JPH10245291A - Production apparatus for liquid fertilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production apparatus capable of efficiently treating excreta of domestic animal by a series of processes and extremely reducing a running cost, equipped with a decomposing tank containing a fine foam generating part and a coarse foam generating part and a concentrating tank containing a foam generating part for evaporation so as to decompose excreta of domestic animal with a bacterium to form a liquid fertilizer. SOLUTION: A decomposing tank 2 for decomposing an organic substance in excreta of domestic animal with a bacterium to give a liquid fertilizer comprising an inorganic substance consisting essentially of fertilizer three components of nitrogen, phosphoric acid and potassium and other organic substance component is equipped with an air spraying pipe 4 for supplying a fine foam, a heating element 5 for heating water, an air spraying pipe 21 for generating a coarse foam so as to circle and recycle a liquid in the tank so that the air spraying pipe 21 is crossed to the air spraying pipe 4. The treated solution is overflown from the decomposing tank 2 to a second decomposing tank 6 having the same functions, then overflown to a concentrating tank 11 equipped with a foam generating part 13 for evaporation and a heating element 14 and the decomposed solution is concentrated to give a liquid fertilizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid fertilizer manufacturing apparatus capable of manufacturing liquid fertilizer (hereinafter sometimes abbreviated as "liquid fertilizer") using livestock excrement as a raw material.

[0002]

2. Description of the Related Art A garbage disposal apparatus for treating garbage in water has been known. For example, utility model registration 3
In the registered publication of No. 0123267, a bubbler having a sintered element stretched is provided at a lower position of a garbage disposal basket in water,
There is disclosed a garbage disposal apparatus that decomposes garbage in water by supplying oxygen necessary and sufficient for the growth and decomposition of bacteria attached to the garbage in water by a large number of fine air bubbles blown out from a bubbler.

[0003]

However, with the above-mentioned conventional garbage processing apparatus, it is not possible to process livestock excreta into liquid fertilizer concentrated in a series of steps. However, there is a problem that the liquid fertilizer cannot be efficiently concentrated. Further, the conventional processing device for garbage or the like has a problem that it is difficult to commercialize the production of liquid fertilizer using livestock due to high running costs such as electricity costs.

[0004] The present invention has been made in view of such problems of the prior art, and it is possible to efficiently process livestock excreta into concentrated liquid manure in a series of steps, and to improve the quality of the livestock. It is an object of the present invention to provide a liquid fertilizer manufacturing apparatus capable of greatly reducing the running cost for processing human waste into a concentrated liquid fertilizer as compared with the related art.

[0005]

The liquid fertilizer manufacturing apparatus according to the present invention for solving the above-mentioned problems is characterized in that nitrogen, phosphoric acid, A decomposition tank for producing a liquid fertilizer containing an inorganic substance mainly composed of minerals such as calcium and three components of potassium fertilizer and other organic substances, for supplying oxygen necessary for the growth of the bacteria to the bacteria. A decomposition tank including a microbubble generating section for generating microbubbles having a relatively small diameter and a coarse bubble generating section for generating coarse bubbles having a relatively large diameter for swirling and circulating a liquid, A concentration tank for concentrating the liquid fertilizer obtained in the tank, comprising a concentration tank including an evaporating bubble generation unit for generating evaporating bubbles for evaporating the liquid fertilizer. Than it is.

In the liquid fertilizer manufacturing apparatus according to the present invention, the evaporating air bubble generator generates air bubbles from a position closer to the liquid surface than a position between the bottom of the concentrating tank and the surface of the liquid fertilizer. There should be. Further, in the liquid fertilizer manufacturing apparatus according to the present invention, the microbubble generating section for decomposing may include air supplied for generating normal air bubbles every predetermined number of micro air bubbles or every predetermined time. It is preferable to provide a clogging prevention unit for supplying high-pressure air whose pressure is at least twice as high as the pressure. Further, in the liquid fertilizer production apparatus according to the present invention, the decomposition tank has a coarse bubble generation section for generating coarse bubbles having a relatively large diameter for rotating and circulating water containing bacteria in the decomposition tank. It is preferable that the coarse-bubble generating section generates coarse-bubble bubbles from a position closer to the liquid surface than an intermediate position between the bottom in the decomposition tank and the liquid surface. Further, in the liquid fertilizer production apparatus according to the present invention, the coarse bubble generating section and the fine bubble generating section are preferably arranged such that the generated bubbles cross each other on a plane.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the entire configuration of a liquid fertilizer manufacturing apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. 1 and 2, reference numeral 1 denotes a stock solution tank.
Livestock excrement, which is a raw material of liquid fertilizer, is put in this. The human waste from the stock solution tank 1 is sent to the next first decomposition tank 2 at a rate of about 5 tons per day.

The first decomposition tank 2 is made of concrete or an iron plate on which a heat insulating material is adhered to the outside, and is water-resistant. The first decomposition tank 2 contains water containing aerobic bacteria. Also, at the bottom of the first decomposition tank 2,
An air diffuser 4 for supplying minute air bubbles to the water is provided. This air diffuser 4 is, for example, 10 to 50
It is made of a porous substance such as a rod-shaped sintered alloy of liter / mim / m. The mechanism in which minute bubbles are generated from the diffuser 4 is that air is supplied from the aeration fan 20 to the diffuser 4 (hollow body) via the pipe 20a, and the supplied air is converted from the sintered alloy. By being pushed out of the small opening (hole) of the diffuser tube 4 to the outside, minute bubbles are generated.

Further, a heating element 5 for warming water to a predetermined temperature for activating bacteria in the water is provided in the first decomposition tank 2. The heating element 5 may be constituted by a heater or the like.
As shown in the figure, the kerosene-fired hot water boiler 5a
When hot water is sent through a pipe, heat is generated. In addition, as shown in FIG.
At the bottom of the decomposition tank 6, the entire liquid inside is convected.
A diffuser tube 21 for generating coarse-grained bubbles for generating coarse-grained bubbles having a relatively large diameter for swirling and circulation (2 to 8 m
(a structure in which a through hole nozzle having a diameter of m is opened) is provided.
As shown in FIG.
The air diffuser 4 for generating microbubbles for supplying oxygen to the bacteria is provided at the bottom of the second decomposition tank 6 so as to cross each other in a plane. That is, the diffuser tube 4 and the diffuser tube 21 for generating coarse particles are arranged at the bottom of the second decomposition tank 6 so as to be orthogonal to each other. With this cross arrangement, the microbubbles for supplying oxygen to the bacteria and the coarse bubbles for convection / circulation of the liquid can sufficiently exhibit their functions independently without interfering with each other. In addition, the operation of supplying oxygen to the bacteria and the operation of circulating the liquid coexist and are efficiently performed. In FIG. 2, a cross-sectional view of the second decomposition tank 6 (a cross-sectional view taken along line AA in FIG. 1).
However, in the present embodiment, the first
Similarly, also at the bottom of the decomposition tank 2, a diffuser tube for generating coarse bubbles is arranged crosswise to the diffuser tube 4 for generating fine bubbles.

Next, human waste is supplied from the stock solution tank 1 to the first decomposition tank 2 at a predetermined pace. When this human waste is supplied, the liquid in which the water and human waste in the first decomposition tank 2 are mixed overflows by a predetermined amount, and the next second decomposition tank 6
Go to To perform this overflow well,
In the first embodiment, the upper part of the wall surface between the first decomposition tank 2 and the second decomposition tank 6 (for example, 6,0
The overflow opening 7 is formed at a height of 00 mm to 2,500 mm). In the second decomposition tank 6 as well, in the same manner as in the first decomposition tank 2, water containing bacteria, an air diffuser 8 for generating bubbles for supplying oxygen to the bacteria, and an air diffuser 8 for activating the bacteria. A heating element 9 for heating water to a predetermined temperature is provided.

Next, when the liquid from the first decomposition tank 2 overflows from the overflow opening 7 and moves to the second decomposition tank 6, the liquid in the second decomposition tank 6 is further reduced by the overflow opening. It overflows from 10 and moves to the next maturation / concentration tank 11. This aging
In the concentration tank 11 as well as in the first decomposition tank 2 and the second decomposition tank 6, a diffuser tube 1 for generating water containing bacteria and bubbles for supplying oxygen to the bacteria.
And a heating element 14 for heating the liquid to a predetermined temperature in order to activate bacteria.

The liquid aged and concentrated in the maturation / concentration tank 11 is converted into a liquid fertilizer through a pipe 22 through a product tank 23.
Is stored in. The liquid fertilizer stored in the product tank 23 is used as a composting accelerator sprayed on the compost, fine particle compost, liquid fertilizer for a sprayer, and the like. In addition, the first described above
As shown in FIG. 2, each of the decomposition tank 2, the second decomposition tank 6, and the aging / concentration tank 11 has a structure in which the upper part is closed by a pneumatic dome roof.

Next, the operation of the first embodiment will be described.
First, the behavior in the first decomposition tank 2 will be described. In the first decomposition tank 2, fibers (straw, sawdust, etc. laid on a livestock floor), inorganic substances (digested), organic substances (undigested), etc., are converted into ammonia (NH ₃ ). Furthermore, it is decomposed into nitrite (NO ₂ ⁻ ). That is, in the first decomposition tank 2, the organic matter in the human waste is separated from oxygen supplied by aeration from the bottom of the first decomposition tank 2 (generation of microbubbles from the air diffuser 4) and aerobic bacteria (bacteria). Is decomposed into nitrous acid or oxidized to nitrite via ammonia. In addition, the water flow generated by the rise of the coarse bubbles from the coarse bubble generating air diffuser 21 breaks the pseudo-lumps into pseudo particles, increasing the specific surface area and easily decomposing the remaining organic matter.

Next, the behavior in the second decomposition tank 6 and the aging / concentration tank 11 will be described. This second decomposition tank 6
In the aging / concentration tank 11, the pseudo particles such as NO ₂ ⁻ , organic phosphorus (P), and organic potassium generated in the first decomposition tank 2 are decomposed to nitrate NO ₃ ⁻ and phosphate HP.
It is broken down (to remove ammonia nitrogen) into a suspension containing three components of fertilizer such as O ₄ ²⁻ and potassium salt K ⁺ . That is, in the second decomposition tank 6, nitrite is oxidized to nitric acid by the action of a further aerobic bacterium (bacteria), and dissolves inorganic substances such as calcium to nitrate. Phosphorus similarly dissolves as a phosphate (becomes easier to be absorbed). Pseudo-particles are almost crushed and suspended, and do not deposit on product tanks, pipes, decomposition tank bottoms, or the like.

The suspension treated as described above contains three components of nitrogen N, phosphoric acid P ₂ O ₅ , potassium K ₂ O, and inorganic and other organic components mainly composed of minerals such as calcium. This liquid fertilizer does not contain ammonia nitrogen, NH ₃ -N or various bacteria. This liquid fertilizer contains bacteria grown by eating organic matter (MLSS = 10,000-
(30,000 mg / l), high activity, no germs or odor.

Finally, the post-treatment of the manufactured liquid fertilizer will be described. Second decomposition tank 6 and aging / concentration tank 11
Is filtered and separated into dehydrated slag and filtrate. Of these, dehydrated slag is used as fine compost, and the filtrate is used, for example, as a liquid fertilizer for a sprayer (used for golf course turf, etc.).

Embodiment 2 FIG. Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic diagram showing the entire configuration of the second embodiment, and FIG. 3 and 4, the same reference numerals are given to the same parts as those in FIGS. 1 and 2, and the description will be omitted. In the second embodiment, in order to mainly reduce the running cost in the liquid fertilizer production plant, the following several devices are added. First, in the second embodiment, a microbubble for supplying oxygen to bacteria, which is provided at the bottom of each of the first decomposition tank 2, the second decomposition tank 6, and the maturation / concentration tank 11 in FIG. The air diffusers 4, 8, 13
Compared to a conventional device (for example, generating a bubble having a diameter of 15.0 mm), it is configured to generate a bubble having a diameter (for example, a bubble having a diameter of 1.0 mm) which is about 15 times smaller than that of a conventional apparatus. As described above, when the bubbles generated from the air diffusers 4, 8, and 13 are made minute, the following advantages are obtained. That is, in general, the amount of air for supplying dissolved oxygen (oxygen dissolved in water) D ₀ required for the growth of bacteria is a static condition, and the following formula 1 is satisfied in the case of water where D ₀ = 0.

(Equation 1) DO ₂ = DO ₁ × K × (specific surface area) ^1/3 × (rise rate ratio) ¹ As shown in the following Table 1, the specific surface area of the bubbles decreases as the bubble diameter decreases. growing.

[0019]

[Table 1]

From the above equation 1 and Table 1, for example, 15.0
In contrast to the conventional apparatus that generates coarse-grained bubbles having a small specific surface area of 400 m ² / m ³ with a diameter of mm, in the second embodiment, for example, microbubbles having a large specific surface area of 6000 m ² / m ³ with a diameter of 1.0 mm , As shown in FIG.
The amount of air required for supplying oxygen to the bacteria is reduced to about one third of that of the conventional apparatus, and the running cost such as the cost of electric power can be greatly reduced.

Then, in the conventional apparatus, the second embodiment is used.
Did not small bubbles with a large specific surface area be generated like this? The reason is that, as shown in Table 1, if the bubble diameter is, for example, about 15.0 mm, the nozzle (downward bowl type nozzle) that generates bubbles will not be blocked by human waste or the like. For example, when it is as small as 1.0 mm, a nozzle that generates air bubbles (a diffuser 4, 8, 1 in FIG. 3)
This is because the third bubble generation hole) is closed by human waste or the like. In other words, it has been known that generating bubbles with a small diameter saves power in the past, but in the past, if bubbles were formed with a small diameter, the opening (hole) of the nozzle would be clogged. Large bubbles were generated. Thus, in the second embodiment, it is possible to generate bubbles having a small diameter by taking the following countermeasures against nozzle blockage.

FIG. 6 shows a device for removing clogging (pulse backwash) provided in the air diffusers 4, 8, and 13 according to the second embodiment. In FIG. 6, reference numeral 30 denotes the microbubble generating air diffusers 4, 8 and
An aeration fan for sending air for aeration to 13, an air reservoir for storing high-pressure air for backwashing, a bebicon for supplying high-pressure air for backwashing to the air reservoir, 33 Is an electromagnetic valve for opening and closing between the air reservoir 31 and the air diffusers 4, 8, and 13, and 34 is such that the electromagnetic valve 33 is normally closed, for example, and is opened once a day for 5 seconds. A timer for providing time data of the clock to the microcomputer 34; a check valve 36 for preventing high-pressure air from the air reservoir 31 from flowing back to the aeration fan 30; is there. In the clogging removing device configured as described above, the microcomputer 3 is operated, for example, once a day for 5 seconds.
The electromagnetic valve 33 is opened by 4 and the high-pressure air from the air reservoir 31 is supplied to the air diffusers 4, 8 and 13 in a pulsed manner. By this operation, fine particles of human urine which are attached to the surface of the fine nozzles of the diffuser tubes 4, 8, and 13 and grow and solidify and are becoming tightly clogged are blown off. Clogging is prevented or eliminated.

As described above, in this embodiment, the air diffusion tubes 4, 8, and 13 are provided with the clogging removing device, so that the bubbles generated from the air diffusion tubes are reduced in diameter and large in specific surface area. It becomes possible to do. Therefore, the running cost for supplying oxygen to the bacteria can be significantly reduced as compared with the conventional case.

Next, in the second embodiment, as shown in FIG. 4, the liquid in the first decomposition tank 2 and the second decomposition tank 6 is used to generate coarse bubbles for convection, swirling and circulation. The coarse bubble nozzle 41 is arranged at a position closer to the liquid surface than the intermediate position between the bottom surfaces of the decomposition tanks 2 and 6 and the liquid surface (liquid surface). To occur. At the same time, guide vanes 42, 43 for guiding and guiding the liquid so as to be easy to convection, swirl, and circulate are provided near the liquid surface of the decomposition tanks 2, 6. In the second embodiment, as described above, the coarse bubble nozzle 41 is provided at a position close to the liquid surface for the following reason. That is, generally, the following equation 2 holds for the power.

(Equation 2) Electric power (KW) = wind pressure (mmAg) × air volume (m ³ / m ² )}
(6120 x efficiency)

In general, as for the wind pressure for generating bubbles in water, the lower the water depth, the lower the wind pressure (low water depth = low wind pressure). Therefore, if the same bubble is generated, the power consumption is smaller and the running cost can be reduced when the bubble is generated from a position where the water depth is low, that is, a position close to the liquid surface.

Next, in the second embodiment, there is provided an aerator for generating bubbles for concentration by evaporating the liquid in the aging / concentration tank 11. This aeration apparatus comprises an evaporating / concentrating air diffuser 15 and a floating body 16 for supporting the air diffuser 15 near the liquid surface. The evaporating / concentrating air diffuser 15 is provided at a position near the liquid level,
In order to evaporate the water of the liquid (particularly the liquid surface or a portion close to the liquid surface), bubbles are generated. As shown in FIG. 3, the air diffuser 15 is always kept at a constant depth from the liquid level at a position not far from the liquid level (that is, a shallow layer position) by a floating body 16 floating on the liquid level. It is arranged at the position of the. The liquid evaporates from the water surface by the bubbles from the air diffuser 15. The vapor generated by the evaporation is discharged to the outside by an exhaust fan 18 via an exhaust duct 17.

In the second embodiment, as described above, the evaporation / concentration air diffuser 15 is supported at a position near the liquid level by the floating body 16 for the following reason. That is, generally, the following equation 2 holds for the power.

(Equation 2) Electric power (KW) = wind pressure (mmAg) × air volume (m ³ / m ² ) ÷
(6120 x efficiency)

In general, as for the wind pressure for generating bubbles in water, the lower the water depth, the lower the wind pressure (low water depth = low wind pressure). Therefore, the floating body 16
And the level difference (water depth) between the liquid level and the air diffuser 15
Is maintained at a constant small value irrespective of a change in the liquid level, so that low loss = low power is realized. That is, in the second embodiment, the water depth up to the bottom of the aging / concentrating tank 11 is 2,500 mm.
When aeration is performed from the bottom of the liquid, the water column becomes large and the power consumption also increases. Therefore, in the second embodiment, by providing the shallow aeration device composed of the air diffuser 15 and the floating body 16, it is possible to perform aeration from a position where the water depth is low near the liquid surface. Compared with the case where aeration is performed from the bottom of the concentration tank 11, the wind pressure for aeration can be reduced. Therefore, according to the second embodiment, the running cost (power consumption) for aeration for evaporating / concentrating the liquid in the aging / concentrating tank 11 is significantly reduced.

In FIG. 3, reference numeral 51 denotes a supply / exhaust heat exchanger for exchanging heat between the exhaust gas (about 40 ° C.) from the aging / concentration tank 11 and the supply air, and 52 denotes a supply / exhaust liquid. And a heat exchanger for supplying and discharging liquid for preheating the human waste in the stock solution tank 1.

Finally, Table 2 below compares the running cost of the liquid fertilizer manufacturing apparatus according to the second embodiment with that of the conventional liquid fertilizer manufacturing apparatus. As shown in Table 2, in the present embodiment 2, by providing (1) a device for removing clogging of a diffuser tube as described above, bubbles are reduced in diameter for supply of oxygen to bacteria and have a small specific surface area. (2) Aeration for convection, swirling, and circulation of the liquid in the decomposition tanks 2 and 6 should be performed in a shallow layer near the liquid surface, Guide vanes 42 and 43 for guiding convection, swirling and circulation are provided. (3) A diffuser tube 15 used for aeration for evaporating and condensing liquid in the aging / concentration tank 11 is floated by a floating body 16. By adding some contrivances such as support at a nearby shallow layer, it has become possible to greatly reduce the running cost as compared with the conventional apparatus.

[0033]

[Table 2]

[0034]

As described above, in the liquid fertilizer manufacturing apparatus according to the present invention, the liquid fertilizer containing three components of nitrogen, phosphoric acid and potassium fertilizer, particularly the concentrated liquid Since fertilizer can be manufactured, it is possible to efficiently perform effective treatment of human waste.

Further, in the liquid fertilizer manufacturing apparatus according to the present invention, bubbles for liquid evaporation for concentrating the liquid fertilizer are formed from a position closer to the liquid surface than a position between the bottom and the liquid fertilizer surface in the concentration tank. Since it is generated, the running cost (power consumption) for generating the evaporating bubbles can be significantly reduced.

In the liquid fertilizer manufacturing apparatus according to the present invention, in order to prevent clogging of the microbubble generating portion for supplying oxygen to the bacteria, a pulse is generated every predetermined number of times of generation of bubbles or every predetermined time. In addition, high-pressure air whose pressure is at least twice as high as the supply of air for generating normal air bubbles is supplied. Therefore, clogging is prevented even if minute bubbles are generated. By generating minute bubbles, the running cost (power consumption) for generating bubbles for supplying oxygen to bacteria is reduced as compared with the related art. It can be greatly reduced.

Further, in the liquid fertilizer manufacturing apparatus according to the present invention, the decomposition tank is provided with coarse bubbles for convection, swirling, and circulating the liquid containing bacteria in the decomposition tank. Since the gas is generated from a shallow layer position closer to the liquid surface than an intermediate position between the surface and the surface, the running cost (power consumption) for generating the coarse bubbles can be significantly reduced.

Further, in the liquid fertilizer manufacturing apparatus according to the present invention, the microbubble generator for supplying oxygen to the bacteria and the coarse bubble generator for swirling and circulating the liquid are arranged so as to cross each other. Therefore, the generation of microbubbles for supplying oxygen to the bacteria and the generation of coarse bubbles for swirling and circulation of the liquid can be efficiently performed without interfering with each other.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic diagram illustrating an overall configuration of a second embodiment of the present invention.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a diagram for explaining the merits of an evaporating / concentrating air bubble generator (shallow diffuser) according to the second embodiment.

FIG. 6 is a schematic diagram showing a configuration of a device for removing clogging of a microbubble generating air diffuser used in Embodiment 2.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 stock solution tank 2 first decomposition tank 4,8,13 diffuser tube for generating microbubbles 5,9,14 heating element 5a kerosene-fired hot water boiler 6 second decomposition tank 10 overflow opening 11 maturation / concentration tank 15 dispersion for evaporation / concentration Trachea 16 Floating body 17 Exhaust duct 18 Exhaust fan 20a. Reference Signs List 22 piping 20 and 30 aeration fan 21 diffuser tube for generating coarse bubbles 23 product tank 31 air reservoir 32 bebicon 33 solenoid valve 34 microcomputer 35 timer 36 check valve 41 coarse bubble nozzle 41 51 supply / exhaust heat exchanger 52 supply / discharge Liquid heat exchanger

Claims (5)

[Claims] 1. A liquid fertilizer containing three components of fertilizers of nitrogen, phosphoric acid and potassium, an inorganic component mainly composed of calcium, and other organic components by decomposing organic matter therein by bacteria from animal waste. A microbubble generating section for generating microbubbles having a relatively small diameter for supplying oxygen necessary for the growth of the bacteria to the bacteria, and a swirling / circulating liquid in the decomposition tank. A decomposition tank including a coarse-bubble generating section for generating coarse-grained bubbles having a relatively large diameter; and a concentration tank for concentrating the liquid fertilizer obtained in the decomposition tank, wherein the liquid fertilizer is evaporated. A liquid fertilizer production apparatus, comprising: a concentration tank including an evaporating bubble generation unit that generates evaporating bubbles for causing the liquid to be evaporated. 2. The liquid fertilizer manufacturing apparatus according to claim 1, wherein the evaporating air bubble generation unit generates microbubbles from a position closer to the liquid surface than a position between the bottom of the concentration tank and the surface of the liquid fertilizer. A liquid fertilizer production device, characterized in that: 3. The liquid fertilizer production apparatus according to claim 1, wherein the microbubble generator for decomposition is pulsed at predetermined time intervals, compared with air supplied for generating normal air bubbles. A liquid fertilizer production device comprising a clogging prevention unit for supplying high-pressure air whose pressure is at least twice as high. 4. The method according to claim 1, wherein the coarse-bubble generating section provided in the decomposition tank is more liquid than an intermediate position between a bottom in the decomposition tank and a liquid surface. A liquid fertilizer manufacturing device that generates coarse bubbles from a position near the surface. 5. The liquid fertilizer production apparatus according to claim 4,
The coarse-grained bubble generator and the microbubble generator are mutually
A liquid fertilizer production apparatus, wherein bubbles generated by each of the liquid fertilizers are arranged so as to cross on a plane in the decomposition tank.