Sludge volume reduction system

Abstract

To provide a sludge volume reduction system providing an efficient method of cooling solubilized sludge to realize increase in the operating rate of a sludge solubilizing device and in the sludge treatment efficiency and to make the efficiency of solid-liquid separation after solubilization treatment more efficient while treating unpleasant odor emitted from the solubilized sludge.SOLUTION: A sludge volume reduction system 1 comprises a solubilizing device 52 solubilizing sludge separated from a sludge separation mechanism 20 using high temperature / high pressure water, a post-solubilization storage tank 54, i.e., a non-pressure container connected to the solubilizing device 52 to store the solubilized sludge, a flash steam discharge line 146 connected to the post-solubilization storage tank 54 to discharge flash steam generated in the post-solubilization storage tank 54, and a flash steam treatment unit 100 connected to the flash steam discharge line 146 to treat organic substances included in the flash steam.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sludge volume reduction system. [Background technology]

[0002] A method combining hydrothermal treatment and microbial treatment is known as a method for reducing the volume of organic waste, particularly organic sludge discharged during organic wastewater treatment such as activated sludge. In this treatment method, the solid components of the organic sludge are solubilized by hydrothermal treatment. Subsequently, the liquid components of the solubilized organic sludge are subjected to microbial treatment. Patent Document 1 discloses an example of such an organic waste treatment method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-021797 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in hydrothermal treatment, a form is known in which the sludge is heated by blowing steam into a solubilization device containing the sludge, thereby solubilizing the sludge.

[0005] Solubilization equipment using hydrothermal treatment is usually a pressure vessel. Sludge containing a large amount of water is heated in a sealed vessel above the boiling point of water, and the high-temperature, high-pressure water breaks down the organic polymers that make up the sludge into smaller molecules, thereby solubilizing it.

[0006] The components solubilized by hydrothermal treatment of sludge have improved biodegradability, and so microbial treatment can convert them into carbon dioxide, methane, etc., thereby reducing the volume of the sludge. However, because microorganisms die in high-temperature environments, the sludge must be cooled after solubilization before being subjected to microbial treatment.

[0007] However, if the sludge after solubilization treatment is cooled in the solubilization device, the next solubilization treatment cannot be started during the cooling process, which reduces the operating rate of the solubilization device and ultimately reduces the sludge treatment efficiency.

[0008] In addition, it is possible to increase the sludge solubilization rate and, therefore, the sludge volume reduction rate by making the reaction conditions of the hydrothermal treatment more severe (increasing the temperature, pressure, or time, etc.). However, as the solubilization rate increases, excessive degradation of the sludge occurs, resulting in the generation of volatile organic compounds, and the sludge after solubilization treatment will emit an unpleasant odor.

[0009] Another issue is that metal components in sludge and charcoal produced as a side reaction during hydrothermal treatment have low solubility in water, resulting in the formation of a solubilized residue after hydrothermal treatment. This solubilized residue cannot be decomposed by microorganisms. Therefore, chemicals such as pH adjusters and coagulants must be added to the solubilized sludge to flocculate the solubilized residue, and then the sludge must be separated into a (highly biodegradable) liquid component and a (less biodegradable) solubilized residue using a thickener or dehydrator. Naturally, efficient solid-liquid separation methods (such as using less chemicals, miniaturizing thickeners and dehydrators, and using less energy) are required.

[0010] Therefore, the present invention aims to provide an efficient method for cooling solubilized sludge, thereby improving the operating rate of the solubilization equipment and ultimately the efficiency of sludge treatment, and to provide a sludge volume reduction system that treats the unpleasant odors (volatile organic substances) emitted from solubilized sludge while improving the efficiency of solid-liquid separation after solubilization treatment (reducing the use of chemicals, reducing the size of concentrators and dehydrators, saving power, etc.). [Means for solving the problem]

[0011] The sludge volume reduction system of the present invention is a sludge volume reduction system comprising an activated sludge treatment apparatus and a hydrothermal solubilization apparatus, wherein the activated sludge treatment apparatus comprises an aerobic tank and a sludge separation mechanism, and the hydrothermal solubilization apparatus comprises a solubilization apparatus that solubilizes sludge separated from the sludge separation mechanism with high-temperature, high-pressure water, a storage tank that is a non-pressure vessel connected to the solubilization apparatus for storing the solubilized sludge, a flash steam discharge line connected to the storage tank for discharging flash steam generated in the storage tank, and a flash steam treatment section connected to the flash steam discharge line for treating organic matter contained in the flash steam. [Effects of the Invention]

[0012] According to the present invention, by providing an efficient cooling method for solubilized sludge, it is possible to increase the operating rate of the solubilization equipment and, in turn, the efficiency of sludge treatment. It is also possible to provide a sludge volume reduction system that treats the unpleasant odors (volatile organic substances) emitted from solubilized sludge while improving the efficiency of solid-liquid separation after solubilization treatment (reducing the use of chemicals, reducing the size of concentrators and dehydrators, saving power, etc.). [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a sludge volume reduction system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing the schematic configuration of a sludge volume reduction system 1 according to one embodiment of the present invention. The sludge volume reduction system 1 is a system for reducing the volume of sludge to be disposed of as industrial waste. The sludge volume reduction system 1 includes an activated sludge treatment apparatus 10 and a hydrothermal solubilization apparatus 50.

[0015] The activated sludge treatment device 10 is a device that decomposes organic matter and the like using activated sludge. The activated sludge treatment device 10 includes an adjustment tank 12, an aerobic tank line 102, and an aerobic tank 14. The adjustment tank 12 is a tank for adjusting the amount of water to be treated that is treated in the aerobic tank 14. The adjustment tank 12 stores the water to be treated. The aerobic tank 14 is a tank for decomposing organic matter contained in the water to be treated using microorganisms. The aerobic tank 14 holds a high concentration of aerobic microorganisms in the form of activated sludge. The aerobic tank line 102 is a line connected at one end to the adjustment tank 12 and at the other end to the aerobic tank 14. The water to be treated flows from the adjustment tank 12 to the aerobic tank 14 through the aerobic tank line 102.

[0016] The activated sludge treatment apparatus 10 further includes a sludge separation mechanism 20. The sludge separation mechanism 20 separates the treated liquid treated in the aerobic tank 14 into solid and liquid.

[0017] The sludge separation mechanism 20 includes a separation tank 22 and a separation tank line 104. The separation tank 22 is a tank for performing solid-liquid separation of the water to be treated that has been treated in the aerobic tank 14. The separation tank line 104 is a line connected at one end to the aerobic tank 14 and at the other end to the separation tank 22. The water to be treated that has been treated in the aerobic tank 14 flows from the aerobic tank 14 to the separation tank 22 through the separation tank line 104.

[0018] The sludge separation mechanism 20 further includes a treated water line 112. One end of the treated water line 112 is connected to the separation tank 22. The liquid separated in the separation tank 22 is discharged as treated water E1 from the separation tank 22 to the outside of the activated sludge treatment device 10 through the treated water line 112. Arrow 302 in Figure 1 indicates the flow of treated water E1.

[0019] The sludge separation mechanism 20 further includes a post-separation storage tank 24 and a post-separation storage tank line 114. The post-separation storage tank 24 is a tank for storing excess sludge. Excess sludge refers to solid components that have been separated into solid and liquid in the separation tank 22. The post-separation storage tank line 114 is a line connected at one end to the separation tank 22 and at the other end to the post-separation storage tank 24. The excess sludge that has been separated into solid and liquid in the separation tank 22 flows from the separation tank 22 to the post-separation storage tank 24 through the post-separation storage tank line 114. Arrow 304 in FIG. 1 indicates the flow of excess sludge.

[0020] The sludge separation mechanism 20 further includes a dehydrator 26 and a dehydrator line 116. The dehydrator 26 is a machine that dehydrates excess sludge. The dehydrator 26 may be a thickener. The dehydrator line 116 is a line connected at one end to the post-separation storage tank 24 and at the other end to the dehydrator 26. The excess sludge stored in the post-separation storage tank 24 flows from the post-separation storage tank 24 to the dehydrator 26 through the dehydrator line 116.

[0021] The sludge separation mechanism 20 further includes a post-dehydration storage tank 28 and a post-dehydration storage tank line 118. The post-dehydration storage tank 28 is a tank for storing dehydrated sludge. Dehydrated sludge refers to sludge after being dehydrated by the dehydrator 26. The post-dehydration storage tank line 118 is a line connected at one end to the dehydrator 26 and at the other end to the post-dehydration storage tank 28. The dehydrated sludge dehydrated by the dehydrator 26 flows from the dehydrator 26 to the post-dehydration storage tank 28 through the post-dehydration storage tank line 118. Arrow 306 in Figure 1 indicates the flow of dehydrated sludge.

[0022] The sludge separation mechanism 20 further includes an industrial waste line 120. One end of the industrial waste line 120 is connected to the post-dehydration storage tank 28. The dehydrated sludge stored in the post-dehydration storage tank 28 is discharged as industrial waste E2 from the post-dehydration storage tank 28 to the outside of the activated sludge treatment device 10 through the industrial waste line 120.

[0023] The sludge separation mechanism 20 further includes a desorption liquid tank 30 and a desorption liquid tank line 122. The desorption liquid tank 30 is a tank for storing liquid generated by dehydration by the dehydrator 26. The desorption liquid tank line 122 is a line connected at one end to the dehydrator 26 and at the other end to the desorption liquid tank 30. The liquid generated by dehydration by the dehydrator 26 flows from the dehydrator 26 to the desorption liquid tank 30 through the desorption liquid tank line 122.

[0024] The sludge separation mechanism 20 further includes an equalization tank line 124 and an equalization tank line pump 32. The equalization tank line 124 is a line connected at one end to the desorption liquid tank 30 and at the other end to the equalization tank 12. The liquid stored in the desorption liquid tank 30 flows to the equalization tank 12 through the equalization tank line 124. The equalization tank line pump 32 is a pump provided in the equalization tank line 124. The liquid stored in the desorption liquid tank 30 is forced to flow into the equalization tank 12 by the equalization tank line pump 32.

[0025] The hydrothermal solubilization apparatus 50 will now be described. The hydrothermal solubilization apparatus 50 includes a solubilization apparatus 52 and a solubilization apparatus line 142. The solubilization apparatus 52 is an apparatus for solubilizing the dewatered sludge produced in the sludge separation mechanism 20. The solubilization apparatus 52 can be formed of a pressure vessel. The solubilization apparatus line 142 is a line connected at one end to the post-dehydration storage tank 28 and at the other end to the solubilization apparatus 52. The dewatered sludge stored in the post-dehydration storage tank 28 flows from the post-dehydration storage tank 28 to the solubilization apparatus 52 via the solubilization apparatus line 142.

[0026] The hydrothermal solubilization apparatus 50 further includes a solubilization apparatus line pump 60 and a solubilization apparatus line valve 62. The solubilization apparatus line pump 60 is a pump provided in the solubilization apparatus line 142. The dewatered sludge stored in the post-dehydration storage tank 28 is caused to flow into the solubilization apparatus 52 by the solubilization apparatus line pump 60. The solubilization apparatus line valve 62 is a valve provided in the solubilization apparatus line 142 downstream of the solubilization apparatus line pump 60. The solubilization apparatus line valve 62 makes it possible to switch whether or not dewatered sludge flows through the solubilization apparatus line 142 and to adjust the amount of dewatered sludge flowing through the solubilization apparatus line 142.

[0027] The hydrothermal solubilization apparatus 50 further includes a steam line 150 and a steam line valve 64. The steam line 150 is a line connected at one end to the solubilization apparatus 52. Steam S is supplied to the solubilization apparatus 52 via the steam line 150. The steam line valve 64 is a valve provided on the steam line 150. The steam line valve 64 makes it possible to switch whether or not steam S flows through the steam line 150 and to adjust the amount of steam S flowing through the steam line 150.

[0028] The hydrothermal solubilization apparatus 50 further includes a post-solubilization storage tank 54, a post-solubilization storage tank line 144, and a post-solubilization storage tank line valve 66. The post-solubilization storage tank 54 may be simply referred to as a storage tank. The post-solubilization storage tank 54 is a tank for storing sludge solubilized in the solubilization apparatus 52. The post-solubilization storage tank 54 can be formed of a non-pressure vessel. The post-solubilization storage tank line 144 is a line connected at one end to the solubilization apparatus 52 and at the other end to the post-solubilization storage tank 54. The sludge solubilized in the solubilization apparatus 52 flows from the solubilization apparatus 52 to the post-solubilization storage tank 54 through the post-solubilization storage tank line 144. The post-solubilization storage tank line valve 66 is a valve provided in the post-solubilization storage tank line 144. The post-solubilization storage tank line valve 66 makes it possible to switch whether or not solubilized sludge flows through the post-solubilization storage tank line 144 and to adjust the amount of solubilized sludge flowing through the post-solubilization storage tank line 144. The post-solubilization storage tank line valve 66 can be, for example, an electric valve.

[0029] The hydrothermal solubilization apparatus 50 further includes a water and / or chelating agent supply line 148 and a water and / or chelating agent supply line pump 68. The water and / or chelating agent supply line 148 may be referred to as a supply line. The water and / or chelating agent supply line 148 is a line connected at one end to the post-solubilization storage tank 54. Water and / or chelating agent WC is supplied to the post-solubilization storage tank 54 via the water and / or chelating agent supply line 148. The water and / or chelating agent supply line pump 68 is a pump provided in the water and / or chelating agent supply line 148. The water and / or chelating agent is supplied to the post-solubilization storage tank 54 by the water and / or chelating agent supply line pump 68.

[0030] The hydrothermal solubilization apparatus 50 further includes an air line 152 and an air line pump 70. The air line 152 is a line connected at one end to the post-solubilization storage tank 54. Air A is supplied to the post-solubilization storage tank 54 via the air line 152. The air line pump 70 is a pump provided on the air line 152. Air is supplied to the post-solubilization storage tank 54 by the air line pump 70.

[0031] The hydrothermal solubilization apparatus 50 further includes a flash steam treatment section 100 and a flash steam discharge line 146. The flash steam treatment section 100 treats organic matter contained in the flash steam discharged from the post-solubilization storage tank 54. In the example shown in FIG. 1 , the flash steam treatment section 100 is the aerobic tank 14. The flash steam discharge line 146 is a line connected at one end to the post-solubilization storage tank 54 and at the other end to the flash steam treatment section 100. The flash steam discharged from the post-solubilization storage tank 54 flows from the post-solubilization storage tank 54 to the flash steam treatment section 100 through the flash steam discharge line 146. Arrow 312 in FIG. 1 indicates the flow of flash steam. Note that the flash steam discharge line 146 is always open, i.e., it is always open and not closed by a valve or the like, and is connected to the post-solubilization storage tank 54. The flash steam discharge line 146 is also equipped with a check valve or vacuum breaker valve (not shown). By installing a check valve or a vacuum breaker valve, it is possible to prevent backflow in the flash steam discharge line 146 even when the internal pressure of the post-solubilization storage tank 54 drops due to cooling or the like. Furthermore, by connecting the flash steam discharge line 146 to the post-solubilization storage tank 54 in a constantly open state, it is possible to avoid the post-solubilization storage tank 54 being designated as a pressure vessel.

[0032] The hydrothermal solubilization apparatus 50 further includes a solubilized supernatant liquid line 180, a first valve 71, a second valve 72, a third valve 73, a fourth valve 74, a fifth valve 75, and a solubilized supernatant liquid line pump 82. The solubilized supernatant liquid line 180 includes, as output lines 160, a first output line 161, a second output line 162, a third output line 163, a fourth output line 164, a fifth output line 165, and a discharge line 167. One end of each of the first output line 161, the second output line 162, the third output line 163, the fourth output line 164, and the fifth output line 165 is connected to the post-solubilization storage tank 54 at different heights. The other ends of the first outlet line 161, the second outlet line 162, the third outlet line 163, the fourth outlet line 164, and the fifth outlet line 165 are connected to one end of a discharge line 167. The other end of the discharge line 167 is connected to the adjustment tank 12. The solubilized supernatant liquid obtained by solid-liquid separation in the storage tank after solubilization flows to the adjustment tank 12 through the first outlet line 161, the second outlet line 162, the third outlet line 163, the fourth outlet line 164, or the fifth outlet line 165, and further through the solubilized supernatant liquid line 180 and the discharge line 167. Each of the first outlet line 161, the second outlet line 162, the third outlet line 163, the fourth outlet line 164, and the fifth outlet line 165 is provided with a valve. The first valve 71 is a valve provided in the first outlet line 161. The second valve 72 is a valve provided in the second outlet line 162. The third valve 73 is a valve provided in the third outlet line 163. The fourth valve 74 is a valve provided in the fourth outlet line 164. The fifth valve 75 is a valve provided in the fifth outlet line 165. The valves provided in the outlet lines enable switching whether or not the solubilized supernatant flows through the outlet lines and adjustment of the amount of solubilized supernatant flowing through the outlet lines. Depending on which valve is opened, it is possible to switch the height from which the solubilized supernatant flows out of the post-solubilization storage tank 54. The solubilized supernatant line pump 82 is a pump provided in the solubilized supernatant line 180. The solubilized supernatant is flowed into the adjustment tank 12 by the solubilized supernatant line pump 82. Arrow 324 in FIG. 1 indicates the flow of the solubilized supernatant.

[0033] The hydrothermal solubilization apparatus 50 further includes a solubilized residue discharge line 170, a residue storage line 172, a residue dehydration line 174, and a solubilized residue discharge line pump 80. The solubilized residue discharge line 170 is a line having one end connected to the post-solubilization storage tank 54 and the other end connected to a storage / dehydration branch point 201. One end of the solubilized residue discharge line 170 is preferably connected near the bottom of the post-solubilization storage tank 54. The residue storage line 172 is a line having one end connected to the storage / dehydration branch point 201 and the other end connected to the post-separation storage tank 24. The residue dehydration line 174 is a line having one end connected to the storage / dehydration branch point 201 and the other end connected to the dehydrator 26. The solubilized residue obtained by solid-liquid separation in the post-solubilization storage tank 54 flows from the post-solubilization storage tank 54 to the storage / dehydration branch point 201 via the solubilized residue discharge line 170. The solubilized residue that has flowed to the storage / dehydration branch point 201 can flow to the post-separation storage tank 24 via the residue storage line 172. The solubilized residue that has flowed to the storage / dehydration branch point 201 can flow to the dehydrator 26 via the residue dehydration line 174. As described above, the dehydrator 26 may be a concentrator. The storage / dehydration branch point 201 may be provided with a switching device (not shown) for switching whether the solubilized residue flows to the residue storage line 172 or the residue dehydration line 174, or only one of the residue storage line 172 and the residue dehydration line 174 may be provided. The solubilized residue discharge line pump 80 is a pump provided in the solubilized residue discharge line 170. The solubilized residue is caused to flow to the post-separation storage tank 24 and / or the dehydrator 26 by the solubilized residue discharge line pump 80. Arrow 322 in Figure 1 indicates the flow of the solubilized residue.

[0034] The sludge volume reduction system 1 may further include a control unit (not shown). The control unit can control the opening and closing of the valves and the operation of the pumps described above.

[0035] The volume reduction of sludge in the sludge volume reduction system 1 will now be described. The solubilization device 52 of the hydrothermal solubilization apparatus 50 solubilizes the sludge separated from the sludge separation mechanism 20 with high-temperature, high-pressure water. Specifically, dewatered sludge flows from the post-dehydration storage tank 28 into the solubilization device 52 through the solubilization device line 142. At this time, the solubilization device line valve 62 opens, and the solubilization device line pump 60 operates. Steam S is supplied to the solubilization device 52 through the steam line 150. At this time, the steam line valve 64 opens, and the solubilization device line valve 62 and the post-solubilization storage tank line valve 66 close. The supply of steam S increases the temperature of the sludge inside the solubilization device 52, and the pressure inside the solubilization device 52 increases. Exposing the sludge to high temperature and high pressure breaks down the sludge inside the solubilization device 52 into smaller molecules, and at least a portion of the sludge is solubilized.

[0036] Next, the solubilized sludge is transferred to the post-solubilization storage tank 54. There is high pressure inside the solubilization device 52. Therefore, by opening the post-solubilization storage tank line valve 66 of the post-solubilization storage tank line 144, the solubilized sludge is pushed out by the internal pressure of the solubilization device 52 and transferred from the solubilization device 52 to the post-solubilization storage tank 54 through the post-solubilization storage tank line 144. If the post-solubilization storage tank line valve 66 is an electric valve, the sludge can be transferred to the post-solubilization storage tank 54 by gradually opening the post-solubilization storage tank line valve 66.

[0037] In the post-solubilization storage tank 54, the solubilized sludge is stored, flashed, cooled, and subjected to solid-liquid separation. Explaining flashing, a flash steam discharge line 146 that is always open is connected to the post-solubilization storage tank 54. Therefore, flash steam generated from the solubilized sludge transferred to the post-solubilization storage tank 54 at high temperature and high pressure flows out from the post-solubilization storage tank 54 through the flash steam discharge line 146. The organic matter that has been degraded into small molecules in the solubilization device 52 is easily volatilized. At least a portion of the degraded organic matter flows out of the post-solubilization storage tank 54 together with the flash steam.

[0038] Furthermore, the solubilized sludge transferred from the solubilization device 52 to the post-solubilization storage tank 54 is cooled efficiently due to the pressure release. Transferring the sludge to the post-solubilization storage tank 54 can accelerate the cooling of the solubilized sludge, particularly to temperatures around 100°C.

[0039] Furthermore, organic matter that has been reduced in molecular weight tends to emit an odor. In the sludge volume reduction system of this embodiment, a flash steam discharge line 146 that is always open is connected to the post-solubilization storage tank 54. Therefore, organic matter that tends to emit an odor flows out of the post-solubilization storage tank 54 through the flash steam discharge line 146. Therefore, for example, even if the post-solubilization storage tank 54 is open at room temperature, odor can be reduced.

[0040] Furthermore, since sludge solubilization is usually performed in a batch process, the use of a post-solubilization storage tank 54 for receiving the sludge after solubilization can improve the utilization rate of the solubilization device 52, i.e., the pressure vessel.

[0041] The flash steam treatment unit 100 will now be described. The flash steam treatment unit 100 is a unit that treats organic matter contained in the flash steam. In the example shown in FIG. 1 , the flash steam treatment unit 100 is the aerobic tank 14. When the flash steam treatment unit 100 is the aerobic tank 14, the flash steam is injected into, for example, the bottom of the aerobic tank 14. By injecting the flash steam into the aerobic tank 14, the odor of the flash steam can be trapped in the aerobic tank 14. In addition, by injecting the flash steam into the aerobic tank 14, the liquid temperature in the aerobic tank 14 can be increased. Increasing the liquid temperature in the aerobic tank 14 can promote the decomposition of waste by aerobic microorganisms.

[0042] The sludge volume reduction system 1 of this embodiment, as described above, can achieve the following benefits. By transporting the solubilized sludge, which contains a large amount of water and is in a high-temperature, high-pressure state, to a storage tank that is constantly open to the atmosphere while undergoing flash vaporization, the sludge can be instantly cooled to 100°C. Furthermore, the hydrothermal solubilization apparatus, once emptied by the transport, can immediately be used for the next solubilization treatment, thereby improving the operating rate of the hydrothermal solubilization apparatus and, ultimately, the sludge treatment efficiency. Furthermore, the storage tank is constantly maintained at atmospheric pressure through the flash steam discharge line and flash steam treatment unit, thereby avoiding the need for a pressure vessel and reducing equipment costs. Furthermore, the release of unpleasant odors from the solubilized sludge, particularly volatile organic compounds, into the atmosphere can be suppressed.

[0043] In the example shown in FIG. 1 , the flash steam treatment unit 100 is an aerobic tank 14. However, the flash steam treatment unit 100 is not limited to being an aerobic tank 14. The flash steam treatment unit 100 may be an apparatus or treatment form that performs at least one of scrubber treatment, biological treatment, adsorption treatment, and combustion treatment. The above-described flash steam treatment unit 100 can suppress the release of unpleasant odors and their causative substances, such as volatile organic compounds, into the atmosphere, generated by hydrothermal treatment, i.e., hydrothermal solubilization treatment, with simple equipment. Among the above examples, the flash steam treatment unit 100 is preferably an aerobic tank 14 as shown in FIG. 1 . When the flash steam treatment unit 100 is an aerobic tank 14, the flash steam discharge line 146 is connected to the aerobic tank 14, and the organic matter contained in the flash steam is dissolved in the water in the aerobic tank 14 and subjected to biological treatment. When the flash steam treatment unit 100 is an aerobic tank 14, additional flash steam treatment equipment is not required, and unpleasant odors generated by hydrothermal treatment and their causative substances, such as volatile organic compounds, can be trapped and decomposed. It is also possible to heat the aerobic tank 14. Heating the aerobic tank 14 can promote the decomposition of organic matter by activated sludge in the aerobic tank 14.

[0044] The hydrothermal solubilization apparatus 50 may further include an air supply system for supplying outside air to the lower portion of the post-solubilization storage tank 54. The air supply system includes the air line 152 and air line pump 70 described above. The end of the air line 152 on the post-solubilization storage tank 54 side is located near the bottom of the post-solubilization storage tank 54. The air supply system can aerate the solubilized sludge. Aerating the solubilized sludge in the post-solubilization storage tank 54 has the following effects: heat exchange with ambient air at room temperature, accelerated cooling due to the promoted latent heat of vaporization of water, reduced odor due to the volatilization of VOCs (volatile organic compounds), and prevention of backflow of flash steam. The air line 152 is equipped with a check valve (not shown). The check valve prevents backflow in the air line 152 even when the internal pressure of the air line 152 drops, such as when air is not supplied. As described above, aeration of the solubilized sludge can promote the vaporization of substances that cause unpleasant odors generated by hydrothermal treatment, such as volatile organic compounds. In addition to the cooling effect of the supplied ambient air, the cooling process can be accelerated by the latent heat of vaporization of the volatile organic compounds and water. Furthermore, supplying air can prevent backflow in the flash steam line, which can cause negative pressure to build up in the storage tank during cooling.

[0045] In the post-solubilization storage tank 54, the solubilized sludge undergoes solid-liquid separation. Because the hydrothermal solubilization residue has excellent settling properties, when the transfer of the solubilized sludge from the solubilization device 52 to the post-solubilization storage tank 54 or the aeration by the air supply equipment is stopped, the solubilized sludge quickly settles to the bottom of the post-solubilization storage tank 54. One end of the solubilized residue discharge line 170 is connected near the bottom of the post-solubilization storage tank 54. The solubilized residue discharge line 170 is then connected to the post-separation storage tank 24 or the dehydrator 26 via a storage / dehydration branch point 201. The dehydrator 26 can be a thickener. With this configuration, the thickener or dehydrator 26 can be used to thicken and / or dehydrate the sludge, i.e., excess sludge, discharged from the activated sludge treatment device 10 and the solubilized residue discharged from the hydrothermal solubilization device 50, thereby reducing additional capital investment. It is also possible to carry out a mixed treatment of the excess sludge and the solubilized residue, or to switch between the treatments using a timer or the like.

[0046] In the post-solubilization storage tank 54, the solubilized sludge undergoes solid-liquid separation. The liquid component remains in the post-solubilization storage tank 54 as a supernatant liquid. One end of a discharge line is connected to the post-solubilization storage tank 54. The discharge line is connected to a position above the solubilized residue discharge line 170. The discharge line is also connected to the adjustment tank 12 via a solubilized supernatant liquid line 180. With this configuration, the solubilized supernatant liquid is extracted from the post-solubilization storage tank 54 and supplied to the aerobic tank 14. Therefore, the solubilized supernatant liquid can be decomposed by the activated sludge contained in the aerobic tank 14.

[0047] The solubilized supernatant line 180 may include multiple outlet lines, one end of which is connected to the post-solubilization storage tank 54 at different heights, and a discharge line 167 to which the other ends of the multiple outlet lines are connected. Each of the multiple outlet lines is equipped with a valve for opening and closing the flow path. This configuration allows the solubilized supernatant, with reduced solubilized residue contamination, to be introduced into the aerobic tank 14 or anaerobic layer by changing the valve to be opened depending on the height of the residue settling surface in the solubilized supernatant. The anaerobic tank will be described later. Furthermore, if the solubilized residue after the supernatant is extracted is supplied to the dehydrator 26 or concentrator, the amount of pH adjuster, flocculant, and other additives required for the dehydration and concentration processes can be reduced, thereby reducing the use of chemicals. Furthermore, the amount of wastewater processed by the dehydrator 26 or concentrator can be reduced, allowing for the dehydrator 26 or concentrator to be made smaller and consume less power.

[0048] The hydrothermal solubilization apparatus 50 includes a water and / or chelating agent supply line 148 that supplies at least one of water and a chelating agent to the storage tank. The provision of the water and / or chelating agent supply line 148 can prevent organic matter and metal ions from precipitating from the solubilized supernatant due to a drop in temperature. Consequently, the solubilization rate immediately after the hydrothermal treatment can be maintained even after cooling.

[0049] The above describes one embodiment of the present invention. However, the present invention is not limited to the above embodiment and various modifications, variations, and combinations are possible. For example, an anaerobic tank can be provided midway along the solubilized supernatant line 180. By providing an anaerobic tank, an increase in the load on the aerobic tank 14 due to the treatment of the solubilized supernatant can be suppressed.

[0050] Furthermore, if a boiler device is installed in the sludge volume reduction system 1, the thermal energy of the boiler blow water or exhaust gas can be used as the thermal energy for hydrothermal solubilization. This reduces the need for additional energy such as heat or pressure. The boiler blow water or exhaust gas can also be used to neutralize the solubilized sludge. This reduces the cost of neutralizing the boiler blow water or solubilized sludge and suppresses the emission of acid gases from the boiler. It also reduces the need to add alkaline or ionic components.

[0051] (1) The sludge volume reduction system is A sludge volume reduction system comprising an activated sludge treatment device and a hydrothermal solubilization device, the activated sludge treatment device includes an aerobic tank and a sludge separation mechanism; The hydrothermal solubilization apparatus includes a solubilization device that solubilizes the sludge separated from the sludge separation mechanism with high-temperature, high-pressure water, a storage tank that is a non-pressure container connected to the solubilization device for storing the solubilized sludge, a flash steam discharge line connected to the storage tank and discharging flash steam generated in the storage tank, and a flash steam treatment unit connected to the flash steam discharge line for treating organic matter contained in the flash steam. (2) In the above sludge volume reduction system, The flash steam treatment section performs at least one of scrubber treatment, biological treatment, adsorption treatment, and combustion treatment. (3) In the above sludge volume reduction system, The flash steam discharge line is connected to the aerobic tank, and the organic matter contained in the flash steam is dissolved in the water in the aerobic tank and biologically treated. (4) In the above sludge volume reduction system, The hydrothermal solubilization apparatus further includes an air supply system for supplying outside air to the lower part of the storage tank. (5) In the above sludge volume reduction system, At least one of a concentrator or a dehydrator is further provided between the activated sludge treatment device and the hydrothermal solubilization device, The storage tank further includes a solubilized residue discharge line for extracting the solubilized residue from the bottom thereof and supplying the solubilized residue to the concentrator or the dehydrator. (6) In the above sludge volume reduction system, The apparatus further includes a solubilized supernatant line for withdrawing the solubilized supernatant from the storage tank and supplying it to the aerobic tank. (7) In the above sludge volume reduction system, An anaerobic tank is further provided in the solubilized supernatant line. (8) In the above sludge volume reduction system, the solubilized supernatant line includes a plurality of outlet lines, one end of which is connected to the storage tank at different heights, and a discharge line to which the other end of the plurality of outlet lines is collected; Each of the plurality of outlet lines is provided with a valve for opening and closing the flow path. (9) In the above sludge volume reduction system, The hydrothermal solubilization apparatus further includes a supply line that supplies at least one of water and a chelating agent to the reservoir.

[0052] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] This disclosure includes matters that contribute to achieving Goal 6 of the SDGs (Sustainable Development Goals), "Clean water and sanitation," and Goal 7, "Affordable and clean energy." [Explanation of symbols]

[0053] 1 Sludge volume reduction system 10. Activated sludge treatment equipment 12 Adjustment tank 14 Aerobic tank 20 Sludge separation mechanism 22 Separation tank 24 Post-separation storage tank 26 Dehydrator 28 Storage tank after dehydration 30 Desorption tank 50 Hydrothermal solubilization equipment 52 Solubilizer 54 Post-solubilization storage tank 100 Flash steam treatment section

Claims

1. A sludge volume reduction system comprising an activated sludge treatment device and a hydrothermal solubilization device, the activated sludge treatment device includes an aerobic tank and a sludge separation mechanism; The hydrothermal solubilization apparatus is a sludge volume reduction system comprising: a solubilization apparatus that solubilizes sludge separated from the sludge separation mechanism using high-temperature, high-pressure water; a storage tank that is a non-pressure container connected to the solubilization apparatus for storing the solubilized sludge; a flash steam discharge line connected to the storage tank for discharging flash steam generated in the storage tank; and a flash steam treatment unit connected to the flash steam discharge line for treating organic matter contained in the flash steam.

2. The sludge volume reduction system according to claim 1 , wherein the flash steam treatment unit performs at least one of a scrubber treatment, a biological treatment, an adsorption treatment, and a combustion treatment.

3. 2. The sludge volume reduction system according to claim 1, wherein the flash steam discharge line is connected to the aerobic tank, and the organic matter contained in the flash steam is dissolved in water in the aerobic tank and biologically treated.

4. The sludge volume reduction system according to claim 1 , wherein the hydrothermal solubilization device further comprises an air supply system for supplying outside air to a lower portion of the storage tank.

5. At least one of a concentrator or a dehydrator is further provided between the activated sludge treatment device and the hydrothermal solubilization device, The sludge volume reduction system according to any one of claims 1 to 3, further comprising a solubilized residue discharge line that extracts the solubilized residue from the bottom of the storage tank and supplies it to the concentrator or the dehydrator.

6. 4. The sludge volume reduction system according to claim 1, further comprising a solubilized supernatant line for withdrawing the solubilized supernatant from the storage tank and supplying it to the aerobic tank.

7. The sludge volume reduction system according to claim 6, further comprising an anaerobic tank in the solubilized supernatant line.

8. the solubilized supernatant line includes a plurality of outlet lines, one end of which is connected to the storage tank at different heights, and a discharge line to which the other end of the plurality of outlet lines is collected; The sludge volume reduction system according to claim 6, wherein each of the plurality of outlet lines is provided with a valve for opening and closing the flow path.

9. The sludge volume reduction system according to claim 1 or 2, wherein the hydrothermal solubilization device further comprises a supply line for supplying at least one of water and a chelating agent to the storage tank.

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