WO2023228010A1

WO2023228010A1 - System for cultivating and harvesting biomass

Info

Publication number: WO2023228010A1
Application number: PCT/IB2023/055035
Authority: WO
Inventors: Insaf AYARI
Original assignee: Food For Future Sarl
Priority date: 2022-05-23
Filing date: 2023-05-16
Publication date: 2023-11-30

Abstract

The present disclosure describes a photobioreactor for cultivating and harvesting phototrophic microorganisms. The photobioreactor includes at least a cultivation system and a harvest system, and may include other systems such as nutrients supply system. The cultivation system includes a container for containing and cultivating a suspension culture of microorganisms. A plurality of air injectors are provided on a bottom wall of the container to agitate the culture. In addition, the cultivation system includes a filtration container with a removable filter screen for separating the biomass from the culture. The filtration container may revolve around a vertical axis while tilting relative to the vertical axis. The air injectors are effective in preventing the microorganisms from gathering towards the bottom wall, and prominently reduces the time and cost required to cultivate high quality. The photobioreactor may also communicate with and controlled by a remote computing device.

Description

SYSTEM FOR CULTIVATING AND HARVESTING BIOMASS

TECHNICAL FIELD

[0001] The present invention relates to the field of cultivating and harvesting biomass, and more particularly relates to the field of systems and devices for cultivating and harvesting biomass such as cyanobacteria or microalga through photobioreactors (PBR).

BACKGROUND

[0002] Photobioreactors have been used for both large-scale and at-home production of phototrophic microorganisms and biomass, such as cyanobacteria or microalgae. Specifically, Spirulina is a biomass of cyanobacteria (blue-green algae) that is particularly popular since it is ecologically sound and nutrient-rich in protein and vitamins. Spirulina may be used as a dietary supplement or whole food for humans. It is also used as a feed supplement in the aquaculture, aquarium, and poultry industries. Cultivation of such cyanobacteria and microalgae also consumes carbon dioxide and generates oxygen, therefore it also has a potential in carbon mitigation.

[0003] Photobioreactors have been developed and discussed in the art. For example, in Yusuf Chisti & Murray Moo- Young, Bioreactors, Encyclopedia of Physical Science and Technology 247-271 (2003), different types of bioreactors and considerations for their designs are discussed.

[0004] There are also prior art references describing specific designs of bioreactor and related mechanisms and methods for cultivating and harvesting the microorganisms.

In Jian Li et al., Design and characterization of a scalable airlift flat panel photobioreactor for microalgae cultivation, 27 Journal of Applied Phycology 75-86 (2014), a flat panel photobioreactor prototype with bulk liquid flow driven by an external airlift has ben designed, modeled and experimentally characterized for the purpose of developing scalable industrial photobioreactors. In Megan S. Fulleringer et al., Design of a Small Scale Algae Cultivation System to Produce Biodiesel, McGill University (2009), a small-scale algae cultivation system for the production of biodiesel is disclosed. In Ekkachai Kanchanatip et al., Fouling characterization and control for harvesting microalgae Arthrospira (spirulina) Maxima using a submerged, disc-type ultrafiltration membrane, 209 Bioresource Technology 23-30 (2016), the fouling of a circular-disc ultrafiltration membrane in a submerged bioreactor system to harvest Arthrospira maxima cells is disclosed. In P. Carlozzi, Hydrodynamic aspects and Arthrospira growth in two outdoor tubular undulating row photobioreactors, 54 Applied Microbiology and Biotechnology 14-22 (2000), two tubular undulating row photobioreactors with a high illuminated surface/volume ratio has been designed and constructed for the growth of photosynthetic microorganisms. In European Patent Application Publication No. EP 2 568 038 Al, a modular photobioreactor for producing microalgae particularly indicated for absorber emission gases with a high carbon dioxide (CO2) content is disclosed. In Zhang Xu et al., A simple and low-cost airlift photobioreactor for microalgal mass culture, 24 Biotechnology Letters 1767-1771 (2002), an airlift photobioreactor for microalgal mass culture has been designed and developed. In Gulab Singh et al., Microalgae harvesting techniques: A review, 217 Journal of Environmental Management 499-508 (2018), a discussion is focused on assessing technical, economical and application potential of various harvesting techniques so as to allow selection of an appropriate technology for cost effectively harvesting of microalgae from their culture medium. PCT Application Publication No. WO 2013/126560A2 discloses a non-blocking filtration system wherein the suspension filtered continuously scrubs the filter, keeping it free of deposits of solid deposits while the filtrate is removed in a variety of biological and chemical applications, substantially reducing the cost of unit operations. U.S. Patent No. 10,851,511 discloses a mobile microalgae harvesting apparatus including a harvesting boom coupled to a harvesting vessel , where the harvesting boom skims a microalgae mixture of microalgae and water from a surface of a body of water down to a predetermined depth below the surface. PCT Application Publication No. WO 2014/064602A3 provides a photobioreactor comprising a sealed, covered plastic sheeting coated with a thin layer of a highly dense culture of photoautotrophic single celled organism. European Patent Publication No. EP 2164640B1 discloses a continuous process for recovering and concentrating valuable components from microalgae. U.S. patent application publication No. US2012/0202290A discloses a tubular photobioreactor that has a core structure in the shape of a truncated cone and one or more transparent or translucent tubes which are helically wound around the core structure. U.S. patent application publication No. 2021/0062124A1 discloses a photobioreactor system with a plurality of elongated bioreactors with an air mixing system in each bioreactor. PCT Application publication No. WO2021/164509A1 discloses a cell separation apparatus for bioreactor with a filter membrane and a flow drive assembly using paddles to drive the flow movement. However, these devices are highly complicated and are designed for mass production or use in a lab. In addition, the separation of the biomass from the culture may take an extensive time.

[0005] In addition, conditions for cultivating microorganisms have been evaluated. In Attilio Converti et al., Cultivation of spirulina platensis in a combined airlift-tubular reactor system, 32 Biochemical Engineering Journal 13-18 (2006), a study is disclosed aiming at evaluating the efficiency of a bench-scale tubular photobioreactor by means of batch cultivations of Spirulina platensis under light- limited conditions. In Hong-Wei Yen et al., Design of photobioreactors for algal cultivation, Biofuels from Algae 225-256 (2019), factors affecting microalgae growth and biofuels production, and microalgae cultivation in closed and open systems are discussed. In Vincent Rochatte. Developpement et modelisation d’un photobioreacteur solaire a dilution intemedu rayonnement. Autre. Universite Blaise Pascal - Clermont-Ferrand II, 2016. Frangais, a approach is developed based on the construction of models of photobioreactors, capable of predicting their performance regardless of their geometry, the lighting conditions, or the cultivated microalgae. In Roger W. Babcock Jr et al., Hydrodynamics and mass transfer in a tubular airlift photobioreactor, 14 Journal of Applied Phycology 169-184 (2002), a methodology is described to determine the mass transfer coefficients for O2 stripping and CO2 dissolution which would be required to achieve a desired biomass productivity. In N’goran Urbain Niangoran. Optimisation de la culture de la spiruline en milieu controle : eclairage et estimation de la biomasse. Optique / photonique. Universite Paul Sabatier - Toulouse III, 2017, Frangais, optimization of spirulina cultivation in a controlled environment regarding lighting and biomass estimation is discussed. In F. Fasaei et al., Techno- economic evaluation of microalgae harvesting and dewatering systems, 31 Algal Research 347-362 (2018), a study is disclosed concerning a quantitative techno-economic analysis of different large-scale harvesting and dewatering systems with focus on processing cost, energy consumption and resource recovery.

[0006] However, there is a need in the art of photobioreactors for cultivating and harvesting biomass that is compact and streamlines the cultivation and harvest process, thus is particularly suitable for at-home production of phototrophic organisms and biomass. There is also a need in the art for a photobioreactor that is capable of facilitating and thus expediting the separation of biomass from the suspension culture. In addition, there is a need in the art for a photobioreactor that may ensure the quality of the biomass and improve the production yield of the biomass.

SUMMARY

[0007] One aspect of the invention provides a biomass harvest system, which comprises: an inlet through which a suspension culture may be able to be introduced; a filtration container that may be configured to revolve around a vertical axis while tilting relative to the vertical axis, wherein the filtration container may be in fluid communication with an outlet; a filter screen that may be removably attached within the filtration container; and a piston that may be able to move towards and away from the filtration container, wherein the piston is configured to press excess fluid out of the filtration container.

[0008] According to one aspect of the invention, the piston may be movable towards and away from the filtration container between an extended position in which the piston extends into the filtration container and a retraction position in which the piston is spaced from the filtration container, the piston may press excess fluid out of the filtration container in the extended position.

[0009] According to one aspect of the invention, the extended position may comprise a plurality of extended positions that differ from each other in a distance to a bottom of the filter screen.

[00010] According to one aspect of the invention, the filtration container may be supported by a shaft that tilts relative to the vertical axis, and the shaft may revolve around the vertical axis while tilting relative to the vertical axis thus the filtration container revolves along with the shaft. In addition, the shaft may be pivotably connected to a spindle at an eccentric location, and the spindle may extend along the vertical axis and is configured to rotate around the vertical axis.

[00011 ] According to one aspect of the invention, the biomass harvest system may further comprise a chassis and a cradle block, wherein the cradle block may be supported by the chassis in a manner that the cradle block is pivotable relative to the chassis around a horizontal axis that is perpendicular to the vertical axis, and the shaft may be supported by the cradle block in a manner that the shaft is pivotable relative to the cradle block around a pivoting axis that is perpendicular to the horizontal axis. [00012] According to one aspect of the invention, the shaft may comprise a sink hole that communicate an inner space of the filtration container with the outlet.

[00013] According to one aspect of the invention, the piston may comprise a center passage that opens in a bottom of the piston facing the filtration container, and the inlet is communicated to the center passage.

[00014] According to one aspect of the invention, the filter screen may be of a shape of a truncated cone.

[00015] According to one aspect of the invention, the filter screen may comprise a protrusion provided in a center of a bottom wall of the filter screen.

[00016] According to one aspect of the invention, the filter screen may comprise a plurality of perforations.

[00017] According to one aspect of the invention, a diameter of the plurality of perforations may be in a range of 10-100 microns, or 20-80 microns, or 30-60 microns. [00018] Another aspect of the invention provides a biomass cultivation system, which comprises: a container in which a suspension culture of microorganisms may be contained; and a plurality of injectors provided on a bottom wall of the container, the plurality of injectors ejecting a gas into the suspension culture to agitate the suspension culture; and a gas source that may supply a gas to the plurality of injectors, wherein each of the plurality of injector may eject the gas along an ejection direction that tilts upward relative to a horizontal plan; and at least a part of the plurality of injectors may be distributed so as to, when viewed in a top view of the bottom wall, eject the gas in a substantively same circumferential direction.

[00019] According to another aspect of the invention, the part of the plurality of injectors are evenly distributed along a circle around a center of the bottom wall.

[00020] According to another aspect of the invention, the circle may be of a shape selected from round, oval, square, triangle, rectangle, rounded rectangle, and polygon. [00021 ] According to another aspect of the invention, the plurality of injectors may comprise a plurality of first injectors and a plurality of second injectors; the plurality of first injectors may be distrusted along a same circle along which the plurality of second injectors are distributed; and when viewed in the top view of the bottom wall, the plurality of first injectors may eject the gas in a first circumferential direction that is opposed to a second circumferential direction in which the plurality of second injectors eject the gas. [00022] According to another aspect of the invention, the plurality of injectors may comprise a plurality of first injectors and a plurality of second injectors; the plurality of first injectors may be distrusted along a first circle that is different from a second circle along which the plurality of second injectors are distributed.

[00023] According to another aspect of the invention, each of the injectors may comprise a first section and a second section that are connected to each other; the first section may extend vertically and is fixed to the bottom wall; and the second section may extend along the ejecting direction.

[00024] According to another aspect of the invention, the ejecting direction may form an angle relative to the horizontal plan in a range selected from the group consisting of 20-70 degree, 25-65 degrees, and 30-60 degrees.

[00025] According to another aspect of the invention, when viewed in the top view of the bottom wall, the ejecting direction of each injector may form an angle relative to a radial direction towards a center of the bottom wall in a range of 70-1 10 degrees, 75-105 degrees, 80-100 degrees, and 85-95 degrees.

[00026] According to another aspect of the invention, the gas source may be selected from a group consisting of an air compressor, an air pump, and a compressed air tank.

[00027] According to another aspect of the invention, the container may further comprise an outer cylinder and an inner cylinder in the outer cylinder; the suspension culture may be contained in a space between the outer cylinder and the inner cylinder; and a light source may be provided inside of the inner cylinder.

[00028] According to another aspect of the invention, the light source may comprise at least one selected from the group consisting of a light emitting diode light source, an incandescent lamp, a fluorescent lamp, and an ultraviolet light source.

[00029] Furthermore, an additional aspect of the invention provides a photobioreactor comprising the biomass harvest system as aforementioned and/or the biomass cultivation system as aforementioned.

[00030] According to the additional aspect of the invention, the photobioreactor may further comprise a housing that contains the biomass harvesting system and supports the container of the cultivation system a control compartment containing the harvest system. [00031 ] According to the additional aspect of the invention, the housing may further comprise an input compartment; the input compartment may comprise an inlet that is in fluid communication with the container in the cultivation system; the input compartment may be configured to be removably attached to a nutrient cartridge, wherein when the nutrient cartridge is attached, the inlet may be in fluid communication with an inner space of the nutrient cartridge.

[00032] According to an additional aspect of the invention, the photobioreactor further comprising a networking module that communicates with a mobile computing device, wherein the mobile computing device can display an operational status of the photobioreactor.

[00033] According to an additional aspect of the invention, the mobile computing device can control the photobioreactor.

[00034] According to an additional aspect of the invention, the photobioreactor further comprising communicating with a cloud based service, and communicating with the mobile computing device vis the cloud based service.

[00035] According to an additional aspect of the invention, the mobile computing device is a smart phone.

[00036] The aspects of the invention provide many advantages. The photobioreactor is compact in structure, is effective in preventing the microorganisms from gathering towards the bottom wall, and thus may prominently reduce the time and cost required to cultivate high quality biomass regardless of natural conditions and climatic constraints. With a closed and controlled biomass cultivation system, optimized cultivation conditions and production yield are guaranteed. In addition, the aspects of the invention may be fully automated and expandable to connect to a remote management platform to provide an optimized user experience.

BRIEF DESCRIPTION OF DRAWINGS

[00037] The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings,

[00038] FIG. 1 illustrates a side view of the photobioreactor according to one embodiment of the present invention; [00039] FIGS. 2A-2C illustrate schematic diagrams of the hydraulic circuits in the photobioreactor according to one embodiment of the present invention;

[00040] FIGS. 3A-3D illustrate the structure of the harvest system in the photobioreactor according to one embodiment of the present invention; specifically, FIG. 3A illustrates a side view of the harvest system when the piston aligns with the filtration container, FIG. 3B illustrates a vertical cross section view of the filtration container and components that support and move the filtration container, FIG. 3C illustrates a partial perspective view of the components in the circle 3C of FIG. 3B, FIG. 3D illustrates a cross section view taken along the plane 3D-3D of FIG. 3B, FIG. 3E illustrates a mechanical transmission diagram showing the power transmission forming the movement of the filtration container, FIG. 3F illustrates a cross section view of the piston of the harvest system, FIG. 3G illustrates the state in which the piston is located at the retracted position, and FIG. 3H illustrate the state in which the piston is located at the extended position;

[00041 ] FIGS. 4A-4C illustrate partial views of the harvest system during the flushing process according to one embodiment of the present invention;

[00042] FIGS. 5A and 5B illustrate a perspective view and a cross section view, taken along the plane 5B-5B of FIG. 5A, of the container of the cultivation system according to one embodiment of the present invention;

[00043] FIG. 6 illustrates a cross section view of the input mechanism of the cultivation system according to one embodiment of the present invention;

[00044] FIGS. 7A-7C illustrate views of the airlift agitation mechanism of the cultivation system according to one embodiment of the present invention; specifically, FIG. 7A illustrates a top view of the bottom of the container, FIG. 7B illustrates a side view of an injector, and FIG. 7C illustrates a front view of the injector; and

[00045] FIGS. 8A-8D illustrate the arrangement and structure of the injectors according to other embodiments of the present invention;

[00046] FIG. 9 illustrates an exemplary structure of the control unit according to one embodiment of the present invention;

[00047] FIG. 10 illustrates an exemplary implementation of the microcontroller and the components of the present invention;

[00048] FIG. 11 illustrates a main routine run by the control unit according to one embodiment of the present invention; and [00049] FIG. 12. illustrates an exemplary embodiment of the present invention further comprising a cloud based service and communicating with a mobile computing device.

DETAILED DESCRIPTION

[00050] In the drawings, like numerals indicates like elements throughout. Certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. The terminology includes the words specifically mentioned, derivatives thereof and words of similar import. The embodiments illustrated below are not intended to be exhaustive or to limit the invention to the precise form disclosed. These embodiments are chosen and described to best explain the principle of the invention and its application and practical use and to enable others skilled in the art to best utilize the invention.

[00051] FIG. 1 illustrates a side view of the photobioreactor 100 according to one embodiment of the present invention, showing the appearance of the photobioreactor 100. The photobioreactor 100 is designed for cultivating and harvesting biomass, such as cyanobacteria or microalgae, at home. Other embodiments may also be used in large scale production of biomass. The photobioreactor generally comprises a cultivation system for growing the biomass in a suspension culture and a harvest system for separating and collecting the biomass from the suspension culture. The photobioreactor 100 further comprises hydraulic circuits connecting the cultivation system and harvest system to deliver suspension culture, water, waste etc. between the systems, and a control unit to control the components in the photobioreactor. The cultivation system comprises a container for containing the suspension culture and an input mechanism for introducing substances such as starter culture and nutrients to the container. As shown in FIG. 1, the photobioreactor 100 comprises a cultivation system 102 and a housing 101 supporting the cultivation system 102 and accommodating other components (not shown in FIG. 1), such as the harvest system, the input mechanism, the hydraulic circuits, the electric circuits, and the control unit, among others. The housing 101 comprises an input compartment 101a on top of the cultivation system 102, a base 101b supporting all the components including the cultivation system 102 from the bottom, and a harvest compartment 101c extending between the input compartment 101a and the base 101b and alongside of the cultivation system 102. The input compartment 101a mainly contains the input mechanism for introducing starter microorganisms, nutrients and so on to the cultivation system 102, and other components, for example, related hydraulic circuits. The harvest compartment 101c contains the harvest system, part of the hydraulic circuits and electric circuits, among the others. The base 101b, in addition to supporting the cultivation system 102, may also contain components necessary for the photobioreactor 100, such as hydraulic circuits, electric circuits, agitation mechanism for agitating the suspension culture, etc. The control unit is also contained in the housing 101 at an appropriate location based on the design and structure of the components. In the embodiment shown in FIG. 1, the exposed cultivation system 102 makes the suspension culture visible to a user, the user may observe the suspension culture that may be illuminated by the light source in the cultivation system 102. In addition, the other components are accommodated in an integrated housing 101 which is attached to and supports the cultivation system 102. Therefore, the photobioreactor 100 provides a compact design that is also aesthetically satisfying. The photobioreactor 100 is thus particularly desirable as a home appliance. In other embodiments, the photobioreactor may be designed in other ways. For example, the cultivation system may be detachable from the housing. In addition, the cultivation system may be separated from the harvest system with hydraulic circuits and electric circuits connected between the two systems.

[00052] Below, embodiments of the photobioreactor and its components will be described in detail by referring to the drawings.

[00053] Hydraulic Circuits

[00054] FIGS. 2A-2C illustrate schematic diagrams of the photobioreactor 100 according to one embodiment of the present invention, depicting the hydraulic and fluid circuits in and between the cultivation system 102 and the harvest system 204. The hydraulic and fluid circuits may include but are not limited to, hydraulic circuits transferring suspension culture, water, flushing agent, or waste to and from the cultivation system and harvest system and between these two systems, hydraulic circuits for adding nutrients, water, and starter biomass to the cultivation system, and gas supply circuit for supplying gas (for example, air) to the airlift agitation mechanism. These circuits may comprise devices such as, check valves, two-way valves, flow rate meters, pumps, metering pumps, pressure sensors, and so on. In this embodiment, most of these devices may communicate with and/or be electrically controlled by a control unit (see FIG. 9). However, some of these devices may be self-controlled or regulated. For example, check valves may be completely mechanical and reply on a pressure differential to only allow a fluid flow in one direction. Unless otherwise indicated, the “valve” hereinafter refers to a two-way valve that allows a fluid flow in both directions and switches between an open state and a closed state through an actuator that can be in turn controlled by the control unit, for example, pneumatic, hydraulic, electric actuator). An example of electric actuated valve is solenoid valve. However, it shall be understood that in another embodiment, these valves may also be manually controlled by a user.

[00055] As shown in FIGS. 2A-2C, the photobioreactor 100 comprises a cultivation system 102 and a harvest system 204, as the main components. The microorganisms, such as, macroalgae, microalgae, cyanobacteria and purple bacteria, are cultivated in the cultivation system 102, using photosynthesis to generate biomass from lights and carbon dioxide. The generated biomass together with the water, that is, suspension culture, will then be discharged to the harvest system 204 to extract the biomass from the suspension culture.

[00056] The cultivation system 102 includes a container 203 in which phototrophic microorganisms can be cultivated in water with the aid of a light source housed in an inner cylinder 506. In this embodiment, the container 203 is cylindrical with a round cross section. In other embodiments, the cross section of the cylindrical container may be of any other shapes, such as rectangular, triangular, oval, among others.

[00057] The top of the container 203 is provided with an opening 206 to as an inlet to receive substances such as starter microorganisms (for example, spirulina), water, sterile agent, nutrients, etc. In addition, the nutrients may be drawn from a nutrient cartridge in the input compartment 101a into the container 203 through a pump 242. A degassing outlet 248 is also provided to release excess gases in the container 203. The gases may include those generated by the culture in the container 203, or those from the injectors of the airlift agitation mechanism for agitating the culture, which will be described later.

[00058] A plurality of injectors 250 are distributed in the bottom of the container 203 to stir and agitate the suspension culture so as to keep the microorganisms distributed evenly in the culture and prevent the microorganisms to deposit and gather towards the bottom of the container. A gas source, such as an air pump, 246 is connected to the injectors 250 through a check valve 220 and supply a gas, for example, air, to the injectors 250. The structure and distribution of the injectors 250 will be described in detail later.

[00059] A harvest hydraulic circuit 260 is provided, delivering fluid, such as suspension culture, from the cultivation system 102 to the harvest system 204. A waste hydraulic circuit 270 is also provided, between the harvest system 204 and the waste tank 218, delivering fluid, such as filtered suspension culture or flushing fluid, from the harvest system 204 to the waste tank 218 to be disposed. Optionally, in addition to the harvest hydraulic circuit 260 and waste hydraulic circuit 270, additional hydraulic circuit may be provided. For example, a flushing hydraulic circuit 280 may be provided, delivering flushing fluid such as water or sterile agent from the flushing tank 216 to the harvest system 204. A recycle hydraulic circuit 272 may be provided between the harvest system 204 and the cultivation system 102, delivering the fluid, for example, filtered culture or flushing water, discharged from the harvest system 204 back to the cultivation system 102. [00060] Specifically, in this embodiment, at one end of the harvest hydraulic circuit 260, a discharge tube 254 is provided inside of the container 203 through the bottom of the container 203. The discharge tube 254 is used to discharge the suspension culture, when it is ready to harvest biomass, to the harvesting hydraulic circuit 260 which leads to the harvest system 204. The discharge tube 254 extends vertically so that its opening 254a is positioned at a height h3 (see FIG. 2B). In this embodiment, the height h3 is no less than half of the height hl of the container 203. The suspension culture to be harvested may then be drawn into the discharge tube 254 through the opening 254a and discharged into the harvesting hydraulic circuit 260 leading to the harvest system 204.

[00061] In addition, or optionally, a drainage opening 256 is provided on the bottom of the container 203 and connected to a valve 228. The valve 228 can be commanded to open or close, such as a solenoid valve. When the valve 228 is normally closed and may drain the culture when it is open. The drainage opening 256 thus is used to discharge the culture from the bottom of the container 203 and may be used when it is intended to completely drain the container 203. In this embodiment, the drainage opening 256 is in communication with the discharge hydraulic circuit 260 at the downstream of the valve 228. Therefore, the culture will be drained into the harvesting hydraulic circuit 260, go through the harvest system 204, discharged into the waste hydraulic circuit 270, and reach the waste tank 218. By this arrangement, biomass can also be harvested when the container 203 is drained, for example, to be cleaned, to avoid waste. In another embodiment, alternatively or additionally, the drainage opening 256 may also be connected directly to the waste tank 218 bypassing the harvest system 204.

[00062] FIG. 2B illustrates the harvesting hydraulic circuit 260 as a part of the hydraulic circuits shown in FIG.2A. As shown in FIG. 2B, the harvesting hydraulic circuit 260 delivers the suspension culture from the container 203 of the cultivation system 102 to the inlet 262 of the harvest system 204. Specifically, the discharge tube 254 is connected to the harvesting hydraulic circuit 260 through the normally closed valve 230. The valve 228 can be commanded to open, such as a solenoid valve. Downstream of the valve 230, a check valve 224 is provided allowing the flow of fluid away from the discharge tube 254 and preventing the fluid from flowing back to discharge tube 254. The harvesting hydraulic circuit 260 then goes through a pump 238 before arriving at the inlet 262 of the harvest system 204. Optionally, a flow meter 244 measuring the fluid flow rate may be provided in line of the harvesting hydraulic circuit 260. By this arrangement, when the control unit (not shown) send an ON signal to open the valve 230 and activates the pump 238, the suspension culture may be drawn from the opening 254a of the discharge tube 254 through the harvesting hydraulic circuit 260 to the inlet 262 of the harvest system 204. It should be noted that the order of the valve 230, check valve 224, flow meter 244, pump 238 in the harvesting hydraulic circuit 260 is exemplary and may be alternatively arranged if needed.

[00063] The harvest system 204 may then separate the biomass out of the suspension culture and discharge the waste fluid through the outlet 264 of the harvest system 204 to the waste hydraulic circuit 270. The harvest system 204 will be described in detail later.

[00064] FIG. 2C illustrates the waste hydraulic circuit 270 as a part of the hydraulic circuits shown in FIG. 2A. As shown in FIG. 2C, the outlet 264 of the harvest system 204 is connected to the waste hydraulic circuit 270. A check valve 222 is provided downstream of the outlet 264, allowing the flow of fluid away from the outlet 264 but prevent the flow of fluid back to the outlet 264. A pump 240 is provided downstream of the check valve 222. The waste hydraulic circuit 270 then split into two lines, one leading back to the container 203 of the cultivation system 102 through a solenoid valve 234 thus forms the recycle circuit 272, while the other leading to the waste tank 218 through a solenoid valve 232. Therefore, when the valve 234 is open, the fluid may be delivered back to the container 203; otherwise when the solenoid valve 232 is open, the fluid may be discharged to the waste tank 218. Therefore, the waste fluid discharged from the harvest system 204 may be delivered either back to the suspension culture in the container 203, or to the waster tank 218 depending on, for example, if the waster fluid is reusable or may be manually selected by the user.

[00065] As shown in FIG. 2A, a flushing hydraulic circuit 280 may be provided to deliver flushing fluid, such as water or other liquid solvent or detergent, from the flushing tank 216 to the inlet 262 of the harvest system 204. The flushing fluid will then run though substantively the same fluid path as the suspension culture does to flush and cleanse the flushing fluid path, that is, the fluid path from the inlet 262 through the harvest system 204 to the outlet 264, then into the waste hydraulic circuit 270 until the waste tank 218. Therefore, the fluid path, especially the related components in the harvest system 204 will be flushed and cleansed. Specifically, the flushing hydraulic circuit 280 starts from the flushing tank 216, and connects the flushing tank 216 to a solenoid valve 236 and a check valve 226, and then leads to the harvesting hydraulic circuit 260 at the upstream of the pump 244. The check valve 226 only allows the fluid flowing in the direction from the flushing tank 216 towards the waste tank 218 but prevent the fluid flowing in the opposite direction. Therefore, under the control of the control unit, when the solenoid valve 236 is open and the pump 224 is activated, the flushing fluid will then be delivered through the flushing fluid path until reaching the waste tank 218.

[00066] In this embodiment, the flushing hydraulic circuit 280 is connected directly to the inlet end of the pump 244 in the harvest hydraulic circuit 260, so that the pump 244 may be used to pump either the suspension culture or the flushing fluid. It thus may reduce the parts in the photobioreactor. In another embodiment, the flushing hydraulic circuit 280 may also be connected to the upstream of the check valve 224 or the solenoid valve 230 or 228 in the harvesting hydraulic circuit 260 as long as the connecting point of the flushing hydraulic circuit and the harvesting hydraulic circuit is upstream of the pump 244, thus the check valve 236 in the flushing hydraulic circuit 280 may be omitted too. In another embodiment, the flushing hydraulic circuit may also be connected directly to the inlet 262 of the harvest system 204. In this case, an additional pump will be required in the flushing hydraulic circuit.

[00067] As aforementioned, the valves 228, 230, 232, 234, and 236 are valves that switch between an open state and a closed state under control of the control unit through electric signals, and may be solenoid valves as an example. However, these valves can be actuated through pneumatic, hydraulic, electric actuators (such as, electromagnetic, piezoelectric) which is in turn controlled by the control unit.

[00068] It should be understood that the hydraulic and fluid circuits and their components are just an example and can be modified or omitted. For example, as long as suspension culture can be delivered from the cultivation system to the harvest system, either through a circuit with or without control unit or even manfully, the bioreactor may function. For example, the flushing hydraulic circuits may be omitted, and the harvest system may be cleansed manually by adding water or flushing agent solvent to the filtration container. The recycle circuit 272 may also be omitted. In addition, in this embodiment, some circuits, share components such as pumps, flow rate meters, check valves; for example, the flushing hydraulic circuit 280 shares the pump 238 and flow rate meter 244 with the harvest hydraulic circuit 260. However, they may also be configured independently and thus comprises their own specific components. In this case, the valve 236 may be omitted and the check valve 226 may function as a switch through the control of the hydraulic pressure by controlling the pump. Furthermore, the order of the components in a circuit may be interchanged, the selection of specific type of components may also be modified. For example, some valves may have built-in check mechanism to allow switch between open state and closed state and, when in open state, only allow a fluid flow in one direction. Therefore, some check valve and valve, for example, the valve 236 and the check valve 226 may be replaced with such valve.

[00069] Harvest system

[00070] Below, the structure and function of the harvest system 204 will be described in detail by referring to FIGS. 3A-3H and 4A-4C.

[00071 ] As shown in FIG. 3 A, the harvest system 204 comprises an inlet 262 through which the suspension culture is introduced to the harvest system 204, a filtration container 315, a removable filter screen 362 disposed within the filtration container 315, and a piston 321. The filtration container 315 is in fluid communication with the outlet 264 of the harvest system 204. The piston 321 is movable towards and away from the filtration container 315 between a retraction position in which the piston 321 is spaced from the filtration container 315 as indicated by the distance d in FIG. 3 A, and an extended position, in which the piston 321 extends into the filter screen 362 and thus the filtration container 315. In the extended position, the piston 321 is configured to press the biomass remained in the filter screen and squeeze excess fluid out of the filtration container 315. The harvest system 204 has a virtual center axis Cl that extends in the vertical direction. The filtration container 315 extends along a virtual longitudinal axis C2 that forms an acute angle cp with the center vertical axis Cl. The filtration container 315 is able to revolve around the center vertical axis Cl while tilting along the longitudinal axis C2 relative to the center vertical axis C 1 , thus the longitudinal axis C2 is also a virtual axis revolving together with the filtration container 315. The piston 321 is disposed along the longitudinal axis C3 that also forms an acute angle cp with the center vertical axis Cl, however, the piston 321 does not revolve around the longitudinal axis Cl but is configured to reciprocate linearly along the longitudinal axis C3, which is fixed. Therefore, the piston 321 titles relative to the vertical axis at the angle (p. In FIG, 3 A, the filtration container 315 is at the position that aligns with the piston 315. That is to say, the filtration container 315 can be moved to and stop at the position where the longitudinal axis C3 of the piston 321 aligns with the longitudinal axis C2 of the filtration container 315.

[00072] Filtration Container and Related Components

[00073] FIG. 3B illustrate a vertical cross section view of the harvest system 204 with the piston 321 and its supporting mechanism omitted. As shown in FIG. 3B, the harvest system 204 further comprises a chassis 326 (See FIG. 3A) including a base 327 and a frame 328, containing and supporting the components of the harvest system 204. A motor 330 is fixed to the frame 328, with the rotor 331 thereof fixedly connected with a drive pulley 332. The drive pulley 332 is further connected with a driven pulley 333 centered at the center vertical axis Cl through a belt 334. Therefore, the rotation of the rotor 331 of the motor 330 can be transmitted to the spindle 340 of the driven pulley 333. The motor 330 can be an electric motor and may be a stepping motor that divides a full rotation into a number of equal steps or a stepless motor.

[00074] The spindle 340 of the driven pulley 333 extends vertically with the center of the spindle 340 in alignment with the center vertical axis C 1. The lower portion of the spindle 340 forms the rotor of the driven pulley 333. The middle portion of the spindle 340 extends through a bore of the bracket 346 and is rotatably supported by a bracket 346 through an upper bearing 342 and a lower bearing 344. The upper portion of the spindle 340 extends beyond the bracket 346 and is enlarged in the diameter so as to be supported and stopped by bracket 346 in the vertical direction. The bracket 346 is further fixedly attached to the frame 328. Therefore, the spindle 340 is rotatable around the center vertical axis Cl but is not movable along the center vertical axis Cl. [00075] In addition, the filtration container 315 is pivotally connected to the spindle 340 at an eccentric location relative to the center vertical axis Cl of the spindle 340. Specifically, as shown in FIG. 3B, the filtration container 315 has a shape of truncated cone around the center axis C2. The filtration container 315 is supported by a shaft 366 that is elongated and extends along the center axis C2. The lower end 366b of the shaft 366 is attached to the upper end of the spindle 340 in a manner that the shaft 366 is able to pivot around two pivot pins that are perpendicular to each other. FIG. 3C illustrates a partial enlarged perspective view of the components in the circle 3C of FIG. 3B, specifically showing the pivot assembly 368 connecting the shaft 366 with the spindle 340. The pivot assembly 368 includes an intermediate plate 371 that is pivotably connected to each of the shaft 366 and spindle 340 around the respective perpendicular axes. Specifically, the spindle 340 comprises a flange 360 that protrudes upwards from the spindle 340. The flange 369 includes an opening 370 while the intermediate plate 371, at one end connected to the flange 369, has a through hole at one end (blocked by the flange 369 and thus not seen in FIG. 3C). A pivot pin 372 extends through the through hole in the intermediate lug 371 and is fixed to the opening 370 of the flange 369 so that the intermediate plate 371 is able to pivot around the pivot pin 372 relative to the spindle 340. The through hole 370 of the flange 369 is located at an eccentric position relative to the rotation center of the spindle 340, that is, the center vertical axis Cl. In addition, the intermediate plate 371, at the other end connected to the shaft 366, comprises two protrusions 371a and 371b that sandwich the lower end 366a of the shaft 366. The lower end 366a further comprises a through hole 374 (shown in dotted line), and a pivot pin 376 extends through the through hole 374 and is fixed to the protrusions 371a and 371b. Thus, the spindle 366 is able to pivot around the pivot pin 376 relative to the intermediate plate 371. The pivot pin 372 and pivot pin 374 are perpendicular to each other so that the shaft 366 is able to pivot relative to the spindle 340 in two directions that are perpendicular to each other though the pivot assembly 368. The pivot assembly 368 thus provides more degree of freedom in the movement of lower end 366a of the shaft 366 relative to the spindle 340, thus may accommodate the movement of the lower end 366a when it is revolving around the center vertical axis Cl at an eccentric position.

[00076] As shown in FIG. 3B, the shaft 366 is further supported by a cradle block 380, which is in turn supported by the frame 328, so that the shaft 366, together with the filtration container 315, is able to revolve around the center vertical axis Cl while tilting relative to the center vertical axis Cl . Below, the structure and movement of the cradle block 380 together with the shaft 366 and the filtration container 315 will be described by referring to FIGS. 3B, 3D, and 3E. Specifically, in this embodiment, the cradle block 380 is pivotable around a first horizontal axis X relative to the frame 328 of the harvest system 204, while the shaft 366, together with the filtration container 315, is pivotable around a second axis Y that is perpendicular to the first horizontal axis X, relative to the cradle block 380.

[00077] As shown in FIGS. 3B and 3D, a pair of bearing shafts 382 opposing to each other are fixedly attached to the frame 328, respectively, and extend along the horizontal axis X. The virtual extension of the bearing shafts 382, that is, the horizontal axis X intersects with the center vertical axis Cl at the origin O. The cradle block 380 is then supported through a pair of bearings 384, respectively, by the respective bearing shafts 382. Therefore, the cradle block 380 is able to pivot around the horizontal axis X relative to the frame 328. In another embodiment, the bearing shafts may be fixedly attached to the cradle block and supported by the frame through a pair of bearings. In another embodiment, other mechanisms that are able to achieve the pivoting movement of the cradle block may be employed, such as, ball screw, bearingless rotor, ball bearing, universal joint, among others.

[00078] In addition, as shown in FIGS. 3B and 3D, the cradle block 382 has a bore 386 that allows the shaft 366 to go through the cradle block 380. In this embodiment, cross section of the bore 386 is an elongated slot, so that it prevents potential hinder with the movement of the shaft 366 and the other components, and may also reduce the weight of the cradle block while keeping a sufficient strength. In another embodiment, the cross section of the bore may be of other shape, such as, round, oval, rectangular, and square, among others.

[00079] As shown in FIG. 3D, a pivot shaft 388 extends through a through hole 374 of the shaft 366 along an axis Y, and pivotably attached at the both ends to the cradle block 380. The axis Y is fixed relative to the cradle block 380 and is perpendicular to the horizontal axis X. The axis Y also intersects with the center vertical axis C 1 and the horizontal axis X at the origin O. Therefore, the axes X and Y form a moving coordinate system that is fixed relative to and moves along with and the cradle block 380. The pivot shaft 388 is supported by cradle block 380 through a pair of bearings 390, and the shaft 366 is fixed to the pivot shaft 388. Therefore, the pivot shaft 388, thus the shaft 366 is able to pivot around the axis Y relative to the cradle block 380. In another embodiment, the pivot shaft may be fixedly attached to the cradle block and pivotably attached to the shaft supporting the filtration container through a pair of bearings. In another embodiment, other mechanisms that are able to achieve the pivoting movement of the cradle block may be employed, such as, ball screw, bearingless rotor, ball bearing, universal joint, among others. In another embodiment, the pivot shaft may be fixed to the cradle block 380 while pivotably connected to the shaft 366 through, for example, bearing, universal joint, among others.

[00080] Therefore, the shaft 366 is able to pivot around both the axes X and Y that are perpendicular to each other with its portion at the origin O static relative to the frame 328. When the motor 330 is activated thus rotates the spindle 340, the lower end 366a of the shaft 366 also rotates around the center vertical axis along with the spindle 240. The upper end 366b of the shaft 366 also rotates around the center vertical axis Cl with the origin O as the fulcrum. Since the filtration container 315 is fixedly attached to the upper end 366b of shaft 366, the filtration container 315 thus revolves around the center vertical axis C 1 while tilting relative to the center vertical axis Cl at an angle cp along with the rotation of the spindle 340. The angle cp is determined by the eccentric distance, the distance between the pivot pin 372 and the center vertical axis Cl, and the distance between the pivot pin 372 and the origin O.

[00081 ] FIG. 3E illustrates a mechanical transmission diagram showing the power transmission from the driven pulley 333 to the shaft 366. In FIG. 3E, components are simplified, for example, the cradle block 380 is simplified as a plane extending along the axes X and Y, the spindle 340 and shaft 366 are simplified as solid lines, and the frame 328 is shown by shadow lines. As shown in FIG. 3E, the rotation of the driven pulley 333 around the center vertical axis Cl is transmitted to the rotation of the spindle 340 around the center vertical axis Cl. The shaft 366, extending along the axis C2 that tilts relative to the center vertical axis Cl, is pivotably connected to the spindle 340 through the intermediate plate 371, that is, the pivot assembly 368 at an eccentric location from the center vertical axis Cl. Note, in order to accommodate the eccentric revolving movement of the shaft 366 due to it is practically not a line but occupies a space, the pivot assembly 368 (the intermediate plate 371) allows the shaft 366a pivots around two axes. In addition, the shaft 366 is supported by the cradle block 380 at the location O in a manner that the shaft 366 is pivotable around the axis Y through the bearings 390, and the cradle block 380 is further supported by the frame 328 in a manner that the cradle block 380 is pivotable around the axis X through the bearings 384. Therefore, when the spindle 340 rotates around the center vertical axis Cl along with the rotation of the driven pulley 333, the shaft 366 revolves around the center vertical axis while tilting relative to the center vertical axis. Thus, the filtration container 315 supported by the shaft 366 also revolves around the center vertical axis while tilting relative to the center vertical axis.

[00082] The tilting and revolving movement of the filtration container may greatly expediate the filter of the suspension culture to separate the biomass. It could be understood by those skilled in the art that other mechanisms may be employed to achieve the tilting and revolving movement of the filtration container. For example, a wobbling pin gear may be employed instead of the transmission mechanism from the driven pulley to the shaft. Known mechanism to agitate or stir a flask in the art may also be employed. In addition, the present invention is also intended to cover changes may be made to the embodiment shown in FIGS. 3A-3E. For example, the transmission from the motor to driven pulley may be substituted with gear transmission, chain transmission, instead of belt transmission. In another embodiment, the motor may be configured to drive the spindle directly instead of through a transmission mechanism. The number, type, and rotation center of the components, such as, the pulley, spindle, shaft, and pivot assembly may be adjusted and changed according to a specific application in order to achieve the tilting and revolving movement of the filtration container.

[00083] As shown in FIGS. 3A and 3B, a filter screen 362 is disposed within the filtration container 315. The filter screen 362 also has a shape of truncated cone, that is similar to but smaller than the filtration container 315, so that when the filter screen 362 is attached inside the filtration container 315, there is a space between the outer wall of the filter screen 362 and the inner wall of the filtration container 315. The filter screen 362 comprises a plurality of fine perforations 365 on the side wall and bottom wall like a mesh, so as to filter the liquid while keeping the biomass in the filter screen. The size of the perforations 365 may be decided based on the species of the biomass that is grown in the suspension culture, more specifically, the size, shape, and coiling or intertwining status of the biomass cells. The size of the perforations 365 shall be smaller enough to prevent most of the biomass from passing through but also big enough to accelerate the filtration. For example, for spirulina, which is usually in a shape of coils of spiral cells, the diameter of the perforations may be in the range of 30-60 microns. When the filtered culture is introduced back to the cultivation system, this also enables collecting the fresh biomass while leaving some of the spirulina cells in the culture to reproduce after the harvest is complete. In one embodiment, the diameter of the perforations 365 may be in the rage of 10-100 microns, preferably 20-80 microns, more preferably 30-60 microns. Optionally, a protrusion 364 may be provided in the center of the bottom wall of the filter screen 362. The protrusion 364 may be a dome-like shape. The protrusion 364 may prevent condensation of the biomass in the middle of the filter screen.

[00084] The filter screen 362 is removably attached in the filtration container 315. Therefore, when the filtration is finished, the filter screen 362 may be removed from the filtration container 315 and thus the harvest system 204, the biomass in the filter screen 362 may then be collected. The filter screen 362 then may also be cleaned separately. Depending on the wear degree of the filter screen and the blockage degree of its perforations, the filter screen can also be substituted with a new one.

[00085] The inner space of the filtration container 315 is in communication with the outlet 264 of the harvest system 204. In the embodiment shown in FIG. 3B, the upper end 366b of the shaft 366, that is attached to the bottom of the filtration container 315, is bored with a sink hole 367. The sink hole 367 communicates the inner space of the filtration container 315 to the outlet 264, thus the liquid filtered out of the filter screen 362 may be drained through the sink hole 367 to the outlet 264. In another embodiment, the outlet 264 may be provided directly in the bottom of the filtration container 315 and communicated with the inner space of the filtration container 315.

[00086] Piston and Related Components

[00087] Referring to FIGS. 3A, 3F, and 3G, the harvest system 204 further comprises a piston 321 and an actuator 314. As aforementioned, the piston 321 is able to move between an extended position in which the piston 321 extends into the filtration container 315 and a retraction position in which the piston 321 is spaced from the filtration container 315. Therefore, the piston 321 is used to press the biomass in the filter screen 362 to squeeze remaining liquid out of filter screen, and thus further accelerate the filtration. The piston 321 has a similar shape of frustum cone as the filter screen 362. The piston 321 is smaller than the inner space of the filter screen 362, so that the piston 321 is able to extend into the inner space of the filter screen 362. The piston 321 is also configured to be big enough to press the biomass in the filter screen 362 to squeeze excess fluid out of the filter screen 362. [00088] As shown in FIG. 3A, the actuator 314 comprises a roller screw 318 and a motor 316 as the actuator of the roller screw 318. When the motor 316 is activated, the roller of the roller screw 318 is able to reciprocate linearly along the longitudinal axis C3 which forms the same angle cp with the center vertical axis C 1 as the longitudinal axis C2 of the filtration container 315 does. As shown in FIG. 3F, the roller screw 318 comprises a threaded roller 351 and a screw 353. The screw 353 has a threaded hole 354 that is in threaded connection with the roller 351. The roller 351 is fixedly attached to the rotor 352 of the motor 316, and the screw 353 is fixedly attached to the piston axle 322 of the piston 321. Therefore, when the motor 316 is activated and rotates its rotor 352 and thus the roller 351 in one direction, the screw 353 moves downwards along the longitudinal axis C3 and thus moves the piston 321 towards the filtration container 315; when the motor 316 rotates its rotor and thus the roller 351 in the opposite direction, the screw 353 moves upwards along the longitudinal axis C3 and thus moves the piston 321 away from the filtration container 315. The roller screw together with the motor is an example of the mechanism to allow the piston to reciprocate back and forth. In another embodiment, other mechanism may be employed to achieve the reciprocated movement of the piston, such as ball screw, cylinder piston mechanism, crank and slider mechanism, eccentric gear mechanism, Maltese mechanism, cam mechanism, among others.

[00089] In another embodiment, the piston 321 may be further configured to stop at a plurality steps of extended positions, for example, 2-5 extended positions. At the respective extended positions, the piston 321 is at different distance from the bottom of the filter screen 362. This can be achieved by configure the actuator 314 to stop when the piston 321 reaches the respective extended positions. For example, when the actuator 314 comprises with the motor 316 and the roller screw 318, the rotation of the motor 316 may stop at predetermined intervals, under the control of the control unit (not show). In this case, the revolving of the filtration container and the pressing of the piston may be performed alternately for a plurality of times. For example, when the revolving of the filtration container and thus the filtration has performed for a predetermined time, the revolving is stopped, and the piston may move to the first extended position that is the farthest from the bottom of the filter screen to compress the biomass and the suspension culture remained in the filter screen. Then the piston moves back to the retracted position, and moves to the next extended position that is closer to the bottom of the filter screen after the filtration container is revolved and stopped again. The process keeps going until the filtration is completed.

[00090] In this embodiment, the inlet 262 of the harvest system 204 that allows suspension culture or other fluids such as flushing fluid to be drawn into the harvest system 204 is provided onto the piston 321. FIG. 3G illustrates the state in which the piston 321 is spaced from the filtration container 315 and the suspension culture is introduced to the harvest system 204. Note in this state, referring to FIG.2A, the solenoid 230 for the harvest hydraulic circuit is open so that the suspension culture may be introduced to the inlet 264 and the solenoid valve 232 or 234 is also open so that the filtered culture may be introduce back to the cultivation container 203 or the waste tank 218. As shown in FIG. 3G, the piston 321 comprises a center passage 354 along the longitudinal axis C3 that opens at the bottom of the piston 321 facing the filtration container 315, and extend to the piston axle 322. The inlet 262 is provided to the piston axle 322 and is in communication with the center passage 354. Therefore, as shown by the arrows in FIG. 3F, the fluid may go into the center passage 354 through the inlet 262, flow into and get filtered by the filter screen 362, then flow through the space between the filter screen 362 and the sink hole 367 before reaching the outlet 264. In another embodiment, the inlet 262 may be provided on other portions of the piston 321 and is in communication with the center passage 354. In another embodiment, the inlet 262 may be provided separately from the piston. For example, the inlet 262 may be provided above the opening of the filtration container. In this case, the center passage in the piston may be omitted.

[00091] FIG. 3H illustrates the state in which the piston 321 is moved into the filter screen 362 at the extended position and pressing the biomass in the filter screen 362. Note in this state, referring to FIG. 2 A, the solenoid 230 for the harvesting hydraulic circuit is closed so that the suspension culture does not flow to the inlet 264 and the solenoid valve 232 or 234 is open so that the remaining fluid that is squeezed out of the biomass may be introduce back to the cultivation container 203 or the waste tank 218. As shown in FIG. 3H, the piston 321 is fitted into the filter screen 362 with a gap t between the bottom of the piston 321 and the bottom wall of the filter screen 362. The biomass 356 in the gap is thus being pressed and excess fluid may be squeezed out of the filter screen 362. The gap t may be adjusted by adjusting the stoke of the roller screw 314. As shown in FIG. 3H, the center passage 354 in the piston 321 include a dilated section 355 at the opening of the bore 354, so that the protrusion 364 on the center of the filter screen 362 will be contained into the dilated section 355 without hindering the pressing of the piston 321 onto the biomass. In another embodiment, the diameter of the center passage is greater than the diameter of the protrusion, thus the dilated section is not necessary. After being pressed to remove the excess fluid, the filter screen 362 may be removed from the filtration container 315, and the biomass left in the filter screen 362 can be collected. The harvesting of the biomass is thus finished.

[00092] FIGS. 4A-4C illustrate the partial views of the harvest system 204 during the flushing process. FIG. 4A illustrate the state when the flushing process is started. The piston 321 has moved back to the retracted position to be spaced from the filtration container 315 after pressing the biomass. As shown in FIG.4A, some of biomass 356 is remained on the piston 321 . In addition, some perforations on the filter screen 362 may be blocked by biomass or other impurities. Therefore, referring to FIG. 2A, the solenoid valve 236 in the flushing hydraulic circuit 280 is open and the solenoid valves 232 and 234 are closed, so that the flushing fluid (for example, water) may be introduced to the filtration container 315 from the flushing tank 216 through the inlet 262 and stay in the filtration container 315, as indicated by the arrows in FIG. 4 A.

[00093] Next, as shown in FIG. 4B, when a predetermined amount of flushing fluid has been introduced into the filtration container 315, the solenoid valve 236 in the flushing hydraulic circuit 280 (see FIG. 2A) is closed while the solenoid valves 232 and 234 in the waste hydraulic circuit 270 are kept closed. The motor 316 is activated and drives the piston 321 through the roller screw 318 until the piston 321 reaches the extended position and is fitted into the filter screen 362 of the filtration container 315, as shown by Arrow 402. Since there are flushing fluid in the filtration container 315, the piston 321 is soaked at least partially in the flushing fluid and is thus cleaned. The biomass attached to the piston, if any, will also be flushed into the flushing fluid.

[00094] Next, as shown in FIG. 4C, the motor 316 is activated again and drive the piston 321 through the roller screw 318 back to the retracted position in which the piston 312 is spaced from the filtration container 315. The solenoid 232 or 234 is opened depending on if the flushing fluid is intended to circle back from the outlet 264 to the cultivation container 203 for recycled use or to the waste tank 218 to be disposed. In this state, optionally, the motor 330 may be activated to make the filtration container 315 revolve, to facilitate cleaning of the filter screen 362 and the filtration container 315 while accelerate the flushing fluid to drain. [00095] In addition, the flushing process as shown in FIG. 4A-4C may also be performed when the filter screen 362 is removed from the filtration container 315.

[00096] Alignment between Piston and Filtration Container

[00097] When the filtration container 315 is pressed by the piston 321, the filtration container 315 is required to revolve and stay in the position where the longitudinal axis C2 of the filtration container 315 matches with the longitudinal axis C3 of the piston 321, so that the piston 321 and the filtration container 315 are aligned with each other. To achieve the alignment of the filtration container 315 with the piston 321, a position sensor 395 (see FIG. 3B) may be provided to the harvest system 204 to detect the rotation position of the filtration container 315. In FIG. 3B, the position sensor 395 is provided onto the spindle 340. The position sensor 395 may be an angular sensor, revolve speed sensor, acceleration sensor, gyroscope that may detect directly or indirectly the rotation angle of the spindle.

The position sensor 395 may also be other sensors such as a magnetic sensor, an ultrasonic sensor, or optical or laser sensor that may detect every time when the detected object passes by a predetermined location. For example, a laser emitter may be provided on the frame 328 or the piston 321 emitting a laser towards the spindle or the filtration container , a laser sensor may be provided on the spindle at the location when the filtration container 315 aligned with the piston 321. Therefore, when the spindle 340 and the filtration container 315 rotates to a position where the laser sensor detects the laser, the filtration container 315 is at a position in alignment with the piston 321.

[00098] The position sensor may be provided on other components that drives or moves along with the filtration container, such as, the rotor of the motor 330 that drives the filtration container 315, the drive pulley or the driven pulley between the motor 330 and the spindle 340, the shaft 366 that supports the filtration container, or the filtration container itself.

[00099] The position sensor is also connected to and is readable by the control unit (not shown), the structure of which will be described later.

[000100] The alignment between the filtration container 315 and the piston 321 may be achieved by mechanical devices. For example, a stopping mechanism may be provided and activated to stop the filtration container at a specific position when the alignment between the filtration container and the piston is needed. In another embodiment, the piston may revolve in synchronization with the filtration container so that the piston is always in alignment with the filtration container. In this case, the piston and the filtration container may be driven to revolve by respective motors or the same motor.

[000101] Cultivation System

[000102] Below, the structure and function of the cultivation system 102 will be described in detail by referring to FIGS. 5A-8D. The cultivation system 102 is an embodiment of the cultivation system according to the present invention.

[000103] FIGS. 5A and 5B illustrate a perspective view of the container 203 of the cultivation system 102 and a cross section view of the container 203 taken along the plane 5B-5B in FIG. 5A, respectively. As shown in FIGS. 5A and 5B, the container 203 comprises an outer cylinder 502, a base plate 504, and a top wall 512. The outer cylinder 502 is hermetically sealed onto the base plate 504. An inner cylinder 506 is provided inside the outer cylinder 502 and is also hermetically sealed onto the base plate 504. In this embodiment, the outer cylinder 504 and inner cylinder 506 both have a round cross section and are concentrically disposed and attached onto the base plate 504. The biomass or microorganisms is intended to grow within the space between the outer cylinder 504 and inner cylinder 506. A light source 210 is provided in the inner cylinder 506 of the container 203 and extends along the vertical direction, providing lights needed for growing the phototrophic microorganisms. The outer cylinder 502 and the inner cylinder 506 are transparent or translucent, and may be made of materials such as glass, or polymer.

Therefore, both the light emitted from the light source 210 and ambient light may enter the inner space between the outer cylinder 502 and the inner cylinder 506 and provide lighting necessary for the biomass to grow. In this embodiment, the top wall 510 of the container 203 is opaque. However, in another embodiment, the top wall 510 may be transparent or translucent. The light source 210 may comprise one or more light sources that emits lights in the visible or invisible spectrum, for example, a light emitting diode (LED) light source, incandescent lamp, and fluorescent lamp. For example, the light source 210 comprises a light source in the visible spectrum 210a, which may be one emitting white light or colored light, or may be color adjustable, and may further be color temperature adjustable or brightness adjustable, according to the species of the biomass, growth condition, and aesthetical design requirement. In addition, the light source 210 may further comprise an ultraviolet (UV) source 210b, e.g., UVC (200 to 280 nm) lamp or LED, that emits ultraviolet light that may be used to disinfect the container 203 and the culture therein prior to addition of starting culture. [000104] In another embodiment, the inner cylinder 506 may be arranged eccentric with the outer cylinder 502. In addition, the cross section of the inner cylinder or the outer cylinder may be of other shape, such as, oval, rounded rectangle, square, rectangle, polygon, among others. In addition, in another embodiment, the inner cylinder 506 may be omitted, and the light source and other components may be provided at other locations, such as, the top wall or bottom wall of the container, and the inner or outer side of the outer cylinder, etc.

[000105] A discharge tube 254 is provided inside of the container 203, specifically, the biomass growing space between the outer cylinder 502 and the inner cylinder 506. As aforementioned, the discharge tube 254 extends through the bottom of the container 203, that is, the base plate 504 and is in communication with the harvesting hydraulic circuit 260 (see FIG. 2A). The discharge tube 254 is used to discharge the suspension culture, when it is ready for harvesting biomass, to the harvesting hydraulic circuit 260 which leads to the harvest system 204. The discharge tube 254 extends vertically so that its opening 254a is positioned at a height h3 (see FIG. 2B). In this embodiment, the height h3 is no less than half of the height hl of the container 203. In other embodiment, the height h3 may be at a different height and determined based on the species of the biomass and the hydraulic design of the hydraulic circuits. It is typically desirable to place the discharge tube 254 and its opening 254a above the base plate 504. The suspension culture to be harvested may then be drawn into the discharge tube 254 through the opening 254a and discharged into the harvesting hydraulic circuit 260 leading to the harvest system 204. A cover 254b that is larger than the opening 254a is supported above the opening 254a. The cover 254b may prevent biomass and other precipitations from entering the discharge tube 254 unintendedly when the suspension culture is not drawn to the harvest system 204.

[000106] In the bottom wall of the container 203, that is, the base plate 504, a drainage opening 256 is provided. As aforementioned and shown in FIG. 2A, the drainage opening is connected to the solenoid valve 228 and is used to drain the container 203. In addition, a plurality of injectors 250 are provided on the bottom wall, that is, the base plate 504 as a component of the airlift agitation mechanism for agitating the suspension culture, which will be described in detail later.

[000107] On the top wall 512 of the container 203, a degassing opening 248a is provided for the degassing outlet 248. As shown in FIG. 5B, the degassing outlet 248 is formed by a sleeve inserted in the degassing opening 248a. The degassing outlet 248 is used to release extra gases from the container 203, for example, gases generated by the biomass (usually oxygen), and gases released from the injector(s) 250. In addition, the degassing outlet 248 may comprise a filter (not shown) covering its opening to prevent foreign matters from entering the container 203. In another embodiment, the degassing opening 248 and thus the degassing outlet 248 may be provided on other locations of the container, such as, upper end of the outer cylinder 506.

[000108] The top wall 512 is additionally provided with an opening 206 for introducing substances when needed, such as, water, starter culture, sterile agent, nutrients, etc. The opening 206 is communicated to the input mechanism 610 that is accommodated in the housing, for example, the input compartment 101a as shown in FIG.l.

[000109] Input Mechanism

[000110] FIG. 6 illustrates a cross section view of the input mechanism 600 of the cultivation system 102. The input mechanism 600 is accommodated in the input compartment 101a of the housing 101 (see FIG.l) that is on top of the cultivation system 102. As shown in FIG. 6, the input mechanism 600 comprises a first inlet 612 and a second inlet 614. As shown in FIG. 6, the first inlet 612 comprises an opening 604 in the bottom wall 602 of the input compartment 101a and a pin 606 that is positioned in the opening 604 and is supported by the bottom wall 602. The top end of the pin 606 extends beyond the bottom wall 602 and is shaped to be sharp. In addition, the first inlet 612 is in communication with the opening 206 of the container 203 through, for example, a conduit. Therefore, as shown by the dotted line 622, a container or bottle 622 may be positioned to have its opening aligned with the first inlet 612, the pin 606 will then piece through the cover of the container 622 or push the cover into the container 622, the liquid in the container 622 will then be introduced into the container 203 through the first inlet 612. The first inlet 612 may be generally used to introduce any kind of liquid that is needed to the container 203. For example, at the beginning to use the photobioreactor, a bottle of starter suspension culture with the microorganisms may be introduced this way. The amount of the starter microorganisms can thus be controlled by the volume of the container. Other liquid, such as, water, sterile agent, and nutrients may be introduced through the first inlet 612. However, in this embodiment, the second inlet 614 is utilized to introduce nutrients that are required for the growth of the microorganisms in the container 203. Specifically, the second inlet 614 is formed by a protrusion 608 on the bottom wall 602. The top end of the protrusion 608 is also shaped to be sharp. The protrusion 608 is hollow and the inner space of the protrusion 608 is in communication with the opening 203 through, for example, a conduit, with a metering pump 616 provided midway. A replaceable nutrient cartridge 630 may be removably attached into the input compartment 101a. The nutrient cartridge 630 contains a predetermined amount of nutrient liquid which is a solution of the nutrients that is optimized for the species of the microorganism. When the nutrient cartridge 630 is attached in position, the protrusion 608 pieces the nutrient cartridge 630 and thus communicates the inner space of the nutrient cartridge 630 with the container 203. When the metering pump 616 is activated, the nutrient liquid will then be drawn into the container 203. The metering pump 616 may also be used to control the volume of the nutrient liquid that is being added to the culture in the container 203. Typically, nutrient liquid is added at the beginning of a suspension culture or after harvesting of biomass from an established culture.

[00011 1] The nutrient liquid usually may comprise compounds for providing nutrients needed for the growth of microorganisms, agents for adjusting pH value, and solvents such as water, among others, depending on the species of the microorganisms. For example, a nutrient liquid for spirulina may comprise sodium bicarbonate (Nat ICO i), potassium phosphate (K2HPO4), sodium nitrate (NaNCh), potassium sulphate (K2SO4), sodium chloride (NaCl), magnesium sulfate (MgSCU), EDTA, calcium chloride (CaCh), iron(II) sulphate (FeSCh), boric acid (H3BO4), manganese chloride (MnCh), zinc sulfate (ZnSCU), etc. Therefore, not only does the design of the nutrient cartridge make it easy to control the amount of the nutrients to add into the culture, it also simplifies the process by replacing the cartridge with a new one when the cartridge is exhausted or when the species of the microorganism is changed.

[000112] Airlift Agitation Mechanism

[000113] Below, the airlift agitation mechanism 700 will be described in detail by referring to FIGS. 2A, 5A, and 7A-7C. The airlift agitation mechanism 700 is used to agitate the culture in the container 203, to prevent the microorganisms, thus the biomass, to gather in the bottom of the container 203 due to the gravity. In addition, in this embodiment, the airlift agitation mechanism 700 achieves the agitation by ejecting a gas, for example, air, into the container 203. Therefore, the airlift agitation mechanism 700 may further increase the solubility of the gas in the culture, so as to increase the concentration of air, carbon dioxide, oxygen, or other content in the culture. The airlift agitation mechanism 700 thus may ensure the quality of biomass and improve the production yield of the bioreactor.

[000114] As schematically shown in FIG. 2A, the airlift agitation mechanism 700 comprises a gas source 246 and a plurality of injector 250 that is in communication with the gas source 246. The gas source 246 supplies a gas, for example, air to the injectors 250. In another embodiment, the gas may be selected from nitrogen, carbon dioxide, oxygen, or any combination thereof, among others. A check valve 220 is provided midway to prevent fluid, such as, culture and air, from flowing back towards the gas source 246. The gas source 246 and the gas circuit including the check valve 220 may be contained in the housing, for example, the housing 101 as shown in FIG. 1.

[000115] The gas source 246 may be chosen from the group of air compressor, air pump, a compressed air tank, or a tank that stores other types of compressed gas, such as, nitrogen, carbon dioxide, oxygen, or combination thereof. In this embodiment, the gas source 246 is an air compressor that, when activated, compresses and supplies air to the injectors 250.

[000116] The number of the injectors 250 is not limited, and may be two, three, or more. In this embodiment, three injectors 250 are arranged on a round circle around the center of the bottom wall of the container 203. However, more or less injectors 250 may be distributed, and the injectors 250 may be distributed in other arrangements if needed. FIG. 7A-7C illustrate the distribution and structure of the injectors 250 according to one embodiment of the present invention. In addition to agitate the suspension culture, the design of the injectors according to the present embodiment may also prevent bio film from growing on the surfaces of the container. Thus, the quality of biomass is ensured, and the production yield of the bioreactor is greatly improved.

[000117] FIG. 7A illustrates a top view of the bottom of the container 230 according to one embodiment of the present invention. As shown in FIG. 7A, three injectors 250 are distributed evenly along a circle as indicated by the dotted line 702 on the bottom of the container 230, that is, the base plate 504.

[000118] FIG. 7B illustrates a side view of an injector 250 viewed in the radial direction R in FIG. 7A. FIG. 7C illustrates a front view of the injector 250. As shown in FIG. 7C, the distal end 250c of the injector 250 has a width “L.” The injector 250, at the distal end 250c, includes at least one nozzle 710 from which the gas is ejected. In this embodiment, five nozzles 710 are arranged in a row. However, more or less nozzles may be provided, and they may be distributed in more than one rows or in any other arrangement. The nozzles 710 are configured to eject the gas along the direction 704 so as to agitate the culture.

[000119] As shown in FIG. 7B, the gas is ejected in the ejection direction 704 that forms an acute angle a with the horizontal plane 706 so that the ejection direction tilts upward. The angle a is in a range of 20-70 degrees, and may also be in a range of 25-65 degrees, 30-60, or 35-55 degrees. In another embodiment, the angle a may be determined otherwise based on the application of the bioreactor. The injector 250 includes a first section 250a that extends along the vertical direction, followed with a second section 250b that extends along a direction that tilts upwards. In another embodiment, the injector 250 may also be formed in another shape, for example, a consecutive curve. In the top view of the FIG. 7A, the injector 250 is arranged so that the ejection direction 704 is substantively along the same circumferential direction, that is, counterclockwise direction. Specifically, in the top view, the ejection direction 704 forms an angle P with the radial direction R, and the angle is around 90 degrees. In another embodiment, the angle P may be in a range from 70-110 degrees, 75-105 degrees, 80-100 degrees, and 85-95 degrees, and so on. In addition, the ejection direction 704 of each of the three injectors 250 is directed in the same circumferential direction, that is, counterclockwise direction in FIG. 7A. In another embodiment, the ejection direction 704 may also be directed in clockwise direction. Therefore, the injectors 250 eject the gas in a direction that tilts upwards and in the same circumferential direction. Therefore, the bubbles generated by the ejected gas will stir the culture in the circumferential direction (counterclockwise or clockwise) while pushing the microorganisms in the culture upwards when moving upwards due to buoyancy.

Therefore, the microorganisms will be distributed more evenly in the suspension culture. [000120] The injectors may be provided in other arrangements. FIGS. 8A-8D illustrate the arrangement and structure of the injectors according to other embodiments of the present invention. As shown in FIG. 8 A, eight injectors are arranged, in which a first group of four injectors 810a are distributed along a large circle while the remaining group of four injectors 810b are distributed along a smaller circle. In addition, the injectors 810a and injectors 810b between two groups are staggered in the circumferential direction. This arrangement may be employed for a relatively large container. In another embodiment, there may be more groups of injectors. The number of injectors of each group may differ from each other. The injectors between adjacent groups do not have to be staggered and may be aligned in the radial direction.

[000121 ] In addition, the injectors may be configured to be directed at opposite directions in the circumferential direction. For example, as shown in FIG. 8B, a part of the injectors, that is, injectors 820a, are directed to and thus eject gas in a clockwise direction while the other part of the injectors, that is, injectors 820b, are directed to and thus eject gas in a counterclockwise direction. A switch or pneumatic valve (not shown) may be provided in the circuit from the gas source to the injectors. Therefore, the first group of the injectors 820a and the second group of the injectors 820b may be turned on alternatively or if needed, so that the culture may be stirred in either of the clockwise and counterclockwise direction. As shown in FIG. 8B, all the injectors 820a and 820b are arranged along the same circle. However, the injectors may be distributed along a plurality of circles as those in FIG. 8A.

[000122] FIG. 8C illustrates injectors 830 that are distributed along an oval circle. This arrangement is particular useful for a container with an oval, rectangular, or rounded rectangular cross section. In this case, the ejection direction of each injector may form a different angle relative to the radial direction, which, for example, may be in a wider range, such as, 80-100 degrees, 75-105 degrees, 70-110 degrees, or 60-120 degrees. The injectors may be distributed along a circle of other shapes, such as, round, oval, square, rectangle, triangle, rounded rectangle, polygon, depending on the form factor of the container and its components and other requirement of the photobioreactor.

[000123] FIG. 8D illustrates an injector according to another embodiment of the present invention. The injector 840 is configured to be able to eject the gas optionally in two substantially opposed directions. Specifically, the injector 840 splits into a first section 842 including a first group of nozzles that eject gas in one circumferential direction and a second section 844 a second group of nozzles that eject gas in the other circumferential direction. A switch may be provided to switch the gas supply from the gas source to one of the two groups of the nozzles. For example, as shown in FIG. 8D, the injector includes a third section 846 that tilts upwards but is directed to a substantively opposed direction projected in a horizontal plane to the second section. Therefore, each injector is switchable in ejecting gas between two substantially opposed circumferential directions. Therefore, the culture may also be stirred in two opposed directions optionally. [000124] As aforementioned, the airlift agitation mechanism ejects gas so as to agitate the suspension culture to distribute microorganisms more evenly in the suspension culture and prevent the microorganisms from gathering in the bottom of the container. In addition, the flow of the gas and the culture also prevents biofilm from growing or staying on the surface of the container. Therefore, the airlift agitation mechanism may ensure the quality of the biomass and improve the production yield of the biomass. The airlift agitation mechanism may also be adjusted to achieve optimum results. The width L of the distal end 250C, the number, arrangement, and diameter of the at least one nozzle 710, the ejection direction 704 (that is, the angles a and |3), and the number and arrangement of the injector may be determined based on the application of the bioreactor, taking into account factors, such as, size, aspect ratio, and shape of the container, and species of the microorganisms, among others.

[000125] Other Components

[000126] Optionally or in addition, the photobioreactor may comprise other components.

[000127] For example, a transmittance sensor or optical density sensor may be provided in the cultivation system 102, for example, in the outer cylinder 502, in the inner cylinder 506, under the top wall 512, etc. The transmittance sensor detects the transmittance of the suspension culture, which may reflect the mature degree of the suspension culture and help decide if the suspension culture is ready for harvest.

[000128] In addition, other sensors for detecting the status of the culture may be provided, such as, a level sensor for detecting the liquid level of the culture in the container, a thermometer for detecting the temperature of the culture, a pH sensor for detecting pH value of the culture, etc. A heater, a cooler, or a thermostat may be provided for adjusting the temperature of the culture.

[000129] It should be noted that the photobioreactor may run without these additional components. The cultivation system and the harvest system may be manually controlled. Alternatively, when the starter microorganisms, water, and nutrients to be added to the photobioreactor are timed and metered, and the photobioreactor is placed in environment with substantively constant temperature, the cultivation system and the harvest system may each run at a predetermined timing.

[000130] Control Unit [000131] As aforementioned, a control unit is provided to control the components in the photobioreactor, which may automatically control or facilitate the manual control of the running of the photobioreactor. FIG. 9 illustrates an exemplary structure of a control unit 900 according to one embodiment of the present invention. The control unit 900 is an electronic control unit (ECU) comprising at least one processor 910, memory 920 coupled to the at least one processor 910, and I/O interface 940 for connecting I/O devices with the ECU 900, and the memory comprises computer executable instructions 930 that, when executed by the at least one processor 910, performs the method required to control the related components in the photobioreactor and run routines required to cultivate and harvest the biomass.

[000132] Through I/O interface 940, ECU 900 further electrically connects to and controls or receives or send signal from or to the components in the photobioreactor, such as the hydraulic circuits 260, 270, 280 etc., the airlift agitation mechanism 700, the light source 210, any sensors that are provided. Specifically, the ECU 900 connects to and controls the running or turns on/off of the valves, pumps, metering pumps, among others, in the hydraulic circuits as described. The ECU 900 also connects to the gas source 246, valves, switches in the airlift agitation mechanism 700, the light source 210, optional heater, optional thermostat, in the cultivation system 102. In addition, ECU 900 also receives or sends signals from and to any sensors provided in the photobioreactor, such as, the position sensor 395 for detecting the angular position of the filtration container, and other optional sensors such as thermometer, pH sensor, level sensor, among others.

[000133] Optionally, ECU 900 may further connect to the communication module 950, a clock 950, and other I/O devices 970 through the I/O interface 940. ECU 900 may read time and/or date information from the clock 950 and use it to control the running of the photobioreactor. The communication module 950 may enable ECU 900 to communicate and exchange information with external devices (such as, computer, server, smart phone, tablet), and may comprise modules such as Wi-Fi, Bluetooth, ethemet, telecommunication module, among others. In another embodiment, some of the external module may be embedded in the ECU 900, such as, the clock 960, communication module 950.

[000134] Optionally, ECU 900 may further connect to other devices such as additional storage to save the data, a display for displaying data and information, a speak for playing sounds to inform user about the status of the culture or the bioreactor, input devices such as keypad, keyboard, and mouse, and a touch screen for both inputting and outputting information. In another embodiment, ECU 900 may also connect to a user’s device (computer, smart phone, or tablet) through the communication module and use the user’s device as an I/O device. Alternatively, ECU 900 may also send and receive data to and from a server through the communication module, and a user may retrieve data from and send information and instruction to ECU 900 through the server on the user’s device. ECU 900 may thus prompt the user with information, such as,

[000135] A specific example of the ECU 900 microcontroller is shown on FIG. 10, where other components of the system is connected to and communicate with the ECU 900 via General Purpose Input/Output (GPIO), Analog-to-Digital Converter (ADC), Universal asynchronous Receiver/Transmitter (UART), and Pulse Width Modulation (PWM) interfaces. The ECU 900 via its GPIO interfaces connects to and controls through respective relays water and fluid pumps 238 240 242 228 and 230, solenoid valves 232 234 236 and 246, air pump 246, visible light source (white LED 210a), and UV light source (UV LED 210b). Sensors, such as temperature sensor (thermostat) 1121, and flow meter 244, also communicate with the ECU 900 microcontroller via GPIO. Other sensors, such as pH Meter sensor 1123 optical density sensor 1124, and Oxygen concentration sensor 1125 communicate with the ECU 900 microcontroller via the ADC interface.

Motors 316 and 330 are controller by motor controllers 1131 1133 (e.g., TMC2022 modules) which receives control inputs from the PWM interface of the ECU 900. The ECU 900 microcontroller is also connected to a wireless communication module, e.g., Wifi and/or LTE module 1170. The wireless communication module 1170 enables the ECU 900 to communicate with web service and remote users. Touch screen display 1190 is also connected to the ECU 900, which provides a control interface of the system, and also can display the operational status of the system. Electrical power is typical supply by AC to DC power supply converts mains power (110/200V AC) to DC, and a DC power supply (12 and/or 5 V) to the various components as needed.

[000136] FIG. 11 illustrates a main routine 1100 run by ECU 900 according to one embodiment of the present invention. The main routine 1100 is performed, for example, when the photobioreactor 100 is run for the first time, or each time when the culture in the photobioreactor 100 is completely drained and the photobioreactor 100 is restarted.

[000137] As shown in FIG. 10, the main routine 1100 begins at step 1002 when the photobioreactor 100 is turned on for the first time or is restarted. When initialized, the main routine 1100 then goes to the step 1110 followed by step 1 120 to prepare the photobioreactor 100. The step 1110 turns on the UV LED 210b for a predetermined amount of time to sterilize the container 203, and prompts the user to add culture medium, such as water to the container 203 and/or flushing tank 216. The main purpose is to prepare the components, especially the hydraulic circuits of the photobioreactor 100 for cultivating and harvesting the biomass. ECU 900 may perform an initial flushing routine to flushing the hydraulic circuits. Specifically, the user may add flushing fluid (for example, water or sterile agent) into the cultivation system 102 through the first inlet 612. If an output device is connected to ECU 900, the user may also be prompted to do so by ECU 900 via the output device. ECU 900 may then send signals to turn on the solenoid valve 228 in the harvest hydraulic circuit 260 and solenoid valve 232 in the waste hydraulic circuit 270, to drain the flushing fluid through and also flush the harvest hydraulic circuit 260 and waste circuit 270. In addition, ECU 900 may also send signals to turn on the solenoid valve 230 in the harvest hydraulic circuit 260 and the solenoid valve 236 in the flushing hydraulic circuit 280, and activate the pump 238 to draw the flushing fluid from the tank 216 to flush the harvest system 204 and related hydraulic circuit. At the end of the preparation routine, the user add starter microorganisms to the cultivation system 102 and insert the nutrient cartridge. Similarly, if an output device, such as a touch screen display 1 190, is connected to ECU 900, the user may also be prompted to do so by ECU 900 via the output device. Based on the species and amount of starter microorganisms, ECU 900 may send signals to draw a predetermined water into the cultivation system 102, for example, to turn on the solenoid valve 236 in the flushing hydraulic circuit 280 and valve 234 in the waste hydraulic circuit 270 and thus the water from the flushing tank 216 may be drawn into the cultivation system 206. Alternatively, the user may also add water manually to the cultivation system 102. Once the water is added to the system, the final step of preparation is triggered. The UVC lamp 210b in the light source 210 is activated to disinfect and sterilize the culture chamber. This step may substantially reduce the risk of contamination of the culture environment before cultivation routine starts.

[000138] The routine 1000 then goes to cultivation routine at the step 1130. During the cultivation routine, ECU 900 may, at predetermined intervals, turn on and off the visible light source 210a to adjust the illumination or to disinfect the culture chamber, turn on and off the gas source 246 to adjust the agitation of the culture, add water to the cultivation system 102 from the flushing tank 216, add nutrients from the nutrient cartridge, etc. In addition to that, or alternatively, when the photobioreactor is provided with sensors such as optical density sensor 1124, pH sensor 1123, water level sensor, and thermometer 1121, ECU 900 may control the light source, airlift agitation mechanism, and water and nutrients addition accordingly. If a heater, cooler, or temperature sensor 1121 is connected, ECU 900 may also adjust the temperature based on the read from the temperature sensor 1121.

[000139] During the cultivation routine, ECU 900 also determines when it is ready to harvest at the step 1140. This is determined by periodically measuring the turbidity of the culture via the optical density sensor 1124. If the ECU 900 determines that it is below harvesting threshold, ECU 900 keeps running the cultivation routine, otherwise, ECU 900 proceeds to the next step 1150. ECU 900 may determine that it is ready to harvest when, for example, a predetermined time has passed since the cultivation routine has started (such as, every 3-6 weeks), or based on the reading from the optical density sensor 1124. When the optical density reaches a predetermined level, ECU 900 determines that there have grown a sufficient amount of microorganisms and it is ready to harvest.

[000140] When ECU 900 determines that it is ready to harvest, the routine then goes to the harvest routine at step 1150. For example, ECU 900 sends signals to turn on the solenoid valve 230 in the harvest hydraulic circuit 260, turn on the solenoid valve 234 or 232 in the waste hydraulic circuit 270 depending on if the filtered culture is intended to be circulated back to the cultivation system 102 or to be disposed, and activate the metering pump 238 to draw suspension culture from the cultivation system 102 to the harvest system 204. Usually, only a part of suspension culture in the cultivation system 102 will be drawn, for example, 1/10-1/5, so that the remaining suspension culture will keep growing more microorganisms for the next harvest. The ECU 900 can measure the amount of the culture that is harvested by the readings of the flow meter 244 (step 1160). For example, ECU 900 can stop the harvesting routine, when 2 liters of the microorganism culture passed the harvesting system. Alternatively, more or less, or all of the suspension culture may be harvested. The ECU 900 may then activate the motor 330 and make the filtration container 315 revolve. At predetermined intervals, the ECU 900 stops the revolving of the filtration container 315, turns the filtration container 315 to align with the piston 321, move the piston 321 to a predetermined extended position to press fluid out of the filtration container 315 and then back to retracted position. In another embodiment when a plurality of extended positions are configured, the ECU 900 repeats the revolve of the filtration container, the pressing of the piston until the piston reaches the extended position that is the closest to the bottom of the filtration container 315. The user may then remove the filter screen 326 out of the harvest system 204 and collect the biomass.

[000141 ] After the harvest routine, the routine 1000 then goes to flushing routine at the step 1170. Similarly, ECU 900 turns on the solenoid valve 236 in the flushing hydraulic circuit 280, and turns on solenoid valve 234 or 232 in the waste hydraulic circuit 270 depending on if the flushed fluid is to be introduced back to the culture in the cultivation system 102 or to be disposed to the waste tank 218, and draw water from the flushing tank 216 to flush the harvest system 204.

[000142] The routine 1100 then determines if the cultivation of the microorganisms is to be continued (step 1180). For example, if a microorganism culture has been growing for a prolonged period of time (e.g., 3 months), The routine 1100 may prompt the user to reinitialize the culture to minimize the chance of contamination. The routine 1100 may also receive instructions from the user if an input device is connected. If it is determined to continue the cultivation routine, the of the microorganisms, the routine 1100 goes back to the step 1130, the cultivation routine; otherwise, the routine 1100 stops the running of the photobioreactor 100. In this case, when the routine 1100 goes back to cultivation routine at step 1130 after harvest, the cultivation routine, as aforementioned will first add water to the cultivation system 102 from the flushing tank 216, add nutrients from the nutrient cartridge (step 1190), etc.

[000143] FIG. 12 illustrates a specific embodiment of the present invention, which may be freely combined with the embodiments discussed above. In this particular embodiment, the photobioreactor 1210 is also equipped with a network layer (e.g., a Wi-Fi module), which is capable of display operational status of the photobioreactor 1210 and receive control inputs from a mobile computing device, such as a smart phone 1240. This can be achieved by the direct communication between the photobioreactor 1210 and the smart phone 1240, for example when the two devices are on the same Wi-Fi network. More commonly, the photobioreactor 1210 communicates via cloud based services 1260 with the smart phone 1240. In the example shown, the cloud based service comprises a MQTT broker 1220 and webservices 1230. The photobioreactor 1210 sends and receives messages using Message Queuing Telemetry Transport (MQTT) and utilizes an MQTT broker. MQTT is a standards-based messaging protocol, or set of rules, used for machine- to-machine communication. MQTT supports messaging between devices to the cloud and the cloud to the device. Specifically, an MQTT broker receives messages published by clients, filters the messages by topic, and distributes them to subscribers. In this case, the MQTT broker 1220 subscribes to the photobioreactor 1210, and the photobioreactor 1210 publishes its operational status to the MQTT broker 1220. The cloud based services 1260 that the photobioreactor 1210 communicates to also include web services 1230, for example comprises a webserver and associated database application, which can be implemented using node.js and mongoDB. The MQTT broker 1220 also subscribes to the smart phone 1240 running an appropriate application. The smart phone 1240 can display the operational status of the photobioreactor 1210 via messages published to the MQTT broker 1220. The smart phone 1240 can also communicate with the webservices 1230 to get the operational status of the photobioreactor 1210, and post commands to control the photobioreactor 1210 via the web services 1230. The application for the smart phone 1240, for example, can be implemented using flutter. The smart phone 1240 can also be of any other computing device running the appropriate programming, such as a laptop or a desktop computer. Administrative functions of the web services 1230 can be conducted via a computing device 1250, which may include create, read, update and delete (CRUD) of the data on the web services 1230. This functionality is typically distinct from for the user interface implemented on the smart phone 1240.

[000144] While the foregoing specification has been described with regard to certain preferred embodiments, and many details have been set forth for the purpose of illustration, it will be apparent to those skilled in the art without departing from the spirit and scope of the invention, that the invention may be subject to various modifications and additional embodiments, and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention. Such modifications and additional embodiments are also intended to fall within the scope of the appended claims.

Claims

What is claimed:

1. A biomass harvest system, comprising: an inlet through which a suspension culture is able to be introduced; a filtration container that is configured to revolve around a vertical axis while tilting relative to the vertical axis, wherein the filtration container is in fluid communication with an outlet; a filter screen that is removably attached within the filtration container; and a piston that is able to move towards and away from the filtration container, wherein the piston is configured to press excess fluid out of the filtration container.

2. The biomass harvest system of claim 1, wherein the piston is movable towards and away from the filtration container between an extended position in which the piston extends into the filtration container and a retraction position in which the piston is spaced from the filtration container, the piston presses excess fluid out of the filtration container in the extended position.

3. The biomass harvest system of claim 2, wherein the extended position comprises a plurality of extended positions that differ from each other in a distance to a bottom of the filter screen.

4. The biomass harvest system of any one of claims 1-3, wherein the filtration container is supported by a shaft that tilts relative to the vertical axis, and the shaft revolves around the vertical axis while tilting relative to the vertical axis thus the filtration container revolves along with the shaft.

5. The biomass harvest system of claim 4, wherein the shaft is pivotably connected to a spindle at an eccentric location, and the spindle extends along the vertical axis and is configured to rotate around the vertical axis.

6. The biomass harvest system of claim 4 or 5, further comprises a chassis and a cradle block, wherein the cradle block is supported by the chassis in a manner that the cradle block is pivotable relative to the chassis around a horizontal axis that is perpendicular to the vertical axis, and the shaft is supported by the cradle block in a manner that the shaft is pivotable relative to the cradle block around a pivoting axis that is perpendicular to the horizontal axis.

7. The biomass harvest system of any one of claims 4-6, wherein the shaft comprises a sink hole that communicates an inner space of the filtration container with the outlet.

8. The biomass harvest system of any one of claims 1-7, wherein the piston comprises a center passage that opens in a bottom of the piston facing the filtration container, and the inlet is communicated to the center passage.

9. The biomass harvest system of any one of claims 1-8, wherein the filter screen is of a shape of a truncated cone.

10. The biomass harvest system of any one of claims 9, wherein the filter screen comprises a protrusion provided in a center of a bottom wall of the filter screen.

11. The biomass harvest system of any one of claims 1 -9, wherein the filter screen comprises a plurality of perforations.

12. The biomass harvest system of claim 10, wherein a diameter of the plurality of perforations is in a range of 10-100 microns, or 20-80 microns, or 30-60 microns.

13. A biomass cultivation system, comprising: a container in which a suspension culture of microorganisms is contained; a plurality of injectors provided on a bottom wall of the container, the plurality of injectors ejecting a gas into the suspension culture to agitate the suspension culture; and a gas source that supplies a gas to the plurality of injectors, wherein each of the plurality of injector ejects the gas along an ejection direction that tilts upward relative to a horizontal plan; and at least a part of the plurality of injectors are distributed so as to, when viewed in a top view of the bottom wall, eject the gas in a substantively same circumferential direction.

14. The biomass cultivation system of claim 13, wherein the part of the plurality of injectors are evenly distributed along a circle around a center of the bottom wall.

15. The biomass cultivation system of claim 14, wherein the circle is of a shape selected from round, oval, square, triangle, rectangle, rounded rectangle, and polygon.

16. The biomass cultivation system of any one of claims 13-15, wherein the plurality of injectors comprises a plurality of first injectors and a plurality of second injectors; the plurality of first injectors are distrusted along a same circle along which the plurality of second injectors are distributed; and when viewed in the top view of the bottom wall, the plurality of first injectors eject the gas in a first circumferential direction that is opposed to a second circumferential direction in which the plurality of second injectors eject the gas.

17. The biomass cultivation system of any one of claim 13-15, wherein the plurality of injectors comprises a plurality of first injectors and a plurality of second injectors; the plurality of first injectors are distrusted along a first circle that is different from a second circle along which the plurality of second injectors are distributed.

18. The biomass cultivation system of any one of claims 13-17, wherein each of the injectors comprises a first section and a second section that are connected to each other; the first section extends vertically and is fixed to the bottom wall; and the second section extends along the ejecting direction.

19. The biomass cultivation system of any one of claims 13-18, wherein the ejecting direction forms an angle relative to the horizontal plan in a range selected from the group consisting of 20-70 degree, 25-65 degrees, and 30-60 degrees.

20. The biomass cultivation system of any one of claims 13-19, wherein when viewed in the top view of the bottom wall, the ejecting direction of each injector forms an angle relative to a radial direction towards a center of the bottom wall in a range of 70-110 degrees, 75-105 degrees, 80-100 degrees, and 85-95 degrees.

21. The biomass cultivations system of any one of claims 13-20, wherein the gas source is selected from a group consisting of an air compressor, an air pump, and a compressed air tank.

22. The biomass cultivation system of any of claims 13-21, wherein the container further comprises an outer cylinder and an inner cylinder in the outer cylinder; the suspension culture is contained in a space between the outer cylinder and the inner cylinder; and a light source is provided inside of the inner cylinder.

23. The biomass cultivation system of claim 22, wherein the light source comprises at least one selected from the group consisting of a light emitting diode light source, an incandescent lamp, a fluorescent lamp, and an ultraviolet light source.

24. A photobioreactor comprising the biomass harvest system of any one of claims 1 - 12 and/or the biomass cultivation system any one of claim 13-23.

25. The photobioreactor of claim 24, further comprising: a housing that contains the biomass harvesting system and supports the container of the cultivation system a control compartment containing the harvest system.

26. The photobioreactor of claim 25, wherein the housing further comprising an input compartment; the input compartment comprises an inlet that is in fluid communication with the container in the cultivation system; and the input compartment is configured to be removably attached to a nutrient cartridge, wherein when the nutrient cartridge is attached, the inlet is in fluid communication with an inner space of the nutrient cartridge.

27. A photobioreactor comprising of any one of claims 1-26, further comprising a networking module that communicates with a mobile computing device, wherein the mobile computing device can display an operational status of the photobioreactor.

28. A photobioreactor comprising of claim 27, wherein the mobile computing device can control the photobioreactor.

29. A photobioreactor comprising of claim 27, further comprising communicating with a cloud based service, and communicating with the mobile computing device vis the cloud based service.

30. A photobioreactor comprising of any one of claims 27-29, wherein the mobile computing device is a smart phone.