Photobioreactor device for microalgae culture

Abstract

Provided is a photobioreactor device for microalgae culture, characterized in that the device comprises: an outer container for containing a culture solution, the outer container comprising a transparent side wall and a removable upper cover; the inner container is used for containing culture liquid and microalgae and can be contained in the outer container and taken out of the outer container, the inner container comprises a transparent side wall, a top screen and a bottom screen, each of the top screen and the bottom screen comprises a screen mesh, the mesh size of the screen mesh can allow the culture liquid and gas to pass through, and meanwhile the microalgae is prevented from passing through; at least one of the top screen and the bottom screen is removably engageable with the inner container; and the gas circulation unit injects gas rich in carbon dioxide into the outer container.

Description

Technical Field

[0001] The utility model relates to the field of microalgae cultivation and propagation, in particular to a photobioreactor device for microalgae cultivation. Background Art

[0002] Microalgae is a single-celled microorganism, about 2-30um. Microalgae can use carbon dioxide in the gas for efficient photosynthesis, and it has strong adaptability and fast reproduction. Since microalgae consume carbon dioxide and produce oxygen during their growth, they can be used to purify the air. Organic carbon, ammonia nitrogen, organic phosphorus and other substances in wastewater can be used as carbon sources, nitrogen sources and phosphorus sources required for the growth of microalgae. Therefore, microalgae can be used to purify wastewater. In addition to absorbing organic matter in wastewater, microalgae can also absorb heavy metals in wastewater. Microalgae cultivated in a safe and hygienic environment also have high nutritional value and medicinal value. For example, different types of microalgae may contain a variety of unsaturated fatty acids, algae polysaccharides, phycocyanin, astaxanthin, carotene, etc. In addition, some types of microalgae with higher "oil content" can also be used as biofuels.

[0003] Large-scale artificial cultivation of microalgae can promote the application of microalgae in food, feed, health care, light chemical industry, biofuel, environmental engineering and other industries. Currently, there are two main ways to cultivate microalgae: open culture and closed photobioreactor. Open culture is relatively simple and low investment. However, the yield of open culture of microalgae is low and there is serious biological pollution. Complex closed photobioreactor culture of microalgae is easy to control biological pollution and has a relatively high yield, but the cost is also relatively high.

[0004] We have been committed to developing a low-cost and high-yield photobioreactor device for cultivating microalgae. At present, photobioreactors for cultivating microalgae include plate, tubular and column types. The dissolved oxygen level of the tubular reactor is very high, and the accumulation of dissolved oxygen will inhibit the growth of algae. The plate reactor is restricted by height, and a dead corner will be formed at the bottom of the reactor, which is not conducive to the growth of microalgae. The column (or box, tower) reactor overcomes the limitation of oxygen accumulation, has a simple structure, and the culture solution is evenly mixed, and sufficient light source can be obtained.

[0005] CN103087919B discloses a column reactor for cultivating microalgae in organic wastewater. The lower end of the column reactor made of organic glass provides a funnel-shaped opening, and a valve is provided on the opening. The microalgae are stirred and grown in the organic wastewater in the column reactor in a suspended state. A gas supply (carbon dioxide mixed gas) device is provided at the lower part of the reactor. The LED artificial light source is arranged on the periphery of the column. The reactor harvests the microalgae by self-flocculation. Specifically, an alkaline solution is dripped into the reactor, and the concentrated algae pulp is collected from the funnel-shaped opening. Although the harvesting of microalgae reduces a certain amount of work by setting an opening at the lower end of the reactor to flow out the concentrated algae pulp, however, the microalgae still needs to be extracted from the concentrated algae pulp. In addition, since the algae pulp is concentrated with an alkaline solution, the microalgae are also alkalized, and can only continue to treat the wastewater after adjusting the pH value, and are no longer suitable for other purposes.

[0006] In order to reduce the difficulty of harvesting microalgae, CN103966074A discloses a box-type microalgae fixed culture photobioreactor. A light-transmitting reaction box is provided, and several groups of adsorbent materials (filter paper, sponge, foam plastic or fabric fiber) are suspended longitudinally in the box as fixed carriers for the growth of microalgae. The culture liquid is pumped from bottom to top to the circulation pipeline at the bottom of the box, and the circulation pipeline is located above the adsorbent material. The culture liquid flows to the adsorbent material through the small holes in the pipeline. The mixed gas rich in carbon dioxide is input into the box from the side. The light source can be a natural light source or a lighting device in the box. When harvesting, the adsorbent material needs to be taken out and the microalgae needs to be scraped off the adsorbent material. CN109456878A discloses a tower photobioreactor. This patent application is also a fixed culture method. The tower is stacked from bottom to top and arranged in a roughly horizontal direction. The truncated cone tray located in the center fixes the activated sludge beads, and the outer ring tray outside the periphery fixes the microalgae beads.

[0007] Although the immobilized microalgae culture method is conducive to the harvest of microalgae, it is not necessarily suitable for other types of microalgae to be fixed on a carrier for growth. Secondly, the circulation of the culture solution requires additional energy consumption. Since the loading of microalgae is solidified, the area and amount of the adsorption material will determine the production capacity of the microalgae. In the embodiment of CN103966074A, the microalgae density determined by the area and amount of the adsorption material is obviously lower than the density of the suspended microalgae.

[0008] It can be seen from the above patents or applications that the microalgae reactor needs to meet the following basic conditions: sufficient light, sufficient contact with the culture solution, gas circulation (supply of carbon dioxide and discharge of oxygen), and a low-cost, pollution-free and convenient harvesting device. The fixed culture method has its inherent problems, such as low production capacity, limited types of algae cultured, and the need for additional power to achieve a water circulation unit that continuously flows on the carrier. In contrast, although the traditional suspended culture method is conducive to production capacity, it takes time and manpower to extract the microalgae from a large amount of water in the harvesting of microalgae, such as drying or centrifugation. These methods are also not conducive to the reuse of culture solution. The art needs a microalgae culture photobioreactor device that can meet production capacity and facilitate harvesting. Utility Model Content

[0009] According to the present disclosure, various aspects and advantages of the present invention will be partially set forth in the following description, or may be apparent from the description, or may be understood through technical practice.

[0010] The present disclosure provides a photobioreactor device for microalgae cultivation, the device comprising: an outer container for containing culture solution, the outer container comprising a transparent side wall and a removable upper cover; an inner container for containing culture solution and microalgae, the inner container being able to be contained inside the outer container and taken out from the outer container, wherein the inner container comprises a transparent side wall, a top screen and a bottom screen, the top screen and the bottom screen both comprising a screen, the mesh size of the screen being able to allow culture solution and gas to pass therethrough while preventing microalgae from passing therethrough, at least one of the top screen and the bottom screen being able to be removably engaged with the inner container; and a gas circulation unit, the gas circulation unit injecting a carbon dioxide-rich gas into the outer container.

[0011] In some embodiments, the bottom screen has an engagement feature for removably engaging the inner container.

[0012] In some embodiments, the engagement feature is a thread or a snap fit.

[0013] In some embodiments, the device further includes one or more of the following sensors: a temperature sensor, a pH sensor, an air pressure sensor, a carbon dioxide concentration sensor, or a light sensor.

[0014] In some embodiments, the gas circulation unit includes an air inlet for injecting carbon dioxide-rich gas and an air outlet for discharging the gas, the air inlet and the air outlet are respectively connected to an air inlet pipe and an air outlet pipe, the air inlet pipe and the air outlet pipe are respectively provided with an air inlet valve and an air outlet valve, and the air inlet valve and the air outlet valve control the inflow, outflow and flow rate of the air flow.

[0015] In some embodiments, the device further includes an air pressure sensor disposed near the air outlet.

[0016] In some embodiments, the air inlet is arranged at the bottom of the outer container, and the air outlet is arranged at the upper cover.

[0017] In some embodiments, a gas diffuser is disposed at the bottom of the outer container near the gas inlet, and the gas diffuser allows the gas entering from the gas inlet to split into smaller bubbles, thereby achieving more efficient gas exchange and promoting fluidization of the microalgae in the inner container.

[0018] In some embodiments, the device further includes an inlet for injecting culture fluid or water and an outlet for discharging culture fluid, the inlet and the outlet are respectively connected to an inlet pipe and an outlet pipe, the inlet pipe and the outlet pipe are respectively provided with an inlet valve and an outlet valve, and the inlet valve and the outlet valve control the inflow and outflow and flow rate of culture fluid or water.

[0019] In some embodiments, the liquid inlet and the liquid outlet are arranged on the bottom side wall of the outer container. When the liquid inlet and the liquid outlet are used as liquid inlets, the culture solution or water is injected into the outer container by a liquid pump. When the liquid inlet and the liquid outlet are used as liquid outlets, the culture solution in the outer container and the inner container can be discharged during the harvesting of microalgae.

[0020] In some embodiments, the device further includes a second liquid inlet disposed on the upper cover.

[0021] In some embodiments, the air inlet valve and the air outlet valve are electrically connected to the air pressure sensor and / or the carbon dioxide concentration sensor.

[0022] In some embodiments, the liquid inlet valve and the liquid outlet valve are electrically connected to the pH sensor.

[0023] In some embodiments, the device further includes a lighting unit, and the lighting unit is daylight or lamplight.

[0024] In some embodiments, the lighting unit is a waterproof LED light tube arranged in the center of the inner container.

[0025] In some embodiments, the device further includes a base that supports the outer container, provides access for pipes or cables, and / or provides a power source.

[0026] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present technology and, together with the description, are used to explain the principles of the present technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The specification provides a comprehensive and achievable disclosure of the present invention with reference to the accompanying drawings, which is directed to a person skilled in the art and includes the best mode for making and using the present system and method, in which:

[0028] Figure 1 A schematic diagram showing a photobioreactor device for microalgae cultivation according to an exemplary embodiment of the present disclosure;

[0029] Figure 2 shows a schematic diagram of an outer container according to an exemplary embodiment of the present disclosure;

[0030] Figure 3 A schematic diagram of an inner container according to an exemplary embodiment of the present disclosure is shown;

[0031] Figure 4 shows a schematic diagram of a bottom screen according to an exemplary embodiment of the present disclosure;

[0032] Figure 5 A schematic diagram of a base according to an exemplary embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0033] The present invention will now be described in detail with reference to embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. The word "exemplary" is used herein to mean "used as an example, instance or illustration". Any implementation described herein as "exemplary" is not necessarily interpreted as being more preferred or more advantageous than other implementations. In addition, each example is provided by way of explanation rather than limitation of the technology. In fact, it is obvious to those skilled in the art that modifications and changes may be made to the present technology without departing from the scope or spirit of the claimed technology. For example, a feature shown or described as part of one embodiment may be used together with another embodiment to produce yet another embodiment. Therefore, the present disclosure is intended to cover such modifications and changes within the scope of the appended claims and their equivalents. Numerical and letter marks are used in the specific implementation to represent features in the drawings. Similar or similar marks in the drawings and the specification are used to refer to similar or similar parts in the present invention.

[0034] As used herein, the singular expressions "a", "an" and "the" also include the plural case, unless the context clearly dictates otherwise. Terms such as "coupled", "fixed", "connected to", etc. refer to direct coupling, fixing or connection as well as indirect coupling, fixing, or connection through one or more intermediate components or features, unless otherwise specified herein. The terms "include", "comprise", "compose", "have" or any other variations thereof herein are intended to cover non-exclusive inclusion. For example, a process, method, article or device that includes a set of features is not necessarily limited to these features, but may include features that are not explicitly listed or other features inherent to such a process, method, article or device. In addition, unless clearly stated to the contrary, "or" is inclusive rather than exclusive. For example, any of the following satisfies condition A or B: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0035] Terms indicating approximation, such as "about," "approximately," "approximately," or "substantially," include values ​​within 10% greater or less than the value being described. When used in the context of an angle or direction, these terms include values ​​within 10 degrees greater or less than the angle or direction being described. For example, "approximately perpendicular" includes directions that deviate from perpendicular within 10 degrees in any direction (e.g., clockwise or counterclockwise).

[0036] The benefits, other advantages and solutions to the problems are described below in conjunction with specific embodiments. However, the benefits, advantages, solutions to the problems and any features that may cause any benefit, advantage or solution to occur or become more obvious should not be construed as key, required or essential features of any or all claims.

[0037] In general, the photobioreactor device of the utility model is a column reactor using a suspended culture method. The photobioreactor device for microalgae culture described herein can be applied to a variety of microalgae required by the aforementioned industries, such as Spirulina, Chlorella, Haematococcus pluvialis, Nannochloropsis, Dunaliella salina, Phaeochromis triangularis, Cryptodinium coryneformis, Scenedesmus, Chrysophyte, etc.

[0038] Now referring to the accompanying drawings, Figure 1 A schematic diagram of a photobioreactor device 100 for microalgae cultivation according to an exemplary embodiment of the present disclosure is shown. Although the device 100 shown in the figure is a cylinder, it can be understood that the device 100 can also be implemented as a box-type, hexagonal prism, octagonal prism, elliptical prism, or other column-type container suitable for implementing the present invention. The device 100 includes an outer container 200 and an inner container 300 located inside the outer container 200. For clarity, Figure 1The thickness of the side walls of the outer container 200 and the inner container 300 is not shown. The outer container 200 and the inner container 300 both include transparent side walls, which can be made of transparent glass or transparent plastic. Preferably, plexiglass, i.e., polymethyl methacrylate, also known as acrylic material, can be used. The thickness of the plexiglass needs to be selected to meet the requirement that it can still withstand the pressure caused by the liquid after the container is filled with liquid. The outer container 200 and the inner container 300 can be of different shapes. Preferably, the outer container 200 and the inner container 300 are both cylinders. The outer diameter of the cylinder of the inner container 300 can be close to but smaller than the inner diameter of the cylinder of the outer container 200. The size of the outer diameter of the cylinder of the inner container 300 should be set as large as possible, but it does not prevent the inner container 300 from being taken out of the outer container 200 without obstruction. A larger outer diameter of the inner container 300 is conducive to making full use of space, thereby increasing the production capacity of the microalgae 120.

[0039] The inner container 300 can be supported inside the outer container 200 by a support member (not shown). For example, a thicker protrusion can be formed on the inner side of the bottom of the outer container 200 to support the bottom of the inner container 300. In another embodiment, a plurality of vertically upward support columns are formed on the inner side of the bottom of the outer container 200 to support the bottom of the inner container 300. In another embodiment, the inner wall of the outer container 200 forms a support ring with holes through which gas or liquid can pass. The inner diameter of the support ring is slightly smaller than the radius of the inner container 300, and the bottom of the inner container 300 is supported by an annular support member. The support member should be designed not to affect the gas and liquid flow between the outer container 200 and the inner container 300. The support member can be a structure integrally formed with the outer container 200 or the inner container 300, or it can be a separate support member. In other embodiments, the support member can also combine the support function with other components shown in the drawings.

[0040] Figure 2 A schematic diagram of an outer container 200 according to an exemplary embodiment of the present disclosure is shown. An upper cover 210 is provided on the top of the outer container 200. The upper cover 210 can be removably engaged with the outer container 200 in the form of threads, snaps, etc. Optionally, a sealing ring may be provided when the upper cover 210 is engaged with the outer container 200. Preferably, a lock is provided between the upper cover 210 and the outer container 200. When the operator extracts the device 100, it is convenient to move the outer container 200 together with the inner container 300. The operator in this article can be an operator or a manipulator in automated large-scale production. The upper cover 210 can be provided with a handle (not shown) to facilitate the operator's manipulation. The bottom of the outer container 200 can be provided with a lower cover that can maintain liquid tightness. The bottom of the outer container 200 can also be an acrylic material integrally formed with its side wall. When the outer container 200 is filled with liquid, the bottom is open except for necessary openings (for example, Figure 2 A good seal should be maintained except for the air inlet 230 in the middle or the liquid inlet and outlet 250 on the side wall.

[0041] In a preferred embodiment, a sensor group (not shown) may be provided on the top of the outer container 200. The sensor group may be waterproof so as to contact the culture solution for more accurate measurement. The sensor group may include one or more of the following sensors: a temperature sensor, a pH sensor, an air pressure sensor, a carbon dioxide concentration sensor, or a photosensor, etc. Different types of microalgae are suitable for cultivation within different temperature ranges, and the temperature sensor can be used to monitor the temperature of the device 100. The pH sensor can be used to monitor the pH value of the microalgae culture environment (mainly the culture solution 110). Those skilled in the art will appreciate that since the upper cover 210 can conveniently open the outer container 200, it is also possible to monitor the various parameters of the device 100 manually without using sensors. In addition, each sensor may also be set at other positions of the device 100.

[0042] The device 100 includes a gas circulation unit. Specifically, the outer container 200 is provided with an air inlet 230 and an air outlet 240. Preferably, the carbon dioxide-rich gas can be injected into the outer container 200 through the air inlet 230 provided at the bottom of the outer container 200, and the excess gas can be discharged through the air outlet 240 provided at the top of the outer container 200 to balance the internal and external pressures. Figure 2 As shown, the air inlet 230 is arranged at the bottom of the outer container 200, preferably at the center of the bottom to facilitate aeration. The air outlet 240 is arranged at the upper cover 210 of the outer container 200. The carbon dioxide-rich gas can be injected through an air pump. It is understood that the air inlet 230 and the air outlet 240 can also be arranged at other positions of the outer container 200. The air inlet 230 and the air outlet 240 are preferably arranged on opposite sides of the device 100 in the vertical direction to facilitate the gas to fully contact the microalgae 120 ( Figure 3 ). Since the microalgae 120 can fix carbon and release oxygen, the density of the gas flowing out through the air outlet 240 is lower than the density of the gas flowing in through the air inlet 230. Therefore, it is preferred to set the air inlet 230 at the bottom of the outer container 200, and set the air outlet 240 at the top of the outer container 200 (for example, the upper cover 210). The air inlet 230 and the air outlet 240 are respectively connected to the air inlet pipe 232 and the air outlet pipe 242. The air inlet pipe 232 and the air outlet pipe 242 are respectively provided with an air inlet valve 234 and an air outlet valve 244, and the air inlet valve 234 and the air outlet valve 244 control the inlet and outlet and flow rate of the air flow. The air inlet pipe 232 and the air outlet pipe 242 can be plastic pipes, or rubber pipes or other materials. The air inlet pipe 232 and the air outlet pipe 242 preferably stop between the outer container 200 and the inner container 300. In other embodiments, the air outlet pipe 242 may also pass through the top of the inner container 300 to the inside of the inner container 300 .

[0043] In the gas rich in carbon dioxide, the concentration of carbon dioxide can be below 35%. Different species of microalgae have different carbon fixation capabilities. Selecting appropriate carbon dioxide injection concentrations for different microalgae species can significantly increase production capacity. For example, for a certain genus of Scenedesmus used as biofuel, the optimal injection concentration of carbon dioxide is 15%. The carbon dioxide of some green algae can be injected at a gradually increasing concentration, with the highest injection concentration being 18%-22%. For some types of microalgae, high concentrations of carbon dioxide will inhibit their growth, and it is necessary to select an appropriate carbon dioxide injection concentration. For example, some types of Chlorella can be injected at a low concentration of 400-500ppm. Other types of microalgae are suitable for injection concentrations not higher than 6%. In combination with a carbon dioxide concentration sensor, changes in the carbon dioxide content in the device 100 can be effectively monitored. Preferably, a carbon dioxide concentration sensor is provided near the gas outlet 240, thereby enabling real-time monitoring of the consumption capacity of microalgae for carbon dioxide. Preferably, a pressure sensor is provided near the gas outlet 240, thereby enabling real-time detection of changes in air pressure in the device 100. Although each sensor can be monitored manually and the flow valve can be controlled, it is preferred that the carbon dioxide sensor and the pressure sensor are intelligently connected to the inlet valve 234 and the outlet valve 244, and the inlet and outlet and flow of the gas are automatically controlled by a computer or a remote server. In this way, the supply of carbon dioxide is guaranteed, and the pressure inside and outside the outer container 200 is balanced. It will be understood by those skilled in the art that the carbon dioxide concentration range and injection method implemented above are not restrictive.

[0044] In a preferred embodiment, a gas diffuser 220 may be provided at the bottom of the outer container 200. The gas diffuser 220 is provided near the gas inlet 230. Figure 2 As shown, the gas diffuser 220 is located above the air inlet 230. When the air inlet 230 is located on the bottom side wall, the gas diffuser 220 is located on the side of the air inlet 230. The gas diffuser 220 is used for aeration and has a porous structure and can be made of metal or other materials. The gas diffuser 220 can be a common disc-type gas diffuser or a Figure 2 The hood-type gas diffuser is shown located above the gas inlet 230. The gas diffuser 220 allows the gas entering through the gas inlet 230 to be split into smaller bubbles at the dense holes, thereby achieving more efficient gas exchange and promoting fluidization of the microalgae 120 in the inner container 300.

[0045] Although the present invention can add solid culture medium or pour in / out culture solution 110 by opening the upper cover 210, preferably, the device 100 can also include an inlet for injecting culture solution 110 or water and an outlet for discharging culture solution, the inlet and the outlet are respectively connected to an inlet pipe and an outlet pipe, the inlet pipe and the outlet pipe are respectively provided with an inlet valve and an outlet valve, and the inlet valve and the outlet valve control the inflow and outflow and flow rate of culture solution or water. Figure 2 In the preferred embodiment shown, the bottom side of the outer container 200 is provided with an inlet and outlet 250. The inlet and outlet 250 can help adjust the composition and concentration of the culture solution 110. When the inlet and outlet 250 is used as an inlet, it is connected to a liquid pump to inject the culture solution 110 or water into the outer container 200. When the inlet and outlet 250 is used as an outlet, the excess culture solution 110 can be discharged. Importantly, when harvesting the microalgae 120, the inlet and outlet 250 can be used as an outlet to discharge all the culture solution 110 in the outer container 200 and the inner container 300. The inlet and outlet 250 can be connected to an inlet and outlet pipe 252. The inlet and outlet pipe 252 can be provided with an inlet and outlet valve 254, and the inlet and outlet valve 254 controls the inlet and outlet and flow rate of the culture solution 110 or water. The culture solution discharged from the inlet and outlet 250 can also be stored for recycling. The inlet and outlet valve 254 can be electrically connected to, for example, a pH sensor to achieve automatic control of the valve. Figure 2 As shown, the upper cover 210 is provided with a second liquid inlet 260 ( Figure 1 250). The culture solution 110 can be injected into the outer container 200 through the liquid inlet 260. The culture solution 110 consumed during the growth of the microalgae can also be replenished by injecting new culture solution 110 through the liquid inlet 250. The liquid inlet 260 is connected to the liquid inlet pipe 262. The liquid inlet pipe 262 can be provided with a liquid inlet valve 264, and the inflow and flow rate of the liquid are controlled by the liquid inlet valve 264. The provision of the second liquid inlet 260 can avoid frequent opening of the upper cover 210. Choosing to add a solid culture medium or pouring the culture solution 110 on the top can allow the nutrients to be fully mixed with the water and infiltrate the algae beads 120.

[0046] Targeted culture solutions can be used for microalgae of different types and uses. For example, for a certain type of Chlorella cultivated for the purpose of extracting nutrients, the concentrations of total nitrogen and total phosphorus in the injected culture solution can be 15-25 mg / L and 1.5-2.5 mg / L, respectively. Nitrogen-containing compounds can be, for example, urea, sodium nitrate, etc. Phosphorus-containing compounds can be selected from potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium hydroxide, etc. Other components of compounds can also be selectively added to the culture solution in trace amounts to help the growth of microalgae, such as copper sulfate, iron sulfate, zinc sulfate, magnesium sulfate, ferrous sulfate, cobalt chloride, sodium chloride, calcium chloride, disodium ethylenediaminetetraacetic acid, boric acid, etc. In other embodiments, if the microalgae is used for sewage treatment, sewage can be poured or injected as the culture solution. Those skilled in the art will understand that the composition and concentration of the culture solution implemented above are not restrictive.

[0047] Figure 3 Schematic diagram of an inner container 300 according to an exemplary embodiment of the present disclosure is shown. The inner container 300 includes a top screen 310 and a bottom screen 320 located at the top and bottom of the inner container 300, respectively. The top screen 310 and the bottom screen 320 are designed to allow gas or culture solution 110 to enter and exit. At least one or both of the top screen 310 and the bottom screen 320 can be removably engaged with the inner container 300. For example, it is engaged with the inner container 300 in the form of a thread, a snap, etc. Optionally, a lock is provided at the removable joint. The following takes the bottom screen 320 being removable from the inner container 300 as an example. In a preferred embodiment, the top screen 310 and the bottom screen 320 can have the same configuration. Preferably, a handle 340 is provided on the top screen 310 to facilitate the operator to take the inner container 300 out of the outer container 200. During the cultivation of the microalgae 120, the handle 340 can be pivoted and moved to the side of the top screen 310 so as not to affect the gas and liquid entering and exiting the inner container 300.

[0048] Figure 4 A schematic diagram of a bottom screen 320 according to an exemplary embodiment of the present disclosure is shown. The bottom screen 320 includes a screen 322. The microalgae 120 in suspension culture is contained in the inner container 300. The mesh size of the screen 322 should be designed to allow gas and culture solution 600 to pass through, while the microalgae 120 cannot pass through it. Different microalgae species have different algae bead sizes, and the mesh size of the screen 322 can be adapted to the size of different types of microalgae 120. Figure 4The bottom screen 320 in the embodiment may further include a coupling feature 326 with the inner container 300. In a preferred embodiment, the coupling feature 326 provides both the functions of a thread and a buckle. In other embodiments, the coupling feature 326 may only provide a coupling function. In some embodiments, the coupling feature 326 may further include a lock. Since the mesh size of the screen 322 prevents the microalgae 120 from passing through it, the microalgae 120 is suspended inside the inner container 300 without leaking into the space between the outer container 200 and the content 300. Since the mesh size of the screen 322 allows the gas and the culture solution 110 to pass through it, the culture solution 110 and the gas can be filled in the inner container 300 and the outer container 200, including the space between the outer container 200 and the content 300, so that the microalgae 120 can fully contact the carbon dioxide-rich gas and the culture solution 110. When the inner container 300 is removed from the outer container 200 to harvest the microalgae 120, the bottom screen 320 may need to be removed. Therefore, the bottom screen 320 may further include friction features or other engagement features that facilitate removal of the bottom screen 320 from the inner container 300 by an operator.

[0049] In some embodiments, when the culture solution 110 needs to be retained in the outer container 200, that is, when the culture solution 110 does not need to be drained through the liquid inlet and outlet 250, the device 100 may further include a hollow support structure. The support structure can support the inner container 300 on the top of the outer container 200 when the inner container 300 is taken out of the outer container 200, so as to wait for the culture solution 110 to flow back to the outer container 200 through the screen 322 and the hollow part of the support structure.

[0050] Regardless of the method used to discharge the culture solution 110 from the inner container 300, the microalgae 120 will remain in the inner container 300 due to being blocked by the screen 322. Optionally, when the top screen 310 is designed to be removable (the bottom screen 320 is removable or non-removable), the top screen 310 can be opened to pour the microalgae 120 out of the inner container 300.

[0051] The utility model utilizes the setting of a double-layer container and sets a screen 322 in the inner container 300, thereby greatly reducing the cost of separating the microalgae 120 from the culture solution 110, and the culture solution 110 can be recycled without contaminating the culture solution 110 and the microalgae 120. For example, the sun drying method or centrifugation method commonly used in the art requires time, power and manpower, and the flocculation method will change the composition of the microalgae 120. When culturing microalgae on a large scale, it can be considered to use a fully automatic robotic arm to replace the operator to perform the above process.

[0052] The device 100 may further include a lighting unit. The lighting unit may be a waterproof LED light tube 330 arranged in the center of the inner container 300 (see Figure 3). Optionally, the lighting unit may also be other types of non-LED lighting devices. The lighting unit may also be arranged in other places, for example, the lower surface of the upper cover 210, the base 400 of the outer container 200 ( Figure 5 ) or the outside of the device 100. In some embodiments, the inner container 300 may be provided with a transparent hollow column at the center thereof that is higher than the liquid level of the outer container 200, so that a lighting unit that does not need to be particularly waterproof can pass through it. Optionally, the photosensitive sensor can sense the light intensity of the environment in which the device 100 is located. When the external light (such as sunlight) is sufficient to provide the required light intensity for the microalgae 120, the lighting unit can be turned off. When the external light is insufficient, the lighting unit can be automatically lit. The lighting unit can be powered by mains electricity, disposable batteries, rechargeable batteries, etc. For example, a cable can pass through the base 400, or a battery holder or charging method can be provided on the base 400. In some embodiments, the lighting unit can be charged during the day and automatically lit at night. As a result, the microalgae 120 can absorb light energy 24 hours a day to increase production capacity. In other embodiments, the device 100 may not include a lighting unit, but be illuminated by daylight or indoor lighting. The lighting unit can also be used to assist in adjusting the ambient temperature of the device 100 . For example, the lighting unit can be combined with a temperature sensor or further electrically connected to the temperature sensor. The lighting unit can be automatically illuminated to increase the temperature of the device 100 based on input data from the temperature sensor.

[0053] Figure 5 Schematic diagram of a base 400 according to an exemplary embodiment of the present disclosure is shown. The base 400 may be an independent component arranged below the outer container 200, or may be integrally formed with the bottom of the outer container 200. The base 400 may be a hollow transparent structure, with a window 410 and a window 420 respectively opened from the top and the side to lead out the air inlet pipe 232. Since the air inlet pipe 232 is located at the center of the bottom of the outer container 200, the base 400 may be used to stably support the outer container 200. The base 400 may also provide other functions, such as assisting the introduction and extraction of cables for the lighting unit or sensor, or providing power, etc.

[0054] This specification uses examples to disclose the utility model, including the best mode, and enables any technician in the field to practice the utility model, including making and using any device or system and performing methods that are combined with each other without contradiction between any embodiments. The patent scope of the utility model is defined by the claims and may include other examples that can be thought of by those skilled in the art. If these other examples include structural elements that are not different from the literal wording of the claims, or include equivalent structural elements that are not substantially different from the literal wording of the claims, the scope of the claims covers these other examples.

Claims

1. A photobioreactor device for microalgae cultivation, characterized in that: The device comprises: An outer container for containing a culture solution, the outer container comprising a transparent side wall and a removable upper cover; An inner container for containing the culture solution and microalgae, the inner container being capable of being contained inside the outer container and being taken out from the outer container, wherein the inner container comprises a transparent side wall, a top screen and a bottom screen, the top screen and the bottom screen both comprising a mesh having a mesh size capable of allowing the culture solution and gas to pass therethrough while preventing the microalgae from passing therethrough, and at least one of the top screen and the bottom screen being capable of being removably engaged with the inner container; and A gas circulation unit is provided for injecting a gas rich in carbon dioxide into the outer container.

2. The device according to claim 1, characterized in that The bottom screen has an engagement feature that removably engages the inner container.

3. The device according to claim 2, characterized in that The engagement feature is a thread or a snap fit.

4. The device according to claim 1, characterized in that The device further comprises one or more of the following sensors: a temperature sensor, a pH sensor, an air pressure sensor, a carbon dioxide concentration sensor or a light-sensitive sensor.

5. The device according to claim 1, characterized in that The gas circulation unit includes an air inlet for injecting the carbon dioxide-rich gas and an air outlet for discharging the gas, the air inlet and the air outlet are respectively connected to an air inlet pipe and an air outlet pipe, the air inlet pipe and the air outlet pipe are respectively provided with an air inlet valve and an air outlet valve, and the air inlet valve and the air outlet valve control the inlet, outlet and flow rate of the air flow.

6. The device according to claim 5, characterized in that The device further includes an air pressure sensor disposed near the air outlet.

7. The device according to claim 5, characterized in that The air inlet is arranged at the bottom of the outer container, and the air outlet is arranged at the upper cover.

8. The device according to claim 7, characterized in that A gas diffuser is disposed at the bottom of the outer container near the gas inlet, and the gas diffuser allows the gas entering from the gas inlet to be split into smaller bubbles, thereby achieving more efficient gas exchange and promoting fluidization of the microalgae in the inner container.

9. The device according to claim 1, characterized in that The device further includes a liquid inlet for injecting the culture solution or water and a liquid outlet for discharging the culture solution, the liquid inlet and the liquid outlet are respectively connected to a liquid inlet pipe and a liquid outlet pipe, the liquid inlet pipe and the liquid outlet pipe are respectively provided with a liquid inlet valve and a liquid outlet valve, and the inlet valve and the liquid outlet valve control the inflow and outflow and flow rate of the culture solution or water.

10. The device according to claim 9, characterized in that The liquid inlet and the liquid outlet are arranged on the side wall of the bottom of the outer container. When the liquid inlet and the liquid outlet are used as the liquid inlet, the culture solution or water is injected into the outer container by a liquid pump. When the liquid inlet and the liquid outlet are used as the liquid outlet, the culture solution in the outer container and the inner container can be discharged during the harvesting of the microalgae.

11. The device according to claim 10, characterized in that The device also includes a second liquid inlet arranged on the upper cover.

12. The device according to claim 6, characterized in that The air inlet valve and the air outlet valve are electrically connected to the air pressure sensor and / or the carbon dioxide concentration sensor.

13. The device according to claim 9, characterized in that The liquid inlet valve and the liquid outlet valve are electrically connected to the pH sensor.

14. The device according to claim 1, characterized in that The device further comprises a lighting unit, which is daylight or lamplight.

15. The device according to claim 14, characterized in that The lighting unit is a waterproof LED light tube arranged in the center of the inner container.

16. The device according to claim 1, characterized in that The device further includes a base that supports the outer container, provides access for pipes or cables, and / or provides a power source.

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