KR101425874B1 - Apparatus and method for cultivating micro-algae with nitrite - Google Patents

Abstract

The present invention relates to a device and a method for culturing microalgae by inducing partial nitrification of ammoniacal nitrogen through an MBR tank and using nitrite nitrogen produced by the partial nitrification as a culturing source for the microalgae. The device for culturing microalgae using nitrite nitrogen according to the present invention comprises: an anaerobic digestion tank which enables anaerobic digestion of livestock excrement; an MBR tank which is operated under nitrite nitrogen (NO_2-N) production conditions and is capable of converting ammoniacal nitrogen into nitrite nitrogen (NO_2-N) by biological treatment of an anaerobic digestion liquid in the anaerobic digestion tank; a microalgae culturing tank which cultures microalgae by using nitrite nitrogen (NO_2-N) and phosphorous included in discharged water of the MRB tank as nutritious elements; and a microalgae separation film which separates raw water in the microalgae culturing tank into microalgae and treating water. Nitrogen and phosphorous included in the anaerobic digestion liquid is separated in a sludge form by the MBR tank. Partial nitrogen and phosphorous included in the anaerobic digestion liquid is discharged with discharge water in order to be supplied to the microalgae culturing tank.

Description

[0001] The present invention relates to an apparatus and a method for culturing microalgae using nitrite nitrogen,

The present invention relates to an apparatus and a method for culturing microalgae using nitrite nitrogen, and more particularly, to an apparatus and a method for culturing microalgae by nitrite nitrogen produced by partial nitrification by inducing partial nitrification of ammonia nitrogen through MBR The present invention relates to an apparatus and a method for culturing microalgae using nitrite nitrogen used as a source.

Recently, interest in microalgae has been amplified in relation to the problem of CO2 reduction in order to mitigate the global warming phenomenon caused by carbon dioxide emission. The microalgae are used as energy sources by biochemically fixing carbon dioxide through photosynthesis. Biomass obtained as a result of microalgae growth is highly valuable for animal feeds, raw materials for bioenergy, and the like. In addition, eutrophication can be alleviated by using nitrogen and phosphorus contained in livestock manure without artificially supplying nitrogen and phosphorus necessary for culturing microalgae.

Accordingly, there have been attempts to cultivate microalgae using wastewater as a medium, such as the development of a microalgae culture solution using livestock classification (Korean Patent Laid-Open Nos. 2003-76133 and 2003-95154). However, in this case, because the purpose is to cultivate algae, there is a disadvantage that the treatment of wastewater can not be performed stably.

In addition, technologies for treating wastewater using microalgae include a water purification device using a fluid contact material module and a bird module and a water purification method using the same (Korean Patent Laid-Open No. 2006-100869), a rural watershed A method for improving water quality (Korea Patent Publication No. 2005-0024728) was proposed. The shape of the reaction tank for treating wastewater using microalgae (Korea Patent Publication No. 2012-73432) and the microalgae culture and harvesting apparatus (Korean Patent Laid-Open No. 2011-118908) have been proposed.

However, the above technologies have limitations in directly treating high concentrations of nitrogen and phosphorus contained in animal manure anaerobic digestive juices, and can not artificially control the growth of algae. Thus, the treatment efficiency of nitrogen and phosphorus is low, It has a drawback that it is very difficult. In addition, there is a disadvantage in that it is difficult to stably produce and recover fine algae because algae are used or algae present in a certain system are used.

Korean Patent Publication No. 2003-76133 Korean Patent Publication No. 2003-95154 Korean Patent Publication No. 2006-100869 Korean Patent Publication No. 2005-0024728 Korea Patent Publication No. 2012-73432 Korea Patent Publication No. 2011-118908

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method and apparatus for anaerobic digestion of livestock manure by biologically treating the anaerobic digestive juice with MBR to remove organic matter and solid components, The present invention provides an apparatus and method for culturing microalgae using nitrite nitrogen which can effectively remove nitrogen and phosphorus from livestock manure and simultaneously improve the culture efficiency of microalgae.

It is an object of the present invention to provide an apparatus and a method for inducing partial nitrification of ammonia nitrogen through MBR and using nitrite nitrogen produced by partial nitrification as a culture source of microalgae.

In order to accomplish the above object, the apparatus for culturing microalgae using nitrite nitrogen according to the present invention is operated in an anaerobic digestion tank for anaerobic digestion of livestock manure and under conditions for producing nitrite nitrogen (NO ₂ -N) An MBR tank for biologically treating the anaerobic digestion liquid to convert ammonia nitrogen into nitrite nitrogen (NO ₂ -N), nitrite nitrogen (NO ₂ -N) and phosphorus contained in the effluent of the MBR tank A microalgae culture tank for culturing a microalgae, and a microalgae separation membrane for separating raw water of the microalgae culture tank by microalgae and treated water, wherein nitrogen and phosphorus contained in the anaerobic digestive juice are sludge And a portion of the nitrogen and phosphorus contained in the anaerobic digestion liquid is discharged to the effluent and supplied to the microalgae culture tank .

The nitrite nitrogen (NO ₂ -N) production condition can be operated under the condition that the MBR tank is 0.3 to 3 mg / L dissolved oxygen. The nitrite nitrogen (NO ₂ -N) may be produced under the conditions that the MBR bath is operated at a pH of 6.5 to 8 or the MBR bath is operated at a temperature of 25 to 35 ° C.

The microalgae culture tank further includes an acidifier device for supplying carbon dioxide (CO ₂ ) necessary for culturing the microalgae to one side of the microalgae culture tank and preventing membrane contamination of the microalgae separation membrane. A light source for supplying light energy necessary for culturing can be disposed. At this time, the carbon dioxide required for the algae culture (CO ₂₎ is carbon dioxide (CO ₂ contained in the exhaust gas of the generator used, or using a biogas carbon dioxide (CO ₂₎ contained in the biogas produced in the anaerobic digestion tank ) Can be used.

The microalgae culture tank may be any one of a plate-like complete mixing type, a cylindrical full mixing type, a pipeline type plug flow type, and an oxidized spherical type plug flow type.

The method for culturing microalgae using nitrite nitrogen according to the present invention comprises the steps of anaerobic digesting anaerobic digestion of livestock manure and biologically treating the anaerobic digestion liquid with MBR to obtain ammonia nitrogen in anaerobic digestion solution as nitrite (NO ₂ -N), culturing the microalgae in a microalgae culture tank using the effluent of the MBR tank as nourishing material, and introducing the microalgae into the microalgae culture tank through the microalgae separation membrane Wherein the MBR tank is operated under a nitrite nitrogen (NO ₂ -N) production condition, and the nitrite nitrogen (NO ₂ -N) production condition is such that the MBR tank has a dissolved oxygen concentration of 0.3 To 3 mg / L, the MBR bath is operated at a pH of 6.5 to 8, and the MBR bath is operated at a temperature of 25 to 35 ° C.

The apparatus and method for culturing microalgae using nitrite nitrogen according to the present invention have the following effects.

In the anaerobic digestion of livestock manure, the ammonia nitrogen contained in the anaerobic digestion liquid of livestock manure is partially nitrified to produce nitrite nitrogen, which is used as a microalgae culture source, Time and energy can be saved. In addition, the efficiency of the microalgae cultivation by the nitrite nitrogen compared to the completely nitrified nitrate nitrogen can be improved, so that the microalgae culture can be efficiently performed.

FIG. 1 is a schematic view of an apparatus for culturing microalgae using nitrite nitrogen according to an embodiment of the present invention. FIG.
FIGS. 2 to 5 are schematic views of a microalgae culture tank according to an embodiment of the present invention. FIG.
6 is a graph showing the growth of microalgae according to the type of nitrogen source.
7 is a graph showing the nitrogen removal efficiency according to the type of nitrogen source.

The present invention provides a technique for purifying livestock manure and using the nitrogen component contained in livestock manure for the cultivation of microalgae. Livestock manure is converted to anaerobic digestion through anaerobic digestion process. Anaerobic digestion is biologically treated by MBR (membrane bio-reactor), and MBR runoff is used for microalgae culture.

In the conventional MBR process applied to the wastewater treatment process, ammonia nitrogen is converted to nitrate nitrogen (NO ₃ -N) via nitrite nitrogen (NO ₂ -N) by the oxidation reaction of microorganisms. The nitrate nitrogen is converted into nitrogen through the denitrification process and the wastewater is treated.

In the present invention, as described above, nitrogen is used as a culture source of microalgae, and nitrite nitrogen (NO ₂ -N), which is an intermediate product instead of nitrate nitrogen (NO ₃ -N) as an end product of nitrification process, It is characterized by its use as a culture source.

Conventional wastewater contains a low concentration of nitrogen (ammonia nitrogen) in comparison with livestock manure, and the conversion process of ammonia nitrogen to nitrate nitrogen by the MBR process proceeds in a relatively short time. On the other hand, livestock manure contains a high concentration of ammonia nitrogen, which is time consuming and expensive to convert ammonia nitrogen to nitrate nitrogen. This is because ammonia nitrogen is partially nitrified by the high concentration of nitrite nitrogen generated by partial nitrification.

Meanwhile, in the present invention, the efficiency of microalgae culturing by nitrite nitrogen and nitrate nitrogen was examined through experiments, and it was found that there was no significant difference between them. Accordingly, an apparatus and a method for providing a nutrient source for microalgae are proposed, and the optimum nitrite nitrogen production conditions are presented.

Hereinafter, an apparatus and a method for culturing microalgae using nitrite nitrogen according to an embodiment of the present invention will be described in detail with reference to the drawings.

1, an apparatus for culturing microalgae using nitrite nitrogen according to an embodiment of the present invention includes an anaerobic digestion tank 110, an MBR tank 120, a microalgae culture tank 130, and a microalgae separation membrane 140, .

The anaerobic digestion tank 110 anaerobically digests livestock manure. The MBR tank 120 biologically treats the anaerobic digestion liquid supplied from the anaerobic digestion tank 110 and removes the solid matter using the separation membrane 121 . The microalgae culture tank 130 serves to cultivate microalgae using the effluent of the MBR tank. The microalgae separation membrane 140 separates the effluent of the microalgae culture tank 130 into microalgae and treated water .

As described above, the MBR tank of the present invention is characterized by partial nitrification of a high concentration of ammonia nitrogen contained in the anaerobic digestion solution with nitrite nitrogen (NO ₂ -N). The nitrite nitrogen produced by the MBR tank NO ₂ -N) is used for microalgae culture. For the production of nitrite nitrogen (NO ₂ -N), the MBR reactor is operated under the following conditions.

First, the dissolved oxygen (DO) of the MBR bath 120 should be maintained at 0.3 to 3 mg / L. If the dissolved oxygen of the MBR tank 120 is less than 0.3 mg / L, the partial nitrification reaction, i.e., the nitrite nitrogen generation reaction, is hardly achieved due to the small amount of oxygen. If the dissolved oxygen exceeds 3 mg / L, Is not increased.

Next, the pH of the MBR bath 120 should be maintained at 6.5-8. If the pH of the MBR bath 120 is between 6.5 and 8, free ammonia is activated to prevent complete nitrification of ammonia nitrogen to nitrate nitrogen, thereby maximizing the concentration of nitrite nitrogen. On the other hand, if the pH is less than 6.5, the concentration of free ammonia is low and the complete nitrification reaction occurs. If the pH is more than 8, the concentration of free ammonia becomes too high and the efficiency of partial nitrification reaction is lowered because free ammonia is evaporated into the atmosphere.

Finally, the temperature of the MBR bath 120 should be maintained at a temperature of 25 to 35 占 폚. When the temperature of the MBR bath 120 is in the range of 15 to 25 ° C, nitrate nitrogen is more actively produced than nitrite nitrogen. If the temperature of the MBR bath 120 is more than 35 ° C, microorganisms in the MBR bath 120 are damaged There is a concern.

In addition, the MBR tank 120 biologically removes organic matter at a high concentration through the action of aerobic microorganisms and removes total solids (SS) through the separation membrane 121, Thereby increasing light supply efficiency and allowing microalgae to grow smoothly.

The anaerobic digestion liquid of the anaerobic digestion tank 110 is biologically treated by the MBR tank 120 and is separated into sludge and effluent. The effluent of the MBR tank 120 is supplied to the microalgae culture tank 130. Nitrogen and phosphorus contained in the anaerobic digestion liquid are separated in the form of sludge by the MBR tank 120. However, since the anaerobic digestion liquid contains high concentrations of nitrogen and phosphorus, some of the nitrogen and phosphorus are discharged in the effluent, The effluent of the MBR bath 120 containing nitrogen and phosphorus serves as a nutrient for microalgae. At this time, the nitrogen contained in the effluent of the MBR bath 120 is in the form of nitrite nitrogen (NO ₂ -N).

The microalgae culture tank 130 serves to cultivate microalgae using an amount of nitrite nitrogen (NO ₂ -N) and effluent containing phosphorus as a nutrient, and the microalgae separation membrane 140 is a microalgae culture tank, And serves to separate raw water in the culture tank 130 into microalgae and treated water.

The microalgae culture tank 130 can be implemented in various forms. For example, the microalgae culture tank 130 can be implemented in various forms, for example, a full plate type mixing type (see FIG. 2), a cylindrical full type mixing type See FIG. 4), or an oxidized spherical plug flow type (see FIG. 5). Meanwhile, the microalgae cultured in the microalgae culture tank 130, that is, the microalgae grown as nourishing nitrogen and phosphorus, include Ankistrodesmus gracilis SAG278-2 (KCTC AG20745), Senethes Scenedesmus accuminatus (KCTC AG 10316), Senethesmus Kuah give the cow Scenedesmus quadicauda: include KCTC AG10032) can be used: KCTC AG 10308), it is used in Los peora platen system (Arthrospira platensis: KCTC AG20590) and Chlorella vulgaris (Chlorella vulgaris.

The micro-algae separation membrane 140 may be formed by a filtration method in which the flow direction of the micro-algae is the same as the filtration direction of the treated water or a crossflow type filtration method in which the filtration direction of the micro- Can be used. In addition, the microalgae separation membrane 140 may be at least one selected from the group consisting of a microfiltration membrane having a membrane pore size of 0.1 μm to several μm and an ultrafiltration membrane having a membrane pore size of 0.002 to 0.05 μm, . By applying such a microalgae separation membrane 140, it is possible to independently separate the hydraulic retention time (HRT) and the solids retention time (SRT). Particularly, the concentration of microalgae in the microalgae culture tank 130 Control is possible. Meanwhile, the treated water separated by the microalgae separation membrane 140 may be partially transported and supplied to the MBR tank 120 to control the concentration of the anaerobic digestion liquid.

The microalgae culture tank 130 further includes a diffuser 131 for supplying carbon dioxide (CO ₂ ) necessary for microalgae culture and preventing membrane contamination of the microalgae separation membrane 140 And a light source 132 for supplying light energy required for culturing the microalgae may be disposed on the microalgae culture tank 130. When the microalgae culture tank 130 is constructed of a pipeline type plug flow type (see FIG. 4), an air exchange column 133 may be provided in place of the air diffuser 131, ). Further, carbon dioxide (CO ₂ ) required for culturing the microalgae can be recovered by using carbon dioxide (CO ₂ ) contained in the biogas produced in the anaerobic digestion tank 110 or by using carbon dioxide (CO ₂ ) contained in the exhaust gas of the generator using biogas ₂ ) can be used.

The apparatus and method for culturing microalgae using nitrite nitrogen according to an embodiment of the present invention have been described above. Next, the efficiency of microalgae culture and nitrogen removal efficiency by nitrite nitrogen will be examined.

6 shows the growth of microalgae according to the kind of nitrogen source. Referring to FIG. 6, both nitrate nitrogen (indicated by a circle in FIG. 6) and nitrite nitrogen (indicated by a circle in FIG. 6) 6), and it can be seen that the efficiency of microalgae cultivation by nitrate nitrogen and the efficiency of microalgae cultivation by nitrite nitrogen are not much different from each other.

FIG. 7 shows the nitrogen removal efficiency according to the kind of nitrogen source. Referring to FIG. 7, it can be seen that nitrogen removal efficiency by nitrate nitrogen and nitrite nitrogen is better than ammonia nitrogen, and nitrate nitrogen and nitrite It can be seen that the nitrogen removal efficiency by each nitrogen is almost the same.

110: anaerobic digestion tank 120: MBR tank
121: Separation membrane 130: Microalgae culture tank
131: diffuser 132: light source
133: air exchange column 140: micro algae separation membrane

Claims (8)

Anaerobic digestion tank anaerobic digestion of livestock manure;
An MBR tank operated under the condition of producing nitrite nitrogen (NO ₂ -N) and biologically treating the anaerobic digester of the anaerobic digester to convert ammonia nitrogen into nitrite nitrogen (NO ₂ -N);
A microalgae culture tank for culturing microalgae using nitrite nitrogen (NO ₂ -N) and phosphorus contained in the effluent of the MBR tank as nutrients; And
And a micro algae separation membrane for separating raw water of the microalgae culture tank by microalgae and treated water,
The organic matter contained in the anaerobic digestion liquid and a portion of nitrogen and phosphorus are separated into sludge by the MBR tank. The dissolved nitrogen and phosphorus contained in the anaerobic digestion liquid are discharged to the effluent and supplied to the microalgae culture tank Wherein the nutrient nitrogen-containing micro-algae culture apparatus comprises:
2. The method according to claim 1, wherein the nitrite nitrogen (NO ₂ -N)
Wherein the MBR tank is operated under a condition of 0.3 to 3 mg / L of dissolved oxygen.
2. The method according to claim 1, wherein the nitrite nitrogen (NO ₂ -N)
Wherein the MBR tank is operated at a pH of 6.5 to 8. The apparatus for culturing microalgae using nitrite nitrogen according to claim 1,
2. The method according to claim 1, wherein the nitrite nitrogen (NO ₂ -N)
Wherein the MBR tank is operated at a temperature of 25 to 35 占 폚.
[3] The microalgae culture apparatus according to claim 1, further comprising a diffuser which supplies carbon dioxide (CO ₂ ) necessary for culturing microalgae to one side of the microalgae culture tank and prevents membrane contamination of the microalgae separation membrane, Wherein a light source for supplying light energy necessary for culturing the microalgae is disposed on the upper part of the incubation tank.
The method of claim 5, wherein the microalgae carbon dioxide necessary for the cultivation (CO ₂₎ is carbon dioxide contained in the exhaust gas of the generator used, or using a biogas carbon dioxide (CO ₂₎ contained in the biogas produced in the anaerobic digestion tank (CO ₂ ) is used as the micro-algae culture apparatus.
The microalgae culture apparatus according to claim 1, wherein the microalgae culture tank is any one of a plate-type complete mixing type, a cylindrical full mixing type, a pipeline type plug flow type, and an oxidized spherical type plug flow type. A device for culturing microalgae using nitrogen.
Anaerobic digestion of livestock manure to produce an anaerobic digestive juice;
Biologically treating the anaerobic digestion liquid with the MBR bath to convert the ammonia nitrogen in the anaerobic digester to nitrite nitrogen (NO ₂ -N);
Culturing the microalgae in a microalgae culture tank using the effluent of the MBR tank as nourishing water;
Separating raw water of the microalgae culture tank into microalgae and treated water through a microalgae separation membrane,
The MBR reactor is operated under the conditions of nitrite nitrogen (NO ₂ -N) production, and the nitrite nitrogen (NO ₂ -N)
Wherein the MBR tank is operated under the conditions of dissolved oxygen of 0.3 to 3 mg / L, the MBR tank is operated at a pH of 6.5 to 8, and the MBR tank is operated at a temperature of 25 to 35 ° C. Microalgae culture method.

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