JP2019166424A - Wastewater treatment device and wastewater treatment method - Google Patents

Abstract

To provide a wastewater treatment device capable of discharging filtrated water through a natural discharge route using a principle of siphon without using corrosion-resistant expensive vacuum tank and vacuum pump.SOLUTION: A wastewater treatment device 100 includes a membrane separation tank 10 having membrane separation means 11 dipped and arranged therein, a treated water tank 20 storing water to be treated filtered through the membrane separation means and arranged so that a liquid level of the treated water is lower than a liquid level of the water to be treated in the membrane separation tank, a first treated water path 40 arranged so that a highest position is higher than a liquid level of the water to be treated in the membrane separation tank to connect the membrane separation means with the treated water tank, a second treated water path 50 branching from the first treated water path and connected to the treated water tank via an air vent tank 30 in which a lowest part in an internal space is arranged in a lower position than the liquid level of the treated water in the treated water tank, and a third treated water path 60 branching from the second treated water path between the air vent tank and the treated water tank and connected with pump means 61 capable of discharging the treated water in the second treated water path.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wastewater treatment apparatus and a wastewater treatment method provided with membrane separation means.

  Patent Document 1 discloses a membrane immersion tank in which a filtration membrane is immersed, a treatment water tank that stores the membrane-filtered treated water, and a transfer pipe that connects the filtration membrane in the membrane immersion tank and the treated water tank. In the water treatment apparatus using membrane filtration, the transfer pipe has an opening below the water surface of the membrane immersion tank and is connected to the treatment water tank, and a vacuum pump for reducing the pressure in the pipe to the transfer pipe Alternatively, there has been proposed a water treatment device by membrane filtration configured to connect a decompression device comprising a vacuum tank and transfer membrane filtrate to a treated water tank by a siphon.

JP 2003-251346 A

  In the water treatment apparatus described above, in order to eliminate the clogging caused by the fouling substance deposited on the filtration membrane, a cleaning liquid such as sodium hypochlorite is supplied from the transfer pipe to the filtration membrane as necessary to remove the fouling substance. The chemical solution to be removed is washed.

  If a siphon is formed in the transfer pipe using a decompression device such as a vacuum pump or vacuum tank after such chemical cleaning, the vacuum pump or vacuum tank may be corroded and damaged by chlorine gas generated from the cleaning liquid. For this reason, it is necessary to construct a decompression device using a corrosion-resistant material, and there is a problem in that not only labor is required for selecting parts, but also cost increases.

  In addition, when using a large vacuum tank so that air lock does not occur in the transfer pipe, there is a problem of securing the installation space for that purpose, and the cleaning wastewater flowing into the transfer pipe from the filtration membrane does not flow into the treated water tank. It is necessary to provide a pump means for taking out the components, and there has been a problem that both of them raise the cost of parts and the construction cost.

  In view of the above-described problems, an object of the present invention is to provide a wastewater treatment apparatus and a wastewater treatment apparatus capable of discharging filtered water by a natural discharge path using the principle of siphon without using an expensive vacuum tank or vacuum pump having corrosion resistance. The point is to provide a method.

  In order to achieve the above-mentioned object, the first characteristic configuration of the wastewater treatment apparatus according to the present invention is a wastewater treatment apparatus provided with membrane separation means, as described in claim 1 of the claims, wherein the membrane A membrane separation tank in which the separation means is immersed in the water to be treated, and the treated water filtered by the membrane separation means are stored, and the level of the stored treated water is the liquid level of the water to be treated in the membrane separation tank. A first treatment that connects the membrane separation means and the treated water tank, the treated water tank arranged so as to be lower, and the highest position disposed higher than the liquid level of the treated water in the membrane separation tank. The treated water tank via an air vent tank that is branched from the water path and the first treated water path, and the lowermost part of the internal space is positioned lower than the treated water level of the treated water tank A second treated water path connected to, the air vent tank and the And a third treated water path that is branched from the second treated water path to the water tank and connected to pump means capable of discharging treated water in the second treated water path. is there.

  The discharged water filled in the air vent tank is discharged from the second treated water path to the third treated water path using the pump means, thereby leading the first treated water path communicating with the second treated water path to negative pressure. . The water to be treated in the membrane separation tank is sucked through the membrane separation means due to the negative pressure generated in the first treated water path, the filtration by the membrane separation means proceeds, and the filtered treated water is It flows into one treated water path. As a result, the space between the membrane separation means and the treated water tank is filled with the treated water via the first treated water path, and the continuous filtering action by the membrane separation means is maintained by the siphon principle. . The treated water for satisfying the first treated water path may be treated water stored in the treated water tank, both treated water filtered by the membrane separation means and treated water stored in the treated water tank. There may be.

  As described in the second aspect of the present invention, the second characteristic configuration is that, in addition to the first characteristic configuration described above, the air vent tank is provided with an air release means.

  By opening the air bleed tank to the air with the air release means provided in the air bleed tank, prior to filtration, the air evacuation tank does not cause fluctuations in internal pressure in each treated water path connected to the air bleed tank. It becomes possible to fill the exhalation water.

  In addition to the first or second characteristic configuration described above, the third characteristic configuration includes the connection portion of the third treated water path and the second treated water path, as described in claim 3. It is in the point which is equipped with the flow volume adjustment means which can open and close a flow path between treatment water tanks.

  By releasing the flow path between the connection part of the third treated water path and the treated water tank by the flow rate adjusting means, it is possible to supply exhalation water from the treated water tank to the air vent tank, and As a result of the blockage, expiratory water can be discharged from the air vent tank via the third treated water path and the air in the third treated water path can be drawn out.

  In the fourth feature configuration, as described in claim 4, in addition to any of the first to third feature configurations described above, the third treated water path stores the cleaning liquid of the membrane separation means. It exists in the point connected to a washing | cleaning-liquid storage tank or said 1st treated water path | route.

  When it is necessary to perform chemical cleaning on the membrane separation means, if the third treatment water path is connected to the cleaning liquid storage tank, the treated water can be supplied as dilution water to the cleaning liquid storage tank, and the air vent tank from the cleaning liquid storage tank A diluted cleaning chemical can be introduced. Further, if the third treated water path is connected to the first treated water path, the cleaning chemical introduced into the air vent tank is removed from the third treated water path via the pump means provided in the third treated water path. It becomes possible to supply the membrane separation means via the first treated water path. In the latter case, if the air vent tank is made to function as a cleaning liquid storage tank, there is no need to provide another cleaning liquid storage tank.

  In the fifth feature configuration, as described in claim 5, in addition to any of the first to fourth feature configurations described above, the capacity of the internal space of the air vent tank is the first treated water path. This is because it is set to a value larger than the capacity of the channel space.

  By discharging the expiratory water filled in the air vent tank through the third treated water path, the entire amount of air staying in the internal space of the first treated water path can be sucked and discharged, and the siphon is reliably Can be formed.

  In the sixth feature configuration, in addition to any one of the first to fifth feature configurations described above, the second treated water path is branched from the first treated water path. This is in that the part has a rising part.

  When the exhaled water filled in the air vent tank is discharged through the third treated water path, the first treated water path becomes negative pressure and filtration of the membrane separation means is started. At this time, when the treated water flows from the membrane separation means into the first treated water path, the air that may stay in the internal space of the first treated water path and hinder rapid siphon formation rises together with the treated water. As a result, the siphon is quickly formed.

  In the seventh feature configuration, as described in claim 7, in addition to any of the first to sixth feature configurations described above, the flow path cross-sectional area of the second treated water path is the first treated water. This is because it is set smaller than the channel cross-sectional area of the path.

  Since the flow velocity of the fluid flowing through the second treated water path is higher than that of the first treated water path, air can be quickly extracted.

  The first characteristic configuration of the wastewater treatment method according to the present invention is a wastewater treatment method using the wastewater treatment apparatus having any one of the first to seventh characteristic configurations described above. The first treated water path is filled with treated water to form a siphon to obtain treated water from the membrane separation means, and gas is stored in the first treated water path. From the state where the siphon is not formed by the operation, the pump means is operated to guide the gas stored in the first treated water path to the air vent tank, thereby filling the first treated water path with the treated water. And a filtration operation return step for returning to a state where the filtration operation step is possible.

  In the filtration operation step, the treated water that has passed through the membrane separation means is stored in the treated water tank via the first treated water path by the siphon principle using the water head difference between the membrane separation layer and the treated water tank. Moreover, when air accumulates in the 1st treated water path | route and siphon collapses, the air of a 1st treated water path | route is discharged | emitted by a filtration driving | operation return process, and a siphon is re-formed.

  In addition to the first feature configuration described above, the second feature configuration includes a filtration operation stop step for stopping the flow of treated water in the first treated water path, as described in claim 9. An operation process and the filtration operation stop process are repeatedly executed, and the filtration operation process is configured to take out treated water from the membrane separation means at a constant flow rate through the first treated water path, and an execution time of the filtration operation. It is in the point comprised so that the quantity of the treated water filtered from to-be-processed water may be adjusted by adjusting.

  In order to avoid clogging of the filtration membrane provided in the membrane separation means, a membrane filtration operation step for taking out the treated water and a filtration operation stopping step for relaxing the filtration membrane by stopping the removal of the treated water are alternately performed. By the way, when the flow rate of the treated water flowing into the membrane separation tank fluctuates, if the flow rate of the treated water flowing through the first treated water path is varied in accordance with the variation, the first treated water in the low flow time zone. There is a possibility that the flow velocity of the path is lowered, and bubbles contained in the treated water are retained in the treated water tank due to the influence, and the formed siphon is destroyed. Even in such a case, by adjusting the execution time of the filtration operation, the treated water can be taken out at a constant flow rate from the membrane separation means while maintaining the flow rate of the first treated water path at a certain level or more, and flows into the membrane separation tank. Stable filtration operation can be realized while responding to fluctuations in the flow rate of treated water.

  As described above, according to the present invention, a wastewater treatment apparatus and a wastewater treatment method capable of discharging filtered water by a natural discharge path using the principle of siphon without using an expensive corrosion-resistant vacuum tank or vacuum pump. Can now be provided.

Explanatory drawing of the waste water treatment equipment by the present invention Explanatory drawing of the main part of the wastewater treatment equipment Explanatory drawing of the waste water treatment equipment which shows another embodiment Explanatory drawing of the waste water treatment equipment which shows another embodiment

Hereinafter, embodiments of a wastewater treatment apparatus and a wastewater treatment method according to the present invention will be described.
[Configuration of wastewater treatment equipment]
As shown in FIG. 1, the waste water treatment apparatus 100 includes a membrane separation tank 10 in which the membrane separation means 11 is immersed in the water to be treated, a treatment water tank 20 that stores the treated water filtered by the membrane separation means 11, A first treated water path 40 including a transfer pipe for transferring treated water from the membrane separation means 11 to the treated water tank 20 is provided.

  For example, the membrane separation means 11 is supported by a frame such that a plurality of membrane cartridges provided with an organic filtration membrane are placed in a vertical posture, and through a header pipe where treated water filtered by the membrane cartridge is collected. Therefore, a flat membrane type membrane separation device configured to flow out into the first treated water path 40 can be used.

  An air diffuser 12 is installed below the membrane separation means 11, and air supplied from the blower B is supplied to the air diffuser 12 via the flow rate adjusting valve V11, and the water to be treated is supplied by bubbles supplied to the water to be treated. As a result, an upward flow is generated in a flow parallel to the film surface, and the dirt accumulated on the film surface is peeled off.

  The liquid level L20 of the treated water tank 20 is lower than the liquid level L10 of the membrane separation tank 10, that is, the liquid level of the treated water stored in the membrane separation tank 10 is lower than the liquid level of the water to be treated in the membrane separation tank. The membrane separation tank 10 and the treated water tank 20 are installed so that the highest position (maximum installation height) of the first treated water path 40 is higher than the liquid level L10 of the water to be treated in the membrane separation tank 10. One treated water path 40 is arranged.

  The treated water filtered by the membrane separation means 11 is based on the siphon principle using the water head difference Δh between the liquid level L10 of the membrane separation tank 10 and the liquid level L20 of the treated water tank 20. A siphon forming mechanism is provided so as to flow out into the treated water tank 20 through 40.

  That is, the siphon forming mechanism includes a second treated water path 50 branched from the first treated water path 40 and connected to the treated water tank 20, an air vent tank 30 provided in the second treated water path 50, and an air vent. The third treated water path 60 that branches from the second treated water path 50 between the tank 30 and the treated water tank 20 and the treated water in the second treated water path 50 that is installed in the third treated water path 60 can be discharged. Pump means 61.

  The first treated water path 40 is provided with a pair of flow rate regulating valves V2, V3 for adjusting the flow rate of treated water, a siphon break valve V1, an on-off valve V12, a filtration pressure gauge S1, a filtration flow meter S2, and the like. Based on the value of the filtration pressure gauge S1, the degree of clogging of the filtration membrane is determined, and backwashing or chemical cleaning is performed as necessary. Moreover, the opening degree of the flow regulating valve V2 is adjusted based on the value of the filtration flow meter S2. A flow rate adjusting valve V3 is provided as a preliminary to cope with a failure of the flow rate adjusting valve V2. Therefore, the flow rate adjustment valve V3 is normally closed.

  The air vent tank 30 provided in the second treated water path 50 is provided with an atmosphere release valve V5. The open / close valve V4 is upstream of the air vent tank 30, the open / close valve V6 is downstream, and the third treated water path 60 is An on-off valve V7 is provided on the treated water tank 20 side from the branch portion.

  The third treated water path 60 is provided with a pump means 61, a check valve V8, and open / close valves V9, V10. By opening the open / close valve V9 with the open valve V10 closed, the third treated water path 50 Water is discharged out of the system.

  Further, by opening the on-off valve V10 with the release valve V9 closed, the chemical supply for supplying the cleaning chemical filled in the air vent tank 30 to the membrane separation means 11 via the first treated water path 40. A path 70 is provided. The chemical solution supply path 70 will be described later.

[Configuration of wastewater treatment method]
The process for forming a siphon is described below.
In the initial stage when there is no treated water in the treated water tank 20, first, the treated water tank 20 is filled with activation water. Next, the siphon break valve V1 and the open / close valve V12 are closed, and the atmosphere release valve V5, the open / close valves V4, V6, and V7 of the air vent tank 30 are opened to fill the air vent tank 30 from the treated water tank 20. To do. By opening the air vent tank to the atmosphere, prior to filtration, the air vent tank 30 is filled with exhaled water without causing fluctuations in the internal pressure of the treated water paths 40 and 50 connected to the air vent tank 30. become able to. That is, the atmosphere release valve V5 functions as the atmosphere release means of the present invention.

  Next, the air release valve V5 and the opening / closing valve V7 are closed, and the flow rate adjustment valve V2 is opened slightly to open the pump means 61 provided in the third treated water path 60. At this time, the release valve V10 is closed and the on-off valve V9 is opened. As the expiratory water in the air vent tank 30 is sucked and discharged by the pump means 61, the first treated water path 40 becomes negative pressure, and filtration of the treated water by the membrane separation means 11 is started.

  As a result of the flow of filtered water flowing from the membrane separation means 11 to the first treated water path 40, the air in the first treated water path 40 is discharged via the second treated water path 50 and the third treated water path 60. One treated water path 40 is filled with treated water and a siphon is formed between the membrane separation means 11 and the treated water tank 20, and then the pump means 61 is stopped, the on-off valve V4 is closed, and the on-off valve V12 is opened. Therefore, membrane filtration is continuously performed.

  As shown in FIG. 2, a rising portion 52 is formed at a branch portion from the first treated water path 40 to the second treated water path 50. When the expelled water filled in the air vent tank 30 is discharged through the third treated water path 60, the first treated water path 40 becomes negative pressure, and the filtration of the membrane separation means 11 is started. At this time, when treated water flows from the membrane separation means 11 into the first treated water path 40, air that may stay in the internal space of the first treated water path 40 and hinder rapid siphon formation is treated water. At the same time, since it flows into the rising portion 52, a siphon is quickly formed.

  The on-off valve V7 functions as a flow rate adjusting means, and the on-off valve V7 opens the flow path between the connection portion of the third treated water path 60 and the treated water tank 20, thereby calling the air vent tank 30 from the treated water tank 20. Water can be supplied, and the flow path is closed by the on-off valve V7 to discharge expiratory water from the air vent tank 30 through the third treated water path 60 and draw air in the third treated water path 60. It can be pulled out.

  When the flow rate adjustment valve V2 is closed in this state, a relaxation state is reached in which membrane filtration stops while being diffused from the diffuser 12, and the membrane surface is washed by the upward flow of the water to be treated. At this time, since the inside of the first treated water path 40 is maintained filled with treated water, membrane filtration is resumed when the flow rate control valve V2 is opened. In addition, it will be in a relaxation state also when the siphon formed by air flowing into the first treated water path 40 is broken by opening the siphon break valve V1 during membrane filtration.

  That is, in the wastewater treatment apparatus 100, a filtration operation step in which treated water is filled in the first treated water path 40 to form treated siphon to obtain treated water from the membrane separation means 11, and in the first treated water path 40. From the state in which the siphon is not formed by storing the gas, the pump means 61 is operated to guide the gas stored in the first treated water path 40 to the air vent tank 30, thereby causing the first treated water path 40. A filtration operation return step is performed in which the treated water is filled to return to a state where the filtration operation step is possible.

  In addition, a filtration operation stop process for stopping the flow of treated water in the first treated water path 40 is provided, the filtration operation process and the filtration operation stop process are repeatedly executed, and the filtration operation process is performed via the first treated water path 40. The configuration is such that the treated water is taken out from the membrane separation means 11 at a constant flow rate, and the amount of treated water that is filtered from the treated water is adjusted by adjusting the execution time of the filtration operation.

  When the flow rate of the water to be treated flowing into the membrane separation tank 10 is constant, the membrane filtration operation step for taking out the treated water and the removal of the treated water in order to avoid clogging of the filtration membrane provided in the membrane separation means 11 The filtration operation stop process of stopping the process and relaxing the filter membrane is alternately performed at predetermined time intervals. For example, a membrane filtration operation process for 9 minutes and a filtration operation stop process for 1 minute are repeatedly performed in units of 10 minutes.

  However, when the flow rate of the water to be treated flowing into the membrane separation tank 10 varies, if the flow rate of the treated water flowing through the first treated water path 40 is varied in accordance with the variation, There is a possibility that the siphon may collapse due to the occurrence of an airlock phenomenon on the downstream side of the first treated water path 40 due to the influence of contained bubbles. Therefore, the flow rate of the water to be treated flowing into the membrane separation tank 10 is operated so as to maintain the instantaneous flow rate during filtration at a constant speed (in this embodiment, 0.8 m / second or more).

  However, even in such a case, by adjusting the execution time of the filtration operation, the treated water can be taken out from the membrane separation means 11 at a constant flow rate, and it corresponds to the flow rate fluctuation of the treated water flowing into the membrane separation tank 10. However, stable filtration operation can be realized.

  Specifically, when the flow rate of the water to be treated flowing into the membrane separation tank 10 is small, the time for the filtration operation stop process is set long, and when the flow rate of the water to be treated flowing into the membrane separation tank 10 is large By setting the time of the filtration operation stop process short, the instantaneous flow rate of the treated water flowing through the first treated water path 40 is kept constant regardless of the fluctuation of the flow rate of the treated water flowing into the membrane separation tank 10. be able to.

  The capacity of the internal space of the air bleed tank 30 described above needs to be set to a value larger than the capacity of the flow path space of the first treated water path 40, and the first process is performed by setting in this way. The entire amount of air staying in the internal space of the water path 40 is sucked to ensure siphon formation.

  Moreover, it is preferable that the flow path cross-sectional area of the 2nd treated water path | route 50 is set smaller than the flow path cross-sectional area of the 1st treated water path | route 40, and by setting in this way, 1st treated water Since the flow velocity of the fluid flowing through the second treated water path 50 is higher than that of the path 40, air can be quickly extracted.

[Method of membrane cleaning]
Next, the cleaning of the membrane separation means 11 will be described.
When the value of the filtration pressure gauge S1 becomes larger than a preset pressure, the membrane separation means 11 cannot properly filter the water head difference Δh. In preparation for such a case, the waste water treatment apparatus 100 can perform a chemical cleaning step of cleaning the membrane by injecting a cleaning chemical from the first treated water path 40 toward the inside of the membrane separation means 11. It is configured as follows. For example, a dilute solution of sodium hypochlorite can be used as the cleaning solution.

  In the chemical cleaning process, first, the siphon break valve V1 is opened, and the process proceeds from the filtration operation process to the filtration operation stop process. When the flow control valve V2, the on-off valves V4, V6, V7, V9, and V12 are closed, the air vent tank 30 is filled with a chemical solution, and then the atmosphere release valve V5 and the on-off valves V6 and V7 are opened. The treated water flows into the air vent tank 30 and the chemical solution is diluted.

  When diluted to a predetermined concentration, the on-off valve V7 and the siphon break valve V1 are closed and the on-off valve V10 is opened to start the pump means 61. The cleaning chemical liquid flows from the air vent tank 30 into the first treated water path 40 via the second treated water path 50, the third treated water path 60, and the chemical liquid supply path 70, and is further supplied to the membrane separation means 11 to form the membrane. Washed. That is, the air vent tank 30 functions as a cleaning chemical solution storage tank.

  When the cleaning is completed, the air release valve V5 and the on-off valve V10 are closed, and the on-off valves V4 and V9 flow rate adjusting valve V2 are opened to start the pump means 61, so that the cleaning waste liquid passes through the third treated water path 60. Discharged. Then, it transfers to a filtration operation process by performing a filtration operation return process.

  The cleaning waste liquid discharged through the third treated water path 60 is returned to the biological treatment tank on the upstream side of the membrane separation tank 10.

  A magnetic pump having corrosion resistance can be suitably used as the pump means 61, and water leakage due to deterioration of the bearing or the like due to chlorine components contained in the cleaning chemical solution can be avoided even when used over time.

[Other configurations of wastewater treatment equipment for membrane cleaning]
As shown in FIG. 3, the third treated water path 60 may be connected to the chemical tank 80 via the on-off valve V13.

  The treated water stored in the treated water tank 20 is supplied to the chemical liquid tank 80 via the third treated water path 60 by the pump means 61 and diluted to a predetermined concentration, and then the diluted chemical liquid is first treated via the chemical liquid supply path 70. You may comprise so that it may flow into the water path 40 and may be supplied to the membrane separation means 11, and a membrane | film | coat may be wash | cleaned.

  That is, the third treated water path 60 is connected to the cleaning liquid storage tank 80 or the first treated water path 40 that stores the cleaning liquid of the membrane separation means 11.

  In the embodiment described above, the wastewater treatment apparatus 100 including one air vent tank 30 in one water treatment system in which treated water is sent from the membrane separation means 11 to the treated water tank 20 via the first treated water path 40. Although described, a plurality of water treatment systems may be provided so that each water treatment system is processed by one air vent tank 30.

  What is necessary is just to comprise so that the 2nd treated water path | route 50, the air bleeding tank 30, and the 3rd treated water path | route 60 may be combined, and time may be varied with respect to each system | strain, and a filtration driving | operation return process may be performed.

  In the above-described embodiment, in the process for forming the siphon, the flow rate adjustment valve V2 is operated to fill the first treated water path 40 of each system with treated water, but even if the on-off valve V12 is operated. Alternatively, both the flow rate adjustment valve V2 and the on-off valve V12 may be operated. That is, the treated water for satisfying the first treated water path 40 of each system may be treated water stored in each treated water tank 20, and treated water filtered by each membrane separation means 11 and each treated water tank. Both of the treated water stored in 20 may be used.

[Configuration for automatic operation of wastewater treatment equipment]
As shown in FIG. 4, a liquid level sensor S3 is provided in the bleed tank 30, and the detection values of the sensors S1, S2, S3 are input, and the opening / closing and opening of each valve are adjusted based on the detected values. By providing a control device that controls the start and stop of the pump means, the above-described filtration operation return step, filtration operation step, filtration operation stop step, and the like may be automatically performed.

  The control device adjusts the filling amount of expiratory water according to the liquid level sensor S3 when executing the filtration operation return step, and adjusts the filling amount of the cleaning chemical according to the liquid level sensor S3 when performing the chemical solution cleaning step.

  In FIG. 4, a valve denoted by a symbol M is a motor-driven automatic valve and is remotely controlled by a control device. Moreover, it is preferable that the pump means and the check valve are redundantly installed in preparation for failure.

  As the filtration membrane provided in the membrane separation means 11 described above, an ultrafiltration membrane, a microfiltration membrane or the like is used. In addition to a flat membrane, a hollow fiber membrane or the like can be used as the membrane form.

  Each of the above-described embodiments is an example of the present invention, and the present invention is not limited by the description. The specific configuration of each part can be appropriately changed and designed within the range where the effects of the present invention are exhibited. Needless to say.

100: Waste water treatment device 10: Membrane separation tank 11: Membrane separation means 12: Aeration device 20: Treated water tank 30: Air vent tank 40: First treated water path 50: Second treated water path 60: Third treated water path 61: Pump means 70: Chemical solution supply path 80: Chemical solution tank V1: Siphon break valves V2, V3: Flow rate adjusting valves V4, V6, V7: On-off valve V5: Atmospheric release valve

Claims (9)

A wastewater treatment apparatus equipped with membrane separation means,
A membrane separation tank in which the membrane separation means is immersed in the water to be treated;
The treated water filtered by the membrane separation means is stored, and the treated water tank disposed so that the stored treated water level is lower than the treated water level of the membrane separation tank,
A first treated water path that is disposed such that the highest position is higher than the level of the water to be treated in the membrane separation tank, and connects the membrane separation means and the treated water tank;
It branches from said 1st treated water path | route, and is connected to the said treated water tank through the air vent tank arrange | positioned so that the lowest part of internal space may become a position lower than the liquid level of the treated water of the said treated water tank A second treated water path;
A third treated water path that is branched from the second treated water path between the air vent tank and the treated water tank and connected to pump means capable of discharging treated water in the second treated water path;
Wastewater treatment equipment equipped with.   The wastewater treatment apparatus according to claim 1, wherein the air vent tank is provided with an air release means.   The wastewater treatment apparatus according to claim 1 or 2, further comprising a flow rate adjusting means capable of opening and closing a flow path between a connection portion of the third treated water path and the treated water tank in the second treated water path.   The wastewater treatment apparatus according to any one of claims 1 to 3, wherein the third treated water path is connected to a cleaning liquid storage tank that stores the cleaning liquid of the membrane separation unit or the first treated water path.   The wastewater treatment apparatus according to any one of claims 1 to 4, wherein a capacity of an internal space of the air vent tank is set to a value larger than a capacity of a flow path space of the first treated water path.   The wastewater treatment apparatus according to any one of claims 1 to 5, wherein the second treated water path includes a rising portion at a branch portion from the first treated water path.   The wastewater treatment apparatus according to any one of claims 1 to 6, wherein a flow path cross-sectional area of the second treated water path is set smaller than a flow path cross-sectional area of the first treated water path. A wastewater treatment method using the wastewater treatment apparatus according to any one of claims 1 to 7,
Filtration operation step of obtaining treated water from the membrane separation means by forming siphon by filling the first treated water path with treated water;
The gas stored in the first treated water path leads the gas stored in the first treated water path to the air vent tank by operating the pump means from a state where no siphon is formed. Filtration operation return step of returning the state where the filtration operation step is possible by filling the first treated water path with the treated water,
Effluent treatment method. A filtration operation stop process for stopping the flow of treated water in the first treated water path is provided, the filtration operation process and the filtration operation stop process are repeatedly performed, and the filtration operation process is performed via the first treated water path. Configured to extract treated water from the membrane separation means at a constant flow rate,
The wastewater treatment method according to claim 8, wherein the amount of treated water filtered from the treated water is adjusted by adjusting an execution time of the filtration operation.

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