JP2006055794A - Anaerobic digester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anaerobic digester which can perform sufficient agitation by installing an agitation device, such as a pump, in a tank, and enables easy maintenance. <P>SOLUTION: In the anaerobic digester for treating sewage and waste introduced into an anaerobic digestion tank body 10 by methane fermentation, water passages 19a, 19b connected to a liquid layer 14 is formed in the anaerobic digestion tank body 10 so as to be separated from a gas layer 15, and agitation devices 18a, 18b are installed so as to be freely put in and out of the water passages 19a, 19b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an anaerobic digester for treating sewage and waste by methane fermentation.

  Conventionally, an anaerobic digester that treats sewage and waste by methane fermentation introduces sewage and waste into an anaerobic digester body and decomposes them with microorganisms.

  In order to accelerate the decomposition, it is important to sufficiently stir the sewage and waste introduced into the anaerobic digester body, and it can be divided into several types depending on the stirring method.

  The gas agitation method is a method in which the generated biogas is blown into the tank and agitated, and the mechanical agitation method is agitated with a stirring blade, and the agitation method by the circulation pump is used to extract the liquid in the tank, There are various types, such as circulating and stirring again in the tank with a circulation pump, or by submerging in the liquid in the tank and installing a circulation pump and stirring.

  In this stirring system, a system (Patent Documents 1 and 2) in which a circulation pump is installed in the tank and the liquid is directly stirred is superior from the viewpoint of stirring.

JP 60-168597 A JP-A-52-72880

  However, in the anaerobic digestion tank body, biogas mainly composed of methane produced by fermentation by microorganisms is accumulated, and this is explosive and harmful. There is a problem that maintenance becomes difficult.

  As with the gas agitation method, maintenance is easy if the blower that blows in biogas is outside the tank, but the power cost increases because the blower blows into the body of the anaerobic digester with a deep water depth. In this case, the tank cannot be sufficiently stirred.

  In the method of stirring using a circulation pump installed outside the tank, maintenance of the circulation pump is easy, but sufficient stirring cannot be obtained even if the liquid in the tank is circulated.

  Furthermore, in the mechanical stirring method using the stirring blade, since the stirring blade is installed in the tank through the biogas layer having explosive and harmful properties, maintenance and sealing are troublesome.

  Therefore, in the agitation method in which these power devices are installed outside, the agitation at the bottom of the tank is not sufficient, and thus the problem of sedimentation of sewage and sand mixed in waste in the tank is unavoidable during long-term operation. In fact, an anaerobic digestion tank whose dead space has reached 68% of the tank after 13.5 years of operation has been reported (edited by the Japan Sewerage Association: sewerage facility planning / design guidelines and explanation, p460).

  Furthermore, in the above stirring method, there is a problem that the scum formed by the close contact between the gas such as methane generated by methane fermentation and the suspended matter or microorganisms and floating near the water surface of the anaerobic digester body cannot be removed. .

  An object of the present invention is to provide an anaerobic digester that can perform sufficient stirring by installing a stirring device such as a pump in a tank and that can be easily maintained.

  In order to achieve the above object, the invention of claim 1 is directed to an anaerobic digester for treating sewage and waste introduced into an anaerobic digester main body by methane fermentation, and a gas layer and an anaerobic digester main body. It is an anaerobic digester in which a water channel that is isolated and connected to a liquid layer is formed, and a stirrer is freely inserted and removed through the water channel.

  The invention according to claim 2 is characterized in that an opening is formed in the side surface located in the liquid layer of the anaerobic digester main body, and an inlet / outlet pipe extending upward to the opening, or the upper periphery of the opening and the anaerobic digester main body. The anaerobic digester according to claim 1, wherein the water channel is formed by connecting a cylinder covering the top.

  According to a third aspect of the present invention, the opening is formed near the water surface of the liquid layer, and an opening / closing pipe extending upward is connected to the opening, or a cylinder covering the opening and the upper outer periphery of the anaerobic digester body. The water channel is formed, and a shelf for holding the stirring device is provided on the inner wall of the anaerobic digester body below the opening, and the stirring device for ejecting the water flow upward is inserted from the water channel into the shelf. The anaerobic digester according to claim 2, wherein an inclined plate is attached to the inner wall of the anaerobic digester main body located on the water surface above the installed stirrer.

  According to a fourth aspect of the present invention, the opening is formed in a side wall near the bottom of the anaerobic digester main body, and an inlet / outlet pipe is connected so as to extend from the opening to the surface of the water. It is an anaerobic digester of Claim 2 or 3 installed in the bottom part of a digester tank main body.

  The invention of claim 5 is provided with an inlet / outlet pipe that penetrates the gas layer from the upper part of the anaerobic digester main body and faces the liquid layer to form a water channel, and the stirring device can be freely inserted and removed through the water channel. An anaerobic digester as described.

  The invention according to claim 6 is the anaerobic digestion according to any one of claims 1 to 5, wherein a sand removal pipe is provided so as to penetrate the gas layer from the center of the top of the anaerobic digester body and face the bottom of the digester body. Device.

  The present invention provides an anaerobic digester body with a water channel that is isolated from the gas layer and connected to the water layer, and a stirring device is provided in the water layer through the water channel, so that stirring is good, and maintenance is performed. Since it can be pulled out of the anaerobic digester body through the water channel, there is an advantage that maintenance can be easily performed.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of the present invention. In the figure, reference numeral 10 denotes a vertical cylindrical anaerobic digester body. An inflow pipe 11 for waste water, waste, or the like is connected to the center of the side surface of the anaerobic digester body 10, and an outflow pipe 12 is connected to the opposite side.

  The outflow pipe 12 is attached at a position lower than the water surface w of the anaerobic digester main body 10 and is raised so that the middle is sufficiently higher than the water surface w in the anaerobic digester main body 10, and the start-up pipe 12a. A siphon breaker 13 having an open top surface is provided at the upper end, and an outlet 12b is provided by branching from the rising pipe 12, so that wastewater after methane fermentation is supplied from the outlet 12b to the post-treatment system. It has become.

  From the inflow pipe 11, sewage, waste, etc. introduced into the anaerobic digester main body 10 form a liquid layer 14 of a predetermined height in the digester main body 10, where a methane fermentation treatment is performed, It flows out from the outflow pipe 12. In the anaerobic digestion tank main body 10 above the water surface w of the liquid layer 14, a gas layer 15 is formed and a sealed gas holder 16 is formed. Gas mainly composed of methane produced by fermentation) is collected.

  In the figure, the anaerobic digester body 10 and the gas holder 16 are integrated, but the gas holder 16 may be formed separately and formed so as to fit inside the anaerobic digester body 10.

  The gas holder 16 is provided with an outlet 17 for discharging biogas.

  A bottom stirrer 18a composed of a submersible pump is installed near the bottom side wall of the anaerobic digester main body 10, and the liquid is ejected in a substantially horizontal direction as shown by the arrow in the drawing to create a flow. This flow causes a swirling flow near the bottom of the anaerobic digester body 10.

  Near the installation place of the bottom stirring device 18a, a water channel 19a for taking in and out the bottom stirring device 18a is formed so as to be isolated from the gas layer 15. The water channel 19a for taking in and out is formed with an opening 20a on the side wall of the anaerobic digester main body 10 near the place where the bottom stirring device 18a is installed, and extends through the water surface w from the opening 20a to open and take out a pipe 21a. Are connected and formed.

  A lifting tool and a power cable 22a are connected to the bottom stirring device 18a, and the bottom stirring device 18a is connected to the bottom of the anaerobic digester main body 10 through a water channel 19a formed by an inlet / outlet tube 21a. Or can be taken out of the anaerobic digester body 10.

  An opening 20b is formed near the water surface w on the side wall of the anaerobic digester body 10 on the side opposite to the inlet / outlet pipe 21a of the bottom agitator 18a, and the inlet / outlet pipe 21b is connected to the opening 20b, A water channel 19b for taking in and out the water surface agitator 18b composed of an underwater pump is formed.

  On the inner wall of the anaerobic digester main body 10 below the opening 20b, a shelf 23 for installing the water surface agitating device 18b is formed, and a lifting tool and a power cable 22b are connected to the water surface agitating device 18b.

  The water surface agitator 18b ejects the liquid upward as shown by the arrows in the figure. An inclined plate 24 is provided on the inner surface of the anaerobic digester main body 10 located on the water surface w above the water surface agitator 18b, and the flow discharged upward from the water surface agitator 18b by the inclined plate 24 is horizontal. The scum layer floating on the water surface w as a swirling flow is stirred.

  A sand removal pipe 26 is provided so as to penetrate the gas layer 15 from the center of the top of the anaerobic digester body 10 and face the bottom of the anaerobic digester body 10.

  In the above, sewage, waste, etc. are introduced into the anaerobic digester main body 10 from the inflow pipe 11 to form the liquid layer 14, and the methane fermentation treatment is performed while being stirred by the bottom stirring device 18a and the water surface stirring device 18b. Then, it is discharged from the outflow pipe 12 as appropriate.

  Since these agitators 18a and 18b are directly installed in water, the agitation efficiency is high and the agitator 18b can be installed at any position in the anaerobic digester main body 10. Therefore, it is easy to agitate the scum and the sand accumulated at the bottom. It is.

  Biogas composed of methane gas, carbon dioxide gas, etc., collected in the gas holder 16 of the anaerobic digester body 10 is exhausted from the outlet 17 and used as fuel gas for boilers, gas engines and the like.

  When maintenance of the bottom stirring device 18a and the water surface stirring device 18b is performed over time, the stirring devices 18a and 18b can be pulled up through the water channels 19a and 19b by pulling up the lifting tool and the power cables 22a and 22b, respectively. . At this time, since the water channels 19a and 19b are isolated from the gas layer 15, they can be taken out safely and installed again.

  Further, since the sand accumulated at the bottom of the anaerobic digester main body 10 is accumulated at the center by stirring, it can be easily extracted from the sand removal pipe 26 with a vacuum car or the like.

  During the methane fermentation process, the tops of the inlet / outlet pipes 21a and 21b and the sand removal pipe 26 are closed with a lid, the lid is removed at the time of use, the biogas accumulated in the upper part is exhausted, and the agitators 18a and 18b are pulled up. Or connect or insert a vacuum hose.

  FIG. 2 shows another embodiment of the present invention.

  In the present embodiment, the water channel 19a for taking in and out of the bottom agitator 18a and the water channel 19b for taking in and out the water surface agitator 19b are the cylinder 27 and the anaerobic digester main body 10 provided on the upper outer periphery of the anaerobic digester main body 10. It is formed with a double cylinder formed with the side wall. That is, a conical portion 28 is formed in the lower portion of the cylinder 27, the conical portion 28 is connected to the side wall of the anaerobic digester main body 10, and an opening is formed on the side surface of the anaerobic digester main body 10 located in the conical portion 28. 20a and 20b are formed to form water channels 19a and 19b.

  The openings 20a and 20b are formed in a part of the anaerobic digester body 10, but may be formed all around. In the case of forming the entire circumference, the cylinder 27 and the side wall of the anaerobic digester body 10 (side wall of the gas holder 16) are connected.

  Further, the water channels 19a, 19b may be formed by connecting to the side surface of the anaerobic digester main body 10 in a circular arc shape or a U-shape in cross section instead of the cylinder 23.

  Also in this example, since the water channels 19a and 19b are formed separately from the gas layer 15, the agitators 18a and 18b can be safely taken in and out.

  FIG. 3 shows still another embodiment of the present invention.

  In this example, the water channel 19a for taking in and out of the bottom agitator 18a and the water channel 19b for taking in and out the water surface agitator 18b are not connected to the side wall of the anaerobic digester body 10, but the top of the anaerobic digester body 10 The inlet / outlet pipes 21a and 21b are provided substantially vertically to form the inlet / outlet water channels 19a and 19b, and the stirrers 18a and 18b are taken in and out through the water channels 19a and 19b formed by the inlet / outlet pipes 21a and 21b. It is a thing.

  In this example, the inlet / outlet pipe 21b of the water surface agitator 18b is positioned near the inner wall of the anaerobic digester main body 10, and the shelf 23 is positioned on the center side of the anaerobic digester main body 10 with respect to the inlet / outlet pipe 21b. In addition, although the inclined plate 24 is shown in the drawing so as to be above it, this is for convenience of explanation, and the shelf plate 23 and the inclined plate 24 are arranged in the circumferential direction with respect to the loading / unloading pipe 21. Is provided.

  Accordingly, the water surface agitating device 18b is inserted from the take-in / out pipe 21b, moved in the circumferential direction by the inclined surface 30 of the shelf plate 23, and installed so that the inclined plate 24 is located on the upper portion thereof.

  Further, a shelf 23 is provided so that the water surface agitator 18b is located directly under the inlet / outlet pipe 21b, and a flexible discharge hose (not shown) is attached to the outlet of the water surface agitator 18b. You may comprise so that it may be located in the outer side and the inclination board 24 directly. In this case, the discharge hose floats with a specific gravity of less than 1 so as to approach the inclined plate 24, and at the time of recovery, the discharge hose can be bent and recovered in the inlet / outlet pipe 21b due to its flexibility. To.

  As described above, in the present invention, (1) since a stirrer is installed at the bottom of an anaerobic digester and can be vigorously stirred in a swirling flow, contact efficiency between methane fermentation microorganisms and sewage / waste is good, Good methane fermentation is possible. At that time, in the conventional method, it was difficult to maintain the stirring apparatus without opening the anaerobic digestion tank, but in the present invention, the stirring apparatus can be pulled up from the water channel provided on the side surface of the anaerobic digestion tank. Therefore, maintenance can be performed easily. In the present invention, (2) the scum that is difficult to remove by the conventional method can be vigorously stirred in the swirl flow near the water surface by the combination of the stirrer installed in the anaerobic digester and the inclined plate. Can be easily crushed. Furthermore, as a result of the swirl flow described in (1), sand does not deposit in the majority of the bottom surface of the anaerobic digester, while sand concentrates in a narrow area in the center. Sand can be efficiently extracted through the vertical sand removal pipe installed there without opening the anaerobic digester.

  As described above, according to the present invention, a considerable part of the problems of the conventional anaerobic digester can be solved, and an anaerobic digester that can be efficiently maintained and managed can be provided.

It is a figure which shows one embodiment of this invention. It is a figure which shows other embodiment of this invention. It is a figure which shows other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Anaerobic digester body 14 Liquid layer 15 Gas layer 18a, 18b Stirrer 19a, 19b Water channel

Claims (6)

  In an anaerobic digester that treats wastewater and waste introduced into the anaerobic digester body by methane fermentation, a water channel is formed in the anaerobic digester body that is isolated from the gas layer and connected to the liquid layer, and stirred through the water channel. An anaerobic digester characterized in that the apparatus is provided so that it can be inserted and removed freely.   An opening is formed on the side surface located in the liquid layer of the anaerobic digester main body, and an outlet / inlet pipe extending upward is connected to the opening, or a cylinder covering the opening and the upper outer periphery of the anaerobic digester main body is connected. The anaerobic digester according to claim 1, which forms the water channel.   The opening is formed near the water surface of the liquid layer, and the water channel is formed by connecting an opening / closing pipe extending upward to the opening, or a cylinder covering the opening and the upper outer periphery of the anaerobic digester body, A shelf for holding the stirring device is provided on the inner wall of the anaerobic digester body below the opening, and a stirring device for ejecting a water flow upward is inserted from the water channel and installed on the shelf. The anaerobic digester according to claim 2, wherein an inclined plate is attached to the inner wall of the anaerobic digester body located on the water surface above the agitator.   The opening is formed on a side wall near the bottom of the anaerobic digester body, and a take-in / out pipe is connected to extend from the opening to the surface of the water. Through the take-out / pipe, the submersible pump is connected to the bottom of the anaerobic digester body. The anaerobic digester of Claim 2 or 3 installed in this.   The anaerobic digester according to claim 1, wherein a water channel is formed by providing an inlet / outlet pipe that penetrates the gas layer from the upper part of the anaerobic digester main body and faces the liquid layer, and the stirring device can be freely inserted and removed through the water channel. The anaerobic digester according to any one of claims 1 to 5, wherein a sand removal pipe is provided so as to penetrate the gas layer from the center of the top of the anaerobic digester main body and face the bottom of the anaerobic digester main body.

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