JP3608353B2 - Membrane module and water treatment apparatus using the same - Google Patents

Description

[0001]
The present invention relates to a membrane module and a water treatment apparatus using the same .
[0002]
[Prior art]
When wastewater treatment is performed using a membrane, it is necessary to select an optimal module shape and membrane pore size depending on the suspended solid concentration and viscosity of the stock solution to be filtered, the operation method, the required treated water quality, and the like. Here, the module refers to a filter in which a membrane element is incorporated in a container (housing or casing). Currently available modules include tubular, hollow fiber, spiral, and flat membranes (pleated type, plate & frame type), but each has advantages and disadvantages.
In recent years, an immersion method has been developed in which these membrane modules are immersed in a reactor and a filtrate is obtained by suction filtration. At this time, the membrane module is immersed in a highly turbid liquid such as activated sludge or agglomerated sludge and filtered, so plate and frame type flat membranes that are optimal for filtration of liquids containing solids are mainly used. .
[0003]
When a tubular or hollow fiber module is immersed in the liquid to be filtered, the tubular module cannot secure a large membrane area and is not suitable for mass processing, or the hollow fiber module adheres to the inside of a bundle of hollow fiber membranes. Or, there is a problem that the suspended suspended solids are difficult to remove by air bubbling. On the other hand, an immersion flat membrane type module in which a flat membrane membrane is immersed is easier to clean the membrane surface by air bubbling than a hollow fiber membrane module, and also has a higher membrane packing density than a tubular module. It is considered suitable for filtration of turbid liquid.
However, when the membrane packing density is compared between the submerged flat membrane module and the spiral module, the spiral shape is higher. Therefore, if a spiral membrane module is used, it is considered that the membrane separator can be made compact. However, since the conventional spiral membrane module has a narrow liquid flow path and is not suitable for separation of a liquid containing a solid content, there is no example in which the spiral membrane module is applied to filtration of a highly turbid liquid.
[0004]
A spiral type membrane element is formed by winding a bag-like flat membrane around a water collecting tube shaft together with a spacer, and mounting it in a container called a vessel. At this time, since the spacer portion serves as a flow path for the stock solution, the film interval is determined by the thickness. Although the thickness of the spacer is usually about 1 mm, a spiral type membrane element is also proposed in which the spacer is made into a corrugated plate and expected to promote turbulent flow on the membrane surface. The height is set to 2.5 mm (see Japanese Patent Laid-Open No. 4-87695). However, with such a membrane interval, suspended substances are blocked between the membranes, making it impossible to operate.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a membrane module that can be suction filtered by being immersed in a highly turbid liquid and a water treatment apparatus using the same.
[0006]
[Means for Solving the Problems ]
[0007]
The present invention is characterized in that a plurality of bag-like flat membranes are attached to the filtrate water collecting tube shaft and wound in a spiral so that the membrane interval is 5 to 10 mm. The present invention further the membrane module the longitudinal ends of the bag-shaped flat sheet membrane of the scan Pairaru membrane element cross-sectional shape and characterized by being fixed to the casing or a plurality of poles of circular addition polygonal It is to provide. Moreover, the water treatment apparatus of the present invention is characterized in that one or a plurality of the membrane modules of the present invention are mounted in a reactor.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the spiral membrane element of the present invention has a plurality of bag-like flat membranes attached to the filtrate water collecting tube shaft. Examples of membranes to be used include microfiltration membranes and ultrafiltration membranes. Etc. are preferable.
[0009]
The spiral membrane element of the present invention is formed by winding a plurality of membranes as described above in a spiral so that the membrane spacing is 5 to 10 mm. By setting the distance between the membranes to 5 mm or more, even if a high-turbidity liquid of about 15000 mg / (liter) is filtered, the flow path is not blocked, and bubbling air is reliably supplied between the membranes. Therefore, it was found that accumulation of the cake layer on the film surface can also be prevented. If the membrane distance of the spiral membrane element is 10 mm or less, the membrane packing density is equal to or higher than that of the flat membrane module of the plate & frame type.
[0010]
Moreover, it is preferable to attach a reinforcing material to the upper end and the lower end of the bag-shaped flat membrane in the spiral membrane element of the present invention. As the reinforcing material, it is preferable to use a plastic thin plate whose shape can be freely adjusted, or a wire stretched in a mesh shape. Further, depending on the length of the membrane element in the vertical direction, it is preferable to attach a reinforcing material to an intermediate portion thereof.
[0011]
As described above, the spiral membrane element of the present invention has a sufficiently wide membrane interval and a high membrane packing density. Therefore, the spiral membrane element is effective for immersing this in a liquid to be filtered and performing suction filtration. The liquid material can be used as a liquid to be filtered. As the liquid to be filtered, a liquid containing suspended substances of 5000 to 15000 mg / (liter) is generally targeted.
At that time, the spiral membrane element of the present invention is preferably immersed in the filtrate to be filtrated so that the filtrate collecting pipe axis is positioned perpendicular to the water surface, and suction filtered.
As a suction method, there are a method using a pump and a method using a height difference (head difference), but any method can be applied in the present invention.
[0012]
When the filtration is continued, the suspended matter removed on the membrane surface forms a cake layer, causing an increase in the filtration resistance and increasing the filtration pressure. Therefore, the cake layer on the film surface is regularly removed. For removing the cake layer, it is preferable to perform membrane cleaning by air bubbling from below the membrane element. The air blown from below the spiral membrane element rises between the membranes of the spiral membrane element, and peels and removes the cake layer on the membrane surface by the bubbles and water flow.
[0013]
The membrane module of the present invention is obtained by fixing the spiral membrane element of the present invention as described above to a casing or pole having a circular or polygonal cross section.
The water treatment apparatus of the present invention has one or more membrane modules of the present invention mounted in a reactor. The membrane module is preferably installed such that its filtrate water collection tube axis is positioned perpendicular to the water surface in the reactor. Moreover, it is preferable to provide an air diffuser below the membrane element for air bubbling cleaning of the membrane surface.
[0014]
【Example】
Next, the present invention will be described in more detail based on examples with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a cross-sectional view of a membrane module showing an embodiment of the present invention. In FIG. 1, a membrane module 1 includes a spiral membrane element formed by attaching a plurality of bag-like flat membranes 3 to a filtrate collecting pipe shaft 2 and winding them in a spiral, and each bag-like flat membrane 3 The end in the longitudinal direction is fixed to the casing 4.
[0015]
FIG. 2 is a schematic longitudinal sectional view of a water treatment apparatus in which the membrane module shown in FIG. 1 is mounted in a reactor. In this water treatment apparatus, one membrane module 1 is mounted in a reactor 10 in a state in which the filtrate collecting pipe shaft 2 is positioned perpendicular to the water surface, and the upper and lower ends of the membrane element are reinforced. It is reinforced by the material 5. Further, a diffuser facility 6 is attached below the membrane element. The upper end portion of the filtrate water collecting pipe shaft 2 is above the water surface in the reactor 10.
When wastewater treatment is performed with this water treatment apparatus, the liquid to be filtered put into the reactor 10 is filtered through a membrane by suction filtration, and treated water that has passed through the membrane is sucked from the upper end of the filtrate collecting pipe shaft 2 by suction. It is discharged out of the system.
After continuing the filtration for a predetermined time, air is blown from the diffuser 6 to periodically remove the cake layer on the membrane surface, and air bubbling cleaning is performed.
When the spiral membrane element is immersed in the aeration tank of the sewage treatment plant, since the air amount necessary for biological treatment is always supplied, this air may be used for cleaning.
[0016]
FIG. 3 is a cross-sectional view of a membrane module showing another embodiment of the present invention, and FIG. 4 is an explanatory view showing an arrangement example of the membrane module in the reactor. The membrane module 11 shown in FIG. 3 is different from the embodiment shown in FIG. 1 in that the cross-sectional shape is fixed to a triangular casing 14.
FIG. 5 is a cross-sectional view of a membrane module showing another embodiment of the present invention, and FIG. 6 is an explanatory view showing an arrangement example of the membrane module in the reactor. The membrane module 21 shown in FIG. 5 is the embodiment shown in FIG. 1 in that six bag-like flat membranes 3 are attached to the filtrate collecting pipe shaft 2 and fixed to a casing 24 having a hexagonal cross section. Is different.
The membrane modules shown in FIGS. 3 and 5 can be arranged as shown in FIGS. 4 and 6, respectively, compared to the case where the casing has a circular cross-sectional shape (FIG. 1). And the dead space between adjacent membrane modules is eliminated.
[0017]
FIG. 7 is a plan view of a membrane module showing still another embodiment of the present invention, and FIG. 8 is a side view of the membrane module shown in FIG. In the membrane module 31 shown in FIG. 7, three bag-like flat membranes 33 are mounted on the filtrate collecting pipe shaft 32 and wound to form a spiral membrane element. The end portions in the direction are fixed to the three poles 34, respectively. The upper end and the lower end of the wound bag-shaped flat membrane are reinforced by the reinforcing material 35.
[0018]
FIG. 9 is a plan view of a membrane module showing still another embodiment of the present invention. In this membrane module 41, a bag-like flat membrane 43 is attached to the filtrate water collecting pipe shaft 42 and wound to form a spiral membrane element, and the end of the bag-like flat membrane 43 in the longitudinal direction is The cross-sectional shape is fixed to the casing 44 having a circular shape. The upper end of the bag-like flat membrane 43 is fixed by a wire 45 stretched in a mesh shape as a reinforcing material, and the lower end (not shown) is reinforced by a reinforcing material similar to that shown in FIG. In this embodiment, the mesh width needs to be as large as about 50 mm so that the wire is not clogged.
In addition, the black point in a figure means a fixed point.
[0019]
【The invention's effect】
The membrane module of the present invention can perform efficient solid-liquid separation by immersing in a highly turbid liquid and suction filtration. The present invention also blowing air from below the spiral type membrane element, by performing air bubbling cleaning periodically film surface, it can be removed cake layer of the membrane surface by the bubbles and water, stable over a long period of time Thus, the filtration operation can be performed. Furthermore, in the present invention, by using a casing having a polygonal cross-sectional shape, the film filling density can be remarkably increased, dead space between modules can be eliminated, and the apparatus can be made compact. Therefore, according to the water treatment apparatus of the present invention, wastewater containing high turbidity concentration, for example, wastewater containing activated sludge can be efficiently and stably treated over a long period of time with a compact apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a membrane module showing one embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of a water treatment apparatus of the present invention equipped with the membrane module shown in FIG.
FIG. 3 is a schematic cross-sectional view of a membrane module showing another embodiment of the present invention.
4 is an explanatory view showing an arrangement example of the membrane module shown in FIG. 3; FIG.
FIG. 5 is a schematic cross-sectional view of a membrane module showing still another embodiment of the present invention.
6 is an explanatory view showing an arrangement example of the membrane module shown in FIG. 5. FIG.
FIG. 7 is a plan view of a membrane module showing still another embodiment of the present invention.
8 is a side view of the membrane module shown in FIG.
FIG. 9 is a plan view of a membrane module showing still another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Membrane module 2 Filtrate collecting pipe shaft 3 Bag-shaped flat membrane 4 Casing 5 Reinforcing material 6 Air diffuser 10 Reactor 11 Membrane module 14 Casing 21 Membrane module 24 Casing 31 Membrane module 32 Filtrate collecting tube shaft 33 Bag-shaped flat membrane Membrane 34 Pole 35 Reinforcement material 41 Membrane module 45 Wire

Claims (5)

In a membrane module using a spiral membrane element in which a plurality of bag-like flat membranes are attached to the filtrate water collecting tube shaft and the membrane spacing is 5 to 10 mm, the spiral membrane element is wound in the longitudinal direction of the flat membrane. The membrane module is characterized in that the end portion is fixed to a casing having a circular or polygonal cross section. In a membrane module using a spiral membrane element in which a plurality of bag-like flat membranes are attached to the filtrate water collecting tube shaft and the membrane interval is 5 to 10 mm, the spiral membrane element is wound in the longitudinal direction of the flat membrane. A membrane module, characterized in that the end of is fixed to a plurality of poles. A water treatment apparatus comprising one or more membrane modules according to claim 1 or 2 mounted in a reactor. One or a plurality of the membrane modules according to claim 1 or 2 are mounted so that the filtrate collecting pipe shaft is positioned perpendicular to the water surface in the reactor. One or a plurality of the membrane modules according to claim 1 or 2 are mounted so that the filtrate collecting pipe shaft is positioned perpendicular to the water surface in the reactor, and a diffuser is provided below the membrane element. A water treatment apparatus characterized by comprising.

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