JP2005342691A - Methane fermentation treatment method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the efficiency of treatment while suppressing the increase in the amount of a treatment liquid and to accelerate a treatment speed to realize a high load. <P>SOLUTION: In the sludge blanket type methane fermentation treatment method, turbulent reaction layers for retaining granules in a granular state are formed so as to be vertically stacked by two or more steps inside a reaction tank from the lower part; further, the upper part thereof is provided with a laminar flow layer (sludge blanket) for overflowing water including clarified water in treated water comprising granules upward from the turbulent reaction layer at the lower part from the upper part and also returning the water comprising the granules to the turbulent reaction layer; further, a vertical type first through barrel for a long and slender downflow is provided from a free water surface at the center of the tank over the lowest part of the tank; further, a second through barrel for flowing water including gas from the turbulent reaction layer at the lowest part in the tank to the free water surface at the center of the tank is provided; and the treated waste water is passed in an upward flow in the order of the turbulent reaction layer at the lowest stage in the tank, the turbulent reaction tank at the upper part thereof, and the laminar flow layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  As wastewater treatment such as industrial wastewater such as food industry and organic waste such as organic sludge and garbage, it is energy saving compared to the activated sludge treatment method and newly produces methane gas as biogas as energy Methane fermentation treatment methods have attracted attention and are in practical use.

  An upflow anaerobic sludge bed method called anaerobic digestion or UASB is prevalent in methane fermentation treatment. In the methane fermentation process called the UASB method, the organic matter of organic waste is converted into methane gas, water, and carbon dioxide gas through a two-stage decomposition process. In other words, the organic matter of organic waste is decomposed into lower fatty acids such as acetic acid during the acid fermentation process, and then this fatty acid is decomposed into methane gas by methane bacteria to complete the decomposition of the organic matter in the organic waste. To do.

  The current methane fermentation treatment is mainly the upward flow anaerobic sludge blanket method (UASB method). In this UASB method, anaerobic microorganisms, mainly methanogens, are granulated into granules called self-granulated granules, and raw water is supplied in an upward flow to form a sludge blanket zone in the tank. It is a processing method.

  When the granules are made larger, the surface area becomes smaller. By forming the granules, the solid-liquid separability of the granules can be improved, and a large amount of microorganisms can be held in the tank at a high density.

By the way, such an anaerobic microorganism treatment method by the UASB method has the following problems in the prior art.
(1) When the granules are made larger, the sedimentation property becomes higher and is strongly pressed. As a result, the granules are consolidated in the lower part of the tank, and a dead space is formed.
(2) When granules are made larger, the surface area becomes smaller, the processing speed becomes slower, and a high load cannot be applied.
(3) Although the apparatus is relatively inexpensive, it still costs tens of millions to hundreds of millions of yen on an industrial scale, and it is desirable if this can be made cheaper.

  The present invention solves the following problems from the above.

  The problem to be solved by the present invention is to increase the efficiency of processing while suppressing an increase in the amount of processing liquid. That is, the processing speed is increased and a high load is realized. In addition, it will provide the market with devices that are cheaper than current industrial scale devices.

  In order to solve the above problems, the present invention adopts the following configuration.

  That is. Two or more turbulent reaction layers are formed in the anaerobic tank from the bottom of the tank, and a laminar flow layer as a clarification zone is formed in the upper part of the tank. Raw water is passed from the bottom to the top of the tank. To achieve the UASB method methane fermentation treatment and to solve the above object (problem).

  More specifically, it is a sludge blanket-type methane fermentation treatment method, in which a turbulent reaction layer that retains granular granules in a turbulent state is vertically formed in the reactor tank in two or more stages from below. In addition, the water containing clear water out of the treated water containing granules upward from the lower turbulent reaction layer is overflowed from the upper side to the outside of the tank, and the granules are Water is returned to the turbulent reaction layer, and a vertical first through cylinder is provided for the elongate downward flow from the free water surface at the center of the tank to the bottom of the tank, and the free water surface at the center of the tank is provided. A second through-cylinder for flowing water containing gas from the turbulent reaction layer at the bottom of the tank is provided, and the treatment wastewater is directed upward from the turbulent reaction layer at the bottom of the tank to the turbulent reaction layer above it and then the laminar flow layer. It is characterized by the fact that water is passed by the flow.

  Note that the free water surface at the center of the tank where the upper part of the first through cylinder for the elongate downward flow faces is structurally separated from the free water surface at the uppermost layer of the tank by a partition wall or the like. This partition can be made in the form of separating the inside and outside by a plane square box.

  Further, as a better configuration, in the methane fermentation treatment method according to claim 1, in the turbulent reaction layer above the lowermost turbulent reaction layer, the third penetration is performed so that the treated water is returned from the upper part to the lower part of this layer. A cylinder was provided.

  By doing in this way, mixing with the water of another layer does not occur in each chamber of each layer, and therefore a preferable reaction can be performed without mixing different types of bacteria in each layer.

  In order to better carry out the above method, a gas flow or a water flow is blown upward into the second through cylinder in the above invention.

  Furthermore, in order to implement the said method better, the process waste water which flows in into the tank lower part was made to flow in intermittently.

  Furthermore, in order to carry out the above method even better, a vertical turbulent reaction layer was formed in two to four stages from below, and the raw water was passed upward.

  In addition, the sludge blanket type methane fermentation treatment apparatus for carrying out the above method has a laminar flow layer for separating granules and clarified water at the upper part of the methane fermentation treatment tank, and a vertical type below the laminar flow layer. Two or more layers of turbulent reaction layers, a vertical first through cylinder that returns treated water from the upper center of the tank to the lower part of the tank, and a turbulent reaction layer at the bottom of the tank on the free water surface in the center of the tank A vertical second through-tube that allows water to flow upward, a raw water inflow pipe provided at the bottom of the tank (below the turbulent reaction layer), and treated water provided at the top of the laminar flow tank There is provided an apparatus configured to have an overflow weir that drains to the outside of the tank in an overflow type.

  In particular, this apparatus is designed to form a conical first partition wall protruding upward in the center of the turbulent reaction layer in each vertical stage and a narrow dew outside the first partition wall. It is a tank comprised so that it might have an inverted conical type 2nd partition wall provided in surroundings.

  Further, the device is provided in a vertical penetrating cylinder so as to surround a conical first partition wall provided in a convex shape at the center of the tank and to form a narrow dew on the outside of the first partition wall. And an inverted conical second partition, and a gas blowing pipe for blowing gas downward is provided.

  An increase in the amount of the processing liquid can be suppressed, and an increase in the processing liquid temperature can be suppressed to improve the processing efficiency. Especially in granule blanket type methane fermentation treatment, when organic waste protein is decomposed by methane fermentation treatment, its constituent element nitrogen is accumulated in the anaerobic sludge as ammonia, and the ammonia concentration becomes high as mentioned above. The activity of methanogens that decompose organic matter into methane, carbon dioxide and water is reduced by the toxicity of free ammonia. However, according to the present invention, the movement of waste water and treated water becomes faster than the conventional granule blanket type methane fermentation treatment, ammonia accumulation is reduced, and the adverse effects due to alkalinization are also suppressed. .

  And since there is basically no mixing of water between the first stage turbulent bed, the second stage turbulent bed, and the laminar bed, the growth of different bacteria in each layer is preferably performed.

  In addition, since a high load can be realized by increasing the processing speed, there is an effect that a large amount of processing can be performed with a small apparatus.

  Furthermore, since the processing can be made more efficient and faster, it is possible to provide an apparatus with a high energy recovery rate that is significantly cheaper than the current industrial scale apparatus.

  Hereinafter, the present invention will be described in more detail.

Embodiment 1
FIG. 1 is a diagram showing Embodiment 1 of the present invention. In this figure, 1 is a cylindrical or rectangular tube-shaped methane fermentation tank, and a turbulent reaction layer 2 (lower stage) having the following structure from the lower part of the tank 1. 201, the upper stage 202) are provided in two vertical stages, and the laminar flow layer 3 having the following structure is provided on the turbulent reaction layer 201 in the upper stage of the tank 1.

  Each stage of the two-stage turbulent flow (reaction) layer 2 includes conical first partition walls 2011 and 2012 that are convex upward, and narrow channels 2031 and 2032 outside the first partition walls. It is provided so as to have the inverted conical second partition walls 2012 and 2022 provided so as to form, and is processed in an upward flow from the lower turbulent flow layer 201 to the upper turbulent flow layer 201 through the narrow channel 2031. Water is allowed to flow, and the treated water is allowed to flow from the upper turbulent bed 202 to the laminar bed 3 through the narrow flow path 2032 in an upward flow.

  In addition, in the vicinity of the treated water free water surface in the center of the tank 1, in this example, a flat rectangular box-type partition wall 5 having a partition wall 501 having a flat plate rectangular parallelepiped shape at the center is provided so as to protrude upward from the free water surface. Two independent chambers isolated from the surroundings are formed.

  One of the boxes in each partition wall is provided with a vertically long first circulation flow tube 4 for lowering the reaction water near the free water surface to the lowest part of the tank 1 (first turbulent flow layer 201). At the same time, a vertically long second circulation flow cylinder 6 is provided so that the reaction water at the upper part of the first turbulent flow layer 201 rises to one chamber in the box partition. As a result, the water in the first turbulent layer 201 circulates between one chamber in the box partition and is not mixed with the water in the other layers except for the route to the free water surface outside the box partition. Has been.

  The water in the one chamber in the box partition is higher (lifted up) than the free water surface outside the box partition, because the water containing gas rises from the second flow tube 6, although not shown in the figure. When a gas (and / or water) supply pipe is connected in the second flow tube 6, the free water surface height is further increased.

  And, by supplying such gas or water, the flow rate of raw water and treated water is increased, the contact efficiency between the granule and water having a porous structure is improved, the treatment speed is improved, and high load reaction is realized. it can.

  Further, the other chamber in the box partition wall is separated from the one chamber in the box partition wall and the outside of the box partition wall from the lower surface and the free water surface, and communicates with the second-stage turbulent layer. As a result, the other chamber in the box partition is a dead end, and part of the water circulates between the second turbulent layer.

  A number of raw water inflow (supply) pipes 7 are installed at the same height at the bottom of the tank 1 and are provided with the raw water ejection direction downward.

  8 is a spray pipe for defoaming bubbles on the free water surface at the upper part of the tank. Water drained to the outside from the tank 1 or treated water from the final sedimentation basin that may be further provided in the tank 1 Of clean water is sprayed.

Reference numeral 9 denotes an overflow weir, which is provided to discharge water on the laminar free water surface to the outside of the tank 1 by the overflow method.
Embodiment 2
This example is shown in FIG. 3 and, as can be seen from the figure, a third through cylinder 10 is provided to return the reaction water from the upper free water surface of the second stage turbulent layer 202 to the lower part of the interior of the second stage turbulent layer 202. The other structure is the same as that of the first embodiment.

  According to this example, the mixing of water in the second-stage turbulent layer 202 is promoted, and the reaction by the bacteria in the same layer becomes better.

Tank size: Cylindrical diameter 112mm
Tank height 1520mm
Capacity of tank 15L
The apparatus of embodiment 1 is
Inlet water CODcr ... 10,000mg / L
Inlet water pH: 5.5 to 6.8
Treated water pH: 6.8 to 7.4
Treatment water circulation rate: 50%
Sludge concentration ... 55000mg / L
MLVSS ... 87.0%
I drove under the conditions of

  The result of measuring the relationship between the CODcr removal rate and the TLP type volumetric load in this example is shown in the graph of FIG. As can be seen from this figure, in this embodiment, the decrease in load is remarkably low.

  On the other hand, it can be seen that in the conventional example in which the turbulent flow layer is provided in a single phase (one layer) (substantially parallel three on the left side of the graph), the load decreases rapidly and is large.

  According to the present invention described above, the invention is industrially useful as follows.

  An increase in the amount of the processing liquid can be suppressed, and an increase in the processing liquid temperature can be suppressed to improve the processing efficiency. Especially in granule blanket type methane fermentation treatment, when organic waste protein is decomposed by methane fermentation treatment, its constituent element nitrogen is accumulated in the anaerobic sludge as ammonia, and the ammonia concentration becomes high as mentioned above. The activity of methanogens that decompose organic matter into methane, carbon dioxide and water is reduced by the toxicity of free ammonia. However, according to the present invention, the movement of waste water and treated water becomes faster than the conventional granule blanket type methane fermentation treatment, ammonia accumulation is reduced, and the adverse effects due to alkalinization are suppressed, which is useful.

  And since there is basically no mixing of water between the first stage turbulent bed, the second stage turbulent bed, and the laminar bed, the growth of different bacteria in each layer is preferably performed.

  Moreover, since a high load can be realized by increasing the processing speed, it is also useful in that a large amount of processing can be performed with a small apparatus.

  Furthermore, since the processing can be made more efficient and faster, it is possible to provide an apparatus with a high energy recovery rate that is significantly cheaper than the current industrial scale apparatus.

It is a longitudinal cross-sectional view of the methane fermentation apparatus of Embodiment 1 of this invention. The figure which showed the performance curve at the time of implementation of the methane fermentation apparatus of Example 1. FIG. It is a longitudinal cross-sectional view of the methane fermentation apparatus of Embodiment 2 of this invention.

Explanation of symbols

1: Methane fermentation tank 2: Turbulent layer 201: First turbulent layer
2011: first partition 2012: second partition 202: second turbulent layer 2021: first partition 2022: second partition 2031, 2032: narrow channel 3: laminar flow layer 4: first through cylinder 5: box partition 6 : Second through pipe 7: Raw water supply pipe 8: Spray pipe 9: Overflow weir 10: Third through pipe

Claims (8)

It is a sludge blanket type methane fermentation treatment method, wherein a turbulent reaction layer that retains granular granules in a turbulent state is formed by laminating vertically in two or more stages in the tank of the reaction tank, Furthermore, the water containing clear water out of the treated water containing granules upward from the lower turbulent reaction layer is overflowed to the outside of the tank from above, and the water containing granules is turbulently reacted. In addition, a vertical first through cylinder is provided for the elongate downward flow from the free water surface at the center of the tank to the bottom of the tank, and the turbulent flow at the bottom of the tank on the free water surface at the center of the tank. Provide a second through-cylinder for flowing water containing gas from the reaction layer, and let the treated wastewater flow upward from the turbulent reaction layer at the bottom of the tank to the turbulent reaction layer above it and then the laminar flow layer. A methane fermentation treatment method, characterized in that 2. The methane fermentation treatment method according to claim 1, wherein the turbulent reaction layer above the lowermost turbulent reaction layer is provided with a third through cylinder for returning treated water from the upper part to the lower part of the layer. The methane fermentation treatment method according to claim 1 or 2, wherein a gas flow is blown upward into the second through cylinder. 4. The methane fermentation treatment method according to any one of claims 1 to 3, wherein raw water for treatment to be introduced into the lower portion of the tank is intermittently introduced. The methane fermentation treatment method according to any one of claims 1 to 4, wherein the vertical turbulent reaction layer is formed in two to four stages from below, and waste water is passed in an upward flow. In order to carry out the method invention according to any one of claims 1 to 5, a laminar bed separating granule and clarified water at the upper part of the methane fermentation treatment tank, and a two-stage vertically below the laminar bed The laminated turbulent reaction layer, the vertical through-tube that returns the treated water from the upper center of the tank to the lowermost part of the tank, the waste water inflow pipe provided below the turbulent reaction layer, and the laminar flow layer A methane fermentation treatment apparatus characterized by comprising an overflow weir that overflows treated water provided in the upper part and overflows outside the tank. 7. The turbulent reaction layer in each vertical type according to claim 6, wherein the conical first partition wall provided in a convex shape at the center of the tank and a narrow channel outside the first partition wall are formed. A methane fermentation treatment apparatus, characterized in that it has an inverted conical second partition wall enclosed in a so-called manner. 8. The methane fermentation treatment apparatus according to claim 6 or 7, wherein a gas blowing pipe for blowing gas upward is provided in the second through cylinder.

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