JP6744045B2 - Water treatment equipment - Google Patents

Description

The present invention includes a pretreatment tank, a reaction tank, a treated water collecting section installed in the reaction tank, and a circulating water recovery section for collecting circulating water from the reaction tank and returning the circulating water to the pretreatment tank. A water treatment device provided.

A methane fermentation method is known as a biological treatment of organic wastewater generated from sewage treatment plants, food factories and the like. The methane fermentation method is an anaerobic microbial treatment in which organic matter contained in organic wastewater is decomposed into methane and carbon dioxide by the action of anaerobic microorganisms in the absence of oxygen. In general, since anaerobic treatment has a slow reaction rate and is inefficient, a high-load treatment apparatus such as a UASB (Upflow Anaerobic Sludge Blanket) method or an EGSB (Expanded Granular Sludge Bed) method that holds anaerobic microorganisms at a high concentration is used. It The UASB method is an anaerobic microbial treatment using granule sludge having a good sedimentation property, in which the granule sludge is retained in the reaction tank, and the granule sludge is stirred by the waste water flowing from the lower part of the reaction tank. The wastewater flowing in from the lower part becomes an upward flow, passes through the reaction tank, and is discharged from the upper part as treated water.

Normally, in a reaction tank that holds granulated sludge, a solid-liquid separator is installed in the upper part of the reaction tank, and the granulated sludge is separated from the treated water so that it does not flow out together with the treated water. There is. For example, Patent Document 1 describes a gas-solid separation device for separating treated water, treated gas, and granulated sludge in the upper part of a reaction tank.

JP, 2001-47085, A

In methane fermentation, an acid generation reaction is performed as a pretreatment for methane fermentation. The acid production reaction is a reaction for decomposing high molecular weight organic matter into low molecular weight organic matter, and is carried out in a pretreatment tank different from the reaction tank in which methane fermentation is carried out. Since the organic wastewater, which is the water to be treated, flows into the pretreatment tank, there is a problem that the reaction conditions in the pretreatment tank or the reaction tank become unstable due to fluctuations in the water quality of the organic wastewater. Conventionally, in order to reduce the influence of fluctuations in the water quality of this pretreatment tank, part of the treated water has been returned to the pretreatment tank.

However, when part of the treated water is returned to the pre-treatment tank, the solid-liquid separation device installed in the reaction tank will not only process the treated water discharged but also treat the treated water returned to the pre-treatment tank. Ability is required. Therefore, in the conventional apparatus, there is a problem that the solid-liquid separation apparatus becomes long and the reaction tank becomes long accordingly.
Therefore, an object of the present invention is to reduce the throughput of the solid-liquid separation device and downsize the solid-liquid separation device.

The present inventor, as a result of diligent examination of the above problems, by collecting the circulating water for returning to the pretreatment unit outside the treated water collecting unit, it is possible to reduce the treatment amount in the treated water collecting unit. Found and completed the present invention.
That is, the present invention is the following water treatment device.

The water treatment apparatus of the present invention for solving the above-mentioned problems is a pretreatment tank, a reaction tank, a treated water collecting section for performing solid-liquid separation provided in the reaction tank, and circulating water from the reaction tank. And a circulating water recovery section for returning the circulating water to the pretreatment tank, wherein the opening in the tank of the circulating water recovery section is between the treated water collecting section and the wall surface of the reaction tank. It is characterized by being provided.

Further, the water treatment apparatus of the present invention for solving the above-mentioned problems is a pretreatment tank, a reaction tank, a treated water collecting section for solid-liquid separation provided in the reaction tank, and the pretreatment tank. A flow path connecting the reaction tank, and a circulating water recovery unit that recovers the circulating water from the reaction tank and returns the circulating water to the flow path, and the tank internal opening of the circulating water recovery unit is It is provided between the treated water collecting part and the wall surface of the reaction tank.

According to these water treatment devices, since the circulating water returned to the pretreatment tank or the flow path is collected between the treated water collecting section and the wall surface of the reaction tank, the treatment amount by the treated water collecting section is reduced. be able to. Then, by reducing the treatment amount of the treated water collecting portion, the treated water collecting portion can be downsized, and the reaction tank can be downsized accordingly.

Also, by returning the circulating water to the pretreatment tank or the flow path connecting the pretreatment tank and the reaction tank, the reaction in the pretreatment tank or the reaction tank is stabilized even if the quality of the water to be treated changes. Can be transformed into In addition, when the circulating water is returned to the flow path connecting the pretreatment tank and the reaction tank, the capacity of the pretreatment tank can be reduced.

Furthermore, as one embodiment of the present invention, the opening in the tank has a feature of opening upward.
According to this feature, solids such as granule sludge flowing under the opening in the tank can be prevented from flowing into the opening in the tank, so that the amount of solids flowing out from the reaction tank together with the circulating water is reduced. can do.

Further, as an embodiment of the present invention, there is a feature that the in-tank opening is provided at substantially the height of the water surface.
On the water surface of the reaction tank, the treated gas and the attached granule sludge may float as floating sludge, and if this floating sludge is left unattended, it becomes a solid substance that covers the water surface and becomes an obstacle to the movement of the treated gas. The problem of becoming a thing arises.
By providing the in-tank opening at approximately the height of the water surface, the floating sludge can be collected together with the circulating water and flow into the bottom of the reaction tank through the pretreatment tank.

Furthermore, as one embodiment of the present invention, the opening in the tank is provided with a weir, and the circulating water is recovered by overflow.
According to this feature, on the water surface of the reaction tank, the flow toward the opening in the tank becomes strong, so that the suspended sludge can be easily collected.

Further, one embodiment of the present invention has a feature that the weir is provided on the outer periphery of the treated water collecting part.
According to this feature, since the flow toward the opening in the tank is formed over the entire area of the reaction tank, the suspended sludge can be collected more reliably.

The water treatment apparatus of the present invention for solving the above-mentioned problems, a pretreatment tank, a reaction tank, a treatment water collecting section provided in the reaction tank for performing solid-liquid separation, and the pretreatment tank, In the tank of the circulating water recovery unit, a flow path connecting the reaction tank and a circulating water recovery unit for recovering the circulating water from the reaction tank and returning the circulating water to the pretreatment tank or the flow path are provided. The opening is characterized in that it is provided substantially at the height of the water surface of the wall surface of the reaction tank.

According to this water treatment device, since the circulating water returned to the upstream treatment tank or the flow path is collected from the opening in the tank provided on the wall surface of the reaction tank, the amount of water treated by the treated water collecting unit can be reduced. .. Further, since the in-tank opening is provided at a height substantially above the water surface, the suspended sludge can be collected together with the circulating water.

According to the water treatment device of the present invention, the circulating water is recovered between the treated water collecting part and the wall surface of the reaction tank or from the wall surface of the reaction tank, and the circulating water is reacted with the pre-treatment unit or the pre-treatment tank. Since the liquid is returned to the flow path connecting the tanks, the throughput of the solid-liquid separation device is reduced, and the solid-liquid separation device can be downsized. Furthermore, with the miniaturization of the solid-liquid separation device, the reaction tank can be downsized.

It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 1st Embodiment of this invention. It is a schematic explanatory drawing which shows various shapes of the opening part in a tank of the circulating water recovery part of the water treatment apparatus of this invention. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 2nd Embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 3rd Embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 4th Embodiment of this invention. (A) is a front view and (B) is a plan view of a reaction tank. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 5th Embodiment of this invention. (A) is a front view and (B) is a plan view of a reaction tank. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 6th Embodiment of this invention. (A) is a front view and (B) is a plan view of a reaction tank. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 7th Embodiment of this invention. (A) is a front view and (B) is a plan view of a reaction tank. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 8th Embodiment of this invention. (A) is a front view and (B) is a plan view of a reaction tank. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 9th Embodiment of this invention. It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of the 10th Embodiment of this invention.

The water treatment apparatus of the present invention includes a reaction tank, a pretreatment tank provided in the preceding stage of the reaction tank, a treated water collecting section provided in the reaction tank, and a flow path connecting the pretreatment tank and the reaction tank. And a circulating water recovery unit that recovers the circulating water from the reaction tank and returns the circulating water to the pretreatment tank or the flow path.

The use of the water treatment device of the present invention is not particularly limited as long as it is a device for treating water to be treated by the pretreatment tank and the reaction tank. For example, it can be used for a biological treatment device for biologically treating organic wastewater generated from a sewage treatment plant, a food factory, or the like, or a reaction device using a carrier catalyst or the like.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that this embodiment does not limit the present invention.
[First Embodiment]
FIG. 1 is a schematic explanatory view showing the structure of a water treatment device 1A according to the first embodiment of the present invention.
As shown in FIG. 1, the water treatment apparatus 1A according to the first embodiment of the present invention includes a pretreatment tank 2 and a reaction tank 3.

The water treatment device 1 according to the first embodiment of the present invention is an anaerobic treatment device for anaerobically treating the water W0 to be treated with anaerobic microorganisms. The pretreatment tank 2 is an acid generation tank and the reaction tank 3 is methane. It is a fermenter. Examples of the water W0 to be treated include organic wastewater generated from sewage treatment plants, food factories and the like. In the acid production tank, acid production that mainly produces lower fatty acids from solids or high molecular weight organic substances such as sugars, proteins or oils is performed, and in the methane fermentation tank, methane production that produces methane mainly from lower fatty acids is performed. Done. Both the pretreatment tank 2 and the reaction tank 3 are in an anaerobic state.

(Pre-treatment tank)
The pre-stage treatment tank 2 is a treatment tank for decomposing high molecular weight organic matter and the like contained in the water to be treated W0 into lower fatty acids and the like by microorganisms such as acid-producing bacteria. A pipe L0 for supplying the water W0 to be treated is provided at the upper part of the pretreatment tank 2, and a pipe L1 is provided at the bottom as a flow path connecting the pretreatment tank 2 and the reaction tank 3. There is. The acid generation treated water W1 that has been subjected to the acid generation treatment is supplied to the reaction tank 3 through the pipe L1.

(Reaction tank)
The reaction tank 3 is a reaction tank that holds granule sludge of methanogens, and produces methane from the organic matter whose molecular weight has been lowered in the pretreatment tank 2.
A pipe L1 for supplying the acid generation treated water W1 transferred from the pretreatment tank 2 is connected to the bottom of the reaction tank 3, and the acid generation treated water W1 is supplied to the inside of the reaction tank 3 so as to move upward. A stream is formed. By this upward flow, the acid generation treated water W1 and the granulated sludge are stirred and mixed, and the methane generation reaction is promoted. The methane produced by the methane production reaction is recovered as biogas G from a pipe L5 installed at the upper part of the reaction tank 3.
Further, a treated water collecting part 4 for separating the granulated sludge and the treated water W2 is installed above the reaction tank 3.

(Treatment water collection part)
The treated water collecting part of the present invention may be configured to include a tubular body installed higher than the water surface of the reaction tank, and a blocking member for blocking the upward flow at the bottom of the bottom opening of the tubular body. As long as it has any shape.
For example, in the treated water collection part 4 of the first embodiment, as shown in FIG. 1, a tubular body whose cross-sectional area decreases toward the lower side and a lower portion of the bottom opening of the tubular body are arranged with a gap therebetween. It is configured by a plate member having a mountain-shaped cross section.

In addition, a trough-like treated water outlet 5 that opens upward is installed near the water surface inside the tubular body. The treated water outlet 5 serves to discharge the treated water W2 out of the reaction tank. The pipe L2 is connected.

The pipe L2 is provided with a flow rate adjusting member such as a valve to adjust the flow rate of the treated water W2 discharged from the pipe L2. The flow rate of the treated water W2 is appropriately set in consideration of the water quality of the treated water W0, the water quality of the treated water W2, the methane production efficiency in the reaction tank 3, the residence time of the treated water W0 in the reaction tank 3, and the like.

When the treated water W2 is discharged from the pipe L2, the treated water W2 flows in through the bottom opening of the tubular body of the treated water collecting portion 4. On the other hand, the granulated sludge having a large specific gravity does not flow from the bottom opening of the cylindrical body, but rolls on the plate member arranged in the lower part and settles to the bottom part of the reaction tank 3.

(Circulating water recovery unit)
The water treatment apparatus of the present invention includes a circulating water recovery unit 6 for recovering the circulating water W3 from the reaction tank and returning the circulating water W3 to the pretreatment tank 2. The circulating water recovery unit 6 of the first embodiment is composed of a pipe L3 having an in-tank opening 6a provided between the wall surface of the reaction tank 3 and the cylindrical body of the treated water collecting section 4.
By providing the circulating water recovery unit 6, since the circulating water W3 is recovered from the in-tank opening 6a installed outside the tubular body of the treated water collecting unit 4, the treated water W2 from the conventional return path L4 is The return can be stopped or reduced. Therefore, it is possible to reduce the treatment capacity of the treated water collecting part 4 and the treated water outflow part 5, and to reduce the size of these components.

The opening in the tank of the circulating water recovery unit may be installed at any position as long as it is outside the tubular body of the treated water collecting unit. For example, as in the first embodiment, it may be installed on the wall surface of the reaction tank 3. In addition to the configuration of penetrating the pipe L3 and installing the in-tank opening 6a between the wall surface of the reaction tank 3 and the cylindrical body of the treated water collecting portion 4, the pipe L3 is joined to the wall surface of the reaction tank 3 to form a wall surface. There may be mentioned a configuration in which an opening in the tank is installed. Moreover, you may install the opening part in a tank in multiple places.
When the circulating water W3 is collected from the opening in the tank, the water in the reaction tank 3 flows toward the opening in the tank. Therefore, when the opening in the tank is formed on a part of the wall surface of the reaction tank, Is uneven in the direction of upward flow near and far from the opening in the tank, and there is a risk that the uniformity of granule sludge may deteriorate during agitation. Therefore, from the viewpoint of forming a good upward flow with a small deviation, it is preferable to install the in-tank opening in a well-balanced manner between the wall surface of the reaction tank 3 and the treated water collecting section 4.

When the in-tank opening is installed between the wall surface of the reaction tank 3 and the treated water collecting portion 4, the in-tank opening is preferably opened upward. By opening upward, the outflow of solids such as granule sludge can be reduced.

Further, the in-tank opening is preferably installed in the upper part of the reaction tank, and particularly preferably installed at substantially the height of the water surface in the reaction tank. By installing in the upper part of the reaction tank, the outflow of granule sludge can be reduced. In addition, the generated processing gas may remain attached to the granulated sludge without being separated, and may float to the water surface in the reaction tank. If the floating sludge that has floated to the water surface is left as it is, it becomes a solid substance that is dried and covers the water surface, which causes a problem that it becomes an obstacle to the movement of the processing gas. Therefore, by installing the opening in the tank at the height of the water surface in the reaction tank, the floating sludge can be collected together with the circulating water W3 and returned to the bottom of the reaction tank 3 via the pretreatment tank 2.

Moreover, it is preferable that the opening in the tank is provided with a weir and the circulating water is collected by overflow. When the circulating water is collected by the overflow, the water flow on the water surface strongly flows toward the opening in the tank, so that the floating sludge floating on the water surface can be collected more quickly.

FIG. 2 illustrates the shape of the opening in the tank. FIG. 2A is an example in which the pipe L3 is joined to the wall surface of the reaction tank 3 and the opening 60 in the tank is installed on the wall surface. According to this configuration, since the structure is a simple structure, when the circulating water recovery unit 6 is attached to the reaction tank, it can be attached by a simple process.

2B to 2D, the pipe L3 is penetrated through the wall surface of the reaction tank 3 and the tank opening 60 is provided between the wall surface of the reaction tank 3 and the cylindrical body of the treated water collecting portion 4. Here is an example. The left figure is a perspective view of the in-tank opening 60, and the right figure is a side view of the in-tank opening 60 installed inside the reaction tank 3. By installing the in-tank opening 60 between the wall surface of the reaction tank 3 and the tubular body of the treated water collecting portion 4, it is possible to form an upward flow with a small deviation in forming the upward flow in the tank. it can.

The in-tank opening 60 illustrated in FIG. 2B has a shape obtained by cutting the pipe L3 in the vertical direction. Since this shape is a simple structure, the in-tank opening 60 can be formed in the pipe L3 by simple processing.

The in-tank opening 60 shown in FIG. 2C has a shape obtained by cutting the pipe L3 in the inclined direction, and the in-tank opening 60 is installed so as to face upward. According to this shape, since the circulating water W3 is collected from the upward direction of the opening 60 in the tank, solids such as granule sludge flowing under the reaction tank 3 are sucked up together with the circulating water W3 and flow out. Can be suppressed.

The in-tank opening 60 shown in FIG. 2D is a funnel-shaped in-tank opening 60 attached to the pipe L3 so as to open upward. According to this shape, as in the case of FIG. 2C, the outflow of solids such as granulated sludge can be reduced, and further, when it is installed at a height of approximately the water surface, it can function as a weir. .. Here, the weir has a structure in which the inside of the in-tank opening 60 is not submerged in water, but flows from the water surface into the inside of the in-tank opening 60 like a waterfall.

[Second Embodiment]
FIG. 3 is a schematic explanatory view showing the structure of the water treatment device 1B according to the second embodiment of the present invention.
In the water treatment device 1B of the second embodiment, two in-tank openings 6b are provided between the wall surface of the reaction tank 3 and the tubular body of the treated water collecting portion 4.
The in-tank opening 6b has a funnel-like shape and is open upward.

If there is one in-tank opening, an upward flow flows toward one in-tank opening, so that an upward flow that flows in an oblique direction occurs. When such an upward flow bias occurs, the uniformity of the granulated sludge in the agitated state deteriorates.
On the other hand, by providing the plurality of in-tank openings 6b as in the second embodiment, the upward flow is distributed and flows into the plurality of in-tank openings 6b, so that the deviation of the upward flow is reduced and the granulation is reduced. It is possible to improve the uniformity of the stirring condition of the sludge.

In addition, since the in-tank opening 6b is opened upward, when collecting the circulating water W3, it is possible to suck up the flowing granule sludge in the lower part of the in-tank opening 6b. To prevent.

[Third Embodiment]
FIG. 4 is a schematic explanatory view showing the structure of a water treatment device 1C according to the third embodiment of the present invention.
The water treatment device 1C according to the third embodiment has a configuration in which the in-tank opening 6c is provided at the height of the water surface of the wall surface of the reaction tank 3.
In this embodiment, the floating sludge floating on the water surface can be collected together with the circulating water W3 and returned to the pretreatment tank 2.

[Fourth Embodiment]
FIG. 5: is a schematic explanatory drawing which shows the structure of the water treatment apparatus 1D of the 4th Embodiment of this invention.
In the water treatment device 1D of the fourth embodiment, as in the second embodiment, two tank internal openings 6d are provided between the wall surface of the reaction tank 3 and the tubular body of the treated water collecting portion 4, and further, The in-tank opening 6d has a weir 7a.
In this embodiment, as in the second embodiment, since there are a plurality of in-tank openings 6d, the upward flow deviation is small, and the uniformity of the agitation state of the granule sludge can be enhanced.

Further, the in-tank opening 6d is provided with a weir 7a, and the circulating water W3 is recovered by flowing over the weir 7a. When the circulating water W3 is collected by the overflow, a strong flow is generated toward the in-tank opening 6d on the water surface, so that the floating sludge can be quickly collected.

[Fifth Embodiment]
FIG. 6 is a schematic explanatory view showing the structure of the water treatment device 1E according to the fifth embodiment of the present invention.
The water treatment device 1E of the fifth embodiment has a configuration including an in-tank opening 6e formed along the wall surface of the reaction tank 3. The in-tank opening 6e has a weir 7b.

According to the in-tank opening 6e, the circulating water W3 is collected all around the inner surface of the reaction tank 3, so that the floating sludge can be quickly collected.
Further, in this embodiment, since the upward flow flows toward the entire circumference of the inner surface of the reaction tank 3, the deviation of the upward flow is small and the uniformity of the stirring state of the granule sludge can be enhanced.
The in-tank opening 6e may be provided in a part of the inner surface of the reaction tank 3 or in a plurality of places.

[Sixth Embodiment]
FIG. 7: is a schematic explanatory drawing which shows the structure of the water treatment apparatus 1F of the 6th Embodiment of this invention.
The water treatment device 1F of the sixth embodiment is configured to include an in-tank opening 6f formed along the outer peripheral surface of the treated water collecting portion 4. Further, the in-tank opening 6f is configured to include a weir 7c.

According to the in-tank opening 6f, the circulating water W3 is collected all around the outer peripheral surface of the treated water collecting part 4, so that the floating sludge can be quickly collected.
Moreover, since the width of the weir 7c is shorter than the width of the weir 7b of the in-tank opening 6e in the fifth embodiment, the overflow amount of the circulating water W3 per width of the weir becomes large. Therefore, according to the in-tank opening 6f of the sixth embodiment, it is possible to collect the suspended sludge more quickly than in the in-tank opening 6e of the fifth embodiment.
Further, in this embodiment, since the upward flow flows toward the entire outer circumference of the treated water collecting section 4 installed in the substantially center of the reaction tank 3, the deviation of the upward flow is small and the granule sludge The uniformity of the stirring state can be improved.
The in-tank opening 6f may be provided at a part or a plurality of locations on the outer peripheral surface of the treated water collecting portion 4.

[Seventh Embodiment]
FIG. 8: is a schematic explanatory drawing which shows the structure of the water treatment apparatus 1G of the 7th Embodiment of this invention.
In the water treatment apparatus 1G of the seventh embodiment, the water treatment apparatus 1F of the sixth embodiment is further provided with two tank internal openings 6g inside the tubular body of the treated water collecting section 4. is there. In addition, the in-tank opening 6g has a weir 7d.

Floating sludge may rarely occur inside the tubular body of the treated water collecting portion 4, and the in-tank opening 6g collects the floating sludge generated inside the tubular body of the treated water collecting portion 4. This is a configuration for.
However, since the amount of the treated water W2 flowing into the tubular body of the treated water collecting portion 4 increases as the overflow amount in the tank opening 6g increases, the tubular body of the treated water collecting portion 4 is enlarged and separated. There is also an adverse effect that it is necessary to maintain performance. In view of such circumstances, the width of the weir of the in-tank opening installed outside the treated water collecting part 4 is smaller than that of the weir of the in-tank opening installed inside the treated water collecting part 4. The width ratio (width of inner weir/width of outer weir) is preferably 1/2 or less, more preferably 1/5 or less, and particularly preferably 1/10 or less.

[Eighth Embodiment]
FIG. 9: is a schematic explanatory drawing which shows the structure of the water treatment apparatus 1H of the 8th Embodiment of this invention.
In the water treatment device 1H according to the eighth embodiment, the water treatment device 1F according to the sixth embodiment further includes an in-tank opening 6h formed along the inner circumference of the tubular body of the treated water collecting portion 4. It is a configuration provided. Further, the in-tank opening 6h is configured to include a weir 7e.
According to this embodiment, since the in-tank opening 6h is formed on the entire inner wall of the tubular body of the treated water collecting portion 4, the suspended sludge generated inside the tubular body of the treated water collecting portion 4 can be quickly removed. Can be recovered.
The in-tank opening 6h may be provided at a part of or a plurality of locations on the inner wall of the tubular body of the treated water collecting section 4.

[Ninth Embodiment]
FIG. 10: is a schematic explanatory drawing which shows the structure of the water treatment apparatus 1I of the 9th Embodiment of this invention.
In the water treatment apparatus 1I of the ninth embodiment, the water treatment apparatus 1A of the first embodiment is further provided with a pipe L6 for returning the circulating water W4 recovered from the previous reaction tank 3 to the pipe L1. Is. In the ninth practical mode, the pipe L6 is formed independently of the pipe L3 that returns the circulating water W3 to the pretreatment tank 2, but it may be branched from the pipe L3.

The pipe L6 is provided with a pump or the like, and the flow rate of the circulating water W4 can be adjusted. Further, the means for sending the circulating water W4 to the pipe L6 may use gravity in addition to the power of a pump or the like, and the flow rate adjusting means may use a valve or the like.

According to the pipe L6, the circulating water W4 is supplied to the pipe L1 to supply the acid generation treated water supplied to the reaction tank 3 when the concentration of the acid generation treated water W1 discharged from the pretreatment tank 2 is high. The concentration of W1 can be adjusted. Therefore, the concentration of the acid generation treated water W1 flowing into the reaction tank 3 can be stabilized.

[Tenth Embodiment]
FIG. 11: is a schematic explanatory drawing which shows the structure of the water treatment apparatus 1J of the 10th Embodiment of this invention.
In the water treatment device 1J of the tenth embodiment, as the circulating water recovery part 6, only the pipe L6 for returning the circulating water W4 recovered from the previous reaction tank 3 to the pipe L1 is provided. According to this water treatment device 1J, the reaction in the reaction tank 3 can be stabilized with a simple structure.

INDUSTRIAL APPLICABILITY The water treatment device of the present invention can be used as a biological treatment device for biologically treating organic wastewater generated from a sewage treatment plant, a food factory, or the like, or a reaction device using a carrier catalyst or the like. In the reaction tank that holds the granulated sludge, a high treatment capacity is required for the treated water collecting portion, so that the effect of the present invention that the load on the treated water collecting portion is reduced can be more exerted.

1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J... Water treatment device, 2... Pretreatment tank, 3... Reaction tank, 4... Treated water collecting section, 5... Treated water outflow section, 6... Circulating water recovery part, 60, 6a, 6b, 6c, 6d, 6e, 7f, 6g, 6h... Tank opening part, 7a, 7b, 7c, 7d, 7e... Weir, L1, L2, L3, L4 L5, L6... Piping, W0... Treated water, W1... Acid generating treated water, W2... Treated water, W3, W4... Circulating water, G... Biogas, P... Pump

Claims (5)

A pretreatment tank,
A reaction tank,
A treated water collecting part which is provided in the reaction tank and performs solid-liquid separation,
A flow path connecting the pretreatment tank and the reaction tank,
The circulating water is recovered from the reaction tank, and the circulating water is provided with a circulating water recovery unit for returning the circulating water to the pretreatment tank or the flow path .
The tank internal opening of the circulating water recovery unit is provided between the treated water collecting unit and the wall surface of the reaction tank,
The water treatment device, wherein the opening in the tank is provided with a weir, and the circulating water is recovered by overflow . A pretreatment tank,
A reaction tank,
A treated water collecting part which is provided in the reaction tank and performs solid-liquid separation,
A flow path connecting the pretreatment tank and the reaction tank,
The circulating water is recovered from the reaction tank, and the circulating water is provided with a circulating water recovery unit for returning the circulating water to the pretreatment tank or the flow path .
The tank internal opening of the circulating water recovery unit is provided between the treated water collecting unit and the wall surface of the reaction tank,
The opening in the tank is equipped with a weir, and the circulating water is collected by overflow.
The water treatment device, wherein the weir is provided along the entire circumference or a part of the outer peripheral surface of the treated water collecting part, or along the whole circumference or a part of the inner surface of the reaction tank . A pretreatment tank,
A reaction tank,
A treated water collecting part which is provided in the reaction tank and performs solid-liquid separation,
A flow path connecting the pretreatment tank and the reaction tank,
The circulating water is recovered from the reaction tank, and the circulating water is provided with a circulating water recovery unit for returning the circulating water to the pretreatment tank or the flow path .
The opening in the tank of the circulating water recovery unit is provided along the entire circumference or a part of the outer peripheral surface of the treated water collecting section, or along the entire circumference or a part of the inner surface of the reaction tank . Water treatment device characterized by. It said tank opening, the water treatment apparatus according to any one of claims 1-3, characterized in that open upward. It said tank opening, the water treatment apparatus according to any one of claims 1 to 4, characterized in that provided in the height of the substantially water.

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