Manufacturing method of solid raw material

Abstract

To provide a manufacturing method of solid raw material that can efficiently utilize effluent obtained after decomposing and treating used disposable diapers and subsequently collecting recycle resources and that can easily generate solid raw material from the effluent.SOLUTION: A manufacturing method of solid raw material includes: a separation process 1 of agitating used disposable diapers together with a process liquid using a separator and decomposing and treating it to obtain components constituting disposable diapers; a classification process 2 of performing classification using a classifier 10 into pulp 8 and plastic in the solid constituents separated in the separation process 1; a first pulp recovery process 4 of collecting the pulp 8 from a first effluent 3 that is the liquid component separated in the separation process 1; a dehydration process 6 of separating solid components and liquid components in a second effluent 5 obtained after collecting the pulp 8 in the first pulp recovery process 4; and a drying process 7 of drying the solid components separated from the second effluent 5 in the dehydration process 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing a solid raw material for producing a raw material for solid fertilizer or solid fuel from solid components contained in a waste liquid after decomposition treatment of used paper diapers. [Background technology]

[0002] In October 2022, the government announced a policy to promote domestic production of chemical fertilizers by getting serious about using sludge from sewage treatment as fertilizer, aiming to avoid the financial pressure on farmers and rising food prices caused by the soaring cost of chemical raw materials. The government has also announced a policy to compile a policy for using sewage sludge as fertilizer for agriculture, encouraging the national and local governments to use sewage sludge as fertilizer, and reducing dependence on chemical fertilizer raw materials imported from abroad.

[0003] Furthermore, in July 2022, the GX Executive Council, chaired by the Prime Minister, was held to consider necessary measures to transition the economy, society, and industrial structure, which have been centered on fossil fuels since the Industrial Revolution, to a clean energy-centered one, thereby implementing a transformation of the entire economic and social system, in other words, GX (Green Transformation).

[0004] The conference outlined the roles and direction of efforts of the relevant parties in expanding the use of sewage sludge as fertilizer. It also stated that with the aim of domestically producing fertilizer, ensuring a stable supply, and building a resource-circulating society, the Ministry of Agriculture, Forestry and Fisheries, the Ministry of Land, Infrastructure, Transport and Tourism, the agricultural sector, and the sewerage sector will work together to ensure safety and quality, while also promoting understanding, including among consumers, and that all relevant parties will take the initiative in making all-out efforts to significantly expand the use of sewage sludge as fertilizer.

[0005] Meanwhile, Patent Document 1 proposes decomposing used paper diapers, which have come into widespread use in recent years, and recovering the materials that make up the paper diapers as recyclable resources (pulp, plastic, etc.). In addition to the materials that make up the paper diapers, used paper diapers contain feces and urine excreted from the human body, and the discharged liquid after the used paper diapers are decomposed with a treatment liquid contains feces and urine.

[0006] Used paper diapers are decomposed using processing liquid, and the wastewater after the recyclable resources are recovered is treated and then ultimately discharged into the sewer system. After being treated at a sewage treatment plant, it is then released into the natural environment, such as rivers and the ocean.

[0007] Incidentally, the wastewater discharged after decomposing used disposable diapers and recovering recyclable resources contains feces and urine discharged from the human body, which contains nutrients beneficial to the soil (nitrogen, phosphorus, potassium). In addition, the solid components (scum) extracted from the wastewater can be compressed and molded to become the raw material for solid fuel.

[0008] Therefore, Patent Document 2 discloses that used disposable diapers are finely crushed in a crusher, then mixed with water in a water mixing tank, and the suspended matter (solid matter) suspended in a settling tank is used as a soil conditioner, fertilizer, etc. The aqueous liquid from which the suspended matter has been removed is then subjected to sewage treatment and discharged into the sewer system. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-121699 [Patent Document 2] JP 2004-25574 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, in Patent Documents 1 and 2, although the wastewater after the decomposition process of used paper diapers (the wastewater after the recycling resources are recovered) contains nutrients that are beneficial to the soil, this wastewater is treated and then wastedly discharged into the sewer system, and is not used effectively, which is an issue.

[0011] In addition, the wastewater discharged into the sewer system and discharged to the sewage treatment plant is mixed with other sewage sludge to become sewage sludge, and when this sewage sludge is used as fertilizer, it needs to be disinfected and sterilized to remove bacteria, etc., because it contains things other than feces and urine discharged from the human body. Therefore, when using sewage sludge as fertilizer, processes such as disinfection and sterilization are required, and there is an issue that it cannot be easily manufactured into fertilizer.

[0012] Therefore, the present invention aims to provide a method for producing solid raw materials that can effectively utilize the wastewater remaining after decomposing used paper diapers and recovering recyclable resources, and that can easily produce solid raw materials from the wastewater. [Means for solving the problem]

[0013] In order to solve the above-mentioned problems and achieve the object, a first aspect of the present invention is characterized by comprising a separation process in which used paper diapers are stirred in a separator with a processing liquid to decompose and process the components that make up the paper diapers; a sorting process in which the solid components pulp and plastic separated in the separation process are sorted in a sorting machine; a pulp recovery process in which pulp is recovered from the discharged liquid, which is the liquid component separated in the separation process; a dewatering process in which the solid components and liquid components in the discharged liquid after the pulp has been recovered in the pulp recovery process are separated; and a drying process in which the solid components separated from the discharged liquid in the dewatering process are dried.

[0014] A second aspect of the present invention is characterized by comprising a solid raw material producing step of producing a solid raw material from the solid component dried in the drying step.

[0015] A third aspect of the present invention is characterized in that the solid raw material production step produces powder fertilizer, granular fertilizer, and solid fuel raw material.

[0016] A fourth aspect of the present invention is characterized in that in the drying step, the solid component is vacuum dried, freeze-dried, or vacuum freeze-dried to produce the solid raw material.

[0017] A fifth aspect of the present invention is characterized by having a liquid fertilizer production step of producing liquid fertilizer from the liquid component separated from the drainage liquid in the dehydration step. Effect of the Invention

[0018] According to the present invention, used paper diapers are decomposed and processed in a separation process, the solid components pulp and plastic separated in the separation process are sorted in a sorting process, pulp is recovered from the effluent, which is the liquid component separated in the separation process, in a pulp recovery process, the solid components and liquid components in the effluent after the pulp is recovered in the pulp recovery process are separated in a dehydration process, and the solid components separated from the effluent in the dehydration process are dried in a drying process to produce solid raw materials.Therefore, it is possible to effectively utilize the effluent after used paper diapers are decomposed and processed and the effluent after recycling resources are recovered, and solid raw materials can be easily produced from the effluent. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a block diagram showing steps of a method for producing a solid raw material according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing an apparatus used in each step of the method for producing a solid raw material according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, a method for producing a solid raw material according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1 and Fig. 2, the method for producing a solid raw material according to the present embodiment includes a separation step 1 in which used paper diapers are agitated with a processing liquid in a separator 9 to decompose and process the paper diapers into components constituting the paper diapers, a sorting step 2 in which the solid components pulp and plastic separated in the separation step 1 are sorted by a sorter 10, a first pulp recovery step 4 in which pulp 8 is recovered from the waste liquid 3, which is the liquid component separated in the separation step 1, a dewatering step 6 in which the solid components and liquid components in the waste liquid 5 after the pulp 8 is recovered in the first pulp recovery step 4 are separated, and a drying step 7 in which the solid components separated from the waste liquid 5 in the dewatering step 6 are dried.

[0021] The separator 9 used in the separation process 1 is formed of an outer body separating tank fixed to a housing, and an inner body separating tank with a large number of small holes formed on the outer peripheral surface and rotatably supported in the outer body separating tank. Used paper diapers and treatment liquid are put into the inner body separating tank, and the used paper diapers are agitated together with the treatment liquid by the rotation of the inner body separating tank, and are decomposed and processed into the materials that make up the paper diapers. Used paper diapers are decomposed and processed into pulp, plastic, and other materials in the inner body separating tank, and most of the pulp is mixed in the treatment liquid.

[0022] When the treated liquid is discharged from the inner body separation tank, the solid matter remaining in the inner body separation tank is plastic 28, plastic pulp 24 with a small amount of pulp attached, and other matter. The treated liquid discharged from the inner body separation tank (hereinafter referred to as "first waste liquid 3") has pulp 8 recovered by a first pulp recovery device 11. The waste liquid (hereinafter referred to as "second waste liquid 5") after the pulp 8 is recovered from the first waste liquid 3 contains sludge components. This second waste liquid 5 is dehydrated by a dehydrator 12 in a dehydration process 6, and is separated into solid sludge components (scum) and a liquid portion. The liquid components separated from the second waste liquid 5 by the dehydrator 12 become liquid fertilizer 14 in a liquid fertilizer production process 13, and the solid sludge components are dried by a dryer 15 in a drying process 7. In this case, even if the sludge is dehydrated by the dehydrator 12, the solid sludge components still contain a small amount of moisture, and the moisture content is reduced as much as possible by the dryer 15.

[0023] The drying device 15 may be vacuum drying, vacuum freeze drying, freeze drying, or heat drying using a heater. From the solid sludge component (scum) dried by the drying device 15, a solid raw material 20 is produced in a solid raw material production process 16. This solid raw material 20 is crushed into powder by a solid fertilizer production device 18 to produce powder fertilizer 17, and is produced into granules to produce granular fertilizer 19. These powder fertilizers 17 and granular fertilizers 19 are sludge collected from used paper diapers, organic matter discharged from the human body, and contain nitrogen, phosphoric acid, potassium, and the like, which are beneficial nutrients for soil. In addition, harmful bacteria are killed because the used paper diapers are sterilized and disinfected during the decomposition process.

[0024] The solid raw material 20 produced by the drying device 15 is mixed with pulp recovered by the first pulp recovery device 11 and the like by the solid fuel production device 25, and compressed and molded to produce solid fuel raw material 26. The moisture separated from the solid sludge components by the drying device 15 is mixed with the moisture dehydrated by the dehydration device 12 to become the raw material for liquid fertilizer 14.

[0025] The solid matter remaining in the inner body separation tank of the separator 9, namely, plastic 28, plastic pulp 24 with a small amount of pulp attached, and the rest are sent to the sorter 10 in the sorting process 2. The sorter 10 is formed of an outer body sorting tank fixed to a housing, and an inner body sorting tank with many small holes formed in its outer circumferential surface and rotatably supported in the outer body sorting tank. The solid components remaining in the inner body separation tank, namely, pulp, plastic, plastic with a small amount of pulp attached, and the rest, are fed into the inner body sorting tank.

[0026] Dry air is supplied into the outer body sorting tank, and the dry air is blown onto the pulp 8, plastic 28, plastic pulp 24 with a small amount of pulp attached, and other materials in the inner body sorting tank rotating inside the outer body sorting tank, and the materials are sorted into pulp 8, plastic 28, plastic pulp 24, and other materials. The dry air supplied to the outer body sorting tank to dry the pulp 8, plastic 28, plastic pulp 24, and other materials contains pulp 8 mixed in, and this dry air is collected by the second pulp recovery device 22 in the second pulp recovery process 21, where the pulp 8 is captured by a filter or the like. The plastic pulp 24 in the inner body sorter is collected in the plastic pulp recovery process 23. The plastic 28 remaining in the outer body sorting tank is collected in the plastic recovery process 27.

[0027] Next, the analysis results of the powder fertilizer 17 and the granular fertilizer 19 produced from the solid raw material produced by the method for producing a solid raw material according to the present embodiment will be described. [Table 1] As shown in Table 1, the powder fertilizer 17 and granular fertilizer 19 produced from the solid raw material of this embodiment contain lime, zinc, and copper in addition to the components nitrogen, phosphoric acid, and potassium. The lime is contained in the treatment liquid used when treating used paper diapers.

[0028] Furthermore, the levels of harmful substances such as arsenic, cadmium, nickel, chromium, mercury, lead, and mercury are below the values ​​set by the Fertilizer Control Law, meaning that there is no problem with spreading them on fields as fertilizer and releasing them into the natural environment.

[0029] In addition, powdered and granular fertilizers made from solid raw materials contain lime and are therefore strongly alkaline, but this can be neutralized by mixing in a neutralizing agent. In addition, powdered and granular fertilizers made from solid raw materials contain lime, so they can also be used as soil conditioners to neutralize acidic soil.

[0030] As described above, according to the method for producing a solid raw material of this embodiment, the second waste liquid 5 obtained after decomposing and processing used disposable diapers and recovering recyclable resources is not discharged into sewerage or the like, so that the second waste liquid 5 can be effectively utilized and the solid raw material 20 can be easily produced from waste liquid that would have been discarded in the past. Meanwhile, lime is strongly alkaline, so it can be neutralized by mixing it with a neutralizing agent before use.

[0031] The solid raw material 20 produced by the solid raw material manufacturing method of this embodiment is sterilized and disinfected when used paper diapers are decomposed and processed, so it does not contain any fungi that are harmful to the human body and can be used as a raw material in a hygienic condition.

[0032] Furthermore, the solid raw material 20 according to this embodiment is sludge adhering to used paper diapers and is discharged from the human body, and therefore does not contain any other sludge (livestock manure or other substances). As a result, the powdered fertilizer, granular fertilizer, and solid fuel produced from this solid raw material 20 are hygienic and do not harm the human body or the environment. Furthermore, even if it is burned as solid fuel, it does not have a negative impact on the environment.

[0033] Furthermore, according to the method for producing solid raw materials in this embodiment, in addition to decomposing used paper diapers and recovering the recyclable resources pulp 8, plastic 28, and plastic pulp 24, the second effluent 5 produced by processing used paper diapers is also separated into solid and liquid components, and the liquid components are used as liquid fertilizer 14 and the solid components are used as solid raw materials 20 for powder fertilizer 17, granular fertilizer 19, and solid fuel raw material 26, making it possible to almost completely recycle used paper diapers.

[0034] As a result, since nothing is released into the natural world after the disposal of used paper diapers, there is no adverse effect on the natural environment. In particular, in the manufacturing method of the solid raw material of this embodiment, since used paper diapers are not crushed, small pieces of plastic (microplastics) are not generated, and microplastics are not released into the ocean.

[0035] As described above, the embodiment of the present invention has been disclosed, but it is clear that modifications can be made by those skilled in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the claims. [Industrial Applicability]

[0036] The method for producing solid raw materials according to the present invention is not limited to a method for producing solid raw materials from used paper diapers, but can also be used to decompose and process urine pads and other sanitary products and produce solid raw materials from these urine pads and other sanitary products. [Explanation of symbols]

[0037] 1 Separation process 2. Sorting process 3. First drain 4. First pulp recovery process 5. Second drainage 6 Dehydration process 7 Drying process 8. Pulp 9 Separator

Claims

1. A separation process (1) in which used paper diapers are agitated together with a treatment liquid in a separator (9) to decompose and treat the components constituting the paper diaper; a sorting step (2) for sorting the solid components, pulp (8) and plastics (28), separated in the separation step (1) by a sorting machine (10); a pulp recovery step (4) for recovering pulp (8) from a discharged liquid (3) which is a liquid component separated in the separation step (1); a dewatering step (6) for separating solid and liquid components in the discharged liquid (5) after the pulp (8) is recovered in the pulp recovery step (4); and a drying step (7) of drying the solid component separated from the waste liquid (5) in the dehydration step (6).

2. 2. The method for producing a solid raw material according to claim 1, further comprising a solid raw material production step (16) for producing a solid raw material (20) from the solid component dried in the drying step (7).

3. 3. The method for producing solid raw materials according to claim 2, characterized in that in the solid raw material production step (16), powder fertilizer (17), granular fertilizer (19), and solid fuel raw material (26) are produced.

4. 3. The method for producing a solid raw material according to claim 1 or 2, characterized in that in the drying step (7), the solid component is vacuum dried, freeze-dried, or vacuum freeze-dried to produce the solid raw material (20).

5. 2. The method for producing a solid raw material according to claim 1, further comprising a liquid fertilizer production step (13) for producing liquid fertilizer (14) from the liquid component separated from the drainage liquid (5) in the dehydration step (6).

Images