JP2022007645A - Sludge fertilizer having high nitrogen mineralization ratio - Google Patents

Abstract

To provide a sludge fertilizer having a high nitrogen mineralization ratio.SOLUTION: This invention relates to a method of producing a sludge fertilizer and the sludge fertilizer produced by the same, the method including: forming a stacked body including a sludge layer, an organic fertilizer material layer, and a woody biomass layer; then preparing a fertilizer raw material body by covering an outer side of the stacked body with a sludge layer; and subjecting the fertilizer raw material body to conditional anaerobic fermentation.SELECTED DRAWING: Figure 1

Description

There is an application for application of Article 30, Paragraph 2 of the Patent Law. Name of the research meeting: The 74th Annual Academic Lecture Meeting of the Japan Society of Civil Engineers in the first year of Reiwa Date: September 3, 1st year of Reiwa 2. Posting address: https: // confit. atlas. jp / guide / event / jsce2019 / top https: // confit. atlas. jp / guide / event / jsce2019 / session / 1VII-224-31 / tables? pXWfDeB01x https: // confit. atlas. jp / guide / event / jsce2019 / subject / VII-55 / subjects? cryptold = Publication date: June 28, 1st year of Reiwa 3. Posting address: https: // confit. atlas. jp / guide / event / jsce2019 / top https: // confit. atlas. jp / guide / event / jsce2019 / session / 1VII-224-31 / tables? pXWfDeB01x https: // confit. atlas. jp / guide / event / jsce2019 / subject / VII-57 / subjects? cryptold = Publication date: June 28, 1st year of Reiwa 4. Publication name: Reiwa 1st year Japan Society of Civil Engineers National Convention 74th Annual Academic Lecture DVD Version Lecture Summary Publication Date: August 1, 2019 5. Publication name: Reiwa 1st year Civil Society Western Chapter Research Presentation Summary (CD-ROM) Publication date: February 20, 2020

The present invention relates to sludge fertilizer having a high nitrogen mineralization rate.

Currently, there is a need to promote the utilization of resources such as sewage sludge, sewage heat, and phosphorus generated from sewage treatment facilities. The 2015 Amendment to the Sewerage Act stipulates the need for efforts to recycle sludge as fuel or fertilizer. In addition, the Ministry of the Environment's "Basic Plan for Promotion of Sound Material-Cycle Society" states that it will support the use of fertilizer for sewage sludge in the region.

Sewage sludge is dehydrated at a terminal treatment plant using a polymer flocculant or an inorganic flocculant, and most of it is collected as dehydrated sludge (dehydrated cake; moisture content 75.5 to 78.0%) by an industrial waste treatment company at a high price. It is disposed of in land or used as a building material (raw material for cement after incineration). Utilizing the characteristic that 80% of the components of sewage sludge are organic matter, the results of energy utilization and green farmland utilization are only about 22% and 10%, respectively. The Ministry of Land, Infrastructure, Transport and Tourism's "Productivity Revolution Project" aims to increase the energy and agricultural utilization rate of sewage sludge to 40% by 2020 (FY2).

Sludge fertilizer produced from sewage sludge is classified as ordinary fertilizer by the Fertilizer Control Law, and when registering fertilizer, the minimum amount of main components (nitrogen, phosphoric acid, potash, etc.) that should be contained as fertilizer, and harmful substances that are allowed to be contained. It is necessary to meet official standards (standard values) such as the maximum amount of components (heavy metals). The fertilizer components of sludge fertilizer are high in nitrogen and phosphoric acid, and low in potassium.

The existing sludge fertilizer has a problem that it tends to become muddy when it contains water and is difficult to use. The heavy metal content of sludge fertilizer is the standard value (T-Hg: 2mg / kg, As: 50mg / kg, Cd: 5mg / kg, Ni: 300mg / kg, Cr: 500mg / kg, Pb: 100mg / kg). Although it is as follows, it is much higher than cow dung compost, horse manure compost, chicken manure, and pig manure compost. Furthermore, most of the sludge fertilizers are used for single-year crops of leafy vegetables and fruit vegetables, and the main use is to return agricultural land to pasture. ), It is difficult to add high value, and the use of sludge fertilizer is stagnant.

Patent Document 1 discloses a method for producing fertilizer, which uses a fertilizer obtained by removing metals from sewage sludge molten slag. However, the metal removal process is time-consuming and leads to an increase in fertilizer production costs. It is desired to develop a method capable of producing sludge fertilizer with high added value while suppressing the production cost.

Japanese Unexamined Patent Publication No. 2016-44121

An object of the present invention is to provide a sludge fertilizer having a high nitrogen mineralization rate.

As a result of diligent studies to solve the above problems, the present inventors have laminated sludge such as sewage sludge and a suitable fertilizer raw material, and then covered the outside with sludge to suppress ventilation from the outside. We have found that sludge fertilizer with a high nitrogen mineralization rate can be produced by anaerobic fermentation, and have completed the present invention.

That is, the present invention includes the following.
[1] After forming a laminate containing a sludge layer, an organic fertilizer material layer, and a woody biomass layer, a fertilizer raw material is prepared by covering the outside with a sludge layer, and the fertilizer raw material is conditionally anaerobically fertilized. How to make sludge fertilizer, including.
[2] The method according to the above [1], wherein the laminate includes a sludge layer sandwiched vertically by either or both of an organic fertilizer material layer and a woody biomass layer.
[3] The method according to the above [1] or [2], wherein the laminate includes a sludge layer as the lowest layer.
[4] The method according to any one of [1] to [3] above, wherein the laminate contains at least two layers each of a sludge layer, an organic fertilizer material layer, and a woody biomass layer.
[5] The method according to any one of the above [1] to [4], wherein the laminate includes at least one of an oil-based organic fertilizer material layer and a shochu lees layer as an organic fertilizer material layer.
[6] From the lower layer to the upper layer, the sludge layer, the oily organic fertilizer material layer, the woody biomass layer, the shochu lees layer, the sludge layer, the shochu lees layer, the woody biomass layer, and the oily organic fertilizer material are formed. The method according to [5] above, which comprises a structure in which layers are laminated in this order.
[7] The fertilizer raw material contains sludge, oily organic fertilizer material, woody biomass, and lees in dry weight at a mixing ratio of 30 to 50%: 10 to 30%: 20 to 40%: 0 to 20%, respectively. The method according to the above [5] or [6], which comprises the amount of the above.
[8] The method according to any one of the above [1] to [7], wherein the organic fertilizer material layer contains rice bran as an oil-based organic fertilizer material.
[9] The method according to any one of [1] to [8] above, wherein the sludge layer contains sewage sludge.
[10] The method according to any one of the above [1] to [9], wherein the sludge layer contains dehydrated sludge.
[11] The method according to any one of the above [1] to [10], wherein the woody biomass layer contains sawdust.
[12] The method according to any one of the above [5] to [7], wherein the lees lees layer contains sweet potato lees.
[13] The method according to any one of the above [1] to [12], which comprises performing turning back during the period of conditional anaerobic fermentation.
[14] The method according to any one of [1] to [13] above, further comprising mixing at least a part of the laminate before covering the outside with a sludge layer.
[15] Sludge fertilizer produced by the method according to any one of the above [1] to [14].
[16] The sludge fertilizer according to [15] above, wherein the sludge fertilizer contains Bacillus order bacteria as a dominant species.
[17] The sludge fertilizer according to the above [15] or [16], which has a C / N ratio of 7 or more.
[18] The sludge fertilizer according to any one of the above [15] to [17], wherein the heavy metal content is 50 mg or less per 1 kg of sludge fertilizer.
[19] A method for cultivating a plant, which comprises applying the sludge fertilizer according to any one of the above [15] to [18] to the plant.

According to the present invention, sludge fertilizer having a high nitrogen mineralization rate can be produced.

FIG. 1 is a diagram schematically showing an example of a sandwich method for laminating (depositing) fertilizer raw materials. Note that "water" in the figure schematically shows the order of spraying, and does not indicate the formation of a water layer. FIG. 2 is a graph showing the results of nitrogen mineralization tests of various fertilizers. White circles indicate rapeseed oil cake, white squares indicate cow dung compost, diamonds indicate chicken manure compost, black circles indicate aerobic fertilized sewage sludge fertilizer CSK, and black squares indicate conditional anaerobic fertilized sewage sludge fertilizer SW of the present invention. FIG. 3 is a graph showing the results of nitrogen mineralization tests of various fertilizers. Black circles indicate rapeseed oil cake, white squares indicate aerobic fermented sewage sludge fertilizer CSK, and diamonds indicate aerobic fermented sewage sludge fertilizer KG. FIG. 4 is a graph showing the results of nitrogen mineralization tests of various fertilizers. Black circles indicate sewage sludge mixed compost C, and black squares indicate sewage sludge mixed compost D.

Hereinafter, the present invention will be described in detail.
In the present invention, sludge and other fertilizer raw materials are laminated, and preferably sludge is stacked in a sandwich shape so as to be sandwiched between other fertilizer raw materials to form (manufacture) a laminate, and then the outside is covered with a sludge layer. It relates to a method for producing sludge fertilizer by conditional anaerobic fermentation. By covering the outside with a sludge layer, it is possible to suppress (reduce) ventilation from the outside and promote the generation of conditioned anaerobic conditions.

More specifically, the present invention prepares a fertilizer raw material by forming a laminate including a sludge layer, an organic fertilizer material layer, and a woody biomass layer, and then covering the outside with a sludge layer. The present invention relates to a method for producing sludge fertilizer, including conditional anaerobic fermentation.

In the method of the present invention, sludge, organic fertilizer materials and woody biomass are first stacked in layers so as to form a laminate, so that the laminate and the fertilizer raw material are compared with the case where they are simply mixed and stacked. It can facilitate the adjustment of water content in the body and facilitate the assurance of overall uniformity.

When forming the laminate, the sludge, the organic fertilizer material, and the woody biomass are sandwiched so that at least one sludge layer is vertically sandwiched by either or both of the organic fertilizer material layer and the woody biomass layer. It is preferable to stack them on. That is, in a preferred embodiment, the laminate formed in the method of the present invention contains at least one sludge layer sandwiched vertically by either or both of the organic fertilizer material layer and the woody biomass layer.

Here, "the sludge layer sandwiched above and below by either or both of the organic fertilizer material layer and the woody biomass layer" is (i) above the organic fertilizer material layer and the sludge layer adjacent to the lower side of the sludge layer. A sludge layer sandwiched between adjacent organic fertilizer material layers, (ii) a woody biomass layer adjacent to the lower side of the sludge layer and a sludge layer sandwiched between a woody biomass layer adjacent to the upper side of the sludge layer, (iii). A sludge layer sandwiched between an organic fertilizer material layer adjacent to the lower side of the sludge layer and a woody biomass layer adjacent to the upper side of the sludge layer, and (iv) a woody biomass layer and a sludge layer adjacent to the lower side of the sludge layer. A combination of a sludge layer sandwiched by an organic fertilizer material layer adjacent to the upper side, and (v) at least one organic fertilizer material layer and at least one woody biomass layer adjacent to the lower side of the sludge layer (for example, below). A combination including, but not limited to, an organic fertilizer material layer adjacent to the sludge layer and a woody biomass layer adjacent to the opposite side of the organic fertilizer material layer) and at least one organic material adjacent to the upper side of the sludge layer. A combination of a fertilizer material layer and at least one woody biomass layer (eg, but not limited to, an organic fertilizer material layer adjacent to the sludge layer and a woody biomass layer adjacent to the opposite side of the organic fertilizer material layer). Includes any aspect of the sludge layer sandwiched by (a combination comprising). By sandwiching the sludge layer up and down with either or both of the organic fertilizer material layer and the woody biomass layer, the sludge layer with a high water content can be changed to the organic fertilizer material layer and the woody biomass layer with a relatively low water content. Not only can it absorb water and make the water content more uniform overall, but it can also create more suitable conditions for subsequent operations and fermentation.

In a preferred embodiment, a sludge layer may be used as the bottom layer when forming the laminate. That is, the laminate may include a sludge layer as the bottom layer. By making the bottom layer of the laminated body a sludge layer, when the outside of the laminated body is covered with the sludge layer as it is, a fertilizer raw material body completely covered with the sludge layer can be produced.

In one embodiment, in the laminate and fertilizer raw material of the present invention, the sludge layer, the organic fertilizer material layer, and the woody biomass layer also have an organic fertilizer material layer and a woody biomass layer between the sludge layer and the sludge layer. It may be laminated in a sandwich shape so as to be sandwiched.

In the method of the present invention, after forming a laminate including a sludge layer, an organic fertilizer material layer, and a woody biomass layer, the sludge layer covers the outside to form a fertilizer raw material, whereby conditioned anaerobic in the fertilizer raw material. Conditions can be created.

In the present specification, a state in which anaerobic condition (oxygen deficiency state) is always maintained (for example, a state in which the whole fertilizer raw material or the like is covered with vinyl and sealed) is referred to as an absolute anaerobic condition. On the other hand, in the present specification, the fertilizer raw material and the like are anaerobic (oxygen deficient state) because forced aeration (for example, an operation of directly and continuously sending air or oxygen into the fertilizer raw material) is not performed. However, the state where the limited inflow of air or oxygen is not excluded, for example, a part of the fertilizer raw material (for example, the surface layer) is in contact with air or oxygen, and natural ventilation is limited. The condition of limited contact with air or oxygen during a limited number of turns (for example, 1 to 4 times throughout the fermentation process) is called a conditional anaerobic condition.

More specifically, in the present invention, by forming a layer containing a large amount of water (particularly a sludge layer) near the surface layer portion of the fertilizer raw material body, ventilation from the outside through the surface layer is suppressed (at least a part of ventilation). On the other hand, oxygen inside the fertilizer raw material is consumed by aerobic bacteria, so that the inside of the fertilizer raw material quickly becomes anaerobic. The slight ventilation through the sludge layer provided near the surface layer of the fertilizer raw material does not cause the anaerobic inside of the fertilizer raw material to be lost. In addition, oxygen is temporarily supplied when the fertilizer raw material is turned back, which will be described later, but at a depth of more than 30 cm from the surface layer, oxygen is consumed by aerobic bacteria immediately after that, and the fertilizer becomes anaerobic again.

In the present invention, the sludge is not particularly limited, but may be sewage sludge, industrial sludge, or the like. The sludge may be dehydrated, and such sludge is referred to as dehydrated sludge. Dewatered sludge usually has a water content of 65-85%, for example 70-80% or 75-78%, but not limited to: The sludge may be, for example, sewage sludge or dehydrated sludge of industrial sludge. Each sludge layer contained in the laminate and the fertilizer raw material according to the present invention contains one kind or two or more kinds of such sludge. A sludge layer composed of dehydrated sludge is also referred to as a dehydrated sludge layer.

In the present invention, the organic fertilizer material is not particularly limited, but may be an oil-based organic fertilizer material, shochu lees, or both. In the present invention, the "oil-based organic fertilizer material" means an organic fertilizer material rich in oil. The oil-based organic fertilizer material is not particularly limited, and examples thereof include rice bran, oil cake containing a large amount of oil (for example, soybean meal, rapeseed meal (rapeseed meal), cottonseed meal, tea meal cake, etc.). The laminate may contain one or more organic fertilizer materials. Each organic fertilizer material layer contained in the laminate may contain one or more organic fertilizer materials. The laminate may include at least one of the oil-based organic fertilizer material layer and the shochu lees layer as the organic fertilizer material layer. In the laminate, the oily organic fertilizer material and the lees are preferably contained in separate organic fertilizer material layers. In one embodiment, the organic fertilizer material layer comprises rice bran, preferably the oily organic fertilizer material. The lees may be any lees such as sweet potato lees, potato lees, barley lees, and rice lees. The lees lees are in any form such as a dried lees lees solid, a lees stock solution, and a dehydrated lees (for example, a solid fraction obtained by solid-liquid separating the lees stock solution with a centrifuge or the like, that is, a dehydrated cake). May be.

In the present invention, woody biomass refers to a plant-derived organic material rich in lignocellulosic (lignin, cellulose, and hemicellulose). Generally, woody biomass is not suitable as a fertilizer material as it is (without composting). Examples of woody biomass include sawdust (bamboo sawdust, coniferous sawdust, broad-leaved sawdust, etc.), cut grass of herbaceous plants such as dunchiku, yoshi, suki, and rice, bark, scraps, leaves, and wood chips. Not limited to these. Each woody biomass layer contained in the laminate may contain one or more woody biomasses.

The laminate may include at least one or at least two sludge layers. The laminate may include at least one or at least two organic fertilizer material layers. The laminate may include at least one or at least two woody biomass layers. In a preferred embodiment, the laminate may include at least two layers each of a sludge layer, an organic fertilizer material layer, and a woody biomass layer.

In one embodiment, the laminate is a sludge layer, an organic fertilizer material layer, a woody biomass layer, an organic fertilizer material layer, a sludge layer, an organic fertilizer material layer, a woody biomass layer, and an organic fertilizer from the lower layer to the upper layer. It may include one or more (for example, one, two, or three or more) structures in which material layers are laminated in this order. In another embodiment, the laminate has one or more structures in which a sludge layer, an organic fertilizer material layer, a woody biomass layer, an organic fertilizer material layer, and a sludge layer are laminated in this order from a lower layer to an upper layer ( For example, one, two, or three or more) may be included. For example, from the lower layer to the upper layer, the laminated body includes a sludge layer, an organic fertilizer material layer, a woody biomass layer, an organic fertilizer material layer, a sludge layer, an organic fertilizer material layer, a woody biomass layer, an organic fertilizer material layer, and It may include one or more structures in which sludge layers are laminated in this order.

In one embodiment, the laminate is a sludge layer, an oily organic fertilizer material layer, a woody biomass layer, a shochu lees layer, a sludge layer, a shochu lees layer, a woody biomass layer, and an oily organic fertilizer from the lower layer to the upper layer. It may include a structure in which material layers are laminated in this order.

In the present invention, it is preferable to cover the outside with a sludge layer to prepare a fertilizer raw material after forming the laminate. By covering the outside with a sludge layer, ventilation from the outside (that is, permeation of air and oxygen) can be suppressed, and the generation of conditional anaerobic conditions can be promoted as described above. Here, "covering the outside with a sludge layer" means that at least the entire exposed portion is covered with a sludge layer. The ground contact surface (bottom surface) of the laminate or the fertilizer raw material may be a sludge layer, but may not be a sludge layer. In other words, when the entire grounded fertilizer raw material except the ground surface is covered with a sludge layer, the fertilizer raw material is obtained by covering the outside with a sludge layer, and is overall. It can be considered that it is covered with a sludge layer.

After forming the laminate, the outside of the laminate can be directly covered with a sludge layer. Alternatively, after the formation of the laminate, before covering the outside with the sludge layer, at least a part of the laminate (for example, a part or the whole of the laminate) is mixed by cutting back or the like, and then the outside is covered with the sludge layer. May be good. It is also preferable to mix at least a part of the laminate, and if necessary, adjust the overall sedimentary shape, and then cover the outside with a sludge layer. By mixing at least a portion of the laminate before covering the outside with a sludge layer, local masses are less likely to form. Even when at least a part of the laminate is mixed and then the outside is covered with a sludge layer, the water content is adjusted by stacking the laminate once in the form of the laminate as compared with the case where the fertilizer raw materials are mixed from the beginning. And can enjoy the above-mentioned advantages of ensuring overall uniformity. Therefore, the method of the present invention may further comprise mixing at least a portion of the laminate after formation of the laminate and before covering the outside with a sludge layer. Such a case is also included in the present invention of "making a fertilizer raw material by covering the outside with a sludge layer after forming a laminated body".

The conditional anaerobic condition in the present invention does not require that the structure in which the sludge layer covers the fertilizer raw material is maintained throughout the fermentation period as long as the above definition of the conditional anaerobic condition is satisfied. That is, even if the sludge layer on the surface layer of the fertilizer raw material is lost due to turning back or the like, the conditional anaerobic condition can be maintained.

In a preferred embodiment, the laminate may include a sewage sludge layer, a rice bran layer, a sawdust layer (eg, bamboo sawdust), and a shochu lees layer (eg, sweet potato lees layer).

In one embodiment, the fertilizer raw material is not limited to the following, but is preferably one having a height of 50 cm to 700 cm, for example, 60 cm to 400 cm, 70 cm to 200 cm, or 70 cm to 100 cm as a whole. good. In one embodiment, the fertilizer raw material has a height of preferably 50 cm to 200 cm, for example 60 cm to 200 cm, 70 cm to 150 cm, or 70 cm to 100 cm as a whole when the total volume of the fertilizer raw material is 5 m ³ . In the case of 10 m ³ , it may have a height of 100 cm to 400 cm, for example, 120 cm to 400 cm, 140 cm to 300 cm, or 140 cm to 200 cm as a whole.

The width and depth of the bottom surface of the fertilizer raw material are not particularly limited, but for example, the width of the bottom surface may be 1 m to 10 m and the depth may be 1 m to 10 m. In one embodiment, the width of the bottom surface is 1 m to 5 m and the depth is 1 m. It may be up to 5m. In one embodiment, the bottom surface of the fertilizer raw material may be substantially square, but is not limited thereto.

The fertilizer raw material is not limited to the following, but sludge, oily organic fertilizer material, woody biomass, and shochu lees are classified by dry weight, sludge: oily organic fertilizer material: woody biomass: shochu lees = 30 ~. It may be contained in a blending ratio of 50%: 10 to 30%: 20 to 40%: 0 to 20%. In one embodiment, the fertilizer raw material is sludge, oily organic fertilizer material, woody biomass, and shochu lees by dry weight, sludge: oily organic fertilizer material: woody biomass: shochu lees = 35-45%: 15 It may be contained in a blending ratio of ~ 25%: 25 to 35%: 5 to 15%, or 38 to 42%: 20 to 30%: 25 to 35%: 0 to 10%. In a particularly preferred embodiment, the fertilizer raw material is sludge, oily organic fertilizer material, woody biomass, and shochu lees by dry weight, sludge: oily organic fertilizer material: woody biomass: shochu lees = about 40%: about. 20%: Approximately 30%: Approximately 10% is included. In the present invention, "about" means a range of ± 5% of the stated numerical value.

When sludge, organic fertilizer materials, and woody biomass are laminated to form a laminate, the moisture content of the laminate as a whole is usually 55 to 65%, preferably 58 to 63%, and more preferably 60 to. It is preferable to adjust to 63%. In addition, when preparing a fertilizer raw material using a laminate containing sludge, organic fertilizer material, and woody biomass, the water content of the fertilizer raw material as a whole is usually 55 to 65%, preferably 58 to 58. It is also preferable to adjust to 63%, more preferably 60 to 63%. When the water content of the fertilizer raw material used is low, an appropriate amount of water can be added to the laminate so as to have the above-mentioned moisture content during or after the lamination between the laminations. Alternatively, when a fertilizer raw material having a large amount of water, for example, a lees stock solution, is used, it is preferable to reduce the amount of water added. In one embodiment, when applying water, it is preferable to spread the water evenly on the surface of the layer.

In one embodiment, water may be applied to at least one of the woody biomass layer and the organic fertilizer material layer at the time of forming the laminate so as to have the above-mentioned water content.

In one embodiment, the above moisture is formed between the woody biomass layer and the organic fertilizer material layer, or between the organic fertilizer material layer and the sludge layer during the formation of the laminate and / or the preparation of the fertilizer raw material. Water may be applied to the rate. In one embodiment, the sludge layer, the oily organic fertilizer material layer, the woody biomass layer, the shochu lees layer, the sludge layer, the shochu lees layer, the woody biomass layer, and the oily organic fertilizer material layer are formed from the lower layer to the upper layer. Oily organic between the sludge layer and the adjacent oily organic fertilizer material layer when forming a laminate containing one or more stacked structures in order and when producing a fertilizer raw material containing the laminate. Between the fertilizer material layer and the woody biomass layer adjacent to it, between the woody biomass layer and the shochu lees layer adjacent to it, between the shochu lees layer and the sludge layer adjacent to it, the sludge layer and its Between the shochu lees layer adjacent to the top, between the shochu lees layer and the woody biomass layer adjacent to it, between the woody biomass layer and the oily organic fertilizer material layer adjacent to it, and the oily organic fertilizer material layer. Water may be applied between one, two, or three or more layers selected from the group consisting of and adjacent sludge layers on it. In a preferred embodiment, water can be applied between the woody biomass layer and the lees layer adjacent thereto, and between the oily organic fertilizer material layer and the sludge layer adjacent thereto.

As described above, the fertilizer raw material of the present invention can be subjected to conditional anaerobic fermentation by accelerating the generation of conditional anaerobic conditions by covering the outside with a sludge layer. Conditional anaerobic fermentation means fermentation performed under conditional anaerobic conditions, for example, fermentation involving conditioned anaerobic bacteria.

The fermentation period of the fertilizer raw material is not limited to the following, but may be, for example, 30 to 150 days, preferably 50 to 100 days, and more preferably 30 to 60 days. Fermentation of the fertilizer raw material is not limited to the following, but is preferably carried out under temperature conditions of 0 to 40 ° C, preferably 10 to 40 ° C, for example, 20 to 35 ° C.

It can be cut back during the fermentation period of the fertilizer raw material. The switching can be performed, for example, once every 1 to 6 weeks, for example, once every 2 to 5 weeks, or approximately once every 1 month (27 to 34 days). Switching can be done by a conventional method. One week is 7 days for the present invention.

In a preferred embodiment, fertilization (composting) can be completed when fermentation proceeds, the temperature of the fertilizer raw material rises, and the temperature gradually decreases beyond the peak. The fertilizer raw material that has been fertilized can be used as sludge fertilizer. The present invention also provides such sludge fertilizers.

The sludge fertilizer obtained by the method of the present invention preferably contains Bacillales bacteria as a dominant species at the completion of fertilization (composting). In the present invention, "included as a dominant species" means that the ratio of the number of cells of the target microorganism to the number of cells of the microorganism contained in the test sample is the highest. Here, "dominant species" is not construed as being limited to organisms in a narrow sense, and for example, various species of bacteria belonging to the order Bacillales can be collectively referred to as "dominant species". In one embodiment, the sludge fertilizer of the present invention may be high in high temperature bacteria of the order Bacillales. Such hyperthermic bacteria may be, for example, a relative of Cerasibacillus quisquiliarum or a relative of Sinibacillus soli. Bacillales bacteria contained in sludge fertilizer as a dominant species are bacteria that form spores due to temperature rise (high temperature) and pH change and can survive under aerobic or anaerobic conditions. It is preferable that the Bacillales bacteria increase remarkably in the latter half of the production process (fermentation process) of the sludge fertilizer according to the present invention. Bacteria contained in sludge fertilizer can be identified based on, for example, 16S rRNA gene sequence analysis, but is not limited thereto.

The sludge fertilizer obtained by the method of the present invention exhibits a high nitrogen mineralization rate (mineralization rate / fertilizer efficiency). The sludge fertilizer of the present invention is not limited to, for example, preferably 70% or more, more preferably 70 to 95%, for example, 75 to 95%, after 140 days of culturing in a nitrogen mineralization test. Alternatively, it can exhibit a nitrogen mineralization rate of 80 to 90%.

The sludge fertilizer of the present invention also preferably exhibits a low heavy metal content. In a preferred embodiment, the heavy metal content of the sludge fertilizer of the present invention is 50 mg or less, preferably 30 mg or less per 1 kg of sludge fertilizer. Here, the heavy metal content means the total content of As, Cr, Cd, Pb, Al, Hg, Cu, Zn and Ni. Due to the low heavy metal content, the sludge fertilizer of the present invention can reduce soil pollution and groundwater pollution due to fertilization.

The sludge fertilizer of the present invention has a high C / N ratio (mass ratio of carbon C content (%) and nitrogen N content (%)) and is useful as a fertilizer. The C / N ratio of the sludge fertilizer of the present invention is preferably 7 or more, more preferably 8 or more, still more preferably 9 or more.

In a preferred embodiment, the sludge fertilizer of the present invention comprises at least one selected from the group consisting of lignocellulosic, typically lignin, cellulose, and hemicellulose. The sludge fertilizer of the present invention preferably contains, for example, at least 20 g of lignocellulosic per 100 g (dry weight) of sludge fertilizer, more preferably at least 30 g, at least 40 g, or at least 50 g, for example, 40 g to 70 g or 40 g. It may contain up to 60 g. Since the sludge fertilizer of the present invention contains a large amount of fiber components such as lignocellulosic, it has good water retention. In a preferred embodiment, the sludge fertilizer of the present invention exhibits good workability by containing a large amount of fiber components.

In a preferred embodiment, the sludge fertilizer of the present invention has a low potassium content as compared with cow dung compost, pig dung compost and the like.

The present invention also provides a method for cultivating a plant using the sludge fertilizer of the present invention. In one embodiment, the method of the present invention relates to a method for cultivating a plant, which comprises applying sludge fertilizer to the plant. The sludge fertilizer may be applied by a conventional method, and for example, it can be applied according to a general method for applying sewage sludge fertilizer. The plant is not particularly limited, but may be, for example, a plant in which fertilization with high nitrogen and low potassium is desirable. Examples of the plant include, but are not limited to, leafy vegetables, fruit vegetables, root vegetables, grains (rice, barley, wheat, corn, etc.), mushrooms, fruit trees, cha (tea), and the like. The amount of fertilizer applied (nitrogen equivalent amount) is not particularly limited, but may be, for example, 1 to 70 kgN / time or 1 to 50 kgN / time per 10 ares.

When used for plant cultivation, the sludge fertilizer of the present invention can bring about an increase in yield as compared with many conventional sewage sludge fertilizers. The sludge fertilizer of the present invention has both immediate and slow effects.

In one embodiment, the sludge fertilizer of the present invention, when used for tea cultivation, can bring about an increase in yield and can also adjust the composition ratio of tea leaves.

For example, by using the sludge fertilizer of the present invention together with other fertilizer raw materials (for example, oil cake such as rapeseed oil cake) in an appropriate mixing ratio (for example, sludge fertilizer of the present invention: oil cake such as rapeseed oil cake = 10:90). By using in a mass ratio of ~ 60: 40, 15: 85 ~ 55: 45, or 25: 75 ~ 50: 50), the amount of flavor component (eg, theanin) can be increased.

For example, by using the sludge fertilizer of the present invention in an appropriate mixing ratio together with other fertilizer raw materials (for example, oil cake such as rapeseed oil cake) (for example, sludge fertilizer of the present invention: oil cake such as rapeseed oil cake = 65:35. By using in a mass ratio of ~ 100: 0, 70: 30 ~ 100: 0, or 75: 25 ~ 100: 0), the amount of the first tea catechins can be reduced.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the technical scope of the present invention is not limited to these examples.

[Example 1] Preparation of sewage sludge fertilizer Conditional anaerobic fermentation sewage sludge fertilizer of the present invention using sewage sludge (dehydrated sludge; moisture content 75.5%), rice bran, bamboo waste, and dried shochu lees as fertilizer raw materials. SW was prepared.

Specifically, sewage sludge (1/3 amount) is spread on the bottom layer, and rice bran (1/2 amount), bamboo waste (1/2 amount), water (1/2 amount), and shochu lees are placed on top of it. Dry solids (1/2 amount), sewage sludge (1/3 amount), shochu lees dry solids (1/2 amount), bamboo waste (1/2 amount), rice bran (1/2 amount), and water (1/2 amount) is placed in layers in this order to form a laminate, and finally sewage sludge (1/3 amount) is placed and the whole (upper part and side surface) is covered with sewage sludge with high water content. The initial state of the anaerobic condition was constructed. The thickness of each layer was about 3 to 30 cm.

Part of the water content of the sewage sludge is absorbed by rice bran, bamboo scraps, and dried solids of shochu lees, while the water added between the fertilizer raw materials makes the total water content (moisture content) about 60%. It was adjusted. The water added between the fertilizer raw materials was sprayed over the entire surface of the fertilizer raw material layer.

In this way, the fertilizer raw materials were deposited so as to form a fertilizer raw material body having a bottom surface of 2 m × 2 m, a top surface of 1.5 m × 1.5 m, and a height of 0.8 m as a whole. FIG. 1 schematically shows a method of laminating (depositing) a sandwich-type fertilizer raw material used here. The fertilizer raw material was fermented for over 3 months under conditional anaerobic conditions. Under conditioned anaerobic conditions, unlike aerobic conditions, forced aeration is not performed, so fermentation involving conditioned anaerobic bacteria is performed, in which ammonia gas is not emitted and odors are less likely to be emitted.

During the fermentation period, it was cut back by a wheel loader approximately once a month (3 times in total; 36th, 67th, and 98th days of fermentation). When the temperature 30 cm and 60 cm below the top surface of the fertilizer raw material was measured over time, the temperature rose as the fermentation progressed and exceeded 60 ° C on the 65th to 70th days of fermentation, but 55 after that. It dropped to about ℃. Fertilizer preparation (composting) was completed after the third rounding on the 98th day from the start of fermentation.
Table 1 shows the mixing ratio of the raw materials in the obtained conditional anaerobic fermentation sewage sludge fertilizer SW.

[Example 2] Organism community structure analysis in the fertilizer preparation process Changes in the bacterial flora in the fertilizer raw material during the fertilizer preparation (composting) in Example 1 were investigated over time. DNA from a sample of fertilizer raw material collected at each turning (collected at a depth of 30 to 90 cm from the top surface of the fertilizer raw material) using a DNA extraction kit (FastDNA Spin Kit for Soil; MP Biomedicals). Extraction was performed and PCR amplification was performed. For PCR amplification, Bacteria / Archaea Universal Primer Set Univ515F / Univ909R (Univ515F: 5'-GTGCCAGCMGCCGCGGTAA-3'(SEQ ID NO: 1); Univ909R: 5'-CCCCGYCAATTCMTTTRAGT-3' (SEQ ID NO: 2)) 16S rRNA gene was nucleic acid amplified using. The amplification product was purified using the QIAquick PCR Purification Kit (QIAGEN), followed by DNA sequence analysis using MiSeq (Illumina) and MiSeq reagent kit v3 (Illumina), and the open source software QIIME 2 (Bolyen E., et. Data analysis was performed using al., (2019) Nature Biotechnology 37: 852-857., Https://doi.org/10.1038/s41587-019-0209-9).

As a result, it was shown that the bacteria of the order Bacillales increased during the composting process and existed as a dominant species at the completion of composting (1st turn-back: 20.8%, 2nd turn-back: 62.5). %, At the time of the third turning back: 80.3%). That is, bacteria of the order Bacillales accounted for 80% of the microorganisms in the conditional anaerobic fermentation sewage sludge fertilizer SW at the time of completion of composting.

Furthermore, in particular, related species of Cerasibacillus quisquiliarum, which is a high-temperature bacterium of the order Bacillales (16S rRNA gene homology 95%, abundance ratio: 0.5-56.0%) and Sinibacillus. It was shown that related species of soli) (16S rRNA gene homology 98%, abundance ratio: 0.2-26.8%) are predominant.

Furthermore, two types of fertilizers (sewage sludge mixed compost A and B) prepared using raw materials such as field soil and soil improvement material TYK (component analysis results are shown in Table 3) were prepared for sewage sludge (dehydrated sludge). Similarly, the structure of the microbial community in the composting process was analyzed. The fertilizer raw materials shown in Table 2 were thoroughly mixed, deposited and fermented on an oxygen-free supply for over 3 months. During the fermentation period, it was cut back about once a month. DNA was extracted from the sample collected at the time of cutback in the same manner as above, the 16S rRNA gene was nucleic acid amplified, and sequence analysis was performed.

As a result, in the sewage sludge mixed compost A, a group of microorganisms belonging to the order Clostridiales existed as dominant species (at the first turn-back: 20.2%, at the second turn-back: 12.4%, at the third turn-back). : 21.6%). In sewage sludge mixed compost A, in addition to anaerobic bacteria belonging to the order Crostridium, closely related species of conditional anaerobic Massilibacterium senegalense belonging to the order Basilidium (homologity 98%, abundance ratio: The presence of 1.0 to 14.5%) confirmed that anaerobic fermentation had occurred in the composting of sewage sludge mixed compost A. On the other hand, in the sewage sludge mixed compost B, bacteria belonging to Actinomycetales including actinomycetales exist as dominant species (1st turn-back: 32.1%, 2nd turn-back: 33.5%, 3rd turn-back). Time: 35.2%), especially the genus Actinomadura was present. As described above, it was shown that even in the case of fertilizer produced by composting sewage sludge, the bacterial flora differs greatly depending on the raw material and the composting method.

[Example 3] Measurement of nitrogen mineralization rate The nitrogen mineralization rate (fertilizer efficiency) of various fertilizers was measured. As the fertilizer, the conditional anaerobic fertilized sewage sludge fertilizer SW produced according to the blending ratio shown in Table 1 in Example 1, and as a comparative example, rapeseed oil cake, cow manure compost, chicken manure compost, aerobic fertilized sewage sludge fertilizer CSK (commercially available product). ), Aerobic fermentation sewage sludge fertilizer KG (prepared by composting device Kaguya Hime), sewage sludge mixed compost C, sewage sludge mixed compost D were tested. The composting device Kaguya Hime is a small composting device that can adjust the air volume (NFN300, agricultural and livestock trial type; Fujihira Kogyo Co., Ltd.).

Aerobic fertilized sewage sludge fertilizer KG (prepared by composting device Kaguya Hime) is 40% sewage sludge (dehydrated sludge), 30% bamboo waste, 20% rice bran, 10% dry solids of sweet potato shochu (all dry weight%). After adjusting the water content to about 60%, mixing and stirring, fill the washing net (6.25 kg; 2.5 kg in dry weight), and perform aerobic fermentation in an environment adjusted to an aeration rate of 0.4 mL / min. Manufactured by composting.

Sewage sludge mixed compost C is made by adjusting the water content of sewage sludge (dehydrated sludge) 49.0%, field soil 18.1%, soil improvement material TYK 32.9% [dry weight%] to about 60%, and using sewage sludge on the outside. It was prepared by mixing and stirring without covering and then fermenting under conditional anaerobic conditions.

Sewage sludge mixed compost D is sewage sludge (dehydrated sludge) 11.0%, bamboo waste 8.7%, rice bran 5.6%, sweet potato shochu lees stock solution 2.8%, field soil 40.1%, soil improvement material TYK 15.6% [dry weight%]. The water content was adjusted to about 60%, and the mixture was mixed and stirred without covering the outside with sewage sludge, and then fermented under conditional anaerobic conditions.

Mix 10 g of Andosols (air-dried soil) and 200 mg of fertilizer, put them in a 100 mL culture bottle, add distilled water to adjust the water content to 60% of the maximum capacity, and then cultivate at 25 ° C for 140 days. The nitrogen mineralization test was carried out. Samples were taken over time during the test period. Add 50 mL of 10% potassium chloride to the culture bottle containing the sample, shake for 30 minutes, filter with a filter paper, and apply 10 mL of the filtrate to the distillation method to measure the amount of ammonia nitrogen and nitrate nitrogen. The amount of soil-derived nitrogen was subtracted to calculate (quantify) the inorganic nitrogen content. The nitrogen mineralization rate (fertilization efficiency)% was calculated according to the following formula.
Nitrogen mineralization rate (fertilizer efficiency)% = [Inorganic nitrogen content in each sample (N mg / g fertilizer)] / [Total nitrogen content in fertilizer at the start of culture (N mg / g fertilizer)] x 100

The results are shown in FIGS. 2 to 4. The nitrogen mineralization rates (fertilizer efficiency) of rapeseed oil cake, cow dung compost, chicken manure compost, and existing aerobic fertilized sewage sludge fertilizer CSK after 140 days of cultivation were 58.5%, 35.5%, 27.0%, and 67.2%, respectively. However, the nitrogen mineralization rate (fertilizer efficiency) of the conditional anaerobic fermentation sewage sludge fertilizer SW of the present invention was 88.3%, which was much higher than those of the comparative examples (Fig. 2). On the other hand, the nitrogen mineralization rates (fertilizer efficiency) of rapeseed oil cake, aerobic fermented sewage sludge fertilizer CSK, and aerobic fermented sewage sludge fertilizer KG after 140 days of cultivation, calculated by another test system, were 60.3% and 64.5, respectively. % And 62.3%, showing the same nitrogen mineralization rates as each other (Fig. 3). The nitrogen mineralization rates (fertilization efficiency) of sewage sludge mixed compost C and sewage sludge mixed compost D calculated by another test system after 140 days of cultivation at 25 ° C were 49.8% and 35.5%, respectively, which are so high. The nitrogen mineralization rate was not shown (Fig. 4).

From the above results, it was shown that the conditional anaerobic fermentation sewage sludge fertilizer SW of the present invention has a significantly higher nitrogen mineralization rate (fertilizer efficiency) than conventional fertilizers and other sewage sludge fertilizers.

Conditional anaerobic fermentation Sewage sludge fertilizer After forming a laminate by the same method using the same fertilizer raw material as SW, the laminate is mixed once as a whole, then adjusted to the same shape as the laminate, and the ground surface is prepared. A fertilizer raw material was prepared by covering the entire outside except sewage sludge (1/3 amount), and when conditional anaerobic fermentation was carried out in the same manner, the composition, nitrogen content and nitrogen similar to those of the conditional anaerobic fermentation sewage sludge fertilizer SW were obtained. Conditional anaerobic fermentation sewage sludge fertilizer SWM showing the mineralization rate was obtained (nitrogen content 4.04% of conditional anaerobic fermentation sewage sludge fertilizer SWM, nitrogen content 3.91% of conditional anaerobic fermentation sewage sludge fertilizer SW). This fertilizer SWM was generally low in mass.

[Example 4] Component analysis of fertilizer The components of various fertilizers tested in Examples 2 and 3 were analyzed by a conventional method. Regarding the inorganic components, P ₂ O ₅ was analyzed by the ammonia vanadomolybdate method, and K ₂ O, MgO, and Ca O were analyzed by the atomic absorption method. Heavy metal components were analyzed by ICP mass spectrometry for As, Cr, Cd, Pb and Al, reduction vaporization for Hg, and atomic absorption spectrometry for Cu, Zn and Ni. The C / N ratio was calculated from the total carbon content and total nitrogen content in the compost. Lignin, cellulose and hemicellulose were quantified according to the method of PJ Van Soest et al. Specifically, among the fiber components, ADF (acidic detergent fiber: lignin + cellulose) and NDF (neutral detergent fiber: lignin + cellulose + hemicellulose) are detergent analysis methods, and the amount of lignin is Van Soest and McQueen's. The amount was quantified by the method, and the amount of hemicellulose was determined from the difference between the amount of NDF and the amount of ADF, and the amount of cellulose was determined from the difference between the amount of ADF and the amount of lignin. The results are shown in Table 3.

As shown in Table 3, the conditional anaerobic fertilized sewage sludge fertilizer of the present invention has a lower heavy metal content than other sewage sludge fertilizers, and has a heavy metal content to the same extent as cow dung compost, horse manure compost, and horse manure compost. Was shown to be reduced. It was also shown that the conditional anaerobic fermentation sewage sludge fertilizer of the present invention contains a large amount of fiber components, has good water retention, and has a low potassium content.

[Example 5] Application of conditional anaerobic fermentation sewage sludge fertilizer of the present invention to tea cultivation In tea cultivation, fertilizer is generally applied in 7 batches. In this example, three of them, that is, three times when nutrients are stored in the tree body (second autumn fertilizer (late September to early October), first spring fertilizer (mid-February), For the second spring fertilizer (early March)), fertilizer was applied using the test fertilizer (6 to 24 kgN / 10a fertilizer).

The test fertilizers were (i) conventional fertilizer mixed with rapeseed oil lees and leaf mold, (ii) conventional fertilizer mixed with rapeseed oil lees and mushroom waste fungus bed, (iii) rapeseed oil lees and aerobic fertilized sewage sludge fertilizer CSK (= 50). %: 50%) and mushroom waste bed mixed fertilizer, and (iv) rapeseed oil lees and conditional anaerobic fertilizer sewage sludge fertilizer SW (= 50%: 50%) and mushroom waste bed mixed fertilizer of the present invention. Was used.
After fertilization, the growth condition and yield of tea leaves were investigated. Table 4 shows the results for Ichibancha (tea leaves).

As shown in Table 4, the conditional anaerobic fermented sewage sludge fertilizer of the present invention increases the number of new leaves, the number and weight of total shoots, and a remarkable increase in yield as compared with other fertilizers. Brought about.
Similar results were obtained for the second and third teas (tea leaves).
Furthermore, the components of the first tea (tea leaves) (Table 5) and the third tea (tea leaves) (Table 6) were analyzed.

As shown in Tables 5 and 6, in the test plots in which 50% of the sewage sludge fertilizer CSK or the conditional anaerobic fermentation sewage sludge fertilizer SW was used as the test fertilizer (excluding leaf mold and waste fungus bed), the fertilizer was higher than the conventional fertilizer. It was shown that the theanin content of tea leaves was increased, and that the theanin content was further increased, especially when the conditional anaerobic fermentation sewage sludge fertilizer SW was used. On the other hand, the content of catechins is lower in the test plots in which 50% of sewage sludge fertilizer CSK or conditional anaerobic fermentation sewage sludge fertilizer SW was used as the test fertilizer (for fertilizer components excluding humus or waste fungus bed). A trend was shown. A similar test was conducted using 50% of sewage sludge fertilizer CSK (excluding leaf mold and waste fungus bed) as a test fertilizer (sewage sludge fertilizer CSK + rapeseed oil cake (25%: 75%) + waste fungus bed). Similarly, the theanine content of tea leaves tended to increase and the catechin content tended to decrease as compared with conventional fertilizers.

Theanine is an umami component, and catechin is a bitter component having functionality such as an antioxidant effect. It was shown that the conditional anaerobic fermentation sewage sludge fertilizer of the present invention can be used to produce tea leaves having a high umami component content.

Claims (10)

A sludge material including a sludge layer, an organic fertilizer material layer, and a woody biomass layer is formed, and then the outside is covered with a sludge layer to prepare a fertilizer raw material, which is conditioned anaerobically fertilized. How to make fertilizer. The method according to claim 1, wherein the laminate includes a sludge layer sandwiched vertically by either or both of an organic fertilizer material layer and a woody biomass layer. The method according to claim 1 or 2, wherein the laminate includes at least one of an oil-based organic fertilizer material layer and a shochu lees layer as an organic fertilizer material layer. From the lower layer to the upper layer, the laminate forms a sludge layer, an oil-based organic fertilizer material layer, a woody biomass layer, a shochu lees layer, a sludge layer, a shochu lees layer, a woody biomass layer, and an oil-based organic fertilizer material layer. The method of claim 3, comprising a structure laminated in order. The method according to any one of claims 1 to 4, further comprising mixing at least a part of the laminate before covering the outside with a sludge layer. A sludge fertilizer produced by the method according to any one of claims 1 to 5. The sludge fertilizer according to claim 6, wherein the sludge fertilizer contains Bacillus order bacteria as a dominant species. The sludge fertilizer according to claim 6 or 7, wherein the C / N ratio is 7 or more. The sludge fertilizer according to any one of claims 6 to 8, wherein the heavy metal content is 50 mg or less per 1 kg of sludge fertilizer. A method for cultivating a plant, which comprises applying the sludge fertilizer according to any one of claims 6 to 9 to the plant.

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