JP2003071256A - Membrane washing method and treating method for liquid to be treated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane washing method, or the like, capable of preventing local excess or lack of aeration and stably maintaining uniform washing of the whole of membrane surface of a separation film membrane. SOLUTION: In a treating apparatus 10, a monitoring device 5 for monitoring the aeration state of a liquid level part S of a liquid L0 to be treated in a treating tank 1 is provided above the treating tank 1 installed with a membrane module 2 and a diffuser 70. An image photographed by the monitoring device 5 is outputted to a control device 6 and the existence of bubbles is determines by a light and shade treatment of the image. From this determination result, an amount of aeration at a presumed area unit corresponding to a diffusing unit 7 is taken-in and adjustment of the amount of aeration is carried out based thereon when excess of or lack in the amount of aeration is generated. As a result, local excess or lack in the amount of aeration is made appropriate and a uniform membrane washing can be accomplished.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a membrane cleaning method for cleaning a separation membrane (filtration membrane) used for membrane separation of a liquid to be treated, and a method of treating a liquid to be treated using the method. .

[0002]

2. Description of the Related Art For purification treatment of liquid to be treated (water) containing solid matter, particulate matter, etc., various solid-liquid separation, liquid-liquid separation, etc.
The filtration treatment by membrane separation is widely used, and various separation membranes are applied according to the filtration accuracy (filter size). Examples of the separation membrane include a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, a nanofiltration (NF) membrane, and a reverse osmosis (RO) membrane. Properties of these separation membranes
The shape varies widely depending on the application, and particularly in the purification treatment in which a large amount of liquid to be treated is continuously subjected to membrane separation while biological treatment, for example, a membrane module in which a plurality of membrane elements are collectively arranged is provided in multiple stages. Often provided.

In such a membrane separation, in order to maintain the membrane separation ability, that is, the filtration performance in a good condition for a long period of time, the solid matter or the like which is the filtration residue adhered to or deposited on the surface of the separation membrane is appropriately washed. In recent years, in purification treatment, further improvement in the quality of treated water (purified water) is desired. In addition to purified water, cleaning liquid (water) used for manufacturing precision equipment and semiconductors
Further reduction of the particulate matter contained in is also desired.
In response to such requirements, UF membranes and NF with high filtration accuracy
High-performance membranes capable of cross-flow filtration such as membranes and RO membranes have been widely adopted, and along with this, the importance of membrane cleaning is increasing.

Conventionally, many methods have been put to practical use or proposed as a method for cleaning a separation membrane, which are roughly classified; (1) a method for recovering filtration resistance by backwashing, (2) a surface-active surface of the separation membrane. Examples include a method of cleaning with a cleaning liquid such as an agent, and (3) a method of aerating from below the separation membrane to remove / remove the deposits or deposits on the surface of the separation membrane. Among these, in the aeration cleaning method described in (3) above, in the case of a treatment tank in which membrane separation is performed while biological treatment is performed in an aerobic atmosphere, the aeration device can also be used for membrane cleaning. Since it may not necessarily require a chemical solution, it is excellent in simplicity and cleanability.

[0005]

Generally, the membrane cleaning by aeration cleaning is composed of a single or a plurality of air diffusing units installed below a separation membrane or a membrane module having the same, or a perforated pipe (air diffusing pipe) or the like. It is general that air or the like is discharged from the air diffuser to be brought into contact with bubbles on the surface of the separation membrane. In addition, a method of biologically treating a liquid to be treated with activated sludge in an aerobic atmosphere to obtain treated water (purified water) in combination with membrane separation is widely used. In such a method, a separation membrane or a membrane is used. It is necessary to keep the filtration resistance of the entire module low enough to maintain good filtration performance.
For this reason, in order to realize a uniform aeration state, the configuration, shape, etc. of the membrane module, the number of air diffusers for performing aeration, the rectifier of bubbles, etc., depend on the treatment conditions of the liquid to be treated and the treatment tank. It is set appropriately.

However, even if the apparatus is designed and adjusted so as to achieve such aeration conditions, various factors are combined in the actual treatment of the liquid to be treated, and the aeration state is short-term or long-term. There is also a risk that the discharge of air bubbles from a part of the air diffuser may be insufficient or stopped in some cases. If this happens, local aeration shortage will occur, making uniform cleaning of the separation membrane and its membrane module difficult, leading to an increase in overall filtration resistance, and as a result, the treatment efficiency of the liquid to be treated may decrease. There is.

Therefore, the present invention has been made in view of such circumstances, and prevents local aeration excess / deficiency,
An object of the present invention is to provide a membrane cleaning method capable of stably maintaining uniform cleaning of the entire membrane surface of a separation membrane. Another object of the present invention is to provide a method for treating a liquid to be treated, which can stably maintain a desired membrane separation performance for a long period of time by using the membrane cleaning method of the present invention and can suppress a decrease in treatment efficiency.

[0008]

In order to solve the above problems, a membrane cleaning method according to the present invention is a method for aeration cleaning a separation membrane immersed in a treatment tank to which a liquid to be treated is supplied. The aeration step of aerating the liquid to be treated in the tank from substantially below the membrane separation part having the separation membrane and the aeration state of the liquid surface part of the liquid to be treated are monitored from the outside of the liquid to be treated. Based on the aeration amount (aeration air amount) and / or the aeration amount distribution acquired in the monitoring process and the monitoring process for acquiring the aeration amount and / or the aeration amount distribution in the liquid surface part, part or all of the membrane separation part And an adjusting step of adjusting an aeration amount for the.

In such a membrane cleaning method, in the aeration step, when aeration is performed from substantially below the membrane separation section immersed in the treatment tank, the filtration residue and solids adhered and deposited on the membrane surface due to the membrane separation. And air bubbles come into contact with each other, and the deposits on the film surface are peeled off and removed mainly by a mechanical action, whereby the film surface is aerated and cleaned. After that, the bubbles pass through the membrane separation unit, reach the liquid surface of the liquid to be treated, and are discharged into the gas phase. Thus, the bubbles are continuously supplied to the liquid surface portion, and the bubbling state, that is, the aeration state is constantly formed. Such aeration state of the liquid surface can be observed from outside (outside) of the liquid to be treated.

As described above, the configuration, shape, etc. of the membrane separation unit, or the number of air diffusers for performing aeration, etc. are appropriately set depending on the treatment conditions of the liquid to be treated and the treatment tank, and the entire membrane separation unit is set. It is desirable to perform aeration and cleaning uniformly, but sometimes aeration is unevenly distributed, and in the unlikely event that aeration is reduced or stopped from a part of the air diffuser. This happens when,
A local difference (excess or deficiency) may occur in the aeration amount of the liquid surface of the liquid to be treated.

Therefore, by performing a monitoring step to observe and monitor the aeration state of the liquid surface part and obtain the planar aeration amount distribution, a difference in the aeration amount occurs and its deviation (uneven distribution). Is detected. Further, by acquiring the aeration amount over the entire liquid surface part, it is possible to detect the excess or deficiency of the entire aeration amount for the membrane separation part. The total aeration amount is
It can also be obtained by integrating (integrating) the aeration amount distribution.

Then, the adjustment step is performed, and based on the aeration amount distribution of the liquid surface obtained in the monitoring step, for example, air bubbles to a part of the membrane separation section where the aeration amount is relatively small or large. Adjust the aeration rate by adjusting the supply rate. As a result, the entire membrane separation section can be uniformly aerated and cleaned, and the uniform cleaning state can be maintained. In addition, it is possible to adjust the aeration amount of the entire liquid surface portion as desired.

More specifically, the monitoring step includes an imaging step of imaging the liquid surface portion from the outside of the liquid surface portion, and an area dividing step of dividing the image obtained in the imaging step into a virtual predetermined number of areas. , A bubble determination step of digitizing the image information of the image obtained in the imaging step and determining the presence or absence of bubbles in the image based on the numerical information, and the aeration amount over the entire region based on the determination result of the presence or absence of bubbles And / or an aeration amount acquisition step of obtaining an aeration amount distribution, and an adjustment amount calculation step of calculating an adjustment amount of the aeration amount to a portion corresponding to each region in the membrane separation unit from the aeration amount and / or the aeration amount distribution. In the adjusting step, it is preferable to adjust the aeration amount to a part or all of the membrane separation section based on the adjusting amount.

Either the area dividing step or the bubble determining step may be performed first, or may be performed simultaneously in parallel. The "image information" refers to position information on the image, information about color tones such as color, hue, brightness, luminance, and saturation at each position, or information about distribution of such tone.

With this configuration, the aeration state of the liquid surface can be monitored in a non-contact manner by imaging the liquid surface of the liquid to be processed, and the obtained image can be image-processed.
The aeration amount distribution in virtual region units and / or the aeration amount in the entire region can be acquired. Further, the number of divisions into the virtual area is not particularly limited, for example, when the air diffuser for performing aeration is composed of a plurality of air diffusers, if the number of divisions according to the number of air diffusers, An aeration amount distribution for each aeration unit can be obtained. Furthermore, since the adjustment amount (that is, the adjustment amount) of the aeration amount is calculated based on the aeration amount and / or the distribution of the aeration amount, there is an advantage that the adjustment of the aeration amount can be performed reliably and easily.

Further, in the bubble determination step, it is preferable to use information on the brightness or the brightness on the image as the image information. Here, according to the knowledge of the inventor, when a captured image of a liquid surface part in an aerated state is displayed in gray scale, the brightness on the image varies depending on the presence or absence of air bubbles (presence or absence), specifically, The brightness of the image part where bubbles are present is
It was confirmed that the size tended to be larger (the degree of white color was higher) as compared with the part without bubbles. Furthermore, it was confirmed that the area ratio of light and dark on the image differs depending on the amount of aeration, that is, there is a correlation between the area of the'bright 'part on the image and the amount of aeration.

That is, the bubbles on the image can be identified by "brightness", and as a result, the amount of bubbles and thus the amount of aeration can be obtained from the area of the area where the bubbles are present. Further, depending on the color model used in the image processing, it is possible to discriminate the bubbles not only by the brightness but also by the brightness. For example, general-purpose R
In the processing by the GB model (mode), the brightness can be defined by the brightness, or the general-purpose L that can express black and white by the gradation of the brightness.
^{In the *} a ^* b model (YCbCr model) and the like, it is possible to specify the brightness according to the brightness. The same applies to the case where the original captured image is grayscale. For example, the brightness from black to white is set to a numerical value of 0 to 256 gradations, a numerical value of a percentage (%), or a numerical value of monochrome two gradations. It is possible to adopt a general method such as

More specifically, for example, first, before the film cleaning method is performed, an image of the liquid surface portion in an aerated state is acquired, and the boundary value of brightness or luminance depending on the presence or absence of bubbles or its range or range. A threshold value (hereinafter, collectively referred to as “discrimination setting value”) is set in advance, and in the bubble discrimination step, the digitized brightness or luminance on the image (hereinafter, referred to as “actual value such as brightness”) is set. A comparison is made with the set value for discrimination. The actual bubble value is digitized, for example, on a pixel-by-pixel basis on the image, and a comparison operation is performed for each pixel.

At this time, when the measured bubble value is "brighter" (white) value than the set value for determination, it is determined to be a bubble portion, and conversely, when it is "dark" (black) value, it is determined not to be a bubble portion. it can. In particular, when the binarization process is adopted, it is possible to discriminate bubbles in white or black, which is a simpler process. Then, in the aeration amount acquisition step, the number of pixels determined to have bubbles is integrated for each region or the entire region, and the obtained integrated value is regarded as the bubble amount, that is, the aeration amount, or the integrated value is multiplied by a predetermined factor. The amount of aeration can be calculated by performing correction such as.

Further, in the adjustment amount calculation step,
Aeration amount according to the difference between the actual measurement value of the aeration amount obtained for each area and the preset value of the aeration amount set beforehand, or the average value of the aeration amount obtained for each area It is more preferable to calculate the adjustment amount of.

In this way, when the measured value of the aeration amount in each region is below the set value or average value of the aeration amount, the adjustment amount is set so as to increase the aeration amount in that region, and conversely the former. If the value exceeds the latter, the adjustment amount is calculated so that the aeration amount to the area is reduced. This adjustment amount is calculated according to the difference based on the actual measurement value of the aeration amount, and according to this adjustment amount, by adjusting the aeration amount to the region corresponding to the region in the membrane separation unit, the aeration amount for the whole membrane separation unit is adjusted. The uniform cleaning can be promoted, and the aeration amount can be controlled more easily and surely.

Furthermore, in the imaging step, the liquid surface portion is imaged continuously or intermittently, and in the area dividing step and / or the bubble discrimination step, a plurality of images sampled from the plurality of images obtained in the imaging step are sampled. It is useful to use the image of.

The aeration state of the liquid surface of the liquid to be treated usually changes moment by moment, and it is desirable to monitor continuously or intermittently in the monitoring step. In this case, if one image at a certain moment is processed to determine the bubbles and thus the aeration amount, it may be difficult to accurately grasp the state of the liquid surface portion which is not constant with time in some cases.

On the other hand, a plurality of images sampled at fixed time intervals from images obtained by continuously or intermittently capturing the liquid surface portion are used in the region division step and / or the bubble determination step. As a result, the time average value of the aeration amount at the liquid surface portion can be obtained. Therefore, it is possible to grasp the aeration state of the liquid surface portion more accurately and in accordance with the actual condition. Further, by shortening the time interval of image sampling, it becomes possible to adjust the aeration amount in a state close to real time.

Further, as an apparatus for effectively carrying out the membrane cleaning method of the present invention, an apparatus for aerobically cleaning a membrane separation section having a separation membrane provided in a treatment tank into which a liquid to be treated is supplied. There is an aeration part installed below the membrane separation part to aerate the liquid to be treated in the treatment tank, and an aeration state at the liquid surface part of the liquid to be treated provided outside the liquid to be treated. And an aeration amount and / or an aeration amount distribution acquired by the monitoring unit, which are connected to the aeration unit and the monitoring unit for monitoring the aeration amount and / or acquiring the aeration amount and / or the aeration amount distribution on the liquid surface. Based on the above, it is preferable to use the one that includes an adjustment unit that adjusts the aeration amount for a part or all of the membrane separation unit.

Further, the monitoring section has an image pickup section for picking up an image of the liquid level section from the outside of the liquid level section, and the image obtained by the image pickup section is subjected to image processing to detect the presence or absence of bubbles in the image. It is preferable that the aeration amount and / or the aeration amount distribution in the liquid surface portion be acquired based on the determination result.

Further, the method for treating the liquid to be treated according to the present invention is suitable for using the membrane cleaning method of the present invention, and is a method for biologically treating the liquid to be treated with activated sludge, which contains activated sludge. And a supply step of supplying the liquid to be treated to a treatment tank having a membrane separation unit having a separation membrane, and a treatment process of performing the membrane separation of the liquid to be treated by the membrane separation unit while carrying out the membrane cleaning method according to the present invention. It is characterized by being provided.

Further, as an apparatus for effectively carrying out the method for cleaning a liquid to be treated of the present invention, the liquid to be treated is biologically treated with activated sludge and membrane-separated with a separation membrane. A treatment tank containing a liquid to be treated, a membrane separation unit arranged in the treatment tank and having a separation membrane, and a membrane cleaning apparatus for effectively implementing the above-described membrane cleaning method of the present invention. It is useful to use the one provided with.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The same elements will be denoted by the same reference symbols, without redundant description. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. The dimensional ratios in the drawings are not limited to the illustrated ratios.

FIG. 1 is a sectional view schematically showing the configuration of a preferred embodiment of a treatment apparatus for a liquid to be treated, which is equipped with a membrane cleaning apparatus for effectively carrying out the membrane cleaning method according to the present invention. 2 is a sectional view taken along line II-II in FIG. The treatment apparatus 10 is an immersion type membrane separation apparatus for carrying out biological treatment and membrane separation of the liquid to be treated L0 in parallel, and a membrane module 2 having a plurality of separation membranes such as immersed flat membranes in the treatment tank 1.
(Membrane separation part) is provided.

The membrane module 2 is connected to a filtration pump 3 provided outside the processing tank 1. Further, an air diffuser 70 (aeration unit) connected to the blower 4 via a pipe provided with the electric control valve 8 is installed at the bottom of the processing tank 1. The air diffuser 70 is provided with a plurality of air diffuser units 7 at predetermined intervals, and the electric control valve 8 is provided in each of the pipelines provided with the plurality of air diffuser units 7 arranged in the same direction. It is provided (see FIG. 2). Each air diffuser unit 7 has a large number of fine holes, and a large number of bubbles K are discharged to the liquid L0 to be treated in the treatment tank 1 so that the entire membrane module 2 is aerated. There is.

Further, each electric control valve 8 has a liquid L0 to be treated.
A control device 6 connected to a monitoring device 5 (monitoring part) installed above the processing tank 1 so as to face the liquid surface S of the above is connected. The monitoring device 5 has an image pickup unit such as a TV camera and picks up an image of the entire liquid surface S. The image pickup unit employs, for example, an image pickup sensor having a plurality of pixels such as CCD and CMOS. The captured image is output to the control device 6.

As will be described later, the control device 6 records and processes the picked-up image, and outputs a valve opening signal based on the processing result to the electric control valve 8.
Then, the amount of bubbles emitted from the air diffuser 70 is adjusted according to the valve opening degree of the electric control valve 8. In this way, the control device 6 and the electric control valve 8 constitute an adjusting unit, and the adjusting unit, the monitoring device 5, and the air diffusing device 7 are provided.
A membrane cleaning device is constructed from 0.

FIG. 3 is a perspective view schematically showing a main part of another embodiment of a treatment apparatus for a liquid to be treated, which is provided with another membrane cleaning apparatus for effectively carrying out the membrane cleaning method according to the present invention ( It is a partial configuration diagram). 1 and 2 except that an electric control valve V _ij is provided between each air diffusion unit 7 and an electric control valve 8 installed in a pipe to which the air diffusion unit 7 is connected. The processing device 10 shown in FIG.

Further, the control device 6 has an input / output interface.
A chair 61 and a storage / calculation unit 63 connected to the chair 61 are provided.
And each electric control valve V_ijAnd the monitoring device 5
Interface 61. Monitoring device 5
The obtained captured image is passed through the input / output interface 61.
Is input to the storage / calculation unit 63, and stored in the storage / calculation unit 63.
Input / output of the processing signal (the valve opening adjustment signal described later)
Each electric control valve V through the interface 61_ijIs output to
It In this way, the control device 6 and the electric control valve V _ijFrom key
The adjusting unit is configured, and the adjusting unit, the monitoring device 5, and the scattering unit are configured.
A film cleaning device is constituted by the air device 70.

An example of the method for cleaning a film and the method for treating a liquid to be treated according to the present invention using the treatment apparatus 20 thus constructed will be described. Here, FIG. 4 is a flow chart showing an example of a specific procedure of the film cleaning method in the method for treating a liquid to be treated according to the present invention. Further, FIG. 5 is a plan view schematically showing the aeration state in the liquid surface portion S.

The operation of the processing apparatus 20 is started, and first, the liquid L0 to be processed is supplied into the processing tank 1 (supply step). A predetermined amount of the liquid to be treated L0 is stored and the membrane module 2 is immersed in the liquid to be treated L0, and air is blown from the blower 4 to open the electric control valves 8 and V _ij at a predetermined opening degree to scatter. Aeration from the air device 70 is started (step W1; aeration process). Thereby, the liquid L0 to be treated is aerated and agitated, and the aerobic treatment of the liquid L0 to be treated is performed by the activated sludge. At the same time, the filtration pump 3 is operated to perform the membrane separation by the membrane module 2 while continuously and continuously supplying the liquid to be treated L0, and the treated liquid L1 is discharged to the outside of the treatment tank 1. Treated liquid L1
May be subjected to other processing as necessary.

At this time, the membrane module 2 is accompanied by the membrane separation.
The solid content, which is a filtration residue, adheres to and accumulates on the film surface of No. 1, but due to aeration from the air diffuser 70, the air bubbles and the adherent come into contact with each other to remove and remove the adherent, and the liquid L0 to be treated is treated. The membrane cleaning of the separation membrane is performed at the same time as the aerobic treatment (biological treatment).

On the other hand, along with the operation of the air diffuser 70, the monitoring device 5 is operated to start monitoring the liquid surface portion S of the liquid L0 to be treated (step S1), and the liquid surface portion S is kept from above for a predetermined time t.
(For example, a unit of seconds, a unit of minutes, etc.) is imaged (step S
2; imaging step). For the imaging of the liquid surface portion S, for example, a moving image may be continuously or intermittently acquired, or a still image may be continuously or intermittently acquired as in stroboscopic photography. Next, the data of the captured image is input to the control device 6, and the captured image is sampled to obtain a plurality of sampled images αn (step S3).

Next, for each sampled image αn, information such as brightness, luminance, and hue is digitized for each pixel P, and position information is assigned to each pixel (step S4). Here, each pixel P
An example will be described in which image processing is performed on lightness or darkness, that is, lightness M on an image in RGB mode for _lm (subscripts l and m indicate two-dimensional position information of pixels). Further, the brightness M of each pixel P _lm in each sampling image αn
Is integrated over time (specifically, information of all the sampled images αn is integrated) and divided by time t to calculate an average value (step S4). Thereby, the time average value of the brightness M of the captured image at the imaging time t of the liquid surface portion S is obtained.

Next, the image in which the two-dimensional distribution information of the brightness M is extracted is reconstructed from the obtained time average value of the brightness M and the position information of each pixel P _lm (step S5). Further, this reconstructed image is divided into virtual regions corresponding to the installation site of the air diffusion unit 7 (step S6; region dividing step). Specifically, for example, as shown in FIG. 5, a planar area R _ij (subscripts i and j are virtual areas) in which the individual air diffusing units 7 are respectively included when viewed from above the liquid surface S. (Indicates the two-dimensional position of)).

Next, each region R_ijOf air bubbles in
And calculate the amount of bubbles and thus the amount of aeration from the discrimination result.
(Step S7; bubble determination step and aeration amount acquisition step
Also doubles as). When distinguishing bubbles, first
Cell P_lmBinarizes the brightness of. Normally in RGB mode
Is a numerical value within the range of 0 to 255 and is stored in advance.
.For distinguishing between light and dark (black and white) stored in the computing unit 63
Setting value and each pixel P _lmCompare the measured values such as brightness of
If it is more than the judgment value, it is set to “0: White” and exceeds the judgment value.
If this is the case, it will be “1: Black”.

Next, the number of pixels having a 0 value in each region R _ij is integrated and standardized by the total number of pixels to obtain an index of the amount of bubbles in each region R _ij . A factor considering the arrangement of the region R _ij , the distance of the air diffuser unit 7 from the blower 4, and the like are corrected to this index to obtain the aeration amount index D _ij . Thus
It is possible to obtain the aeration amount over the entire region Ra by acquiring the aeration amount distribution in each region R _ij and integrating these.

Further, the average value Dav of the aeration amount index is calculated by dividing the value obtained by integrating the aeration amount index D _ij of each region R _ij for all the regions Ra by the number of regions (i × j) (step S).
8). Next, each aeration index D _ij and their average value Dav
Are compared, the difference between the two is determined, and the adjustment amount of the aeration amount is calculated if necessary (step S9; adjustment amount calculation step). In the determination, the difference between the two is calculated, and when the absolute value of the difference exceeds a predetermined allowable amount, the adjustment amount of the aeration amount according to the difference is calculated.

Specifically, for example, the correspondence relationship (table, conversion formula, etc.) between the difference value and the adjustment amount of the aeration amount corresponding to the difference value is stored or input in the storage / calculation unit 63 and is actually calculated. One method is to calculate the adjustment amount from the difference value. The control signal of the valve opening degree corresponding to the obtained adjustment amount is input from the storage / calculation unit 63 to the input / output interface 6
1 to output to the corresponding electric control valve V _ij . From this, the adjusted valve opening degree, aeration amount from the air diffuser unit 7 on the line with an electric control valve V _ij is adjusted. As a result, it is possible to adjust the aeration amount in the region R _ij (step W2; adjustment process).

On the other hand, the aeration amount index D _ij and their average value D
If the difference from av is within the allowable amount, step S9 is repeated for all regions Ra, and further, steps S2 to S9 are repeated during the operation period of the air diffuser 70, and thereafter, cleaning of the membrane module 2 and the liquid to be treated are performed. The biological treatment of L0 is completed. In this way, the monitoring process is composed of steps S1 to S9, and the processing process is composed of steps S1 to S9 and steps W1 and W2.

According to the processing apparatus 20 thus constructed, the film cleaning method and the method for processing the liquid to be processed, the monitoring device 5 monitors the entire liquid surface S of the liquid L0 to be processed in a non-contact manner. Then, the controller 6 processes the captured image to determine the presence / absence of bubbles, and based on the determination result, the aeration amount in the liquid surface portion S after a lapse of a certain time and the aeration amount distribution in units of the region R _ij are acquired.

As a result, it is possible to grasp the transition of the aeration state at the liquid surface portion S, and to make a local determination of the amount of aeration. Then, the region R _{ij in} which the amount of aeration is insufficient
It is possible to adjust the aeration amount of the air diffuser unit 7 corresponding to the above, thereby optimizing the aeration amount to be insufficient and averaging the aeration amount in the liquid surface portion S. Therefore, the membrane module 2
The amount of aeration air to the whole is made uniform, and uniform aeration cleaning can be achieved.

Further, by performing the membrane cleaning for adjusting the aeration amount as described above continuously or intermittently during the operation period of the air diffuser 70, that is, during the aerobic treatment of the liquid L0 to be treated, The uniform membrane cleaning can be stably maintained. Therefore, the membrane separation performance of the processing device 20 can be stably exerted for a long period of time, and it is possible to effectively prevent the processing efficiency of the liquid L0 to be processed from decreasing.

Furthermore, since the presence or absence of bubbles can be easily discriminated by the brightness of the image, that is, the brightness or the brightness, complicated image processing is unnecessary. Therefore, it is possible to prevent the algorithm from being simplified and the processing time from excessively increasing. As a result, the aeration amount can be easily feedback-controlled in real time, and uniform cleaning can be achieved more reliably.

Furthermore, in the image processing by the control device 6, the imaged image of the liquid surface portion S is virtually divided into regions R _ij corresponding to the diffuser unit 7, and the aeration amount distribution in units of the regions R _ij is acquired. Since the amount of air diffused for each air diffuser unit 7 can be adjusted by adjusting the valve opening of the electric control valve V _ij provided for each air diffuser unit 7, the uniformity of the membrane cleaning is further enhanced.

Further, since the time average value of the aeration amount at the liquid surface S is calculated using a plurality of images sampled from the images obtained by continuously or intermittently capturing the liquid surface S, The aeration state of the part S can be grasped more accurately and according to the actual condition. Therefore, uniform cleaning of the entire membrane module 2 can be realized more accurately. Further, if the time interval of image sampling or the imaging time t is shortened,
Aeration amount control can be performed in a state closer to real-time processing.

The present invention is not limited to the above-described embodiment, and, for example, the processing apparatus 10 can be used to carry out a film cleaning substantially equivalent to the above-described procedure (see FIG. 4). In this case, the adjustment of the aeration amount is performed in units of the air diffusing unit 7 group on the piping line corresponding to the electric control valve 8. In addition, as a concrete method of the image processing and the numerical processing in steps S2 to S9, other generally used algorithms and processing flows can be applied. In the case where the presence / absence of bubbles is determined by the brightness / darkness brightness / luminance processing. The procedure of is not particularly limited to the one described above. For example, the area division in step S6 may be performed before digitizing the image information in step S4.

Further, the number of divisions of the area R _ij is not limited to that shown in the figure. Furthermore, image processing parameters other than brightness or luminance may be used, for example, using a color image,
A bubble may be identified by performing a general patterning process on the bubble shape. In addition, various imaging filters may be provided in the imaging unit of the monitoring device 5 in order to improve the accuracy of bubble identification.

[0055]

As described above, according to the film cleaning method of the present invention, the aeration state of the liquid surface portion of the liquid to be treated is monitored from the outside, and the aeration amount and / or distribution of the aeration amount on the liquid surface portion can be obtained. Since the aeration amount is adjusted based on the above, it is possible to prevent local excess or deficiency of the aeration amount and to stably maintain uniform cleaning of the entire membrane surface of the separation membrane. Further, according to the method for treating a liquid to be treated according to the present invention, by using the membrane cleaning method of the present invention, desired membrane separation performance can be stably maintained for a long period of time, and a reduction in treatment efficiency of the liquid to be treated can be suppressed. It becomes possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing the configuration of a preferred embodiment of a treatment apparatus for a liquid to be treated, which is equipped with a membrane cleaning apparatus for effectively carrying out a membrane cleaning method according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view (partially configured) schematically showing a main part of another embodiment of a treatment apparatus for a liquid to be treated, which is provided with another membrane cleaning apparatus for effectively carrying out the membrane cleaning method according to the present invention. (Figure)
Is.

FIG. 4 is a flowchart showing an example of a specific procedure of a film cleaning method in the method for treating a liquid to be treated according to the present invention.

FIG. 5 is a plan view schematically showing an aeration state on a liquid surface portion.

[Explanation of symbols]

1 ... Treatment tank, 2 ... Membrane module, 3 ... Filtration pump, 4 ...
Blower, 5 ... Monitoring device (monitoring part), 6 ... Control device (adjusting part), 7 ... Air diffuser unit, 8, V _ij ... Electric control valve (adjusting part) 10, 20 ... Processing device (processing liquid) Processing device),
70 ... Air diffuser (aeration part), L0 ... Liquid to be treated, _Rij ... Region, S ... Liquid surface part.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4D006 GA02 HA93 JA31A JA52A                       KC02 KC14 KE01Q KE30P                       PA01 PB08 PB24 PC62                 4D028 BC17 BD17                 5B057 BA11 CA01 CA02 CA08 CA16                       CB01 CB02 CB06 CB08 CB16                       CE12 DA02 DA11 DB05 DB06                       DB08 DB09 DC22 DC25 DC36                 5L096 AA02 AA03 AA06 BA03 CA02                       DA02 EA43 FA32 FA35 FA59                       GA40 GA41 GA51

Claims (3)

[Claims] 1. A membrane cleaning method for aeration-cleaning a separation membrane immersed in a treatment tank to which a liquid to be treated is supplied, the method comprising: a membrane separation unit having the separation membrane in the liquid to be treated in the treatment tank. An aeration step of aerating substantially from below, and an aeration state in the liquid surface portion of the liquid to be treated, which is being aerated, is monitored from the outside of the liquid to be treated, and the amount of aeration and / or the amount of aeration in the liquid surface portion. Membrane cleaning comprising: a monitoring step of acquiring a distribution; and an adjusting step of adjusting an aeration amount for a part or all of the membrane separation unit based on the aeration amount and / or the aeration amount distribution acquired in the monitoring step. Method. 2. The imaging step, wherein the monitoring step captures an image of the liquid surface portion from the outside of the liquid surface portion; and an area dividing step of dividing the image obtained in the image capturing step into a virtual predetermined number of areas. The image information of the image obtained in the imaging step is digitized, and a bubble determination step of determining the presence / absence of bubbles in the image based on the numerical information, and based on the determination result of the presence / absence of bubbles, the entire area is covered. An aeration amount acquisition step of acquiring an aeration amount and / or an aeration amount distribution, and calculating an adjustment amount of the aeration amount to a portion corresponding to each region of the membrane separation unit from the aeration amount and / or the aeration amount distribution. And an adjustment amount calculation step for adjusting the amount of aeration for part or all of the membrane separation unit based on the adjustment amount. The method for cleaning a membrane according to 1. 3. A method of treating a liquid to be treated, which comprises biologically treating the liquid to be treated with activated sludge, wherein the liquid to be treated is contained in a treatment tank containing a membrane separation unit having a separation membrane and containing the activated sludge. A liquid to be treated comprising: a supply process of supplying; and a treatment process of performing membrane separation of the liquid to be treated by the membrane separation unit while performing the membrane cleaning method according to any one of claims 1 to 5. Processing method.