Production method of inorganic nutritious liquid and device therefor

Abstract

To provide a technology capable of more effectively producing an inorganic nutritious liquid from an organic material.SOLUTION: A production method of an inorganic nutritious liquid includes: a supplying step of supplying organic material-containing water to a decomposition tank on the most upstream side among plural decomposition tanks disposed from the upstream side to the downstream side; and a decomposition step of decomposing organic matters contained in the organic material-containing water by nitrifying microbial population in the decomposition tank under an aerobic condition while consecutively transporting the organic material-containing water from the decomposition tank on the upstream side to the decomposition tank on the downstream side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method and an apparatus for producing an inorganic nutrient solution. [Background technology]

[0002] As a technique for using organic fertilizer in hydroponics, there are the techniques of Patent Documents 1, 2, and 3, which were developed by one of the inventors of the present application. The technique of Patent Document 1 involves adding organic fertilizer to a decomposition tank inhabited by nitrifying microorganisms that smoothly decompose organic matter into inorganic nutrients, and decomposing it into nitric acid and the like over a period of about two weeks, resulting in inorganic nutrient differentiation. The technique of Patent Document 2 is an improvement over the technique of Patent Document 1, and involves producing a seed bacterium containing a nitrifying microorganism group. By using this seed bacterium, it has become possible to reduce the time required for generating an inorganic nutrient solution, i.e., for inorganic nutrient differentiation of organic matter, to as little as four days.

[0003] The technology of Patent Document 3 involves adding organic matter (organic fertilizer) to a carrier (column) on which nitrifying microorganisms are immobilized, leaving it to stand overnight, and then washing with water the next day. This process is repeated until the organic matter decomposes and inorganic nutrients such as nitrate are produced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5071897 [Patent Document 2] Patent No. 5388096 [Patent Document 3] Patent No. 5686352 Summary of the Invention [Problem to be solved by the invention]

[0005] In the batch method of Patent Documents 1 and 2, in which organic fertilizer is decomposed in a separate container in advance and the inorganic nutrient solution is added, it takes a long time, about 4 days to 2 weeks, to inorganically fertilize organic matter, and the amount of organic matter that can be added is limited. In addition, in the column method of Patent Document 3, it is possible to inorganically fertilize organic matter in one day, but it is difficult to make the column large, and there is a limit to the amount of inorganic nutrient solution that can be produced. For this reason, there has been a demand for the development of a technology that can efficiently produce inorganic nutrient solution from organic matter.

[0006] An object of the present disclosure is to provide a technique capable of more efficiently producing an inorganic nutrient solution from organic matter. [Means for solving the problem]

[0007] That is, according to the present disclosure, there is provided a method for producing an inorganic nutrient solution, comprising the steps of: a supply step of supplying organic matter-containing water to the most upstream decomposition tank among a plurality of decomposition tanks arranged from upstream to downstream; a decomposition step in which the organic matter contained in the organic matter-containing water is decomposed under aerobic conditions by a nitrifying microorganism group in each of the plurality of decomposition tanks while the organic matter-containing water is transferred sequentially from an upstream decomposition tank to a downstream decomposition tank; A method for producing an inorganic nutrient solution is provided, comprising:

[0008] According to the present disclosure, there is also provided an apparatus for carrying out the method for producing an inorganic nutrient solution, comprising: A plurality of decomposition tanks are arranged from upstream to downstream, Each of the plurality of decomposition tanks is provided with an air supply unit and contains a nitrifying microorganism group; The most upstream decomposition tank among the plurality of decomposition tanks further includes a supply unit to which organic matter-containing water is supplied, The decomposition tanks are arranged in series such that the organic matter-containing water supplied from the supply unit is transferred in sequence from the most upstream decomposition tank to the downstream decomposition tank, and the organic matter contained in the organic matter-containing water is decomposed under aerobic conditions by the nitrifying microorganisms in each of the decomposition tanks. An apparatus for producing a mineral nutrient solution is provided. Effect of the Invention

[0009] According to the present disclosure, organic matter can be efficiently converted into inorganic nutrient solution by supplying organic matter-containing water to the most upstream decomposition tank among a plurality of decomposition tanks arranged from upstream to downstream, and decomposing the organic matter contained in the organic matter-containing water under aerobic conditions by nitrifying microorganisms in each decomposition tank while transferring the organic matter-containing water from the upstream decomposition tank to the downstream decomposition tank in sequence. Therefore, according to the present disclosure, a technology for more efficiently producing an inorganic nutrient solution from organic matter can be provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an apparatus for producing an inorganic nutrient solution according to an embodiment and Example 1 of the present disclosure. [Diagram 2] FIG. 1 is a schematic diagram showing an apparatus for producing an inorganic nutrient solution according to a second embodiment. [Figure 3A] 1 is a graph showing daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the first decomposition tank (Example 1). In the figure, the vertical axis shows each ion concentration (mg / L), and the horizontal axis shows the date. [Figure 3B] 1 is a graph showing daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the second decomposition tank (Example 1). In the figure, the vertical axis shows each ion concentration (mg / L), and the horizontal axis shows the date. [Figure 3C] 1 is a graph showing daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the third decomposition tank (Example 1). In the figure, the vertical axis shows each ion concentration (mg / L), and the horizontal axis shows the date. [Figure 4A] 1 is a graph showing daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the first decomposition tank (Example 2). In the figure, the vertical axis shows each ion concentration (mg / L) and the horizontal axis shows the date. [Figure 4B]1 is a graph showing daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the second decomposition tank (Example 2). In the figure, the vertical axis shows each ion concentration (mg / L), and the horizontal axis shows the date. [Figure 4C] 1 is a graph showing daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the third decomposition tank (Example 2). In the figure, the vertical axis shows each ion concentration (mg / L), and the horizontal axis shows the date. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the present embodiment will be described with reference to the drawings. Note that each configuration shown in the drawings is merely an example for realizing the present disclosure. In addition, in order to avoid duplication, the same reference numerals may be used to denote configurations that have already been described, and repeated description may be omitted.

[0012] FIG. 1 is a schematic diagram of an inorganic nutrient solution manufacturing apparatus 1 according to the present embodiment. The inorganic nutrient solution manufacturing apparatus 1 is provided with a plurality of decomposition tanks arranged from the left (upstream) side of the paper to the right (downstream) side of the paper. The inorganic nutrient solution manufacturing apparatus 1 in FIG. 1 is provided with a most upstream decomposition tank 11 and two or more decomposition tanks arranged downstream (two decomposition tanks 12 and 13 in this embodiment). The materials of these decomposition tanks 11 to 13 are not particularly limited as long as they are containers capable of storing water and having a structure that allows dissolved oxygen to easily spread. The size of each decomposition tank can be set individually as appropriate, but is usually 1 to 100,000 L, preferably 10 L to 80,000 L, and more preferably 15 L to 50,000 L.

[0013] Adjacent decomposition tanks 11-13 are connected in series via pipes 21 and 22. These pipes 21 and 22 may have any structure as long as they can transfer organic matter-containing water to the adjacent decomposition tank downstream. In Fig. 1, these pipes are arranged below the liquid level of the decomposition tanks, but the pipes 21 and 22 may be arranged at a position higher than the liquid level of the decomposition tanks 11-13 so that the overflow flows into the adjacent decomposition tanks 11-13 downstream, or the pipes 21 and 22 may be provided at the bottom of the decomposition tanks 11-13.

[0014] Hereinafter, the most upstream decomposition tank 11 may be referred to as the first decomposition tank 11, and the two downstream decomposition tanks 12 and 13 may be referred to as the second decomposition tank 12 and the third decomposition tank 13, respectively. The first decomposition tank 11 is provided with a supply unit 4 for supplying organic matter-containing water. The supply unit 4 is connected to an organic matter tank and a water supply pipe (not shown), and can supply organic matter-containing water at a desired concentration by appropriately diluting the organic matter with water. The organic matter-containing water supplied from the supply unit 4 to the first decomposition tank 11 is sequentially transferred to the second decomposition tank 12 and the third decomposition tank 13 downstream through the above-mentioned pipes 21 and 22.

[0015] Each of the decomposition tanks 11-13 is equipped with an air supply unit 5 such as an air pump and contains a nitrifying microorganism group in order to efficiently decompose organic matter (particularly nitrogen-containing organic matter) contained in the organic matter-containing water under aerobic conditions by the nitrifying microorganism group. The air supply unit 5 is preferably disposed at the bottom of each of the decomposition tanks 11-13 as shown in FIG. 1. The aeration amount from the air supply unit 5 is not particularly limited, but it is desirable that the aeration amount is such that aerobic conditions can be maintained overall in each of the decomposition tanks 11-13. For example, the aeration amount can be 0.1 L / min or more per 1 L of organic matter-containing water in the decomposition tanks 11-13.

[0016] The term "nitrifying microorganisms" refers to the "microorganisms performing parallel multiple mineralization reactions" disclosed in Patent Documents 1 to 3, and includes a microorganisms performing ammonification and a microorganisms performing nitrification, and thus can smoothly decompose organic nitrogen into nitrate nitrogen such as nitrate ions and nitrates. The "microorganisms performing ammonification" can be, for example, ammonia-producing bacteria such as protozoa, bacteria, and filamentous fungi. The "microorganisms performing nitrification" can be, for example, ammonia-oxidizing bacteria (or nitrite-producing bacteria) belonging to the genera Nitrosomonas, Nitrorosococcus, and Nitrosospira (including Nitrosolobus and Nitrosovibrio), and nitrite-oxidizing bacteria (or nitrate-producing bacteria) belonging to the genera Nitrobacter, Nitrospira, and Nitrococcus. Two or more of these microorganisms can be used in combination.

[0017] The above-mentioned nitrifying microorganisms may be added to each decomposition tank in the form of an inorganic nutrient solution obtained according to this embodiment, a culture solution of the nitrifying microorganisms, or a dried product thereof, etc. In this case, the amount of the nitrifying microorganisms added is not particularly limited, but may be, for example, 0.1% or more in terms of the volume ratio of the culture solution to the decomposition tank, or 0.01 g / L or more in terms of the dried product.

[0018] The nitrifying microorganisms may be immobilized on a suitable solid carrier and provided in each decomposition tank. In this case, the amount of the solid carrier on which the nitrifying microorganisms are immobilized is not particularly limited, but may be, for example, 0.1% or more, preferably 5% or more, in terms of the volume ratio of the solid carrier to the decomposition tank.

[0019] Here, the "solid carrier" is preferably a fibrous or porous solid carrier having air permeability, and more preferably made of a material suitable for immobilizing microorganisms. For example, a solid carrier made of one or more materials selected from polyvinylidene chloride fibers, charcoal, perlite, sand, vermiculite, ceramics, zeolite, glass, rock wool, urethane, nylon, and melamine resin can be used.

[0020] Further, the third decomposition tank 13 located at the most downstream position is provided with an outlet 3 for the inorganic nutrient solution produced by the decomposition treatment of the organic matter in each of the decomposition tanks 11 to 13. In FIG. 1, the outlet 3 is disposed at a position higher than the liquid level in the third decomposition tank 13 so that the overflow is discharged as the inorganic nutrient solution, but the outlet 3 may be provided below the liquid level in the third decomposition tank 13. As a result, the organic matter-containing water supplied from the supply unit 4 is transferred in one direction from the most upstream first decomposition tank 11 to the downstream second decomposition tank 12, and further from the second decomposition tank 13 to the third decomposition tank 13, through the pipes 21 and 22 connecting the adjacent decomposition tanks 11 to 13, while being decomposed under aerobic conditions by the nitrifying microorganisms in each of the decomposition tanks 11 to 13.

[0021] In addition to the above configuration, each of the decomposition tanks 11-13 may be equipped with sensors for detecting the temperature and water level of the organic matter-containing water (or inorganic nutrient solution) and the concentrations of nitrate ions, nitrite ions, and ammonium ions. The supply unit 4 may also be equipped with a valve or the like for controlling the supply amount of the organic matter-containing water. The organic matter tank connected to the supply unit 4 may also be equipped with a heater for adjusting the liquid temperature of the organic matter-containing water, agitating blades for preventing precipitation of the organic matter, and the like. The pipes 21 and 22 may also be equipped with valves and pumps for preventing backflow of the organic matter-containing water.

[0022] Next, a method for producing an inorganic nutrient solution will be described. The method for producing an inorganic nutrient solution according to the present embodiment is a method for producing an inorganic nutrient solution, a supply step of supplying organic matter-containing water to the most upstream decomposition tank among a plurality of decomposition tanks arranged from upstream to downstream; a decomposition step in which the organic matter contained in the organic matter-containing water is decomposed under aerobic conditions by a group of nitrifying microorganisms in each of the decomposition tanks while the organic matter-containing water is transferred from an upstream decomposition tank to a downstream decomposition tank in sequence; The present invention is characterized by comprising:

[0023] The method for producing an inorganic nutrient solution according to this embodiment is carried out, for example, by the apparatus according to this embodiment shown in FIG.

[0024] The "inorganic nutrient solution" in this embodiment may have a nitrate ion concentration of 100 mg / L or more, preferably 200 mg / L or more, more preferably 400 mg / L or more, and an ammonium ion concentration of 20 mg / L or less, and may be usable as a liquid fertilizer for hydroponic cultivation of plants. In addition to nitrates and nitrate ions, the inorganic nutrient solution may contain organic fertilizers or inorganic fertilizers containing phosphoric acid, potassium, calcium, various trace elements, etc., plant growth promoters, plant activation agents, etc.

[0025] The "organic matter-containing water" in this embodiment is water in which an organic matter described later is dissolved or dispersed. The "organic matter" may be any organic resource such as organic fertilizer, food residue, plant residue, livestock waste, or excrement, but it is preferable to use a high-nitrogen-containing organic matter having a C / N ratio, which is the carbon to nitrogen content ratio of the organic matter as a whole, of 24 or less, preferably 11 or less. Specifically, the "organic matter" is preferably one or more selected from fish broth, corn steep liquor, oil cake, fish meal, methane digestion liquid, compost, rice bran, soybean flour, soybean meal, plant residue, milk, powdered milk, yeast lees, sake lees, shochu lees, food waste, and livestock manure, and in particular, liquids such as bonito broth and corn steep liquor are preferable.

[0026] In the supply step of this embodiment, the method of supplying the organic matter-containing water to the most upstream decomposition tank may be continuous or intermittent. The amount of organic matter-containing water supplied per day can be set appropriately, for example, 1 to 100,000 L, preferably 5 L to 1000 L, and can be 1 to 100% of the volume of the most upstream decomposition tank, preferably 30% to 70%. The content of organic matter in the organic matter-containing water can be 0.1 to 100 g / L, preferably 1 to 50 g / L, calculated as dry weight. More specifically, the content of the organic matter in the organic matter-containing water can be 0.14 to 140 g / L, preferably 1.4 to 70 g / L (0.1 to 100 g / L, preferably 1 to 20 g / L in terms of dry weight) when fish broth (e.g., bonito broth) is used as the organic matter, and 0.2 to 200 g / L, preferably 2 to 100 g / L (0.1 to 100 g / L, preferably 1 to 40 g / L in terms of dry weight) when corn steep liquor is used. It is desirable to gradually increase the content of the organic matter in the organic matter-containing water within the above range from the viewpoint of suppressing damage to the ecosystem of the nitrifying microorganisms. For example, at the start of the supply of the organic matter-containing water, it is preferable to set the content of the organic matter in the organic matter-containing water to 10 g / L or less in terms of dry weight.

[0027] In the decomposition process of this embodiment, the organic matter-containing water is continuously supplied to the most upstream decomposition tank in an amount exceeding the volume of the most upstream decomposition tank, and the organic matter-containing water is transferred from the most upstream decomposition tank to the downstream decomposition tank, and from the downstream decomposition tank to the further downstream decomposition tank, through the piping connecting the adjacent decomposition tanks. Meanwhile, the organic matter contained in the organic matter-containing water is decomposed under aerobic conditions by the nitrifying microorganisms in each decomposition tank. In other words, the treated water after the organic matter-containing water is decomposed in a certain decomposition tank is transferred to a decomposition tank downstream of the decomposition tank, and the nitrifying microorganisms living in the downstream decomposition tank decompose the organic matter remaining in the treated water under aerobic conditions. The inorganic nutrient solution produced by this process is finally taken out from the most downstream decomposition tank.

[0028] The "nitrifying microorganisms" living in each decomposition tank are as described above in the description of the inorganic nutrient solution manufacturing apparatus 1. By the action of the nitrifying microorganisms, the organic nitrogen contained in the organic matter is decomposed into ammonia nitrogen (ammonium ion or ammonium salt), the ammonia nitrogen is decomposed into nitrite nitrogen (nitrite ion or nitrite), and the nitrite nitrogen is further decomposed into nitrate nitrogen (nitrate ion or nitrate). The water temperature suitable for these decomposition processes is a water temperature suitable for the growth of the nitrifying microorganisms, and specifically, is 15 to 42°C, preferably 15 to 37°C, and more preferably 20 to 37°C.

[0029] The "aerobic conditions" are as described above in the description of the inorganic nutrient solution manufacturing apparatus 1. If the inside of the decomposition tank is not maintained under aerobic conditions, the denitrification reaction by the denitrifying bacteria is likely to occur, and the generated nitrate nitrogen will be gasified and lost outside the system, which is undesirable.

[0030] The inorganic nutrient solution produced by the above-mentioned device or method according to the present embodiment can be used as it is for hydroponic cultivation as a stock solution, but it can also be used after diluting it 2 to 10 times or mixed with a chemical fertilizer. The inorganic nutrient solution can also be dried and processed into a concentrated solution, powder, tablet, or other form.

[0031] The inorganic nutrient solution produced by the device or method according to the present embodiment can be used as a fertilizer for all kinds of plants, including vegetables, fruit trees, trees, flowers, and ornamental plants. In particular, it can be suitably used for cultivating leafy vegetables such as bok choy, komatsuna, lettuce, and spinach, and vegetables whose fruits are harvested such as tomatoes. The inorganic nutrient solution can be used not only for hydroponic cultivation, but also as a fertilizer for cultivation using general soil.

[0032] The inorganic nutrient solution produced by the device or method according to the present embodiment can be added to the nutrient solution for hydroponics, thereby enabling hydroponics with direct addition of organic matter (organic fertilizer). Here, the ratio of the inorganic nutrient solution added to the nutrient solution can be, for example, 5 to 100%.

[0033] The organic matter that can be added directly to the nutrient solution containing the inorganic nutrient solution produced by the device or method according to the present embodiment may be the same as the "organic matter" contained in the organic matter-containing water described above. Moreover, the amount of organic matter that can be added at one time when adding the organic matter directly to the nutrient solution containing the inorganic nutrient solution is 10 g or less in dry weight conversion per 1 L of the nutrient solution. EXAMPLES

[0034] The present embodiment will be specifically described below with reference to examples.

[0035] Example 1: Production example of inorganic nutrient solution (20 L x 3 tanks) (1) Device configuration Fig. 1 is a schematic diagram of an inorganic nutrient solution manufacturing apparatus 1 of this embodiment. As shown in Fig. 1, three 20 L capacity plastic open cylindrical tanks are arranged in series, designated from the left (upstream) side as a first decomposition tank 11, a second decomposition tank 12, and a third decomposition tank 13. The first decomposition tank 11 and the second decomposition tank 12, and the second decomposition tank 12 and the third decomposition tank 13 are connected in series via pipes 21 and 22 (inner diameter 8 mm), respectively.

[0036] The first decomposition tank 11 is provided with a supply unit 4 for supplying organic matter-containing water (bonito broth) from above. The supply unit 4 is connected to a tank of bonito broth and a water pipe, and can supply the bonito broth at a desired concentration by appropriately diluting it with tap water.

[0037] When the bonito broth supplied from the supply unit 4 to the first decomposition tank 11 reaches a certain water level, it is transferred through piping 21 to the second decomposition tank 12. Furthermore, when the bonito broth reaches a certain water level in the second decomposition tank 12, the organic matter-containing water is transferred through piping 22 to the third decomposition tank 13. In this way, the bonito broth is transferred successively from the first decomposition tank 11, which is the most upstream, to the second decomposition tank 12 and the third decomposition tank 13, which are downstream. The piping 21 and 22 are arranged so as to be located below the liquid level in the decomposition tanks.

[0038] Each decomposition tank is equipped with an air supply unit (air pump) 5 and a solid carrier 6 on which nitrifying microorganisms are immobilized, in order to efficiently decompose the bonito broth under aerobic conditions using nitrifying microorganisms. Sanbreo (registered trademark) (Asahi Kasei Home Products, Inc.) was used as the solid carrier 6. Sanbreo (registered trademark) is a polyvinylidene chloride fiber that is crimped into a sphere with a diameter of about 2 cm and connected in a rosary shape. Since it has a high porosity and specific surface area, it has high adhesion properties for microorganisms and excellent breathability. The air pump 5 was placed at the bottom of the decomposition tank so that air could be supplied to the entire tank. Since Sanbreo (registered trademark) has a high specific gravity and sinks in water, one end of the solid carrier 6 was fixed to the top of the decomposition tank, and the other end was placed so as to hang down along the inner wall of the decomposition tank.

[0039] An outlet 3 for inorganic nutrient solution generated by the decomposition of organic matter in each decomposition tank is provided at the top of the third decomposition tank 13, which is located at the most downstream position. Overflow is allowed to flow out from this outlet 3, so that the decomposition solution flows in one direction from the left (upstream) side to the right (downstream) side through the pipes 21 and 22 connecting the decomposition tanks.

[0040] (2) Method for producing inorganic nutrient solution Next, an inorganic nutrient solution was produced using the inorganic nutrient solution production apparatus 1 described above in (1). In this example, the bonito broth used was a by-product (concentrated product with a nitrogen concentration of 6%) produced during the process of bonito production at a bonito factory in Yaizu City.

[0041] First, nitrifying microorganisms were immobilized on the solid carrier 6 in the following procedure according to the method described in the aforementioned Patent Document 2. First, Sanbreo (registered trademark) and water were placed in a 20 L container, and bonito broth was added to a final concentration of 1 g / L. 5 g / L of soil was added as a source of microorganisms. The container was aerated with an air pump while culturing at a water temperature of 32°C. When the ammonium ion concentration reached 20 mg / L or less and the nitrate ion concentration reached 150 mg / L or more, it was deemed that the nitrifying microorganisms had been immobilized on the carrier, and the culturing was terminated.

[0042] Next, 1 L of inorganic nutrient solution previously produced in the same manner as in this example was added as seed bacteria for nitrifying microorganisms to each decomposition tank of the inorganic nutrient solution producing apparatus 1, and aeration was started with the air pump 5. The air supply rate of the air pump 5 to each decomposition tank was set to 4 L / min. 118 g (about 1 L) of the solid carrier 6 on which the nitrifying microorganisms were immobilized as described above was added to each decomposition tank.

[0043] The supply unit 4 started adding organic matter-containing water containing bonito broth at a concentration of 1 g / L to the first decomposition tank 11 at a flow rate of 10 L / day (April 12, 2022, "220412" (same below) in Figures 3A-C). Thereafter, as shown in Figures 3A-C, the concentration of the bonito broth added was gradually increased up to a maximum of 7 g / L. The flow rate was slowed to 7 L / day on August 5, 2022. The water temperature in each decomposition tank was kept constant at 35°C. The ion concentrations of ammonium ions, nitrite ions, and nitrate ions in each decomposition tank were measured almost every day.

[0044] (3) Results and Discussion The measurement results are shown in Figures 3A, 3B, and 3C. Figure 3A is a graph showing the daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the first decomposition tank 11, the second decomposition tank 12, and the third decomposition tank 13.

[0045] As shown in Fig. 3A, when the concentration of added bonito broth was up to 2g / L, nitrification also progressed in the first decomposition tank 11, and the nitrate ion concentration reached 296mg / L. However, when the concentration of bonito broth reached 4g / L or more, nitrite and nitrate were not generated, and decomposition was limited to ammonia, and the ammonium ion concentration stabilized at approximately 220mg / L at 4g / L of bonito broth and 400mg / L at 7g / L of bonito broth.

[0046] As shown in FIG. 3B, in the second decomposition tank 12, nitrification proceeded without any problems even when the concentration of added bonito broth was 4 g / L, and the nitrate ion concentration reached 567 mg / L. When the concentration of bonito broth was increased to 7 g / L, nitrate production decreased and the nitrite ion concentration increased, but when the flow rate was reduced to 7 L / day on August 5, 2022, nitrate production recovered and the nitrate ion concentration reached 1005 mg / L.

[0047] As shown in FIG. 3C, stable nitric acid production proceeded in the third decomposition tank 13, and the nitrate ion concentration reached 148 mg / L when the concentration of added bonito broth was 1 g / L, 348 mg / L when it was 2 g / L, 612 mg / L when it was 4 g / L, and 1005 mg / L when it was 7 g / L.

[0048] From the above results, it was found that according to the method disclosed herein, when the concentration of added bonito broth is 4 g / L, 10 L of inorganic nutrient solution containing 600 mg / L of nitric acid can be continuously produced every day, and when the concentration of added bonito broth is 7 g / L, 7 L of inorganic nutrient solution containing 1000 mg / L of nitric acid can be continuously produced every day.

[0049] Example 2: Production example of inorganic nutrient solution (2 tons x 3 tanks) (1) Device configuration Fig. 2 is a schematic diagram of the inorganic nutrient solution manufacturing apparatus 1 of this embodiment. As shown in Fig. 2, three 2-ton open cylindrical plastic tanks are arranged in series, designated as a first decomposition tank 11, a second decomposition tank 12, and a third decomposition tank 13 from the left (upstream) side on the page.

[0050] The first decomposition tank 11 is provided with a supply unit 4 for supplying organic matter-containing water (bonito broth) from above. Each decomposition tank is equipped with an air supply unit (air pump) 5, and among them, the second decomposition tank 12 and the third decomposition tank 13 are equipped with a solid carrier 6 on which the nitrifying microorganisms used in Example 1 are immobilized.

[0051] An outlet 3 for the inorganic nutrient solution is provided at the top of the third decomposition tank 13, which is located at the most downstream position. The overflow is allowed to flow out from this outlet 3, so that the decomposition treatment solution flows in one direction from the left (upstream) side to the right (downstream) side through the pipes 21 and 22 connecting the decomposition tanks.

[0052] (2) Method for producing inorganic nutrient solution Next, an inorganic nutrient solution was produced using the inorganic nutrient solution production apparatus 1 described above in (1). In this example, the bonito broth used was a by-product (concentrated product with a nitrogen concentration of 6%) produced during the process of bonito flakes production at a bonito flakes factory in Makurazaki City. The solid carrier 6 on which the nitrifying microorganisms were immobilized was prepared in the same manner as in Example 1.

[0053] First, 2 L of inorganic nutrient solution, which had been produced in advance in the same manner as in this example, was added as seed bacteria for nitrifying microorganisms to each decomposition tank of the inorganic nutrient solution producing apparatus 1, and aeration was started with the air pump 5. The air supply rate by the air pump 5 to each decomposition tank was set to 150 L / min. 2360 g (about 20 L) of the solid carrier 6 on which the nitrifying microorganisms were immobilized as described above was added to each of the second decomposition tank 12 and the third decomposition tank 13.

[0054] The supply unit 4 started adding organic matter-containing water containing bonito broth at a concentration of 1.2 g / L to the first decomposition tank 11 at a flow rate of 500 L / day (October 6, 2022, "2022 / 10 / 6" (same below) in Figures 4A-C), and the concentration of bonito broth was increased to 2.4 g / L from October 25, 2022. The water temperature of each decomposition tank was kept constant at 25 ° C for the first decomposition tank 11 and 35 ° C for the second decomposition tank 12 and the third decomposition tank 13. The ion concentrations of ammonium ions, nitrite ions, and nitrate ions in each decomposition tank were measured almost every day.

[0055] (3) Results and Discussion The measurement results are shown in Figures 4A, 4B, and 4C. Figure 4A is a graph showing the daily changes in the concentrations of ammonium ions (-x-), nitrite ions (-△-), and nitrate ions (-O-) in the first decomposition tank 11, the second decomposition tank 12, and the third decomposition tank 13.

[0056] 4A, the ammonium ion concentration was the highest throughout the test period in the first decomposition tank 11. When the concentration of added bonito broth was 1.2 g / L, nitrite production also began to progress in the first decomposition tank 11, but when the concentration of bonito broth was increased to 2.4 g / L, the production stopped at the stage of ammonia production.

[0057] 4B, in the second decomposition tank 12, nitrification proceeded without any problems even when the concentration of added bonito broth was 2.4 g / L, and the nitrate ion concentration reached 300 mg / L. Nitrite eventually decreased below the detection limit, and the ammonium ion concentration on the final day, November 22, 2022, was 36.2 mg / L.

[0058] As can be seen from Figure 4C, stable nitric acid production proceeded in the third decomposition tank 13, and the nitrate ion concentration reached a maximum of 221 mg / L. The reason why the nitrate ion concentration is slightly lower than that in the second decomposition tank 12 is thought to be because the decomposition tanks are large, and it takes some time for the nitrate ion concentration in the third decomposition tank 13 to reach that of the second decomposition tank 12.

[0059] From the above results, it was found that according to the method of the present disclosure in which multiple decomposition tanks are connected together, nitrification can be carried out without problems even in the 2-ton decomposition tanks 11-13, and when the concentration of the added bonito broth is 2.4 g / L, 500 L of inorganic nutrient solution containing 200 mg / L of nitrate can be continuously produced every day.

[0060] Although the embodiments and examples of the present disclosure have been described in detail above with reference to the drawings, the specific configurations are not limited to these, and design changes that do not deviate from the gist of the present disclosure are included in the present disclosure.

[0061] For example, in the above examples, an embodiment has been described in which a solid carrier made of polyvinylidene chloride fibers is used as a solid carrier for immobilizing nitrifying microorganisms, but the present disclosure is not limited to this, and any solid carrier having breathability, such as charcoal, perlite, sand, vermiculite, ceramic, zeolite, glass, rock wool, urethane, nylon, melamine resin, etc., can also be used.

[0062] In addition, in the above examples, an embodiment in which organic matter-containing water is continuously supplied in the supply process is described, but this is not limited to this, and the present disclosure also includes an embodiment in which the supply is intermittent, for example, by supplying continuously for 12 hours and then stopping the supply for 12 hours, or by supplying continuously for only 4 hours a day. [Industrial Applicability]

[0063] The present disclosure allows for the rapid mass production of inorganic nutrient solution derived from organic fertilizer, and even in nutrient culture (hydroponics, culture medium cultivation, drip irrigation) that has mainly been carried out using chemical fertilizers, it is possible to replace the inorganic nutrient solution produced by the present disclosure. The inorganic nutrient solution produced by the present disclosure can be handled in the same way as inorganic nutrient solution using chemical fertilizers, and it is expected that it will be introduced to producers who have been hesitant to use organic fertilizers until now. For the above reasons, the present disclosure can be used in the field of agriculture, particularly in the field of greenhouse cultivation. [Explanation of symbols]

[0064] 3 Outlet 4 Supply section 5 Air supply unit (air pump) 11,12,13 Decomposition tank

Claims

1. A method for producing an inorganic nutrient solution, comprising: a supply step of supplying organic matter-containing water to the most upstream decomposition tank among a plurality of decomposition tanks arranged from upstream to downstream; a decomposition step in which the organic matter contained in the organic matter-containing water is decomposed under aerobic conditions by a group of nitrifying microorganisms in the plurality of decomposition tanks while the organic matter-containing water is transferred sequentially from an upstream decomposition tank to a downstream decomposition tank; A method for producing an inorganic nutrient solution comprising the steps of:

2. 2. The method for producing an inorganic nutrient solution according to claim 1, wherein the decomposition step comprises transferring treated water obtained after the organic matter-containing water has been decomposed in the decomposition tank to a decomposition tank located downstream of the decomposition tank, and decomposing the organic matter remaining in the treated water in the downstream decomposition tank under aerobic conditions by the nitrifying microorganisms living in each of the decomposition tanks.

3. The method for producing an inorganic nutrient solution according to claim 1 , further comprising the step of extracting the inorganic nutrient solution from the most downstream decomposition tank among the plurality of decomposition tanks.

4. The method for producing an inorganic nutrient solution according to claim 1, wherein the volumes of the plurality of decomposition tanks are all 1 to 10,000 L.

5. The amount of the organic matter-containing water supplied per day is 1 to 100% of the volume of the most upstream decomposition tank, and The content of the organic matter in the organic matter-containing water is 0.1 to 100 g / L in terms of dry weight. The method for producing an inorganic nutrient solution according to claim 1 .

6. The method for producing an inorganic nutrient solution according to claim 1, wherein the organic matter has a C / N ratio, which is a content ratio of carbon to nitrogen, of 24 or less.

7. 2. The method for producing an inorganic nutrient solution according to claim 1, wherein the organic matter is one or more organic matter selected from the group consisting of fish broth, corn leachate, oil cake, fish meal, methane digestate, compost, rice bran, soybean flour, soybean meal, plant residue, milk, powdered milk, yeast lees, sake lees, shochu lees, food waste, and livestock manure.

8. The nitrifying microorganisms are The microorganisms include those which perform ammonification and those which perform nitrification, and Immobilized on a breathable fibrous or porous solid carrier; The method for producing an inorganic nutrient solution according to claim 1 .

9. The method for producing an inorganic nutrient solution according to claim 8, wherein the solid carrier is made of one or more materials selected from polyvinylidene chloride fibers, charcoal, perlite, sand, vermiculite, ceramics, zeolite, glass, rock wool, urethane, nylon, and melamine resin.

10. An apparatus for carrying out the method for producing an inorganic nutrient solution according to any one of claims 1 to 9, A plurality of decomposition tanks are arranged from upstream to downstream, Each of the plurality of decomposition tanks is provided with an air supply unit and contains a nitrifying microorganism group; The most upstream decomposition tank among the plurality of decomposition tanks further includes a supply unit to which organic matter-containing water is supplied, The plurality of decomposition tanks are arranged in series such that the organic matter contained in the organic matter-containing water supplied from the supply unit is decomposed under aerobic conditions by the nitrifying microorganisms in each of the decomposition tanks while the organic matter-containing water is sequentially transferred from the most upstream decomposition tank to the downstream decomposition tank. Equipment for producing inorganic nutrient solution.

11. The apparatus for producing an inorganic nutrient solution according to claim 10, comprising the most upstream decomposition tank and two or more decomposition tanks arranged downstream.

12. 11. The apparatus for producing an inorganic nutrient solution according to claim 10, wherein the most downstream decomposition tank among the plurality of decomposition tanks further comprises an outlet for withdrawing the inorganic nutrient solution.

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