Waste treatment system and raw material supply equipment

Abstract

To provide a waste treatment system that improves the efficiency of processing organic waste. [Solution] The waste treatment system comprises a raw water storage tank in which a pump with a crushing mechanism is located inside, and a treatment tank located downstream of the raw water storage tank for decomposing organic waste contained in the raw water by microorganisms, wherein the raw water storage tank sends the raw water to the treatment tank via the pump with a crushing mechanism. The pump with a crushing mechanism may be located at the bottom of the raw water storage tank.

Description

[[Technical Field]]

[0001] An embodiment of the present invention relates to a waste treatment system and a raw material supply device. [[Background Art]]

[0002] Conventionally, waste treatment systems using microorganisms have been used as facilities for treating organic waste such as kitchen garbage. In particular, in recent years, development of biogas production systems for utilizing organic waste as an energy resource has been progressing. As a biogas production system, for example, a methane fermentation system for producing methane gas from organic waste is known. The methane fermentation system is a system that produces methane gas by fermenting organic waste using anaerobic microorganisms. Patent Document 1 discloses a technique in which a grinder (crushing device) for finely crushing a material to be crushed is provided upstream of a methane fermentation tank, and the organic waste finely crushed by the grinder is charged into the methane fermentation tank, thereby increasing the fermentation rate in the fermentation process. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Patent Application Laid-Open No. 2022-164226 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] In the above-mentioned conventional technology, in order to finely crush the carried-in organic waste, a grinder such as a wet bead mill needs to be arranged between a raw material storage tank that stores raw materials (such as slurry obtained by mixing organic waste and water) and a methane fermentation tank. This not only lengthens the waste treatment process, but also causes the problem that the equipment cost and operating cost of the waste treatment system increase.

[0005] One of the objectives of the present invention is to provide a waste treatment system that improves the efficiency of treating organic waste.

[0006] Another objective of the present invention is to provide a raw material supply device capable of supplying raw materials containing highly efficient organic waste. [Means for solving the problem]

[0007] A waste treatment system according to one embodiment of the present invention comprises a raw material supply device including a raw material storage tank in which a pump with a crushing mechanism is disposed inside, and a fermentation treatment device disposed downstream of the raw material supply device for decomposing organic waste contained in the raw material by the action of microorganisms, wherein the raw material supply device sends the raw material to the fermentation treatment device via the pump with a crushing mechanism.

[0008] In the waste treatment system described above, the pump with the crushing mechanism may be located at the bottom of the raw material storage tank.

[0009] In the waste treatment system described above, the raw material supply device may include a raw material delivery pipe connected to the pump with a crushing mechanism, a raw material supply pipe for transporting the raw material to the fermentation treatment device, a raw material return pipe for returning the raw material to the raw material storage tank, and three-way valves connected to the raw material delivery pipe, the raw material supply pipe, and the raw material return pipe, respectively.

[0010] In the waste treatment system described above, the three-way valve may be an automatically operated valve.

[0011] In the waste treatment system described above, the three-way valve may periodically switch between a first mode, which connects the raw material delivery pipe and the raw material supply pipe, and a second mode, which connects the raw material delivery pipe and the raw material return pipe. In this case, the period during which the three-way valve operates in the first mode may be shorter than the period during which the three-way valve operates in the second mode.

[0012] In the waste treatment system described above, the yeast treatment apparatus may be a methane fermentation treatment apparatus.

[0013] The raw material supply device according to one embodiment of the present invention includes a raw material storage tank, a pump with a crushing mechanism disposed inside the raw material storage tank, a raw material delivery pipe connected to the pump with the crushing mechanism, a raw material supply pipe for transporting raw materials to a fermentation treatment device that decomposes organic waste by the action of microorganisms, a raw material return pipe for returning the raw materials to the raw material storage tank, and three-way valves connected to the raw material delivery pipe, the raw material supply pipe, and the raw material return pipe, respectively. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing the configuration of a biogas production system according to one embodiment of the present invention. [Figure 2] This is a schematic diagram showing the configuration of a raw material supply device in a biogas production system according to one embodiment of the present invention. [Figure 3] This is a schematic diagram showing the configuration of a biogas production system according to one embodiment of the present invention. [Modes for carrying out the invention]

[0015] Hereinafter, one embodiment of the present invention will be described with reference to the drawings, etc. However, the present invention can be implemented in various forms without departing from its gist, and is not to be interpreted as being limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same function as those described with respect to previously shown drawings are denoted by the same reference numerals, and redundant explanations may be omitted.

[0016] In this specification, "biogas" refers to gas obtained by decomposing organic matter using microorganisms. Examples of biogas include gases that can be used as energy resources, such as methane and hydrogen.

[0017] In this specification and in the drawings, "down" refers to the direction of gravity (vertical direction), and "up" refers to the direction opposite to the direction of gravity. Also, "left" and "right" refer to directions perpendicular to "up" and "down."

[0018] <First Embodiment> A waste treatment system according to one embodiment of the present invention will be described using a biogas generation system as an example. The biogas generation system 100 of this embodiment is a system that decomposes organic waste such as food waste by the action of microorganisms to produce biogas such as methane gas and hydrogen. However, the waste treatment system according to one embodiment of the present invention is not limited to a biogas generation system, and may be other fermentation treatment systems that decompose organic waste by the action of microorganisms.

[0019] Figure 1 shows the configuration of a biogas production system 100 according to one embodiment of the present invention. The biogas production system 100 of this embodiment includes at least a raw material supply device 110 and a fermentation treatment device 120. In addition, the biogas production system 100 of this embodiment includes a water seal trap 130 and a washing trap 140 as biogas pretreatment equipment. The biogas produced by the biogas production system 100 is stored in a gas holder 150. The biogas stored in the gas holder 150 is used as fuel for hot water boilers, micro gas turbines, gas engines, etc. However, the example shown in Figure 1 is just one example and is not limited to this example.

[0020] The raw material supply device 110 is a device that supplies organic waste, which is a raw material for producing biogas, to a fermentation treatment device 120 arranged at a subsequent stage. Specifically, the raw material supply device 110 includes the slurry 10 stored inside a raw material storage tank 111. The slurry 10 is a mixture obtained by crushing organic waste such as food waste discharged from food factories and the like and then mixing the crushed waste with water, and is also called sludge. The raw material supply device 110 of the present embodiment is characterized by a mechanism for delivering the slurry 10, which is the raw material, to the fermentation treatment device 120. The specific configuration of the raw material supply device 110 will be described later.

[0021] The fermentation treatment device 120 is a treatment tank that decomposes organic waste using anaerobic microorganisms. Specifically, the fermentation treatment device 120 is a methane fermentation treatment device. The slurry 10 delivered from the raw material supply device 110 is supplied to the fermentation treatment device 120 arranged at the subsequent stage. In the fermentation treatment device 120, the organic waste contained in the slurry 10 is treated by anaerobic microorganisms and decomposed into methane gas, carbon dioxide, hydrogen, and the like. In the present embodiment, a UASB (Upflow Anaerobic Sludge Bed) type anaerobic treatment device is used as the fermentation treatment device 120, but anaerobic treatment devices of other types may also be used.

[0022] The fermentation treatment device 120 includes a biological sludge bed 121 in which anaerobic microorganisms having methane fermentation ability are granulated and held at high density. The granulated anaerobic microorganisms exist in the treatment tank as black granular bodies called granules, and the aggregate of granules functions as the biological sludge bed 121. In addition, although the present embodiment is described by exemplifying anaerobic microorganisms, it is also possible to use aerobic microorganisms.

[0023] The treated water discharged from the fermentation treatment device 120 is sent to a water-sealed trap 130. In the water-sealed trap 130, gas mixed into the treated water is removed.

[0024] The methane gas produced by the fermentation treatment apparatus 120 is sent to the washing trap 140. In the washing trap 140, slaked lime is used to convert carbon dioxide into calcium carbonate. As the ratio of carbon dioxide concentrations decreases, the relative concentration of methane gas increases, making it possible to obtain methane gas at a high concentration level comparable to city gas. For this reason, the washing trap 140 is also called a reforming device.

[0025] Finally, the high-concentration methane gas generated in the washing trap 140 is stored in the gas holder 150. The methane gas generated by the biogas generation system 100 of this embodiment has a concentration equivalent to that of city gas. Therefore, when using the methane gas generated by the biogas generation system 100, it is not necessary to use equipment specifically for biogas, and general city gas-compatible equipment can be used.

[0026] In this embodiment, a biogas generation system 100 for producing methane gas from organic waste has been illustrated, but this is merely one example. In other words, the biogas generation system 100 can be appropriately configured according to the type of biogas to be extracted from organic waste, as long as the basic structure of the fermentation treatment apparatus 120, which will be described later, remains unchanged. For example, in recent years, attempts have been made to generate hydrogen using residues such as pineapple peels. The biogas generation system 100 of this embodiment can also be used as a system to extract hydrogen as biogas from organic waste.

[0027] Next, we will describe in detail the raw material supply device 110, which functions as a source of raw materials in the biogas production system 100.

[0028] Figure 2 is a schematic diagram showing the configuration of a raw material supply device 110 in a biogas production system 100 according to one embodiment of the present invention. The raw material supply device 110 includes a raw material storage tank 111, a pump with a crushing mechanism 112, a raw material delivery pipe 113, a raw material supply pipe 114, a raw material return pipe 115, and a three-way valve 116. However, the raw material supply device 110 is not limited to the example shown in Figure 2 and may include other elements (components).

[0029] The raw material storage tank 111 is a tank for storing the slurry 10, which is the raw material. Such a tank is also called a slurry tank. In this embodiment, the raw material storage tank 111 is made of stainless steel, but a tank made of other materials may also be used.

[0030] The crushing mechanism pump 112 is a pump equipped with a crushing section at its suction port, including rotating blades and fixed blades, and is capable of finely crushing organic waste contained in the slurry 10 while simultaneously sucking up the slurry 10. For example, a grinder pump (registered trademark) can be used as the crushing mechanism pump 112. Typically, pumps placed in a raw material storage tank are of a type that allows as much of the organic waste contained in the slurry to pass through as intact as possible by creating a large space within the casing. However, in this embodiment, the crushing mechanism pump 112 is placed in order to further crush the organic waste contained in the slurry 10 into finer particles. As will be described later, the crushing mechanism pump 112 also plays a role in circulating the slurry 10 stored in the raw material storage tank 111, so it is preferable to place it at the bottom of the raw material storage tank 111 so that the entire inside of the raw material storage tank 111 can be circulated.

[0031] In the subsequent fermentation treatment apparatus 120, the time required for fermentation treatment of organic waste increases in proportion to the size of the organic waste being fermented. Generally, in order to shorten the time required for fermentation treatment, efforts are often made to increase the amount of microorganisms used in the fermentation treatment, and therefore, the raw material (slurry) stored in the raw material storage tank is usually sent out as is by a general pump. In contrast, the inventor focused on the mechanism by which microorganisms ingest organic matter and came up with the configuration of this embodiment. That is, microorganisms do not ingest organic matter as solid matter, but rather solubilize it first and then ingest it as a water-soluble substance. Therefore, if the substrate of the material to be fermented is the same, the smaller the size, the shorter the time required for fermentation treatment. In other words, the smaller the size of the organic waste contained in the raw material supplied to the fermentation treatment apparatus, the shorter the fermentation treatment time. For this reason, in this embodiment, a pump with a crushing mechanism 112 is used as the raw material delivery pump, and the organic waste contained in the slurry 10 is crushed in the grinder section and sent out.

[0032] In this embodiment, an example is shown in which a pump with a crushing mechanism 112 is used as the pump that pumps the raw material while crushing it. However, any pump that performs a similar function may be used, and other types of pumps may be used.

[0033] The raw material delivery pipe 113 has one end connected to a crushing pump 112 and is a pipe that delivers the slurry 10 sucked out from the crushing pump 112. The other end of the raw material delivery pipe 113 is connected to a three-way valve 116.

[0034] The raw material supply pipe 114 has one end connected to a three-way valve 116 and is a pipe that supplies slurry 10, which is drawn out from the crushing mechanism pump 112 and sent out via the raw material delivery pipe 113 and the three-way valve 116, to the fermentation processing device 120. The slurry 10 supplied to the fermentation processing device 120 is subjected to fermentation processing in the fermentation processing device 120.

[0035] The raw material return pipe 115 is connected at one end to a three-way valve 116 and is a pipe that returns the slurry 10, which is drawn out from the crushing mechanism pump 112 and sent out via the raw material delivery pipe 113 and the three-way valve 116, to the raw material storage tank 111. The slurry 10 returned to the raw material storage tank 111 is mixed again with the slurry 10 stored inside the raw material storage tank 111. In other words, the raw material supply device 110 of this embodiment has a circulation path that returns the slurry 10 sent out by the crushing mechanism pump 112 back to the raw material storage tank 111.

[0036] The three-way valve 116 is a valve equipped with three ports for connecting piping. As shown in Figure 2, the three-way valve 116 of this embodiment is equipped with a first port to which the raw material delivery pipe 113 is connected, a second port to which the raw material supply pipe 114 is connected, and a third port to which the raw material return pipe 115 is connected, with the raw material delivery pipe 113, raw material supply pipe 114, and raw material return pipe 115 connected to each port, respectively. The three-way valve 116 has a ball valve with an L-shaped flow path inside, which allows switching of the direction of fluid flow. The three-way valve 116 of this embodiment is an automatically operated valve that can be operated by electromagnetic control, but it is not limited to this example, and may also be a manually operated valve that can be operated manually.

[0037] The three-way valve 116 has a first mode that connects the raw material delivery pipe 113 and the raw material supply pipe 114 (i.e., a mode in which the first port and the second port are connected) and a second mode that connects the raw material delivery pipe 113 and the raw material return pipe 115 (i.e., a mode in which the first port and the third port are connected), and the first mode and the second mode are switched periodically. In other words, the raw material supply device 110 is configured to alternately repeat a first period in which the slurry 10 is supplied to the fermentation processing device 120 and a second period in which the slurry 10 is circulated within the raw material supply device 110.

[0038] Mode switching of the three-way valve 116 is performed by a control unit (not shown). Specifically, when it is time to supply slurry 10 to the fermentation processing device 120, it switches to the first mode, and when the timing for supplying slurry 10 to the fermentation processing device 120 ends, it switches to the second mode. Specifically, the period during which the three-way valve 116 operates in the first mode (first period) is shorter than the period during which the three-way valve 116 operates in the second mode (second period). For example, out of 60 minutes, the first period is between 5 and 30 minutes, and the second period is between 30 and 55 minutes. In other words, the raw material supply device 110 is configured such that the period during which slurry 10 circulates within the raw material supply device 110 (the period during which the three-way valve 116 operates in the second mode) is relatively longer, and the period during which slurry 10 is supplied to the fermentation processing device 120 (the period during which the three-way valve 116 operates in the first mode) is relatively shorter.

[0039] However, the switching between the first mode and the second mode is not limited to being performed regularly, but may also be performed irregularly. For example, when controlling the timing of supplying slurry 10 to the fermentation processing apparatus 120 according to the progress of the fermentation process, the slurry 10 may normally be circulated in the raw material supply device 110, and the three-way valve 116 may be switched to the first mode only when it is time to supply slurry 10.

[0040] As described above, in this embodiment, the raw material supply device 110 circulates the organic waste contained in the slurry 10 internally through the raw material return pipe 115 and is repeatedly crushed by the crushing mechanism pump 112, thereby obtaining a slurry 10 containing organic waste with very small particle size. As a result, when fermentation treatment is performed in the fermentation treatment device 120 located downstream, the time required for fermentation treatment by microorganisms can be shortened. In other words, according to this embodiment, it is possible to provide a raw material supply device that can supply raw materials containing organic waste with high processing efficiency.

[0041] Furthermore, as described above, the raw material supply device 110 of this embodiment generates internal circulation of the slurry 10, so the slurry 10 stored inside the raw material storage tank 111 is constantly circulating. In other words, the slurry 10 does not accumulate inside the raw material storage tank 111 (especially in the corners), thus preventing the formation of scum. In addition, the operation of the crushing mechanism pump 112 inside the raw material storage tank 111 generates heat, which heats the slurry 10. When the slurry 10 is heated, it can be supplied to the fermentation processing device 120 located downstream at an appropriate temperature, thereby improving the efficiency of the fermentation process.

[0042] Therefore, by incorporating the raw material supply device 110 of this embodiment into a waste treatment system, it is possible to provide a waste treatment system (in this embodiment, a biogas generation system 100) that improves the efficiency of processing organic waste.

[0043] <Second Embodiment> In the example shown in the first embodiment, the fermentation processing apparatus 120 is directly connected downstream of the raw material supply device 110. However, the example is not limited to this, and other equipment may be placed between the raw material supply device 110 and the fermentation processing apparatus 120. That is, in this specification, "placed downstream of the raw material supply device" includes being placed directly or indirectly downstream of the raw material supply device.

[0044] Figure 3 is a schematic diagram showing the configuration of a biogas production system 100a according to one embodiment of the present invention. The biogas production system 100a shown in Figure 3 corresponds to the biogas production system 100 shown in Figure 1, with the addition of a heating device 210, a solubilizing device 220, and a pH adjustment tank 230. In Figure 3, elements that are the same as those shown in Figure 1 are denoted by the same reference numerals and detailed explanations are omitted.

[0045] In Figure 3, the heating device 210 is a device that processes the raw material (slurry 10) supplied from the raw material supply device 110 by heating it. The raw material is heated using a heating means (not shown), such as a coil heater installed inside the device. In the heating device 210, the raw material is heated to a temperature of 55°C to 90°C (preferably 65°C to 70°C), and finally cooled to 50°C or below (preferably 45°C or below) before being sent out of the device. The processing by the heating device 210 is intended to maintain the temperature inside the tank of the solubilization device 220 connected downstream at 40°C to 50°C, as well as to decompose organic matter contained in the raw material, particularly proteins.

[0046] As described above, in this embodiment, the raw material supply device 110 heats the raw material (slurry 10) stored inside the raw material storage tank 111 due to the self-heating caused by the operation of the crushing mechanism pump 112. Therefore, in this embodiment, the raw material supply device 110 can also function as a heating device, in which case the heating device 210 described above can be omitted.

[0047] The solubilization device 220 is a device that processes high-molecular-weight organic substances contained in the raw material by converting them into low-molecular-weight organic substances using microorganisms (solubilizing bacteria). The raw material, which is sent from the heating device 210 at around 45 degrees Celsius, is supplied directly to the solubilization device 220. In the solubilization device 220, high-molecular-weight organic substances are processed by microorganisms and converted into lower organic acids such as acetic acid. For this reason, the solubilization device 220 is also called an acid production device. In particular, in the example shown in Figure 3, the particle size of the organic waste in the raw material supplied from the raw material supply device 110 is sufficiently small, so the processing efficiency of the solubilization process by microorganisms inside the solubilization device 220 can be improved.

[0048] Furthermore, the raw materials processed in the solubilizer 220 are maintained at a temperature of 40 to 50 degrees Celsius inside the processing tank. In the example shown in Figure 3, the raw materials heated in the heating device 210 are ultimately supplied to the subsequent solubilizer 220 at a temperature of 50 degrees Celsius or lower, so the raw materials in the solubilizer 220 are maintained at a temperature of 40 to 50 degrees Celsius. In addition, the heating treatment in the heating device 210 decomposes organic substances such as proteins in the raw materials, which can increase the efficiency of the solubilization treatment (low molecular weight treatment) of high molecular weight organic substances in the solubilizer 220. Moreover, by decomposing proteins and other substances in the heating device 210 beforehand, effects such as a reduction in residue when organic substances are solubilized in the solubilizer 220 can be obtained.

[0049] Although not shown in the diagram, the solubilization device 220 may be equipped with a circulation pump for circulating the wastewater in the tank and a pH meter for measuring the pH value of the raw material. In other words, the solubilization device 220 may be configured to circulate the raw material in the tank using the circulation pump while simultaneously checking the change in the pH value of the raw material over time.

[0050] The pH adjustment tank 230 is a tank for adjusting the pH value of the raw material inside the solubilizer 220. Specifically, the pH adjustment tank 230 in this embodiment is a tank for storing an alkaline solution. As the alkaline solution, for example, sodium hydroxide can be used, but is not limited to this. As described above, the pH value of the solubilizer 220 is measured periodically. If it is determined that the inside of the solubilizer 220 has become acidic based on the measured pH value, an appropriate amount of alkaline solution is supplied to the solubilizer 220 from the pH adjustment tank 230. The amount of alkaline solution supplied is adjusted using a flow rate adjustment pump or the like (not shown).

[0051] As described above, in this embodiment, a heating device 210, a solubilizing device 220, and a pH adjusting tank 230 are arranged between the raw material supply device 110 and the fermentation processing device 120 as pre-treatment devices to modify the organic matter in the raw material supplied to the fermentation processing device 120 into a state that is easily processed by the fermentation processing device 120. However, this is not the only example, and any of the heating device 210, solubilizing device 220, and pH adjusting tank 230 may be omitted.

[0052] The embodiments of the present invention described above can be combined and implemented as appropriate, insofar as they do not contradict each other. Based on the embodiments described above, any additions, deletions, or design changes made by those skilled in the art, or additions, omissions, or changes in processes, are also included within the scope of the present invention, as long as they retain the essence of the invention.

[0053] Furthermore, any effects or benefits other than those brought about by the embodiments described above, if they are clear from the description herein or easily predictable to a person skilled in the art, are naturally considered to be brought about by the present invention. [Explanation of symbols]

[0054] 10...Slurry, 100, 100a...Biogas generation system, 110...Raw material supply device, 111...Raw material storage tank, 112...Pump with crushing mechanism, 113...Raw material delivery pipe, 114...Raw material supply pipe, 115...Raw material return pipe, 116...Three-way valve, 120...Fermentation treatment device, 121...Biological sludge bed, 130...Water seal trap, 140...Washing trap, 150...Gas holder, 210...Heating device, 220...Solubilization device, 230...pH adjustment tank

Claims

1. A raw material supply device including a raw material storage tank in which a pump with a crushing mechanism is located, A fermentation treatment device is located downstream of the raw material supply device and decomposes organic waste contained in the raw material by the action of microorganisms, Equipped with, The raw material supply device is a waste treatment system that sends the raw material to the fermentation treatment device via the pump with a crushing mechanism.

2. The waste treatment system according to claim 1, wherein the pump with the crushing mechanism is located at the bottom of the raw material storage tank.

3. The waste treatment system according to claim 1, wherein the raw material supply device includes a raw material delivery pipe connected to the pump with a crushing mechanism, a raw material supply pipe for transporting the raw material to the fermentation treatment device, a raw material return pipe for returning the raw material to the raw material storage tank, and three-way valves connected to the raw material delivery pipe, the raw material supply pipe, and the raw material return pipe, respectively.

4. The waste disposal system according to claim 3, wherein the three-way valve is an automatically operated valve.

5. The waste treatment system according to claim 3, wherein the three-way valve periodically switches between a first mode that connects the raw material delivery pipe and the raw material supply pipe and a second mode that connects the raw material delivery pipe and the raw material return pipe.

6. The waste treatment system according to claim 5, wherein the period during which the three-way valve operates in the first mode is shorter than the period during which the three-way valve operates in the second mode.

7. The waste treatment system according to any one of claims 1 to 6, wherein the fermentation treatment apparatus is a methane fermentation treatment apparatus.

8. Raw material storage tank, A pump with a crushing mechanism is placed inside the raw material storage tank, A raw material delivery pipe connected to the pump with the crushing mechanism, A raw material supply pipe that transports raw materials to a fermentation treatment device that decomposes organic waste by the action of microorganisms, A raw material return pipe for returning the raw material to the raw material storage tank, A three-way valve connected to each of the raw material delivery pipe, the raw material supply pipe, and the raw material return pipe, A raw material supply device, including a raw material supply device.

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