JPWO2011062268A1 - Water purifier and operation method thereof - Google Patents

Abstract

The water purifier of the present invention includes a raw water supply line, a plurality of membrane modules provided in parallel for filtering the raw water, and a plurality of supply channels branched from the raw water supply line and connected to the raw water inlet of each membrane module And an on-off valve provided in each of the supply channels, a backwash water discharge line connected to the on-off valve, a permeate transfer line, and a permeate of each membrane module branched from the permeate transfer line. And a plurality of transfer channels connected to the outlet. ADVANTAGE OF THE INVENTION According to this invention, the water purifying apparatus which can supply a fixed amount of permeated water stably, and its operation method can be provided compactly with the high processing capacity of filtration.

Description

The present invention relates to a water purifier provided with a membrane module and an operation method thereof.
This application claims priority on November 20, 2009 based on Japanese Patent Application No. 2009-265363 for which it applied to Japan, and uses the content here.

  Conventionally, as a method for removing pollutants and fungi contained in raw water such as tap water, a water purification method using a membrane module is known, and a water purification apparatus provided with a membrane module is widely used at home and the like.

However, the water purifier provided with the membrane module is likely to be clogged due to the solid matter such as pollutants in the raw water adhering to the surface of the filtration membrane, and the filtration performance is likely to deteriorate with use.
The recovery of the filtration performance can be solved by making the filtration membrane disposable and replacing it as necessary. However, there is a problem that the replacement takes time. Moreover, disposable is not always preferable in terms of environmental problems and resource saving.

Therefore, a method for recovering the filtration performance by washing the membrane module has been proposed. For example, Patent Literature 1 includes two filtration units (membrane modules) provided in parallel and a switchable three-way valve that supplies raw water to one of the filtration units, and the filtered water (permeated water) is supplied. A filtration device that supplies water-absorbed buildings is disclosed. According to the said filtration apparatus, raw water is first supplied to one filtration unit A, it filters, and the obtained permeated water is supplied to a water supply building. When the filtration filter A provided in the filtration unit A is clogged with dirt or the like, the supply of the raw water to the filtration unit A is stopped and the three-way valve is switched so that the raw water is supplied to the other filtration unit B. Next, filtration is performed in the filtration unit B, and most of the obtained permeated water is supplied to the water-supplied building, and a part of the permeated water is sent to the filtration unit A, and the permeated water is caused to flow back to the filter A. Wash (backwash). And when the filter B of the filtration unit B is clogged, this time, the supply of raw water is switched from the filtration unit B to the filtration unit A by the three-way valve.
Next, filtration is performed by the filtration unit A, and most of the obtained permeated water is supplied to the water supply building, and a part of the permeated water is sent to the filtration unit B to backwash the filter B.
As described above, according to the filtration device described in Patent Document 1, the clogged filtration filter can be reused, and the use can be continued without replacing the filter over a long period of time.

JP 11-137976 A

However, since the filtration device described in Patent Document 1 performs filtration alternately by two filtration units, the filtration capacity is low, and the amount of permeated water that can be supplied is small. In addition, since filtration is performed with one filtration unit and at the same time, the other filtration unit is backwashed using a part of the obtained permeate, the amount of permeate that can be supplied is easily reduced. In order to secure a sufficient amount of permeated water, a filtration unit having a large filtration filter or a plurality of filtration filters may be installed, but it is difficult to make the filter compact.
In addition, since the amount of permeated water used for backwashing changes depending on the progress of backwashing, the amount of permeated water that can be supplied is easily changed when filtration and backwashing are performed simultaneously, and a certain amount of permeated water is stably supplied. That wasn't always easy.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a water purifier that is compact, has a high filtration capacity, and can stably supply a certain amount of permeated water, and an operation method thereof.

The water purifier of the present invention includes a raw water supply line, a plurality of membrane modules provided in parallel for filtering the raw water, and a plurality of supply channels branched from the raw water supply line and connected to the raw water inlet of each membrane module And an on-off valve provided in each of the supply channels, a backwash water discharge line connected to the on-off valve, a permeate transfer line, and a permeate of each membrane module branched from the permeate transfer line. And a plurality of transfer channels connected to the outlet.

  The operation method of the water purification apparatus of the present invention operates a water purification apparatus including a plurality of membrane modules provided in parallel for filtering raw water and a plurality of on-off valves for switching supply and stop of the raw water to the membrane modules. In the method, the on-off valve is switched so as to supply raw water to all of the membrane modules, and the raw water is supplied to some of the membrane modules (A) of the membrane modules, the filtration step of filtering the raw water, and the remaining The on-off valve is switched to stop the supply of raw water to the membrane module (B), all the permeated water that has passed through the membrane module (A) is sent to the membrane module (B), and the membrane module (B) is backwashed The first backwashing step, and the supply of raw water to the membrane module (A) is stopped, the on-off valve is switched to supply raw water to the membrane module (B), and the permeated water that has permeated the membrane module (B) of It sends a hand membrane module (A), and repeating the a second backwash step of backwashing the membrane module (A).

  In addition, immediately before the first backwashing step and the second backwashing step, the on-off valve is switched so as to stop the supply of raw water to all of the membrane modules, and air is taken into the membrane modules to supply raw water. It is preferable to perform a raw water discharging step of discharging and a raw water filling step of switching the on-off valve so as to supply raw water to all of the membrane modules and supplying and filling raw water to all of the membrane modules.

  According to the present invention, it is possible to provide a water purifier that is compact and has a high filtering capacity and that can stably supply a certain amount of permeated water and an operation method thereof.

It is a schematic block diagram which shows an example of the water purifier used for this invention. It is a figure which shows flows, such as raw | natural water at the time of a 1st backwash process. It is a figure which shows flows, such as raw | natural water at the time of a 2nd backwash process. It is a figure which shows flows, such as raw | natural water at the time of a raw | natural water discharge process. It is a figure which shows flows, such as raw | natural water at the time of a raw | natural water filling process.

Hereinafter, the present invention will be described in detail.
[Water purification equipment]
Drawing 1 is a schematic structure figure showing an example of a water purifier used for the present invention. This water purifier 1 includes two membrane modules 10 and 10 provided in parallel for filtering raw water supplied from a tap water, a raw water supply line 20 for supplying raw water to the membrane modules 10 and 10, and a membrane module. On-off valves 40, 40 for switching the supply and stop of the raw water to the membrane modules 10, 10 provided in the middle of the raw water supply line 20 and the permeated water transfer line 30 for transferring the permeated water that has passed through 10, 10; Via the backwash water discharge line 50 for discharging the backwash water used for backwashing the membrane modules 10, 10, the air supply / exhaust line 60 for supplying and exhausting air to the membrane modules 10, 10, and the membrane modules 10, 10 And a bypass line 70 that can transfer the raw water to the permeate transfer line 30 without being configured.

The membrane module 10 includes a filtration membrane 11.
As the filtration membrane 11, a filtration membrane usually used in a water purifier such as a microfiltration membrane, an ultrafiltration membrane, and a nanofiltration membrane can be used. Of these, a microfiltration membrane is preferred.
Examples of the shape of the filtration membrane 11 include a hollow fiber membrane, a flat membrane, a tubular membrane, and a spiral membrane. These are suitable as filtration membranes because they can easily block the passage of solids and fungi of 0.1 μm or more. Among them, hollow fiber membranes are preferred, for example, cellulose-based, polyolefin-based, polyvinyl alcohol-based, PMMA (polymethacrylic acid) It is preferable to use hollow fiber membranes made of various materials such as methyl) and polysulfone. In particular, it is preferable to use a hollow fiber membrane made of a material having high elongation such as polyethylene.
Further, when a hollow fiber membrane is used as the filtration membrane 11, its pore diameter (filtration accuracy), filtration area, film thickness, outer diameter and the like are not particularly limited, but for example, the pore diameter is 0.01 to 2 μm, filtration The area is 0.2 to 10 m ² , the film thickness is 5 to 300 μm, the outer diameter is 20 to 2000 μm, and the porosity is 20 to 90%.

  The raw water supply line 20 is branched at a branch point 21 into a first supply channel 21A and a second supply channel 21B. The first supply channel 21A and the second supply channel 21B are connected to the raw water inlets 12 and 12 of the membrane modules 10 and 10 via the on-off valves 40 and 40, respectively. The raw water supply line 20 includes a valve 22 that adjusts the water pressure of the raw water upstream of the branch point 21.

Here, the on-off valve, the membrane module, and the raw water inlet to which the first supply channel 21A is connected are referred to as the first on-off valve 40A, the first membrane module 10A, and the raw water inlet 12A, respectively.
On the other hand, the on-off valve, the membrane module, and the raw water inlet to which the second supply channel 21B is connected are referred to as a second on-off valve 40B, the second membrane module 10B, and the raw water inlet 12B, respectively.
Of the first supply channel 21A, the upstream channel 211A is from the branch point 21 to the first on-off valve 40A, and the downstream channel 212A is from the first on-off valve 40A to the raw water inlet 12A.
On the other hand, in the second supply flow path 21B, the section from the branch point 21 to the second on-off valve 40B is the upstream flow path 211B, and the section from the second on-off valve 40B to the raw water inlet 12B is the downstream flow path 212B.

The valve 22 is not particularly limited as long as the water pressure of the raw water can be adjusted, and a valve normally used in a water purifier such as a pressure reducing valve can be used.
The on-off valve 40 may be two two-way valves, but a three-way valve is preferable. The on-off valve 40 is controlled to open and close based on a control command from a control unit (not shown), and switches between supply and stop of raw water to the membrane module 10. The on-off valve 40 can be manually opened and closed to switch between supply and stop of raw water.

  The permeated water transfer line 30 branches at a branch point 31 into a first transfer channel 31A and a second transfer channel 31B. The first transfer channel 31A and the second transfer channel 31B are connected to the permeate outlets 13 and 13 of the first membrane module 10A and the second membrane module 10B, respectively.

  The backwash water discharge line 50 is branched at a branch point 51 into a first discharge channel 51A and a second discharge channel 51B. The first discharge channel 51A is connected to the downstream channel 212A via the first on-off valve 40A. On the other hand, the second discharge channel 51B is connected to the downstream channel 212B via the second on-off valve 40B.

The air supply / exhaust line 60 branches off at a branch point 61 into a first supply / exhaust flow path 61A and a second supply / exhaust flow path 61B. The first air supply / exhaust flow path 61A and the second air supply / exhaust flow path 61B are connected to the air supply / exhaust ports 14 and 14 of the first membrane module 10A and the second membrane module 10B, respectively. The air supply / exhaust ports 14 and 14 are preferably provided in the vicinity of the permeate outlets 13 and 13. The air supply / exhaust line 60 includes a valve 62 that controls supply / exhaust of air upstream from the branch point 61.
The valve 62 is not particularly limited as long as air supply / exhaust can be controlled, and a valve normally used in a water purifier such as an electromagnetic valve or an air vent can be used.

One end of the bypass line 70 is connected to the raw water supply line 20 via the valve 71, and the other end is joined to the permeate transfer line 30 on the downstream side of the branch point 31.
The valve 71 is not particularly limited as long as the flow direction of the raw water can be controlled, and a valve normally used in a water purifier such as a water stop valve can be used.

  In addition, in the water purifier 1 shown in FIG. 1, although two membrane modules are provided in parallel, the water purifier used for this invention is not limited to what is shown in FIG. 1, For example, the number of membranes according to the required amount of water You may use the water purifier with which the module was provided in parallel.

[how to drive]
Hereinafter, the operation method of the water purifier of the present invention will be described according to the operation using the water purifier 1 shown in FIG.
In the operation method of the cleaning apparatus of the present invention, the filtration step, the first backwashing step, and the second backwashing step are repeatedly performed.

  In the filtration step, the valve 22 is opened and the valve 62 is closed. Further, the valve 71 selects the raw water supply line 20, and the first on-off valve 40A selects the first supply channel 21A (that is, the upstream channel 211A and the downstream channel 212A communicate with each other). In addition, the second on-off valve 40B is opened so as to select the second supply channel 21B (that is, the upstream channel 211B and the downstream channel 212B communicate with each other).

  In the filtration step, raw water is supplied from the raw water supply line 20 to the first membrane module 10A and the second membrane module 10B via the first supply channel 21A and the second supply channel 21B. And filter the raw water. At this time, the water pressure in the raw water supply line 20 is adjusted by the valve 22. The water pressure is preferably about 0.1 to 0.3 MPa.

The raw water flows from the raw water inlet 12 of each membrane module, permeates through the filtration membrane 11 of the membrane module, becomes permeate, and is discharged from the permeate outlet 13. The permeated water discharged from the first membrane module 10A passes through the first transfer channel 31A, while the permeated water discharged from the second membrane module 10B passes through the second transfer channel 31B and reaches the branch point. At 31, the water is fed from the permeate transfer line 30 to a pipe (not shown) connected to each water tap.
In addition, in FIG. 1, the flow of raw | natural water and permeated water is shown by the arrow.

Next, after performing the filtration step for a predetermined time or after filtering a predetermined amount of raw water, each membrane module is back-washed as follows.
Here, the flow of raw water or the like during backwashing is shown by arrows in FIGS.

  In the first backwash process, the valve 22 is opened and the valve 62 is closed. Further, the valve 71 selects the raw water supply line 20, and the first on-off valve 40A selects the first supply channel 21A (that is, the upstream channel 211A and the downstream channel 212A communicate with each other). ) Each open. Then, the second on-off valve 40B switches so as to select the downstream flow path 212B and the second discharge flow path 51B (that is, the downstream flow path 212B and the second discharge flow path 51B communicate with each other).

  In the first backwashing step, the second on-off valve 40B is switched as described above, and the raw water is supplied from the raw water supply line 20 through the first supply passage 21A as shown in FIG. Supply only to 10A, and stop supply of raw water to the second membrane module 10B. At this time, the water pressure in the raw water supply line 20 is adjusted by the valve 22. The water pressure is preferably about 0.1 to 0.3 MPa.

The raw water flows from the raw water inlet 12A of the first membrane module 10A, passes through the filtration membrane 11 (11A) of the first membrane module 10A, becomes permeated water, and is discharged from the permeated water outlet 13 (13A). . All of the discharged permeated water is sent to the second membrane module 10B via the first transfer channel 31A and the second transfer channel 31B.
In order to send all the permeated water to the second membrane module 10B, for example, a valve (not shown) is installed in the permeated water transfer line 30 and the valve is closed.

The permeated water sent to the second membrane module 10B flows in from the permeated water outlet 13B of the second membrane module 10B and passes through the second membrane module 10B. At this time, dirt or the like accumulated in the filtration membrane 11 (11B) of the second membrane module 10B is washed away by the permeated water, and the second membrane module 10B is backwashed.
The permeated water containing dirt becomes backwash water and is discharged from the raw water inlet 12B. The backwash water passes through the downstream flow path 212B and the second discharge flow path 51B, and is discharged from the backwash water discharge line 50 to the outside of the system.

The backwashing time in the first backwashing process is preferably 30 to 90 seconds. If the backwash time is 30 seconds or longer, the second membrane module 10B can be sufficiently backwashed. On the other hand, if the backwash time is 90 seconds or less, the supply stop time to the water supply building can be shortened, and the amount of water used for washing can be reduced.
The backwash time can be set by a rotary switch (not shown).

After the first backwashing step described above is completed, the second backwashing step is subsequently performed.
In the second backwashing step, the valve 22 is opened and the valve 62 is closed. Further, the valve 71 is opened to select the raw water supply line 20. Then, the first on-off valve 40A selects the downstream flow path 212A and the first discharge flow path 51A (that is, the downstream flow path 212A and the first discharge flow path 51A communicate with each other). The on / off valve 40B is switched so as to select the second supply flow path 21B (that is, the upstream flow path 211B and the downstream flow path 212B communicate with each other).

  In the second backwashing step, the first on-off valve 40A and the second on-off valve 40B are switched as described above, and the raw water is supplied from the raw water supply line 20 to the second supply passage 21B as shown in FIG. Then, only the second membrane module 10B is supplied, and the supply of raw water to the first membrane module 10A is stopped. At this time, the water pressure in the raw water supply line 20 is adjusted by the valve 22. The water pressure is preferably about 0.1 to 0.3 MPa.

The raw water flows in from the raw water inlet 12B of the second membrane module 10B, passes through the filtration membrane 11B of the second membrane module 10B, becomes permeated water, and is discharged from the permeated water outlet 13 (13B). All of the discharged permeated water is sent to the first membrane module 10A via the second transfer channel 31B and the first transfer channel 31A.
In order to send all of the permeated water to the first membrane module 10A, it may be performed in the same manner as in the first backwashing step.

The permeate sent to the first membrane module 10A flows from the permeate outlet 13A of the first membrane module 10A and passes through the first membrane module 10A. At this time, dirt accumulated in the filtration membrane 11A of the first membrane module 10A is washed away by the permeated water, and the first membrane module 10A is backwashed.
The permeated water containing dirt becomes backwash water and is discharged from the raw water inlet 12A. The backwash water passes through the downstream flow path 212A and the first discharge flow path 51A and is discharged from the backwash water discharge line 50 to the outside of the system.

The backwashing time in the second backwashing process is preferably 30 to 90 seconds. If the backwash time is 30 seconds or more, the first membrane module 10A can be sufficiently backwashed. On the other hand, if the backwash time is 90 seconds or less, the supply stop time to the water supply building can be shortened, and the amount of water used for washing can be reduced.
The backwash time can be set by a rotary switch (not shown).

After the second backwashing process is completed, the process may be directly transferred to the filtration process. However, in order to backwash each membrane module more effectively, the first backwashing process and the second backwashing process are performed. It is preferable to repeat.
As for the number of repetitions, it is preferable that the first backwashing step and the second backwashing step are one set, and 2 to 10 sets are repeated.
The first backwashing step and the second backwashing step may be performed in the reverse order.

Moreover, it is preferable that the operating method of the water purifier of this invention performs the raw | natural water discharge process and raw | natural water filling process which are shown below immediately before a 1st backwash process and a 2nd backwash process.
Here, FIG. 4 shows the flow of raw water and the like during the raw water discharging step by arrows, and FIG. 5 shows the flow of raw water and the like during the raw water filling step by arrows.

  In the raw water discharging step, the valve 62 is opened. The valve 22 may be open or closed. Further, the valve 71 may be opened so as to select the raw water supply line 20 or may be opened so as to select the bypass line 70. The first on-off valve 40A selects only the downstream flow path 212A and the first discharge flow path 51A (that is, the downstream flow path 212A and the first discharge flow path 51A communicate with each other). The second on-off valve 40B is switched so that only the downstream flow path 212B and the second discharge flow path 51B are selected (that is, the downstream flow path 212B and the second discharge flow path 51B communicate with each other).

In the raw water discharging step, the first on-off valve 40A and the second on-off valve 40B are switched as described above, and the supply of raw water to each membrane module is stopped as shown in FIG.
Then, air is taken in from the air supply / exhaust line 60, and air is taken into the first membrane module 10A and the second membrane module 10B via the first supply / exhaust channel 61A and the second supply / exhaust channel 61B.
By taking air into each membrane module, the raw water staying in the membrane module is discharged from the raw water inlet 12. The raw water discharged from the first membrane module 10A passes through the downstream flow channel 212A and the first discharge flow channel 51A, while the raw water discharged from the second membrane module 10B flows into the downstream flow channel 212B and the second discharge channel. It passes through the flow path 51B, merges at the branch point 51, and is discharged out of the system from the backwash water discharge line 50.

The discharge time in the raw water draining process is preferably 15 to 60 seconds. If the drainage time is within the above range, the raw water can be sufficiently discharged from each membrane module.
The drainage time can be set by a rotary switch (not shown).

After the raw water discharge process described above is completed, the raw water filling process is subsequently performed.
In the raw water filling step, the valves 22 and 62 are opened. Further, the valve 71 is opened to select the raw water supply line 20. The first on-off valve 40A selects the first supply passage 21A (that is, the upstream passage 211A and the downstream passage 212A communicate), and the second on-off valve 40B Switching is performed so that the supply flow path 21B is selected (that is, the upstream flow path 211B and the downstream flow path 212B communicate with each other).

  In the raw water filling step, as described above, the first on-off valve 40A and the second on-off valve 40B are switched, and as shown in FIG. Raw water is supplied (filled) to the first membrane module 10A and the second membrane module 10B via the supply flow path 21B. At this time, the water pressure in the raw water supply line 20 is adjusted by the valve 22. The water pressure is preferably about 0.1 to 0.3 MPa.

  The raw water flows from the raw water inlet 12 of each membrane module, fills each module with the raw water, and at the same time, air in each module is discharged from the air supply / exhaust port 14. Air exhausted from the first membrane module 10A passes through the first air supply / exhaust flow path 61A, while air exhausted from the second membrane module 10B passes through the second air supply / exhaust flow path 61B to branch off. At 61, they are discharged from the air supply / exhaust line 60 to the outside of the system, and each module can be filled with raw water. At this time, for example, by installing a valve (not shown) in the permeate transfer line 30 and closing the valve, the raw water passes through the filtration membrane 11 of each membrane module, and the permeate is discharged from the permeate outlet 13. Can be suppressed.

The discharge time in the raw water filling step is preferably 5 to 20 seconds. If the filling time is within the above range, each membrane module can be sufficiently filled with raw water.
The filling time can be set by a rotary switch (not shown).

After the raw water filling process is completed, a first backwash process and a second backwash process are performed. That is, it is preferable to repeat in order of the filtration step, the raw water discharging step, the raw water filling step, the first backwashing step, the raw water discharging step, the raw water filling step, and the second backwashing step.
In addition, before shifting to a filtration process from a 2nd backwashing process as mentioned above, when repeating a 1st backwashing process and a 2nd backwashing process, according to the repetition frequency, a raw water discharge process and a raw water The filling step is preferably performed before each backwashing step.

  In this way, by performing the raw water discharging step immediately before the first backwashing step and the second backwashing step, it is possible to remove dust and the like accumulated on the bottom of the membrane module. Furthermore, by performing the raw water filling step, pressure is uniformly applied to the filtration membrane of the membrane module. When backwashing is performed in this state, dirt and the like accumulated on the filtration membrane can be washed away more effectively.

  In the operation method of the water purification apparatus of the present invention, the means for controlling switching from filtration to backwashing is not particularly limited, and may be switched manually, or an automatic control means is provided in the water purification apparatus, and automatic control is performed. You may switch. By the automatic control, for example, the first backwashing process and the second backwashing process can be performed when the water purifier is activated or at midnight.

  Also, as shown in FIG. 1, if the water purifier is provided with a bypass line 70 and can be switched from the raw water supply line 20 to the bypass line 70, when filtration is not necessary, the valve 71 switches to the bypass line 70, The raw water can be transferred to the permeate transfer line without going through the membrane module, and can be supplied to the pipe connected to each water tap. Furthermore, if it is set to switch from the raw water supply line 20 to the bypass line 70 at the time of a power failure or the like, normal water supply can be performed by automatic control.

  In addition, in the water purifier 1 shown in FIG. 1, although the raw | natural water permeate | transmits from the outer side of the filtration membrane 11 and is filtered, the membrane module which employ | adopted what is called an out-in system is used, but this invention is used for this. It is not limited, For example, you may use the membrane module which employ | adopted what is called an in-out system with which raw | natural water permeate | transmits from the inner side to the outer side and is filtered.

  As described above, according to the present invention, when the raw water is filtered, the filtration is performed in all the membrane modules, so that the filtration capacity is high. Therefore, since a sufficient amount of permeated water can be supplied (water supply), the water purifier can be made compact. Furthermore, when the membrane module is backwashed, all of the permeated water obtained by the membrane module that is not backwashed is used for backwashing, that is, the permeated water supply by filtration and backwashing are not performed at the same time. An amount of permeated water can be stably supplied.

INDUSTRIAL APPLICABILITY The water purifier of the present invention and the operation method thereof are useful when treating tap water having high turbidity, that is, tap water having a clogging degree in the range of 20 to 70, which is an index representing turbidity of tap water. It is. Among them, particularly remarkable effects are shown when processing tap water having higher turbidity, that is, tap water having a clogging degree in the range of 40 to 70. Here, the degree of clogging is obtained by the following method.
Clogging degree: 100- (filtration flow rate after 10 minutes / initial filtration flow rate) × 100
(Filtration conditions)
Pressurized pressure: 100 KPa
Membrane area: 5.0 m ²
Flow rate: 5 mL / min The present invention is particularly remarkable when treating tap water in which the content of organic components in the clogging material filtered on the surface of the hollow fiber membrane is in the range of 60% to 90%. Show the effect. In addition, content of the said organic component is the value analyzed by 700 degreeC and the ashing method for 2 hours.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
[Example 1]
The tap water was filtered using the water purifier shown in FIG.
As the first membrane module 10A and the second membrane module 10B, a hollow fiber membrane (“MPOE050” manufactured by Mitsubishi Rayon Co., Ltd., filtration area: 5.0 m ² , filtration accuracy as a filtration membrane) : 0.1 μm, film thickness: 55 μm, outer diameter: 380 μm).
As the valve 22, a pressure reducing valve (size: 20A) was used, and the maximum value of the working pressure was set to 0.8 MPa, and the secondary pressure was set to 0.15 MPa.
As the first on-off valve 40A and the second on-off valve 40B, an electric three-way valve (size: 20A, operating voltage: DC 24V) was used.
As the valve 62, an electromagnetic valve (size: 8A, operating voltage: DC24V) was used.
As the valve 71, a water stop valve (size: 20A) was used.
Further, a check valve (not shown) and a bypass valve (not shown) were installed in the permeate transfer line 30 and the bypass line 70, respectively.

Each valve was switched by automatic control, and the conditions of each process were set as shown below.
The supply amount of the raw water (tap water) was set to 18 L / min, and the valve 22 was adjusted so that the water pressure of the raw water in the raw water supply line 20 was 0.15 MPa.
The backwashing time of the first backwashing process and the second backwashing process was set to 45 seconds, the discharging time of the raw water discharging process was set to 30 seconds, and the filling time of the raw water filling process was set to 10 seconds.

Then, after starting the operation of the water purification device, the raw water discharging step, the raw water filling step, the first back washing step, the raw water discharging step, the raw water filling step, and the second back washing step are repeated twice in this order, and then the filtration step It was moved to. Then, when the cleaning time set by the timer by automatic control was reached, switching from filtration to backwashing was performed (that is, opening and closing of each valve was switched by automatic control). And after repeating twice in order of a raw | natural water discharge process, a raw | natural water filling process, a 1st backwash process, a raw | natural water discharge process, a raw | natural water filling process, and a 2nd backwash process, it was made to transfer to the filtration process. This operation was repeated for 2 months, and tap water was filtered.
As a result, a sufficient and constant amount of permeated water could be stably supplied (water supply). In addition, as a result of measuring the clogging degree of raw | natural water (tap water), it was in the range of 40-60.
Further, after completion of the operation, clogging substances on the surface of the hollow fiber membrane were collected and analyzed for organic components by an ashing method at 700 ° C. for 2 hours. As a result, 60% of the clogging substances were organic components. It was.

After installing the water purifier in the previous period and operating the water purifier, the flow rate retention rate at the beginning and end of the operation was measured and found to be 92%. However, the flow rate retention is defined by the following equation.
Flow rate retention: (End flow rate / Initial flow rate) x 100

[Example 2]
A water purification apparatus similar to that in Example 1 was installed, and the operation was performed in the same manner as in Example 1 except that the raw water discharging process and the raw water filling process were not performed. The tap water was filtered. As a result, a sufficient and constant amount of permeated water could be stably supplied (water supply). In addition, as a result of measuring the flow rate retention at the beginning and the end of the operation, it was 33%.

  According to the present invention, it is possible to provide a water purifier that is compact and has a high filtering capacity and that can stably supply a certain amount of permeated water and an operation method thereof.

  1: Water purifier, 10: Membrane module, 20: Raw water supply line, 30: Permeate transfer line, 40: On-off valve, 50: Backwash water discharge line, 60: Air supply / exhaust line, 70: Bypass line.

Claims (3)

Raw water supply line,
A plurality of membrane modules provided in parallel to filter raw water;
A plurality of supply channels branched from the raw water supply line and connected to the raw water inlet of each membrane module;
An on-off valve provided in each of the supply channels;
A backwash water discharge line connected to the on-off valve;
A permeate transfer line;
A plurality of transfer channels branched from the permeate transfer line and connected to the permeate outlet of each membrane module;
Water purifier with A method of operating a water purification apparatus comprising a plurality of membrane modules provided in parallel for filtering raw water, and a plurality of on-off valves for switching supply and stop of the raw water to the membrane modules,
A filtration step of switching the on-off valve to supply raw water to all of the membrane modules, and filtering the raw water;
Among the membrane modules, raw water was supplied to a part of the membrane modules (A), and the on-off valves were switched so as to stop the supply of raw water to the remaining membrane modules (B), and the membrane modules (A) were permeated. A first backwashing step of sending all permeated water to the membrane module (B) and backwashing the membrane module (B);
The supply of raw water to the membrane module (A) is stopped, the on-off valve is switched to supply raw water to the membrane module (B), and all the permeated water that has passed through the membrane module (B) is transferred to the membrane module (A). A second backwashing step of backwashing the membrane module (A);
How to operate the water purifier.   Immediately before the first backwashing step and the second backwashing step, the on-off valve is switched so as to stop the supply of raw water to all of the membrane modules, air is taken into the membrane modules and the raw water is discharged. The operation method of the water purification apparatus of Claim 2 which performs a raw | natural water discharge process and the raw | natural water filling process which switches an on-off valve so that raw water is supplied to all the membrane modules, and supplies and fills all the membrane modules with raw water.

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