JP7598622B2 - Wastewater treatment equipment - Google Patents

Description

This specification relates to wastewater treatment using membranes.

Conventionally, membrane separation devices having various membranes such as flat membranes and hollow fiber membranes have been used in wastewater treatment. For example, Patent Document 1 proposes the following technology. The membrane separation device is placed in an activated sludge treatment tank. A water collection pipe is connected to the membrane separation device, and a suction pump is connected to the water collection pipe. Treated water is drawn from the membrane separation device by the suction pump.

JP 2002-18466 A

The membrane separation device separates water from solids. Therefore, solids do not normally flow into the suction tube used to suck up the water filtered by the membrane separation device. However, in reality, solids can be present in the suction tube due to various reasons. For example, solids can unintentionally enter the suction tube during the manufacture of the wastewater treatment device. If the membrane is damaged, solids that pass through the membrane can reach the suction tube. Solutes such as calcium contained in the filtered water can precipitate in the suction tube. Organic matter contained in the filtered water can cause a biofilm to form in the suction tube. However, in reality, there has been a lack of sufficient ingenuity in terms of cleaning the suction tube.

This specification discloses a technique for cleaning suction tubes.

The technology disclosed in this specification can be realized as the following application examples:

[Application Example 1]
A wastewater treatment device, comprising:
An exterior wall forming an outer surface;
One or more water treatment tanks including a membrane treatment tank provided in an equipment space that is a space surrounded by the outer wall;
A membrane separation device disposed in the membrane treatment tank and having a membrane for filtering water;
a suction pipe connected to the membrane separation device and disposed within the device space, for suctioning water filtered by the membrane separation device from the membrane separation device;
a washing pipe having an opening, connected to the suction pipe and disposed within the device space, for moving water containing solids in the suction pipe out of the suction pipe;
a valve provided on a flow path of the cleaning pipe;
A wastewater treatment device comprising:

With this configuration, by opening the valve, water containing solids can be moved from inside the suction tube through the cleaning tube to the outside of the suction tube, making it easy to clean the suction tube. In addition, by closing the valve, foreign matter can be prevented from entering the suction tube through the opening of the cleaning tube.

[Application Example 2]
The wastewater treatment device according to Application Example 1,
The opening of the cleaning pipe is disposed at a position higher than the water surface at the horizontal position of the opening.
Wastewater treatment equipment.

With this configuration, the operator can easily observe the water flowing out from the opening of the cleaning pipe. In addition, by observing the water flowing out from the opening of the cleaning pipe, the operator can easily check the cleaning status of the suction pipe.

[Application Example 3]
The wastewater treatment device according to Application Example 2,
The opening of the cleaning pipe is disposed in the membrane treatment tank or in a water treatment tank upstream of the membrane treatment tank among the one or more water treatment tanks.
Wastewater treatment equipment.

This configuration prevents water flowing out from the opening of the cleaning pipe from flowing into the water treatment tank downstream of the membrane treatment tank.

[Application Example 4]
The wastewater treatment device according to any one of Application Examples 1 to 3,
The valve is a manual valve.
Wastewater treatment equipment.

With this configuration, the operator can easily open and close the communication between the suction tube and the opening of the irrigation tube by operating the manual valve.

[Application Example 5]
The wastewater treatment device according to any one of Application Examples 1 to 4,
the opening of the irrigation tube is located at a position higher than the highest portion of the interior region of the suction tube;
Wastewater treatment equipment.

With this configuration, water containing low-density solids can be easily moved from inside the suction tube to outside the suction tube through the cleaning tube, making it easy to clean the suction tube.

[Application Example 6]
The wastewater treatment device according to any one of Application Examples 1 to 5,
the irrigation tube is connected to a portion of the suction tube that forms the highest portion of the interior region of the suction tube;
Wastewater treatment equipment.

With this configuration, water containing low-density solids can be easily moved from inside the suction tube to outside the suction tube through the cleaning tube, making it easy to clean the suction tube.

[Application Example 7]
The wastewater treatment device according to any one of Application Examples 1 to 5,
The suction tube is
a first portion forming a highest portion of an interior area of the suction tube;
A second portion is connected to the first portion on the opposite side to the membrane separation device side and forms an internal region located at a lower position than the highest portion of the internal region of the first portion;
Including,
the irrigation tube is connected to the second portion of the suction tube;
Wastewater treatment equipment.

With this configuration, water containing solids that have settled in the second portion can easily move out of the suction tube through the cleaning tube, making it easy to clean the suction tube.

[Application Example 8]
The wastewater treatment device according to any one of Application Examples 1 to 7,
The membrane treatment tank includes N membrane separation devices (N is an integer of 2 or more),
The suction tube is
N first tubes respectively connected to the N membrane separation devices;
A second tube connected to the N first tubes;
Including,
The flushing pipe is connected to the second pipe.
Wastewater treatment equipment.

This configuration allows the suction tube to be properly cleaned when N membrane separation devices are used.

[Application Example 9]
The wastewater treatment device according to Application Example 8,
a height of a highest portion of the inner region of the second tube is lower than any of N heights of N highest portions of the N inner regions of the N first tubes;
Wastewater treatment equipment.

With this configuration, when the suction pump and the second pipe are connected via a pipe, the degree of freedom of the suction pump's position can be improved without reducing the slope of the pipe.

[Application Example 10]
A wastewater treatment device according to any one of Application Examples 1 to 9;
A suction pump;
an outer pipe that connects the suction pipe and the suction pump;
A wastewater treatment system comprising:

With this configuration, the suction pump can suck water from the membrane separation device through the suction tube and the outer tube, and the cleaning tube can be used to clean the suction tube.

The technology disclosed in this specification can be realized in various forms, for example, as a wastewater treatment method and wastewater treatment device, a wastewater treatment system including a wastewater treatment device and a suction pump, a method for cleaning a suction pipe, etc.

1 is a schematic diagram showing a wastewater treatment device as an embodiment; FIG. 1 is a schematic diagram of a membrane separation tank 140 viewed downward. 1 is a schematic diagram of a membrane separation tank 140 as viewed in a body direction Db. 1 is a schematic diagram of a portion of a membrane separation tank 140 as viewed in a body direction Db. FIG. 1 is a schematic diagram illustrating an example of a wastewater treatment system 1000. 13 is a flowchart showing an example of a cleaning process for the aspirating tube 800. 13A and 13B are flow charts showing another embodiment of the cleaning process for the aspirating tube 800. FIG. 4 is a schematic diagram showing another embodiment of the wastewater treatment device.

A. First embodiment:
A1. Device configuration:
FIG. 1 is a schematic diagram showing a wastewater treatment device as an embodiment. In the figure, a wastewater treatment device 100 is shown as seen from the side. The wastewater treatment device 100 of this embodiment performs purification treatment of wastewater (also called raw water) from a general household or the like (such a device is also called a "septic tank"). The wastewater treatment device 100 has an outer wall 190 that forms an outer surface 190s of the wastewater treatment device 100. In this embodiment, the outer wall 190 forms a substantially cylindrical body 190b extending in a horizontal direction Db (the body 190b extending in one direction is also called a pipe body). Hereinafter, the direction Db in which the body 190b extends is also called the body direction Db. In FIG. 1, the body direction Db is the left direction.

The outer wall 190 forms an equipment space 190d, which is a space surrounded by the outer wall 190. The equipment space 190d is the internal space of the body 190b. In the equipment space 190d, an aeration screen 110, a flow rate adjustment tank 120, a denitrification tank 130, a membrane separation tank 140, a disinfection tank 150, and a discharge pump tank 160 are provided in this order from the upstream side (the left side of FIG. 1). Two adjacent tanks are separated by a partition wall. Wastewater that flows into the wastewater treatment device 100 is treated by these water treatment tanks 110-160 in this order.

Wastewater that flows into the wastewater treatment device 100 flows into the aeration screen 110. The aeration screen 110 is equipped with a screen 111 that has an aeration device, and removes large solids. Water that passes through the screen 111 flows into the flow rate adjustment tank 120.

The flow rate adjustment tank 120 is equipped with a pump 121 and a metering adjustment device 122. The pump 121 transfers the water in the flow rate adjustment tank 120 to the metering adjustment device 122. The metering adjustment device 122 transfers a measured portion of the transferred water to the denitrification tank 130. The excess water returns to the flow rate adjustment tank 120.

The denitrification tank 130 is equipped with an aeration device 131 disposed at the bottom. A blower (not shown) is connected to the aeration device 131. Sludge is stored in the denitrification tank 130. The blower performs intermittent aeration under timer control. When aeration (i.e., air supply) is stopped, anaerobic treatment is performed by anaerobic microorganisms contained in the sludge. As described below, water aerobically treated in the membrane separation tank 140 (water containing nitrate ions (also called nitrification liquid)) is transferred to the denitrification tank 130 by a circulation pump 149. Nitrate ions are reduced by the action of denitrifying bacteria contained in the anaerobic microorganisms to generate nitrogen gas, which is then released into the air (so-called denitrification). In addition, the inside of the denitrification tank 130 is stirred by aeration performed by the blower. The water treated in the denitrification tank 130 flows into the membrane separation tank 140 through an opening 139 in the partition wall.

The membrane separation tank 140 includes a membrane separation device 900, a circulation pump 149, a suction pipe 800, and a cleaning pipe 700. The membrane separation device 900 includes a membrane module 910 that filters water, and an aeration device 940 arranged below the membrane module 910. Hereinafter, the membrane separation device 900 is also referred to as a membrane unit 900. In the embodiment of FIG. 1, three membrane units 900 are arranged in the membrane separation tank 140. One membrane unit 900 includes a plurality of membrane modules 910. In this embodiment, one membrane module 910 is constructed using a plurality of hollow fiber membranes. The total number of membrane modules 910 arranged in the membrane separation tank 140 is adjusted, for example, by adjusting the number of membrane units 900. A blower (not shown) is connected to the aeration device 940 of each membrane unit 900. In this embodiment, air is supplied to the aeration device 940 by the blower. Activated sludge is also contained in the membrane separation tank 140. The water (including the activated sludge) in the membrane separation tank 140 is agitated by air from the air diffuser 940. The aerobic microorganisms contained in the activated sludge undergo aerobic treatment using the oxygen contained in the air from the air diffuser 940. The membrane separation tank 140 is an example of a membrane treatment tank that performs water treatment using a membrane.

A suction pipe 800 is connected to the membrane unit 900 to suck the water filtered by the membrane unit 900 from the membrane unit 900. The suction pipe 800 includes three first pipes 810 connected to the three membrane units 900, respectively, and a second pipe 820 connected to the three first pipes 810. A first connection pipe 148 is fixed to the outer wall 190, penetrating the outer wall 190 and connecting the membrane separation tank 140 to the outside of the wastewater treatment device 100. The second pipe 820 is connected to the first connection pipe 148. A cleaning pipe 700 is connected to the second pipe 820 (details will be described later).

The circulation pump 149 transfers the water in the membrane separation tank 140 to the denitrification tank 130. The dotted line in the figure from the circulation pump 149 to the denitrification tank 130 indicates that the water flows from the circulation pump 149 to the denitrification tank 130, and does not indicate the actual flow path. The actual flow path is positioned so as to avoid other components such as the membrane unit 900. Although not shown in the figure, excess sludge in the membrane separation tank 140 is transferred to the sludge storage tank by a sludge transfer pump.

Outside the wastewater treatment device 100, the connection pipe 148 and the suction pump 600 are connected by a first outer pipe 610. The suction pump 600 sucks water from the multiple membrane units 900 through a suction pipe 800 arranged in the device space 190d and the first outer pipe 610. In addition, a water supply pipe 611 is connected to the middle of the first outer pipe 610 (details will be described later).

A second connection pipe 151 is fixed to the outer wall 190, penetrating the outer wall 190 and connecting the disinfection tank 150 to the outside of the wastewater treatment device 100. The suction pump 600 and the second connection pipe 151 are connected by a second outer pipe 620. The suction pump 600 transfers the water sucked from the membrane unit 900 to the disinfection tank 150 through the second outer pipe 620.

The disinfection tank 150 contains a disinfectant 152, and the water that flows into the disinfection tank 150 is disinfected using the disinfectant 152. The disinfected water flows into the discharge pump tank 160 through an opening 159 in the partition wall.

The discharge pump tank 160 is equipped with a discharge pump 161. The discharge pump 161 transfers the water in the discharge pump tank 160 outside the wastewater treatment device 100.

The outer wall 190 has multiple manhole openings 180 located at the top of the outer wall 190. Workers can inspect the inside of the wastewater treatment device 100 through the manhole openings 180.

A2. Configuration of the membrane unit 900, the suction pipe 800 and the washing pipe 700:
2 is a schematic diagram of the membrane separation tank 140 viewed downward. Three membrane units 900 are arranged in the membrane separation tank 140 in the body direction Db. The second pipe 820 of the suction pipe 800 includes a straight pipe 820a, which is a straight pipe extending in the body direction Db, and a branch pipe 820b connected to the straight pipe 820a. The straight pipe 820a is arranged next to the three membrane units 900. The branch pipe 820b is connected to the first connecting pipe 148 fixed to the outer wall 190 (FIGS. 1 and 3).

3 is a schematic diagram of the membrane separation tank 140 viewed in the body direction Db. In FIG. 3, the membrane unit 900 and the suction pipe 800 are shown, and the cleaning pipe 700 is omitted. As shown in FIG. 2 and FIG. 3, the membrane unit 900 includes a plurality of membrane modules 910, an aeration device 940 arranged below the plurality of membrane modules 910, a water collection pipe 920 arranged above the plurality of membrane modules 910, and an individual pipe 911 connecting the water collection pipe 920 and the membrane module 910. The individual pipe 911 is provided for each membrane module 910. The water collection pipe 920 of the membrane unit 900 and the straight pipe 820a of the second pipe 820 of the suction pipe 800 are connected by the first pipe 810. The first pipe 810 (FIG. 2) is provided for each membrane unit 900. A valve 811 is provided on the flow path of each first tube 810 (hereinafter, the valve 811 is also referred to as a unit valve 811). The unit valve 811 is, for example, a manual valve. When the wastewater treatment device 100 is in operation, the unit valve 811 is in an open state. When a malfunction of the membrane unit 900 occurs, such as when the membrane module 910 is broken, or when the membrane unit 900 is removed from the wastewater treatment device 100, the unit valve 811 is closed when the inside of the second tube 820 of the suction pipe 800 and the membrane separation tank 140 can directly communicate with each other. This prevents foreign matter (for example, activated sludge) from entering the suction pipe 800.

3, the height of the first tube 810 gradually decreases from the water collection tube 920 to the second tube 820 of the membrane unit 900. Here, the area inside the tube where water can flow is called the internal area. In this embodiment, the highest part 800h of the internal area of the suction tube 800 is the internal area of the connection part of the first tube 810 with the water collection tube 920. The first height H1 in the figure is the height of this part 800h. This first height H1 is common between the multiple first tubes 810 of the membrane unit 900. The second height H2 is the height of the highest part 820h of the internal area of the second tube 820 (H1>H2). The reason why the second tube 820 is lower than the first tube 810 in this way will be described later. In FIG. 3, the highest part 820h of the internal area of the second tube 820 is selected from the straight tube 820a. However, in this embodiment, the height and inner diameter of the straight pipe 820a and the branch pipe 820b are the same. Therefore, the highest part 820h may be selected from the branch pipe 820b.

Figure 3 further shows water levels WL1 and WL2. The first water level WL1 is the highest water level in the membrane separation tank 140, and the second water level WL2 is the lowest water level in the membrane separation tank 140. During normal operation of the wastewater treatment device 100, the water level in the membrane separation tank 140 fluctuates between these water levels WL1 and WL2.

Figure 4 is a schematic diagram of a portion of the membrane separation tank 140 viewed in the body direction Db. In Figure 4, the membrane unit 900, the second pipe 820 of the suction pipe 800, and the cleaning pipe 700 are shown, and the first pipe 810 of the suction pipe 800 is omitted. As shown in the figure, the cleaning pipe 700 is connected to the horizontal part of the straight pipe 820a, extends horizontally from the straight pipe 820a, bends vertically upward, and extends vertically upward to reach the opening 700o. As described later, when the suction pipe 800 is cleaned, water is discharged from the opening 700o (hereinafter, the opening 700o is also referred to as the discharge opening 700o). A valve 710 is provided on the flow path of the cleaning pipe 700 (hereinafter, the valve 710 is also referred to as the cleaning valve 710). In this embodiment, the cleaning valve 710 is a manual valve.

The discharge opening 700o is disposed in the membrane separation tank 140. That is, the horizontal position of the discharge opening 700o is included in the membrane separation tank 140 (FIG. 2). The third height H3 in FIG. 4 is the height of the discharge opening 700o. When the discharge opening 700o is inclined with respect to the horizontal plane, the third height H3 is the lowest position of the edge of the discharge opening 700o. In this embodiment, the third height H3 is higher than the height of the water surface in the normal operating state of the membrane separation tank 140 (when the water level fluctuates, the highest water level. In this embodiment, the first water level WL1). That is, the discharge opening 700o is disposed in the air. Also, the third height H3 of the discharge opening 700o is higher than the first height H1 of the highest part 800h (FIG. 3) of the internal region of the suction pipe 800.

A3. Connection between the wastewater treatment device 100 and the suction pump 600:
Fig. 5 is a schematic diagram showing an example of a wastewater treatment system 1000 including a wastewater treatment device 100 and a suction pump 600. In the example of Fig. 5, the wastewater treatment device 100 is buried under the ground GL (i.e., underground). A manhole frame 510 is attached to the manhole opening 180, and a cover 520 is fitted into the manhole frame 510. A part of the wastewater treatment device 100 is shown in the figure. The wastewater treatment system 1000 includes the wastewater treatment device 100, the suction pump 600, a first outer pipe 610 connecting the wastewater treatment device 100 and the suction pump 600, and a water supply pipe 611 connected to the first outer pipe 610.

The first outer pipe 610 is connected to the outer opening 148o of the first connecting pipe 148. The first outer pipe 610 is connected to the suction pipe 800 by the first connecting pipe 148. The first outer pipe 610 extends from the first connecting pipe 148 at an upward gradient to near the suction pump 600 (in the figure, a part of the first outer pipe 610 is shown by a dotted line for simplification). In the example of FIG. 5, the first outer pipe 610 bends vertically upward near the suction pump 600, extends vertically upward, and reaches the ground GL. The first outer pipe 610 is then connected to the suction pump 600 arranged on the ground.

A valve 613 (also referred to as pump valve 613) is provided near the suction pump 600 on the flow path of the first outer pipe 610. The pump valve 613 is, for example, a manual valve. When the wastewater treatment device 100 is in operation, the pump valve 613 is in an open state. When the suction pipe 800 is cleaned, which will be described later, the pump valve 613 is closed.

A water supply pipe 611 is connected to the portion of the first outer pipe 610 that is located on the ground and is closer to the wastewater treatment device 100 than the pump valve 613. The water supply pipe 611 extends from the first outer pipe 610 to an opening 611o. As described below, when the suction pipe 800 is cleaned, water is supplied to the opening 611o (hereinafter, the opening 611o is also referred to as the water supply opening 611o). A valve 612 (also referred to as the water supply valve 612) is provided on the flow path of the water supply pipe 611. In this embodiment, the water supply valve 612 is a manual valve. When the wastewater treatment device 100 is in operation, the water supply valve 612 is in a closed state. When the suction pipe 800 is cleaned, as described below, the water supply valve 612 is opened.

A4. Cleaning of the suction tube 800:
FIG. 6 is a flow chart showing an embodiment of the cleaning process of the suction pipe 800 (FIG. 5). The operator cleans the suction pipe 800 according to the procedure of FIG. 6. In S110, the operator stops the operation of the suction pump 600 (FIG. 5). For example, the operator turns off the power switch of the suction pump 600. In S120, the operator closes the pump valve 613. In S130, the operator opens the cleaning valve 710 and the water supply valve 612. The operator operates the cleaning valve 710 provided in the membrane separation tank 140 through the manhole opening 180 (FIG. 1). In S140, the operator supplies water to the water supply opening 611o. For example, the operator supplies tap water to the water supply opening 611o. Hereinafter, the water supplied to the water supply opening 611o is also referred to as supply water.

The feed water supplied to the water supply opening 611o (FIG. 5) generates the following water flow. That is, the water in the first outer pipe 610 flows into the wastewater treatment device 100. The water that flows into the wastewater treatment device 100 flows into the second pipe 820 of the suction pipe 800. The water in the second pipe 820 (FIG. 3) can move through the first pipe 810 to the multiple membrane modules 910 of the membrane unit 900. However, the multiple membrane modules 910 are arranged in the water in the membrane separation tank 140. In addition, the movement of water from the inside of the membrane module 910 to the outside (here, inside the membrane separation tank 140) is caused by the membrane permeation pressure. Therefore, the water that moves to the membrane module 910 remains as a part of the water that flows out from the second pipe 820. The other water that flows out from the second pipe 820 (FIG. 5) moves to the washing pipe 700. The water in the washing pipe 700 is discharged from the discharge opening 700o. The discharged water falls into the membrane separation tank 140. Hereinafter, the water flow from the water supply opening 611o to the discharge opening 700o is referred to as the wash water flow.

Solids may be present in the suction pipe 800 due to various causes. For example, during the manufacture of the wastewater treatment device 100, solids (e.g., resin fragments) may unintentionally enter the suction pipe 800. If the membrane module 910 is damaged, solids (e.g., sludge) that have passed through the membrane module 910 may reach the suction pipe 800. Solutes such as calcium contained in the water filtered by the membrane module 910 may precipitate in the suction pipe 800. Biofilms may be generated in the suction pipe 800 due to organic matter contained in the water filtered by the membrane module 910. When such solids in the suction pipe 800 are sucked by the suction pump 600, the solids may be mixed into the treated water discharged from the wastewater treatment device 100. In order to prevent such malfunctions, it is preferable to remove the solids in the suction pipe 800.

In this embodiment, water is continuously supplied to the water supply opening 611o (FIG. 5). As a result, solid matter in the suction pipe 800 is swept away by the cleaning water flow and discharged from the discharge opening 700o.

In addition, in this embodiment, the suction pipe 800 is washed with the unit valve 811 open. In this case, water can move between the second pipe 820 and the membrane unit 900 through the first pipe 810. Therefore, solids on the membrane module 910 side of the unit valve 811 can also be caught in the washing water flow and can be discharged from the discharge opening 700o.

In addition, solids having a density lower than that of water may be present in the suction pipe 800. For example, low-density resin fragments generated during the manufacture of the wastewater treatment device 100 may be present in the suction pipe 800. In addition, solids in which biofilm and gas (e.g., air, etc.) are integrated may be generated in the suction pipe 800. Such low-density solids tend to move to the higher parts of the internal region of the pipe, such as the suction pipe 800. In this embodiment, the third height H3 of the discharge opening 700o (FIG. 4) is higher than the first height H1 of the highest part 800h of the internal region of the suction pipe 800. Therefore, low-density solids in the suction pipe 800 are easily discharged from the discharge opening 700o. In addition to solids, gases such as air may be present in the suction pipe 800. The gas in the suction pipe 800 may hinder the suction of water by the suction pump 600. Such gases are also easily discharged from the discharge opening 700o, just like low-density solids.

Solid matter may also be present in the first outer pipe 610 (FIG. 5). The solid matter in the first outer pipe 610 is also swept away by the cleaning water flow and discharged from the discharge opening 700o (the same applies to the gas in the first outer pipe 610).

In S160 (FIG. 6), the operator determines whether a predetermined termination condition for terminating the cleaning is satisfied. The termination condition may be any condition that indicates that the possibility of a malfunction in the wastewater treatment device 100 is low. For example, a first condition that no solid matter is visually observed in the water discharged from the discharge opening 700o may be used as the termination condition. Also, a second condition that it is visually confirmed that no gas is being discharged from the discharge opening 700o may be used as the continuation condition. In this embodiment, the termination condition is satisfied when both the first and second conditions are satisfied.

If the termination condition is not satisfied (S160: No), the operator repeats S160 (i.e., water supply to the water supply opening 611o (Figure 5) continues) until the termination condition is satisfied. If the termination condition is satisfied (S160: Yes), in S170, the operator closes the cleaning valve 710 (Figure 5) and the water supply valve 612. In S180, the operator stops the supply of water to the water supply opening 611o. In S190, the operator opens the pump valve 613. In S200, the operator starts the operation of the suction pump 600. Then, the process in Figure 6 ends. With the above, the cleaning process of the suction pipe 800 ends, and the operation of the wastewater treatment device 100 begins.

As described above, in this embodiment, the wastewater treatment device 100 (FIG. 1) includes an outer wall 190, a plurality of water treatment tanks 110-160 including a membrane separation tank 140, a membrane separation device 900 arranged in the membrane separation tank 140, a suction pipe 800 connected to the membrane separation device 900, a cleaning pipe 700 connected to the suction pipe 800, and a cleaning valve 710 provided on the flow path of the cleaning pipe 700. The outer wall 190 forms the outer surface 190s of the wastewater treatment device 100. The outer wall 190 also forms an apparatus space 190d, which is a space surrounded by the outer wall 190. The plurality of water treatment tanks 110-160 are provided in the apparatus space 190d. The membrane separation device 900 has a membrane module 910 that filters water. The suction pipe 800 is a pipe arranged in the apparatus space 190d, and is a pipe for sucking water filtered by the membrane separation device 900 from the membrane separation device 900. The cleaning pipe 700 is a pipe disposed in the device space 190d and has a discharge opening 700o. The cleaning pipe 700 is a pipe for moving water containing solid matter in the suction pipe 800 to the outside of the suction pipe 800. As described with reference to Figures 5 and 6, this configuration allows water containing solid matter to be moved from inside the suction pipe 800 to the outside of the suction pipe 800 through the cleaning pipe 700 by opening the cleaning valve 710, so that the suction pipe 800 can be easily cleaned. In addition, by closing the cleaning valve 710, it is possible to prevent foreign matter from entering the suction pipe 800 through the discharge opening 700o of the cleaning pipe 700.

As described in FIG. 4, the discharge opening 700o of the cleaning pipe 700 is positioned higher than the water level at the horizontal position of the discharge opening 700o (here, the first water level WL1 of the membrane separation tank 140). Therefore, the operator can easily observe the water flowing out from the discharge opening 700o of the cleaning pipe 700. Also, by observing the water flowing out from the discharge opening 700o of the cleaning pipe 700, the operator can easily check the cleaning status of the suction pipe 800.

Also, as shown in Figures 2, 4, etc., the discharge opening 700o of the cleaning pipe 700 is arranged in the membrane separation tank 140. Therefore, it is possible to prevent the water flowing out from the discharge opening 700o of the cleaning pipe 700 from flowing into the water treatment tank downstream of the membrane separation tank 140.

The cleaning valve 710 of the cleaning pipe 700 is a manual valve. Therefore, an operator can easily open and close the communication between the suction pipe 800 and the discharge opening 700o of the cleaning pipe 700 by operating the cleaning valve 710. Furthermore, compared to valves with complex configurations (e.g., valves that are opened and closed by a driving source such as hydraulics), manual valves have a simple configuration and are highly durable. Therefore, it is possible to prevent foreign matter from entering the suction pipe 800 from the discharge opening 700o due to valve failure.

In addition, in this embodiment, as shown in Figures 3 and 4, the discharge opening 700o of the cleaning pipe 700 is located at a position higher than the highest part 800h of the internal region of the suction pipe 800 (H3>H1). Therefore, when low-density solids are present in the suction pipe 800, the water containing the low-density solids can be easily moved from inside the suction pipe 800 to outside the suction pipe 800 through the cleaning pipe 700, so that the suction pipe 800 can be easily cleaned.

3, the suction pipe 800 includes a first pipe 810 and a second pipe 820. The first pipe 810 forms the highest part 800h of the internal region of the suction pipe 800. The second pipe 820 is a part connected to the opposite side of the first pipe 810 from the membrane separation device 900 side. The second height H2 of the highest part 820h of the internal region of the second pipe 820 is lower than the first height H1 of the highest part 800h of the internal region of the first pipe 810. That is, the second pipe 820 forms an internal region located at a lower position than the highest part 800h of the internal region of the first pipe 810. Solids having a density higher than that of water may be present in the suction pipe 800. Such solids may be deposited in the lower second pipe 820 of the suction pipe 800. And, as shown in FIGS. 2 and 4, the cleaning pipe 700 is connected to the second pipe 820 of the suction pipe 800. With this configuration, water containing solid matter accumulated in the second tube 820 can easily move out of the suction tube 800 through the cleaning tube 700, making it easy to clean the suction tube.

As shown in FIG. 2, the wastewater treatment device 100 includes N (N is an integer of 2 or more. In this embodiment, N=3) membrane separation devices 900 arranged in the membrane separation tank 140. The suction pipe 800 includes N first pipes 810 connected to the N membrane separation devices 900, respectively, and a second pipe 820 connected to the N first pipes 810. The cleaning pipe 700 is connected to the second pipe 820. Therefore, when N membrane separation devices 900 are used, the suction pipe 800 can be appropriately cleaned. For example, by discharging the water in the second pipe 820 common to the N membrane separation devices 900 from the discharge opening 700o of the cleaning pipe 700, it is possible to suppress unevenness in the degree of cleaning among the N membrane separation devices 900.

Also, as shown in FIG. 5, in this embodiment, the suction pump 600 and the second pipe 820 of the suction pipe 800 are connected via the first outer pipe 610. When the suction pump 600 is far from the wastewater treatment device 100, the gradient of the first outer pipe 610 extending from the wastewater treatment device 100 toward the suction pump 600 must be made small. When the gradient of the first outer pipe 610 is small, gas such as air tends to accumulate in the first outer pipe 610. In this embodiment, as shown in FIG. 3, the second height H2 of the highest part 820h of the internal region of the second pipe 820 is lower than any of the N heights (common first height H1 in this embodiment) of the N highest parts 800h of the N internal regions of the N first pipes 810. Therefore, even if the suction pump 600 is far from the wastewater treatment device 100, the gradient of the first outer pipe 610 can be made large. In other words, when the lower limit of the gradient of the first outer pipe 610 is determined, the suction pump 600 can be placed at a position far from the wastewater treatment device 100. In this way, the degree of freedom of the position of the suction pump 600 can be improved without reducing the gradient of the first outer pipe 610. Note that, when the difference between the first height H1 and the second height H2 is large, low-density solids and gases tend to accumulate in the first pipe 810. Therefore, it is preferable that the difference between the first height H1 and the second height H2 is small. For example, the difference between the first height H1 and the second height H2 is preferably 120 mm or less, particularly preferably 100 mm or less, and most preferably 80 mm or less.

B. Second embodiment:
7(A) and 7(B) are flow charts showing another embodiment of the cleaning process for the aspirating tube 800 (FIG. 5). The only difference from the embodiment in FIG. 6 is that S120 is replaced by S120a (FIG. 7(A)) and S190 is replaced by S190a (FIG. 7(B)). The other parts of the cleaning process are the same as the corresponding parts of FIG. 6 (illustration and description of the same parts are omitted).

In S120a (FIG. 7A), the operator closes the unit valve 811 in addition to the pump valve 613. If the wastewater treatment device 100 has multiple membrane units 900, the operator closes all of the unit valves 811.

In S190a (FIG. 7B), the operator opens the unit valve 811 in addition to the pump valve 613. If the wastewater treatment device 100 has multiple membrane units 900, the operator opens all of the unit valves 811.

In this way, in the second embodiment, the suction pipe 800 is cleaned while the unit valve 811 is closed. This prevents the pressure caused by the cleaning water flow from being applied to the membrane unit 900 (e.g., the membrane module 910). As a result, damage to the membrane unit 900 can be prevented.

C. Third embodiment:
8 is a schematic diagram showing another embodiment of the wastewater treatment device. The figure shows a part of a membrane separation tank 140x as seen in the body direction Db. Except for the suction pipe 800x and the washing pipe 700x, the configuration of the wastewater treatment device 100x is the same as the configuration of the wastewater treatment device 100 in FIGS. 1 to 4 (illustration and description of the same parts are omitted).

The suction pipe 800x has a first pipe 810x and a second pipe 820x. The only difference between the first pipe 810x of this embodiment and the first pipe 810 of FIG. 3 is that the first pipe 810x extends horizontally without changing its height. A unit valve 811 is provided on the flow path of the first pipe 810x. The first height H1x is the height of the highest part of the internal region of the first pipe 810x. In this embodiment, the internal region of the first pipe 810x extends horizontally. Therefore, when following the first pipe 810x from the membrane unit 900 to the second pipe 820x, at any position, the height of the highest part of the internal region is the first height H1x.

The only difference between the second tube 820x of this embodiment and the second tube 820 of Figures 3 and 4 is that the branch tube 820xb of this embodiment is longer than the branch tube 820b of Figure 2. The configuration of the straight tube 820a of this embodiment is the same as the configuration of the straight tube 820a of Figure 2. The second height H2 is the height of the highest part 820h of the internal region of the second tube 820x (in Figure 8, the highest part 820h is selected from the straight tube 820a). In this embodiment, the second height H2 is higher than the first height H1x. In this embodiment, the highest part of the internal region of the suction tube 800x is the highest part 820h of the internal region of the second tube 820x. The second height H2 indicates the height of the highest part of the internal region of the suction tube 800x.

The cleaning pipe 700x is connected to the upper surface (i.e., the highest part) of the straight pipe 820a. In this way, the cleaning pipe 700x is connected to the part of the suction pipe 800x that forms the highest part 820h of the internal area of the suction pipe 800x. The cleaning pipe 700x then extends vertically upward from the straight pipe 820a to the discharge opening 700xo. A cleaning valve 710x is provided on the flow path of the cleaning pipe 700x.

In this embodiment, the cleaning process of the suction tube 800x is the same as in the embodiment of FIG. 6 or FIG. 7. Here, a cleaning valve 710x is used instead of the cleaning valve 710, and a discharge opening 700xo is used instead of the discharge opening 700o.

The third height H3x (FIG. 8) is the height of the discharge opening 700xo. In this embodiment, the discharge opening 700xo is also disposed in the membrane separation tank 140x. The third height H3x is higher than the height of the water surface in the normal operating state of the membrane separation tank 140x (if the water level fluctuates, the highest water level. In this embodiment, the first water level WL1). That is, the discharge opening 700xo is disposed in the air. The third height H3x of the discharge opening 700xo is also higher than the second height H2 of the highest part 800h of the internal region of the suction pipe 800x. The cleaning valve 710x is a manual valve. Although not shown, the membrane separation tank 140x also has three membrane units 900 in this embodiment. The suction pipe 800x includes three first pipes 810x connected to the three membrane separation devices 900, respectively, and a second pipe 820x connected to the three first pipes 810x. The cleaning pipe 700x is connected to the second pipe 820x. In this way, the wastewater treatment device 100x of this embodiment has various features in common with the wastewater treatment device 100 of Figures 1 to 4. Therefore, the wastewater treatment device 100x has various advantages similar to those of the embodiment of Figures 1 to 4.

As described above, solids having a density lower than that of water may be present in the suction pipe 800x. Such low-density solids tend to gather in the highest part of the internal region of the suction pipe 800x. In this embodiment, the cleaning pipe 700x is connected to a part of the suction pipe 800x that forms the highest part of the internal region of the suction pipe 800x. Therefore, when low-density solids are present in the suction pipe 800x, cleaning the suction pipe 800x with supply water (FIGS. 6, 7(A), and 7(B)) can easily discharge water containing low-density solids from the discharge opening 700xo. In this way, the suction pipe 800x can be easily cleaned. In addition, gas in the suction pipe 800x is easily discharged from the discharge opening 700xo, just like low-density solids.

D. Modification (1) The suction pipe connected to the membrane separation device may be various pipes connected to the membrane separation device and configured to suck water from the membrane separation device, instead of the configuration of the suction pipes 800, 800x (FIGS. 1-5, 8). For example, the first pipe 810 may include a portion disposed at a higher position than the connection portion with the membrane unit 900. The internal region of the second pipe 820 may include a portion disposed at a higher position than the highest portion of the internal region of the first pipe 810. Also, in the embodiment of FIG. 2, the total number of membrane separation devices 900 may be 1. In this case, the total number of first pipes 810 may be 1. Also, the second pipe 820 may be a pipe without a branch connecting one first pipe 810 and the first connecting pipe 148. In this way, the suction pipe may be one pipe without a branch connected to one membrane separation device. In this case, the washing pipe may be connected to any position of the suction pipe.

(2) The configuration of the cleaning pipe may be any configuration that can be connected to the suction pipe and move the water containing solids in the suction pipe out of the suction pipe, instead of the configuration of the cleaning pipe 700, 700x (Figures 2, 4, 5, and 8) described above. For example, the opening of the cleaning pipe (e.g., the discharge opening 700o, 700xo) may be located at a position lower than the highest part of the internal area of the suction pipe (e.g., part 800h of the suction pipe 800 in Figure 4). The opening of the cleaning pipe may be located below the water surface. The cleaning pipe may extend from the suction pipe to a water treatment tank (e.g., the flow rate adjustment tank 120) upstream of the membrane separation tank 140, 140x. The opening of the cleaning pipe may be located in the water treatment tank upstream of the membrane separation tank 140, 140x. The cleaning pipe may be connected to the first pipe 810, 810x. In this case, it is preferable that a cleaning pipe is provided for each of the first pipes 810, 810x.

In addition, to clean the suction pipe, water is supplied to the pipe connected to the suction pipe. In the embodiment of FIG. 5, water is supplied to the water supply opening 611o of the water supply pipe 611 connected to the suction pipe 800 via the first outer pipe 610. Here, the height of the water supply position can be various heights. For example, water can be supplied at various heights above the manhole opening 180. Here, the higher the water supply position, the more likely the water in the suction pipe will flow out from the opening of the cleaning pipe (for example, the discharge opening 700o in FIG. 5). In addition, the lower the height of the opening of the cleaning pipe, the more likely the water in the suction pipe will flow out from the opening of the cleaning pipe. The height of the opening of the cleaning pipe may be experimentally determined in advance so that when water for cleaning is supplied to the pipe connected to the suction pipe, the water in the suction pipe will flow out from the opening of the cleaning pipe. For example, it is preferable that the height of the opening of the cleaning pipe is the same as the highest part of the manhole opening (for example, the highest part 180h of the manhole opening 180 in FIG. 5), and that the water in the suction pipe flows out from the opening of the cleaning pipe when water is supplied to the pipe connected to the suction pipe without applying pressure. Here, the water level of the membrane treatment tank (for example, the membrane separation tank 140) having the membrane separation device may be set to the water level in the normal operating state (the lowest water level when the water level fluctuates. In the example of FIG. 3, the second water level WL2). Even if the opening of the cleaning pipe is higher than the water level of the membrane treatment tank, the water in the suction pipe may flow out from the opening of the cleaning pipe due to the pressure loss of the membrane. Note that any pipe connected to the suction pipe may be used to supply water for cleaning the suction pipe. For example, a pipe for supplying water, such as the water supply pipe 611, may be connected to the suction pipe.

In either case, it is preferable that the cleaning pipe has a simple configuration that allows solid matter to move easily. For example, it is preferable that the cleaning pipe is a single flow path with no branches.

(3) The valve (e.g., cleaning valve 710, 710x) provided on the flow path of the cleaning pipe may have various configurations capable of opening and closing the cleaning pipe. For example, a valve selected from a ball valve, a globe valve, a gate valve, a butterfly valve, a needle valve, and a diaphragm valve may be used. In addition, in order to discharge water containing various solids through the cleaning pipe, it is preferable that the valve is configured so that the solids can easily move. For example, the valve may have a valve body and a valve seat, and be configured so that the valve body is moved by an external force. It is preferable that the valve is a valve that opens and closes one flow path and does not have a branch flow path. It is preferable that the valve is a single-function valve that opens and closes the flow path. Note that the valve may be a valve that is opened and closed by a power source such as electricity, hydraulic pressure, or air pressure instead of a manual valve. For example, the valve may be an electromagnetic valve. Similarly, various valves can be adopted for other valves (e.g., water supply valve 612, pump valve 613, unit valve 811, etc.).

(4) The cleaning process of the suction tube may be various other processes instead of the processes of FIG. 6, FIG. 7(A), and FIG. 7(B). For example, the termination condition of S160 (FIG. 6) may be various other conditions instead of both the first and second conditions described above being satisfied. For example, the termination condition may be that the elapsed time from the start of the supply of water to the water supply opening 611o (FIG. 5) is equal to or longer than a predetermined reference time. The reference time may be determined experimentally in advance so that solids and the like can be appropriately discharged. In addition, the order of the operation of each of the multiple valves in S120 (S120a)-S140 and the start of the water supply may be any order. In addition, the order of the operation of each of the multiple valves in S170-S190 (S190a) and the stop of the water supply may be any order. The cleaning process may be performed while the pump valve 613 is open.

(5) The membrane used in water treatment is not limited to a hollow fiber membrane, but may be any membrane that separates solids from water containing solids such as activated sludge and filters the water. For example, the membrane may be a flat membrane or a monolith membrane. In addition, the membrane may be made of various materials such as synthetic resins and ceramics.

(6) The configuration of the membrane separation device may be any configuration having one or more membranes, instead of the configuration of the membrane separation device 900 in Figures 2 and 3. For example, the air diffuser 940 may be omitted from the membrane separation device. In this case, it is preferable to place a separate air diffuser below the membrane separation device. Also, the total number of membranes included in one membrane separation device may be one. In this case, the water collection pipe (e.g., the water collection pipe 920 (Figure 3)) may be omitted. And, the suction pipe (e.g., the first pipe 810 of the suction pipe 800) and one membrane may be directly connected.

(7) The configuration of the membrane treatment tank may be various configurations having one or more membrane separation devices instead of the configuration of the membrane separation tank 140 in Figures 1 to 4. For example, the membrane treatment tank may be a contact aeration tank having a membrane separation device and a contact material.

(8) The configuration of the wastewater treatment device may be various other configurations instead of the configuration of the wastewater treatment device 100, 100x (Figures 1-4, 8). For example, multiple water treatment tanks (e.g., water treatment tanks 110-160) used for water treatment may be distributed among multiple bodies. For example, one body may house only a membrane treatment tank. In this case, one body having a membrane treatment tank also constitutes a wastewater treatment device having a membrane treatment tank. In addition, the second outer pipe 620 (Figure 1) connects the suction pump 600 and the wastewater treatment device having the disinfection tank 150. In addition, the wastewater treatment is not limited to the water treatment tanks 110-160 described in Figure 1, etc., and one or more various water treatment tanks including a membrane treatment tank may be used. For example, an anaerobic treatment tank having an agitation device may be used instead of the denitrification tank 130.

(9) The wastewater treatment system configured to suck water from the membrane separation device and to be able to clean the suction pipe may have various other configurations instead of the configuration of the wastewater treatment system 1000 in FIG. 5. In general, the wastewater treatment system may have various configurations including a wastewater treatment device including a membrane treatment tank, a suction pump, and an outer pipe that connects the suction pipe of the wastewater treatment device to the suction pump. For example, in the embodiment of FIG. 5, the water supply pipe 611 may be omitted. In the cleaning process of the suction pipe, an operator may disconnect the first outer pipe 610 from the suction pump 600 and supply water to the end of the first outer pipe 610. The wastewater treatment device may also be installed on the ground.

The present invention has been described above based on examples and modified examples, but the above-mentioned embodiments of the invention are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit of the invention, and equivalents thereof are included in the present invention.

100, 100x...wastewater treatment device, 110...aeration type screen, 111...screen, 120...flow rate adjustment tank, 121...pump, 122...metering adjustment device, 130...denitrification tank, 131...aeration device, 139...opening, 140, 140x...membrane separation tank, 148...first connecting pipe, 148o...opening, 149...circulation pump, 150...disinfection tank, 151...second connecting pipe, 152...disinfectant, 159...opening, 160...discharge pump tank, 161...discharge pump, 180...manhole opening, 190...outer wall, 190b...body, 190d...device space, 190s...outer surface, 600...suction pump, 610...first outer pipe, 611...water supply pipe, 611o...water supply opening, 612...water supply valve, 613... Pump valve, 620... second outer pipe, 700, 700x... cleaning pipe, 700o, 700xo... discharge opening, 710, 710x... cleaning valve, 800, 800x... suction pipe, 800h... part, 810, 810x... first pipe, 811... unit valve, 820, 820x... second pipe, 820a... straight pipe, 820b, 820xb... branch pipe, 8 20h...part, 900...membrane separation device (membrane unit), 910...membrane module, 911...individual pipe, 920...water collection pipe, 930...chemical solution pipe, 940...aeration device, 1000...wastewater treatment system, H1, H1x...first high, H2...second high, H3, H3x...third high, GL...ground, Db...body direction, WL1...first water level, WL2...second water level

Claims (8)

A wastewater treatment device, comprising:
An exterior wall forming an outer surface;
One or more water treatment tanks including a membrane treatment tank provided in an equipment space that is a space surrounded by the outer wall;
A membrane separation device disposed in the membrane treatment tank and having a membrane for filtering water;
a suction pipe connected to the membrane separation device and disposed within the device space, for suctioning water filtered by the membrane separation device from the membrane separation device;
a washing pipe having an opening, connected to the suction pipe and disposed within the device space, for moving water containing solids in the suction pipe out of the suction pipe;
a valve provided on a flow path of the cleaning pipe;
Equipped with
The opening of the cleaning pipe is disposed at a position higher than the water surface level at a horizontal position of the opening, which is the position of the opening when viewed downward in the water treatment tank in which the opening of the cleaning pipe is disposed;
The opening of the cleaning pipe is disposed in the membrane treatment tank or in a water treatment tank upstream of the membrane treatment tank among the one or more water treatment tanks.
Wastewater treatment equipment. The wastewater treatment device according to claim 1 ,
The valve is a manual valve.
Wastewater treatment equipment. The wastewater treatment device according to claim 1 or 2 ,
the opening of the irrigation tube is located at a position higher than the highest portion of the interior region of the suction tube;
Wastewater treatment equipment. The wastewater treatment device according to any one of claims 1 to 3 ,
the irrigation tube is connected to a portion of the suction tube that forms the highest portion of the interior region of the suction tube;
Wastewater treatment equipment. The wastewater treatment device according to any one of claims 1 to 3 ,
The suction tube is
a first portion forming a highest portion of an interior area of the suction tube;
A second portion is connected to the first portion on the opposite side to the membrane separation device side and forms an internal region located at a lower position than the highest portion of the internal region of the first portion;
Including,
the irrigation tube is connected to the second portion of the suction tube;
Wastewater treatment equipment. The wastewater treatment device according to any one of claims 1 to 5 ,
The membrane treatment tank includes N membrane separation devices (N is an integer of 2 or more),
The suction tube is
N first tubes respectively connected to the N membrane separation devices;
A second tube connected to the N first tubes;
Including,
The flushing pipe is connected to the second pipe.
Wastewater treatment equipment. The wastewater treatment device according to claim 6 ,
a height of a highest portion of the inner region of the second tube is lower than any of N heights of N highest portions of the N inner regions of the N first tubes;
Wastewater treatment equipment. A wastewater treatment device according to any one of claims 1 to 7 ,
A suction pump;
an outer pipe that connects the suction pipe and the suction pump;
A wastewater treatment system comprising:

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