KR101958938B1 - a floating marine photobioreactors - Google Patents

Abstract

The present invention relates to a floating marine photobioreactor which has improved productivity of microalgaes by effectively inhibiting biofouling. The floating marine photobioreactor comprises: a culture container which accommodates a microalgae culture medium, is made of a non-biodegradable polymer and includes a mesh, and in which a material of a portion thereof is sulfonated; and a buoyancy means which provides buoyance to the culture container.

Description

A floating marine photobioreactors

The present invention relates to subtype marine photobioreactors.

Currently, human beings are in need of new energy development to prepare for depletion of fossil fuels. At the same time, in order to urgently address the serious environmental problems caused by the use of fossil fuels, (Kim, K. et al., J. Ind. Eng. Chem., 33, 326-329, 2016, Park, K. et al., Bioprocess Eng. , 186-190, 2000). Among them, microalgae, the third generation of bio-energy, are able to produce various types of energy such as bio-diesel and bio-ethanol as well as effectively remove carbon dioxide due to high photosynthetic efficiency compared with land plants and do not utilize food crops It is also free of ethical problems. Despite these advantages, however, production of bioenergy using microalgae faces commercial limitations. The price of bio-energy produced using microalgae is still higher than that of petroleum energy. Cultivation of microalgae energy production cost accounts for about 40-50% of total production cost. In order to lower the cost of these culture production processes, a method of culturing microalgae in the ocean is attracting attention. The culture of microalgae using the ocean is advantageous in that it can achieve 1) wide culture area, 2) control of culture temperature using high specific heat of seawater, 3) nutrient supply through sea water, and 4) Park, H. et al., Biotechnol., J. 11, 1461-1470, 2016). In order to utilize nutrients in seawater for cultivation, microalgae cells can not pass through, but dissolved nutrients can be made through selective permeable membranes (eg, cellulosic semi-permeable membranes, polymeric membranes, etc.) (Kim, Z Et al., J. Microbiol. Biotechnol., 26, 1098-1102, 2016). In addition, bacteria and microalgae attach to the surface of the membranes to close the pores of the membranes, and biofouling phenomena that lower the permeability of the seawater should be reduced. This is to prevent the nutrient supply through the seawater and shorten the life of the membranes, Thereby reducing efficiency. The most widely used method to inhibit biofouling is to treat biocides in advance with semipermeable membranes, but this approach is not suitable for microalgae cultivation because it also inhibits the growth of microalgae. In order to inhibit the attachment of microalgae, it is necessary to pay attention to the characteristics of microalgae. Microalgae have hydrophobicity in water and have a negative charge. Therefore, microalgae use hydrophilicity of chitosan, (Liu, CX et al., J. Membr. Sci., 346, 121-130, 2010) There is a case of using a semi-permeable membrane with a negative charge by taking advantage of the fact that the microalgae are negatively charged in water C. et al., Int. J. Food Microbiol., 97, 237-245, 2005).

However, in the case of the above-described prior art, there is a problem that a material having a negative charge is likely to be dissolved in water, and therefore, the effect is deteriorated when it is used for a long time.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a sub-type marine photobioreactor with improved micro-algae productivity. However, these problems are exemplary and do not limit the scope of the present invention.

According to one aspect of the present invention, there is provided a culture vessel comprising a selective permeation membrane in which a part of a space for accommodating a microalgae culture liquid is sulfonated; And floatation means for providing buoyancy to the culture vessel.

According to one embodiment of the present invention as described above, the productivity of microalgae can be improved by effectively inhibiting bio-pollution by using the sub-type marine photobioreactor of the present invention. Of course, the scope of the present invention is not limited by these effects.

1 is a photograph showing a state of a 100 ml subtype photobioreactor with a filter membrane of a PET mesh material attached to a lower portion thereof.
2 is a conceptual diagram showing a process of synthesizing sulfonated PET using chlorosulfonic acid.
3 shows SP-mesh (20 min reaction, b), SP-mesh (40 min reaction, SP-mesh) c) and SP-mesh (60 min reaction, d).
4 is a graph showing the permeability of SP-mesh and P-mesh of the present invention.
FIG. 5 is a graph showing the results of Tetraselmis sp. The productivity of the product.
FIG. 6 is a scanning electron micrograph of the SP-mesh and P-mesh of the present invention showing the results of (a) before P-mesh culture, (b) after P-mesh culture, (D) after incubation.

Definition of Terms:

As used herein, the term "microalgae" refers to phytoplankton inhabiting the ocean, and plankton such as cochlearinism, which often causes red tides, is also a microalgae. Microalgae, which focuses on marine bioenergy research, is a species of microalgae that is rich in lipids, that is, oil. The size is about 10 microns (micron, one millionth of a meter) and about one tenth the thickness of the hair.

As used herein, the term "photosynthetic microorganism" refers to algae, red algae, and blue algae capable of photosynthesis, including, for example, Chlorella, Chlamydomonas , Haematococous , Botryococcus ), may be a three or four etc. death mousse (Scenedesmus), Spirulina (Spirulina), tetra-cell Miss (Tetraselmis), two flying it Ella (Dunaliella), but is not limited to such. At this time, the above microalgae can produce carotenoids, microbial cells, pycobiliproteins, lipids, carbohydrates, unsaturated fatty acids and proteins in a culture container.

 The term " biofouling "as used herein refers to a phenomenon in which biofilms are formed by attaching microorganisms to the bottom of a ship, a heat exchanger of a power plant, an offshore structure, etc., There arises a problem that the permeability of the seawater is reduced by blocking the pores of the algal culture membrane.

As used herein, the term "sulfonation" refers to a reaction for synthesizing a sulfonic acid by introducing an SO ₃ H group to an organic compound. The reaction is carried out by reacting hydrocarbons with concentrated sulfuric acid and fuming sulfuric acid. It is usually introduced into carbon atoms, but sometimes it is also introduced into nitrogen atoms. Generally refers to a reaction in which a reagent such as sulfuric acid, fuming sulfuric acid, sulfur trioxide, or chlorosulfuric acid (chlorosulfonic acid) is reacted with an aromatic compound such as an aromatic hydrocarbon or a derivative thereof to replace with a sulfonic acid group.

DETAILED DESCRIPTION OF THE INVENTION [

According to one aspect of the present invention, there is provided a culture vessel comprising a selective permeation membrane in which a part of a space for accommodating a microalgae culture liquid is sulfonated; And floatation means for providing buoyancy to the culture vessel.

In the subtype marine photobioreactor, the culture container may include a selective permeable membrane in which an upper portion can be opened and a material under the culture container is sulfonated.

In the subtype marine photobioreactor, the selective permeable membrane may be a semi-permeable membrane or a mesh, and the selective permeable membrane may be made of a degradable polymer.

In the sub-type marine photobioreactor, the refractory polymer may be selected from the group consisting of teflon, polytetrafluoroethylene, polyolefine, polyamides, polyacrylate, silicon, polymethylmethacrylate but are not limited to, poly methly methacrylate, polystyrene, polypropylene, ethylene-vinyl acetate copolymers, polyethylene-maleic anhydride copolymers, polyamides, poly (vinyl chloride) ), Poly (vinyl imidazole), chlorosulphonate polyolefin, polyethylene terephthalate (PET), nylon, low density polyethylene (LDPE), high density polyethylene high density polyethylene (HDPE), acryl, polyetheretherketone, polyimide de, polycarbonate, polyurethane or poly (ethylene oxide), and the said means of support can be pontoon, plastic canister, styrofoam, buoy, pipe or wood carvings. have.

In order to prevent biofouling phenomenon, the inventors of the present invention thought that sulfonated PET is hydrophilic in water and has a negative charge, so that the biofouling phenomenon will be suppressed by the repulsive force with the surface charge of microalgae. Therefore, the degree of sulfonation (DS) was calculated by comparing the weight before and after the sulfonation synthesis, and the hydrophilicity of the membrane was compared using the contact angle method. A polymer woven mesh was used as a selective permeable membrane and polyethylene terephthalate (sulfonated) film of polyethylene terephthalate (PET) to induce sulfonation by attaching SO ₃ H groups.

Finally, a prototype photobioreactor with a 100-mL scale was fabricated using a sulfonated membrane and the initial concentration was fixed at 0.2 g / L. When the bioreactor was inhibited, the degree of microalgae cultivation was measured using a conventional PET photobioreactor Respectively. After the incubation, a scanning electron microscope (SEM) analysis was conducted to compare the inhibition of bio - contamination of the semi - permeable membrane to effectively inhibit biofouling, thereby developing a sub - type marine bioreactor with improved microalgae productivity.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of explanation.

It is to be understood that throughout the specification, when an element such as a film, region or substrate is referred to as being "on", "connected to", "laminated" or "coupled to" another element, It will be appreciated that elements may be directly "on", "connected", "laminated" or "coupled" to another element, or there may be other elements intervening therebetween. On the other hand, when one element is referred to as being "directly on", "directly connected", or "directly coupled" to another element, it is interpreted that there are no other components intervening therebetween do. A uniform code refers to a uniform element. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

Also, relative terms such as "top" or "above" and "under" or "below" can be used herein to describe the relationship of certain elements to other elements as illustrated in the Figures. Relative terms are intended to include different orientations of the device by adding weight to the orientation depicted in the Figures. For example, in the figures the elements are turned over so that the elements depicted as being on the top surface of the other elements are oriented on the bottom surface of the other elements. Thus, the example "top" may include both "under" and "top" directions depending on the particular orientation of the figure. If the elements are oriented in different directions (rotated 90 degrees with respect to the other direction), the relative descriptions used herein can be interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically showing ideal embodiments of the present invention. In the figures, for example, variations in the shape shown may be expected, depending on manufacturing techniques and / or tolerances. Accordingly, the embodiments of the present invention should not be construed as limited to the particular shapes of the regions shown herein, but should include, for example, changes in shape resulting from manufacturing.

Example 1: Use of strain and strain

The present inventors have found that Tetraselmis sp. KCTC12429BP was cultured using artificial seawater. The culture medium was used by adding to the f / 2-Si medium modified in artificial seawater artificial sea water is 30 g / L NaCl in distilled water, 0.66 g / L KCl, 8.48 g / L MgCl 2 6H 2 O used in the tests, 1.9 g / L CaCl ₂ 2H ₂ O, 6.318 g / L MgSO ₄ 7H ₂ O, and 0.18 g / L NaHCO ₃ . Then, the modified f / 2-Si medium was added to the distilled water at a concentration of 225 mg / L NaNO ₃ , 5 mg / L NaH ₂ PO ₄ .H ₂ O, 3.15 g / L FeCl ₃ .6H ₂ O, 4.36 g / _{2 EDTA · 2H2O, 180 mg /} L MnCl 2 · 4H 2 O, 22 mg / L ZnSO 4 · 7H 2 O, 10 mg / L CoCl 2 · 6H 2 O, 9.8 mg / L CuSO 4 · 5H 2 O, 6.3 mg / L Na ₂ MoO ₄ .2H ₂ O, 0.225 g / L NaNO ₃ , and 0.015 g / L NaH ₂ PO ₄ . The seeds for this culture were maintained in a 2 L volume bubble column photobioreactor under the condition of a luminous intensity of 100 μE / m ₂ / s, a temperature of 20 ° C., 2% CO _2, 0.1 vvm aeration.

Example 2: Fabrication and operation of a subtype photobioreactor

The inventors of the present invention have found that when Tetraselmis sp. To confirm the difference in culture, a subtype photobioreactor was fabricated.

Specifically, the subtype photobioreactor was made of high-density polypropylene with a thickness of 2 mm. First, the horizontal and vertical lengths were 9 cm and 7 cm, respectively, and the height was 5 cm. The maximum volume of the liquid was 300 mL. In addition, the top and bottom of the hexahedral biochemical reactor were open, and a filtration membrane (0.0063 m ² ) was attached to the bottom of the reactor to allow permeation of artificial seawater. A 50-mL tube was attached on both sides. Thereafter, 2 L of the medium was put into a rectangular water tank having a length of 30 cm and a length of 21 cm and a height of 15 cm, which can accommodate a maximum of 10 L of liquid, using the modified f / 2-Si The prepared subtype photobioreactor was allowed to float and stirred at 450 rpm using a magnetic stirrer. At this time, the initial cell concentration was maintained at a temperature of 23 ° C with a light intensity of 55 ± 5 μE / m ² / s at 0.2 g / L (dry cell weight, DCW) (FIG.

Example 3: Semi-permeable membrane and sulfonation reaction

The selective permeable membrane used in the present invention was a sulfonation reaction of a PET membrane (P-mesh) and a sulphonated sulfonated membrane (SP-mesh) by the following method.

First, 0.05 M of chlorosulfonic acid (ClSO ₃ H) solution was prepared using dichloromethane (CH ₂ Cl ₂ ) as a solvent. P-mesh was added to the above 0.05 M chlorosulfonic acid solution, After 20, 40, and 60 minutes of reaction, washed with distilled water repeatedly to remove the residual chlorosulfonic acid of the synthesized SP-mesh. After proceeding until there was no change in the pH of the washing water, a desiccator (Fig. 2). The degree of sulfonation (DS) was calculated using the following formula (1) by measuring the weight (Wo) of the P-mesh before the reaction and the weight (Wr) of the SP-mesh after the reaction.

As a result, as shown in the following Table 1, the SP-mesh which was reacted for 20 minutes was 5.40 g before the reaction but increased to 5.44 g after the reaction. The SP-mesh which reacted for 40 minutes was changed from 5.23 g to 5.29 g, The SP-mesh reacted for 60 minutes increased from 6.10 g to 6.19 g. The DS value increased to 0.82%, 1.23% and 1.52% due to the attachment of -SO ₃ H to the benzene ring of PET in the sulfonation reaction. As the synthesis time increases, more -SO ₃ H adheres . The weight of the filter membrane before and after the reaction according to the sulfonation time and the DS value calculated using the weight of the filter membrane are shown in Table 1 below.

Reaction time (min) Weight before reaction
( W _o , g) Weight after reaction
( W _r , g) DS (%) 20 5.40 5.44 0.82 40 5.23 5.29 1.23 60 6.10 6.19 1.52

Example 4: Measurement of contact angle

The contact angle was precisely measured using a contact angle meter apparatus (DGD Fast / 60, GBX Technologies, Romans-sur-Isère, France), and 100 μL of water was dropped on the P-mesh and SP- Were measured by drop casting method. This can be measured by comparing the state of dropping the water droplet on the P-mesh before the reaction and the state of dropping the drop on the synthesized SP-mesh. When the contact angle between the filter, water droplet and gas phase decreases Meaning that the SP-mesh is more hydrophilic than the P-mesh (Fig. 3).

As a result, as shown in Table 2 below, as the sulfonation time was increased to 20 minutes, 40 minutes, and 60 minutes, it decreased from 75.5 degrees to 64.6 degrees, 53.4 degrees, and 44.5 degrees (Fig. 3). This means that the higher the degree of synthesis, the higher the hydrophilicity of the filter membrane. The reduction of the contact angle is due to the attachment of SO ₃ H groups on the surface. The contact angles with the sulfonation time are shown in Table 2 below.

Time (minutes) 0 20 40 60 Contact angle ( ^o ) 75.5 ± 2.0 64.6 ± 2.6 53.4 ± 2.9 44.5 ± 3.2

Example 5 Measurement of Water Permeability

Water permeability is an important index for evaluating the properties of filter membranes . Tetraselmis sp. , The nutrients dissolved in water are supplied through the filter membrane. Therefore, the higher the permeability of the permeated water, the higher the permeability of Tetraselmis sp. The culture efficiency of the culture medium is enhanced. Thus, SP-mesh (SP-mesh) was used to measure the permeability of permeated water using a SP-mesh filter membrane with P-mesh (0.0063 m ² ) and 20, 40, To the attached negative-type semi-permeable reactor was added 0.13 g / L (DCW) of Tetraselmis sp. , The amount of water permeated every 30 seconds was measured, and water permeability was calculated using the following formula (2).

Where Paw is the average water permeability (AWP) and Vw is the volume (mL) of water permeated through the semipermeable membrane. T is the time (sec) taken for water to permeate and A is the area of the semi-permeable membrane (m ² ).

As a result, the permeability of water gradually increased over time (> 150 sec) in the initial (< 150 sec) and gradually decreased in water (Fig. 4). This is due to the fact that the pore size of the filter membrane over time has decreased by Tetraselmis sp. (20 minutes), 34 mL (40 minutes), and 40 mL (60 minutes) of water was passed through the SP-mesh for 600 seconds. . Thus for a result of calculating the average water permeability (AWP), P-mesh is 5.42 mL / m showed a value of ² / s SP-mesh is ^{7.67 mL / m 2 / s (} 20 bun), 8.99 mL / m ² / s (40 min) and 10.58 mL / m ² / s (60 min). In this case, SP-mesh shows faster water permeability than P-mesh because firstly hydrophobicity decreases and hydrophilicity increases and hydrophilic water is relatively easy to permeate. Secondly, SP- Since the sulfone group (-SO ₃ H) attached to the mesh is negatively charged in water, Tetraselmis sp. , Which is caused by electrostatic repulsion, is relatively suppressed. The average water permeability of the P-mesh and SP-mesh is shown in Table 3 below.

P-mesh SP-mesh (20 min) SP-mesh (40 min) SP-mesh (60 min) Average water permeability
(mL / m ² / s) 5.42 7.67 8.99 10.58

Example 6: Measurement of cell concentration

To determine the effect of SP-mesh according to the present invention on cell culture as compared to P-mesh, a SP-mesh filter membrane having a P-mesh of 0.0063 m ² and a sulfonation reaction time of 60 minutes Tetraselmis sp. Incubated with a prototype incubator . The culture was carried out three times in total and the cell concentration in the incubator was measured. Cell number, cell size, and fresh cell weight (FCW) were measured precisely using a Coulter counter (Multisizer 4, Beckman Coulter, Inc., Fullerton, CA, USA).

As a result, the initial culture concentration was 0.2 g / L (DCW), but the cell concentration of the SP-mesh membrane was increased over time (FIG. 5). After 6 days of culture, the final cell concentration was obtained from P-mesh and SP-mesh at 0.95 and 1.27 g / L, respectively. The above results show that when SP-mesh is used than P-mesh, Tetraselmis sp. And 34 ± 5.5%, respectively. The reason for this effect is that the water permeability was increased by the hydrophilic property generated by the attachment of -SO ₃ H and the -SO ₃ H exhibited the electrostatic repulsive force in the water to suppress the biodegradation phenomenon, do.

Example 7: Electron Scanning Microscope (SEM) Measurement

The surface morphology of P-mesh and SP-mesh (reaction time: 60 min, DS: 1.52%) used before and after culturing was examined by electron microscopy (JSM-6010LA, JEOL Ltd., Tokyo, Japan), and the filter membrane used after culturing was measured after drying for two days in an oven after thoroughly wiping off the water.

As a result, when compared with before and after culturing, it was confirmed that the SP-mesh greatly reduced the bio-contamination phenomenon as compared with the P-mesh (Fig. 6). This phenomenon suggests that the SP-mesh with -SO ₃ H group is negatively charged like Tetraselmis sp.

As a result, the sub-type marine photobioreactor using the sulfonated reaction membrane of the present invention effectively inhibits bio-contamination and thus exhibits improved microalgae productivity. Therefore, various fields (osmotic pressure, Reverse osmosis).

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (7)

A culture vessel containing a mesh made of a poorly decomposable polymer in which a part of the space accommodating the microalgae culture liquid is sulfonated; And
And floatation means for providing buoyancy to the culture vessel. The method according to claim 1,
The culture vessel is open at the top. The method according to claim 1,
Wherein the material under the culture vessel comprises a sulfonated selective permeable membrane. delete delete The method according to claim 1,
The refractory polymer may be selected from the group consisting of teflon, polytetrafluoroethylene, polyolefine, polyamides, polyacrylate, silicon, poly methly methacrylate, polystyrene, Polypropylene, ethylene-vinyl acetate copolymers, polyethylene-maleic anhydride copolymers, polyamides, poly (vinyl chloride), poly (vinyl fluoride), polyvinyl imidazole imidazole), chlorosulphonate polyolefin, polyethylene terephthalate (PET), nylon, low density polyethylene (LDPE), high density polyethylene (HDPE), acryl acryl, polyetheretherketone, polyimide, polycarbonate, polyurea, (Polyurethane) or the polyethylene oxide, the sub type marine photobioreactor oxide (poly (ethylene oxide)). The method according to claim 1,
Wherein said support means is a pontoon, a plastic can, a styrofoam, a buoy, a pipe or a piece of wood.

Images