Solid-liquid separation apparatus, organic waste treatment system, and organic waste treatment method

Abstract

A solid-liquid separation apparatus, an organic waste treatment system, and an organic waste treatment method that enable low-cost separation of digested fluids. [Solution] A solid-liquid separation device for separating digestate into solid and liquid, comprising a solid-liquid separation container including an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder, and at least one upward flow generating unit that generates an upward flow containing bubbles in an outer fluid space formed between the outer cylinder and the inner cylinder or an inner fluid space formed inside the inner cylinder, wherein the inner fluid space and the outer fluid space are in communication on the upper and lower sides of the inner cylinder and are configured to form a circulation channel for circulating the digestate and bubbles, and the upward flow generating unit is configured to stop the circulation of the digestate and bubbles.

Description

Technical Field

[0001] The present invention relates to a solid-liquid separation device, an organic waste treatment system, and an organic waste treatment method.

Background Art

[0002] Conventionally, an organic waste treatment apparatus including an anaerobic tank that separates organic waste into biogas and treated water, an MF membrane that filters the treated water obtained in the anaerobic tank, a reverse osmosis membrane (RO membrane) that membrane-separates the treated water filtered by the MF membrane, and an evaporation concentration device that evaporates and concentrates the treated water membrane-separated by the reverse osmosis membrane is known (Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the organic waste treatment apparatus described in Patent Document 1, although the filtration treatment by the MF membrane is performed as a pretreatment for membrane-separating the treated water by the reverse osmosis membrane, the removal of solids contained in the treated water is insufficient only by the filtration treatment by the MF membrane, which causes clogging of the reverse osmosis membrane. In addition, due to the clogging, the replacement frequency of the reverse osmosis membrane increases, resulting in a problem of high running costs.

[0005] The present invention relates to a solid-liquid separation device, an organic waste treatment system, and an organic waste treatment method capable of realizing the separation of digested liquid at low cost.

Means for Solving the Problems

[0006] The solid-liquid separation apparatus according to the present invention is a solid-liquid separation apparatus for separating digestate into solid and liquid, comprising a solid-liquid separation container including an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder, and at least one upward flow generating unit that generates an upward flow containing bubbles in an outer fluid space formed between the outer cylinder and the inner cylinder or an inner fluid space formed inside the inner cylinder, wherein the inner fluid space and the outer fluid space are in communication on the upper and lower sides of the inner cylinder and are configured to form a circulation channel for circulating the digestate and bubbles, and the upward flow generating unit is configured to stop the circulation of the digestate and bubbles.

[0007] In the solid-liquid separation apparatus according to the present invention, the outer cylinder may have at least one solid outlet from which the solid can be discharged, and at least one liquid outlet from which the liquid can be discharged.

[0008] In the solid-liquid separation apparatus according to the present invention, the upward flow generating section may include at least one gas release section located below the vertical midpoint of the solid-liquid separation container, which releases gas into the outer flow space or the inner flow space.

[0009] The solid-liquid separation apparatus according to the present invention includes a top plate portion provided opposite to the upper opening of the inner cylinder, and the lower surface of the top plate portion may have an inclined surface that is central in the planar direction and slopes downward.

[0010] The solid-liquid separation apparatus according to the present invention may include at least one of an inner swirling flow generation unit that converts the flow in the inner flow space into a swirling flow, and an outer swirling flow generation unit that converts the flow in the outer flow space into a swirling flow.

[0011] In the solid-liquid separation apparatus according to the present invention, the inner swirling flow generating section and the outer swirling flow generating section are provided with a plurality of blades arranged at predetermined intervals, and the plurality of blades may have a shape that is curved in the circumferential direction of the inner cylinder.

[0012] In the solid-liquid separation apparatus according to the present invention, the blade portion may be configured to be non-rotatable.

[0013] The organic waste treatment system according to the present invention is an organic waste treatment system for treating organic waste, comprising: a production tank that reacts the organic waste with anaerobic microorganisms to produce biogas and digested sludge; a digested sludge separation device that separates the digested sludge into solid and digested liquid; a solid-liquid separation device that further separates the digested liquid separated by the digested sludge separation device into solid and liquid; and a concentration device that concentrates the liquid separated by the solid-liquid separation device, wherein the solid-liquid separation device comprises a solid-liquid separation container including an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder; and at least one upward flow generating unit that generates an upward flow containing bubbles in an outer fluid space formed between the outer cylinder and the inner cylinder or an inner fluid space formed inside the inner cylinder, wherein the inner fluid space and the outer fluid space are in communication on the upper and lower sides of the inner cylinder and are configured to form a circulation channel for circulating the digested liquid and bubbles, and the upward flow generating unit is configured to stop the circulation of the digested liquid and bubbles.

[0014] The present invention relates to an organic waste treatment method, which is an organic waste treatment method for treating organic waste, comprising: a production step of reacting the organic waste with anaerobic microorganisms to produce biogas and digested sludge; a digested sludge separation step of separating the digested sludge into a solid and a digested liquid; a solid-liquid separation step of further separating the digested liquid separated in the digested sludge separation step into a solid and a liquid; and a concentration step of concentrating the liquid separated in the solid-liquid separation step, wherein the solid-liquid separation step comprises: an inflow step of introducing the digested liquid into a solid-liquid separation container including an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder; a circulation step of circulating the digested liquid and bubbles by generating an upward flow containing bubbles in an outer fluid space formed between the outer cylinder and the inner cylinder or an inner fluid space formed inside the inner cylinder; and a stopping step of stopping the circulation of the digested liquid and bubbles. [Effects of the Invention]

[0015] According to the solid-liquid separation device, organic waste treatment system, and organic waste treatment method of the present invention, it becomes possible to realize the separation of digestion liquid at low cost.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic diagram showing an organic waste treatment system according to the present embodiment. [Figure 2] It is a schematic cross-sectional view showing a solid-liquid separation device according to the present embodiment. [Figure 3] It is an enlarged view showing a part of the solid-liquid separation device according to the present embodiment in an enlarged manner. [Figure 4] It is an enlarged view showing a part of the solid-liquid separation device according to the present embodiment in an enlarged manner. [Figure 5] It is a schematic plan view showing a lower blade part according to the present embodiment. [Figure 6] It is a schematic bottom view showing an upper blade part according to the present embodiment. [Figure 7] It is a schematic diagram showing the flow of solid-liquid separation.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to each claim, and not all combinations of the features described in the embodiments are essential for the solution means of the invention. Also, in the present embodiment, there are cases where the scales and dimensions of each component are exaggeratedly shown, and cases where some components are omitted.

[0018] [Overall Configuration of Organic Waste Treatment System] The organic waste treatment system according to this embodiment is a system for treating organic waste. Examples of organic waste include digested liquid as a residue after fermentation treatment in a biogas plant, but it is not limited thereto. For example, livestock excrement, food waste, food residues, processing residues and residual liquids such as milk and beverages, sludge, agricultural residues, etc., as long as they are mixtures of solids and liquids, and are not limited to organic "waste". Note that the solid may be in an organic state or an inorganic state, and the ratio of solid to liquid is not particularly limited.

[0019] As shown in FIG. 1, the organic waste treatment system 1 includes a production tank 100 that reacts organic waste with anaerobic microorganisms to produce biogas and digested sludge, a gas storage tank 200 that stores the biogas produced in the production tank 100, a sludge storage tank 300 that stores the digested sludge produced in the production tank 100, a digested sludge separation device 400 (primary separation device) that separates the digested sludge stored in the sludge storage tank 300 into solids and digested liquid, a solid-liquid separation device 500 (digested liquid separation device, secondary separation device) that further separates the digested liquid separated by the digested sludge separation device 400 into solids and liquids, a concentration device 600 that concentrates the liquid separated by the solid-liquid separation device 500, a permeate storage tank 700 that stores the permeate that has passed through the concentration device 600, and a concentrated liquid storage tank 800 that stores the concentrated liquid concentrated by the concentration device 600.

[0020] As the separation method by the digested sludge separation device 400, for example, a method of capturing solids with a filter, a method of precipitating solids, a method of floating solids, a method of adsorbing solids to an adsorbent, etc. can be used. As the method of precipitating solids, for example, a static precipitation method, a coagulation precipitation method of adding a coagulant, an electrocoagulation method of charging and aggregating, etc. can be used. As the method of floating solids, for example, an atmospheric pressure flotation method by adding a foaming agent or a foam aid, a pressure flotation method by injecting fine bubbles, etc. can be used. In this embodiment, the digested sludge separation device 400 includes a screen and is configured to capture solids by the screen.

[0021] In this embodiment, the digested sludge separation device 400 has been described as being located upstream of the solid-liquid separation device 500, but the invention is not limited to this configuration, and the device may be located both upstream and downstream of the solid-liquid separation device 500.

[0022] The concentration device 600 is equipped with a filtration membrane, such as a known MF membrane or RO membrane, and is configured to concentrate the liquid using the filtration membrane. Alternatively, the concentration device 600 may also be equipped with an evaporation means for evaporating the liquid, and is configured to concentrate the liquid using the evaporation means.

[0023] Furthermore, the organic waste treatment system 1 includes a gas supply channel 2 that supplies biogas generated in the generation tank 100 to a gas storage tank 200, a first sludge supply channel 3 that supplies digested sludge generated in the generation tank 100 to a sludge storage tank 300, a second sludge supply channel 4 that supplies digested sludge stored in the sludge storage tank 300 to a digested sludge separation device 400, a digested liquid supply channel 5 that supplies the digested liquid separated in the digested sludge separation device 400 to a solid-liquid separation device 500, a liquid supply channel 6 that supplies the liquid separated in the solid-liquid separation device 500 to a concentrate device 600, a permeate supply channel 7 that supplies the permeate that has passed through the concentrate device 600 to a permeate storage tank 700, and a concentrate supply channel 8 that supplies the concentrate concentrated in the concentrate device 600 to a concentrate storage tank 800. The gas supply passage 2, the first sludge supply passage 3, the second sludge supply passage 4, the digestate supply passage 5, the liquid supply passage 6, the permeate supply passage 7, and the concentrated liquid supply passage 8 are each formed in a tubular shape with an internal space that allows fluid to flow through them.

[0024] Furthermore, since known configurations can be used for all components of the organic waste treatment system 1 except for the solid-liquid separator 500, only the configuration of the solid-liquid separator 500 will be described in the following explanation, and the other components will be omitted.

[0025] [Configuration of a solid-liquid separation device] As shown in Figures 2 to 4, the solid-liquid separation device 500 includes a solid-liquid separation container 510 that separates digestate into solid and liquid, an upward flow generating unit 520 that generates an upward flow containing air bubbles inside the solid-liquid separation container 510, a discharge unit 530 that discharges waste from inside the solid-liquid separation container 510, a lower swirling flow generating unit 540 located below the inner cylinder 512 (described later), and an upper swirling flow generating unit 550 located above the inner cylinder 512 (described later).

[0026] <Configuration of a solid-liquid separation container> As shown in Figures 2 to 4, the solid-liquid separation container 510 has an outer cylinder 511 extending vertically and an inner cylinder 512 provided inside the outer cylinder 511.

[0027] In this specification, "vertical" includes both perfectly vertical and nearly vertical. "Nearly vertical" refers to a state that is slightly inclined with respect to the vertical, specifically, a state that is inclined to such an extent that it does not impede the function of the solid-liquid separation device 500.

[0028] The outer cylinder 511 is formed in a cylindrical shape with its upper and lower ends open. The outer cylinder 511 has an inlet 511a into which digested fluid can flow in, a solid outlet 511b into which solids obtained by separating the digested fluid can be discharged, and a liquid outlet 511c into which liquids obtained by separating the digested fluid can be discharged.

[0029] The inlet 511a, solid outlet 511b, and liquid outlet 511c are openings formed from the inner surface to the outer surface of the outer cylinder 511. In addition, known valves may be provided at the inlet 511a, solid outlet 511b, and liquid outlet 511c, and these valves may be opened and closed at any desired timing. The inlet 511a is connected to the digestive fluid supply passage 5 by a tube joint TJ. The liquid outlet 511c is connected to the liquid supply passage 6 by a tube joint TJ.

[0030] The inlet 511a, solid outlet 511b, and liquid outlet 511c may each be provided as one or as two or more. In this embodiment, only one inlet 511a and one liquid outlet 511c are provided, and they are located near the middle of the outer flow space 515, which will be described later. By providing the liquid outlet 511c near the middle of the outer flow space 515, the liquid obtained by separating the digested liquid can be efficiently discharged. On the other hand, two solid outlets 511b are provided, one near the upper part and one near the lower part of the outer flow space 515. By providing the solid outlets 511b near the upper part and the lower part of the outer flow space 515, the solids (floating solids and settled solids) obtained by separating the digested liquid can be efficiently discharged. In this embodiment, as will be described later, since the lower end of the outer cylinder 511 is fitted into the bottom 513, the solid discharge port 511b provided near the bottom of the outer flow space 515 is formed to penetrate the bottom 513.

[0031] The inner cylinder 512 is formed in a cylindrical shape with its upper and lower ends open. The outer diameter of the inner cylinder 512 is smaller than the inner diameter of the outer cylinder 511. Also, the vertical length of the inner cylinder 512 is shorter than the vertical length of the outer cylinder 511. In this embodiment, only one inner cylinder 512 is provided, but it is not limited to this, and two or more may be provided.

[0032] The shapes of the outer cylinder 511 and the inner cylinder 512 are not limited to cylindrical shapes, but may be, for example, rectangular, conical, or pyramidal. Furthermore, a convex or concave portion may be formed in a part of the vertical direction, or it may be formed in a bellows-like shape.

[0033] The solid-liquid separation container 510 has a bottom portion 513 that closes the lower end of the outer cylinder 511 and a top portion 514 that closes the upper end of the outer cylinder 511. The bottom portion 513 is formed in the shape of a bottomed cylinder with an open top. The bottom portion 513 is configured to close the lower end of the outer cylinder 511 by fitting the lower end of the outer cylinder 511 into it. The top portion 514 is formed in the shape of a toped cylinder with an open bottom. The top portion 514 is configured to close the upper end of the outer cylinder 511 by fitting the upper end of the outer cylinder 511 into it.

[0034] Furthermore, the solid-liquid separation container 510 has an outer fluid space 515 formed between the outer cylinder 511 and the inner cylinder 512, and an inner fluid space 516 formed inside the inner cylinder 512. The outer fluid space 515 and the inner fluid space 516 are in communication on the upper and lower sides of the inner cylinder 512, and are configured to form a circulation channel CP for circulating the digested liquid and bubbles.

[0035] <Configuration of the upward flow generation section> As shown in Figures 2 to 4, the upward flow generation unit 520 includes a gas generation unit 521 that generates gas, a gas release unit 522 that releases the gas generated in the gas generation unit 521 into the outer flow space 515 or the inner flow space 516, a gas supply unit 523 that supplies the gas generated in the gas generation unit 521 to the gas release unit 522, and a connecting unit 524 that connects the gas release unit 522 and the gas supply unit 523. In this embodiment, only one upward flow generation unit 520 is provided, but it is not limited to this, and two or more may be provided.

[0036] The gas generating unit 521 is, for example, a fan or a blower. The gas generating unit 521 has a switch 521a for starting or stopping the generation of gas. In other words, the switch 521a is configured to start or stop the release of gas by the gas release unit 522.

[0037] The gas release section 522 is, for example, a tube and is configured to allow gas to flow. One end of the gas release section 522 is connected to the connecting section 524, and the other end of the gas release section 522 is connected to the mounting section 543c of the support section 543, which will be described later. Therefore, the gas release section 522 in this embodiment is configured to release gas into the inner flow space 516. Specifically, the gas release section 522 is configured to release gas into the inner flow space 516 via the support section 543, which will be described later.

[0038] Furthermore, the other end of the gas release section 522 only needs to be located below the vertical midpoint of the solid-liquid separation container 510 from the viewpoint of generating an upward flow, and may be connected to, for example, the outer cylinder 511 or the inner cylinder 512. When the other end of the gas release section 522 is connected to the outer cylinder 511, the gas release section 522 is configured to release gas into the outer flow space 515.

[0039] The gas supply unit 523 is, for example, a tube and is configured to allow gas to flow. One end of the gas supply unit 523 is connected to the gas generation unit 521, and the other end of the gas supply unit 523 is connected to the connection unit 524. The connection unit 524 is, for example, a tube joint and is inserted into an opening (not shown) formed in the top 514.

[0040] The upward flow generating unit 520, having the above configuration, is configured to generate an upward flow containing bubbles in the inner flow space 516 by releasing gas into the inner flow space 516 through the gas release unit 522. When the gas release unit 522 releases gas into the outer flow space 515, the upward flow generating unit 520 generates an upward flow containing bubbles in the outer flow space 515.

[0041] Furthermore, the upward flow generation unit 520 is configured such that the circulation of digested liquid and bubbles in the circulation channel CP can be stopped at any or predetermined timing by the switch 521a stopping the release of gas by the gas release unit 522. The stopping by switch 521a may be performed manually or automatically. Examples of methods for automatically stopping by switch 521a include, but are not limited to, a method in which the switch 521a is turned on and then turned off after a predetermined time has elapsed, or a method in which the switch 521a is turned on and then turned off after a predetermined flow rate has been released.

[0042] <Configuration of the discharge section> As shown in Figures 2 and 3, the discharge section 530 has a cylindrical section 531 for discharging waste from the solid-liquid separation container 510 and a holding section 532 for holding the cylindrical section 531. Examples of waste include excess material (e.g., gas or liquid) that exceeds the volume of the solid-liquid separation container 510.

[0043] The cylindrical portion 531 is formed in a tubular shape with both ends open and is inserted into an opening (not shown) formed in the top portion 514. That is, the upper end of the cylindrical portion 531 is located outside the solid-liquid separation container 510, and the lower end of the cylindrical portion 531 is located inside the solid-liquid separation container 510. The cylindrical portion 531 may be formed by connecting two or more tubes, as shown in Figure 2, or it may be composed of a single tube. The cylindrical portion 531 also has a plurality of inlet holes 531a for allowing gas from inside the solid-liquid separation container 510 to flow into the cylindrical portion 531. The inlet holes 531a are provided in the portion of the cylindrical portion 531 located inside the solid-liquid separation container 510 (in this embodiment, below the axial middle portion of the cylindrical portion 531), and are provided along the axial and circumferential directions of the cylindrical portion 531.

[0044] The holding portion 532 is formed in a disc shape and has a mounting hole 532a in its center for attaching the cylindrical portion 531. The holding portion 532 also has insertion holes 532b at both radial ends for inserting projections 551c formed on the upper end of the top plate portion 551, which will be described later. The holding portion 532 is configured to hold the cylindrical portion 531 by inserting the lower end of the cylindrical portion 531 into the mounting hole 532a. The holding portion 532 is also configured to be attached to the upper end of the top plate portion 551 by inserting the projections 551c into the insertion holes 532b. By attaching the holding portion 532 to the upper end of the top plate portion 551, the inner cylinder 512 can be prevented from floating up. Note that the holding portion 532 is optional, or it may be formed integrally with the upper swirling flow generating portion 550, which will be described later.

[0045] The discharge section 530, having the above configuration, is configured to discharge waste that has flowed into the cylindrical section 531 from the lower end of the cylindrical section 531 and the inlet hole 531a of the cylindrical section 531 to the outside of the solid-liquid separation container 510. The waste discharged from the discharge section 530 can be supplied to, for example, any storage tank.

[0046] <Configuration of lower swirl flow generation section> As shown in Figures 2, 4, and 5, the lower swirling flow generating unit 540 has a weight portion 541 placed on the bottom surface of the bottom portion 513, a plurality of (seven in this embodiment) blade portions 542 (lower blade portions) provided at predetermined intervals in the circumferential direction of the inner cylinder 512, and a support portion 543 capable of supporting the inner cylinder 512.

[0047] The blade portion 542 is provided on the upper surface of the weight portion 541 and is configured to be non-rotatable. Each blade portion 542 extends along the radial direction of the inner cylinder 512 and has a curved shape in the circumferential direction of the inner cylinder 512. In other words, the blade portions 542 are arranged radially around the axis of the inner cylinder 512.

[0048] The inner end of each blade 542 in the direction of extension is located within the region of the inner cylinder 512 in a plan view. On the other hand, the outer end of each blade 542 in the direction of extension is located within the region between the outer cylinder 511 and the inner cylinder 512 in a plan view. Furthermore, each blade 542 is formed so that its height increases from the outer side in the direction of extension to the inner side. This has the advantage of allowing for efficient swirling without obstructing the flow from the outer flow space 515 or the flow from the inner flow space 516.

[0049] The support portion 543 is formed in a cylindrical shape with its upper and lower ends open, and has a shape that tapers from the lower end to the upper end. The support portion 543 has an insertion groove 543a at its upper end into which the lower end of the inner cylinder 512 can be inserted. The insertion groove 543a is formed in a concave shape that recesses downward from the upper end of the support portion 543. The support portion 543 is configured to support the inner cylinder 512 by inserting the lower end of the inner cylinder 512 into the insertion groove 543a.

[0050] The support portion 543 has an annular tubular portion 543b at its lower end that surrounds the blade portion 542. The support portion 543 also has a mounting portion 543c to which the gas release portion 522 is attached.

[0051] The tube section 543b is formed in a tubular shape having an internal space that allows the gas supplied from the gas outlet section 522 to flow. An outlet hole 543d is formed on the inner circumference of the tube section 543b (the end on the vane section 542 side) to allow the gas supplied from the gas outlet section 522 to flow out. In this embodiment, the outlet hole 543d is a plurality of openings formed at predetermined intervals in the circumferential direction of the tube section 543b. The outlet hole 543d may be a single opening, or it may be an annular opening extending along the circumferential direction of the tube section 543b.

[0052] The mounting portion 543c is formed extending upward from a part of the circumferential direction of the pipe portion 543b and is formed in a cylindrical shape with its upper and lower ends open. Therefore, the gas supplied from the gas opening portion 522 flows through the mounting portion 543c and is supplied to the pipe portion 543b. The support portion 543 is configured to connect with the gas opening portion 522 by inserting the mounting portion 543c into the other end of the gas opening portion 522.

[0053] The support portion 543 having the above configuration is provided between the upper surface of the weight portion 541 and the lower end of the inner cylinder 512, and is configured to connect the outer flow space 515 and the inner flow space 516 between the lower end of the support portion 543 and the upper surface of the weight portion 541. Specifically, the support portion 543 is attached to the weight portion 541 by fixing a plurality of fixing parts (not shown) extending from the outer circumference of the pipe portion 543b (the end on the outer cylinder 511 side) to the outer edge of the weight portion 541. In this embodiment, a configuration in which the support portion 543 includes a pipe portion 543b and a mounting portion 543c has been described, but it is not limited to this, and a configuration without these parts is also possible.

[0054] <Configuration of the upper swirling flow generation section> As shown in Figures 2, 3, and 6, the upper swirling flow generation unit 550 has a top plate portion 551 provided opposite the upper opening 512a of the inner cylinder 512, a plurality of (six in this embodiment) blade portions 552 (upper blade portions) provided at predetermined intervals in the circumferential direction of the inner cylinder 512, and a mounting portion 553 that can be attached to the inner cylinder 512.

[0055] The top plate portion 551 has a circular planar shape. Furthermore, the top plate portion 551 has an inclined surface 551a that is located in the center in the planar direction and slopes downward. That is, the top plate portion 551 has a shape where the center in the planar direction is recessed downward, and as a whole, it is formed in a roughly conical shape. From the viewpoint of efficiently circulating the material to be separated and the bubbles, it is sufficient that at least the lower surface of the top plate portion 551 has an inclined surface 551a.

[0056] A communication hole 551b is formed in the center of the top plate portion 551 in the planar direction, communicating with the internal fluid space 516 and the internal space of the cylindrical portion 531. In addition, a plurality of (three in this embodiment) protrusions 551c are formed at the upper end of the top plate portion 551, which are inserted into the insertion hole 532b of the holding portion 532.

[0057] The blades 552 are provided on the lower surface of the top plate 551. Specifically, the blades 552 are formed extending downward from the lower surface of the top plate 551 and are configured to be non-rotatable. Each blade 552 extends along the radial direction of the inner cylinder 512 and has a curved shape in the circumferential direction of the inner cylinder 512. That is, the blades 552 are arranged radially around the axis of the inner cylinder 512.

[0058] The curvature direction of the blade portion 552 may be the same as or different from the curvature direction of the blade portion 542, but it is preferable that they be the same from the viewpoint of efficiently swirling the digestive fluid and bubbles.

[0059] The inner end of each blade 552 in the direction of extension is located within the region of the inner cylinder 512 when viewed from the bottom. On the other hand, the outer end of each blade 552 in the direction of extension is located within the region between the outer cylinder 511 and the inner cylinder 512 when viewed from the bottom. Furthermore, each blade 552 is formed so that its height decreases from the outer side in the direction of extension towards the inner side. This has the advantage of allowing for efficient swirling without obstructing the flow from the outer flow space 515 or the flow from the inner flow space 516.

[0060] The mounting portion 553 is formed in an annular shape that surrounds the lower end of the blade portion 552. In other words, the upper swirling flow generation portion 550 according to this embodiment is configured to connect the outer flow space 515 and the inner flow space 516 between the lower surface of the top plate portion 551, the surface of the blade portion 552, and the inner circumference of the mounting portion 553 (the end on the blade portion 552 side).

[0061] The mounting portion 553 has a mounting groove 553a at its lower end into which the upper end of the inner cylinder 512 can be inserted. The mounting groove 553a is formed in a concave shape that is recessed upward from the lower end of the mounting portion 553. The mounting portion 553 is configured to be attached to the inner cylinder 512 by inserting the upper end of the inner cylinder 512 into the mounting groove 553a.

[0062] <Configuration of the inner swirling flow generation unit and the outer swirling flow generation unit> In this embodiment, either the lower swirling flow generation unit 540 or the upper swirling flow generation unit 550 functions as an inner swirling flow generation unit 560 that converts the flow in the inner flow space 516 into a swirling flow. The other of the lower swirling flow generation unit 540 or the upper swirling flow generation unit 550 functions as an outer swirling flow generation unit 570 that converts the flow in the outer flow space 515 into a swirling flow.

[0063] Whether the lower swirling flow generation unit 540 and the upper swirling flow generation unit 550 function as the inner swirling flow generation unit 560 or the outer swirling flow generation unit 570 depends on the position where the upward flow generation unit 520 generates an upward flow. Specifically, when the upward flow generation unit 520 generates an upward flow in the inner flow space 516, the lower swirling flow generation unit 540 functions as the inner swirling flow generation unit 560, and the upper swirling flow generation unit 550 functions as the outer swirling flow generation unit 570. On the other hand, when the upward flow generation unit 520 generates an upward flow in the outer flow space 515, the lower swirling flow generation unit 540 functions as the outer swirling flow generation unit 570, and the upper swirling flow generation unit 550 functions as the inner swirling flow generation unit 560.

[0064] [Methods for disposing of organic waste] Next, an organic waste treatment method using the organic waste treatment system 1 will be described with reference to Figure 7. The organic waste treatment method according to this embodiment includes a production step of reacting organic waste with anaerobic microorganisms to produce biogas and digested sludge, a digested sludge separation step of separating the digested sludge produced in the production step into solid and digested liquid, a solid-liquid separation step of further separating the digested liquid separated in the digested sludge separation step into solid and liquid, a drying step of drying the solid separated in the solid-liquid separation step, and a concentration step of concentrating the liquid separated in the solid-liquid separation step.

[0065] [Generation process] Organic waste is introduced into the generation tank 100. The organic waste reacts with anaerobic microorganisms within the generation tank 100 to produce biogas and digested sludge. The biogas produced in the generation tank 100 is supplied to the gas storage tank 200 via the gas supply channel 2 and stored in the gas storage tank 200. Meanwhile, the digested sludge produced in the generation tank 100 is supplied to the sludge storage tank 300 via the first sludge supply channel 3 and stored in the sludge storage tank 300.

[0066] [Digested sludge separation process] The digested sludge stored in the sludge storage tank 300 is supplied to the digested sludge separator 400 via the second sludge supply channel 4, where it is separated into solid and digested liquid. The digested liquid separated in the digested sludge separator 400 is supplied to the solid-liquid separator 500 via the digested liquid supply channel 5.

[0067] [Solid-liquid separation process] The solid-liquid separation process according to this embodiment includes an inflow step of introducing digestate into the solid-liquid separation container 510, a circulation step of circulating the digestate and bubbles, a stopping step of stopping the circulation of the digestate and bubbles, a solid discharge step of discharging the solid obtained by separating the digestate, and a liquid discharge step of discharging the liquid obtained by separating the digestate.

[0068] <Inflow process> The digested liquid is introduced into the solid-liquid separation container 510. Specifically, the digested liquid separated in the digested sludge separation device 400 is introduced into the solid-liquid separation container 510 from the inlet 511a. Although the digested sludge separation device 400 removes coarse solids from the digested sludge, the liquid introduced into the solid-liquid separation container 510 still contains many fine solids.

[0069] <Circulation process> As shown in Figure 7, an upward flow containing bubbles B is generated in the inner fluid space 516 (see arrow F1 in Figure 7). Specifically, first, gas generation is started by the switch 521a of the gas generation unit 521, and the generated gas is supplied to the gas release unit 522 via the gas supply unit 523 and the connection unit 524. Next, the gas release unit 522 releases the gas into the inner fluid space 516 via the support unit 543. This generates an upward flow containing bubbles B in the inner fluid space 516. The gas released into the inner fluid space 516 flows between each vane unit 542 and swirls, so a swirling upward flow is generated in the inner fluid space 516. That is, the digested liquid and bubbles B in the inner fluid space 516 rise up the inner fluid space 516 while swirling.

[0070] As the digestive fluid in the inner fluid space 516 rises, the digestive fluid in the outer fluid space 515 is drawn into the inner fluid space 516 (see arrow F2 in Figure 7), and a downward flow is generated in the outer fluid space 515 (see arrow F3 in Figure 7). The digestive fluid drawn from the outer fluid space 515 into the inner fluid space 516 flows between each vane 542, and, combined with the swirling force caused by the gas released from the gas release section 522, rises in the inner fluid space 516 while swirling.

[0071] Meanwhile, the digestive fluid and bubbles B rising in the inner flow space 516 rise to the top plate 551, and then flow along the inclined surface 551a of the top plate 551 into the outer flow space 515, and descend through the outer flow space 515 (see arrow F4 in Figure 7). As the digestive fluid and bubbles B flowing into the outer flow space 515 swirl between each vane 552, a swirling downward flow is generated in the outer flow space 515. In other words, the digestive fluid and bubbles B in the outer flow space 515 descend through the outer flow space 515 while swirling.

[0072] The digested fluid and bubbles B circulate through the circulation channel CP as described above. During this circulation process, some of the suspended solids in the digested fluid settle in the outer fluid space 515 and accumulate at the bottom of the outer fluid space 515.

[0073] Furthermore, during the circulation process described above, the flow velocity increases (pressure decreases) as the digested liquid and bubbles B are drawn from the outer flow space 515 into the inner flow space 516, causing the bubbles B to become finer. In addition, bubbles B circulating in the circulation channel CP become even finer as they swirl between the inner flow space 516 and the outer flow space 515, and as they are sheared by the blades 542 and 552. In other words, the more bubbles B circulate in the circulation channel CP, the finer they become. Also, fine solids contained in the digested liquid are further finened as they are sheared by the blades 542 and 552.

[0074] As described above, the solid-liquid separation apparatus 500 according to this embodiment is configured to generate microbubbles. By generating microbubbles, the total surface area of ​​the bubbles generated in the solid-liquid separation container 510 is increased, thereby improving the separation performance. Microbubbles refer to microbubbles (bubbles with a diameter of 1 μm or more and less than 100 μm) and ultrafine bubbles (bubbles with a diameter of less than 1 μm).

[0075] <Stopping process> The gas generation unit 521 is stopped at any time or at a predetermined timing by the switch 521a. When this is done, the release of gas by the gas release unit 522 is stopped, and the circulation of digested liquid and bubbles B in the circulation channel CP is stopped.

[0076] When circulation stops, bubbles B rise through the inner and outer fluid spaces 516 and 515, adsorbing suspended solids in the digested fluid. As a result, settled solids (solids too large and heavy to float even with the buoyancy of bubbles B) are present at the bottom of the inner and outer fluid spaces 516 and 515, floating solids (solids too large and heavy to float with the buoyancy of bubbles B) are present at the top of the inner and outer fluid spaces 516 and 515, and liquids containing few solids are present in the middle of the inner and outer fluid spaces 516 and 515. In this way, the digested fluid can be separated into solid and liquid.

[0077] <Solid discharge process and liquid discharge process> The solid obtained by separating the digestate is discharged from the solid outlet 511b. The liquid obtained by separating the digestate is discharged from the liquid outlet 511c. After the solid discharge process, the circulation process and the stop process may be repeated to further concentrate the liquid.

[0078] [Drying process] The solid discharged from the solid-liquid separation container 510 is dried. Drying can be carried out by any method, such as sun-drying. The dried solid can be used as solid fertilizer.

[0079] [Concentration process] The liquid discharged from the solid-liquid separation container 510 is supplied to the concentrate 600 via the liquid supply channel 6, where it is concentrated. The permeate that has passed through the concentrate 600 is supplied to the permeate storage tank 700 via the permeate supply channel 7, where it is stored. The permeate stored in the permeate storage tank 700 is circulated to the production tank 100 for reuse in new biogas production. Meanwhile, the concentrated liquid concentrated in the concentrate 600 is supplied to the concentrated liquid storage tank 800 via the concentrated liquid supply channel 8, where it is stored. The liquid supplied to the concentrated liquid storage tank 800 is used as liquid fertilizer.

[0080] As described above, the concentration method used by the concentration device 600 can be a concentration method using a filtration membrane or a concentration method using evaporation. However, from the viewpoint of suppressing the loss of fertilizer components contained in the liquid separated by the solid-liquid separation device 500, it is preferable to use a concentration method using a filtration membrane. Concentration methods using evaporation include, for example, high-temperature drying, reduced-pressure distillation, hot air drying, and sun drying.

[0081] [Advantages of the solid-liquid separation apparatus and organic waste treatment system according to this embodiment] The solid-liquid separation apparatus 500 according to this embodiment is a solid-liquid separation apparatus for separating digestate into solid and liquid, and comprises a solid-liquid separation container 510 including an outer cylinder 511 extending in the vertical direction and at least one inner cylinder 512 provided inside the outer cylinder 511, and at least one upward flow generating unit 520 that generates an upward flow containing bubbles in an outer fluid space 515 formed between the outer cylinder 511 and the inner cylinder 512 or an inner fluid space 516 formed inside the inner cylinder 512, wherein the inner fluid space 516 and the outer fluid space 515 are in communication on the upper and lower sides of the inner cylinder 512 and are configured to form a circulation channel CP for circulating the digestate and bubbles, and the upward flow generating unit 520 is configured to stop the circulation of the digestate and bubbles.

[0082] With the solid-liquid separator 500 having such a configuration, solids in the digestate that are too large and heavy to float even by the buoyancy of the bubbles can be allowed to settle and settle at the bottom of the outer fluid space 515 and the inner fluid space 516. Furthermore, with the solid-liquid separator 500, solids in the digestate that are too large and heavy to float by the buoyancy of the bubbles can be adsorbed onto the bubbles, while the outer fluid space 515 and the inner fluid space 516 can be raised. In other words, with the solid-liquid separator 500, the digestate can be separated into solid and liquid by circulating the digestate and bubbles. In addition, since the solid-liquid separator 500 according to this embodiment can remove most of the solids in the digestate, if, for example, filtration treatment using a filtration membrane is performed as a post-treatment of the solid-liquid separator 500, clogging of the filtration membrane can be suppressed, and the frequency of filtration membrane replacement due to clogging, and consequently the running costs, can be reduced.

[0083] Furthermore, the solid-liquid separation apparatus 500 according to this embodiment does not require the use of a pressure pump or the like to pressurize the raw water to generate bubbles, thus enabling low-cost separation of digestate and offering the advantages of high reliability and durability. In addition, since there is no need to use a pressure pump, there is no need to use a nozzle, which also eliminates the need to replace nozzles due to wear.

[0084] In the solid-liquid separation apparatus 500 according to this embodiment, the outer cylinder 511 has at least one solid discharge port 511b from which solids can be discharged, and at least one liquid discharge port 511c from which liquids can be discharged. A solid-liquid separation apparatus 500 with such a configuration has the advantage that the solids can be used as solid fertilizer and the liquids can be used as liquid fertilizer.

[0085] In the solid-liquid separation apparatus 500 according to this embodiment, the upward flow generation unit 520 is provided with at least one gas release unit 522 located below the vertical midpoint of the solid-liquid separation container 510, which releases gas into the outer fluid space 515 or the inner fluid space 516. With a solid-liquid separation apparatus 500 having such a configuration, an upward flow containing gas bubbles can be generated simply by releasing gas from the gas release unit 522, and the digestate and gas bubbles can be circulated, which has the advantages of separating the digestate at low cost and without losing fertilizer components contained in the digestate, as well as the high durability of the apparatus itself.

[0086] The solid-liquid separation apparatus 500 according to this embodiment includes a top plate portion 551 provided opposite the upper opening 512a of the inner cylinder 512, and the lower surface of the top plate portion 551 has an inclined surface 551a that is inclined downwards and is located in the center in the planar direction. With a solid-liquid separation apparatus 500 having such a configuration, the digested liquid that rises flows along the inclined surface 551a, which has the advantage of efficiently circulating the digested liquid.

[0087] The solid-liquid separation apparatus 500 according to this embodiment includes at least one of an inner swirling flow generation unit 560 that converts the flow in the inner flow space 516 into a swirling flow, and an outer swirling flow generation unit 570 that converts the flow in the outer flow space 515 into a swirling flow. A solid-liquid separation apparatus 500 with such a configuration has the advantage that the digested liquid and bubbles are more easily circulated by the swirling flow. In addition, because the bubbles swirl, they can be made finer. As the bubbles are made finer, the total surface area of ​​the bubbles increases, which improves the separation performance.

[0088] In the solid-liquid separation apparatus 500 according to this embodiment, the inner swirling flow generation unit 560 and the outer swirling flow generation unit 570 are equipped with a plurality of blades 542 (or blades 552) provided at predetermined intervals, and the plurality of blades 542 (or blades 552) have a shape that is curved in the circumferential direction of the inner cylinder 512. The solid-liquid separation apparatus 500 with such a configuration has the advantage that a swirling flow can be generated simply by flowing sludge between each blade 542 (or blade 552). In addition, since the bubbles are sheared by the blades 542 (or blades 552), there is also the advantage that the bubbles can be made finer. As the bubbles are made finer, the total surface area of ​​the bubbles increases, so the separation performance can be improved. Furthermore, not only bubbles but also solids contained in the digestate are sheared by the blades 542 (or blades 552), so there is also the advantage that the solids are made finer and easier to float.

[0089] In the solid-liquid separation apparatus 500 according to this embodiment, the blade portion 542 (or blade portion 552) is configured to be non-rotatable. With a solid-liquid separation apparatus 500 having such a configuration, a swirling flow can be generated without rotating the blade portion 542 (or blade portion 552), which has the advantage of lower costs (for example, the number of parts, power costs, costs associated with parts replacement, etc.). In addition, since the blade portion 542 (or blade portion 552) does not rotate, there is the advantage that fine solids mixed in the digested liquid do not get caught on the blade portion 542 (or blade portion 552).

[0090] The organic waste treatment system 1 according to this embodiment is an organic waste treatment system for treating organic waste, comprising: a production tank 100 that reacts organic waste with anaerobic microorganisms to produce biogas and digested sludge; a digested sludge separation device 400 that separates the digested sludge into solid and digested liquid; a solid-liquid separation device 500 that further separates the digested liquid separated by the digested sludge separation device 400 into solid and liquid; and a concentration device 600 that concentrates the liquid separated by the solid-liquid separation device 500, wherein the solid-liquid separation device 500 comprises an outer cylinder 511 extending in the vertical direction and the outer cylinder 511 The solid-liquid separation container 510 includes at least one inner cylinder 512 located inside, and at least one upward flow generating unit 520 that generates an upward flow containing bubbles in an outer fluid space 515 formed between the outer cylinder 511 and the inner cylinder 512, or in an inner fluid space 516 formed inside the inner cylinder 512. The inner fluid space 516 and the outer fluid space 515 are in communication on the upper and lower sides of the inner cylinder 512, and are configured to form a circulation channel CP for circulating the digested liquid and bubbles. The upward flow generating unit 520 is configured to stop the circulation of the digested liquid and bubbles.

[0091] According to the organic waste treatment system 1 having such a configuration, coarse solids can be removed in the digested sludge separator 400, and fine and minute solids can be largely removed in the solid-liquid separator 500. For example, if the concentrate and 600 are equipped with a filtration membrane, clogging of the filtration membrane can be suppressed, and the frequency of filtration membrane replacement due to clogging, and consequently the running costs, can be reduced. Also, for example, if the concentrate and 600 are equipped with an evaporation means, the loss of fertilizer components due to high-temperature heating can be suppressed. Furthermore, according to the organic waste treatment system 1 according to this embodiment, since there is no need to use coagulants or pressure pumps for solid-liquid separation, there is also the advantage of low manufacturing costs and running costs.

[0092] [Differentiation] The solid-liquid separation apparatus, organic waste treatment system, and organic waste treatment method according to the present invention are not limited to the embodiments described above, and various modifications can be made without departing from the technical concept of the present invention.

[0093] In the embodiments described above, a digested sludge separation device 400 and a concentration device 600 were used in addition to the solid-liquid separation device 500. However, the invention is not limited to these, and devices or means other than the digested sludge separation device 400, the solid-liquid separation device 500, and the concentration device 600 may be used.

[0094] In the embodiments described above, the upper swirling flow generation unit 550 was described as having a top plate portion 551, but it is not limited to this and may not have a top plate portion 551. Also, the top plate portion 551 may not have an inclined surface 551a and may be formed in a flat shape.

[0095] In the embodiments described above, the solid-liquid separation device 500 was described as comprising a lower swirling flow generation unit 540 and an upper swirling flow generation unit 550, but it is not limited to this, and may comprise only one of them, or neither.

[0096] In the embodiments described above, the solid-liquid separation device 500 was described as comprising a top portion 514 that closes the upper end of the outer cylinder 511 and a discharge portion 530 that discharges gas from inside the solid-liquid separation container 510. However, it is not limited to this configuration, and it may also be configured as an open-to-the-air type with the upper ends of the outer cylinder 511 and inner cylinder 512 open, without the top portion 514 and the discharge portion 530.

[0097] In the embodiments described above, the outer cylinder 511 and the bottom portion 513 were described as being formed independently, but the invention is not limited to this, and the outer cylinder 511 and the bottom portion 513 may be formed integrally. Also, for example, the outer cylinder 511, bottom portion 513, weight portion 541 and blade portion 542 may be formed integrally, or the bottom portion 513, weight portion 541 and blade portion 542 may be formed integrally, or the weight portion 541 and blade portion 542 may be formed integrally. Furthermore, the weight portion 541 may not be provided.

[0098] It is clear from the claims that the above-mentioned modifications are included within the scope of the present invention. [Explanation of symbols]

[0099] 1: Organic waste treatment system 2: Gas supply path 3: First sludge supply channel 4: Second sludge supply channel 5: Digestive fluid supply channel 6:Liquid supply path 7: Permeate supply path 8: Concentrate supply path 100: Generation tank 200: Gas storage tank 300: Sludge storage tank 400: Digested sludge separation device 500: Solid-liquid separation equipment 510: Solid-liquid separation container 511: Outer cylinder 511a: Inlet 511b :Solid discharge port 511c:Liquid outlet 512: Inner cylinder 512a: Upper side opening 513: Bottom 514:Top 515:Outer flow space 516:Inner flow space 520: Upward flow generation section 521: Gas generation unit 521a: Switch 522: Gas release section 523: Gas supply unit 524: Connection part 530: Discharge section 531:Cylinder part 531a:Inflow hole 532: Holding part 532a: Mounting hole 532b: Insertion hole 540: Lower swirl flow generation section 541: Weight section 542: Feather part 543: Support part 543a: Insertion groove 543b: Pipe section 543c: Attached part 543d:Outflow hole 550: Upper swirl flow generation section 551: Top panel 551a: Inclined surface 551b:Communication hole 551c:Protrusion 552: Feather part 553: Mounting part 553a: Mounting groove 560: Inner swirling flow generation unit 570:Outer swirl flow generation section 600: Concentrator 700: Permeate storage tank 800: Concentrated liquid storage tank B: Air bubbles CP: Circulation channel TJ: Tube Joint

Claims

1. A solid-liquid separation apparatus for separating digestive fluid into solid and liquid, A solid-liquid separation container comprising an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder, At least one upward flow generating unit that generates an upward flow containing bubbles in the outer flow space formed between the outer cylinder and the inner cylinder or in the inner flow space formed inside the inner cylinder. Equipped with, The inner fluid space and the outer fluid space are connected on the upper and lower sides of the inner cylinder, and are configured to form a circulation channel for circulating the digested liquid and bubbles. The upward flow generating unit is configured to be able to stop the circulation of the digested liquid and bubbles. Solid-liquid separation equipment.

2. The outer cylinder is, At least one solid discharge port capable of discharging the solid, The liquid has at least one liquid outlet from which it can be discharged. It has The solid-liquid separation apparatus according to claim 1.

3. The upward flow generating section includes at least one gas release section located below the vertical midpoint of the solid-liquid separation container, which releases gas into the outer flow space or the inner flow space. The solid-liquid separation apparatus according to claim 1 or 2.

4. It is equipped with a top plate portion that is provided opposite the upper opening of the inner cylinder, The lower surface of the top plate portion has an inclined surface that is central in the planar direction and slopes downward. The solid-liquid separation apparatus according to claim 1 or 2.

5. An inner swirling flow generation unit that converts the flow within the inner flow space into a swirling flow, An outer swirling flow generation unit that converts the flow in the outer flow space into a swirling flow, comprising at least one of the following The solid-liquid separation apparatus according to claim 1 or 2.

6. The inner swirling flow generating unit and the outer swirling flow generating unit are equipped with a plurality of blades arranged at predetermined intervals. The plurality of fin portions have a shape that is curved in the circumferential direction of the inner cylinder. The solid-liquid separation apparatus according to claim 5.

7. The aforementioned blade portion is configured to be non-rotatable. The solid-liquid separation apparatus according to claim 6.

8. An organic waste treatment system for treating organic waste, A production tank that reacts the aforementioned organic waste with anaerobic microorganisms to produce biogas and digested sludge, A digested sludge separation apparatus for separating the digested sludge into solid and digested liquid, A solid-liquid separator further separates the digested liquid separated by the digested sludge separator into solid and liquid components. A concentration device for concentrating the liquid separated by the solid-liquid separation device, Equipped with, The solid-liquid separation apparatus is A solid-liquid separation container comprising an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder, At least one upward flow generating unit that generates an upward flow containing bubbles in the outer flow space formed between the outer cylinder and the inner cylinder or in the inner flow space formed inside the inner cylinder. It has, The inner fluid space and the outer fluid space are connected on the upper and lower sides of the inner cylinder, and are configured to form a circulation channel for circulating the digested liquid and bubbles. The upward flow generating unit is configured to be able to stop the circulation of the digested liquid and bubbles. Organic waste treatment system.

9. A method for treating organic waste, A production step involves reacting the aforementioned organic waste with anaerobic microorganisms to produce biogas and digested sludge, A digested sludge separation step for separating the digested sludge into a solid and a digested liquid, A solid-liquid separation step further separates the digested liquid separated in the digested sludge separation step into solid and liquid, A concentration step for concentrating the liquid separated in the solid-liquid separation step, Includes, The solid-liquid separation step is, An inflow step of introducing the digested liquid into a solid-liquid separation container which includes an outer cylinder extending vertically and at least one inner cylinder provided inside the outer cylinder, A circulation step in which the digested liquid and bubbles are circulated by generating an upward flow containing bubbles in the outer fluid space formed between the outer cylinder and the inner cylinder or in the inner fluid space formed inside the inner cylinder, A stopping step to stop the circulation of the digested liquid and bubbles. including Methods for disposing of organic waste.

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