JP2021112743A - Membrane separation active sludge treatment device, and membrane separation active sludge treatment method - Google Patents

Abstract

To provide a partition plate insertion type membrane separation active sludge treatment device and method, enhancing nitrogen removal efficiency further, capable of changing a nitrification promotion operation time zone and denitrification promotion operation time zone easily in short time, further applicable in variation of inflow sewage amount during day.SOLUTION: There are provided a partition plate insertion type membrane separation active sludge treatment device having a single reaction tank for conducting an aerobic treatment and a non-oxygen treatment, an impregnation membrane separation unit arranged inside of the reaction tank, and aeration means, in which the reaction tank is divided into a plurality of sections by a partition plate, at least one section of the plurality of sections is set as an aerobic section in which the impregnation membrane separation unit and the aeration means, and other sections are set as sections for changing an aerobic condition and an oxygen-free condition, in which circulation water amount adjusting means is arranged, and a membrane separation active sludge treatment method using the circulation water amount adjusting means.SELECTED DRAWING: Figure 4

Description

The present invention relates to a membrane separation activated sludge treatment apparatus and method capable of efficiently removing nitrogen together with membrane separation.

Conventionally, in treating sewage containing nutrients such as nitrogen and phosphorus, an activated sludge method has been used in which sewage is introduced into a reaction tank and aerated and agitated together with activated sludge for biological treatment. Particularly in recent years, in order to obtain clear treated water containing no solid matter from the treated water treated by this active sludge method, a membrane separation device is immersed in a reaction vessel, and the treated water is separated and discharged. The active sludge method (Membrane Bioreactor (MBR) method) is often used.

In such an immersion type membrane separation device, it is necessary to blow air from the lower air diffuser pipe in order to prevent sludge from adhering to the membrane surface and causing fouling (clogging of the membrane), which is usually the case. Is diverging almost continuously. In the activated sludge method, nitrification proceeds by the action of nitrifying bacteria under such an aerobic state, but on the other hand, in order to perform denitrification treatment by denitrifying bacteria, it is necessary to make the inside of the tank anoxic. .. Therefore, in the membrane separation activated sludge method, it is necessary to secure both the air diffuser for the membrane surface cleaning and nitrification treatment at the time of membrane filtration and the anoxic state for the denitrification treatment. As a technique to be realized, a membrane separation activated sludge device and a method for advancing aerobic treatment (nitrification treatment) and anoxic treatment (denitrification treatment) in a single reaction vessel have been proposed (Patent Document 1).

As shown in FIG. 1 of the present application, the apparatus proposed in Patent Document 1 includes a single reaction tank 1 that performs aerobic treatment and anoxic treatment, and an immersion membrane separation unit arranged inside the reaction tank. A device having 2 and an aeration means 4, the reaction tank 1 is divided into a plurality of compartments by a partition plate 7 whose bottom is provided so as to be separated from the bottom surface of the reaction tank, and the plurality of compartments are divided into a plurality of compartments. At least one of these compartments is an aerobic compartment in which the immersion membrane separation unit 2 and the aeration means 4 are arranged, and the remaining compartments are changed from an aerobic state to an anoxic state and from an anoxic state to an aerobic state. Partition plate insertion, which is a partition for switching and is provided with a liquid level control means or a partition plate height control means for switching between a state in which the liquid level in the reaction tank is higher than the upper end of the partition plate and a state in which the liquid level is lower than the upper end of the partition plate. This is a type of membrane separation active sludge treatment device (Baffled Membrane Bioreactor (B-MBR method)).

In the method of Patent Document 1, the raw water pump 8 is turned on when the liquid level in the reaction tank 1 becomes a low water level (LWL: Low Water Level), and the raw water pump 8 turns on when the liquid level becomes a high water level (HWL: High Water Level). By changing the liquid level by setting to OFF, a state in which the liquid level is higher than the partition plate and a state in which the liquid level is lower than the partition plate are alternately created (FIG. 1). Here, when the liquid level is higher than the partition plate, the circulating flow (from the membrane unit accommodating compartment, over the partition plate 7 to enter another compartment, and the other compartments are entered by the air from the air diffuser pipe 4 over the entire tank. A circulating flow that descends within the compartment and returns to the membrane unit containment compartment via the region below the partition plate 7) is formed (FIG. 2). Due to the formation of such a circulating flow, sludge containing a large amount of nitrate nitrogen obtained by the nitrification treatment in the membrane separation unit accommodating compartment is transferred to other compartments, and aerobic treatment (nitrification treatment) is performed inside and outside the partition plate 7. Progress (this time zone is called "nitrification promotion operation time zone"). On the other hand, when the liquid level is lower than the partition plate, the flow of the liquid is divided between the membrane separation unit accommodating compartment and the other compartments, and as a result, the other compartments become anoxic and anoxic treatment (denitrification). Processing) progresses (this time zone is called "denitrification promotion operation time zone"). As described above, the method of Patent Document 1 is a method in which the nitrification promotion operation time zone and the denitrification promotion operation time zone are alternately repeated by alternately creating a state in which the liquid level is higher and a state in which the liquid level is lower than that of the partition plate. be.

Japanese Unexamined Patent Publication No. 2004-261711

However, in the method described in Patent Document 1, it has been desired to further improve the nitrogen removal efficiency. Further, in the method of Patent Document 1, the nitrification promotion operation time zone and the denitrification promotion operation time zone are switched by alternately creating a state in which the liquid level is higher and a state in which the liquid level is lower than that of the partition plate. It took a long time to switch.

Furthermore, in sewage treatment, the daily fluctuation of the inflow sewage amount (the inflow drainage amount and the concentration fluctuation of pollutants) is large, and in general, in a large-scale treatment device, there is a fluctuation of about 0.5 to 1.5 times the daily average value. In small-scale processing equipment, there is a fluctuation of about 0.2 to 3 times. With respect to such daily load fluctuations, it has been difficult to carry out an efficient nitrification and denitrification reaction by the method of Patent Document 1. Further, in order to reduce the daily fluctuation of the inflow sewage amount, it was necessary to provide a large-capacity flow rate adjusting tank.
Under such circumstances, Patent Document 1 does not pay any attention to accurately adjusting the flow rate of the circulating flow in the reaction vessel, and also describes the shape of the upper end of the partition plate installed in the reaction vessel. Was not mentioned at all.

In view of the above-mentioned conventional problems, the present invention can further improve the nitrogen removal efficiency, easily switch between the nitrification promotion operation time zone and the denitrification promotion operation time zone in a short time, and further, the amount of inflow sewage. It is an object of the present invention to provide a partition plate insertion type membrane separation active sludge device and method showing high applicability to daily load fluctuations.

The inventors of the present application have diligently studied the cause of insufficient nitrogen removal efficiency in the conventional membrane separation activated sludge treatment method of the partition plate insertion type. As a result, when the liquid level is lower than that of the partition plate (denitrification promotion operation time zone), the flow of the liquid is divided inside and outside the partition plate, and no circulating flow is generated in the section where the membrane separation unit is not arranged. Raw water, nitrifying solution (liquid containing nitrifying nitrogen after nitrification treatment) and denitrifying bacteria involved in the denitrification reaction are not sufficiently mixed, and as a result, efficient denitrification reaction is difficult to proceed. I found.

Then, by using a membrane separation activated sludge treatment device provided with a circulating water amount adjusting means in the reaction vessel, a small amount of circulating flow rate for achieving the above-mentioned sufficient mixing can be secured during the denitrification promotion operation time zone. At the same time, it has been conceived that dissolved oxygen (DO), which is an obstacle to denitrification, can be maintained at a low level, and as a result, the nitrogen removal efficiency is improved. Further, by using such a membrane separation activated sludge treatment device, it is possible to easily switch between the nitrification promotion operation time zone and the denitrification promotion operation time zone in a short time, and further, the inflow sewage amount can be changed daily. The present invention has been completed with the idea that efficient progress of the denitrification reaction can be achieved.

That is, the present invention relates to the following (1) to (8).
(1) A membrane separation active sludge treatment apparatus having a single reaction tank for aerobic treatment and anoxic treatment, an immersion membrane separation unit arranged inside the reaction tank, and an aeration means for reaction. The tank is divided into a plurality of compartments by a partition plate whose bottom is provided so as to be separated from the bottom surface of the reaction tank, and at least one of the plurality of compartments is provided with an immersion membrane separation unit and an aeration means. Membrane separation active sludge treatment apparatus in which the aerobic compartment is used as a compartment and the other compartment is used as a compartment for switching from an aerobic state to an anoxic state and from an anoxic state to an aerobic state. Membrane separation active sludge treatment device characterized by being provided with.

(2) The membrane separation according to (1), wherein the circulating water amount adjusting means is a swing type circulating water amount adjusting device including a circulating water amount adjusting plate and an adjusting plate moving means for swinging the circulating water amount adjusting plate. Activated sludge treatment equipment.
(3) The membrane separation activated sludge treatment apparatus according to (2), wherein the circulating water amount adjusting plate is a rectangular adjusting plate that is curved or bent in the lateral direction.
(4) The circulating water amount adjusting means is a slide plate having an opening, and is a circulating water amount adjusting device provided with a slide plate capable of adjusting the opening ratio of the opening provided in the partition plate. The membrane separation activated sludge treatment apparatus according to the above.

(5) The membrane separation activated sludge treatment apparatus according to (1), wherein the circulating water amount adjusting means is a partition plate having a notch at the upper end.
(6) The membrane separation activated sludge treatment apparatus according to (5), wherein the notch provided at the upper end of the partition plate is a combination of notches having different depths.
(7) The circulating water amount adjusting means includes a circulating water amount adjusting plate, a swing type circulating water amount adjusting device provided with an adjusting plate moving means for swinging the circulating water amount adjusting plate, and a partition plate having a notch at the upper end. The membrane separation activated sludge treatment apparatus according to (1), which is a means combining the above.

(8) This is a membrane separation active sludge treatment method in which aerobic treatment and anoxic treatment are performed in a single reaction vessel in which the immersion membrane separation unit is arranged, and the bottom is from the bottom surface of the reaction vessel around the immersion membrane separation unit. By partitioning with partition plates provided apart from each other and aerating from below the immersion membrane separation unit, the inside of the compartment in which the immersion membrane separation unit is arranged is maintained in an aerobic state, and the other compartments are separated. A membrane separation active sludge treatment method for switching from an aerobic state to an anoxic state and from an anoxic state to an aerobic state, wherein the amount of circulating water is adjusted by a means for adjusting the amount of circulating water.

In the present specification, the "anoxic state" does not mean only a completely anoxic state, but also a state in which the oxygen concentration is low enough to reduce nitrate nitrogen to nitrogen molecules by the action of denitrifying bacteria. Used in the sense of inclusion.

According to the present invention, in a compartment other than the membrane separation unit accommodating compartment, a small amount of circulating flow rate that provides a sufficient mixture of raw water, nitrification liquid and denitrifying bacteria required for the denitrification reaction can be accurately obtained even during the denitrification promotion operation time. Since it can be well controlled and secured, the efficiency of removing nitrogen from organic sewage can be improved. In addition, the nitrification promotion operation time zone and the denitrification promotion operation time zone can be easily switched in a short time, and further, it can be applied to the daily fluctuation of the inflow sewage amount, so that the membrane separation activated sludge treatment is efficient. Is possible.

It is a figure which shows typically the membrane separation activated sludge treatment apparatus of the conventional method (Patent Document 1). It is a figure which shows typically the flow of the circulating water in the membrane separation activated sludge treatment apparatus of a partition plate insertion type. It is a side view and the top view schematically showing the membrane separation activated sludge treatment apparatus of the conventional method (Patent Document 1). It is a side view and the top view schematically showing the membrane separation activated sludge treatment apparatus of this invention. It is a figure which shows typically another embodiment of the circulating water amount adjusting means of this invention. It is a figure which shows still another embodiment of the circulating water amount adjusting means of this invention schematically. It is a figure which shows still another embodiment of the circulating water amount adjusting means of this invention schematically. It is a figure which shows still another embodiment of the circulating water amount adjusting means of this invention schematically.

Hereinafter, embodiments of the membrane separation activated sludge treatment apparatus and method according to the present invention will be described with reference to the drawings. In FIGS. 1 to 8, members having the same function are designated by the same reference numerals.
As will be described later, the feature of the present invention is that the membrane separation activated sludge treatment apparatus of the partition plate insertion type is provided with the circulating water amount adjusting means. First, one implementation of the membrane separation activated sludge treatment apparatus and method according to the present invention. The overall configuration of the embodiment will be described with reference to FIG.

In the membrane separation activated sludge apparatus of FIG. 4, the immersion type membrane separation unit 2 is provided in the single tank type reaction tank 1. A suction pump 3 is connected to the membrane separation unit 2 outside the reaction tank 1, and an aeration means 4 (aeration device) for washing the membrane and treating aerobic organisms is provided below the membrane separation unit 2. ing. The aeration means 4 is connected to the blower 5, and air is supplied from the blower 5.

As the membrane separation unit 2, it is preferable to use a material that is hard to get dirty as the membrane itself, or a membrane that has an appropriate gap between the membranes so that the surface of the membrane is hard to get dirty. As the membrane separation unit 2, a module formed by using a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, or the like can be used. From the viewpoint of economy, a module using a microfiltration membrane or an ultrafiltration membrane, which has a high filtration rate, can be made compact, and is easy to maintain, is preferable. As the shape of the membrane, a flat membrane, a hollow fiber membrane, or the like is used. The immersion type membrane separation unit itself used here is widely used in this field and is also commercially available.

Sludge containing microorganisms is contained in the reaction tank 1, and these microorganisms act as decomposing bacteria of organic substances and further, decomposing bacteria of these microorganisms to carry out biological treatment. Therefore, it is preferable that the reaction tank 1 has no corners or irregularities on the inner surface so that the sludge is not partially unevenly distributed and oxygen is uniformly supplied. As a result, the temperature and pH of the treatment liquid become uniform in the reaction vessel 1, and the decomposition treatment can proceed stably. In addition, the microorganisms contained in sludge contribute to the decomposition of soluble organic substances such as bacteria, yeast and fungi including mold, and are acquired from the natural world such as soil, compost, and sludge by enrichment culture and acclimatization. NS. It is also possible to isolate and use a major group of microorganisms involved in decomposition from this acclimatization solution. The sludge itself containing these microorganisms is well known in this field.

The activated sludge treatment conditions in the reaction vessel 1 may be any well-known conditions usually used in the membrane separation activated sludge method, but the MLSS (Mixed Liquor Suspended Solid) concentration is usually 3000 to 20000 mg / L, preferably 5000 to 5000. It is 15000 mg / L and the HRT (hydraulic residence time) is usually 2 to 24 hours, preferably 4 to 8 hours.

The reaction tank 1 of FIG. 4 is further provided with a partition plate 7. The bottom of the partition plate 7 is provided so as to be separated from the bottom surface of the reaction tank, and surrounds the membrane separation unit 2 in the lateral direction (upper and lower sides are open). Anything that surrounds the target is sufficient. The partition plate 7 may be combined with the tank wall to surround the membrane separation unit 2, and is preferably two flat plates that cooperate with the tank wall of the reaction tank 1 to define a rectangular region. Alternatively, of the four peripheral surfaces of the membrane separation unit 2, one surface is surrounded by the partition plate 7 and the other three surfaces are surrounded by the tank wall, or the partition plate 7 surrounds the entire circumference of the membrane separation unit 2. It may be. The volume ratio of the accommodation compartment to the other compartment of the membrane separation unit 2 is usually set to be 1: 0.5 to 5, preferably in the range of 1: 1 to 3.

In the specific example of FIG. 4, there is only one storage compartment for the immersion membrane separation unit (hereinafter, also referred to as “membrane separation unit storage compartment”), but in the case of large-scale sewage treatment or the like, per unit time. If desired, a plurality of membrane separation unit accommodating compartments (aerobic compartments) may be provided, and the membrane separation unit may be immersed in each of these compartments in order to increase the processing amount. In this case, it is possible to provide a plurality of compartments other than the membrane separation unit accommodating compartment (hereinafter, also referred to as “other compartments”), but one of them has a simpler structure and makes it easier to ensure the uniformity of the reaction solution. preferable.

The sewage that has flowed into a sewage treatment facility such as a sewage treatment plant is separated and removed from sand and dust in the pretreatment facility, and then introduced as raw water from the raw water tank into the reaction tank 1 by a raw water pump. In the present invention, the raw water is preferably supplied to a compartment other than the membrane separation unit accommodating compartment. As a result, the hydrogen donor required for the denitrification reaction is supplied, and the denitrification reaction proceeds efficiently during the denitrification promotion time zone.

The membrane separation activated sludge treatment apparatus of the present invention may have a liquid level control means for adjusting the liquid level in the reaction vessel 1. As the liquid level control means, for example, a level sensor for checking the liquid level in the reaction vessel, that is, the position of the liquid surface is provided, and the raw water supplied to the reaction tank by the raw water pump according to the liquid level detected by the level sensor. Means for controlling the flow rate of the

With such a configuration shown in FIG. 4, sewage is biologically treated in the reaction tank 1, and sludge substances and the like are prevented from adhering to the membrane surface of the membrane separation unit 2 due to the air from the air diffuser pipe 4. However, the treatment liquid in the reaction tank 1 can be filtered by the membrane separation unit 2, and the filtered water can be sucked by the suction pump 3 and taken out of the tank. In the specific example of FIG. 4, the filtration pressure is obtained by the suction pump 3, but the filtration pressure may be obtained only by the difference between the water level in the reaction tank and the water level of the filtered water outlet, that is, the natural head. Further, the filtration pressure may be obtained by pressurizing from the stock solution side.

A feature of the present invention is that such a membrane separation activated sludge treatment apparatus is provided with a circulating water amount adjusting means. By this circulating water amount adjusting means, the amount of water of the circulating flow formed in the tank by the air from the air diffuser pipe 4 is adjusted. Here, the term "circulating flow" means, as shown in FIG. 2, when the inside and outside of the partition plate are in an overflow state, the membrane separation unit accommodating compartment passes over the partition plate 7 and enters another compartment. It is a flow of liquid that descends in the compartment and returns to the membrane unit accommodating compartment through the region below the partition plate 7. The circulating water amount adjusting means is preferably provided at the upper part or the upper end of the partition plate, and is preferably a means for adjusting the amount of water in the circulating flow moving from the membrane separation unit accommodating section to another section.

Hereinafter, the circulating water amount adjusting means in the present invention will be described with reference to FIGS. 4 to 8, but in order to understand the circulating water amount adjusting means of the present invention, the membrane separation activated sludge of the conventional method (the method of Patent Document 1) is described. The processing apparatus is shown in comparison with FIG.
The first embodiment of the circulating water amount adjusting means in the present invention is a swing type circulating water amount adjusting device including a circulating water amount adjusting plate and an adjusting plate moving means for swinging (swinging) the circulating water amount adjusting plate. .. Specifically, as shown in FIG. 4, a circulating water amount adjusting plate (hereinafter, also referred to as “swing plate”) 20a, a fixing member 21 for fixing one side of the swing plate in the longitudinal direction, and the swing plate 20a are provided. It is a swing type circulating water amount adjusting device provided with the adjusting plate moving means 22 for swinging. Further, the upper view of FIG. 4 is a top view of the membrane separation activated sludge treatment apparatus of the present invention when the swing plates 20a and 20b completely cover the upper part of the partition plate and block the circulating flow (side surface of FIG. 4). In the figure, the circulating water amount adjusting means on the right side is omitted, and in the top view, the adjusting plate moving means 22 is omitted).

One of the two sides of the swing plate 20a shown in FIG. 4 in the longitudinal direction is fixed to the rod-shaped fixing member 21. Further, the swing plate 20a is detachably connected to the adjusting plate moving means 22, and the swing plate 20a is moved up and down by the adjusting plate moving means 22 to swing, thereby increasing the opening degree at the upper part of the partition plate. Can be adjusted.

Here, the opening degree of the swing plate is set to 0% when the swing plate completely covers the upper part of the partition plate and the circulating flow is almost completely blocked in the side view of FIG. 4, and the opening degree is set to 0% by the adjusting plate moving means 22. When the swing plate is moved upward and the lower end of the swing plate is higher than the liquid level in the reaction tank (when fully open), the opening degree is 100%, and the swing plate is moved around the fixing member. It is set between 0 and 100% depending on the angle. The opening degree of the swing plate can be adjusted according to the detected dissolved oxygen concentration (DO value) by installing a dissolved oxygen meter (DO meter) in the reaction vessel, for example.

The swing plate has any shape such as a rectangular shape, a trapezoidal shape, a flat plate shape, etc. It may be a thing. The swing plate 20a shown in FIG. 4 is a rectangular adjusting plate curved in the lateral direction, and when installed so as to be curved in the adjusting plate moving means 22 direction (upward direction) (convex state), the upper part of the partition plate. It is preferable because it can be adjusted along the flow of the circulating flow.

The length of the swing plate in the longitudinal direction can be almost the same as the upper end of the partition plate so as to cover the entire upper part of the partition plate, but a part of the upper end of the partition plate, for example, 1/5 of the length of the upper end of the partition plate. It may be a length that covers ~ 1/2. Further, even when a plurality of partition plates are installed in the reaction tank, the swing plate does not need to be installed so as to cover the upper part of all the partition plates, and is a part of the upper end length of all the partition plates. For example, it may be installed at 1/5 to 1/2 of the upper end length of the entire partition plate. The length of the swing plate in the lateral direction is such that when the swing plate is moved in the direction of the partition plate (downward) by the adjusting plate moving means 22, the swing plate completely covers the upper part of the partition plate and almost completely covers the circulating flow. It is preferable that the length is such that it can be cut off. Further, the thickness of the swing plate may be a thickness having a strength capable of withstanding the control of the circulating flow.

The fixing member 21 is not particularly limited as long as it fixes the swing plate so that it can swing. As the fixing member 21, for example, one side of the swing plate 20a in the longitudinal direction is fixed to the side surface of the rod-shaped fixing member, and both ends of the rod-shaped member are connected to the tank wall of the reaction tank so as to be rotatable by using bearings. It can be configured. Alternatively, using a member that combines a hollow tube and a rod-shaped member penetrating the hollow tube, one side of the swing plate 20a in the longitudinal direction is fixed to the side surface of the hollow tube, and the hollow is formed. Both ends of the rod-shaped member penetrating the inside of the pipe can be fixed to the tank wall of the reaction tank. With such a configuration, the swing plate 20a can be swung up and down by the adjusting plate moving means 22 while one side of the swing plate 20a in the longitudinal direction is fixed to the fixing member, and the upper part of the partition plate can be opened and closed. can.

The position where both ends of the fixing member 21 are fixed to the tank wall of the reaction tank is from the highest liquid level in the reaction tank from the viewpoint of efficiently adjusting the amount of circulating water and reducing corrosion of the fixing member 21 by the treatment liquid. Is also preferable. Further, from the viewpoint of efficiently adjusting the amount of circulating water, both ends of the fixing member 21 are preferably fixed at positions shifted from directly above the partition plate 7 in a section other than the membrane separation unit accommodating section.

Further, the adjusting plate moving means 22 is not particularly limited as long as the swing plate can be moved up and down, but a known driving device such as an electric cylinder, a pneumatic cylinder, or a hydraulic cylinder can be used.

In addition to the circulating water amount adjusting means shown in FIG. 4, various mechanisms and shapes can be used. For example, as shown in FIG. 5, a rectangular swing plate 20c bent in the lateral direction can also be used. If such a swing plate is installed so as to be bent (convex state) in the adjusting plate moving means 22 direction (upward direction), it is preferable to adjust the upper part of the partition plate along the flow of the circulating flow. .. The circulating water amount adjusting means shown in FIG. 5 has the same configuration as the circulating water amount adjusting means shown in FIG. 4 except that the swing plate has a bent shape in the lateral direction, and can achieve the same function. can.

By using such a swing type circulating water amount adjusting device, it is possible to easily switch between the nitrification promotion operation time zone and the denitrification promotion operation time zone in a short time. Further, in a compartment other than the membrane separation unit accommodating compartment, even during the denitrification promotion operation zone, a small amount of circulating water that brings about sufficient mixing necessary for the denitrification reaction is secured, and dissolved oxygen that hinders denitrification (dissolved oxygen) DO) can be maintained at a low level, and the efficiency of removing nitrogen from organic sewage can be improved.

In the time zone for promoting nitrification (nitrification promotion operation time zone), the entire reaction vessel can be maintained in an aerobic state by increasing the opening degree of the swing plate to secure a large amount of circulating water. As a result, the nitrification reaction can be promoted.

In addition to the swing type configuration shown in FIGS. 4 and 5, a swing plate (circulating water amount adjusting plate) is fixed to the upper end of the partition plate via a hinge member or the like, and the swing plate can be attached to and detached from the adjusting plate moving means. By connecting the swing plates in this way and causing the swing plate to tip over by the adjusting plate moving means, it is also possible to use the circulating water amount adjusting means having an overturning dam structure that opens and closes the upper part of the partition plate.

Also, instead of the swing plate, a member that can be expanded or expanded by introducing air inside, such as a balloon or a hollow sheet, is installed at the upper end or upper part of the partition plate to block the circulation flow. A damming type circulating water volume adjusting means for adjusting the circulating water volume can also be used.

A second embodiment of the circulating water amount adjusting means in the present invention is a circulating water amount adjusting device provided with a slide plate 30 having an opening 31 as shown in FIG. The slide plate 30 is installed near the upper end of the partition plate 7 also having the opening 32, and when the slide plate 30 is slid in the horizontal direction, the opening 31 of the slide plate 30 and the opening 32 of the partition plate overlap. The degree can be adjusted to adjust the opening degree (aperture ratio) of the partition plate.

Here, the opening degree (opening ratio) of the slide plate is set to 0% when the opening of the partition plate and the opening of the slide plate do not overlap and the circulating flow is almost completely blocked in FIG. The case where the openings are completely overlapped with each other and fully opened is defined as 100% of the opening, and is defined as the ratio of the total area of the openings to the total area of the openings when the openings are fully opened. The opening degree (opening ratio) of the slide plate can be adjusted according to the detected dissolved oxygen concentration (DO value) by installing a dissolved oxygen meter (DO meter) in the reaction vessel, for example.

The shape of the opening of the slide plate and the partition plate can be appropriately selected from a rectangular shape, a circular shape, an elliptical shape, and the like. Further, the total area of all the openings in the total area of the slide plate is preferably about 1/3 to 2/3. The shape of the entire slide plate is not particularly limited, but usually, a rectangular plate that easily slides in the horizontal direction can be used. The slide plate 30 can be fixed near the upper end of the partition plate so as to be slidable in the horizontal direction by using a plurality of slide plate fixing members 33. The slide plate can be moved in the horizontal direction by using the slide plate moving means 34, and the slide plate moving means 34 uses, for example, a known driving device such as an electric cylinder or a pneumatic or hydraulic cylinder. be able to.

When a circulating water amount adjusting device provided with such a slide plate is used, the liquid level operating water level in the reaction tank is lower than the upper end of the opening of the slide plate and the partition plate as shown in FIG. It is preferable to set the operating water level in a range higher than about one-third from the bottom of the opening of the partition plate.

By using the circulating water amount adjusting device provided with such a slide plate, it is possible to easily switch between the nitrification promotion operation time zone and the denitrification promotion operation time zone in a short time. Further, in a compartment other than the membrane separation unit accommodating compartment, even during the denitrification promotion operation zone, a small amount of circulating water that brings about sufficient mixing necessary for the denitrification reaction is secured, and dissolved oxygen that hinders denitrification (dissolved oxygen) DO) can be maintained at a low level, and the efficiency of removing nitrogen from organic sewage can be improved.

In the time zone for promoting nitrification (nitrification promotion operation time zone), the entire reaction vessel can be maintained in an aerobic state and the nitrification reaction can be promoted by adjusting the opening ratio of the slide plate to be large. ..

A third embodiment of the circulating water amount adjusting means in the present invention is a partition plate in which a notch 40 is provided at the upper end of the partition plate as shown in FIG. The shape of the notch can be appropriately selected from a rectangle, an inverted trapezoid, an inverted triangle, a semicircle, a semicircle, and the like. The width and depth of one notch are usually 3 to 30 cm, preferably 5 to 25 cm, respectively.

When a partition plate having a notch as shown in FIG. 7 is used as a means for adjusting the amount of circulating water, the amount of circulating water is accurately and finely adjusted by adjusting the liquid level in the reaction vessel in the range of A to C (FIG. 7). It becomes possible to adjust. Specifically, when the liquid level is adjusted to a position between A and B, the amount of circulating water increases, and the entire reaction tank can be maintained in an aerobic state to promote the nitrification reaction (nitrification promotion). Operating hours). When the liquid level is adjusted to a position between B and C, it is possible to fine-tune the amount of circulating water, and during the denitrification promotion operation time, a small amount of circulation that provides sufficient mixing required for the denitrification reaction. It is possible to maintain a low level of dissolved oxygen (DO), which is an obstacle to denitrification, while securing the amount of water, and it is possible to proceed with an efficient denitrification reaction. Further, when the liquid level is adjusted to be lower than C, the inside and outside of the partition plate are divided so that there is no circulation amount.

The shape of the notch is a plurality of semi-elliptical shapes having different depths as shown in FIG. 8, in addition to the case where the plurality of notches 40 have substantially the same width and depth as shown in FIG. The cutouts 41a to 41c may be combined in a fixed repeating order. The shape of the notch is not limited to a semi-elliptical shape and may be any shape such as a rectangular shape as long as the amount of circulating water can be finely adjusted efficiently. In the case of dividers with notches of different depths, as shown in FIG. 8, the width of one notch is usually 3 to 30 cm, preferably 5 to 25 cm. Further, the depth of the notch is the deepest case, usually 20 to 60 cm, preferably 30 to 50 cm, and a shallower notch depth is supplied during the denitrification promotion operation time zone. It can be appropriately set according to the amount of circulating water to be supplied.

When a partition plate having a plurality of notches having different depths as shown in FIG. 8 is used as a circulating water volume adjusting means, the liquid level in the reaction vessel is adjusted in the range of A to E (FIG. 8). , It is possible to fine-tune the amount of circulating water with high accuracy. Specifically, when the liquid level is adjusted to a position between A and B, the amount of circulating water is maximized, and the entire reaction vessel can be maintained in an aerobic state to promote the nitrification reaction (nitrification promotion). Operating hours). When the liquid level is adjusted to a position between B and C, the circulating water volume is large, and when the liquid level is adjusted to a position between C and D, the circulating water volume is medium and the liquid level is D to D to D. When adjusted to the position between E, the amount of circulating water becomes small, and when the liquid level is adjusted to a position lower than E, the inside and outside of the partition plate are divided, and there may be no circulation amount. can.

Therefore, in the denitrification promotion operation time zone, by adjusting the liquid level to the position between B and E in FIG. 8, the circulating water amount can be finely adjusted so as to obtain the required circulating water amount, and as a result, the circulating water amount can be finely adjusted. It is possible to maintain a low level of dissolved oxygen (DO), which is an obstacle to denitrification, while ensuring a small amount of circulating water that provides sufficient mixing required for the denitrification reaction during the denitrification promotion operation time. Therefore, an efficient denitrification reaction can proceed.

In the method of Patent Document 1, the shape of the upper end of the partition plate installed in the reaction vessel is not particularly described, and it is assumed that the upper end is composed of a flat horizontal plane. In such a partition plate, in order to secure a small amount of circulation flow rate required during the denitrification promotion operation time zone, it is necessary to control the liquid level at a position of about 5 mm to 20 mm from the upper end of the partition plate, and the inflow It was difficult to accurately control the circulation flow rate due to fluctuations in the amount of sewage, the influence of impurities, and the adhesion of biofilms. On the other hand, by using the partition plate having the notch as shown in FIGS. 7 and 8, the water level difference can be formed according to the required circulating flow rate, and the circulating water amount can be controlled accurately. .. Therefore, the flow rate adjusting tank for raw water becomes unnecessary, and the capacity can be reduced even when the flow rate adjusting tank is installed.

In the membrane separation activated sludge treatment apparatus of the present invention, as the above-mentioned circulating water amount adjusting means, a swing type circulating water amount adjusting device according to the first embodiment and a notch at the upper end according to the third embodiment are provided. When the partition plates are used in combination, the amount of circulating water can be finely adjusted more accurately and efficiently. In this case, as the swing plate (circulating water amount adjusting plate) used in the first embodiment, when the swing plate (circulating water amount adjusting plate) is moved most in the direction of the partition plate (downward), the upper part of the partition plate is completely covered to allow the circulating flow. It is desirable that the size or shape is such that the cutout portion at the upper end of the partition plate, which is the third embodiment, is completely closed while blocking almost completely.

Since the apparatus and method of the present invention have a wide adjustable range of the circulating water amount by the circulating water amount adjusting means, the liquid level is adjusted by adjusting the difference between the raw water supply flow rate and the membrane filtration flow rate according to the daily fluctuation of the inflow sewage amount. It can be easily controlled. Specifically, when the liquid level in the reaction vessel becomes high, the membrane filtration flow rate may be controlled to be larger than the raw water supply flow rate, and when the liquid level is low, the raw water supply flow rate may be controlled to be larger than the membrane filtration flow rate. .. When the liquid level in the reaction tank is an intermediate liquid level, the operation is performed so that the raw water supply flow rate and the membrane filtration flow rate are substantially the same. For example, it is necessary to increase the raw water flow rate during times when the amount of inflow sewage is large. For example, it becomes easy to operate within the adjustable range of the circulating water volume.

In the present invention, unlike the method of Patent Document 1, it is not necessary to greatly change the liquid level in order to create an overflow state and a split state of the liquid inside and outside the partition plate, so that the nitrification promotion operation time zone and denitrification promotion are promoted. It is possible to continuously supply raw water to the reaction tank at a constant flow rate so that the amount of circulating water is optimal for each of the operating hours. Therefore, there is an advantage that it is not necessary to install a special raw water supply device or raw water flow rate control device. In the present invention, the "constant flow rate" may be changed as long as the flow rate is constant at a predetermined time, and may be changed to obtain an optimum flow rate.

The present invention is not limited to the above embodiment as long as it is a membrane separation activated sludge treatment apparatus and method provided with circulating water volume adjusting means, and treatment conditions other than the above and pretreatment of raw water have been well known. It can be carried out under the same conditions as the method.

The present invention further improves the nitrogen removal efficiency, can easily switch between the nitrification promotion operation time zone and the denitrification promotion operation time zone in a short time, and further, with respect to the daily load fluctuation of the inflow sewage amount. It is also possible to provide a partition plate insertion type membrane separation active sludge device and method showing high applicability.

1 Reaction tank 2 Membrane separation unit 3 Suction pump 4 Aeration means 5 Blower 6 Level sensor 7 Partition plate 8 Raw water pump 9 Raw water tank 20a, 20b, 20c Circulating water volume adjustment plate (swing plate)
21 Fixing member 22 Adjusting plate moving means 30 Slide plate 31 Slide plate opening 32 Partition plate opening 33 Slide plate fixing member 34 Slide plate moving means 40 Notches 41a, 41b, 41c Notches

That is, the present invention relates to the following (1) to ( 5 ).
(1) A membrane separation active sludge treatment apparatus having a single reaction tank for aerobic treatment and anoxic treatment, an immersion membrane separation unit arranged inside the reaction tank, and an aeration means for reaction. The tank is divided into a plurality of compartments by a partition plate whose bottom is provided so as to be separated from the bottom surface of the reaction tank, and at least one of the plurality of compartments is provided with an immersion membrane separation unit and an aeration means. Membrane separation active sludge treatment apparatus in which the aerobic compartment is used as a compartment and the other compartment is used as a compartment for switching from an aerobic state to an anoxic state and from an anoxic state to an aerobic state. The circulating water amount adjusting means is a slide plate having an opening, and is a circulating water amount adjusting device provided with a slide plate capable of adjusting the opening ratio of the opening provided in the partition plate. Membrane separation active sludge treatment equipment.

(2) The membrane separation activated sludge treatment apparatus according to (1), wherein the circulating water amount adjusting means is a means for mixing anoxic sewage in other compartments.
(3) The membrane separation activated sludge treatment apparatus according to (1) or (2), wherein the total area of all openings in the total area of the slide plate is 1/3 to 2/3.
(4) One of (1) to (3), wherein the slide plate is fixed to the upper end of the partition plate so as to be slidable in the horizontal direction by a slide plate moving means and a plurality of slide plate fixing members. The membrane separation activated sludge treatment apparatus according to the above.

( 5 ) This is a membrane separation active sludge treatment method in which aerobic treatment and anoxic treatment are performed in a single reaction tank in which the immersion membrane separation unit is arranged, and the bottom is from the bottom of the reaction tank around the immersion membrane separation unit. By partitioning with partition plates provided apart from each other and aerating from below the immersion membrane separation unit, the inside of the compartment in which the immersion membrane separation unit is arranged is maintained in an aerobic state, and the other compartments are separated. In the membrane separation active sludge treatment method for switching from an aerobic state to an anoxic state and from an anoxic state to an aerobic state, the circulating water amount is adjusted by a circulating water amount adjusting means, and the circulating water amount adjusting means has an opening. A membrane separation active sludge treatment method, which is a slide plate and is a circulating water amount adjusting device provided with a slide plate capable of adjusting the opening ratio of an opening provided in the partition plate.

Claims (8)

A membrane separation active sludge treatment apparatus having a single reaction vessel that performs aerobic treatment and anoxic treatment, an immersion membrane separation unit arranged inside the reaction vessel, and an aeration means, and the reaction vessel is a membrane separation active sludge treatment apparatus. The bottom is divided into a plurality of compartments by a partition plate provided apart from the bottom surface of the reaction tank, and at least one of the plurality of compartments is preferably provided with an immersion membrane separation unit and an aeration means. A means for adjusting the amount of circulating water is provided in the membrane separation active sludge treatment apparatus, which is an air compartment and the other compartments are used to switch from an aerobic state to an anoxic state and from an anoxic state to an aerobic state. A membrane separation active sludge treatment apparatus characterized by this. The membrane-separated activated sludge treatment apparatus according to claim 1, wherein the circulating water amount adjusting means is a swing-type circulating water amount adjusting device including a circulating water amount adjusting plate and an adjusting plate moving means for swinging the circulating water amount adjusting plate. .. The membrane separation activated sludge treatment apparatus according to claim 2, wherein the circulating water amount adjusting plate is a rectangular adjusting plate that is curved or bent in the lateral direction. The membrane separation according to claim 1, wherein the circulating water amount adjusting means is a slide plate having an opening, and is a circulating water amount adjusting device provided with a slide plate capable of adjusting the opening ratio of the opening provided in the partition plate. Activated sludge treatment equipment. The membrane separation activated sludge treatment apparatus according to claim 1, wherein the circulating water amount adjusting means is a partition plate having a notch at the upper end. The membrane separation activated sludge treatment apparatus according to claim 5, wherein the notch provided at the upper end of the partition plate is a combination of notches having different depths. The circulating water amount adjusting means is a combination of a circulating water amount adjusting plate, a swing type circulating water amount adjusting device provided with an adjusting plate moving means for swinging the circulating water amount adjusting plate, and a partition plate having a notch at the upper end. The membrane separation activated sludge treatment apparatus according to claim 1, which is a means. This is a membrane separation active sludge treatment method in which aerobic treatment and anoxic treatment are performed in a single reaction vessel in which an immersion membrane separation unit is arranged, and the bottom is separated from the bottom surface of the reaction vessel around the immersion membrane separation unit. By partitioning with the provided partition plate and aerating from below the immersion membrane separation unit, the inside of the compartment where the immersion membrane separation unit is arranged is maintained in an aerobic state, and the other compartments are in an aerobic state. A membrane separation active sludge treatment method for switching from anoxic to anoxic and from anoxic to an aerobic state, wherein the amount of circulating water is adjusted by a means for adjusting the amount of circulating water.

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