JP2000350925A - Membrane separating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily specify a filter membrane element whose membrane is broken and facilitate the control of a water circulation volume of water to be treated and purifying water for backward washing to the filter membrane element. SOLUTION: This membrane separating device is a pressure-type large-size membrane separating device which treats water to be treated such as river water by membrane separation. In addition, the device is of the same constitution as a conventional membrane separation device excepting the constitution of treated water chambers 42 of a pressure container 40 and that of treated water pipes 44 incidental to the treated water chambers 42. The pressure container 40 of the membrane separating device is equipped with the treated water chamber 42 provided per each filter membrane element 12 above an upper container wall 41 and the individual treated water pipes 44 connected to the upper part of each of the treated water chambers 42. Each of the individual treated water pipes 44 is equipped with a manual flow rate regulating valve 46 and a water sampling pipe 50 with an ON-OFF valve connected to a high- sensitivity turbidimeter 48 branches off from each of the individual treated water pipes 44 on the upstream of the flow rate regulating valve 46.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane separation device, and more particularly, to a membrane separation device for inspecting a membrane rupture of a filtration membrane element or a group of a predetermined number of filtration membrane elements. Also, the present invention relates to a membrane separation apparatus which is capable of controlling the flow rates of water to be treated and backwash water, and which is optimal as a pressure-type large-capacity membrane separation apparatus.

[0002]

2. Description of the Related Art Conventionally, when raw water such as river water is treated to produce purified water or industrial water, or when wastewater is treated, as one of a series of treatment processes, suspended water in treated water is treated. MF membrane, UF membrane, N
A membrane separation device using a filtration membrane such as an F membrane is used.

Here, the configuration of a conventional large-sized pressure-type membrane separation apparatus will be described with reference to FIG. FIG. 5 is a flow sheet showing the configuration of a conventional large pressure type membrane separation apparatus. The large pressure type membrane separation device 10 is a device for treating river water as water to be treated, and as shown in FIG. 5, formed as a pressure vessel and has a membrane separation tower 14 having a plurality of filtration membrane elements 12 therein. And a treated water tank 16 for storing the treated water.
A treated water pump 18 for feeding water from the treated water tank 16 to the membrane separation tower 14, a treated water tank 20 for containing treated water obtained by subjecting the treated water to membrane separation, and treating as backwash water A backwash pump 22 for sending water from the treated water tank 20 to the membrane separation tower 14 is provided.

The membrane separation tower 14 has a boundary between the filtration membrane of the filtration membrane element 12 and the partition wall 24 as shown in FIG.
It is partitioned into a lower treated water chamber 26 and an upper treated water chamber 28. The filtration membrane element 12 is configured as a modular element in which, for example, several hundred hollow fiber UF membranes are bundled as a filtration membrane, and is supported by the partition wall 24.
It hangs down in the water chamber 26 to be treated.

[0005] The water to be treated is the treated water chamber 2 of the membrane separation tower 14.
The water is sent to the water chamber 26 by the water pump 18 through the water pipe 30 connected to the bottom of the filter 6 and is permeated through the filtration membrane element 12 to be subjected to membrane separation. The water flows into the water chamber 28. The treated water flows out to the treated water tank 20 via the treated water pipe 32 connected to the treated water chamber 28. The backwashing water is sent from the treated water tank 20 to the treated water chamber 28 by the backwashed water pump 22 via the backwashed water pipe 34 connected to the treated water pipe 32, and the filtration membrane element 12 is subjected to membrane separation processing. Conversely, the water passes through the treated water chamber 26 while passing through the filter membrane to wash the filtration membrane.
Is discharged to the outside through the backwash water drainage pipe 36 from the lower part of the water. In addition, in the upper part of the water chamber 26 to be treated of the membrane separation tower 14,
A vent pipe 38 is provided.

[0006]

When the membrane separation device 10 is operated for a long period of time, the filtration membrane of the filtration membrane element 12 is damaged or broken, and a part of the water to be treated is removed. In some cases, the water passes through a damaged or broken portion of the filtration membrane and flows into the treated water chamber 28 without being subjected to the membrane separation treatment, thereby deteriorating the quality of the treated water. However, the above-described conventional membrane separation device 10 has a problem that unless the operation is stopped, it is difficult to detect a filtration membrane element in which a membrane is damaged or a membrane is broken (hereinafter, simply referred to as a membrane break).

Therefore, conventionally, when the quality of the treated water is lowered, when there is a suspicion that the membrane of the filtration membrane element is broken, the operation of the membrane separation device 10 is temporarily stopped, and the membrane separation tower 14 is disassembled. All the filtration membrane elements 12 were taken out, and the membrane breakage inspection of the filtration membrane elements 12 had to be performed for each one. For this reason, the treatment efficiency of the membrane separation device 12 was reduced, and a predetermined amount of treated water could not be obtained.

In addition, in a large-capacity pressure-type membrane separation apparatus in which a large number, for example, 100, of filtration membrane elements are installed in one membrane separation tower, membrane breakage occurs in the filtration membrane element due to deterioration of the quality of treated water. It is actually difficult to judge. That is, when the number of the installed filtration membrane elements is large, when the water to be treated is mixed into the treated water due to the membrane breakage of a small number of the filtration membrane elements, even if a high-sensitivity turbidity meter or a fine particle meter is used. However, it is extremely difficult to detect the mixing of the treated water with the treated water. This is because the number of filtration membrane elements is large, the amount of treated water is enormous, and it is difficult to detect a small amount of water to be treated due to dilution with a large amount of treated water. Further, even if it can be determined that a membrane rupture has occurred in the filtration membrane element, in order to specify the membrane rupture membrane element out of the 100 filtration membrane elements, 100 filtration membranes are required from the membrane separation tower. Take out the element, 1
It was necessary to check the filtration membrane by carrying out a single aeration test or the like.

[0009] On the other hand, it is extremely important to detect the membrane breakage of the filtration membrane element. This is because, for example, when bacteria or bacteria that accompany the water to be treated enter the treated water, even if the amount is very small, a problem often occurs in the safety of the treated water.

In the conventional membrane separation apparatus, the flow rates of the water to be treated and the backwash water can be controlled for each membrane separation tower, but the flow rates of the water to be treated and the backwash water can be controlled for each filtration membrane element. There is no control. On the other hand, when a large number of filtration membrane elements are installed in the membrane separation tower, generally, the flow rate of the water to be treated and the backwash water per unit area of the filtration membrane differs depending on the installation location of the filtration membrane element. Becomes uneven. As a result, for example, when determining the timing of chemical cleaning of a conventional membrane separation device, the flow rate of the water to be treated per unit area of the filtration membrane is large, or the flow rate of the backwash water per unit area of the filtration membrane is small. Since the filtration membrane element is used as a reference, there is a problem that the frequency of chemical cleaning increases.

In the above description, the problem is explained by taking as an example a membrane separation apparatus in which raw water such as river water is treated water.
The same problem exists with general liquid membrane separation, which is not limited to water membrane separation. Therefore, an object of the present invention is to provide a membrane separation device having a configuration that facilitates identification of a membrane element in which a membrane has been broken and that facilitates control of the flow rates of a liquid to be treated and a backwashing liquid through the membrane element. It is to be.

[0012]

Means for Solving the Problems In the course of solving the above-mentioned problems, the present inventor has installed one filter membrane element in one pressure vessel to detect membrane breakage for each filter membrane element. In addition, it has been considered that the flow rates of the liquid to be treated and the backwashing liquid can be controlled for each filtration membrane element. However, in this case, the membrane separation device becomes large and complicated, the operation becomes difficult, and the equipment cost increases and the installation space becomes large, so that it is not economically feasible. Therefore, the inventor of the present invention conceived of providing a processing liquid chamber for each filtration membrane element or providing a common processing liquid chamber for a plurality of filtration membrane elements, repeated experiments, and completed the present invention. Was.

[0013] To achieve the above object, a membrane separation device according to the present invention comprises a plurality of filtration membrane elements in a pressure vessel, and transfers from a treatment liquid chamber partitioned in the pressure vessel to a treatment liquid chamber. In an external pressure can type membrane separation device that allows a liquid to be treated to pass through a filtration membrane element, a treatment liquid chamber provided for each filtration membrane element, or provided in common to a plurality of filtration membrane elements, And a processing liquid pipe connected to each of the processing liquid chambers.

In the present invention, since the filtration membrane element is separated and independent for each treatment liquid chamber, it is possible to inspect the membrane breakage of the filtration membrane element for each treatment liquid chamber. There is no limitation on the means for inspecting the film breakage. For example, a suspended matter detecting means is provided in an individual processing liquid pipe connected to each processing liquid chamber, and the film breakage is determined based on deterioration of the properties of the processing liquid. As a means for detecting a suspended solid, for example, a turbidity meter or a fine particle meter is used. In other words, the membrane separation device according to the present invention includes a common processing liquid chamber for the filtration membrane elements belonging to each inspection group for each inspection group of the filtration membrane elements for performing the membrane breakage inspection.

In the present invention, the number of filtration membrane elements belonging to the processing liquid chamber is not limited, and the number of filtration membrane elements may be one, a plurality, or a large number of, for example, 10 to 15. Further, the number of filtration membrane elements in the processing liquid chambers may be the same for all the processing liquid chambers, or may be different for each processing liquid chamber. There is no limitation on the shape of the processing liquid chamber, and the processing liquid chamber may be box-shaped, cylindrical, or polygonal cylindrical, and the processing liquid chamber may be arranged freely as long as it can correspond to the arrangement of the filtration membrane element. A cylindrical processing liquid chamber may be provided in a grid pattern on the container wall, a long processing liquid chamber may be continuously provided concentrically from the center of the pressure vessel, or a short processing liquid chamber may be provided separately. Alternatively, they may be provided continuously or spaced apart in the radial direction. INDUSTRIAL APPLICABILITY The present invention can be applied to a membrane separation device regardless of the type of filtration membrane element, the type of filtration membrane, the properties of the liquid to be treated, the cross-flow method or the dead-end flow method (whole-filtration method).

In a preferred embodiment of the present invention, a flow control valve is provided in the processing liquid pipe upstream of the connection position with the backwash liquid pipe. This makes it possible to control the flow rates of the liquid to be processed and the reverse cleaning liquid for each processing liquid chamber. Further, when the filtration membrane element is broken, the outflow of the processing liquid from the processing liquid chamber belonging to the filtration membrane element whose membrane is broken is stopped by closing the flow control valve, and the operation of the membrane separation device is continued. You can continue.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 The present embodiment is an example of an embodiment of a membrane separation apparatus according to the present invention. FIG. 1 is a flow sheet showing a configuration of a main part of the membrane separation apparatus of the embodiment, and FIG. It is sectional drawing of the treatment water chamber which shows the structure of a treatment water chamber. The same components as those in FIG. 5 among the components and parts shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. The membrane separation device of the present embodiment is a large pressure type membrane separation device that performs membrane separation treatment of water to be treated such as river water, and has a configuration of a treatment water chamber of a membrane separation tower and a configuration of a treatment water pipe associated therewith. Except for the above, it has the same configuration as the conventional membrane separation device 10 described with reference to FIG.

The membrane separation tower 40 of the membrane separation apparatus according to the present embodiment.
Is formed as a pressure vessel, and as shown in FIG. 1, is connected to a treated water chamber 42 provided for each filtration membrane element 12 on the upper vessel wall 41 and an upper part of each treated water chamber 42. And an individual treatment water pipe 44. Further, the membrane separation tower 40 has the water chamber 26 to be treated in the lower part defined by the upper vessel wall 41 as in the conventional case, and the filtration membrane element 12 is suspended from the upper vessel wall 41. A treated water pipe 30 and a backwash water drain pipe 36 are connected to a lower portion of the treated water chamber 26, respectively.

Each of the individual treatment water pipes 44 is provided with a manual flow control valve 46. Further, a water sampling pipe 50 with an open / close valve connected to the high-sensitivity turbidity meter 48 is branched from each of the individual treatment water pipes 44 upstream of the flow control valve 46. Although not shown, a control device is provided, and each water sampling pipe 50 has an on-off valve sequentially opened in accordance with a set schedule. Turbidity is measured. Each individual treated water pipe 44 joins the treated water pipe 32 and the treated water tank 20
(See FIG. 5).

As shown in FIG. 2, the treated water chamber 42 is a cylindrical small chamber, and is fixed to the upper container wall 41 with, for example, embedded bolts 52 or the like. Further, in the treated water chamber 42, the filtration membrane element 12 hangs down through an element hole 54 penetrating the upper container wall 41. The filtration membrane element 12 is provided at the upper end of the filtration membrane element 12 and has an annular plate 12a to which a bundle of hollow fiber membranes is fixed, and a bolt 5 embedded therein.
6 and the like, the upper container wall 4 is fixed to the upper container wall 41.
1 supported. The bundles of hollow fiber membranes are joined to each other with an adhesive or the like, and are fixed to the central hole of the annular plate 12a.

With reference to FIGS. 1 and 5, a method of operating the membrane separation apparatus of the embodiment will be described. In operation, first, in the same manner as in the conventional membrane separation apparatus 10, water to be treated is passed through the membrane separation tower 40, and a membrane separation treatment is performed to obtain treated water. In the present embodiment, when the water to be treated is passed, by adjusting the manual flow control valve 46 provided in each of the individual treated water pipes 44, regardless of the difference in the arrangement of the filtration membrane element 12, each filtration can be performed. The water to be treated can be passed through the membrane element 12 at the same flow rate. After the water to be treated is passed through and the membrane separation treatment is performed for several tens of minutes to several hours, a back washing treatment is performed using the treated water.

During the back washing process, the water pump 18 to be treated
Is stopped, and the opening / closing valve of the vent pipe 38 and the backwash water drain pipe 3
The on / off valve 6 is opened to drain the water to be treated and the concentrated suspended solids in the membrane separation tower 14. Next, the on / off valve of the treated water pipe 32 is closed, the backwash water pump 22 is started, and the treated water in the treated water tank 20 is passed through the backwash water pipe 34, the treated water pipe 32, and the individual treated water pipe 44. Water is supplied to the chamber 42. The backwash water permeates while washing the filtration membrane element 12, flows into the treated water chamber 26, and flows out of the backwash water drain pipe 36 to the outside.

The flow rate of the backwash water during the backwash is 1.0 to 1.0.
5.0 m / day is appropriate, and the backwashing time is 30 seconds to 3 seconds.
It is about 00 seconds. At this time, the flow rate of the backwash water passing through each filtration membrane element 12 can be equalized by adjusting the flow rate control valve 46 irrespective of the difference in arrangement of the filtration membrane elements 12. The filtration membrane element 12 can be washed uniformly and uniformly.

If the membrane separation treatment is continued for several tens of days to several months, the pressure difference between the membranes of the filtration membrane element 12 may be reduced only by the ordinary backwashing operation when the flow rate of the water to be treated is constant. It becomes difficult, and it becomes impossible to secure a predetermined flow rate. Therefore, when the transmembrane pressure reaches a predetermined value, chemical cleaning of the filtration membrane element 12 is performed using a chemical such as an acid, an alkali or a surfactant.

In this embodiment, the treated water chamber 42, the individually treated water pipe 44, and the water sampling pipe 50 are
Since the turbidity of the treated water can be measured for each filtration membrane element 12, it is possible to quickly identify the membrane element 12 whose membrane has been broken while operating the membrane separation device. In addition, a manual flow control valve 4 is provided for each individual treatment water pipe 44.
6 is provided, and the flow rates of the water to be treated and the backwash water can be adjusted for each filtration membrane element 12, so that the clogging state of the filtration membrane and the chemical cleaning time can be uniformly set throughout the filtration membrane element 12. can do. Note that the flow control valve 46 is not limited to a manual flow control valve, and an automatic flow control valve can be used.

Evaluation Test of Membrane Separation Apparatus of Embodiment Example In order to evaluate the membrane separation apparatus of this embodiment example, an experiment of detecting membrane breakage was performed using the membrane separation apparatus shown in the following specific example. Specific Example of Membrane Separator 1) Specifications of Filtration Membrane Element 12 Membrane material: inner diameter 0.8 mm x outer diameter 1.2 mm x length 2000
mm external pressure type UF hollow fiber membrane (fraction molecular weight 50,0
00, manufactured by PAN) Element outer diameter: 150 mm in diameter x 2200 mm in length Element membrane area: 40 m ² / piece Flux of treated water (flow rate through filtration membrane): 0.
7m / day

2) Specifications of membrane separation tower 14 Dimensions: 1600 mm in diameter × 4000 mm in height Pressure resistance: 5 kgf / cm ² Number of filtration membrane elements per membrane separation tower: 31 Total membrane area of filtration membrane elements per membrane separation tower: 1,2
Treatment water amount per 40 m ² membrane separation tower: 868 m ³ / day 3) Specifications of membrane separation device Number of membrane separation towers per membrane separation device: 4 Total number of filtration membrane elements: 124 Treatment water amount: about 3,400 m ³ / day Day

4) Raw water (water to be treated) pH 7.0 to 7.5, turbidity 5 to 15 degrees, and water temperature 1 which were pre-filtered with an auto strainer having a mesh size of 200 μm.
River water at 5 to 23 ° C 5) Treated water Turbidity: 0.01 ° or less 6) Operating conditions of membrane separation device Filtration method: Quantitative filtration method Operating pressure: 0.3 kgf / cm ² Washing method: LV 2.5 m / day Backwashing with treated water at different flow conditions

One of the hundreds of hollow fiber membranes in one filtration membrane element 12 provided in the membrane separation apparatus of the above specific example.
The book was deliberately fractured, and a detection experiment of the fracture was performed. In this experiment, the turbidity of the treated water of the filtration membrane element which did not break was about 0.01 degree on average and 0.05 degree at the maximum. On the other hand, the turbidity of the treated water of the filtration membrane element whose membrane was intentionally broken was measured to be 0.2 degrees. The numerical value of 0.2 degrees is about 20 times the turbidity of the treated water of the filtration membrane element in which the membrane is not broken, and is a turbidity difference that can be clearly judged as a membrane break.

Therefore, in this embodiment, if there is a spare filtration membrane element, it can be replaced with a filtration membrane element identified as having a membrane breakage, and water can be immediately restarted. Alternatively, the individual treatment water pipe 4 of the filtration membrane element 12 whose membrane has been broken
The operation of the membrane separation apparatus can be continued by closing the flow control valve 46 of 4 and allowing the treated water to flow out from the other individual treated water pipes 44.

Using a conventional membrane separator 10 having the same specifications as in the specific example, except for the configuration of the treated water chamber, one hollow fiber membrane of the filtration membrane element is intentionally broken, and then the same as in the above-described example. Then, a water flow experiment was performed. When treated water was sampled and the turbidity was measured, the turbidity of the treated water was around 0.02 degrees. That is, even if there is a filtration membrane element in which a membrane break has occurred, the turbidity of the treated water is the turbidity of the treated water when no membrane break has occurred in all the filter membrane elements.
There is almost no difference in turbidity from 1 degree. Therefore, it is extremely difficult to determine that a membrane break has occurred in the filtration membrane element. In addition, the number of fine particles in the treated water was counted using a fine particle meter.
There is a difference between the number of fine particles of the treated water when the membrane break occurs in one hollow fiber membrane of the filtration membrane element and the number of the fine particles of the treated water when the membrane break does not occur in all the filter membrane elements. , No significant difference could be found.

The difference between the turbidity of the treated water and the number of fine particles in the conventional membrane separation device 10 due to the presence or absence of membrane breakage is that the treated water of the 31 filtration membrane elements 12 is combined and then collected. This is because mixed water to be treated is diluted into a large amount of treated water.

Embodiment 2 This embodiment is a modification of Embodiment 1 and is similar to that of FIG.
Is a schematic plan view showing an arrangement of a treated water chamber of Embodiment 2;
FIG. 4 is a sectional view of the treated water chamber taken along the line II in FIG. In the membrane separation device of the present embodiment, one treated water chamber 60
As shown in FIGS. 3 and 4, a common treated water chamber for a plurality of filtration membrane elements 12 (in FIG. 3, one treated water chamber is simply provided for four filtration membrane elements). Is provided on the upper container wall 41 of the membrane separation tower 40. Also, an individual treated water pipe 62 is provided in each treated water chamber 60. In the membrane separation device of the present embodiment, similarly to the first embodiment, a large number of filtration membrane elements 12 hang down in the water chamber 26 to be treated of the membrane separation tower 40. It has the same configuration as the membrane separation device 40 of the first embodiment.

In this embodiment, the turbidity of the treated water is measured for the group of four filtration membrane elements 12 belonging to the common treated water chamber 60, and the judgment of membrane breakage is made for each group.

[0035]

According to the present invention, the processing liquid chambers provided for each one of the filtration membrane elements or commonly provided for a plurality of filtration membrane elements, and the processing liquid chambers connected to the respective processing liquid chambers. With the provision of the liquid tube, the membrane rupture inspection can be performed for each treatment liquid chamber, so that it is easy to identify the filtration membrane element whose membrane has ruptured. In addition, by providing a flow control valve in the processing liquid pipe upstream of the connection position with the reverse cleaning liquid pipe, the flow rates of the liquid to be processed and the reverse cleaning liquid pipe with respect to the filtration membrane element can be easily controlled. For example, since the reverse cleaning solution can be uniformly passed through the filtration membrane element unit, the number of defective cleanings can be reduced, the time interval between chemical cleaning can be extended, and the membrane separation processing time can be extended. Furthermore, when the filtration membrane element is broken, the outflow of the processing liquid from the processing liquid chamber belonging to the filtration membrane element whose membrane is broken is stopped by closing the flow control valve,
The operation of the membrane separation device can be continued.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a configuration of a main part of a membrane separation device of a first embodiment.

FIG. 2 is a cross-sectional view of a processing liquid chamber showing a configuration of the processing liquid chamber.

FIG. 3 is a schematic plan view showing an arrangement of a processing liquid chamber according to a second embodiment.

4 is a cross-sectional view of the processing liquid chamber taken along the line II in FIG.

FIG. 5 is a flow sheet showing a configuration of a conventional large-sized pressure type membrane separation apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Conventional large pressure type membrane separation apparatus 12 Filtration membrane element 14 Membrane separation tower 16 Treated water tank 18 Treated water pump 20 Treated water tank 22 Backwash pump 24 Partition wall 26 Treated water chamber 28 Treated water chamber 30 Treated water pipe Reference Signs List 32 treated water pipe 34 backwash water pipe 36 backwash water drain pipe 38 vent pipe 40 membrane separation tower of membrane separator of Embodiment 1 41 upper vessel wall 42 treated water chamber 44 individual treated water pipe 46 flow control valve 48 high sensitivity turbidity Total 50 Water sampling pipe with on-off valve 52 Embedded bolt 54 Element hole 56 Embedded bolt 60 Treated water chamber of membrane separation device of Embodiment 2 62 Individually treated water pipe

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA06 GA07 HA03 HA19 JA18A JA25A JA64Z JA70A KC03 KC13 KC16 KE01Q KE05P KE07P KE12P KE13P KE15P KE16P KE22Q KE23Q KE24Q KE28Q LA03 MA01B04PA

Claims (3)

[Claims] 1. An external pressure can body type having a plurality of filtration membrane elements in a pressure vessel and allowing a treatment liquid to permeate from the treatment liquid chamber partitioned in the pressure vessel to the treatment liquid chamber via the filtration membrane element. A processing liquid chamber provided for each filtration membrane element or provided in common to a plurality of filtration membrane elements, and a processing liquid pipe connected to each processing liquid chamber. A membrane separation device. 2. The membrane separation apparatus according to claim 1, wherein a suspension detecting means is provided in a processing liquid tube connected to each processing liquid chamber. 3. The membrane separation apparatus according to claim 1, wherein a flow control valve is provided in a processing liquid pipe upstream of a connection position with the reverse cleaning liquid pipe through which the reverse cleaning liquid flows.