Apparatus and method for large-scale cultivation of haematococcus pluvialis by outdoor photobioreactor

Abstract

This invention provides an apparatus and method for large-scale cultivation of Haematococcus pluvialis in an outdoor photobioreactor, comprising: an interconnected and mutually restraining foundation to construct a stable base to prevent local settlement; an A-frame structure as a support on the base, the angle between the A-frame support and the ground being 45°–75°, with the above-ground structure interconnected; horizontally parallel rows of uniformly sized, horizontally parallel tubular photobioreactors for cultivating Haematococcus pluvialis, placed on the interlocking openings on the inclined surfaces of the A-frame support, the tubular photobioreactors at the same horizontal position being interconnected by U-shaped connecting pipes to form a continuous, sealed pipeline; a peristaltic pump at the near-ground end, which uses power to pump the culture medium upwards to the highest point, flowing through all the tubular photobioreactors and back to the pump, forming a circulation. This invention also provides a method for large-scale cultivation of Haematococcus pluvialis in an outdoor photobioreactor.

Description

Technical Field

[0001] This invention relates to the field of artificial cultivation technology of economic microalgae, and in particular to an outdoor photobioreactor for large-scale cultivation of Haematococcus pluvialis and its method. Background Technology

[0002] As photoautotrophic organisms, economically valuable microalgae rely on natural light resources for efficient and safe production, making this crucial factor in the success of related aquaculture models. Photobioreactors located outdoors often utilize unidirectional light sources. Compared to indoor, automated, intelligent supplemental lighting methods, they offer more abundant and inexpensive natural light resources. However, they also face challenges such as mutual shading between upper and lower layers, ensuring safe communication of the culture medium, uneven sediment settling due to varying loads at different times and locations, dust accumulation, and strong wind loads.

[0003] Open-type microalgae culture tanks represent a basic form for large-scale outdoor use, characterized by simple structure, convenient operation, and low cost, such as racetrack tanks for Spirulina recirculating aquaculture. However, the cultivation process in open facilities is highly susceptible to and subject to drastic changes in the external environment, making it difficult to provide suitable cultivation conditions. They are easily contaminated by fungi, protozoa, and other algae; the culture medium evaporates significantly; CO2 supply and mass exchange are uneven and locally insufficient; and light is only absorbed by the surface culture. Furthermore, they often involve single-stage cultivation and harvesting, resulting in low algal cell density and low efficiency per unit area. Closed-type photobioreactors, which enable semi-continuous or continuous cultivation with high light energy utilization, can isolate the algae from the external environment, preventing contamination from air contact with the Haematococcus pluvialis culture medium. A central control system provides fixed light intensity, temperature, pH, nutrients, etc., for algal cell growth, allowing for control of environmental parameters to meet cultivation needs. Currently, various photobioreactors are available on the market, such as flat-plate, tubular, columnar, thin-film, and hemispherical photobioreactors. Considering the comprehensive utilization of light and space resources, the application of vertical multi-layer pipeline photobioreactors is the preferred choice.

[0004] To save materials and for simplicity in design and manufacturing, as well as overall aesthetics, many systems employ a vertical layout with identical pipe specifications, where identical tubular photobioreactors are placed on upright supports for cultivation and production. However, this often results in shading between upper and lower layers, leading to insufficient light for the lower tubular photobioreactors and low growth rates. Dust accumulation and high wind loads (>20m / s) are common risks. Increasing the spacing between tubular photobioreactors to mitigate mutual shading leads to increased height, higher structural costs, and poorer stability, increasing the requirements for support materials and structures. Furthermore, wind resistance and disaster prevention often present bottlenecks, especially for upper and lower tubular photobioreactors connected by pipes. Due to the significant difference in water level potential energy and the abrupt 360° change in water flow direction, leaks and breaks at the pipe joints are highly likely to occur.

[0005] To facilitate rapid construction and project implementation, single-unit foundations are often used. Especially in newly developed outdoor areas, different blocks exhibit varying settlement effects, and uneven settlement of the substrate due to different loads at different times leads to instability of the foundation supports. Since vertical supports exert the greatest direct pressure on the ground, resulting in significant settlement, tubular photobioreactors mounted on vertical supports are susceptible to swaying, deviation from the center of gravity, and even collapse under wind and rain. The settlement of the vertical supports on the ground causes varying stability and settling properties at different foundation locations, affecting the horizontal displacement of the tubular photobioreactors. This can lead to spatial misalignment of adjacent multi-layered photobioreactor pipes, disrupting the connectivity of the culture medium, causing localized cavities, impacting photosynthetic efficiency, and promoting the deposition of dead cells.

[0006] Long-term outdoor cultivation will result in significant dust accumulation. When flushing with water, wastewater from the upper tubular photobioreactor drips directly onto the lower tubular photobioreactor, affecting the flushing effect and consequently impacting the light transmittance of the tubular photobioreactor. Ensuring the safety, ease of management, and efficient utilization of light resources in large-scale Haematococcus pluvialis cultivation significantly hinders the sustainable and efficient development of outdoor photobioreactor cultivation models. Summary of the Invention

[0007] In view of the above-mentioned existing technical requirements, the present invention provides an outdoor photobioreactor for large-scale cultivation of Haematococcus pluvialis and a method thereof. This is achieved through the following technical solution: An outdoor photobioreactor device for large-scale cultivation of Haematococcus pluvialis includes an A-frame support, a tubular photobioreactor, an algal solution storage tank, a liquid addition pipe, a peristaltic pump, a base connecting section, a base, a U-shaped connecting pipe, and a collection pipe. Several bases are provided, and adjacent bases are interconnected via the base connecting section to form an integral structure. The A-frame support is mounted on the base. The multiple tubular photobioreactors are arranged horizontally in parallel and fixed to two sides of the A-frame support. The ends of the tubular photobioreactors at the same horizontal level are interconnected via the U-shaped connecting pipe to form a continuous culture medium flow path. The near-ground end of the culture medium flow path is connected to the algal solution storage tank and the peristaltic pump, which drives the culture medium to circulate in the flow path. The algal solution storage tank is also connected to a liquid addition pipe and a collection pipe.

[0008] Preferably, the base is a rectangular concrete block, and the connecting section of the base is reinforced concrete.

[0009] Preferably, the herringbone support has a fitting opening, and the tubular photobioreactor is installed on the fitting opening.

[0010] Preferably, the peristaltic pump is connected to the pipeline photobioreactor via a connecting pipe with a switch.

[0011] Preferably, the angle between the A-frame support and the ground is 45°-75°.

[0012] The present invention also provides a method for large-scale cultivation of Haematococcus pluvialis using the above-mentioned device, comprising the following steps: (1) Inject a culture medium containing Haematococcus pluvialis into the culture medium flow path; (2) Start the peristaltic pump to circulate the culture medium in the flow path; (3) Control the culture conditions to promote the growth of Haematococcus pluvialis; (4) Harvest when Haematococcus pluvialis grows to the target concentration.

[0013] Preferably, the tubular photobioreactor is sterilized before the culture medium is injected.

[0014] Preferably, after harvesting, nutrient solution is added to the culture medium flow path for continuous culture.

[0015] Preferably, the flow state of the culture medium in the flow path is controlled by adjusting the flow rate of the peristaltic pump.

[0016] Preferably, the tubular photobioreactor is arranged in an east-west direction.

[0017] The beneficial effects of this invention are as follows: 1. Stable structure and strong resistance to settlement: The interconnected inclined base has excellent resistance to settlement, ensuring that the device is not easily broken or displaced in newly built sites, under inconsistent loads and full load conditions.

[0018] 2. The U-shaped inlet joint with no water level difference reduces the impact of water flow and minimizes overall structural failure caused by localized stress, making it suitable for large-scale cultivation systems. With adjustable diameter and spacing, photobioreactors located at high altitudes have ample light resources but must also withstand significant wind loads (>20 m / s).

[0019] 3. The stable triangle formed by the A-shaped structure constitutes a mutually supportive and stable culture circulation system, which effectively forms a wind-resistant structure, reduces structural swaying, and increases the service life of the Haematococcus pluvialis culture area by 70%-80%.

[0020] 4. Economical and practical with wide applicability: The inclined base of the connection resists settlement and has a service life of 5-8 years, which is much longer than the traditional single vertical column culture method (which needs to be replaced and adjusted every 1-2 years). At the same time, it avoids the use of U-shaped pipe joints with water level differences to form a continuous sealed pipeline, which improves the success rate of cyclic continuous culture. Attached Figure Description

[0021] Figure 1 This is a side view of the outdoor photobioreactor used in the embodiment for large-scale cultivation of Haematococcus pluvialis. Schematic diagram; Figure 2 This is a top view schematic diagram of an outdoor photobioreactor for large-scale cultivation of Haematococcus pluvialis; Figure 3 This is a schematic diagram of the bottom of an outdoor photobioreactor for large-scale cultivation of Haematococcus pluvialis.

[0022] Component names: 1. A-frame support, 2. Fitting port, 3. Pipeline photobioreactor, 4. Connector with switch, 5. Algal solution storage tank, 6. Liquid addition pipe, 7. Peristaltic pump, 8. Base connecting section, 9. Base, 10. U-shaped connector, 11. Collection pipe. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments: In this invention, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] This invention provides an outdoor photobioreactor for large-scale cultivation of Haematococcus pluvialis, comprising: a base 9 that is interconnected and mutually restrained, forming a stable foundation to prevent local settlement; A stable A-frame support 1 is installed on the base 9. The two sides of the A-frame support 1 are inclined at an angle to the ground. The structure above ground is connected to the structure below ground. The A-frame support 1 supports the pipeline photobioreactor 3. On the two inclined sides of the herringbone support 1, the parallel tubular photobioreactors 3 of the same size, which are used to cultivate Haematococcus pluvialis, are placed on the interlocking openings 2. The tubular photobioreactors 3 are connected to each other at the same horizontal position through U-shaped connecting pipes 10, so that the traditional vertical series arrangement is adjusted to a horizontal parallel layout, and the above-ground part and the ground part are organically connected.

[0025] At the near-ground end is a peristaltic pump 7. The culture medium in the row of interconnected tubular photobioreactors 3 is pumped upward by the power of the peristaltic pump 7 to the highest point, and then flows back to the peristaltic pump by gravity, forming an upper and lower culture medium circulation.

[0026] The base 9 is a cuboid, interconnected with adjacent longitudinal bases 9 via reinforced concrete base connecting sections 8, forming an interconnected and mutually restraining base. The vertical pressure applied to the support is dispersed horizontally through this restraining base. This includes the pressure difference on the base 9 caused by the different bearing pressures of the partially vacant and near-full-load states of the tubular photobioreactor 3, which could lead to different settlement patterns. This reduces the impact of varying bearing pressures on the stability and settlement of the base 9 at different locations, thus minimizing the different settlement phenomena caused by these pressure differences. The adjacent, stable bases 9 ensure a stable spatial distribution for photobioreactor pipelines of different capacities, guaranteeing normal communication of the culture medium, preventing the formation of local cavities, oxidative damage caused by high dissolved oxygen, and the deposition of dead cells, thereby improving the efficiency of photosynthesis.

[0027] In this design, a herringbone structure is installed on the base 9 as a support, replacing the single upright support with two inclined supports that lean against each other at an angle to the ground. The structures above and below are organically connected, with the tubular photobioreactor 3 placed on the two inclined interlocking openings 2, supporting it. This prevents the upper and lower layers from blocking each other's light, ensuring sufficient illumination for the lower photobioreactor and guaranteeing light intensity between the upper and lower layers. The tubular photobioreactor 3, positioned on the inclined interlocking openings 2, reduces the elevation difference between the upper and lower layers, minimizing changes in water pressure and flow rate of the peristaltic pump 7. Simultaneously, the herringbone support 1 and the tubular photobioreactor 3 distribute pressure on the ground, resulting in stable performance, long service life, reduced risk, and simplified management.

[0028] The herringbone bracket 1 is a base 9 with a sloping side on both sides, which are connected and mutually restrain each other. The V-shaped structure of the double brackets forms a stable foundation.

[0029] The tubular photobioreactors 3 are connected by U-shaped connectors 10 to form a continuous, sealed pipeline. The U-shaped connectors 10 change the layout from vertical to horizontal, with the two ends connected in parallel to form a parallel pipeline group, which facilitates smooth and safe operation. The tubular photobioreactors 3 are placed on both sides. At the end near the ground are a peristaltic pump 7 and an algal solution storage tank 5. The algal solution storage tank 5 is connected to a liquid addition pipe 6 with a switch, a collection pipe 11 with a switch, the peristaltic pump 7, and the tubular photobioreactor 3 at the bottom. The peristaltic pump 7 uses power to pump the culture medium upwards to the highest point, then returns to the peristaltic pump 7, forming a circulation. The peristaltic pump 7 has the characteristics of strong self-priming ability, no risk of cross-contamination, and low shear force. Traditional circulation pumps rely on impeller rotation to generate centrifugal force to transport fluid, with the fluid directly contacting the pump chamber and moving parts, resulting in greater shear force and a shorter algal lifespan. A three-way connector can also be configured, normally closed, but used as an inlet for injecting fresh culture medium and collecting culture medium when necessary. The peristaltic pump 7 is connected to the tubular photobioreactors 3 via a connector 4 with a switch. Maintaining the circulation of algal solution in the pipeline photobioreactor is important and necessary. It helps keep microalgal cells in suspension, improves light energy utilization efficiency and reduces photoinhibition, and also increases the CO2 gas exchange rate and accelerates the dissolution rate. It also helps separate the O2 produced by microalgae from the algal solution, reducing the inhibition of dissolved oxygen on microalgal photosynthesis. At the same time, it also helps to ensure the uniform distribution of nutrients and solution and eliminate photothermal stratification of the algal solution.

[0030] The herringbone support 1 has a large and fixed bottom spacing and a small and interconnected top spacing, which changes the single column to a double column and forms a double column with oblique force, thus having better stability and resisting the chance of settlement.

[0031] The tubular photobioreactor 3 is oriented east-west to avoid mutual shading caused by a north-south orientation.

[0032] The deposition on the base 9 is detected by a level instrument. If the deposition is in the millimeter range, no adjustment is needed. If the horizontal change is 1 cm or more, a pad is required. This pad is placed below the inclined interlocking opening 2 of the inverted tubular photobioreactor to help the A-frame support 1, which has a large settlement, to have the same horizontal height.

[0033] The system includes a long, narrow base 9, with half of each of two herringbone pillars 1 arranged to form a V-shaped support, thus improving space utilization efficiency.

[0034] The present invention also provides a method for cultivating Haematococcus pluvialis outdoors using the above-mentioned herringbone-shaped photobioreactor, comprising the following steps: 1) Set up interconnected and mutually restraining bases 9, and use a level to correct and adjust them after natural settlement; 2) A herringbone structure is set on the base 9 to form a stable support to support the tubular photobioreactor 3; the three-dimensional multi-layer tubular photobioreactor 3 is placed on both sides, and the two ends of the tubular photobioreactor 3 are connected by return pipes. At the end near the ground is a peristaltic pump 7, which pumps the culture medium upward by power to the highest point, and then flows back to the peristaltic pump 7 to form a cycle.

[0035] 3) Before use, the assembled tubular photobioreactor 3 needs to be sterilized using chemical methods. After cleaning, it should be soaked in bleach for further sterilization and then rinsed clean. Then, algal solution is added through the inlet pipe 6 with a switch, gradually filling the tubular photobioreactor 3 from bottom to top. The peristaltic pump 7 is then turned on, and the oxygen-to-carbon dioxide ratio is adjusted to achieve uniform gas-liquid mixing. After completion, the frequency converter is adjusted to control the flow rate of the algal solution. These conditions are maintained to allow microalgae to grow in the tubular photobioreactor 3. When the microalgae reach a high concentration or a harvest concentration, the flow rate and volume of the peristaltic pump 7 are increased, and the algae are collected from the collection pipe 11 with a switch. After drying, algal powder is obtained. Nutrient solution is promptly added to the algal solution in the tubular photobioreactor 3 to continue growth. This allows for continuous cultivation in the photobioreactor. Example

[0036] The outdoor A-frame photobioreactor for large-scale cultivation of Haematococcus pluvialis is mainly composed of interconnected and mutually restraining base 9, A-frame support 1, and parallel U-shaped pipe 10 connected to a pipeline photobioreactor 3.

[0037] 1) The interconnected and mutually restraining connecting bases 9 require 15-30 days of natural settlement, and will be corrected and adjusted using a level. They are constructed of cast concrete, with a rectangular shape of 60*40*40 cm. The north-south longitudinal spacing between the two bases 9 is 140 cm, and they are interconnected with the longitudinally adjacent bases 9 via a reinforced concrete connecting section 8. The east-west spacing is 50 m. 2) A herringbone support 1 is welded and installed on the connected base 9 as a carrier. The angle between the two inclined angle steels and the ground is 45°. The structures on the ground are organically connected to each other. The pipeline photobioreactor 3 is placed on the inclined interlocking openings 2 on both sides.

[0038] 3) The tubes of the 6cm diameter tubular photobioreactor 3 are connected by U-shaped connecting pipes 10. The U-shaped connecting pipes 10 are changed from a vertical to a horizontal arrangement. The tubular photobioreactor 3 is spaced 4cm apart, each tube is 100m long, and the total length is 4000m. This ensures that the total length and volume of the tubes increase equally while maintaining a constant specific surface area. See the top view. Figure 2 The U-shaped connectors at both ends are connected in parallel for a parallel layout. Considering the light transmittance of the glass tubes, and given that the local area receives more than 8 hours of sunshine per year for 280 days, with light intensity of 1000-4000 μmol / m², −2 s −1 Considering all factors, a 6 cm diameter, 2 mm wall thickness glass tube was selected as the tubular photobioreactor 3. The total volume of a single tubular photobioreactor 3 is 1100 L. The tubular photobioreactor 3 has a snap-fit ​​port 2 located on both sides of the A-frame support 1. At the near-ground end is a peristaltic pump 7 (model HL100-15), which pumps the culture medium upwards to the highest point of the tubular photobioreactor 3, then back to the peristaltic pump 7, forming a circulation. An additional T-junction is configured to connect to the collection and liquid addition pipes; this is normally closed but serves as an inlet for injecting fresh culture medium and collecting culture medium when necessary.

[0039] Before use, the assembled tubular photobioreactor 3 needs to be sterilized using chemical methods. After cleaning, it is soaked in 1% bleach for further sterilization, and then rinsed twice with sterilized fresh water. Then, algal solution is added through the switchable inlet pipe 6, gradually filling the tubular photobioreactor 3 from bottom to top. The peristaltic pump 7 is then turned on, and the oxygen-to-carbon dioxide ratio is adjusted to achieve uniform gas-liquid mixing. After completion, the frequency converter in the peristaltic pump 7 controls the flow rate of the algal solution, which enters the tubular photobioreactor 3 through the switchable connector 4. Microalgae grow in the tubular photobioreactor 3. When the microalgae reach a high concentration or harvest concentration, they are harvested by increasing the flow rate and velocity of the peristaltic pump 7 through the algal solution storage tank 5 and exiting through the switchable collection pipe 11. After drying, algal powder is obtained. Nutrient solution is replenished to the tubular photobioreactor 3 through the switchable inlet pipe 6 to continue growth. This allows for continuous cultivation in the photobioreactor. Example

[0040] 1) The interconnected and mutually restraining bases 9 are constructed of cast concrete, with a rectangular shape of 60*40*40 cm. The north-south spacing is 155 cm, and the east-west spacing is 25 m. 2) A herringbone structure is welded on the base 9 as a support, and the angle between the two inclined angle steels and the ground is 60°. The pipeline photobioreactor 3 is placed on the inclined interlocking openings 2 on both sides.

[0041] 3) The 6cm diameter glass tube photobioreactor 3 consists of 20 tubes connected in series, with a spacing of 4cm between tubes, and connected by U-shaped connectors 10. Each row has 1600 tubes, with a spacing of 2.5 meters between each row and a length of 100 meters. Each row can hold 10 tons of culture medium, with a total of 2000 rows, forming the entire culture system. Based on a 21-day production cycle, it can produce 200 tons of Haematococcus pluvialis dry powder containing astaxanthin annually. Example

[0042] 1) The interconnected and mutually restraining bases 9 are constructed of cast concrete, with rectangular dimensions of 60*40*40 cm. The north-south spacing is 170 cm, and the east-west spacing is 50 cm. 2) A herringbone structure is welded on the base 9 as a support, and the angle between the two inclined angle steels and the ground is 75°. The pipeline photobioreactor 3 is placed on the inclined interlocking openings 2 on both sides.

[0043] 3) The 6cm diameter glass tube photobioreactor 3 consists of 20 tubes connected in series, with a spacing of 4cm between tubes, and connected by U-shaped connectors 10. Each row has 1600 tubes, with a spacing of 2.5 meters between each row and a length of 100 meters. Each row can hold 10 tons of culture medium, and a total of 1000 rows constitute the entire culture system. Based on a 21-day production cycle, it can produce 100 tons of Haematococcus pluvialis dry powder containing astaxanthin annually.

[0044] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A device for large-scale cultivation of Haematococcus pluvialis using an outdoor photobioreactor, characterized in that, The system includes a herringbone support (1), a tubular photobioreactor (3), an algal solution storage tank (5), a liquid addition pipe (6), a peristaltic pump (7), a base connecting section (8), a base (9), a U-shaped connecting pipe (10), and a collection pipe (11). Several bases (9) are provided, and adjacent bases (9) are connected to each other through the base connecting section (8) to form an integral structure. The herringbone support (1) is provided on the base (9). The multiple tubular photobioreactors (3) are arranged in a horizontal parallel manner and fixed on the two sides of the herringbone support (1). The ends of the tubular photobioreactors (3) at the same horizontal height are connected to each other through the U-shaped connecting pipe (10) to form a continuous culture medium flow path. The near-ground end of the culture medium flow path is connected to the algal solution storage tank (5) and the peristaltic pump (7). The peristaltic pump (7) drives the culture medium to circulate in the flow path. The algal solution storage tank (5) is also connected to the liquid addition pipe (6) and the collection pipe (11).

2. The apparatus for large-scale cultivation of Haematococcus pluvialis in an outdoor photobioreactor according to claim 1, characterized in that: The base (9) is a rectangular concrete structure, and the connecting section (8) of the base is reinforced concrete.

3. The apparatus for large-scale cultivation of Haematococcus pluvialis in an outdoor photobioreactor according to claim 1, characterized in that: The herringbone support (1) has a fitting port (2), and the tubular photobioreactor (3) is installed on the fitting port (2).

4. The apparatus for large-scale cultivation of Haematococcus pluvialis in an outdoor photobioreactor according to claim 1, characterized in that: The peristaltic pump (7) is connected to the pipeline photobioreactor (3) via a connecting pipe (4) with a switch.

5. The apparatus for large-scale cultivation of Haematococcus pluvialis in an outdoor photobioreactor according to claim 1, characterized in that: The angle between the A-frame bracket (1) and the ground is 45°-75°.

6. A method for large-scale cultivation of Haematococcus pluvialis using the apparatus described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Inject a culture medium containing Haematococcus pluvialis into the culture medium flow path; (2) Start the peristaltic pump (7) to circulate the culture medium in the flow path; (3) Control the culture conditions to promote the growth of Haematococcus pluvialis; (4) Harvest when Haematococcus pluvialis grows to the target concentration.

7. The method for large-scale cultivation of Haematococcus pluvialis according to claim 6, characterized in that, Before injecting the culture medium, the tubular photobioreactor (3) is disinfected.

8. The method for large-scale cultivation of Haematococcus pluvialis according to claim 6, characterized in that, After harvesting, nutrient solution is added to the culture medium flow path for continuous culture.

9. The method for large-scale cultivation of Haematococcus pluvialis according to claim 6, characterized in that, The flow state of the culture medium in the flow path is controlled by adjusting the flow rate of the peristaltic pump (7).

10. The method for large-scale cultivation of Haematococcus pluvialis according to claim 6, characterized in that, The pipeline photobioreactor (3) is arranged in an east-west direction.

Images