Liquid treatment facility and liquid treatment method therefor

Abstract

To provide a liquid treatment facility and a liquid treatment method in a liquid treatment facility capable of suppressing a decline in quality of treated water and a decline in treatment efficiency of liquid treatment equipment caused by the implementation of scouring.SOLUTION: A liquid treatment facility 10 includes a treatment tank 11, a membrane unit 20, a treatment channel 13, a diffusion pipe 22, and biological membrane outflow prevention devices 30A and 30B. The membrane unit 20 has a hollow fiber membrane 23 and a biological membrane 24, and the biological membrane 24 treats treated liquid S. The treatment channel 13 allows the treated liquid S treated by the membrane unit 20 to be discharged outside the treatment tank 11. The diffusion pipe 22 supplies air to the outside of the hollow fiber membrane 23. The biological membrane outflow prevention devices 30A and 30B prevent the biological membrane 24 detached from the hollow fiber membrane 23 from flowing out of the treatment channel 13 to the outside of the treatment tank 11. The biological membrane outflow prevention devices 30A and 30B prevent inflow of the biological membrane 24 from the treatment tank 11 into the treatment channel 13 by regulating a flow F of the treated liquid S in the treatment tank 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid treatment facility that treats a liquid to be treated using a biofilm, and a liquid treatment method in the liquid treatment facility. [Background technology]

[0002] Conventionally, this type of liquid treatment facility is equipped with a liquid treatment device as shown in Patent Document 1. The liquid treatment device in Patent Document 1 includes a casing that is immersed in the liquid to be treated in a treatment tank and is open at the top and bottom, a plurality of gas-permeable hollow fiber membranes arranged inside the casing, a gas supply means that supplies gas to the inside of the hollow fiber membranes, and an aeration means that is installed below the casing and supplies a gas such as air to the outside of the hollow fiber membranes. In the liquid treatment device in Patent Document 1, a biofilm is formed on the outer surface of the hollow fiber membranes, which utilizes the gas supplied to the inside of the hollow fiber membranes.

[0003] In the liquid treatment device of Patent Document 1, in order to maintain an appropriate thickness of the biofilm growing on the surface of the hollow fiber membrane, the hollow fiber membrane is periodically rocked to promote the detachment of the biofilm (scouring). Here, the hollow fiber membrane is rocked by a relatively fast upward flow of gas generated inside the casing by aeration from the bottom of the casing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2006-101805 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the liquid treatment equipment of Patent Document 1, when the scouring is performed in the liquid treatment device, the detached biofilm is carried by the upward flow of gas and flows out from the top of the casing. Therefore, a large amount of biofilm is contained in the treated liquid that flows out from the vicinity of the casing during or immediately after scouring. Therefore, there is a problem that the water quality of the treated liquid deteriorates due to scouring.

[0006] For this reason, in conventional liquid treatment equipment, the supply of the liquid to be treated to the treatment tank is temporarily stopped during the scouring process to prevent deterioration of the water quality of the treated liquid. However, in large-scale liquid treatment equipment, it is often difficult to temporarily stop the supply of the liquid to be treated to the treatment tank. Therefore, there is a problem that temporarily stopping the supply of the liquid to be treated actually reduces the treatment efficiency of the liquid treatment equipment.

[0007] An object of the present invention is to provide a liquid treatment facility and a liquid treatment method therefor that can suppress the deterioration of the water quality of the treated water and the deterioration of the treatment efficiency of the liquid treatment facility that are caused by the implementation of scouring. [Means for solving the problem]

[0008] In order to achieve the above object, the liquid treatment facility of the present invention comprises: a treatment tank to which a liquid to be treated is supplied; a gas-permeable membrane immersed in the liquid to be treated in the treatment tank; and a biofilm formed on the outer surface of the gas-permeable membrane and utilizing an oxygen-containing gas supplied into the gas-permeable membrane, the liquid treatment facility comprising: a liquid treatment device that treats the liquid to be treated with the biofilm; a discharge section that discharges the liquid to be treated treated by the liquid treatment device to the outside of the treatment tank; an air diffuser that is located below the gas-permeable membrane and supplies gas to the outside of the gas-permeable membrane; and a biofilm outflow prevention device that prevents the biofilm that has been detached from the gas-permeable membrane by the gas supplied from the air diffuser from outflowing to the outside of the treatment tank through the discharge section, a movable weir capable of regulating the flow of the liquid to be treated flowing from the treatment tank to the discharge section, wherein the movable weir regulates the flow of the liquid to be treated, thereby blocking the biofilm flowing from the treatment tank to the discharge section; This prevents the biofilm from flowing from the treatment tank into the discharge section.

[0009] Here, the biofilm outflow prevention device that prevents the biofilm from outflowing from the discharge part to the outside of the treatment tank includes not only a device that completely prevents the biofilm from outflowing to the outside of the treatment tank, but also a device that significantly reduces the amount of the biofilm that outflows to the outside of the treatment tank. Furthermore, preventing the biofilm from flowing into the discharge part from the treatment tank includes not only completely preventing the biofilm from flowing in, but also significantly reducing the amount of the biofilm that inflows.

[0010] According to this, By scouring, the biofilm that has been detached from the gas-permeable membrane is blocked before it flows from the treatment tank to the discharge section. This can prevent biofilms from flowing from the treatment tank to the discharge section.

[0013] In the liquid treatment equipment of the present invention, the membrane outflow prevention device is provided with a partition that regulates the flow of the treated liquid at the top of the liquid treatment device, and the partition is formed so as to be able to rise and fall relative to the liquid treatment device so as to surround the liquid treatment device, and rises so as to protrude upward from the liquid surface in the treatment tank to regulate the flow of the treated liquid, thereby blocking the biofilm flowing out from the liquid treatment device.

[0014] This allows the biofilm that has been detached from the gas-permeable membrane by scouring to be blocked before it flows out of the liquid treatment device.

[0015] In the liquid treatment equipment of the present invention, the partition section is a part that regulates the flow of the liquid to be treated, and is formed so that the diameter of the part that is formed to surround the liquid treatment device gradually increases.

[0016] This increases the volume of the liquid to be treated that can be regulated, making it less likely for the liquid to overflow the partition, and therefore effectively blocks the biofilm that flows out with the liquid to be treated before it leaves the liquid treatment device.

[0017] In the liquid treatment equipment of the present invention, the partition section is a part that regulates the flow of the liquid to be treated, and is formed so that the diameter of the part that is formed to surround the liquid treatment device gradually decreases.

[0018] In this way, the partition is formed at an angle opposite to the flow of the liquid to be treated, so that the return of the partition makes it easier to retain the biofilm that flows out with the liquid to be treated below, thereby efficiently blocking the biofilm before it flows out of the liquid treatment device.

[0019] In the liquid treatment facility of the present invention, the biofilm outflow prevention device is driven by the gas supplied to the outside of the gas-permeable membrane by the air diffuser.

[0020] This allows the gas supplied by the air diffuser to be used both to clean the biofilm and to prevent the biofilm from flowing from the treatment tank to the discharge section.

[0021] The liquid treatment method in a liquid treatment facility of the present invention comprises a treatment tank to which a liquid to be treated is supplied, a gas-permeable membrane immersed in the liquid to be treated in the treatment tank, and a biofilm formed on the outer surface of the gas-permeable membrane and utilizing an oxygen-containing gas supplied into the gas-permeable membrane, the biofilm treating the liquid to be treated using the biofilm, a discharge section discharging the liquid to be treated treated by the liquid treatment device to the outside of the treatment tank, and an aeration device located below the gas-permeable membrane and supplying gas to the outside of the gas-permeable membrane, the method comprising: a biofilm peeling step in which the biofilm is peeled off from the gas-permeable membrane by the gas supplied by the aeration device; and a membrane outflow prevention step in which the biofilm peeled off from the gas-permeable membrane in the membrane peeling step is prevented from flowing out of the treatment tank through the discharge section, by regulating the flow of the liquid to be treated in the treatment tank.

[0022] This makes it possible to prevent biofilms that have been detached from the gas-permeable membrane by scouring from flowing from the treatment tank into the discharge section. [Effects of the Invention]

[0023] According to the liquid treatment equipment of the present invention, the biofilm detached from the gas-permeable membrane by scouring does not flow out of the treatment tank through the discharge port, thereby preventing deterioration of the water quality of the treated liquid due to scouring. Furthermore, since it is not necessary to temporarily stop the supply of the liquid to be treated to the treatment tank when scouring is performed, the treatment efficiency (treatment capacity, treatment time) of the liquid treatment device is not reduced. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic configuration diagram of a liquid treatment facility according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic plan view of the liquid processing equipment. [Figure 3] FIG. 2 is a partially enlarged cross-sectional view of a hollow fiber membrane and a biomembrane in a membrane module of the liquid treatment facility. [Figure 4] 10 is a diagram showing the case where the movable weir in the biofilm outflow prevention device of the liquid treatment facility falls downward. FIG. [Figure 5] FIG. 10 is a schematic configuration diagram of a liquid treatment facility according to another embodiment of the present invention. [Figure 6] FIG. 2 is a plan view of the biofilm outflow prevention device of the liquid treatment facility. [Figure 7] 7 is a cross-sectional view taken along the line AA in FIG. 6. [Figure 8] 7 is a cross-sectional view of FIG. 6 taken along line B-B. [Figure 9] 10 is a diagram showing the case where the upper part of the baffle in the biofilm outflow prevention device of the liquid treatment facility protrudes above the liquid surface in the treatment tank. FIG. [Figure 10] FIG. 10 is a schematic configuration diagram of a liquid treatment facility according to another embodiment of the present invention. [Figure 11] FIG. 10 is a schematic configuration diagram of a liquid treatment facility according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The liquid treatment facility of the present invention will be described below.

[0026] 1, a liquid treatment facility 10 according to one embodiment of the present invention is a facility for aerobic biological treatment of a liquid S to be treated (e.g., organic wastewater, sludge, etc.) in a treatment tank 11 at a sewage treatment plant, an industrial wastewater treatment plant, etc. The liquid treatment facility 10 mainly comprises the treatment tank 11, a membrane unit 20 (an example of a "liquid treatment device"), and a first biofilm outflow prevention device 30A.

[0027] The treatment tank 11 is a tank to which the liquid to be treated S is supplied. The treatment tank 11 is connected to an inflow water channel 12 and a treatment water channel 13 (an example of a "discharge section").

[0028] The inflow water channel 12 is a water channel for supplying the liquid to be treated S into the tank. As shown in Fig. 2, the inflow water channel 12 is formed along one end (upstream side) of the treatment tank 11. The inflow water channel 12 supplies the liquid to be treated S into the tank from one end side of the treatment tank 11.

[0029] The treatment water channel 13 is a water channel for discharging the liquid to be treated S to the outside of the treatment tank 11. As shown in Fig. 2, the treatment water channel 13 is formed along the other end (downstream side) of the treatment tank 11. The treatment water channel 13 discharges the liquid to be treated S in the tank from the other end side of the treatment tank 11 to the outside of the treatment tank 11.

[0030] As shown in Figures 1 and 2, in a liquid treatment facility 10, a liquid to be treated S (raw water) is supplied from an inflow channel 12 to a treatment tank 11. Furthermore, the liquid to be treated S (treated water) treated by a membrane unit 20 is discharged from the treatment tank 11 to a treatment channel 13. The liquid to be treated S (raw water) is supplied to the treatment tank 11 via a first settling outflow channel (not shown) through a raw water tank (not shown) and the inflow channel 12. The liquid to be treated S supplied to the treatment tank 11 is circulated within the tank by a circulation pump (not shown). The liquid to be treated S (treated water) treated by the membrane unit 20 is discharged to the outside of the treatment tank 11 via the treatment channel 13.

[0031] As shown in Fig. 2, a plurality of membrane units 20 are arranged in parallel at predetermined intervals in the treatment tank 11. Although Fig. 2 shows three membrane units 20 arranged as an example, the number of membrane units 20 is not limited to this, and four or more or two or less membrane units 20 may be arranged.

[0032] The membrane unit 20 is a device that treats the liquid to be treated S in the treatment tank 11. As shown in FIG. 1, the membrane unit 20 is mainly composed of a membrane module 21 and an air diffuser 22 (an example of an "air diffuser").

[0033] In the membrane unit 20, a plurality of membrane modules 21 are arranged in parallel at predetermined intervals. Note that, although six membrane modules 21 are arranged in Fig. 1 as an example, the number is not limited to six, and in practice, a large number (for example, several tens to several hundreds) of membrane modules 21 are arranged.

[0034] As shown in FIG. 3, the membrane module 21 is mainly composed of a large number of bundled hollow fiber membranes 23 (an example of a “gas-permeable membrane”) and a biomembrane 24.

[0035] The hollow fiber membrane 23 is a membrane immersed in the liquid to be treated S in the treatment tank 11. The hollow fiber membrane 23 is arranged so as to extend in the vertical direction of the treatment tank 11. The hollow fiber membrane 23 is gas permeable and can selectively allow oxygen in the air to pass through. The hollow fiber membrane 23 is mainly composed of a non-porous membrane, but may also be a composite membrane of non-porous and porous membranes.

[0036] 1 and 3, air A (an example of an "oxygen-containing gas") is supplied to the inside of the hollow fiber membrane 23 from a first blower 14 provided outside the treatment tank 11 via an air supply pipe 15. The air A supplied by the first blower 14 passes through the membrane surface of the hollow fiber membrane 23 without forming bubbles and dissolves in the liquid S to be treated in the treatment tank 11.

[0037] As shown in Fig. 3, a biofilm 24 is formed on the outer surface of the hollow fiber membrane 23. In the biofilm 24, organisms utilize oxygen contained in the air A from the hollow fiber membrane 23 to biologically remove substances to be treated (e.g., organic matter, nitrogen compounds, etc.) in the liquid to be treated S. The biofilm 24 is formed to a predetermined thickness M from the outer surface of the hollow fiber membrane 23. The thickness M of the biofilm 24 is set in consideration of conditions such as the contact efficiency between the biofilm 24 (organisms in the biofilm 24) and oxygen, and the oxygen transfer efficiency in the biofilm 24.

[0038] In the membrane unit 20, in order to maintain the biofilm 24 formed on the hollow fiber membrane 23 at an appropriate film thickness M, the biofilm 24 is periodically (for example, once to several times a day) cleaned (scouring) with cleaning air (an example of a "gas") supplied from the air diffuser 22. Specifically, an upward flow is generated by discharging cleaning air from the air diffuser 22. The generated upward flow causes the hollow fiber membrane 23 to vibrate, thereby detaching the biofilm 24 from the hollow fiber membrane 23 and adjusting the film thickness M.

[0039] As shown in FIG. 1, the air diffuser 22 is located below the membrane module 21 (hollow fiber membranes 23) and supplies cleaning air to the outside of the hollow fiber membranes 23 (see FIG. 3). The air diffuser 22 intermittently discharges cleaning air from below the membrane module 21 toward the hollow fiber membranes 23 (see FIG. 3). The cleaning air discharged from the air diffuser 22 is supplied to the air diffuser 22 from a second blower 16 provided outside the treatment tank 11 via an air supply pipe 17. One end of the air supply pipe 17 is connected to the second blower 16, and the other end is connected to the air diffuser 22. Within the treatment tank 11, the air supply pipe 17 is arranged vertically from above the treatment tank 11 along the membrane units 20.

[0040] As shown in Fig. 1, the air diffuser 22 supplies cleaning air as bubbles into the liquid S to be treated. The bubbles discharged from the air diffuser 22 rise, generating an upward flow in the treatment tank 11. The air diffuser 22 creates turbulence or shear force on the surface of the biofilm 24 (see Fig. 3) with the generated upward flow, thereby cleaning the biofilm 24. Note that the gas discharged from the air diffuser 22 is not limited to cleaning air, and any gas capable of cleaning the biofilm 24, such as nitrogen gas or biogas, may be used.

[0041] In the liquid treatment equipment 10, cleaning (scouring) of the biofilm 24 causes the biofilm 24 detached from the hollow fiber membranes 23 to flow out from the upper part (vicinity) of the membrane unit 20, carried by the upward flow of the cleaning air. Therefore, a large amount of biofilm 24 is contained in the liquid to be treated S that flows out from the vicinity of the membrane unit 20 during or immediately after scouring. Therefore, scouring deteriorates the quality of the treated liquid discharged from the treatment water channel 13 to the outside of the treatment tank 11. Therefore, the liquid treatment equipment 10 is provided with a first biofilm outflow prevention device 30A, which prevents the biofilm 24 detached from the hollow fiber membranes 23 by the cleaning air supplied from the air diffuser 22 from flowing out from the treatment water channel 13 to the outside of the treatment tank 11. Here, preventing the biofilm 24 from flowing out of the treatment waterway 13 to the outside of the treatment tank 11 does not only mean that the liquid treatment equipment 10 (first biofilm outflow prevention device 30A) completely prevents the biofilm 24 from flowing out of the treatment tank 11, but also means that the amount of biofilm 24 flowing out of the treatment tank 11 is significantly reduced.

[0042] As shown in Figure 1, the first biofilm outflow prevention device 30A comprises a movable weir 31 capable of regulating the flow F (see Figure 2) of the treated liquid S flowing from the treatment tank 11 into the treatment water channel 13, and a drive unit 32 for operating the movable weir 31.

[0043] The movable weir 31 is provided on the upper part of the side wall of the treatment tank 11 on the side to which the treatment channel 13 is connected (at the boundary between the treatment tank 11 and the treatment channel 13). The movable weir 31 is a flat weir that can swing on the upper part of the side wall of the treatment tank 11. The movable weir 31 stands upward on the upper part of the side wall of the treatment tank 11, thereby restricting the flow F of the liquid to be treated S flowing from the treatment tank 11 into the treatment channel 13 and blocking the liquid to be treated S before it flows into the treatment channel 13. In other words, the movable weir 31 stands upward on the upper part of the side wall of the treatment tank 11, thereby increasing the weir level (overflow height). Furthermore, by restricting the flow F of the liquid to be treated S flowing into the treatment channel 13, the movable weir 31 blocks the biofilm 24 contained in the liquid to be treated S before it flows into the treatment channel 13.

[0044] 4, the movable weir 31 tilts downward at the upper part of the side wall of the treatment tank 11, thereby releasing the restriction on the flow F of the liquid to be treated S and allowing the liquid to be treated S to flow from the treatment tank 11 into the treatment waterway 13. In other words, the movable weir 31 tilts downward at the upper part of the side wall of the treatment tank 11, thereby lowering the weir level (overflow height).

[0045] 1 and 4, the movable weir 31 is actuated by driving a driving unit 32. The driving unit 32 mainly includes an air cylinder 33 and a switching valve .

[0046] The air cylinder 33 is connected to the air supply pipe 17 via a switching valve 34. The air cylinder 33 is driven by cleaning air supplied to the air diffuser pipe 22 of the membrane unit 20. That is, the air cylinder 33 is driven by using the cleaning air supplied by the air diffuser pipe 22 to the outside of the hollow fiber membranes 23. In other words, the movable weir 31 operates by using the cleaning air supplied by the air diffuser pipe 22 to the outside of the hollow fiber membranes 23.

[0047] When the movable dam 31 is raised upward, the air cylinder 33 retracts the piston rod 33a as shown in Fig. 1. On the other hand, when the movable dam 31 is lowered downward, the air cylinder 33 extends the piston rod 33a as shown in Fig. 4.

[0048] As shown in Figure 2, in the liquid treatment facility 10, a plurality of movable weirs 31 (three movable weirs 31 in Figure 2) are arranged in parallel along the treatment water channel 13. Each movable weir 31 is arranged so as to face one of the plurality of membrane units 20 (three membrane units 20 in Figure 2) arranged in the treatment tank 11. Note that, although three movable weirs 31 are arranged in Figure 2 as an example, this is not limiting, and four or more or two or less movable weirs 31 may be arranged as long as they are arranged in accordance with the number of membrane units 20.

[0049] Next, a liquid treatment method for scouring the biofilm 24 in the liquid treatment facility 10 equipped with the first biofilm outflow prevention device 30A will be described.

[0050] As described above, in the liquid treatment facility 10, scouring is periodically performed on the biofilm 24. The scouring is performed on any one of the membrane units 20. For example, the scouring is performed on the membrane unit 20 on the left side in FIG. 2 (first membrane unit 20A).

[0051] Scouring of the membrane unit 20 is performed using cleaning air supplied by the air diffuser 22. Specifically, cleaning air is intermittently discharged from the air diffuser 22 of the first membrane unit 20A, which is the target of scouring, to the outside of the hollow fiber membranes 23. When the air diffuser 22 discharges the cleaning air, an upward flow of bubbles in the cleaning air is generated. The generated upward flow of cleaning air detaches the biofilm 24 from the hollow fiber membranes 23 (biofilm detachment process).

[0052] Here, as shown in Fig. 2, when scouring is performed on the first membrane unit 20A, the movable weir 31 (first movable weir 31A and second movable weir 31B) adjacent to the first membrane unit 20A is raised upward to restrict the flow F of the liquid to be treated S flowing from the treatment tank 11 into the treatment channel 13. Specifically, as shown in Fig. 2, the air cylinder 33 that operates the first movable weir 31A and the second movable weir 31B is driven by cleaning air supplied from the air supply pipe 17, causing the first movable weir 31A and the second movable weir 31B to rise upward (see Fig. 1). As a result, the first movable weir 31A and the second movable weir 31B rise upward to restrict the flow F of the liquid to be treated S from the treatment tank 11 into the treatment channel 13. This prevents the biofilm 24 that has been peeled off from the hollow fiber membrane 23 in the biofilm peeling process from flowing from the treatment tank 11 into the treatment water channel 13. In other words, the biofilm 24 that has been peeled off from the hollow fiber membrane 23 in the biofilm peeling process is prevented from flowing out of the treatment tank 11 from the treatment water channel 13 (membrane outflow prevention process).

[0053] On the other hand, when scouring is performed on the first membrane unit 20A, as shown in Figure 2, the movable weir 31 (third movable weir 31C) located away from the first membrane unit 20A is tilted downward (see Figure 4) to allow the liquid to be treated S to flow from the treatment tank 11 into the treatment water channel 13. That is, by tilting the movable weir 31 (third movable weir 31C) located in a position where it is difficult for the biofilm 24 peeled off in the membrane peeling step to flow into the treatment water channel 13, the liquid to be treated S is allowed to flow into the treatment water channel 13 in a concentrated manner from a location away from the first membrane unit 20A where scouring is being performed. In this way, by tilting the movable weir 31 located away from the membrane unit 20 undergoing scouring and allowing a limited inflow of the treated liquid S from the treatment tank 11 into the treatment waterway 13, it is possible to simultaneously perform scouring of the membrane unit 20 and treatment of the treated liquid S by the biofilm 24 without temporarily stopping the supply of the treated liquid S to the treatment tank 11 during scouring. This reduces the amount of biofilm 24 that flows out of the treatment tank 11 from the treatment waterway 13 through the third movable weir 31C.

[0054] In addition, in the liquid treatment equipment 10, the biofilm outflow prevention device that prevents the biofilm 24 peeled off from the hollow fiber membrane 23 from flowing out of the treatment water channel 13 to the outside of the treatment tank 11 may be changed from the first biofilm outflow prevention device 30A shown in Figure 1 to the second biofilm outflow prevention device 30B shown in Figure 5.

[0055] As shown in Figure 5, the second biofilm outflow prevention device 30B includes a baffle 40 (an example of a "partition section") that regulates the flow F1 (see Figure 6) of the treated liquid S above the membrane unit 20, and a lifting section 50 for raising and lowering the baffle 40.

[0056] As shown in Figure 6, the baffle 40 is a cylindrical member formed by combining four partition plates 41 so as to surround the membrane unit 20. As shown in Figures 7 and 8, the partition plate 41 is a hollow member made of two parallel plates with a closed upper end and an open lower end, forming an internal space. The internal space of the partition plate 41 serves as an air reservoir 42 to which a gas such as air can be supplied. Therefore, when the baffle 40 is attached to the membrane unit 20 and submerged in the treatment tank 11, buoyancy is imparted to the baffle 40 by supplying a gas such as air to the air reservoir 42, causing the baffle 40 to rise so as to protrude above the liquid level E of the treatment tank 11.

[0057] 6 and 7, the baffle 40 has a pair of guide plates 43a, 43b that form guide grooves on the inner surfaces (the surfaces facing the membrane unit 20) of two opposing partition plates 41 out of the four partition plates 41. The guide plates 43a, 43b are portions that are guided by the air supply pipe 17, the air supply pipe 15, or the guide pipe 53 when the baffle 40 moves up and down. The guide plates 43a, 43b have groove-shaped portions formed in the vertical direction.

[0058] 7, the pair of first guide plates 43a have groove-shaped portions that fit into the air supply pipe 17 and slide along the air supply pipe 17. The pair of second guide plates 43b have groove-shaped portions that fit into the air supply pipe 15 or the guide pipe 53 and slide along the air supply pipe 15 and the guide pipe 53. In this way, the pair of first guide plates 43a slide along the air supply pipe 17 and the pair of second guide plates 43b slide along the air supply pipe 15 and the guide pipe 53, so that the baffle 40 is guided by the air supply pipe 17, the air supply pipe 15, and the guide pipe 53 and can move up and down in the vertical direction.

[0059] As shown in FIGS. 6 to 8, the lifting section 50 mainly includes an air supply pipe 51, an exhaust pipe 52, a guide pipe 53, and a stopper .

[0060] The air supply duct 51 is an air supply pipe branched from the air supply pipe 17. As shown in FIG. 7, the air supply duct 51 is inserted into the air reservoir 42 (the lower end of the partition plate 41) when the baffle 40 is attached to the membrane unit 20 and submerged in the treatment tank 11. The air supply duct 51 supplies a portion of the cleaning air supplied to the air diffuser pipe 22 to the air reservoir 42. When the cleaning air is supplied from the air supply duct 51 to the air reservoir 42, buoyancy is imparted to the baffle 40, causing the upper portion of the baffle 40 to rise and protrude above the liquid level E of the treatment tank 11. In addition, a portion of the cleaning air discharged from the air diffuser pipe 22 turns into bubbles and flows into the air reservoir 42 from below the baffle 40, causing buoyancy to be imparted to the baffle 40, causing the upper portion of the baffle 40 to rise and protrude above the liquid level E of the treatment tank 11. That is, the baffle 40 operates by utilizing the cleaning air supplied to the outside of the hollow fiber membrane 23 by the air diffuser 22 .

[0061] The exhaust pipe 52 is a pipe for exhausting the cleaning air stored in the air reservoir 42 to the outside. As shown in Figures 7 and 8, the exhaust pipe 52 is formed at the upper end of the partition plate 41. The exhaust pipe 52 is extended so that its upper end protrudes upward from the liquid level E of the treatment tank 11. The exhaust pipe 52 is formed so that its lower end can communicate with the air reservoir 42 of the partition plate 41. When the cleaning air stored in the air reservoir 42 is exhausted from the exhaust pipe 52, the buoyancy applied to the baffle 40 decreases, and the upper part of the baffle 40 descends (sinks) below the liquid level E of the treatment tank 11.

[0062] The guide pipe 53 is a guide for guiding the baffle 40 in the vertical direction. As shown in Figure 7, the guide pipe 53 is installed to extend in the vertical direction from below the air supply pipe 15. The guide pipe 53 is formed in the same straight line as the air supply pipe 15 which is installed to extend in the vertical direction. The guide pipe 53 is arranged in parallel with the air supply pipe 17 so as to sandwich the membrane unit 20 therebetween.

[0063] The stopper 54 is a member for stopping the baffle 40, which is descending within the treatment tank 11, at a predetermined lower limit position. As shown in Figures 7 and 8, the stopper 54 is fixed to the air supply pipe 17 and the guide pipe 53. The lower end of the baffle 40 (the lower end of the partition plate 41) comes into contact with the stopper 54, thereby preventing the baffle 40 from descending.

[0064] Next, a liquid treatment method for scouring the biofilm 24 in the liquid treatment facility 10 equipped with the second biofilm outflow prevention device 30B will be described.

[0065] As described above, cleaning air is supplied from the air supply pipe 17 to the air diffuser pipe 22, and the cleaning air is discharged. Subsequently, the biofilm 24 is peeled off from the hollow fiber membranes 23 by an upward flow generated by the air diffuser pipe 22 discharging the cleaning air (membrane peeling process). At the same time, cleaning air is supplied from the air supply pipe 17 to the air diffuser pipe 22, and the baffle 40 is raised relative to the membrane unit 20 so that the upper end of the baffle 40 protrudes above the liquid level E in the treatment tank 11, as shown in FIG. 9. As a result, the flow F1 (see FIG. 6) of the liquid S to be treated above the membrane unit 20 is regulated by the baffle 40.

[0066] Specifically, cleaning air is supplied from the air supply pipe 51 to the air reservoir 42 of the baffle 40, imparting buoyancy to the baffle 40. In addition to the cleaning air supplied from the air supply pipe 51, cleaning air discharged from the air diffuser 22 flows into the air reservoir 42. As a result, as shown in FIG. 9 , the baffle 40 rises (floats), and the top of the baffle 40 protrudes above the liquid level E in the treatment tank 11. As shown in FIG. 6 , the baffle 40 surrounds the membrane unit 20 from above. Therefore, the baffle 40 can prevent the biofilm 24 detached from the hollow fiber membranes 23 in the biofilm detachment step from flowing out from the top of the membrane unit 20 (biofilm outflow prevention step). That is, the biofilm 24 detached from the hollow fiber membranes 23 in the biofilm detachment step does not flow out of the treatment tank 11 from the treatment water channel 13.

[0067] On the other hand, by stopping the discharge of cleaning air from the air diffuser pipe 22 (stopping the supply of cleaning air from the air supply pipe 17 to the air diffuser pipe 22), the supply of cleaning air from the air supply duct 51 to the air reservoir 42 and the inflow of cleaning air from the air diffuser pipe 22 to the air reservoir 42 are stopped. As a result, the cleaning air stored in the air reservoir 42 is exhausted from the exhaust pipe 52, and the buoyancy applied to the baffle 40 is released. Therefore, the baffle 40 automatically descends (sinks) to a predetermined lower limit position by its own weight. When the baffle 40 descends to the predetermined lower limit position, the circulation of the liquid S to be treated in the treatment tank 11 by the circulation pump (not shown) is resumed. Furthermore, the biofilm 24 that is blocked above the membrane unit 20 by the baffle 40 sinks to the bottom of the treatment tank 11 by its own weight when the discharge of cleaning air from the aeration pipe 22 stops and the upward flow caused by the bubbles of the cleaning air disappears.

[0068] Furthermore, the second biofilm outflow prevention device 30B operates only for one target membrane unit 20. Therefore, as shown in FIG. 2, when there are multiple membrane units 20, the second biofilm outflow prevention device 30B provided in the membrane unit 20 that is not undergoing scouring is stopped, and only the second biofilm outflow prevention device 30B provided in the membrane unit 20 that is undergoing scouring (e.g., the first membrane unit 20A) is operated. In this way, by operating only the second biofilm outflow prevention device 30B provided in the membrane unit 20 that is undergoing scouring, it is possible to simultaneously perform scouring of the membrane unit 20 and treatment of the treated liquid S without temporarily stopping the supply of the treated liquid S to the treatment tank 11 during scouring.

[0069] As described above, according to this embodiment, the biofilm 24 detached from the hollow fiber membranes 23 due to scouring does not flow out of the treatment tank 11 from the treatment water channel 13, thereby suppressing deterioration of the water quality of the treatment liquid caused by scouring. Furthermore, since there is no need to temporarily stop the supply of the treatment liquid S to the treatment tank 11 when scouring is performed, the treatment efficiency (treatment capacity, treatment time) of the membrane unit 20 does not decrease.

[0070] In particular, the first biofilm outflow prevention device 30A can knock down a movable weir 31 located away from the membrane unit 20 performing scouring, thereby allowing the treated liquid S to flow into the treatment waterway 13 in a limited manner.Therefore, in a large-scale liquid treatment facility with a large number of membrane units 20 and where the distance between the membrane units 20 and the treatment waterway 13 can be sufficiently secured, scouring of the membrane units 20 and treatment of the treated liquid S can be performed simultaneously, without significantly reducing the treatment capacity of the entire liquid treatment facility.

[0071] Furthermore, since the second biofilm outflow prevention device 30B has a structure in which the baffle 40 is provided around the membrane unit 20, it can be easily installed in an existing membrane unit 20. Therefore, the second biofilm outflow prevention device 30B can be easily introduced into the treatment tank 11 without being affected by the shape of the existing treatment tank 11, etc.

[0072] Furthermore, the second biofilm outflow prevention device 30B surrounds the upper part (nearby part) of one membrane unit 20, thereby preventing the biofilm 24 from flowing out from the upper part of the membrane unit 20. Therefore, compared to the first biofilm outflow prevention device 30A, which prevents the biofilm 24 just before the treatment water channel 13, the impact of the biofilm 24 detached from the hollow fiber membrane 23 on the treatment of the treated liquid S throughout the liquid treatment equipment 10 can be reduced.

[0073] Furthermore, the second biofilm outflow prevention device 30B surrounds the upper part (nearby part) of one membrane unit 20, thereby preventing the biofilm 24 from flowing out from the upper part of the membrane unit 20. Therefore, in a liquid treatment facility (e.g., a small-scale liquid treatment facility) in which scouring of the membrane unit 20 is performed on each unit, scouring of the membrane unit 20 and treatment of the treated liquid S can be performed efficiently.

[0074] In this embodiment, the movable weir 31 is operated by driving the air cylinder 33, but this is not limitative, and the movable weir 31 may also be operated by driving a motor.

[0075] Furthermore, in this embodiment, the movable weir 31 is constructed as a flat weir, but this is not limited to this, and as long as the weir level (overflow height) at the boundary between the treatment tank 11 and the treatment water channel 13 is changeable, it may be a system in which the weir level (overflow height) is increased by the buoyancy generated by filling the inside of the weir with air or the like.

[0076] Furthermore, in this embodiment, the treatment water channel 13 is constructed by a concave groove, but this is not limited to this, and the structure may also be such that a portion of the pipe member is opened so that the treated liquid S can flow inside.

[0077] Furthermore, in this embodiment, the upper portion of the baffle 40 is formed vertically as shown in FIG. 9 , but this is not limiting. The upper portion of the baffle 40 may be formed to expand outward as shown in FIG. 10 . That is, the portion that restricts the flow F1 of the liquid S to be treated above the membrane unit 20 and that is formed to surround the membrane unit 20 may be formed with a gradually expanding diameter. By forming the upper portion of the baffle 40 in this manner, the volume of the liquid S to be treated above the baffle 40 (the volume of the liquid S to be treated that can be restricted in flow) increases compared to when the upper portion of the baffle 40 is formed vertically, making it more difficult for the liquid S to overflow the baffle 40. Therefore, the biofilm 24 that flows out together with the liquid S to be treated can be efficiently blocked before it flows out of the membrane unit 20.

[0078] Furthermore, as shown in FIG. 11 , the upper portion of the baffle 40 may be formed so as to narrow inward. That is, the portion that restricts the flow F1 of the liquid S to be treated at the upper portion of the membrane unit 20 and is formed so as to surround the membrane unit 20 may be formed with a gradually narrowing diameter. By forming the upper portion of the baffle 40 in this manner, the upper portion of the baffle 40 is formed to be inclined in the opposite direction to the flow F1 of the liquid S to be treated, so that the biofilm 24 that flows out together with the liquid S to be treated can be easily retained downward by the return of the upper portion of the baffle 40. Therefore, the biofilm 24 can be efficiently blocked before it flows out of the membrane unit 20. Note that, although the upper portion of the baffle 40 itself is formed so as to narrow inward in FIG. 11 , a return piece (not shown) extending inward may be provided for the upper portion of the baffle 40 that is formed vertically as shown in FIG. 9 . By providing a return piece on the upper part of the baffle 40 formed in the vertical direction, the diameter of the part that regulates the flow F1 of the liquid to be treated S above the membrane unit 20 can be gradually reduced. [Explanation of symbols]

[0079] 10 Liquid processing equipment 11 Treatment tank 13 Treatment channel (discharge section) 20 Membrane unit (liquid treatment device) 22 Diffuser pipe (air diffuser) 23 Hollow fiber membrane (gas permeable membrane) 24 Biofilm 30A 1st biofilm outflow prevention device (biofilm outflow prevention device) 30B 2nd biofilm outflow prevention device (biofilm outflow prevention device) F Flow of treated liquid F1 Flow of treated liquid S Liquid to be treated

Claims

1. a treatment tank to which the liquid to be treated is supplied; a liquid treatment device comprising: a gas-permeable membrane immersed in the liquid to be treated in the treatment tank and having gas permeability; and a biofilm formed on the outer surface of the gas-permeable membrane and utilizing an oxygen-containing gas supplied into the gas-permeable membrane, wherein the liquid to be treated is treated by the biofilm; a discharge section that discharges the liquid to be treated that has been treated by the liquid treatment device to the outside of the treatment tank; an air diffuser located below the gas-permeable membrane and supplying gas to the outside of the gas-permeable membrane; a biofilm outflow prevention device that prevents the biofilm peeled off from the gas-permeable membrane by the gas supplied from the air diffuser from flowing out of the treatment tank through the discharge section; Equipped with The biofilm outflow prevention device is a movable weir capable of regulating the flow of the liquid to be treated flowing from the treatment tank to the discharge part; The movable weir regulates the flow of the liquid to be treated, thereby blocking the biofilm flowing from the treatment tank to the discharge part, and preventing the biofilm from flowing from the treatment tank to the discharge part. Liquid treatment equipment characterized by:

2. the biofilm outflow prevention device includes a partition that regulates the flow of the liquid to be treated in the upper part of the liquid treatment device, The partition portion is a liquid treatment device surrounding the liquid treatment device and configured to be liftable relative to the liquid treatment device; The device rises so as to protrude above the liquid surface in the treatment tank and regulates the flow of the liquid to be treated, thereby blocking the biofilm flowing out from the liquid treatment device. The liquid treatment facility according to claim 1,

3. The partition portion is a portion that regulates the flow of the liquid to be treated, and the diameter of the portion that is formed to surround the liquid treatment device is gradually enlarged. The liquid treatment facility according to claim 2,

4. The partition portion is a portion that regulates the flow of the liquid to be treated, and the diameter of the portion that is formed to surround the liquid treatment device is gradually reduced. The liquid treatment facility according to claim 2,

5. The biofilm outflow prevention device is configured such that the movable weir is driven by the gas supplied to the air diffuser so that the air diffuser supplies the gas to the outside of the gas-permeable membrane. The liquid treatment facility according to any one of claims 1 to 4, characterized in that

6. a treatment tank to which the liquid to be treated is supplied; a liquid treatment device comprising: a gas-permeable membrane immersed in the liquid to be treated in the treatment tank and having gas permeability; and a biofilm formed on the outer surface of the gas-permeable membrane and utilizing an oxygen-containing gas supplied into the gas-permeable membrane, wherein the liquid to be treated is treated by the biofilm; a discharge section that discharges the liquid to be treated that has been treated by the liquid treatment device to the outside of the treatment tank; an air diffuser located below the gas-permeable membrane and supplying gas to the outside of the gas-permeable membrane; In a liquid treatment facility comprising: a biofilm detachment step of detaching the biofilm from the gas-permeable membrane by the gas supplied by the air diffuser; a biofilm outflow prevention step of preventing the biofilm peeled off from the gas-permeable membrane in the biofilm peeling step from flowing out of the treatment tank through the discharge part; Including, In the biofilm outflow prevention step, a movable weir is provided in the treatment tank and capable of regulating the flow of the liquid to be treated flowing from the treatment tank to the discharge part, thereby regulating the flow of the liquid to be treated, thereby blocking the biofilm flowing from the treatment tank to the discharge part and preventing the biofilm from flowing from the treatment tank to the discharge part. A liquid treatment method in a liquid treatment facility, comprising:

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