Efficient microalgae culture device and use method thereof

Abstract

The invention relates to the technical field of microalgae culture devices, in particular to an efficient microalgae culture device and a using method thereof.The efficient microalgae culture device comprises a first-stage raceway pond, a second-stage raceway pond and a third-stage raceway pond which are sequentially stacked from bottom to top, and a partition plate is arranged at the bottom of a pond body of each stage of raceway pond; the horizontal areas of the three layers of raceway ponds are sequentially reduced from bottom to top, and a first-stage stirring system, a second-stage stirring system and a third-stage stirring device are arranged at one time corresponding to each stage of raceway pond; wherein each of the first-stage stirring system and the second-stage stirring system comprises a stirring device and a drainage device, the drainage device comprises a backflow channel and a drainage pipeline, and a lighting system is arranged at the bottom of each stage of raceway pond; the raceway ponds are arranged on the basis of a multi-layer stacking mode, and the effective culture liquid volume in unit occupied area is effectively increased; meanwhile, through the drainage mechanism, culture solution flow inoculation in the multi-stage raceway pond is achieved, the gas-liquid mass transfer efficiency is improved, the inoculation amount and the initial algae cell concentration are greatly improved, the culture period is shortened, and the culture efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of microalgae cultivation device technology, specifically to a high-efficiency microalgae cultivation device and its usage method. Background Technology

[0002] Similar to other microbial cultures, increasing the inoculum ratio in microalgae cultivation helps achieve a higher initial cell concentration, thus gaining an advantage in population competition. A higher inoculum ratio effectively inhibits the growth of contaminating bacteria or algae and promotes rapid entry of microalgae into the logarithmic growth phase, accelerating biomass accumulation. In industrial-scale scaling-up processes, an inoculum ratio of at least 1:10 is typically required, but existing raceway tanks and their operating methods often fail to meet this requirement, thus limiting overall cultivation efficiency. Furthermore, as the most commonly used open system in microalgae autotrophic cultivation, raceway tanks are limited by light penetration depth, typically maintaining only a low culture medium level. This significantly reduces the effective culture volume per unit area, resulting in low photosynthetic efficiency and a yield per unit area far lower than closed systems such as column or tubular photobioreactors. Moreover, the lower liquid level makes it difficult to install gas distributors in raceway tanks, relying solely on natural contact between the liquid surface and air for gas-liquid exchange, leading to extremely low carbon dioxide dissolution efficiency, further restricting the growth rate and cultivation efficiency of microalgae.

[0003] To improve microalgae cultivation efficiency and reduce production costs, researchers have successively developed various improved raceway systems. For example, patent CN201910941046.6 proposes a microalgae cultivation raceway system and its operating method: by setting a guide plate in the center of the pool and installing aeration pipes and lighting devices on its upper and lower sides respectively, the circulating culture medium is divided into upper and lower layers, which simultaneously receive light and gas supply as it flows through the functional area, thereby improving carbon dioxide solubility and light energy utilization to a certain extent. However, this design failed to effectively increase the biomass yield per unit area, and its reliance on compressed air supply not only increased operating costs but also resulted in low gas utilization efficiency due to the short bubble travel distance and insufficient contact time. Patent CN202010913481.0 discloses a circular ladder-type raceway system and its microalgae cultivation method, which adds multi-level annular stepped channels to the traditional straight-channel structure, promoting the reciprocating circulation of the culture medium in the complex flow channels, effectively alleviating the problems of microalgae sedimentation and local dead zones. Nevertheless, this approach still fails to fundamentally address the key bottlenecks hindering efficient microalgae cultivation, such as low yield per unit area, insufficient carbon dioxide dissolution, and uneven light distribution.

[0004] Overall, while existing improved runway pools have made breakthroughs in fluid dynamics and local environmental control, they still have significant limitations in integrating and improving light efficiency, gas efficiency, and space utilization efficiency, urgently requiring more systematic structural and technological innovation. Furthermore, since the beginning of the 21st century, with the increasing scarcity of available land resources, traditional runway pools, due to their inherent drawbacks such as large footprint, low yield per unit area, and high requirements for terrain and water quality, are typically only deployed on marginal lands such as saline-alkali land and tidal flats, severely restricting their widespread application. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency microalgae cultivation device and its method of use that can effectively improve space utilization, light efficiency and gas efficiency, and effectively increase biological yield per unit area.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A high-efficiency microalgae cultivation device includes a primary raceway tank, a secondary raceway tank, and a tertiary raceway tank stacked sequentially from bottom to top. Each of the primary, secondary, and tertiary raceway tanks comprises a rectangular pool with an open top. A partition is installed along the length of the bottom center of each of the three raceway tanks. The horizontal area of ​​the primary, secondary, and tertiary raceway tanks decreases sequentially. A primary stirring system is installed on the outer side of the secondary raceway tank, a secondary stirring system is installed on the outer side of the tertiary raceway tank, and a tertiary stirring device is installed on the inner side of the tank. Both the primary and secondary stirring systems include a stirring device and a flow diversion device, with the flow diversion device containing a flow pipe and a return channel.

[0007] Preferably, both the primary and secondary mixing systems include mixing blades, which are rotatably connected to the bearing structure and the secondary and tertiary raceway pool bodies via mixing shafts. The bottom of the mixing blades in the primary mixing system extends into one side of the internal partition of the primary raceway pool, and the bottom of the mixing blades in the secondary mixing system extends into one side of the internal partition of the secondary raceway pool. The tertiary mixing device includes mixing blades, which are fixedly mounted on the mixing shaft of the secondary mixing system, and the bottom of the mixing blades in the tertiary mixing device extends into one side of the internal partition of the tertiary raceway pool. The mixing shafts are all horizontally positioned, and their length direction is perpendicular to the length direction of the partition.

[0008] Preferably, the height difference between the bottom of the primary, secondary, and tertiary runway pools is 40-60cm; the height difference between the agitator shaft of the primary agitator system and the bottom of the secondary runway pool, and the height difference between the agitator shaft of the secondary agitator system and the bottom of the tertiary runway pool, are 35-55cm; the agitator blade radius of the primary and secondary agitator systems is 70-110cm; and the agitator blade radius of the tertiary agitator is 30-50cm.

[0009] Preferably, the diversion device includes a vortex-shaped diversion pipe with an opening at the outer end; the stirring shaft has a hollow structure inside, and the inner end of the diversion pipe is connected to the interior of the stirring shaft; the stirring shaft is connected to a diversion channel and a return channel, with a diversion valve at the inlet of the diversion channel and a return valve at the inlet of the return channel.

[0010] Preferably, the outlet end of the diversion channel of the primary mixing system is configured to cooperate with the secondary raceway pool, and the outlet end of the return channel of the primary mixing system is configured to cooperate with the primary raceway pool; the outlet end of the diversion channel of the secondary mixing system is configured to cooperate with the tertiary raceway pool, and the outlet end of the return channel of the secondary mixing system is configured to cooperate with the secondary raceway pool.

[0011] Preferably, the bottom of the primary, secondary, and tertiary running track pools are provided with sewage outlets, and the sides of the secondary and tertiary running track pools are provided with overflow outlets; the overflow outlet of the secondary running track pool is connected to the primary running track pool through an overflow channel, and the overflow outlet of the tertiary running track pool is connected to the secondary running track pool through an overflow channel.

[0012] Preferably, the primary, secondary, and tertiary runway pools are all equipped with lighting systems, which include fiber optic lighting systems or solar lighting systems.

[0013] A method for microalgae cultivation, characterized by including a seed culture / isotropic culture mode and a propagation mode: Seed culture / individual culture mode: Microalgae are cultured in a single primary raceway tank, a secondary raceway tank, or a tertiary raceway tank. During the culture process, the primary, secondary, or tertiary stirring system is activated separately to circulate and stir the culture medium in the raceway tank. Expansion cultivation mode: Simultaneous use of primary and secondary raceway tanks, secondary and tertiary raceway tanks, or simultaneous use of primary, secondary and tertiary raceway tanks for microalgae cultivation; during the cultivation process, the stirring system or stirring device corresponding to the raceway tank in use is activated to circulate and stir the culture medium in the raceway tank. At the same time, the culture medium in the upper raceway tank is diverted to the lower raceway tank through the diversion device, and the culture medium in the lower raceway tank is returned to the upper raceway tank through the overflow port.

[0014] Preferably, the specific process of the seed culture / individual culture mode includes: Using the primary raceway tank alone: ​​Close the drainage valve of the drainage channel in the primary mixing system and open the return valve of the return channel; inject the culture medium and microalgae into the primary raceway tank, turn on the primary mixing system, drive the mixing blades to rotate, and drive the culture medium to circulate in the primary raceway tank; at the same time, when the culture medium enters the drainage pipe, it mixes with air and is then reinjected into the primary raceway tank through the return channel to complete the gas-liquid exchange. Using the secondary raceway tank alone: ​​Close the drainage valve of the drainage channel in the secondary mixing system and open the return valve of the return channel; inject the culture medium and microalgae into the secondary raceway tank, turn on the secondary mixing system, drive the mixing blades to rotate, and drive the culture medium to circulate in the secondary raceway tank; at the same time, when the culture medium enters the drainage pipe, it mixes with air and is then reinjected into the secondary raceway tank through the return channel to complete the gas-liquid exchange; Using the three-stage raceway tank alone: ​​Inject culture medium and microalgae into the three-stage raceway tank, turn on the three-stage stirring device, drive the stirring blades to rotate, and drive the culture medium to circulate in the three-stage raceway tank.

[0015] Preferably, the specific process of the expansion cultivation mode includes: Simultaneous use of primary and secondary raceway tanks: When the microalgae culture in the primary raceway tank meets the requirements for seed use, water or culture medium is injected into the secondary raceway tank, so that the primary raceway tank inoculates the secondary raceway tank; the reflux valve of the reflux channel in the primary mixing system is closed, and the drainage valve of the drainage channel is opened; the drainage valve of the drainage channel in the secondary mixing system is closed, and the reflux valve of the reflux channel is opened; and the primary and secondary mixing systems are turned on at the same time, driving the mixing blades to rotate, causing the culture medium to circulate in the primary and secondary raceway tanks; When using both a secondary and tertiary raceway tank: Once the microalgae culture in the secondary raceway tank meets the requirements for seed use, inject water or culture medium into the tertiary raceway tank to inoculate the secondary raceway tank into the tertiary raceway tank; close the reflux valve of the reflux channel in the secondary mixing system and open the drainage valve of the drainage channel; and simultaneously turn on the secondary mixing system and the tertiary mixing device to drive the mixing blades to rotate, causing the culture medium to circulate between the secondary and tertiary raceway tanks. When using a primary, secondary, and tertiary raceway tank simultaneously: Once the microalgae culture in the primary raceway tank meets the requirements for seed use, inject water or culture medium into the secondary and tertiary raceway tanks, so that the primary raceway tank inoculates the secondary and tertiary raceway tanks; close the reflux valve of the reflux channel in the primary mixing system and open the drainage valve of the drainage channel; close the reflux valve of the reflux channel in the secondary mixing system and open the drainage valve of the drainage channel; and simultaneously start the primary, secondary, and tertiary mixing systems, driving the mixing blades to rotate and causing the culture medium to circulate in the primary, secondary, and tertiary raceway tanks.

[0016] The beneficial effects of this invention are: This invention employs a multi-layered stacked raceway pool method, thereby accommodating more culture medium within the same raceway pool area, significantly increasing the culture capacity per unit area, improving space utilization and biological yield per unit area.

[0017] This invention incorporates a stirring system or device in each of the three raceway tanks. The stirring paddles drive the culture medium in the raceway tanks to flow directionally around the baffles. The stirring system also includes drainage pipes that cooperate with a hollow stirring shaft. Each drainage pipe has a drainage channel leading to the next stage raceway tank and a return channel leading to the same stage raceway tank. The drainage pipes can be switched between drainage and return modes by valve control, thereby enabling individual cultivation in a single-stage raceway tank or switching between multi-stage raceway tank combined expansion cultivation modes.

[0018] The drainage device of the present invention can simultaneously drain or return the culture medium and inject air and culture medium together into the next or same level raceway pool, thereby effectively extending the gas-liquid contact path and greatly enhancing the mass transfer efficiency between air, especially carbon dioxide, and the culture medium.

[0019] This invention employs a multi-level raceway pool structure with progressively decreasing horizontal area from bottom to top. The lowest level raceway pool serves as the main culture unit with a substantial volume, while the volume of subsequent expansion raceway pools decreases progressively. Since the volume of the first-level raceway pool is greater than the combined volume of the culture medium in the second and third-level raceway pools, the mature microalgae seed culture in the first-level raceway pool is mixed with the culture medium in the second and third-level raceway pools. This results in a very high initial biomass in the second and third-level raceway pools, leading to rapid proliferation. Simultaneously, the algal cell concentration in the first-level raceway pool is diluted and replenished with nutrients, allowing it to re-enter the rapid proliferation phase. This gradient configuration ensures that the actual inoculation ratio during the inoculation process is far higher than the 1:10 requirement in conventional microbial culture, thereby helping the microalgae to quickly establish population dominance in the initial stage, rapidly enter the logarithmic growth phase, and significantly improve overall culture efficiency and biomass accumulation rate.

[0020] The invention also includes an underwater lighting system evenly distributed at the bottom of each raceway pool to actively supplement the light in the culture medium. This effectively compensates for the problem of insufficient light at the bottom layer caused by the limited light penetration depth when relying on natural light in the traditional method, so that the microalgae can obtain sufficient light energy throughout the liquid layer and promote uniform growth. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 2 This is a top view of Embodiment 1 of the present invention; Figure 3 This is a top view of the primary runway pool in Embodiment 1 of the present invention; Figure 4 This is a top view of the secondary runway pool in Embodiment 1 of the present invention; Figure 5 This is a top view of the three-stage runway pool in Embodiment 1 of the present invention; Figure 6 This is a side view of the primary and secondary runway pools in Embodiment 1 of the present invention. Figure 7 This is a side view of the combination of a secondary raceway pool and a tertiary raceway pool in Embodiment 1 of the present invention; Figure 8 This is a side sectional view of the three-stage runway pool according to Embodiment 1 of the present invention; Figure 9 This is a schematic diagram of the internal structure of the stirring shaft in the primary stirring system of Embodiment 1 of the present invention; Figure 10 This is a schematic diagram of the internal structure of the stirring shaft in the secondary stirring system of Embodiment 1 of the present invention; Figure 11 This is a schematic diagram of the lighting system structure of Embodiment 1 of the present invention.

[0022] In the diagram: Primary racetrack pool 1; Primary baffle 11; Primary pool body 12; Primary drain outlet 13; Secondary racetrack pool 2; Secondary baffle 21; Secondary pool body 22; Primary mixing system 23; Primary drainage pipe 231; Primary mixing blade 232; Primary mixing shaft 233; Primary return valve 2331; Primary drainage valve 2332; Primary mixing bearing 24; Primary drainage pipe outlet 25; Secondary overflow outlet 26; Secondary drain outlet 27; III 3. Stage raceway pool; 31. Stage 3 partition; 32. Stage 3 pool body; 33. Stage 2 mixing system; 331. Stage 2 drainage pipe; 332. Stage 2 mixing blade; 333. Stage 2 mixing shaft; 333. Stage 2 reflux valve; 3331. Stage 2 drainage valve; 3332. Stage 2 mixing bearing; 35. Stage 2 drainage pipe outlet; 36. Stage 3 overflow outlet; 37. Stage 3 mixing device; 38. Stage 3 sewage outlet; 4. Lighting system; 41. Photoconductor; 42. Optical fiber; 43. Submersible lighting fixture. Detailed Implementation Example

[0023] The following is a further explanation of the present invention in conjunction with specific embodiments, such as... Figure 1 As shown, this embodiment is a high-efficiency microalgae cultivation device, which mainly includes a primary raceway pool 1, a secondary raceway pool 2, and a tertiary raceway pool 3 stacked sequentially from bottom to top. Each of the primary raceway pool 1, secondary raceway pool 2, and tertiary raceway pool 3 includes a cuboid pool with an open top, and the horizontal area of ​​each raceway pool decreases sequentially from bottom to top, so that the volume of the primary raceway pool is greater than the sum of the volumes of the secondary and tertiary raceway pools. The three raceway pools are installed by a bracket, and the spacing height between each raceway pool can be controlled by adjusting the size of the bracket.

[0024] like Figure 2-5 As shown, a primary baffle 11 is provided at the center of the bottom of the primary pool 12. The length direction of the primary baffle 11 is the same as that of the primary pool 12, and there are gaps between its two ends and the inner sides of the two ends of the primary pool 12, so that the culture medium can flow freely to both sides from the gaps at both ends of the primary baffle 11. Similarly, a secondary baffle 21 is provided at the bottom of the secondary pool 22, and a tertiary baffle 31 is provided at the bottom of the tertiary pool 32.

[0025] A primary stirring system 23 is provided on the secondary tank 22 to stir the culture medium in the primary tank 12; a secondary stirring system 33 is provided on the tertiary tank 32 to stir the culture medium in the secondary tank 12.

[0026] The primary stirring system 23 includes a primary stirring shaft 233, which is mounted on the secondary tank 22 via multiple primary stirring bearings 24 and can rotate freely. One end of the primary stirring shaft 233 is connected to a drive motor, allowing it to rotate under the action of the drive motor. The other end extends outside the secondary tank 22, above the primary tank 12, and is fixedly connected to a primary stirring blade 232. When the primary stirring shaft 233 starts to rotate, it drives the primary stirring blade 232 to rotate synchronously. The lowest end of the primary stirring blade 232 extends into the outer side of the primary partition 11 inside the primary tank 12, so that when the primary stirring blade 232 starts to rotate, it drives the culture medium inside the primary tank 12 to flow. A primary drainage pipe 231 is also provided on the primary stirring shaft 233, such as... Figure 6 As shown, the primary drainage pipe 231 has a vortex-shaped pipe structure, with an opening at its outer end. The opening direction is the same as the rotation direction of the primary stirring blade 232, so that when the opening end reaches the primary tank 12, the culture medium in the primary tank 12 can be introduced into the primary drainage pipe 231; as shown Figure 4 and 9As shown, the interior of the primary stirring shaft 233 is hollow. The inner end of the primary drainage pipe 231 is connected to the interior of the primary stirring shaft 233, so that the culture medium in the primary drainage pipe 231 can enter the primary stirring shaft 233 as the primary drainage pipe 231 rotates. The primary stirring shaft 233 is connected to a drainage channel and a return channel. The outlet 25 of the primary drainage pipe is connected to the secondary raceway pool 2, and a primary drainage valve 2332 is installed at the inlet of the drainage channel. The end of the return channel is connected to the primary raceway pool 1, and a primary return valve 2331 is installed at the inlet of the return channel.

[0027] The secondary stirring system 33 includes a secondary stirring shaft 333, which is mounted on the tertiary tank 32 via multiple secondary stirring bearings 34 and can rotate freely. One end of the secondary stirring shaft 333 is connected to a drive motor, allowing it to rotate under the motor's influence. The other end extends beyond the tertiary tank 32, above the secondary tank 22, and is fixedly connected to a secondary stirring blade 332. When the secondary stirring shaft 333 starts rotating, it drives the secondary stirring blade 332 to rotate synchronously. The lowest point of the secondary stirring blade 332 extends into the outer side of the secondary baffle 21 inside the secondary tank 22, causing the culture medium inside the secondary tank 22 to flow when the secondary stirring blade 332 starts rotating. A secondary drainage pipe 331 is also provided on the secondary stirring shaft 333, such as... Figure 7 As shown, the secondary drainage pipe 331 has a vortex-shaped pipe structure, with an opening at its outer end. The opening direction is the same as the rotation direction of the secondary stirring blade 332, so that when the opening end reaches the secondary tank 22, the culture medium in the secondary tank 22 can be introduced into the secondary drainage pipe 331; as shown Figure 5 and 10 As shown, the interior of the secondary stirring shaft 333 is hollow. The inner end of the secondary drainage pipe 331 is connected to the interior of the secondary stirring shaft 333, so that the culture medium in the secondary drainage pipe 331 can enter the secondary stirring shaft 333 as the secondary drainage pipe 331 rotates. The secondary stirring shaft 333 is connected to a drainage channel and a return channel. The secondary drainage pipe 35 is connected to the tertiary raceway pool 3, and a secondary drainage valve 3332 is installed at the inlet of the drainage channel. The end of the return channel is connected to the secondary raceway pool 2, and a secondary return valve 3331 is installed at the inlet of the return channel.

[0028] like Figure 8As shown, a tertiary stirring device 37 is provided on the secondary stirring shaft 333. The tertiary stirring device 37 mainly includes a tertiary stirring blade structure, which is fixedly installed on the secondary stirring shaft 333. When the drive motor drives the secondary stirring shaft 333 to rotate, it will also drive the tertiary stirring blade to rotate. The lowest end of the tertiary stirring blade extends into one side of the tertiary partition 31 inside the tertiary tank 32. When it rotates, it can drive the culture medium in the tertiary raceway tank 3 to flow.

[0029] like Figure 3-8 As shown, a primary drain outlet 13 is provided on one side of the bottom of the primary tank 12, and the primary drain outlet 13 is located on the opposite side of the primary stirring blade 232; a secondary drain outlet 13 is provided on one side of the bottom of the secondary tank 22, and a secondary drain outlet 23 is located on the opposite side of the secondary stirring blade 332; a tertiary drain outlet 38 is provided on one side of the bottom of the tertiary tank 32, and a tertiary drain outlet 38 is located on the opposite side of the tertiary stirring blade; on one side of the secondary tank 22... A secondary overflow port 26 is provided on the side, and the direction of the secondary overflow port 26 is the same as that of the primary stirring system 23. It is connected to the primary tank 12, so that the culture medium flowing out of the secondary overflow port 26 can flow back into the primary tank 12. A tertiary overflow port 36 is provided on one side of the tertiary tank 32, and the direction of the tertiary overflow port 36 is the same as that of the secondary stirring system 33. It is connected to the secondary tank 22, so that the culture medium flowing out of the tertiary overflow port 36 can flow back into the secondary tank 22.

[0030] In this embodiment, the height difference between adjacent racetrack pools is 50cm. The primary stirring shaft 233 is positioned 40cm above the bottom of the secondary pool 22, and the secondary stirring shaft 333 is positioned 40cm above the bottom of the tertiary pool 32. The radii of the primary stirring blades 232 and 332 are 80cm, and the radius of the tertiary stirring blades is 30cm. The height of each overflow port from the bottom of the corresponding pool is 40cm, and the height of the side plate of each pool is 45cm.

[0031] Each track pool is equipped with a lighting system 4, such as Figure 11 As shown, the lighting system 4 in this embodiment adopts an optical fiber lighting system, which specifically includes a light collector 41 for collecting external light. The light collector 41 transmits the light to the underwater lighting fixture 43 through the optical fiber 42. The underwater lighting fixture 43 is set at the bottom of each raceway pool and can provide light to the culture medium in the raceway pool. Example

[0032] The difference between this embodiment and embodiment 1 is that the lighting system 4 in this embodiment is a solar lighting system. The light collector 41 is replaced with a solar cell module, which can convert solar energy into electrical energy and store it in a battery. The solar cell module is connected to the underwater lighting fixture 43 through a cable, which can supply power to the underwater lighting fixture 43 and make it emit light to provide illumination for the culture medium in the raceway pool. Example

[0033] This embodiment describes a method for microalgae cultivation based on the high-efficiency microalgae cultivation device proposed in Embodiment 1 or Embodiment 2. In this embodiment, only a single-stage raceway pool is used for seed culture / individual culture mode, and the specific process includes: Fill the primary raceway pool 1 with water to a height of 30cm, turn on the primary stirring system 23, close the primary drainage valve 2332, and open the primary return valve 2331; introduce ozone into the water for disinfection, then let it stand for 2 hours, and then add BG11 culture medium and Chlorella seeds.

[0034] During the cultivation process, the culture medium not only circulates within the primary raceway tank 1 but also passes through the primary drainage pipe 231. During this time, some air is introduced into the primary drainage pipe 231, promoting thorough gas-liquid exchange and improving carbon dioxide dissolution efficiency and oxygen removal. Cultivation reaches OD... 680 Harvesting begins when the volume reaches approximately 1. Taking a 1000L volume primary raceway pool 1 as an example, 1000L of culture medium can be obtained. Example

[0035] The difference between this embodiment and embodiment 3 is that this embodiment only uses the secondary raceway pool 2 for seed culture / individual culture mode, and the specific process includes: Fill the secondary raceway pool 2 with water to a height of 30cm, turn on the secondary stirring system 33, close the secondary drainage valve 3332, and open the secondary reflux valve 3331; introduce ozone into the water for disinfection, then let it stand for 2 hours, and then add SP culture medium and spirulina seeds.

[0036] During the cultivation process, the culture medium not only circulates within the secondary raceway tank 2 but also passes through the secondary drainage pipe 331. During this time, some air is introduced into the secondary drainage pipe 331, promoting thorough gas-liquid exchange and improving carbon dioxide dissolution efficiency and oxygen removal. Cultivation reaches OD... 680 Harvesting begins when the culture medium reaches approximately 0.7. Taking a 500L volume primary raceway pool 1 as an example, 500L of culture medium can be obtained. Example

[0037] The difference between this embodiment and embodiment 4 is that this embodiment only uses the three-stage raceway pool 3 for seed culture / individual culture mode, and the specific process includes: Fill the three-stage raceway pool 3 with water to a height of 30cm, turn on the drive motor to drive the secondary stirring shaft 333 to rotate, which in turn drives the tertiary stirring blades to rotate; introduce ozone into the water for disinfection, then let it stand for 2 hours, and then add SP culture medium and spirulina seeds.

[0038] In this way, the culture medium circulates repeatedly in the three-stage raceway tank, and biomass continuously accumulates. Cultured until OD... 680 Harvesting begins when the culture medium reaches approximately 0.7. Taking a 250L three-stage raceway pool as an example, 250L of culture medium can be obtained. Example

[0039] The difference between this embodiment and embodiment 3 is that this embodiment uses a method that simultaneously activates the primary runway pool 1 and the secondary runway pool 2 for expansion culture. The specific process includes: First, the primary runway pool was cultured to OD using the method described in Example 3. 680 When the water level reaches approximately 1, preparations can begin for inoculation in the secondary track pool. Fill the secondary track pool 2 with water to a height of 30cm, turn on the secondary mixing system 33, close the secondary drainage valve 3332, and open the secondary return valve 3331. Simultaneously, keep the primary drainage valve 2332 closed and the primary return valve 2331 open, ensuring that the liquids in the primary track pool 1 and the secondary track pool 2 circulate independently without mutual flow. Introduce ozone into the water in the secondary track pool 2 for disinfection, then let it stand for 2 hours. Afterward, open the primary drainage valve 2332 and close the primary return valve 2331, allowing the liquids in the primary track pool 1 to circulate independently without mutual flow. The culture medium can be guided to the secondary raceway pool 2 by the primary drainage pipe 231. When the liquid level in the secondary raceway pool 2 reaches the height of the secondary overflow port 26, it can flow back to the primary raceway pool 1 through the secondary overflow port 26. In this way, the culture medium forms a circulation between the primary raceway pool 1 and the secondary raceway pool 2. During this process, the mature seed liquid in the primary raceway pool 1 completes the inoculation of the secondary raceway pool 2. At the same time, when the culture medium passes through the drainage pipe, it will also bring some air into the drainage pipe, which will promote the full exchange between gas and liquid, improve the carbon dioxide dissolution efficiency and oxygen removal effect.

[0040] Secondary runway pool starting OD 680 The inoculum concentration reached as high as 0.6, with an inoculation ratio as high as 2:1. Taking a 1000L primary track pool and a 500L secondary track pool as examples, the culture was repeated until the OD (October Resultant) was reached. 680 When the concentration is around 1, it only takes 4 days to obtain 1500L of culture medium. Example

[0041] The difference between this embodiment and embodiment 6 is that this embodiment is a method for using both the secondary runway pool 2 and the tertiary runway pool 3 simultaneously in an expansion culture mode. The specific process includes: First, the secondary runway pool 2 was cultured to OD. 680 Around step 1, preparations can be made for inoculation of the tertiary track pool 3; fill the tertiary track pool 3 with water to a height of 30cm, turn on the drive motor to drive the secondary stirring shaft 333 to rotate, driving the secondary stirring blades 332 and tertiary stirring blades to rotate, while keeping the secondary drainage valve 3332 closed and the secondary return valve 3331 open, so that the liquids in the tertiary track pool 3 and the tertiary track pool 2 circulate independently without mutual flow; ozone is introduced into the water of the tertiary track pool 3 for disinfection, and then left to stand for 2 hours; after standing, the secondary drainage valve 3332 is opened and the secondary return valve 3331 is closed .... The culture medium in pool 2 can be drained to the tertiary raceway pool 3 by the secondary drainage pipe 331. When the liquid level in the tertiary raceway pool 3 reaches the height of the tertiary overflow port 36, it can flow back to the secondary raceway pool 2 through the tertiary overflow port 36. In this way, the culture medium forms a circulation between the secondary raceway pool 2 and the tertiary raceway pool 3. During this process, the mature seed liquid in the secondary raceway pool 2 completes the inoculation of the tertiary raceway pool 3. At the same time, when the culture medium passes through the drainage pipe, it will also bring some air into the drainage pipe, which will promote the full exchange between gas and liquid, improve the carbon dioxide dissolution efficiency and oxygen removal effect.

[0042] Level 3 runway pool starting OD 680 The inoculum size reached as high as 0.6, with an inoculation ratio as high as 2:1. Taking a 500L secondary runway tank and a 250L tertiary runway tank as examples, the culture was repeated until the OD (October Resultant) was reached. 680 When the concentration is around 1, it only takes 4 days to obtain 750L of culture medium. Example

[0043] The difference between this embodiment and embodiment 7 is that this embodiment is a method for using a propagation mode that simultaneously activates the primary runway pool 1, the secondary runway pool 2, and the tertiary runway pool 3. The specific process includes: First, cultivate the first-level runway pool 1 to OD. 680Around step 1, preparations can be made for inoculation of the secondary track pool 2 and the tertiary track pool 3. Fill the secondary track pool 2 and the tertiary track pool 3 with water to a height of 30cm, turn on the secondary mixing system 33 and the tertiary mixing device 37, keep the primary drainage valve 2332 closed and the primary return valve 2331 open, keep the secondary drainage valve 3332 closed and the secondary return valve 3331 open, so that the liquids in the primary track pool 1, secondary track pool 2 and tertiary track pool 3 remain in an independent flow state; then, ozone disinfection is carried into the water in the secondary track pool 2 and the tertiary track pool 3 respectively, and after disinfection, let it stand for 2 hours; then open the primary drainage valve 2332. 32. Close the primary reflux valve 2331, open the secondary drainage valve 3332, and close the secondary reflux valve 3331. This allows the culture medium in the primary runway pool 1 to be drained to the secondary runway pool 2 under the action of the primary drainage pipe 231, and the culture medium in the secondary runway pool 2 to be drained to the tertiary runway pool 3 under the action of the secondary drainage pipe 331. At the same time, the culture medium in the secondary runway pool 2 can be returned to the primary runway pool 1 through the secondary overflow port 26, and the culture medium in the tertiary runway pool 3 can be returned to the secondary runway pool 2 through the tertiary overflow port 36. In this process, the primary runway pool 1 completes the inoculation of the secondary runway pool 2 and the tertiary runway pool 3. Level 3 runway pool starting OD 680 The inoculation ratio reached as high as 0.5, with a ratio as high as 1.3:1. Taking a 1000L primary track pool, a 500L secondary track pool, and a 250L tertiary track pool as examples, the culture was again carried out to OD... 680 When the concentration is around 1, it only takes 5 days to obtain 1750L of culture medium. Example

[0044] This embodiment is an experimental comparison between microalgae cultivation based on a traditional raceway pond and the device and method proposed in this invention.

[0045] Approximately 30 cm of water was added to a traditional runway tank. The agitator was turned on, and ozone was introduced for disinfection. After disinfection, the tank was allowed to stand for 2 hours. Then, culture medium was added and inoculated using a 100L column reactor at an inoculation ratio of 1:10, initially only 0.1. During this process, the culture medium circulated repeatedly within the runway tank, exchanging gas and liquid only with the surface air and receiving only surface sunlight. After 15 days of incubation, when the OD... 680 Harvesting begins when the temperature reaches approximately 1. Taking a 1000L primary raceway pool as an example, 1000L of culture medium can be obtained.

[0046] By comparing the data obtained from the experiment in this embodiment with the data in the previous embodiment, it can be found that the device and method proposed in this invention have significantly improved the culture cycle and the biological yield per unit space compared with traditional raceway pools and traditional culture methods.

[0047] The above description is merely a further explanation of the present invention in conjunction with specific embodiments. All descriptions made do not imply any limitation on the scope of protection of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-efficiency microalgae cultivation device, comprising a primary raceway tank, a secondary raceway tank, and a tertiary raceway tank stacked sequentially from bottom to top, characterized in that: The primary, secondary, and tertiary running track pools all comprise rectangular pools with an open top. A partition is installed along the length of the pool at the center of its bottom. The horizontal area of ​​the primary, secondary, and tertiary running track pools decreases sequentially. A primary agitation system is installed on the outer side of the secondary running track pool, a secondary agitation system is installed on the outer side of the tertiary running track pool, and a tertiary agitation device is installed on the inner side of the pool. Both the primary and secondary agitation systems include an agitation device and a flow diversion device, with the flow diversion device containing a flow pipe and a return channel.

2. The high-efficiency microalgae cultivation device according to claim 1, characterized in that: Both the primary and secondary mixing systems include mixing blades, which are rotatably connected to the bearing structure and the secondary and tertiary racetrack pool bodies via mixing shafts. The bottom of the mixing blades in the primary mixing system extends into one side of the internal partition of the primary racetrack pool, and the mixing blades in the secondary mixing system extend into one side of the internal partition of the secondary racetrack pool. The tertiary mixing device includes mixing blades, which are fixedly mounted on the mixing shaft of the secondary mixing system. The bottom of the mixing blades in the tertiary mixing device extends into one side of the internal partition of the tertiary racetrack pool. All mixing shafts are horizontally positioned, with their length direction perpendicular to the length direction of the partition.

3. The high-efficiency microalgae cultivation device according to claim 2, characterized in that: The height difference between the bottom of the primary, secondary, and tertiary runway pools is 40-60cm. The height difference between the agitator shaft of the primary agitator system and the bottom of the secondary runway pool, and the height difference between the agitator shaft of the secondary agitator system and the bottom of the tertiary runway pool, are both 35-55cm. The agitator blade radius of the primary and secondary agitator systems is 70-110cm. The agitator blade radius of the tertiary agitator is 30-50cm.

4. The high-efficiency microalgae cultivation device according to claim 2, characterized in that: The diversion device includes a vortex-shaped diversion pipe with an opening at the outer end; the stirring shaft has a hollow interior, and the inner end of the diversion pipe is connected to the interior of the stirring shaft; the stirring shaft is connected to a diversion channel and a return channel, with a diversion valve at the inlet of the diversion channel and a return valve at the inlet of the return channel.

5. The high-efficiency microalgae cultivation device according to claim 4, characterized in that: The outlet end of the diversion channel of the primary mixing system is configured to cooperate with the secondary raceway pool, and the outlet end of the return channel of the primary mixing system is configured to cooperate with the primary raceway pool; the outlet end of the diversion channel of the secondary mixing system is configured to cooperate with the tertiary raceway pool, and the outlet end of the return channel of the secondary mixing system is configured to cooperate with the secondary raceway pool.

6. The high-efficiency microalgae cultivation device according to claim 5, characterized in that: The bottom of the primary, secondary, and tertiary running track pools are all equipped with sewage outlets, and the sides of the secondary and tertiary running track pools are equipped with overflow outlets. The overflow outlet of the secondary running track pool is connected to the primary running track pool through an overflow channel, and the overflow outlet of the tertiary running track pool is connected to the secondary running track pool through an overflow channel.

7. The high-efficiency microalgae cultivation device according to claim 1, characterized in that: The bottom of the primary, secondary, and tertiary runway pools are all equipped with lighting systems, which include fiber optic lighting systems or solar lighting systems.

8. A method for microalgae cultivation using the apparatus according to any one of claims 1-7, characterized in that: Including seed culture / individual culture mode and propagation mode: Seed culture / individual culture mode: Microalgae are cultured in a single primary raceway tank, a secondary raceway tank, or a tertiary raceway tank. During the culture process, the primary, secondary, or tertiary stirring system is activated separately to circulate and stir the culture medium in the raceway tank. Expansion cultivation mode: Simultaneous use of primary and secondary raceway tanks, secondary and tertiary raceway tanks, or simultaneous use of primary, secondary and tertiary raceway tanks for microalgae cultivation; during the cultivation process, the stirring system or stirring device corresponding to the raceway tank in use is activated to circulate and stir the culture medium in the raceway tank. At the same time, the culture medium in the upper raceway tank is diverted to the lower raceway tank through the diversion device, and the culture medium in the lower raceway tank is returned to the upper raceway tank through the overflow port.

9. The microalgae cultivation method according to claim 8, characterized in that: The specific process of the seed culture / individual culture mode includes: Using the primary raceway tank alone: ​​Close the drainage valve of the drainage channel in the primary mixing system and open the return valve of the return channel; inject the culture medium and microalgae into the primary raceway tank, turn on the primary mixing system, drive the mixing blades to rotate, and drive the culture medium to circulate in the primary raceway tank; at the same time, when the culture medium enters the drainage pipe, it mixes with air and is then reinjected into the primary raceway tank through the return channel to complete the gas-liquid exchange. Using the secondary raceway tank alone: ​​Close the drainage valve of the drainage channel in the secondary mixing system and open the return valve of the return channel; inject the culture medium and microalgae into the secondary raceway tank, turn on the secondary mixing system, drive the mixing blades to rotate, and drive the culture medium to circulate in the secondary raceway tank; at the same time, when the culture medium enters the drainage pipe, it mixes with air and is then reinjected into the secondary raceway tank through the return channel to complete the gas-liquid exchange; Using the three-stage raceway tank alone: ​​Inject culture medium and microalgae into the three-stage raceway tank, turn on the three-stage stirring device, drive the stirring blades to rotate, and drive the culture medium to circulate in the three-stage raceway tank.

10. The microalgae cultivation method according to claim 8, characterized in that: The specific process of the aforementioned extended cultivation model includes: Simultaneous use of primary and secondary raceway tanks: When the microalgae culture in the primary raceway tank meets the requirements for seed use, water or culture medium is injected into the secondary raceway tank, so that the primary raceway tank inoculates the secondary raceway tank; the reflux valve of the reflux channel in the primary mixing system is closed, and the drainage valve of the drainage channel is opened; the drainage valve of the drainage channel in the secondary mixing system is closed, and the reflux valve of the reflux channel is opened; and the primary and secondary mixing systems are turned on at the same time, driving the mixing blades to rotate, causing the culture medium to circulate in the primary and secondary raceway tanks; When using both a secondary and tertiary raceway tank: Once the microalgae culture in the secondary raceway tank meets the requirements for seed use, inject water or culture medium into the tertiary raceway tank to inoculate the secondary raceway tank into the tertiary raceway tank; close the reflux valve of the reflux channel in the secondary mixing system and open the drainage valve of the drainage channel; and simultaneously turn on the secondary mixing system and the tertiary mixing device to drive the mixing blades to rotate, causing the culture medium to circulate between the secondary and tertiary raceway tanks. When using primary, secondary, and tertiary raceway tanks simultaneously: Once the microalgae culture in the primary raceway tank meets the requirements for seed use, inject water or culture medium into the secondary and tertiary raceway tanks, so that the primary raceway tank inoculates the secondary and tertiary raceway tanks; close the reflux valve of the reflux channel in the primary mixing system and open the drainage valve of the drainage channel; close the reflux valve of the reflux channel in the secondary mixing system and open the drainage valve of the drainage channel; and simultaneously start the primary, secondary, and tertiary mixing systems, driving the mixing blades to rotate and causing the culture medium to circulate in the primary, secondary, and tertiary raceway tanks.

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