JP5495129B2 - Membrane element, membrane module and membrane separation system - Google Patents

Description

  The present invention relates to a membrane element, a membrane module and a membrane separation system used for solid-liquid separation, and more particularly to a membrane element, a membrane module and a membrane separation system used in membrane separation activated sludge treatment such as organic waste water.

  Conventionally, in the membrane separation activated sludge treatment of organic waste water or the like, an MBR (Membrane Bio Reactor: activated sludge membrane separation) system in which a membrane module is arranged has been used. In this type of MBR system, a membrane module that performs solid-liquid separation is disposed inside a reaction tank, and an air diffuser is provided below the membrane module. Here, the membrane module refers to one in which a plurality of membrane elements are integrated by arranging a plurality of membrane elements in parallel at regular intervals and accommodated in a casing. The membrane element is obtained by covering the surface of the membrane support plate with a filtration membrane, and a flow path through which filtered water flows is formed inside the membrane element. A pump that communicates with the flow path and creates a negative pressure in the flow path is provided outside the reaction tank. By driving this pump, the water to be treated passes through the filtration membrane, and suspended substances in the water to be treated are captured by the filtration membrane. And the clean filtration water permeate | transmitted through the filtration membrane and attracted | sucked by the flow path in a membrane element is taken out outside the processing tank. Moreover, the upward flow parallel to the surface of the filtration membrane is generated by the air lift action of the air bubbles diffused from the diffuser, and the deposits are detached from the filtration membrane.

  FIG. 9 shows a schematic plan view of the inside of the membrane element 4. When the treated water suction pump 12 connected to the membrane element 4 via the pipe 2 is driven, the treated water passes through a filtration membrane (not shown). The filtered water that has passed through the filtration membrane flows in the horizontal direction through the water channel 28 divided into a plurality by the partition plate 27, passes through the plurality of branch channels 15 </ b> A, and flows into the header channel 13. Then, the filtered water is sucked by the pump from the water collection port 14 of the header channel 13 and is taken out and collected.

  Here, when each branch channel 15A has the same cross-sectional area and the same shape, the resistance from the inlet of the filtered water to the water collection port 14 of the branch channel 15A is the branch channel 15A far from the water collection port 14. It gets higher. Therefore, the flow rate of the filtered water flowing into the header channel 13 from the branch channel 15 </ b> A decreases as the branch channel 15 </ b> A is far from the water collection port 14.

  Furthermore, since each branch flow path 15A is arranged in the vertical direction and the water collecting port 14 of the header flow path 13 is often provided at the top of the header flow path 13, in addition to the resistance due to pipe friction, Thus, resistance due to height loss is added. Therefore, the resistance from the inlet of the branch flow path 15A located at the position farthest from the water collection port 14, that is, the lowest position in the branch flow path 15A, to the water collection port 14 becomes the largest. The difference between the resistance and the resistance from the branch flow path 15A located closest to the water collection port 14 to the water collection port 14 is increased.

  Due to the difference in resistance from each branch flow path 15A to the water collecting port 14, the flow rate of the filtered treated water flowing through each branch flow path 15A becomes non-uniform, resulting in a difference in the amount of filtered water moving. Thereby, the amount of water that is filtered and absorbed from the outside to the inside of the membrane element 4 varies depending on the location (position) of the surface of the filtration membrane 25. That is, places where the amount of filtration (flux) is high and places where the filtration amount (flux) is low are distributed on the surface of the filtration membrane 25. And the place where the filtration amount is high becomes overloaded, and the surface of the filtration membrane 25 is likely to be clogged.

  In order to clean and regenerate a place where clogging is likely to occur, it is necessary to increase the amount of air diffused from the air diffuser. However, while there is a place where clogging is not present, it is inefficient to increase the amount of air diffused in order to clean and regenerate the place where clogging is likely to occur.

  Actually, it is almost impossible to concentrate the air diffusing only in a place where the degree of clogging is high, and when a place where the degree of clogging is high occurs, the filtration membrane 25 including the place where the degree of clogging is low is also included. It is necessary to clean the entire surface with an increased amount of aeration. Thereby, the washing | cleaning driving | operation of the filtration membrane 25 surface by aeration becomes inefficient.

  Conventionally, in order to efficiently clean the filtration membrane, the entire membrane surface can be cleaned by adjusting the air diffuser so that bubbles are evenly diffused or by improving the rigidity of the membrane support that supports the membrane. The effect is made uniform (for example, refer to Patent Documents 1 to 7).

JP 2007-136389 A JP-A-7-132214 JP-A-7-194947 Japanese Patent Laid-Open No. 7-194946 JP-A-6-178920 JP-A-5-137974 Japanese Patent Laid-Open No. 7-24268

  However, although the membrane elements described in Patent Documents 1 to 7 have a configuration in which a suction nozzle is provided at the top, they have a configuration in which a plurality of branch channels are arranged in the vertical direction as shown in FIG. Absent. For this reason, in the cited documents 1-7, the solution of the problem that the difference of the clogging degree generate | occur | produces by the difference in the filtration amount by the position of the filtration membrane surface is not considered. Therefore, even if the cleaning method described in Patent Documents 1 to 7 is applied to a membrane element having a plurality of branch channels, the filtration membrane surface of the membrane element cannot be efficiently cleaned.

  The present invention was made to solve the above-described problems, and a membrane element that can prevent a difference in the degree of clogging on the filtration membrane surface in a membrane element having a plurality of branch channels, An object is to provide a membrane module and a membrane separation system.

  Another object of the present invention is to improve the efficiency of the cleaning operation of the filtration membrane surface by aeration and to stabilize the entire filtration operation.

In order to achieve the above object, the membrane element according to the present invention is provided with a filtration membrane, a water channel for carrying the filtered water that has permeated the filtration membrane, and the filtration treated water provided between the filtration membrane and the membrane support plate. A spacer having a hole movable in the water channel; a header channel into which filtered water standing in a vertical direction and transported through the water channel flows; and a plurality of vertical channels arranged in the water channel and the header channel. And a water collecting port that is provided in the header flow path and takes out the filtered water transported through the header flow path to the outside, the cross-sectional area of the branch flow path is The position of the N-th branch flow channel from the water collection port among the plurality of branch flow channels is N, the cross-sectional area of the branch flow channel farthest from the water collection port is a reference value, The cross-sectional area of the branch channel is the reference value The value obtained by dividing a sectional area ratio R, the coefficient A (1 to 1.5), when the index B (0.2 to 0.25), satisfy the relationship R = A × ^{N -B} And

According to the above configuration, each branch channel of the membrane element is formed so that the pressure loss from the inlet of the filtered water of each branch channel to the water collection port of the header channel is equal, The flow rate of the filtered treated water flowing through each branch channel can be made uniform, and a difference in the degree of clogging on the filtration membrane surface can be prevented. Therefore, the cleaning operation of the filtration membrane surface by aeration is made efficient, and the entire filtration operation can be stabilized.
The said structure WHEREIN: Each of the said branch flow path is formed so that the filtration process water of an equal flow volume may flow.

According to the said structure, the flow volume of the filtration process water which flows through each several branch flow path can be equalized, and it can prevent that a difference arises in the clogging degree in the filtration membrane surface.
The said structure WHEREIN: Each of the said branch flow path is formed so that the cross-sectional area may become so small that the branch flow path arrange | positioned near the said water collection port.

According to the said structure, the flow volume of the filtration process water which flows through each several branch flow path can be closely approached, and it can prevent that a difference arises in the degree of clogging in the filtration membrane surface.
In the above configuration, the water collection port is provided at an upper end portion of the header flow path, and each of the branch flow paths is formed such that the cross-sectional area thereof is smaller as the branch flow path is disposed above. It is characterized by.

According to the said structure, the flow volume of the filtration process water which flows through each several branch flow path can be closely approached, and it can prevent that a difference arises in the degree of clogging in the filtration membrane surface.
In the above-described configuration, each of the branch flow paths is formed such that the cross-sectional area thereof is equal to the pressure loss from the filtered water inlet of each of the branch flow paths to the water collecting port of the header flow path. And

According to the said structure, the flow volume of the filtration process water which flows through each several branch flow path can be made equal, and it can prevent that a difference arises in the clogging degree in the filtration membrane surface.
The said structure WHEREIN: The said water channel is divided | segmented into the several area | region by the 1 or several partition plate provided in the horizontal direction, It is characterized by the above-mentioned.

According to the above configuration, by providing one or more partition plates in the water channel in the horizontal direction and dividing the water channel into a plurality of regions, the filtered water easily flows in the water channel in the horizontal direction and is arranged in the vertical direction. In addition, the flow rate of the filtered treated water flowing through each of the plurality of branch flow paths can be made more uniform, and a difference in the degree of clogging on the filtration membrane surface can be prevented.
The membrane module according to the present invention is characterized in that a plurality of membrane elements are arranged and housed in a casing.

According to the said structure, a membrane module can be immersed in to-be-processed water, membrane filtration can be performed with a several membrane element, the washing | cleaning operation of the membrane surface by aeration can be made efficient, and stable filtration operation can be performed. .
In addition, a membrane separation system according to the present invention includes the membrane element having the above-described configuration.

  According to the said structure, the washing | cleaning operation | movement of the membrane surface by aeration can be made efficient, and the membrane separation system by which stabilization of the whole filtration operation was implement | achieved can be provided.

  According to the present invention, each branch channel of the membrane element is formed so that the pressure loss from the filtered treated water inlet of each branch channel to the water collecting port of the header channel is equal, The flow rate of the filtered treated water flowing through the branch channel can be made uniform, and a difference in the degree of clogging on the filtration membrane surface can be prevented. Therefore, the cleaning operation of the filtration membrane surface by aeration is made efficient, and the entire filtration operation can be stabilized.

It is a typical top view of the membrane element concerning the embodiment of the present invention. It is a schematic diagram of the whole structure of a MBR (Membrane Bio Reactor: membrane separation type activated sludge process) system. It is a schematic diagram which shows the internal structure of a reaction tank. It is a schematic diagram for demonstrating the structure of a spacer. It is the schematic diagram which looked at a part of membrane support plate from diagonally downward. It is explanatory drawing of the theory of equal flow distribution from a branch flow path. It is a flowchart which shows the calculation procedure of the cross-sectional area of a branch flow path. It is a graph which shows the relationship between the cross-sectional area ratio of each branch flow path calculated according to the calculation procedure shown in FIG. 7, and a branch flow path position, (a) is the total number of branch flow paths, (b) is a branch flow. The total number of paths is 30, and (c) is a graph when the total number of branch flow paths is 50. It is a typical top view of the membrane element in the past.

Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 2 is a diagram schematically showing the overall configuration of an MBR (Membrane Bio Reactor: membrane separation activated sludge treatment) system 1 according to an embodiment of the present invention. The MBR system 1 includes a raw water pipe 17 that draws raw water such as waste water from the outside, a raw water pump 18 that is a driving force for drawing raw water from the raw water pipe 17, an anaerobic tank 19, an oxygen-free tank 20, a reaction tank 21, Is the main component.

  FIG. 3 is a schematic diagram showing the internal configuration of the reaction vessel 21. As shown in the figure, a partition plate 22 that divides the inside of the reaction tank 21 into two regions is disposed at the center of the reaction tank 21. The membrane module 5 is disposed on one side with the partition plate 22 therebetween, and an aerobic tank region 23 is provided on the other side. The membrane module 5 includes a plurality of membrane elements 4 arranged in parallel at regular intervals at a predetermined interval, and a casing 41 for accommodating the plurality of membrane elements 4. Below the membrane module 5, an air diffuser 8 that diffuses bubbles is provided. Bubbles diffused from the diffuser 8 cause an upward flow parallel to the filtration membrane surface between the membrane elements 4 by the air lift action of the bubbles. The adhering matter on the filter membrane surface is released by this upward flow.

  Above the membrane module 5, a pipe 2 communicating with a flow path (not shown) in each membrane element 4 and a treated water suction pump 12 attached to the pipe 2 are provided. The treated water suction pump 12 draws filtered treated water by setting the inside of the membrane element 4 to a negative pressure and takes the filtered treated water out.

  In the aerobic tank region 23 in the reaction tank 21, a fine air diffuser 24 for dissolving oxygen in the water to be treated is disposed. The fine air diffuser 24 emits fine air bubbles to maintain the dissolved oxygen concentration in the aerobic tank region 23 in the reaction tank 21 at a high concentration. In addition, activated sludge is mixed in the water to be treated in the reaction tank 21. The activated sludge performs an aerobic treatment in which ammonia in the water to be treated is nitrated nitrogen while breathing dissolved oxygen in the water to be treated.

Next, the internal configuration of the membrane element 4 will be described with reference to FIG. FIG. 1 is a schematic plan view of one membrane element 4.
In the membrane element 4, a water channel 28 that conveys filtered water that has permeated through a filtration membrane (not shown), a header channel 13 into which the filtered water that is vertically installed and conveyed through the water channel 28 flows, A plurality of branched flow paths 15 arranged in the vertical direction and connecting the water paths 28 and the header flow paths 13 are provided. The water channel 28 is provided with a plurality of partition plates 27 in the horizontal direction, and the water channel 28 is divided into a plurality of regions 16 by the partition plates 27. In the example shown in FIG. 1, the water channel 28 is divided into six regions 16 arranged in the vertical direction. Each of these regions 16 is connected to the header channel 13 via one or a plurality of branch channels 15. The header flow path 13 has the same cross-sectional shape and extends linearly in the vertical direction. A water collection port 14 is provided at the upper end of the header channel 13 and the pipe 2 is connected thereto. The water collection port 14 is an opening for taking out and collecting the filtered water transported through the header channel 13 to the outside.

  A spacer 29 is installed in the water channel 28. By installing the spacer 29 in the water channel 28, the filtration membrane (not shown) is attracted to the membrane support plate (not shown) side that supports the filtration membrane by the negative pressure generated by the suction of the treated water suction pump 12. It can prevent that the width | variety between a membrane support plate becomes narrow and can prevent that filtration efficiency falls.

FIG. 4 is a schematic diagram illustrating an example of the configuration of the spacer 29. The spacer 29 is configured by connecting elongated rectangular flat plates 30 vertically and horizontally. One side surface of the flat plate 30 is attached to the membrane support plate, and the other side surface is in contact with the filtration membrane. The flat plate 30 is provided with a circular hole 31 penetrating in the thickness direction. Through the holes 31, the filtered water can move in the water channel 28. The shape of the hole 31 is not limited to a circle, and may be, for example, an ellipse, a rectangle, or a polygon.
The spacer 29 is not limited to the flat plate 30 provided with the holes 31, and may be a structure in which a large number of columns are arranged on the membrane support plate 26 or a structure that allows water to pass therethrough.

  Next, with reference to FIG. 5, the detailed internal structure of the membrane element 4 and the flow of filtered water in the membrane element 4 will be described. FIG. 5 is a schematic view of a part of the membrane support plate 26 as viewed obliquely from below after the filtration membrane 25 attached to the surface of the membrane support plate 26 constituting the membrane element 4 is removed.

  Various grooves for forming a water channel 28 and the like are provided on the surface of the membrane support plate 26. A filtration membrane 25 is attached to the surface of the membrane support plate 26 so as to cover the groove. In a state where the membrane support plate 26 is covered with the filtration membrane 25, the water channel 28, the header channel 13, and the plurality of branch channels 15 are formed in a space sandwiched between the membrane support plate 26 and the filtration membrane 25. Is done.

  When suction is performed by driving the treated water suction pump 12, the water passage 28, the header flow passage 13, and the branch flow passage 15 become negative pressure, and the water to be treated permeates the filtration membrane 25 as indicated by an arrow D 1. The filtered water that has permeated through the filtration membrane 25 enters the water channel 28 between the membrane support plate 26 and the filtration membrane 25. Thereafter, the filtered water flows through the water channel 28 toward the branch channel 15 and flows into the header channel 13 through the branch channel 15 as indicated by an arrow D2. Thereafter, the filtered water moves upward in the header channel 13 as indicated by an arrow D3, and is discharged to the outside from the water collection port 14 of the header channel 13 as indicated by an arrow D4.

  Each branch channel 15 is formed by changing the physical shape so that the flow rates of the filtered treated water flowing through each branch channel 15 are equal. In the present embodiment, by adjusting the cross-sectional area of each branch channel 15, the flow rate of the filtered water that flows through each branch channel 15 is adjusted.

  The cross-sectional area of each branch flow path 15 that equalizes the flow rate of filtered water flowing through each branch flow path 15 can be analyzed as a problem of equal flow distribution handled in the fluid engineering shown in FIG. Hen, technical data Fluid resistance of pipes and ducts (1979)).

In the following, the total number of branch channels 15 is n, and each branch channel 15 is represented as “branch channel 15 _j (j = 1 to n)”. Q _j is the flow rate near the confluence of the filtered water flowing through the header flow path 13 and the filtered water flowing through the branch flow path 15 _j , A is the cross-sectional area of the header flow path 13, and V _j is near the confluence. , P _j is the pressure near the confluence, q _j is the flow rate of the filtered water flowing through the branch channel 15 _j , v _j is the average flow rate of the filtered water flowing through the branch channel 15 _j , and p _j is inlet pressure of the filtration treatment water branch channel 15 _j, a _j is the cross-sectional area of the branch flow path 15 _j, L is the length of the header channel 13, h is the branch flow path 15 _j length of, l branch The distance between the flow path 15 _j and the branch flow path 15 _{j + 1} is represented.

In the schematic structure shown in FIG. 6, with respect to the sections of the branch flow path 15 _j and the branch flow path 15 _{j + 1} , the average flow velocities V _{j + 1} and V _j in the header flow path 13 and the pressures P _{j + 1} and P _j are as follows. The formula holds.

（但し、ξ：合流抵抗係数、λ：管路摩擦損失係数、Ｄ：ヘッダ流路１３の断面の直径、ｇ：重力加速度）

(However, ξ: Confluence resistance coefficient, λ: Pipe friction loss coefficient, D: Diameter of the cross section of the header flow path 13, g: Gravity acceleration)

The second term on the right side of Equation 2 represents the pipe friction loss in the header flow path 13 and the merge loss due to the merge of the filtered water flowing through the header flow path 13 and the filtered water flowing in from the branch flow path 15 _j. . In addition, the third term on the right side of Equation 2 indicates the height loss due to the distance between the branch flow path 15 _j and the branch flow path 15 _{j + 1} .

Further, the pressure p _j −Δp _j at the outlet portion of the filtered water in the branch flow channel 15 _j (the communication portion with the header flow channel 13) is set to the pressure P at the confluence of the branch flow channel 15 _j in the header flow channel 13. _It is approximated as being equal to _j , and the following formula 4 is used.

Here, each loss coefficient of the confluence loss coefficient and the pipe friction loss coefficient of the branch flow path 15 _j in Expression 4 is given a superscript “′”, and each loss of the header flow path 13 in Expression 2 is set. It is distinguished from the coefficient.

Further, in order to provide a condition for collecting water from each branch channel 15 _j to the header channel 13 at an equal flow rate, the following formula 5 is provided as a condition for pressure equilibrium.

Using these equations, the cross-sectional area a _j of the branch flow path 15 _j that equalizes the filtered water flowing through each branch flow path 15 _j can be calculated.

FIG. 7 is a flowchart showing a procedure for calculating the cross-sectional area a _j using these equations. Hereinafter, the procedure for calculating the cross-sectional area a _j of the branch flow path 15 _j will be described with reference to FIG.
First, as an initial condition, setting the entire flow rate is the total of each flow flowing from the branch paths 15 _j to the header channel 13 (step S101).

Next, the flow rate of each branch channel 15 _j is set by dividing the total flow rate by the total number of branch channels 15 (step S102).
Then, as an initial value, to set the pressure at the inlet of the branch passage 15 ₁ (step S103).

Then, using Equation 1, and the overall flow rate, the flow rate of branch flow paths 15 _1, based on the cross-sectional area of the header flow passage 13, and filtration treatment water flowing through the header channel 13 branch passage 15 calculating the flow rate and flow velocity in the confluence j with filtration water flowing to the header channel 13 from _j (step S104).

Next, using Formula 3, the pressure loss in the section between the junction point j and the junction point (j + 1) in the header channel 13 is calculated (step S105).
Next, the pressure at the junction 1 is calculated based on the pressure at the junction ₁ between the header channel 13 and the branch channel 151, the friction loss, and the junction loss (step S106).

Next, the pressure at the junction (j + 1) is calculated based on the pressure at the junction 1 and Equation 2 (step S107).
Next, the pressure loss in each branch flow path 15 _j is calculated based on the calculation results in Step S105 and Step S107 and Equation 5 (Step S108).
Then, based on the calculation result and the Equation 4 in step S107, it calculates the cross-sectional area _{a j} and flow rate _{v j} of the branch flow path 15 _j (step S109).

  FIG. 8 is a graph showing the result of calculating the cross-sectional area of each branch channel 15 in accordance with the calculation procedure described above. Here, the vertical axis “cross-sectional area ratio R” of the graph uses the cross-sectional area of the branch flow channel 15 farthest from the water collection port 14 of the header flow channel 13 as a reference value, and the cross-sectional area of each branch flow channel 15 The value divided by the reference value. The horizontal axis “branch channel position N” represents each of the plurality of branch channels 15 provided in the membrane element 4. The value “1” indicates the branch flow path 15 closest to the water collection port 14 of the header flow path 13, and the value of N representing the branch flow path 15 at that position as it gradually moves away from the water collection port 14 and approaches the water collection port 14. Is numbered so that it increases by one. That is, the value “N” represents the branch channel 15 that is Nth farthest from the water collection port 14.

  FIG. 8A shows that the total number of branch flow paths 15 is 10 (N = 1,..., 10), and FIG. 8B shows that the total number of branch flow paths 15 is 30 (N = 1,..., 30). FIG. 8C shows the case where the total number of branch flow paths 15 is 50 (N = 1,..., 50).

  As can be seen from the graphs shown in FIG. 8, the cross-sectional area of the branch flow path 15 decreases as the branch flow path 15 gradually approaches the water collection port 14. This is because the cross-sectional area of the branch flow path 15 is smaller as it is closer to the water collection port 14, so that the flow rate of the filtered treated water flowing in the branch flow path 15 is increased and the fluid resistance is increased. It shows that the flow rate of filtered water becomes uniform.

但し、係数Ａは１〜１．５の範囲内にあり、指数Ｂは０．２〜０．２５の範囲にある。 8A, 8B, and 8C, it was confirmed that the relationship between the branch flow path position N and the cross-sectional area ratio R can be expressed by Equation 6.

However, the coefficient A is in the range of 1 to 1.5, and the index B is in the range of 0.2 to 0.25.

  By designing the cross-sectional area of each branch flow path 15 so as to satisfy the relationship of Formula 6, the branch flow path 15 located near the water collection port 14 of the header flow path 13 is given high resistance by a small cross-sectional area, As the distance from the water collecting port 14 increases, the cross-sectional area of the branch flow path 15 can be increased to gradually reduce the resistance. As a result, the pressure loss and resistance from the inlet of each branch channel 15 to the water collection port 14 can be made constant, and an equal flow of filtered water flows from each branch channel 15 into the header channel 13. Thereby, in the water channel 28 in the membrane element 4, the filtered water flows linearly at a constant speed in the horizontal direction toward the branch channel 15, so that the filtration rate on the surface of the filtration membrane 25 can be made uniform. . Therefore, the surface of the filtration membrane 25 can be used evenly and efficiently, clogging and dirt on the surface of the filtration membrane 25 are equalized, and the cleaning operation of the surface of the filtration membrane 25 by the air diffuser 8 is made more efficient. Stabilization of the entire filtration operation can be realized.

  In the above-described embodiment, the pressure loss from the inlet of each branch channel 15 to the water collecting port 14 is adjusted by adjusting the cross-sectional area of the branch channel 15 in order to equalize the flow rate flowing through each branch channel 15. (Resistance) was made equal. However, the physical shape of the branch channel 15 to be adjusted is not limited to the cross-sectional area of the branch channel 15. For example, by adjusting the length of the branch flow path 15, the shape of the cross section or the shape of the flow path, or by adjusting these in combination with the cross-sectional area of the branch flow path 15, the pressure loss is made equal, and the flow rate is adjusted. It may be even.

  In the above-described embodiment, the water collection port 14 is provided at the upper end of the header flow path 13. However, the position where the water collection port 14 is provided is not limited to this, and the water collection port 14 is located at the center of the header flow path 13. You may provide in a part or a lower part. When the water collection port 14 is provided at a position other than the upper end portion of the header flow path 13, Equation 6 does not hold, but the branch flow path 15 arranged near the water collection port 14 on the same principle as the above-described embodiment. By reducing the cross-sectional area and equalizing the pressure loss, the flow rate of the filtered water flowing through each branch channel 15 can be made uniform.

  In the above-described embodiment, the example in which the water channel 28 is divided into the plurality of regions 16 by the partition plate 27 is shown. However, the filtered water can be easily transported in the horizontal direction because the vertical width of the water channel 28 is narrow. In such a case, it is not necessary to divide the region 16 and the number of partition plates 27 to be provided may be one.

In the embodiment described above, the branch flow path 15 and the header flow path 13 are formed by providing a groove in the membrane support plate 26. However, the present invention is not limited to this, and the branch flow path 15 and the header flow path 13 are formed by pipes. However, the branch channel 15 and the header channel 13 may be externally attached to the membrane support plate 26.
The shape of the membrane element 4 is not limited to a rectangular flat plate shape, and may be, for example, a cylindrical shape.

  The present invention can be applied not only to solid-liquid separation in activated sludge membrane separation processing but also to solid-liquid separation other than activated sludge, and can be applied to all fields of membrane separation processing using membrane elements. .

1 ... MBR (Membrane Bio Reactor) system 2 ... Piping 4 ... Membrane element 5 ... Membrane module 12 ... Treatment water suction pump 13 ... ...... Header flow path, 14 ......... Water collecting port, 15 ......... Branch flow path, 16 ......... Region, 17 ......... Raw water piping, 18 ......... Raw water pump, 19 ......... Anaerobic tank, 20 ... ...... Anoxic tank, 21 ......... Reaction tank, 22 ......... Partition plate, 23 ......... Aerobic tank area, 24 ......... Fine diffuser, 25 ......... Filtration membrane, 26 ......... Membrane Support plate, 27... Partition plate, 28... Water channel, 29... Spacer, 30.

Claims (4)

A filtration membrane, a water channel that conveys the filtered water that has passed through the filtration membrane, a spacer that is provided between the filtration membrane and the membrane support plate, and has a hole through which the filtered water can move in the water channel, and a vertical direction Provided in the header flow path, a header flow path into which filtered treated water standing up and flowing through the water flow path flows, a plurality of vertical flow paths that connect the water flow path and the header flow path. In a membrane element comprising a water collection port for taking out the filtered treated water conveyed through the header channel,
The cross-sectional area of the branch flow path is defined as N in the position of the Nth branch flow path from the water collection port among the plurality of branch flow paths, and the breakage of the branch flow channel farthest from the water collection port. A value obtained by dividing the cross-sectional area of each branch channel by the reference value is defined as a cross-sectional area ratio R, a coefficient A (1 to 1.5), and an index B (0.2 to 0.25). ), The membrane element satisfying the relationship of R = A × N− ^B . The membrane element according to claim 1 , wherein the water channel is divided into a plurality of regions by one or a plurality of partition plates provided in a horizontal direction. A membrane module comprising a plurality of membrane elements according to claim 1 arranged in a casing. A membrane separation system comprising the membrane element according to claim 1 or 2 .

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