JP4882164B2 - Membrane filtration device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane filtration device having a membrane backwash mechanism improved in a membrane filtration device comprising a plurality of membrane modules.
[0002]
[Prior art]
Reverse osmosis (RO) membranes for desalination, ultrafiltration (UF) membranes used for solid-liquid separation treatment such as water treatment for removing trace organics, river water, industrial water or wastewater, or biologically treated water In a membrane filtration device such as a microfiltration (MF) membrane, when raw water is passed through, contaminants such as turbidity adhere to the membrane surface, and the flux (permeate flow rate) decreases due to clogging of the membrane. . For this reason, the flow of the raw water is periodically stopped, and the flux is recovered by performing the backwash that causes the membrane permeate to flow backward from the secondary side (permeate side) of the membrane module to the primary side (raw water side). There is a need.
[0003]
In the conventional membrane filtration apparatus, a permeated water tank for storing the permeated water for backwashing and a backwash pump for causing the permeated water in the permeated water tank to flow under pressure to the secondary side of the membrane module are attached. ing. In addition, management of these permeate tanks and backwash pumps, instruments for operation, and other equipment are also required.
[0004]
[Problems to be solved by the invention]
In the conventional membrane filtration apparatus, a permeated water tank, a backwash pump, and equipment associated therewith are required for backwashing the membrane module, and the equipment cost, power cost, and maintenance cost required for these facilities are high.
[0005]
The present invention solves the above-mentioned conventional problems, eliminates the need for facilities such as a permeate tank and backwash pump for backwashing of the membrane module, and is a membrane filtration device with low equipment, power, and maintenance costs The purpose is to provide.
[0006]
[Means for Solving the Problems]
The membrane filtration device of the present invention is a membrane filtration device comprising a plurality of membrane modules. The membrane permeate obtained from other membrane modules is directly passed through the membrane module to be backwashed so that the membrane is backwashed. It is equipped with a liquid passage switching mechanism for switching the path, a compressor for supplying pressurized air to each membrane module, and an air pipe. The introduction of raw water to the membrane module for backwashing is stopped, and instead from the compressor Introduce pressurized air into the primary side of the membrane module that performs the backwash and introduce permeated water from other membrane modules into the secondary side of the membrane module that performs the backwash, or perform backwashing, or A membrane filtration device configured to supply pressurized air to the secondary side of a membrane module for backwashing, mix in backwash water and backwash with a gas-liquid mixed fluid, and a raw water tank The raw water main pipe (10) is connected to (7). The raw water branch pipe branches off from the raw water main pipe (10), the terminal side of each raw water branch pipe is connected to the raw water inlet of each membrane module, and each raw water branch pipe is provided with an open / close valve to concentrate each membrane module. The water outlet is connected to an inflow port of a three-way valve through a pipe, each of the three-way valves has two outflow ports, and one of the outflow ports is connected to a branch pipe for concentrated water circulation, These concentrated water branch pipes are connected to a concentrated water main pipe (40), and one end of a branch pipe for backwash drainage is connected to the other outflow port of the three-way valve, and the other end of the branch pipe is connected. Is connected to a main pipe (50) for discharging backwash drainage, and one end of a branch pipe for extracting permeate is connected to the permeate outlet of the membrane module, and the other end of the branch pipe Is permeate extraction The end side of the air branch pipe is connected to the portion between each open / close valve and each membrane module of the raw water branch pipe, and the upstream end side of each air branch pipe is air. It is connected to the main pipe (60), and this air main pipe (60) is connected to the compressor (8) .
[0007]
In such a membrane filtration device of the present invention, the membrane passage to be backwashed can be directly passed through the membrane module to be backwashed by the fluid passage switching mechanism and backwashed. Facilities such as a permeate tank and a backwash pump are not required.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a membrane filtration device of the present invention will be described in detail with reference to the drawings.
[0009]
1 and 2 are system diagrams showing an embodiment of the membrane filtration device of the present invention. FIG. 1 shows a filtration operation state, and FIG. 2 shows a backwash operation state.
[0010]
In FIGS. 1 and 2, among the valves, the blackened portion indicates the portion during liquid passage (valve opening), and the white portion indicates the portion during non-liquid passage (valve closing).
[0011]
This membrane filtration device passes the raw water in the raw water tank 7 through the membrane modules 1 to 6 arranged in parallel via the pump P ₁ , the raw water main pipe 10 and the raw water branch pipes 11 to 16, and concentrates the concentrated water. The water is circulated to the raw water tank 7 through the water branch pipes 41 to 46 and the concentrated water main pipe 40, and the permeated water is taken out through the permeated water branch pipes 21 to 26 and the permeated water main pipe 20. Each piping configuration will be described in detail as follows.
[0012]
A raw water main pipe 10 is connected to the raw water tank 7 through a pump P ₁ and an opening / closing valve V ₁₀ . Incidentally, fungicide to raw water of the raw water main pipe 10 is capable added by chemical feed pump P _2.
[0013]
The raw water branch pipes 11 to 16 branch from the raw water main pipe 10, and the terminal sides of the raw water branch pipes 11 to 16 are connected to the raw water inlets of the membrane modules 1 to 6. Open / close valves V _{11 to} V ₁₆ are provided in the raw water branch pipes 11 to ₁₆ , respectively.
[0014]
The concentrated water outlets of the membrane modules 1 to 6 are connected to the inflow ports of the three-way valves V _{31 to} V ₃₆ via the pipes _{31 to 36} . Each of the three-way valves V _{31 to} V ₃₆ includes two outflow ports, and branch pipes 41 to 46 for circulating the concentrated water are respectively connected to one of the outflow ports.
[0015]
These concentrated water branch pipes 41 to 46 are connected to the concentrated water main pipe 40. An open / close valve V ₄₀ is provided in the concentrated water main pipe 40.
[0016]
One ends of branch pipes 51 to 56 for discharging backwash drainage are connected to the other outflow ports of the three-way valves V _{31 to} V ₃₆ , respectively. The other ends of the branch pipes 51 to 56 are connected to a main pipe 50 for discharging backwash drainage.
[0017]
One ends of branch pipes 21 to 26 for extracting permeate water are connected to the permeate outlets of the membrane modules 1 to 6 through on-off valves V _{21 to} V ₂₆ , respectively. The end is connected to the main piping 20 for extracting permeate. Close valve _{V 20} is provided in the main pipe 20. The main pipe 20 for extracting permeated water is provided with a residual chlorine meter 9A for measuring residual chlorine in the permeated water and a turbidity meter 9B for measuring turbidity.
[0018]
End side of the air branch pipes 61 to 66 for the air backwash is connected to the portion between each opening and closing valve _V 11 _{~V 16} and each membrane module 1-6 of the raw water branch pipes 11-16. The upstream end side of each of the air branch pipes ₆₁ to 66 is connected to the air main pipe 60 via the open / close valves V _{61 to} V ₆₂ . The air main pipe 60 is connected to the compressor 8 via an on-off valve V _60.
[0019]
In this membrane filtration apparatus, after filtering raw water in each membrane module 1-6 for a predetermined time, backwashing is performed, and a filtration process and a backwashing process are repeated alternately. In the backwashing step, the permeated water of the other five membrane modules is passed through one membrane module to perform backwashing, and the membrane modules to be sequentially backwashed are switched.
[0020]
First, the filtration process will be described with reference to FIG.
[0021]
In the raw water filtration step, the raw water introduction valves V ₁₀ , V ₁₁ , V ₁₂ , V ₁₃ , V ₁₄ , V ₁₅ , V ₁₆ and the permeated water extraction valves V ₂₀ , V ₂₁ , V ₂₂ , V _{23 are used.} , V ₂₄ , V ₂₅ , V ₂₆ are opened. The concentrated water circulation valve V ₄₀ is opened, and the three-way valves V ₃₁ , V ₃₂ , V ₃₃ , V ₃₄ , V ₃₅ , and V ₃₆ are connected to the concentrated water circulation branch pipes 41 and 42 of the membrane module. , 43, 44, 45, 46 are selected so as to communicate with each other. The other valve _V 60 _{~V 66} are closed.
[0022]
The raw water in the raw water tank 7 is transferred from the raw water introduction main pipe 10 to the membrane modules 1, 2, 3, 4, 5, 6 via the branch pipes 11, 12, 13, 14, ₁₅ , 16 by the raw water pump P1. Introduce. The permeated water of the membrane modules 1 to 6 is taken out from the branch pipes 21, 22, 23, 24, 25 and 26 through the main pipe 20. On the other hand, the concentrated water is circulated from the main pipe 40 to the raw water tank 7 through the pipes 31 and 41, the pipes 32 and 42, the pipes 33 and 43, the pipes 34 and 44, the pipes 35 and 45, and the pipes 36 and 46, respectively. In this filtration step, the flow path selection of the three-way valves V ₃₁ , V ₃₂ , V ₃₃ , V ₃₄ , V ₃₅ , V ₃₆ is adjusted, and a part of the concentrated water is respectively branched into the branch pipes 51, 52, 53, 54. , 55, 56 and the main pipe 50 may be discharged out of the apparatus.
[0023]
Note that the raw water introduced into the membrane module 1-6, fungicides such as hypochlorite is injected by chemical feed pump P _2.
[0024]
Next, the backwashing process of backwashing the membrane module 1 with the permeated water of the membrane modules 2 to 6 will be described with reference to FIG.
[0025]
In order to perform back washing of the membrane module 1, as shown in FIG. 2, the valves V ₁₁ and V ₂₀ are first closed and the valves V ₆₀ and V ₆₁ are closed while the raw water pump P ₁ and the chemical injection pump P ₂ are operated. The flow path is selected so that the pipes ₃₁ and 51 are in communication with the three-way valve V31. Next, the compressor 8 is started.
[0026]
Thereby, the introduction of the raw water into the membrane module 1 is stopped, and instead, the pressurized air from the compressor 8 is introduced to the primary side of the membrane module 1 through the collecting pipe 60 and the branch pipe 61.
[0027]
Raw water similarly to the membrane module 2-6 filtration step is introduced, but concentrated water is circulated to the raw water tank 7, the permeate of the membrane module 2-6 from branch pipe 22-26, the valve V ₂₀ is closed As a result, the branched pipes 22, 23, 24, 25, and 26 are introduced into the secondary side of the membrane module 1 through the branched pipe 21.
[0028]
In the membrane module 1, when the permeated water of the membrane modules 2 to 6 introduced to the secondary side permeates the membrane, the contaminants attached to the membrane surface are peeled off and introduced from the pipe 61 to the primary side of the membrane. The peeling effect due to the pressurized air passing through the membrane module at a high speed 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 separated. The backwash waste water of the membrane module 1 containing the peeled material is discharged out of the apparatus through the pipes 51 and 50.
[0029]
Thus, after the membrane module 1 is backwashed, the membrane module 2 is backwashed by passing the permeated water of the membrane module 1 and the membrane modules 3 to 6 through the membrane module 2. In this case, the valves V ₁₂ and V ₆₁ are closed from the state shown in FIG. 2, the valves V ₁₁ and V ₆₂ are opened, 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 turned on. Switch 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 Water is introduced into the secondary side of the membrane module 2 to backwash the membrane module 2, and backwash wastewater is discharged out of the apparatus through the pipes 52 and 50.
[0030]
The membrane modules 3 to 6 can be sequentially backwashed by switching the flow paths in the same manner.
[0031]
After performing such backwashing for each membrane module, the filtration process is resumed by returning to the state of FIG.
[0032]
The flow path switching by the series of valves described above can be performed by automatic control without requiring manpower, and the back washing and filtration steps of each membrane module may be performed according to a preset time schedule.
[0033]
In this embodiment, a membrane permeate was collected retrieving main pipe 20 to the opening and closing valve V ₂₀ from the membrane module is provided, at the time of backwashing, other membrane backwash subject of the membrane module close this valve V ₂₀ Since backwashing can be performed by backflowing the permeated water of the module, facilities such as a permeating water tank and backwashing pump for backwashing are unnecessary, and in particular, the pump can be operated with only the raw water pump and the chemical injection pump. Become.
[0034]
In FIG. 2, only one membrane module 1 among the membrane modules 1 to 6 is backwashed, and the permeated water of the other membrane modules 2 to 6 is caused to flow back to the membrane module 1. You may backwash simultaneously about this or more membrane modules. For example, in FIG. 2, the valve V ₆₂ is further opened, the valve V ₁₂ is closed, and the three-way valve V ₃₂ is selected on the communication side of the pipes ₃₂ and 52 so that the permeated water of the membrane modules 3 to 6 is passed through the membrane module 1. , 2 may be made to flow backward to the secondary side, and the membrane modules 1 and 2 may be backwashed simultaneously.
[0035]
In order to pressurize 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 backwashing flow rate, the membrane module provided in the membrane filtration device However, it is desirable that the permeated water flow back from two or more membrane modules with respect to each membrane module to be backwashed. However, since excessive flow of permeated water may cause damage to the membrane, (number of membrane modules to be backwashed): (Supply permeate to membrane modules to be backwashed) The number of membrane modules) is preferably in the range of 1: 2-5.
[0036]
The membrane filtration device of 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 one shown in the drawings unless it exceeds the gist thereof. For example, in order to enhance the backwash effect in FIG. 1 and 2, are supplied to the primary side of the membrane pressurized air from the compressor during backwashing, pressurized air This, on the secondary side of the membrane It may be supplied and mixed in backwash water and backwashed with a gas-liquid mixed fluid.
[0037]
Such a membrane filtration device of the present invention is particularly suitable for a solid-liquid separation UF membrane separation device or MF membrane separation device used for various water treatments, or a desalting RO membrane separation device.
[0038]
【Effect of the invention】
As described above in detail, the membrane filtration device of the present invention directly passes the membrane permeated water obtained from other membrane modules through the membrane module that performs backwashing by selecting the direction of fluid passage by the fluid passage switching mechanism. Liquid can be backwashed. For this reason, facilities, such as a permeate tank and a backwash pump for backwashing, become unnecessary. 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 process of a membrane filtration device according to an embodiment of the present invention.
FIG. 2 is a system diagram showing a backwashing process 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

Claims (1)

In a membrane filtration apparatus including a plurality of membrane modules, a fluid passage switching mechanism that switches a fluid passage so that membrane permeated water obtained from other membrane modules is directly passed through a membrane module that performs back washing and backwashed. And a compressor and air piping for supplying pressurized air to each membrane module,
The introduction of raw water into the membrane module to be backwashed is stopped, and instead, pressurized air from the compressor is introduced to the primary side of the membrane module to be backwashed, and the permeated water of other membrane modules is Introduce into the secondary side of the membrane module to be washed and perform backwashing, or supply pressurized air to the secondary side of the membrane module to perform backwashing and mix in backwash water to mix gas-liquid fluid A membrane filtration device configured to perform backwashing at
The raw water main pipe (10) is connected to the raw water tank (7), the raw water branch pipe is branched from the raw water main pipe (10), and the terminal side of each raw water branch pipe is connected to the raw water inlet of each membrane module. In addition, each raw water branch pipe is provided with an open / close valve, and the concentrated water outlet of each membrane module is connected to the inflow port of the three-way valve through the pipe, and each of the three-way valves has two outflow ports, Branch pipes for circulating the concentrated water are connected to one outflow port of each of these, and these concentrated water branch pipes are connected to the concentrated water main pipe (40). One end of a branch pipe for discharge is connected, and the other end of the branch pipe is connected to a main pipe (50) for discharging backwash drainage, and each of the permeate outlets of the membrane module is for permeate discharge. One of the branch piping And the other end of the branch pipe is connected to a main pipe (20) for extracting permeated water, and an air branch is connected to a portion between each open / close valve and each membrane module of the raw water branch pipe. Membrane filtration characterized in that the end side of the pipe is connected, the upstream end side of each air branch pipe is connected to the air main pipe (60), and this air main pipe (60) is connected to the compressor (8). apparatus.

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