JP2022057310A - Sewage treatment apparatus and sewage treatment method - Google Patents

Abstract

To provide a sewage treatment apparatus and a sewage treatment method capable of simultaneously removing nitrogen and phosphorus from sewage and stably performing sewage treatment against a fluctuation in a flow rate of the sewage.SOLUTION: In a sewage treatment apparatus including a membrane separation device 2 and an air diffuser 4 inside a reaction tank 1, the reaction tank 1 includes: a first partition plate 7a that partitions a region where a membrane separation device 2 is arranged and a region where the membrane separation device 2 is not arranged, and a second partition plate 7b that has an upper end higher than an upper end of the first partition plate 7a in a region where the membrane separation device 2 is not arranged.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sewage treatment apparatus and a sewage treatment method.

Conventionally, a reaction tank for biologically treating sewage, a membrane separation device for removing solid matter from sewage immersed in the reaction tank and biologically treated, and a membrane separation device installed under the membrane separation device. A sewage treatment device including an air diffuser for supplying a gas such as air is known, and in the biological treatment of sewage in a reaction tank, for example, sewage is treated with organic sludge containing microorganisms, that is, so-called activated sludge. It is carried out based on the activated sludge method.

Specifically, in the activated sludge method, a nitrification reaction for converting ammonia into nitrite or nitric acid is carried out in the presence of oxygen (aerobic state). Further, a denitrification reaction is carried out to convert nitrite or nitric acid converted from ammonia into nitrogen by the nitrification reaction. Unlike the nitrification reaction performed in the presence of oxygen (aerobic state), the denitrification reaction must be performed in an oxygen-free state. The denitrification reaction may be carried out in a reaction tank different from the reaction tank in which the nitrification reaction is carried out, but in order to save space in the sewage treatment device, the nitrification reaction and the denitrification reaction are carried out in a single reaction tank. A sewage treatment device to be performed has been proposed (see, for example, Patent Documents 1 to 3).

FIG. 8 is a diagram schematically showing a conventional sewage treatment apparatus. The sewage treatment apparatus of FIG. 8 includes a reaction tank 1 for performing a nitrification reaction in an aerobic state and a denitrification reaction in an oxygen-free state, and a raw water tank 9 for supplying sewage to the reaction tank 1. 1 has a partition plate 7 for partitioning the inside of the reaction tank 1 into a plurality of sections. Specifically, the reaction tank 1 is divided into a sewage region A surrounded by a partition plate 7 and a sewage region B surrounded by the partition plate 7 and the inner wall of the reaction tank 1, and the sewage region A is a membrane separation device 2 and a dispersion. It has a trachea 4. Further, the reaction tank 1 has a sewage supply start water level LWL (Low water level) for starting the supply of sewage from the raw water tank 9 and a sewage supply stop water level HWL for stopping the supply of sewage from the raw water tank 9. (High water level), and the upper end of the partition plate 7 is located between the sewage supply start water level LWL and the sewage supply stop water level HWL.

In the sewage treatment apparatus of FIG. 8, when the water level in the reaction tank 1 reaches the sewage supply start water level LWL, the sewage supply from the raw water tank 9 is started, and when the water level reaches the sewage supply stop water level HWL, the sewage from the raw water tank 9 is started. The supply of sewage is set to be stopped, and the water level of sewage is configured to change. As a result, the water level of sewage is higher than the upper end of the partition plate 7 (hereinafter referred to as "sewage overflow position") and lower than the upper end of the partition plate 7 (hereinafter referred to as "sewage non-overflow position"). .) And go back and forth.
FIG. 9 is a diagram schematically showing the flow of sewage when the water level of the sewage in the reaction tank 1 in FIG. 8 is at the sewage overflow position.

When the water level of the sewage is at the sewage overflow position, the air supplied from the diffuser pipe 4 to the membrane separation device 2 causes the sewage to overflow the upper end of the partition plate 7 and circulate around the partition plate 7. Is formed. Due to this circulating flow, nitrite and nitric acid in the sewage region A are transferred to the sewage region B, and most of the air in the sewage region A is discharged to the outside of the reaction tank 1 without being transferred to the sewage region B. That is, when a circulating flow is formed, the nitrification reaction that converts ammonia into nitrite or nitric acid proceeds in the presence of oxygen in the sewage region A, and in the sewage region B, the nitrite that has moved from the sewage region on the circulating flow The denitrification reaction that converts nitric acid to nitrogen proceeds.

On the other hand, when the water level of the sewage is in the non-overflow position of the sewage, the flow of the sewage is divided between the sewage region A and the sewage region B, so that even if the air diffuser 4 supplies air to the membrane separation device 2. , A circulating flow circulating around the partition plate 7 is not formed. That is, in the sewage region A, the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen, and in the sewage region B, the nitrite or nitric acid transferred from the sewage region A before the sewage flow is disrupted is nitrogen. The denitrification reaction that converts to nitrite proceeds.

In the conventional sewage treatment device as shown in FIG. 8, in order to achieve good denitrification efficiency, the overflow time zone and the overflow stop time zone of the sewage are set to about 5 to 10 minutes, respectively, and overflow. The operation was repeated at intervals of 10 to 20 minutes including the time zone and the overflow stop time zone. Further, in the reaction tank 1, the volume ratio of the sewage region A, which is an aerobic zone, and the sewage region B, which is an oxygen-free zone, was set and fixed at about 1: 1 to 1: 2.

Furthermore, depending on the scale of the sewage treatment plant, the amount of sewage inflow may fluctuate significantly from day to day. For example, in a small-scale sewage treatment plant, the inflow of sewage during the high load time is two to three times the inflow of sewage during the average treatment time, and the inflow of sewage during the low load time is greatly reduced. It is about 10 to 20% of the inflow of sewage in the average time zone.

Japanese Unexamined Patent Publication No. 2004-261711 International Publication No. 2018/123647 International Publication No. 2018/198422

However, in the conventional sewage treatment apparatus (FIG. 8), since the interval in which the overflow time zone and the overflow stop time zone are combined is short, the anaerobic state required for phosphorus removal is reached from the anoxic state in the sewage region B. There was a problem that phosphorus could not be sufficiently removed. In addition, in the conventional sewage treatment equipment, the volume ratio of the aerobic zone and the anoxic zone was fixed, so the ratio of the overflow time zone and the overflow stop time zone of the sewage and the amount of air blown by the auxiliary aeration means were adjusted. However, there was a problem that it was not possible to sufficiently cope with daily flow rate fluctuations (load fluctuations).

An object of the present invention is to provide a sewage treatment apparatus and a sewage treatment method capable of simultaneously removing nitrogen and phosphorus from sewage and stably performing sewage treatment against fluctuations in the flow rate of sewage.

In order to achieve the above object, the sewage treatment apparatus of the present invention has a membrane separation device for separating contaminants contained in the sewage and bubbles in the membrane separation device inside the reaction tank for treating the sewage. In a sewage treatment device provided with an air diffuser to supply, a first partition plate for partitioning the inside of the reaction tank into a region where the membrane separation device is arranged and a region where the membrane separation device is not arranged, and the membrane. A second partition plate having an upper end higher than the upper end of the first partition plate is provided in a region where the separation device is not arranged.

In order to achieve the above object, the sewage treatment method of the present invention comprises a membrane separation device for separating contaminants contained in the sewage and bubbles in the membrane separation device inside the reaction tank for treating the sewage. A sewage treatment device including an air diffuser for supplying, and a first partition plate for partitioning the inside of the reaction tank into a region where the membrane separation device is arranged and a region where the membrane separation device is not arranged. In a sewage treatment method using a sewage treatment device including a second partition plate having an upper end higher than the upper end of the first partition plate in a region where the membrane separation device is not arranged, the sewage is said. A first overflow step that crosses the first partition plate, a non-overflow step in which the sewage does not cross the first partition plate, and a second overflow step in which the sewage crosses the second partition plate. And, characterized by having.

According to the present invention, nitrogen and phosphorus can be removed from sewage at the same time, and sewage treatment can be stably performed against fluctuations in the flow rate of sewage.

It is the top view (upper figure) and side view (lower figure) which show schematicly the sewage treatment apparatus which concerns on 1st Embodiment of this invention. It is a side view schematically showing the flow of sewage when the water level of sewage in the reaction tank in FIG. 1 is at the sewage overflow position of the first partition plate 7a. It is a side view schematically showing the flow of sewage when the water level of sewage in the reaction tank in FIG. 1 is at the sewage overflow position of the second partition plate 7b. The flow of sewage when the water level of the sewage in the reaction tank in FIG. 1 is at the sewage overflow position of the second partition plate 7b and is aerated by the auxiliary aeration device 5b in the second region Z2 is schematically shown. It is a side view which shows. It is a top view schematically showing the sewage treatment apparatus which concerns on the 2nd Embodiment of this invention. It is a top view which shows schematically the sewage treatment apparatus which concerns on 3rd Embodiment of this invention. It is a top view schematically showing the sewage treatment apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows schematically the conventional sewage treatment apparatus. FIG. 8 is a side view schematically showing the flow of sewage when the water level of sewage in the reaction tank in FIG. 8 is at the sewage overflow position.

Hereinafter, the first embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 (lower figure) is a side view schematically showing a sewage treatment apparatus according to an embodiment of the present invention.

The sewage treatment apparatus of FIG. 1 (lower figure) includes a single-tank type reaction tank 1 for biologically treating sewage. The reaction tank 1 has a rectangular parallelepiped shape, and is configured by joining four tank walls made of a rectangular plate-shaped member and a bottom surface so as to be orthogonal to each other. The reaction tank 1 includes a membrane separation device 2 that separates contaminants contained in sewage, an air diffuser 4 that supplies bubble-like air to the membrane separation device 2, a first partition plate 7a, and a second partition plate. Has 7b and. The membrane separation device 2 is connected to a suction pump 3 outside the reaction tank 1. When the suction pump 3 is driven, the biologically treated sewage is filtered by the membrane separation device 2, and the filtered water is taken out of the reaction tank 1.

The air diffuser 4 is installed in the lower part of the membrane separation device 2 and is connected to a blower (not shown) outside the reaction tank 1, and the blower supplies air to the air diffuser 4. Since the membrane separation device 2 filters sewage, sludge substances in sewage adhere to the membrane surface of the membrane separation device 2, and if the sludge substances in sewage adhering to the membrane surface of the membrane separation device 2 are left unattended, The membrane separation device 2 is clogged and sewage cannot be properly filtered. However, the air supplied from the blower to the air diffuser tube 4 is supplied to the membrane surface of the membrane separation device 2, so that sludge substances and the like are released. It prevents the film from adhering to the membrane surface of the membrane separation device 2.

The inside of the reaction vessel 1 is partitioned by the first partition plate 7a into a region in which the membrane separation device 2 is arranged and a region in which the membrane separation device 2 is not arranged. The second partition plate 7b is arranged between the first partition plate 7a and the inner wall of the reaction tank, and the region where the membrane separation device 2 is not arranged is divided into two regions by the second partition plate 7b. There is. The second partition plate 7b has an upper end higher than the upper end of the first partition plate 7a, and the difference between the upper end of the second partition plate 7b and the upper end of the first partition plate 7a is usually 3 to 50 cm. 5 to 30 cm is preferable. Since the sewage treatment apparatus of the present embodiment has two partition plates (baffles), it is also referred to as a double baffled membrane bioreactor (2B-MBR). The first partition plate 7a and the second partition plate 7b are arranged apart from the bottom of the reaction tank 1. Since the partition plate is required to be durable, it is made of a metal such as stainless steel. As the arrangement of the first partition plate 7a and the second partition plate 7b in the reaction tank 1, various embodiments can be used as shown in FIGS. 5 to 7 described later.

The first partition plate 7a and the second partition plate 7b may have a height adjusting means capable of adjusting the height at the upper end portion. Examples of the height adjusting means include a rectangular plate-shaped member fixed to the upper end of the partition plate by using a plurality of fixing members, such as a movable weir that can slide in the vertical direction. Further, it is a rectangular plate-shaped member fixed to the upper end portion of the partition plate via a hinge member or the like, and is a means for adjusting the height of the upper end portion of the partition plate by overturning the plate-shaped member. May be good. When such a height adjusting means is attached to the partition plate, it is not necessary to provide a difference in height of the upper end between the first partition plate 7a and the second partition plate 7b, and the second partition plate 7b It suffices that the upper end of the height adjusting means installed at the upper end portion of the first partition plate 7a is arranged higher than the upper end of the first partition plate 7a.

FIG. 1 (upper figure) is a top view of the sewage treatment apparatus of FIG. 1 (lower figure).
The first partition plate 7a and the second partition plate 7b each consist of four rectangular plate-shaped members. The first partition plate 7a surrounds the entire circumference of the membrane separation device 2, and the second partition plate 7b surrounds the entire circumference of the first partition plate 7a. By providing the first partition plate 7a and the second partition plate 7b, the reaction tank 1 has a first region Z1 in which the membrane separation device is arranged, and the first partition plate and the second partition plate. It is divided into a second region Z2 surrounded by a second region Z3 and a third region Z3 surrounded by a second partition plate and an inner wall of the reaction tank. The volume ratio of the first region, the second region and the third region can be selected from the optimum value according to the inflow load and the processing target, but in a general sewage system, it is 1: 1 to 2: 0. It is preferably 2 to 1.

The sewage treatment device of FIG. 1 (lower figure) includes a sewage supply means for supplying sewage to the third region Z3. The reaction tank 1 is connected to a raw water tank (not shown) for storing raw water via a raw water pump 6, and when the raw water pump 6 is driven, the sewage to be treated is a third in the reaction tank 1 by a sewage supply means from the raw water tank. It is supplied to the region Z3.

Auxiliary aeration means 5a is arranged on the side of the lower part of the membrane separation device in the first region Z1 (FIG. 1 (lower figure)), and auxiliary aeration is performed when the amount of oxygen is insufficient in the oxygen supply by the diffuser tube 4. The amount of oxygen can be supplemented by aeration from the means 5a. Further, an auxiliary aeration means 5b is arranged in the second region Z2, and by performing aeration from the auxiliary aeration means 5b, for example, the second region is preferably in an aerobic state in a high load time zone described later. Aeration can be performed. The auxiliary aeration means 5a and 5b are connected to blowers (not shown), respectively, and air is supplied from the blowers.

In the sewage in the reaction tank 1, nitrifying bacteria for performing a nitrifying reaction, denitrifying reaction executing bacteria (denitrifying bacteria) for performing a denitrification reaction, and phosphorus release and phosphorus are used to carry out the treatment of the sewage. Contains phosphorus-accumulating bacteria for ingestion. The denitrifying reaction executing bacterium is, for example, a denitrifying bacterium such as Pseudomonas denitrificans or Paracoccus denitrificans, or a heterotrophic bacterium that does not operate in an aerobic state but performs a denitrifying reaction in an oxygen-free state. .. The phosphorus-accumulating bacterium is, for example, a polyphosphate-accumulating bacterium.

FIG. 2 is a side view schematically showing the flow of sewage when the water level in the reaction tank in FIG. 1 is at the sewage overflow position of the first partition plate 7a.

When the water level in the reaction tank 1 is at the sewage overflow position of the first partition plate 7a (the position between WL1 (Water Level 1) and WL2 (Water Level 2) in FIG. 1 (lower figure)), the air diffuser 4 When air is supplied from the membrane separation device 2 to the membrane separation device 2, the sewage overflows from the first region Z1 to the upper end of the partition plate 7a and moves to the second region Z2 outside the partition plate 7a (FIG. 2). After that, the sewage descends in the second region Z2, passes through the region below the partition plate 7a, and returns to the first region Z1 inside the partition plate 7a. That is, when the water level of sewage is at the sewage overflow position of the first partition plate 7a and the sewage overflows the partition plate 7a, a circulating flow circulating around the partition plate 7a is formed. When a circulating flow is formed, for example, nitrite and nitric acid in the first region Z1 migrate to the second region Z2, and most of the air in the first region Z1 does not migrate to the second region Z2. It is released to the outside of the reaction tank 1. At this time, in the first region Z1 (aerobic compartment), the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen, and in the second region Z2 (anoxic compartment), the second region Z2 (anoxic compartment) rides on the circulating flow. A denitrification reaction that converts nitrite or nitric acid transferred from region Z1 of 1 into nitrogen proceeds.

On the other hand, the water level of sewage is at a non-overflow position of sewage (a position lower than WL1 in FIG. 1 (lower figure)), and the flow of sewage is divided between the first region Z1 and the second region Z2. At this time, even if the air diffuser 4 supplies air to the membrane separation device 2, a circulating flow circulating around the partition plate 7a is not formed. Therefore, in the first region Z1 (aerobic compartment), ammonia is introduced in the presence of oxygen. The nitrification reaction to convert to nitrite and nitric acid proceeds, and in the second region Z2 (anoxic section), nitrite and nitric acid transferred from the first region Z1 are converted to nitrogen before the flow of sewage is interrupted. The denitrification reaction proceeds.

FIG. 3 is a side view schematically showing the flow of sewage when the water level in the reaction tank in FIG. 1 is at the sewage overflow position of the second partition plate 7b.
When the water level in the reaction tank 1 is at the sewage overflow position of the second partition plate 7b (the position higher than WL2 in FIG. 1 (lower figure)), the water level of the sewage is the sewage overflow position of the first partition plate 7a. As in the case of the position (between WL1 and WL2) (FIG. 2), a circulating flow circulating around the partition plate 7a is formed. At this time, in the first region Z1 (aerobic zone), the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen, and in the second region Z2 (anoxic zone), the second region Z2 (anoxic zone) rides on the circulating flow. A denitrification reaction that converts nitrite or nitric acid transferred from region Z1 of 1 into nitrogen proceeds.

Further, in FIG. 3, the sewage that has overflowed from the first region Z1 to the upper end of the partition plate 7a also migrates to the third region Z3 outside the partition plate 7b. After that, the sewage that has migrated to the third region Z3 descends in the third region Z3, passes through the region below the partition plate 7b, and returns to the first region Z1 inside the partition plate 7a. That is, when the water level of the sewage is at the sewage overflow position of the second partition plate 7b, the first region Z1 and the third region Z3 are accompanied by the circulating flow circulating in the first region Z1 and the second region Z2. A circulating flow is formed. At this time, an anaerobic state is formed in the third region Z3.

In the present invention, the aerobic state means a state in which oxygen molecules are dissolved in sewage, and the anoxic state means that oxygen molecules are not dissolved in sewage, but bound oxygen is dissolved in the form of nitrate or nitrite. The anaerobic state is a state in which neither oxygen molecules nor bound oxygen are dissolved. The anoxic state and the anaerobic state can be confirmed or distinguished by measuring the dissolved oxygen concentration and the nitric acid concentration in the sewage with, for example, a dissolved oxygen meter or a nitric acid meter.

In FIG. 3, the anaerobic compartment of the third region Z3 and the oxygen-free compartment of the second region Z2 are the ratio of the circulating water amount of the third region Z3 to the circulating water amount of the second region Z2, that is, the second partition. It can be formed by setting the ratio of the amount of overflow water of the plate 7b to the amount of overflow water of the first partition plate 7a to 1: 1 to 1:10, preferably 1: 3 to 1: 5. Since the amount of overflow water in the partition plate is determined by the product (overflow cross-sectional area) of the overflow water depth (difference between the water level and the upper end of the partition plate) and the overflow weir length (length of the partition plate), the reaction tank 1 An anaerobic compartment (Z3) and an oxygen-free compartment (Z2) can be formed by appropriately setting the upper end positions and lengths of the partition plates 7a and 7b inside and further adjusting the water level in the reaction tank 1. .. Further, the raw water supplied to the third region Z3 by the sewage supply means contains organic substances and ammonia that consume oxygen, and the consumption of oxygen by these organic substances and ammonia is also involved in the formation of the anaerobic state.

In FIG. 3, in the third region Z3 (anaerobic compartment), a process for biologically removing phosphorus is performed. Specifically, raw water is supplied to the third region Z3 by a sewage supply means, and the raw water contains organic substances that consume oxygen, ammonia, phosphorus, and the like. Further, the sewage that overflows the upper end of the partition plate 7b and migrates to the third region Z3 contains activated sludge containing phosphorus-accumulating bacteria, and in the anaerobic third region Z3, the phosphorus-accumulating bacteria contain organic substances. It takes in and releases phosphorus. The sewage in which the amount of phosphorus dissolved is increased by the metabolism of the phosphorus-accumulating bacteria in the third region passes through the region below the second partition plate 7b and returns to the first region Z1 inside the partition plate 7a.

In the first region Z1 (aerobic zone), the phosphorus-accumulating bacteria overdose more than the amount released in the third region Z3 (anaerobic zone). That is, since the phosphorus-accumulating bacterium ingests more phosphorus than once released, the phosphorus content in the bacterium is improved. Phosphorus in the sewage can be removed from the sludge containing the phosphorus-accumulating bacteria in which an excessive amount of phosphorus has been ingested by separating the sludge containing the phosphorus-accumulating bacteria by the membrane separation device 2.

The water level of the sewage in the reaction tank 1 is generally changed by changing the supply amount of the raw water supplied from the raw water tank into the reaction tank 1 by the sewage supply means, but the suction amount of the membrane is changed. You may. Further, the sewage treatment apparatus of the present embodiment may have a water level control means for adjusting the water level in the reaction tank 1. As the water level control means, for example, there is a liquid level sensor for checking the water level in the reaction tank 1, that is, the position of the liquid surface. When the liquid level sensor detects the water level of sewage, the raw water pump 6 automatically controls the amount of raw water supplied to the reaction tank 1 by the sewage supply means.

In the present embodiment, the treatment time zone of one day is set to, for example, the normal load time zone (11:00 to 18:00, 23:00 to 23:00) based on the daily flow rate fluctuation of the sewage supplied to the sewage treatment apparatus. It can be divided into a high load time zone (8:00 to 11:00, 18:00 to 23:00) and a low load time zone (23:00 to 8:00) in advance.

The high load time zone and the low load time zone can be set based on the measured value selected from the sewage inflow amount and the sewage quality or the calculated value obtained from the measured value. Specifically, using the 1-hour value of the inflow of sewage, for example, 0.5 times or less is the low load time zone and 0.5 to 1.5 times the normal load is 0.5 times the 1-hour value of the daily average sewage amount. The time zone, 1.5 times or more, can be set as the high load time zone. In addition, not only the inflow of sewage but also the quality of sewage, for example, concentration data such as BOD (biological oxygen demand), COD (chemical oxygen demand), SS (suspended solids), etc. are acquired, and the inflow of sewage and sewage are obtained. Using the product of water quality (concentration), the load time zone can be set from the ratio to the daily average load as described above.

In a treatment plant that automatically measures sewage inflow and sewage quality, the load classification is determined by the product of the sewage inflow and sewage quality (concentration) according to the inflow load that changes from moment to moment, and the load classification is determined. You can drive. In the previous example, three load categories are shown, but more categories can be set for sewage treatment.

Next, the sewage treatment method executed by the sewage treatment apparatus (FIG. 1) according to the first embodiment of the present invention will be described.

As described above, the sewage treatment device of the present embodiment has a membrane separation device 2, an air diffuser tube 4, a first partition plate 7a, and a second partition plate 7b inside the reaction tank 1. The membrane separation device 2 is connected to the suction pump 3 outside the reaction tank 1, and the air diffuser 4 is connected to a blower (not shown) outside the reaction tank 1 (FIG. 1 (lower figure)). By the first partition plate 7a and the second partition plate 7b, the sewage treatment device is surrounded by the first region Z1 in which the membrane separation device is arranged, the first partition plate and the second partition plate. It is divided into a second region Z2 and a third region Z3 surrounded by a second partition plate and an inner wall of the reaction tank.

When the raw water pump 6 is driven, the raw water is supplied to the third region Z3 of the reaction tank 1 by the sewage supply means. The sewage supplied to the inside of the reaction tank 1 contains activated sludge containing nitrifying bacteria, denitrification reaction executing bacteria (denitrification bacteria), and phosphorus-accumulating bacteria, and the sewage is biologically treated by these bacteria. When the blower is driven, air bubbles are supplied from the air diffuser tube 4 installed at the bottom of the membrane separation device 2. When the suction pump 3 is driven, the biologically treated sewage is filtered by the membrane separation device 2, and the filtered water is sucked by the suction pump 3 and taken out of the reaction tank 1. At this time, the air supplied from the air diffuser 4 to the membrane separation device 2 collides with the membrane surface of the membrane separation device 2 and prevents sludge substances and the like from adhering to the membrane surface.

(Normal load time zone)
Hereinafter, a sewage treatment method during a normal load time period in which the amount of sewage flowing into the reaction tank 1 is an average amount will be described.
First, the water level of the sewage in the reaction tank 1 overflows the sewage overflow position of the first partition plate 7a, that is, the position of overflowing the first partition plate 7a but not the second partition plate 7b (FIG. 1). (Position between WL1 and WL2 in the figure below) is set, and sewage treatment is executed for 7.5 minutes in this state (first overflow step). At this time, by supplying air from the air diffuser 4 to the membrane separation device 2, the sewage overflows from the first region Z1 over the upper end of the partition plate 7a and shifts to the second region Z2 outside the partition plate 7a. do. After that, the sewage descends in the second region Z2, passes through the region below the partition plate 7a, returns to the first region Z1 inside the partition plate 7a, and the circulating flow circulating around the partition plate 7a flows. It is formed (Fig. 2). When a circulating flow is formed, the nitrification reaction that converts ammonia into nitrite or nitric acid proceeds in the presence of oxygen in the first region Z1 (aerobic compartment), and circulation occurs in the second region Z2 (anoxic compartment). The denitrification reaction that converts nitrite and nitric acid that have moved from the first region Z1 to nitrogen on the flow proceeds.

Next, the water level of the sewage in the reaction tank 1 is set to the sewage non-overflow position (position lower than WL1 in FIG. 1 (lower figure)) of the first partition plate 7a, and the sewage treatment is performed in this state for 7.5 minutes. (Non-overflow step). At this time, the flow of sewage is divided between the first region Z1 and the second region Z2, and a circulating flow circulating around the partition plate 7a is not formed. Therefore, in the first region Z1 (aerobic compartment), the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen, and in the second region Z2 (anoxic compartment), the flow of sewage is disrupted. A denitrification reaction that converts nitrite and nitric acid previously transferred from the first region Z1 to nitrogen proceeds.

The operation of the first partition plate 7a at the sewage overflow position (7.5 minutes) and the operation of the first partition plate 7a at the sewage non-overflow position (7.5 minutes) are combined as described above. The operation is performed for 3 intervals (45 minutes) as an interval (15 minutes). This makes it possible to efficiently proceed the nitrification reaction in the first region Z1 and the denitrification reaction in the second region Z2.

Next, the water level of the sewage in the reaction tank 1 is set to the sewage overflow position of the second partition plate 7b (the position higher than WL2 in FIG. 1 (lower figure)), and the sewage treatment is executed in this state for 5 minutes. (Second overflow step). At this time, the sewage that has overflowed from the first region Z1 to the upper end of the partition plate 7a also migrates to the third region Z3 outside the partition plate 7b. Therefore, along with the circulating flow circulating in the first region Z1 and the second region Z2, the circulating flow circulating in the first region Z1 and the third region Z3 is formed (FIG. 3). At this time, an anaerobic compartment is formed in the third region Z3.

In the third region Z3 (anaerobic compartment), phosphorus-accumulating bacteria contained in sewage take up organic matter and release phosphorus. In the third region, the sewage in which the amount of phosphorus dissolved is increased by the metabolism of the phosphorus-accumulating bacteria passes through the region below the second partition plate 7b and returns to the first region Z1 inside the partition plate 7a. In the first region Z1 (aerobic compartment), the phosphorus-accumulating bacteria overdose more than the amount released in the third region Z3 (anaerobic zone). That is, since the phosphorus-accumulating bacteria ingest more phosphorus than once released, the phosphorus content in the bacteria is improved. Phosphorus in the sewage containing phosphorus-accumulating bacteria ingested in an excessive amount is removed by separating sludge containing phosphorus-accumulating bacteria by the membrane separation device 2.

As described above, in the normal load time zone, the first region is an aerobic compartment, the second region is an oxygen-free compartment, and the third region is an anaerobic compartment, so that nitrogen and phosphorus can be simultaneously produced from the sewage. Can be removed.

(High load time zone)
Hereinafter, a method for treating sewage during a high load time period in which the amount of sewage flowing into the reaction tank 1 is large and the inflow load is large will be described.

Since the inflow of raw water containing ammonia is large during the high load time zone, aeration is performed from the auxiliary aeration means 5b installed in the second region Z2 in order to promote the nitrification reaction, and the second region Z2 is subjected to aeration. It is used as an aerobic compartment (Fig. 1 (lower figure)).

First, the water level in the reaction tank 1 is set to the sewage overflow position of the second partition plate 7b (the position higher than WL2 in FIG. 1 (lower figure)), and the sewage treatment is executed for 7.5 minutes in this state. ..

FIG. 4 shows when the water level in the reaction tank 1 in FIG. 1 is at the sewage overflow position (position higher than WL2) of the second partition plate 7b and is aerated from the auxiliary aeration device 5b in the second region. It is a side view which shows the flow of the sewage of.

When the water level in the reaction tank 1 is at the sewage overflow position of the second partition plate 7b, the second is due to the sewage overflowing from the first region Z1 to the upper end of the partition plate 7a and the aeration from the auxiliary aeration means 5b. The sewage that has risen in the region Z2 of the above is transferred to the third region Z3 outside the partition plate 7b beyond the upper end of the 7b. After that, the sewage descends in the third region Z3, passes through the region below the partition plate 7b, and reaches the first region Z1 inside the partition plate 7a and the second region Z2 inside the partition plate 7b. return. That is, a circulating flow circulating in the first region Z1 and the third region Z3 and a circulating flow circulating in the second region Z2 and the third region Z3 are formed (FIG. 4). When the circulating flow is formed, the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen in the first region Z1 (aerobic compartment) and the second region Z2 (aerobic compartment). Most of the air in the first region Z1 and the second region Z2 is discharged to the outside of the reaction tank 1 without migrating to the third region Z3, and in the third region Z3 (anoxic compartment), it becomes a circulating flow. The denitrification reaction that rides and converts nitrite and nitric acid that have moved from the first region Z1 and the second region Z2 into nitrogen proceeds.

Next, the water level of the sewage in the reaction tank 1 overflows the sewage overflow position of the first partition plate 7a, that is, a position that overflows the first partition plate 7a but does not overflow the second partition plate 7b (FIG. 1). (Position between WL1 and WL2 in the figure below)), and sewage treatment is executed for 7.5 minutes in this state. At this time, the flow of sewage is divided between the first region Z1 and the second region Z2 and the third region Z3, and the circulation flow via the third region Z3 is not formed. Therefore, in the first region Z1 (aerobic compartment) and the second region Z2 (aerobic compartment), the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen, and the third region Z3 (absent) In the oxygen section), a denitrification reaction that converts nitrite and nitric acid transferred from the first region Z1 and the second region Z2 into nitrogen proceeds before the flow of sewage is disrupted.

The operation of the first partition plate 7b at the sewage overflow position (7.5 minutes) and the operation of the first partition plate 7a at the sewage overflow position (7.5 minutes) are combined for one interval as described above. As (15 minutes), the operation of repeating the interval a plurality of times is performed. This makes it possible to perform good nitrogen removal in the third region Z3 while promoting the nitrification reaction in the first region Z1 and the second region Z2 even in the high load time zone.

By aeration from the auxiliary aeration means 5a arranged in the first region Z1 during the high load time zone, the amount of oxygen used for the nitrification reaction can be supplemented (FIG. 4). By using both the auxiliary aeration means 5a arranged in the first region Z1 and the auxiliary aeration means 5b arranged in the second region Z2, the oxygen dissolution efficiency in the sewage can be improved. Compared with the case of supplying the amount of oxygen, the amount of air blown from the blower can be reduced and energy saving can be achieved. In addition, during high load hours, sewage treatment with increased membrane flux is required as the amount of treated water increases, but energy-saving operation is realized by minimizing the amount of cleaning air from the air diffuser pipe 4. can do.

(Low load time zone)
Hereinafter, a sewage treatment method in a low load time zone in which the amount of sewage flowing into the reaction tank 1 is small and the inflow load is small will be described.

Since the inflow of raw water containing organic matter and ammonia is small during the low load time period, the third region Z3 is not used as a reaction section but is used as a raw water introduction drain, and the auxiliary aeration means 5b is stopped. , The second region Z2 is used as an oxygen-free compartment or an anaerobic compartment (FIG. 1 (below)). In addition, since the inflow amount is small, the rising speed of the water level becomes slow, so the sewage overflow time zone and the sewage overflow stop time zone are lengthened, and the interval time is set long.

First, the water level in the reaction tank 1 overflows the sewage overflow position of the first partition plate 7a, that is, a position that overflows the first partition plate 7a but does not overflow the second partition plate 7b (FIG. 1 (lower figure). ) Is set to the position between WL1 and WL2), and the sewage treatment is executed for 15 minutes in this state (FIG. 2) (first overflow step). At this time, by supplying air from the air diffuser 4 to the membrane separation device 2, the sewage overflows from the first region Z1 over the upper end of the partition plate 7a and shifts to the second region Z2 outside the partition plate 7a. do. After that, the sewage descends in the second region Z2, passes through the region below the partition plate 7a, returns to the first region Z1 which is the internal region of the partition plate 7a, and circulates around the partition plate 7a. Is formed (Fig. 2). When a circulating flow is formed, the nitrification reaction that converts ammonia into nitrite or nitric acid proceeds in the presence of oxygen in the first region Z1 (aerobic compartment), and circulation occurs in the second region Z2 (anoxic compartment). A denitrification reaction that converts nitrite and nitric acid that have moved from the first region Z1 to nitrogen on the flow proceeds.

Next, the water level of the sewage in the reaction tank 1 was set to the sewage non-overflow position of the first partition plate 7a (the position lower than WL1 in FIG. 1 (lower figure)), and the sewage treatment was executed in this state for 15 minutes. (Non-overflow step). At this time, the flow of sewage is divided between the first region Z1 and the second region Z2, and a circulating flow circulating around the partition plate 7a is not formed. Therefore, in the first region Z1 (aerobic compartment), the nitrification reaction for converting ammonia into nitrite or nitric acid proceeds in the presence of oxygen, and in the second region Z2 (anoxic compartment), the flow of sewage is disrupted. A denitrification reaction that converts nitrite and nitric acid previously transferred from the first region Z1 to nitrogen proceeds.

The second region Z2 can be changed to an anaerobic compartment after the denitrification reaction has proceeded as an oxygen-free compartment. Specifically, in the first overflow step, the water level in the reaction tank 1 is lowered to reduce the amount of overflow water in the first partition plate 7a, so that the second region Z2 is anaerobic from the oxygen-free section. Can be changed to a parcel. In the non-overflow step, the second region Z2 can be changed from the oxygen-free section to the anaerobic section by lengthening the sewage treatment time. In the second region Z2 which has become an anaerobic compartment, a step of releasing phosphorus by phosphorus-accumulating bacteria contained in sewage is executed. At this time, the sewage in which the amount of phosphorus dissolved increased due to the metabolism of the phosphorus-accumulating bacteria in the second region passes through the region below the first partition plate 7a and enters the first region Z1 inside the partition plate 7a. return. In the first region Z1 (aerobic compartment), the phosphorus-accumulating bacteria overdose more than the amount released in the second region Z2 (anaerobic compartment). Phosphorus in the sewage can be removed from the sludge containing the phosphorus-accumulating bacteria in which an excessive amount of phosphorus has been ingested by separating the sludge containing the phosphorus-accumulating bacteria by the membrane separation device 2.

In the low load time zone, the operation of the first partition plate 7a at the sewage overflow position (15 minutes) and the operation of the first partition plate 7a at the sewage non-overflow position (15 minutes) are combined. The operation is performed at a plurality of intervals as one interval (30 minutes). By lengthening the time of one interval, it is possible to sufficiently secure the nitrification time and the denitrification time according to the low inflow load and perform good nitrogen removal. Furthermore, good phosphorus removal can be achieved by lengthening the interval time and reducing the amount of overflow water. In addition, the auxiliary aeration device 5a installed in the first region Z1 is controlled so that the amount of air blown is the minimum necessary, the flux of the membrane is kept small, and the amount of aeration for cleaning the membrane from the air diffuser 4 is also the minimum necessary. To control. By performing such an operation, energy-saving operation can be realized.

As described above, the daily treatment time zone is divided into a normal load time zone, a high load time zone, and a low load time zone in advance based on the daily flow rate fluctuation of the sewage supplied to the sewage treatment device. By performing optimal sewage treatment in the first region, the second region, and the third region during the above time period, nitrogen and phosphorus are simultaneously removed from the sewage, and the sewage treatment is stable against fluctuations in the flow rate of the sewage. Can be executed and energy-saving operation can be realized.

The degree of progress of the nitrification reaction in the reaction vessel 1, the state of nitrogen removal, and the state of phosphorus removal are the redox potentials (ORPs) and the concentrations of various components in the first region, the second region, and the third region. It can be grasped from the measured value.

Since the membrane permeated water becomes the final treated water in the first region, the dissolved oxygen (DO) concentration, oxidation-reduction potential (ORP), ammoniacal nitrogen (NH4 _- N) concentration and nitric acid in the first region It is possible to judge whether or not the target water quality is obtained based on the concentration of sex nitrogen (NO ₃ -N). For example, when the NH ₄ -N concentration in the first region is higher than the target value and the DO concentration is low, it is considered that the progress of the nitrification reaction is insufficient, so that the auxiliary aeration means 5a provided in the first region It is necessary to control to increase the amount of aeration. On the other hand, when the NO ₃ -N concentration in the first region is higher than the target value and the DO concentration is high, it is considered that the denitrification reaction is excessively progressing, so that the auxiliary aeration provided in the first region is provided. It is necessary to control the aeration amount of the means 5a to be reduced. Further, in order to promote the nitrification reaction, it is preferable to set the ORP of the first region Z1 to 100 to 200 mV or more. When the ORP is lower than this, it is necessary to control to increase the aeration amount of the auxiliary aeration means 5a. Furthermore, these indicators can be judged comprehensively.

In the second region, when the operation mainly for the denitrification reaction is performed, if the concentration of NO ₃ -N is higher than the target value, the aeration amount of the auxiliary aeration means 5a provided in the first region. Need to be controlled to reduce. Further, in order to promote the denitrification reaction, it is preferable to set the ORP of the second region Z2 to -100 to 0 mV. In order to perform more preferable control according to the load state, the conditions of the first region and the third region and the measured values of other items (DO, NH4 _- N) in the second region should be taken into consideration. is important. It is preferable to prepare an arithmetic expression using the measured value in advance and control the auxiliary aeration means 5a and / or the auxiliary aeration means 5b based on this arithmetic expression.

In the third region, it is preferable to set the ORP to −200 to −100 mV when the operation is mainly performed for the release of phosphorus by phosphorus-accumulating bacteria. Further, in the first region, NO ₃ -N is not detected in order to form an anaerobic compartment, and it is preferable to maintain a state in which there is no decrease in NH ₄ -N.

As described above, the dissolved oxygen (DO) concentration, redox potential (ORP), ammoniacal nitrogen (NH ₄ -N) concentration and nitrate nitrogen (NO ₃ -N) concentration in the first region, and the second region From dissolved oxygen (DO) concentration, redox potential (ORP), ammoniacal nitrogen (NH4-N) concentration and nitrate nitrogen (NO ₃ -N) concentration, redox potential (ORP) and ammonia concentration in the third region By controlling the amount of air exposure from the auxiliary air exhaust means provided in the first region or the second region based on the selected measured value or the calculated value obtained from the measured value, the load time zone can be classified. The optimum operation method can be realized accordingly. Further, it is also possible to control the ratio of the overflow time zone and the overflow stop time zone based on the measured value or the calculated value obtained from the measured value. Further, in the processing plant where the measured values are automatically measured, appropriate operation control can be performed by setting the control method with an arithmetic expression or the like using various measurement data.

Next, the sewage treatment apparatus and the sewage treatment method according to another embodiment of the present invention will be described.

FIG. 5 is a top view schematically showing a sewage treatment apparatus according to a second embodiment of the present invention.

The sewage treatment apparatus of FIG. 5 has basically the same configuration and operation as the first embodiment (FIG. 1), and has a second partition plate 7b and a tank wall of the reaction tank at the four corners of the reaction tank 1. It differs from the first embodiment (FIG. 1) in that a plurality of third regions Z3 surrounded by are formed. In the following, explanations will be omitted for overlapping configurations and actions, and explanations will be given for different configurations and actions.

In FIG. 5, the second region Z2 in the reaction tank 1 is surrounded by the four tank walls of the reaction tank 1 in addition to the first partition plate 7a and the second partition plate 7b. Further, a third region Z3 is arranged at each of the four corners in the reaction tank 1. Here, the four corners of the reaction tank 1 refer to four joint portions in which the four tank walls constituting the reaction tank 1 are joined to each other. That is, in the present embodiment, the reaction tank 1 is surrounded by a first partition plate 7a and a first region Z1 in which a membrane separation device is arranged, a first partition plate, a second partition plate, and a reaction tank. It is divided into a second region Z2 surrounded by the inner wall of the reaction tank and four third regions Z3 surrounded by the second partition plate and the inner wall of the reaction tank.

By arranging the third region Z3 at the four corners of the reaction tank 1 as shown in FIG. 5, the water level in the reaction tank 1 is adjusted to the sewage overflow position of the second partition plate 7b (from WL2 in FIG. 1 (lower figure)). When set to (corresponding to a high position), the circulating flow circulating in the first region Z1 and the third region Z3 is a circulating flow along the diagonal direction connecting the center and the four corners of the reaction vessel 1. Since all four third regions Z3 formed in the reaction vessel 1 have the same positional relationship with the first region Z1, they form an oxygen-free state or an anaerobic state equally with the four third regions Z3. It has the advantage that it is easy to control the anoxic state or the anaerobic state. In addition, when remodeling an existing water treatment facility, there is an advantage that it is easy to apply when the reaction tank shape is close to a square.

FIG. 6 is a top view schematically showing a sewage treatment apparatus according to a third embodiment of the present invention.

The structure and operation of the sewage treatment apparatus of FIG. 6 are basically the same as those of the first embodiment (FIG. 1), and the first region Z1 in which the membrane separation apparatus 2 is arranged is one of the reaction tanks 1. In that the third region Z3 is arranged in the vicinity of the inner wall, the third region Z3 is arranged in the vicinity of the inner wall facing the one inner wall, and the second region Z2 is arranged between the first region and the third region. It is different from the first embodiment (FIG. 1). In the following, explanations will be omitted for overlapping configurations and actions, and explanations will be given for different configurations and actions.

In FIG. 6, the first region Z1 is surrounded by three inner walls of the reaction tank 1 in addition to the first partition plate 7a, and is arranged in the vicinity of one inner wall of the reaction tank 1. The second region Z2 is surrounded by two facing inner walls of the reaction tank 1 in addition to the first partition plate 7a and the second partition plate 7b. That is, in the present embodiment, the reaction tank 1 is surrounded by three inner walls of the first partition plate 7a and the reaction tank 1, and the first region Z1 in which the membrane separation device is arranged and the first partition plate. A second region Z2 surrounded by 7a, a second partition plate 7b, and two opposing inner walls of the reaction tank 1, and a third region Z3 surrounded by the second partition plate and the three inner walls of the reaction tank 1. It is divided into.

As shown in FIG. 6, by arranging the first region, the second region, and the third region as a cohesive region inside the reaction vessel 1, equipment such as a membrane separation device can be arranged. It is easy to control the circulation flow velocity. In addition, when remodeling an existing water treatment facility, there is an advantage that it is easy to apply when the reaction tank shape is an elongated rectangular shape.

FIG. 7 is a top view schematically showing a sewage treatment apparatus according to a fourth embodiment of the present invention.

The sewage treatment apparatus of FIG. 7 has basically the same configuration and operation as those of the third embodiment (FIG. 6), and the third region Z3 is surrounded by the second partition plate 7b. It differs from the third embodiment (FIG. 6) in that it is divided into regions and the four regions Z3 are arranged so as to be in contact with the first partition plate 7a. In the following, explanations will be omitted for overlapping configurations and actions, and explanations will be given for different configurations and actions.

In FIG. 7, four third regions Z3 exist in the reaction tank 1, and each region Z3 is surrounded by a second partition plate 7b composed of four rectangular plate-shaped members, and the first region Z3 is surrounded by a second partition plate 7b. It is arranged so as to be in contact with the partition plate 7a of. Further, the second region Z2 includes a tank wall facing the tank wall located in the vicinity of the membrane separation device 2, two tank walls joined to the tank wall, a first partition plate 7a, and a second partition plate. It is surrounded by 7b. Since the second partition plate 7b is arranged so as to be separated from the bottom of the reaction tank 1 and in contact with the partition plate 7a, the second partition plate 7b is placed in the reaction tank 1 in a stable state by using a plate material or a steel material. It is desirable to fix it. That is, in the present embodiment, the reaction tank 1 is surrounded by the first partition plate 7a and the three inner walls of the reaction tank 1, and the first region Z1 in which the membrane separation device is arranged and the first partition. It is divided into a second region Z2 surrounded by a plate 7a, a second partition plate 7b, and three inner walls of a reaction vessel, and four third regions Z3 surrounded by a second partition plate 7b.

A large water pressure may be applied to the first partition plate 7a depending on the difference in water level between the first region and the second region. As in the present embodiment, a plurality of third regions Z3 surrounded by a second partition plate 7b are provided inside the reaction tank 1, and the plurality of third regions Z3 are used as the first partition plate 7a. By arranging them so as to be in contact with each other, there is an advantage that the second partition plate 7b functions as a reinforcing material for the first partition plate 7a, and the sewage treatment device having high durability can be obtained.

Although the present invention has been described above with reference to the above-described embodiment, the present invention is not limited to the above-mentioned embodiment.

The present invention can provide a sewage treatment apparatus and method capable of simultaneously removing nitrogen and phosphorus from sewage and stably performing sewage treatment against fluctuations in the flow rate of sewage.

1 Reaction tank 2 Membrane separation device 3 Suction pump 4 Diffusing pipe 5a, 5b Auxiliary aeration means 6 Raw water pump 7a First partition plate 7b Second partition plate Z1 First region Z2 Second region Z3 Third region

Claims (15)

In a sewage treatment device provided with a membrane separation device for separating pollutants contained in the sewage and an air diffuser for supplying air bubbles to the membrane separation device inside a reaction tank for treating sewage.
A first partition plate that partitions the inside of the reaction vessel into a region where the membrane separation device is arranged and a region where the membrane separation device is not arranged.
A second partition plate having an upper end higher than the upper end of the first partition plate in a region where the membrane separation device is not arranged,
A sewage treatment device characterized by being equipped with. The reaction tank reacts with the first region in which the membrane separation device is arranged, the second region surrounded by the first partition plate and the second partition plate, and the second partition plate. The sewage treatment apparatus according to claim 1, further comprising a third region surrounded by an inner wall of the tank. The reaction tank includes a first region in which the membrane separation device is arranged, a second region surrounded by the first partition plate, the second partition plate, and the inner wall of the reaction tank, and the second. The sewage treatment apparatus according to claim 1, further comprising a third region surrounded by a partition plate and an inner wall of the reaction tank. The sewage treatment apparatus according to claim 2 or 3, further comprising a sewage supply means for supplying sewage to the third region. The sewage treatment apparatus according to any one of claims 2 to 4, wherein an auxiliary aeration means is provided in the second region. The present invention according to any one of claims 2 to 5, wherein the volume ratio of the first region, the second region, and the third region is 1: 1 to 2: 0.2 to 1. The described sewage treatment device. The sewage treatment apparatus according to any one of claims 1 to 6, wherein at least one of the first partition plate and the second partition plate is provided with a water level adjusting means at the upper end. .. A sewage treatment device including a membrane separation device for separating contaminants contained in the sewage and an air diffuser for supplying air bubbles to the membrane separation device inside a reaction tank for treating sewage. The first partition plate for partitioning the inside of the tank into a region where the membrane separation device is arranged and a region where the membrane separation device is not arranged, and the first partition plate where the membrane separation device is not arranged. In a sewage treatment method using a sewage treatment device including a second partition plate having an upper end higher than the upper end of the partition plate.
In the first overflow step where the sewage crosses the first partition plate,
A non-overflow step in which the sewage does not cross the first partition plate,
A second overflow step in which the sewage crosses the second partition plate, and
A sewage treatment method characterized by having. The reaction tank reacts with the first region in which the membrane separation device is arranged, the second region surrounded by the first partition plate and the second partition plate, and the second partition plate. The sewage treatment method according to claim 8, further comprising a third region surrounded by an inner wall of the tank. The reaction tank includes a first region in which the membrane separation device is arranged, a second region surrounded by the first partition plate, the second partition plate, and the inner wall of the reaction tank, and the second. The sewage treatment method according to claim 8, further comprising a third region surrounded by a partition plate and an inner wall of the reaction tank. The invention according to any one of claims 8 to 10, wherein a high load time zone and / or a low load time zone is preset based on the daily flow rate fluctuation of the sewage supplied to the sewage treatment apparatus. The described sewage treatment method. In the high load time zone, the second region surrounded by the first partition plate and the second partition plate, or the first partition plate, the second partition plate, and the inner wall of the reaction tank. The sewage treatment method according to claim 11, wherein a second region surrounded by is an aerobic compartment. In the low load time zone, the second region surrounded by the first partition plate and the second partition plate, or the first partition plate, the second partition plate, and the inner wall of the reaction tank. The sewage treatment method according to claim 11, wherein the second region surrounded by is an oxygen-free section or an anaerobic section. 11. The high load time zone and / or the low load time zone is set based on a measured value selected from the inflow amount of sewage and the quality of sewage or a calculated value obtained from the measured value. The sewage treatment method according to any one of 13 to 13. Dissolved oxygen (DO) concentration in the first region, redox potential (ORP), ammoniacal nitrogen (NH ₄ -N) concentration and nitrate nitrogen (NO ₃ -N) concentration, dissolved oxygen in the second region. From (DO) concentration, redox potential (ORP), ammoniacal nitrogen (NH ₄ -N) concentration and nitrate nitrogen (NO ₃ -N) concentration, redox potential (ORP) and ammonia concentration in the third region. The claim is characterized in that the amount of air exposure from the auxiliary air exhaust means provided in the first region or the second region is controlled based on the selected measured value or the calculated value obtained from the measured value. The sewage treatment method according to any one of 9 to 14.

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