JP2019214026A - Post-processing method and apparatus for methane fermentation liquid - Google Patents

Abstract

To provide a post-processing method and apparatus for methane fermentation liquid capable of simplifying cleaning in a post-processing step.SOLUTION: A fermented liquid F obtained after a methane fermentation treatment of biomass S, is introduced into a bottomed chamber 11 and temporarily stored therein, and aeration is performed in the bottomed chamber 11 to precipitate high pH crystallizing components (for example, phosphate ions, ammonium ions, and magnesium ions) in the fermented liquid F by increasing pH, then, a metal frame net 17 is exchangeably laid during the aeration in the bottomed chamber 11 so that at least a part of the precipitated crystal (for example, MAP) is attached thereto and the fermented liquid F after crystallization is overflowed from the bottomed chamber 11 to a subsequent post-treatment step. Preferably, a pair of bottomed chambers 11a and 11b are connected to an inflow path of the fermented liquid F after the methane fermentation treatment via a switching valve, and when one of the bottomed chambers 11a and 11b is connected, the other is cleaned.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and an apparatus for post-treatment of a methane fermentation liquor, and more particularly to a method and an apparatus for post-treatment of a fermentation liquor generated after a methane fermentation treatment of biomass.

  From the viewpoint of forming a recycling-oriented society, biomass S containing organic matter such as garbage, high-concentration organic wastewater, surplus sludge, and livestock manure is anaerobically decomposed by microorganisms to generate biogas G as an energy source. A methane fermentation treatment technology has been put to practical use (see Patent Literature 1 and Non-Patent Literature 1). Referring to FIG. 4, the flow of the conventional methane fermentation plant will be described to the extent necessary for understanding the present invention. First, the biomass S to be treated is stored in a raw material tank 1, subjected to pretreatment such as separation of foreign matter, pulverization, dilution, etc. as necessary, and then fed into a methane fermentation tank (bioreactor) 2 by a raw material pump 1a. Provide for fermentation treatment.

  The methane fermentation treatment (organic matter digestion process) in the methane fermentation tank 2 is a complicated reaction process in which various organic substances such as proteins, carbohydrates, and lipids are decomposed by symbiosis of many microbial groups. High molecular weight organic substances are decomposed into low molecular weight alcohols, fatty acids, hydrogen, etc. in the stage, fatty acids, etc. are oxidatively decomposed into acetic acid in the second stage, and finally biogas G is produced from acetic acid, hydrogen, etc. in the third stage Is done. The illustrated example shows a wet methane fermentation tank 2 for treating biomass S having a relatively low solids concentration, but a dry methane fermentation tank for processing biomass S having a relatively high solids concentration. It is also possible.

  In the methane fermenter 2, biogas G is generated, and a fermentation liquid or a fermentation residue (hereinafter, both are collectively referred to as a fermentation liquid) F is generated after the fermentation treatment. The fermentation liquor F can be recycled as a compost (compost), soil improvement material, or the like by performing post-treatment, or can be rendered harmless by appropriate wastewater treatment or the like. In the illustrated post-treatment step, first, the fermentation liquid F generated in the methane fermentation treatment is sent to the fermentation liquid adjustment tank 20 via the inflow passage 2a and temporarily stored therein, and the fermentation liquid F in the adjustment tank 20 is solidified by the fermentation liquid pump 29. The liquid is sent to a liquid separator (eg, a dehydrator) 30 to separate a solid phase and a liquid phase. At the time of solid-liquid separation, a coagulant may be added from the coagulant tank 31 by the coagulant pump 31a as shown in the illustrated example. The liquid phase after solid-liquid separation is once stored in a filtrate tank 32 and sent to a wastewater treatment device (for example, an activated sludge treatment device) 34 by a filtrate pump 33 so that it can be detoxified to a predetermined environmental standard value. The fermentation liquid F can be discharged into an environment such as a sewer by a drain pump 35, for example. Also, the solid phase after solid-liquid separation can be put into an appropriate composting device and recycled.

JP 2000-167523 A JP 2004-195453 A

The New Energy Foundation, “Biomass Technology Handbook-Know-how for Introduction and Commercialization-Chapter 3, Methane Fermentation” Ohmsha Co., Ltd., October 25, 2008, pp. 206-447 Agricultural and Food Technology Research Organization Press Release “Development of Technology for Reusing Phosphorus Generated in Swine Raising” Published June 18, 2008, Internet <http: // www. nar. affrc. go. jp / publicity_report / press / laboratory / nilgs / 012887. html> Kazuaki Shimamura et al., "Validation of Highly Efficient Phosphorus Recovery Method Using Two-Bed Fluidized-Bed MAP Reactor," Ebara Times No. 206, published in 2005, Internet <http: // www. ebara. co. jp / about / technologies / abstract / detail / __ icsFiles / afieldfile / 2016/04/25 / 206_P23_1. pdf>

However, in the conventional methane fermentation treatment, the crystallized components dissolved in the fermentation solution F after the methane fermentation treatment are subjected to the post-treatment step (particularly, from the fermenter storage tank 20 surrounded by the dotted line in FIG. In the following steps), and the deposited crystals may cause blockage of the inside of the processing tank / piping and affect the operation of the plant. Most of the precipitated crystals are when the biomass S to be treated contains crystallization components such as phosphate ions (PO ₄ ^3- ), ammonium ions (NH ₄ ⁺ ), and magnesium ions (Mg ²⁺ ). And magnesium ammonium phosphate (MgNH ₄ PO ₄ ; hereinafter, referred to as MAP) formed by combining them.

The target of methane fermentation is a complex buffer solution containing many buffers, and the precipitation of crystals in the post-treatment process is caused by multiple conditions (pressure, temperature, etc.). It is difficult to simply formulate the reaction. However, in the raw material tank 1 in FIG. 4, the acidity is usually maintained at about pH 4 to 5 by the lactic acid fermentation reaction, and in the methane fermentation tank 2, the pH is usually maintained at about 7.5 by the decomposition reaction to the bio-iogas G described above. On the other hand, the fermented liquid F discharged from the methane fermenter 2 is gradually released as dissolved carbon dioxide (H ₂ CO ₃ ) as carbon dioxide (CO ₂ ). In the post-treatment step, the pH rises and usually reaches pH 8 or higher. One cause of the precipitation of crystals such as MAP in the post-treatment process is considered to be such an increase (alkalineization) of the fermentation liquid F at pH 8 or higher. That is, phosphate ions, ammonium ions, magnesium ions, and the like that form crystals such as MAP are crystallization components (hereinafter, sometimes referred to as high pH crystallization components) that precipitate due to an increase in pH.

  In a conventional methane fermentation plant of biomass S containing a high pH crystallization component, to prevent crystals such as MAP precipitated in the post-treatment process from blocking the treatment tanks and pipes, periodically or as needed. It is essential to clean the inside. However, once the operation of the methane fermentation tank 2 is temporarily stopped, it takes a long time to restart. Therefore, cleaning of the post-processing step may be required without stopping the operation of the methane fermentation tank 2. There is a demand for the development of a technology that can be cleaned without any hassle.

  The present inventor has paid attention to intensively and efficiently precipitating high pH crystallized components in a pre-stage of a post-treatment step of a methane fermentation treatment. For example, in the treatment of high-concentration organic wastewater (swine sewage) generated in the pig farming industry, etc., a technique of recovering phosphoric acid contained in the organic wastewater as MAP has been developed (Patent Document 2, Non-Patent Documents 2). 3). If such a crystal recovery technology is applied to the post-treatment step of the methane fermentation treatment, and if high pH crystallized components can be intensively and efficiently precipitated in the front part of the post-treatment step, the latter part of the post-treatment step Therefore, it can be expected that the precipitation of crystals at the step is suppressed to be small, and the cleaning operation of the whole post-processing step is simplified.

  Therefore, an object of the present invention is to provide a method and an apparatus for post-treatment of a methane fermentation solution, which can simplify cleaning of a post-treatment step.

  Referring to the embodiment of FIG. 1 (A), the post-treatment method of the methane fermentation liquid according to the present invention is such that the fermentation liquid F after the methane fermentation treatment of the biomass S is introduced into the bottomed chamber 11 and temporarily stays there. A high-pH crystallizing component (eg, phosphate ion, ammonium ion, magnesium ion) in the fermentation solution F is precipitated by increasing the pH by aerating the inside of the chamber 11, and is exchangeably deposited in the bottomed chamber 11. At least a part of the precipitated crystals (for example, MAP) during aeration is attached to the frame network 17, and the fermented liquid F after the crystal deposition is caused to overflow from the bottomed chamber 11 to a subsequent post-processing step.

  Referring to the embodiment of FIG. 1 (A), the post-treatment apparatus for the methane fermentation liquid according to the present invention incorporates a bottomed chamber 11 for temporarily storing the fermentation liquid F after the methane fermentation treatment of biomass S, Aeration device 15 for aerating into bottom chamber 11 to precipitate high pH crystallization components (for example, phosphate ions, ammonium ions, magnesium ions) in fermentation solution F by increasing the pH, and aeration device 15 in bottomed chamber 11 It is provided with a metal frame network 17 which is set up so that it can be exchanged upward, and an overflow weir 14 which allows the fermented liquid F after crystal precipitation to overflow from the bottomed chamber 11 to the subsequent post-processing step.

  In a preferred embodiment, as shown in FIG. 2A, a pair of bottomed chambers 11a and 11b are provided, and the inflow passage 2a of the fermented liquid after the methane fermentation treatment is taken into one of the inlets of the bottomed chambers 11a and 11b. A switching valve 40 is provided to connect to one of the chambers 12, and the other is cleaned when one of the bottomed chambers 11a and 11b is connected.

  In another preferred embodiment, as shown in FIG. 1 (B), a fermentation liquid adjusting tank 20 for storing the fermentation liquid F overflowing from the overflow weir 14 is provided, and the bottomed chamber 11 is provided with the flow of the fermentation liquid adjustment tank 20. A small bottomed room 11 with an overflow weir 14 is provided inside the entrance 21 and partitioned from the surroundings, and an aeration device 15 and a frame net 17 are provided in the small bottomed room 11.

  In a preferred embodiment, as shown in FIG. 1 (B), an aeration device 26 is also provided in the fermentation liquid adjusting tank 20 to remove the high pH crystallized component in the unprecipitated fermentation liquid F in the bottomed small room 11. In the adjustment tank 20, precipitation is performed by increasing the pH. Further, an inclined bottom surface 23 is provided in the fermentation liquid adjusting tank 20, and a collection groove 24 for precipitated crystals can be formed at the lower end of the inclined bottom surface 23.

  In a more preferred embodiment, as shown in FIG. 2 (B), a pair of fermented liquid conditioning tanks 20a and 20b with a small bottomed chamber 11 are provided, and the inflow passage 2a of the fermented liquid F after the methane fermentation treatment has a small bottomed. A switching valve 40 is provided which is connected to one of the inlets 21 of the fermentation liquid adjusting tanks 20a and 20b with the room 11.

  The post-treatment method and apparatus of the methane fermentation solution according to the present invention take the fermentation solution F after the methane fermentation treatment of the biomass S into the bottomed chamber 11 to temporarily stay there, and aeration is performed by the aeration device 15 in the bottomed chamber 11. The high pH crystallized component in the fermentation liquid F is precipitated by increasing the pH, and a metal frame network 17 is exchangeably disposed during the aeration in the bottomed chamber 11 to replace at least a part of the precipitated crystal (for example, MAP). Since the fermented liquid F after the deposition and the precipitation of the crystals overflows from the bottomed chamber 11 to the subsequent post-processing step, the following advantageous effect is obtained.

(A) High-pH crystallized components are intensively precipitated in the first part of the post-treatment step of the methane fermentation treatment, and the precipitation of crystals in the second part of the post-treatment step is suppressed to a small degree, so that the entire post-treatment step is cleaned. Can be simplified.
(B) A bottomed chamber 11 for intensively precipitating high-pH crystallized components is provided at the front stage of the post-treatment step of the methane fermentation treatment, and a metal frame for adhering the precipitated crystals inside the bottomed chamber 11. By providing the body net 17, the clogging of the processing tanks and pipes in the post-processing step can be avoided by a simple short work of replacing the bottomed chamber 11 or the frame net 17 as necessary.

(C) If a pair of bottomed chambers 11a and 11b are connected to the inflow path 2a of the fermentation liquid F via the switching valve 40, the other bottomed chamber 11b can be cleaned when one bottomed chamber 11a is connected. Thus, the post-treatment step can be cleaned without stopping the inflow of the fermentation liquid F.
(D) Further, by forming the bottomed chamber 11 into a small bottomed chamber 11 having an overflow weir 14 provided inside the inlet 21 of the fermentation liquid regulating tank 20 and partitioned from the surroundings, the precipitation of high pH crystallized components is achieved. Even if it is not possible to secure a separate space for the high-temperature crystallization, the high pH crystallized component can be intensively deposited by using a part of the installation space of the conventional fermentation solution adjusting tank 20.

Hereinafter, embodiments and examples for carrying out the present invention will be described with reference to the accompanying drawings.
It is an explanatory view of one embodiment of a post-treatment method of a methane fermentation solution according to the present invention. FIG. 4 is an explanatory view of another embodiment of the post-treatment method of the methane fermentation liquid according to the present invention. It is explanatory drawing of an example of the aeration apparatus 15 and frame net 17 used by this invention. It is explanatory drawing of an example of the post-processing method of the conventional methane fermentation liquid.

  FIG. 1A shows an embodiment of a method for post-treatment of a methane fermentation solution according to the present invention. In the illustrated post-treatment method, the precipitation tank 10 is provided between the methane fermentation tank 2 and the fermentation liquid adjustment tank 20 described above with reference to FIG. The fermentation liquid F generated in the methane fermentation tank 2 immediately after the methane fermentation treatment is introduced into the precipitation tank 10, and the high pH crystallized components in the fermentation liquid F are intensively precipitated in the precipitation tank 10. Is overflowed into the fermented liquid adjusting tank 20 which is a subsequent post-processing step. By providing the precipitation tank 10 immediately after the methane fermentation tank 2, high pH crystallized components are intensively precipitated in the pre-stage of the post-treatment process, and the precipitation of crystals in the post-stage of the post-treatment process is suppressed to be small. The cleaning operation of the entire process can be simplified. The installation position of the precipitation tank 10 is not limited to the position immediately after the fermentation tank 2 as in the illustrated example, but can be appropriately selected in the preceding stage of the post-treatment process.

  In the illustrated example, the precipitation tank 10 has a bottomed chamber 11 for taking in and temporarily retaining the fermentation liquid F, an aeration device 15 provided at the bottom of the bottomed chamber 11, and a fermentation liquid F above the aeration device 15 which can be exchanged. And a metal frame net 17 submerged in the metal frame. The bottomed chamber 11 is provided with an inlet 12 connected to the fermentation liquid inflow passage 2a, and an overflow weir 14 connected to the subsequent fermentation liquid adjustment tank 20. The intake fermentation liquid F stays for a predetermined time. Can be done. The capacity of the bottomed chamber 11 can be designed so that the high pH crystallized component in the fermentation solution F stays for a sufficient time to be deposited in accordance with the intake flow rate of the fermentation solution F. Therefore, it is desirable to design in consideration of the labor and time of cleaning.

The aeration apparatus 15 in the illustrated example replaces the carbon dioxide gas (H ₂ CO ₃ ) dissolved in the fermentation liquid F with the aeration gas P and drives it out, so that the high pH crystallization components (phosphate ion, ammonium Ions, magnesium ions) to raise the pH in the bottomed chamber 11 to such an extent as to precipitate. An example of the aeration gas P is air, but it is also possible to use a nitrogen gas or another harmless gas. As described above, in the conventional methane fermentation treatment, crystals such as MAP are precipitated in the post-treatment step in which the fermentation liquid F has a pH of 8 or more. By increasing the temperature to about 9 or more, intensive and efficient precipitation of the high pH crystallized component in the bottomed chamber 11 can be promoted.

  The aeration device 15 can be installed at an appropriate position in the bottomed chamber 11, but is preferably provided at the bottom of the bottomed chamber 11. By providing the aeration device 15 at the bottom of the bottomed chamber 11, the entire fermentation liquid F can be aerated while being stirred, and the pH of the fermentation liquid F inside the bottomed chamber 11 can be raised as a whole. Further, the aeration of the fermentation liquid F while stirring it enhances the precipitation efficiency of the high pH crystallized components in the fermentation liquid F as a whole, and increases the unprecipitated high concentration in the fermentation liquid F overflowing from the bottomed chamber 11. The pH crystallization component can be reduced, and the precipitation of crystals in the subsequent post-treatment step can be suppressed to a small level. In the illustrated example, a single aeration device 15 is provided at the bottom of the bottomed chamber 11, but a plurality of aeration devices 15 can be provided at the bottom of the bottomed chamber 11.

  In the illustrated metal frame network 17, crystals such as MAP deposited in the post-treatment process of the conventional methane fermentation process adhere to the metal surface of the treatment tank / pipe, and further precipitation proceeds on the surface to grow. Therefore, an environment in which crystals are deposited, adhered, and grown is created above the aeration device 15 where the air diffuses (bubbles). The frame net 17 can be made of a material to which crystals easily adhere and grow depending on the methane fermentation plant to be applied. For example, it can be made of aluminum, stainless steel, or copper. Further, the frame net 17 is desirably a net-like or basket-like shape through which air can freely pass so that the contact area of the aeration device 15 with the air is large. Furthermore, since the surface of the frame net 17 is more suitable for the attachment and growth of crystals than a smooth surface, it is desirable to perform an appropriate roughening treatment.

  The metal frame net 17 in the illustrated example can be fixed and attached to the upper surface of the aeration device 15 with a fixing jig 17a, and can be removed from the aeration device 15 by releasing the fixing jig 17a as necessary. . Some of the crystals deposited above the aeration device 15 do not adhere to the frame net 17 and precipitate, but most of the crystals adhere to the surface of the frame net 17. Therefore, the precipitated crystals can be collected by a simple short work of replacing the frame net 17 as necessary, and the cleaning work in the post-processing step can be simplified. However, the fixing of the frame net 17 to the aeration device 15 is not essential to the present invention, and the frame net 17 independent of the aeration device 15 may be suspended, for example, above the aeration device 15 and sunk. (See the aeration device 26 in FIG. 1B).

  FIG. 3 shows an embodiment of the aeration device 15 and the metal frame net 17 suitable for the present invention. The aeration device 15 shown in FIGS. 3A and 3B has a hollow tubular air supply pipe 15c having an intake port 15a at one end and a sealed end 15b at the other end, and a peripheral wall of the air supply pipe 15c. Are formed with a large number of blow holes 15d. By connecting the aeration hose 16 (see FIG. 1) to the intake port 15a to feed air, diffused air (bubbles) can be supplied from a number of outlets 15d in the peripheral wall. On one side along the central axis direction of the air supply pipe 15c, a leg portion for stably seating on the bottom surface of the bottomed chamber 11 is formed, and on the opposite side along the central axis direction, a metal frame net is formed. A mounting plate 15e for mounting the mounting member 17 is provided. If necessary, the aeration device 15 can include a plurality of air supply pipes 15c, and the pH of the fermentation liquid F inside the bottomed chamber 11 can be raised as a whole.

  FIGS. 3C and 3D show a state in which the metal frame net 17 is attached to the attachment plate 15e of the aeration device 15 described above and fixed by the fixing jig 17a. As shown in the illustrated example, the aerating device 15 is seated on the bottom surface of the bottomed chamber 11 in a state where the metal frame net 17 is fixed to the mounting plate 15e, so that the entire frame net 17 is dispersed by the aerating device 15. By intersecting with air (bubbles), the space where the frame net 17 is set can be set as an environment where crystals can be easily deposited, adhered and grown. A plurality of aerators 15 and a frame net 17 can be provided at the bottom of the bottomed chamber 11. By providing the plurality of aerators 15 and the frame net 17, the entire internal space of the bottomed chamber 11 can be reduced. An environment in which crystals can be easily deposited, adhered, and grown can be provided.

  As shown in FIG. 1 (A), the high pH crystallized components are intensively precipitated in the pre-stage of the post-processing step, and the frame net 17 is replaced as necessary, thereby simplifying the cleaning work in the post-processing step. Can be In FIG. 1A, instead of replacing the frame net 17, a plurality of deposition tanks 10 are prepared in advance, and the precipitation tanks 10 are replaced as necessary, thereby simplifying the cleaning work in the post-processing step. It is also possible to convert. As described above, most of the crystals precipitated inside the precipitation tank 10 adhere to the surface of the frame net 17, but a part thereof does not adhere and precipitates at the bottom of the bottomed chamber 11, so that the post-treatment step is closed. In order to avoid this, it is not enough to replace the frame net 17, but it is also necessary to clean the inside of the bottomed chamber 11. By replacing the precipitation tank 10 itself, it is possible to further simplify the cleaning operation in the post-processing step.

  Preferably, as shown in FIG. 2A, the precipitation tank 10 includes a pair of bottomed chambers 11a and 11b. Each of the bottomed chambers 11a and 11b is provided with an aeration device 15 and a metal frame net 17, and an intake 12 and an overflow weir 14. Further, a switching valve 40 (V1, V2) for connecting the inflow passage 2a of the fermented liquid to one of the inlets 12 of the bottomed chambers 11a and 11b is provided, and one of the bottomed chambers 11a and 11b overflows. A switching valve 40 (V3, V4) for connecting the weir 14 to the subsequent fermentation liquid adjusting tank 20 is provided.

  In the embodiment shown in FIG. 2A, for example, the switching valves V1 and V3 are opened (the switching valves V2 and V4 are closed) to incorporate the bottomed chamber 11a in the post-processing step, and the bottomed chamber 11a is used for the processing liquid F in the processing chamber. High pH crystallized components are intensively precipitated. After the deposited crystals are sufficiently deposited on the surface of the frame net 17, the switching valves V1 and V3 are closed (the switching valves V2 and V4 are opened) to separate the bottomed chamber 11a from the post-processing step and to remove the other bottomed chamber. The chamber 11b is installed, and the high pH crystallization component in the processing solution F is intensively precipitated in the other bottomed chamber 11b. The inside of the bottomed chamber 11a can be cleaned while being separated from the post-processing step.

  When the crystals deposited on the surface of the frame net 17 of the bottomed chamber 11b are sufficiently deposited, the switching valves V1 and V3 are opened (the switching valves V2 and V4 are closed) to remove the bottomed chamber 11b from the post-processing step. At the same time as the separation, the bottomed chamber 11a is installed again, and the high pH crystallized component in the processing solution F is intensively deposited in the bottomed chamber 11a. By repeatedly switching the bottomed chambers 11a and 11b in this manner, the post-treatment process can be easily cleaned while continuously receiving the fermentation liquid F without stopping the operation of the methane fermentation tank 2, and the post-treatment is performed. Blockage of processing tanks and pipes in the process can be avoided.

  Thus, it is possible to achieve the object of the present invention, that is, provision of "method fermentation solution post-treatment method and apparatus capable of simplifying post-treatment step cleaning".

  FIG. 1 (B) shows another embodiment of the present invention in which the bottomed chamber 11 of the precipitation tank 10 of FIG. 1 (A) is incorporated inside an inlet 21 of a fermentation liquid adjusting tank 20 which is a subsequent post-treatment step. Here is an example. As described above with reference to FIG. 1 (A), the precipitation tank 10 is installed between the methane fermentation tank 2 and the fermentation liquid adjustment tank 20 to concentrate high pH crystallized components in the fermentation liquid F. The precipitation suppresses the precipitation of crystals in the subsequent post-treatment process, but requires additional installation space as compared with the conventional fermentation solution adjusting tank 20. By incorporating the bottomed chamber 11 of the precipitation tank 10 inside the fermentation liquid adjustment tank 20 as shown in FIG. 1B, even if additional installation space cannot be secured, the fermentation liquid adjustment tank 20 can be installed. High pH crystallized components can be intensively precipitated by utilizing a part of the space.

  In the embodiment of FIG. 1 (B), a bottomed small room 11 with an overflow weir 14 is provided inside the inflow port 21 of the fermentation liquid adjusting tank 20 and partitioned from the surroundings. The deposition tank 10 is formed by disposing a metal frame net 17. The inflow port 21 of the fermentation liquid regulating tank 20 is connected to the fermentation liquid inflow passage 2a, and the fermentation liquid F generated in the methane fermentation tank 2 after the methane fermentation treatment is taken in from the inflow port 21 of the fermentation liquid regulating tank 20. In the illustrated example, the bottomed small room 11 is of an open-top type, and the fermentation liquid F introduced from the inlet 21 of the fermentation liquid adjusting tank 20 stays in the bottomed small room 11 inside the inlet 21 for a predetermined time, and After the high pH crystallization component is intensively precipitated in the small bottom chamber 11, it is sent from the overflow weir 14 of the small bottom chamber 11 to the fermentation liquid adjusting tank 20. The capacity of the bottomed small room 11 can also be designed so that the fermented liquid F stays for a time during which the high pH crystallized component is sufficiently precipitated, but it is desirable that the size be such that it can be cleaned in a short time.

  In the embodiment of FIG. 1 (B), an aeration device 26 is also provided in the fermented liquid adjusting tank 20, and the high pH crystallized component in the unprecipitated fermented liquid F in the small-bottomed room 11 is removed in the fermented liquid adjusting tank 20. Has been deposited. That is, the high pH crystallized component in the fermented liquid F is precipitated in the small-bottomed room 11 as much as possible. Unprecipitated high pH crystallization components may remain in F. Also in the fermentation liquor adjusting tank 20, the aeration device 26 raises the pH in the fermentation liquor F to promote the precipitation of the high-pH crystallized component. The high-pH crystallized component which has not been precipitated can be reduced, and the precipitation of crystals in the post-treatment step following the fermenter tank 20 can be suppressed.

  The aeration device 26 shown in FIG. 1 (B) is difficult to be seated on the inclined bottom surface 23 of the fermentation liquid adjusting tank 20, which will be described later. I have. In addition, in the small-bottomed room 11, the metal crystals 17 are attached to the aeration device 15 to attach and grow the deposited crystals, whereas the aeration of the fermentation solution adjusting tank 20 is performed by the non-precipitation in the fermentation solution F. The purpose is to supplement the precipitation of the high pH crystallized component of the fermentation solution. Therefore, the metal frame net 17 is not attached to the aeration device 26, and the precipitated crystals are precipitated on the bottom surface 23 of the fermentation solution adjusting tank 20. . However, it is also possible to attach the metal frame net 17 to the aeration device 26 of the fermentation solution adjusting tank 20 and attach and grow the precipitated crystals.

  The fermentation liquid adjusting tank 20 shown in FIG. 1 (B) has a slanted bottom surface 23, and by installing a dam plate 23a at the lower end portion of the slanted bottom surface 23, the precipitated crystals settled at the lower end portion of the bottom surface are removed. A collection groove 24 is formed. As described above, since the precipitated crystals are precipitated in the fermentation liquid adjusting tank 20, it may be necessary to appropriately clean the inside of the fermenting liquid adjusting tank 20, especially the entire bottom surface. As shown in the illustrated example, the bottom surface 23 is inclined so that the precipitated precipitated crystals collect in the collecting groove 24, so that the precipitated crystals can be collected by cleaning around the collecting groove 24, thereby simplifying the cleaning operation.・ The time can be shortened.

  Preferably, as shown in FIG. 2 (B), a pair of fermentation liquid adjusting tanks 20a and 20b are provided, and each of the adjusting tanks 20a and 20b is provided with a small-bottomed room 11, respectively, to form precipitation tanks 10a and 10b. An aeration device 15 and a metal frame net 17 are provided in the bottomed small room 11 of each of the adjusting tanks 20a and 20b, and an overflow weir 14 is provided. Further, a switching valve 40 (V1, V2) for connecting the fermentation liquid inflow path 2a to one of the inlets 21 of the fermentation liquid adjustment tanks 20a, 20b is provided, and one of the fermentation liquid adjustment tanks 20a, 20b is provided. A switching valve 40 (V3, V4) for connecting the outlet 22 to a subsequent post-processing step (for example, the fermentation liquid pump 29 and the solid-liquid separation device 30 in FIG. 4) is provided.

  As in the case of FIG. 2A described above, in the embodiment of FIG. 2B, for example, the switching valves V1 and V3 are opened (the switching valves V2 and V4 are closed) and the fermentation liquid adjusting tank 20a is moved backward. High pH crystallized components in the treatment liquid F are intensively precipitated in the bottomed small room 11 of the fermentation solution adjusting tank 20a, and are not concentrated in the fermentation solution adjusting tank 20a outside the bottomed small room 11. The high pH crystallization component of the precipitation is replenished. After the crystals have sufficiently precipitated, the switching valves V1 and V3 are closed (the switching valves V2 and V4 are opened) to disconnect the fermentation solution adjusting tank 20a from the post-processing step, and incorporate the other fermenting solution adjusting tank 20b. The high pH crystallized component in the treatment liquid F is intensively precipitated in the small-bottomed room 11 of the fermentation liquid adjusting tank 20b, and the non-precipitated high-pH crystals are further deposited in the fermentation liquid adjusting tank 20a outside the bottomed small room 11. The additional components are precipitated.

  Further, when crystals are sufficiently deposited in the fermentation liquid adjusting tank 20b, the switching valves V1 and V3 are opened (the switching valves V2 and V4 are closed) to disconnect the fermenting liquid adjusting tank 20b from the post-processing step and to adjust the fermentation liquid. The tank 20a is installed again, and the high pH crystallization component in the treatment liquid F is precipitated in the fermentation liquid adjusting tank 20a. By repeating the switching of the fermentation liquid adjusting tanks 20a and 20b in this way, even if it takes time to clean the inside of the fermentation liquid adjusting tanks 20a and 20b, there is no possibility that the operation of the methane fermentation plant will be affected. Further, it is possible to easily clean the post-processing step while continuously receiving the fermentation liquid F without stopping the operation of the methane fermentation tank 2, and it is possible to avoid clogging of the processing tank and piping in the post-processing step. Become.

DESCRIPTION OF SYMBOLS 1 ... Raw material tank 1a ... Raw material pump 2 ... Methane fermentation tank (bioreactor) 2a ... Fermentation liquid inflow path 10 ... Precipitation tank (precipitation chamber) 11 ... Bottomed chamber (bottomed small room)
DESCRIPTION OF SYMBOLS 12 ... Inlet 14 ... Overflow weir 15 ... Aeration device 15a ... Intake port 15b ... Sealed end 15c ... Air supply pipe 15d ... Outlet hole 15e ... Mounting plate 16 ... Aeration hose 17 ... Metal frame net 17a ... Fixing jig Reference Signs List 20 fermentation liquid adjustment tank 21 inlet 22 outlet 23 internal bottom surface (inclined bottom surface) 23a damming plate 24 collection groove 26 aeration device 27 aeration hose 28 hanging member 29 fermentation liquid pump 30 ... solid-liquid separator 31 ... flocculant tank 31a ... flocculant pump 32 ... filtrate tank 33 ... filtrate pump 34 ... wastewater treatment device 35 ... wastewater pumps 40 and 41 ... switching valve S ... biomass F ... fermented liquid G ... biogas P … Aeration gas

Claims (8)

The fermented liquor after the methane fermentation treatment of the biomass is introduced into a bottomed chamber and temporarily retained, and aerated in the bottomed chamber to precipitate high pH crystallized components in the fermented liquor by increasing the pH. Methane fermentation by adhering at least a part of the precipitated crystals during aeration to a metal frame mesh which is settled in a replaceable manner, and allowing the fermentation liquid after the crystal precipitation to overflow from a bottomed chamber to a subsequent post-treatment step. Post-treatment method for liquid. 2. The method according to claim 1, wherein a pair of said bottomed chambers is connected to an inflow path of the fermented liquid after the methane fermentation treatment via a switching valve, and methane formed by cleaning one when the one bottomed chamber is connected. Post-treatment method of fermentation liquor. A bottomed chamber for taking in the fermentation liquid after the methane fermentation treatment of biomass and temporarily retaining the fermentation liquid, an aeration apparatus for aerating the bottomed chamber to precipitate a high pH crystallized component in the fermentation liquid by increasing the pH, and the bottomed chamber A methane fermentation system comprising a metal frame mesh replaceably disposed above an aeration device in the inside, and an overflow weir for overflowing the fermentation solution after the crystal precipitation from a bottomed chamber to a subsequent post-treatment process. Liquid post-treatment device. The methane fermentation liquid according to claim 3, further comprising a pair of said bottomed chambers, and a switching valve for connecting an inflow path of the fermentation liquid after the methane fermentation treatment to any of the inlets of the bottomed chamber. Post-processing device. 4. The overflow weir according to claim 3, further comprising a fermentation liquid regulating tank for storing the fermentation liquid overflowing from the overflow weir, and wherein the bottomed chamber is partitioned from the surroundings inside an inlet of the fermentation liquid adjustment tank. A post-treatment device for a methane fermentation solution, wherein the methane fermentation solution is provided in a small room with a bottom, and the aeration device and the frame network are provided in the small room with a bottom. 6. The apparatus according to claim 5, wherein an aeration device is provided also in the fermentation liquid adjusting tank, and high pH crystallized components in the unprecipitated fermentation liquid in the small bottomed chamber are precipitated and precipitated by increasing the pH in the fermentation liquid adjusting tank. Post-treatment device for methane fermentation liquid. 7. The post-treatment device for methane fermentation solution according to claim 5, wherein an inclined bottom surface is provided in the fermentation solution adjusting tank, and a collection groove for the precipitated crystals is formed at a lower end of the inclined bottom surface. The apparatus according to any one of claims 5 to 7, further comprising a pair of fermented liquid adjusting tanks with the small bottomed chamber, wherein the inflow path of the fermented liquid after the methane fermentation treatment is set in the fermented liquid adjusting tank with the small closed bottomed chamber. A post-treatment device for a methane fermentation solution comprising a switching valve connected to any one of the inlets.