JP2002137979A - Method of manufacturing liquefied fertilizer for nourishing solution vegetation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently manufacture a liquefied fertilizer for nourishing solution vegetation from organic waste. SOLUTION: An organic waste is subjected to methane fermentation under anaerobic condition, and the liquefied fertilizer for nourishing solution vegetation is obtained from supernatant liqueur obtained by desorbing generated gas ingredient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a liquid fertilizer used in a hydroponic method without using soil, and more particularly to a method for producing a liquid fertilizer for hydroponic culture from organic wastes such as kitchen waste and livestock waste. About the method.

[0002]

2. Description of the Related Art In recent years, hydroponic cultivation methods that do not use soil have become widespread in Japan as a method for efficiently mass-producing crops such as vegetables. Generally, in the nutrient solution cultivation method, a nutrient solution obtained by dissolving a fertilizer component in water is circulated to a cultivation bed, but the nutrient solution does not contain solids, and the fertilizer component is in the form of ions or chelates that can be directly absorbed by the cultivated crop from the root. Must be present in nutrient solution. Chemical fertilizers are easy to handle and present in nutrient solutions in the form of ions and chelates, and are widely used in hydroponic cultivation methods.

Recently, however, many chemical fertilizers have been supplied by importing inexpensive foreign products. Regardless of soil cultivation or nutrient cultivation, crops cultivated with imported chemical fertilizers accumulate as organic waste after consumption as kitchen waste and the like as livestock manure. Such accumulation of organic waste is circulated by rain, groundwater, etc., and ultimately stays in the soil as a nitrogen component, which is one of the causes of an increase in environmental load such as excessive nitrogen in domestic soil. . For this reason, it is recommended that organic waste such as kitchen waste and livestock excreta discharged in large quantities be recycled as fertilizer as much as possible.

Conventionally, methods for treating organic waste include methods such as incineration, landfill, composting, and fermentation with aerobic fermenters. However, incineration generally generates toxic chemicals, and landfills and aerobic fermentation processes cause the proliferation of pathogenic organisms such as cryptospores and 0-157 bacteria, and the health damage to nearby residents due to emission of ammonia odor and putrefaction odor. There are problems such as the spread of disease and disgust. The storage and treatment of manure in dry lagoons, such as those found in dairy farms, can also cause odor problems, and when rainwater flows into these treatment facilities, pathogenic organisms such as cryptospores overflow and spread to the surrounding environment.

[0005] On the other hand, composting has a problem that the production process is complicated, the facility load is increased due to an increase in capacity due to the input of auxiliary materials, and furthermore, the application of immature compost to agricultural lands promotes anoxic state of the soil and the growth of crops. There are also problems such as the generation of inhibitors. Therefore, recently, a method of methane fermentation in an anaerobic state has attracted attention as a method of treating organic waste. In this method, a liquid containing organic waste (organic matter-containing liquid) is introduced into a closed fermenter, where the organic matter is fermented by an anaerobic methane bacterium to desorb methane-based gas components. In this method, the remaining liquid is converted into liquid fertilizer. The generated gas component is stored in a gas tank or the like and is used as a heating fuel or the like. The method of methane fermentation in such an anaerobic state has an advantage that since organic waste is treated in a closed fermenter, it does not cause a problem of spreading bad smell or pathogenic organisms around.

[0006]

Hitherto, there has been no effective use of the desorbed solution produced by methane fermentation in an anaerobic state except for spraying it as liquid fertilizer on soil. However, when the desorbed liquid is applied to the soil as liquid fertilizer, a large amount of liquid fertilizer is required as a whole to apply the required amount to the farmland of a certain level of management scale. It is necessary to set up storage facilities. Further, in order to transfer a large amount of liquid fertilizer from the production facility for the desorbed liquid to the storage facility, it is necessary to provide a transfer means such as a dedicated large tank lorry.

On the other hand, if there is no agricultural land or storage facility that accepts the desorbed liquid as liquid fertilizer in an area where it can be economically transported from the desorbed liquid production facility, secondary treatment such as discharging the river after some detoxification treatment is performed. Requires measures. However, the detoxification process has a problem that it requires the same equipment and cost as public sewage treatment. Therefore, the present inventors, as a result of various studies,
Considering many facilities, it has been found that as a liquid fertilizer to be used for hydroponic cultivation methods that can be consumed in large quantities, a desorbed solution obtained by methane fermentation in an anaerobic condition that is environmentally superior in terms of production is effective as a whole. Thus, the present invention has been completed.

[0008]

That is, the present invention provides an anaerobic methane fermentation of an organic waste, and a liquid fertilizer for hydroponics from a desorbed liquid obtained by desorbing a gas component produced. A method for producing a liquid fertilizer for hydroponics, which is a feature of the present invention (claim 1). According to the present invention, since a process for producing a liquid fertilizer for hydroponics from a desorbed solution produced by subjecting organic waste such as kitchen waste to methane fermentation in an anaerobic state is adopted, the environment is polluted during the production process. There is no danger. Then, the desorbed liquid used as liquid fertilizer in the hydroponics can be reduced as organic waste to the liquid fertilizer production process, so that an organic substance cycle can be formed and the amount of discharged to the environment can be suppressed. Further, the desorbed liquid for nutrient solution cultivation is an organic substance, and can avoid various problems caused by the use of chemical fertilizer. Furthermore, since the consumption of the desorbed liquid can be increased, a river discharge facility or the like becomes unnecessary.

[0009] In the above method, a liquid fertilizer for hydroponics can be obtained by removing solids from the desorbed liquid (claim 2). By removing solids contained in the desorbed liquid in this way, problems such as closing pipes and nozzles of the hydroponic cultivation equipment can be avoided. In any of the above methods,
The liquid fertilizer for hydroponics can be obtained by removing the organic acid from the desorbed solution (claim 3). By removing organic acids such as volatile organic acids contained in the desorbed solution, it is possible to suppress the occurrence of factors that inhibit the growth of crops, such as fermentation in a nutrient solution and an anoxic condition.

[0010] In any of the above methods, a liquid fertilizer for hydroponics can be obtained by further adding another fertilizer component to the desorbed liquid. Thus, by adding another fertilizer component, the ratio of nitrogen, phosphorus, potassium, magnesium, and the like in the liquid fertilizer for hydroponics can be optimally adjusted. When adding the fertilizer component, the fertilizer component can be made not to contain calcium (claim 5). When the concentration of liquid fertilizer increases, calcium reacts with other substances to promote its precipitation, which causes problems such as closing pipes and nozzles of the hydroponic cultivation equipment. However, this can be avoided by the above method. In any one of the above methods, the desorbed solution can be further concentrated to obtain a liquid fertilizer for hydroponics (Claim 6). When the desorbed liquid is concentrated in this way, the transfer and storage of the desorbed liquid to the nutrient cultivation facility become easier.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a process flow diagram for implementing the method of the present invention. 1 is a closed type methane fermentation tank, 2 is a desorbed liquid storage tank for storing the desorbed liquid generated in the methane fermentation tank 1,
Reference numeral 3 denotes a transfer pump, 4 denotes a storage tank for storing a nutrient solution of desorbed liquid or its slurry, such as a lagoon, manual bag, or slurry tank, 5 denotes a mixing tank, 6 denotes a stirring device, and 7 denotes a hopper that stores a flocculant. , 8 is a transfer pump, 9 is a pressurized levitation tank, 10 is a pressurizing device for supplying pressurized fine bubbles to the pressurized levitation tank 9, 11 is pressurized air for pressurized levitation and treated A mixing pressurized tank for mixing water, 12 is a temporary storage tank, 1
3 is a transfer pump, 14 is an upflow anaerobic sludge bed tank, 15 is a biogas tank for storing biogas produced by methane fermentation in the upflow anaerobic sludge bed tank 14, 16 is a temporary storage tank, 17 is Stirring device, 18 is a transfer pump, 19 is a microfiltration device, 20 is a temporary storage tank, 21 is a transfer pump, 22 is a reverse osmosis membrane device for concentrating fertilizer components, 23 and 24 are filling devices, and 25 is a liquid fertilizer cubbiter filling. Product, 26 is a product filled with cubbiter of filtered water, V1 to V7 are on-off valves, R
1, R2 is a check valve, and a to o2 are pipes.

The methane fermentation tank 1 is connected to a pipe for introducing a nutrient solution or slurry for organic waste (not shown) and a pipe for discharging generated gas, and further provided with a stirring device for stirring the inside. The nutrient solution or the slurry-like desorbed liquid generated in the methane fermentation tank 1 overflows from the pipe a and is stored in the desorbed liquid storage tank 2. The desorbed liquid in the desorbed liquid storage tank 2 is pumped up by the transfer pump 3 and supplied to the mixing tank 5 via the pipes b1, b2, and b5. In the normal operation of supplying the desorbed liquid to the mixing tank 5, the on-off valves V1 and V2 are opened, and V3 and V4 are closed. The storage tank 4 is used to temporarily store the desorbed liquid when the processing capacity of the desorbed liquid is temporarily reduced, or to use a part of the desorbed liquid as an excess product to open another valve from the on-off valve V6. It is used when supplying to a facility (for example, a facility for shipping for soil application), in which case the on-off valve V2 is closed and the on-off valve V3 (or V5, V6) is opened. When replenishing liquid is supplied from the storage tank 4 to the mixing tank 5, the on-off valve V4 is opened.

In the mixing tank 5, the desorbed liquid is diluted with water from the pipe c so as to have a concentration (or viscosity) suitable for the subsequent step, and a pH adjuster is supplied from the pipe d to supply the pH adjuster.
Adjust the value. Generally, the pH value of the desorbed solution obtained by methane fermentation is neutral to weakly alkaline, so that a pH adjuster such as phosphoric acid or sulfuric acid is added, and the subsequent coagulation sedimentation step or upward flow The pH value is adjusted to a pH value suitable for the anaerobic sludge bed method (the former is based on a precipitant and the latter is neutral to weakly alkaline). Further, in the mixing tank 5, a coagulating sedimentation agent is supplied from the hopper 7 to precipitate and separate the solid content in the desorbed liquid.
The flocculant to the hopper 7 is supplied from the pipe e. As the coagulating sedimentation agent, a calcium-based coagulating sedimentation agent, for example, Manited Inc. Ecogaia W commercially available from Com. Can be used. The precipitated solid is discharged from the bottom of the mixing tank 5 to the outside through a drain pipe (not shown) or the like. The discharged solid can be returned to the methane fermentation tank 1.

The desorbed liquid whose concentration and pH have been adjusted in the mixing tank 5 and further the solid content has been separated is transferred to a pipe f by a transfer pump 8.
To the pressurized flotation tank 9 where the solids remaining in the desorbed liquid are separated by flotation with fine bubbles, and the piping g3
Is returned to the methane fermentation tank 1 by a pipe (not shown).
The air bubbles for floating are supplied from the pipe i2 after the pressurized air generated by the pressurizing device 10 and the desorbed liquid (water to be treated) from the pipe g1 are mixed in the mixing and pressurizing tank 11.

The desorbed liquid treated in the pressurized flotation tank 9 is connected to a pipe g
2 to the temporary storage tank 12 and then to the transfer pump 13
Is supplied to the upward-flowing anaerobic sludge bed tank 14 through a pipe g4 provided. In the upward anaerobic sludge bed tank 14, the anaerobic methane bacteria decomposes and removes organic acids contained in the desorbed solution by methane fermentation. The biogas mainly composed of methane gas generated in the upward flow anaerobic sludge bed tank 14 is stored in the biogas tank 15 via the pipe h1. On the other hand, the desorbed liquid from which the organic acid has been removed in the upward anaerobic sludge bed tank 14 overflows from the pipe h2 and flows out to the temporary storage tank 16. In the temporary storage tank 16, other fertilizer components, for example, a phosphate fertilizer, a potassium fertilizer, and further a magnesium fertilizer are added from the pipe i, and the ratio of nitrogen, phosphorus, potassium, magnesium and the like in the desorbed liquid is used as a liquid fertilizer for nutrient cultivation. Adjust to the desired range. However, when the desorbed liquid is within the range of the fertilizer component required for the liquid fertilizer for hydroponics, this fertilizer addition step is omitted.
In the temporary storage tank 16, the internal nutrient solution is maintained in a uniform state by the stirring device 17.

The liquid desorbed from the temporary storage tank 16 is supplied to a microfiltration device 19 by a pipe j1, a transfer pump 18 and a pipe j2, where the remaining solids and bacteria are further separated and removed. The microfiltration device 19 has a filter such as a hollow fiber module or a flat membrane module having a pore diameter of 0.1 μm, and solids and bacteria are separated by the pressure filtration action of the filter. Removed solids etc. can be properly turned on / off valve V7
Is opened and discharged from the pipe l, and returned to the methane fermentation tank 1. The desorbed liquid from which solids and bacteria have been removed by the microfiltration device 19 is transferred to a temporary storage tank 20 via a pipe k1, and further supplied to a reverse osmosis membrane device 22 by a pipe k2, a transfer pump 21 and a pipe k3. The reverse osmosis membrane device 22 separates water from the desorbed liquid by the separation action of the reverse osmosis membrane and concentrates the fertilizer component.

The desorbed liquid in which the fertilizer components are concentrated is supplied as liquid fertilizer for nutrient cultivation from a pipe n to a filling device 23, where it is successively filled into containers of an appropriate volume and shipped as a liquid fertilizer cubittainer-filled product 25. Is done. The separated filtered water is supplied from a pipe o1 to a filling device 24, where it is similarly filled one after another in containers of an appropriate volume, and shipped as a cubbiter filled product 26 of the filtered water. The filtered water is used, for example, as dilution water for adjusting the concentration of liquid fertilizer for hydroponics. Further, at least a part of the filtered water can be supplied from the pipe o2 to the mixing tank 5, and used as a part of the dilution water for diluting the desorbed liquid. Note that the above series of processing steps is desirably performed continuously, but may be performed batchwise.

[0018]

EXAMPLE A liquid fertilizer for hydroponic cultivation was produced from the detached liquid using an experimental apparatus having the same flow as the process flow of FIG. 10% of the desorbed solution obtained by methane fermentation with dilution water
, And a calcium-based coagulant / precipitant was added so as to have a concentration of 0.9% with respect to the desorbed solution after dilution. In this state, the pH value of the desorbed solution dropped from 7.2 to 7.0, so that no pH adjuster was particularly added. Next, the desorbed liquid subjected to the precipitation treatment of the solid content is treated with floating fine bubbles to further remove the remaining solid content, and then the BOD load is 0.5 g / L by an upward anaerobic sludge bed method. -Organic acids were removed under day conditions. At that time, biogas having a concentration of 45 ml / g · BOD · day was produced at a ratio of methane to carbon dioxide of 6: 4. On the other hand, the pH value of the treated effluent was 7.
5. Total organic acid concentration is less than 3mg / l, BOD is 10mg
/ L.

Next, another fertilizer component was added to the desorbed solution from which the organic acid had been removed, and the fertilizer component ratio of nitrogen, phosphorus, potassium, and magnesium was adjusted to 7: 2: 4: 2. When the concentration of liquid fertilizer increases, calcium component reacts with other substances, such as phosphoric acid, to promote precipitation, and causes problems such as closing pipes and nozzles of the hydroponic cultivation equipment. Next, the desorbed liquid prepared from the fertilizer component was subjected to microfiltration, and the SS concentration was set to 0.
Purification was performed to less than 1 mg / L, followed by reverse osmosis membrane treatment to obtain concentrated liquid fertilizer and filtered water at a weight ratio of 1:25. There were no emissions or releases to the environment, which were particularly problematic. Using the liquid fertilizer thus obtained, a nutrient solution for hydroponics was adjusted, and a crop was grown while circulating the nutrient solution. The growing condition of the crop was very good, and no clogging occurred in the pipes and supply nozzles through which the nutrient solution flows.

[0020]

As described above, in the method for producing a liquid fertilizer for hydroponics according to the present invention, methane fermentation of an organic waste is carried out in an anaerobic state, and a gas component produced is desorbed from the desorbed liquid. It is characterized by obtaining liquid fertilizer for hydroponics. Therefore, the following effects are obtained. There is no risk of polluting the environment during the manufacturing process. The desorbed liquid used as liquid fertilizer in the hydroponics can be reduced as an organic waste to the liquid fertilizer production process, so that an organic substance cycle can be formed and the amount of discharged to the environment can be suppressed. The liquid used for hydroponic cultivation is an organic substance, and can avoid various problems caused by the use of chemical fertilizers. Since the consumption of desorbed liquid can be increased, river discharge facilities are not required.

In the above method, a solid fertilizer for hydroponic cultivation can be obtained by removing solids from the desorbed liquid, thereby avoiding problems such as closing pipes and nozzles of the hydroponic cultivation equipment. Furthermore, in any of the above methods, it is possible to obtain a liquid fertilizer for hydroponics by removing organic acids from the desorbed solution,
As a result, it is possible to suppress the occurrence of factors that inhibit crop growth, such as fermentation in a nutrient solution and anoxic condition.

Further, in any of the above methods, a liquid fertilizer for hydroponics can be obtained by adding another fertilizer component to the desorbed liquid, whereby the ratio of nitrogen, phosphorus, potassium, magnesium, etc. in the liquid fertilizer can be reduced. It can be adjusted optimally. When adding the above fertilizer component, the fertilizer component can be made to contain no calcium component, so that even if the liquid fertilizer concentration increases, it does not react with other substances and promote its precipitation, so that Problems such as closing pipes and nozzles can be avoided. Furthermore, in any one of the above methods, the desorbed liquid can be further concentrated to obtain a liquid fertilizer for hydroponic cultivation, whereby the transfer and storage of the desorbed liquid to the hydroponic cultivation facility become easier.

[Brief description of the drawings]

FIG. 1 is a process flow chart for implementing a method for producing a liquid fertilizer for hydroponics according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Methane fermentation tank 2 Desorption liquid storage tank 3 Transfer pump 4 Storage tank 5 Mixing tank 6 Stirrer 7 Hopper 8 Transfer pump 9 Pressurized floating tank 10 Pressurizing device 11 Mixing pressurized tank 12 Temporary storage tank 13 Transfer pump 14 Countercurrent anaerobic sludge bed tank 15 Biogas tank 16 Temporary storage tank 17 Stirrer 18 Transfer pump 19 Microfiltration device 20 Temporary storage tank 21 Transfer pump 22 Reverse osmosis membrane device 23 Filling device 24 Filling device 25 Liquid fertilizer cubbiter filling product 26 Filtration Water Cubtainer Filled Products V1-V7 On-off valves R1, R2 Check valves a-o2 Piping

Claims (6)

[Claims] 1. A liquid fertilizer for hydroponic cultivation, wherein an organic waste is subjected to methane fermentation in an anaerobic state, and a liquid component for hydroponic cultivation is obtained from a desorbed liquid obtained by desorbing generated gas components. Production method. 2. The method for producing a liquid fertilizer for hydroponic cultivation according to claim 1, wherein a solid content is removed from the desorbed liquid to obtain a liquid fertilizer for hydroponic cultivation. 3. The method for producing a liquid fertilizer for hydroponic cultivation according to claim 1, wherein the organic acid is removed from the separated liquid to obtain a liquid fertilizer for hydroponic cultivation. 4. The method for producing a liquid fertilizer for hydroponic cultivation according to claim 1, wherein another fertilizer component is further added to the separated liquid to obtain a liquid fertilizer for hydroponic cultivation. 5. The method for producing liquid fertilizer for hydroponics according to claim 4, wherein the added fertilizer component does not contain calcium. 6. The method for producing a liquid fertilizer for hydroponics according to claim 1, wherein the liquid obtained is further concentrated to obtain a liquid fertilizer for hydroponics.