Diluent adding system

Abstract

To provide a diluent adding system which can be used in a diluent adding system in an organic waste treatment system.SOLUTION: A diluent adding system 100 of adding a diluent to carbonized sludge slurry in an organic waste treatment system including a pretreatment device 2 for carrying out a pretreatment of organic waste, a hydrothermal carbonization device 3 for applying a hydrothermal carbonization treatment to the treated material obtained by the pretreatment, and a solid / liquid separator 4 for subjecting the carbonized sludge slurry obtained by the hydrothermal carbonization treatment to solid / liquid separation, in which the diluent is a separation liquid generated in the organic waste treatment system.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a diluent addition system that adds separated liquid generated in an organic waste treatment system to a carbonized sludge slurry as a diluent. [Background technology]

[0002] Conventionally, a method for producing biomass fuel is known in which a diluent is added to a carbonized sludge slurry obtained after hydrothermal carbonization of organic waste, and then the carbonized sludge slurry is washed (for example, Patent Document 1). In this method for producing biomass fuel, potassium ions contained in the carbonized sludge slurry are removed by adding a diluent to the carbonized sludge slurry for washing, and then performing solid-liquid separation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-206684 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the biomass fuel production method described in Patent Document 1, a large amount of water was required because a diluent was added in an amount about 2 to 25 times the weight of the carbonized sludge slurry (dry base) to perform washing. Therefore, when industrial water or tap water was used as the diluent, this led to an increase in the production cost of biomass fuel.

[0005] Therefore, there is a demand for a diluent addition system that can efficiently add a diluent to a carbonized sludge slurry by effectively utilizing water resources without increasing production costs. [Means for solving the problem]

[0006] The characteristic configuration of the diluent addition system of the present invention is that it is a diluent addition system that adds a diluent to a carbonized sludge slurry in an organic waste treatment system that includes a pretreatment device that performs pretreatment of organic waste, a hydrothermal carbonization device that performs hydrothermal carbonization of the treated material obtained by the pretreatment, and a solid-liquid separator that performs solid-liquid separation of the carbonized sludge slurry obtained by the hydrothermal carbonization, and the diluent is a separated liquid generated in the organic waste treatment system.

[0007] Carbonized sludge slurry obtained by hydrothermal carbonization of organic waste contains inorganic ions, such as anions like chloride ions and cations like calcium ions and sodium ions. When carbonized sludge slurry containing such components flows through the piping in the treatment system, clogging or corrosion of the piping may occur due to precipitation of scale, etc. In addition, if these components are contained in the biomass fuel, which is the final product obtained by treating the organic waste, the quality of the fuel may be affected. Therefore, by adding a diluent to the carbonized sludge slurry to dissolve more inorganic ions in water, more of these inorganic ions can be removed from the solid matter in the carbonized sludge slurry when the carbonized sludge slurry is subjected to solid-liquid separation, so that it is possible to suppress precipitation of scale, etc. and stabilize the fuel quality. In particular, in this configuration, by using the separated liquid generated in the organic waste treatment system as the diluent, the amount of water used in the entire organic waste treatment system can be reduced, and water resources can be used appropriately, which makes it possible to reduce the treatment cost.

[0008] A further characteristic configuration of the present invention is that the pretreatment device is a pretreatment solid-liquid separator that performs solid-liquid separation of the organic waste, and the dilution liquid is a dehydrated filtrate separated from the organic waste by the pretreatment solid-liquid separator.

[0009] Conventionally, such dewatered filtrate has been discharged from the treatment system after being subjected to appropriate treatment. Therefore, if the dewatered filtrate is reused as a diluent for the carbonized sludge slurry, it is possible to reduce the amount of water used in the entire treatment system and make appropriate use of water resources.

[0010] A further characteristic configuration of the present invention is that the dilution liquid is a hydrothermal carbonization dewatering filtrate separated from the carbonized sludge slurry by the solid-liquid separator.

[0011] In this configuration, the hydrothermal carbonization dewatering filtrate separated from the carbonized sludge slurry in the solid-liquid separator is used as the diluent, which reduces the amount of water used in the entire treatment system and makes it possible to properly use water resources.

[0012] A further characteristic feature of the present invention is that the dehydration filtrate is treated with a dehydration separated liquid treatment device, and treated water obtained by treating the dehydration filtrate in the dehydration separated liquid treatment device is used as the dilution liquid.

[0013] Conventionally, the dehydrated filtrate was discharged from the treatment system after being treated in the dehydration separated liquid treatment device. In this configuration, the treated water from the dehydration separated liquid treatment device is not discharged from the system, but is used as a diluent. This makes it possible to reuse the water in the treatment system, thereby reducing the amount of water used.

[0014] A further characteristic configuration of the present invention is that the hydrothermal carbonization apparatus has a cooling heat exchanger that cools the carbonized sludge slurry, and the cooling water after heat exchange circulating through the cooling heat exchanger is used as the diluting liquid.

[0015] Since the carbonized sludge slurry immediately after the hydrothermal carbonization process is at a high temperature of about 100°C to 150°C, it is necessary to cool the carbonized sludge slurry in a cooling heat exchanger to meet the heat resistance temperature of the solid-liquid separator. When the cooling water used in the cooling heat exchanger is not circulated, it can be effectively utilized by using the discharged cooling water as a diluent. In addition, the temperature of the carbonized sludge slurry can be lowered by adding a diluent before cooling the carbonized sludge slurry in the cooling heat exchanger, so that the load on the cooling heat exchanger can be reduced.

[0016] A further characteristic configuration of the present invention is that the apparatus further includes, between the hydrothermal carbonization apparatus and the solid-liquid separator, a measuring device for measuring the concentration of inorganic ions contained in the carbonized sludge slurry, an addition amount adjustment mechanism for adjusting the amount of the dilution liquid added, and a control device for controlling the addition amount adjustment mechanism in accordance with the concentration measured by the measuring device.

[0017] By measuring the concentration of inorganic ions such as chloride ions and sodium ions contained in the carbonized sludge slurry and adjusting the amount of diluent added according to the concentration, it is possible to properly use the separated liquid generated in the organic waste treatment system and reduce the power consumption of related equipment. By temporarily storing the separated liquid that is not used as a diluent in a tank or the like and adding it when necessary, it is possible to effectively use the separated liquid generated in the organic waste treatment system without discharging it outside the system. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a diluent addition system 100 according to a first embodiment. [Diagram 2] FIG. 1 is a schematic diagram of a diluent addition system 100 according to a second embodiment. [Diagram 3] FIG. 11 is a schematic diagram of a diluent adding system 100 according to a third embodiment. [Figure 4] FIG. 11 is a schematic diagram of a diluent adding system 100 according to a fourth embodiment. [Diagram 5] FIG. 11 is a schematic diagram of a diluent adding system 100 according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the diluent addition system according to the present invention will be described with reference to the drawings. In this embodiment, as an example of the diluent addition system, a diluent addition system in an organic waste treatment system having a fermenter and a hydrothermal carbonization device will be described. However, the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the gist of the present invention.

[0020] [First embodiment] FIG. 1 is a schematic diagram of a diluent addition system 100 according to the first embodiment. The diluent addition system 100 includes a pretreatment solid-liquid separator 2 (an example of a pretreatment device), a hydrothermal carbonization device 3, and a solid-liquid separator 4. These constitute an organic waste treatment system. The organic waste to be treated in this system includes sewage sludge, human waste sludge, agricultural village wastewater sludge, septic tank sludge, food waste such as food waste, lignocellulosic waste such as used paper and waste paper, agricultural residues, livestock manure, etc. These organic wastes may be treated alone or in combination. In the following description, organic waste will be simply referred to as sludge, and the organic waste treatment system will be simply referred to as the treatment system.

[0021] A fermenter 1 may be provided before the treatment system in this embodiment. The fermenter 1 receives sludge and performs anaerobic fermentation treatment. The sludge fed into the fermenter 1 has a solid concentration of, for example, 3.0% by weight or more and 10.0% by weight or less. The fermenter 1 can perform mesophilic fermentation treatment or high-temperature fermentation treatment. In the mesophilic fermentation treatment, the fermenter is operated at a temperature of, for example, about 30 to 42°C with a residence time of about 15 to 30 days. In the high-temperature fermentation treatment, the fermenter is operated at a temperature of, for example, about 50 to 60°C with a residence time of about 7 to 20 days.

[0022] In the fermenter 1, digestion gas is generated by anaerobic fermentation of the sludge. The digestion gas is a gas (biogas) containing approximately 60% by volume of methane and approximately 40% by volume of carbon dioxide. The generated digestion gas is extracted from the fermenter 1 and used as fuel for heating the fermenter 1, etc. In other words, the energy contained in the sludge is recovered as digestion gas (gas energy) by a heating treatment facility not shown. The fermentation residue of the sludge after the anaerobic fermentation treatment in the fermenter 1, i.e., the digested sludge, is transferred to a pretreatment solid-liquid separator 2 described later.

[0023] The pretreatment solid-liquid separator 2 separates the solids containing water into solids and liquids. In this embodiment, the solids containing water correspond to the digested sludge transferred from the fermenter 1. The pretreatment solid-liquid separator 2 dehydrates the digested sludge transferred from the fermenter 1. The solid concentration of the digested sludge is, for example, 1.5 to 5% by mass. The pretreatment solid-liquid separator 2 can be, for example, any of a belt press dehydrator, a centrifugal dehydrator, a screw press dehydrator, a filter press dehydrator, a belt concentrator, and a centrifugal concentrator. Of course, it is also possible to configure the pretreatment solid-liquid separator using other solid-liquid separators. In this configuration, it is preferable to use a screw press dehydrator. Since the screw press dehydrator has a relatively high solid recovery rate, the dehydrated filtrate is relatively clean and is more suitable as a dilution liquid.

[0024] The digested sludge that has been subjected to solid-liquid separation (dewatered) in the pretreatment solid-liquid separator 2 becomes dewatered sludge with a moisture content of, for example, about 80% by mass. The dewatered sludge is transferred to a hydrothermal carbonization apparatus 3, which will be described later.

[0025] When digested sludge is dehydrated in the pretreatment solid-liquid separator 2, a dehydrated filtrate is produced together with the dehydrated sludge. Since the digested sludge is weakly alkaline, the dehydrated filtrate is also weakly alkaline. The pipe 20 transfers the dehydrated filtrate discharged from the pretreatment solid-liquid separator 2 to the carbonized sludge slurry described below as a diluent. The entire amount of the dehydrated filtrate may be added to the carbonized sludge slurry, or only a portion of it may be added.

[0026] The hydrothermal carbonization apparatus 3 heats the solid matter whose moisture content has been reduced by the pretreatment solid-liquid separator 2. The solid matter whose moisture content has been reduced by the pretreatment solid-liquid separator 2 corresponds to the dehydrated sludge that has been dehydrated in the pretreatment solid-liquid separator 2. In this embodiment, the hydrothermal carbonization apparatus 3 performs hydrothermal carbonization of the dehydrated sludge transferred from the pretreatment solid-liquid separator 2. The hydrothermal carbonization refers to carbonizing the dehydrated sludge or the like by performing high-temperature, high-pressure treatment in an atmosphere of gas containing no oxygen, in an atmosphere of gas with a low oxygen concentration, or in a state where oxygen is blocked.

[0027] In the hydrothermal carbonization apparatus 3, first, the dewatered sludge (for example, with a moisture content of about 80% by mass) transferred from the pretreatment solid-liquid separator 2 is preheated. The preheated dewatered sludge is subjected to the above-mentioned high-temperature, high-pressure treatment. The high-temperature, high-pressure treatment at this time is performed in a gas atmosphere with an oxygen concentration of 5% by volume or less, for example. This high-temperature, high-pressure treatment is performed in a reactor (not shown) possessed by the hydrothermal carbonization apparatus 3, and the oxygen concentration inside the reactor is maintained at approximately 0% by volume during this treatment. In the reactor, the carbonized sludge (carbonized sludge slurry) and the dewatered sludge supplied to the reactor are mixed and stirred.

[0028] The reactor is covered with a jacket (not shown), and a heat transfer medium (e.g., heat transfer oil) flows through this jacket. As a result, the carbonized sludge slurry in the reactor is heated by the heat transfer medium, for example, to 200°C. The temperature of the carbonized sludge slurry in the reactor is not limited to 200°C, and may be any temperature within the range of, for example, 160°C to 250°C. The pressure in the reactor is any pressure within the range of about 0.6 MPa to 3 MPa gauge pressure. Therefore, in the hydrothermal carbonization device 3, high-temperature, high-pressure treatment is performed in a state where the temperature of the dewatered sludge is 160°C or higher and 250°C or lower, and the pressure in the reactor is 0.6 MPa or higher and 3 MPa gauge pressure or lower.

[0029] The dewatered sludge supplied to the reactor is treated at the above pressure and temperature to become a carbonized sludge slurry. By the hydrothermal carbonization treatment, inorganic ions such as chloride ions, sodium ions, potassium ions, calcium ions, magnesium ions, sulfide ions, and phosphate ions are dissolved from the solid matter of the carbonized sludge slurry into water. If the carbonized sludge slurry containing these components flows through the piping in the diluent addition system 100, clogging and corrosion of the piping may occur due to the generation of scale. In addition, if these components are contained in the fuel obtained by treating the sludge, the quality of the fuel may be affected. Therefore, in this configuration, in order to dissolve these components in water and remove them from the solid matter in the carbonized sludge slurry, the carbonized sludge slurry is washed by adding a diluent.

[0030] The dilution liquid added to the carbonized sludge slurry is preferably the dehydrated filtrate obtained by solid-liquid separation in the pretreatment solid-liquid separator 2. The dehydrated filtrate is added to the carbonized sludge slurry as the dilution liquid through the pipe 20. This allows components such as chloride ions to be dissolved in water, so that these can be removed from the solid matter in the carbonized sludge slurry. In addition, since the carbonized sludge slurry obtained by the hydrothermal carbonization treatment may exhibit weak acidity, in this embodiment, the carbonized sludge slurry can be neutralized by adding the dehydrated filtrate, which is weakly alkaline, to the carbonized sludge slurry, and the occurrence of corrosion in the downstream pipes and equipment can be suppressed. Furthermore, since the dehydrated filtrate was conventionally discharged outside the treatment system, by using it as the dilution liquid, it is not necessary to introduce water from the outside, so that the amount of water used in the entire treatment system can be reduced. In addition, if the pretreatment solid-liquid separator 2 is a screw press dehydrator, the dehydrated filtrate is relatively clean, so it is more suitable for diluting the carbonized sludge slurry.

[0031] The amount of dilution liquid added to the carbonized sludge slurry is preferably about 2 to 10 times the amount of the carbonized sludge slurry. Since the more dilution liquid added, the longer the time required for washing, the amount of dilution liquid added and the washing time should be appropriately set according to the amount of carbonized sludge slurry to be treated. The solid matter concentration of the carbonized sludge slurry before dilution is, for example, about 10 to 20 mass%, and the solid matter concentration of the carbonized sludge slurry becomes, for example, 1.5 to 5 mass% by adding the dilution liquid.

[0032] The temperature of the carbonized sludge slurry immediately after being discharged from the hydrothermal carbonization apparatus 3 is 100°C to 150°C. The carbonized sludge slurry is adjusted to a temperature suitable for handling (for example, 60°C or lower) by being cooled in a cooling heat exchanger (not shown). In this embodiment, the temperature of the carbonized sludge slurry can be lowered by adding a dewatered filtrate (for example, 40°C) that is at a lower temperature than the carbonized sludge slurry, so that a cooling heat exchanger is not required or the load on the cooling heat exchanger can be reduced. Therefore, it is possible to efficiently configure a treatment system.

[0033] The solid-liquid separator 4 separates the solid matter containing water into solid and liquid. In this embodiment, the solid matter containing water corresponds to the carbonized sludge slurry transferred from the hydrothermal carbonization device 3. The solid-liquid separator 4 dewaters the carbonized sludge slurry to which the dewatered filtrate is added as a diluting liquid. The solid concentration of the carbonized sludge slurry after dilution is, for example, 1.5 to 5 mass%. The solid-liquid separator 4 is not particularly limited, but is preferably a filter press dewatering machine. The carbonized sludge slurry is in a state in which carbonized material that has become fine particles is dispersed in water. Therefore, a filter press dewatering machine with fine filter openings and a high solid recovery rate even when compressed at high pressure is suitable as the solid-liquid separator 4. Of course, it is also possible to configure the solid-liquid separator using other solid-liquid separators, for example, a centrifugal dewatering machine or a screw press dewatering machine can be used.

[0034] The carbonized sludge slurry that has been subjected to solid-liquid separation (dewatered) in the solid-liquid separator 4 becomes carbonized sludge with a moisture content of, for example, 35 mass % or less.

[0035] Carbonized sludge has highly active surface functional groups on its particle surface, and is known to have self-heating properties if left as is. Therefore, the carbonized sludge is placed in a curing vessel (not shown) and is subjected to low-temperature oxidation treatment of the particle surface by contacting with oxygen-containing gas such as air blown into the vessel. This makes it possible to obtain biomass fuels and the like with reduced heat generation and ignition properties of the carbonized sludge.

[0036] By configuring the diluent addition system 100 as described above, it becomes possible to dilute the carbonized sludge slurry with the dewatered filtrate obtained by solid-liquid separation in the pretreatment solid-liquid separator 2. Therefore, components such as chlorine and sodium contained in the carbonized sludge slurry can be dissolved in water and removed. In addition, by using the separated liquid generated in the treatment system as the diluent, there is no need to introduce water from the outside, so it is possible to reduce the amount of water used in the entire treatment system and make effective use of water resources.

[0037] Second Embodiment Next, a diluent addition system 100 according to a second embodiment will be described with reference to FIG. 2. In this embodiment, the diluent addition system 100 adds the hydrothermal carbonization dehydration filtrate, which has been subjected to solid-liquid separation in the solid-liquid separator 4, to the carbonized sludge slurry via a pipe 40. The entire amount of the hydrothermal carbonization dehydration filtrate may be added to the carbonized sludge slurry, or only a portion of it may be added. The other configurations are the same as those in the first embodiment, and therefore detailed descriptions of the same configurations as those in the first embodiment will be omitted.

[0038] When the carbonized sludge slurry is dehydrated in the solid-liquid separator 4, a separated liquid (hydrothermal carbonization dehydration filtrate) is generated together with the carbonized sludge. By using this separated liquid as a diluent, it is not necessary to introduce water from the outside, so it is possible to reduce the amount of water used in the entire treatment system and make effective use of water resources.

[0039] It is preferable to use a filter press dehydrator as the solid-liquid separator 4. The filter press dehydrator is a device that is washed in a batch manner after removing the carbonized sludge that has been separated into solid and liquid. Therefore, the hydrothermal carbonization dehydration filtrate that has been separated into solid and liquid in the solid-liquid separator 4 may be temporarily stored in a tank or the like and added to the carbonized sludge slurry from the tank or the like as necessary.

[0040] Third Embodiment Next, a diluent addition system 100 according to a third embodiment will be described with reference to FIG. 3. In this embodiment, the diluent addition system 100 has a dehydrated separated liquid treatment device 6 that performs, for example, coagulation and precipitation treatment on the dehydrated filtrate obtained by solid-liquid separation in the pretreatment solid-liquid separator 2. The dehydrated filtrate treated in the dehydrated separated liquid treatment device 6 is added to the carbonized sludge slurry as treated water through a pipe 60. The treated water obtained by treating the dehydrated filtrate in the dehydrated separated liquid treatment device 6 may be added in its entirety to the carbonized sludge slurry, or only a portion of it may be added. Since the other configurations are the same as those in the first embodiment, detailed description of the same configurations as those in the first embodiment will be omitted.

[0041] The dehydrated separated liquid treatment device 6 preferably performs an acidic coagulation precipitation treatment. In the acidic coagulation precipitation treatment, the pH of the water to be treated is adjusted as necessary, and then an iron-based inorganic coagulant is injected to perform coagulation precipitation treatment under acidic conditions. The acidic precipitation treatment causes the pollutants contained in the dehydrated filtrate to be coagulated and precipitated, phosphorus and heavy metals are removed, and the increase in the COD (chemical oxygen demand) of the treated water is also suppressed. As a result, the water quality of the dehydrated filtrate can be improved. As the iron-based inorganic coagulant, inorganic coagulants such as polyferric sulfate, ferric chloride, and ferrous sulfate can be used. In addition, the precipitate (settled sludge) produced by the coagulation precipitation treatment may be mixed with the carbonized sludge slurry. This reduces the amount of the settled sludge to be treated and allows it to be effectively used as carbonized sludge (fuel). The treatment of the dehydrated filtrate is not limited to the coagulation precipitation treatment, and may be a coagulation flotation separation treatment or a coagulation filtration treatment.

[0042] Conventionally, treated water that has been subjected to acidic coagulation and sedimentation treatment has been discharged outside the treatment system, where it has been further purified or released into the hydrosphere, such as rivers, oceans, etc. In this embodiment, the treated water is used as a diluting liquid without being discharged outside the system, so there is no need to introduce water from outside, and it is possible to reduce the amount of water used in the entire treatment system and make effective use of water resources.

[0043] As described above, it is preferable that the pretreatment solid-liquid separator 2 is a screw press dehydrator. Since the screw press dehydrator has a relatively high solid recovery rate, the dehydrated filtrate is relatively clean and more suitable as a dilution liquid.

[0044] The temperature of the treated water is, for example, 40°C, which is lower than the temperature (100°C to 150°C) of the carbonized sludge slurry immediately after it is discharged from the hydrothermal carbonization apparatus 3. Therefore, by adding treated water to the carbonized sludge slurry, the temperature of the carbonized sludge slurry can be lowered, so that the flow rate of the refrigerant in the cooling heat exchanger for cooling the carbonized sludge slurry can be reduced or the cooling heat exchanger can be made unnecessary. Therefore, it is possible to configure an efficient treatment system.

[0045] [Fourth embodiment] Next, a diluent addition system 100 according to a fourth embodiment will be described with reference to Fig. 4. In this embodiment, the diluent addition system 100 has a cooling heat exchanger 5 that cools the carbonized sludge slurry that has been subjected to high temperature and high pressure treatment in the hydrothermal carbonization device 3. Cooling water flowing through the cooling heat exchanger 5 is added to the carbonized sludge slurry via a pipe 50. The other configurations are the same as those in the first embodiment, so detailed descriptions of the same configurations as those in the first embodiment will be omitted.

[0046] The temperature of the carbonized sludge slurry immediately after being discharged from the hydrothermal carbonization apparatus 3 is 100°C to 150°C. In the cooling heat exchanger 5, heat exchange is carried out between the cooling water flowing through the cooling heat exchanger 5 and the carbonized sludge slurry, thereby adjusting the temperature of the carbonized sludge slurry to a temperature suitable for handling (for example, 60°C or lower). The temperature of the cooling water may be lower than the temperature of the carbonized sludge slurry, and is, for example, 20°C to 40°C.

[0047] In this embodiment, the cooling water flowing through the cooling heat exchanger 5 is added to the carbonized sludge slurry before heat exchange in the cooling heat exchanger 5. As described above, the temperature of the cooling water is lower than that of the carbonized sludge slurry, so the temperature of the carbonized sludge slurry is lowered by adding the cooling water to the carbonized sludge slurry as a diluting liquid. Therefore, the load on the cooling heat exchanger 5 can be reduced. In addition, since there is no need to introduce water from outside, it is possible to reduce the amount of water used in the entire treatment system. In particular, when the cooling water flowing through the cooling heat exchanger 5 is not circulated, the amount of water used can be significantly reduced.

[0048] Fifth embodiment Next, a diluent adding system 100 according to a fifth embodiment will be described with reference to Fig. 5. In this embodiment, the diluent adding system 100 includes a pipe 20, a pipe 21, a pipe 60, a pipe 40, a pipe 41, a measuring device 12, and a control device 13. Since the other configurations are the same as those of the first to third embodiments, detailed descriptions of the same configurations as those of the first to third embodiments will be omitted.

[0049] The pipe 20 is a pipe for supplying the dehydrated filtrate obtained by solid-liquid separation in the pretreatment solid-liquid separator 2 to the carbonized sludge slurry, and includes a first pump 8 for pressurizing the dehydrated filtrate and a first switching valve 10. The pipe 21 branches off from the pipe 20 downstream of the first pump 8 and supplies the dehydrated filtrate to the dehydrated separated liquid treatment device 6. The dehydrated filtrate treated in the dehydrated separated liquid treatment device 6 becomes treated water, and is added to the carbonized sludge slurry through the pipe 60. The first switching valve 10 is, for example, a three-way valve, and the flow path of the dehydrated filtrate can be switched by operating it. The pipe 21 may not branch off from the pipe 20 and may connect the pretreatment solid-liquid separator 2 and the dehydrated separated liquid treatment device 6, and each of the pipes 20 and 21 may be provided with a pump and a flow control valve.

[0050] By operating the first switching valve 10, the dehydrated filtrate can be switched between a first state in which it is added to the carbonized sludge slurry through piping 20, and a second state in which it is treated in the dehydrated separated liquid treatment device 6 to become treated water and added to the carbonized sludge slurry. This allows the dehydrated separated liquid treatment device 6 to be operated efficiently, and also allows the dehydrated filtrate obtained through solid-liquid separation in the pretreatment solid-liquid separator 2 to be used as a diluent for the carbonized sludge slurry, making it possible to reduce the amount of water used in the entire treatment system.

[0051] The hydrothermal carbonization dehydration filtrate separated into solid and liquid in the solid-liquid separator 4 is added to the carbonized sludge slurry through the pipe 40. The pipe 40 has a second pump 9 for pressurizing the hydrothermal carbonization dehydration filtrate and a second switching valve 11. The pipe 41 branches off from the pipe 40 downstream of the second pump 9 and is a pipe for supplying the hydrothermal carbonization dehydration filtrate to the fermenter 1. The second switching valve 11 is a three-way valve like the first switching valve 10, and the flow path of the hydrothermal carbonization dehydration filtrate can be switched by operating it. The pipe 41 may not branch off from the pipe 40 and may connect the solid-liquid separator 4 and the fermenter 1, and each of the pipes 40 and 41 may be provided with a pump and a flow control valve.

[0052] By operating the second switching valve 11, the hydrothermal carbonization dehydration filtrate is switched between a third state in which it is added to the carbonized sludge slurry through the pipe 40 and a fourth state in which it is supplied to the fermenter 1 through the pipe 41. When the amount of dehydrated filtrate required for washing the carbonized sludge slurry is insufficient, the third state allows the hydrothermal carbonization dehydration filtrate to be added to the carbonized sludge slurry, so the amount of dilution liquid can be increased. On the other hand, if the amount of dehydrated filtrate required for washing the carbonized sludge slurry is sufficient, there is no need to add the hydrothermal carbonization dehydration filtrate to the carbonized sludge slurry, so the fourth state allows the hydrothermal carbonization dehydration filtrate to be returned to the fermenter 1. Since the hydrothermal carbonization dehydration filtrate has a low pH, the pH of the digested sludge can be lowered by returning it to the fermenter 1. This allows the pH of the dehydrated filtrate separated into solid and liquid in the pretreatment solid-liquid separator 2 to be lowered, so it is possible to reduce the amount of acid added in the dehydrated separated liquid treatment device 6. In addition, since the hydrothermal carbonization dehydration filtrate contains organic matter generated by the hydrothermal carbonization process, by adding the hydrothermal carbonization dehydration filtrate to the fermenter 1, the amount of digester gas generated can be increased, making it possible to increase the amount of energy recovered.

[0053] The measuring device 12 measures the concentration of inorganic ions contained in the carbonized sludge slurry upstream of the addition section where the diluent is added to the carbonized sludge slurry. The inorganic ions are chloride ions, sodium ions, potassium ions, sulfide ions, phosphate ions, etc. The measuring device 12 can be a known measuring device, and for example, ion chromatography, silver nitrate titration (Mohr method), or absorptiometry can be used. The control device 13 adjusts the amount of diluent added based on the information measured by the measuring device 12. Specifically, when increasing the amount of diluent added, the rotation speed of the first pump 8 or the second pump 9 is increased to increase the flow rate of the dehydrated filtrate, treated water, or hydrothermal carbonization dehydrated filtrate. Note that a tank for temporarily storing the dehydrated filtrate, treated water, or hydrothermal carbonization dehydrated filtrate may be provided in the diluent addition system 100, and the diluent stored in the tank may be adjusted to be added to the carbonized sludge slurry as necessary.

[0054] In this embodiment, the dewatered filtrate, treated water, or hydrothermal carbonization dewatered filtrate is added to the carbonized sludge slurry as a diluent, so that it is possible to reduce the amount of water used in the entire treatment system and to reduce power consumption. In addition, since the temperature of the carbonized sludge slurry is lowered by the addition of the diluent, there is no need to provide a cooling heat exchanger 5 between the hydrothermal carbonization device 3 and the solid-liquid separator 4. Therefore, it is possible to configure the diluent addition system 100 more efficiently. [Industrial Applicability]

[0055] INDUSTRIAL APPLICABILITY The present invention can be used in a diluent addition system in an organic waste treatment system. [Explanation of symbols]

[0056] 2: Pretreatment solid-liquid separator (pretreatment device) 3:Hydrothermal carbonization equipment 4:Solid-liquid separator 6: Dehydration and separated liquid treatment device 5: Cooling heat exchanger 12: Measuring equipment 13: Control device 100: Dilution liquid addition system

Claims

1. A diluent addition system for adding a diluent to the carbonized sludge slurry in an organic waste treatment system including a pretreatment device for performing pretreatment of organic waste, a hydrothermal carbonization device for performing hydrothermal carbonization of the treated material obtained by the pretreatment, and a solid-liquid separator for performing solid-liquid separation of the carbonized sludge slurry obtained by the hydrothermal carbonization, comprising: A diluent adding system, wherein the diluent is a separated liquid generated in the organic waste treatment system.

2. The pretreatment device has a pretreatment solid-liquid separator that performs solid-liquid separation of the organic waste, 2. The diluent adding system according to claim 1, wherein the diluent is a dehydrated filtrate separated from the organic waste by the pretreatment solid-liquid separator.

3. The diluent adding system according to claim 1 , wherein the diluent is a hydrothermal carbonization dewatering filtrate separated from the carbonized sludge slurry by the solid-liquid separator.

4. The pretreatment device has a pretreatment solid-liquid separator that performs solid-liquid separation of the organic waste, The organic waste treatment system further includes a dehydrated separated liquid treatment device that treats the dehydrated filtrate separated from the organic waste by the pretreatment solid-liquid separator, The diluent adding system according to claim 1 , wherein treated water obtained by treating the dehydrated filtrate in the dehydrated separated liquid treatment device is used as the diluent.

5. The hydrothermal carbonization apparatus has a cooling heat exchanger that cools the carbonized sludge slurry, The diluent supply system according to claim 1 , wherein the cooling water after heat exchange that flows through the cooling heat exchanger is used as the diluent.

6. a measuring device that measures the concentration of inorganic ions contained in the carbonized sludge slurry between the hydrothermal carbonization apparatus and the solid-liquid separator; An addition amount adjustment mechanism for adjusting the amount of the diluent added; The diluent addition system according to any one of claims 1 to 5, further comprising a control device that controls the addition amount adjustment mechanism in accordance with the concentration measured by the measurement device.

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