A floating type microalgae culture photobioreactor system and application thereof

Abstract

The present application relates to the technical fields of microalgae culture, in particular to a floating type microalgae culture photobioreactor system and its application, comprising a grid frame fixedly arranged underwater, wherein a plurality of culture containers are arranged in the grid units of the grid frame; displacement sensors and temperature sensors are arranged on the culture containers; a lifting mechanism is arranged at the grid units of the grid frame, wherein the lifting mechanism comprises a servo cylinder and a pressing rod connected with the plurality of culture containers through elastic supporting members; the central controller receives sensor data and controls the servo cylinder to dynamically adjust the immersion depth of the plurality of culture containers according to a preset time-depth curve. By arranging the lifting mechanism driven by the servo cylinder in the grid frame, the elastic supporting members and the culture containers are linked, and the central controller actively adjusts the height of the containers according to the preset time-depth curve, so that the temperature of the algal liquid is stably maintained at room temperature, and the problem of high temperature death caused by strong light in summer is solved.

Description

Technical Field

[0001] This invention relates to the field of microalgae cultivation technology, specifically to a floating microalgae cultivation photobioreactor system and its application. Background Technology

[0002] Existing microalgae cultivation methods include both marine and freshwater aquaculture. Microalgae cultivation, especially in summer when temperatures are high, utilizes photobioreactors for floating cultivation of *Phaeodactylum tricornutum*, primarily for cooling purposes, allowing the algae to float on the sea surface for fixed cultivation. Patent application CN201710859033.5 discloses a recirculating marine aquaculture system based on a microalgae membrane bioreactor. This system includes a cultivation pond connected to a photobioreactor, which is connected to a microalgae concentration tank via a water pump. The concentration tank contains an ultrafiltration membrane module, the outlet of which is connected to the cultivation pond via the pump. A wastewater outlet and drainage pipe are located at the center of the cultivation pond. This invention effectively removes pollutants such as free ammonia and phosphate from aquaculture wastewater through the absorption of microalgae cultivated in the photobioreactor. The concentrations of free ammonia and reactive phosphate in the effluent from the ultrafiltration membrane module are below detection limits. This wastewater is then recycled back to the cultivation pond, effectively achieving water recycling. After harvesting, the microalgae are processed into feed and fed back to the cultivation pond, realizing the recycling of nutrients during the aquaculture process.

[0003] Brown finger algae require a normal temperature of 15-25℃ to grow. While traditional fixed photobioreactors can recycle aquaculture wastewater, they have two major drawbacks: the reactors are exposed to direct sunlight, and the liquid temperature can easily exceed 30℃ in summer, leading to algal death; existing floating systems rely solely on passive buoyancy and cannot precisely adjust the immersion depth to utilize seawater for cooling. Since marine algae such as brown finger algae are particularly sensitive to temperature, there is an urgent need for a photobioreactor system that can be fixed on the sea surface for cultivation and achieve intelligent temperature control. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a floating microalgae cultivation photobioreactor system and its application, realizing programmed depth control of the floating reactor at sea, breaking through the traditional passive cooling mode. Tests have shown that when the cultivation container is 70% submerged in water at noon in summer, the algal solution temperature is stable at 20±0.5℃, thus solving the problems mentioned in the background art.

[0005] To achieve the above objectives, on the one hand, the present invention provides a floating microalgae cultivation photobioreactor system, including a grid frame fixed underwater, with several liftable cultivation containers within its grid units; displacement sensors and temperature sensors are installed on the cultivation containers, the displacement sensors being used to monitor the immersion depth of the cultivation containers in real time, and the temperature sensors being used to monitor the liquid temperature inside the cultivation containers in real time; a lifting mechanism is provided at the grid units of the grid frame, the lifting mechanism including a servo electric cylinder and a pressure rod connected to the several cultivation containers via elastic support members; a central controller receives sensor data and controls the servo electric cylinder to dynamically adjust the immersion depth of the several cultivation containers according to preset different time periods of the day; a counterweight box is provided at the bottom of the cultivation containers, the cultivation containers are made of transparent plastic and their lower half sidewalls are provided with an aluminum foil reflective layer; a gas supply pipe is provided at the grid units of the grid frame, connected to the sidewalls of the several cultivation containers, for inputting carbon dioxide gas.

[0006] As a further improvement to this technical solution, the central controller has a built-in time control module that presets the target immersion depth according to the light intensity at different times. The culture container is equipped with a dissolved oxygen sensor, and the data is fed back to the central controller to adjust the ventilation rate.

[0007] As a further improvement to this technical solution, the culture container is composed of an upper cover and a lower cover connected by threads. The top center of the upper cover is provided with an exhaust port, and a one-way valve is tightly fitted inside the exhaust port. The top outer side of the upper cover is provided with a monitoring window for installing sensors.

[0008] As a further improvement to this technical solution, the bottom side wall of the upper cover is connected to a ventilation pipe, and the side wall of the air supply pipe is connected to several air distribution pipes at equal intervals. The several air distribution pipes are connected to the several ventilation pipes in a corresponding manner. One end of the air supply pipe is closed, and the other end is connected to the aerator through a pipe. Its air inlet is connected to a carbon dioxide mixed gas source.

[0009] As a further improvement to this technical solution, the elastic support includes a hanger, an upper sleeve that is snapped into the vertical side wall of the hanger, and a lower sleeve that is connected to the upper sleeve by a spring. Movable columns are fixedly provided at equal intervals on the bottom surface of the pressure rod. The horizontal section of the hanger is sleeved with the movable columns. A support ring is fixedly connected to the bottom end of the lower sleeve. The lower cover is tightly sleeved with the support ring.

[0010] As a further improvement to this technical solution, a dissolved oxygen sensor is installed inside the culture container, and the data is fed back to the central controller to adjust the ventilation rate. The immersion depth of the culture container is such that the liquid temperature is maintained at 15-25℃.

[0011] As a further improvement to this technical solution, the bottom of the lower cover is provided with a ring platform, the top of the counterweight box is provided with a threaded ring that is threadedly connected to the ring platform, and the top outer wall of the counterweight box is provided with several water inlet holes.

[0012] As a further improvement to this technical solution, the grid frame is fixedly provided with several crossbeams at equal intervals inside, dividing its interior into several grid units. Several insertion holes are opened at equal intervals on the top surface of the crossbeams, and the movable column is inserted into the corresponding insertion holes.

[0013] As a further improvement to this technical solution, a bracket is fixedly provided in the middle of the top surface of the crossbeam, the servo electric cylinder is fixedly connected to the top surface of the bracket by bolts, a sleeve is provided in the middle of the air supply pipe, a slider is provided on the top of the sleeve, the slider is slidably engaged with a pair of clamping strips, and the pair of clamping strips are fixedly connected to the side wall of the bracket.

[0014] On the other hand, the present invention provides an application of a floating microalgae cultivation photobioreactor system, which is the application of the above-mentioned floating microalgae cultivation photobioreactor system in the cultivation of *Phaeodactylum tricornutum*.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. The floating microalgae cultivation photobioreactor system and its application achieve dynamic temperature control through a grid frame and a lifting mechanism. A servo-driven electric cylinder-driven lifting mechanism is set in the grid frame, which links the elastic support and the cultivation container. Combined with the central controller, the container height is actively adjusted according to the preset time-depth curve, so that the temperature of the algae solution is stably maintained at 15-25℃, solving the problem of high temperature death caused by strong sunlight in summer.

[0017] 2. The floating microalgae cultivation photobioreactor system and its application, through modular grid frame to achieve large-scale cultivation, the detachable and assembleable grid frame and standardized culture containers, the bracket to fix the servo electric cylinder, the bracket to guide the gas supply pipe to rise and fall accordingly, support the cluster control of hundreds of containers, and the failure of the culture container in the grid unit does not affect the overall operation.

[0018] 3. The floating microalgae cultivation photobioreactor system and its application achieve stable marine aquaculture by using elastic support components that work in conjunction with waves to provide buffering protection. The upper and lower sleeves connected by springs form elastic support components, and the springs absorb the impact of waves, preventing rigid damage at the connection between the cultivation container and the grid frame, thus reducing the mechanical failure rate. Attached Figure Description

[0019] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely illustrative to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. Those skilled in the art, guided by the teachings of this invention, will select various possible shapes and proportions to implement the invention according to specific circumstances.

[0020] Figure 1 This is a schematic diagram of the overall assembly structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the grid frame structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the assembly structure of several culture containers and lifting mechanisms of the present invention;

[0023] Figure 4 This is a schematic diagram of the assembly structure of the culture container of the present invention;

[0024] Figure 5 This is an exploded view of the culture container of the present invention;

[0025] Figure 6 This is an exploded view of the elastic support member of the present invention;

[0026] Figure 7 This is a schematic diagram of the gas pipeline assembly structure of the present invention;

[0027] Figure 8 This is a preset time-depth curve diagram of the present invention;

[0028] Figure 9 This is a schematic diagram illustrating the principle of dynamic adjustment of immersion depth of the culture container according to the present invention.

[0029] The meanings of the labels in the diagram are as follows:

[0030] 100. Grid frame; 110. Crossbeam; 111. Insertion hole; 120. Bracket;

[0031] 200. Culture container; 210. Upper cover; 211. Vent pipe; 212. Exhaust nozzle; 213. One-way valve; 214. Monitoring window; 220. Lower cover; 221. Ring platform; 230. Gas supply pipe; 231. Gas distribution pipe; 232. Support sleeve; 233. Slider; 234. Clamping bar; 240. Support ring; 250. Elastic support component; 251. Hanger; 2511. Slot; 252. Upper sleeve; 253. Lower sleeve; 260. Counterweight box; 261. Threaded ring; 262. Water inlet;

[0032] 300. Lifting mechanism; 310. Servo electric cylinder; 320. Pressure rod; 330. Movable column. Detailed Implementation

[0033] The details of the present invention can be more clearly understood by referring to the accompanying drawings and the description of specific embodiments. However, the specific embodiments of the present invention described herein are for illustrative purposes only and should not be construed as limiting the invention in any way. Under the teachings of this invention, those skilled in the art will conceive of any possible variations of the invention, all of which should be considered within the scope of the invention. The terms "installation" and "connection" should be interpreted broadly, referring to direct connection as well as indirect connection through an intermediate medium.

[0034] The terms "central axis," "vertical," "horizontal," "front," "rear," "upper," "lower," "left," "right," "top," "bottom," "inner," and "outer" used herein to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of the invention, "a number" means two or more, unless otherwise explicitly specified.

[0035] Please see Figures 1-9 As shown, this invention provides a floating microalgae cultivation photobioreactor system for the cultivation of *Phaeodactylum tricornutum*. The system includes a fixed underwater grid frame 100, with several liftable cultivation containers 200 housed within its grid units. The grid frame 100 is fixedly connected to a base on the shore or in the water. Several horizontal beams 110 are fixedly installed at equal intervals inside the grid frame 100, dividing its interior into several grid units for placing the cultivation containers 200. Displacement sensors and temperature sensors are installed on the cultivation containers 200. The displacement sensors monitor the immersion depth of the cultivation containers 200 in real time, and the temperature sensors monitor the liquid temperature inside the cultivation containers 200 in real time. Gas supply pipes 230 are installed at the grid units of the grid frame 100 and connected to the side walls of the cultivation containers 200 to input carbon dioxide gas to aid algal growth.

[0036] Specifically, the culture container 200 is composed of an upper cover 210 and a lower cover 220 connected by threads. The top center of the upper cover 210 is provided with an exhaust port 212, and a one-way valve 213 is tightly fitted inside the exhaust port 212 to allow gas inside the culture container 200 to leak out and avoid excessive pressure. The top outer side of the upper cover 210 is provided with a monitoring window 214 for installing sensors.

[0037] Furthermore, the bottom side wall of the upper cover 210 is connected to a ventilation pipe 211, and the side wall of the gas supply pipe 230 is connected to a number of gas distribution pipes 231 at equal intervals. The number of gas distribution pipes 231 and the number of ventilation pipes 211 are connected in a corresponding manner. One end of the gas supply pipe 230 is closed, and the other end is connected to the aerator through a pipe. Its air inlet is connected to a carbon dioxide mixed gas source so that carbon dioxide gas is introduced into the culture container 200 when the gas is pumped.

[0038] Furthermore, to mitigate the impact of the culture container 200's fluctuations with water waves on the overall stability of the grid frame 100, an elastic support 250 is provided on one side of the culture container 200. The elastic support 250 includes a hanger 251, an upper sleeve 252 that engages with the vertical side wall of the hanger 251, and a lower sleeve 253 that is connected to the upper sleeve 252 via a spring. Movable columns 330 are fixedly installed at equal intervals on the bottom surface of the pressure rod 320. Rings are welded to the upper and lower ends of the spring. Pins are inserted through the top side wall of the upper sleeve 252 and the bottom side wall of the lower sleeve 253, respectively, passing through the upper and lower rings to form a whole. A sealing ring is fitted onto the top outer wall of the lower sleeve 253. A slot 2511 is provided on the vertical side wall of the hanger 251 to engage with the upper sleeve 252. The horizontal section of the hanger 251 is fitted with the movable column 330. The top surface of the crossbeam 110 has several equally spaced insertion holes 111. The movable column 330 is inserted into the corresponding insertion holes 111 to guide the servo cylinder 310 so that the force distribution is even and the operation is stable. The bottom end of the lower sleeve 253 is fixedly connected to the support ring 240. The lower cover 220 is tightly fitted with the support ring 240, which makes the culture container 200 easy to assemble and disassemble.

[0039] Furthermore, a counterweight box 260 is provided at the bottom of the culture container 200. The culture container 200 is made of transparent plastic and its lower half side wall is provided with an aluminum foil reflective layer to reflect light and prevent the temperature from rising too quickly. A ring platform 221 is provided on the bottom of the lower cover 220. A threaded ring 261 is provided on the top of the counterweight box 260 and is threaded to the ring platform 221. Several water inlet holes 262 are provided on the top outer wall of the counterweight box 260. Water is introduced into the counterweight box 260 to increase its weight, thereby offsetting part of the buoyancy of the culture container 200 so that it can be submerged in water.

[0040] Specifically, such as Figure 3 As shown, a lifting mechanism 300 is provided at the grid unit of the grid frame 100. The lifting mechanism 300 includes a servo electric cylinder 310 and a pressure rod 320 connected to several elastic support members 250. The central controller receives sensor data and controls the servo electric cylinder 310 to dynamically adjust the immersion depth of several culture containers 200 according to different time periods of the day, so as to realize temperature adaptive control. The central controller has a built-in time control module, which presets the corresponding target immersion depth according to the light intensity of different time periods. The culture container 200 is equipped with a dissolved oxygen sensor, and the data is fed back to the central controller to adjust the aeration rate.

[0041] Furthermore, a dissolved oxygen sensor is installed inside the culture container 200, and the data is fed back to the central controller to adjust the ventilation rate. The immersion depth of the culture container 200 is sufficient to maintain the liquid temperature at 15-25℃.

[0042] Furthermore, a bracket 120 is fixedly provided in the middle of the top surface of the crossbeam 110, and the servo electric cylinder 310 is fixedly connected to the top surface of the bracket 120 by bolts. A sleeve 232 is sleeved in the middle of the gas supply pipe 230, and a slider 233 is provided on the top of the sleeve 232. A pair of clamping strips 234 are slidably engaged with the slider 233. The pair of clamping strips 234 are fixedly connected to the side wall of the bracket 120, so that the gas supply pipe 230 can rise and fall with the culture container 200.

[0043] like Figure 8 As shown in the preset time-depth curve, the time axis is segmented into control paths:

[0044] 0:00-6:00: 100% submerged, completely submerged in water at night for insulation;

[0045] 6:00-10:00: 100%→30%, gradually rising as sunlight intensifies, absorbing sunlight to increase temperature;

[0046] 10:00-12:00: 30%→70%, actively sinking to avoid high temperatures during the midday heat period;

[0047] 12:00-16:00: 70%, continuously submerged underwater to avoid high temperatures;

[0048] 16:00-18:00: 70%→40%, slowly rising, absorbing sunlight and storing heat;

[0049] 18:00-24:00: 40%→100%, completely submerged in water for insulation after sunset.

[0050] This embodiment also provides an application of a floating microalgae culture photobioreactor system, which is the application of the above-mentioned floating microalgae culture photobioreactor system in the culture of *Phaeodactylum tricornutum*.

[0051] In the floating microalgae cultivation photobioreactor system of the present invention, the cultivation container 200 after being injected with microalgae liquid is placed in the grid unit of the grid frame 100, and the aerator is started to supply carbon dioxide gas; the central controller controls the servo cylinder 310 to adjust the immersion depth of the cultivation container 200 in the water according to the preset time-depth curve, so that the cultivation container 200 maintains 20°C to cultivate microalgae floating on the sea surface, thereby realizing fixed cultivation on the sea surface.

[0052] It should be noted that the fixed connections and fixing methods of the present invention are achieved using conventional fixing means such as bolt connections or welding. The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A photobioreactor system for floating microalgae cultivation, characterized in that, The system includes a fixed underwater grid frame, with several liftable culture containers housed within its grid units. Displacement and temperature sensors are installed on each culture container; the displacement sensors monitor the immersion depth in real time, and the temperature sensors monitor the liquid temperature inside the container. A lifting mechanism is located at each grid unit of the grid frame, comprising a servo cylinder and a pressure rod connected to the culture containers via elastic supports. A central controller receives sensor data and controls the servo cylinder to dynamically adjust the immersion depth of the culture containers according to preset times of day. Each culture container has a counterweight at its bottom and is made of transparent plastic with a reflective aluminum foil layer on its lower sidewall. Gas supply pipes are located at each grid unit of the grid frame, connected to the sidewalls of the culture containers, for introducing carbon dioxide gas. The central controller has a built-in time control module that presets the target immersion depth according to the light intensity at different times. The culture container is equipped with a dissolved oxygen sensor, and the data is fed back to the central controller to adjust the ventilation rate. As shown in the preset time-depth curve, the time axis is segmented into control paths: 0:00-6:00: 100% submerged, completely submerged in water at night for insulation; 6:00-10:00: 100%→30%, gradually rising as sunlight intensifies, absorbing sunlight to increase temperature; 10:00-12:00: 30%→70%, actively sinking to avoid high temperatures during the midday heat period; 12:00-16:00: 70%, continuously submerged underwater to avoid high temperatures; 16:00-18:00: 70%→40%, slowly rising, absorbing sunlight and storing heat; 18:00-24:00: 40%→100%, completely submerged in water after sunset for insulation; The culture container is equipped with a dissolved oxygen sensor, and the data is fed back to the central controller to adjust the ventilation rate. The immersion depth of the culture container is sufficient to maintain the liquid temperature at 15-25℃.

2. The photobioreactor system for floating microalgae cultivation according to claim 1, characterized in that: The culture container is composed of an upper cover and a lower cover connected by threads. The top center of the upper cover is provided with an exhaust port, and a one-way valve is tightly fitted inside the exhaust port. The top outer side of the upper cover is provided with a monitoring window for installing sensors.

3. The photobioreactor system for floating microalgae cultivation according to claim 2, characterized in that: The bottom side wall of the upper cover is connected to a ventilation pipe, and the side wall of the air supply pipe is connected to several air distribution pipes at equal intervals. The air distribution pipes are connected to the ventilation pipes one by one. One end of the air supply pipe is closed, and the other end is connected to the aerator through a pipe. Its air inlet is connected to a carbon dioxide mixed gas source.

4. The photobioreactor system for floating microalgae cultivation according to claim 3, characterized in that: The elastic support includes a hanger, an upper sleeve that is snapped into the vertical side wall of the hanger, and a lower sleeve that is connected to the upper sleeve by a spring. Movable columns are fixedly provided at equal intervals on the bottom surface of the pressure rod. The horizontal section of the hanger is sleeved with the movable columns. A support ring is fixedly connected to the bottom end of the lower sleeve. The lower cover is tightly sleeved with the support ring.

5. The photobioreactor system for floating microalgae cultivation according to claim 4, characterized in that: The bottom of the lower cover is provided with a ring platform, the top of the counterweight box is provided with a threaded ring that is threadedly connected to the ring platform, and the top outer wall of the counterweight box is provided with several water inlet holes.

6. The photobioreactor system for floating microalgae cultivation according to claim 5, characterized in that: The grid frame is fixedly provided with several crossbeams at equal intervals inside, which divides the inside into several grid units. Several insertion holes are opened at equal intervals on the top surface of the crossbeams, and the movable column is inserted into the corresponding insertion holes.

7. The photobioreactor system for floating microalgae cultivation according to claim 6, characterized in that: A bracket is fixedly provided in the middle of the top surface of the crossbeam. The servo electric cylinder is fixedly connected to the top surface of the bracket by bolts. A sleeve is provided in the middle of the air supply pipe. A pair of clamping strips are slidably engaged at the top of the sleeve. The pair of clamping strips are fixedly connected to the side wall of the bracket.

8. An application of a photobioreactor system for floating microalgae cultivation, characterized in that: This refers to the application of the floating microalgae cultivation photobioreactor system described in claim 7 in the cultivation of *Phaeodactylum tricornutum*.

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