JP3862005B2 - Membrane filtration device and membrane filtration method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane filtration device using a membrane module used in a water purification facility that purifies and supplies raw water taken from lakes and rivers, and particularly when the membrane module is damaged and exceeds a turbidity control value. The present invention relates to a membrane filtration device and a membrane filtration method for stopping only a membrane module that has been made and continuing water supply from other membrane modules.
[0002]
[Prior art]
In recent years, there is concern about contamination of purified water by the pathogenic microorganism Cryptosporidium. In such a water source, the Cryptosporidium provisional guideline stipulates that the turbidity of treated water be 0.1 ° C. or less. For this reason, monitoring of water quality turbidity is further strengthened in water purification facilities.
[0003]
Recently, membrane filtration methods that provide good quality water have been widely introduced into purified water. This membrane filtration method is not only a water purification method that can easily automate the operation management of water purification facilities, and can solve the shortage of manpower, but is also an excellent method that can remove the above-mentioned Cryptosporidium. Furthermore, in order to increase the amount of water purification, a multi-sequence system in which two or more membrane filtration devices are arranged in parallel has been adopted. Then, a turbidity measuring device for detecting film breakage is installed for each series, and the treated water is constantly monitored.
[0004]
FIG. 7 is a configuration diagram (in the case of four filtration series) showing an outline of a conventional membrane filtration apparatus. In FIG. 7, when the membrane of the membrane module of the first filtration series 11 is damaged, the turbidity detected by the turbidity measuring device TuIR1 provided in that series rises, and the turbidity is, for example, a provisional reference value. When 1/10 of 0.01 degree (referred to as turbidity control value), the control means (not shown) closes the shut-off valve V1, and the other second filtration series 12, third filtration series 13, It becomes the driving | operation which makes a membrane permeated water by the 4th filtration series 14 (75% of the maximum water supply amount). Thereafter, the membrane module in the first filtration system 11 in which the membrane is damaged is manually inspected to determine the damaged membrane module. Then, the damaged membrane module is updated, and then the turbidity remaining in the pipe is removed. 100% operation is restored after cleaning.
[0005]
FIG. 8 is a diagram showing the water supply capacity over time in the conventional example. 7 and 8, when the membrane of the membrane module included in the first filtration series 11 is damaged, the second filtration series 12 and the third filtration are stopped with the first filtration series 11 stopped. In order to continue operation with the three filtration systems of the series 13 and the fourth filtration system 14, the operation is continued with a water supply amount of 3/4 (75%) of the maximum water supply amount. Identify and recover.
[0006]
[Problems to be solved by the invention]
However, if the membrane module is damaged and an abnormality in turbidity is detected, it will be rushed to the site, and the damaged membrane module will be judged, removed and replaced, and the piping will be cleaned and restored. 1 filtration system 11 had a problem of stopping water supply for a long time (about 12 hours or more).
[0007]
By the way, according to the guidelines for introduction of membrane filtration devices in small-scale water supply (1994), even when one series of membrane filtration devices with multiple filtration systems stops, water supply capacity of 75% or more of the maximum water supply capacity It is required to have
[0008]
The present invention has been made to solve the above problems, and when abnormal turbidity is detected in treated water from a filtration line having a membrane module, the filtration line is stopped immediately, By identifying the damaged membrane module and automatically returning the operation of the remaining membrane module while stopping the membrane module, water supply can be performed even if any membrane module in the multi-line system is damaged. An object of the present invention is to provide a membrane filtration device and a membrane filtration method capable of quickly returning the ability unattended.
[0009]
[Means for Solving the Problems]
1st invention of this invention which solved the said subject is the membrane filtration apparatus by which the raw | natural water sent from the raw | natural water tank is connected in parallel, and is filtered through the filtration series which consists of several membrane modules, A turbidity measuring means for measuring the turbidity of the membrane permeated water provided at each outlet of the filtration series, and a cutoff provided at each outlet of the filtration series for blocking the passage of the membrane permeated water as the feed water A valve, a return valve for returning the membrane permeated water to the raw water tank, a membrane module valve for controlling the flow of the membrane permeated water from the membrane module, and a valve control means for controlling the opening and closing of the valve, The valve control means opens the return valve of the filtration series when the turbidity measurement means detects abnormal turbidity in which the membrane permeated water sent from the filtration series exceeds a predetermined reference value, and the shutoff valve Close the plural in the filtration series Membrane modules are sequentially switched, and the membrane permeate is sent to each membrane module. The turbidity measuring means identifies the membrane module exhibiting abnormal turbidity, closes the membrane module valve of the membrane module, and It opens, the return valve is closed, the membrane module valve of another membrane module is opened, and the membrane permeated water is fed.
[0010]
According to the first aspect of the present invention, even if the membrane of the membrane module is damaged, the membrane module of which membrane module is damaged can be specified by the turbidity measuring means. Only the membrane module whose membrane is broken can be stopped and other membrane modules can be operated by the control means, and the amount of water supplied as standard can be secured.
[0011]
The invention according to claim 2 is the invention according to claim 1, wherein the filtration system is characterized in that a membrane module valve is provided at each outlet or inlet of the membrane module.
[0012]
According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, in addition to the effect of the first aspect of the invention, the membrane permeated water that has become turbidity abnormal by providing the membrane module valve at each outlet or inlet of the membrane module. Can be stopped.
[0013]
According to a third aspect of the present invention, in the first aspect of the present invention, the turbidity measuring means of the membrane permeated water from the membrane module detects abnormal turbidity, the shutoff valve is closed, and the return valve is opened. As a result, the turbidity measuring means, the shutoff valve, and the return valve are arranged so that the membrane permeated water is returned to the raw water tank via the return valve.
[0014]
According to the third aspect of the invention, in addition to the effect of the first aspect of the invention, when the turbidity measuring means detects a turbidity abnormality, it shuts off the transmission of the permeated water indicating the abnormality. The membrane permeate that does not match is not supplied as purified water.
[0015]
Invention of Claim 4 is the membrane filtration method by which the raw | natural water sent from the raw | natural water tank is connected in parallel, and is filtered through the filtration series which consists of a some membrane module, Membrane permeated water from the said filtration series When the turbidity is measured and the turbidity shows an abnormal value, the water supply as the membrane permeated water from the filtration series showing the abnormality is interrupted and returned to the raw water tank, and each membrane module of the filtration series is returned. In order to measure the turbidity, the raw water is sent to each other, and the turbidity measurement is stopped. As a result, the permeable water from the membrane module showing abnormality is stopped, while the permeable water from other membrane modules is resumed. It is characterized by that.
[0016]
According to the invention described in claim 4, even if the membrane of the membrane module is broken, the membrane module of which membrane module is broken can be specified by the turbidity measuring means. Only the membrane module whose membrane is broken can be stopped and other membrane modules can be operated by the control means, and the amount of water supplied as standard can be secured. Moreover, it can prevent that the membrane permeated water whose turbidity exceeds a predetermined value is sent to the water supply side.
[0017]
The invention described in claim 5 is characterized in that, in the invention described in claim 4, an additive having turbidity is added to the raw water tank.
[0018]
According to the fifth aspect of the invention, in addition to the effect of the fourth aspect of the invention, when detecting the abnormal module, it is possible to detect abnormal turbidity when the raw water has low turbidity. Even when there is a possibility that it cannot be performed, a membrane module with a broken membrane can be easily identified by adding a turbidity component.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a membrane filtration device according to the present invention will be described in detail with reference to the drawings.
[0020]
FIG. 1 is a configuration diagram (four filtration series) showing the outline of the membrane filtration device of the present invention. In FIG. 1, raw water is taken into a first filtration series 11, a second filtration series 12, a third filtration series 13, and a fourth filtration series 14. Subsequent to these filtration series 11, 12, 13, and 14, turbidity measuring devices TuIR 1, TuIR 2, TuIR 3, and TuIR 4 for detecting the turbidity of the membrane permeated water are provided. The flowmeters FIQ1, FIQ2, FIQ3, and FIQ4 are provided for detecting the flow rate. Further, return valves V11, V12, V13, and V14 are provided in the subsequent stage for returning the membrane permeated water to the raw water when the turbidity measuring device detects abnormal turbidity. Furthermore, it has shut-off valves V1, V2, V3, V4 for supplying or stopping the membrane permeated water as supply water, and when at least one of the turbidity measuring devices TuIR1, TuIR2, TuIR3, TuIR4 detects an abnormality, the abnormality is detected. While opening the return valve of the series to which the detected turbidity measuring instrument is connected, the shut-off valve is closed and the supply of feed water from this series is stopped.
[0021]
In order that the membrane permeated water showing abnormal turbidity is not supplied as feed water, if the turbidity measuring device detects turbidity anomaly, water is supplied by the shutoff valve before the membrane permeated water showing abnormal turbidity is sent as feed water Must be stopped and returned to the raw water tank by return valve. Therefore, the turbidity measuring means, the shut-off valve and the return valve need to be arranged so as to realize it. If this is grasped temporally, the time t1 when the membrane permeated water showing abnormal turbidity is sent through the pipe from the first filtration series 11 to the shutoff valve V1, and the detection time t2 of the turbidity measuring device TuIR1. Then, the following equation (1) is established between the time t3 when the shutoff valve V1 is “closed” and the return valve V11 is “open”. In addition, it is desirable that the same relationship is established in the second filtration series 12, the third filtration series 13, and the fourth filtration series 14.
t1> t2 + t3 (1)
At this time, before the membrane permeated water reaches the water supply side, abnormal turbidity is detected, the return valve is opened, and the membrane permeated water showing the abnormal turbidity is returned to the raw water tank through the return valve.
[0022]
FIG. 2 is a schematic configuration diagram showing a schematic configuration for one series of the membrane filtration device, and shows the first filtration series 11 as an example. In FIG. 2, in the first filtration system 11, five membrane modules M11, M12, M13, M14, and M15 are provided in parallel, and the membrane module valve V101 provided on the outlet side of the membrane permeated water of each membrane module. , V102, V103, V104, V105 and the shut-off valve V1 pass the membrane permeated water as feed water. These membrane module valves are controlled by valve control means.
[0023]
Next, the operation will be described. The filtration series is composed of four series of first filtration series 11, second filtration series 12, third filtration series 13, and fourth filtration series 14, of which the filtration series of the first filtration series 11 has. A case where the membrane module M11 is damaged will be described.
[0024]
As shown in FIG. 2, the membrane module M11 is included when the membrane of the membrane module M11 of the first filtration system 11 is broken and the turbidity of the membrane permeated water is 0.01 degree or more of the turbidity control value. The turbidity measuring device TuIR1 of the first filtration system 11 is accompanied by an alarm notifying that the membrane has been damaged, closing the shut-off valve V1 of the damaged first filtration system 11, opening the return valve V11, and generating membrane permeated water. Return to the aquarium. This treatment prevents the permeated water having a turbidity exceeding 0.01 degrees from entering the water supply side.
[0025]
On the other hand, the 2nd filtration series 12, the 3rd filtration series 13, and the 4th filtration series 14 in which turbidity does not show abnormality continue operation and water supply. As a result, in this example, since the membrane filtration device 1 according to the present invention is composed of four filtration series, the water supply amount at this time is 75% (3/4) of the maximum water supply amount.
[0026]
Next, in the first filtration system 11 having the damaged membrane module, the damaged membrane module M11 is identified while the raw water (including the returned membrane permeated water) is circulated by the raw water pump and the circulation pump P (identification). The details of the method will be described later), and the damaged filtration sequence number and the damaged membrane module number are displayed on a display board (not shown). The membrane module M11 displaying this number is in a stopped state since the membrane module valve V101 connected to the membrane module M11 has already been closed. At this time, the membrane modules M12, M13, M14, and M15 that are not damaged start operation, but after cleaning the piping, when the shutoff valve is opened and the operation is started, the filtration series and the shutoff valve Therefore, there is a risk that the permeated water that exceeds the permissible turbidity is primarily supplied. Therefore, when the turbidity measuring device TuIR1 shows a normal value, the return valve V11 is closed, the shutoff valve V1 is opened, and water supply is started. As described above, the membrane filtration device 1 according to this example has four filtration series, and each filtration series has five membrane modules, and the membrane permeation of this one membrane module. Since the amount of water production corresponds to 1/20 (5%) of the whole, the water supply amount at this time is 19/20 (95%) of the maximum water supply amount.
[0027]
FIG. 3 is a flowchart showing a method for sequentially inspecting and returning damaged membrane modules according to this embodiment of the present invention. In FIG. 1, when the turbidity measuring device TuIR1 of the first filtration system 11 detects abnormal turbidity, the return valve V11 is opened, the shutoff valve V1 is closed, and the supply of membrane permeated water to the outside is stopped. Is done. By this operation, as shown in FIG. 3, all the membrane module valves of the filtration system 11 that detected abnormal turbidity are closed (step S1). Next, the flow rate is adjusted from the membrane permeated water to one membrane module (step S2). Next, the first membrane module valve V101 is opened (step S3). Next, turbidity is detected by the turbidity measuring device TuIR1 (step S4).
[0028]
Thereby, membrane module M11 which shows abnormal turbidity is specified, and which membrane module was damaged can be specified (Step S5). Thus, the turbidity of the membrane permeated water by all the membrane modules M11, M12, M13, M14, and M15 is sequentially measured (step S6: YES). As a result, the membrane module valve whose turbidity is within the standard is opened (step S7). Thereafter, when the turbidity measuring device TuIR1 is stabilized at a normal value (managed turbidity or less) (step S8: YES), the return valve V11 is closed and the shutoff valve V1 is opened (step S9).
[0029]
Thus, one membrane module valve is opened, the other membrane module valve is closed, membrane permeated water is returned, and turbidity is sequentially measured. As a result, the membrane module with the damaged membrane shows an abnormal value, and the membrane module with the damaged membrane is identified. Usually, this takes about 2 hours.
[0030]
FIG. 5 is a diagram showing an operation state until a membrane module having a damaged membrane according to the present embodiment of the present invention is identified and returned. As shown in FIG. 5, when a filtration unit having a damaged membrane module is detected and stopped, the water supply amount becomes 3/4 (75%) of the maximum water supply amount, but after 2 hours, 19/20 The water supply has returned to (95%).
[0031]
In addition, when raw | natural water shows low turbidity, it exists in the tendency for the failure | damage of a membrane module to be difficult to determine with a high performance turbidity measuring device. This tendency is particularly exhibited in a large membrane filtration apparatus that requires a large number of large membrane modules to be arranged. When 10,000 hollow fibers are accommodated in one large membrane module, when the turbidity leaks from one hollow fiber, the setting value detected by the turbidity measuring device is 0.01 degree turbidity. Assuming that the recovery rate is 90 to 95% and the number of membrane modules in one filtration system is five, the turbidity required for the raw water is calculated to be about 10 degrees.
[0032]
Therefore, a membrane module with a broken membrane can be detected by injecting turbidity with such turbidity. In short, turbidity may be easily detected according to each condition. The turbidity may be added during normal operation or only when a damaged membrane module is specified.
[0033]
At this time, as the turbidity, turbidity adjusted by mixing the turbidity of the washing waste water may be used. Further, powdered activated carbon, bentonite, or kaolin may be used. In some cases, from the point of view of reuse, magnetic ferritic or martensitic stainless powder is used, and a powder having a particle size range of 1 to 5 μm is injected, and the drainage side uses a magnetic recovery device. It may be collected.
[0034]
The present invention relates to a filtration system having a membrane module in which the membrane is broken, stopping the supply of membrane permeated water from the filtration series in which abnormal turbidity is detected, identifying the damaged membrane module in the filtration series, and the membrane module The filtration system that stopped the supply of membrane permeated water was automatically restored, and after a very short time, the membrane filtration device was restored to a water supply capacity of approximately 95% or more of the maximum water supply. Is possible. In addition, it is possible to save labor for restoration and further strengthen labor saving of the membrane filtration device. At this time, it is possible to make the water supply capacity 100% of the maximum water supply amount by demonstrating the reserve power of the membrane. In this case, it is not necessary to replace the membrane in a short time, and maintenance can be performed without reducing the amount of water supply when the membrane is close to chemical cleaning or when the differential pressure of the membrane is high. it can.
[0035]
Further, by incorporating a return pipe for returning the membrane permeated water, the turbidity until the return can be continuously monitored, and a reliable operation method that does not temporarily lower the quality of the feed water can be obtained.
[0036]
In addition, when the operation is performed according to the process of the automatic return system described above, it is possible to avoid the risk of sending the membrane permeated water having a turbidity exceeding 0.01 degree to the water supply side. In addition, when a membrane breakage is detected, an alarm notifying that the membrane module is broken is notified through a telemeter or the like. Conventionally, in facilities having a membrane filtration device, it takes time to determine a damaged module and to clean a pipe, and it is difficult to return the response in a short time, and specialized knowledge is required for the membrane. On the other hand, the membrane filtration apparatus according to the present invention automatically performs the identification of the damaged membrane module and the return of the water supply all automatically, and also displays the filtration series number having the damaged membrane module and the damaged membrane module number. Therefore, it does not take time to identify a damaged membrane module and does not require an advanced engineer. Furthermore, conventionally, a filtration device in which a membrane module has been damaged will be operated with a low water supply capacity until complete recovery, but the membrane filtration device according to the present invention will operate with a high water supply capacity after a very short time. Continued and rarely require urgent action.
[0037]
The embodiment described above is an example for explaining the present invention, and the present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the gist of the invention. is there. For example, when identifying a membrane module with a broken membrane, it is possible to pass water by half of the total number of membrane modules, sequentially inspect, and shorten the confirmation time. Further, as shown in FIG. 6, a membrane module valve may be provided on the inlet side of the membrane module. Moreover, although the filtration series demonstrated the case of four, if it is two or more, how many may be provided. As for the membrane module, five cases have been described, but any number may be provided. Regarding the damaged membrane module number shown on the display board, a series of numbers may be assigned to all the membrane modules, and the numbers may be displayed.
[0038]
〔Example〕
Examples will be described below.
FIG. 4 is a graph showing the turbidity of the membrane permeated water treated by the damaged membrane module. In FIG. 4, among the five membrane modules M11, M12, M13, M14, and M15, one hollow fiber in the membrane module M13 is cut, and the turbidity measurement results are shown. The conditions at this time were as follows.
・ Water flow process 80 minutes ・ Raw water turbidity adjusted to 10 degrees (by powdered activated carbon)
・ Membrane module 72m ² / line, 10,000 hollow fibers per membrane module ・ Raw water flux 1.8m / day, raw water volume 720m ³ / day, recovery rate 95%
[0039]
As shown in FIG. 4, the damaged membrane module can be identified as the membrane module M13 showing abnormal turbidity, can be determined by a densitometer, and can be automatically handled. At this time, the maximum turbidity did not exceed 0.01 degree even after the return of water flow.
[0040]
Moreover, in order to specify a membrane module with a damaged membrane at an early stage, it is possible to increase the amount of turbidity injected to increase the turbidity by 2 to 3 times, thereby speeding up the specification. This is particularly effective when the number of filtration series and the number of membrane modules are large.
[0041]
By the way, when the membrane filtration device is restored by the conventional method, the membrane permeated water is passed through after the pipe is washed. As a result, the turbidity rises, and the maximum turbidity is detected to be 0.15 degree. It took about 30 minutes to reach a turbidity of ˜0.02.
[0042]
【The invention's effect】
As described above, according to the first aspect of the present invention, even if the membrane of the membrane module is damaged, the membrane module in which the membrane is damaged can be identified by the valve control means. Only the membrane module can be stopped and the other membrane modules can be operated, and the amount of water supplied as standard can be ensured.
[0043]
According to the second aspect of the present invention, by providing the membrane module valve at the outlet or the inlet of the membrane module, it is possible to stop the water supply of the membrane permeated water having turbidity abnormality.
[0044]
According to the third aspect of the present invention, when the turbidity measuring means detects turbidity abnormality, the membrane permeated water that does not meet the standard can be supplied as purified water in order to shut off the water transmission of the abnormally permeated water. Absent.
[0045]
According to the invention described in claim 4, even if the membrane of the membrane module is damaged, the membrane module with the damaged membrane can be identified by the valve control means, so that only the membrane module with the damaged membrane is stopped. Thus, other membrane modules can be operated, and the amount of water supplied as standard can be secured.
[0046]
According to the fifth aspect of the present invention, when detecting an abnormal membrane module, even if the raw water has a low turbidity and there is a possibility that an abnormality in turbidity may not be detected, By adding the degree component, it is possible to easily identify the membrane module having a broken membrane.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an outline of a membrane filtration apparatus according to an embodiment of the present invention.
FIG. 2 is a system diagram showing an outline in which a membrane module valve is provided on the treated water side of the membrane module according to the embodiment of the present invention.
FIG. 3 is a flowchart for specifying a damaged membrane module according to an embodiment of the present invention.
FIG. 4 is a graph showing the turbidity of membrane permeated water treated by a damaged membrane module according to an embodiment of the present invention.
FIG. 5 is a diagram showing an operation state in which a damaged membrane module according to an embodiment of the present invention is specified and returned.
FIG. 6 is a system diagram showing an outline in which a membrane module valve is provided on the raw water side of the membrane module according to the embodiment of the present invention.
FIG. 7 is a system diagram showing an outline of a conventional membrane filtration device.
FIG. 8 is a diagram showing an operation state in which a damaged membrane module according to a conventional example is specified and returned.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Membrane filtration apparatus 11 1st filtration series 12 2nd filtration series 13 3rd filtration series 14 4th filtration series V1, V2, V3, V4 Shutoff valves V11, V12, V13, V14 Return valves V101, V102, V103, V104, V105 Module valve

Claims (5)

  In a membrane filtration apparatus in which raw water sent from a raw water tank is connected in parallel and filtered through a filtration line composed of a plurality of membrane modules, the turbidity of membrane permeated water is provided at each outlet of the filtration line. A turbidity measuring means for measuring water, a shutoff valve that is provided at each outlet of the filtration system and blocks passage of the membrane permeate as feed water, and a return valve that returns the membrane permeate to the raw water tank. A membrane module valve for controlling the flow of membrane permeated water from the membrane module, and a valve control means for controlling opening and closing of the valve, wherein the valve control means is fed with the membrane permeated water fed from the filtration system When the turbidity measuring means detects abnormal turbidity exceeding a predetermined reference value, the return valve of the filtration series is opened, the shutoff valve is closed, and a plurality of membrane modules in the filtration series are sequentially switched. Membrane on each membrane module Water is fed, and the turbidity measuring means identifies the membrane module exhibiting abnormal turbidity, closes the membrane module valve of this membrane module, opens the shutoff valve, closes the return valve, and other membranes. A membrane filtration device characterized in that the membrane module valve of the module is opened to feed permeated water.   The membrane filtration apparatus according to claim 1, wherein the filtration system is provided with the membrane module valve at each outlet or inlet of the membrane module.   The turbidity measuring means of the membrane permeated water from the membrane module detects abnormal turbidity, closes the shut-off valve, and opens the return valve. As a result, the membrane permeated water passes through the return valve and is a raw water tank. The membrane filtration device according to claim 1, wherein the turbidity measuring means, the shutoff valve, and the return valve are arranged so as to be returned to. In the membrane filtration method in which the raw water sent from the raw water tank is connected in parallel and filtered through a filtration series consisting of a plurality of membrane modules, the turbidity of the membrane permeated water is measured from the filtration series, When an abnormal value is indicated, the water supply as membrane permeated water passing through the abnormal filtration line is interrupted and returned to the raw water tank, and the raw water is supplied by switching sequentially for each membrane module of the filtration line. The membrane filtration method is characterized in that the turbidity is measured, and as a result, the transmission of the membrane permeated water from the membrane module showing abnormality is stopped while the water transmission of the membrane permeated water from another membrane module is resumed. .   The membrane filtration method according to claim 4, wherein an additive having turbidity is added to the raw water tank.

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