JP5230243B2 - Method and system for methane fermentation treatment of organic waste - Google Patents

Description

  The present invention relates to a method for methane fermentation treatment of organic waste and a system thereof, in which organic waste is subjected to methane fermentation treatment, and digested sludge generated by the methane fermentation treatment is sterilized to produce liquid fertilizer.

  2. Description of the Related Art Conventionally, as a method for treating organic waste, methane fermentation treatment that has a low environmental load and can recover energy and resources has been widely used. Biogas generated by methane fermentation treatment can be used as fuel, and digested sludge can be used as liquid manure or compost. When digested sludge is used as liquid manure, microorganisms such as methanogens remain in the digested sludge after the methane fermentation treatment, and thus it is necessary to sterilize the digested sludge so as not to inhibit the growth of the plant.

  A flow of a general methane fermentation treatment system is shown in FIG. Organic waste has a high solids concentration of tens of thousands to hundreds of thousands of mg / l and may contain a large amount of coarse solids. Therefore, pretreatment such as crushing and sorting was first performed in the pretreatment facility 51. Then, the dilution water is added in the adjustment tank 52 and the solubilization process is performed. In the adjustment tank 52, the organic matter in the waste is solubilized and hydrolyzed to reduce the molecular weight by heating. The adjustment tank 52 is provided with a stirring means. For example, as shown in the drawing, the liquid waste 61 partially extracted from the adjustment tank 52 is circulated by a circulation pump to stir the inside of the tank. The liquid waste 62 discharged from the adjustment tank 52 is methane-fermented in the methane fermentation tank 53 by the decomposition action of the methanogenic bacteria. The biogas generated by the methane fermentation process is effectively used in the gas utilization facility. On the other hand, the digested sludge 63 pulled out from the methane fermentation tank 53 is heated in the sterilization tank 54 and sterilized, and then fed to the liquid fertilizer storage facility 55 to be used as liquid fertilizer.

  As a method for producing liquid fertilizer from organic waste, Patent Document 1 (Japanese Patent Laid-Open No. 2006-256871) discloses a method of heating and sterilizing starch production wastewater, denaturing and precipitating soluble protein, A method for producing a liquid fertilizer by separating solids by separation, treating the separated liquid with anaerobic microorganisms, and the like is disclosed. Here, the heat sterilization is performed to sterilize pathogenic bacteria contained in the starch production waste water.

JP 2006-256871 A

As described above, in the methane fermentation treatment of organic waste, when the solid concentration of the organic waste carried in becomes higher than the assumed TS concentration, for example, 10 to 20%, solubilization in the adjustment tank As a result, the amount of fluid introduced into the methane fermenter and the properties of the charged materials could not be controlled, which could hinder stable charging.
Therefore, when water is introduced from the outside in order to ensure fluidity and diluted in the adjustment tank, the amount of processing in the methane fermentation tank increases, the storage tank for storing liquid fertilizer increases in size, and excessive production of liquid fertilizer It becomes.

In addition, when returning the digestion liquid from the methane fermentation tank to the adjustment tank instead of water from the outside and using it as dilution water, gas such as methane and hydrogen is generated in the adjustment tank due to the methane-producing bacteria remaining in the digestion liquid. There was a problem that the solubilization treatment could not be performed smoothly.
In addition, since the liquid fertilizer manufacturing method described in patent document 1 uses the starch manufacture waste_water | drain with low solid concentration as a raw material, the adjustment tank which performs a solubilization process is unnecessary, and is different from the processing flow of organic waste It is.
Therefore, in view of the above-mentioned problems of the prior art, the present invention can reduce the amount of heat consumed for heating in the adjustment tank for solubilizing organic waste, and can stably and efficiently perform methane fermentation. An object of the present invention is to provide a method and system for methane fermentation treatment of radioactive waste.

Therefore, in order to solve this problem, the present invention provides:
After heating and solubilizing the organic waste in the adjustment tank, the liquid waste from the adjustment tank is subjected to methane fermentation in the methane fermentation tank, and the digested sludge from the methane fermentation tank is removed in the sterilization tank. In the methane fermentation treatment method for organic waste produced by heat sterilization to produce liquid fertilizer, the digested sludge from the methane fermentation tank is solid-liquid separated, and only the separated liquid is separated into the sterilization tank. While being introduced, a part of the liquid manure discharged from the sterilization tank is returned to the adjustment tank, and the liquid manure is used as dilution water for organic waste.
In addition, after heating and solubilizing the organic waste in the adjustment tank, the liquid waste from the adjustment tank is subjected to methane fermentation in the methane fermentation tank, and the digested sludge from the methane fermentation tank is sterilized. in the methane fermentation treatment method for the organic waste which is adapted to produce a liquid fertilizer and heat sterilization treatment with bath,
Digested sludge from the methane fermentation tank is subjected to heat sterilization treatment in the sterilization tank, followed by solid-liquid separation, a part of the liquid fertilizer from which the solid content has been separated is returned to the adjustment tank, and the liquid fertilizer is diluted with organic waste. It is characterized by being used as water.

  According to the present invention, since the liquid fertilizer obtained by heat sterilization treatment in a sterilization tank has a high temperature, it can also be used as a heat source for solubilizing organic waste in a conditioning tank, and can efficiently reduce the amount of heat consumed. Processing. Compared with the case where digested sludge is returned directly, the liquid fertilizer is heat sterilized, so that microorganisms that promote gas generation such as methanogens are also sterilized or damaged. It is possible to prevent a problem that gas such as hydrogen gas is generated. Moreover, the dilution water from the outside can be reduced or eliminated, and the volume of the facility for storing liquid fertilizer can be reduced. Thereby, it becomes possible to accept food wastes having a solids concentration TS of 20 to 90%, for example, high solids wastes such as waste biscuits and waste flour.

Then , the digested sludge from the methane fermentation tank is subjected to solid-liquid separation, and only the separated liquid separated into the sterilization tank is introduced into the sterilization tank to sterilize only the separated liquid obtained by solid-liquid separation of the digested sludge as liquid fertilizer. Therefore, the solid matter concentration of liquid fertilizer is small, transfer for return is easy, and moisture adjustment and concentration adjustment in the adjustment tank are easy. Moreover, organic waste can be efficiently diluted with a small amount of liquid fertilizer, and the concentration after dilution can be easily grasped. Furthermore, since only the separated liquid after solid-liquid separation is supplied to the sterilization tank and subjected to heat sterilization treatment, the amount of treatment in the sterilization tank can be reduced, and the amount of heat consumed can be reduced.

Also, the digested sludge from the methane fermentation tank, solid-liquid separation after the heat sterilization treatment with the sterilizing chamber, by reversal of the portion of the liquid fertilizer separated solids to the adjusting tank, heat sterilization digested sludge By performing solid-liquid separation after the treatment to obtain liquid fertilizer from which the solid content has been separated, the solid concentration of the liquid fertilizer is small, transfer for return is easy, and moisture adjustment and concentration adjustment in the adjustment tank are facilitated. Moreover, organic waste can be efficiently diluted with a small amount of liquid fertilizer, and the concentration after dilution can be easily grasped. Furthermore, the separated sludge is sterilized together with the liquid fertilizer, and can be used as a highly safe compost with few pathogens.

Moreover, the adjustment tank which solubilizes the organic waste by heating, the methane fermentation tank which carries out the methane fermentation treatment of the liquid waste from the adjustment tank, and the digested sludge from the methane fermentation tank are heat sterilized. In a methane fermentation treatment system for organic waste, comprising a sterilization tank adapted to obtain liquid fertilizer,
A solid-liquid separator is provided at the subsequent stage of the methane fermentation tank, and the separated liquid separated by the solid-liquid separator is introduced into the sterilization tank.
A return line for returning a part of the liquid manure from the outlet side of the sterilization tank to the adjustment tank is provided.

Also, the adjustment tank for solubilizing organic waste by heating, and the methane fermentation tank to the methane fermentation treatment of liquid waste from the conditioning tank, heat sterilization digested sludge from the methane fermentation tank In a methane fermentation treatment system for organic waste comprising a sterilization tank adapted to obtain liquid fertilizer,
Rutotomoni provided a solid-liquid separation device downstream of the sterilization chamber,
Provide a return line to return a part of the liquid manure from the outlet side of the sterilization tank to the adjustment tank ,
A portion of liquid fertilizer separated solids in the solid-liquid separator, characterized in that it returned to the adjusting tank by the return line.

  As described above, according to the present invention, since the liquid fertilizer obtained by heat sterilization treatment in a sterilization tank has a high temperature, it can also be used as a heat source for solubilizing organic waste in a conditioning tank, and the amount of heat consumed can be reduced. Reduction and efficient processing can be achieved. Compared with the case where digested sludge is returned directly, the liquid fertilizer is heat sterilized, so that microorganisms that promote gas generation such as methanogens are also sterilized or damaged. It is possible to prevent a problem that gas such as hydrogen gas is generated. Moreover, the dilution water from the outside can be reduced or eliminated, and the volume of the facility for storing liquid fertilizer can be reduced. Thereby, it becomes possible to accept high solids concentration wastes with a solids concentration TS of 20 to 90%.

  In addition, by sterilizing only the separated liquid obtained by solid-liquid separation of digested sludge to make liquid fertilizer, the solid concentration of liquid fertilizer is small, easy transfer for return, easy adjustment of water content and concentration in the adjustment tank It becomes. Moreover, organic waste can be efficiently diluted with a small amount of liquid fertilizer, and the concentration after dilution can be easily grasped. Furthermore, since only the separated liquid after solid-liquid separation is supplied to the sterilization tank and subjected to heat sterilization treatment, the amount of treatment in the sterilization tank can be reduced, and the amount of heat consumed can be reduced.

  In addition, the digested sludge is heat-sterilized and then separated into solid and liquid, and the liquid fertilizer from which the solid content is separated makes the solid concentration of the liquid fertilizer small and easy to transport for return. Concentration adjustment is easy. Moreover, organic waste can be efficiently diluted with a small amount of liquid fertilizer, and the concentration after dilution can be easily grasped. Furthermore, the separated sludge is sterilized together with the liquid fertilizer, and can be used as a highly safe compost with few pathogens.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a block diagram of a processing system according to an embodiment of the present invention. In this treatment system, an organic waste 10 is input, a pretreatment facility 1 that performs pretreatment such as crushing and sorting, and an adjustment tank 2 that heats and solubilizes the pretreated organic waste 10. Then, the liquid waste 12 from the adjusting tank 2 is supplied by the pumping pump 4, and the methane fermentation tank 5 for methane fermentation of the liquid waste 12 and the digested sludge 14 drawn from the methane fermentation tank 5 are pumped. 6, a sterilization tank 7 that obtains liquid fertilizer 15 by heat sterilizing digested sludge 14 and a liquid fertilizer storage facility 8 that stores the sterilized liquid fertilizer 15.

  The pretreatment facility 1 is a facility for performing a pretreatment for making the organic waste 10 suitable for methane fermentation, and includes at least one of crushing and sorting. Crushing crushes food waste into a size suitable for methane fermentation. Sorting removes unsuitable materials such as vinyl and plastic for methane fermentation. As the pretreatment facility 1, a rotary sorter, a rotary blade crushing sorter, a selective crushing sorter, a compression sorter, a wet pulverization sorter, or the like is used.

Organic waste 10 pretreated by the pretreatment facility 1 is supplied to the adjustment tank 2. The adjustment tank 2 lowers the molecular weight of the solid matter of the organic waste 10 by heating to make it soluble. For example, the organic waste 10 is heated to about 30 to 45 ° C. by a heating means (not shown) to solubilize the organic waste 10. At this time, it includes that partial acid fermentation is performed. The adjustment tank 2 is stirred and mixed by stirring means. As an example, a configuration in which a stirring pump 3 is provided as shown in FIG. 1 and the liquid waste 11 partially extracted from the adjusting tank 2 is returned to the adjusting tank 2 by the stirring pump 3 and circulated to stir the inside of the tank. .
Moreover, the adjustment tank 2 performs water quantity adjustment and concentration adjustment with dilution water. This diluted water will be described later.

  In the methane fermentation tank 5, anaerobic microorganisms such as methanogens are propagated in the tank, and conditions such as temperature and pH are maintained in an environment where anaerobic microorganisms can prominently propagate. A methane production stage including acetic acid production and methane production is performed, and biogas 13 and digested sludge 14 are generated. The methane fermentation tank 5 may use either medium temperature methane fermentation or high temperature methane fermentation. In the case of medium temperature methane fermentation, the temperature condition in the tank is about 37 ± 2 ° C., and in the case of high temperature methane fermentation, the tank The internal temperature condition is about 55 ± 2 ° C.

The sterilization tank 7 is sterilized by being supplied with the digested sludge 14 drawn from the methane fermentation tank 5 by the pump 6 and heating the digested sludge 14 with heating means (not shown). Preferably, it heats to 65-80 degreeC.
The liquid fertilizer storage facility 8 stores liquid fertilizer 15 obtained by sterilization in the sterilization tank 7. In the liquid fertilizer storage facility 8, as needed, an element that is insufficient as liquid fertilizer is added to adjust the components, or the SS concentration is adjusted.

About the processing system which has the above structure, the effect | action is demonstrated with a processing method.
The organic waste 10 is subjected to pretreatment such as crushing and sorting in the pretreatment facility 1, and then a part of the liquid fertilizer 15 from the sterilization tank 7 is supplied as dilution water in the adjustment tank 2 and heated. Solubilized. The liquid waste 12 discharged from the adjustment tank 2 is fed to the methane fermentation tank 5 by the pressure feed pump 4.
In the methane fermentation tank 5, the liquid waste 12 is subjected to methane fermentation treatment to generate biogas 13 and digested sludge 14. The biogas 13 is preferably recovered and effectively used in a methane utilization facility. As an example, the biogas 13 is collected in a gas holder, desulfurized in a desulfurization tower, and then used as a fuel for a gas engine.
The digested sludge 14 is fed to the sterilization tank 7 by the pressure pump 6, and is heat sterilized at 65 to 80 ° C. in the sterilization tank 7. The liquid fertilizer 15 obtained by sterilization in the sterilization tank 7 is supplied to the liquid fertilizer storage facility 8 and stored. Moreover, a part of liquid fertilizer 15 is returned to the adjustment tank 2 via the return line 16, and is used for the water | moisture content adjustment and density | concentration adjustment of the organic waste 10 as dilution water. In addition, as dilution water supplied to the adjustment tank 2, in addition to the returned liquid fertilizer 15, dilution water from the outside such as industrial water may be supplied together as usual.

  In the present embodiment, the liquid fertilizer 15 obtained by heat sterilization treatment in the sterilization tank 7 has a high temperature of 65 to 80 ° C., and thus can be used as a heat source for solubilizing the organic waste 10 in the adjustment tank 2. Thus, the heat consumption can be reduced and the processing can be made efficient. In addition, compared with the case where the digested sludge 14 is returned directly, the liquid fertilizer 15 is heat sterilized, so that microorganisms that promote gas generation such as methane-producing bacteria are also sterilized or damaged. This prevents problems such as the generation of methane gas and hydrogen gas. Moreover, the dilution water from the outside can be reduced or eliminated, and the volume of the liquid manure storage facility 8 can also be reduced. Thereby, it becomes possible to accept food wastes having a solids concentration TS of 20 to 90%, for example, high solids wastes such as waste biscuits and waste flour.

2 and 3 are block diagrams of processing systems to which the above embodiment is applied.
In addition to the configuration shown in FIG. 1, the treatment system shown in FIG. 2 connects a solid-liquid separation device 9 to the digested sludge outlet side of the methane fermentation tank 5, and connects the solid-liquid separation device 9 to the separation liquid outlet side. The sterilization tank 7 is connected.
In this configuration, the digested sludge 14 from the methane fermentation tank 5 is fed to the solid-liquid separator 9 and separated into the separated liquid 17 and the separated sludge 18 by the solid-liquid separator 9, and only the separated liquid 17 is separated. It is fed to the sterilization tank 7 and heat sterilized. The liquid fertilizer 15 from the sterilization tank 7 is sent to the liquid fertilizer storage facility 8, and a part of the liquid fertilizer 15 is returned to the adjustment tank 2 through the return line 16 and used as dilution water. On the other hand, the separated sludge 18 is processed by a composting process, an incineration process, a fueling process, or the like, but preferably is composted, whereby the organic waste 10 can be effectively recycled.

According to this configuration, since only the separation liquid 17 obtained by solid-liquid separation of the digested sludge 14 is sterilized to form the liquid fertilizer 15, the solid matter concentration of the liquid fertilizer 15 is small, and compared with the processing system shown in FIG. Therefore, moisture adjustment and concentration adjustment in the adjustment tank 2 are facilitated. In addition, the organic waste 10 can be efficiently diluted with a small amount of liquid fertilizer 15, and the concentration after dilution can be easily grasped. Moreover, the organic waste 10 can be effectively recycled by composting the separated sludge 18.
Furthermore, since only the separated liquid 17 after the solid-liquid separation is supplied to the sterilization tank 7 and heat sterilized, the amount of processing in the sterilization tank 7 can be reduced, and the amount of heat consumed can be reduced.

In addition to the configuration shown in FIG. 1, the treatment system shown in FIG. 3 has a solid-liquid separation device 9 connected to the outlet side of the sterilization tank 7, and a liquid manure storage facility on the separation liquid outlet side of the solid-liquid separation device 9. 8 is connected, and a return line 16 for returning a part of the separated liquid (liquid fertilizer) 17 from the solid-liquid separator 9 to the adjustment tank 2 is provided.
In this configuration, the digested sludge 14 from the methane fermentation tank 5 is heat sterilized in the sterilization tank 7, and then the obtained liquid fertilizer 15 is supplied to the solid-liquid separation device 9. The separated liquid fertilizer 17 is sent to the liquid fertilizer storage facility 8, and a part of the liquid fertilizer 17 is returned to the adjustment tank 2 through the return line 16 and used as dilution water.

According to this configuration, the digested sludge 14 is subjected to heat sterilization treatment, followed by solid-liquid separation to obtain the liquid fertilizer 17 from which the solid content is separated, so that the solid matter concentration of the liquid fertilizer 17 is small and compared with the treatment system shown in FIG. In addition, transfer for return is easy, and moisture adjustment and concentration adjustment in the adjustment tank 2 become easy. Moreover, the organic waste 10 can be efficiently diluted with a small amount of liquid fertilizer 17, and the concentration after dilution can be easily grasped. Moreover, the organic waste 10 can be effectively recycled by composting the separated sludge 18.
Further, the separated sludge 18 is sterilized together with the liquid fertilizer 17 and can be used as a highly safe compost with few pathogens.

  The present invention can reduce the amount of heat consumed by the system, enables stable and efficient methane fermentation treatment, and can produce a safe liquid fertilizer. It can be widely applied to all systems for manufacturing.

1 is a block diagram of a processing system according to an embodiment of the present invention. 1 is a block diagram of a processing system to which an embodiment of the present invention is applied. 1 is a block diagram of a processing system to which an embodiment of the present invention is applied. It is a block diagram of the conventional methane fermentation processing system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pretreatment apparatus 2 Adjustment tank 3 Circulation pump 4, 6 Pressure feed pump 5 Methane fermentation tank 7 Sterilization tank 8 Liquid fertilizer storage equipment 9 Solid-liquid separation apparatus 10 Organic waste 13 Biogas 14 Digested sludge 15 Liquid fertilizer 16 Return line 17 Separation liquid (Liquid fertilizer)
18 Separation sludge

Claims (4)

After heating and solubilizing the organic waste in the adjustment tank, the liquid waste from the adjustment tank is subjected to methane fermentation in the methane fermentation tank, and the digested sludge from the methane fermentation tank is removed in the sterilization tank. the methane fermentation treatment method of heat sterilization and organic waste which is adapted to produce a liquid fertilizer and,
Solid-liquid separation of the digested sludge from the methane fermentation tank, and only introducing the separated liquid into the sterilization tank,
A part of liquid manure discharged from the sterilization tank is returned to the adjustment tank, and the liquid fertilizer is used as dilution water for organic waste. After heating and solubilizing the organic waste in the adjustment tank, the liquid waste from the adjustment tank is subjected to methane fermentation in the methane fermentation tank, and the digested sludge from the methane fermentation tank is removed in the sterilization tank. in the methane fermentation treatment method of the heat sterilized organic waste which is adapted to produce a liquid fertilizer and,
Digested sludge from the methane fermentation tank is subjected to heat sterilization treatment in the sterilization tank, followed by solid-liquid separation, a part of the liquid fertilizer from which the solid content has been separated is returned to the adjustment tank, and the liquid fertilizer is diluted with organic waste. A method for methane fermentation treatment of organic waste, characterized by being used as water. An adjustment tank for solubilizing organic waste by heating, a methane fermentation tank for methane fermentation of liquid waste from the adjustment tank, and digestion sludge from the methane fermentation tank by heat sterilization treatment to produce liquid fertilizer An organic waste methane fermentation treatment system comprising:
A solid-liquid separator is provided at the subsequent stage of the methane fermentation tank, and the separated liquid separated by the solid-liquid separator is introduced into the sterilization tank.
An organic waste methane fermentation treatment system comprising a return line for returning a part of the liquid fertilizer from the outlet side of the sterilization tank to the adjustment tank. An adjustment tank for solubilizing organic waste by heating, a methane fermentation tank for methane fermentation of liquid waste from the adjustment tank, and digestion sludge from the methane fermentation tank by heat sterilization treatment to produce liquid fertilizer An organic waste methane fermentation treatment system comprising:
While providing a solid-liquid separator at the subsequent stage of the sterilization tank,
Provide a return line to return a part of the liquid manure from the outlet side of the sterilization tank to the adjustment tank,
An organic waste methane fermentation treatment system, wherein a part of liquid fertilizer from which solid content has been separated by the solid-liquid separator is returned to the adjustment tank by the return line.

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