Culture medium manufacturing method, culture medium manufacturing device, and cultivation system including the culture medium manufacturing device

Abstract

To prevent the formation of precipitates even if bicarbonate ions are contained in water.SOLUTION: A method for producing culture solution includes: a first step involving the nitrification of water containing bicarbonate ions and ammonium carbonate, leading to the conversion of ammonia nitrogen in the water into nitrate nitrogen and the conversion of bicarbonate ions into carbon dioxide; and a second step involving the addition of a fertilizer component containing at least one element selected from nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper to the water processed in the first step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a method for removing bicarbonate ions from water containing bicarbonate ions, a method for producing nitrogen fertilizer and a nutrient solution including the method, a nutrient solution producing device for producing a nutrient solution by treating water containing bicarbonate ions, and a cultivation system including the nutrient solution producing device. [Background technology]

[0002] Hydroponic cultivation of plants requires the application of fertilizers containing elements essential for plant growth, such as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper. In hydroponic cultivation, chemical fertilizers containing these essential elements are dissolved in water and used as the nutrient solution. The raw water used to prepare the nutrient solution contains bicarbonate ions (HCO3 - When the raw water contains a large amount of bicarbonate ions, the pH of the culture solution increases, which requires complicated pH adjustment and frequent replacement of the culture solution. Therefore, it is recommended to neutralize the raw water with nitric acid or phosphoric acid as a pretreatment to adjust the pH value of the raw water and reduce the bicarbonate ion concentration to about 20 to 50 ppm (see Non-Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "VII Fertilizer and Nutrient Solution Management in Hydroponics", Internet<http: / / www.pref.shizuoka.jp / sangyou / sa-325 / hiryou / documents / sehi16-dai3bu7.pdf> [Non-patent document 2] "Calculation method for hydroponics," Internet<https: / / www.kaneyama.co.jp / image / technical_data / technical_sheet_04.pdf> Summary of the Invention [Problem to be solved by the invention]

[0004] In hydroponic cultivation, bicarbonate ions contained in ammonium carbonate, potassium carbonate, water, etc. not only raise the pH value, but also combine with cations such as calcium ions contained in the nutrient solution to precipitate, causing deposition in the nutrient solution tank or waterway, reducing fertilizer efficiency, degrading the quality of the nutrient solution, clogging or blocking openings and pipes, and increasing management costs, making pretreatment necessary.

[0005] When nitric acid or phosphoric acid is added to raw water as a pretreatment, as in conventional technology, the fertilizer components must be adjusted by subtracting the added nitric acid or phosphate, requiring complex fertilizer calculations.

[0006] In view of these problems, one embodiment of the present invention aims to provide a method for removing bicarbonate ions from water containing bicarbonate ions. Another embodiment of the present invention aims to provide a method for treating water containing bicarbonate ions and a method for producing a culture solution that prevent the formation of precipitates in the culture solution even when bicarbonate ions are contained in the water used to produce the culture solution when carbonates such as ammonium carbonate and potassium carbonate are used in the culture solution, and that does not require complex fertilizer calculations when adjusting the fertilizer. Another embodiment of the present invention aims to provide a culture solution production apparatus that prevents the formation of precipitates even when bicarbonate ions are contained in the water used to produce the culture solution when carbonates such as ammonium carbonate and potassium carbonate are used in the culture solution. [Means for solving the problem]

[0007] One embodiment of the present invention is a method for producing a culture solution that does not require complicated fertilizer calculations and prevents the formation of precipitates even if the raw water contains bicarbonate ions when carbonates such as ammonium carbonate and potassium carbonate are used in the culture solution. -) and ammonium ions in water, thereby converting the ammonium nitrogen to nitrate nitrogen and the bicarbonate ions to carbon dioxide.

[0008] The method for treating water containing bicarbonate ions according to one embodiment of the present invention is to treat bicarbonate ions (HCO - This involves adding ammonium carbonate ((NH4)2CO3) to water containing ammonium nitrate, converting the ammonia nitrogen to nitrate nitrogen and bicarbonate ions to carbon dioxide through nitrification.

[0009] One embodiment of the present invention involves measuring the pH value of a culture solution to which carbonates such as ammonium carbonate or potassium carbonate have been added, or water containing bicarbonate ions, which has been treated by nitrification (treated water), and if the pH value of the culture solution or treated water drops below 4.5, adding at least one of ammonium carbonate ((NH4)2CO3) and carbonates such as potassium carbonate (K2CO3), calcium carbonate (CaCO3), and magnesium carbonate (MgCO3) to the culture solution or treated water to adjust the pH value of the culture solution or treated water to within a range of 4.5 to 6.5. - Nitrification of water containing ammonium carbonate ((NH4)2CO3) can be carried out using nitrifying bacteria.

[0010] The method for producing a culture medium according to one embodiment of the present invention is to add bicarbonate ions (HCO - The method includes a first step in which ammonium carbonate ((NH4)2CO3) is added to water containing bicarbonate ions or a culture solution to which carbonates such as potassium carbonate (K2CO3) have been added, and nitrification is carried out to convert ammonia nitrogen contained in the water containing bicarbonate ions or the culture solution to which carbonates have been added to nitrate nitrogen and convert bicarbonate ions to carbon dioxide; and a second step in which a fertilizer component containing at least one element selected from nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper is added to the treated water from the first step.

[0011] A method for producing a culture medium according to one embodiment of the present invention includes measuring the pH of water during nitrification treatment, and if the pH value of the treated water drops below 4.5, adding at least one of ammonium carbonate ((NH4)2CO3) and carbonates such as potassium carbonate (K2CO3), calcium carbonate (CaCO3), and magnesium carbonate (MgCO3) to the water during nitrification treatment to adjust the pH value of the treated water to a range of 4.5 to 6.5. - Nitrification of water containing ammonium carbonate ((NH4)2CO3) can be carried out using nitrifying bacteria.

[0012] The culture medium producing device according to one embodiment of the present invention is a device for producing bicarbonate ions (HCO - The system includes a pre-treatment section that adds ammonium carbonate ((NH4)2CO3) to water containing ammonium carbonate (NH4)2CO3) or a culture solution to which carbonates such as potassium carbonate (K2CO3) have been added to cause nitrification, thereby converting the ammonia nitrogen contained in the treated water into nitrate nitrogen and converting bicarbonate ions into carbon dioxide, and an adjustment section that adds fertilizer components containing at least one element selected from nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper to the treated water that has undergone the first stage.

[0013] A culture medium producing apparatus according to one embodiment of the present invention may include a pretreatment unit that includes a pH sensor that measures the pH value of the treated water and a first chemical supply unit that adds ammonium carbonate ((NH4)2CO3) to the treated water. The culture medium producing apparatus according to one embodiment of the present invention may also include a control unit that, when the pH sensor in the pretreatment unit measures less than 4.5, adds ammonium carbonate ((NH4)2CO3) from the first chemical supply unit so that the pH value of the treated water is 4.5 or more and 6.5 or less. The pretreatment unit may include at least one or both of an agitation unit that agitates the treated water and an aeration unit that aerates the treated water.

[0014] A hydroponic cultivation system according to one embodiment of the present invention includes a culture solution producing device including a pretreatment unit and an adjustment unit, and a cultivation tank for cultivating plants, and the culture solution is supplied to the cultivation tank from the adjustment unit. [Effects of the Invention]

[0015] According to one embodiment of the present invention, bicarbonate ions (HCO - By adding ammonium carbonate ((NH4)2CO3) to water containing nitrite, or to a culture solution to which carbonates such as potassium carbonate (K2CO3) have been added, it is possible to suppress the rise in pH and remove bicarbonate ions. Furthermore, when using nitrified water as a culture solution, it is possible to suppress the formation of precipitates even when adjusting the solution by adding fertilizer components. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing the configuration of a culture solution manufacturing apparatus according to one embodiment of the present invention. [Figure 2] 1 is a diagram showing the configuration of a hydroponic cultivation system according to an embodiment of the present invention. [Figure 3] 1 is a graph showing changes in pH value of a culture solution used for cultivating a plant, as measured in Example 1. [Figure 4] 1 shows photographs of the state of precipitates in a culture solution used for cultivating plants, as measured in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different forms, and should not be construed as being limited to the description of the embodiments exemplified below. For clarity of explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual form, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals, and detailed descriptions may be omitted as appropriate. Furthermore, the letters "first" and "second" attached to each element are convenient labels used to distinguish each element and have no further meaning unless otherwise specified.

[0018] [First embodiment] 1 shows the configuration of a culture solution production apparatus 100 according to one embodiment of the present invention. The culture solution production apparatus 100 includes a pretreatment unit 102 and an adjustment unit 104. The pretreatment unit 102 has a pretreatment tank 106 in which water (pretreated water 110) for producing nitrogenous fertilizer (or culture solution) is stored. The adjustment unit 104 has an adjustment tank 108 in which fertilizer components and the like are added to the water (pretreated water 110) that has been subjected to a predetermined treatment in the pretreatment tank 106, thereby producing a culture solution 112.

[0019] The pretreatment tank 106 and the adjustment tank 108 are connected by a first pipe 116. A first valve 120 that controls the flow of the solution is provided in the first pipe 116. The flow of pretreated water (pretreated water 110) from the pretreatment tank 106 to the adjustment tank 108 is controlled by opening and closing the first valve 120. The pretreated water 110 may be supplied from the pretreatment tank 106 to the adjustment tank 108 via a pump (not shown), or may be supplied by utilizing the difference in water levels between the two tanks. The culture solution producing apparatus 100 has a control unit 114, and the opening and closing of the first valve 120 may be controlled by a signal output from the control unit 114. The first pipe 116 may also be provided with a filter 118 for removing fine particles.

[0020] The pretreatment tank 106 is supplied with water (raw water: water before treatment) for producing nitrogen fertilizer (or culture solution) from a treated water supply unit 122. There is no limitation on the raw water supplied from the treated water supply unit 122, and various types of water can be used, including river water or groundwater, secondary treated water from domestic wastewater, and industrial wastewater. The raw water supplied from the treated water supply unit 122 contains bicarbonate ions (HCO3 - The treated water supply unit 122 may be connected to a water tank or tank (not shown) that stores raw water.

[0021] The treated water supply unit 122 and the pretreatment tank 106 are connected by piping, and a first water pump 134 and a second valve 128 are provided in the piping path. The supply of raw water from the treated water supply unit 122 to the pretreatment tank 106 is controlled by driving the first water pump 134 and opening and closing the second valve 128. The operation of the first water pump 134 and the opening and closing of the second valve 128 are controlled by the control unit 114.

[0022] Pretreatment tank 106 is connected to first chemical supply unit 124. First chemical supply unit 124 has the function of supplying a first chemical to pretreatment tank 106. In this embodiment, the first chemical is ammonium carbonate ((NH4)2CO3), and may be supplied from first chemical supply unit 124 as an aqueous ammonium carbonate solution. First chemical supply unit 124 may be connected to a first chemical tank (not shown) and configured to supply the first chemical from the first chemical tank.

[0023] The first chemical supply unit 124 and the pretreatment tank 106 are connected by piping. A second water pump 136 and a third valve 130 are provided in the piping path. The supply of the first chemical from the first chemical supply unit 124 to the pretreatment tank 106 is controlled by driving the second water pump 136 and opening and closing the third valve 130. The operation of the second water pump 136 and the opening and closing of the third valve 130 are controlled by the control unit 114. Note that when ammonium carbonate powder is supplied to the pretreatment tank 106, the second water pump 136 is omitted.

[0024] A second chemical supply unit 126 may be connected to the pretreatment tank 106. The second chemical supply unit 126 has the function of supplying a second chemical to the pretreatment tank 106. The second chemical may contain a component that serves as a fertilizer for plants, such as potassium carbonate (K2CO3), calcium carbonate (CaCO3), magnesium carbonate (MgCO3), etc. The second chemical supply unit 126 has one or more chemical supply systems and supplies one or more aqueous solutions selected from potassium carbonate or a potassium carbonate aqueous solution, calcium carbonate or a calcium carbonate aqueous solution, and magnesium carbonate and a magnesium carbonate aqueous solution to the pretreatment tank 106. The second chemical supply unit 126 may be connected to a second chemical tank (not shown) and configured to supply the second chemical from the second chemical tank.

[0025] The second chemical supply unit 126 and the pretreatment tank 106 are connected by piping. A third water pump 138 and a fourth valve 132 are provided in the piping path. The supply of the second chemical from the second chemical supply unit 126 to the pretreatment tank 106 is controlled by driving the third water pump 138 and opening and closing the fourth valve 132. The operation of the third water pump and the opening and closing of the fourth valve 132 are controlled by the control unit 114.

[0026] Nitrifying bacteria are added to the pretreatment tank 106. The nitrifying bacteria are provided in the pretreatment tank 106 directly, together with a carrier containing the nitrifying bacteria, by being contained in sludge or soil. The nitrifying bacteria are added at a volume ratio of 5 to 20%, for example 10%, to the pretreated water 110. FIG. 1 shows an embodiment in which a carrier 146 containing nitrifying bacteria is provided in the pretreatment tank 106. By containing the nitrifying bacteria, the pretreatment tank 106 can nitrify the bicarbonate ions and ammonium carbonate contained in the pretreated water 110. That is, water containing bicarbonate ions and ammonium carbonate can be nitrified by the nitrifying bacteria, converting ammonia nitrogen to nitrate nitrogen and bicarbonate ions to carbon dioxide, which can be used as nitrogen fertilizer components.

[0027] The pretreatment tank 106 is provided with an agitator 140 to promote the reaction caused by nitrifying bacteria in the pretreated water 110. There are no limitations on the type of agitator 140, and for example, a propeller-type agitator can be used. By agitating the pretreated water 110 with the agitator 140, the nitrification reaction can be promoted. Alternatively, instead of the agitator 140, a submersible pump may be installed in the pretreatment tank 106 to circulate the pretreated water 110 within the tank.

[0028] The pretreatment tank 106 may be equipped with an aeration device 142 for aeration. The aeration device 142 is composed of an air pump 143 for supplying air and a microporous body 144 such as an air stone or a micro-nano bubble nozzle. The microporous body 144 is preferably installed at the bottom of the pretreatment tank 106. By supplying air from the bottom of the pretreatment tank 106 using the aeration device 142, it is possible to promote reactions in which ammoniacal nitrogen is converted into nitrate nitrogen, bicarbonate ions are converted into carbon dioxide, and organic matter is oxidized to water and carbon dioxide.

[0029] The pretreatment tank 106 is provided with sensors that detect the state of the pretreated water 110. FIG. 1 shows an example in which a pH sensor 148, an EC sensor 150, and a water level sensor 152 are installed as sensors in the pretreatment tank 106. The pH sensor 148 is installed to measure the pH value of the pretreated water 110. In order to maintain a continuous nitrification reaction, it is preferable that the pH value of the pretreated water 110 in the pretreatment tank 106 be controlled to a range of 4.5 to 6.5. By monitoring the pH value of the pretreated water 110, the pH sensor 148 can carry out the nitrification reaction under appropriate conditions. The measurement value of the pH sensor 148 is output to the control unit 114.

[0030] The EC sensor 150 is used to measure the electrical conductivity of the pretreated water 110. The ion concentration can be evaluated by measuring the electrical conductivity of the pretreated water 110 with the EC sensor 150. Alternatively, a nitrate ion sensor and an ammonium ion sensor may be provided to directly measure nitrate ions and ammonium ions.

[0031] The water level sensor 152 is provided to detect the water level in the pretreatment tank 106. The measurement value of the water level sensor 152 is output to the control unit 114. When raw water is supplied to the pretreatment tank 106, the control unit 114 controls the operation of the treated water supply unit 122 based on the signal from the water level sensor 152, so that the water level does not exceed a predetermined level.

[0032] The adjusting unit 104 is provided with an agitator 141 that agitates the culture solution 112 in the adjusting tank 108, a nutrient solution supplying device 154 that adds fertilizer components to the culture solution 112, a nutrient solution adjusting device 156 that controls the operation of the nutrient solution supplying device 154, and a water level sensor 153. The nutrient solution adjusting device 156 includes sensors (a pH sensor 149 and an EC sensor 151). The nutrient solution adjusting device 156 detects the pH value of the culture solution 112 using the pH sensor 149 and detects the electrical conductivity of the culture solution 112 using the EC sensor 151. Based on the measured values ​​of these sensors, the nutrient solution adjusting device 156 adds fertilizer components, including components such as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper, to the culture solution 112 from the nutrient solution supplying device 154. The adjusting tank 108 is provided with a water supply port 158 ​​through which the stored culture solution 112 is supplied to the outside.

[0033] The control unit 114 controls the operation of the pretreatment unit 102 and the adjustment unit 104, and has the function of collecting data on the pretreated water 110 and the culture solution 112. The control unit 114 also controls the treatment conditions of the pretreated water 110 based on the collected data, and manages the quality of the culture solution 112.

[0034] According to the culture solution production apparatus 100 of this embodiment, raw water (raw water) used to produce nitrogenous fertilizer (or culture solution) can be treated with nitrifying bacteria in the pretreatment unit 102, allowing the use of raw water of various water qualities. That is, even if the raw water contains bicarbonate ions, these can be converted to carbon dioxide. Furthermore, ammonium carbonate contained in the pretreated water 110 can be converted to nitrate nitrogen, which is used as a nitrogenous fertilizer component. This prevents an increase in the pH value of the pretreated water 110 and also prevents the formation of precipitates even when the culture solution is adjusted by adding fertilizer components in the adjustment unit 104. This prevents an increase in the pH value of the culture solution 112 and prevents precipitates from forming in the adjustment tank 108 and depositing in the openings of pipes, etc., causing clogging or blockage.

[0035] [Second embodiment] This embodiment will explain the operation of the culture solution manufacturing apparatus 100 shown in the first embodiment, a method for treating water containing bicarbonate ions using this apparatus, nitrogen fertilizer manufactured by this apparatus, and a method for manufacturing a culture solution.

[0036] In the culture solution production apparatus 100, water (raw water) to be used in the production of nitrogenous fertilizer (or culture solution) is treated in the pretreatment unit 102, and the nitrogenous fertilizer (or culture solution) is adjusted in the adjustment unit 104. First, water is supplied from the treated water supply unit 122 to the pretreatment tank 106. The water supplied to the pretreatment tank 106 is the water to be used in the production of nitrogenous fertilizer (or culture solution). As described in the first embodiment, various types of water (such as wastewater) can be used as this water, and the water may contain bicarbonate ions.

[0037] Simultaneously with or after the supply of raw water from treated water supply unit 122, an aqueous ammonium carbonate solution is supplied from first chemical liquid supply unit 124 to pretreatment tank 106. Nitrifying bacteria, a carrier containing nitrifying bacteria, sludge containing nitrifying bacteria, or soil are added in an amount of 10% or more by volume to pretreated water 110 containing ammonium carbonate and bicarbonate ions introduced into pretreatment tank 106. The nitrifying bacteria, the carrier containing nitrifying bacteria, the sludge containing nitrifying bacteria, or the soil may be placed in pretreatment tank 106 in advance.

[0038] Next, the agitator 140 is operated to agitate the pretreated water 110, promoting the nitrification reaction by the nitrifying bacteria. Aeration using the aeration device 142 may be performed instead of agitation. Aeration of the pretreated water 110 using the aeration device 142 can promote the nitrification reaction by the nitrifying bacteria. Furthermore, the process of reacting the pretreated water 110 with the nitrifying bacteria may involve simultaneous agitation and aeration, or alternating between agitation and nitrification. The pretreated water 110 containing ammonium carbonate and bicarbonate ions is agitated or aerated, or agitated and aerated, to convert the ammonium ions contained in the pretreated water 110 into nitrate ions and the bicarbonate ions into carbon dioxide through nitrification.

[0039] The pH value of the pretreated water 110 is measured by a pH sensor 148 and controlled to be within the range of 4.5 to 6.5. If the pH value falls below 4.5, an aqueous ammonium carbonate solution is added to the pretreated water 110 from the first chemical supply unit 124 to raise the pH value. If the pH value rises above 6.5, the addition of ammonium carbonate is discontinued.

[0040] The nitrification reaction of the pretreated water 110 may be monitored using an EC sensor 150 (or a nitrate ion sensor or an ammonia ion sensor). The quality of the pretreated water 110 can be controlled by adding ammonium carbonate while measuring the electrical conductivity of the pretreated water 110 with the EC sensor 150, and interrupting the addition of ammonium carbonate when the measured value (EC value) of the EC sensor 150 reaches a predetermined value. The level of electrical conductivity control using the EC sensor 150 is determined by the EC value set in the culture solution. For example, if the EC value of the culture solution 112 is to be between 1.5 and 2.0, the addition of ammonium carbonate is interrupted when the EC value of the pretreated water 110 in the pretreatment tank 106 reaches 0.4 dS / m.

[0041] By the above-described treatment, bicarbonate ions can be removed from water containing bicarbonate ions. This water treatment method also allows the pH value of the water from which bicarbonate ions have been removed to be adjusted. In other words, when adding ammonium carbonate to water from which bicarbonate ions are to be removed, the amount of ammonium carbonate added can be controlled so as not to be excessive.

[0042] The water level of the pretreated water 110 in the pretreatment tank 106 is monitored by a water level sensor 152. When the water level in the pretreatment tank 106 drops, raw water (raw water) is supplied from the treated water supply unit 122 until the water level reaches a predetermined level.

[0043] The pretreated water 110, whose pH value has been adjusted to between 4.5 and 6.5 in the pretreatment tank 106, is transferred to the adjustment tank 108. The water level in the adjustment tank 108 is measured by a water level sensor 153, and when the water level in the adjustment tank 108 falls below a predetermined level, the pretreated water 110 is supplied. The opening and closing of the first valve 120 is controlled by a signal output from the control unit 114. The pretreated water 110 is supplied from the pretreatment tank 106 to the adjustment tank 108 through a first pipe 116. The pretreated water 110 is supplied, for example, by utilizing the difference in water level between the pretreatment tank 106 and the adjustment tank 108. When there is a difference in water level between the pretreatment tank 106 and the adjustment tank 108, opening the first valve 120 causes the pretreated water 110 to flow from the pretreatment tank 106 to the adjustment tank 108 through the first pipe 116. Alternatively, a pump (not shown) may be used to pump the pretreated water 110 from the pretreatment tank 106. The pretreated water 110 is supplied to the equalization tank 108 until the water level reaches a predetermined level. The water level of the equalization tank 108 is monitored by a water level sensor 153.

[0044] When pretreated water 110 is supplied from the pretreatment tank 106 to the adjustment tank 108, the stirring, aeration, or stirring and aeration process is stopped for about 5 to 10 minutes, and the pretreated water 110 is then supplied after the solids suspended in the pretreated water 110 have settled. That is, the supernatant of the pretreated water 110 after the stirring, aeration, or stirring and aeration process is transferred to the adjustment tank 108. A first filter 118 is provided in the first piping 116, but if the pretreated water 110 is supplied without the suspended matter settling, the first filter 118 will quickly become clogged, so it is preferable to wait a predetermined time as described above before the pretreated water 110 is supplied.

[0045] When the water level in the pretreatment tank 106 drops, water (raw water) is replenished from the treated water supply unit 122. The amount of replenished water (raw water) is controlled by a water level sensor 152. After the water (raw water) is replenished, the quality of the pretreated water 110 stored in the pretreatment tank 106 is monitored by a pH sensor 148 and an EC sensor 150, and ammonium carbonate is added from the first chemical supply unit 124 as needed. If the pH value is 4.5 or lower, ammonium carbonate is added from the first chemical supply unit 124, and the addition of ammonium carbonate is stopped when the pH value reaches 6.5 or higher. Agitation or aeration, or both agitation and aeration, is performed as appropriate.

[0046] The pretreated water 110 transferred to the adjustment tank 108 contains nitrate nitrogen, which is the result of the nitrification of ammonium carbonate. Therefore, this aqueous solution can be used as nitrogen fertilizer or as a raw material for nitrogen fertilizer.

[0047] Furthermore, by adding fertilizer components to the pretreated water 110 transferred to the adjustment tank 108, a culture solution 112 to be used for plant cultivation can be produced. The pH value and EC value of the culture solution 112 are measured by a pH sensor 149 and an EC sensor 151 connected to a nutrient solution adjustment device 156. The fertilizer components are added to the adjustment tank 108 by a nutrient solution supply unit 154. The fertilizer components include nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, It contains one or more components selected from zinc, molybdenum, nickel, and copper.

[0048] By using the culture solution production apparatus 100 of this embodiment, ammonium carbonate can be added to water containing bicarbonate ions, and nitrification can be performed using nitrifying bacteria to convert the ammonium carbonate to nitrate nitrogen and the bicarbonate ions to carbon dioxide, thereby adjusting the pH value to a range of 4.5 to 6.5. In other words, by nitrifying water containing ammonium carbonate using nitrifying bacteria, a nitrogen fertilizer containing nitrate nitrogen can be produced, and fertilizer components can be added to produce the culture solution 112. Furthermore, by using the culture solution production apparatus 100 of this embodiment, bicarbonate ions can be easily removed from water (raw water) containing carbonate ions and bicarbonate ions, which tend to combine with cations in the culture solution and precipitate. Furthermore, by not using nitric acid, phosphate, etc., complex fertilizer calculations can be eliminated.

[0049] The pretreated water 110 transferred from the pretreatment tank 106 has been treated with nitrifying bacteria, which removes bicarbonate ions, preventing the formation and deposition of precipitates even when fertilizer components such as calcium are added. Furthermore, by converting ammonium carbonate to nitrate nitrogen, the pH value of the culture solution 112 can be adjusted to a range of 4.5 to 6.5, maintaining fertilizer efficiency. Furthermore, by converting ammonium carbonate to nitrate ions, the ammonia ion concentration can be reduced, making it possible to cultivate plants that do not prefer nutrient solutions with high ammonia concentrations.

[0050] [Third embodiment] FIG. 2 shows a hydroponic cultivation system 160 according to one embodiment of the present invention. The hydroponic cultivation system 160 includes the nutrient solution manufacturing apparatus 100 shown in the first embodiment and a cultivation section 161 in which plants are cultivated. Hydroponic cultivation methods are broadly classified into two types: submerged hydroponic cultivation and thin film hydroponic cultivation. FIG. 2 shows an example in which submerged hydroponic cultivation is applied to the cultivation section 161 of the hydroponic cultivation system 160. Of course, thin film hydroponic cultivation can also be applied to the hydroponic cultivation system 160. Since the nutrient solution manufacturing apparatus 100 was explained in the first embodiment and the method for producing a nutrient solution was explained in the second embodiment, the explanation in this embodiment will focus on the parts related to the cultivation tank 162.

[0051] The culture tank 162 is supplied with the nutrient solution 112 from the adjustment tank 108. The nutrient solution 112 is supplied from the adjustment tank 108 to the culture tank 162 by a pump 157. The nutrient solution 112 is supplied to the culture tank 162 through a supply pipe 166. A cultivation panel 164 is installed above the cultivation tank 162. The plants 200 to be cultivated are arranged on the cultivation panel 164 and cultivated so that their roots extend into the cultivation tank 162.

[0052] Fig. 2 shows a hydroponic cultivation system 160 of a circulation type. An overflow pipe 168 is provided in the cultivation tank 162, and a waterway is formed through which the culture solution that has reached a predetermined water level flows out from the overflow pipe 168 and circulates to the adjustment tank 108. Although not shown, the waterway may be provided with a storage tank that temporarily stores the culture solution that has flowed out from the overflow pipe 168. Note that Fig. 2 shows an example in which the cultivation tank 162 has one level, but this is not limiting and the cultivation tank 162 may be arranged in multiple levels.

[0053] In the adjustment tank 108, fertilizer components necessary for hydroponic cultivation are added to the culture solution from a nutrient solution supply unit 154. In addition, in the adjustment tank 108, the pH value is measured by a pH sensor 149, and the EC value is measured by an EC sensor 151, and the water quality is controlled so that it falls within a range suitable for the culture solution 112. When the water level in the adjustment tank 108 drops, treated pretreated water 110 is supplied from the pretreatment tank 106. In this way, the amount of culture solution 112 is controlled in the adjustment tank 108, and the amount of the decrease is supplied from the pretreatment tank 106, allowing hydroponic cultivation to be carried out continuously.

[0054] According to the hydroponic cultivation system 160 of this embodiment, raw water of various qualities can be used by treating the water (raw water) used to produce the culture solution with nitrifying bacteria. That is, even if the raw water contains bicarbonate ions, these can be converted to carbon dioxide. Furthermore, ammonium carbonate contained in the pretreated water 110 can be converted to nitrate nitrogen, which can be used as a nitrogen fertilizer component. Even when fertilizer components are added to the culture solution in the adjustment unit 104 to produce the culture solution 112, the formation of precipitates can be suppressed. This prevents the deposition of precipitates in water channels such as the adjustment tank 108 and the supply pipe 166, causing clogging and blockage. [Example]

[0055] 10 shows the change in pH value of the culture solution when a plant is grown using a culture solution produced by the production method shown in the second embodiment and a normal culture solution.

[0056] Hydroponic cultivation was performed using the irrigation method. The cultivation was performed indoors on a cultivation rack with artificial lighting. Container lettuce was grown as the plant. Four types of nutrient solution were used.

[0057] The culture medium and its composition are as follows: Sample A: Culture solution prepared by generating nitrate ions from ammonium carbonate Sample B: The nutrient solution was first prepared using nitrate ions generated from ammonium carbonate, and then ammonium carbonate was used to prepare the nutrient solution when top dressing was applied. Sample C: Comparative example, culture solution made from chemical fertilizer Sample D: Comparative example, culture solution in which ammonium carbonate was used to prepare the culture solution

[0058] The graph in Figure 3 shows the change in pH value of the culture solution when container lettuce was grown using Sample A and Sample B. The graph in Figure 3 also shows the results for Comparative Examples Sample C and Sample D. Cultivation was carried out twice over a 43-day cultivation period, with the first period being from the 1st to the 22nd day and the second period being from the 22nd to the 43rd day.

[0059] When the culture solutions of Samples A and B were used, the pH value remained within the range of 5 to 7 during the first and second periods of container lettuce cultivation, with no significant fluctuations observed. On the other hand, when the culture solution of Sample C, a comparative example, was used, a significant increase in the pH value was observed after moving from the first period to the second period. A significant increase in the pH value was also observed in the culture solution of Sample D, a comparative example.

[0060] The significant change in pH value in comparative sample C is thought to be the result of the container lettuce absorbing a large amount of specific components contained in the nutrient solution, causing the ion balance in the nutrient solution to change from its initial state. The change in pH value of comparative sample C, which increased to 7 or more, is thought to be the result of, for example, components such as nitrate nitrogen contained in the nutrient solution being absorbed, causing OH from the roots. - It is assumed that this is the result of the excretion of H. When a component such as ammonia nitrogen is absorbed, the roots + The pH value drops as the nitrification proceeds. In contrast, the pH values ​​of the culture solutions of Samples A and B in the examples are stabilized at between 4.5 and 6.5 due to nitrification by the nitrifying bacteria. Furthermore, the presence of an adequate amount of ammonia nitrogen in the culture solution provides a good balance between the absorption of nitrate nitrogen and ammonia nitrogen by the plants, which is thought to prevent abrupt changes in the pH value. Furthermore, the remaining nitrifying bacteria nitrify the ammonia nitrogen and act as a buffer, which is thought to prevent abrupt changes in the pH value.

[0061] Thus, according to this example, it was confirmed that when a culture solution pretreated with nitrifying bacteria was used, a sudden change in pH value was suppressed. [Example]

[0062] The culture solutions of Samples A and B used in Example 1 and the culture solutions of Samples C and D used as comparative examples were observed for the presence or absence of precipitates after 43 days of use.

[0063] The culture broth of samples A and B was clear and no precipitates were observed. On the other hand, precipitates were observed in the culture broth of samples C and D, which are comparative examples. These results confirmed that treating pretreated water with nitrifying bacteria removes carbonate ions and bicarbonate ions, preventing the formation of precipitates due to reaction with fertilizer components.

[0064] As described above, Examples 1 and 2 confirmed that using nitrifying bacteria to remove ammonium carbonate and bicarbonate ions contained in the pretreated water stabilizes the pH value of the culture solution and prevents the formation of precipitates. [Explanation of symbols]

[0065] 100: culture medium producing apparatus, 102: pretreatment unit, 104: adjustment unit, 106: pretreatment tank, 108: adjustment tank, 110: pretreated water, 112: culture medium, 114: control unit, 116: first piping, 118: first filter, 120: first valve, 122: treated water supply unit, 124: first chemical supply unit, 126: second chemical supply unit, 128: second valve, 130: third valve, 132: fourth valve, 134: first water pump, 136: second water pump, 138: third water pump, 140: agitator, 1 41: Agitator, 142: Aeration device, 143: Air pump, 144: Microporous body, 146: Carrier containing nitrifying bacteria, 148: pH sensor, 149: pH sensor, 150: EC sensor, 151: EC sensor, 152: Water level sensor, 153: Water level sensor, 154: Nutrient solution supply unit, 156: Nutrient solution adjustment device, 157: Pump, 158: Water supply port, 160: Hydroponic cultivation system, 161: Cultivation unit, 162: Cultivation tank, 164: Cultivation panel, 166: Supply pipe, 168: Overflow pipe, 200: Plant

Claims

1. a first stage of nitrifying water containing bicarbonate ions and ammonium carbonate to convert ammonia nitrogen contained in the water into nitrate nitrogen and bicarbonate ions into carbon dioxide; a second step of adding a fertilizer component containing at least one element selected from nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper to the water that has been subjected to the first step.

2. 2. The method for producing a culture medium according to claim 1, wherein the pH of the water is measured, and if the pH value of the water falls below 4.5, at least one carbonate of ammonium carbonate and potassium carbonate is added to the water to adjust the pH value of the water to within a range of 4.5 to 6.

5.

3. The method for producing a culture medium according to claim 1 or 2, wherein the nitrification is carried out by nitrifying bacteria.

4. 4. The method for producing a culture medium according to claim 1, wherein the first step is carried out in a first treatment tank, the water that has undergone the first step is supplied to a second treatment tank, and the second step is carried out in the second treatment tank.

5. a pre-treatment section that nitrifies water containing bicarbonate ions and ammonium carbonate to convert ammonia nitrogen contained in the water into nitrate nitrogen and bicarbonate ions into carbon dioxide; and an adjusting unit that adds a fertilizer component containing at least one element selected from nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, iron, manganese, zinc, molybdenum, nickel, and copper to the water supplied from the pretreatment unit.

6. 6. The culture medium producing apparatus according to claim 5, wherein the pretreatment section includes a pH sensor that measures a pH value of the water, and a first chemical supply section that adds ammonium carbonate to the water.

7. 7. The culture solution producing apparatus according to claim 6, further comprising a control unit that adds ammonium carbonate from the first chemical supply unit so that the pH value of the water is 4.5 or more and 6.5 or less when the measured value of the pH sensor is less than 4.

5.

8. The culture medium producing apparatus according to claim 6 , wherein the pretreatment section further includes a second chemical supply section that adds a carbonate to the water.

9. The culture medium producing apparatus according to claim 5 , wherein the pre-treatment section includes at least one of an agitation section that agitates the water and an aeration section that aerates the water.

10. The culture solution producing apparatus according to any one of claims 5 to 9, a cultivation tank for cultivating plants; Including, A cultivation system, characterized in that a culture solution is supplied to the cultivation tank from the adjustment unit.

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