank and the reaction units from the discharge branch pipes and the material collecting pipelines, so that the cleaning operation of the reactor is completed.

Further, when autotrophic culture of microalgae is carried out, the flow rate of the microalgae liquid is 30 cm/s; the control process of the light intensity in the first LED lamp and the external LED light source is as follows: the light intensity of the white LED lamp tube is adjusted to 2000LUX during inoculation, the light intensity is increased to 10000LUX after one day, the light intensity is increased to 15000LUX after two days, 20000LUX is maintained after the third day, and the red LED lamp tube and the blue LED lamp tube are in a closed state.

Further, when mixotrophic culture of microalgae is performed, the flow rate of the microalgae liquid is 50 cm/s; the control process of the light intensity in the first LED lamp and the external LED light source is as follows: only opening the white LED lamp tube and the red LED lamp tube in the first three days of inoculation, wherein the light intensity of the white LED lamp tube and the red LED lamp tube is adjusted to 2000LUX during inoculation, the light intensity is increased to 10000LUX after one day, the light intensity is increased to 15000LUX after two days, and the light intensity is adjusted to 20000LUX on the third day; after three days, only the white LED lamp tube and the blue LED lamp tube are turned on, and the light intensity of the white LED lamp tube and the light intensity of the blue LED lamp tube are adjusted to 20000 LUX.

Further, when heterotrophic culture of microalgae is carried out, the flow rate of the microalgae liquid is 50 cm/s; the first LED lamp and the external LED light source are both in an off state.

The beneficial results of the invention are as follows:

1. the invention provides a pipeline type photobioreactor which can realize culture in multiple nutrition modes simultaneously; the invention is provided with a reaction unit consisting of a buffer tank and a transparent pipeline, thereby forming a culture dark area (in the buffer tank) and a light area (in the pipeline) so as to improve the yield of a required target product; the proportion and the intensity of light with different colors in the external LED light source can be controlled, so that the growth of algae cells and the accumulation of active substances are promoted, namely, the high-density culture of the algae cells and the high-content accumulation of the active substances can be simultaneously realized.

2. According to the invention, the pH value of the culture solution is controlled to be stable while carbon dioxide is fed back and supplemented as a carbon source through the pH value; controlling to feed back and supplement different types of nutrient salts into the buffer tank through a first peristaltic pump, a second peristaltic pump, a third peristaltic pump, a fourth peristaltic pump and a fifth peristaltic pump by measuring turbidity change; the invention can effectively improve the utilization efficiency of nutrient salt and carbon dioxide. The temperature of the culture solution in the whole reactor is raised and lowered by a temperature sensor in the buffer tank and a heating device.

3. The invention improves the traditional pipeline reactor, and can realize the sectional algae liquid collection, the sectional reaction unit sterilization and the algae seed culture.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the structure of the present invention in the direction of A-A;

FIG. 3 is a block diagram of the electrical control scheme of the present invention;

reference numerals: 1-a cabinet; 2-a feed inlet; 3-a third LED lamp; 4-a man-machine interaction operation interface; 5-a first peristaltic pump; 6-a second peristaltic pump; 7-a third peristaltic pump; 8-a fourth peristaltic pump; 9-a fifth peristaltic pump; 10-nutrient salt make-up line; 11-a carbon dioxide line; 12-an air inlet solenoid valve; 13-a breather valve; 14-an inoculation port; 15-a first LED lamp; 16-heating jacket; 17-a heating device; 18-a pH sensor; 19-a temperature sensor; 20-discharge branch pipes; 21-a circulating pump; 22-a discharge main; 23-circulation pump bypass line; 24-a fourth LED lamp; 25-a first LED lamp; 26-a production line; 27-a discharge pipeline; 28-a circulation manifold; 29-a steam line; 30-a flush line; 31-a diaphragm pump; 32-a turbidity assay cartridge; 33-a return line; 34-a buffer tank; 35-pipe frame; 36-a transparent tube; 37-second LED lamp.

Detailed Description

The technical solution of the present invention will be further explained with reference to the accompanying figures 1-3 and examples,

example 1:

the invention relates to a pipeline type photobioreactor for culturing microalgae in a multi-nutrition mode, which comprises 2 groups of reaction units and a circulation unit, wherein the reaction units are arranged on different heights of a pipe frame 35; each group of reaction units comprises five front-row transparent pipelines 36 and five back-row transparent pipelines 36 which are arranged on the pipe frame from top to bottom, the number of the front-row transparent pipelines 36 and the number of the back-row transparent pipelines 36 are the same, the front-row transparent pipelines 36 and the back-row transparent pipelines 36 are arranged in a staggered mode, and the front-row transparent pipelines 36 and the back-row transparent pipelines 36 are sequentially communicated through bent pipes to form spiral pipelines; an external LED light source is arranged on the pipe frame 35 between the front row of the transparent pipeline 36 and the rear row of the transparent pipeline 36 or behind the transparent pipeline 36, the external LED light source comprises a plurality of groups of LED lamp sets arranged at different heights, and each LED lamp set comprises a second LED lamp 37, a third LED lamp 39 and a fourth LED lamp 24 which are sequentially arranged on the pipe frame 35 from top to bottom; the second LED lamp 37 is a white LED lamp, the third LED lamp 38 is a red LED lamp, and the fourth LED lamp 24 is a blue LED lamp; the external LED light sources are parallel to the transparent pipelines 36 and are respectively arranged corresponding to the transparent pipelines 36 one by one; the light intensity ranges of the second LED lamp 37, the third LED lamp 39 and the fourth LED lamp 24 are 0-20000 LUX.

The transparent pipeline and the bent pipe in the reactor are both glass pipes; the outer diameter of the elbow is 60mm, the inner diameter is 55mm, the length of the straight pipe is 1.5 m, the radian of the elbow is 180 degrees, the joint of the transparent pipeline and the elbow adopts a high-temperature and corrosion resistant silica gel sleeve, the thickness of the silica gel sleeve is 5-8mm, a stainless steel gasket is wrapped outside the silica gel sleeve, and the silica gel sleeve is tightened by a stainless steel pipe hoop;

the circulation unit comprises a buffer tank 34 and a circulation pump 21; the buffer tank 34 comprises a tank body, a cover body detachably connected with the tank body, and a heating jacket 16 arranged outside the tank body; the heating jacket 16 is provided with an inlet and an outlet of a heating medium, and a heating device 17 is also arranged in the heating jacket; a pH sensor 18 and a temperature sensor 19 are arranged in the tank body; a discharge header pipe 22 is arranged at the bottom of the tank body, the discharge header pipe 22 is communicated with an inlet of the circulating pump 21, an outlet pipeline of the circulating pump 21 is divided into a plurality of feeding branch pipes 25 with the same number as that of the reaction units, and the feeding branch pipes 25 are communicated with feeding ports 38 of the reaction units; a material collecting pipeline 26 is arranged on each feeding branch 25; the discharge port of each reaction unit is communicated with a circulation header pipe 28 through a discharge pipeline 27; the circulation main 28 is communicated with the buffer tank 34; the discharge main pipe 22 is also provided with a discharge branch pipe 20 for discharging the buffer tank 34; two groups of reaction units are designed, so that the algae liquid pumped out of the buffer tank can enter the transparent pipeline from the two feed inlets, and the high-pressure impact on the glass tube at the feed inlet when only one feed inlet is provided is reduced;

the cover body is provided with a breather valve 13, an inoculation port 14, a carbon dioxide pipeline 11 for supplementing carbon dioxide, a nutrient salt supplementing pipeline 10 for supplementing nutrient salt and a turbidity test pipeline; one end of the turbidity test pipeline, which is positioned outside the tank body, is communicated with a turbidity detection device. The turbidity detecting device comprises a diaphragm pump 31 and a turbidity detecting box 32; the turbidity test pipeline is communicated with an inlet of the diaphragm pump 31, an outlet of the diaphragm pump 31 is communicated with the turbidity detection box 32, and a turbidity sensor is arranged in the turbidity detection box 32; a return line 33 is provided between the turbidity detecting cassette 32 and the circulation manifold 28. The carbon dioxide pipeline 11 is communicated with a carbon dioxide pressure gas source arranged in the cabinet 1; the nutrient salt supplementing pipeline 10 is respectively communicated with outlet pipelines of a first peristaltic pump 5, a second peristaltic pump 6, a third peristaltic pump 7, a fourth peristaltic pump 8 and a fifth peristaltic pump 9 in the cabinet 1; the inlet pipelines of the first peristaltic pump 5, the second peristaltic pump 6, the third peristaltic pump 7, the fourth peristaltic pump 8 and the fifth peristaltic pump 9 are respectively communicated with the storage tank of a nitrogen source, the storage tank of a phosphorus source, the storage tank of a calcium source, the storage tank of trace elements and the storage tank of vitamins, and the storage tanks are arranged in the cabinet 1. A first LED lamp 15 is arranged at the central part of the lower surface of the cover body; the first LED lamp 15 is a white LED lamp tube, and the light intensity of the first LED lamp 15 ranges from 0 to 20000 LUX. . The circulation main pipe 28 is also provided with a steam pipeline 29 and a flushing pipeline 30; a circulation pump bypass line 23 is provided between the inlet and the outlet of the circulation pump 21. And regulating valves are arranged on the discharge branch pipes 20, the discharge main pipe 22, the discharge pipeline 27, the circulation main pipe 28, an outlet pipeline of the circulation pump 21, the feeding branch 25, the steam pipeline 29, the flushing pipeline 30 and the like.

The reactor also comprises a control unit; the control unit comprises an upper computer, a PLC (programmable logic controller), a pH sensor 18, a temperature sensor 19, a heating device 17 and a turbidity sensor; the upper computer is provided with a human-computer interaction operation interface 4 and a control program and is in bidirectional connection with the PLC; the upper computer is arranged on the machine cabinet and is used for setting working data of the first peristaltic pump 5, the second peristaltic pump 6, the third peristaltic pump 7, the fourth peristaltic pump 8, the fifth peristaltic pump 9, the first LED lamp 15, the second LED lamp, the third LED lamp and the fourth LED lamp, storing data of the pH sensor 18, the temperature sensor 19 and the turbidity sensor fed back by the PLC, and transmitting the set data to the PLC; the input end of the PLC controller is respectively electrically connected with the output ends of the pH sensor 18, the turbidity sensor and the temperature sensor 19, the output end of the PLC controller is respectively electrically connected with the air inlet electromagnetic valve 12 arranged on the carbon dioxide pipeline 11, the first peristaltic pump 5, the second peristaltic pump 6, the third peristaltic pump 7, the fourth peristaltic pump 8, the fifth peristaltic pump 9, the heating device 17 and the first LED lamp 15, the second LED lamp 37, the third LED lamp 3 and the fourth LED lamp 24. The control principle of the PLC is the prior art, and is not described herein.

The invention relates to a using method of a pipeline type photobioreactor for culturing microalgae in a multi-nutrition mode, which is a using method in autotrophic culture of microalgae; taking chlorella as an example; the method comprises the following specific steps:

firstly, sterilizing the reactor for the first time, including sterilizing a buffer tank 34 and sterilizing a reaction unit; the specific steps are that steam is sequentially led into a buffer tank 34 from a circulation main pipe 28 through a steam pipeline 29, and is led into transparent pipelines 36 of reaction units from discharge pipelines 27 of all the reaction units, and the steam and condensate are respectively discharged out of the buffer tank 34 and the reaction units from a discharge branch pipe 20 and a material collecting pipeline 26, so that the sterilization operation of the reactor is completed;

secondly, configuring an autotrophic culture medium, comprising the following steps of: firstly, ultrafiltration water obtained by filtering tap water through a 0.1-micron ultrafiltration membrane is added into a buffer tank 34 from an inoculation port 14, 230L of ultrafiltration water and 10L of nutrient salt mother liquor are added into a formula of BG11 culture medium required by cultured chlorella;

thirdly, inoculating chlorella algae seeds, comprising the following steps: then, the inoculation port 14 is sterilized by alcohol, the inoculation loop is ignited, the inoculation port 14 is opened, and the seed solution of chlorella is added into the buffer tank 34 from the inoculation loop, so that the density of chlorella in the culture solution after uniform mixing is 0.1 g (dry basis)/L.

Fourthly, the cultivation of the chlorella algae seeds comprises the following steps: firstly, the light intensity of the first LED lamp 15 and the external LED light source is regulated and controlled through the PLC, the light intensity of the white LED lamp tube is regulated and controlled to be 2000LUX during inoculation, the light intensity is increased to 10000LUX after one day, the light intensity is increased to 15000LUX after two days, 20000LUX is maintained after the third day, and the red LED lamp tube and the blue LED lamp tube are in a closed state. The circulation pump 21 is kept running, so that the liquid is continuously circulated between the reaction unit and the buffer tank 34, and the flow rate of the algae liquid is controlled to be 30 cm/s; meanwhile, the pH value required by algae culture is set to be 7.8 through the human-computer interaction operation interface 4, and when the pH value is higher than the set value, the PLC controller controls the air inlet electromagnetic valve 12 to be opened, and carbon dioxide is supplemented into the buffer tank 34; when the pH value is lower than the set value, closing the air inlet electromagnetic valve 12; calculating the supply amount of various types of nutrient salts according to the value acquired by the turbidity sensor and the change amount of the turbidity value every day, wherein the specific calculation method refers to patent CN 201110356566.4; a PLC controller is used for controlling a first peristaltic pump 5, a second peristaltic pump 6, a third peristaltic pump 7, a fourth peristaltic pump 8 and a fifth peristaltic pump 9, and further controlling the supply amount of a nitrogen source, a phosphorus source, a calcium source, trace elements and vitamins in a buffer tank 34; when the cell concentration of the microalgae is detected, finishing the culture step when the cell concentration of the microalgae is detected to be unchanged for two consecutive days;

fifthly, harvesting the algae liquid, including whole harvesting or sectional harvesting; the steps of all the harvesting are as follows: stopping the circulating pump 21, opening the discharge branch pipe 20 to collect the algae liquid in the buffer tank 34, and opening the material collecting pipeline 26 to collect all the algae liquid in each reaction unit; the step of sectional recovery is as follows: stopping the circulating pump 21, opening the discharge branch pipe 20 to collect the algae liquid in the buffer tank 34, opening the material collecting pipeline 26 to collect the algae liquid in the reaction units, and simultaneously leaving the algae liquid in at least one reaction unit as seed liquid; when the algae liquid is collected, the flow rate of the algae liquid is low, and pressurized air can be introduced from the steam pipeline 29 to increase the collection speed of the algae liquid; after the step of harvesting in sections, after cleaning and sterilizing the buffer tank 34 and the harvested reaction units during the next culture, the step of configuring the autotrophic culture medium is completed in the buffer tank 34 again, and after the step of sterilizing the culture medium is completed in the buffer tank 34, new algae seeds do not need to be inoculated, and after the step of cooling the culture medium is completed, the microalgae culture step can be started in a new round.

Sixthly, cleaning the reactor, comprising the following steps: tap water is introduced from the flushing pipeline 30, the tap water is sequentially introduced into the buffer tank from the circulating main pipe 28, the tap water is introduced into the transparent pipes 36 of the reaction units from the discharge pipelines 27 of the reaction units, and the tap water is discharged out of the buffer tank 34 and the reaction units from the discharge branch pipe 20 and the material collecting pipeline 26 respectively, so that the cleaning operation of the reactor is completed.

After three days of culture, the density of the chlorella reaches 3 g/L. The utilization rate of the carbon source in the culture process is calculated to be 92%, and the algae cells are improved by 2 g/L compared with the traditional illumination culture. The yield of nutrient salt, such as the yield of nitrogen source, is 62 percent and is improved by 68 percent. The control group for autotrophic culture has no feedback control of pH value, and is fed with mixed air containing 5% CO2, the light intensity of the first LED lamp 15 and the external LED light source is not controlled, the nutrient salt supply amount is not controlled by using turbidity feedback, and the density of cultured chlorella is only 1 g/L after three days. The utilization rate of the carbon source is 20 percent, and the yield of the nitrogen source is 37 percent.

Example 2:

the difference between this example and example 1 is that the method of use is that of the mixotrophic culture of Haematococcus pluvialis;

the method comprises the following specific steps:

secondly, configuring a mixotrophic culture medium, comprising the following steps of: 200L of tap water is added into the buffer tank 34 through the inoculation port 14, then nutrient salt BG11 required by the cultured haematococcus pluvialis algae is added into the inoculation port 14, and finally glucose is added into the solution from the inoculation port 14 according to the proportion of 10g of glucose added into each liter of the solution;

thirdly, sterilizing the culture medium, comprising the following steps: starting the circulating pump 21 during sterilization to circulate the culture medium between the reaction unit and the buffer tank 34 so as to ensure that the temperature in the culture medium is uniform, heating the culture medium to more than 90 ℃ through a heating medium, and maintaining for more than 30min to finish the sterilization of the culture medium;

cooling the culture medium, comprising the following steps: discharging the heating medium in the heating jacket 16, introducing cooling water, keeping the circulating pump 21 on, and cooling the culture medium when the temperature of the culture medium is reduced to below 30 ℃;

fifthly, inoculating haematococcus pluvialis strains, and comprising the following steps: then, the inoculation port 14 is sterilized by alcohol, the inoculation loop is ignited, the inoculation port 14 is opened, and the seed liquid of haematococcus pluvialis is added into the buffer tank 34 from the inoculation loop, so that the density of chlorella in the culture solution after uniform mixing is 0.1 g (dry basis)/L.

Sixthly, the haematococcus pluvialis strain culture method comprises the following steps: the light intensity of the first LED lamp 15 and the light intensity of the external LED light source are regulated and controlled through a PLC, and only the white LED lamp tube and the red LED lamp tube are opened in the first three days of inoculation, wherein the light intensity of the white LED lamp tube and the light intensity of the red LED lamp tube are regulated to 2000LUX in the inoculation process, 10000LUX is increased after one day, 15000LUX is increased after two days, and 20000LUX is increased in the third day; and (4) entering an induction cultivation stage after three days, and only opening the white LED lamp tube and the blue LED lamp tube, wherein the light intensities of the white LED lamp tube and the blue LED lamp tube are adjusted to 20000 LUX. The circulation pump 21 is kept running, so that the liquid is continuously circulated between the reaction unit and the buffer tank 34, and the flow rate of the algae liquid is controlled to be 50 cm/s; meanwhile, the pH value required by algae culture is set to be 7.8 through the human-computer interaction operation interface 4, and when the pH value is higher than the set value, the PLC controller controls the air inlet electromagnetic valve 12 to be opened, and carbon dioxide is supplemented into the buffer tank 34; when the pH value is lower than the set value, closing the air inlet electromagnetic valve 12; calculating the supply amount of various types of nutrient salts according to the value acquired by the turbidity sensor and the change amount of the turbidity value every day, wherein the specific calculation method refers to patent CN 201110356566.4; a PLC controller is used for controlling a first peristaltic pump 5, a second peristaltic pump 6, a third peristaltic pump 7, a fourth peristaltic pump 8 and a fifth peristaltic pump 9, and further controlling the supply amount of a nitrogen source, a phosphorus source, a calcium source, trace elements and vitamins in a buffer tank 34; when the cell concentration of the microalgae is detected, finishing the culture step when the cell concentration of the microalgae is detected to be unchanged for two consecutive days;

collecting algae liquid, including collecting algae liquid completely or sectionally; the steps of all the harvesting are as follows: stopping the circulating pump 21, opening the discharge branch pipe 20 to collect the algae liquid in the buffer tank 34, and opening the material collecting pipeline 26 to collect all the algae liquid in each reaction unit; the step of sectional recovery is as follows: stopping the circulating pump 21, opening the discharge branch pipe 20 to collect the algae liquid in the buffer tank 34, opening the material collecting pipeline 26 to collect the algae liquid in the reaction units, and simultaneously leaving the algae liquid in at least one reaction unit as seed liquid; when the algae liquid is collected, the flow rate of the algae liquid is low, and pressurized air can be introduced from the steam pipeline 29 to increase the collection speed of the algae liquid; after the step of harvesting in sections, after cleaning and sterilizing the buffer tank 34 and the harvested reaction units during the next culture, the step of configuring the autotrophic culture medium is completed in the buffer tank 34 again, and after the step of sterilizing the culture medium is completed in the buffer tank 34, new algae seeds do not need to be inoculated, and after the step of cooling the culture medium is completed, the microalgae culture step can be started in a new round.

And eighthly, cleaning the reactor, comprising the following steps of: tap water is introduced from the flushing pipeline 30, the tap water is sequentially introduced into the buffer tank from the circulating main pipe 28, the tap water is introduced into the transparent pipes 36 of the reaction units from the discharge pipelines 27 of the reaction units, and the tap water is discharged out of the buffer tank 34 and the reaction units from the discharge branch pipe 20 and the material collecting pipeline 26 respectively, so that the cleaning operation of the reactor is completed.

After three days of culture with different light intensities, the density of haematococcus pluvialis reaches 20 g/L, after three days, the haematococcus pluvialis enters an induction stage, and after three days of induction, the dry weight of algal cells reaches 30 g L, wherein the content of astaxanthin in the algal cells is 5%. The yield of astaxanthin after 6 days of cultivation reached 0.25 g/L/d. The control group of the mixotrophic culture is not fed back to control the pH value, mixed air containing 5% CO2 is always introduced, a mode of regulating and controlling light intensity and inducing by not adopting different colors of illumination for three days after the first three days and a mode of adding nutrient salts by turbidity feedback are not adopted, the density of the haematococcus pluvialis cultured for three days is only 9 g/L, and the yield of the astaxanthin cultured for 6 days is only 0.09 g/L/d.

Example 3:

the difference between the present example and example 1 is that the method of use is that of the heterotrophic culture of Haematococcus pluvialis;

the method comprises the following specific steps:

secondly, configuring a mixotrophic culture medium, comprising the following steps of: 200L of tap water is added into the buffer tank 34 through the inoculation port 14, then the nutrient salt BG11 required by the cultured haematococcus pluvialis algae is added into the inoculation port 14, and finally the glucose is added into the inoculation port 14 according to the proportion of adding 20g of glucose into each liter of solution;

Sixthly, the haematococcus pluvialis strain culture method comprises the following steps: the first LED lamp 15 and the external LED light source are turned off. The circulation pump 21 is kept running, so that the liquid is continuously circulated between the reaction unit and the buffer tank 34, and the flow rate of the algae liquid is controlled to be 50 cm/s; meanwhile, the pH value required by algae culture is set to be 7.8 through the human-computer interaction operation interface 4, and when the pH value is higher than the set value, the PLC controller controls the air inlet electromagnetic valve 12 to be opened, and carbon dioxide is supplemented into the buffer tank 34; when the pH value is lower than the set value, closing the air inlet electromagnetic valve 12; calculating the supply amount of various types of nutrient salts according to the value acquired by the turbidity sensor and the change amount of the turbidity value every day, wherein the specific calculation method refers to patent CN 201110356566.4; a PLC controller is used for controlling a first peristaltic pump 5, a second peristaltic pump 6, a third peristaltic pump 7, a fourth peristaltic pump 8 and a fifth peristaltic pump 9, and further controlling the supply amount of a nitrogen source, a phosphorus source, a calcium source, trace elements and vitamins in a buffer tank 34; when the cell concentration of the microalgae is detected, finishing the culture step when the cell concentration of the microalgae is detected to be unchanged for two consecutive days;

After three days of culture, the density of haematococcus pluvialis reaches 35 g liter, the biomass yield is 11.7 g/L/d, and the yield of nutrient salts, such as a nitrogen source, is 73 percent. The control group of heterotrophic culture has pH value not controlled by feedback, and is always fed with mixed air containing 5% CO2, and does not adopt the mode of turbidity feedback and nutrient salt addition, the density of the haematococcus pluvialis cultured for three days is only 16 g/L, the yield of the cultured biomass is only 5.3 g/L/d after 3 days, and the yield of nutrient salt such as nitrogen source is 48%.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pipeline type photobioreactor for culturing microalgae in multiple nutrition modes is characterized in that: comprises a plurality of groups of reaction units and circulating units which are arranged on different heights of a pipe frame (35); each reaction unit comprises a front row of transparent pipelines (36) and a rear row of transparent pipelines (36), the number of the front row of transparent pipelines (36) and the number of the rear row of transparent pipelines (36) are the same and are arranged in a staggered manner, and the front row of transparent pipelines and the rear row of transparent pipelines are communicated in sequence through bent pipes to form spiral pipelines;

the circulation unit comprises a buffer tank (34) and a circulation pump (21); the buffer tank (34) comprises a tank body, a cover body detachably connected with the tank body and a heating jacket (16) arranged outside the tank body; the heating jacket (16) is provided with an inlet and an outlet of a heating medium, and a heating device (17) is also arranged in the heating jacket; a pH sensor (18) and a temperature sensor (19) are arranged in the tank body; a discharge main pipe (22) is arranged at the bottom of the tank body, the discharge main pipe (22) is communicated with an inlet of the circulating pump (21), an outlet pipeline of the circulating pump (21) is divided into a plurality of feeding branches (25) with the same number as that of the reaction units, and the feeding branches (25) are communicated with a feeding hole (38) of the reaction units; a material collecting pipeline (26) is arranged on each feeding branch (25); the discharge hole of each reaction unit is communicated with a circulating main pipe (28) through a discharge pipeline (27); the circulation main pipe (28) is communicated with the buffer tank (34); the discharge main pipe (22) is also provided with a discharge branch pipe (20) for discharging the buffer tank (34);

the cover body is provided with a breather valve (13), an inoculation port (14), a carbon dioxide pipeline (11) for supplementing carbon dioxide, a nutrient salt supplementing pipeline (10) for supplementing nutrient salt and a turbidity test pipeline; one end of the turbidity test pipeline, which is positioned outside the tank body, is communicated with a turbidity detection device.

2. The pipeline photobioreactor for cultivating microalgae in a multi-nutrient mode according to claim 1, wherein: the turbidity detection device comprises a diaphragm pump (31) and a turbidity detection box (32); the turbidity test pipeline is communicated with an inlet of the diaphragm pump (31), an outlet of the diaphragm pump (31) is communicated with the turbidity detection box (32), and a turbidity sensor is arranged in the turbidity detection box (32); a material returning pipeline (33) is arranged between the turbidity detection box (32) and the circulating main pipe (28).

3. The pipeline photobioreactor for cultivating microalgae in a multi-nutrient mode according to claim 1, wherein: the carbon dioxide pipeline (11) is communicated with a carbon dioxide pressure air source arranged in the cabinet (1); the nutrient salt supplementing pipeline (10) is respectively communicated with outlet pipelines of a first peristaltic pump (5), a second peristaltic pump (6), a third peristaltic pump (7), a fourth peristaltic pump (8) and a fifth peristaltic pump (9) in the cabinet (1); the inlet pipelines of the first peristaltic pump (5), the second peristaltic pump (6), the third peristaltic pump (7), the fourth peristaltic pump (8) and the fifth peristaltic pump (9) are respectively communicated with the storage tank of a nitrogen source, the storage tank of a phosphorus source, the storage tank of a calcium source, the storage tank of trace elements and the storage tank of vitamins, and the storage tanks are arranged in the cabinet (1).

4. The pipeline photobioreactor for cultivating microalgae in a multi-nutrient mode as claimed in claim 3, wherein: a first LED lamp (15) is arranged at the central part of the lower surface of the cover body; an external LED light source is arranged between the front row of transparent pipelines (36) and the rear row of transparent pipelines (36) on the pipe frame (35) or at the rear side of the transparent pipelines (36), the external LED light source comprises a plurality of groups of LED lamp groups arranged at different heights, and each LED lamp group comprises a second LED lamp (37), a third LED lamp (39) and a fourth LED lamp (24) which are sequentially arranged on the pipe frame (35) from top to bottom; the first LED lamp (15) and the second LED lamp (37) are both white LED lamp tubes, the third LED lamp (38) is a red LED lamp tube, and the fourth LED lamp (24) is a blue LED lamp tube; the external LED light sources are parallel to the transparent pipelines (36) and are respectively arranged in one-to-one correspondence with the transparent pipelines (36); the light intensity ranges of the first LED lamp (15), the second LED lamp (37), the third LED lamp (39) and the fourth LED lamp (24) are 0-20000 LUX.

5. The pipeline photobioreactor for culturing microalgae according to claim 4, wherein the pipeline photobioreactor comprises: the circulation main pipe (28) is also provided with a steam pipeline (29) and a flushing pipeline (30); and a circulating pump bypass pipeline (23) is arranged between the inlet and the outlet of the circulating pump (21).

6. The pipeline photobioreactor for culturing microalgae according to claim 5, wherein the pipeline photobioreactor comprises: also includes a control unit; the control unit comprises an upper computer, a PLC (programmable logic controller), a pH sensor (18), a temperature sensor (19), a heating device (17) and a turbidity sensor; the upper computer is provided with a human-computer interaction operation interface (4) and a control program and is in bidirectional connection with the PLC; the input end of the PLC controller is respectively electrically connected with the output ends of the pH sensor (18), the turbidity sensor and the temperature sensor (19), the output end of the PLC controller is respectively electrically connected with an air inlet electromagnetic valve (12) arranged on a carbon dioxide pipeline (11), the first peristaltic pump (5), the second peristaltic pump (6), the third peristaltic pump (7), the fourth peristaltic pump (8), the fifth peristaltic pump (9), the heating device (17) and the first LED lamp (15), the second LED lamp (37), the third LED lamp (3) and the fourth LED lamp (24).

7. The method for using the multi-mode microalgae cultivation pipeline type photobioreactor as claimed in claim 6, wherein:

the using method is any one of autotrophic culture, mixotrophic culture or heterotrophic culture of microalgae; the method comprises the following specific steps: the autotrophic culture comprises reactor sterilization, autotrophic culture medium preparation, algae seed inoculation, algae seed culture, algae liquid collection and reactor cleaning; the mixotrophic culture comprises reactor sterilization, mixotrophic culture medium preparation, culture medium sterilization, culture medium cooling, algae seed inoculation, algae seed culture, algae liquid harvesting and reactor cleaning; the heterotrophic culture comprises reactor sterilization, heterotrophic culture medium preparation, culture medium sterilization, culture medium cooling, algae seed inoculation, algae seed culture, algae liquid harvesting and reactor cleaning;

the reactor sterilization includes buffer tank (34) sterilization and reaction unit sterilization; steam is sequentially led into a buffer tank (34) from a circulation main pipe (28) through a steam pipeline (29), and led into transparent pipelines (36) of the reaction units from discharge pipelines (27) of the reaction units, and the steam and condensate are respectively discharged out of the buffer tank (34) and the reaction units from a discharge branch pipe (20) and a material collecting pipeline (26), so that the sterilization operation of the reactor is completed;

the preparation of the autotrophic medium comprises the following steps: firstly, ultrafiltration water obtained by filtering tap water through a 0.1-micron ultrafiltration membrane is added into a buffer tank (34) from an inoculation port (14) and nutrient salt required by the cultured algae;

the mixotrophic culture medium configuration comprises the following steps: adding tap water into a buffer tank (34) through an inoculation port (14), adding nutrient salts required by the cultured algae seeds from the inoculation port (14), and finally adding glucose from the inoculation port (14) according to the proportion of adding 1g to 10g of glucose into each liter of solution;

the heterotrophic culture medium configuration comprises the following steps: adding tap water into a buffer tank (34) through an inoculation port (14), adding nutrient salts required by the cultured algae seeds from the inoculation port (14), and finally adding glucose from the inoculation port (14) according to the proportion of adding 1g to 20g of glucose into each liter of solution;

the culture medium sterilization comprises the following steps: starting a circulating pump (21) during sterilization to enable the culture medium to circulate between the reaction unit and a buffer tank (34) so as to ensure that the temperature in the culture medium is uniform, heating the culture medium to be more than 90 ℃ through a heating medium, and maintaining for more than 30min to finish the sterilization of the culture medium;

the culture medium cooling comprises the following steps: discharging the heating medium in the heating jacket (16), introducing cooling water, keeping the circulating pump (21) on, and completing the cooling of the culture medium when the temperature of the culture medium is reduced to below 30 ℃;

the inoculation of the algal species comprises the following steps: then, disinfecting the inoculation port (14) by using alcohol, igniting an inoculation loop, opening the inoculation port (14), adding seed liquid to be inoculated into the buffer tank (34) from the inoculation loop, and finishing the inoculation operation;

the algae seed culture comprises the following steps: the light intensity of the first LED lamp (15) and the external LED light source is regulated and controlled by a PLC controller, the circulating pump (21) is kept running, so that the liquid is continuously circulated between the reaction unit and the buffer tank (34), and the flow rate of the algae liquid is controlled to be 30-50 cm/s; meanwhile, the pH value required by algae culture is set through a human-computer interaction interface (4), and when the pH value is higher than a set value, the PLC controls to open the air inlet electromagnetic valve (12) and supplement carbon dioxide into the buffer tank (34); when the pH value is lower than a set value, closing the air inlet electromagnetic valve (12); calculating the change of the turbidity value every day according to the numerical value acquired by the turbidity sensor, and controlling a first peristaltic pump (5), a second peristaltic pump (6), a third peristaltic pump (7), a fourth peristaltic pump (8) and a fifth peristaltic pump (9) by utilizing a PLC (programmable logic controller) so as to further control the supply of a nitrogen source, a phosphorus source, a calcium source, trace elements and vitamins in a buffer tank (34); when the cell concentration of the microalgae is detected, finishing the culture step when the cell concentration of the microalgae is detected to be unchanged for two consecutive days;

the algae liquid is collected in a whole or sectional mode; the steps of all the harvesting are as follows: stopping the circulating pump (21), opening the discharge branch pipes (20) to collect the algae liquid in the buffer tank (34), and opening the collection pipelines (26) to collect all the algae liquid in each reaction unit; the step of sectional recovery is as follows: stopping the circulating pump (21), opening the discharge branch pipe (20) to collect the algae liquid in the buffer tank (34), opening the material collection pipeline (26) to collect the algae liquid in the reaction units, and simultaneously leaving the algae liquid in at least one reaction unit as seed liquid; after the step of sectional collection, when the next culture is carried out, after the buffer tank (34) and the collected reaction unit are cleaned and sterilized, the step of configuring the culture medium in the buffer tank (34) is completed again, and after the step of sterilizing the culture medium in the buffer tank (34) is completed, new algae seeds do not need to be inoculated, and after the step of cooling the culture medium is completed, a new round of microalgae culture step can be carried out; when the algae liquid is collected, the flow rate of the algae liquid is low, and pressurized air can be introduced from the steam pipeline (29) to increase the collection speed of the algae liquid;

the reactor cleaning comprises the following steps: tap water is connected from a flushing pipeline (30), the tap water is sequentially led into the buffer tank from a circulation main pipe (28), and is led into transparent pipelines (36) of the reaction units from discharge pipelines (27) of the reaction units, and the tap water is respectively discharged out of the buffer tank (34) and the reaction units from a discharge branch pipe (20) and a material collecting pipeline (26), so that the cleaning operation of the reactor is completed.

8. The method of claim 7, wherein the method comprises the steps of: when the autotrophic culture of the microalgae is carried out, the flow velocity of the microalgae liquid is 30 cm/s; the control process of the light intensity in the first LED lamp (15) and the external LED light source is as follows: the light intensity of the white LED lamp tube is adjusted to 2000LUX during inoculation, the light intensity is increased to 10000LUX after one day, the light intensity is increased to 15000LUX after two days, 20000LUX is maintained after the third day, and the red LED lamp tube and the blue LED lamp tube are in a closed state.

9. The method of claim 7, wherein the method comprises the steps of: when the mixotrophic culture of the microalgae is carried out, the flow velocity of the microalgae liquid is 50 cm/s; the control process of the light intensity in the first LED lamp (15) and the external LED light source is as follows: only opening the white LED lamp tube and the red LED lamp tube in the first three days of inoculation, wherein the light intensity of the white LED lamp tube and the red LED lamp tube is adjusted to 2000LUX during inoculation, the light intensity is increased to 10000LUX after one day, the light intensity is increased to 15000LUX after two days, and the light intensity is adjusted to 20000LUX on the third day; after three days, only the white LED lamp tube and the blue LED lamp tube are turned on, and the light intensity of the white LED lamp tube and the light intensity of the blue LED lamp tube are adjusted to 20000 LUX.

10. The method of claim 7, wherein the method comprises the steps of: when the heterotrophic culture of the microalgae is carried out, the flow velocity of the microalgae liquid is 50 cm/s; the first LED lamp (15) and the external LED light source are both in an off state.