JP2002346348A - Membrane filter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make apparatuses such as a filtrate tank and a backwashing pump for backwashing a membrane module unnecessary and to reduce expenses for apparatuses, power, and maintenance which are necessary for backwashing. SOLUTION: In a membrane filter device having a plurality of membrane modules 1-6, a liquid passage change-over mechanism for changing over liquid passages is installed to pass filtrate obtained from the other membrane modules 2-6 directly through the membrane module 1 for backwashing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane filtration device provided with a plurality of membrane modules and having an improved membrane backwashing mechanism.

[0002]

2. Description of the Related Art Ultrafiltration used for reverse osmosis (RO) membrane for desalination, water treatment for removing trace organic substances, solid-liquid separation treatment of river water, industrial water or wastewater, or biologically treated water. In membrane filtration devices such as (UF) membrane and microfiltration (MF) membrane,
Contaminants such as turbidity adhere to the membrane surface by passing the raw water through, and the membrane is clogged, resulting in flux (permeate water volume).
Decreases. For this reason, the flow of raw water is periodically stopped, and backwashing is performed in which the membrane permeated water flows backward from the secondary side (permeated water side) to the primary side (raw water side) of the membrane module to recover the flux. There is a need.

[0003] In a conventional membrane filtration apparatus, a permeate tank for storing the permeated water for backwashing, and a backwash pump for pressurizing and backflowing the permeated water in the permeate tank to the secondary side of the membrane module. Is attached. In addition, instruments and other equipment for managing and operating these permeated water tanks and backwash pumps are also required.

[0004]

In the conventional membrane filtration apparatus, a permeated water tank, a backwash pump and associated equipment are required for backwashing of the membrane module, and equipment costs and power costs required for these facilities are required. And maintenance costs are high.

The present invention solves the above-mentioned conventional problems, does not require equipment such as a permeated water tank and a backwash pump for backwashing a membrane module, and has low equipment costs, power costs, and maintenance costs. It is an object to provide a membrane filtration device.

[0006]

The membrane filtration device of the present invention comprises:
In a membrane filtration device provided with a plurality of membrane modules, a liquid passage switching mechanism that switches a liquid passage so that membrane permeated water obtained from another membrane module is directly passed through the membrane module that performs backwash to backwash. It is characterized by having.

[0007] In the membrane filtration device of the present invention, the backflow can be backwashed by passing the permeated water obtained from another membrane module directly through the backwashing membrane module by the passage switching mechanism. In addition, facilities such as a permeated water tank and a backwash pump for backwashing are not required.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the membrane filtration device of the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 are system diagrams showing an embodiment of a membrane filtration device according to the present invention. FIG. 1 shows a filtration operation state, and FIG. 2 shows a backwash operation state.

In FIGS. 1 and 2, a black portion of each valve indicates a portion where the liquid is flowing (valve opened), and a white portion indicates a portion where the liquid is not flowing (valve closed). .

In this membrane filtration device, raw water in a raw water tank 7 is passed through a pump P ₁ , a raw water main pipe 10 and raw water branch pipes 11 to 16 to membrane modules 1 to 6 arranged in parallel, and concentrated water Of the concentrated water branch pipes 41 to 46 and the concentrated water main pipe 40
And the permeated water is circulated to the raw water tank 7 through the
1 through 26 and the permeated water main pipe 20 are taken out. Each piping configuration will be described in detail as follows.

[0012] pump in the raw water tank 7 _{P 1} and the opening and closing valve V
_The raw water main pipe 10 is connected via ₁₀ . In addition,
The fungicide to raw water of the raw water main pipe 10 is capable added by chemical feed pump P _2.

From the raw water main pipe 10 to the raw water branch pipes 11 to
A branch 16 is connected, and the terminal side of each raw water branch pipe 11 to 16 is connected to the raw water inlet of the membrane module 1 to 6.
Close valve _V 11 _{~V 16} is provided in each raw water branch pipes 11-16.

The concentrated water outlets of the membrane modules 1 to 6 are
Three-way valve V via pipes 31-36 ₃₁~ V₃₆Inflow of
Connected to port. The three-way valve V₃₁~ V₃₆
Each have two outflow ports, of which
Branch pipes 41 for circulating concentrated water are connected to one of the outflow ports.
To 46 are connected.

The concentrated water branch pipes 41 to 46 are connected to the concentrated water main pipe 40. Off valve V ₄₀ is provided in the concentrate Mizushi pipe 40.

[0016] The other end of the branch pipe 51 to 56 of each of the outflow port backwash drainage discharge of the three-way valve _V 31 _{~V 36} is connected. The other ends of the branch pipes 51 to 56 are connected to a main pipe 50 for discharging backwash drainage.

One end of each of branch pipes 21 to 26 for extracting permeated water is connected to the permeated water outlets of the membrane modules 1 to 6 via on-off valves V _{21 to} V ₂₆ , respectively. The other end of 26 is connected to a main pipe 20 for taking out permeated water. Close valve _{V 20} is provided in the main pipe 20. The main pipe 20 for taking out the permeated water has a residual chlorine meter 9A for measuring residual chlorine in the permeated water,
A turbidity meter 9B for turbidity measurement is provided.

[0018] is connected to terminal side of the air branch pipes 61 to 66 for the air backwash to portions between the opening and closing valve _V 11 _{~V 16} and each membrane module 1-6 of the raw water branch pipes 11 to 16 I have. The upstream end side of each of the air branch pipes ₆₁ to 66 is connected to the main air pipe 60 via opening / closing valves V _{61 to} V ₆₂ . The air main pipe 60 is connected to the compressor 8 via an on-off valve V _60.

In this membrane filtration device, each of the membrane modules 1 to
In 6, the raw water is filtered for a predetermined time, then backwashed, and the filtration step and the backwash step are alternately repeated. In the backwashing step, backwashing is performed by passing permeated water of the other five membrane modules through one membrane module,
The membrane modules to be backwashed are sequentially switched.

First, the filtration step will be described with reference to FIG.

In the raw water filtration step, a valve for introducing raw water is used.
V₁₀, V₁₁, V₁₂, V₁₃, V₁₄, V_Fifteen, V
₁₆And a valve V for removing permeated water₂₀, V₂₁,
V₂₂, V ₂₃, V₂₄, V₂₅, V₂₆Open.
Also, a valve V for circulating concentrated water₄₀And open
, Three-way valve V₃₁, V₃₂, V₃₃, V₃₄, V
₃₅, V ₃₆Circulates concentrated water at the concentrated water outlet of the membrane module.
Communicates with branch branch pipes 41, 42, 43, 44, 45, 46
The flow path is selected so as to make it. Other valves V₆₀
~ V₆₆Is closed.

[0022] The raw water by the pump _{P 1,} the branches each raw water of the raw water tank 7 from the raw water introduced for the main pipe 10 pipe 11, 12, 13,
After going through 14, 15, 16 each membrane module 1, 2, 3,
Introduce to 4,5,6. The permeated water of the membrane modules 1 to 6 is taken out from the branch pipes 21, 22, 23, 24, 25, 26 via the main pipe 20 respectively. On the other hand, the concentrated water is supplied to pipes 31 and 41, pipes 32 and 42, pipes 33 and 43, and pipe 3 respectively.
4, 44, pipes 35, 45, and pipes 36, 46 are circulated from the main pipe 40 to the raw water tank 7. In this filtration step, the three-way valves V ₃₁ , V ₃₂ , V ₃₃ ,
By adjusting the flow path selection of V ₃₄ , V ₃₅ , V ₃₆ , a part of the concentrated water is respectively supplied to the branch pipes 51, 52, 53, 54, 55, 56.
Alternatively, it may be discharged outside the apparatus via the main pipe 50.

[0023] Incidentally, the raw water introduced into the membrane module 1-6, fungicides such as hypochlorite is injected by chemical feed pump P _2.

Next, a back washing step of back washing the membrane module 1 with the permeated water of the membrane modules 2 to 6 will be described with reference to FIG.

[0025] To perform backwashing of the membrane module 1, as shown in FIG. 2, the raw water pump _{P 1,} while actuating the dosing pump _{P 2,} first close valve _{V 11, V 20,} the valve V
_60, the _{V 61} with an open, three-way valve _{V 31} pipes 31 and 51 to the channel selected to communicate. Next, the compressor 8 is started.

As a result, the introduction of raw water into the membrane module 1 is stopped, and the pressurized air from the compressor 8 is instead supplied to the membrane module 1 through the collecting pipe 60 and the branch pipe 61.
Introduced to the next side.

In the membrane modules 2 to 6, raw water is introduced in the same manner as in the filtration step, and concentrated water is circulated to the raw water tank 7. The permeated water of the membrane modules 2 to 6 from the branch pipes 22 to 26 is
By the valve _{V 20} is closed, each branch pipe 22,
23, 24, 25, and 26 are introduced into the secondary side of the membrane module 1 through the branch pipe 21.

In the membrane module 1, when the permeated water of the membrane modules 2 to 6 introduced on the secondary side passes through the membrane, the contaminants adhering to the membrane surface are peeled off, and the primary membrane of the membrane is removed from the pipe 61. The peeling effect due to the high speed of the pressurized air introduced into the side passing through the membrane module is superimposed. That is, the backwash water and the pressurized air are mixed, and the gas-liquid interface moves rapidly, a strong shearing force is applied to the adhered contaminants, and the adhered contaminants are sufficiently removed. The backwash drainage of the membrane module 1 containing the exfoliated matter is discharged to the outside of the apparatus via the pipes 51 and 50.

After the backwashing of the membrane module 1 as described above, the permeated water of the membrane module 1 and the membrane modules 3 to 6 is passed through the membrane module 2 to backwash the membrane module 2. In this case, the valves V ₁₂ , V
_The valve ₆₁ is closed, the valves V ₁₁ and V ₆₂ are opened, and the three-way valve V ₃₁ is returned to the communication side of the pipes ₃₁ and 41, and the three-way valve V ₃₂ is switched to the communication side of the pipes ₃₂ and 52.
In this way, the introduction of the raw water into the membrane module 2 is stopped, and instead the pressurized air from the compressor 8 is introduced into the primary side of the membrane module 2 and the permeation of the membrane module 1 and the membrane modules 3 to 6 is performed. Water is introduced into the secondary side of the membrane module 2 to backwash the membrane module 2, and the backwash wastewater is piped 5.
It is discharged out of the device through 2,50.

By performing the same flow switching for the membrane modules 3 to 6, backwashing can be sequentially performed.

After performing such backwashing for each membrane module, the state is returned to the state shown in FIG. 1 and the filtration step is restarted.

The flow path switching by the above-mentioned series of valves can be performed by automatic control without manual operation, and the back washing and filtration steps of each membrane module may be performed according to a preset time schedule. .

In this embodiment, the open / close valve V is connected to the main pipe 20 for collecting and extracting the membrane permeated water from each membrane module.
₂₀ is provided, at the time of backwashing, permeation tanks and backwash for this reason that allows the valve V ₂₀ to backwash the subject of the membrane module close the backwashing by backflow permeate other membrane module, backwashing No equipment such as a pump is required, and the pump can be operated with only the raw water pump and the chemical injection pump.

In FIG. 2, the membrane modules 1 to
6, the backwash is performed only on one of the membrane modules 1 and the permeated water of the other membrane modules 2 to 6 is caused to flow back to the membrane module 1, but two or more membrane modules are simultaneously backwashed. May be performed. For example, FIG.
In further a valve _{V 62} open, the valve _{V 12} is closed,
By selecting the flow path of the three-way valve V32 to the communication side of the pipes ₃₂ and 52, the permeated water of the membrane modules 3 to 6 is caused to flow back to the secondary side of the membrane modules 1 and 2,
2 may be backwashed simultaneously.

In order to supply the permeated water from the membrane module that has not been backwashed to the secondary side of the membrane module to be backwashed at a sufficient backwash flow rate, a membrane filter is provided. In the case where all of the membrane modules have the same specifications, it is desirable that the permeated water is made to flow backward from two or more membrane modules per one membrane module to be backwashed.
However, backflow of an excessively large amount of permeated water may cause breakage of the membrane, etc., so (number of membrane modules to be backwashed): (supply water to the membrane module to be backwashed) It is preferable that the number of membrane modules) = 1: 2 to 5.

The membrane filtration device shown in FIGS. 1 and 2 is an example of an embodiment of the membrane filtration device of the present invention, and the present invention is not limited to the illustrated ones unless it exceeds the gist. For example, in FIGS. 1 and 2, pressurized air from the compressor is supplied to the primary side of the membrane at the time of backwashing in order to enhance the backwashing effect. Backwashing with only water may be used. This pressurized air may be supplied to the secondary side of the membrane, mixed with the backwash water, and backwashed with a gas-liquid mixed fluid.

Such a membrane filtration device of the present invention is particularly suitable for a UF membrane separation device or MF membrane separation device for solid-liquid separation used for various water treatments, or an RO membrane separation device for desalination.

[0038]

As described in detail above, the membrane filtration device of the present invention allows a membrane module for backwashing to be performed by selecting a flow direction by a flow path switching mechanism. Backwashing can be performed by passing permeated water directly. Therefore, facilities such as a permeated water tank and a backwash pump for backwashing are not required. In addition, equipment costs, power costs, and maintenance costs for backwashing can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a filtration step of a membrane filtration device according to an embodiment of the present invention.

FIG. 2 is a system diagram showing a back washing step of the membrane filtration device of FIG.

[Explanation of symbols]

 1,2,3,4,5,6 Membrane module 7 Raw water tank 8 Compressor 9A Residual chlorine meter 9B Turbidity meter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA03 GA06 GA07 JA52A JA53A JA57A JA63A JA67A KA03 KA63 KA67 KC02 KC03 KC13 KC14 KD06 KD24 KE13P KE30P PA01 PB04 PB08

Claims (1)

[Claims] In a membrane filtration device provided with a plurality of membrane modules, a liquid passage is switched so that membrane permeated water obtained from another membrane module is directly passed through a membrane module to be backwashed and backwashed. A membrane filtration device comprising a passage switching mechanism.