JP2011177654A - Filtration apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration apparatus capable of easy construction of the apparatus having a desired processing capability while reducing the load for the equipment for backwashing. <P>SOLUTION: A first filtration unit 2A and a second filtration unit 2B for membrane filtration of raw water each include a connecting line 23 for connecting an MF membrane module 3 and an RO membrane module 5, and a backwashing line 31 for supplying filtered water through the MF membrane module 3 to the secondary side of the MF membrane module 3. The backwashing lines 31 in both of the first filtration unit 2A and the second filtration unit 2B are so connected to each other via a backwashing connecting line 37 that, when the second filtration unit 2B is backwashed, for example, the filtered water through the MF membrane module 3 of the first filtration unit 2A is supplied to the second filtration unit 2B via the backwashing connecting line 37. As a result, the load for the equipment for the backwashing can be reduced compared to the case where both of the first filtration unit 2A and the second filtration unit 2B each have an independent backwashing line 31. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a filtration apparatus for obtaining a filtrate by filtering a stock solution with a membrane such as a microfiltration membrane or an ultrafiltration membrane.

  Membrane filtration apparatuses using membrane modules such as microfiltration membranes and ultrafiltration membranes are known. In order to eliminate clogging of the membrane module, the membrane filtration apparatus performs backwashing in which the membrane is washed by causing the filtrate to flow backward from the secondary side to the primary side of the membrane module. For example, Patent Document 1 describes that backwashing is performed in an external pressure hollow fiber membrane module. In the case of a membrane filtration apparatus equipped with this type of membrane module, usually the filtrate is stored in a backwash tank or the like, and the filtrate stored in the backwash tank is supplied to the secondary side of the membrane module. Is done.

JP-A-9-220446

  However, in the conventional membrane filtration apparatus that requires a backwash tank and a backwash pump, the occupied area in the site tends to be large, and it is difficult to effectively construct the water treatment capacity in the predetermined site. In particular, in membrane filtration devices that perform secondary treatment of filtered water pretreated with a microfiltration membrane with a reverse osmosis membrane, the configuration of piping associated with the installation of backwash tanks and backwash pumps is complicated and complicated. As a result, the number of valves for opening and closing the flow path increased, resulting in an increase in equipment load.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a filtration device that facilitates the construction of a device having a desired processing capacity while reducing the equipment load for backwashing. And

  The present invention includes a filtration unit in which a plurality of pre-stage membrane modules having a pre-stage membrane for filtering a stock solution, and a post-stage membrane module having a post-stage membrane having a higher membrane separation performance than the pre-stage membrane, In the filtration device that filters the filtrate discharged from the front membrane module through the rear membrane module, the filtration device includes a plurality of filtration units, and the filtration unit includes a secondary side of the front membrane module and a primary side of the rear membrane module. Are connected to the flow line of the filtrate, and are provided in the communication line, and are fed from the filtrate pressure feed pump that feeds the filtrate while maintaining the suction side pressure at the set pressure, and the filtrate pressure feed pump. A backwash line connecting the downstream side where the filtrate flows and the secondary side of the front membrane module, and each backwash line of each of the plurality of filtration units. They are communicated with each other through a backwash communication line through which the filtrate flows, and during backwashing, the filtrate discharged from the front membrane module of the filtration unit other than the backwash target is filtered through the backwash communication line. The unit is supplied to the unit.

In the present invention, the filtrate discharged from the front membrane module is pumped by the filtrate pump. Here, for example, if the connection between the upstream membrane module and the filtrate pumping pump is continuously performed without cutting off with an intermediate tank or the like, the balance is lost between the suction side and the discharge side of the filtrate pumping pump. In addition, cavitation may occur on the suction side of the filtrate pump. However, the filtrate pump according to the present invention pumps the filtrate from the front membrane module while maintaining the suction side pressure at the set pressure, and thus can effectively prevent the occurrence of cavitation. An intermediate tank or the like for pumping the liquid becomes unnecessary. Furthermore, in the present invention, since the filtrate pump is also used for the function of transferring the backwash liquid, it is not necessary to provide a backwash pump separately, and the equipment burden is reduced.
Furthermore, in this invention, the filtrate discharged | emitted from the front | former membrane module of filtration units other than the backwash object passes along a backwash communication line as a backwash liquid, and is supplied to the filtration unit of the backwash object. Therefore, in each filtration unit, an independent backwash pipe dedicated to backwashing, a valve for opening and closing the flow path of these backwash pipes, etc. can be omitted, and instead each of the plurality of filtration units can share a backwash communication line. It becomes possible to perform backwashing alternately. As a result, it is easy to construct an apparatus having a desired processing capacity while reducing the equipment load for backwashing.

  Further, it is preferable that the front membrane is a microfiltration membrane and the rear membrane is a reverse osmosis membrane. The turbidity having a relatively large particle size in the stock solution is previously removed by a microfiltration membrane, so that the life of the reverse osmosis membrane can be extended.

  Furthermore, it is preferable that the filtration unit includes a plurality of front-stage membrane modules, and the number of front-stage membrane modules in each filtration unit is the same. When the number of pre-stage membrane modules in the filtration unit other than the backwash target is larger than the pre-membrane module in the filtration unit to be backwashed, the filtration used for backwashing according to the number of pre-membrane modules to be backwashed It is necessary to reduce the liquid flow rate. However, according to the above-described configuration, the number of pre-stage membrane modules in each of the filtration units is the same, so that control such as adjustment of the flow rate of the filtrate during backwashing is simplified and effective in realizing a simple configuration. .

  ADVANTAGE OF THE INVENTION According to this invention, construction | assembly of the apparatus which has desired processing capacity becomes easy, reducing the equipment load for backwashing.

It is a figure showing typically the filtration device concerning the embodiment of the present invention. It is a perspective view of the filtration device concerning this embodiment. It is sectional drawing along the III-III line of FIG. It is sectional drawing along the IV-IV line of FIG. It is a figure which shows typically the functional structure of an operation panel. It is a flowchart which shows the procedure which concerns on the filtration process of the filtration apparatus which concerns on this embodiment. It is a figure which shows the flow of the fluid at the time of filtration operation. It is a figure which shows the flow of the fluid at the time of the backwash operation of a 2nd filtration unit. It is a figure which shows the flow of the fluid at the time of the backwash operation of a 1st filtration unit. It is a figure which shows the flow of the fluid of the flushing process of a 1st, 2nd unit. It is a figure which shows typically the filtration apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows typically the filtration apparatus which concerns on 3rd Embodiment of this invention.

  Hereinafter, a filtration device according to a preferred embodiment of the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 5, the filtration device 1 </ b> A is a device that receives raw water (raw solution) such as domestic wastewater, industrial water, factory wastewater, or river water, and purifies it by membrane filtration. The filtration apparatus 1A includes a plurality of filtration units 2A and 2B, and a plurality of MF membrane modules 3 and a plurality of RO membrane modules 5 are incorporated in the filtration units 2A and 2B, respectively. The raw water received by the filtration units 2A and 2B is first supplied to the MF membrane module 3 to remove turbidity having a relatively large particle size, and then supplied to the RO membrane module 5 for secondary treatment. Is done. The filtration units 2 </ b> A and 2 </ b> B realize a transportable mode by accommodating a plurality of MF membrane modules 3 and a plurality of RO membrane modules 5 in a container 7.

  The filtration device 1A according to the present embodiment includes two filtration units 2A and 2B. One filtration unit (hereinafter referred to as “first filtration unit”) 2A and the other filtration unit (hereinafter referred to as “second”). 2B) is provided with the same elements. In the following description, the first filtration unit 2A will be mainly described in detail, and a part of the description of the second filtration unit 2B will be omitted.

  The first filtration unit 2 </ b> A includes a container 7 that houses the MF membrane module 3 and the RO membrane module 5. The container 7 is a box-shaped marine container 7 that is usually used for freight transportation, and is composed of a flat base 7a disposed at the bottom of the container 7 and a lid portion 7b attached to the base 7a. It has a shape. A door is provided at one end of the lid portion 7b in the longitudinal direction. Each length of the container 7 can be about 6 m (20 feet) or 12 m (40 feet).

  The first filtration unit 2A includes a plurality of MF membrane modules 3. The MF membrane module 3 includes an MF membrane (microfiltration membrane) 3a made of a hollow fiber membrane and a substantially cylindrical case 3a that accommodates a bundle of a large number of MF membranes 3a. The case 3a is fixed to the case 3a via an adhesive layer provided near both ends.

  The MF membrane module 3 is divided into a primary side region UA and a secondary side region DA across the MF membrane 3a, the primary side is an upstream side region UA that receives raw water, and the secondary side is This is the downstream area DA that is the destination of the filtered water that has passed through the MF membrane 3a. And the raw | natural water introduction part 3c connected to the primary side is provided in one edge part of the MF membrane module 3. FIG. The other end of the MF membrane module 3 is discharged with the filtered water discharge portion 3d communicating with the secondary side and the raw water and backwash water that communicated with the primary side and did not pass through the MF membrane 3a. And a cleaning water discharge portion 3e.

  The plurality of MF membrane modules 3 are installed in the same number of two groups. In the present embodiment, a total of 14 MF membrane modules 3 are divided into seven, and a plurality of MF membrane modules 3 belonging to each group are arranged in two rows. The number of MF membrane modules 3 and the like can be appropriately selected according to the desired water treatment capacity, the size of the container 7, and the like.

  The explanation will focus on the MF membrane module 3 belonging to one group. The MF membrane module 3 is erected between the filtered water discharge header pipe 9 arranged on the upper side and the raw water introduction header pipe 11 arranged on the lower side. Has been. The raw water introduction header pipe 11 is installed along the lower side of the container 7, that is, along the base 7a. The raw water introduction header pipe 11 is provided with a plurality of branch pipes corresponding to the number of the MF membrane modules 3, and the raw water introduction section 3c of the MF membrane module 3 is connected to the branch pipe of the raw water introduction header pipe 11 via a joint pipe. It is connected to the.

  The filtered water discharge header pipe 9 is installed on the upper side of the container 7, that is, along the ceiling of the lid portion 7b. The filtrate water discharge header pipe 9 is provided with a plurality of branch pipes corresponding to the number of the MF membrane modules 3, and the filtrate water discharge section 3d of the MF membrane module 3 is connected to the filtrate water discharge header pipe 9 via a joint pipe. Connected to the branch pipe.

  Further, on the upper side of the MF membrane module 3, a washing water discharge header pipe 13 is installed side by side with the filtrate water discharge header pipe 9. The cleaning water discharge header pipe 13 is provided with a plurality of branch pipes corresponding to the number of the MF membrane modules 3, and the cleaning water discharge section 3e of the MF membrane module 3 is connected to the cleaning water discharge header pipe via the joint pipe. It is connected to 13 branch pipes.

  As shown in FIGS. 1, 2 and 4, the RO membrane module 5 includes an RO membrane (reverse osmosis membrane) 5 a and a substantially cylindrical case in which a plurality of RO membranes 5 a are accommodated in a line (“ 5b). The RO membrane module 5 is divided into a primary region UA and a secondary region DA with the RO membrane 5a interposed therebetween. The primary side is an upstream area UA that receives the filtrate, and the secondary side is a downstream area DA that is an outflow destination of secondary permeated water that has passed through the RO membrane 5a.

  One end of the RO membrane module 5 is provided with a filtrate introduction part 5c that communicates with the primary side, and the other end has a permeate discharge part 5d that communicates with the secondary side, A concentrated water discharge part 5e communicating with the next side is provided. From the concentrated water discharge part 5e, the filtered water that has not permeated the RO membrane 5a is discharged.

  The plurality of RO membrane modules 5 are fixed to the gantry 15 in a state of being laid along the longitudinal direction of the container 7. Various forms of connection between the plurality of RO membrane modules 5 can be employed, but the plurality of RO membrane modules 5 according to the present embodiment are connected in multiple stages. More specifically, four RO membrane modules 5 are arranged in the first stage, two RO membrane modules 5 are arranged in the second stage, and one RO membrane module 5 is arranged in the third stage. Is arranged.

  In the first-stage RO membrane module 5, the filtrate introduction part 5 c is connected to the upstream header pipe 17, and the permeate discharge part 5 d is connected to the downstream header pipe 19. The filtrate introduction section 5c of the second stage RO membrane module 5 communicates with the concentrated water discharge section 5e of the first stage RO membrane module 5, and the permeate discharge section 5d is connected to the downstream header pipe 19. Yes. The filtrate introduction section 5c of the third-stage RO membrane module 5 communicates with the concentrated water discharge section 5e of the second-stage RO membrane module 5, and the permeate discharge section 5d is connected to the downstream header pipe 19. Yes. Moreover, the concentrated water discharge part 5e of the RO membrane module 5 of the 3rd stage is connected to the pipe line which discharges filtered water. By setting it as such a connection aspect, it becomes possible to increase the flow volume of secondary permeated water.

  Next, the configuration of the piping of the filtration device 1A will be described with reference to FIG. In FIG. 1, one of the plurality of MF membrane modules 3 divided into two groups is shown as a representative, and one of the MF membrane modules 3 is shown as a representative. Yes. Furthermore, one of the plurality of RO membrane modules 5 is shown as a representative.

  The first filtration unit 2A of the filtration device 1A is provided with an introduction line 21 for receiving raw water from a raw water storage tank (not shown). The introduction line 21 includes a pipe line 21a having a predetermined pipe diameter. The pipeline 21 a of the introduction line 21 branches in two directions, and each branch portion is connected to the raw water introduction header pipe 11 that communicates with the MF membrane module 3.

The introduction line 21 is provided with an MF liquid feed pump (raw liquid supply pump) 21b, and raw water is supplied to the MF membrane module 3 at a predetermined flow rate by the MF liquid feed pump 21b. Each branch portion of the introduction line 21 is provided with a _first valve V1 that opens and closes the flow path. The first valve V ₁ can be an automatic control by an operation panel (control means) 41, for example, an electric valve assuming a sequence control, but is a manual valve when switching manually. Also good.

  The first filtration unit 2A is provided with a communication line 23 for connecting the MF membrane module 3 and the RO membrane module 5. The MF membrane module 3 and the RO membrane module 5 are connected via an intermediate tank or the like. Directly connected by the communication line 23.

  The communication line 23 includes pipe lines 23a and 23b having a predetermined pipe diameter, and an RO liquid feed pump (filtrate pressure feed pump) 23d that pumps filtered water to the RO membrane module 5 at a predetermined high pressure. The filtered water filtered by the membrane module 3 is directly supplied to the RO membrane module 5 by the RO liquid feed pump 23d.

The pipelines 23a and 23b of the communication line 23 are divided into an upstream pipeline 23a and a downstream pipeline 23a with the RO liquid feed pump 23d interposed therebetween. The upstream pipe line 23a is branched in two directions corresponding to the MF membrane modules 3 divided into two groups, and each branch portion is a filtrate drain header that communicates with the MF membrane module 3. Each is connected to a tube 9. Each branch portion is provided with a _second valve V2 for opening and closing the flow path. The second valve V _2, the operation panel automatic control by the (control means) 41, for example, the sequence control can be employed such as an electric valve assumes, when performing switching of manually, there manually valve May be.

  Further, the upstream side pipe line 23a is provided with a flow meter 23e for measuring the flow rate of the filtered water flowing in the pipe line. The downstream end of the upstream pipe 23a is connected to the suction part of the RO liquid pump 23d, and the pressure on the suction side of the RO liquid pump 23d is set near the suction part of the RO liquid pump 23d. A pressure sensor 23f for detection is provided.

The downstream line 23 a of the communication line 23 has an upstream end connected to the discharge portion of the RO liquid feeding pump 23 d and a downstream end connected to the upstream header pipe 17 that communicates with the RO membrane module 5. Further, the downstream side pipe line 23a is provided with a _third valve V3 for opening and closing the flow path. The third valve V ₃ may be an electric valve or the like assuming automatic control by the operation panel (control means) 41, for example, sequence control. However, when performing manual switching, the third valve V ₃ is a manual valve. May be.

The first filtration unit 2A is provided with a backwash water discharge line 25 for discharging backwash water or raw water from the MF membrane module 3. The backwash water discharge line 25 includes a pipe line 25a having a predetermined pipe diameter. The upstream pipe line of the backwash water discharge line 25 branches in two directions, and each branch part is connected to a wash water discharge header pipe 13 that communicates with the primary side of the MF membrane module 3. Each branch portion is provided with a _fourth valve V4 that opens the flow path. The downstream side of the backwash water discharge line 25 communicates with a waste liquid tank (not shown). In the case of backwashing, the backwashing water flows and is discharged through the backwashing water discharge line 25, but in the flushing process, the raw water flows and is discharged.

  Further, the first filtration unit 2A has a permeated water discharge line 27 for discharging the secondary permeated water that has passed through the RO membrane module 5, and a concentrated water discharge that communicates the primary side of the RO membrane module 5 with the waste liquid tank 30. Line 29 is provided.

The permeate discharge line 27 communicates with the secondary side of the RO membrane module 5 via the downstream header pipe 19. Permeate discharge line 27 comprises a pipe 27a having a given tube diameter, a flow meter 27b for measuring the flow rate of the secondary permeate flowing in conduit 27a, a valve V ₅ of the fifth opening and closing the flow path Have Valve V ₅ of the fifth automatic control by the operation panel, for example, the sequence control can be employed such as an electric valve assumes, when performing switching of the manual may be a manual valve. The secondary permeated water filtered by the RO membrane module 5 is sent out of the container 7 through the permeated water discharge line 27.

  The concentrated water discharge line 29 includes a pipe line 29a having a predetermined pipe diameter. The conduit 29a of the concentrated water discharge line 29 is connected to the concentrated water discharge part 5e of the RO membrane module 5 at the third stage (final stage), and as a result, communicates with the primary side of the RO membrane module 5. The mode which performs is realized. In the RO membrane modules 5 arranged in multiple stages, the concentrated water that has not permeated any RO membrane 5a is discharged to the concentrated water discharge line 29 via the concentrated water discharge portion 5e of the third-stage RO membrane module 5. The

  The concentrated water discharge line 29 is provided with a control valve Va capable of adjusting the flow path to a predetermined opening degree. During the filtration operation, the flow rate of the secondary permeate flowing out from the RO membrane module 5 slightly increases when the opening degree is reduced by the control valve Va, and the flow rate of the permeate decreases slightly when it is opened. Therefore, the flow rate of the secondary permeated water can be finely adjusted by adjusting the opening degree by the control valve Va. Further, a flow meter 29b for detecting the flow rate of the liquid flowing in the conduit 29a is provided on the downstream side of the control valve Va as necessary.

The first filtration unit 2 </ b> A is provided with a backwash line 31 that branches from the communication line 23 and indirectly communicates with the secondary side of the MF membrane module 3. The backwash line 31 includes a pipe line 31a having a predetermined pipe diameter. The pipe 31a of the backwash line 31 is connected to the downstream side pipe 23a of the communication line 23 at the upstream end where the filtrate flows, and the connecting part is connected to the discharge part of the RO liquid feed pump 23d and the third part. It is provided between the valve V _3. Further, the downstream end is connected to the upstream pipe line 23a of the communication line 23, and the connection part is provided between the suction part of the RO liquid feeding pump 23d and the flow meter 23e.

Further, in the backwash line 31, a sixth valve V ₆ and the seventh valve V ₇ for opening and closing the flow path in the conduit 31a is provided. The configuration of the backwash line 31 described above embodies a mode in which the downstream side where the filtered water discharged from the RO liquid feed pump 23d flows and the secondary side of the MF membrane module 3 are communicated.

  The first filtration unit 2 </ b> A includes a high-pressure air supply unit 33 that supplies compressed air for air scrubbing to the MF membrane module 3. The high-pressure air supply unit 33 includes a compressor (not shown) that sends out compressed air, and a high-pressure air supply pipe 33 a that supplies the compressed air sent out by the compressor to the primary side of the MF membrane module 3.

The downstream portion of the high-pressure air supply pipe 33a branches into a plurality of branch pipes corresponding to the number of MF membrane modules 3. Each branch pipe of the high-pressure air supply pipe 33a is connected to the lower part of the MF membrane module 3 so as to communicate with the primary side of each of the plurality of MF membrane modules 3. The high-pressure air supply pipe 33a is provided with an _eighth valve V8 that opens and closes a branch passage that communicates with the MF membrane module 3 side. Valve V ₈ The eighth automatic control by the operation panel, for example, the sequence control can be employed such as an electric valve assumes, when performing switching of the manual may be a manual valve.

  The first filtration unit 2A includes, for example, a chemical tank such as an NaOH storage tank 35a, a scale inhibitor storage tank 35b, a reducing agent storage tank 35c, and an NaClO storage tank 35d, and a liquid feed pump (not shown) corresponding to each of the chemical liquid tanks 35a to 35d. ) And prepared. The SBS (sodium bisulfite) stored in the reducing agent storage tank 35 c and the scale inhibitor stored in the scale inhibitor storage tank and the scale inhibitor are used when the RO membrane module 5 is washed. The NaClO solution stored in the NaClO storage tank 35d is used when the MF membrane module 3 is back-washed.

  Although the piping configuration in the first filtration unit 2A has been described above, the second filtration unit 2B has the same configuration. The backwash line 31 of the first filtration unit 2 </ b> A and the backwash line 31 of the second filtration unit 2 </ b> B communicate with each other via a backwash communication line 37.

The backwash communication line 37 includes a pipe line 37a having a predetermined pipe diameter. One end of the conduit 37a is connected to the conduit 31a of the backwash line 31 of the first filtration unit 2A, and the other end is connected to the conduit 31a of the backwash line 31 of the second filtration unit 2B. ing. The connection portion between the conduit 31a of the backwash line 31 of the conduit 37a and the first filter unit 2A backwash contact line 37 is situated between the sixth valve V ₆ with the seventh valve V ₇ Similarly, the connection portion between the conduit 31a of the backwash line 31 of the conduit 37a and the second filtering unit 2B of the backwash contact line 37, between the sixth valve V ₆ with the seventh valve V ₇ It is.

The pipe 37a of the backwash communication line 37 is provided with a _ninth valve V9 that opens and closes the flow path in order to release the pressure applied to the pipe 37a. The ninth valve V ₉ may be an electric valve or the like assuming automatic control by the operation panel, for example, sequence control, but may be a manual valve when performing manual switching.

  In addition to the normal filtration operation, the filtration device 1A includes an operation panel 41 that performs opening / closing control of a flow path for performing a backwash operation. The operation panel 41 includes a control CPU (Central Processing Unit), a storage device (Strage Unit), an input device (Input Device), an output device (Output Device), and the like, and operates according to a predetermined program. The valve control unit 43, the MF pump control unit 45, the RO pump control unit 47, the secondary permeate water control unit 49, and the backwash control unit 50 are realized (see FIG. 5).

  The operation panel 41 according to the present embodiment is provided in both the first filtration unit 2A and the second filtration unit 2B, and the operation panel 41 on the first filtration unit 2A side and the operation panel 41 on the second filtration unit 2B side. Are connected to each other by wire or wireless so that control signals can be transmitted and received. In addition, as an aspect which embodies this invention, it is not limited to the aspect which provides the operation panel 41 in each of the 1st filtration unit 2A and the 2nd filtration unit 2B, either the 1st filtration unit 2A or the 2nd filtration unit 2B The operation panel 41 may be provided only on one side, and the operation panel 41 may perform unified control of both the first filtration unit 2A and the second filtration unit 2B. In the present embodiment, for example, the operation panel 41 on the first filtration unit 2A side has the valve control unit 43, the MF pump control unit 45, the RO pump control unit 47, and the secondary permeate control unit 49 in the first filtration unit 2A. In this embodiment, it is assumed that all functions of the backwash control unit 50 are realized. However, a plurality of control devices (control means) may be arranged in a distributed manner so that each function is shared by each control device. .

  The operation panel 41 on the first filtration unit 2A side and the operation panel 41 on the second filtration unit 2B side perform substantially the same operation control during the filtration operation, and perform different operations while adjusting each other during the backwash operation. Execute control. Hereinafter, the operation panel 41 on the first filtration unit 2A side will be mainly described, and the description of the operation panel 41 on the second filtration unit 2B side will be omitted.

The operation panel 41 is connected to the first valve V ₁ , the second valve V ₂ , and the third valve V ₃ by wire or wireless so that control signals can be transmitted and received. When a control signal is transmitted from the operation panel 41 functioning as the valve control unit 43 to the first to third valves V _{1 to} V ₃ , the first to third valves V _{1 to} V ₃ accept the control signal. The first to third valves V _{1 to} V ₃ open or close the flow paths according to the received control signal.

  The operation panel 41 is connected to a flow meter 23e provided on the communication line 23 by wire or wirelessly, and is configured to be able to acquire flow rate data detected by the flow meter 23e. The operation panel 41 is connected by wire or wireless so that a control signal can be transmitted to and received from the MF liquid feeding pump 21b.

The operation panel 41 functioning as the MF pump control unit 45 monitors the flow rate data detected by the flow meter 23e, and the flow rate data is more than a predetermined threshold (for example, a certain error range centered on 25 m ³ / h). When the flow rate is low, the MF liquid feed pump 21b is operated at a high speed to increase the flow rate. When the flow rate data is higher than a predetermined threshold, the MF liquid feed pump 21b is operated at a low speed to decrease the flow rate. As a result, the MF pump control unit 45 performs automatic control to maintain the flow rate of the filtered water passing through the communication line 23 at a predetermined set flow rate. As a result, the raw water of the predetermined flow rate is supplied to the MF membrane module 3 and the second MF membrane. Supply to at least one of the modules 3. The flow rate setting of the filtrate water is executed by an input operation of the operation panel 41 by an operator or the like, and the operation panel 41 receiving the input operation sets and registers the input value in a memory or the like as a threshold value of the filtrate water flow rate.

  The operation panel 41 is connected to a pressure sensor 23f provided on the communication line 23 by wire or wirelessly, and is configured to be able to acquire pressure data detected by the pressure sensor 23f. The operation panel 41 is connected by wire or wireless so that control signals can be transmitted and received to the RO liquid pump 23d.

  The operation panel 41 functioning as the RO pump control unit 47 monitors the pressure data detected by the pressure sensor 23f, and the pressure data is lower than a predetermined threshold (for example, a certain error range centered on the water column 5m). In this case, the RO liquid feeding pump 23d is operated at a low speed to reduce the pressure feeding flow rate, and when the pressure data is higher than a predetermined threshold, the RO liquid feeding pump 23d is operated at a high speed to increase the pressure feeding flow rate. As a result, the RO liquid feed pump 23d controlled by the RO pump control unit 47 performs automatic control so as to maintain the pressure on the suction unit side at a predetermined set pressure. The pressure setting on the suction side of the RO liquid pump 23d is executed by an input operation of the operation panel 41 by an operator or the like, and the operation panel 41 that receives the input operation sucks the input value into the RO liquid pump 23d. Set and register in the memory or the like as the pressure threshold on the part side.

The operation panel 41 is connected to a flow meter 27b provided in the permeate discharge line 27 by wire or wirelessly, and is configured to be able to acquire flow rate data detected by the flow meter 27b. The operation panel 41 is connected to a flow meter 29b provided in the concentrated water discharge line 29 by wire or wirelessly, and is configured to be able to acquire flow rate data detected by the flow meter 29b. The operation panel 41 is connected by wire or wirelessly to a control signal to the control valve Va provided in the fifth valve V ₅ and the concentrated water discharge line 29 provided in the permeate discharge line 27 enables transmission and reception Has been.

  The operation panel 41 functioning as the secondary permeated water control unit 49 has flow data detected by the flow meter 27b of the permeated water discharge line 27 and flow data detected by the flow meter 29b of the concentrated water discharge line 29 as necessary. And monitoring. The operation panel 41 performs automatic control to hold the flow rate data detected by the flow meter 27b of the permeate discharge line 27 so that the flow rate becomes a predetermined set flow rate. The set flow rate of the secondary permeated water is executed by an input operation of the operation panel 41 by an operator or the like, and the operation panel 41 receiving the input operation sets the input value in a memory or the like as a threshold value of the flow rate of the secondary permeated water. sign up.

The operation panel 41 is connected to the sixth valve V ₆ and the seventh valve V ₇ provided in the backwash line 31 by wire or wireless so that control signals can be transmitted and received. The operation panel 41 is wired so that control signals can be transmitted to and received from the fourth valve V ₄ provided in the backwash water discharge line 25 and the eighth valve V ₈ provided in the high-pressure air supply unit 33. Or connected by radio.

The operation panel 41 functioning as the backwash control unit 50 includes the first valve V ₁ , the third valve V ₃ , the fifth valve V ₅ , and the sixth valve 2 when the first filtration unit 2A is a backwash target. The second valve unit is closed by closing the valve V ₆ and the ninth valve V ₉ and opening the second valve V ₂ , the fourth valve V ₄ , the seventh valve V ₇ and the eighth valve V _8. The filtered water supplied from 2B is received as backwash water. Further, the operation panel 41 supplies backwash water to the secondary side of the MF membrane module 3 to backwash the MF membrane 3a, and discharges the backwash water that has permeated through the MF membrane 3a from the backwash water discharge line 25. On the other hand, when the first filtration unit 2A is not subject to backwashing, the operation panel 41 has a third valve V ₃ , a fourth valve V ₄ , a fifth valve V ₅ , a seventh valve V ₇ , And the eighth valve V ₈ are closed, the first valve V ₁ , the second valve V ₂ , the sixth valve V ₆ , and the ninth valve V ₉ are opened, and the filtration from the MF membrane module 3 is performed. Water is fed into the backwash communication line 37.

  Next, a processing flow using the filtration device 1A according to the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart showing an operation procedure of the filtration device 1A. Moreover, FIG. 7 is a figure which shows the flow of the liquid in the state which is performing the filtration operation, and FIG. 8 is the figure which shows the flow of the liquid in the state which is performing the backwash process of the 2nd filtration unit 2B. FIG. 9 is a diagram showing the flow of the liquid in a state in which the first filtration unit 2A is backwashed. Moreover, FIG. 10 is a figure which shows the flow of the liquid in the state which has performed the flushing process to both the 1st filtration unit 2A and the 2nd filtration unit 2B.

When the filtration device 1A is operated, it is necessary to input a set value according to the processing capacity or required performance of the filtration device 1A as an initial setting. In this embodiment, for example, the normal filtration is 27 minutes, the MF membrane module 3 of the first filtration unit 2A is backwashed for 1 minute, the backwash of the MF membrane module 3 of the second filtration unit 2B is 1 minute, and the first The flushing process of the MF membrane module 3 of the first filtration unit 2A and the MF membrane module 3 of the second filtration unit 2B is performed for a total of 30 minutes, and an input operation for performing the operation is performed by the operator. . Furthermore, the set flow rate of the filtrate water is 25 m ³ / h, the set pressure on the suction side of the RO liquid pump 23 d is 5 m, and the set flow rate of the secondary filtrate is 20 m ³ / h. The

As shown in FIG. 6, when the raw water filtering process is started, the operation panel 41 starts a normal filtering operation (step S1). Here, the operation panel 41 (see FIGS. 1 and 7) opens the first valve V ₁ , the second valve V ₂ , the third valve V ₃ , and the fifth valve V _5, and opens the fourth valve V ₅ . The valve V ₄ , the sixth valve V ₆ , the seventh valve V ₇ , and the eighth valve V ₈ are closed. Through the valve control described above, the flow paths of the introduction line 21, the communication line 23, the permeate discharge line 27, and the concentrated water discharge line 29 are opened, and the backwash line 31, the backwash communication line 37, and the backwash are performed. The flow path of the water discharge line 25 is closed.

Next, the MF liquid feeding pump 21b is driven, and when the pressure data detected by the pressure sensor 23f reaches a predetermined pressure (water column 5m), the RO liquid feeding pump 23d is driven to supply filtered water to the RO membrane module 5. . Further, the opening degree of the control valve Va is finely adjusted so that the flow rate of the secondary permeated water discharged from the RO membrane module 5 maintains a predetermined set flow rate (20 m ³ / h).

The normal filtration operation will be described in more detail. In the filtering device 1A, MF-RO direct connection control such as flow rate control, pressure control, and flow rate control is performed. Specifically, the flow rate data of the filtrate water detected by the flow meter 23e is input to a control CPU (not shown) of the operation panel 41. The control CPU performs PID (Proportional Integral Derivative) calculation based on the flow rate data detected by the flow meter 23e, and performs inverter frequency control for the MF liquid feed pump based on the result. Thereby, the motor rotation speed control of the MF liquid feed pump 21b is executed, and the supply amount of raw water to the MF membrane module 3 varies. In addition, as PID calculation for inverter frequency control for MF liquid feed pumps, for example, output calculation based on a deviation from a set value can be mentioned, and in this embodiment, an output for maintaining the flow rate of filtered water at 25 m ³ / h. It is an operation.

  Further, the pressure data on the suction side of the RO liquid pump 23 d acquired by the pressure sensor 23 f is input to the control CPU of the operation panel 41. The control CPU performs PID calculation based on pressure data detected by the pressure sensor 23f, and performs inverter frequency control for the RO liquid pump. Thereby, the motor rotation speed control of the RO liquid feed pump 23d is executed, and the discharge amount of the RO liquid feed pump 23d varies. The PID calculation for controlling the inverter frequency for the RO liquid pump includes, for example, an output calculation based on a deviation from a set value. In this embodiment, the pressure on the suction side of the RO liquid pump 23d is maintained at the water column 5m. It is an output calculation for

Further, the flow rate data of the secondary filtrate detected by the flow meter 27 b provided in the permeate discharge line 27 is input to the control CPU of the operation panel 41. The control CPU performs PID calculation based on the flow rate data detected by the flow meter 27b, and controls the opening degree of the control valve Va based on the result. As a result, the flow rate of the concentrated water discharged from the RO membrane module 5 varies, and the flow rate of the secondary permeate varies accordingly. The PID calculation for controlling the opening degree of the control valve Va includes, for example, an output calculation based on a deviation from a set value. In this embodiment, the flow rate of the secondary permeated water is maintained at 20 m ³ / h. Output operation.

By performing the above MF-RO direct control, for example, when the MF membrane differential pressure is increased, the rotational speed of the MF liquid feed pump 21b is increased and the flow rate of the filtrate water is maintained at 25 m ³ / h. When the RO membrane differential pressure increases, the rotational speed of the RO liquid feed pump 23d increases and the flow rate of the secondary permeate is maintained at 20 m ³ / h (flow rate of concentrated water 5 m ³ / h). . Therefore, the state in which the pressure on the suction side of the RO liquid pump 23d is stable at the water column 5m (that is, the state where the pushing flow rate and the drawing flow rate of the RO liquid pump 23d are balanced) can be continued. Occurrence of cavitation on the suction side of the liquid feed pump 23d can be prevented.

  When the above-described filtration operation time (27 minutes) elapses, the filtration device 1A starts the alternating backwash operation between the first filtration unit 2A and the second filtration unit 2B. The first backwash target is the MF membrane module 3 of the second filtration unit 2B, and the MF membrane module 3 of the first filtration unit 2A is other than the backwash target.

When the backwash operation of the MF membrane module 3 of the second filtration unit 2B is started (step S2), the operation panel 41 of the first filtration unit 2A executes the backwash water supply control, while the second filtration unit 2B The operation panel 41 executes backwash water acceptance control. Specifically, the operation panel 41 (see FIGS. 1 and 8) of the first filtration unit 2A is closed third valve _{V 3} while continuing operation of the MF feeding pump 21b and RO feeding pump 23d and, opening the valve _{V 6} of the sixth. On the other hand, the operation panel 41 of the second filtration unit 2B closes the first valve V ₁ , the third valve V ₃ , the fourth valve V ₄ , and the seventh valve V ₇ , and the MF liquid feeding pump. The drive of 21b and RO liquid feed pump 23d is stopped.

The backwash line 31 and backwash flow in which the backwash water flows from the first filtration unit 2A to the second filtration unit 2B by the backwash water supply control of the first filtration unit 2A and the backwash water reception control of the second filtration unit 2B. The flow path of the communication line 37 is opened. The filtered water (backwash water) from the first filtration unit 2A is pumped by the RO liquid feed pump 23d, flows through the backwash communication line 37, and is supplied to the backwash line 31 of the second filtration unit 2B. . In the second filtration unit 2B, the backwash water received in the backwash line 31 flows back through the communication line 23 and is supplied to the secondary side of the MF membrane module 3, and the backwash water that has permeated the MF membrane 3a is backwash water. It flows through the discharge line 25 and is discharged. The operation panel 41 of the second filtration unit 2B is configured to open the valve V ₈ of the eighth to drive the compressor, not shown, by supplying air for air scrubbing into the primary side of the MF membrane module 3 MF Air scrubbing of the membrane module 3 is also performed at the same time.

Here, the control accompanying the backwash operation of the second filtration unit 2B will be described in more detail. In the first filtration unit 2A of the filtration device 1A, MF-RO direct connection control such as flow rate control and pressure control is performed. Specifically, the flow rate data of the filtrate water detected by the flow meter 23e is input to a control CPU (not shown) of the operation panel 41. The control CPU performs PID (Proportional Integral Derivative) calculation based on the flow rate data detected by the flow meter 23e, and performs inverter frequency control for the MF liquid feed pump based on the result. Thereby, the motor rotation speed control of the MF liquid feed pump 21b is executed, and the supply amount of raw water to the MF membrane module 3 varies. In addition, as PID calculation for inverter frequency control for MF liquid feed pumps, for example, output calculation based on a deviation from a set value can be mentioned, and in this embodiment, an output for maintaining the flow rate of filtered water at 25 m ³ / h. It is an operation.

  Further, the pressure data on the suction side of the RO liquid pump 23 d acquired by the pressure sensor 23 f is input to the control CPU of the operation panel 41. The control CPU performs PID calculation based on pressure data detected by the pressure sensor 23f, and performs inverter frequency control for the RO liquid pump. Thereby, the motor rotation speed control of the RO liquid feed pump 23d is executed, and the discharge amount of the RO liquid feed pump 23d varies. The PID calculation for controlling the inverter frequency for the RO liquid pump includes, for example, an output calculation based on a deviation from a set value. In this embodiment, the pressure on the suction side of the RO liquid pump 23d is maintained at the water column 5m. It is an output calculation for

By performing the above MF-RO direct connection control, for example, when the MF membrane differential pressure of the MF membrane module 3 on the pressurization side has increased, the rotational speed of the MF liquid feed pump 21b increases and the filtered water is increased. The flow rate is maintained at 25 m ³ / h. On the other hand, when the MF membrane differential pressure of the MF membrane module 3 of the second filtration unit 2B to be backwashed increases, the rotational speed of the RO liquid feed pump 23d increases and the suction side pressure is increased by the water column 5m. Since this is maintained, the discharge amount (backwash amount) of the RO liquid feed pump 23d is also continuously maintained at 25 m ³ / h. As a result, the occurrence of cavitation on the suction side of the RO liquid pump 23d can be prevented.

  Next, the filtration device 1A starts the backwash operation of the MF membrane module 3 of the first filtration unit 2A (step S3). In the backwash operation of the MF membrane module 3 of the first filtration unit 2A, the operation panel 41 of the first filtration unit 2A performs backwash water reception control, and the operation panel 41 of the second filtration unit 2B performs backwash water supply control. Execute.

  The backwash line 31 and backwash flow in which the backwash water flows from the second filtration unit 2B to the first filtration unit 2A by the backwash water reception control of the first filtration unit 2A and the backwash water supply control of the second filtration unit 2B. The flow path of the communication line 37 is opened. Then, the filtered water (backwash water) from the second filtration unit 2B (see FIG. 9) is supplied to the backwash line 31 of the first filtration unit 2A. Further, this backwash water is supplied to the secondary side of the MF membrane module 3, and the backwash water that has permeated through the MF membrane 3 a flows through the backwash water discharge line 25 and is discharged. In the first filtration unit 2A, air scrubbing of the MF membrane module 3 is also performed at the same time.

1 A of filtration apparatuses will start the flushing process of 1st filtration unit 2A and 2nd filtration unit 2B, after an alternating backwash process is complete | finished (step S4). Here, the operation panel 41 of the first filtration unit 2A closes the second valve V ₂ and the seventh valve V ₇ , and the first valve V ₁ while the fourth valve V ₄ remains open. Is released. Further, the operation panel 41 drives the MF liquid feed pump 21 b to supply raw water to the primary side of the MF membrane module 3. Similarly, the operation panel 41 of the second filtration unit 2B closes the second valve V ₂ and the sixth valve V ₆ , and the fourth valve V ₁ remains open. ₄ is released. Further, the operation panel 41 continues to drive the MF liquid feeding pump 21 b to supply raw water to the primary side of the MF membrane module 3.

In the above flushing process (see FIG. 10), raw water is supplied to both the primary side of the MF membrane module 3 of the first filtration unit 2A and the primary side of the MF membrane module 3 of the second filtration unit 2B. Washing water or turbidity remaining on the primary side of the membrane module 3 is washed away. The operation | movement for a filtration process is performed by repeatedly performing the process from the above step S1 to step S4.
In addition, you may perform the said flushing process alternately after 1st filtration unit 2A and 2nd filtration unit 2B after each backwashing process. Thereby, the turbid substance which floated at the time of backwashing can be removed reliably.

  Next, the operation and effect of the filtration device 1A according to the present embodiment will be described. In the filtration device 1A, the filtered water discharged from the MF membrane module 3 is pumped by the RO liquid feeding pump 23d. Here, for example, if the connection between the MF membrane module 3 and the RO liquid feed pump 23d is continuously performed without cutting off with an intermediate tank or the like, the balance is lost between the suction side and the discharge side of the RO liquid feed pump 23d. If this happens, cavitation may occur on the suction side of the RO liquid pump 23d. However, the RO liquid feed pump 23d of the filtration device 1A pumps the filtrate from the MF membrane module 3 while maintaining the suction side pressure at the set pressure, so that the occurrence of cavitation can be effectively prevented, and the RO liquid feed pump An intermediate tank or the like for pumping the filtered water in 23d becomes unnecessary. Furthermore, in the filtration apparatus 1A, the RO liquid feed pump 23d is also used for the function of transferring filtered water (backwash water), so that it is not necessary to separately provide a backwash pump and the equipment burden is reduced.

  Furthermore, in the filtration device 1A, for example, when the second filtration unit 2B is a backwash target, the filtrate water discharged from the MF membrane module 3 of the first filtration unit 2A other than the backwash target is backwashed as backwash water. It passes through the communication line 37 and is supplied to the second filtration unit 2B. Accordingly, in each of the first and second filtration units 2A and 2B, an independent backwash pipe dedicated to backwashing, a valve for opening and closing the flow path of these backwash pipes, and the like can be omitted. The backwashing in each of the first and second filtration units 2A and 2B can be performed in a shared manner. As a result, it is easy to construct an apparatus having a desired processing capacity while reducing the equipment load for backwashing.

  Further, the first and second filtration units 2A and 2B of the filtration device 1A constitute a unit capable of accommodating and transporting the MF membrane module 3 and the RO membrane module 5 in the container 7. It is also possible to standardize or standardize by determining the water treatment capacity per unit depending on the size. In particular, in the filtration device 1A, the MF membrane module 3 and the RO membrane module 5 are in continuous communication with each other, and no intermediate tank or the like is provided between them. For example, in an aspect provided with an intermediate tank or the like, it is necessary to adjust the capacity of the intermediate tank according to the processing capacity, and it is very difficult to efficiently fit in a narrow area such as a container, and standardization is also difficult. However, the filtration device 1A is not provided with an intermediate tank or the like, and an independent backwash pipe dedicated to backwashing is not required, so that standardization is facilitated, and as a result, expansion of equipment according to the desired water treatment capacity is achieved. It becomes easy.

  The first filtration unit 2A has the MF membrane module 3 in which the MF membrane 3a is incorporated in the previous process of the RO membrane module 5 in which the RO membrane 5a is incorporated, and the second filtration unit 2B is similarly RO membrane The MF membrane module 3 incorporating the MF membrane 3a is disposed in the previous process of the RO membrane module 5 incorporating the 5a. As a result, the turbid matter having a relatively large particle size in the raw water is removed in advance by the MF membrane 3a, so that the life of the RO membrane 5a can be extended.

Furthermore, each of the first filtration unit 2A and the second filtration unit 2B includes a plurality of MF membrane modules 3, and the number of MF membrane modules 3 in the first filtration unit 2A and the MF membrane modules 3 in the second filtration unit 2B. It is the same number as. Here, for example, when the number of MF membrane modules 3 of the first filtration unit 2A other than the backwash target is larger than the number of MF membrane modules 3 of the second filtration unit 2B to be backwashed, the first filtration unit 2A It is necessary to reduce the flow rate of filtered water used for backwashing according to the number of MF membrane modules 3 in the second filtration unit 2B. However, according to the present embodiment, since the number of the MF membrane modules 3 in the first filtration unit 2A and the second filtration unit 2B is the same, the control such as the flow rate adjustment of the filtrate water during backwashing is simplified. This is effective in realizing a simple configuration.
(Second Embodiment)

  Next, a filtration device 1B according to a second embodiment of the present invention will be described with reference to FIG. The filtration device 1B according to the second embodiment includes the same elements and members as the filtration device 1A according to the first embodiment, and the same elements and members as those of the first embodiment are the same. A detailed description is omitted with reference numerals. In FIG. 11, one of the plurality of MF membrane modules 3 divided into two groups is shown as a representative, and one of the MF membrane modules 3 is shown as a representative. Yes. Furthermore, one of the plurality of RO membrane modules 5 is shown as a representative.

  The filtration device 1B according to the present embodiment includes a first filtration unit 2C and a second filtration unit 2D, and the first filtration unit 2C and the second filtration unit 2D have substantially the same configuration. Hereinafter, the first filtration unit 2C will be mainly described.

Unlike the first filtration unit 2A according to the first embodiment, the first filtration unit 2C is not provided with the backwash line 31 branched from the downstream pipe line 23b of the communication line 23. Instead, a backwash line 51 branched from the concentrated water discharge line 29 and indirectly connected to the secondary side of the MF membrane module 3 is provided. The backwash line 51 includes a pipe line 51 a having a predetermined pipe diameter, and an upstream end of backwash water (filtered water) flowing in the pipe line 51 a is connected to a pipe line 29 a of the concentrated water discharge line 29. The downstream end is connected to the upstream line 23 a of the communication line 23. Moreover, the backwash line 51, similarly to the backwash line 31 according to the first embodiment, and the valve V ₆ and the seventh valve V ₇ of the sixth for opening and closing the flow path, a sixth valve Between V ₆ and the seventh valve V ₇ , it is connected to the conduit 37 a of the backwash communication line 37. The configuration of the backwash line 51 described above embodies a mode in which the downstream side where the filtered water discharged from the RO liquid feed pump 23d flows and the secondary side of the MF membrane module 3 are communicated.

According to the filtration device 1B according to the present embodiment, the same effect as that of the filtration device 1A according to the first embodiment can be expected, and the construction of a device having a desired processing capability while reducing the equipment load for backwashing. Becomes easier.
(Third embodiment)

  Next, a filtering device 1C according to a third embodiment of the present invention will be described with reference to FIG. The filtration device 1C according to the third embodiment includes elements, members, and the like that are equivalent to those of the filtration device 1A according to the first embodiment, and the same elements, members, and the like as those of the first embodiment are the same. A detailed description is omitted with reference numerals.

  The filtration device 1C includes a first filtration unit 2E, a second filtration unit 2F, a third filtration unit 2G, and a fourth filtration unit 2H. Furthermore, the backwash line 31 of each filtration unit 2E-2H is connected by the backwash communication line 3761.

  In the filtration device 1C according to the present embodiment, for example, when the third and fourth filtration units 2G and 2H are backwashed, the filtered water from the first and second filtration units 2E and 2F is used as backwash water. 3 and the fourth filtration units 2G and 2H.

  According to the filtration device 1C according to the present embodiment, a desired processing capacity can be achieved while reducing the equipment load for backwashing as with the filtration device 1A according to the first embodiment or the filtration device 1B according to the second embodiment. It becomes easy to construct a device having

  As mentioned above, although this invention was demonstrated concretely based on each embodiment, this invention is not limited only to said each embodiment. For example, the number of filtration units is not limited to two or four, but may be three or five or more, and can be appropriately selected according to the required flow rate of secondary permeate. Further, the pre-stage membrane is not limited to the MF membrane (microfiltration membrane), but may be an ultrafiltration membrane, and the post-stage membrane is not limited to the RO membrane (reverse osmosis membrane). A membrane with high separation performance can be used as appropriate.

  1A, 1B, 1C ... Filtration device, 2A, 2C, 2E ... 1st filtration unit, 2B, 2D, 2F ... 2nd filtration unit, 2G ... 3rd filtration unit, 2H ... 4th filtration unit, 3 ... MF membrane module (Pre-stage membrane module), 3a ... MF membrane (pre-stage membrane), 5 ... RO membrane module (rear-stage membrane module), 5a ... RO membrane, 23 ... communication line, 23d ... RO liquid feed pump (filtrate pressure feed pump), 31 ... backwash line, 37 ... backwash communication line.

Claims (3)

A filtration unit incorporating a plurality of pre-stage membrane modules having a pre-stage membrane for filtering the stock solution and a post-stage membrane module having a post-stage membrane having higher membrane separation performance than the pre-stage membrane is provided, and the stock solution is filtered by the pre-stage membrane module In the filtration device for filtering the filtrate discharged from the preceding membrane module through the latter membrane module,
A plurality of the filtration units;
The filtration unit communicates the secondary side of the front membrane module and the primary side of the rear membrane module, and is provided in a communication line through which the filtrate flows, and in the communication line, and pressure on the suction side A filtrate pump for pumping the filtrate while maintaining a set pressure, and a reverse side for communicating the downstream side of the filtrate discharged from the filtrate pump and the secondary side of the front membrane module A washing line,
The backwash lines of each of the plurality of filtration units are communicated with each other via a backwash communication line through which the filtrate flows, and the backwashed line is discharged from the front membrane module of the filtration unit other than the backwash target during backwashing. The filtration apparatus, wherein the filtrate is supplied to the filtration unit to be backwashed through the backwash communication line.   The filtration device according to claim 1, wherein the front membrane is a microfiltration membrane, and the rear membrane is a reverse osmosis membrane. The filtration unit includes a plurality of the front membrane modules,
The filtration apparatus according to claim 1 or 2, wherein the number of said front membrane modules in each of said filtration units is the same.

Images