JP2001293337A - Cylindrical membrane element and cleaning method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical membrane element, the membrane performance of which can be easily restored by cleaning the element and which element is suitable for membrane-filtering a slurry of high concentration, and a method for cleaning the element. SOLUTION: The cylindrical membrane element 1 comprises a cylindrical membrane 2 and a plurality of bar-shaped support members 3 which are provided inside or outside the membrane 2 in parallel with the axial line of the membrane 2. By supplying a pressure gas and/or pressure liquid from the secondary side of the membrane 2, the element 1 can be cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical membrane element and a method for cleaning the same, and more particularly, to human waste sludge, sewage sludge,
The present invention relates to a cylindrical membrane element suitable for concentration or solid-liquid separation of industrial waste sludge, or a highly concentrated slurry property liquid such as fermentation cells or pulp slurry, and a method for cleaning the cylindrical membrane element.

[0002]

2. Description of the Related Art The apparatus is compact and excellent in workability for waste treatment of human waste sludge, sewage sludge, industrial waste sludge and the like, and separation process of fermentation bacteria in the industrial fields such as food and pharmaceuticals. For this reason, membrane filtration devices are generally widely used.

However, when the above-mentioned high-concentration slurry liquid is subjected to membrane filtration, the suspended matter in the slurry adheres and accumulates on the membrane surface of the primary side (raw water, that is, the side of water to be filtered) in a usual membrane, and the lapse of time. As a result, the filtration performance decreases.

Conventionally, a method of generating turbulence on the primary surface of a membrane has been adopted to prevent the membrane filtration performance from being deteriorated due to such adhesion and deposition of suspended matter. For example, in a hollow fiber membrane, a method of circulating the slurry in the hollow fiber at a high speed, and in a flat membrane, a method of circulating the slurry so that a turbulent flow occurs on the membrane surface are adopted.

[0005]

However, such a method of generating a turbulent flow on the surface of the film has a disadvantage that the energy consumption for circulating the slurry is large and the equipment is complicated.

The present invention solves the above-mentioned conventional problems, and can easily recover the membrane performance by washing, and is suitable for membrane filtration of a high-concentration slurry liquid, and the washing of the cylindrical membrane element. The purpose is to provide a way to:

[0007]

A cylindrical membrane element according to the present invention comprises a cylindrical membrane and a plurality of rod-shaped membrane supports provided inside and outside the cylindrical membrane in a direction parallel to the axis of the cylindrical membrane. And a member.

The method for cleaning a cylindrical membrane element according to the present invention is a method for cleaning such a cylindrical membrane element according to the present invention, wherein the cylindrical membrane element is washed from the secondary side of the cylindrical membrane, that is, from the filtered water (permeated water) side. It is characterized by supplying pressurized gas and / or liquid.

In the cylindrical membrane element of the present invention,
The cylindrical membrane is supported by the membrane support member, and swings in the centrifugal direction during membrane filtration and in the centripetal direction during washing (backwashing), so that the deposits on the membrane surface can be easily peeled and removed. Therefore, the membrane performance can be easily recovered only by periodically performing cleaning (hereinafter, sometimes referred to as “backwashing”) in which pressurized gas and / or liquid is supplied from the secondary side of the cylindrical membrane. be able to.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a cylindrical membrane element according to the present invention. FIG. 1 (a) shows a state during membrane filtration, and FIG. 1 (b) shows a state during backwashing. . FIG.
1 is a diagram showing an embodiment of a cylindrical membrane of a cylindrical membrane element of the present invention, wherein (a) is a perspective view showing a state before winding;
(B) is a sectional view showing the state after winding. FIG. 3 is a system diagram illustrating an embodiment of the membrane filtration step and the washing step of the cylindrical membrane element of the present invention.

A cylindrical membrane element 1 shown in FIGS. 1A and 1B has a cylindrical membrane 2 and a plurality of cylindrical membrane elements 2 provided inside and outside the cylindrical membrane 2 in a direction parallel to the axis of the cylindrical membrane 2. (FIG. 1 (a),
(8 in (b)) rod-shaped membrane support member 3 (3A to 3H)
It is composed of As shown in the drawing, the membrane support members 3 are arranged on the same circumference at equal intervals. The cylindrical membrane 2 is zigzag so that the membrane support members 3A to 3H are alternately located inside and outside, that is, among the eight membrane support members 3A to 3H, the membrane support members 3A, 3C, 3E, 3G is arranged on the inner peripheral side of the cylindrical membrane 2, and the membrane support members 3B, 3D, 3F, 3H are arranged on the outer peripheral side of the cylindrical membrane 2.

Although the number of the membrane support members 3 is arbitrary,
As described above, it is preferable that the number of the cylindrical membranes 2 is even, in order to arrange them every other inside and outside of the cylindrical membrane 2. In order to sufficiently obtain the effect of removing adhered substances due to rocking of the cylindrical membrane 2 during membrane filtration and backwashing described below,
The number of the membrane support members 3 is preferably about 6 to 24. The diameter of the membrane support member 3 is 5 to 20 mm.
It is preferred that it is about.

On the other hand, if the inner diameter of the cylindrical membrane 2 is excessively small, the fluidity of slurry such as sludge flowing through the membrane is poor, and there is a possibility of blockage of the flow path. Preferably, there is. The upper limit of the inner diameter of the cylindrical film 2 is not particularly limited, but is generally 200 mm or less from the viewpoint of handleability and the like.

The membrane material of the cylindrical membrane 2 may be any material as long as it is applied to a normal membrane filtration element, and any of them can be applied.
Fluororesins such as polytetrafluoroethylene, polysulfone, and the like are preferable in terms of physical strength that can sufficiently secure the swinging effect of the film described later, and polytetrafluoroethylene is particularly optimum.

FIG. 1A shows a cylindrical membrane element 1 composed of such a cylindrical membrane 2 and a membrane support member 3.
As shown in (1), at the time of membrane filtration, the cylindrical membrane 2 is moved from the inside of the cylindrical membrane 2 which is the primary side of the membrane by the internal pressure of the liquid for filtering the membrane to the inner side of the membrane supporting members 3A, 3C, 3E, 3G. And expands in the centrifugal direction while being supported by the outer peripheral membrane support members 3B, 3D, 3F, and 3H. Then, at the time of backwashing in which pressurized air and / or liquid is supplied from the outer peripheral side of the cylindrical film 2 which is the secondary side of the cylindrical film 2, the pressure of the backwash fluid is used as shown in FIG. The cylindrical membrane 2 separates from the outer peripheral side membrane support members 3B, 3D, 3F, 3H, and contracts in the centripetal direction while being supported by the inner peripheral side membrane support members 3A, 3C, 3E, 3G. . Therefore, in the membrane backwashing step, the cylindrical membrane 2 is subjected to the pressing force of the backwash fluid, and the cylindrical membrane 2 swings greatly during the backwash as compared with the membrane filtration.
Deposits on the primary surface of the cylindrical film 2, that is, the inner peripheral surface of the cylindrical film 2, are easily removed and removed.

Incidentally, the cylindrical membrane 2 needs to be a porous membrane having a pore diameter smaller than the particle diameter of the suspended substance in the slurry in order to separate the suspended substance in the slurry to be subjected to membrane filtration. It is said. At the same time, the cylindrical membrane 2
It is required to have a physical strength that can sufficiently withstand swings during membrane filtration and backwashing as shown in (a) and (b).

Therefore, in order to combine such pore diameter with durability against membrane oscillation, the cylindrical membrane 2 according to the present invention is required.
Preferably has a multilayer structure as shown in FIG.

The cylindrical membrane 2 shown in FIG. 2B is obtained by forming a large-pore-diameter support membrane layer 2B as a reinforcing layer on the outer periphery of a microporous thin film layer 2A responsible for membrane filtration.

The pore thin film layer 2A preferably has a pore diameter of about 0.01 to 1 μm and a thickness of about 10 to 50 μm from the viewpoint of membrane filtration.

In order to secure the strength of the cylindrical membrane 2, the large-pore-diameter support membrane layer 2B has a pore diameter of 1 to 10 μm and a thickness of 500 μm.
It is preferable that the thickness is 5000 μm.

The cylindrical film 2 having such a multilayer structure is shown in FIG.
As shown in (a), the microporous thin film 2a is laminated on one end side of the large pore diameter support membrane 2b, and it can be easily manufactured by winding in the direction of the arrow from the lamination end side.

Both of the porous thin film 2a and the large-diameter support film 2b are made of fluororesin, polysulfone, polyvinyl alcohol, etc., and are particularly preferably made of polytetrafluoroethylene.

Such a cylindrical membrane element of the present invention can perform membrane filtration with the inside of the cylindrical membrane 2 as the primary side and the outer periphery as the secondary side, and pressurized gas and / or
Alternatively, it is possible to easily remove the attached matter on the inner peripheral surface of the cylindrical film 2 by supplying the liquid.

This backwashing varies depending on the properties of the slurry to be subjected to membrane filtration, etc.
Once every second for 1 to 10 seconds, especially 30 minutes for membrane filtration
It is preferable to perform backwash for 1-2 seconds per second.

Next, a method of operating the membrane filtration step and the backwashing step using the cylindrical membrane element of the present invention will be described with reference to FIG.

In FIG. 3, reference numeral 10 denotes a membrane module in which a cylindrical membrane element 1 of the present invention is housed in a pressure-resistant container 4. 5 is an air filter, 6 is a water purification filter,
Reference numeral 7 denotes a liquid level detection sensor.

This apparatus introduces a slurry flowing from a slurry introduction pipe 11 into a membrane module 10 and performs membrane filtration.

The membrane module 10 has a raw water chamber (primary side) and a filtered water chamber (secondary side) separated by the cylindrical membrane element 1. The raw water chamber has an inlet port 10a and an outlet port 10b. Is provided.

The filtered water chamber is provided with an inlet port 10c for tap water or pressurized air and an outlet port 10d for filtered water.

The slurry introduction pipe 11 has an introduction valve V
₁ is provided, the drain pipe 12 is branched from between the introduction valve V ₁ and the port 10a of the pipe 11, drain valve V ₂ is provided in the drain pipe 12.

The pipe 1 is connected to the slurry outflow port 10b.
3, the exhaust valves V ₃ and the exhaust pipe 14 is connected in this order, the liquid level detection sensor 7 is provided in the pipe 13.

In order to pressurize the slurry in the raw water chamber of the membrane module 10 with air (air), air from a compressed air source is supplied to the pipe 13 through the pipe 15, the air filter 5, and the pipe 1.
6, and it is capable introduced through the supply valve V ₄ and the pipe 17.

To clean the raw water chamber with tap water, tap water is supplied to the pipe 13 by the pipe 18 and the water supply valve V _5.
And can be introduced through a pipe 19.

[0035] In order to introduce tap water filtration water chamber of the membrane module 10, the pipe 18 is branched pipe 20, water purification filter 6, the inlet port 10c of the filtration water chamber via a washing water valve V ₆ and the pipe 21 Communicating.

The pipe 21 is branched from the pipe 16
The air from the pipe 22 is ₇Can be introduced via
It has been.

[0037] outlet port 10d of the filtration water chamber is filtered water outlet pipe 23 is connected, takeout valve V ₈ is provided in the pipe 23.

Next, a description will be given of a filtration step, a washing step, and a backwashing step by the filtration device having such a configuration.

[Water Sampling Step] A predetermined amount of slurry is introduced into the membrane module 10 from the pipe 11 by opening the introduction valve V ₁ and the exhaust valve V ₃ . Have opened the exhaust valve V ₃ and the introduction valve V ₁ to the detection of the liquid level at the liquid level measuring sensor 7, the exhaust valves V at the stage where the liquid level measuring sensor 7 detects the liquid surface
₃ and close the inlet valve _{V 1.}

[0040] As the [Filtration step] takeout valve V ₈ opens, and collecting the filtered water through the cylindrical membrane element 1 of the membrane module 10 from a slurry having solid. In this filtration step, the solid content of the slurry gradually covers the membrane surface, making it difficult for filtered water to flow out. Therefore, the open air supply valve _{V 4,} guides the air in the pipe 13 at about 0.1~0.2MPa through the air filter 5. Thereby, the slurry in the raw water chamber of the membrane module 10 is pressurized by the air pressure, and the filtered water is taken out from the pipe 23.

[Washing Step 1] In the filtering step, sufficient filtered water may not be secured depending on the type of slurry. In that case, close the supply valve V ₄ and the lead valve V _8, applying a counter pressure to the cylindrical membrane element 1 by opening briefly the exhaust valve V ₃ and the air supply valve V _7. Thereby, the solid matter adhering to the surface of the cylindrical membrane element 1 on the raw water chamber side is temporarily separated from the membrane surface. Then, filtered water is taken out again by the same operation as in the filtration step.

The water collecting step, the filtering step and the washing step 1 are repeated until a predetermined amount of slurry is processed.

[Extrusion Step] After the filtration, the air supply valve V ₄ and the introduction valve V ₁ are opened to push back the slurry remaining in the membrane module 10 and the peripheral piping from the introduction piping 11 by air pressure.

[Cleaning Step 2] In order to clean the inside of the membrane module 10, the water supply valve V ₅ and the drain valve V ₂ are opened to supply cleaning water such as tap water through the pipes 18, 19 and 13. The dirt is introduced into the raw water chamber, and dirt attached to the inner surface of the cylindrical membrane element 1 is washed away.
₂ and drain through the drain pipe 12.

[Cleaning Step 3] Since the cleaning step 2 is for cleaning the film surface with water, it may not be possible to remove dirt attached to the surface of the cylindrical membrane element 1 or in the film. In addition, if the filter is used for a long period of time, dirt accumulates and may hinder the filtration process. Therefore, the following cleaning is performed.

That is, the washing water valve V ₆ and the drain valve V ₂ are opened, and the water purification filter 6 for removing solids in the washing water is opened.
The washing water is introduced into the filtration water chamber of the membrane module 10 through the filter, the washing water is passed from the filtration water side of the cylindrical membrane element 1 to the raw water side, and the solid content adhering to the inner surface of the cylindrical membrane element 1 Wash off.

[0047] The washing, the air supply valve V ₇ is opened, even if the compressed air may also be carried out in a gas-liquid mixture of pressurized air and washing water.

In FIG. 1, the cleaning water and the pressurized air used for cleaning the membrane module 10, particularly the cleaning water and the pressurized air supplied so as to pass through the cylindrical membrane element 1, are all filtered by the filters 6 and 5. The dust removal treatment is performed so as not to contain particles larger than the pore diameter of the membrane element 1. By removing particles that block the membrane holes of the cylindrical membrane element 1 in this manner, contamination by washing water or washing air during washing can be prevented, and effective membrane washing can be performed.

In this cleaning step, FIG.
As shown in (b), the cylindrical membrane 2 of the cylindrical membrane element 1
By swinging, it is possible to obtain a good effect of removing and cleaning the attached matter.

[0050]

As described in detail above, according to the present invention, it is possible to easily remove the deposits on the membrane surface and recover the membrane performance only by performing regular backwashing. In a membrane filtration process such as concentration, separation, and separation of fermentation cells, membrane filtration of a high-concentration slurry can be stably performed over a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a cylindrical membrane element of the present invention. FIG. 1 (a) shows a state at the time of membrane filtration,
(B) The figure shows the state at the time of backwashing.

2A and 2B are diagrams showing an embodiment of a cylindrical membrane of the cylindrical membrane element of the present invention, wherein FIG. 2A is a perspective view showing a state before winding, and FIG. 2B is a sectional view showing a state after winding. It is.

FIG. 3 is a system diagram illustrating an embodiment of a membrane filtration step and a washing step of the cylindrical membrane element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical membrane element 2 Cylindrical membrane 3 Membrane support member 2a Porous thin film 2b Large pore diameter support membrane 2A Large pore thin film layer 2B Large pore diameter support membrane layer 4 Pressure vessel 5 Air filter 6 Water purification filter 7 Liquid level detection sensor 10 Membrane module

Claims (2)

[Claims] 1. A cylindrical shape comprising: a cylindrical film; and a plurality of rod-shaped film support members provided inside and outside the cylindrical film in a direction parallel to an axis of the cylindrical film. Membrane element. 2. The method for cleaning a cylindrical membrane element according to claim 1, wherein pressurized gas and / or liquid is supplied from a secondary side of the cylindrical membrane.