JP2006205119A - Method for using immersion type membrane separation apparatus and immersion type membrane separation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for using a diffuser of an immersion type membrane separation apparatus and the immersion type membrane separation apparatus. <P>SOLUTION: Air is supplied from an air supply unit 14 to the diffuser 10 for supplying uniformly-dispersed air bubbles to a membrane module 11 for filtering sludge. The supply of the air to be supplied from the air supply unit is controlled by an air supply control unit 15. The air supply control unit 15 has a timer 151 and controls so that air is supplied intermittently from the air supply unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a submerged membrane separation comprising a membrane module for filtering sludge, an air diffuser having an air diffuser for ejecting bubbles from below the membrane module, and an air supply device for supplying air to the air diffuser. The present invention relates to a method for using the apparatus, and more particularly to a method for preventing a reduction in filtration capacity in a submerged membrane separator and a submerged membrane separator.

  Submerged membrane separation activated sludge treatment equipment that performs cross-flow filtration using the flow associated with the rising of bubbles has already been used in many fields as an efficient energy-saving filtration equipment, and activated sludge treatment of various wastewater. It plays an important role for liquid filtration (see, for example, Patent Document 1).

In the submerged membrane separation activated sludge treatment apparatus, it is necessary to disperse bubbles as uniformly as possible in order to effectively use the filtration membrane. For this purpose, various diffusers have been developed so far. For example, to those conventionally used in normal activated sludge treatment, 1) A nozzle made of a rubber elastic body that opens while the air diffuser (air diffuser) is supplying air and automatically closes when stopped What to use (for example, see Patent Document 2) 2) Having a perforated pipe with holes (diffusive portions) of about 10 mm at intervals of several centimeters downward 3) Pipe with open end A relatively small hole of about several millimeters is provided at an interval of about several centimeters in the upward direction, and cleaning (hereinafter referred to as flushing) is performed by periodically flowing a liquid mixture of air and sludge at high speed (for example, 4), and 4) a trough type (for example, see Patent Document 4) in which the bottom surface is opened and a hole or a notch (aeration portion) is provided on the side surface.
Japanese Patent Publication No. 4-70958 JP 2002-273180 A Japanese Patent Laid-Open No. 2002-186991 Japanese Patent Application Laid-Open No. 7-241591

  However, the above air diffuser has the following problems. First, those that use rubber elastic nozzles deteriorate due to the aging of the rubber, the rubber elasticity deteriorates, the diffuser part does not close completely, and the sludge enters the nozzle. There was a problem that the part was blocked. On the other hand, perforated pipes and trough-type pipes have a problem that sludge flows backward and enters from the diffuser, and the diffuser is blocked by drying and solidifying inside the diffuser. When the air diffuser is blocked, an appropriate cross flow cannot be obtained, resulting in a rapid decrease in filtration capacity. In addition, those that perform regular flushing require very high installation accuracy for the air diffuser, and the pressure distribution in the air diffuser is biased, so the flow rate of air ejected from the air diffuser changes. In some cases, it is difficult to uniformly disperse the bubbles. Even when the bubbles are not uniformly dispersed, an appropriate cross flow cannot be obtained, and there is a problem in that an appropriate filtration capacity cannot be exhibited.

  Thus, it cannot be said that the conventional air diffuser satisfies the two requirements of uniformly dispersing the air bubbles and preventing the air diffuser from being blocked at the same time, and can sufficiently prevent a decrease in the filtration capacity. It was not a thing.

  The present invention has been made to solve the problems of the prior art, and in the diffuser of the submerged membrane separator, the air bubbles are uniformly dispersed and the air diffuser is blocked by blocking. It is an object of the present invention to provide a method of using a submerged membrane separator and a submerged membrane separator that can prevent a reduction in processing capacity.

  The method of using the submerged membrane separation device according to the present invention includes a membrane module that filters sludge, an air diffuser that has an air diffuser that ejects bubbles from below the membrane module, and air that supplies air to the air diffuser. A method of using a submerged membrane separation apparatus comprising a supply device, wherein the air supply device repeats the supply and stop of air to the diffuser.

  According to the above method, in the submerged membrane separator, the supply and stop of air from the air supply device to the air diffuser are repeated (air is supplied intermittently). This is derived from the fact that the inventors of the present application have obtained the following knowledge after extensive research. That is, when air is continuously supplied, 1) a back flow phenomenon occurs simultaneously with the ejection of bubbles in the air diffuser, and the sludge enters the air diffuser. 2) The sludge that has entered the interior is dried by the supplied air. And solidify in the diffuser. On the other hand, with the sludge infiltrated into the diffuser (before the sludge solidifies in the diffuser), the processing liquid (sludge is intentionally added to the diffuser by stopping the air supply. ) By pulling in and suppressing drying of the sludge and then supplying air again, the liquid sludge can be discharged out of the air diffuser together with the treatment liquid.

  In this way, by intermittently supplying air, it is possible to effectively prevent the air diffuser from being blocked, so that it is not necessary to perform flushing with uneven bubble dispersion. Therefore, it is possible to prevent the air diffuser from being blocked while uniformly dispersing the bubbles, and it is possible to easily and effectively prevent a reduction in the filtration processing capacity.

  Therefore, preferably, the continuous supply time for continuously supplying the air is shorter than the time for the sludge that has entered the air diffuser to flow back from the air diffuser of the air diffuser into the air diffuser and solidifies in the air pipe. The supply stop time for stopping the supply is longer than the time during which the inside of the diffuser is substantially filled with the sludge that has entered the diffuser. Further preferably, the supply stop time with respect to the continuous supply time is 10 seconds or more with respect to 5 hours or less.

  Thereby, obstruction | occlusion of an aeration part can be prevented more efficiently and effectively.

  The submerged membrane separation device according to the present invention includes a membrane module that filters sludge, an air diffuser having an air diffuser that ejects bubbles from below the membrane module, and supplies air to the air diffuser. An air supply device and an air supply control device provided with a timer for performing control for intermittently supplying air from the air supply device to the diffuser.

  According to the apparatus of the said structure, air is supplied from an air supply apparatus to the diffuser which has a diffuser part, such as a diffuser hole and a notch, which distributes and supplies a bubble uniformly to the membrane module which filters sludge. This supply of air is controlled by an air supply control device. The air supply control device has a timer and intermittently controls the supply of air (the supply and stop of air are repeated).

  Therefore, by intermittently supplying air on the basis of the above knowledge, it is possible to effectively prevent the air diffuser from being blocked, so that it is not necessary to perform flushing with uneven bubble dispersion. Therefore, it is possible to prevent the air diffuser from being blocked while uniformly dispersing the bubbles, and it is possible to easily and effectively prevent a reduction in the filtration processing capacity.

  According to the method of using the submerged membrane separator and the submerged membrane separator according to the present invention, the air supply can be effectively prevented from being blocked by supplying air intermittently, so that There is no need to perform flushing with uneven dispersion. Therefore, it is possible to effectively prevent the air diffuser from being blocked while uniformly dispersing the bubbles, and to easily and effectively prevent a reduction in the filtration processing capacity. Thereby, filtration performance can be maintained over a long period of time.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of a submerged membrane separation apparatus according to a first embodiment of the present invention. FIG. 1A is a longitudinal sectional view, and FIG. 1B is a bottom view. Moreover, FIG. 2 is the fragmentary sectional view which looked at the place which has arrange | positioned the immersion type membrane separator of this embodiment in the septic tank from the side.

  As shown in FIG. 1, the submerged membrane separation apparatus 1 according to the present embodiment includes a multi-tubular membrane module 11 that filters sludge, an air diffuser 10 that ejects bubbles from below the membrane module 11, An air supply device 14 that supplies air to the air diffuser 10, and an air supply controller 15 that includes a timer 151 that performs control for intermittently supplying air from the air supply device 14 to the air diffuser 10. It comprises. The air supply device 14 is realized by an air pump, and the air supply control device 15 is realized by a control unit (such as a microcomputer) provided in the air pump or a computer such as a personal computer connected to the air pump. In the present embodiment, there is further provided a guide tube 12 that guides the bubbles ejected from the air diffuser 10 to the membrane module 11.

  First, the function of the submerged membrane separation apparatus 1 in the septic tank 31 will be described with reference to FIG. The septic tank 31 having the merge processing function is roughly composed of two to three tanks. For example, in the case of 3 tanks, it is comprised from a solid-liquid separation tank, a denitrification tank, and a nitrification tank, and in the case of 2 tanks, it is comprised from a solid-liquid separation tank and a nitrification tank. In the septic tank 31 of this embodiment, the tank 32 and the tank 33 are partitioned by a partition plate 34, the tank 32 corresponds to a solid-liquid separation tank or a denitrification tank, and the tank 33 corresponds to a nitrification tank. The invention is not limited to this. The submerged membrane separation apparatus 1 is installed in the nitrification tank 33 and is almost entirely immersed in an activated sludge liquid having an MLSS concentration of about 5000 to 18000 mg / L. And the domestic waste water (sewage) sent from the tank 32 of the front | former stage through the transfer pipe 35 is filtered using the activated sludge of the nitrification tank 33 (sewage containing activated sludge is called a to-be-processed liquid). It should be noted that an alarm (not shown) is activated when the transfer amount of domestic wastewater increases abruptly or when the filtration performance deteriorates and the water level in the nitrification tank 33 exceeds the upper limit HWL.

  In the submerged membrane separation apparatus 1, an air diffuser 10 is installed below the membrane module 11, and bubbles are sent substantially uniformly throughout the membrane module 11. Bubbles sent from below into the membrane module 11 rise in the membrane module 11 with the liquid to be treated containing activated sludge, and are discharged from the upper end thereof. Thus, during aeration, the liquid to be treated circulates inside and outside the membrane module 11 in the nitrification tank 33, and during this time, filtration treatment is performed in the membrane module 11.

  The filtrate after the filtration process is performed in the membrane module 11 is discharged through the discharge pipe 36 connected to the filtrate discharge port. The filtered filtrate is pumped up by a pump 37 through a discharge pipe 36 and sent to a disinfection tank 38. The filtrate sent to the sterilization tank 38 is sterilized and discharged from the discharge port 39.

  The perforated pipe-type air diffuser 10 provided in the submerged membrane separation apparatus 1 of the present embodiment includes a skewered pipe 103 for dispersing air, and air from the air supply device 14 in the air diffuser 10. The air inlet 102 to be introduced into the pipe 103, the air diffuser 101 provided as the air diffuser for ejecting the introduced air and the sludge backflow and discharge are efficiently prevented so that the sludge does not accumulate on the pipe 103. An open end 104 is provided for efficient operation. The open end 104 of the skewer-shaped pipe 103 is bent downward so that the dead end of the backflowed sludge is generated and does not accumulate in the pipe 103, and is opened at a position lower than the diffuser hole 101 opened downward.

  Air is sent from the air supply device 14 connected to the air introduction port 102 (the piping from the air supply device 14 to the air introduction port 102 is not shown). The air introduced into the pipe 103 is ejected from the air diffuser holes 101 (13 air diffuser holes 101 are drawn in FIG. 1B) provided in the skewer-like pipe 103 substantially isotropically. The air bubbles are dispersed in the guide tube 12.

  The membrane module 11 reinforces the adhesive force of a large number of tubular membranes 110 that perform filtration processing, a cylindrical container 111 for fixing the tubular membrane 110, and the focusing and fixing of the tubular membrane 110 and the cylindrical container 111, and filtration after the filtration processing. A wedge-shaped ring 113 and a filtrate discharge port 112 that form a passage for discharging the liquid to the outside are provided.

  The both ends of the tubular membrane 110 are focused and fixed to the cylindrical container 111 by a thermosetting resin (the broken line portion in the figure). Bubbles ejected from the air diffuser 10 rise in the cylindrical container 111 and are distributed to the tubular membrane 110 substantially evenly. The bubble rises in the tubular membrane 110 with the sludge and gives a cross flow to the sludge. During this time, sludge is filtered by gravity difference or suction pressure, and the filtrate is formed by a wedge-shaped ring 113 after passing through the gap between the tubular membranes 110 and is formed between the tubular membrane 110 and the cylindrical container 111. And is discharged to the outside from the filtrate outlet 112 (the piping from the filtrate outlet 112 to the outside is not shown). The guide tube 12 has a net 13 between the air diffuser 10 and the tubular membrane 110 for separating massive sludge and the like that may block the tubular membrane 110 and removing large contaminants. Installed.

  Here, the backflow phenomenon of sludge will be described. The air supplied from the air inlet 102 to the air diffuser 10 has a water depth shallower than that of the open end 104 (that is, the water pressure is low), and is thus ejected from the air diffuser hole 101 into the sludge. At this time, sludge flows backward instantaneously even during the air supply due to the water pressure fluctuation in the vicinity of the air diffuser 101 which is considered to be due to the vertical fluctuation of the liquid level. When the air supply is continued, such sludge is gradually dried by exposure to air, and is accumulated as a solidified / dried material around the air diffuser 101 every time the backflow is repeated. It will be blocked. For example, if the diameter of the air diffuser 101 is 6 mm and the MLSS concentration of sludge exceeds several thousand when the air flow rate per air diffuser 101 is about 10 L / min, it is partially blocked in one day. However, most of the inside of the pipe 103 except for the vicinity of the air inlet 102 may be clogged with solidified sludge in a few days, and most of the air diffusion holes 101 may be completely blocked. In addition, if the diameter of the air diffuser 101 is made small (for example, in the case of 2 mm or less), it has been found that the sludge does not easily flow backward. However, when the air supply is stopped due to a power failure or the like, the sludge flows backward. Since the air diffuser 101 may be immediately blocked by sludge, it is not realistic.

  When the supply of air is stopped, the inside of the pipe 103 is almost filled with the sludge flowing in from the diffuser holes 101 and the open end 104. At this time, if the sludge that has flowed back into the pipe remains in a liquid state, when air is supplied again, it is pushed out from the air diffuser 101 and the open end 104 together with the sludge that flows in. Therefore, the blockage preventing method for the air diffuser 10 according to the present invention is to coagulate by repeating the supply stop and restart if the continuous supply time of the air is shorter than the coagulation time of the sludge flowing back into the air diffuser 10. This is based on the knowledge that can be prevented in advance. Further, since the effect of washing out increases as the amount of sludge in the air diffuser 10 increases, the supply stop time is preferably longer than the time during which the air diffuser 10 is substantially filled with sludge. The relationship between the supply stop time and the continuous supply time varies depending on the structure of the air diffuser 10 and the air flow rate. However, when the continuous air supply time exceeds 5 hours, depending on the nature of the sludge, Therefore, it is preferably 10 seconds or more for 5 hours or less, more preferably 30 seconds or more for 2 hours or less, and continuous supply time for 1 hour or more in terms of operating efficiency. The supply stop time is preferably 1 minute or less.

  Therefore, according to the device of the present embodiment based on the above knowledge, air is supplied from the air supply device 14 to the air diffuser 10 that uniformly distributes and supplies bubbles to the membrane module 11 that filters sludge. The air supply is controlled by the air supply control device 15. The air supply control device 15 has a timer 151 and intermittently controls the supply of air.

  That is, the air supply control device 15 instructs the air supply device 14 to supply air and starts a timer. When a predetermined timer time (continuous supply time: 2 hours, for example) has passed, An instruction to stop the supply is sent to the air supply device 14. Further, the air supply device 14 instructs to stop the air supply and starts the timer, and when the predetermined timer time (supply stop time: for example, 30 seconds) has passed, the air supply device 14 instructs to start the air supply again. Send to. Hereinafter, the air supply is intermittently controlled by controlling this repeatedly.

  By such control, in a state where the sludge has entered the diffuser 10 (before the sludge solidifies in the diffuser 10), the supply of air is stopped to intentionally enter the diffuser 10. By drawing the treatment liquid (sludge) and suppressing the drying of the sludge and then supplying air again, the liquid sludge with the treatment liquid can be discharged out of the air diffuser 10.

  In this way, by intermittently supplying air, it is possible to effectively prevent the air diffusion holes 101 from being blocked, so that it is not necessary to perform flushing with uneven bubble dispersion. Accordingly, it is possible to prevent the air diffuser 101 serving as the air diffuser from being blocked while uniformly dispersing the bubbles, and it is possible to easily and effectively prevent the reduction of the filtration processing capability.

  Subsequently, a second embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram of a submerged membrane separation apparatus according to the second embodiment of the present invention. FIG. 3A is a longitudinal sectional view, and FIG. 3B is a bottom view. In the submerged membrane separation apparatus 1 ′ of this embodiment, a trough-type air diffuser 100 is used instead of the perforated pipe-type air diffuser 10 in the first embodiment. Since other configurations are the same as those of the first embodiment, description thereof will be omitted.

  The air diffuser 100 according to this embodiment includes a doughnut-shaped trough 1003 and is fixed to the guide cylinder 12 by four fixing plates 1004. On the wall surface of the trough 1003, notches 1001 are provided as diffusers reaching the bottom (in the example shown, 12 are provided on the outside of the trough 1003 and 4 are provided on the inside). The air supplied from the air introduction port 1002 spreads to the ceiling portion of the trough 1003 and blows into the liquid from the bottom of the notch 1001 as bubbles.

  In the trough-type air diffuser 100, the water pressure fluctuation accompanying the vertical fluctuation of the liquid level is instantaneously transmitted to the entire air layer. Therefore, the fluctuation of the liquid level in the trough 1003 is of the perforated pipe type in the first embodiment. Smaller than the air diffuser 10. However, sludge is attached in the vicinity of the notch 1001 from which air is ejected, and wetting and drying are repeated. By continuing the supply of air, solidified / dried sludge grows and the passage (inside the trough 1003) narrows unevenly. In the trough-type air diffuser 100 originally provided with a notch, the amount of air blown out varies greatly depending on a slight difference in water depth and dimensions. It tends to decrease significantly. As a result, air bubbles are not uniformly distributed to the membrane module 11 and the filtration performance is deteriorated even if the blockage does not occur.

  On the other hand, it is conceivable to provide a hole in the wall surface of the trough 1003 instead of the notch 1001. Thereby, the influence of the water depth difference is equivalent to that of the perforated pipe type diffuser 10, but is more likely to be blocked than when the notch 1001 is provided.

  From the above, the method for preventing the obstruction of the air diffuser according to the present invention is also effective for the trough type air diffuser 100. Therefore, by intermittently supplying the air, it is possible to effectively prevent the notch 1001 that is the air diffuser from being blocked, and it is possible to easily and effectively prevent a reduction in the filtration capacity.

  Subsequently, a third embodiment of the present invention will be described. FIG. 4 is a schematic configuration diagram of a submerged membrane separation apparatus according to the third embodiment of the present invention. 4A is a longitudinal sectional view, and FIG. 4B is a bottom view. In the submerged membrane separation apparatus 2 of the present embodiment, a plate-type membrane module 21 equipped with a plurality of membrane plates 210 is used instead of the multi-tubular membrane module 11 in the first embodiment. Further, the air diffuser 20 of this embodiment includes a straight pipe 203 for dispersing air, an air inlet 202 for introducing air from the air supply device 14 into the pipe 203 in the air diffuser 20, and a pipe 203. Provided with an open end 204 provided for efficient backflow and discharge of sludge so that the sludge does not accumulate on the pipe 203 and a diffuser hole 201 as a diffuser for ejecting the introduced air. is doing. That is, it is a holed pipe type that is functionally similar to the air diffuser 10 of the first embodiment except that the straight pipe 203 is used so as to be suitably used for the plate type membrane module 21.

  Also in the present embodiment, the air supplied from the air supply device 14 is introduced from the air introduction port 202, and the diffuser holes 201 (five diffuser holes in FIG. 4B) are provided in the pipe 203 at substantially equal intervals. 201 is drawn). The bubbles ejected from the air diffuser 201 are dispersed in the guide tube 22 and distributed substantially evenly between the gaps 213 between the membrane plates 210 (or the membrane plate 210 and the frame 211).

  A membrane is adhered to the membrane plate 210 at both sides of the plate on which the filtrate passage is formed. Since the air bubbles rise in the gap 213 while accompanying the sludge, the crossflow is given to the sludge. During this time, the sludge is filtered by the gravity difference and suction pressure, and the filtrate is pulled up from the membrane plate 210 for each membrane plate 210 and joined to the outside by the water collecting pipe 212 (the piping extending from the water collecting pipe to the outside is omitted). ing). In the case of the plate-type membrane module 21, the sludge passage is often wide, so it is not necessary to install the net 13 as in the first embodiment in the guide tube 22 (of course, the net is not installed). Does not prevent installation).

  Also in the present embodiment, by intermittently supplying air, it is possible to effectively prevent the air diffusion holes 201 from being blocked, so that it is not necessary to perform flushing with uneven bubble dispersion. Therefore, it is possible to effectively prevent the air holes 201 as the air diffuser from being blocked while uniformly dispersing the air bubbles, and it is possible to easily and effectively prevent the reduction of the filtration capacity.

  Furthermore, a fourth embodiment of the present invention will be described. FIG. 5 is a schematic configuration diagram of a submerged membrane separation apparatus according to the fourth embodiment of the present invention. FIG. 5A is a longitudinal sectional view, and FIG. 5B is a bottom view. In this embodiment, a trough-type air diffuser 200 is used instead of the perforated pipe-type air diffuser 20 in the third embodiment. Since other configurations are the same as those of the third embodiment, description thereof will be omitted.

  The air diffuser 200 according to the present embodiment includes a linear trough 2003 corresponding to the plate-type membrane module 21 and is fixed to the guide tube 22 by four fixing plates 2004. The wall surface of the trough 2003 is provided with notches 2001 as diffusers reaching the bottom (in the example shown, six are provided). The air supplied from the air inlet 2002 spreads to the ceiling portion of the trough 2003, and becomes air bubbles from the portion below the upper end of the notch 2001 and is ejected into the liquid.

  Also in the present embodiment, as in the second embodiment, the method for preventing obstruction of the air diffuser according to the present invention is effective. Therefore, by intermittently supplying the air, it is possible to prevent the notch 2001 that is the air diffuser from being blocked, and it is possible to effectively prevent a reduction in the filtration processing capacity.

<Example>
Here, examples of the present invention will be described. The case where intermittent air supply was performed using the submerged membrane separation apparatus 1 shown in FIGS. 1 and 2 was compared with the case where it was not performed.

The multi-tubular membrane module 11 of the present embodiment is equipped with 625 tubular membranes 110 having a hole diameter of about 0.4 μm, an inner diameter of 11 mm, and a thickness of 0.2 mm to form a membrane module having a diameter of about 30 cm and a length of about 56 cm. The effective membrane area is 10.9 m ² . The length of the guide tube 12 installed at the lower part of the membrane module 11 is about 30 cm. In the air diffuser 10, thirteen air diffused holes 101 are provided at intervals of about 7 cm in a skewer-like transparent pipe 103 having an inner diameter of 20 mm. FIG. 6 is an image of an unused air diffuser taken from the air diffuser side. The distance from the floor surface of the nitrification tank 33 to the air diffusion holes 101 is about 12 cm, and the air flow rate is about 10 L / min per one air diffusion hole 101.

  The operation of stopping the supply of air once every hour for 1 minute was repeated for 3 months, and then the immersion membrane separator 1 was pulled up and the state of the air diffuser 10 was observed. FIG. 7 is an image of the air diffuser after three months in Example 1 taken from the air diffuser side.

  As a result, as shown in FIG. 7, the entire inner surface of the pipe 103 was wet with liquid sludge, but solidified sludge was not observed, and solidified sludge was also present in all the air diffusion holes 101 and the open ends 104. It was not attached. In addition, the sludge liquid surface above the membrane module 11 before being pulled up was almost uniformly raised, and there was almost no decrease in the filtration flow rate.

  Further, the immersion membrane separation apparatus 1 was returned to the nitrification tank 33 again, and the state of the air diffuser 10 was observed after operating for 5 days with a supply stop time of 30 seconds.

  The state of the air diffuser 10 was observed in the same manner as in Example 1 except that the air supply was stopped once every 5 hours for 1 minute.

  As a result, gel-like sludge adhered to the inner surface of the pipe 103 in some places, but there were no air diffused holes 101 and open ends 104 in a completely closed state, and the rising state of the sludge liquid surface was substantially uniform. . Moreover, the fall of the filtration flow rate was also slight.

<Comparative example>
After supplying air continuously for 5 days, the submerged membrane separator 1 (however, the net 13 is not attached) was pulled up, and the state of the air diffuser 10 was observed. FIG. 8 is an image of the air diffuser after 5 days in the comparative example taken from the air diffuser side.

  As a result, as shown in FIG. 8, the solidified sludge adhering to the pipe 103 around the air diffuser 101 was adhered, and the seven open ends 104 were also semi-closed (arrows in the figure). (See the section indicated by). The adhering sludge could not be removed simply by running water. Further, the sludge liquid surface above the membrane module 11 before being pulled up corresponds to one place of the air diffuser 101 near the air inlet 102 and seven open ends 104 corresponding to the closed state of the air diffuser 10. Only the area was raised. Also, the filtration flow rate was reduced to about 2/3 compared to the time when the test was started.

  As described above, it has been shown that the air supply hole 101 can be effectively blocked by intermittently controlling the air supply. Furthermore, it was shown that the deterioration of the filtration performance can be prevented while the bubbles are uniformly dispersed.

1 is a schematic configuration diagram of a submerged membrane separation apparatus according to a first embodiment of the present invention. It is the fragmentary sectional view which looked at the place which has arrange | positioned the immersion type membrane separator of 1st Embodiment in the septic tank from the side. It is a schematic block diagram of the immersion type membrane separator which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the immersion type membrane separator which concerns on 3rd Embodiment of this invention. It is a schematic block diagram of the immersion type membrane separator which concerns on 4th Embodiment of this invention. An unused air diffuser is taken from the air diffuser side. The air diffuser after 3 months in Example 1 is taken from the air diffuser side. The air diffuser after 5 days in the comparative example is taken from the air diffuser side.

Explanation of symbols

1, 1 ', 2, 2' Submerged membrane separator 11, 21 Membrane module 10, 100, 20, 200 Air diffuser 101, 201 Air diffuser (air diffuser)
1001, 2001 Notch (air diffuser)
14 Air supply device 15 Air supply control device 151 Timer

Claims (4)

Method of using a submerged membrane separation apparatus comprising a membrane module for filtering sludge, an air diffuser having an air diffuser for ejecting bubbles from below the membrane module, and an air supply device for supplying air to the air diffuser Because
A method of using a submerged membrane separation device, wherein the air supply device repeats the supply and stop of air to the diffuser. The continuous supply time for continuously supplying the air is shorter than the time for the sludge that has entered the air diffuser to flow back from the air diffuser of the air diffuser to solidify in the vent pipe,
2. The method of using a submerged membrane separation apparatus according to claim 1, wherein the supply stop time for stopping the supply of air is longer than the time during which the inside of the diffuser is substantially filled with sludge that has entered the diffuser. .   The method of using the submerged membrane separation apparatus according to claim 2, wherein the supply stop time with respect to the continuous supply time is 10 seconds or more with respect to 5 hours or less. A membrane module for filtering sludge;
An air diffuser having an air diffuser for ejecting bubbles from below the membrane module;
An air supply device for supplying air to the air diffuser;
An immersion type membrane separation apparatus comprising: an air supply control device including a timer that performs control for intermittently supplying air from the air supply device to the air diffuser.

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