JP2005319375A - Membrane treatment method and membrane treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane treatment method and a membrane treatment apparatus capable of utilizing ozone related equipment in both of filtration and washing. <P>SOLUTION: In a filtration process, ozone treated water W2 which is set to an ozone concentration upon the filtration in an ozone reaction tower 11 is allowed to permeate membrane modules 1, 2, 3 from the primary side to the secondary side thereof and, is filtered, therethrough. In a circulation washing process, the ozone treated water W2 which is set to an ozone concentration upon the washing in the ozone reaction tower 11 is circulated between the primary sides of the membrane modules 1, 2, 3 and the ozone reactor 11 and, therethrough, the membrane modules 1, 2, 3 are washed. According to the membrane treatment method and the membrane treatment apparatus, the efficiency of utilization of the ozone related equipment can be enhanced. Further, because the ozone treated water is circulated, ozone can be efficiently utilized and the control of ozone concentration can be exactly performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a membrane treatment method and a membrane treatment apparatus, and more particularly to a membrane treatment method and a membrane treatment apparatus that can use ozone-related equipment for both filtration and cleaning.

Conventionally, a “slime removal method” is known in which ozone-containing water having a concentration of 0.2 mg / L or more is passed through a membrane at a linear flow rate of 1 m / s or more during cleaning (see, for example, Patent Document 1).
Also, during backwashing, ozone is injected into the backwashing water on the secondary side of the membrane module, and ozone that has passed through the secondary side is mixed with the circulating water on the primary side to perform air scrubbing (bubbling). "Apparatus" is known (for example, refer to Patent Document 2).
In addition, a “membrane cleaning device cleaning method” is known in which ozone scrubbing (bubbling) is performed by blowing ozone-containing air into the primary side of the membrane module during backwashing (see, for example, Patent Document 3).
Further, a “purification method of sewage secondary treated water” is known in which ozone is blown into water supplied to the primary side of the membrane module during filtration (see, for example, Patent Document 4).
JP-A-3-249927 JP-A-5-305221 ([0023]) Japanese Patent Laying-Open No. 2002-361054 ([0022]) JP 2002-136981 A ([0011])

In the above “slime removal method”, the ozone-related equipment is used only for the circulation cleaning process, and is not used in the filtration process. Moreover, since ozone-containing water is flowed and discharged out of the system as it is, ozone that has not been used is also discarded, and there is a problem that there is a lot of waste.
Further, in the above-mentioned “membrane separation water treatment apparatus”, ozone-related equipment is used only for the circulation cleaning process, and is not used in the filtration process, so there is a problem that the utilization efficiency of the equipment is poor. Moreover, since ozone that has passed through the secondary side is mixed with the primary side of the membrane module, there is a problem that it is difficult to control the ozone concentration on the primary side, which requires higher ozone cleaning than the secondary side.
Moreover, in the above-mentioned “cleaning method of membrane filtration apparatus”, ozone-related equipment is used only for the circulation cleaning process, and is not used in the filtration process, so there is a problem that the utilization efficiency of the equipment is poor. Moreover, since ozone-containing air is blown and discharged out of the system as it is, ozone that has not been used is also discarded, and there is a problem that there is a lot of waste.
Moreover, in the above-mentioned “purification method of sewage secondary treated water”, ozone-related equipment is used only for the filtration process, and is not used in the circulation cleaning process. .
Therefore, an object of the present invention is to provide a membrane treatment method and a membrane treatment apparatus that can use ozone-related equipment for both filtration and cleaning.

In a first aspect, the present invention circulates ozone-treated water whose ozone concentration is the ozone concentration during filtration to the primary side of the membrane module, and a part of the ozone-treated water is recovered from the primary side of the membrane module. During the normal operation of repeating the filtration process for permeating to the secondary side and the backwashing process for allowing the washing water to permeate from the secondary side to the primary side of the membrane module, the ozone-treated water with the ozone concentration being the ozone concentration at the time of circulating cleaning is used. Provided is a membrane treatment method characterized by sandwiching a circulation washing step of washing the membrane module by circulating water through a primary side of the membrane module.
In the membrane treatment method according to the first aspect, since ozone is used in both the filtration step and the circulation cleaning step, ozone-related equipment can be used for both filtration and washing, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water is circulated through the primary side of the membrane module, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In a second aspect, the present invention provides the membrane treatment method having the above-described configuration, wherein the ozone concentration during circulation cleaning is made higher than the ozone concentration during filtration.
In the membrane treatment method according to the second aspect, the cleaning effect can be enhanced by making the ozone concentration during circulation cleaning higher than the ozone concentration during filtration.

In a third aspect, the present invention provides the membrane treatment method having the above-described configuration, wherein a plurality of the membrane modules are installed in parallel, the normal operation is performed in some membrane modules, and the normal operation is stopped in the remaining membrane modules. Then, a film processing method is provided in which the circulation cleaning step is performed.
In the membrane treatment method according to the third aspect, circulation cleaning can be performed without completely stopping filtration.

In a fourth aspect, the present invention provides the membrane treatment method configured as described above, wherein the filtration step is stopped when a differential pressure between a primary side and a secondary side of the membrane module is equal to or greater than a predetermined value during the filtration step. Provided is a film processing method characterized by performing the circulation cleaning step.
In the membrane treatment method according to the fourth aspect, the circulation washing step can be performed when the filtration ability is not recovered in the back washing step.

In a fifth aspect, the present invention relates to a membrane module, an ozone reaction tower that injects ozone into raw water to produce ozone treated water, an ozone treated water tank that stores the ozone treated water, and an ozone concentration of the ozone treated water. By circulating ozone treated water between the ozone reaction tower, the ozone treated water tank and the primary side of the membrane module while maintaining the ozone concentration during filtration, a part of the ozone treated water is secondary from the primary side of the membrane module. Filtration circulation means for permeating to the side to obtain filtered water, backwashing means for allowing washing water to permeate from the secondary side to the primary side of the membrane module, while the ozone concentration of the ozone treated water is set to the ozone concentration during circulation washing Circulating cleaning means for cleaning the membrane module by circulating ozone treated water between the ozone reaction tower, the ozone treated water tank, and the primary side of the membrane module. To provide a membrane treatment apparatus is characterized in that comprises a.
In the membrane treatment apparatus according to the fifth aspect, since ozone is used in both the filtration process and the circulation washing process, the ozone-related equipment can be used for both filtration and washing, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water is circulated through the primary side of the membrane module, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In a sixth aspect, the present invention relates to a membrane module, an ozone reaction tower that injects ozone into raw water to make ozone treated water, an ozone treated water tank that stores the ozone treated water, and an ozone concentration of the ozone treated water. A portion of the ozone treated water is transmitted from the primary side to the secondary side of the membrane module by circulating ozone treated water between the ozone treated water tank and the primary side of the membrane module while maintaining the ozone concentration during filtration. Filtration circulation means for obtaining filtered water, backwashing means for permeating the washing water from the secondary side to the primary side of the membrane module, and the ozone reaction tower while the ozone concentration of the ozone treated water is set to the ozone concentration during the circulation washing. The membrane by circulating ozone treated water between the ozone treated water tank and circulating ozone treated water between the ozone treated water tank and the primary side of the membrane module. To provide a membrane treatment apparatus is characterized in that comprises a circulation cleaning means for cleaning the module.
In the membrane treatment apparatus according to the sixth aspect, since ozone is used in both the filtration process and the circulation cleaning process, the ozone-related equipment can be used for both filtration and washing, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water is circulated through the primary side of the membrane module, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In a seventh aspect, the present invention relates to a membrane module, an ozone reaction tower that injects ozone into raw water to produce ozone treated water, an ozone treated water tank that stores the ozone treated water, and an ozone concentration of the ozone treated water. By circulating ozone treated water between the ozone reaction tower, the ozone treated water tank and the primary side of the membrane module while maintaining the ozone concentration during filtration, a part of the ozone treated water is secondary from the primary side of the membrane module. Filtration circulation means for permeating to the side to obtain filtered water, backwashing means for allowing washing water to permeate from the secondary side to the primary side of the membrane module, while the ozone concentration of the ozone treated water is set to the ozone concentration during circulation washing Ozone treated water is circulated between the ozone reaction tower and the ozone treated water tank, and ozone is circulated between the ozone reaction tower, the ozone treated water tank and the primary side of the membrane module. To provide a membrane treatment apparatus is characterized in that comprises a circulation washing means for washing the membrane module by circulating physical water.
In the membrane treatment apparatus according to the seventh aspect, since ozone is used in both the filtration process and the circulation cleaning process, ozone-related equipment can be used for both filtration and washing, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water is circulated through the primary side of the membrane module, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In an eighth aspect, the present invention provides a membrane treatment apparatus having the above-described configuration, wherein the ozone concentration during circulation cleaning is higher than the ozone concentration during filtration.
In the membrane treatment apparatus according to the eighth aspect, the cleaning effect can be enhanced by making the ozone concentration during circulation cleaning higher than the ozone concentration during filtration.

In a ninth aspect, the present invention provides the membrane processing apparatus having the above-described configuration, wherein a plurality of the membrane modules are installed in parallel, the filtration circulation means is operated in some membrane modules, and the filtration circulation is performed in the remaining membrane modules. The film processing apparatus is characterized in that the circulating cleaning means is operated by stopping the means.
In the membrane treatment apparatus according to the ninth aspect, the circulation cleaning can be performed without completely stopping the filtration.

In a tenth aspect, the present invention provides the membrane treatment apparatus having the above-described configuration, wherein the circulation is performed when a differential pressure between the primary side and the secondary side of the membrane module when the filtration circulation unit is operated is equal to or greater than a predetermined value. A film processing apparatus characterized by operating a cleaning means is provided.
In the membrane treatment method according to the tenth aspect, the circulation washing step can be performed when the filtration ability is not recovered in the back washing step.

In an eleventh aspect, the present invention provides the membrane treatment apparatus having the above-described configuration, wherein ozone treatment water is not supplied to the primary side of the membrane module between the ozone reaction tower and the ozone treatment water tank without supplying ozone treatment water. There is provided a membrane treatment apparatus comprising a pre-filtration circulation means for making the ozone concentration of the ozone treated water to be the ozone concentration during filtration while circulating.
In the membrane treatment method according to the eleventh aspect, it is possible to prevent clogging of the membrane from proceeding when ozone treatment water having an ozone concentration lower than the ozone concentration during filtration is supplied to the primary side of the membrane module at the start of the filtration step. .

  According to the membrane treatment method and the membrane treatment apparatus of the present invention, ozone-related equipment can be used for both filtration and cleaning, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water is circulated through the primary side of the membrane module, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

  Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is an explanatory diagram of a configuration of a film processing apparatus 100 according to the first embodiment.
The membrane treatment apparatus 100 includes a raw water pump 10 that takes in raw water W1 such as sewage secondary treated water and tap raw water, an ozone reaction tower 11 that converts raw water W1 into ozonized water W2 by ozonized air, and ozonized air. To circulate the generated ozone generator 12, the exhausted ozone treatment tower 13 for detoxifying the ozone discharged from the ozone reaction tower 11, the ozone treated water tank 14 for storing the ozone treated water W2, and the ozone treated water W2. Circulation pump 15, an ozone concentration meter 16 for measuring the ozone concentration of the ozone treated water W2 at the inlet of the circulation pump 15, and the ozone treated water W 2 passed through the primary side are filtered and filtered to the secondary side The return path 17 for returning the membrane module 1, 2, 3 that allows the water W3 to permeate, and the ozone treated water W2 that has not been filtered and has exited from the primary side of the membrane module 1, 2, 3 to the ozone reaction tower 11 A short path 17b for returning the ozone treated water W2 discharged from the circulation pump 15 to the ozone reaction tower 11 without passing through the membrane modules 1, 2, 3, a filtered water tank 20 for storing the filtered water W3, and a filtered water tank 20 Backwash pump 21 for supplying backwash water W3 to the secondary side of membrane modules 1, 2, 3 and backwashing, drainage tank 23 for storing backwash drainage, and membrane modules 1, 2, 3 primary Compressor 24 for supplying air to the side to perform air scrubbing, Reservoir 30 for storing filtered water W3 to relieve the imbalance between the production amount of filtered water W3 and the demand amount as purified water or reclaimed water, and the flow rate In addition, the pressure difference between the membrane modules 1, 2, 3 and the ozone concentration, the amount of water stored, etc. are monitored, and the pumps 10, 15, 21, the ozone generator 12, the compressor 24, and the valves V1 to V20, V22 to V24 are connected. And a control unit 40 for work. In addition, FI in a figure is a flowmeter.
Although not shown, the primary side inlet pressures p11, p21, and p31, the primary side outlet pressures p12, p22, and p32, and the secondary side outlet pressures p13, p23, and p33 are measured. It has a pressure gauge.

  The filtration membranes of the membrane modules 1, 2, 3 are, for example, external pressure hollow fiber membranes having ozone resistance. The pore size of the filtration membrane is 0.45 μm or less.

  Next, the operation will be described. As an initial state, it is assumed that the pumps 10, 15, 21 and the ozone generator 12 and the compressor 24 are stopped and the valves V1 to V20 and V22 to V24 are closed.

[Start operation]
-Circulation process before filtration-
The raw water pump 10 is operated to pass the raw water W1 through the ozone reaction tower 11. Further, the ozone generator 12 is operated to inject ozonized air into the ozone reaction tower 11. Further, the valves V1 and V2 are opened, and the circulation pump 15 is operated.
The ozone-treated water W <b> 2 that has been subjected to ozone treatment in the ozone reaction tower 11 flows into the ozone-treated water tank 14. The ozone-treated water W2 stored in the ozone-treated water tank 14 returns to the ozone reaction tower 11 through the short path 17b. Accordingly, the ozone treated water W2 circulates between the ozone reaction tower 11 and the ozone treated water tank 14.
When the inflow amount of the raw water W1 and the injection amount of ozonized air are adjusted and the ozone concentration measured by the ozone concentration meter 16 reaches the ozone concentration during filtration, the operation is shifted to normal operation.
The ozone concentration during filtration is such that the residual ozone concentration at the outlets of the membrane modules 1, 2 and 3 during normal operation is 1.0 to 2.0 mg / L. This is to prevent clogging in the membrane modules 1, 2 and 3 in combination with sterilization or inactivation of bacteria and protozoa, removal of chromaticity, and reduction of COD (chemical oxygen demand). It is.

[Normal operation]
-Filtration process-
The valves V3 to V11 and V20 are opened, and the valve V2 is closed.
The ozone-treated water W2 flows from the ozone-treated water tank 14 into the primary inlet of the membrane modules 1, 2, and 3, flows out of the primary outlet, and returns to the ozone reaction tower 11 through the return path 17a. Accordingly, the ozone-treated water W2 circulates between the ozone reaction tower 11, the ozone-treated water tank 14, and the primary sides of the membrane modules 1, 2, and 3.
Part of the ozone-treated water W2 that passes through the primary side of the membrane modules 1, 2, 3 (usually over 50%) permeates the membrane from the primary side to the secondary side to become filtered water W3, and the rest is the ozone reaction tower 11 Return to.
The filtered water W3 is stored in the filtered water tank 20. The filtered water W3 that overflows the filtered water tank 20 is stored in the water tank 30.

During the filtration step, differential pressures ΔP1, ΔP2, and ΔP3 in the membrane modules 1, 2, and 3 are obtained.
ΔP1 = (p11 + p12) / 2−p13
ΔP2 = (p21 + p22) / 2−p23
ΔP3 = (p31 + p32) / 2−p33
It is. If all of the differential pressures ΔP1, ΔP2, and ΔP3 are equal to or lower than the first threshold value (for example, 0.20 MPa), the filtration process is continued. If all of the differential pressures ΔP1, ΔP2, and ΔP3 are equal to or higher than the second threshold value (for example, 0.25 MPa). The chemical cleaning is requested, and if any one of the differential pressures ΔP1, ΔP2, and ΔP3 is between the first threshold value and the second threshold value, the process proceeds to the circulation cleaning operation.
If a filtration process is continued for 10 to 20 minutes, it will transfer to a backwash process.

-Backwash process-
The membrane modules 1, 2, 3 are backwashed in order.
For example, when the membrane module X (X is one of 1, 2 and 3) is back-washed, the valve V _{16 + X} is opened and the valves V _{2 + X} , V _{5 + X} , and V _{8 + X} are closed. Further, the valves V12 and V11 _{+ X} are opened, and the backwash pump 21 is operated. Thereby, the filtrate W3 permeate | transmits back from the secondary side of the membrane module X to a primary side, and the backwashing of a membrane is performed.
At the same time, the valve V _{21 + X} is opened and the compressor 24 is operated. Thereby, air scrubbing cleaning is performed.
When backwashing and air scrubbing are continued for 30 seconds to 3 minutes, the backwashing pump 21 and the compressor 24 are stopped, and the valves V21 _{+ X} , V12, and V12 _{+ X} are closed. Thereafter, the valve V2 _{+ X} is opened, the circulation pump 15 is operated, and the backwash drainage on the primary side of the membrane module X is drained from the valve V16 _{+ X} to the drainage tank 23. After 30 to 60 seconds, the valve V _{16 + X} is closed, the valves V _{5 + X} and V _{8 + X} are opened, and the process returns to the filtration step.

[Circulation cleaning operation]
-Circulation cleaning process-
The membrane modules 1, 2, and 3 are circulated and washed simultaneously.
The raw water pump 10 is stopped and the valves V9 to V11 are closed. Thereby, the ozone treatment W2 circulates between the ozone reaction tower 11, the ozone treatment water tank 14, and the primary sides of the membrane modules 1, 2, 3 without being filtered.
The ozone concentration measured by the ozone densitometer 16 is adjusted to the ozone concentration during circulation cleaning by adjusting the injection amount of ozonized air.
The ozone concentration during cleaning is such that the residual ozone concentration at the inlet of the circulation pump 15 becomes 1.0 to 5.0 mg / L.
After continuing a circulation washing process for 0.5 to 5 hours, valve | bulb V9-V11 is opened, the raw | natural water pump 10 is operated, and it returns to a filtration process.

[Test example]
Membrane treatment was performed using the membrane treatment apparatus 100 of Example 1.
The conditions for the filtration operation are as follows.
(1) The material of the filtration membrane is polyvinylidene fluoride (PVDF), and the pore diameter is 0.1 μm.
(2) The filtration flux was 4 m / day, and the filtration flow rate was 3.6 m ³ / hour / module.
(3) The ozone concentration during filtration was such that the residual ozone at the inlet of the circulation pump 15 was 1.75 mg / L. At this time, the dissolved ozone concentration on the primary side of the membrane modules 1, 2, 3 was 1.0 mg / L.
(4) The filtration process was continued for 10 minutes.
(5) In the backwashing process, backwashing and air scrubbing were performed for 30 seconds, and drainage from the primary side outlets of the membrane modules 1, 2, 3 was performed for 60 seconds.
FIG. 2 shows the quality of raw water W1 and the quality of filtered water W3.

The conditions of the circulating cleaning operation are as follows.
(6) The discharge rate of the circulation pump 15 was 3.6 m ³ / hour · module.
(7) The ozone concentration during cleaning was such that the residual ozone at the inlet of the circulation pump 15 was 3.0 mg / L. At this time, the dissolved ozone concentration at the outlets of the membrane modules 1, 2, and 3 was 2.0 mg / L.
(8) The circulation cleaning step was continued for 3 hours.
FIG. 3 shows the filtration operation conditions immediately before the circulation cleaning operation and the filtration operation conditions immediately after the circulation cleaning operation.
By the circulation cleaning operation, the differential pressure was reduced, the output of the circulation pump 15 was reduced, and the power consumption of the circulation pump 15 was reduced by about 16%.

  According to the membrane treatment apparatus 100 of Example 1, since ozone is used in both the filtration process and the circulation washing process, ozone-related equipment can be used for both filtration and washing, and the utilization efficiency of the equipment can be improved. Further, since the ozone-treated water W2 is circulated through the primary side of the membrane modules 1, 2, and 3, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In the film processing apparatus 100 of the first embodiment, the circulation cleaning operation may be changed as follows.
[Circulation cleaning operation]
-Circulation cleaning process-
Circulating and washing part or all of the membrane modules 1, 2, and 3.
The valve V _{X + 8} of the membrane module X (X is one, two or three of 1, 2, 3) whose differential pressures ΔP1, ΔP2, ΔP3 are equal to or higher than the first threshold value is closed. Thereby, regarding the membrane module X, the ozone treatment W2 circulates between the ozone reaction tower 11, the ozone treatment water tank 14, and the primary side of the membrane module X without being filtered. For membrane modules other than membrane module X, the filtration process is continued.
The ozone concentration measured by the ozone densitometer 16 is adjusted to the ozone concentration during circulation cleaning by adjusting the injection amount of ozonized air.
The ozone concentration at the time of washing may be higher than the ozone concentration at the time of filtration, but may be the ozone concentration at the time of filtration. Even with the ozone concentration at the time of filtration, the membrane module X that is not filtered can provide a cleaning effect.

If the circulation washing process is continued for 0.5 to 5 hours, the valve V _{X + 8} is opened and the process returns to the filtration process.

  According to the second embodiment, the filtrate W3 can be supplied from a membrane module other than the membrane module X even during the circulation cleaning operation of the membrane module X.

FIG. 4 is an explanatory diagram of a configuration of the film processing apparatus 200 according to the third embodiment.
The membrane treatment apparatus 200 includes a raw water pump 10 that takes in raw water W1 such as sewage secondary treated water and tap raw water, an ozone reaction tower 11 that converts raw water W1 into ozonized water W2 by ozonized air, and ozonized air. The ozone generator 12 to be generated, the waste ozone treatment tower 13 for detoxifying the ozone discharged from the ozone reaction tower 11, the ozone treatment water tank 14 for storing the ozone treatment water W2, and the ozone treatment water W2 in the filtration process. A circulation pump 15 for circulation, an ozone concentration meter 16 for measuring the ozone concentration of the ozone treated water W2 at the inlet of the circulation pump 15, and the ozone treated water W2 passed through the primary side are filtered and secondary The membrane modules 1, 2, 3 that allow the filtrate W3 to permeate to the side, and the ozone-treated water W2 that has not been filtered and exited from the primary side of the membrane modules 1, 2, 3, are returned to the ozone-treated water tank 14. The ozone concentration at the inlet of the circulation path 18c, the short path 17d and the circulation pump 18 for circulating the ozone treated water W2 between the ozone reaction tower 11 and the ozone treated water tank 14 in the circulation cleaning step, and the circulation pump 18 is measured. Ozone concentration meter 19 for filtering, filtered water tank 20 for storing filtered water W3, and backwash pump for supplying back filtered water W3 from filtered water tank 20 to the secondary side of membrane modules 1, 2, 3 21, a drainage tank 23 for storing backwash drainage, a compressor 24 for supplying air to the primary side of the membrane modules 1, 2, 3 for air scrubbing, and a production amount of filtered water W 3, purified water and reclaimed water In order to alleviate the unbalance in demand, the water tank 30 for storing the filtered water W3, the flow rate, the differential pressure of the membrane modules 1, 2 and 3, the ozone concentration, the amount of water stored, etc. are monitored. 10,15,18,21 and ozone generator 12 and compressor 24 and valves V1, V3~V19, and a control unit 40 for operating the V21～V24. In addition, FI in a figure is a flowmeter.
Although not shown, the primary side inlet pressures p11, p21, and p31, the primary side outlet pressures p12, p22, and p32, and the secondary side outlet pressures p13, p23, and p33 are measured. It has a pressure gauge.

  The filtration membranes of the membrane modules 1, 2, 3 are, for example, external pressure hollow fiber membranes having ozone resistance. The pore size of the filtration membrane is 0.45 μm or less.

  Next, the operation will be described. As an initial state, the pumps 10, 15, 18, 21 and the ozone generator 12 and the compressor 24 are stopped, and the valves V1, V3 to V19, and V21 to V24 are closed. To do.

[Start operation]
-Circulation process before filtration-
The raw water pump 10 is operated to pass the raw water W1 through the ozone reaction tower 11. Further, the ozone generator 12 is operated to inject ozonized air into the ozone reaction tower 11. Further, the valve V21 is opened and the circulation pump 18 is operated.
The ozone-treated water W <b> 2 that has been subjected to ozone treatment in the ozone reaction tower 11 flows into the ozone-treated water tank 14. The ozone-treated water W2 stored in the ozone-treated water tank 14 returns to the ozone reaction tower 11 through the short path 17d. Accordingly, the ozone treated water W2 circulates between the ozone reaction tower 11 and the ozone treated water tank 14.
When the inflow amount of the raw water W1 and the injection amount of ozonized air are adjusted and the ozone concentration measured by the ozone concentration meter 19 reaches the ozone concentration during filtration, the operation is shifted to normal operation.
The ozone concentration during filtration is such that the residual ozone concentration at the outlets of the membrane modules 1, 2 and 3 during normal operation is 1.0 to 2.0 mg / L. This is to prevent clogging in the membrane modules 1, 2 and 3 in combination with sterilization or inactivation of bacteria and protozoa, removal of chromaticity, and reduction of COD (chemical oxygen demand). It is.

[Normal operation]
-Filtration process-
The valves V1, V3 to V11 are opened, and the circulation pump 15 is operated.
The ozone-treated water W2 flows from the ozone-treated water tank 14 into the primary side inlet of the membrane modules 1, 2 and 3, flows out of the primary-side outlet, and returns to the ozone-treated water tank 14 via the return path 17c. Accordingly, the ozone-treated water W2 circulates between the ozone reaction tower 11 and the ozone-treated water tank 14 and between the ozone-treated water tank 14 and the primary side of the membrane modules 1, 2, and 3.
Part (usually over 50%) of the ozone-treated water W2 passing through the primary side of the membrane modules 1, 2, 3 permeates the membrane from the primary side to the secondary side to become filtered water W3, and the rest is the ozone-treated water tank 14 Return to.
The filtered water W3 is stored in the filtered water tank 20. The filtered water W3 that overflows the filtered water tank 20 is stored in the water tank 30.

During the filtration step, differential pressures ΔP1, ΔP2, and ΔP3 in the membrane modules 1, 2, and 3 are obtained.
ΔP1 = (p11 + p12) / 2−p13
ΔP2 = (p21 + p22) / 2−p23
ΔP3 = (p31 + p32) / 2−p33
It is. If all of the differential pressures ΔP1, ΔP2, and ΔP3 are equal to or lower than the first threshold value (for example, 0.20 MPa), the filtration process is continued. If all of the differential pressures ΔP1, ΔP2, and ΔP3 are equal to or higher than the second threshold value (for example, 0.25 MPa). The chemical cleaning is requested, and if any one of the differential pressures ΔP1, ΔP2, and ΔP3 is between the first threshold value and the second threshold value, the process shifts to the circulation cleaning operation.
If a filtration process is continued for 10 to 20 minutes, it will transfer to a backwash process.

-Backwash process-
The membrane modules 1, 2, 3 are backwashed in order.
For example, when the membrane module X (X is one of 1, 2 and 3) is back-washed, the valve V _{16 + X} is opened and the valves V _{2 + X} , V _{5 + X} , and V _{8 + X} are closed. Further, the valves V12 and V11 _{+ X} are opened, and the backwash pump 21 is operated. Thereby, the filtrate W3 permeate | transmits back from the secondary side of the membrane module X to a primary side, and the backwashing of a membrane is performed.
At the same time, the valve V _{21 + X} is opened and the compressor 24 is operated. Thereby, air scrubbing cleaning is performed.
When backwashing and air scrubbing are continued for 30 seconds to 3 minutes, the backwashing pump 21 and the compressor 24 are stopped, and the valves V21 _{+ X} , V12, and V12 _{+ X} are closed. Thereafter, the valve V2 _{+ X} is opened, the circulation pump 15 is operated, and the backwash drainage on the primary side of the membrane module X is drained from the valve V16 _{+ X} to the drainage tank 23. After 30 to 60 seconds, the valve V _{16 + X} is closed, the valves V _{5 + X} and V _{8 + X} are opened, and the process returns to the filtration process.

[Circulation cleaning operation]
-Circulation cleaning process-
The membrane modules 1, 2, and 3 are circulated and washed simultaneously.
The raw water pump 10 is stopped and the valves V9 to V11 are closed. Thereby, the ozone treatment W2 circulates between the ozone reaction tower 11 and the ozone treatment water tank 14 and between the ozone treatment water tank 14 and the primary side of the membrane modules 1, 2, 3 without being filtered.
The ozone concentration measured by the ozone densitometer 16 is adjusted to the ozone concentration during circulation cleaning by adjusting the injection amount of ozonized air.
The ozone concentration during cleaning is such that the residual ozone concentration at the inlet of the circulation pump 15 becomes 1.0 to 5.0 mg / L.
When the circulation cleaning process is continued for 0.5 to 5 hours, the valves V9 to V11 are opened, the raw water pump 10 is operated, and the process returns to the filtration process.

  According to the membrane treatment apparatus 200 of Example 3, since ozone is used in both the filtration process and the circulation cleaning process, ozone-related equipment can be used for both filtration and washing, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water W2 is circulated through the primary side of the membrane modules 1, 2, and 3, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In the film processing apparatus 200 of the third embodiment, the circulation cleaning operation may be changed as follows.
[Circulation washing operation]
-Circulation cleaning process-
Circulating and washing part or all of the membrane modules 1, 2, and 3.
The valve V _{X + 8} of the membrane module X whose differential pressures ΔP1, ΔP2, and ΔP3 are equal to or higher than the first threshold value is closed (X is one, two, or three of 1, 2, and 3). Thereby, regarding the membrane module X, the ozone treatment W2 is circulated between the ozone-treated water tank 14 and the primary side of the membrane module X without being filtered. For membrane modules other than membrane module X, the filtration process is continued.
The ozone concentration measured by the ozone densitometer 16 is adjusted to the ozone concentration during circulation cleaning by adjusting the injection amount of ozonized air.
The ozone concentration at the time of washing may be higher than the ozone concentration at the time of filtration, but may be the ozone concentration at the time of filtration. Even with the ozone concentration at the time of filtration, the membrane module X that is not filtered can provide a cleaning effect.

If the circulation washing process is continued for 0.5 to 5 hours, the valve V _{X + 8} is opened and the process returns to the filtration process.

  According to the fourth embodiment, the filtered water W3 can be supplied from a membrane module other than the membrane module X even in the circulation cleaning operation of the membrane module X.

FIG. 5 is an explanatory diagram of a configuration of a film processing apparatus 300 according to the fifth embodiment.
The membrane treatment apparatus 300 includes a raw water pump 10 that takes in raw water W1 such as sewage secondary treated water and tap raw water, an ozone reaction tower 11 that converts raw water W1 into ozonized water W2 by ozonized air, and ozonized air. The ozone generator 12 to be generated, the waste ozone treatment tower 13 for detoxifying the ozone discharged from the ozone reaction tower 11, the ozone treatment water tank 14 for storing the ozone treatment water W2, and the ozone treatment water W2 in the filtration process. A circulation pump 15 for circulation, an ozone concentration meter 16 for measuring the ozone concentration of the ozone treated water W2 at the inlet of the circulation pump 15, and the ozone treated water W2 passed through the primary side are filtered and secondary The membrane modules 1, 2, 3 that allow the filtered water W3 to permeate to the side, and the ozone-treated water W2 that has not been filtered and exited from the primary side of the membrane modules 1, 2, 3 are returned to the ozone reaction tower 11 The ozone concentration at the inlet of the path 17a, the short path 17d for circulating the ozone treated water W2 between the ozone reaction tower 11 and the ozone treated water tank 14 in the circulation cleaning step, and the inlet of the circulation pump 18 is measured. Ozone concentration meter 19 for filtration, filtered water tank 20 for storing filtered water W3, and backwash pump 21 for supplying back filtered water W3 from filtered water tank 20 to the secondary side of membrane modules 1, 2, and 3 And a drainage tank 23 for storing backwash wastewater, a compressor 24 for supplying air to the primary side of the membrane modules 1, 2 and 3 and performing air scrubbing, a production amount of filtered water W3, purified water and reclaimed water as A water tank 30 for storing filtered water W3 in order to alleviate the unbalance in demand, and a pump for monitoring the flow rate, the differential pressure of membrane modules 1, 2, 3 and the ozone concentration, the amount of water stored, etc. 0,15,18,21 and ozone generator 12 and compressor 24 and valves V1, V3~V19, and a control unit 40 for operating the V21～V24. In addition, FI in a figure is a flowmeter.
Although not shown, the primary side inlet pressures p11, p21, and p31, the primary side outlet pressures p12, p22, and p32, and the secondary side outlet pressures p13, p23, and p33 are measured. It has a pressure gauge.

  The filtration membranes of the membrane modules 1, 2, 3 are, for example, external pressure hollow fiber membranes having ozone resistance. The pore size of the filtration membrane is 0.45 μm or less.

  Next, the operation will be described. As an initial state, the pumps 10, 15, 18, 21 and the ozone generator 12 and the compressor 24 are stopped, and the valves V1, V3 to V19, and V21 to V24 are closed. To do.

[Start operation]
-Circulation process before filtration-
The raw water pump 10 is operated to pass the raw water W1 through the ozone reaction tower 11. Further, the ozone generator 12 is operated to inject ozonized air into the ozone reaction tower 11. Further, the valve V21 is opened and the circulation pump 18 is operated.
The ozone-treated water W <b> 2 that has been subjected to ozone treatment in the ozone reaction tower 11 flows into the ozone-treated water tank 14. The ozone-treated water W2 stored in the ozone-treated water tank 14 returns to the ozone reaction tower 11 through the short path 17d. Accordingly, the ozone treated water W2 circulates between the ozone reaction tower 11 and the ozone treated water tank 14.
When the inflow amount of the raw water W1 and the injection amount of ozonized air are adjusted and the ozone concentration measured by the ozone concentration meter 19 reaches the ozone concentration during filtration, the operation is shifted to normal operation.
The ozone concentration during filtration is such that the residual ozone concentration at the outlets of the membrane modules 1, 2 and 3 during normal operation is 1.0 to 2.0 mg / L. This is to prevent clogging in the membrane modules 1, 2 and 3 in combination with sterilization or inactivation of bacteria and protozoa, removal of chromaticity, and reduction of COD (chemical oxygen demand). It is.

[Normal operation]
-Filtration process-
The valves V1, V3 to V11 are opened, and the circulation pump 15 is operated.
The ozone-treated water W2 flows from the ozone-treated water tank 14 into the primary inlet of the membrane modules 1, 2, and 3, flows out of the primary outlet, and returns to the ozone reaction tower 11 through the return path 17a. Accordingly, the ozone-treated water W2 circulates between the ozone reaction tower 11, the ozone-treated water tank 14, and the primary sides of the membrane modules 1, 2, and 3.
Part of the ozone-treated water W2 that passes through the primary side of the membrane modules 1, 2, 3 (usually over 50%) permeates the membrane from the primary side to the secondary side to become filtered water W3, and the rest is the ozone reaction tower 11 Return to.
The filtered water W3 is stored in the filtered water tank 20. The filtered water W3 that overflows the filtered water tank 20 is stored in the water tank 30.

During the filtration step, differential pressures ΔP1, ΔP2, and ΔP3 in the membrane modules 1, 2, and 3 are obtained.
ΔP1 = (p11 + p12) / 2−p13
ΔP2 = (p21 + p22) / 2−p23
ΔP3 = (p31 + p32) / 2−p33
It is. If all of the differential pressures ΔP1, ΔP2, and ΔP3 are equal to or lower than the first threshold value (for example, 0.20 MPa), the filtration process is continued. If all of the differential pressures ΔP1, ΔP2, and ΔP3 are equal to or higher than the second threshold value (for example, 0.25 MPa). The chemical cleaning is requested, and if any one of the differential pressures ΔP1, ΔP2, and ΔP3 is between the first threshold value and the second threshold value, the process proceeds to the circulation cleaning operation.
If a filtration process is continued for 10 to 20 minutes, it will transfer to a backwash process.

-Backwash process-
The membrane modules 1, 2, 3 are backwashed in order.
For example, when the membrane module X (X is one of 1, 2 and 3) is back-washed, the valve V _{16 + X} is opened and the valves V _{2 + X} , V _{5 + X} , and V _{8 + X} are closed. Further, the valves V12 and V11 _{+ X} are opened, and the backwash pump 21 is operated. Thereby, the filtrate W3 permeate | transmits back from the secondary side of the membrane module X to a primary side, and the backwashing of a membrane is performed.
At the same time, the valve V _{21 + X} is opened and the compressor 24 is operated. Thereby, air scrubbing cleaning is performed.
When backwashing and air scrubbing are continued for 30 seconds to 3 minutes, the backwashing pump 21 and the compressor 24 are stopped, and the valves V21 _{+ X} , V12, and V12 _{+ X} are closed. Thereafter, the valve V2 _{+ X} is opened, the circulation pump 15 is operated, and the backwash drainage on the primary side of the membrane module X is drained from the valve V16 _{+ X} to the drainage tank 23. After 30 to 60 seconds, the valve V _{16 + X} is closed, the valves V _{5 + X} and V _{8 + X} are opened, and the process returns to the filtration process.

[Circulation washing operation]
-Circulation cleaning process-
The membrane modules 1, 2, and 3 are circulated and washed simultaneously.
The raw water pump 10 is stopped and the valves V9 to V11 are closed. Thereby, the ozone treatment W2 circulates between the ozone reaction tower 11, the ozone treatment water tank 14, and the primary sides of the membrane modules 1, 2, 3 without being filtered.
The ozone concentration measured by the ozone densitometer 16 is adjusted to the ozone concentration during circulation cleaning by adjusting the injection amount of ozonized air.
The ozone concentration during cleaning is such that the residual ozone concentration at the inlet of the circulation pump 15 becomes 1.0 to 5.0 mg / L.
When the circulation cleaning process is continued for 0.5 to 5 hours, the valves V9 to V11 are opened, the raw water pump 10 is operated, and the process returns to the filtration process.

  According to the membrane treatment apparatus 300 of the fifth embodiment, ozone is used in both filtration and cleaning because ozone is used in both the filtration process and the circulation cleaning process, and the utilization efficiency of the equipment can be improved. Further, since the ozone treated water W2 is circulated through the primary side of the membrane modules 1, 2, and 3, ozone can be used without waste and the ozone concentration on the primary side can be accurately controlled.

In the film processing apparatus 300 of the fifth embodiment, the circulation cleaning operation may be changed as follows.
[Circulation washing operation]
-Circulation cleaning process-
A part or all of the membrane modules 1, 2, 3 is circulated and washed.
The valve V _{X + 8} of the membrane module X whose differential pressures ΔP1, ΔP2, and ΔP3 are equal to or higher than the first threshold value is closed (X is one, two, or three of 1, 2, and 3). Thereby, regarding the membrane module X, the ozone treatment W2 circulates between the ozone reaction tower 11, the ozone treatment water tank 14, and the primary side of the membrane module X without being filtered. For membrane modules other than membrane module X, the filtration process is continued.
The ozone concentration measured by the ozone densitometer 16 is adjusted to the ozone concentration during circulation cleaning by adjusting the injection amount of ozonized air.
The ozone concentration at the time of washing may be higher than the ozone concentration at the time of filtration, but may be the ozone concentration at the time of filtration. Even with the ozone concentration at the time of filtration, the membrane module X that is not filtered can provide a cleaning effect.

If the circulation washing process is continued for 0.5 to 5 hours, the valve V _{X + 8} is opened and the process returns to the filtration process.

  According to the sixth embodiment, the filtered water W3 can be supplied from a membrane module other than the membrane module X even in the circulation cleaning operation of the membrane module X.

  The membrane treatment method and membrane treatment apparatus of the present invention are used for water treatment using both ozone treatment and membrane filtration.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 2 is a chart showing the quality of raw water and filtered water tested with the membrane treatment apparatus according to Example 1. 3 is a chart showing membrane treatment conditions before and after circulation cleaning tested with the membrane treatment apparatus according to Example 1. FIG. FIG. 6 is an explanatory diagram illustrating a film processing apparatus according to a third embodiment. FIG. 10 is a configuration explanatory view showing a film processing apparatus according to a fifth embodiment.

Explanation of symbols

1, 2 and 3 Membrane module 10 Raw water pump 11 Ozone reaction tower 12 Ozone generator 14 Ozone treated water tank 15 Circulating pump 16 Ozone concentration meter 17a, 17c Return path 17b, 17d Short path 20 Filtration water tank 23 Drain tank 30 Water tank 100, 200,300 Membrane treatment equipment V1-V24 Valve W1 Raw water W2 Ozone treated water W3 Filtration water

Claims (11)

  Filtration process and washing water in which ozone treated water whose ozone concentration is filtered is circulated through the primary side of the membrane module and a part of the ozone treated water is permeated from the primary side to the secondary side of the membrane module During normal operation that repeats the backwashing process of permeating from the secondary side of the membrane module to the primary side, ozone treated water whose ozone concentration is the ozone concentration during circulation cleaning is circulated through the primary side of the membrane module. A membrane treatment method characterized by sandwiching a circulation washing step for washing the membrane module.   2. The membrane treatment method according to claim 1, wherein the ozone concentration during circulation cleaning is made higher than the ozone concentration during filtration.   The membrane treatment method according to claim 1 or 2, wherein a plurality of the membrane modules are installed in parallel, the normal operation is performed in some membrane modules, and the normal operation is stopped in the remaining membrane modules. A film processing method comprising performing a circulation cleaning step.   The membrane treatment method according to any one of claims 1 to 3, wherein the filtration step is stopped when a differential pressure between a primary side and a secondary side of the membrane module is a predetermined value or more during the filtration step. A film processing method comprising performing the circulation cleaning step.   A membrane module; an ozone reaction tower that injects ozone into raw water to produce ozone treated water; an ozone treated water tank that stores the ozone treated water; and And filtering the ozone treated water between the ozone treated water tank and the primary side of the membrane module to permeate a part of the ozone treated water from the primary side to the secondary side of the membrane module to obtain filtered water Circulation means, backwashing means for allowing washing water to permeate from the secondary side to the primary side of the membrane module, the ozone reaction tower and the ozone treatment water tank with the ozone concentration of the ozone treated water being the ozone concentration during circulation washing And a circulation cleaning means for cleaning the membrane module by circulating ozone treated water between the primary sides of the membrane module. Film processing equipment.   A membrane module; an ozone reaction tower that injects ozone into raw water to produce ozone treated water; an ozone treated water tank that stores the ozone treated water; Circulating the ozone treated water between the primary side of the membrane module and passing the ozone treated water from the primary side to the secondary side of the membrane module to obtain filtered water, and washing Backwashing means for allowing water to permeate from the secondary side to the primary side of the membrane module, and ozone treated water between the ozone reaction tower and the ozone treated water tank while setting the ozone concentration of the ozone treated water to the ozone concentration during circulation washing. Circulating and washing the membrane module by circulating ozone treated water between the ozone treated water tank and the primary side of the membrane module Film processing apparatus characterized by comprising a means.   A membrane module; an ozone reaction tower that injects ozone into raw water to produce ozone treated water; an ozone treated water tank that stores the ozone treated water; and And filtering the ozone treated water between the ozone treated water tank and the primary side of the membrane module to permeate a part of the ozone treated water from the primary side to the secondary side of the membrane module to obtain filtered water Circulating means, backwashing means for permeating the wash water from the secondary side to the primary side of the membrane module, and the ozone reaction tower and the ozone treated water tank while the ozone concentration of the ozone treated water is set to the ozone concentration during circulation washing. Circulating ozone treated water between the ozone reaction tower, the ozone treated water tank, and the primary side of the membrane module. Film processing apparatus characterized by comprising a circulating washing means for washing the membrane module Te.   8. The film processing apparatus according to claim 5, wherein the ozone concentration during circulation cleaning is made higher than the ozone concentration during filtration.   The membrane treatment apparatus according to any one of claims 5 to 8, wherein a plurality of the membrane modules are installed in parallel, the filtration circulation means is operated in some membrane modules, and the filtration circulation is performed in the remaining membrane modules. A film processing apparatus characterized in that the circulating cleaning means is operated by stopping the means.   10. The membrane treatment apparatus according to claim 5, wherein the circulation is performed when a differential pressure between a primary side and a secondary side of the membrane module when the filtration circulation unit is operated is equal to or greater than a predetermined value. A film processing apparatus characterized by operating a cleaning means.   The membrane treatment apparatus according to any one of claims 5 to 10, wherein ozone treated water is not supplied to a primary side of the membrane module between the ozone reaction tower and the ozone treated water tank without supplying ozone treated water. A membrane treatment apparatus comprising pre-filtration circulation means for making the ozone concentration of the ozone treated water the ozone concentration during filtration while circulating.

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