The present invention relates to photobioreactor for culturing a photosynthetic microorganism, and more particularly to a photobioreactor using a barrier for mass culture of a photosynthetic microorganism, wherein the barrier allows water, gas, and nutrients to freely pass through, but restricts free diffusion of the photosynthetic microorganism.
Photosynthetic unicellular microorganisms may produce various organic substances such as proteins, carbohydrates, and lipids through photosynthesis. In particular, photosynthetic unicellular microorganisms are recently considered as an optimal organism for the purpose of elimination of carbon dioxide, which is a main cause of global warming, as well as production of added value products such as functional polysaccharides, carotenoids, vitamins, and unsaturated fatty acids. In addition, the photosynthetic unicellular microorganisms have been noted in biological energy production to replace fossil fuel, i.e. a limited energy source, because microalgae can fix carbon dioxide and accumulate it into a body as a lipid. Numerous studies have been conducted to produce bioenergy such as biodiesel by using lipids thus accumulated.
However, to practicalize useful resultants obtained by employing microalgae, e.g. removal of carbon dioxide or production of bioenergy, high concentration culture, mass culture, or high concentration mass culture of photosynthetic microorganisms is required. Thus, a technique associated with establishment of a large-scale culture facility is essentially required.
Typically, various types of photobioreactor placed indoors or on lands have been used as a culture facility for culturing photosynthetic microorganisms, however manufacture, maintenance, and operation of the photosynthetic microorganism culturing facility (such as a lighting unit, and a supplement and mixing unit of medium and gas) are costly, so that it is difficult to establish a large-scale facility required for commercialization. Consequently, profitability secure is a most important and prior task for mass culture of photosynthetic microorganisms in a commercialized scale, and it is urgently required to develop a culturing technique which allows high concentration culture with low cost to be performed and facilitates scale-up. Thus, there is an attempt to culture photosynthetic microorganisms on or in water such as sea or lake by using a semipermeable membrane. Such techniques include Japanese Laid-open Patent Publication No. 2007-330215 and Korean Registered Patent No. 991373, etc.
However, a photobioreactor using the semipermeable membrane as above has a problem in economical efficiency because the cost of the semipermeable membrane is high; durability is low; and exchange of materials through the semipermeable membrane is restrictive.
The present invention is to solve various problems including the problem as above, and is intended to provide a photobioreactor for mass culture of photosynthetic microorganisms that is efficient in terms of costs, time, efficiency, and space. However, these solutions are for illustrative purpose only, and the scope of the present invention is not limited thereto.
According to one aspect of the present invention, provided is a photobioreactor including a culture container capable of holding a photosynthetic microorganism to be cultured and liquid for dispersing the photosynthetic microorganisms, wherein a whole or at least a part of the culture container has a barrier allowing water, gas, and nutrients to freely pass through, but restricting free diffusion of the photosynthetic microorganisms.
The photosynthetic microorganisms may be dispersed and cultured in the liquid.
The barrier may be prepared with a material which allows water, gas, and nutrients to freely pass through, but restricts diffusion of photosynthetic microorganisms. For example, the barrier may be a mesh sheet or perforated sheet.
The mesh sheet may have a fabric structure. Since the mesh sheet having a fabric structure does not restrict penetration of gas, water, and nutritional salts, but free diffusion of photosynthetic microorganisms, the mesh sheet may be applied to mass culture of photosynthetic microorganisms in an economical and convenient way.
In the photobioreactor, an opening size of the mesh sheet may be adjusted depending on a size of a photosynthetic microorganism to be cultured. For example, the opening size may be 0.1 μm to 200 μm, 0.1 μm to 100 μm, 0.2 μm to 50 μm, 0.5 μm to 25 μm, 0.5 μm to 22 μm, 1 μm to 20 μm, 3 μm to 18 μm, or 4 μm to 16 μm. Optionally, the opening size may be 50% to 300%, 70 to 250%, 85% to 200%, 90% to 160%, 100% to 150%, 100% to 140%, 100% to 130% or 110% to 120% of a size of a photosynthetic microorganism to be cultured.
In the photobioreactor, the mesh sheet may be woven with a polymer fiber. The polymer may be a biodegradable polymer or hardly degradable polymer. The biodegradable polymer may be one or at least two selected from the group consisting of polycaprolactone, poly lactic acid, poly(lactic co-glycolic acid) copolymer, cellulose, methyl cellulose, ethyl cellulose, cellulose acetate, curdlan, polyglutamic acid, polylysine, polyhydroxy alkanoate, polyethylene glycol, polyglycolic acid, and polyester, but not limited thereto.
In addition, the hardly degradable polymer may be one or at least two selected from the group consisting of teflon (polytetrafluoroethylene), polyolefine, polyamides, polyacrylate, silicon, poly methyl methacrylate, polystyrene, ethylene vinyl acetate copolymer, polyethylene-maleic anhydride copolymer, polyamide, poly(vinyl chloride), poly(vinyl fluoride), poly(vinyl imidazole), chlorosulphonate polyolefin, polyethylene terephthalate (PET), nylon, low density polyethylene (LDPE), high density polyethylene (HDPE), acryl, polyetherketone, polyimide, polycarbonate, polyurethane, and polyethylene oxide, but not limited thereto.
The mesh sheet differs from a semipermeable membrane in that the semipermeable film restricts penetration of a macromolecule having at least a certain size such as proteins, while the mesh sheet allows a macromolecule, except a material having a cell size, to freely penetrate. The present inventors demonstrate that the mesh sheet can be usefully applied to mass culture of photosynthetic microorganisms by finding an astonishing fact that, even in the case of culturing a photosynthetic microorganism having a size smaller than the opening size of the mesh sheet, the photosynthetic microorganism is not diffused to outside of the culture container, while nutrients including nutrition salts, water, and gas, which are required for culture, freely pass through.
In the photobioreactor, expect the mesh sheet, remaining parts of the culture container may be prepared with a semipermeable or non-permeable and transparent or translucent material.
The perforated sheet differs from a typical semipermeable membrane in that the perforated sheet is prepared by artificially perforating a non-permeable or semipermeable polymer membrane. The perforated sheet may be prepared by irregularly or regularly perforating a polymer membrane by using a micro perforating device. A size of the hole may be adjusted depending on a size of a photosynthetic microorganism to be cultured. For example, a size of the hole may be 0.1 μm to 200 μm, 0.1 μm to 100 μm, 0.2 μm to 50 μm, 0.5 μm to 25 μm, 0.7 μm to 22 μm, 1 μm to 20 μm, 3 μm to 18 μm, or 4 μm to 16 μm. Optionally, a size of the hole may be 50% to 300%, 70 to 250%, 85% to 200%, 90% to 160%, 100% to 150%, 100% to 140%, 100% to 130% or 110% to 120% of a size of a photosynthetic microorganism to be cultured.
The non-permeable polymer membrane may be one or at least two selected from the group consisting of teflon (polytetrafluoroethylene), polyolefine, polyamides, polyacrylate, silicon, poly methyl methacrylate, polystyrene, ethylene vinyl acetate copolymer, polyethylene-maleic anhydride copolymer, polyamide, poly(vinyl chloride), poly(vinyl fluoride), poly vinyl imidazole, chlorosulphonate polyolefin, polyethylene terephthalate (PET), nylon, low density polyethylene (LDPE), high density polyethylene (HDPE), acryl, polyetherketone, polyimide, polycarbonate, polyurethane, and polyethylene oxide, but not limited thereto.
The semipermeable polymer membrane may be prepared with a composite material of a hydrophilic polymer and the polymer fiber which is used to form the non-permeable membrane as above, wherein the hydrophilic polymer may be one or at least two selected from the group consisting of cellulose, methyl cellulose, ethyl cellulose, cellulose acetate, poly vinyl alcohol, cellophane, nitrocellulose and polyester.
In the photobioreactor, the culture container may be provided with one or more inlet, wherein the inlet may be provided with a switching unit which may be in a form of a zipper, a zipper bag, a valve, a check valve, a tub cap, an adhesive tape, a clip, or a clawclip.
In the photobioreactor, the culture container may be allowed to float on a water surface by a buoyant unit or to submerge under the water surface to a certain depth by a sedimentation unit. The buoyant unit may be a floater such as a buoy separately placed outside of the culture container or may be in a shape of an air injection tube which is not separately placed but extended from the culture container. In addition, the sedimentation unit may be a plumb bob coupled to a lower part of the culture container, or an underwater structure placed underwater or under a water surface to allow the culture container to submerge under the water surface in a certain depth.
In that case, the culture container may be an enclosed-type culture container or an open-type culture container having an opened upper face, wherein the open-type culture container may have a raceway-shaped pond structure, and may further include a culture medium circulator to circulate the culture medium. According to an embodiment of the present invention, the open-type culture container may include an upper frame, and a barrier which is coupled to the upper frame to hold photosynthetic microorganisms. A whole or part of the barrier is prepared with a material which allows water, gas, and nutrients to freely pass through, but restricts free diffusion of the photosynthetic microorganism. Further, the open-type culture container may additionally include a vertical frame and a lower frame. The upper frame may be prepared with a buoyant material or additionally include a buoyant unit. When the upper frame is prepared with a buoyant material, the frame may be a plastic frame or tube having a vacuum inside or including air or gas capable of providing buoyancy. As necessary, the frame may house the barrier to thereby modulate a depth of the culture container.
Additionally, one end of the culture container may be coupled to the buoyant unit and another end may be coupled to the sedimentation unit.
In the photobioreactor, one face of the culture container may be configured to modulate light energy supplied to photosynthetic microorganisms through a light blocking area. The light blocking area has a light filtering function, so that a certain region of wavelengths, among solar light supplied to the photobioreactor, may selectively penetrate or be blocked. The wavelength region may be, for example, where divided as blue, red or green series, etc., among solar light wavelength. The wavelength region to penetrate or to be blocked may be appropriately selected depending on types of photosynthetic microorganisms to be cultured. A membrane having the light filtering function may be prepared by mixing a plastic or polymer material with a chemical component capable of absorbing a light wavelength at a certain wavelength region. The chemical component may be included in a pigment dye.
In the photobioreactor, the culture container may be configured to be rotated in an axial direction by a force from water or wind through a fan attached to one face of the culture container. The fan may be configured to include two or more fans extending to different directions from each other, and the fans may cross each other. In addition, the fan may have a curve to allow the culture container to be rotated on a vertical axis.
According to another aspect of the present invention, provided is a culture facility for photosynthetic microorganisms including a floating structure including the photobioreactor.
The floating structure includes a partition, which is coupled between the frame and frame and installed to prevent loss of the photobioreactor, wherein the partition separates an inside and outside of the culture facility. The partition may be prepared with various materials such as plastics, wood, plywood, nets, but preferably nets in consideration of costs and free communication of environmental water. The culture facility for photosynthetic microorganisms thus formed has a structure similar to a sort of floating fish cages. A buoyant unit may be attached to the frame of the floating structure formed on a water surface to float the floating structure onto the water surface. The buoyant unit may adjust buoyancy taken into account conditions such as solar light energy and nutritional salts required to culture of photosynthetic microorganisms to be cultured. The buoyant unit may be prepared with various materials such as styrofoam or a plastic vessel which has a vacuum inside or includes air or gas capable of providing buoyancy. Also, the buoyant unit may overlay the upper frame, or the upper frame may be coupled to a separate buoyant unit. When the buoyant unit overlays the upper frame, the buoyant unit may serve as a working space used by an operator to conduct a work in the culture facility. In addition, the floating structure may be configured to include an operator supporting unit where an operator may conduct a management work. The operator supporting unit plays a role as a support on which an operator may conduct a work, and the operator supporting unit may be coupled to the buoyant unit or the underwater or floating facility separated from the buoyant unit. In that case, the photobioreactor may be provided with or without a buoyant unit. For the photobioreactor without a buoyant unit, in order not to allow the photobioreactor to submerge under a water surface too deep, a depth of a bottom face of the floating structure may be appropriately modulated to respond to changes in light intensity or cell concentration.
According to another aspect of the present invention, provided is a method for culturing photosynthetic microorganisms, including preparing the photobioreactor; and introducing, into one or more of the photobioreactor, photosynthetic microorganisms and a culture medium, and then putting the photobioreactor to the culture facility to perform photosynthesis.
In the culturing method, the photosynthetic microorganisms are dispersed and cultured in a culture medium without a carrier.
According to an embodiment of the present invention as above, it is possible to implement the photobioreactor capable of mass culture of photosynthetic microorganisms in an economical and efficient way. Surely, the scope of the present invention is not limited to the effect.
, Δ A polyester mesh sheet;
∘, : nylon mesh sheet;
, □: 50 kDa molecular weight cut-off semipermeable
membrane;
f/2: f/2 culture medium; and
NSW: near seawater.
The terms used herein are defined as follows.
As used herein, the term “semipermeable” refers to a phenomenon in which only some materials are available to selectively pass through an interface such as a membrane or plate, and counteracts “permeable” indicating that most of materials are available to pass through and “non-permeable” indicating that most of materials are unavailable to pass through.
As used herein, the term “translucent” refers to a phenomenon in which some of light pass through an interface such as a membrane or plate, and counteracts “transparent” indicating that most of light pass through, and “opaque” indicating that pass of light is substantially blocked.
As used herein, the term “barrier” refers to a structure spatially separating an inside of a culture container including photosynthetic microorganisms to be cultured from an outside of the culture container. The wording “allows water, gas, and nutrients to freely pass through, but restricts diffusion of photosynthetic microorganisms” means that most of materials including macromolecules such as water, gas and nutrients are available to freely pass through, rather than a certain molecule selectively passes through by osmosis, however free diffusion of cells such as photosynthetic microorganisms is restricted. Although some cells may pass through the barrier, cell concentrations of both sides of the barrier do not reach equivalent states. A semipermeable membrane differs from “the barrier allowing water, gas, and nutrients to freely pass through, but restricting diffusion of photosynthetic microorganisms” in that the semipermeable membrane restricts penetration of gas, and considerable number of macromolecules is not available to pass through at all. The barrier may be, for example a mesh sheet or perforated sheet.
As used herein, the mesh sheet may be woven with a pattern, for example plain weave, twill weave, and warp stain to include a structure woven by crossing weft threads and warp threads in a vertical direction, or be prepared by varying processing methods or types of a sheet material used such as compound weaving, pile weaving, and leno weaving. The mesh sheet refers to a sheet prepared by applying a technique used in preparation of a woven fabric.
As used herein, the term “perforated sheet” refers to a sheet having holes by artificially perforating a planar material, wherein the planar material may be a film and the film may be a non-permeable or semipermeable membrane. Through artificial perforation, the perforated sheet may provide the same effect as the mesh sheet.
As used herein, the term “nutrient” is a material taken by an organism for nutrition, and includes mineral salts such as ferric salts, sodium salts, potassium salts, phosphate, and magnesium salts, and organic nutrients such as vitamins, proteins, lipids, and carbohydrates except oxygen for respiration and water and carbon dioxide for photosynthesis.
As used herein, the term “environmental water” refers to water in a space where the photobioreactor of the present invention is introduced and culture is performed, wherein the water may include seawater, fresh water and brackish water, as well as water in an artificially created water storage tank or pond.
As used herein, the term “free pass” or “free diffusion” refers to a state in which a certain material is available to pass through two spaces separated by a barrier without limitation, wherein pass is a concept irrelevant to a concentration difference of a certain material in both spaces, while diffusion refers to a phenomenon in which a certain material migrates from a space having a high concentration into a space having a low concentration.
As used herein, the wording “restricting free diffusion” is a case where diffusion of a certain material, which is present in overwhelmingly high concentration in one space among two spaces separated by a barrier, into the other space is substantially restricted under the barrier exiting condition, although diffusion occurs when the barrier does not exist, and the case does not exclude migration of some materials. Thus, the wording “restricting free diffusion” may be used as the same concept of the wording “substantially restricting diffusion”.
As used herein, the term “opening size” refers to a size of a space between weft threads and warp threads which are woven to cross each other in the mesh structure.
As used herein, the term “photosynthetic microorganism” refers to green algae, red algae, and blue-green algae, which are capable of photosynthesis, for example chlorella, Chlamydomonas, Haematococcus, Botryococcus, Scenedesmus, Spirulina, Tetraselmis, and Dunaliella, etc., but not limited thereto. The photosynthetic microorganism as described above may produce metabolites such as carotenoids, mycobiont, phycobiliproteins, lipids, carbohydrates, unsaturated fatty acids, and proteins in a culture container.
Hereinafter, embodiments of the present invention are described with reference to the accompanying drawings. The present invention may, however, be embodied in various forms differs from each other, and should not be construed as limited to the embodiments illustrated in the disclosed drawings. Rather, the embodiments illustrated in drawings are provided so that the disclosure of the present invention will be complete, and will fully convey the scope of the present invention to those skilled in the art. Also, the dimensions of elements may be exaggerated or reduced for convenience of illustration.
The photobioreactor for mass culturing photosynthetic microorganisms using a mesh sheet according to the present invention may maximize degrees of growth of photosynthetic microorganisms with minimized cost, so that the photosynthetic microorganisms may be efficiently mass produced. In addition, the photobioreactor is placed to float on a water surface or placed underwater to submerge to a certain depth in order to provide an effect of overcoming spatial constraints for mass culture.
As shown in
Particularly, the mesh sheet is characterized by allowing environmental water, gas and nutrients to freely pass through, while restricting free diffusion of photosynthetic microorganisms or contaminant microorganisms. More particularly, since environmental water may be introduced, nutrients required for growth of photosynthetic microorganisms may be supplied, and waste excreted during growth of photosynthetic microorganisms may be removed with environmental water. Since an additional nutrient supplier and purifier is not required, cost, time, and labor-saving effect is provided. Moreover, generated oxygen may be released, and carbon dioxide required for photosynthesis of photosynthetic microorganisms may be supplied through the mesh sheet. Further, since photosynthetic microorganisms are cultured in a manageable and restrictive culture container, it is possible to prevent environmental contamination caused by mass propagation of photosynthetic microorganisms, and to facilitate harvest of mass cultured photosynthetic microorganisms. In particular, the photobioreactor prepared by using the mesh sheet 111 according to the first embodiment of the present invention provides an effect of increasing growth of photosynthetic microorganisms by about 1.5 to 2 times of that of a photobioreactor prepared by using a typical semipermeable membrane, indicating that production efficiency of the photosynthetic microorganisms is significantly improved.
The mesh sheet is characterized by allowing water, nutrients, gas and waste of photosynthetic microorganisms to be freely introduced and released, while blocking free diffusion of the photosynthetic microorganisms. For example, the mesh sheet may be woven with a polymer fabric. The polymer may be a biodegradable polymer or hardly degradable polymer. The biodegradable polymer may be one or at least two selected from the group consisting of polycaprolactone, poly lactic acid, poly(lactic-co-glycolic acid) copolymer, cellulose, methyl cellulose, ethyl cellulose, cellulose acetate, nitrocellulose, curdlan, polyglutamic acid, polylysine, polyhydroxy alkanoate, polyethylen glycol, polyglycolic acid, and polyester, but not limited thereto.
In addition, the hardly degradable polymer may be one or at least two selected from the group consisting of teflon (polytetrafluoroethylene), polyolefine, polyamides, polyacrylate, silicon, poly methyl methacrylate, polystyrene, ethylene-vinyl acetate copolymer, polyethylene-maleic anhydride copolymer, polyamide, poly(vinyl chloride), poly(vinyl fluoride), poly vinyl imidazole, chlorosulphonate polyolefin, polyethylene terephthalate (PET), nylon, low density polyethylene (LDPE), high density polyethylene (HDPE), acryl, polyetherketone, polyimide, polycarbonate, polyurethane, and polyethylene oxide, but not limited thereto.
The culture container prepared by using the mesh sheet may be not particularly limited, but be prepared in any shape, for example circular, oval, cone, or cylindrical shape, provided that the shape is capable of holding photosynthetic microorganisms.
In addition, a whole or part of the barrier of the culture container may be prepared with the mesh sheet, and others are prepared by using non-permeable or semipermeable and transparent or translucent material for maintaining a stereoscopic shape, while floating. For example, when one end of a plastic container holding photosynthetic microorganisms is sealed by using the mesh sheet, the container may float near a surface of seawater due to buoyancy of the plastic container.
As shown in
The buoyant unit may be an article such as typical styrofoam, a buoy, and a vacant vessel, coupled to the culture container through a coupling unit (see
As shown in
As shown in
As shown in
As shown in
As shown in
The photobioreactor 108 according to the eighth embodiment of the present invention is characterized by having a wobbling structure allowing a culture container 110 to wobble by wind or wave. For example, as shown in
As shown in
Moreover, as shown in
As above, when the culture container having the open upper part, and a barrier, which is placed at a whole or part of the side and/or bottom face, allowing gas, water, and nutrients to freely pass through, while restricting free diffusion of photosynthetic microorganisms is used, it is possible to more efficiently culture photosynthetic microorganisms because the raw cost is greatly reduced; gases are more freely exchanged; waste generated during photosynthesis are readily removed; and nutrients are readily supplied from environmental water.
A culture facility for photosynthetic microorganisms 1000 according to an embodiment of the present invention may include a photobioreactor 1100 and a floating structure 1200 holding the photobioreactor, wherein, in the culture facility, a plurality of culture containers capable of culturing photosynthetic microorganisms are secured at a certain location of a water surface to facilitate collection after culture without loss. To prevent loss of the photobioreactor 1100, the floating structure 1200 includes an upper frame of culture facility 1210 and fences 1220 for coupling the upper frames of curling field 1210 to separate inside from outside of the culture facility 1000. As shown in
As above, when culture is performed by confining the photobioreactor according to an embodiment of the present invention by using the culturing filed of photosynthetic microorganisms, it is possible to prevent loss of the photobioreactor without a particular securer, and to facilitate putting and collecting of the photobioreactor.
Hereinafter, the present invention will be described in more detail with reference to experimental examples. The present invention may, however, be embodied in various forms differs from each other, and should not be construed as limited to the experimental examples set forth hereinafter, the experimental examples are provided so that the disclosure of the present invention will be complete, and will fully convey the scope of the present invention to those skilled in the art.
An experiment was conducted to investigate whether photosynthetic marine microorganisms are released through a mesh sheet. Culture containers were constructed by attaching mesh sheets respectively prepared with PET, polyester and nylon to bottoms of plastic containers having a total volume of 100 ml. 60 ml of photosynthetic microorganism (wet weight: 0.5 g/L) (Tetraselmis sp.) was placed into the culture container and the container was allowed to float on a plastic container containing 1 L of f/2-Si medium to investigate whether the photosynthetic microorganisms were released to outside of the culture containers prepared with the mesh sheets. An opening size for nylon and PET was 5 μm, and an opening size for polyester was 15 μm. If photosynthetic microorganisms are released to outside of the mesh sheet, the photosynthetic microorganisms would grow using a medium at outside. During culture of photosynthetic microorganisms, temperature was maintained at 20° C., and μE/m2/s of intensity of light was supplied using fluorescent light. After five days of culture, concentrations of photosynthetic microorganisms at inside and outside of the reactor were measured with coulter counter (model: multi-sizer 3, Beckman Inc., USA).
Characterization of the mesh sheet used and volume of culture medium contained in the culture container set forth in Table 1 below.
As shown in
Photosynthetic microorganisms were cultured by practically using the culture container prepared with the mesh sheet, and also photosynthetic microorganisms were cultured by using a semipermeable membrane of a cellulose material as a control.
1 L of f/2-Si, and 1 L of near seawater (NSW) were poured into two plastic water baths having a capacity of containing 2 L of an aqueous solution, wherein the NSW was prepared by diluting f/2-Si medium to 1/30 in order to adjust nitrogen and phosphorus concentration similar to that of dissolved in seawater of Incheon. The mesh sheet with polyester or nylon material (0.003 m2) was attached to a bottom of the plastic reactor. 100 ml of culture medium, to which 0.05 g/l (wet weight) of photosynthetic microorganisms were inoculated, was poured into the plastic container, and then the container was allowed to float on the water bath while photosynthetic microorganisms were cultured (
Consequently, as shown in
Then, the present inventor measured nutritional salt permeability of the culture container prepared with the mesh sheet. For a control, a semipermeable membrane of a cellulose material was used to culture photosynthetic microorganisms.
Nutritional salts permeability was measured with a transfer rate of nitrates, which is an important factor for culture of photosynthetic microorganisms. A method for measuring nutritional salt permeability of the mesh sheet was as follows: 2 L of seawater including nitrates having concentrations of 100, 200 or 400 mg/L was prepared in a rectangular water bath; a rectangular plastic container containing 100 ml of seawater without nitrates was allowed to float on the water bath; and changes in the concentration difference due to introduction of nitrates from the water bath to the plastic container was measured with lapse of time.
Consequently, as shown in Table 2 below and
The present inventors placed the photobioreactor according to an embodiment of the present invention on sea culturing filed in Yeongheung-Do. Then, Tetraseimis sp. (KCTC12236BP) was cultured for 9 days to investigate growth of the strain and degrees of penetration of a nitrogen source. The same type of photosynthetic microorganisms were cultured in photobioreactors prepared by using non-permeable membrane (polyethylene) and semipermeable membrane together with the reactor prepared with the mesh sheet according to an embodiment of the present invention. The photobioreactor had a structure as shown in
During culturing Tetraselmis sp. for 9 days, temperature, water temperature, measured water temperature, and measured temperature of see culture facility for Yeongheung-Do are recorded as in μE/m2/s; and average light irradiation time was 7.4 hours (see
Degrees of growth of photosynthetic microorganisms in the photobioreactor were determined based on cell concentration and wet weight of photosynthetic microorganisms. When the photobioreactors prepared by using the mesh sheets of polyester and PET material were used, growth of photosynthetic microorganisms were respectively increased to 1.68×106, and 1.77×106 cells/ml (
To investigate reuse efficiency of the mesh sheet according to an embodiment of the present invention, the mesh sheet used in Experimental Example 4 was collected. The mesh sheet was, then, washed or not washed and used to culture Tetraselmis sp. strain for 9 days in a culturing device in sea at Yeongheung-Do, while measuring nitrate transfer efficiency. As a control, the semipermeable membranes of a cellulose material having molecular weight cut-off of 6-8 kDa and 15 kDa, which were used in Experimental Example 4, were used after washing or without washing. Also, an unused membrane was used as a control for the whole experiment. Particularly, washing was performed with running tap water as follows: each used membrane was immersed in a 2 L of water bath filled with 1 L of tap water for about five minutes; and the front and reverse sides of the membrane were manually washed with running tap water for about 1 minute without an additional washing tool.
While culturing the Tetraselmis sp. strain for 9 days, transfer rates of nitrates through the membranes were compared by the same method as Experimental Example 3. Consequently, as shown in
The present invention has been described with reference to the embodiments and experimental examples illustrated in the drawings for only exemplary purpose, and it should be understood that numerous modifications and other equivalent embodiment can be made thereto by a person skilled in the art. Therefore, the technical protection scope of the present invention should be defined by the technical sprit of the appended claims.
The photobioreactor according to an embodiment of the present invention is allowed to culture of photosynthetic microorganisms with low costs and high efficiency, and can thus be applied to production of biodiesel and useful products such as astaxanthin derived from microalgae, as well as production of foods using microalgae.
Number | Date | Country | Kind |
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10-2013-0037421 | Apr 2013 | KR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/KR2014/002919 | 4/4/2014 | WO | 00 |