JP2010194482A - Membrane separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane separator capable of stably discharging of a filtrate by a natural discharge route and capable of smoothly charging over the natural discharge route to a forcible discharge route. <P>SOLUTION: The membrane separator 6 includes a membrane separation tank 4 to which a solution to be treated is supplied, the filter membrane 6a arranged in the membrane separation tank 4 so as to be immersed in the solution to be treated and a discharge mechanism 20 for discharging the filtrate, which is subjected to solid-liquid separation treatment by the filter membrane 6a, to the water storage tank 12 installed outside the membrane separation tank 4. The discharge mechanism 20 includes a natural discharge pipe 21 discharging the filtrate by the head difference across the inside and outside of the membrane separation tank 4, the forcible discharge pipe 23 equipped with a pump 24 sucking the filtrate, and solenoid valves 29a and 29b as a route changeover mechanism for discharging the filtrate from either one of the natural discharge pipe 21 and the forcible discharge pipe 23. A gas-liquid separation tank 25 for separating air getting mixed in the filtrate is provided to the natural discharge pipe 21. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a treatment tank to which a liquid to be treated is supplied, a filtration membrane immersed in the treatment tank, and a discharge mechanism for discharging the filtrate separated by solid-liquid separation with the filtration membrane to the outside of the tank. The present invention relates to a membrane separator.

  As shown in FIG. 8, conventionally, a filtration membrane 81 immersed in a membrane separation tank 85, a forced discharge pipe provided with a pump 83 in a natural discharge pipe 82 that discharges the processing liquid in the filtration membrane 81 to a storage tank 90. 84, and a natural discharge pipe on the basis of the measured values of a liquid level meter 86 provided in the membrane separation tank 85 and a flow meter 88 provided in a supply pipe 87 of water to be treated to the membrane separation tank 85. A membrane separation device 80 configured to switch the discharge of the filtrate through the natural discharge pipe 82 and the forced discharge pipe 84 by controlling the opening and closing of the open / close valves 89a and 89b provided in the 82 and the forced discharge pipe 84, respectively. Proposed.

  The storage tank 90 is disposed so that the liquid level of the storage tank 90 is lower than the liquid level of the membrane separation tank 85, and stored from the membrane separation tank 85 through the natural discharge pipe 82 using the water head difference between the two liquid levels. The filtrate is drained into the tank 90. Therefore, the natural discharge pipe 82 and the forced discharge pipe 84 are also disposed at a position lower than the liquid level of the membrane separation tank 85. And if the to-be-processed water which flows into the membrane separation tank 85 increases, or if the liquid level of the membrane separation tank 85 becomes high, the on-off valves 89a and 89b are controlled, and the forced discharge pipe 84 is activated by starting the pump 83. The filtrate is discharged stably by forcibly discharging the filtration membrane.

JP 2002-143847 A

  However, since the water to be treated filtered by the filtration membrane 81 contains air bubbles, the flow rate flowing down the natural discharge pipe 82 or the forced discharge pipe 84 to the storage tank 90 becomes unstable. was there. In particular, if the natural discharge pipe 82 is arranged in an arch shape and there is a piping part higher than the liquid level of the membrane separation tank 85, there is a possibility that the drainage is interrupted by bubbles.

  In addition, facilities such as membrane separation tanks are constructed in the area excavated in the ground, and pump facilities etc. are arranged in the vicinity, but when expanding or updating existing facilities, cost control and installation Due to various factors such as limited space, the pump equipment and the discharge pipe may not be installed below the liquid level of the membrane separation device.

  In such a case, the pump equipment, a part of the natural discharge pipe and the forced discharge pipe are installed on the slab located above the liquid level of the membrane separator, but the natural discharge pipe discharges the filtrate. Even when trying to do so, the filtrate is aerated by the aeration device in the membrane separation tank and contains a large amount of air, so the air in the filtrate is deposited in the natural discharge pipe, and the discharge of the filtrate through the natural discharge pipe is interrupted. There was a problem that the filtrate could not be discharged stably.

  Furthermore, even if the pump is started and the filtrate is discharged through the forced transfer pipe, there is a problem that priming water is required at the time of starting the pump, and the filtrate contains a large amount of air as described above. Even with this type of pump, there was a problem that it could not be self-primed by air lock. In addition, the cavitation may become intense and the pump may be damaged.

  An object of this invention is to provide the membrane separator which can discharge | emit the filtrate by a natural discharge path stably, and can perform switching from a natural discharge path to a forced discharge path smoothly.

  In order to achieve the above-mentioned object, the first characteristic configuration of the membrane separation apparatus according to the present invention is as described in claim 1 of the present invention. And a membrane separation device provided with a discharge mechanism for discharging the filtrate separated by solid-liquid separation with the filtration membrane to the outside of the tank, wherein the discharge mechanism is a water head inside and outside the treatment tank. A natural discharge path for discharging the filtrate due to the difference, a forced discharge path including a pump for sucking the filtrate, and a path switching mechanism for discharging the filtrate from either the natural discharge path or the forced discharge path In the natural discharge path, a gas-liquid separation unit for separating air mixed in the filtrate is provided.

  According to the above configuration, since the gas / liquid separation unit is provided in the natural discharge path, when the filtrate is discharged through the natural discharge path, air mixed in the filtrate is separated by the gas / liquid separation unit. The natural discharge path is not interrupted, and the flow rate of the filtrate can be stabilized. When increasing the transfer amount, forced discharge by the pump can be performed by switching from the natural discharge path to the forced discharge path by the path switching mechanism.

  As described in the second aspect, the second characteristic configuration is that, in addition to the first characteristic configuration described above, the forced discharge path is connected to the gas-liquid separation unit.

  According to the above configuration, the air mixed in the forced discharge path is separated by the gas-liquid separation unit, so that the transfer flow rate can be stabilized. In addition, since a part of the forced discharge path can be used also as the natural discharge path, it is possible to reduce the parts of the discharge pipe and the construction cost, and to make the equipment compact.

  The third feature configuration is that, in addition to the second feature configuration described above, the discharge-side path of the pump is connected to the gas-liquid separation unit as described in the third aspect.

  According to the above-described configuration, the air in the forced discharge path accumulates in the gas-liquid separation part provided in the discharge side path of the pump, so that the air can accumulate in the suction side path of the pump and the inside of the pump when the pump is stopped. This eliminates the possibility of air lock occurring when the pump is restarted.

  In the fourth feature configuration, as described in claim 4, in addition to the second or third feature configuration described above, when switching to the forced discharge path, the liquid level of the gas-liquid separation unit is the pump level. It is in the point above the discharge part.

  According to the above-described configuration, if the filtrate is stored so that the liquid level of the gas-liquid separation unit is higher than the discharge unit of the pump during the discharge of the filtrate through the natural discharge path, Since the filtrate flows into the forced drain path and the forced drain path is filled with filtrate, there is no need for priming water to start the pump when switching from the natural drain path to the forced drain path, and forced drain from the natural drain path. Switching to a route can be performed smoothly.

  In addition to the second or third characteristic configuration described above, the fifth characteristic configuration includes the pump for sucking filtrate in the natural discharge path, and the forced discharge path is configured as described in claim 5. It is in the point.

  According to the above-described configuration, the forced discharge path is configured with the pump for sucking the filtrate in the natural discharge path, so that the natural discharge path is provided when the pump is stopped, and the forced discharge path is provided while the pump is operating. Thus, the natural discharge route and the forced discharge route can be used together. The pump functions as a path switching mechanism that discharges the filtrate from either the natural discharge path or the forced discharge path. Accordingly, it is possible to reduce the parts of the discharge pipe and the construction cost, and to make the equipment compact.

  In addition to any one of the first to fifth feature configurations described above, the sixth feature configuration is a liquid level meter that measures the liquid level of the gas-liquid separation unit, as described in claim 6; An exhaust mechanism for sucking and exhausting air from the gas-liquid separation unit based on the liquid level measured by the liquid level gauge is provided.

  According to the above-described configuration, the filtrate is stored in the gas-liquid separation part via the natural discharge path by sucking and exhausting the air in the gas-liquid separation part by the exhaust mechanism and making the inside of the gas-liquid separation part have a negative pressure. Then, by raising the liquid level of the gas-liquid separation unit to a predetermined liquid level, it is possible to start discharging the filtrate through the natural discharge path. Furthermore, for example, even if air in the filtrate separated by the gas-liquid separation unit accumulates and the liquid level of the gas-liquid separation unit decreases, the air in the gas-liquid separation unit is discharged by the exhaust mechanism based on the measured water level of the liquid level gauge. Is sucked and exhausted, so that the liquid level of the gas-liquid separator is kept at a predetermined level, and the discharge of the filtrate by the natural discharge mechanism can be easily maintained.

  Further, when the fourth characteristic configuration is provided, by adjusting the liquid level of the filtrate of the gas-liquid separation unit by the exhaust mechanism so as to be higher than the discharge unit of the pump provided in the forced discharge path, It is possible to smoothly switch the filtrate discharge from the natural discharge path to the forced discharge path.

  In the seventh feature configuration, in addition to any of the first to sixth feature configurations described above, an automatic valve that is opened to the atmosphere in the event of a power failure is provided in the gas-liquid separation unit. The opening mechanism is provided.

  The open mechanism opens the automatic valve in the event of a power failure, opens the gas-liquid separation part to the atmosphere, and functions as a siphon break that stops the discharge of the filtrate through the natural discharge path, so that the filtrate is being discharged through the natural discharge path. When a power failure occurs, the discharge of the filtrate can be automatically stopped to obstruct the filtration membrane.

  In addition, when the pressure in the natural discharge path falls below the set value, the automatic valve opens to function as an air release mechanism that opens the gas-liquid separation unit to the atmosphere. It is possible to prevent accidents that cause damage.

  In the eighth feature configuration, as described in claim 8, in addition to the third feature configuration described above, an open mechanism that opens the gas-liquid separation unit to the atmosphere and a liquid level of the gas-liquid separation unit are measured. A liquid level meter, an open / close mechanism that opens and closes the filtrate outlet of the gas-liquid separator, and when the liquid level measured by the liquid level meter falls below a predetermined value, the pump is operated and the gas-liquid is A control unit is provided that opens the separation unit to the atmosphere and closes the opening / closing mechanism to recover the liquid level of the gas-liquid separation unit.

  According to the above configuration, the control unit closes the filtrate outlet of the gas-liquid separation unit by the opening / closing mechanism and opens the gas-liquid separation unit to the atmosphere by the opening mechanism when the liquid level measured by the liquid level gauge becomes a predetermined value or less. At the same time, the pump provided in the forced discharge path is operated to transfer the filtrate into the gas-liquid separation unit and recover the liquid level of the gas-liquid separation unit. Even if a mechanism is not provided, the air in the gas-liquid separation unit can be exhausted while the siphon is maintained.

  As described above, according to the present invention, there is provided a membrane separation apparatus that can stably discharge filtrate through a natural discharge path and can smoothly switch from the natural discharge path to the forced discharge path. I was able to do that.

Explanatory drawing of the sewage treatment apparatus by this invention Explanatory drawing of the membrane separation apparatus by this invention Illustration of the control unit Explanatory drawing of 2nd embodiment of a membrane separator Explanatory drawing of 3rd embodiment of a membrane separator Explanatory drawing of 4th embodiment of a membrane separator Explanatory drawing of 5th embodiment of a membrane separator Illustration of a conventional membrane separation device

Hereinafter, an embodiment when the membrane separation device according to the present invention is applied to a sewage treatment device will be described.
As shown in FIG. 1, the sewage treatment apparatus 100 includes an anaerobic tank 1 into which raw water, which is untreated water to be treated, an anaerobic tank 2 adjacent to the downstream side of the anaerobic tank 1, and an anaerobic tank 2. The aerobic tank 3 adjacent to the downstream side is constituted by being separated by a partition wall.

  In the anaerobic tank 1, anaerobic treatment is performed by microorganisms under anaerobic conditions, and BOD components contained in the raw water are taken into the microorganisms, and phosphorus compounds are hydrolyzed to form normal phosphoric acid and phosphorus is released into the liquid.

  In the anaerobic tank 2, the water to be treated flowing from the anaerobic tank 1 is subjected to anaerobic treatment by microorganisms under anaerobic conditions, and nitrate ions and nitrite ions are reduced to nitrogen gas, that is, denitrification treatment is performed.

  In the aerobic tank 3, an air diffuser 3a is installed at the bottom, and ammonium ions derived from human urine and the like contained in the water to be treated flowing in from the anaerobic tank 2 are oxidized by microorganisms under aerobic conditions. Nitric acid or a nitrification treatment that converts to nitric acid is performed, and further, an aerobic treatment is performed in which normal phosphoric acid in the water to be treated is taken into sludge and accumulated as polyphosphoric acid.

  The water to be treated biologically treated in each of the treatment tanks 1, 2, 3 is transferred to the downstream side through an opening formed in the lower part of the partition wall, or is transferred to the downstream side after overflowing the partition wall.

  The water to be treated that has been aerobically treated in the aerobic tank 3 is filtered by the membrane separation device 6 adjacent to the downstream side of the aerobic tank 3 and further discharged to the water storage tank 7 on the downstream side.

  The membrane separation device 6 includes a membrane separation tank 4 as a treatment tank to which a liquid to be treated is supplied, a filtration membrane 6a immersed in the membrane separation tank 4, and a filtrate obtained by solid-liquid separation with the filtration membrane 6a. A discharge mechanism 20 for discharging to the water storage tank 7 is provided.

  As the filtration membrane 6a, an ultrafiltration membrane, a microfiltration membrane, or the like is employed. As the form of the membrane, a flat membrane, a tubular membrane, a hollow fiber membrane or the like is preferably used.

  The membrane separation tank 4 includes a liquid level meter 4b that detects the liquid level of the membrane separation tank 4 and an excess sludge discharge pipe 5 that discharges excess sludge. Further, an air diffuser 4a is disposed below the filtration membrane 6a.

  The air diffuser 4a applies a flow velocity parallel to the membrane surface to the water to be treated by air supplied from a blower (not shown) to peel off dirt substances accumulated on the membrane surface, and to remove the dirt in the membrane separation tank 4. Oxygen is supplied to the activated sludge contained in the treated water. As a result, the inside of the membrane separation tank 4 is in an aerobic condition, and the activated sludge nitrifies the water to be treated.

  Further, the sewage treatment apparatus 100 circulates the treated water in the membrane separation tank 4 to the aerobic tank 3 and the first circulation path 8 for circulating the treated water in the membrane separation tank 4 to the anoxic tank 2. A second circulation path 9 and a third circulation path 10 for circulating the water to be treated in the anaerobic tank 2 to the anaerobic tank 1 are provided.

  As shown in FIG. 2, the discharge mechanism 20 includes a natural discharge pipe 21 serving as a natural discharge path for discharging the filtrate due to a water head difference between the inside and outside of the membrane separation tank 4, and a forced pump 24 that sucks the filtrate. A forced discharge pipe 23 serving as a discharge path, and switching valves 29a and 29b serving as a path switching mechanism that discharges filtrate from either the natural discharge pipe 21 or the forced discharge pipe 23 are provided.

  One end of the natural discharge pipe 21 and the forced discharge pipe 23 is disposed on the filtrate side of the filtration membrane 6 a, and the other end is opened to the water storage tank 7.

  The natural discharge pipe 21 is provided with a gas-liquid separation tank 25 as a gas-liquid separation unit that separates air mixed in the filtrate at a position higher than the membrane separation tank 4. A liquid level meter 26 for measuring the liquid level in the separation tank 25, and a vacuum pump 27a and an automatic valve 27b as an exhaust mechanism for sucking and exhausting air in the gas-liquid separation tank 25 based on the measured liquid level of the liquid level meter 26 In addition, an opening mechanism including an automatic valve 28 that is opened at the time of a power failure and opens the gas-liquid separation tank 25 to the atmosphere, and a pressure gauge 70 that detects the pressure of a gas portion in the gas-liquid separation tank 25 are provided.

  Further, the natural discharge pipe 21 includes an opening / closing valve 22 as an opening / closing mechanism for opening / closing the filtrate outlet of the gas / liquid separation tank 25 on the downstream side of the gas / liquid separation tank 25.

  The automatic valves 27b and 28 are constituted by, for example, electromagnetic valves that are controlled to be opened and closed by the control unit 12.

  The switching valves 29a and 29b and the opening / closing valve 22 may be any valves that can pass and shut off the treated water flowing through the pipe. For example, gate valves, globe valves, ball valves, butterfly valves, needle valves, stop valves, etc. are suitable. Used for. Furthermore, the valve is preferably one that is electrically controlled to open and close from the viewpoint of automation of the apparatus, but may be one that is manually opened and closed by an operator.

  As shown in FIG. 3, the controller 12 starts and stops the vacuum pump 27a, opens and closes the automatic valve 27b, and switches the switching valves 29a and 29b based on signals from the liquid level gauge 4b, the liquid level gauge 26, and the pressure gauge 70. Control of opening / closing, opening / closing of the suction pump 24, opening / closing of the opening / closing valve 22, and opening / closing of the automatic valve 28.

  The automatic valve 28 is configured to be closed by power supply from the control unit 12, opened when power supply from the control unit 12 is stopped during a power failure, and the gas-liquid separation tank 25 is opened to the atmosphere. Further, the control unit 12 opens the automatic valve 28 when detecting that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become a set value or less, and controls the gas-liquid separation tank 25 to be opened to the atmosphere. Has been.

  Accordingly, even if the facility in which the membrane separation device 6 is installed is out of power and the diffuser 4a that performs filtration membrane cleaning stops, the automatic valve 28 opens and the gas-liquid separation tank 25 is opened to the atmosphere. The filtration can be stopped immediately, the membrane can be prevented from being blocked, and the overflow of the water tank 7 can be avoided.

  Further, when the control unit 12 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become equal to or lower than the set value, the control unit 12 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to open to the atmosphere. Therefore, for example, an abnormal negative pressure state in the gas-liquid separation tank 25 is detected due to the operation of the vacuum pump 27a in the closed state due to clogging of the filtration membrane 6a, failure of the switching valve 29a, the opening / closing valve 22, or the like. Therefore, it is possible to prevent an accident such as the pressure in the gas-liquid separation tank 25 and the natural transfer pipe 21 from being extremely lowered and collapsing.

  The control unit 12 may monitor the current and voltage of the vacuum pump 27a and detect an abnormal negative pressure state in the gas-liquid separation tank 25.

  When drainage by the natural discharge pipe 21 is started in a state where the liquid level in the gas-liquid separation tank 25 is below the lowest water level LWL that can be transferred by the natural discharge pipe 21, the switching valve 29a is opened, the switching valve 29b, and the open / close valve 22 is closed. The automatic valve 27b is opened, the vacuum pump 27a is started, and the air in the gas-liquid separation tank 25 is discharged to the outside, whereby the pressure in the gas-liquid separation tank 25 is made negative. Then, treated water is stored in the gas-liquid separation tank 25 through the natural discharge pipe 21. The on-off valve 22 may be left open.

  When the liquid level meter 26 detects the high water level HWL of the liquid level in the gas-liquid separation tank 25, the automatic valve 27b is closed, the vacuum pump 27a is stopped, and the open / close valve 22 is opened. At this time, the natural discharge pipe 21 upstream of the gas-liquid separation tank 25 is filled with treated water.

  Then, the treated water filtered by the filtration membrane 6a of the membrane separation device 6 by the principle of siphon due to the water head pressure difference according to the water head difference between the liquid level of the membrane separation tank 4 and the liquid level of the water storage tank 7 is a natural discharge pipe 21. It is naturally transferred to the water tank 7 through it.

  When the liquid level in the gas-liquid separation tank 25 reaches the lowest water level LWL that can be transferred by the natural discharge pipe 21 from the start of the discharge of air in the gas-liquid separation tank 25 by the vacuum pump 27a, the open / close valve 22 is opened. An operation method is also possible in which the vacuum pump 27a is stopped when the liquid level in the gas-liquid separation tank 25 reaches the high water level HWL by opening and starting filtration.

  As described above, when the treated water flows into the natural discharge pipe 21, no power is required for transferring the treated water, which is economical. The treated water stored in the water tank 7 is appropriately drained through the drain pipe 11.

  When the liquid level in the gas-liquid separation tank 25 detected by the liquid level meter 26 detects the lowest water level LWL that can be transferred by the natural discharge pipe 21, the control unit 12 opens the automatic valve 27b and operates the vacuum pump 27a. The air in the liquid separation tank 25 is discharged to recover the liquid level. At this time, the on-off valve 22 or the switching valve 29a as an opening / closing mechanism for opening and closing the filtrate outlet of the gas-liquid separation tank 25 may be closed to stop the filtration, or the filtration may be continued while being opened. .

  When the liquid level meter 4b detects the low water level LWL of the liquid level in the membrane separation tank 4, the control unit 12 closes the switching valve 29a and stops discharging the filtrate through the natural transfer pipe 21. It is also possible to open the automatic valve 28, open the gas-liquid separation tank 25 to the atmosphere, and stop the discharge of the filtrate through the natural transfer pipe 21.

  When forcibly discharging treated water through the forced discharge pipe 23, the control unit 12 closes the switching valve 29a, opens the switching valve 29b, and activates the suction pump 24.

  The natural discharge pipe 21 and the forced discharge pipe 23 may be switched to the forced discharge pipe 23 when the liquid level meter 4b detects an abnormally high water level HHWL.

  Note that the vacuum pump 27a and the automatic valve 27b for discharging the air in the gas-liquid separation tank 25 are not necessarily provided, and an operator pours treated water into the gas-liquid separation tank 25, for example. You may fill treated water.

  Further, the gas-liquid separation unit does not need to be a tank such as the gas-liquid separation tank 25, and a portion enlarged in diameter by a reducer is provided in the pipe constituting the natural discharge pipe 21, and the enlarged part is gas-liquid separated. It is good also as a part.

  In this embodiment, the opening / closing valve 22 is provided in the lower part of the gas-liquid separation tank 25. However, as described above, the opening / closing valve 22 can be operated in an always open state, and therefore the opening / closing valve 22 is not necessarily provided. .

  Next, a second embodiment will be described. The same or corresponding parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof is omitted.

  As shown in FIG. 4, the discharge mechanism 30 includes a natural discharge pipe 31 as a natural discharge path for discharging the filtrate due to a water head difference between the inside and outside of the membrane separation tank 4, and a suction pump 34 for sucking the filtrate. A forced discharge pipe 33 serving as a discharge path and switching valves 39a and 39b serving as a path switching mechanism for discharging filtrate from either the natural discharge pipe 31 or the forced discharge pipe 33 are provided.

  The natural discharge pipe 31 is provided with a gas-liquid separation tank 25 as a gas-liquid separation unit that separates air mixed in the filtrate at a position higher than the membrane separation tank 4.

  One end of the natural discharge pipe 31 is disposed on the filtrate side of the filtration membrane 6 a, the other end is opened to the water storage tank 7, and the forced discharge pipe 33 has a suction side of the suction pump 34 on the downstream side of the gas-liquid separation tank 25. The natural discharge pipe 31 is connected to the gas-liquid separation tank 25 side, and the discharge side of the suction pump is the natural discharge pipe 31 downstream of the gas-liquid separation tank 25 and is connected to the water storage tank 7 side.

  The switching valves 39a and 39b serving as a path switching mechanism for discharging the filtrate from either the natural discharge pipe 31 or the forced discharge pipe 33 may be used as an opening / closing valve serving as an opening / closing mechanism for opening / closing the filtrate outlet of the gas-liquid separation tank 25. Configured to work.

  Based on the signals from the liquid level gauge 4b, the liquid level gauge 26, and the pressure gauge 70, the control unit 13 (not shown) serves as a start / stop of the vacuum pump 27a, opening / closing of the automatic valve 27b, a path switching mechanism, and an opening / closing valve. The switching valves 39a and 39b are opened and closed, the suction pump 34 is started and stopped, and the automatic valve 28 is opened and closed.

  The automatic valve 28 is configured to be closed by power supply from the control unit 13, opened when power supply from the control unit 13 is stopped during a power failure, and the gas-liquid separation tank 25 is opened to the atmosphere. Further, when the control unit 13 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become equal to or lower than the set value, the control unit 13 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to open to the atmosphere. Has been.

  Accordingly, even if the facility in which the membrane separation device 6 is installed is out of power and the diffuser 4a that performs filtration membrane cleaning stops, the automatic valve 28 opens and the gas-liquid separation tank 25 is opened to the atmosphere. The filtration can be stopped immediately, the membrane can be prevented from being blocked, and the overflow of the water tank 7 can be avoided.

  Further, when the control unit 13 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become equal to or lower than the set value, the control unit 13 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to open to the atmosphere. Therefore, for example, an abnormal negative pressure state in the gas-liquid separation tank 25 can be detected by operating the vacuum pump 27a in a closed state due to clogging of the filtration membrane 6a or failure of the switching valves 39a and 39b. In addition, it is possible to prevent accidents such as the pressure in the gas-liquid separation tank 25, the natural transfer pipe 31, and the forced discharge pipe 33 from being extremely lowered and collapsing.

  The controller 13 may monitor the current and voltage of the vacuum pump 27a and detect an abnormal negative pressure state in the gas-liquid separation tank 25.

  When drainage by the natural discharge pipe 31 is started in a state where the liquid level in the gas-liquid separation tank 25 is below the lowest water level LWL that can be transferred by the natural discharge pipe 31, the switching valves 39a and 39b are closed. The automatic valve 27b is opened, the vacuum pump 27a is started, and the air in the gas-liquid separation tank 25 is discharged to the outside, whereby the pressure in the gas-liquid separation tank 25 is made negative. Then, the treated water is stored in the gas-liquid separation tank 25 through the natural discharge pipe 31. Note that the switching valve 39a may be opened.

  When the liquid level meter 26 detects the high water level HWL of the liquid level in the gas-liquid separation tank 25, the automatic valve 27b is closed, the vacuum pump 27a is stopped, and the switching valve 39a is opened. At this time, the natural discharge pipe 31 upstream of the gas-liquid separation tank 25 is filled with treated water.

  Then, the treated water filtered by the filtration membrane 6a of the membrane separation device 6 by the siphon principle by the head pressure difference corresponding to the head difference between the liquid level of the membrane separation tank 4 and the water level of the water storage tank 7 is a natural discharge pipe 31. It is naturally transferred to the water tank 7 through it.

  The switching valve 39a is turned on when the liquid level in the gas-liquid separation tank 25 reaches the lowest water level LWL that can be transferred by the natural discharge pipe 31 from the start of the discharge of air in the gas-liquid separation tank 25 by the vacuum pump 27a. An operation method is also possible in which the vacuum pump 27a is stopped when the liquid level in the gas-liquid separation tank 25 reaches the high water level HWL by opening and starting filtration.

  As described above, when the treated water flows into the natural discharge pipe 31, no power is required for transferring the treated water, which is economical. The treated water stored in the water tank 7 is appropriately drained through the drain pipe 11.

  When the liquid level in the gas-liquid separation tank 25 detected by the liquid level meter 26 detects the lowest water level LWL that can be transferred by the natural discharge pipe 31, the control unit 13 opens the automatic valve 27b and operates the vacuum pump 27a to The air in the liquid separation tank 25 is discharged to recover the liquid level. At this time, the switching valve 39a as an opening / closing mechanism that opens and closes the filtrate outlet of the gas-liquid separation tank 25 may be closed to stop the filtration, or the filtration may be continued while being opened.

  When the liquid level meter 4 b detects the low water level LWL of the liquid level in the membrane separation tank 4, the control unit 13 closes the switching valve 39 a and stops the discharge of the filtrate through the natural transfer pipe 31. It is also possible to open the automatic valve 28, open the gas-liquid separation tank 25 to the atmosphere, and stop the discharge of the filtrate through the natural transfer pipe 31.

  When forcibly discharging the treated water through the forced discharge pipe 33, the control unit 13 closes the switching valve 39a, opens the switching valve 39b, and activates the suction pump 34.

  The natural discharge pipe 31 and the forced discharge pipe 33 may be switched to the forced discharge pipe 33 when the liquid level meter 4b detects an abnormally high water level HHWL.

  Note that the vacuum pump 27a and the automatic valve 27b for discharging the air in the gas-liquid separation tank 25 are not necessarily provided, and an operator pours treated water into the gas-liquid separation tank 25, for example. You may fill treated water.

  Next, a third embodiment will be described. The same reference numerals are given to the same or corresponding parts as in any of the above-described embodiments, and the description will be omitted.

  As shown in FIG. 5, the discharge mechanism 40 includes a natural discharge pipe 41 as a natural discharge path for discharging the filtrate due to a head difference between the inside and outside of the membrane separation tank 4, and a membrane separation in the path of the natural discharge pipe 41. A gas-liquid separation tank 25 as a gas-liquid separation unit that separates air mixed in the filtrate is provided at a position higher than the tank 4, and a suction pump 44 is provided in the natural discharge pipe 41 on the downstream side of the gas-liquid separation tank 25. Is provided.

  That is, in the present embodiment, the natural discharge pipe 41 becomes a natural discharge path when the suction pump 44 is stopped, and becomes a forced discharge path while the suction pump 44 is activated, and the suction pump 44 has a natural discharge path and a forced discharge path. It becomes a path switching mechanism for switching.

  An open / close valve 42 as an open / close mechanism for opening and closing the filtrate outlet of the gas / liquid separation tank 25 is provided downstream of the gas / liquid separation tank 25 and upstream of the suction side of the suction pump 44.

  Based on the signals from the liquid level gauge 4b, the liquid level gauge 26, and the pressure gauge 70, the control unit 14 (not shown) starts and stops the vacuum pump 27a, opens and closes the automatic valve 27b, and opens and closes the open / close valve 42. The start / stop of the pump 44 and the opening / closing control of the automatic valve 28 are controlled.

  The automatic valve 28 is configured to be closed by power supply from the control unit 14, opened when power supply from the control unit 14 is stopped during a power failure, and the gas-liquid separation tank 25 is opened to the atmosphere. Further, when the control unit 14 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become a set value or less, the control unit 14 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to be opened to the atmosphere. Has been.

  Accordingly, even if the facility in which the membrane separation device 6 is installed is out of power and the diffuser 4a that performs filtration membrane cleaning stops, the automatic valve 28 opens and the gas-liquid separation tank 25 is opened to the atmosphere. The filtration can be stopped immediately, the membrane can be prevented from being blocked, and the overflow of the water tank 7 can be avoided.

  Further, when the control unit 14 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become equal to or lower than the set value, the control unit 14 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to open to the atmosphere. Therefore, for example, an abnormal negative pressure state in the gas-liquid separation tank 25 due to the operation of the vacuum pump 27a in a closed state due to clogging of the filtration membrane 6a or failure of the opening / closing valve 42 can be detected. It is possible to prevent accidents such as the pressure in the liquid separation tank 25 and the natural transfer pipe 41 from being extremely lowered and collapsing.

  The control unit 14 may monitor the current and voltage of the vacuum pump 27a and detect an abnormal negative pressure state in the gas-liquid separation tank 25.

  When drainage by the natural discharge pipe 41 is started in a state where the liquid level in the gas-liquid separation tank 25 is below the lowest water level LWL that can be transferred by the natural discharge pipe 41, the open / close valve 42 is closed. The automatic valve 27b is opened, the vacuum pump 27a is started, and the air in the gas-liquid separation tank 25 is discharged to the outside, whereby the pressure in the gas-liquid separation tank 25 is made negative. Then, the treated water is stored in the gas-liquid separation tank 25 through the natural discharge pipe 41. The on-off valve 42 may be left open.

  When the liquid level meter 26 detects the high water level HWL of the liquid level in the gas-liquid separation tank 25, the automatic valve 27b is closed, the vacuum pump 27a is stopped, and the open / close valve 42 is opened. At this time, the natural discharge pipe 41 on the upstream side of the gas-liquid separation tank 25 is filled with treated water.

  Then, the treated water filtered by the filtration membrane 6a of the membrane separation device 6 by the principle of siphon due to the water head pressure difference according to the water head difference between the liquid surface of the membrane separation tank 4 and the liquid tank 7 is a natural discharge pipe 41. It is naturally transferred to the water tank 7 through it.

  When the liquid level in the gas-liquid separation tank 25 reaches the lowest water level LWL that can be transferred by the natural discharge pipe 41 from the start of the discharge of air in the gas-liquid separation tank 25 by the vacuum pump 27a, the open / close valve 42 is opened. An operation method is also possible in which the vacuum pump 27a is stopped when the liquid level in the gas-liquid separation tank 25 reaches the high water level HWL by opening and starting filtration.

  As described above, when the treated water flows into the natural discharge pipe 41, the power for transferring the treated water is not required, which is economical. The treated water stored in the water tank 7 is appropriately drained through the drain pipe 11.

  When the liquid level in the gas-liquid separation tank 25 detected by the liquid level meter 26 detects the lowest water level LWL that can be transferred by the natural discharge pipe 41, the control unit 14 opens the automatic valve 27b and operates the vacuum pump 27a to The air in the liquid separation tank 25 is discharged to recover the liquid level. At this time, the opening / closing valve 42 as an opening / closing mechanism for opening / closing the filtrate outlet of the gas-liquid separation tank 25 may be closed to stop the filtration, or the filtration may be continued while being opened.

  When the liquid level meter 4 b detects the low water level LWL of the membrane separation tank 4, the control unit 14 closes the open / close valve 42 and stops the discharge of the filtrate through the natural transfer pipe 41. It is also possible to open the automatic valve 28, open the gas-liquid separation tank 25 to the atmosphere, and stop the discharge of the filtrate through the natural transfer pipe 41.

  In the case of this embodiment, the forced discharge of the treated water is performed by starting the suction pump 44.

  The natural discharge pipe 41 and the forced discharge pipe may be switched so as to switch to the forced discharge pipe when the liquid level gauge 4b detects an abnormally high water level HHWL.

  Note that the vacuum pump 27a and the automatic valve 27b for discharging the air in the gas-liquid separation tank 25 are not necessarily provided, and an operator pours treated water into the gas-liquid separation tank 25, for example. You may fill treated water.

  Next, a fourth embodiment of the present invention will be described. The same reference numerals are given to the same or corresponding parts as in any of the above-described embodiments, and the description will be omitted.

  As shown in FIG. 6, the discharge mechanism 50 includes a natural discharge pipe 51 serving as a natural discharge path for discharging the filtrate due to a water head difference between the inside and outside of the membrane separation tank 4, and a suction pump 54 for sucking the filtrate. A forced discharge pipe 53 as a discharge path, and switching valves 59a and 59b as a path switching mechanism for discharging filtrate from either the natural discharge pipe 51 or the forced discharge pipe 53 are provided.

  One end of the natural discharge pipe 51 is disposed on the filtrate side of the filtration membrane 6 a, and the other end is opened to the water storage tank 7.

  The natural discharge pipe 51 is provided with a gas-liquid separation tank 25 as a gas-liquid separation unit that separates air mixed in the filtrate at a position higher than the membrane separation tank 4. A forced discharge pipe 53 is connected to the discharge pipe 51.

  Based on signals from the liquid level gauge 4b, the liquid level gauge 26, and the pressure gauge 70, the control unit 15 (not shown) starts and stops the vacuum pump 27a, opens and closes the automatic valve 27b, and opens and closes the switching valves 59a and 59b. Then, the start and stop of the suction pump 54, the opening and closing of the opening and closing valve 52, and the opening and closing control of the automatic valve 28 are controlled.

  The automatic valve 28 is configured to be closed by power supply from the control unit 15, opened when power supply from the control unit 15 is stopped during a power failure, and the gas-liquid separation tank 25 is opened to the atmosphere. Further, when the control unit 15 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become the set value or less, the control unit 15 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to be opened to the atmosphere. Has been.

  Accordingly, even if the facility in which the membrane separation device 6 is installed is out of power and the diffuser 4a that performs filtration membrane cleaning stops, the automatic valve 28 opens and the gas-liquid separation tank 25 is opened to the atmosphere. The filtration can be stopped immediately, the membrane can be prevented from being blocked, and the overflow of the water tank 7 can be avoided.

  In addition, when the control unit 15 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become equal to or lower than the set value, the control unit 15 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to open to the atmosphere. Therefore, for example, an abnormal negative pressure state in the gas-liquid separation tank 25 due to the operation of the vacuum pump 27a in the closed state due to the clogging of the filtration membrane 6a, the failure of the switching valves 59a, 59b, the opening / closing valve 52 or the like. Since the pressure in the gas-liquid separation tank 25, the natural transfer pipe 51, and the forced discharge pipe 53 is extremely reduced, an accident such as crushing can be prevented in advance.

  The control unit 15 may monitor the current and voltage of the vacuum pump 27a and detect an abnormal negative pressure state in the gas-liquid separation tank 25.

  When drainage by the natural discharge pipe 51 is started in a state where the liquid level in the gas-liquid separation tank 25 is below the lowest water level LWL that can be transferred by the natural discharge pipe 51, the switching valve 59a is opened, the switching valve 59b, and the open / close valve 52 are opened. Close. The automatic valve 27b is opened, the vacuum pump 27a is started, and the air in the gas-liquid separation tank 25 is discharged to the outside, whereby the pressure in the gas-liquid separation tank 25 is made negative. Then, the treated water is stored in the gas-liquid separation tank 25 through the natural discharge pipe 51. The open / close valve 52 may be opened.

  When the liquid level gauge 26 detects the high water level HWL of the liquid level in the gas-liquid separation tank 25, the automatic valve 27b is closed, the vacuum pump 27a is stopped, and the open / close valve 52 is opened. At this time, the natural discharge pipe 51 on the upstream side of the gas-liquid separation tank 25 is filled with treated water.

  Then, the treated water filtered by the filtration membrane 6a of the membrane separation device 6 by the principle of siphon due to the water head pressure difference according to the water head difference between the liquid level of the membrane separation tank 4 and the liquid level of the water storage tank 7 is a natural discharge pipe 51. It is naturally transferred to the water tank 7 through it.

  When the liquid level in the gas-liquid separation tank 25 reaches the lowest water level LWL that can be transferred by the natural discharge pipe 51 from the start of the discharge of air in the gas-liquid separation tank 25 by the vacuum pump 27a, the open / close valve 52 is opened. An operation method is also possible in which the vacuum pump 27a is stopped when the liquid level in the gas-liquid separation tank 25 reaches the high water level HWL by opening and starting filtration.

  In this way, when the treated water flows into the natural discharge pipe 51, the power for transferring the treated water is not required and it is economical. The treated water stored in the water tank 7 is appropriately drained through the drain pipe 11.

  When the liquid level in the gas-liquid separation tank 25 detected by the liquid level gauge 26 detects the lowest water level LWL that can be transferred by the natural discharge pipe 51, the control unit 15 opens the automatic valve 27b and operates the vacuum pump 27a. The air in the liquid separation tank 25 is discharged to recover the liquid level. At this time, the on / off valve 52 or the switching valve 59a as an opening / closing mechanism for opening / closing the filtrate outlet of the gas-liquid separation tank 25 may be closed to stop the filtration, or the filtration may be continued while being opened. .

  When the liquid level meter 4b detects the low water level LWL of the membrane separation tank 4, the control unit 12 closes the switching valve 59a and stops discharging the filtrate through the natural transfer pipe 51. It is also possible to open the automatic valve 28, open the gas-liquid separation tank 25 to the atmosphere, and stop the discharge of the filtrate through the natural transfer pipe 51.

  When forcibly discharging the treated water through the forced discharge pipe 53, the control unit 15 closes the switching valve 59a, opens the switching valve 59b, and activates the suction pump 54.

  The natural discharge pipe 51 and the forced discharge pipe 53 may be switched to the forced discharge pipe 53 when the liquid level meter 4b detects an abnormally high water level HHWL. Switching to drainage by the forced discharge path 53 is possible when the liquid level PL of the gas-liquid separation tank 25 is above the discharge part of the suction pump 24.

  In the present embodiment, the opening / closing valve 52 is provided in the lower part of the gas-liquid separation tank 25. However, since the opening / closing valve 52 can be operated in an open state as described above, the opening / closing valve 52 is not necessarily provided.

  Note that the vacuum pump 27a and the automatic valve 27b for discharging the air in the gas-liquid separation tank 25 are not necessarily provided, and an operator pours treated water into the gas-liquid separation tank 25, for example. You may fill treated water.

  When the vacuum pump 27a and the automatic valve 27b are not provided, the control unit 15 operates the suction pump 54 when the liquid level meter 26 detects that the liquid level in the gas-liquid separation tank 25 has dropped to a predetermined liquid level. Then, the automatic valve 28 is opened to open the gas-liquid separation tank 25 to the atmosphere, and the open / close valve 52 is closed to restore the liquid level in the gas-liquid separation tank 25. Thus, the air in the gas-liquid separation tank 25 can be discharged while maintaining the siphon.

  Next, a fifth embodiment of the present invention will be described. The same reference numerals are given to the same or corresponding parts as in any of the above-described embodiments, and the description will be omitted.

  As shown in FIG. 7, the discharge mechanism 60 includes a natural discharge pipe 61 as a natural discharge path for discharging the filtrate due to a water head difference between the inside and outside of the membrane separation tank 4, and a membrane separation in the path of the natural discharge pipe 61. A gas-liquid separation tank 25 as a gas-liquid separation unit that separates air mixed in the filtrate is provided at a position higher than the tank 4, and a suction pump 64 is provided in the natural discharge pipe 61 on the upstream side of the gas-liquid separation tank 25. The natural discharge pipe 61 on the downstream side of the gas-liquid separation tank 25 is provided with an open / close valve 62.

  That is, in this embodiment, the natural discharge pipe 61 becomes a natural discharge path when the suction pump 64 is stopped, and becomes a forced discharge path while the suction pump 64 is activated, and the suction pump 64 switches between the natural discharge path and the forced discharge path. It becomes a route switching mechanism.

  Based on signals from the liquid level gauge 4b, the liquid level gauge 26, and the pressure gauge 70, the control unit 16 (not shown) starts / stops the vacuum pump 27a, opens / closes the automatic valve 27b, and opens / closes the valve 62/63. Open / close, start / stop of the suction pump 64, and open / close control of the automatic valve 28.

  The automatic valve 28 is configured to be closed by power supply from the control unit 16 and to be opened when power supply from the control unit 16 is stopped during a power failure, and the gas-liquid separation tank 25 is opened to the atmosphere. Further, when the control unit 16 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become a set value or less, the control unit 16 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to be opened to the atmosphere. Has been.

  Accordingly, even if the facility in which the membrane separation device 6 is installed is out of power and the diffuser 4a that performs filtration membrane cleaning stops, the automatic valve 28 opens and the gas-liquid separation tank 25 is opened to the atmosphere. The filtration can be stopped immediately, the membrane can be prevented from being blocked, and the overflow of the water tank 7 can be avoided.

  Further, when the control unit 16 detects that the pressure in the gas-liquid separation tank 25 detected by the pressure gauge 70 has become equal to or lower than the set value, the control unit 16 opens the automatic valve 28 and controls the gas-liquid separation tank 25 to open to the atmosphere. Therefore, for example, an abnormal negative pressure state in the gas-liquid separation tank 25 can be detected due to the operation of the vacuum pump 27a in the closed state due to clogging of the filtration membrane 6a or failure of the on-off valves 62 and 63. Moreover, the pressure in the gas-liquid separation tank 25 and the natural transfer pipe 61 is extremely reduced, and an accident such as crushing can be prevented in advance.

  The controller 16 may monitor the current and voltage of the vacuum pump 27a and detect an abnormal negative pressure state in the gas-liquid separation tank 25.

  When drainage by the natural discharge pipe 61 is started in a state where the liquid level in the gas-liquid separation tank 25 is below the lowest water level LWL that can be transferred by the natural discharge pipe 61, the open / close valve 62 is closed. The automatic valve 27b is opened, the vacuum pump 27a is started, and the air in the gas-liquid separation tank 25 is discharged to the outside, whereby the pressure in the gas-liquid separation tank 25 is made negative. Then, the treated water is stored in the gas-liquid separation tank 25 through the natural discharge pipe 61. The open / close valve 62 may be opened.

  When the liquid level gauge 26 detects the high water level HWL of the liquid level in the gas-liquid separation tank 25, the automatic valve 27b is closed, the vacuum pump 27a is stopped, and the open / close valve 62 is opened. At this time, the natural discharge pipe 61 on the upstream side of the gas-liquid separation tank 25 is filled with treated water.

  Then, the treated water filtered by the filtration membrane 6a of the membrane separation device 6 by the principle of siphon due to the water head pressure difference according to the water head difference between the liquid level of the membrane separation tank 4 and the water level of the water storage tank 7 is a natural discharge pipe 61. It is naturally transferred to the water tank 7 through it.

  When the liquid level in the gas-liquid separation tank 25 reaches the lowest water level LWL that can be transferred by the natural discharge pipe 61 from the start of the discharge of air in the gas-liquid separation tank 25 by the vacuum pump 27a, the open / close valve 62 is opened. An operation method is also possible in which the vacuum pump 27a is stopped when the liquid level in the gas-liquid separation tank 25 reaches the high water level HWL by opening and starting filtration.

  As described above, when the treated water flows into the natural discharge pipe 61, the power for transferring the treated water is not required and it is economical. The treated water stored in the water tank 7 is appropriately drained through the drain pipe 11.

  When the liquid level in the gas-liquid separation tank 25 detected by the liquid level meter 26 detects the lowest water level LWL that can be transferred by the natural discharge pipe 61, the control unit 16 opens the automatic valve 27b and operates the vacuum pump 27a. The air in the liquid separation tank 25 is discharged to recover the liquid level. At this time, at least one of the opening / closing valve 62 and the opening / closing valve 63 serving as an opening / closing mechanism for opening / closing the filtrate outlet of the gas-liquid separation tank 25 may be closed to stop the filtration, or the filtration may be continued while being opened. Good.

  When the liquid level gauge 4b detects the low water level LWL of the membrane separation tank 4, the control unit 16 closes at least one of the open / close valve 62 and the open / close valve 63 and stops the discharge of the filtrate through the natural transfer pipe 61. To do. It is also possible to open the automatic valve 28, open the gas-liquid separation tank 25 to the atmosphere, and stop the discharge of the filtrate through the natural transfer pipe 61.

  In the case of this embodiment, the forced discharge of the treated water is performed by starting the suction pump 64.

  The natural discharge pipe 61 and the forced discharge pipe may be switched so as to switch to the forced discharge pipe when the liquid level meter 4b detects an abnormally high water level HHWL. Note that the forced discharge of the treated water by the suction pump 64 is possible when the liquid level PL of the gas-liquid separation tank 25 is above the discharge part of the suction pump 64.

  In the present embodiment, the opening / closing valve 62 is provided in the lower part of the gas-liquid separation tank 25. However, since the opening / closing valve 62 can be operated in an always open state as described above, the opening / closing valve 62 is not necessarily provided.

  Note that the vacuum pump 27a and the automatic valve 27b for discharging the air in the gas-liquid separation tank 25 are not necessarily provided, and an operator pours treated water into the gas-liquid separation tank 25, for example. You may fill treated water.

  When the vacuum pump 27a and the automatic valve 27b are not provided, the control unit 16 operates the suction pump 64 when the liquid level meter 26 detects that the liquid level in the gas-liquid separation tank 22 has dropped to a predetermined liquid level. Then, the automatic valve 28 is opened to open the gas-liquid separation tank 25 to the atmosphere, and the open / close valve 62 is closed to restore the liquid level in the gas-liquid separation tank 25. Thus, the air in the gas-liquid separation tank 25 can be discharged while maintaining the siphon.

  In any of the above-described embodiments, what is siphon filtered by a water head difference has been described. However, the present invention is not limited to siphon filtration, and gravity filtration that filters by a water head difference between the outlet of a membrane separation tank and a natural discharge pipe. Also applies.

  In any of the above-described embodiments, the flow rate adjustment of the filtrate of the natural discharge pipe or the forced discharge pipe was not specified, but the natural discharge pipe or the forced discharge pipe is appropriately provided with a flow meter, a flow control valve, or the like. Needless to say, the flow rate can be adjusted with technology. In addition, although other instrumentation devices and valves were not clearly shown, it goes without saying that a pressure gauge, a check valve, a gate valve and the like are appropriately provided in the natural discharge pipe or the forced discharge pipe.

  In any of the above-described embodiments, the operation method is described in which the treated water is naturally discharged through the natural discharge path during the steady operation and is switched to the forced discharge path when the membrane separation device 4 is at the abnormally high water level HHWL. The method of switching between the route and the forced discharge route is not limited to this description.

  For example, it is possible to use a control that switches to the forced discharge path when the process liquid discharge flow rate cannot be adjusted properly due to a failure of the flow rate adjustment valve, etc. is there.

  In addition, a control method is also possible in which the operation using the natural discharge route is performed when the inflow amount of the raw water is equal to or less than the set value, and the operation is switched to the operation using the forced discharge route when the set value is exceeded.

  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.

1: Anaerobic tank 2: Anoxic tank 3: Aerobic tank 3a: Air diffuser 4: Treatment tank (membrane separation tank)
4a: Air diffuser 4b: Liquid level meter 5: Excess sludge discharge line 6: Membrane separator 6a: Filtration membrane 7: Water tank 8: First circulation path 9: Second circulation path 10: Third circulation Road 11: Drain pipes 12, 13, 14, 15, 16: Control unit 20: Discharge mechanism 21: Natural discharge path (natural discharge pipe)
22: Open / close mechanism (open / close valve)
23: Forced discharge route (forced discharge pipe)
24: Suction pump 25: Gas-liquid separation part (gas-liquid separation tank)
26: Level gauge 27a: Exhaust mechanism (vacuum pump)
27b: Exhaust mechanism (automatic valve)
28: Opening mechanism (automatic valve)
29a, 29b: path switching mechanism (switching valve)
30: Discharge mechanism 31: Natural discharge route (natural discharge pipe)
33: Forced discharge route (forced discharge pipe)
34: Suction pumps 39a, 39b: path switching mechanism (switching valve)
40: Discharge mechanism 41: Natural discharge route (natural discharge pipe)
42: Opening / closing valve 44: Suction pump 50: Discharge mechanism 51: Natural discharge path (natural discharge pipe)
52: Opening / closing mechanism (opening / closing valve)
53: Forced discharge route (forced discharge pipe)
54: Suction pumps 59a, 59b: Path switching mechanism (switching valve)
60: Discharge mechanism 61: Natural discharge route (natural discharge pipe)
62: Opening / closing mechanism (opening / closing valve)
63: Open / close mechanism (open / close valve)
64: Suction pump 70: Pressure gauge 100: Sewage treatment device LWL: Minimum water level

Claims (8)

A membrane separation apparatus comprising a treatment tank to which a liquid to be treated is supplied, a filtration membrane immersed in the treatment tank, and a discharge mechanism for discharging the filtrate separated by solid-liquid separation with the filtration membrane to the outside of the tank. There,
The discharge mechanism is one of a natural discharge path for discharging the filtrate due to a water head difference between the inside and outside of the treatment tank, a forced discharge path having a pump for sucking the filtrate, the natural discharge path, and the forced discharge path. A path switching mechanism for discharging the filtrate from
A membrane separation apparatus, wherein a gas-liquid separation unit for separating air mixed in the filtrate is provided in the natural discharge path.   The membrane separation apparatus according to claim 1, wherein the forced discharge path is connected to the gas-liquid separation unit.   The membrane separation apparatus according to claim 2, wherein a discharge side path of the pump is connected to the gas-liquid separation unit.   4. The membrane separation apparatus according to claim 2, wherein when switching to the forced discharge path, the liquid level of the gas-liquid separation unit is above the discharge unit of the pump. 5.   The membrane separation apparatus according to claim 2 or 3, wherein the forced discharge path is configured by including a pump for sucking the filtrate in the natural discharge path.   A liquid level meter that measures a liquid level of the gas-liquid separation unit, and an exhaust mechanism that sucks and exhausts air of the gas-liquid separation unit based on a liquid level measured by the liquid level meter is provided. Item 6. The membrane separator according to any one of Items 1 to 5.   The membrane separation apparatus according to any one of claims 1 to 6, wherein the gas-liquid separation unit is provided with an opening mechanism including an automatic valve that is opened to the atmosphere during a power failure.   An open mechanism that opens the gas-liquid separator to the atmosphere, a liquid level meter that measures the liquid level of the gas-liquid separator, an open / close mechanism that opens and closes the filtrate outlet of the gas-liquid separator, and the liquid level meter When the measured liquid level becomes a predetermined value or less, the pump is operated, the gas-liquid separation unit is opened to the atmosphere by the opening mechanism, and the opening / closing mechanism is closed to restore the liquid level of the gas-liquid separation unit The membrane separation apparatus according to claim 3, further comprising a section.

Images