Manufacturing method of greening materials

Abstract

To provide a method for manufacturing a greening material using an alternative material that is inexpensive and is easy to obtain.SOLUTION: A method for manufacturing a greening material includes: a kneading step S1 of producing a kneaded product by kneading a neutralized combustion ash after subjected to neutralization treatment by bringing biomass combustion ash generated by biomass combustion into contact with carbon dioxide gas containing carbon dioxide, soil generated by water purification after subjected to dehydration treatment, a drainage material, a bark compost; and a cleaning step S2 of removing exuded drainage by supplying water droplets to the kneaded product.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a greening material. [Background technology]

[0002] Conventionally, there has been known a vegetation material that is a mixture of soil generated from water purification plants, coconut shell fiber as a moisture adjusting material, and clinker ash (coal ash) as a drainage material. For example, Patent Document 1 discloses a vegetation base material to which soil generated from water purification plants, bark compost, peat moss, crushed coconut, and charcoal have been added. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-73372 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the coconut shell fiber used in conventional greening materials is imported from overseas and therefore expensive.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a method for manufacturing greening materials using alternative materials that are low cost and easy to obtain. [Means for solving the problem]

[0006] In order to achieve the above-mentioned objectives, one embodiment of the method for manufacturing greening materials of the present disclosure includes a kneading step in which neutralized combustion ash generated by burning biomass is neutralized by bringing carbon dioxide gas containing carbon dioxide into contact with neutralized combustion ash, dehydrated water purification waste soil, drainage material, and bark compost to produce a kneaded mixture, and a washing step in which water droplets are supplied to the kneaded mixture to remove any seeped wastewater.

[0007] The biomass combustion ash is fly ash.

[0008] In a preferred embodiment of the method for producing a greening material, in the washing step, the amount and speed of water droplets supplied are controlled so as to maintain the kneaded material in a stationary state.

[0009] In a preferred embodiment of the method for producing a greening material, the washing step is carried out by recovering the wastewater until a liquid-solid ratio, which indicates the ratio of the weight of the recovered wastewater to the weight of the kneaded material, reaches a predetermined value. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a method for manufacturing greening materials using alternative materials that are low cost and easy to obtain. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a flow chart showing the flow of a method for producing a greening material according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a manufacturing system for manufacturing the greening material according to the embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of a testing device corresponding to the neutralization treatment device shown in FIG. [Figure 4] FIG. 4 is a graph showing the results of a pH dependency test of biomass combustion ash. [Figure 5] FIG. 5 is a schematic diagram showing an example of a testing device corresponding to the cleaning device shown in FIG. [Figure 6] FIG. 6 is a graph showing the relationship between the liquid-solid ratio and the electrical conductivity. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to the description of the following embodiments. Furthermore, the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially identical. Furthermore, the components in the embodiments described below can be variously omitted, replaced, or modified without departing from the gist of the present disclosure. In the following embodiments, components necessary for illustrating the embodiments of the present disclosure will be described, and other components will be omitted.

[0013] (Embodiment) Fig. 1 is a flowchart showing the flow of a manufacturing method for a greening material 1 according to an embodiment. As shown in Fig. 1, the manufacturing method for the greening material 1 includes a mixing step S1 and a washing step S2. Fig. 2 is a schematic diagram showing a manufacturing system for manufacturing the greening material 1 according to an embodiment. The greening material 1 according to an embodiment is soil obtained by washing a mixture 2 obtained by mixing neutralized combustion ash 10 obtained by neutralizing biomass combustion ash 12 generated by the combustion of biomass 11, water purification waste soil 20 generated at a water purification plant, drainage material 30, and bark compost 40.

[0014] As shown in Fig. 2, the manufacturing system of the embodiment includes a biomass power generation facility 50, a neutralization treatment device 60, a settling tank 70, a dewatering facility 80, a mixer 90, and a cleaning device 100. In the following explanation, the flow of manufacturing the greening material 1 using the manufacturing system shown in Fig. 2 will be described, along with the neutralized combustion ash 10, water purification soil 20, drainage material 30, and bark compost 40 that constitute the greening material 1, as well as the biomass power generation facility 50, neutralization treatment device 60, settling tank 70, dewatering facility 80, mixer 90, and cleaning device 100 that constitute the manufacturing system.

[0015] In the embodiment, the biomass 11 is woody biomass. Woody biomass includes forest residues such as branches, leaves, treetops, and stumps obtained from forests, sawdust, bark, scrap wood, backboards, and other waste materials from sawmills, and industrial waste such as construction waste and demolished building materials. In the embodiment, the biomass power generation facility 50 shown in FIG. 2 is a facility that generates electricity by directly burning the biomass 11 to turn a steam turbine, or a facility that generates electricity by operating an engine with combustible gases generated by directly burning the biomass 11. In the biomass power generation facility 50, the biomass 11 is burned, generating biomass combustion ash 12 and exhaust gas containing carbon dioxide (CO2).

[0016] Biomass combustion ash 12 is a residue recovered from a combustion furnace or the like that burns biomass 11. In this embodiment, biomass combustion ash 12 refers to fly ash that is blown up together with combustion gas and recovered by a dust collector, and is distinguished from bottom ash that is recovered from the bottom of a combustion furnace or the like. The components of biomass combustion ash 12 mainly include calcium oxide (CaO), silicon dioxide (SiO2), aluminum oxide (Al2O3), chlorine (Cl), etc.

[0017] Biomass combustion ash 12 generated in the biomass power generation facility 50 is transported to a neutralization treatment device 60. In addition, exhaust gas containing carbon dioxide generated by the combustion of biomass 11 is drawn in from the front of the chimney of the combustion furnace or from an inspection hole in the chimney. The exhaust gas is sent to the neutralization treatment device 60 after acidic components in the exhaust gas are removed using a treatment device such as a denitration device.

[0018] In the neutralization treatment device 60, biomass combustion ash 12 transported from the biomass power generation facility 50 is brought into contact with exhaust gas containing carbon dioxide (hereinafter referred to as carbon dioxide) to cause carbonation, thereby lowering the pH and neutralizing the biomass combustion ash. In the following description, the neutralized biomass combustion ash 12 will be referred to as neutralized combustion ash 10. The carbon dioxide to be reacted with the biomass combustion ash 12 does not necessarily have to be exhaust gas generated at the biomass power generation facility 50, but may be exhaust gas generated from a thermal power plant that uses coal, oil, natural gas, or the like as fuel, a factory such as a cement manufacturing plant, a chemical plant, an incineration facility, or the like.

[0019] The neutralization treatment device 60 includes, for example, a container type, a yard pit type, a mechanical agitation type, and the like. The container-type neutralization treatment device 60 is, for example, a portable container with an approximately rectangular parallelepiped shape that can be placed on the bed of a vehicle and is useful when transportation distances are long. The container includes a double-floor treatment tank with a partition wall that vertically divides the internal space. The partition wall is a plate-like member parallel to the bottom of the treatment tank and has multiple vents. In the container-type neutralization treatment device 60, the biomass combustion ash 12 that is brought in is placed on the partition wall. Carbon dioxide is introduced into the space below the partition wall and comes into contact with the biomass combustion ash 12 from below through the vents in the partition wall.

[0020] The yard pit type neutralization treatment device 60 includes, for example, a large treatment yard in which biomass combustion ash 12 can be deposited, and a gas supply nozzle that injects carbon dioxide gas into the layer of deposited biomass combustion ash 12. The yard pit type neutralization treatment device 60 is useful when there is a large amount of biomass combustion ash 12 emitted. The treatment yard may be installed indoors with walls and a ceiling, and carbon dioxide gas may be introduced indoors so that it comes into contact with the layered biomass combustion ash 12 from above.

[0021] The mechanical agitation type neutralization treatment device 60 is a device that can automatically agitate the inside of a treatment tank that contains biomass combustion ash 12 while supplying carbon dioxide gas into the treatment tank. Note that a stirring means may be provided in the container type neutralization treatment device 60. By agitating the biomass combustion ash 12 during the treatment of bringing the biomass combustion ash 12 into contact with carbon dioxide gas, the carbon dioxide gas can be uniformly brought into contact with the biomass combustion ash 12.

[0022] The biomass combustion ash 12 is carbonated by absorbing carbon dioxide. Specifically, calcium components such as calcium oxide contained in the biomass combustion ash 12 are carbonated to produce calcium carbonate (CaCO3). That is, in the neutralization treatment device 60, carbon dioxide is fixed in the biomass combustion ash 12 as carbonate. Furthermore, the neutralization treatment makes heavy metals such as lead (Pb) contained in the biomass combustion ash 12 less soluble, and reduces the electrical conductivity (EC). The biomass combustion ash 12 that has been subjected to the neutralization treatment, i.e., the neutralized combustion ash 10, is transported to the kneader 90.

[0023] Here, the results of verification by the inventors of the present disclosure regarding changes in pH buffer capacity due to neutralization treatment will be described with reference to Figures 3 and 4. Figure 3 is a schematic diagram showing an example of a test device 60A corresponding to the neutralization treatment device 60 shown in Figure 2. Figure 4 is a graph showing the results of a pH dependency test of biomass combustion ash 12.

[0024] In this verification, the change in pH was measured when nitric acid was added to neutralized combustion ash 10 that had been neutralized and to biomass combustion ash 12 that had not been neutralized. The neutralized combustion ash 10 used in this verification was biomass combustion ash 12 that had been mixed with water to have a moisture content of 10 wt%, which was then filled into the test apparatus 60A shown in Figure 3 to a weight of 1500 g DW and neutralized. The biomass combustion ash 12 that had not been neutralized and used in this verification was mixed with water to have a moisture content of 10 wt%.

[0025] In this embodiment, the testing apparatus 60A includes a column made of polyvinyl chloride. The testing apparatus 60A includes a reaction section 61, a resin mesh 62, and an air supply section 63. The reaction section 61 has a cylindrical shape extending vertically, and is the section filled with biomass combustion ash 12. The resin mesh 62 is a resin mesh that closes the lower end of the reaction section 61 and allows the biomass combustion ash 12 to be placed on top of it.

[0026] The gas intake section 63 is located below the reaction section 61 and the resin mesh 62, and is connected to the reaction section 61 via the resin mesh 62. A lower support material 64 is filled inside the gas intake section 63. In this embodiment, the lower support material 64 is gravel. The gas intake section 63 has an gas intake port 65 and receives carbon dioxide gas from the gas intake port 65. The gas intake port 65 supplies carbon dioxide gas to the gas intake section 63 via an gas intake line 66. A flow meter 67 is provided in the gas intake line 66. The flow meter 67 measures the flow rate of carbon dioxide gas supplied to the gas intake section 63.

[0027] In the test device 60A, when carbon dioxide gas is introduced into the air intake section 63 with the biomass combustion ash 12 placed on the resin mesh 62, the carbon dioxide gas passes through the resin mesh 62 and comes into contact with the biomass combustion ash 12 from below. In this verification, the neutralization treatment was carried out under the following conditions: carbon dioxide concentration 10%, aeration speed 0.7 L / m, aeration time 24 hours, and carbon dioxide supply amount 120 g-CO2 / kgDW.

[0028] The horizontal axis of Figure 4 represents the amount (μL) of nitric acid (HNO3) added to the biomass combustion ash 12 and the neutralized combustion ash 10, respectively, and the vertical axis of Figure 4 represents the pH of the biomass combustion ash 12 and the neutralized combustion ash 10, respectively. Also, "fly ash (untreated)" in Figure 4 represents the biomass combustion ash 12 that has not been subjected to a neutralization treatment, and "fly ash (neutralized)" represents the neutralized combustion ash 10 that has been subjected to a neutralization treatment using the testing device 60A for the biomass combustion ash 12. As shown in Figure 4, the pH of the neutralized combustion ash 10 is lower than that of the biomass combustion ash 12. The pH of the biomass combustion ash 12 is not significantly reduced by the addition of nitric acid, but the pH of the neutralized combustion ash 10 is reduced by the addition of nitric acid. In other words, the pH buffering capacity is reduced by the neutralization treatment.

[0029] The water purification waste soil 20 shown in Figure 2 is clayey soil generated during the process of treating water at a water purification plant. At the water purification plant, for example, sludge 21 is settled and separated together with suspended solids, powdered activated carbon, coagulant, etc. in a settling tank 70. The sludge 21 is transferred to dehydration equipment 80 and dehydrated. The dehydration equipment 80 may be a mechanical dehydrator such as a press, or may be a dehydrator that dehydrates by drying in the sun. The dehydrated sludge 21 becomes water purification waste soil 20 and is transferred to a kneader 90.

[0030] The kneading step S1 shown in Figure 1 will now be described. The kneading step S1 is a step in which neutralized combustion ash 10, water purification generated soil 20, drainage material 30, and bark compost 40 are kneaded together to produce a kneaded product 2. The drainage material 30 is, for example, clinker ash. The bark compost 40 is an organic fertilizer made by fermenting bark. In this embodiment, the kneading step S1 is performed using a kneader 90 shown in Figure 2.

[0031] In the kneading step S1, neutralized combustion ash 10, water purification generated soil 20, drainage material 30, and bark compost 40 are fed into a kneader 90 in a ratio of 4-10:3-5:1-2:0.3-1, and kneaded for 5-10 seconds by the kneader 90. In the kneader 90, the neutralized combustion ash 10 and water purification generated soil 20 may be kneaded first for 5-10 seconds, and then the drainage material 30 and bark compost 40 may be kneaded for 5-10 seconds.

[0032] The washing step S2 shown in Fig. 1 will now be described. The washing step S2 is a step of supplying water droplets to the mixture 2 of the neutralized combustion ash 10, water purification waste soil 20, drainage material 30, and bark compost 40 generated in the mixing step S1, and removing the seeped wastewater to wash the mixture 2. In this embodiment, the washing step S2 is performed by a washing device 100 shown in Fig. 2.

[0033] The cleaning apparatus 100 includes, for example, a container type, a yard pit type, and the like. The container-type cleaning apparatus 100 is, for example, a portable container having a substantially rectangular parallelepiped shape that can be placed on the bed of a vehicle, and may also serve as the container-type neutralization treatment apparatus 60 described above. The container includes a double-floor treatment tank equipped with a partition wall that vertically divides the internal space, a sprinkler that sprays countless water droplets from above into the space above the partition wall, and a drain outlet that discharges wastewater from the space below the partition wall. The partition wall is a plate-like member parallel to the bottom surface of the treatment tank and has multiple water inlets. In the container-type cleaning apparatus 100, the kneaded material 2 that has been brought in is placed on the partition wall.

[0034] The yard pit type cleaning apparatus 100 includes, for example, a large treatment yard where the kneaded material 2 can be piled up, sprinklers that spray countless droplets of water from above, and a drainage tank that collects wastewater. The floor of the treatment yard is formed with multiple gratings with slopes for draining water, and a gutter where the multiple gratings join together and connect to the drainage tank. Note that the yard pit type cleaning apparatus 100 may not have a roof and may use rainfall to spray water instead of sprinklers.

[0035] The washing step S2 is carried out while the kneaded material 2 is left standing, so as to maintain the standing state of the kneaded material 2. In other words, the amount and speed of water droplets supplied are controlled so as to suppress vibration of the kneaded material 2 caused by water when water droplets are supplied to the kneaded material 2. This is to prevent the wet kneaded material 2 from becoming a slurry due to vibration. In the washing step S2, when the supplied water flows from top to bottom and leaches out of the kneaded material 2, chloride ions are eluted with the water and discharged together with the wastewater. This reduces the electrical conductivity of the kneaded material 2. The kneaded material 2 whose electrical conductivity has been reduced to a predetermined value in the washing step S2 can be used as a greening material 1.

[0036] Table 1 shows the physical properties of the greening material 1 of this embodiment. As shown in Table 1, the greening material 1 is manufactured to have a pH of 8 or more and 9 or less, and an electrical conductivity of less than 0.15 S / m.

[0037] [Table 1]

[0038] Here, the results of verification by the inventors of the present disclosure regarding changes in electrical conductivity due to cleaning will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram showing an example of a testing device 100A corresponding to the cleaning device 100 shown in Figure 2.

[0039] In this verification, the electrical conductivity (S / m) was measured when water droplets were supplied to the kneaded material 2 and washed. The kneaded material 2 used in this verification was a prototype soil made by mixing the neutralized combustion ash 10 used in the verification of the neutralization treatment described above, the water purification waste soil 20, clinker ash as a drainage material 30, and bark compost 40.

[0040] In this embodiment, the testing apparatus 100A includes a column made of polyvinyl chloride. The testing apparatus 100A includes a cleaning section 101, a resin net 102, and a drainage section 103. The cleaning section 101 has a cylindrical shape extending in the vertical direction, and is a section into which the kneaded material 2 is filled. The resin net 102 is a resin net that closes the lower end of the cleaning section 101 and allows the kneaded material 2 to be placed on top of it.

[0041] The drainage section 103 is located below the cleaning section 101 and the resin mesh 102, and is connected to the cleaning section 101 via the resin mesh 102. The drainage section 103 is filled with a drainage material 104. In this embodiment, the drainage material 104 is gravel. The drainage section 103 has a drain outlet 105, and discharges wastewater from the drain outlet 105. The drain outlet 105 is connected to a leachate receiver 106 that collects the wastewater. Water is supplied to the cleaning section 101 from a water supply tank 108 via a water supply line 107. The downstream end of the water supply line 107 is connected to the top of the cleaning section 101, and supplies water droplets from above to the kneaded material 2 contained in the cleaning section 101. The water supply line 107 is provided with a pump 109 for sending water from the water supply tank 108 to the cleaning section 101, and a digital timer 110 for controlling the pump 109.

[0042] In the test apparatus 100A, when water droplets are supplied to the cleaning section 101 with the kneaded material 2 placed on the resin mesh 102, the water flows from top to bottom of the kneaded material 2, and the leachate passes through the resin mesh 102 and is collected in the leachate receiver 106 via the drainage section 103. In this verification, 367 g DW of the kneaded material 2 was filled into the cleaning section 101 of the test apparatus 100A, and the cleaning process was carried out at a drip rate of 0.08 L / h.

[0043] FIG. 6 is a graph showing the relationship between the liquid-solid ratio and electrical conductivity (S / m). The liquid-solid ratio shown in FIG. 6 indicates the ratio of the weight of wastewater to the weight of the kneaded material 2 washed in the washing step S2. As shown in FIG. 6, the kneaded material 2 before the washing treatment has an electrical conductivity of 0.28 S / m, which is significantly higher than the target value of 0.15 S / m. In contrast, the kneaded material 2 after the washing treatment has a lower electrical conductivity than before the treatment, and the target value of 0.15 S / m or less can be achieved when the liquid-solid ratio is 0.2 or more. The target value of electrical conductivity is more preferably 0.1 S / m or less, and in this case, the target value of 0.1 S / m or less can be achieved when the liquid-solid ratio is 0.6 or more.

[0044] As described above, the manufacturing method of the greening material 1 of the embodiment includes a kneading process S1 in which neutralized combustion ash 10, which is neutralized by bringing carbon dioxide gas containing carbon dioxide into contact with biomass combustion ash 12 generated by the combustion of biomass 11, dehydrated water purification waste soil 20, drainage material 30, and bark compost 40, are kneaded to produce a kneaded product 2, and a washing process S2 in which water droplets are supplied to the kneaded product 2 to remove any seeped wastewater.

[0045] Combustion ash has excellent moisture and water absorption properties. Therefore, by substituting biomass combustion ash 12 obtained by burning biomass 11 for conventional moisture-regulating materials, a highly permeable greening material 1 can be obtained. Furthermore, by neutralizing the biomass combustion ash 12 by exposing it to carbon dioxide before mixing it with the water purification soil 20, heavy metals such as lead contained in the biomass combustion ash 12 can be made less soluble. This prevents heavy metals such as lead from leaching from the greening material 1 containing the neutralized combustion ash 10. Furthermore, the carbon dioxide used for the neutralization process can be derived from the exhaust gas emitted when the biomass 11 is burned. Therefore, by effectively utilizing carbon dioxide in addition to the biomass combustion ash 12 generated at the biomass power generation facility 50, costs can be reduced. Furthermore, by fixing the exhaust gas generated at the biomass power generation facility 50 as carbonates, the amount released into the atmosphere can be reduced, contributing to the creation of a decarbonized society. Furthermore, by washing the kneaded material 2, when the supplied water flows from the top to the bottom and seeps out, chloride ions are eluted with the water and discharged with the wastewater. As a result, the electrical conductivity of the kneaded material 2 decreases, and the kneaded material 2 can be used as a greening material 1.

[0046] In the method for manufacturing the greening material 1 according to the embodiment, the biomass combustion ash 12 is fly ash. Fly ash has small particle size, so when it is mixed with water, it becomes a slurry. Once it becomes a slurry, it becomes highly viscous and is not suitable as a greening material, so it must be dehydrated again, which increases costs. In this embodiment, the fly ash is mixed as a moisture adjuster and then washed, so the electrical conductivity can be reduced without forming a slurry.

[0047] Furthermore, in the method for producing the greening material 1 of the embodiment, in the washing step S2, the supply amount and supply speed of the water droplets are controlled so as to maintain a stationary state of the kneaded material 2. This makes it possible to suppress vibration of the kneaded material 2 caused by water when supplying the water droplets to the kneaded material 2, and therefore makes it possible to suppress the kneaded material 2 containing moisture from becoming a slurry due to vibration.

[0048] Furthermore, in the method for producing the greening material 1 of the embodiment, the washing step S2 is performed by recovering wastewater until a predetermined value is reached in the liquid-solid ratio, which indicates the ratio of the weight of the recovered wastewater to the weight of the kneaded material 2. For example, by verifying in advance the relationship between the liquid-solid ratio and the electrical conductivity of the kneaded material 2, the washing step S2 can be performed so as to achieve a target value of electrical conductivity (less than 0.15 S / m) based on the liquid-solid ratio, without having to measure the electrical conductivity each time in the washing step S2.

[0049] Note that each configuration described in each embodiment may be combined with other configurations in each embodiment without departing from the spirit of the invention. Furthermore, each of these configurations may be combined with configurations in other embodiments different from each embodiment without departing from the spirit of the invention. Furthermore, various modifications may be made without departing from the spirit of the invention. [Explanation of symbols]

[0050] 1 Greening materials 2. Mixture 10 Neutralized combustion ash 11 Biomass 12 Biomass combustion ash 20 Water purification soil 21 Sludge 30 Drainage material 40 Bark Compost 50 Biomass power generation facilities 60 Neutralization treatment equipment 60A Test Equipment 61 Reaction section 62 Resin mesh 63 Air supply section 64 Lower support material 65 Air supply port 66 Air supply line 67 Flow meter 70 Sedimentation pond 80 Dehydration equipment 90 Mixer 100 Cleaning equipment 100A test equipment 101 Cleaning section 102 Resin mesh 103 Drainage section 104 Drainage material 105 Drain port 106 Leachate receiver 107 Water Supply Line 108 Water Tank 109 Pump 110 Digital Timer

Claims

1. a kneading step of kneading the neutralized combustion ash, which is produced by bringing the biomass combustion ash generated by burning biomass into contact with carbon dioxide gas containing carbon dioxide to neutralize the biomass combustion ash, with dehydrated water purification soil, drainage material, and bark compost to produce a kneaded mixture; a washing step of supplying water droplets to the kneaded material to remove exuded wastewater; A method for manufacturing greening materials, comprising:

2. The biomass combustion ash is fly ash; A method for producing the greening material according to claim 1.

3. In the washing step, the amount and speed of water droplets supplied are controlled so as to maintain the kneaded material in a stationary state. A method for producing the greening material according to claim 1 or 2.

4. In the washing step, the wastewater is collected and the washing step is carried out until a liquid-solid ratio indicating a ratio of a weight of the collected wastewater to a weight of the kneaded product reaches a predetermined value. A method for producing the greening material according to any one of claims 1 to 3.

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