JP2023032024A - Membrane separation device - Google Patents

Abstract

To provide a membrane separation device which is multistaged with multiple membrane modules juxtaposed in a vertical direction, and which can adequately restrict deposition of organic matters and the like on membrane surfaces up to an upper stage membrane module.SOLUTION: In a membrane separation device, two or more membrane modules 22 are juxtaposed in a vertical direction in a membrane separation unit 23, and an air diffuser 110 is disposed below the lowest membrane module 22 in the membrane separation unit. The outer peripheral parts of the membrane modules 22 comprise cover plates 52. In addition, a coupling auxiliary plate 53 is provided at a coupling part of the membrane modules that are juxtaposed in the vertical direction.SELECTED DRAWING: Figure 3

Description

The present invention relates to a membrane separation device.

Industrial wastewater and domestic wastewater are treated to remove organic substances and the like contained in the wastewater, and then reused as industrial water or discharged into rivers and the like. Examples of methods for treating industrial wastewater include an activated sludge method in which aerobic microorganisms decompose organic matter by aeration.

Treatment by the membrane separation activated sludge (MBR) method, which combines treatment by the activated sludge method and membrane filtration using a membrane module, is known. In the treatment by the MBR method, as the membrane filtration continues, organic matter and the like accumulate on the surface of the separation membrane, which may cause a decrease in the filtration flow rate and an increase in the transmembrane pressure difference. Therefore, in the treatment by the MBR method, an air diffuser is generally installed below the membrane module, and the air bubbles generated by the air diffuser come into contact with the surface of the membrane. By vibrating, deposition of organic substances and the like on the film surface is suppressed.

Various methods have been studied for solid-liquid separation of activated sludge using membrane modules in which separation membranes such as microfiltration membranes and ultrafiltration membranes are arranged. A multi-stage membrane separation apparatus in which a plurality of membrane modules are arranged vertically is known (Patent Documents 1 and 2).

A multi-stage membrane separation apparatus is proposed when it is necessary to secure a large membrane area for treatment and a large depth of water, such as in a large-scale sewage treatment facility. The use of a multi-stage membrane separator leads to a reduction in the installation area of the membrane module.

WO2014/104135 WO2021/015156

However, in the conventional membrane separation apparatus as disclosed in Patent Document 1, it is difficult to sufficiently suppress the deposition of organic matter and the like on the membrane surface in the upper membrane module.

In the membrane separation device as disclosed in Patent Document 2, the air bubbles diffused from the lower air diffuser may not be collected by the air diffuser between the membrane modules, and the effect of suppressing the deposition of organic matter on the membrane surface is not obtained. Hateful. It is possible to suppress the deposition of organic matter by increasing the amount of air diffused from the air diffuser, but this reduces the energy saving effect and increases the cost.

The present invention provides a multistage membrane separation apparatus in which a plurality of membrane modules are arranged vertically, in which deposition of organic matter and the like on the membrane surface can be sufficiently suppressed up to the upper membrane modules, and which is energy-saving and low-cost. intended to

The present invention has the following aspects.
[1] A membrane separation unit in which two or more membrane modules are arranged vertically, an air diffuser arranged below the membrane module at the bottom of the membrane separation unit, and the air diffuser. and a gas supply device for supplying gas to the device, wherein the membrane separation section and the air diffuser are immersed in the water to be treated, and a cover plate is provided on the outer peripheral portion of the membrane module.
[2] The membrane separation device according to [1], wherein a connecting auxiliary plate is installed at a connecting portion between the membrane modules arranged in the vertical direction.
[3] The membrane separation device according to [1] or [2], which is a membrane separation activated sludge device in which the membrane separation section and the air diffuser are immersed in sludge-containing treated water containing activated sludge.

According to the present invention, the membrane separation apparatus is a multi-stage type in which a plurality of membrane modules are arranged in a vertical direction, and the deposition of organic matter and the like on the membrane surface is sufficiently suppressed up to the upper membrane modules, and is energy-saving and low-cost. can provide

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic diagram which showed an example of the water treatment apparatus. 1 is a perspective view showing an example of a membrane separation section of the present invention; FIG. FIG. 3 is a perspective view of membrane modules arranged side by side in the vertical direction; FIG. 3 is a perspective view of a state in which membrane modules arranged in a vertical direction are separated; FIG. 3 is a front view showing an example of an air diffuser and a header; Figure 6 is a vertical cross-sectional view of the header of Figure 5; FIG. 6 is a plan view of the air diffuser of FIG. 5; FIG. 8 is a cross-sectional view of the air diffuser of FIG. 7 taken along line II. It is a sectional view explaining the operating mechanism of an air diffuser. It is a sectional view explaining the operating mechanism of an air diffuser. It is a sectional view explaining the operating mechanism of an air diffuser. It is a sectional view explaining the operating mechanism of an air diffuser. It is a sectional view explaining an operating mechanism of a header. It is a sectional view explaining an operating mechanism of a header.

An example of an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the dimensions and the like of the drawings illustrated in the following description are only examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope of not changing the gist of the present invention. .

[Water treatment equipment]
The water treatment apparatus 1000 comprises, as shown in FIG. and Furthermore, although illustration is omitted, the water treatment apparatus 1000 includes a flow rate adjustment tank for adjusting the flow rate of raw water flowing into the activated sludge treatment tank 11, a drawing pump for drawing excess sludge from the membrane separation tank 21, and a It is provided with a liquid feeding means for feeding a chemical solution or dilution water, and a discharging means for discharging the treated water from the treated water tank 41 to a factory, a river, or the like.

The activated sludge treatment tank 11 is filled with activated sludge for performing activated sludge treatment.
A first channel 12 and a second channel 13 are connected to the activated sludge treatment tank 11 . The first channel 12 is a channel through which raw water discharged from factories, households, etc. flows into the activated sludge treatment tank 11 . The second flow path 13 is a flow path for allowing sludge-containing treated water (water to be treated) discharged from the activated sludge treatment tank 11 to flow into the membrane separation tank 21 .

An aerator 14 is installed in the activated sludge treatment tank 11 to maintain the inside of the tank in an aerobic condition. The aeration device 14 includes an aeration pipe 14a for aerating the inside of the activated sludge treatment tank 11, an introduction pipe 14b for supplying gas to the aeration pipe 14a, and a blower 14c for feeding the gas. The aeration pipe 14a is not particularly limited as long as it can discharge the gas supplied from the blower 14c upward, and examples thereof include a perforated single pipe and a membrane type.

The membrane separation tank 21 stores sludge-containing treated water containing activated sludge and biologically treated water sent from the activated sludge treatment tank 11 .
The membrane separation tank 21 includes a membrane separation activated sludge apparatus 100 (hereinafter sometimes referred to as "MBR apparatus 100") to which one aspect of the membrane separation apparatus of the present invention is applied. The MBR device 100 will be described later.

A sludge return means 30 is connected to the membrane separation tank 21 and the activated sludge treatment tank 11 . The sludge return means 30 returns part of the sludge-containing treated water from the membrane separation tank 21 to the activated sludge treatment tank 11 .
The sludge return means 30 has a fourth flow path 31 . The fourth channel 31 is a channel for discharging part of the sludge-containing treated water from the membrane separation tank 21 and allowing it to flow into the activated sludge treatment tank 11 .
A pump 31 a is installed in the fourth flow path 31 . As a result, part of the sludge-containing treated water in the membrane separation tank 21 can be returned from the membrane separation tank 21 to the activated sludge treatment tank 11 .

The treated water tank 41 stores the treated water after membrane separation of the sludge-containing treated water.

[Membrane separation device]
The MBR device 100 includes a membrane separation section 23 in which two or more membrane modules 22 are arranged vertically, and an air diffuser 110 arranged below the lowest membrane module 22 of the membrane separation section 23. and a gas supply device 150 that supplies gas to the air diffuser 110 . In the membrane separation tank 21, both the membrane separation section 23 and the air diffuser 110 are arranged in a state of being immersed in the sludge-containing treated water (water to be treated).

(Membrane separation part)
The membrane separation section 23 of this example is formed by two membrane modules 22 arranged side by side in the vertical direction. The number of membrane modules 22 arranged vertically in the membrane separation section 23 can be appropriately set according to the size of the membrane separation tank 21, and can be set to 2 to 5, for example.

The membrane module 22 membrane-separates sludge-containing treated water containing activated sludge. As shown in FIG. 2, the membrane module 22 includes a separation membrane 51, which separates sludge-containing treated water into biologically treated water and activated sludge by solid-liquid separation (membrane separation). The plane view shape of the separation membrane of the membrane module 22 of this example is a rectangular shape. Note that the planar view shape of the separation membrane is not limited to a rectangular shape.

The separation membrane 51 is not particularly limited as long as it has separation ability, and examples thereof include hollow fiber membranes, flat membranes, tubular membranes, monolithic membranes, and the like. Among these membranes, hollow fiber membranes are preferred because of their high volume filling factor. For example, by arranging a plurality of hollow fiber membranes to form a sheet, a separation membrane having a rectangular planar shape can be obtained.

When a hollow fiber membrane is used as the separation membrane 51, its material includes, for example, cellulose, polyolefin, polysulfone, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and the like. Among these, PVDF and PTFE are preferable as the material for the hollow fiber membrane because of their chemical resistance and resistance to pH changes.
When a monolithic membrane is used as the separation membrane, it is preferable to use a ceramic membrane.

The average pore diameter of the micropores formed in the separation membrane 51 is about 0.001 to 0.1 μm for a membrane generally called an ultraseparation membrane, and about 0.1 to 1 μm for a membrane generally called a precision separation membrane. be. In the present embodiment, it is preferable to use a separation membrane having an average pore size within the above range.

A third channel 33 is connected to the membrane module 22 . The third channel 33 is a channel for discharging the treated water that has passed through the separation membrane 51 from the membrane separation tank 21 and allowing it to flow into the treated water tank 41 .
A pump 33 a is installed in the third flow path 33 . This allows the treated water that has passed through the separation membranes of the membrane module 22 to be discharged from the membrane separation tank 21 .

In the membrane separation section 23 of the MBR device 100, a plurality of membrane modules 22 are arranged side by side in the direction perpendicular to the surface direction of the separation membranes 51 of the membrane modules 22 also in the horizontal direction. The vertical positions of the plurality of membrane modules 22 on the first stage from the bottom in the membrane separation section 23 are aligned with each other. The vertical positions of the plurality of membrane modules 22 in the second stage from the bottom in the membrane separation section 23 also match each other. Both ends in the plane direction of the plurality of membrane modules 22 arranged in the horizontal direction are fixed by frames 50 respectively.
The number of membrane modules 22 arranged in the horizontal direction can be appropriately set according to the size of the membrane separation tank 21, and can be set to 2 to 5000, for example.

As shown in FIG. 3 , a cover plate 52 is provided around the peripheries of the membrane modules 22 arranged side by side in the vertical direction so as to surround the peripheries of the membrane modules 22 . The cover plate may surround a portion of the outer periphery, or may surround the entire outer periphery as shown in FIG.

The material of the cover plate 52 is not particularly limited, and examples thereof include metal such as stainless steel (SUS304 series, SUS316 series). In addition, polyethylene, polypropylene, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylic resin (polymethyl methacrylate (PMMA), etc.), polyvinyl chloride resin (PVC), polyacetal resin (POM), Polyamide resin (PA), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polycarbonate resin (PC), modified polyphenylene ether resin (PPE), polyphenylene sulfide resin (PPS), polyether ether ketone resin (PEEK) ), polysulfone resin (PSf), polyethersulfone resin (PES), and the like. The material of the cover plate 52 can be selected according to the size, weight and required strength of the membrane module 22 .

One cover plate 52 to be installed on the outer peripheral portion of the membrane module 22 may be installed on each surface of the outer peripheral portion, or a plurality of cover plates 52 may be installed on one surface depending on the size of the membrane module 22. . The cover plate 52 may also be installed in the portion between the membrane modules 22 arranged side by side in the vertical direction.

As shown in FIG. 3, a connecting auxiliary plate 53 is installed at the connecting portion between the membrane modules 22 arranged in the vertical direction to prevent the membrane modules 22 from sliding in the liquid to be treated. is preferred. This is because even if there is a manufacturing error in the dimensions of each module membrane 22, the connecting auxiliary plate can suppress sliding due to the manufacturing error. In this example, connecting auxiliary plates 53 are provided on the top of the frames 50 arranged on both sides of each separation membrane 51 of the membrane module 22 in the first stage so as to stand up, so that the two connecting auxiliary plates 53 are provided. The second stage membrane module 22 arranged between the plates 53 is prevented from sliding with respect to the first stage membrane module 22 . The connection auxiliary plate 53 that suppresses the sliding of the membrane modules 22 serves also for alignment when arranging the membrane modules 22 side by side in the vertical direction, and does not fix the vertical movement of the membrane modules 22 after arrangement. It has a structure. Therefore, as shown in FIG. 4, the arrangement and separation of the membrane modules 22 are facilitated.
By providing connection auxiliary plates 53 at the lower portions of the frames 50 arranged on both sides of each separation membrane 51 of the membrane module 22 of the second stage, the membrane module 22 of the first stage and the membrane module of the second stage can be separated. 22 may be prevented from sliding in the liquid to be treated.

Examples of the material of the connection auxiliary plate 53 include metals such as stainless steel (SUS304 series, SUS316 series). An L-angle member may be used to ensure strength to prevent bending and breakage when in contact with the membrane module 22 .

(Air diffuser)
The air diffuser 110 is a siphon air diffuser, ie, an air diffuser with a siphon air diffuser tube. In the present invention, it is preferable to provide a siphon air diffuser from the viewpoint of energy saving, low cost, and easy suppression of deposition of organic matter and the like on the membrane surface of the membrane module 22 . As long as it does not impair the effects of the present invention, it may be an air diffuser equipped with a known air diffuser other than the siphon air diffuser.

Below the membrane module 22 of the membrane separation unit 23 , a plurality of air diffusers 110 are provided side by side in the horizontal direction perpendicular to the surface direction of the separation membranes of the membrane module 22 . In each air diffuser 110, the air diffusion holes 126 of the siphon type air diffuser 120 described later are located between the adjacent membrane modules 22 in a plan view, and the length direction of the air diffusion holes 126 (the length of the air diffuser 110) direction) coincides with the plane direction of the membrane module 22 .

The number of air diffusers 110 arranged in the horizontal direction can be appropriately set according to the size of the membrane separation tank 21 and the number of membrane modules 22 arranged in the horizontal direction. can be done.

As shown in FIG. 5 , the air diffuser 110 includes a horizontally extending horizontal tube 116 and three distribution sections spaced along the length of the horizontal tube 116 to distribute gas from the horizontal tube 116 . 118 and six siphon air diffusers 120 arranged in a horizontal row.

Each distribution portion 118 is connected to the horizontal pipe 116 via a connecting pipe portion 119 and is provided to extend downward from the horizontal pipe 116 . Six siphon air diffusers 120 are arranged below the horizontal tube 116 along the length of the horizontal tube 116 with two siphon air diffusers 120 on either side of each distribution section 118 . ing.

The siphon air diffuser 120 is a box-shaped housing formed by combining a plurality of plate-shaped members. As shown in FIGS. 5 and 7 to 9, the siphon diffuser 120 includes an upper plate portion 120A, two side plate portions 120B, two side plate portions 120C, a bottom plate portion 120D, and a first partition wall. 122 and a second partition wall 124 .

The two side plate portions 120B and the two side plate portions 120C forming each siphon diffuser pipe 120 are each rectangular, and the side plate portion 120B is wider than the side plate portion 120C. As shown in FIGS. 7 and 8, the two side plate portions 120B and the two side plate portions 120C forming each siphon diffuser 120 are such that the surfaces of the side plate portions 120B face each other and the surfaces of the side plate portions 120C face each other. are provided so as to extend downward from the lower surface of the upper plate portion 120A. The two side plate portions 120B and the two side plate portions 120C form a rectangular cylinder with a rectangular cross section. In each siphon air diffusion pipe 120 , the surface direction of the side plate portion 120</b>B is parallel to the longitudinal direction of the horizontal pipe 116 .

In the air diffuser 110, the upper plate portions 120A of the six siphon type air diffusion pipes 120 are integrally formed of one flat plate, and the side plate portions 118B on both sides of the six siphon type air diffusion pipes 120 are each integrally formed of one flat plate. is formed in The six siphon-type air diffusers 120 are connected so that the surfaces of the side plate portions 120C of the adjacent siphon-type air diffusers 120 face each other.

As shown in FIG. 7, a rectangular ventilation hole 126 extending along the side plate portion 120B is formed in a portion of each upper plate portion 120A near the side plate portion 120B on the far side from the horizontal pipe 116 in plan view. It is As shown in FIG. 9, the bottom plate portion 120D extends inward from a portion near the lower end of the side plate portion 120B on the side where the air diffusion holes 126 are formed. The plane direction length of the bottom plate portion 120D from the side plate portion 120C is shorter than the top plate portion 120A. The bottom plate portion 120D covers almost half of the lower opening of the rectangular tube formed by the two side plate portions 120B and the two side plate portions 120C, and the bottom plate portion 120D does not cover the opening portion. A treated water inflow portion 127 is provided. In this manner, the siphon air diffuser 120 has a treated water inlet 127 formed at the bottom opening.

The first partition wall 122 has a rectangular shape in a front view, and extends downward from the upper plate portion 120A so that the side plate portion 120B and the side plate portion 120B face each other with the air diffusion hole 126 interposed therebetween. . A lower end 122a of the first partition wall 122 is separated from the bottom plate portion 120D. The treated water inflow portion 127 is located below the lower end 122 a of the first partition wall 122 .

The second partition wall 124 is provided so as to extend upward from the end of the first partition wall 122 of the bottom plate portion 120D located on the side opposite to the diffusion holes 126 . The surfaces of the first partition wall 122 and the second partition wall 124 face each other. The upper end 124a of the second partition wall 124 is separated from the upper plate portion 120A. The upper end 124 a of the second partition wall 124 is located above the lower end 122 a of the first partition wall 122 .

A siphon chamber 128 is formed inside the siphon air diffuser 120 . The siphon chamber 128 is a portion that stores gas. The siphon chamber 128 has a height from the upper end 124a of the second partition wall 124 to the lower end 122a of the first partition wall 122 on the treated water inflow portion 127 side of the first partition wall 122 in the siphon air diffusion pipe 120. point to space. The siphon chamber 128 is divided by a second partition wall 124 into a first siphon chamber 128A and a second siphon chamber 128B.

A communicating portion 125 communicates with the upper portion of the first siphon chamber 128A and the upper portion of the second siphon chamber 128B. A portion from the second siphon chamber 128B in the siphon-type air diffusion pipe 120 to the air diffusion hole 126 forms a path 123. As shown in FIG. In the siphon-type air diffuser 120, the treated water inflow portion 127 side is defined as "upstream" and the air diffusion hole 126 side is defined as "downstream" when the water to be treated flows from the treated water inflow portion 127 to the diffusion holes 126. ”.

The material of the siphon air diffuser 120 is not particularly limited, and examples include polyethylene, polypropylene, acrylonitrile-styrene (AS) resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylic resin (polymethyl methacrylate (PMMA), etc.), Polyvinyl chloride resin (PVC), polyacetal resin (POM), polyamide resin (PA), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polycarbonate resin (PC), modified polyphenylene ether resin (PPE), polyphenylene Sulfide resins (PPS), polyetheretherketone resins (PEEK), polysulfone resins (PSf), polyethersulfone resins (PES), and the like. The material of the siphon type air diffuser 120 may be of one type or a combination of two or more types. It may also be made of metal such as stainless steel (SUS304 series, SUS316 series).

The shape of the horizontal tube 116 is not particularly limited, and examples thereof include a cylindrical shape and a polygonal cylindrical shape. For example, when the cross-sectional shape of the horizontal tube 116 is circular, the internal diameter of the horizontal tube 116 is preferably 10 mm or more.

The cross-sectional area of the horizontal tube 116 is preferably 100 mm ² or more, more preferably 300 mm ² or more and 2000 mm ² or less. If the cross-sectional area of the horizontal pipe 116 is equal to or greater than the lower limit of the above range, the inside of the horizontal pipe 116 is less likely to be clogged with sludge. If the channel cross-sectional area of the horizontal pipe 116 is equal to or less than the upper limit of the above range, the air diffuser 110 will be compact. The channel cross-sectional area of the horizontal pipe 116 is the minimum value of the cross-sectional area of the channel when the horizontal pipe 116 is cut in a direction (vertical direction) perpendicular to the length direction of the horizontal pipe 116 .

The horizontal pipe 116 is not particularly limited, and examples thereof include resin pipes and tubes, metal pipes, and the like. Examples of resins that make up resin pipes and tubes include polyvinyl chloride, polyethylene, polypropylene, PTFE, PVDF, fluorine-based resins such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), nylon, and polyurethane. etc. Examples of the metal that constitutes the metal pipe include stainless steel (SUS304 series, SUS316 series) and the like. The material of the horizontal tube 116 may be of one type or a combination of two or more types.

As shown in FIGS. 7 and 8, the distribution section 118 of this example is provided so as to connect the two opposing side plate sections 120C of the siphon air diffusion pipes 120 on both sides and the ends of the side plate sections 120C. A cylindrical top plate portion 132 is formed by two side plate portions 130 and a top plate portion 132 provided so as to close the upper open end of the rectangular cylinder composed of the two side plate portions 120C and the two side plate portions 130. part. The distribution section 118 in this example shares the side plate section 120C with the siphon air diffusers 120 on both sides. A pair of side plate portions 130 and a top plate portion 132 forming the distribution portion 118 are integrated with the adjacent siphon air diffuser pipes 120 .

An opening 118a is formed on the side of the distribution portion 118 opposite to the horizontal pipe 116 . The opening portion 118a is composed of a lower open end of the distribution portion 118 and a notch portion 134 formed in the lower end portion of the side plate portion 120C shared with the siphon air diffuser 120 in the distribution portion 118 . The opening 118 a of the distributor 118 functions as a gas supply port that supplies gas to the siphon diffuser 120 .

The material of the distribution part 118 is not particularly limited, and for example, the same material as that of the siphon air diffuser 120 can be used. The material of the distribution part 118 may be of one type or a combination of two or more types.

The channel cross-sectional area of the distribution part 118 is preferably 300 mm ² or more, more preferably 500 mm ² or more. On the other hand, 3000 mm ² or less is preferable. If the cross-sectional area of the distribution section 118 is equal to or greater than the lower limit of the above range, the inside of the distribution section 118 is less likely to be clogged with sludge. If the channel cross-sectional area of the distribution part 118 is equal to or less than the upper limit of the above range, the air diffuser 110 becomes compact. The channel cross-sectional area of the distribution portion 118 is the minimum value of the cross-sectional area of the channel when the distribution portion 118 is cut in the direction (horizontal direction) perpendicular to the length direction of the channel in the distribution portion 118. .

The horizontal pipe 116 and the distribution section 118 are connected via a connecting pipe section 119 having a flow channel cross-sectional area smaller than that of the distribution section 118 so that the flow channel in the horizontal pipe 116 and the flow channel in the distribution section 118 are connected. ing. The shape of the connecting tube portion 119 is not particularly limited, and examples thereof include a cylindrical shape and a polygonal tubular shape.

The cross-sectional area of the flow path of the connecting tube portion 119 is preferably 20 mm ² or more, more preferably 28 mm ² or more, still more preferably 35 mm ² or more, and particularly preferably 40 mm ² or more. On the other hand, it is preferably 350 mm ² or less, more preferably 200 mm ² or less, even more preferably 100 mm ² or less, and particularly preferably 60 mm ^{2 or} less. If the cross-sectional area of the connecting pipe portion 119 is equal to or greater than the lower limit of the above range, the inside of the connecting pipe portion 119 is less likely to be clogged with sludge. If the flow passage cross-sectional area of the connection tube portion 119 is equal to or less than the upper limit value of the above range, the gas is easily distributed to the siphon air diffusion tubes 120 evenly. The flow channel cross-sectional area of the connection pipe portion 119 is the minimum value of the cross-sectional area of the flow channel when the connection pipe portion 119 is cut in a direction perpendicular to the length direction of the flow channel in the connection pipe portion 119 . At least a portion of the connecting tube portion 119 preferably has a cross-sectional area of 20 mm ² or more and 350 mm ² or less.

The material of the connecting tube portion 119 is not particularly limited, and examples thereof include the same materials as those mentioned for the horizontal tube 116 . The connection pipe portion 119 may be made of one material or a combination of two or more materials.

In the air diffusion device 110, the siphon type air diffusion pipes 120 and the distribution sections 118 arranged alternately are integrated. Since the air diffuser 110 of this aspect does not require vertical alignment of the opening 118a of the distribution unit 118 and vertical alignment of each siphon type air diffuser 120, each siphon type air diffuser 120 It becomes easy to evenly disperse from. In addition, the assembly work of the air diffuser 110 is facilitated, and the number of parts can be reduced, which is advantageous in terms of cost.

In the air diffuser 110 , each siphon air diffuser 120 is provided below a horizontal tube 116 . Since the horizontal pipe 116 is positioned above each siphon diffuser pipe 120 , the gas can be evenly supplied to each siphon diffuser pipe 120 from the opening 118 a of each distribution part 118 . It can be diffused evenly. In addition, since the height of the MBR device 100 can be made lower than in the case of using an air diffuser having members on the upper side of the horizontal pipe, the MBR device 100 can be made compact.

When the membrane separation tank 21 is viewed from above, the air diffuser 110 is provided at a position where the gap between the adjacent separation membranes in the membrane module 22 and the air diffusion holes 126 of the siphon type air diffusers 120 overlap. preferable. Incidentally, the air diffuser 110 may be provided so that the air diffusion holes 126 of the siphon type air diffusion pipes 120 intersect the membrane modules 22 when the membrane separation tank 21 is viewed from above.

(header)
The MBR device 100 in this example further comprises a header 200. FIG. The header 200 is arranged in the membrane separation tank 21 in a state of being immersed in the sludge-containing treated water (to-be-treated water) together with the membrane separation section 23 and the air diffuser 110 .
The header 200 includes a gas storage section 210, an air supply section 212, and an air supply section 214, as shown in FIGS.

The gas storage part 210 is a part that stores gas, and includes a cylindrical body part 216 and an upper plate part 218 provided to close an upper open end of the body part 216 . The lower end side of body portion 216 in gas reservoir 210 is open. That is, the gas reservoir 210 has a water inlet 210a formed at its lower portion. The shape of the gas reservoir 210 is not particularly limited, and examples thereof include a cylindrical shape and a polygonal tubular shape.

When the gas reservoir 210 is cut horizontally, the cross-sectional area of the gas reservoir is preferably 10,000 mm ² or more, more preferably 20,000 mm ² or more, and preferably 1,000,000 mm ² or less. If the cross-sectional area of gas reservoir 210 is equal to or greater than the lower limit of the range, gas reservoir 210 is less likely to be clogged with sludge. If the cross-sectional area of the gas reservoir 210 is equal to or less than the upper limit of the range, the air diffuser 110 becomes compact.

In the header 200 , an air supply portion 212 and an air supply portion 214 are provided on the upper plate portion 218 of the gas storage portion 210 . Thus, the air supply section 212 and the air supply section 214 are provided above the gas storage section 210 . In the header 200 , an air supply section 212 is provided on the side farther from the air diffuser 110 than the air supply section 214 in the gas storage section 210 . This makes the layout simpler and the MBR device 100 more compact.

The air supply portion 212 has a cylindrical shape and is provided so as to penetrate the upper plate portion 218 of the gas reservoir portion 210 . The air supply unit 212 is connected to the blower 152 of the gas supply device 150 shown in FIG. 1 via a pipe 154 . As a result, the gas sent from the blower 152 through the pipe 154 is sent from the air supply portion 212 into the gas storage portion 210 .

The shape of the air supply portion 212 is not particularly limited, and examples thereof include a cylindrical shape and a polygonal tubular shape. The flow passage cross-sectional area of the air supply portion 212 is preferably 2000 mm ² or more, more preferably 3000 mm ² or more, and preferably 8000 mm ² or less. If the flow passage cross-sectional area of the air supply part 212 is equal to or greater than the lower limit of the range, the air supply part 212 is less likely to be clogged with sludge. If the channel cross-sectional area of the air supply part 212 is equal to or less than the upper limit value of the above range, the air diffuser 110 becomes compact. The channel cross-sectional area of the air supply portion 212 is the minimum value of the cross-sectional area of the channel when the air supply portion 212 is cut in the direction perpendicular to the length direction of the channel in the air supply portion 212 .

The air supply portion 214 is a portion to which the gas in the gas storage portion 210 is sent, and is provided in a cylindrical shape so as to protrude upward from the upper plate portion 218 of the gas storage portion 210 . The air supply portion 214 of the header 200 is connected to the horizontal pipe 116 of the air diffuser 110 via a connecting pipe 220 . As a result, the gas stored in the gas storage section 210 is sent from the air supply section 214 to the horizontal pipe 116 of the air diffuser 110 .

The shape of the air supply portion 214 is not particularly limited, and examples thereof include a cylindrical shape and a polygonal tubular shape. The flow passage cross-sectional area of the air supply portion 214 is preferably 100 mm ² or more, more preferably 300 mm ² or more, and preferably 2000 mm ² or less. If the flow passage cross-sectional area of the air supply portion 214 is equal to or greater than the lower limit of the range, the air supply portion 214 is less likely to be clogged with sludge. If the channel cross-sectional area of the air supply part 214 is equal to or less than the upper limit value of the range, the air diffuser 110 becomes compact. The flow channel cross-sectional area of the air feeding portion 214 is the minimum value of the cross-sectional area of the flow channel when the air feeding portion 214 is cut in the direction perpendicular to the length direction of the flow channel in the air feeding portion 214 .

In the header 200 , the air supply port 214 a of the air supply portion 214 opening into the gas storage portion 210 is located above the air supply port 212 a of the air supply portion 212 opening into the gas storage portion 210 . In the present invention, the positional relationship in the height direction between the air supply port that opens into the gas reservoir of the air supply unit and the air supply port that opens into the gas storage unit of the air supply unit is If the air supply openings of the air section do not open downward, the upper end of these air supply openings or the air supply opening is used as the reference. In the case where the gas reservoir has a plurality of air supply ports opening into the gas reservoir, the uppermost air supply port is used as a reference.

Positioning the air supply port 214a of the air supply unit 214 above the air supply port 212a of the air supply unit 212 makes it difficult for sludge to enter the horizontal pipe 116 of the air diffuser 110 from the gas storage unit 210. Clogging of the horizontal pipe 116 and the connecting pipe portion 119 with sludge is suppressed.

A height difference h1 between the air supply port 214a of the air supply unit 214 and the air supply port 212a of the air supply unit 212 is preferably 50 mm or more, more preferably 100 mm or more. On the other hand, 500 mm or less is preferable, and 300 mm or less is more preferable. If the difference h1 is equal to or greater than the lower limit value of the above range, it is easy to prevent sludge from entering the air diffuser 110 from the header 200 . If the difference h1 is equal to or less than the upper limit of the range, the diffuser 110 will be compact.

The air supply port 212 a of the air supply part 212 in the header 200 is positioned above the opening 118 a of the distribution part 118 in the air diffuser 110 . In the present invention, when the air diffuser is provided with a distribution portion extending downward from the horizontal pipe, the position of the air supply port of the air supply portion of the header in the height direction is the same as the position of the opening of the distribution portion. or higher than that. As a result, when the operation is stopped, the rise of the water level in the gas storage section stops when it reaches the air supply port of the air supply section, so that the effect of suppressing the intrusion of sludge from the header into the air diffuser is sufficiently obtained. easier. In the present invention, the positional relationship in the height direction between the air supply port opened in the gas reservoir of the air supply unit and the opening of the distribution unit is such that the air supply port of the air supply unit and the opening of the distribution unit open downward. If not, the upper edge of those air inlets or openings shall be the reference. In the case where the gas reservoir has a plurality of air supply ports opening into the gas reservoir, the uppermost air supply port is used as a reference.

A height difference h2 between the air supply port 212a of the air supply part 212 and the opening 118a of the distribution part 118 is preferably 5 mm or more, more preferably 10 mm or more. On the other hand, 200 mm or less is preferable, and 180 mm or less is more preferable. If the difference h2 is equal to or greater than the lower limit value of the range, it is easy to prevent sludge from entering the air diffuser 110 from the header 200 . If the difference h2 is equal to or less than the upper limit of the range, the diffuser 110 will be compact.

The air supply port 212 a of the air supply part 212 in the header 200 is located below the lower end 119 a of the connecting pipe part 119 of the air diffuser 110 . As described above, in the present invention, when the horizontal pipe and the distribution section are connected by a connecting pipe section having a flow passage cross-sectional area smaller than that of the distribution section, the air supply of the air supply section of the header is provided. It is preferable that the port is positioned above the lower end of the connecting tube portion. As a result, clogging of the connection pipe portion with sludge can be easily suppressed.

A height difference h3 between the air supply port 212a of the air supply part 212 and the lower end 119a of the connecting pipe part 119 is preferably 50 mm or more, more preferably 100 mm or more. On the other hand, 180 mm or less is preferable. If the difference h3 is equal to or greater than the lower limit value of the range, clogging of the connecting pipe portion 119 with sludge can be easily suppressed. If the difference h3 is equal to or less than the upper limit of the above range, the diffuser 110 will be compact.

The connecting pipe 220 that connects the air supply section 214 and the horizontal pipe 116 preferably has flexibility. As a result, even if the air diffuser 110 and the header 200 vibrate during operation, the vibration is absorbed by the connecting pipe 220 and mitigated, so that the air diffuser 110 and the header 200 are less likely to be damaged. In addition, "the connecting pipe has flexibility" means that the minimum bending radius is 1000 mm or less.

The flexible connecting pipe 220 may be made of any material as long as the connecting pipe 220 is flexible, and examples thereof include PVC hoses, silicone hoses, and fluorine hoses. The connection pipe 220 may be made of one material or two or more materials.

The flow passage cross-sectional area of the connecting pipe 220 is preferably 100 mm ² or more, more preferably 300 mm ² or more. On the other hand, 2000 mm ² or less is preferable. If the cross-sectional area of the connecting pipe 220 is equal to or greater than the lower limit of the above range, the connecting pipe 220 is less likely to be clogged with sludge. If the flow passage cross-sectional area of the connecting pipe 220 is equal to or less than the upper limit of the above range, the air diffuser 110 becomes compact. The flow channel cross-sectional area of the connecting pipe 220 is the minimum value of the cross-sectional area of the flow channel when the connecting pipe 220 is cut in a direction perpendicular to the length direction of the flow channel in the connecting pipe 220 .

The working mechanism of the MBR device 100 will be described below.
Before the start of operation, as shown in FIG. 9, the siphon chamber 128, the communication part 125 and the path 123 in the siphon type air diffuser pipe 120 of the air diffuser 110 are filled with sludge-containing treated water B (water to be treated). there is

Air is supplied from the blower 152 of the gas supply device 150 through the pipe 154, and as shown in FIG. Air can be used as the gas A, for example. In the header 200, the gas A is temporarily stored in the gas storage part 210 to push down the water surface S1, while part of the gas A is sent from the air supply part 214 to the horizontal pipe 116 of the air diffuser 110 through the connecting pipe 220. be done.

The gas sent to the horizontal pipe 116 is distributed to each distribution section 118 and sent to each siphon diffuser pipe 120 of the air diffuser 110 from the treated water inflow section 127 through the opening 118 a of the distribution section 118 . When the gas A is continuously supplied to the siphon type air diffuser pipe 120 of the air diffuser 110 in this way, as shown in FIG. The liquid is pushed out from the inflow portion 127 and the liquid surface S2 in the siphon chamber 128 gradually drops.

When the gas A continues to be supplied and the height of the liquid surface S2 becomes lower than the lower end 122a of the first partition wall 122, as shown in FIG. Due to the difference in interface height, the gas A moves to the path 123 and is released at once from the diffusion holes 126 to form bubbles 400 . Air bubbles 400 released from the air diffusion holes 126 rise inside the cover plate 52 surrounding the membrane module 22 of the membrane separation unit 23 and contact the membrane surface of the separation membrane 51 or are caused by the water flow accompanying the generation of the air bubbles 400. The separation membrane 51 is vibrated. Since the cover plate 52 is provided, the air bubbles 400 sufficiently act on the membrane module 22 in the upper stage, so that the deposition of organic matter on the surface of the separation membrane 51 can be prevented without excessively increasing the diffusion amount. Sufficiently suppressed.
When air is diffused through the air diffusion holes 126, as shown in FIG. Ascend to near. 10 to 12 are repeated to intermittently aerate the air diffuser 110. FIG.

When the operation is stopped, the airtightness in the vicinity of the blower 152 is not normally high, so the gas A in the gas reservoir 210 flows back from the air supply part 212, and as shown in FIG. S1 rises to the air supply port 212a of the air supply part 212. As shown in FIG. In the header 200, since the air supply port 214a of the air supply unit 214 is positioned above the air supply port 212a of the air supply unit 212, the air supply port 214a of the air supply unit 214 is kept away from the water surface S1 even when the operation is stopped. state. Therefore, even if the operation is repeatedly stopped and restarted, sludge is suppressed from entering the air diffuser 110 from the air supply unit 214 . As a result, clogging of the horizontal pipe 116 and the like with dried sludge is suppressed.

[Water treatment method]
A water treatment method using the water treatment apparatus 1000 described above will be described below. The water treatment method of the present embodiment includes an activated sludge treatment process for treating raw water using activated sludge, and a membrane separation process for membrane separation of the sludge-containing treated water obtained in the activated sludge treatment process. ing.

(Activated sludge treatment process)
In the water treatment method using the water treatment apparatus 1000, wastewater (raw water) such as industrial wastewater and domestic wastewater discharged from factories, households, etc. is allowed to flow into the activated sludge treatment tank 11 through the first flow path 12, and Activated sludge is treated in 11 to obtain biologically treated water. The sludge-containing treated water (to-be-treated water) after treatment is allowed to flow into the membrane separation tank 21 through the second flow path 13 .

(Membrane separation process)
In the membrane separation tank 21 , the membrane module 22 of the MBR device 100 membrane-separates sludge-containing treated water (water to be treated) containing activated sludge and biologically treated water. Aeration is performed by the air diffuser 110 during the membrane separation process.

A part of the sludge-containing treated water B is returned from the membrane separation tank 21 to the activated sludge treatment tank 11 by the sludge return means 30 . After membrane separation of the sludge-containing treated water B by the membrane module 22, the treated water is sent to the treated water tank 41 through the third channel 33 and stored therein. The treated water stored in the treated water tank 41 can be reused as industrial water or discharged into a river or the like.

In the water treatment method, the activated sludge treatment process and the membrane separation process may be performed simultaneously using a water treatment apparatus in which the MBR device 100 is provided in the activated sludge treatment tank 11 .

As described above, in the present invention, an air diffuser is arranged below the lowest membrane module in a multi-stage membrane separation unit in which two or more membrane modules are arranged in a vertical direction, Furthermore, a cover plate is arranged on the outer periphery of the membrane module. As a result, deposition of organic substances and the like on the membrane surface of the lower membrane module due to air bubbles diffused from the air diffuser is suppressed. In addition, deposition of organic matter and the like on the membrane surface is also suppressed in the membrane module on the upper side.
Furthermore, if a connection auxiliary plate is installed between the membrane modules installed side by side in the vertical direction, it is possible to suppress the sliding of the connection part of the membrane separation part immersed in the liquid to be treated. becomes. In addition, separation of the membrane separation part in the immersion tank becomes easy, and construction work such as transportation and installation using a crane becomes easy.
In addition, in the present invention, since water treatment is performed only with air bubbles diffused from the lowest air diffuser, energy saving and low cost can be achieved even in an apparatus equipped with a multi-stage membrane separation section.

22 Membrane module 23 Membrane separation section 51 Separation membrane 52 Cover plate 53 Auxiliary connection plate 100 Membrane separation activated sludge apparatus 110 Air diffuser 116 Horizontal pipe 118 Distributor , 118a... opening, 119... connecting tube, 120... siphon air diffuser, 150... gas supply device, 152... blower, 200... header, 210... gas reservoir, 210a... water inlet, 212... air supply Parts 212a... Air supply port 214... Air supply part 214a... Air supply port 216... Body part 218... Upper plate part 220... Connecting pipe.

Claims (3)

a membrane separation unit in which two or more membrane modules are arranged in a vertical direction; an air diffuser arranged under the lowest membrane module of the membrane separation unit; and a gas supply device that supplies the gas, wherein the membrane separation unit and the air diffusion device are immersed in the water to be treated, and a cover plate is provided on the outer peripheral portion of the membrane module. 2. The membrane separation apparatus according to claim 1, wherein a connection auxiliary plate is installed at a connection portion between the membrane modules arranged in the vertical direction. 3. The membrane separation apparatus according to claim 1, wherein said membrane separation unit and said air diffuser are a membrane separation activated sludge apparatus immersed in sludge-containing treated water containing activated sludge.

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