Water treatment apparatus and filtration membrane cleaning method

Abstract

To provide a water treatment apparatus and a filtration membrane cleaning method capable of reliably performing filtration membrane cleaning.SOLUTION: A water treatment apparatus 101A includes: a membrane filtration apparatus 102 having a membrane-containing vessel 103; a membrane-treated water pipe L3 that supplies membrane-treated water processed by the membrane filtration apparatus 102 to a downstream section; a sealed container 104 that stores membrane-treated water supplied to the membrane-treated water pipe L3; and upper membrane cleaning water drain pipes L7a and L7b connected to a primary side of the membrane-containing vessel 103. When cleaning the membrane filtration apparatus 102 using the membrane-treated water stored in the sealed container 104, cleaning water is supplied to a secondary side of the membrane-containing vessel 103 of the membrane filtration apparatus 102 and drained through the upper membrane cleaning water drain pipes L7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a water treatment apparatus and a filtration membrane cleaning method.

Background Art

[0002] In a water treatment apparatus, after performing water treatment using a filtration membrane for a certain period, it is necessary to clean the filtration membrane.

[0003] Patent Document 1 describes a portable water purification treatment apparatus 11 (FIG. 3) characterized in that, at the start of membrane filtration in the membrane module 14 during initial operation, the hypochlorite injection pump 43 is operated to inject a large amount of hypochlorite into the membrane filtration water, and the membrane filtration water into which a large amount of hypochlorite has been injected is sent to the backwash water tank 17 and discharged outside the apparatus via the membrane backwash drainage line 22 connected to the backwash water tank 17. The portable water purification treatment apparatus 11 includes a backwash line 19 that feeds the membrane filtration water stored in the backwash water tank 17 to the membrane module 14 as backwash water for backwash cleaning via the backwash pump 18, an air supply device 20 that supplies air for air scrubbing the membrane module 14, a backwash water drainage line 21 that discharges the backwash water obtained by backwash cleaning the membrane module 14 and the air obtained by air scrubbing from the membrane module 14, and a membrane backwash drainage line 22 that connects the backwash line 19 and the backwash water drainage line 21 and discharges the membrane filtration water stored in the backwash water tank 17 outside the portable water purification treatment apparatus 11. The portable water purification treatment apparatus 11 is usually operated by sequentially repeating three steps: a water supply step, a water filling step, and a backwash step. In the backwash step, the operation of the water intake pump 23 and the hypochlorite injection pump 43 is stopped, and the intake of raw water and the injection of hypochlorite are aborted. Thereafter, the backwash pump 18 and the compressor 51 are operated to supply backwash water from the secondary side of the membrane module 14 and air from the primary side into the membrane module 14, and perform backwash cleaning and air scrubbing cleaning of the filtration membrane housed in the membrane module 14.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The portable water purification treatment device described in Patent Document 1 cannot reliably clean the filtration membrane housed in the secondary side membrane module of the membrane module.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a water treatment device and a filtration membrane cleaning method capable of reliably cleaning a filtration membrane.

Means for Solving the Problems

[0007] As a result of intensive studies, the present inventors have found that when a water treatment device is provided with an upper membrane cleaning water drain pipe connected to the primary side of a membrane filtration device, cleaning water is supplied to the secondary side of the membrane-containing vessel of the membrane filtration device, and drained from the upper membrane cleaning water drain pipe, the filtration membrane can be reliably cleaned, and thus the present invention has been completed. That is, aspects of the present invention are as follows.

[0008] [1] A membrane filtration device having a membrane-containing vessel, A membrane treatment water pipe for supplying the membrane treatment water treated by the membrane filtration device to a subsequent stage, A sealed container for storing the membrane treatment water supplied to the membrane treatment water pipe, An upper membrane cleaning water drain pipe connected to the primary side of the membrane filtration device A water treatment device comprising: When cleaning the membrane filtration device using the membrane treatment water stored in the sealed container, cleaning water can be supplied to the secondary side of the membrane-containing vessel of the membrane filtration device and drained from the upper membrane cleaning water drain pipe. [2] The water treatment device according to [1], further comprising an air pressurizing device for pressurizing air into the membrane treatment water stored in the sealed container. [3] The water treatment device according to [1] or [2], wherein the membrane filtration device further comprises a lower membrane cleaning water drain pipe connected to the primary side of the membrane-containing vessel. [4] The membrane filtration device of the water treatment device according to any one of [1] to [3] has at least one membrane-containing vessel. [5] The membrane filtration device of the water treatment device according to any one of [1] to [4] has two or more membrane-containing vessels. [6] The sealed container of the water treatment device according to any one of [1] to [5] is an empty vessel. [7] A method for cleaning a filtration membrane of the water treatment device according to any one of [1] to [6], wherein the membrane filtration device has two or more membrane-containing vessels, a membrane cleaning step of stopping water treatment in a part of the membrane-containing vessels, and using the membrane-treated water stored in the sealed container to clean the membrane-containing vessels in which water treatment has been stopped; comprising In the membrane cleaning step, a filtration membrane cleaning method is provided in which membrane-treated water is passed through the secondary side of the membrane-containing vessel in which water treatment has been stopped, and primary side upper drainage treatment is performed to discharge water from the upper part of the primary side of the membrane-containing vessel. [8] The water treatment device includes an air pressurizing device for pressurizing air into the membrane-treated water stored in the sealed container, In the membrane cleaning step, before the primary side upper drainage treatment, a first pressurizing treatment is performed by the air pressurizing device to pressurize the membrane-treated water stored in the sealed container, according to the filtration membrane cleaning method described in [7]. [9] In the membrane cleaning step, after the primary side upper drainage treatment, a primary side lower drainage treatment is performed in which membrane-treated water is passed through the secondary side of the membrane-containing vessel and discharged from the lower part of the primary side of the membrane-containing vessel, according to the filtration membrane cleaning method described in [7] or [8].

[10] The water treatment device includes an air pressurizing device for pressurizing air into the membrane-treated water stored in the sealed container, In the membrane cleaning step, between the primary side upper drainage treatment and the primary side lower drainage treatment, a second pressurizing treatment is performed by the air pressurizing device to pressurize the membrane-treated water stored in the sealed container again, according to the filtration membrane cleaning method described in [9].

[11] In the membrane cleaning step, after the primary-side lower part drainage treatment, membrane-treated water is passed through the secondary side of the membrane-containing vessel, and a primary-side upper and lower part drainage treatment is performed, in which drainage is simultaneously carried out from the upper and lower parts of the primary side of the membrane-containing vessel. The filtration membrane cleaning method according to [9] or

[10] .

[12] The water treatment apparatus includes an air pressurizing device that pressurizes air into the membrane-treated water stored in the sealed container. In the membrane cleaning step, between the primary-side lower part drainage treatment and the primary-side upper and lower part drainage treatment, a third pressurizing treatment is performed to repressurize the membrane-treated water stored in the sealed container by the air pressurizing device. The filtration membrane cleaning method according to

[11] .

[13] When performing the first pressurizing treatment, the membrane-treated water stored in the sealed container is pressurized from 0.05 MPa to the upper limit pressure of the membrane. The filtration membrane cleaning method according to [8].

[14] When performing the second pressurizing treatment, the membrane-treated water stored in the sealed container is pressurized from 0.05 MPa to the upper limit pressure of the membrane. The filtration membrane cleaning method according to

[10] .

[15] When performing the third pressurizing treatment, the membrane-treated water stored in the sealed container is pressurized from 0.05 MPa to the upper limit pressure of the membrane. The filtration membrane cleaning method according to

[12] .

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a water treatment apparatus and a filtration membrane cleaning method capable of reliably cleaning a filtration membrane.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0011] The "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0012] The water to be treated, which is the object of treatment of the water treatment apparatus and the water treatment method of the present invention, is not particularly limited. For example, raw water such as groundwater, well water, lake water, river water, industrial water, sewage, and wastewater can be mentioned. The water to be treated may be water that has been subjected to some treatment such as sand filtration in these raw waters. However, the water to be treated is not limited to these examples. The water to be treated may further contain anions such as organic substances, ammonia nitrogen, hydrogen carbonate ions, nitrate ions, sulfate ions, and chloride ions; cations such as iron ions, manganese ions, calcium ions, and magnesium ions; and impurities such as bacteria. However, the components of the water to be treated are not limited to these.

[0013] In the water treatment apparatus of the present invention, treated water can be obtained by filtering the water to be treated with a membrane filtration device. The treated water can be used, for example, for drinking water applications.

[0014] Hereinafter, embodiments of the present invention will be described in detail with appropriate reference to the drawings. However, the present invention is not limited to the embodiments described later, and various changes are possible without departing from the gist of the present invention.

[0015] <First Embodiment> [Water Treatment Apparatus] An example of a water treatment apparatus according to a first embodiment of the present invention, which shows a schematic diagram in FIG. 1, includes a membrane filtration apparatus 102 having a membrane-containing vessel 103, membrane-treated water pipes L3a and L3b for supplying the membrane-treated water processed by the membrane filtration apparatus 102 to the subsequent stage, a sealed container 104 for storing the membrane-treated water supplied to the membrane-treated water pipes L3a and L3b, and upper membrane cleaning water drain pipes L7a, L7b, and L7 connected to the primary side of the membrane filtration apparatus 102. When cleaning the membrane filtration apparatus 102 using the membrane-treated water stored in the sealed container 104, cleaning water is supplied to the secondary side of the membrane-containing vessel 103 of the membrane filtration apparatus 102, and can be drained from the upper membrane cleaning water drain pipe L7. It is a water treatment apparatus 101A that can supply cleaning water to the secondary side of the membrane-containing vessel 103 of the membrane filtration apparatus 102 and drain it from the lower membrane cleaning water drain pipe L8.

[0016] Here, the primary side of the membrane filtration apparatus or the membrane-containing vessel refers to the inlet side of the water that has not been membrane-treated (water to be treated). Also, the secondary side of the membrane filtration apparatus or the membrane-containing vessel refers to the outlet side of the water that has been membrane-treated (treated water).

[0017] Pumping pipes L1, L1a, and L1b are connected to the membrane filtration apparatus 102, and the water to be treated is supplied from the water to be treated supply source 108 to the inlet side of the membrane-containing vessel 103.

[0018] Membrane-treated water pipes L3a and L3b are connected to the membrane filtration apparatus 102, and the membrane-treated water is supplied from the outlet side of the membrane-containing vessel 103 to the inlet side of the sealed container 104.

[0019] In FIG. 1, the membrane filtration apparatus 102 and the sealed container 104 are directly connected by the membrane-treated water pipes L3a, L3b, and L3. However, other water treatment apparatuses, such as an ion exchange resin tower or an RO (reverse osmosis) membrane, may be provided in between.

[0020] A treated water supply pipe L4 is connected to the outlet side of the sealed container 104 to supply the treated water outside the water treatment apparatus.

[0021] [[ID=2)5]] A pressurized pipe L5 is connected to the sealed container 104, and pressurized air is supplied from the air pressurizing device 105 to the outlet side of the sealed container 104.

[0022] A chemical supply pipe L2 is connected to the pumping pipe L1, and chemicals are supplied from the chemical cleaning tank 106 to the inlet side of the membrane filtration device 102.

[0023] A chemical reflux pipe L6 is connected to the treated water supply pipe L4, and chemicals are refluxed from the outlet side of the sealed container 104 to the chemical cleaning tank 106. The chemicals circulate through the chemical cleaning tank 106, the chemical supply pipe L2, the pumping pipe L1a (L1b), the membrane-containing vessel 103 of the membrane filtration device 102, the sealed container 104, the treated water supply pipe L4, the chemical reflux pipe L6, and the chemical cleaning tank 106.

[0024] The membrane filtration device 102 includes a membrane-containing vessel 103. In FIG. 1, the first membrane-containing vessel 103a and the second membrane-containing vessel 103b are shown as the membrane-containing vessel 103, but the number of the membrane-containing vessels 103 is not limited to two, and may be one, or three or more. When the number of the membrane-containing vessels 103 is two or more, the purified water treatment can be performed by other membrane-containing vessels even during the cleaning of some of the membrane-containing vessels, and the operating rate of the water treatment device 101A can be increased. When the membrane filtration device 102 has two or more membrane-containing vessels 103, those membrane-containing vessels 103 may be connected in series or in parallel.

[0025] The filtration membrane of the membrane-containing vessel 103 is not particularly limited, but a pressurized UF (ultrafiltration) membrane / MF (microfiltration) membrane or a hollow fiber membrane is preferable. The membrane material is not particularly limited.

[0026] A pretreatment device of the chemical supply device such as a raw water tank, sand filtration, and an activated carbon tower may be provided between the water to be treated supply source 108 and the membrane filtration device 102.

[0027] The water treatment apparatus 101A according to the first embodiment may further include, and preferably includes, an air pressurizing device 105 that pressurizes air to the membrane-treated water stored in the sealed container 104. As the air pressurizing device 105, for example, it is preferable to use an air compressor. Since the air pressurizing device 105 can extrude water into the sealed container 104 by the force of air, it is not necessary to separately install a backwashing pump. The air pressurized by the air pressurizing device 105 is supplied to the sealed container 104 through the pressurizing pipe L5. When the membrane-treated water in the sealed container 104 is pressurized and supplied to the membrane-containing vessel 103 of the membrane filtration device 102, the membrane of the membrane-containing vessel is cleaned. Since the bubble-containing backwashing water mixed with air is used, the filtration membrane can be air-scrubbed, so the filtration membrane can be surely cleaned without separately adding a membrane cleaning chemical.

[0028] The membrane filtration device 102 preferably further includes a lower membrane cleaning water drain pipe L8 connected to the primary side of the membrane-containing vessel 103. The usage method of the lower membrane cleaning water drain pipe L8 will be described in the filtration membrane cleaning method described later.

[0029] "Water treatment method" The water treatment method according to the first embodiment of the present invention is a water treatment method using the water treatment apparatus 101A according to the first embodiment described above. The water treatment method of this embodiment has a storage step S1 of storing the membrane-treated water treated by the membrane filtration device 102 in the sealed container 104 at the subsequent stage.

[0030] After the membrane is cleaned, the chemical can be stored in the sealed container 104 and refluxed to the chemical cleaning tank 106 through the chemical reflux pipe L6. By refluxing the used chemical to the chemical cleaning tank 106, the chemical can be recycled, the usage amount of the chemical can be reduced, and the cost can be lowered. In this embodiment, it may also be refluxed to the chemical cleaning tank 106 without passing through the sealed container 104.

[0031] The closed container 104 is preferably an empty vessel according to the above-described usage method. In the water treatment apparatus 101A of the present embodiment, by using the closed container 104 such as an empty vessel as a backwash tank, it is possible to eliminate the need for separately installing a backwash tank. Thereby, a compact water treatment apparatus that does not use a backwash pump can be realized.

[0032] [Filtration membrane cleaning method] When performing filtration membrane cleaning, a membrane cleaning step S2 is provided in which water treatment in a part of the membrane-containing vessel 103 is stopped, and the membrane treatment water already stored in the closed container 104 is directly used to clean the membrane-containing vessel 103 where water treatment has been stopped. In the membrane cleaning step S2, primary-side upper drainage treatment P1 is performed in which membrane treatment water is passed through the secondary side of the membrane-containing vessel 103 where water treatment has been stopped and discharged from the upper part of the primary side of the membrane-containing vessel 103.

[0033] When the water treatment apparatus 101A includes an air pressurizing device 105 that pressurizes air into the membrane treatment water stored in the closed container 104, in the membrane cleaning step S2, it is preferable to perform a first pressurizing treatment P2 in which the membrane treatment water stored in the closed container 104 is pressurized by the air pressurizing device 105 before the primary-side upper drainage treatment P1. It is preferable to pressurize the membrane treatment water stored in the closed container 104 to 0.05 MPa to the upper limit pressure of the membrane during the first pressurizing treatment P2. For example, in the case of a pressurized UF membrane made of polyvinylidene fluoride (PVDF), it is preferable to pressurize to 0.05 to 0.3 MPa. The pressurization time is not particularly limited as long as the set pressure value is reached, but for example, 15 to 30 seconds is preferable. In this article, the upper limit pressure of the membrane is the upper limit design pressure that can be tolerated when cleaning the membrane. It is common for the membrane manufacturer to determine the upper limit pressure of the membrane based on the membrane material, shape, type of membrane unit, etc. If the membrane treatment water is pressurized below the lower limit value of the above pressure, the force of the water is weak and clogging of the membrane cannot be surely removed. If the upper limit pressure of the membrane is exceeded, there is a risk of damaging the membrane.

[0034] In the membrane cleaning step S2, after the primary side upper drainage treatment P1, it is preferable to perform a primary side lower drainage treatment P3 in which the membrane-treated water is passed through the secondary side of the membrane-containing vessel 103 and discharged from the lower part of the primary side of the membrane-containing vessel 103.

[0035] When the water treatment apparatus 101A includes an air pressurizing device 105 for pressurizing air into the membrane-treated water stored in the sealed container 104, in the membrane cleaning step S2, between the primary side upper drainage treatment P1 and the primary side lower drainage treatment P3, it is preferable to perform a second pressurizing treatment P4 in which the membrane-treated water stored in the sealed container 104 is pressurized again by the air pressurizing device 105. It is preferable to pressurize the membrane-treated water stored in the sealed container 104 to 0.05 MPa to the upper limit pressure of the membrane during the second pressurizing treatment P4. For example, in the case of a pressurized UF membrane made of PVDF, it is preferable to pressurize it to 0.05 to 0.3 MPa. The pressurizing time is not particularly limited, but 15 to 30 seconds is preferable.

[0036] In the membrane cleaning step S2, after the primary side lower drainage treatment P3, it is preferable to perform a primary side upper and lower drainage treatment P5 in which the membrane-treated water is passed through the secondary side of the membrane-containing vessel 103 and discharged simultaneously from the upper and lower parts of the primary side of the membrane-containing vessel 103.

[0037] When the water treatment apparatus 101A includes an air pressurizing device 105 for pressurizing air into the membrane-treated water stored in the sealed container 104, in the membrane cleaning step S2, between the primary side lower drainage treatment P3 and the primary side upper and lower drainage treatment P5, it is preferable to perform a third pressurizing treatment P6 in which the membrane-treated water stored in the sealed container 104 is pressurized again by the air pressurizing device 105. It is preferable to pressurize the membrane-treated water stored in the sealed container 104 to 0.05 MPa to the upper limit pressure of the membrane during the third pressurizing treatment P6. For example, in the case of a pressurized UF membrane made of PVDF, it is preferable to pressurize it to 0.05 to 0.3 MPa. The pressurizing time is not particularly limited, but 15 to 30 seconds is preferable.

[0038] The membrane cleaning step S2 preferably includes the following three treatment groups. Treatment group 1: First pressurization treatment P2 + primary side upper drainage treatment P1 Pressurize the treated water with a pressurizing device (compressor). Pressurize the backwash water to 0.05 - 0.3 MPa. The pressurization time is preferably about 15 - 30 seconds. Water is passed from the secondary side of the filtration membrane. After performing backwashing of the filtration membrane, open the cleaning drain valve B-3 and drain through the membrane cleaning water drain pipe L9. Since drainage is performed from the inlet of the water to be treated in the membrane-containing vessel, cleaning can be performed starting from the most contaminated part. Treatment group 2: Second pressurization treatment P4 + primary side lower drainage treatment P3 Pressurize the treated water with a pressurizing device (compressor). Pressurize the backwash water to 0.05 - 0.3 MPa. The pressurization time is preferably about 15 - 30 seconds. Water is passed from the secondary side of the filtration membrane. After performing backwashing of the filtration membrane, open the UF drain valve B-2 and drain through the lower membrane cleaning water drain pipe L8. By changing the drainage direction from that of treatment group 1, the filtration membrane can be surely cleaned. Treatment group 3: Third pressurization treatment P6 + primary side upper and lower drainage treatment P5 Pressurize the treated water with a pressurizing device (compressor). Pressurize the backwash water to 0.05 - 0.3 MPa. The pressurization time is preferably about 15 - 30 seconds. After performing backwashing of the filtration membrane, open both the UF drain valve B-2 and the cleaning drain valve B-3, and drain from both the lower membrane cleaning water drain pipe L8 and the membrane cleaning water drain pipe L9. By draining the cleaning water in both directions, cleaning can be more surely performed.

[0039] The opening and closing states of the UF outlet valve B-1, UF drain valve B-2, cleaning drain valve B-3, membrane pressurization valve B-4, and air cleaning valve B-5 in treatment groups 1 - 3 are shown below.

[0040]

Table 1

[0041] <Second Embodiment> [Water treatment device] An example of the water treatment apparatus according to the second embodiment of the present invention, which shows a schematic diagram in FIG. 2, is a water treatment apparatus 101B including a membrane filtration device 102, membrane treatment water pipes L3a and L3b for supplying the membrane treatment water treated by the membrane filtration device to a subsequent stage, and a sealed container 104 for storing the membrane treatment water supplied to the membrane treatment water pipes L3a and L3b, and capable of cleaning the membrane filtration device 102 using the membrane treatment water stored in the sealed container 104.

[0042] In the water treatment apparatus 101B, the membrane-containing vessel 103 is composed of two vessels, a first membrane-containing vessel 103a and a second membrane-containing vessel 103b. Needless to say, the number of membrane-containing vessels 103 is not limited to two and may be three or more. When the number of membrane-containing vessels 103 is two or more, it is possible to perform purified water treatment in other membrane-containing vessels even during the cleaning of some of the membrane-containing vessels, and the operating rate of the water treatment apparatus 101B can be increased. From the viewpoint of enabling automatic cleaning, V3a, V3b, V4a, V4b, V5a, V5b, V7a, V7b, V9a, and V9b are preferably automatic valves.

[0043] In the water treatment apparatus 101B, the sealed container 104 is composed of two vessels, a first sealed container 104a and a second sealed container 104b. Needless to say, the number of sealed containers 104 is not limited to two and may be three or more. When the number of membrane-containing vessels 103 is two or more, the number of sealed containers 104 can be increased correspondingly, and each of the membrane-containing vessels 103 can be cleaned using the water stored in each of the sealed containers 104.

[0044] When the membrane filtration device 102 has two or more membrane-containing vessels 103 and at least a part of them are connected in parallel, it is possible to perform water treatment in other membrane-containing vessels even while stopping water treatment and cleaning some of the membrane-containing vessels, and the operating rate of the water treatment apparatus 101B can be increased. In such a case, for example, the number of sealed containers 104 is increased correspondingly, and each of the membrane-containing vessels 103 is cleaned using the water stored in each of the sealed containers.

[0045] The water treatment apparatus 101B shown in FIG. 2 has two membrane-containing vessels 103 (a first membrane-containing vessel 103a and a second membrane-containing vessel 103b), and membrane treatment water pipes L3a and L3b that supply the membrane treatment water treated by the first membrane-containing vessel 103a and the second membrane-containing vessel 103b to the subsequent stage, and a sealed container 104 (a first sealed container 104a and a second sealed container 104b) that stores the membrane treatment water supplied to the membrane treatment water pipes L3a and L3b. Further, the water treatment apparatus 101B includes a chemical supply pipe L^2 for cleaning the first membrane-containing vessel 103a and the second membrane-containing vessel 103b with chemicals.

[0046] [Water treatment method] By providing on-off valves V5a and V5b in the membrane treatment water pipes L3a and L3b respectively, it is possible to control the water treatment of the first membrane-containing vessel 103a and the second membrane-containing vessel 103b respectively. Also, during membrane cleaning, the chemical is stored in the chemical cleaning tank 106, and is supplied by the chemical cleaning pump 107 to the first membrane-containing vessel 103a and the second membrane-containing vessel 103b of the membrane filtration device 102 through the chemical supply pipe L^2 and the pumping pipes L1a and L1b to clean the membrane. By providing on-off valves V3a and V3b in the pumping pipes L1a and L1b respectively, it is possible to control the cleaning of the first membrane-containing vessel 103a and the second membrane-containing vessel 103b respectively. That is, in the water treatment apparatus in which the membrane filtration device shown in FIG. 2 is composed of two or more membrane-containing vessels, without stopping the water treatment in the membrane filtration device, at least one of the two or more membrane-containing vessels performs water treatment, and for the remaining membrane-containing vessels, a membrane cleaning step is provided in which membrane cleaning is performed using the membrane treatment water stored in the sealed container before water treatment.

[0047] After the membrane is cleaned, the chemical can be stored in the sealed container 104 and refluxed to the chemical cleaning tank 106 through the chemical reflux pipe L6. By refluxing the used chemical to the chemical cleaning tank 106, the chemical can be recycled, the amount of chemical used can be reduced, and the cost can be lowered. Even in this embodiment, it may be refluxed to the chemical cleaning tank 106 without passing through the sealed container 104. From the viewpoint of enabling automatic cleaning, V3a, V3b, V4a, V4b, V5a, V5b, V7a, V7b, V9a, and V9b are preferably automatic valves.

[0048] The sealed container 104 is preferably an empty vessel according to the above-described usage method. In the water treatment apparatus 101B of this embodiment, by using a sealed container 104 such as an empty vessel as a backwash tank, it is possible to eliminate the need for separately installing a backwash tank. Thereby, a compact water treatment apparatus that does not use a backwash pump can be realized.

Explanation of Reference Numerals

[0049] 11 Portable water purification treatment apparatus 12 Raw water line 13 Feed water line 14 Membrane module [[ID=L23]]15 Hypochlorous acid injection device 16 Water filling line 17 Backwash water tank 18 Backwash pump 19 Backwash line 20 Air supply device 21 Backwash water drain line 22 Membrane backwash drain line 23 Water intake pump 25 Frame 27 Water intake hose connection port 28 Strainer 29 Flow rate adjustment valve 30 Flow meter 31, 38 Differential pressure gauge 33 Feed water hose connection port 34, 47, 57, 58 Electric valve 35 Feed water hose [[ID=5Y8]] 37 Backwash water outlet 40 Hypochlorous acid injection section 41 Hypochlorous acid tank 42 Hypochlorous acid injection line 43 Hypochlorous acid injection pump 44, 49, 53 Check Valve 45, 48 Water Level Sensor 51 Compressor 52 Air Supply Line 54 Drain Hose Connection Port 55 Drain Hose 59 Water Intake Source 60 Water Intake Hose 101A, 101B Water Treatment Device 102 Membrane Filtration Device 103 Membrane - Containing Vessel 103a First Membrane - Containing Vessel 103b Second Membrane - Containing Vessel 104 Sealed Container 104a First Sealed Container 104b Second Sealed Container 105 Air Pressurization Device 106 Chemical Cleaning Tank 107 Chemical Cleaning Pump 108 Water to be Treated Supply Source L1, L1a, L1b Water Pumping Pipe L2 Chemical Supply Pipe L3, L3a, L3b Membrane - Treated Water Pipe L4 Treated Water Supply Pipe L5 Pressurization Pipe L6 Chemical Reflux Pipe L7 Upper Membrane Cleaning Water Drain Pipe L8 Lower Membrane Cleaning Water Drain Pipe L9 Membrane Cleaning Water Drain Pipe L10, L10a, L10b Chemical Reflux Pipe B - 1 UF Outlet Valve B - 2 UF Drain Valve B - 3 Cleaning Drain Valve B - 4 Membrane Pressurization Valve B - 5 Air Cleaning Valve V1 Chemical Cleaning Switching Valve V2 Fine - Adjustment Valve V3a, V3b On - Off Valve V4a, V4b On - Off Valve V5a, V5b On - Off Valve V6 On - Off Valve V7a, V7b On / Off Valve V8 Process Water Regulation Valve PW Process Water RW Water to be Treated HPD High-Pressure Drainage C Chemical CP Compressor

Claims

1. a membrane filtration device having a membrane-containing vessel; A membrane-treated water pipe that supplies the membrane-treated water treated in the membrane filtration device to a subsequent stage; a sealed container for storing the membrane-treated water supplied to the membrane-treated water pipe; an upper membrane cleaning water drain pipe connected to the primary side of the membrane filtration device; A water treatment device comprising: When cleaning the membrane filtration device using the membrane-treated water stored in the sealed container, cleaning water can be supplied to the secondary side of the membrane-containing vessel of the membrane filtration device and drained from the upper membrane cleaning water drain pipe.

2. The water treatment device according to claim 1 , further comprising an air pressurizing device that applies air pressure to the membrane-treated water stored in the sealed container.

3. The water treatment device according to claim 1 or 2, further comprising a lower membrane cleaning water drain pipe connected to the primary side of the membrane-containing vessel.

4. The water treatment system of claim 1 or 2, wherein the membrane filtration device comprises at least one membrane-containing vessel.

5. The water treatment device of claim 1 or 2, wherein the membrane filtration device comprises two or more membrane-containing vessels.

6. The water treatment device according to claim 1 or 2, wherein the sealed container is an empty vessel.

7. The filtration membrane cleaning method for a water treatment device according to claim 1 or 2, the membrane filtration device has two or more membrane-containing vessels; A membrane cleaning step in which water treatment in a part of the membrane-containing vessel is stopped and the membrane-treated water stored in the sealed container is used to clean the membrane-containing vessel in which water treatment has been stopped. Equipped with In the membrane cleaning step, membrane-treated water is passed through the secondary side of the membrane-containing vessel in which water treatment has been stopped, and is discharged from the upper part of the primary side of the membrane-containing vessel. This is a filtration membrane cleaning method.

8. the water treatment device includes an air pressurizing device that pressurizes air into the membrane-treated water stored in the sealed container, 8. The filtration membrane cleaning method according to claim 7, wherein, in the membrane cleaning step, a first pressurization treatment is performed by the air pressurization device to pressurize the membrane-treated water stored in the sealed container before the primary-side upper drainage treatment.

9. 8. The filtration membrane cleaning method according to claim 7, wherein, in the membrane cleaning step, after the primary-side upper drainage treatment, a primary-side lower drainage treatment is performed in which membrane-treated water is passed through the secondary side of the membrane-containing vessel and discharged from a lower part of the primary side of the membrane-containing vessel.

10. the water treatment device includes an air pressurizing device that pressurizes air into the membrane-treated water stored in the sealed container, The filtration membrane cleaning method according to claim 9, wherein in the membrane cleaning step, a second pressurization process is performed between the primary side upper drainage treatment and the primary side lower drainage treatment to repressurize the membrane-treated water stored in the sealed container by the air pressurization device.

11. The filtration membrane cleaning method according to claim 9, wherein in the membrane cleaning step, after the primary side lower drainage treatment, membrane-treated water is passed through the secondary side of the membrane-containing vessel, and a primary side upper and lower drainage treatment is performed to discharge simultaneously from the upper and lower parts of the primary side of the membrane-containing vessel.

12. The water treatment device includes an air pressurization device that pressurizes air into the membrane-treated water stored in the sealed container. The filtration membrane cleaning method according to claim 11, wherein in the membrane cleaning step, a third pressurization process is performed between the primary side lower drainage treatment and the primary side upper and lower drainage treatment to repressurize the membrane-treated water stored in the sealed container by the air pressurization device.

13. The filtration membrane cleaning method according to claim 8, wherein the membrane-treated water stored in the sealed container is pressurized from 0.05 MPa to the upper limit pressure of the membrane during the first pressurization process.

14. The filtration membrane cleaning method according to claim 10, wherein the membrane-treated water stored in the sealed container is pressurized from 0.05 MPa to the upper limit pressure of the membrane during the second pressurization process.

15. The filtration membrane cleaning method according to claim 12, wherein the membrane-treated water stored in the sealed container is pressurized from 0.05 MPa to the upper limit pressure of the membrane during the third pressurization process.

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