HK1076065B - Hollow fiber membrane module, hollow fiber membrane module unit, membrane filtering device using the module unit, and method of operating the membrane filtering device - Google Patents

Description

Hollow fiber membrane module, hollow fiber membrane module unit, membrane filtration apparatus using the same, and method for operating the same

Technical Field

The present invention relates to a hollow fiber membrane module, a hollow fiber membrane module unit, a membrane filtration apparatus (membrane filtration system), and an operation method thereof, which are used for purification of tap water, purification of sewer water, industrial processes, and the like.

Technical Field

Water filtration using a membrane module is widely used because it has excellent separation performance, a small apparatus configuration, and can perform large-scale and continuous treatment.

The membrane module includes a microfiltration module, an ultrafiltration module, a reverse osmosis module, and the like, and can be appropriately selected and used according to the substance to be separated. For example, microfiltration modules are widely used for purification of tap water and sewage because they can efficiently remove fine particles and microorganisms of 10 μm or less, particularly 1 μm or less.

Since the microfiltration module is easy to increase the membrane area and easy to handle, it can be used as a hollow fiber membrane module in which hollow fiber membranes are arranged in a cylindrical or mesh form, a pleated membrane module in which flat membranes are folded into a pleated form and arranged in a cylindrical form, or a flat membrane module in which flat membranes are arranged in a mesh form.

Among them, the hollow fiber membrane module is preferably used because it can expand the membrane area per unit volume.

When filtration is performed using the hollow fiber microfiltration membrane module, suspended substances, bacteria and the like in water can be removed through the micropores of the membrane, and thus clear filtered water can be obtained. However, when continuous filtration is performed for a long period of time, clogging of fine pores, reduction in the amount of filtered water, and increase in the filtration pressure are caused, and therefore, the membrane module must be frequently replaced, which is an economical problem.

Therefore, in order to prevent the membrane module from being clogged with substances that clog the membrane surface in water, for example, in the case of the external-pressure type hollow fiber membrane module, the reverse cleaning in which filtered water is reversely introduced from the inside to the outside of the hollow fiber membrane, the gas washing in which air is supplied to the outside of the hollow fiber membrane to vibrate the membrane, or the combination cleaning of both are periodically performed, and the filtration performance is recovered by peeling off the substances that have adhered to the membrane surface that have clogged on the outside of the hollow fiber membrane.

Although the hollow fiber membrane module can increase the membrane area by increasing the number of hollow fiber membranes per unit volume, if the hollow fiber membranes are bundled in a cylindrical shape to increase the membrane area, it is difficult to pass air for gas scrubbing and reverse washing water during washing, and it is difficult to wash. Therefore, the hollow fiber membranes are arranged in a sheet shape and are uniformly arranged at equal intervals, so that the membrane surface can be uniformly cleaned, and the membrane can be applied to filtration of high-turbidity water.

The hollow fiber membrane module can also be used in large-scale treatment facilities, for example, for purification treatment of tap water in excess of 1 ten thousand m³Large scale processing facilities of/d. In this case, although many hollow fiber membrane modules are used to increase the membrane area, for example, when hollow fiber membrane modules are arranged in parallel to form a unit, the arrangement is determined to be able to be approached depending on the size and shape of the fixing member and the water collecting part attached to the end of each hollow fiber membrane module.

For example, the literature proposes: a hollow fiber membrane module in which one or both ends of a hollow fiber membrane are fixed with a fixing member in a housing while keeping the opening, and in which the area of the fixing member surface on the side of the hollow fiber membrane where the fixing member is exposed is defined as A and the area of the fixing member end surface on the side of the hollow fiber membrane where the fixing member is opened is defined as B, 100. gtoreq.A/B.gtoreq.1.2 is satisfied (see Japanese patent laid-open No. 7-178320).

In this module, a sheet-like hollow fiber membrane is fixed by a fixing member having an elongated rectangular shape. In this case, the width of the fixing member on the side where the hollow fiber membranes are exposed is larger than the outer diameter of the header pipe and the connecting portion, and the header pipe and the like do not interfere with each other, so that the side surfaces of the fixing member can be grounded to each other to arrange the modules in parallel, and therefore, all the hollow fiber membranes can be uniformly washed and cleaned with gas without reducing the degree of integration of the hollow fiber membranes.

The more the sheet-like hollow fiber membranes are fixed to one fixing member, the higher the integration degree of the whole hollow fiber membranes, and the processing cost per unit area of the hollow fiber membranes is further reduced. However, the amount of hollow fiber membranes that can be fixed by the elongated rectangular fixing member is limited. On the other hand, if the rectangular width of the fixing member is increased to increase the amount of the hollow fiber membranes that can be fixed, there is a problem that the pressure resistance is extremely decreased.

Further, there is known a hollow fiber membrane module in which a plurality of sheet-like hollow fiber membranes are arranged in parallel and fixed to an end of a cylindrical housing by a fixing member, thereby improving the integration of the hollow fiber membranes and maintaining the interval between the sheet-like hollow fiber membranes to improve the cleaning performance (for example, see japanese patent laid-open No. 2000-51670).

However, in this module, since the sheet-like hollow fiber membranes are arranged in parallel inside the cylindrical housing, the width of the sheet-like hollow fiber membranes fixed to the end portions is shorter than that of the central portion of the cylinder, and there is a problem that the integration of the hollow fiber membranes is lowered.

Further, there is known a hollow fiber membrane module in which a hollow fiber membrane bundle is divided into a plurality of sections, and the sections near the filling sections at both ends are fixed by a support member at a wide spreading width, thereby improving the cleaning performance (see, for example, japanese patent laid-open No. 6-99038).

However, in this module, the packing portions at both ends are fixed to the support body at a wide spread width in the vicinity of the middle portion thereof, and therefore, the degree of integration of the hollow fiber membranes is lowered, and the cleaning performance in the vicinity of the packing portions is sometimes insufficient.

Secondly, when the hollow fiber membrane module is used in a large-scale treatment facility, a large number of hollow fiber membrane modules are placed in the impregnation water tank for use in order to increase the membrane area. In order to effectively utilize the immersion water tank, the hollow fiber membrane modules are arranged in a plurality of rows and layers.

However, in this case, a large amount of piping space and operation space are required, and there is a problem that a space which cannot be effectively used is generated. Therefore, the amount of the cleaning drainage generated by the regular cleaning exceeds the required amount, and the recovery rate of the water is lowered.

In order to solve the above-mentioned problems, the present invention relates to a module using a sheet-like hollow fiber membrane having excellent cleaning properties, and an object of the present invention is to provide a hollow fiber membrane module in which the pressure resistance of a hollow fiber membrane fixing portion does not decrease even when the membrane area is increased, and a hollow fiber membrane module unit in which the integration degree of the hollow fiber membrane is improved. Another object of the present invention is to provide a membrane filtration apparatus using the hollow fiber membrane module unit and a method for operating the same.

Disclosure of Invention

That is, the first aspect of the present invention is a hollow fiber membrane module comprising a plurality of sheet-like hollow fiber membranes (1) and a fixing member (2) for fixing at least one end of the plurality of sheet-like hollow fiber membranes (1) substantially in parallel in a state of being held open, wherein the end surface of the fixing member (2) on the side where the hollow fiber membranes are exposed is substantially rectangular, and the end surface of the fixing member (2) on the side where the hollow fiber membranes are open is substantially circular.

In this way, in the hollow fiber membrane module of the first aspect of the present invention, the end surface shape of the fixing member (2) on the side where the hollow fiber membranes are exposed is substantially rectangular, and the end surface shape of the fixing member (2) on the side where the hollow fiber membranes are open is substantially circular, so that the pressure resistance of the fixing portion of the hollow fiber membranes does not decrease even when the membrane area of the module using the sheet-like hollow fiber membranes having excellent cleaning performance is increased.

The fixing member (2) is preferably provided with a rectangular parallelepiped part (3) having a shape similar to a rectangular parallelepiped on the side where the hollow fiber membrane is exposed, and a cylindrical part (4) having a shape similar to a cylinder on the side where the hollow fiber membrane is opened, because the pressure resistance, the cleaning property, and the integration of the hollow fiber membrane are excellent.

Further, it is preferable that the diameter of the cylindrical part (4) is D (mm) and the length of the cylinder is L (mm) so as to satisfy the requirements

L/D is not less than 0.2 and not more than 1.0.

Furthermore, it is preferable that the length of the long side of the exposed end face of the hollow fiber membrane of the rectangular parallelepiped (3) is W (mm), and the diameter of the cylindrical section (4) is D (mm), so as to satisfy the requirements

W/D is not less than 1.0 and not more than 2.0.

The second main point of the present invention is a hollow fiber membrane module unit comprising a plurality of hollow fiber membrane modules, wherein a plate-like member (5) having a hole penetrating through the cylindrical section (4) is provided on a side surface perpendicular to the membrane surface of the sheet-like hollow fiber membrane (1), and the hollow fiber membrane modules are fixed in position by the plate-like member (5).

In this way, in the hollow fiber membrane module unit according to the second aspect of the present invention, since the plate-like member (5) having the hole that can penetrate the cylindrical portion (4) is provided and the position of the hollow fiber membrane module is fixed by the plate-like member (5), the fixing can be performed simply and reliably and the integration of the hollow fiber membrane can be improved.

Further, it is preferable that the plate-like member (5) is fixed by being inserted and held between the cylindrical portion (4) and a water collecting cover (6) fitted thereto, because the fixing can be performed simply and surely.

The cylindrical portion (4) and the water collection cover (6) are preferably fixed by screwing and engaging, and can be removed more easily.

Furthermore, when a plurality of the hollow fiber membrane module units are arranged in a vertically overlapped manner,

the membrane surface of the sheet-shaped hollow fiber membrane (1) is arranged along the vertical direction, and the water collecting covers (6) adjacent to each other in the vertical direction are connected with each other by a water collecting component (7) extending in the vertical direction,

the side plate (21) is preferably arranged on the side surface parallel to the membrane surface of the sheet-like hollow fiber membrane (1), because the integration of the hollow fiber membrane can be improved in a small installation area.

In this case, if the interval in the vertical direction between the sheet-like hollow fiber membranes (1) of the vertically adjacent hollow fiber membrane modules is 70mm or less, the cleaning efficiency of the hollow fiber membranes is improved, and therefore, it is preferable.

The third main point of the invention is that: a membrane filtration device in which a membrane module unit is disposed in a water tank,

the membrane module unit is composed of a plurality of hollow fiber membrane modules,

the hollow fiber membrane module comprises a plurality of sheet-like hollow fiber membranes (1) and a fixing member (2) for fixing at least one end of the plurality of sheet-like membranes (1) substantially in parallel in a state of maintaining an opening; the hollow fiber membrane module is composed of a hollow fiber membrane module in which the end surface of the fixing member (2) on the side where the hollow fiber membranes are exposed is approximately rectangular and the end surface of the fixing member (2) on the side where the hollow fiber membranes are open is approximately circular,

the membrane area of the membrane module unit is set to S (m)²) The projected area of the membrane module unit is set to A (m)²) The volume of the membrane module unit is set to V' (m)³) The volume of the water tank is set to V (m)³) Then, the following 3 relational expressions are satisfied.

… formula (1) with S/A not less than 1000 and not more than 2000

… formula (2) with S/V' not less than 500 ≤ and 800 ·

V'/V is not less than 0.70 and not more than 0.99

The fourth feature of the present invention is: a method for operating a membrane filtration device in which a membrane module unit is disposed in a water tank, the method comprising:

the membrane module unit is composed of a plurality of hollow fiber membrane modules,

the hollow fiber membrane module is composed of: a hollow fiber membrane module in which at least one end of a plurality of sheet-like membranes (1) is fixed substantially in parallel by a fixing member (2) in an open state, the end face of the fixing member (2) on the side where the hollow fiber membranes are exposed is substantially rectangular, and the end face of the fixing member (2) on the side where the hollow fiber membranes are open is substantially circular,

the membrane area of the membrane module unit is set to S (m)²) The filtration flow stream is set to J (m/D), the filtration time is set to T (h), the number of water discharge cycles is set to N (times), and the water discharge amount is set to D (m)³) When the reverse cleaning flow stream is set to J '(m/D) and the reverse cleaning time is set to T' (h), the membrane filtration apparatus is operated by setting the membrane area S, the filtration flow stream J, the filtration time T, the number of water discharge cycles N, the water discharge amount D, the reverse cleaning flow stream J ', and the reverse cleaning time T' which satisfy the following relational expressions.

N.gtoreq.22.8D/{ S (0.05JT-J 'T') } … … formula (4)

The membrane filtration device of the present invention and the membrane filtration device to which the operation method is applied are small in size, but have a large membrane area and excellent cleaning performance, and therefore can perform filtration stably for a long period of time.

Drawings

Fig. 1 is a perspective view showing an example of a hollow fiber membrane module of the present invention.

Fig. 2 is a sectional view showing an example of a fixing member in the hollow fiber membrane module of the present invention.

Fig. 3 is a perspective view showing an example of a fixing member in the hollow fiber membrane module of the present invention.

FIG. 4 is a sectional view showing another example of a fixing member in the hollow fiber membrane module of the present invention.

Fig. 5 is a perspective view showing another example of the hollow fiber membrane module of the present invention.

Fig. 6 is a perspective view showing an example of a hollow fiber membrane module unit of the present invention.

Fig. 7 is a sectional view showing an example of a position fixing portion of a hollow fiber membrane module unit of the present invention.

Fig. 8 is a front view showing an example of the hollow fiber membrane module unit of the present invention stacked in the vertical direction.

FIG. 9 is a flow chart showing an example of the membrane filtration apparatus of the present invention.

FIG. 10 is a schematic view showing an example of the bottom surface of an immersion water tank in the membrane filtration apparatus of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a perspective view showing an example of a hollow fiber membrane module of the present invention.

The hollow fiber membrane module (A) is substantially composed of a sheet-like hollow fiber membrane (1), a fixing member (2), and a water collection cover (6). A plurality of sheet-like hollow fiber membranes (1) are arranged in parallel at equal intervals, both ends of the hollow fiber membranes are fixed by fixing members (2) in an open state, and water collecting covers (6) are attached to the fixing members (2).

Fig. 2 is a sectional view showing an example of the fixing member in the hollow fiber membrane module of the present invention, and is a sectional view in a direction perpendicular to the membrane surface of the sheet-like hollow fiber membrane.

A plurality of sheet-like hollow fiber membranes (1) are arranged in parallel at equal intervals, and both ends thereof are fixed by fixing members (2).

The end face of the fixing member (2) on the side where the sheet-like hollow fiber membranes (1) are exposed is approximately rectangular, and the shape on the side of the open end of the hollow fiber membranes is approximately circular. When the end surface of the fixing member (2) on the side of the opening of the sheet-like hollow fiber membrane (1) is cylindrical, the bending property is smaller and the stress is dispersed, compared with the case where the end surface is rectangular, so that the pressure resistance is remarkably improved. With such a shape, even when a large number of sheet-like hollow fiber membranes are arranged, the hollow fiber membranes are excellent in all of the integration, cleaning performance, and pressure resistance.

In this case, the shape of the fixing member (2) may be, for example, a shape that continuously changes from the side where the sheet-like hollow fiber membrane (1) is exposed to the side where the opening is opened. However, as shown in fig. 1 and 2, if the fixing member (2) has a rectangular parallelepiped part (3) having a substantially rectangular parallelepiped shape on the side where the hollow fiber membranes are exposed and a cylindrical part (4) having a substantially cylindrical shape on the side where the hollow fiber membranes are opened, the following 3 excellent effects can be obtained at the same time.

1. The plurality of sheet-like hollow fiber membranes (1) can be fixed to the rectangular parallelepiped section (3) of one fixing member (2) with a space maintained therebetween, and therefore, the cleaning performance is excellent.

2. When a plurality of hollow fiber membrane modules (A) are arranged, the side surfaces of the rectangular parallelepiped parts (3) are overlapped with each other, so that a state in which the integration degree of the hollow fiber membranes is extremely high can be achieved without wasting space.

3. Since the fixing member (2) has the cylindrical portion (4) on the side where the hollow fiber membranes are open, the pressure resistance can be greatly improved.

The cross-sectional shape of the cylindrical portion (4) of the fixing member (2) perpendicular to the central axis of the cylinder is not necessarily a perfect circle, and may be an ellipse or a kidney bean, or may be a polygon close to a circle such as a 12-degree angle or a 16-degree angle, but a circle is preferable.

Further, it is preferable that when the diameter of the cylindrical portion (4) is set to D (mm) and the length of the cylinder in the central axis direction is set to L (mm),

satisfy the relation of L/D being more than or equal to 0.2 and less than or equal to 1.0.

The pressure resistance of the fixed part of the hollow fiber membrane is greatly affected by the L/D of the cylindrical part (4). If L/D is less than 0.2, the pressure resistance is insufficient, and therefore the lower limit of L/D is 0.2 or more, preferably 0.25 or more. On the other hand, if the L/D exceeds 1.0, the loss of the effective part of the hollow fiber membrane increases, and therefore the upper limit of the L/D is 1.0 or less, more preferably 0.8 or less.

The diameter D of the cylindrical portion (4) described here means the diameter of the longest portion when the cross section of the cylindrical portion (4) is not a perfect circle.

The dimensions of L and D of the cylindrical section (4) can be set appropriately according to the size of the hollow fiber membrane module, but if D is too small, the arrangement of the sheet-like hollow fiber membranes (1) becomes difficult, and therefore the lower limit of D is preferably 30mm or more, more preferably 50mm or more. On the other hand, if D is too large, the workability of the module may be deteriorated and the pressure resistance may be insufficient, so that the upper limit of D is preferably 400mm or less, more preferably 300mm or less.

Further, since the pressure resistance is insufficient when L is too small, the lower limit thereof is preferably 10mm or more, more preferably 50mm or more. On the other hand, when L is too large, the loss of the effective part of the hollow fiber membrane becomes large, and the water passage resistance also becomes large, so that the upper limit of L is preferably 300mm or less, more preferably 200mm or less.

Fig. 3 is a perspective view showing an example of a fixing member in the hollow fiber membrane module of the present invention. The hollow fiber membrane module (A) of the present invention satisfies the relational expression of 1.0. ltoreq. W/D.ltoreq.2.0 when the length of the long side of the end face of the hollow fiber membrane exposed is W (mm) and the diameter of the cylindrical section (4) is D (mm).

By making W larger than D, the membrane area of the hollow fiber membrane module can be increased without lowering the pressure resistance of the fixing portion of the hollow fiber membrane. However, if the W/D is too large, since it becomes difficult to install and twist the sheet-like hollow fiber membranes, it is difficult to arrange the sheet-like hollow fiber membranes in order, and there arises a problem that the effective lengths of the respective hollow fiber membranes are uneven. Further, since the length of the hollow fiber membranes compressed in the rectangular parallelepiped part (3) is increased, there is a problem that the water flow resistance of the membrane positioned at the outer layer among the laminated sheet-like hollow fiber membranes is increased. Therefore, the upper limit of W/D is preferably not more than 2.0, more preferably not more than 1.8.

On the other hand, if the W/D is too small, the processing becomes easy, but there is a problem that the pressure resistance is lowered, and therefore the lower limit of the W/D is preferably 1.0 or more, more preferably 1.2 or more.

W can be appropriately set according to the membrane area of the hollow fiber membrane module, but if W is too small, it is difficult to increase the membrane area of the module, and therefore the lower limit of W is preferably 40mm or more, more preferably 80mm or more.

On the other hand, since the workability of the module is deteriorated when W is too large, the upper limit of W is preferably 500mm or less, more preferably 400mm or less.

In fig. 3, W is shown when the rectangular parallelepiped section (3) is long in the vertical direction, but W is taken in the horizontal direction when the rectangular parallelepiped section is long in the horizontal direction (the direction in which the sheet-like hollow fiber membranes are stacked).

The arrangement shape of the hollow fiber membranes varies depending on the effective length, outer diameter, width of the sheet-like hollow fiber membranes, and the like of the hollow fiber membranes, and therefore the length of the rectangular parallelepiped section (3) in the axial direction of the hollow fiber membranes can be set as appropriate. However, if the length of the rectangular parallelepiped section (3) in the axial direction of the hollow fiber membranes is too short, it is difficult to bundle a plurality of sheet-like hollow fiber membranes arranged at equal intervals into a cylinder from a rectangular parallelepiped, and therefore the lower limit of the length of the rectangular parallelepiped section (3) in the axial direction of the hollow fiber membranes is preferably 5mm or more, more preferably 10mm or more.

On the other hand, if the length of the hollow fiber membranes in the axial direction of the hollow fiber membranes in the rectangular parallelepiped part (3) is too long, the loss of the effective part of the hollow fiber membranes increases, and the part not involved in filtration increases to increase the water passage resistance, so the upper limit of the length of the hollow fiber membranes in the axial direction of the hollow fiber membranes in the rectangular parallelepiped part (3) is preferably 100mm or less, more preferably 70mm or less, and still more preferably 50mm or less.

In order to collect the filtrate taken out of the hollow fiber membrane, a water collecting cover (6) is attached to the cylindrical portion (4). The better installation of the water collecting cover (6) is as follows: the thread (8) on the outer periphery of the cylindrical part is engaged with the thread (8) on the water collecting cover (6), and then the sealing is performed by a sealing member (9) such as an O-shaped sealing member, so that the removal is simple and the sealing can be performed accurately.

Fig. 4 is a cross-sectional view showing another example of the fixing section in the hollow fiber membrane module of the present invention, which is a cross-sectional view in a direction perpendicular to the membrane surface of the sheet-like hollow fiber membrane.

In this example, a sheet-like hollow fiber membrane (1) is fixed by a fixing member (2) in a housing (10).

In the case where the housing cover (10) is provided as in the example of fig. 4, the above-mentioned items (D), (L), and (W) are based on the size of the fixing member (2) as in the case where the housing cover (10) is not provided.

Even if the shell cover (10) is provided, the water collecting cover (6) can be: a thread (8) on the outer periphery of the cylindrical part (4) is engaged with a thread (8) on the water collection cover (6), and then sealed by a sealing member (9) such as an O-shaped sealing member. Furthermore, the water collection cover (6) may be integrated with the housing cover (10). Alternatively, the water collecting cover (6) may be attached to the fixing member (2).

The hollow fiber membrane module of the present invention preferably has a structure in which both ends of a sheet-like hollow fiber membrane (1) are fixed by different fixing members (2). In the use of the hollow fiber membrane module, when raw water is supplied to the outside of the hollow fiber membranes and treated water is taken out from the inside of the hollow fiber membranes, if the effective length of the hollow fibers is increased, there is a problem that the water passage resistance inside the hollow fiber membranes is increased. However, by adopting the structure of collecting water from both ends of the hollow fiber membrane as shown in fig. 1, it is possible to reduce the water passage resistance and increase the effective length of the hollow fiber. In addition, the both ends are fixed by the fixing members (2), so that the hollow fiber membrane module is easy to support when being installed as a unit.

Fig. 5 is a perspective view showing another example of the hollow fiber membrane module of the present invention. The hollow fiber membrane module (A) in this example is roughly composed of a sheet-like hollow fiber membrane (1), a fixing member (2), a water collection cover (6), and a support member (11). A plurality of sheet-like hollow fiber membranes (1) are arranged in parallel at equal intervals by a fixing member (2), one end of each of the sheet-like hollow fiber membranes is fixed by the fixing member (2), and the other end of each of the sheet-like hollow fiber membranes is supported by a support member (11). In addition, a water collecting cover (6) is arranged on the fixed part (2).

The structure of the support member (11) is not particularly limited as long as a plurality of sheet-like hollow fiber membranes (1) can be supported in parallel at equal intervals, and if resin is applied to the entire hollow fiber membranes for fixation, the hollow fiber membranes may be fixed by a member such as a rod or a wire. The hollow fiber membrane may be folded in a U-shape from the middle, and the folded portion may be fixed by a support member (11).

Such a manner of collecting water only from one end can also be applied to the case where the effective length of the hollow fiber membrane is short and the diameter of the hollow fiber membrane is large.

When the scale of the treatment is large, it is preferable to form a hollow fiber membrane module unit by using a plurality of hollow fiber membrane modules because the workability is excellent. In this case, it is preferable to improve the integration of the membranes of the hollow fiber membrane module unit as much as possible without impairing the cleaning performance.

Fig. 6 is a perspective view showing an example of a hollow fiber membrane module unit of the present invention.

The hollow fiber membrane module unit (B) is substantially composed of a hollow fiber membrane module (A), a plate-like member (5), a water collection cover (6), and a side plate (21).

The plate-like member (5) is provided with 4 holes. The hollow fiber membrane module (A) is fixed by attaching the membrane surface of the hollow fiber membrane module (A) in the vertical direction and the fiber axis of the hollow fiber membrane in the horizontal direction, inserting the cylindrical part (4) into the hole, and attaching the water collecting cover (6) to the protruding cylindrical part, whereby the plate-like member (5) can fix the hollow fiber membrane module (A).

The water collection cover (6) is attached simply and accurately by engaging the cylindrical portion (4) with the screw (8) on the water collection cover (6) as described above. At this time, as shown in fig. 7, by making the water collection cover (6) larger than the holes in the plate-like member (5), the position of the hollow fiber membrane module (a) can be fixed by the water collection cover (6) and the plate-like member (5).

A total of 4 hollow fiber membrane modules (A) can be fixed to the plate-like member (5), and a hollow fiber membrane module unit (B) can be constructed by attaching side plates (21) to both sides along the membrane surface of the sheet-like hollow fiber membrane (1).

In the example of fig. 6, the hollow fiber membrane module unit (B) composed of 4 hollow fiber membrane modules (a) is exemplified, but the number may be adjusted as necessary.

The side plate (21) has a function of maintaining the shape of the hollow fiber membrane module unit (B) and a function of concentrating the air washed with gas on the hollow fiber membrane without leaking to the outside.

For the side plate (21), a plate having rigidity and strength such as stainless steel may be used, but a plate made of resin or light alloy may be attached to a frame made of stainless steel, and it is preferable because the weight is light while the strength is maintained. Further, when the transparent resin plate is used, the hollow fiber membrane module can be visually observed from the outside, and whether the cleaning property is good or not can be confirmed, which is more preferable.

The rectangular parallelepiped parts (3) of the fixing members (2) of the respective hollow fiber membrane modules (A) are connected to each other and arranged in a unit without a gap, whereby the air for gas scrubbing can be uniformly supplied to the whole unit.

The hollow fiber membrane module unit (B) thus assembled is further arranged in a plurality of stages in the vertical direction or the lateral direction to be integrated, and the area of the hollow fiber membrane can be easily adjusted according to the scale of the process.

In this case, although the depth of the immersion water tank in which the hollow fiber membrane module unit (B) is disposed is limited, it is preferable from the viewpoint of improving the integration of the hollow fiber membranes per installation area when a plurality of hollow fiber membrane module units (B) are integrally stacked in the vertical direction as shown in fig. 8. The number of layers in which the hollow fiber membrane module unit (B) is stacked may be, for example, 2 to 10. When the sheet is immersed in a place such as a flocculation and precipitation site of a water purification plant, the number of laminated layers is preferably 4 to 6.

The hollow fiber membrane module units stacked in the vertical direction may be used in parallel in the immersion water tank as needed.

In the case where a plurality of hollow fiber membrane module units (B) are stacked in the vertical direction, if the vertical direction interval between the sheet-shaped hollow fiber membranes (1) of the adjacent hollow fiber membrane modules is too wide, when the gas-washed air is flushed against the membrane surface of the hollow fiber membrane module located below and then rises to the membrane surface of the hollow fiber membrane module located above, the gas-washed air tends to be concentrated and form a rough gas flow. As a result, the dispersibility is reduced, and the uniformity of cleaning of the membrane surface is more difficult to maintain in the hollow fiber membrane module located above.

Therefore, the interval in the vertical direction between the sheet-like hollow fiber membranes (1) is preferably 70mm or less, more preferably 60mm or less. In this way, since the dispersibility can be maintained when the gas-washed air rises to the membrane surface of the hollow fiber membrane module located above the air-washed air after being flushed to the membrane surface of the hollow fiber membrane module located below, the cleaning performance is not impaired even if a plurality of hollow fiber membrane modules are stacked in the vertical direction.

The vertical interval between the sheet-like hollow fiber membranes (1) is not an interval between variable portions caused by vibration due to air washing, and is an interval between the lowermost end portion of the fixed portion of the sheet-like hollow fiber membrane (1) of the upper hollow fiber membrane module and the uppermost end portion of the fixed portion of the sheet-like hollow fiber membrane (1) of the lower hollow fiber membrane module located closest thereto.

If the interval in the vertical direction between the sheet-like hollow fiber membranes (1) is too small, the hollow fiber membranes are entangled with each other and the cleaning property may be impaired, and therefore, the lower limit thereof is preferably 20mm or more, more preferably 30mm or more.

When a plurality of hollow fiber membrane module units (B) are stacked in the vertical direction, the filtrate flowing out of each water collecting cap (6) must be collected and taken out. In this case, the water collecting covers (6) are connected by the water collecting members (7) extending in the vertical direction, so that the structure is compact and the connection is convenient.

As the water collecting member (7), for example, a union joint, a flange joint, a tee joint, an elastic hose, a connector, etc. may be used as long as the water collecting cover (6) and the water collecting member (7) or a plurality of water collecting members (7) can be connected.

The water collecting member (7) may be made of any material having mechanical strength and durability, for example, polycarbonate resin, polysulfone resin, acrylic resin, ABS resin, modified PPE (polyphenylene ether) resin, polyvinyl chloride resin, polyolefin (polypropylene, polyethylene, etc.) resin, stainless steel, bronze, brass, cast steel, etc. may be used.

The fixing member (2) used in the hollow fiber membrane module of the present invention can be suitably selected from those having sufficient adhesive strength to the hollow fiber membrane and the housing (10) and satisfying the performance required for each application, and examples thereof include thermosetting resins such as urethane resins, epoxy resins, silicone resins, and unsaturated polyester resins, and thermoplastic resins such as urethane resins, ethylene vinyl acetate copolymers, and polyolefin resins. The fixing method of the hollow fiber membrane can adopt: a known method such as a hot melt injection method when a thermoplastic resin is used, a method using centrifugal force when a thermosetting resin is used, and a method using self-weight injection.

When the housing (10) is used, the material thereof can be appropriately selected to satisfy the performance required for each application. For example, when the adhesion of polyolefin, polycarbonate, modified poly (di) phenylene ether, ABS, polyvinyl chloride or the like to the fixing member (2) is low, it may be used after the primer treatment.

The hollow fiber membrane used in the hollow fiber membrane module of the present invention is not particularly limited in material, pore diameter, porosity, membrane thickness, outer diameter, and the like. For example, usable hollow fiber membranes are made of: polyalkene, polysulfone, polyvinyl alcohol, cellulose, polyacrylonitrile, polyamide, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and the like.

When the hollow fiber membrane is processed into a sheet form, a material having high strength and high ductility such as polyethylene or polypropylene is preferably used in the case of knitting, for example, from the viewpoint of ease of processing.

When a hydrophobic hollow fiber membrane is used for filtering water, it can be used after hydrophilic treatment.

Further, the hollow fiber membrane has a pore diameter of 0.001 to 3 μm, a porosity of 20 to 95%, a membrane thickness of 5 to 500 μm, and an outer diameter of 20 to 3000. mu.m.

In the hollow fiber membrane module (A) of the present invention, a plurality of sheet-like hollow fiber membranes (1) are arranged in parallel at equal intervals. The method for arranging the hollow fiber membrane in a sheet shape is not particularly limited, and a hollow fiber membrane sheet knitted in a sheet shape is preferably used. The interval between the sheet-like hollow fiber membranes can be appropriately set according to the properties of raw water, and is, for example, 2 to 100 mm. The number of the sheet-like hollow fiber membranes can be appropriately set according to the membrane area of the module.

FIG. 9 is a flow chart showing an example of the membrane filtration apparatus of the present invention. The membrane filtration device is roughly composed of a water tank (12), a hollow fiber membrane module unit (13), an air diffuser (14), a suction pump (15), a liquid medicine pump (16), a liquid medicine tank (17), a reverse cleaning pump (18), a reverse cleaning tank (19) and an air blower (20).

In the membrane filtration device of the present invention, the membrane area of the membrane module unit is set to S (m)²) The projected area of the membrane module unit, that is, the area occupied by the membrane module unit as viewed from above, is set to a (m)²) The volume of the membrane module unit is set to V' (m)³) The volume of the water tank is set to V (m)³) Then, the following 3 relational expressions are satisfied.

… formula (1) with S/A not less than 1000 and not more than 2000

… formula (2) with S/V' not less than 500 ≤ and 800 ·

V'/V is not less than 0.70 and not more than 0.99

The volume V' refers to a volume based on the outer peripheral profile of the membrane module unit, and includes a space in which no component is present inside the membrane module unit.

The method for operating the membrane filtration apparatus of the present invention will be described below. The hollow fiber membrane module unit (13) is mounted inside the water tank (12). The lower part of the hollow fiber membrane module unit (13) is provided with an air dispersing device (14). The suction pump (15) is activated to obtain filtered water, and a part of the filtered water is stored in the reverse washing tank (19). After a certain time of filtration, air is sent out by using a blower (20) connected to the air dispersing device (14) to carry out gas washing and cleaning, and at the same time, reverse cleaning is carried out by using the filtered water in a reverse cleaning tank (19) through a reverse cleaning pump (18). At this time, the chemical in the chemical tank (17) is injected into the reverse cleaning water by the chemical pump (16). The reverse washing water is then discharged from the immersion water tank through an overflow port (not shown) provided in the upper part of the immersion water tank. The gas purge and the reverse purge may be performed separately.

After the washing is finished, the liquid in the water tank is drained from the lower part of the water tank (12). In addition, the water is not necessarily drained every time of washing, and may be drained once every several times of washing. The number of washing operations performed before 1 drainage is hereinafter referred to as the number of drainage cycles N (times). The washing referred to herein means washing performed after the filtration is stopped and before the next filtration is started.

That is, the number of times of purging is 1 in the case where the gas purge and the reverse purge are performed simultaneously or in the case where the gas purge and the reverse purge are performed separately. In addition, for example, in the case of repeatedly performing the cleaning in a plurality of steps such as gas scrubbing cleaning, reverse cleaning, gas scrubbing cleaning, and reverse cleaning, if these cleaning are performed after the filtration is stopped and before the next filtration is started, the number of times of cleaning is also 1.

The cleaning may be performed only by gas scrubbing cleaning or reverse cleaning. In a series of operating cycles, only one of the gas scrubbing purge or the reverse purge, or a combination of both, may be performed. For example, the operation may be performed in the order of i filtration, ii gas washing and cleaning, iii filtration, iv reverse cleaning, and v drainage. In this example, the number of drainage cycles is 2.

As another example, the operation may be performed in the order of i filtration, ii gas washing and cleaning, iii filtration, iv gas washing and cleaning, v reverse cleaning, vi filtration, vii gas washing and cleaning in reverse direction, and viii water discharge. In this example, the number of drainage cycles was 3.

FIG. 10 is a schematic view showing an example of the bottom surface of an immersion water tank in the membrane filtration apparatus of the present invention. The solid line in the figure shows the outline of the bottom surface inside the water tank, and the broken line in the figure shows the outline of the outer periphery of the hollow fiber membrane module unit.

Here, the area efficiency and the volume efficiency of the membrane module unit are explained. The area efficiency is obtained by dividing the membrane area S of the membrane module unit by the projected area a of the membrane module unit (the area obtained by a '(m) × b' (m) in the example of fig. 10). On the other hand, the volumetric efficiency is obtained by dividing the membrane area S of the cell by the volume V' (m) of the cell³) (in the example of FIG. 10, a '(m). times.b' (m). times.cell height (m: not shown in the figure) is obtained).

The volume V (m) of the immersion water tank³) In the example of fig. 10, a (m) × b (m) × effective water depth (m: not shown) of the volume obtained.

In the membrane filtration device of the present invention, the area efficiency S/V of the hollow fiber membrane module unit is preferably 1000-²/m²) More preferably 1100- & gt 1800 (m)²/m²). The area efficiency can be adjusted by changing the number of laminated layers of the unit, but if the number of laminated layers is small, the area efficiency is less than 1000 (m)²/m²) In other words, the unit cannot be made compact and small. On the other hand, the number of laminated layers is large, and the area efficiency is higher than 2000 (m)²/m²) If so, e.g. only at the lowermost part of the unitIn the case of the air diffusing device, the air bubbles may not reach the entire membrane at the upper part of the unit, and thus cleaning may be defective.

In the membrane filtration device of the present invention, the volumetric efficiency S/V' of the membrane module unit is preferably 500-800 (m)²/m³) More preferably 600-700 (m)²/m³). The volumetric efficiency S/V' is less than 500 (m)²/m³) In addition, the size of the apparatus cannot be reduced, and the apparatus becomes large. On the other hand, the volumetric efficiency S/V' is higher than 800 (m)²/m³) The cleaning property is lowered.

In the membrane filtration device of the present invention, the volume of the immersion water tank is set to V (m)³) The volume of the membrane module unit is set to V' (m)³) In the case, it is preferably 0.70. ltoreq. V'/V.ltoreq.0.99. When V'/V is less than 0.70, dead angle is large, and water recovery rate is reduced; on the other hand, when V'/V is more than 0.99, when the unit is placed in the immersion water tank, the space between the unit and the inner wall of the immersion water tank becomes small, and there is a possibility that the unit is broken when mounted.

In the method for operating a filtration apparatus of the present invention, the membrane area of the membrane module unit is set to S (m)²) Filtration of the flow stream, i.e. the filtration capacity (m)³Divided by the membrane area S (m)/D)²) The obtained value was J (m/D), the filtration time was T (h), the number of water discharge cycles was N (times), and the amount of water discharged once was D (m)³) Reverse cleaning stream, i.e. reverse cleaning volume (m)³Divided by the membrane area S (m)/D)²) When the obtained value is J '(m/d) and the back washing time is T' (h), the following relational expression is satisfied.

N≥22.8D/{S(0.05JT-J’T’)}

The water recovery rate Q (%) was determined by the following equation.

Q { (amount of filtered water-reverse amount of washing water)/(amount of raw water supply) } × 100

＝{(S×J×T/24×N-S×J’×T’/24×N)/(S×J×T/24×N+D)}×100

The water recovery rate Q (%) is determined by each condition, but is greatly affected by the water discharge cycle N (times). Further, when the water recovery rate Q (%). is set to be not less than 95 and N (times) is to be obtained, the above formula is:

N≥22.8D/{S(0.05JT-J’T’)}。

in a large-scale treatment facility, the absolute amount of discharged water increases, and the water recovery rate becomes important. Further, when N is obtained by the above formula and the drain cycle is determined, a high recovery rate of not less than 95% of the water recovery rate can be achieved.

In this case, the filtration flow stream J (m/d) can be appropriately set in accordance with the quality of the raw water, and is preferably 0.25 to 2.5 m/d. When the filtration flow rate is less than 0.25m/d, the operation time must be very long, and when the filtration flow rate is more than 2.5m/d, the suction pressure may increase too early.

The filtration time T (h) may be appropriately set depending on the quality of raw water, but a preferable range is 15 to 240 minutes, and a more preferable range is 30 to 120 minutes. When the filtration time is less than 15 minutes, the water recovery rate and the operation rate may be lowered, and when the filtration time exceeds 180 minutes, the cleaning recovery performance of the suction pressure may be lowered.

The amount of air for gas scrubbing (the amount of air per unit projected area of the membrane module unit) may also be appropriately set, but the preferable range is 100-400 (Nm)³/(m²H)), and a more preferable range is 150-250 (Nm)³/(m²H)). Air quantity is less than 100 (Nm)³/(m²H)), the cleaning effect tends to be reduced, while the air amount exceeds 400 (Nm)³/(m²H)), the necessary amount of air tends to be too large.

The time for the gas washing and cleaning may be appropriately set, but a preferable range is 1 to 10 minutes, and a more preferable range is 2 to 5 minutes. If the gas washing cleaning time is less than 1 minute, the cleaning effect is lowered, while if the gas washing cleaning time exceeds 10 minutes, the operation rate is lowered.

The reverse purge stream J' (m/d) may be appropriately set, but a preferable range is 0.3 to 4 times the filtration stream, and a more preferable range is 1 to 3 times the filtration stream. When the reverse purge stream is less than 0.3 times the filtered stream, the cleaning effect is reduced, and when the reverse purge stream is more than 4 times the filtered stream, the water recovery rate is reduced.

The reverse washing time T' (h) may be set as appropriate, but is preferably in the range of 5 to 180 seconds, and more preferably in the range of 10 to 90 seconds. When the reverse washing time is less than 5 seconds, the washing effect is lowered, and on the other hand, when the reverse washing time exceeds 90 seconds, the water recovery rate and the operation rate are lowered.

The chemical liquid injected into the reverse cleaning water may be selected as needed, and an aqueous solution of sodium hypochlorite may be mentioned as an example. The injection concentration may be appropriately selected, but a preferable range is 1 to 100mg/L (concentration in reverse washing water), and a more preferable range is 2 to 50 mg/L. In addition, the injection of the chemical liquid is not necessarily required, and may be performed as needed.

The number of times of the drain cycle N (times) may be appropriately set, and may be 1 time when the reverse washing is performed 1 time or 1 time when the reverse washing is performed several times. The preferable range is 1-4 times of reverse washing in the drainage cycle, and the more preferable range is 1-2 times of reverse washing in the drainage cycle. The suction pressure may rise prematurely below the discharge cycle of 1 reverse cleaning 4 times.

Examples of the experiments

The present invention will be described in more detail below based on experimental examples.

[ production of hollow fiber Membrane Module ]

< Experimental example 1>

The hollow fiber membrane was a hydrophilized polyethylene porous hollow fiber membrane (trade name: EX540T, inner diameter 350 μm, outer diameter 540 μm, material: polyethylene, manufactured by Mitsubishi RAYON corporation), 16 hollow fiber membranes were bundled and folded back and spliced with a connecting fiber to prepare a sheet-like hollow fiber membrane (woven width: 950mm, number of fiber bundles: 70).

The sheet-like hollow fiber membranes (27 sheets) were laminated with a spacing of 6mm (the spacing is the length between the center and the center of the sheet-like hollow fiber membrane) while attaching a braided spacer, and one end of the spacer was inserted into an ABS resin cover (cylinder part inner diameter: 124mm) having a rectangular parallelepiped exposed end of the hollow fiber membrane and a cylindrical opening end of the hollow fiber membrane. Next, a potting resin "C4403/N4221" (1.5 kg of a two-component curable polyurethane resin produced by Nippon polyurethane industries Co., Ltd.) was injected to connect and fix the sheet-like hollow fiber membrane to the housing.

Similarly, the other end portion was connected and fixed to a housing, and both end faces were cut off to open the hollow fiber membranes, thereby producing a hollow fiber membrane module having a structure shown in fig. 4 (membrane area: 34 m)²173mm in W, 124mm in D, 50mm in L, 20mm in rectangular solid hollow fiber membrane fixation length, 0.40 in L/D, 1.40 in W/D).

< Experimental example 2>

A hollow fiber membrane module (membrane area 37 m) was produced in the same manner as in example 1, except that 1.3kg of the potting resin was used²173mm in W, 124mm in D, 35mm in L, 20mm in rectangular solid hollow fiber membrane fixation length, 0.28 in L/D, 1.40 in W/D).

< Experimental example 3>

The hollow fiber membrane was a hydrophilized polyethylene porous hollow fiber membrane (trade name: EX780T, inner diameter 500 μm, outer diameter 770 μm, material: polyethylene, manufactured by Mitsubishi RAYON corporation), and 6 hollow fiber membranes were bundled together and spliced together with a connecting fiber while being folded back, to prepare a sheet-like hollow fiber membrane (woven width: 950mm, number of fiber bundles: 82).

While installing the knitting distance-adjusting block, the piece is put inThe hollow fiber membranes (30 sheets) were stacked at an interval of 6mm, and one end of each of the hollow fiber membranes was inserted into an ABS resin-made cap (inner diameter of the cylindrical portion: 145mm) having a rectangular parallelepiped end exposed to the hollow fiber membrane and a cylindrical opening end. Next, the same type of potting resin (1.7kg) as in experimental example 1 was injected to connect and fix the sheet-like hollow fiber membrane to the housing. Then, the end face was cut off, and the hollow fiber membrane was opened to prepare a hollow fiber membrane module having a structure shown in fig. 5 (membrane area: 30 m)²W is 232mm, D is 145mm, L is 60mm, the hollow fiber membrane fixed length of the rectangular parallelepiped portion is 30mm, L/D is 0.41, and W/D is 1.60).

< Experimental example 4>

A sheet-like hollow fiber membrane was produced in the same manner as in experimental example 1, except that the weaving width was 1200mm and the number of fiber bundles was 167.

The sheet-like hollow fiber membranes (27 sheets) were stacked with a spacing of 12mm while attaching a braided distance adjusting block, and one end of the hollow fiber membranes was inserted into a silicone resin injection-molded capsule (inner diameter: 250mm) having a rectangular parallelepiped exposed end of the hollow fiber membranes and a cylindrical shape at the open end of the hollow fiber membranes. Next, the same kind of potting resin (5.2kg) as in experimental example 1 was injected to connect and fix the sheet-like hollow fiber membranes.

Similarly, the sheet-like hollow fiber membranes were bonded and fixed to each other at the other end, and the hollow fiber membranes were opened by cutting off both end faces to prepare hollow fiber membrane modules having the structure shown in FIG. 1 (membrane area: 90 m)²425mm, 250mm, 150mm, 50mm long hollow fiber membrane fixed length of rectangular parallelepiped portion, 0.60L/D, 1.70W/D).

< comparative example 1>

A sheet-like hollow fiber membrane (membrane surface) was produced in the same manner as in Experimental example 1, except that a rectangular parallelepiped housing (pressure receiving surface size: 121mm in long side and 100mm in short side: the same pressure receiving area as that of the cylindrical portion in Experimental example 1) was used from the end of the hollow fiber membrane on the exposed side to the end of the hollow fiber membrane on the open side, and 2.0kg of a potting resin was usedProduct is 35m²Fixing part size: 121mm long side part, 100mm short side part, and 70mm hollow fiber membrane fixed length).

[ repeated pressure resistance test of hollow fiber Membrane Module ]

The hollow fiber membrane modules prepared in experimental examples 1 to 4 and comparative example 1 were subjected to repeated pressure resistance tests.

In the repeated pressure resistance test, a hollow fiber membrane is cut out from a hollow fiber membrane module, and an opening of the hollow fiber membrane is sealed with a potting resin to prepare a test sample. Next, the prepared test sample was placed in a repeated pressure resistance test apparatus, and pressure application and pressure release were repeated from the end face side of the module to measure the number of cycles until the sample was cracked (condition temperature: 40 ℃, pressure 350kPa, cycle: 30 seconds on/30 seconds off, pressure application direction: pressure application from the end face side of the module, number of times: 5000 times at maximum). The results are shown in Table 1.

TABLE 1

	Experimental example 1	Experimental example 2	Experimental example 3	Experimental example 4	Comparative example 1
						Number of cycles	5,000 times (without cracks)	5,000 times (without cracks)	5,000 times (without cracks)	5,000 times (without cracks)	1,530 times (crack occurred on the injection seal surface)

From the results of the repeated pressure resistance test, it was found that the hollow fiber membrane module of the present invention has excellent pressure resistance.

[ production of hollow fiber Membrane Module Unit ]

< Experimental example 5>

Using the hollow-fiber membrane module produced in Experimental example 1, a hollow-fiber membrane module unit (membrane area 136 m) having a structure shown in FIG. 6 was produced²). Thereafter, the hollow fiber membrane module unit was stacked up in 6 layers in the vertical direction to produce a hollow fiber membrane module unit having a structure shown in fig. 8 and a gas diffusion device mounted on the lower portion (membrane area 816 m)²1.2m for a ', 0.4m for b', 2.637m for unit height, 1700m for area efficiency S/a²/m²Unit volume V' 1.266m³Volume efficiency S/V645 m²/m³)。

< Experimental example 6>

A hollow fiber membrane module was fabricated in the same manner as in Experimental example 5, except that 4 layers of the hollow fiber membrane module were stacked in the vertical directionFiber membrane module unit (membrane area 544 m)²1.2m for a ', 0.4m for b', 1.797m for unit height, 1133m for area efficiency S/a²/m²、V’＝0.863m³630m in volumetric efficiency S/V²/m³)。

[ filtration test ]

< Experimental example 7>

The hollow fiber membrane module unit produced in experimental example 5 was attached to a membrane filtration apparatus (a: 1.21m, b: 0.41m, effective water depth: 2.637m, and V: 1.31 m) shown in fig. 9³、V’/V＝0.97)。

Using the membrane filtration apparatus, a filtration test was carried out for 10 days on a sand-containing water (Japanese: running water) to evaluate the suction pressure. The test conditions are shown in Table 2, and the results are shown in Table 3.

< Experimental example 8>

Except that the water tank is set to 1.3m for a, 0.5m for b, 2.637m for effective water depth and 1.71m for V³The filtration test of sandy water (japanese: running water) was carried out in the same manner as in example 7 except that V'/V was 0.74. The test conditions are shown in Table 2, and the results are shown in Table 3.

< Experimental example 9>

The hollow fiber membrane module unit produced in experimental example 6 was installed in a membrane filtration apparatus (a: 1.21m, b: 0.41m, effective water depth: 1.797m, and V'/V: 0.97) as shown in fig. 9. Using the membrane filtration apparatus, a filtration test was carried out for 10 days on a sand-containing water (Japanese: running water) to evaluate the suction pressure. The test conditions are shown in Table 2, and the results are shown in Table 3.

< Experimental example 10>

Except that the water tank is set to 1.3m for a, 0.5m for b, 1.797m for effective water depth and 1.17m for V³The filtration test of sandy water (japanese: running water) was carried out in the same manner as in example 9 except that V' V was 0.74. The test conditions are shown in Table 2, and the results are shown in Table 3.

< comparative example 2>

Except that the water tank is set to 1.5m for a, 0.7m for b, 2.637m for effective water depth and 2.77m for V³The filtration test of sandy water (japanese: running water) was carried out in the same manner as in example 7 except that V'/V was 0.46. The test conditions are shown in Table 2, and the results are shown in Table 3.

< comparative example 3>

Except that the water tank is set to 1.5m for a, 0.7m for b, 1.797m for effective water depth and 1.89m for V³The sand-containing water filtration test was carried out in the same manner as in example 9 except that V'/V was 0.46. The test conditions are shown in Table 2, and the results are shown in Table 3.

TABLE 2

			Examples of the experiments				Comparative example
									7	8	9	10	2	3
			Area efficiency (m)2/m2)			1,700		1,133							1,700	1,133
Volumetric efficiency (m)2/m3)										645		630		645			630
			V/V’			0.97	0.74	0.97	0.74						0.46	0.46
Filtration	J(m/d)									2.0		0.5		2.0			0.5
			T(h)		1				1
	Cleaning of	Gas scrubbing									Air quantity (Nm)3/(m2/h))	200
Time (h)			2
									Reverse cleaning	J’(m/d)	4.0		1.0		4.0	1.0
T’(h)		0.00833
								Draining water		D(m3)		1.07	1.47	0.731	1.01	2.53	1.73
Number of cycles of drainage N (times)		1	1	2	3	1	4

TABLE 3

	Examples of the experiments				Comparative example
							7	8	9	10	2	3
	Suction pressure at the beginning of the test20℃(kPa)	28.0	28.0	15.0	15.0	28.0							15.0

Suction pressure at the end of the test 20 ℃ (kPa)	30.0	29.7	15.5	15.4	29.6	15.3
							Water recovery (%)	96.8	96.3	95.3	95.5	94.8	94.7

As can be seen from the results of the filtration test, the membrane filtration device of the present invention can achieve a water recovery of 95% or more and also has a stable suction pressure during operation.

The hollow fiber membrane module, the hollow fiber membrane module unit, the membrane filtration device, and the operation method thereof according to the present invention can be used for purification of tap water, purification of sewer water, industrial processes, and the like. In the hollow fiber membrane module of the present invention, since the end surface of the fixing member (2) on the side where the hollow fiber membranes are exposed is approximately rectangular and the end surface of the fixing member (2) on the side where the hollow fiber membranes are open is approximately circular, the pressure resistance of the fixing portion of the hollow fiber membranes is not lowered even when the membrane area of the module using the sheet-like hollow fiber membranes having excellent cleaning performance is increased. In addition, in the hollow fiber membrane module unit of the present invention, since the plate-like member (5) having the hole penetrating the cylindrical portion (4) is provided and the position of the hollow fiber membrane module is fixed by the plate-like member (5), the fixing can be performed simply and surely and the integration degree of the hollow fiber membrane can be improved. The membrane filtration device of the present invention including a plurality of hollow fiber membrane modules of the present invention and the membrane filtration device to which the operation method of the present invention is applied are small in size, but have a large membrane area and excellent cleaning performance, and therefore can perform filtration stably for a long period of time.

Claims (11)

1. A hollow fiber membrane module characterized in that the hollow fiber membrane module has a plurality of sheet-like hollow fiber membranes (1), and

a fixing member (2) for fixing at least one end of the plurality of sheet-like fiber membranes (1) in parallel while maintaining the open state;

the end surface of the fixing member (2) on the side where the hollow fiber membranes are exposed is rectangular, and the end surface of the fixing member (2) on the side where the hollow fiber membranes are open is circular.

2. The hollow fiber membrane module according to claim 1, wherein the fixing member (2) has a rectangular parallelepiped part (3) having a rectangular parallelepiped shape on the side where the hollow fiber membranes are exposed, and a cylindrical part (4) having a cylindrical shape on the side where the hollow fiber membranes are open.

3. The hollow fiber membrane module according to claim 2, wherein the diameter of the cylindrical section (4) is d (mm) and the length thereof is l (mm), the following equation is satisfied:

0.2≤L/D≤1.0。

4. the hollow fiber membrane module according to claim 2, wherein when the length of the long side portion of the exposed end face of the hollow fiber membrane of the rectangular parallelepiped (3) is w (mm), and the diameter of the cylindrical portion (4) is d (mm), the following equation is satisfied:

1.0≤W/D≤2.0。

5. a hollow fiber membrane module unit comprising a plurality of hollow fiber membrane modules according to claim 2, wherein a plate-like member (5) having a hole penetrating the cylindrical section (4) is provided on a side surface perpendicular to the membrane surface of the sheet-like hollow fiber membrane (1), and the hollow fiber membrane modules are fixed in position by the plate-like member (5).

6. The hollow fiber membrane module unit according to claim 5, wherein the cylindrical part (4) is fixed by being sandwiched between and inserted into the plate-like member (5) by a water collecting cover (6) engaged with the cylindrical part.

7. The hollow fiber membrane module unit according to claim 6, wherein the cylindrical part (4) and the water collection cover (6) are fixed by screw engagement.

8. A hollow fiber membrane module unit wherein a plurality of hollow fiber membrane module units according to claim 6 are arranged in a vertical direction in an overlapping manner,

the membrane surface of the sheet-like hollow fiber membrane (1) is arranged in the vertical direction,

and the water collecting covers (6) adjacent in the vertical direction are connected with each other by a water collecting component (7) extending in the vertical direction,

a side plate (21) is arranged on the side surface parallel to the membrane surface of the sheet-shaped hollow fiber membrane (1).

9. The hollow fiber membrane module unit according to claim 8, wherein the interval in the vertical direction between the respective sheet-like hollow fiber membranes (1) of the vertically adjacent hollow fiber membrane modules is 20mm or more and 70mm or less.

10. A membrane filtration apparatus which is a membrane filtration apparatus in which a membrane module unit is disposed in a water tank,

the membrane module unit is composed of a plurality of hollow fiber membrane modules,

the hollow fiber membrane module comprises a plurality of sheet-like hollow fiber membranes (1), and a fixing member (2) for fixing at least one end of the plurality of sheet-like fiber membranes (1) in parallel while maintaining an open state; the hollow fiber membrane module is composed of a hollow fiber membrane module in which the end surface of the fixing member (2) on the side where the hollow fiber membranes are exposed is rectangular and the end surface of the fixing member (2) on the side where the hollow fiber membranes are open is circular,

the membrane area of the membrane module unit is set to S (m)²) The projected area of the membrane module unit is set to A (m)²) The volume of the membrane module unit is set to V' (m)³) The volume of the water tank is set to V (m)³) Then, the following 3 relations are satisfied:

… formula (1) with S/A not less than 1000 and not more than 2000

… formula (2) with S/V' not less than 500 ≤ and 800 ·

V'/V is not less than 0.70 and not more than 0.99.

11. A method of operating a membrane filtration apparatus in which a membrane module unit is disposed in a water tank,

the membrane module unit is composed of a plurality of hollow fiber membrane modules,

the hollow fiber membrane module is composed of: a hollow fiber membrane module in which at least one end of a plurality of sheet-like membranes (1) is fixed in parallel by a fixing member (2) while maintaining an open state, the end face of the fixing member (2) on the side where the hollow fiber membranes are exposed is rectangular, and the end face of the fixing member (2) on the side where the hollow fiber membranes are open is circular,

the membrane area of the membrane module unit is set to S (m)²) The filtration flow stream is set to J (m/D), the filtration time is set to T (h), the number of water discharge cycles is set to N (times), and the water discharge amount is set to D (m)³) And a reverse cleaning flow stream is set to J '(m/D) and a reverse cleaning time is set to T' (h), the membrane filtration device is operated by setting a membrane area S, a filtration flow stream J, a filtration time T, a drainage cycle number N, a drainage quantity D, a reverse cleaning flow stream J ', and a reverse cleaning time T' which satisfy the following relational expressions:

N.gtoreq.22.8D/{ S (0.05JT-J 'T') } … … formula (4).