JP4545715B2 - Organic wastewater treatment equipment repair method - Google Patents

Description

The present invention is related to organic wastewater treatment device repair method.

Conventionally, as a method of biologically treating organic wastewater, organic wastewater is introduced into a biological treatment tank that contains activated sludge and activated sludge is discharged from the biological treatment tank, and the discharged activated sludge is separated by precipitation in a sedimentation tank. The method to do is adopted. Water quality such as biochemical oxygen demand (hereinafter also referred to as “BOD”) after this organic wastewater treatment affects the residence time in this biological treatment tank and the concentration of activated sludge in this biological treatment tank. For this reason, when increasing the throughput of the organic waste water treatment device, the retention time in the biological treatment tank is prevented from being shortened by increasing the capacity of the biological treatment tank.
In order to suppress the increase in the capacity of the biological treatment tank, it is possible to make the activated sludge concentration in the biological treatment tank high, but in that case, a high concentration activated sludge is introduced into the subsequent sedimentation tank. As a result, solid-liquid separation problems such as bulking and sludge levitation may occur.
For this reason, in the conventional organic waste water treatment equipment, the biological treatment tank which has a huge volume is provided.

In addition, as a method of increasing the amount of organic wastewater to be treated while suppressing an increase in the capacity of the biological treatment tank as compared with the method using the biological treatment tank and the precipitation tank, activated sludge is added from the biological treatment tank to the precipitation tank. Without introducing it, the activated sludge in the biological treatment tank is separated into a concentrated solution and a permeate by a membrane separator, and this permeate is discharged as treated water to the outside of the system, or a separate process in the subsequent stage is performed. There is also a method. In the method using this membrane separation apparatus, it is possible to make the concentration of activated sludge in the biological treatment tank high, so that the treatment efficiency of organic wastewater treatment can be increased. That is, the amount of organic wastewater treatment that can be treated relative to the capacity of the biological treatment tank can be increased.
However, this method using a membrane separator cannot respond flexibly to fluctuations in the amount of raw water inflow, especially when the amount of raw water inflow into the biological treatment tank exceeds the capacity of the membrane separator. Has the problem of being difficult.

In Patent Document 1, in an organic wastewater treatment method in which activated sludge in a biological treatment tank is subjected to membrane separation by a membrane separation device, when the inflow amount of raw water fluctuates, the fluctuation is introduced from the biological treatment tank to the sedimentation tank. Is described.
However, in this case, as described above, there is a possibility that a solid-liquid separation failure may occur in the settling tank.
That is, the conventional organic wastewater treatment method using a biological treatment tank and a precipitation tank has a problem that it is difficult to improve the treatment efficiency while suppressing the occurrence of a solid-liquid separation failure.

JP-A-10-128375

The present invention has a task to provide an organic waste water treatment device repair method capable of improving the process efficiency while suppressing the solid-liquid separation failure occurs for organic waste water treatment apparatus existing.

The present inventor has found that by forming a plurality of treatment flows in a biological treatment tank, the treatment efficiency can be improved while suppressing the occurrence of solid-liquid separation failure, and the present invention has been completed. It is.
That is, the present invention has a biological treatment tank in which activated sludge is accommodated and a sedimentation tank in which activated sludge in the biological treatment tank is precipitated and separated in order to solve the above-described problems, An organic wastewater introduction part for introducing organic wastewater on one end side, and an activated sludge discharge part for discharging activated sludge to be introduced into the settling tank on the other end side. Renovate existing organic wastewater treatment equipment that can be used to biologically treat organic wastewater by flowing activated sludge from the introduction part to the activated sludge discharge part to improve the treatment capacity of organic wastewater. An organic wastewater treatment device refurbishment method, wherein the organic wastewater introduction part is moved downstream in the flow direction of activated sludge and a membrane separation device for membrane separation of activated sludge into permeate and concentrate is provided, Activated sludge discharge section by introducing organic waste water When the membrane is separated by the membrane separator while discharging activated sludge, the organic wastewater introduced from the organic wastewater introduction part is biologically treated while flowing downstream, and the organic treatment The organic wastewater introduced from the wastewater introduction part moves upstream from the organic wastewater introduction part after the relocation so that a second treatment stream that is biologically treated while moving upstream can be formed in the biological treatment tank. Forming a membrane separation section for membrane separation of the activated sludge on the side with the membrane separation device, and in the second treatment stream, organic wastewater is biologically treated with activated sludge having a higher sludge concentration than the first treatment stream. Accordingly, there is provided an organic wastewater treatment device refurbishing method characterized in that the membrane separation device is provided so that the concentrated liquid after membrane separation can be mixed with the activated sludge of the second treatment stream .

According to the present invention, a first treatment flow in which organic wastewater is biologically treated from the organic wastewater introduction part to the activated sludge discharge part, and an organic wastewater between the organic wastewater introduction part and the membrane separation part. Is formed in the biological treatment tank, and by mixing the concentrated liquid after the membrane separation with the activated sludge of the second treatment stream, in the second treatment stream, Since organic wastewater is biologically treated with activated sludge having a sludge concentration higher than that of the first treatment stream, the first treatment stream introduced into the sedimentation tank has a sludge concentration that does not cause a solid-liquid separation obstacle, As a whole treatment tank, the sludge concentration is improved more than the activated sludge concentration of the first treatment flow introduced into the settling tank, and the treatment efficiency can be improved.
That is, the processing efficiency can be improved while suppressing the occurrence of a solid-liquid separation failure.

Hereinafter, a preferred first embodiment of the present invention will be described with reference to FIG.
The organic waste water treatment apparatus in the present embodiment includes an initial sedimentation tank 1, a biological treatment tank 2, and a final sedimentation tank 3 from the upstream side. The biological treatment tank 2 is provided with a membrane separation device 4 immersed in activated sludge.

  The first settling tank 1 is provided so as to be able to precipitate and remove sand and gravel, dust, and foreign matters contained in organic waste water (raw water), and is not particularly limited, but is inclined in a mortar shape. The bottom part is provided with an initial settling sludge discharge port, and examples thereof include those capable of removing gravel, dust, foreign matters and the like precipitated from the initial settling sludge discharge port.

The biological treatment tank 2 includes a tank main body 21 in which activated sludge is accommodated, an organic wastewater introduction part 22 into which organic wastewater is introduced from the initial sedimentation tank 1, and the activated sludge in the biological treatment tank 2 as described above. An activated sludge discharge part 23 is provided for flowing down to the final sedimentation tank 3 (hereinafter also simply referred to as “sedimentation tank”).
Further, the membrane separation device 4 is provided in the tank body 21 of the biological treatment tank 2 in a state of being immersed in activated sludge, and the activated sludge is membrane-separated at the place where the membrane separation device 4 is installed. The membrane separation unit 24 becomes.

FIG. 2 is a schematic view showing the top surface of the tank body 21, and the top view of the tank body 21 is formed in a substantially rectangular shape. The organic drainage introduction part 22 is formed at a substantially central part in the longitudinal direction of the tank body, and the membrane separation part 24 is formed on one end side of the tank body 21 with the organic drainage introduction part 22 interposed therebetween. The activated sludge discharge part 23 is formed on the other end side.
The position of the organic waste water introduction part 22 for introducing the organic waste water into the tank body 21 is preferably determined by a distribution ratio between a first treatment flow and a second treatment flow described later.

The membrane separation device 4 includes a filtration membrane such as a microfiltration membrane or an ultrafiltration membrane, and a permeate (permeation) that has passed through the filtration membrane after introducing activated sludge into contact with the filtration membrane. Water) and a concentrated liquid whose activated sludge solid content concentration (sludge concentration) is increased by a filtration membrane can be used.
Further, as this membrane separation apparatus, an apparatus configured to introduce activated sludge at its installation location, discharge the permeate through a pipe or the like, and discharge the concentrate at the installation location is used.
The filtration membrane is not particularly limited to a microfiltration membrane or an ultrafiltration membrane as long as it is generally used for separation of solids and water.

  As described above, the membrane separation device 4 is disposed at a position facing the activated sludge discharge unit 23 in the tank body 21 with the organic drainage introduction unit 22 interposed therebetween. Thus, the organic waste water introduction part 22, the activated sludge discharge part 23, and the membrane separation device 4 (membrane separation part 24) are arranged, so that the organic waste water is transferred from the organic waste water introduction part 22 to the tank body. 21, the activated sludge in the biological treatment tank 2 is membrane-separated by the membrane separation device 4 while discharging the activated sludge from the activated sludge discharge portion 23, so that the activated sludge is discharged from the organic drainage introduction portion 22. A first treatment flow A in which organic wastewater is biologically treated while going to the sludge discharge section 23, and a second treatment flow in which organic wastewater is biologically treated between the organic wastewater introduction section 22 and the membrane separation section 24. Separate with process stream B Path of biological treatment to the (process flow) can be formed in a single biological treatment tank 2.

The final sedimentation tank 3 can introduce the activated sludge discharged from the activated sludge discharge part 23 of the biological treatment tank 2 to allow the gravity liquid separation of the supernatant liquid (treated water) and the precipitation component (solid matter). Is used.
In the final sedimentation tank 3, the bottom surface 31 is inclined so that the precipitated components of the introduced activated sludge can be precipitated and discharged, and the precipitated sediment components are drawn out from the final sedimentation tank 3 as the sludge at the bottom. An activated sludge extraction port 32 for removal is provided.
The final sedimentation tank 3 is provided with an overflow weir 33 so that the supernatant can be discharged out of the system.
In addition, instead of the precipitation separation in the final sedimentation tank 3, the treated water and the solid matter may be separated by floating separation.

Further, the organic waste water treatment apparatus of the present embodiment is provided with a sludge return piping section 5 for returning a part of the drawn sludge drawn from the activated sludge drawing port 32 to the biological treatment tank 2 as return sludge. Yes.
The return position of the return sludge in the biological treatment tank 2 is preferably substantially the same location as the organic waste water introduction part 22 or a position closer to the membrane separation part 24 than the organic waste water introduction part 22.

Although not described in detail here, a general liquid transporting means is used for transporting organic waste water and activated sludge between tanks and apparatuses. In addition, if necessary, the supernatant liquid discharged from the final sedimentation tank 3 is further removed by using a membrane separator using a filtration membrane such as a microfiltration membrane or an ultrafiltration membrane. The permeated water may be discharged out of the system.
Moreover, it is also possible to appropriately provide a device used for general wastewater treatment such as a bar screen, a mesh screen, a raw water tank, a water receiving tank, a coagulation tank, and a temperature control mechanism.

Next, an organic wastewater treatment method using such an organic wastewater treatment apparatus will be described.
First, the organic waste water is first introduced into the settling tank 1 to precipitate sand gravel, dust, foreign matters, etc. contained in the original organic waste water (raw water), and removed from the bottom inclined in a mortar shape. . The organic waste water from which the gravel, dust, foreign matters, etc. are removed is introduced into the biological treatment tank 2 from the organic waste water introduction part 22 and the activated sludge in the biological treatment tank 2 is discharged from the activated sludge discharge part 23. The activated sludge is subjected to membrane separation by the membrane separation device 4. Then, the permeated liquid after the membrane separation is discharged out of the biological treatment tank 2, and the concentrated liquid is discharged at the installation location of the membrane separating apparatus and mixed with the surrounding activated sludge.

As a result, the organic wastewater introduced into the biological treatment tank 2 is activated sludge in a ratio between the activated sludge discharged from the activated sludge discharger 23 and the amount of the permeate discharged by the membrane separation. It will be distributed separately in the direction of the discharge part 23 and the direction of the membrane separation part 24.
Then, the first treatment flow A in which organic wastewater is biologically treated from the organic wastewater introduction section 22 to the activated sludge discharge section 23, and the organic wastewater introduction section 22 to the membrane separation section 24. A second treatment stream B in which organic wastewater is biologically treated is formed in the biological treatment tank 2.

Here, as described above, since the first treatment stream A shares the biological treatment of the second treatment stream B and the organic waste water, all the organic waste water introduced into the biological treatment tank 2 is removed. The flow velocity can be reduced compared to the case of biological treatment.
Therefore, although it depends on the operating conditions of the organic wastewater treatment equipment such as the share of the organic wastewater with the second treatment stream B, it is separated in the final sedimentation tank 3 as compared with the case where all the organic wastewater is biologically treated. It is possible to improve the water quality of the supernatant liquid after being applied.

On the other hand, on the second treatment flow B side, the concentrated liquid of the membrane separation device 4 is discharged at the installation location of the membrane separation device 4 and mixed with the surrounding activated sludge as described above. The sludge concentration around 4 is increased by this concentrated liquid, and is made higher than the sludge concentration in the first treatment stream A.
The activated sludge around the membrane separation device 4 is introduced into the membrane separation device 4 again after the concentrate is mixed. The activated sludge around the membrane separation device 4 is used for the operation time of the organic waste water treatment facility. In addition, the concentration increases with the passage of time, and further, a high concentration region in which the sludge concentration is higher than the sludge concentration of the activated sludge discharged from the activated sludge discharge section 23 is expanded around the membrane separation device 4.
Finally, the diffusion of the activated sludge from the high concentration region to the periphery thereof and the movement of the activated sludge in the direction of the membrane separation portion 24 accompanying the second treatment flow balance and the membrane separation portion 24. A high-concentration region centered on is formed and stabilized.
Therefore, the organic wastewater is biologically treated in the second treatment stream B through a region having a higher sludge concentration than the first treatment stream A.

By adopting the organic wastewater treatment method for operating the organic wastewater treatment device in this way, the first increase in the concentration of activated sludge introduced into the final sedimentation tank 3 via the first treatment flow A is suppressed. In the two treatment streams B, the organic waste water is treated through the high concentration region where the activated sludge concentration is maintained at a high level.
Therefore, it is possible to improve the processing efficiency while suppressing the occurrence of a solid-liquid separation failure.
The concentration of activated sludge in the first treatment stream and the second treatment stream is the activated sludge suspended solids concentration (hereinafter also referred to as “MLSS”) in the first treatment stream, and the solid-liquid separation failure in the final sedimentation tank. It is preferable that it is 6000 mg / L or less in the point which can fully suppress this.
On the other hand, the MLSS in the second treatment stream is preferably in the range of 5000 to 20000 mg / L in that the treatment efficiency of the organic waste water and the membrane separation state of the membrane separation device can be maintained in a good state. is there.

Next, a second embodiment will be described with reference to FIG.
In the first embodiment, the case where the membrane separation device 4 provided in the biological treatment tank 2 is used has been described as an example from the viewpoint that the equipment can be made compact. In the second embodiment, the membrane is used. The difference is that the separation device 4 is installed outside the biological treatment tank 2. In the second embodiment, an activated sludge circulation pipe 48 for introducing activated sludge from the biological treatment tank 2 to the separately installed membrane separation apparatus 4, and a concentrated liquid from the membrane separation apparatus 4 to the biological treatment tank 2. A concentrated liquid return piping 49 is provided for returning the liquid. The point that the membrane separation device 4 is configured to discharge the permeate is the same as in the first embodiment.
The activated sludge circulation pipe section 48 and the concentrated liquid return pipe section 49 introduce activated sludge at the same position as the position where the membrane separation apparatus is installed in the first embodiment into the membrane separation apparatus 4, and membrane separation. One end of the concentrated liquid is opened in the biological treatment tank 2 so that the subsequent concentrated liquid can be returned to the same position as the installation position of the membrane separation apparatus in the first embodiment.
As described above, in the second embodiment, the membrane separation unit 24 is formed outside the biological treatment tank 2 unlike the first embodiment. A second treatment flow is formed from the drainage introduction section 22 to the opening of the activated sludge circulation piping section 48, and the concentrate is returned from the concentrated liquid return piping section 49 in the vicinity of the opening of the activated sludge circulation piping section 48. Therefore, the high concentration region formed in the biological treatment tank 2, the state of the second treatment flow B, and the like are substantially the same as those in the first embodiment.
The organic waste water treatment apparatus of the second embodiment also implements the same organic waste water treatment method as the organic waste water treatment apparatus of the first embodiment. This is also the same in that the processing efficiency can be improved while suppressing the occurrence of a solid-liquid separation failure.

In this second embodiment, although the installation space for the membrane separation device is required, the volume of the activated sludge in the biological treatment tank is not reduced by the amount of the membrane separation device installed, and the membrane separation device is biologically treated. The maintainability of the membrane separation apparatus can be improved as compared with the case where it is immersed in the tank.
Therefore, the processing of the organic waste water for maintenance is not interrupted, or even if it is interrupted, it can be interrupted for a short time, and the reduction in processing efficiency can be suppressed.

Next, a third embodiment will be described with reference to FIGS.
The biological treatment tank 2 in the third embodiment is formed in a substantially rectangular shape when viewed from the top like the tank main body of the first embodiment, and the organic drainage introduction part 22 is provided at a substantially central portion in the longitudinal direction of the tank main body. The membrane separation part 24 is formed on one end side in the longitudinal direction, and the activated sludge discharge part 23 is formed on the other end side. In the biological treatment tank 2 in the third embodiment, a partition wall 25 is further formed so as to cross the tank body at a substantially central portion in the longitudinal direction, and is divided into two sections by the partition wall.
And in order to make organic wastewater flow into both these 2 divisions at once, the organic waste_water | drain introduction | transduction part 22 is formed in the position where this partition wall 25 is faced | matched with the wall surface of a biological treatment tank, and the activated sludge discharge | emission part 23 is carried out. The point which forms the 1st process flow to which it directed and the 2nd process flow toward the membrane separation part 24 is the same as that of 1st embodiment.

Moreover, the membrane separation part 24 in this 3rd embodiment can be formed by installing the membrane separation apparatus 4 inside and outside the biological treatment tank 2 similarly to said 1st embodiment or 2nd embodiment, In such a case, the organic wastewater treatment of the first embodiment and the second embodiment also has the effect of making the organic wastewater treatment device compact and the effect of improving the maintainability of the membrane separation device, respectively. It is the same as the device.
Moreover, it can implement similarly to 1st embodiment and 2nd embodiment about the organic waste water treatment method.

  In the third embodiment, by providing the partition wall 25, for example, when the amount of organic wastewater introduced varies, or the activated sludge discharge amount from the activated sludge discharge section 23, and the membrane Even when there is a change in the ratio of the amount of permeate discharged by separation (distribution ratio of organic wastewater between the first treatment stream and the second treatment stream), the second treatment A high-concentration activated sludge on the flow side flows in, causing a solid-liquid separation failure in the sedimentation separation in the final sedimentation tank 3 in the latter stage of the first treatment stream, or a low concentration of the first treatment stream in the second treatment stream It is possible to prevent the activated sludge from flowing in and reducing the activated sludge concentration in the second treatment stream.

In order to suppress the occurrence of the solid-liquid separation failure as described above or to reduce the activated sludge concentration in the second treatment flow, the partition wall 25 is made to have a structure that completely prevents the liquid from flowing, so that the first treatment flow is reduced. And the second process stream are completely separated and more reliable.
However, in that case, a difference occurs in the water level between the first process stream side and the second process stream side. In order to prevent the occurrence of this difference in water level, it is possible to employ a partition wall 25 that can suppress the activated sludge distribution to a certain extent without completely preventing the distribution of the activated sludge and to obtain a distribution state to some extent. For example, it is possible to use one having one or more through holes or a slit structure, or to form a low height so that the upper end of the wall is lower than the water surface of the biological treatment tank, It is also possible to circulate activated sludge by providing a gap on the bottom side of the biological treatment tank.

Furthermore, although the partition wall has been described as an example here, not only a rigid structure such as a wall structure but also a flexible partition such as a rubber sheet can be used for a part or all of the partition wall.
When such a flexible rubber sheet is employed, it is possible to cause bending when a difference in water level occurs between the rubber sheets. That is, it is possible to suppress the difference in the water level while preventing the activated sludge from flowing through the first treatment stream and the second treatment stream.
In the third embodiment, the partition wall that crosses the tank body at the substantially central part of the rectangular tank body as viewed from above has been described as an example. However, the position where the partition is provided is not limited to the substantially central part, and is one end part. It is also possible to dispose to the side or the other end side.

When the partition wall 25 is provided in this way, a decrease in the activated sludge concentration of the second treatment flow is prevented, but a substance that clogs the membrane separation device 4 may be accumulated. Therefore, in particular, when the membrane separation device 4 is immersed in the biological treatment tank, the membrane separation device 4 is clogged by carrying out sludge extraction near the position where the membrane separation device 4 is installed. It is preferable to discharge the substance to be discharged out of the biological treatment tank.
Alternatively, as shown in FIG. 5, a part or all of the extracted sludge from the section where the second treatment flow is formed may be introduced to the section where the first treatment flow is performed.

  Further, as the partitioning direction, not only the direction crossing the rectangle but also the case of arranging along the longitudinal direction as shown in FIGS.

The organic waste water treatment apparatus as described above as the first to third embodiments can be easily formed by modifying existing facilities.
Usually, when a biological treatment tank is used in combination with a sedimentation tank (final sedimentation tank), it has an organic wastewater introduction part for introducing organic wastewater on one end side, and the activated sludge is precipitated on the other end side. It has an activated sludge discharge part that is discharged to be introduced into the tank, and is formed so that the activated sludge can flow down from the organic waste water introduction part to the activated sludge discharge part to perform biological treatment of the organic waste water.

Therefore, while forming the membrane separation part which membrane-separates the activated sludge of this one end side (upstream side in the existing organic wastewater treatment equipment), the organic wastewater introduction part is moved downstream in the existing organic wastewater treatment equipment. Thus, the existing organic wastewater treatment device can be the organic wastewater treatment device of the first embodiment or the second embodiment.
In other words, the existing organic wastewater treatment apparatus can be modified to improve the organic wastewater treatment capacity with a little effort of providing a membrane separator and moving the organic wastewater introduction part.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(Conventional example 1)
A biological treatment tank with a capacity of 40 L and a sedimentation tank with a capacity of 20 L are provided at the subsequent stage of the biological treatment tank, and artificial biological wastewater having a BOD of about 320 mg / L and a suspended matter concentration (SS) of about 150 mg / L is used. In a state where the MLSS of the treatment tank was 2540 mg / L, biological treatment was performed with a treatment water amount of 40 L / day (HRT = 24 hours), and precipitation separation by the precipitation tank was performed.

(Conventional example 2)
Biological treatment and precipitation separation were performed in the same manner as in Conventional Example 1 except that the amount of treated water was changed to 80 L / day (HRT = 12 hours) instead of 40 L / day, and the biological treatment was performed in a state where MLSS was 2240 mg / L.

Example 1
The biological treatment tank of Conventional Example 1 is divided into two 20L compartments, each of which is treated with the same amount of artificial waste water as used in Conventional Example 1, 80L / day (HRT = 12 hours in each compartment) In one section, as in Conventional Examples 1 and 2, precipitation separation was performed using a precipitation tank in the latter stage, and in the other section, membrane separation was performed using a membrane separation apparatus.
At this time, MLSS was 2570 mg / L in the compartment on the side using the sedimentation tank, and MLSS was 6330 mg / L in the compartment on the side using the membrane separator.

(Example 2)
The amount of treated water on the settling tank side and the membrane separation side is 20 L / day and 60 L / day, respectively, MLSS is 2780 mg / L in the section using the settling tank, and MLSS is 8240 mg / L in the section using the membrane separator. Biological treatment, precipitation separation, and membrane separation were performed at a sludge concentration of L.

  Table 1 shows the conditions of each of the conventional examples and examples, and the BOD and suspended solid content (SS) of the obtained treated water (supernatant liquid, permeate).

In addition, although the operating conditions of the biological treatment tank on the sedimentation tank side of Example 1 are the same conditions as those of Conventional Example 2, the amount of water in the sedimentation tank is small, so that solid-liquid separation is good, and as a result Water quality is improving.
Moreover, the quality of the treated water was further improved by keeping the load on the sedimentation tank side of Example 2 low. On the other hand, the membrane separation side obtains good water quality by maintaining high MLSS.
This table also shows that according to the present invention, it is possible to improve the processing efficiency while suppressing the occurrence of a solid-liquid separation failure.

Schematic which shows the organic waste water treatment apparatus of one Embodiment. Schematic which shows the upper surface view of the biological treatment tank of one Embodiment. Schematic which shows the organic waste water treatment apparatus of other embodiment. Schematic which shows the organic waste water treatment apparatus of other embodiment. Schematic which shows the organic waste water treatment apparatus of other embodiment. Schematic which shows the upper surface view of the biological treatment tank of other embodiment.

Explanation of symbols

  2: biological treatment tank, 3: final sedimentation tank, 4: membrane separation device, 21: tank body, 22: organic drainage introduction section, 23: activated sludge discharge section, 24: membrane separation section, 25: partition (partition wall) ), A: first treatment flow, B: second treatment flow

Claims (1)

An organic treatment tank having an activated sludge stored therein and a sedimentation tank in which the activated sludge of the biological treatment tank is precipitated and separated, and the biological treatment tank introduces organic waste water into one end side. It has a wastewater introduction part, and has an activated sludge discharge part that discharges activated sludge to be introduced into the settling tank at the other end, and allows the activated sludge to flow down from the organic wastewater introduction part to the activated sludge discharge part. An organic wastewater treatment device renovation method that improves the treatment capacity of organic wastewater by renovating an existing organic wastewater treatment device that is formed so as to be capable of biological treatment of organic wastewater,
The organic waste water introduction part is moved downstream of the activated sludge in the downstream direction, and a membrane separation device for separating the activated sludge into a permeate and a concentrated liquid is provided, and the organic sludge is discharged by introducing the organic waste water. A first treatment stream in which organic wastewater introduced from the organic wastewater introduction part is biologically treated while flowing downstream when the membrane is separated by the membrane separator while discharging activated sludge from the part, More than the organic waste water introduction part after relocation so that the organic waste water introduced from the organic waste water introduction part can be formed in the biological treatment tank with a second treatment stream that is biologically treated while moving upstream. Forming a membrane separation section for membrane separation of the activated sludge on the upstream side with the membrane separator, and in the second treatment stream, organic wastewater is biologically treated with activated sludge having a higher sludge concentration than the first treatment stream. In order to make the concentrated solution after membrane separation, Organic waste water treatment device repair method characterized by providing the membrane separator as capable of mixing the activated sludge of physical flow.

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