JP5560343B2 - Methane fermentation treatment equipment - Google Patents

Description

  The present invention relates to a methane fermentation treatment apparatus that decomposes industrial wastewater represented by organic wastewater such as food industry, or wastewater such as sewage and human waste into methane gas, carbon dioxide gas, etc. by methane fermentation.

  In order to treat industrial wastewater such as food industry wastewater and organic waste such as organic sludge and garbage, methane fermentation treatment has attracted attention and has been put to practical use. Methane fermentation treatment is energy saving compared to activated sludge treatment, and can produce methane gas as biogas as energy.

  As an example of the methane fermentation treatment, an anaerobic digestion method or a UASB (upward flow type anaerobic sludge bed) method is widely used. In UASB methane fermentation treatment, organic waste is converted into methane gas, water, and carbon dioxide through a two-stage decomposition process. That is, organic waste is decomposed into lower fatty acids such as acetic acid during the acid fermentation process, and then decomposed into methane gas by the action of methane bacteria.

  In such a methane fermentation treatment, a sludge blanket type methane fermentation treatment apparatus as described in Patent Document 1 is known. In this apparatus, a turbulent reaction layer that retains granular granules in a turbulent state is formed by stacking vertically in two or more stages from below in the tank of the reaction tank. A laminar bed (sludge blanket) is provided which overflows outside the tank and returns water containing granules to the turbulent reaction layer.

JP 2005-342691 A

  In the methane fermentation treatment apparatus described in Patent Document 1, the turbulent reaction layers in each stage are connected through a narrow flow path formed outside a conical first partition wall provided in a convex shape upward. ing. And the 1st penetration cylinder 4 which descends the reaction water near the free water surface of the tank center upper part to the 1st turbulent flow layer 201 of the tank bottom, and the water of the 1st turbulent flow layer 201 near the free water surface of the tank center upper part By providing the second through cylinder 6 to be raised, the water in the first turbulent layer 201 circulates through the vicinity of the free water surface at the upper center of the tank. Because of this internal structure of the tank, when the water to be treated moves sequentially from the lower turbulent reaction layer to the upper turbulent reaction layer, it is normally circulated through the vicinity of the free water surface at the upper center of the tank. There is a risk that the water to be treated that should flow evenly in the radial direction will flow in one direction and reduce the reaction efficiency.

  Then, the subject of this invention is providing the methane fermentation processing apparatus with high reaction efficiency in which the flow state of the to-be-processed water in a multistage reaction tank was improved.

  In order to solve the above-mentioned problems, a methane fermentation treatment apparatus according to the present invention comprises a multistage reaction tank in which the inside of the tank is partitioned into a plurality of reaction chambers by partition walls, and water to be treated and granulated in the multistage reaction tank. The partition is provided with an opening through which the treated water passes from the upstream reaction chamber toward the downstream reaction chamber, and the most downstream reaction chamber has An overflow section is provided to discharge the treated water separated from the granular sludge, and guides the gas generated in one reaction chamber below the surface of the water at the same height as the overflow surface of the overflow section. Degassing means for extracting into the air, and sludge returning means for returning the granular sludge guided below the water surface together with the gas to the other reaction chamber downstream from the one reaction chamber by the degassing means. Is it characterized by having It made.

  According to such a methane fermentation treatment apparatus of the present invention, the granular sludge guided below the water surface together with the gas generated in one reaction chamber is returned to the other reaction chamber on the downstream side. A good sludge blanket can be formed by flowing between a plurality of reaction chambers. In addition, the sludge water containing granule sludge flows between adjacent reaction chambers, whereby the inside of the multistage reaction tank is stirred and mixed to prevent a single flow of water to be treated, thereby promoting the methane fermentation reaction.

  In the methane fermentation treatment apparatus of the present invention, it is preferable that the partition wall is formed in a conical surface shape (for example, a conical surface shape or a quadrangular pyramid surface shape) arranged with the top portion facing downward. By forming the partition wall into a so-called inverted conical surface shape, the gas generated in the reaction chamber moves outward in the radial direction of the reaction chamber with the granular sludge floating in the reaction chamber, and is the same as the overflow surface It is discharged into the air from a free surface of height. In this way, the flow state of the granular sludge in the multistage reaction tank is improved.

  The opening is preferably formed at the top. In this way, an opening is formed at the top of the cone of the partition wall having an inverted conical surface shape, and the water to be treated passes through the opening from the upstream reaction chamber toward the downstream reaction chamber. Is formed inside the reaction chamber in the radial direction, so that the laminar flow of water to be treated and the circulating flow of sludge water accompanying the flow of generated gas can form a stable flow state without interfering with each other It becomes.

  In the methane fermentation treatment apparatus of the present invention, it is preferable that the sludge returning means is composed of a downward piping that returns the granular sludge to the other reaction chamber by gravity. Granule sludge guided under the free water surface at the same height as the overflow surface can be returned to a desired position in the reaction chamber of the return destination through the sludge return means comprising such downward piping.

  In the methane fermentation treatment apparatus of the present invention, it is preferable that the degassing means is an upward pipe that guides the gas below the water surface by buoyancy. In this way, gas generated in one reaction chamber is collected, transferred upward by buoyancy, and guided to the free water surface at the same height as the overflow surface, thereby degassing without using special power. be able to. Moreover, since sludge water can be raised using the lift-up action of the rising gas, it is possible to keep the inside of the multistage reaction tank in an appropriate fluid state with a simple mechanism. Moreover, it is preferable that the upward piping is provided on the peripheral side of the one reaction chamber and is arranged so that the generated gas is easily taken in.

  Moreover, it is preferable that the methane fermentation processing apparatus of this invention is provided with the blower which blows gas in the said upward piping or / and reaction chamber. When the methane fermentation reaction is actively occurring, the inside of the multistage reaction tank can be sufficiently agitated to form an appropriate fluid state without blowing gas from the outside. However, when the amount of methane gas generated is small, the flow state can be adjusted by blowing methane gas or the like from the outside into the upward piping or the reaction chamber. Further, it is possible to reduce the particle size by loosening the granular sludge rising in the upward pipe by the gas blown from the outside. By increasing the sludge surface area in this way, it is possible to improve the methane fermentation reactivity of the granular sludge.

  In the methane fermentation treatment apparatus according to the present invention, the plurality of reaction chambers are preferably stacked in the vertical direction. In such a so-called vertical multistage reactor, it is easy to form a compact methane fermentation treatment apparatus equipped with the degassing means and sludge return means of the present invention.

  In the methane fermentation treatment apparatus of the present invention, it is preferable that treated water is intermittently supplied to the multistage reaction tank. By supplying the treated water intermittently, the granular sludge is settled by its own weight when the treated water stops flowing, and the granular sludge flows from the upper reaction chamber to the lower reaction chamber through the opening. Can do. In this way, the granular sludge that has flowed into the lower reaction chamber rides on the gas flow in the lower reaction chamber and is guided to the degassing means, thereby forming a circulating flow of sludge water in the multistage reaction tank. can do.

  In the methane fermentation treatment apparatus of the present invention, it is preferable that a blocking plate for preventing the gas in the upstream reaction chamber from flowing into the downstream reaction chamber is provided in the vicinity of the upstream side of the opening. For example, by providing a floating gas blocking plate having a cross-sectional area larger than the opening in the reaction chamber slightly upstream from the opening, methane gas generated in the upstream reaction chamber flows into the downstream reaction chamber through the opening. And the gas can be effectively guided to the degassing means. Such a levitation gas blocking plate can be configured as a conical surface disposed so as to have an apex on the upper side.

  According to the methane fermentation treatment apparatus according to the present invention, methane fermentation is effectively performed while preventing a single flow in the reaction chamber by forming a circulation flow in the multistage reaction tank using the gas generated in the reaction chamber. It can be carried out. In addition, by introducing a gas such as methane gas from the outside through a blower, the flow of sludge water to be lifted up can be promoted.

It is a schematic longitudinal cross-sectional view of the multistage reaction tank in the methane fermentation processing apparatus which concerns on one embodiment of this invention. It is the schematic plan view which looked at the multistage type reaction tank of Drawing 1 from the LL direction. It is a schematic flowchart of the methane fermentation processing apparatus containing the multistage reaction tank of FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic longitudinal sectional view of a multistage reaction tank in a methane fermentation treatment apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic plan view seen from the LL direction of FIG.

  In the multistage reaction tank 1, three conical surface partition walls 2 (2 </ b> A, 2 </ b> B, 2 </ b> C) with the top facing downward are installed, and the outer peripheral edge of each partition wall 2 is the cylindrical inner periphery of the multistage reaction tank 1. It is joined to the surface in a watertight state, and the inside of the multistage reaction tank 1 is partitioned into reaction chambers 10 (10Z, 10A, 10B, 10C). Moreover, the opening part 3 (3A, 3B, 3C) is formed in the top part of each partition 2, and each reaction chamber 10 is connected by each opening part 3. FIG. Further, a conical floating gas blocking plate 12 is provided in the vicinity of the lower side of the opening 3 and is fixed to each partition wall 2 by a support means (not shown). An inflow portion 8 of the water to be treated is provided at the lowermost portion of the multistage reaction tank 1, and an overflow basin 4 for overflowing the treated water is provided at the uppermost portion of the multistage reaction tank 1. The treated water that has overflowed flows out of the multistage reaction tank 1 through the outflow pipe 9. Furthermore, one end of a gas discharge pipe 11 that discharges methane gas generated in the multistage reaction tank 1 to the outside of the multistage reaction tank 1 is connected to the top of the multistage reaction tank 1.

  One end of the upward pipe 5A is attached to the vicinity of the outer peripheral edge of the partition wall 2A (the upper part on the peripheral side of the reaction chamber 10Z) through the partition wall 2A. The other end of the upward pipe 5A communicates with a degassing tank 7 (7A) formed so that the water surface exists at substantially the same height as the overflow water surface of the multistage reaction tank 1, and in the reaction chamber 10Z. The generated methane gas is guided to the degassing tank 7A by the upward pipe 5A.

  One end of the downward piping 6A communicates with the degassing tank 7A, and the other end of the downward piping 6A is installed along the upper side of the conical surface of the partition wall 2A, and together with methane gas by the gas lift-up effect due to the upward flow of methane gas The rising sludge water is returned to the reaction chamber 10A from the other end of the downward piping 6A through the degassing tank 7A.

  In the vicinity of the outer peripheral edge of the partition wall 2B (upper part on the peripheral edge side of the reaction chamber 10A), one end of the upward pipe 5B is attached through the partition wall 2B. The other end of the upward pipe 5B communicates with a gas vent tank 7B installed on the same horizontal plane as the gas vent tank 7A so that methane gas generated in the reaction chamber 10A is guided to the gas vent tank 7B by the upward pipe 5B. It has become.

  One end of the downward piping 6B is also communicated with the gas venting tank 7B, and the other end of the downward piping 6B is installed along the upper side of the conical surface of the partition wall 2B. The rising sludge water is returned to the reaction chamber 10B from the other end of the downward piping 6B through the gas venting tank 7B.

  In addition, as shown in FIG. 2, each degassing tank 7 (7A, 7B) is installed so that it may adjoin with the uppermost periphery side in the multistage reaction tank 1. As shown in FIG.

  The methane fermentation treatment apparatus of the present invention configured as described above functions as follows.

  The water to be treated flows in intermittently from the inflow portion 8 and moves between the reaction chambers 10 (10Z, 10A, 10B, 10C) through the openings 3 (3A, 3B, 3C) while rising. In this process, when the water to be treated comes into contact with the granular sludge present in each reaction chamber 10, the organic matter in the water to be treated is decomposed. The treated water is finally separated from the granular sludge at the upper part of the reaction chamber 10C and taken out from the outflow pipe 9 to the outside of the multistage reaction tank 1 through the overflow tank 4 as treated water.

  A part of the methane gas generated in the reaction chamber 10Z is captured by the floating gas blocking plate 12 below the opening 3A and is prevented from flowing into the reaction chamber 10A, and is generated in the reaction chamber 10Z including the blocked methane gas. The methane gas rises along the lower side of the conical surface of the partition wall 2 </ b> A and stays around the junction between the partition wall 2 </ b> A and the multistage reaction tank 1. Since one end of the upward pipe 5A is opened in the vicinity of the joint, the methane gas staying around the joint is guided under the water surface of the degassing tank 7A through the upward pipe 5A, and is discharged from the water surface. The methane gas released therein is discharged out of the multistage reaction tank 1 through the gas discharge pipe 11.

  On the other hand, when methane gas passes through the upward pipe 5A, sludge water containing granules present in the reaction chamber 10Z rises due to the lift-up effect and flows into the gas vent tank 7A. As a result, the water level m in the degassing tank 7A is higher than the water level n in the multistage reaction tank 1, but due to the head difference (mn), sludge water falls through the downward piping 6A and flows into the reaction chamber 10A. To do. Thus, a part of the granules in the reaction chamber 10Z is transferred to the reaction chamber 10A. Further, at the timing when the inflow of the water to be treated is intermittently stopped, the granules fall from the reaction chamber 10A and flow into the 10Z against the direction of the water to be treated. By continuing such an operation, circulation and mixing of granular sludge is achieved between the reaction chamber 10Z and the reaction chamber 10A, and the reaction is effectively performed.

  On the other hand, the methane gas generated in the reaction chamber 10A also rises along the lower side of the conical surface of the partition wall 2B and stays around the joint portion between the partition wall 2B and the multistage reaction tank 1, but the joint portion. Since there is an opening of the upward pipe 5B in the vicinity, the methane gas is guided through the upward pipe 5B under the water surface of the degassing tank 7B, and the methane gas released from the water surface into the air passes through the gas discharge pipe 11. Through the multistage reaction tank 1. When methane gas passes through the upward pipe 5B, sludge water containing granules existing in the reaction chamber 10A rises in the same manner and flows into the degassing tank 7B due to the lift-up effect. As a result, similarly, the water level m in the degassing tank 7B rises higher than the water level n in the multistage reaction tank 1, and sludge water falls from the downward piping 6B due to the head difference (mn) and reacts. It flows into the chamber 10B.

  In this way, a part of the granules in the reaction chamber 10A is transferred to the reaction chamber 10B. Further, at the timing when the inflow of the treated water is intermittently stopped, the granule falls from the reaction chamber 10B and flows into the 10A in parallel with the direction of the treated water flow. By continuing such an operation, circulation and mixing of granular sludge is achieved between the reaction chamber 10A and the reaction chamber 10B, and the reaction is effectively performed.

  In this way, the conical surface-like partition wall 2 with the top portion facing downward is formed, the opening portion 3 is provided at the top portion, the gas venting means including the upward pipe 5 is provided, and the gas vent tank 7 and the downward pipe 6 are provided. By providing the sludge return means, it is possible to prevent a single flow in the multistage reaction tank 1 and to sufficiently circulate and mix the granular sludge in the multistage reaction tank 1. Therefore, compared with the conventional methane fermentation treatment apparatus, the treatment effect can be dramatically increased. In other words, in the comparison with the same processing capacity, the processing equipment installation area and installation cost can be greatly reduced compared to the conventional equipment, and in the comparison with the same installation area or equipment size, the processing capacity is greatly increased. It is possible to exert the effect of increasing the number of times.

  FIG. 3 is a schematic flow diagram of the methane fermentation treatment apparatus of the present invention including the methane gas storage tank 12. The other end of the gas discharge pipe 11 communicated with the uppermost part of the multistage reaction tank 1 is connected to a storage tank 12. Further, one end of a gas blowing pipe 13 communicates with the storage tank 12, and the other end is opened directly below the upward pipe 5A in the reaction chamber 10Z, and a blower 14 capable of blowing gas through the gas blowing pipe 13 is provided with the gas blowing pipe. 13 is installed in the middle.

  By connecting the gas blowing pipe 13 having the blower 14 to the storage tank 12, the methane gas stored in the storage tank 12 can be blown into the multistage reaction tank 1 through the gas blowing pipe 13. By blowing such gas, the methane gas rises in the upward pipe 5A at a high flow rate, so that the gas lift-up effect is more prominently generated and the sludge water in the reaction chamber 10Z flows into the gas vent 7A at a high flow rate. Can be made. In this way, stirring and mixing of the granules can be promoted, and the effect of the methane fermentation treatment can be greatly increased. Further, by blowing methane gas from the outside of the multistage reaction tank 1, the granules having a large particle size are loosened by vibrations generated when bubbles of the methane gas are generated, and dispersed into granules having a smaller particle size. The surface area of the granules can be increased and the effect of the methane fermentation treatment can be further increased.

  In FIG. 3, the other end of the gas blowing pipe 13 is opened directly below the upward pipe 5A. However, the present invention is not limited to this, and the gas blowing pipe 13 may be opened at any place in the reaction chamber 10Z or the upward pipe 5A. .

  Further, in FIG. 3, the other end of the gas blowing tube 13 is opened only in the reaction chamber 10Z, but the other end of the gas blowing tube 13 is branched and opened in the reaction chamber 10A, so that the granule The increase in stirring and mixing can be affected more widely.

  The methane fermentation treatment apparatus according to the present invention can be used for treating various organic industrial wastewater, sewage, human waste and other wastewater.

1 Multistage reaction tank 2, 2A, 2B, 2C Bulkhead 3, 3A, 3B, 2C Opening 4 Overflow tank 5, 5A, 5B Upward piping 6, 6A, 6B Downward piping 7, 7A, 7B Degassing tank 8 Inflow Part 9 Outflow pipe 10, 10Z, 10A, 10B, 10C Reaction chamber 11 Gas discharge pipe 12 Floating gas blocking plate

Claims (10)

  A methane fermentation treatment apparatus comprising a multistage reaction tank in which the inside of the tank is partitioned into a plurality of reaction chambers by partition walls, wherein the water to be treated and granular sludge are brought into contact in the multistage reaction tank, There is an opening through which the water to be treated passes from the upstream reaction chamber toward the downstream reaction chamber, and the overflow from the treated water separated from the granular sludge is discharged to the most downstream reaction chamber. A gas venting means for guiding the gas generated in one reaction chamber under the water surface at the same height as the overflow surface of the overflow section and extracting it into the air; together with the gas by the gas venting means, A methane fermentation treatment apparatus, comprising: sludge returning means for returning granule sludge guided below the water surface to another reaction chamber downstream of the one reaction chamber.   The methane fermentation treatment apparatus according to claim 1, wherein the partition wall is formed in a conical surface shape having a top portion directed downward.   The methane fermentation treatment apparatus according to claim 2, wherein the opening is formed at the top.   The methane fermentation treatment apparatus according to any one of claims 1 to 3, wherein the sludge returning means includes a downward pipe that returns the granular sludge to the other reaction chamber by gravity.   The methane fermentation treatment apparatus according to any one of claims 1 to 4, wherein the degassing means includes an upward pipe that guides the gas below the water surface by buoyancy.   The methane fermentation treatment apparatus according to claim 5, wherein the upward pipe is provided on a peripheral side of the one reaction chamber.   The methane fermentation treatment apparatus according to claim 5 or 6, wherein a blower for blowing gas into the upward pipe or / and the reaction chamber is provided.   The methane fermentation treatment apparatus according to any one of claims 1 to 7, wherein the plurality of reaction chambers are stacked in the vertical direction.   The methane fermentation treatment apparatus according to any one of claims 1 to 8, wherein water to be treated is intermittently supplied to the multistage reaction tank.   The methane fermentation according to any one of claims 1 to 9, wherein a blocking plate is provided in the vicinity of the upstream side of the opening to prevent the gas in the upstream reaction chamber from flowing into the downstream reaction chamber. Processing equipment.

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