JP3469797B2 - Sewage treatment method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment apparatus for treating organic sewage, and more particularly to a sewage treatment method and apparatus for contributing to downsizing of a primary treatment tank.

[0002]

2. Description of the Related Art Conventionally, a precipitation separation tank (also called a contaminant removal tank) for precipitating and separating impurities and solids contained in the wastewater for the primary treatment of organic wastewater flowing into the wastewater treatment apparatus, and Contaminants in sewage due to combinations such as a combination of an anaerobic filter bed tank with an anaerobic filter bed that anaerobically treats, and a combination of a first chamber and a second chamber of the anaerobic filter bed tank with an anaerobic filter bed. In addition to precipitating or suspending solids or solid substances for solid-liquid treatment, sludge generated in the primary treatment stage, contact aeration tank and sedimentation tank in the secondary treatment step, or Japanese Patent Application No. 10-28242 related to the prior application It stores the returned sludge generated in the biological filtration tank filled with the fluidized bed carrier of No. -180388 and the treated water tank. Further, the treated water solid-liquid separated in the primary treatment step is secondarily treated by a contact aeration tank and a precipitation tank, or by a biological filtration tank and a treated water tank having a fluidized bed carrier structure,
It has been sterilized and then discharged.

In the case of this type of sewage treatment equipment, 1 per year
Although the treatment performance that maintains the roles of solid-liquid separation and sludge storage is guaranteed by requiring the pumping treatment more than once, the treatment of organic wastewater in recent years is a domestic wastewater containing human wastewater. Targeting the merger process of
However, in consideration of the stock of accumulated sludge, the capacity of the septic tank is much larger than the conventional septic tank.

However, when considering the housing situation in Japan, it may be difficult to install a large septic tank in a limited installation space, and when considering replacement with an existing single septic tank. It is required to secure the performance of the large sewage septic tank which is equal to or larger than the capacity of the conventional single septic tank, and the processing performance of which is equal to or larger than that.

When considering the miniaturization and compactness of this type of wastewater purification tank, first, it is required to reduce the tank capacity in the secondary treatment step. In this regard, the secondary treatment device described in Japanese Patent Application No. 10-180388, which comprises a biological filtration tank filled with the above-mentioned fluidized bed carrier and a treated water tank, can significantly reduce the capacity.

Then, secondly, the next technical problem is to significantly reduce the tank capacity for solid-liquid separation in the primary treatment step and the tank capacity for sludge storage. For that purpose, it is desired to develop a treatment means capable of effectively reducing the amount of contaminants and solids contained in the inflowing raw water, and the sludge content generated in the process of sewage treatment. In this respect, in the case of a large-scale treatment facility with several tens to several hundreds of persons to be treated, it is possible to reduce the amount of sludge by installing a mechanical sludge concentrator or sludge dewatering device during the treatment process. I am dealing with it.

[0007]

However, in order to incorporate it into a sewage purification tank intended for a small number of people such as households, a large-scale apparatus is required, and the labor and cost required for its maintenance are expensive. Therefore, it is not realistic to try to put it into practical use.

[0008] Therefore, the present inventor paid attention to the existence of scum generated in the stage of the primary treatment, and this scum has a low water content and is extremely promising as a form of sludge concentration and storage.
However, with the insight that it will occur without using equipment such as a concentrator, we will deal with reducing the volume of sludge by providing a treatment form that actively generates and stores scum. I paid attention.

[0009]

Specifically, in claim 1, the scum generated in the precipitation separation tank or generated scum is floated on the scum storage tank, and the scum stored in the scum storage tank is in a consolidated state. Concentrate and store. The solids in the inflowing sewage and the sludge settled or accumulated in the sedimentation separation tank are floated as scum by adding gas or bubbles, and the gas or bubbles are added to the separation tank by means of It will be mixed with the return water from the secondary treatment tank arranged on the downstream side, and the nitrogen gas generated as a result of the mixing will give buoyancy to the sedimented sludge settling at the bottom of the separation tank and float as scum. To do. The scum that gives buoyancy to the sedimented sludge that has settled at the bottom of the sedimentation separation tank is equipped with a scum storage tank that floats and is accommodated, thereby coping with efficient storage by actively generating scum. In addition, the scum that has been given buoyancy by flowing down the filter bed that makes the flow of sewage flowing into the sedimentation tank to settle in the sedimentation tank, or by accumulating gas and bubbles in the accumulated sludge , Floated up and stored in the scum storage tank.

According to the second aspect of the present invention, gas or bubbles are added to the solid matter in the inflowing wastewater and the sludge settled or accumulated in the sedimentation separation tank to float as scum, and the gas or bubbles are included. As the means, it is assumed that the air is intermittently diffused by the diffuser provided at the bottom of the precipitation separation tank. Due to air diffusion, buoyancy is applied to the sedimented sludge that has settled at the bottom of the sedimentation separation tank, and it floats as scum. By providing a scum storage tank in which scum that gives buoyancy to the sedimented sludge settled at the bottom of the sedimentation separation tank floats and is stored, it is possible to cope with efficient storage by actively generating scum.
In addition, the scum that has been given buoyancy by flowing down the filter bed that makes the flow of sewage flowing into the sedimentation tank to settle in the sedimentation tank, or by accumulating gas and bubbles in the accumulated sludge , Floated up and stored in the scum storage tank.

[0011]

On the other hand, as for the apparatus, in claim 3, the wastewater treatment apparatus is provided with a scum storage tank for accommodating scum generated in the precipitation separation tank. The circumference of the scum storage tank is covered by a partition wall, an upper opening of the partition wall is provided at an upper end of the partition wall so as to project to a position higher than a water level of the precipitation separation tank, and a lower portion of the partition wall of the precipitation tank. There is a lower opening that opens below the surface of the water. Occurring in the settling tank,
The generated scum is stored in the scum storage tank through the lower opening. The sedimentation separation tank is provided with a sewage return pipe from the secondary treatment tank arranged on the downstream side of the precipitation separation tank. The nitrogen gas generated by mixing with the secondary treated water that is returned from the sewage return pipe or circulated causes the scum to which buoyancy has been added to the accumulated sludge that has settled at the bottom of the sedimentation separation tank. By providing the scum storage tank, the generation of scum is promoted and the floating effect to the scum storage tank is enhanced.

Further, in claim 4, the sewage treatment apparatus is provided with a scum storage tank for storing scum generated in the precipitation separation tank. The scum storage tank is surrounded by a partition wall, an upper opening of the partition wall is provided at an upper end of the partition wall so as to project to a portion above the water level of the precipitation separation tank, and the precipitation separation tank is provided below the partition wall. There is a lower opening that opens below the water surface. The scum generated or generated in the precipitation separation tank is stored in the scum storage tank through the lower opening. An air diffuser is disposed below the lower opening of the scum storage tank,
By providing a scum storage tank in which scum having buoyancy added to the accumulated sludge settled at the bottom of the sedimentation separation tank by the air blown from the air diffuser is provided with a scum storage tank, scum generation is promoted and scum storage is promoted. Improves the floating effect on the tank.

Further, in claim 6, a filter bed for slowing the flow of the inflowing sewage is layered in the settling separation tank, and the scum floating after the filter bed has flowed down or the filter bed is settling down. Scum that has been settled in a separation tank or has accumulated buoyancy by accumulating gas or bubbles in the sludge that has accumulated, by providing a scum storage tank that floats and is stored, it promotes the generation of scum, The floating effect on the scum storage tank is enhanced.

[0015]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment according to the present invention will be described below in which a vertical sectional view and a plan view of a wastewater purification tank T shown in FIGS. 1 and 2 and a scum storage tank shown in FIG. 3 are incorporated. It will be described based on a perspective view of the precipitation separation tank.

The inside of the sewage purification tank T has a sewage treatment process from the side of the inflow pipe 1 into which the organic sewage such as human waste water and household wastewater flows into the discharge pipe 2 side of the purified treated water. According to the order, first, the primary separation apparatus is divided into a sedimentation separation tank A and an anaerobic filter bed tank B. Among them, in the precipitation separation tank A, a bottomless scum storage tank F having an opening 3 is opened. It has been incorporated. Next, a secondary treatment device including a biological filtration tank C having a carrier flow structure and a treated water tank D is provided, and finally, a secondary tank is discharged via a disinfection tank E.

Reference numeral F denotes a scum storage tank incorporated in the precipitation separation tank A, which is formed in a substantially rectangular tubular bottomless shape, and the upper end portion of which is projected above the water level line WL of the precipitation separation tank A. And the lower end of the scum storage tank F is installed above the main body bottom 5 of the sedimentation separation tank A to a depth position at a proper interval.

Reference numeral 6 denotes an overflow partition wall of the precipitation separation tank A and the next anaerobic filter bed tank B. The overflow partition wall 6 also serves as a rear partition wall of the scum storage tank F, and The left and right side partition walls 7 and the front partition wall 8 are used for
In order to secure a flat area of about a split, it is formed so as to be forward, that is, toward the inflow pipe 1 so as to have a U-shaped cross section. Therefore, when the sedimentation separation tank A is viewed in plan, the front chamber A1 formed between the front wall 9 of the main body of the wastewater purification tank T and the front partition wall 8 of the scum storage tank F, and the left and right sides of the wastewater purification tank T A left and right side chamber A2 formed between the main body side wall 10 and the left and right side partition walls 7 of the scum storage tank F, and a bottom chamber A3 formed between the lower end of the scum storage tank F and the body bottom 5. .

Reference numeral 11 denotes a rectangular tubular advection passage formed at a rear position of the side partition wall 7 of the scum storage tank F, and a lower inlet 12 thereof is opened substantially vertically to the side partition wall 7 of the scum storage tank F. The scum Y that has been formed and that has floated from the bottom chamber A3 of the precipitation separation tank A is less likely to flow into the precipitation separation tank A, and the precipitation separation chamber A
The treated water, which has been solid-liquid separated in the above, flows from the lower inflow port 12 and rises in the advection passage 11,
3 is transferred to the next anaerobic filter bed tank B.

Reference numeral 14 denotes an air diffuser, which is a bottom chamber A3 of the sedimentation separation tank A, and is laid in a pipe just below the scum storage tank F. Reference numeral 15 denotes an air supply pipe to the air diffuser 14, which is arranged along the vertical wall surface of the overflow partition wall 6.

Thus, the sewage flowing from the inflow pipe 1 into the sedimentation separation tank A flows into the front chamber A1 thereof, and is also distributed to the left and right side chambers A2 by being slightly distributed,
It flows downward in the tank of the precipitation separation chamber A. Then, the solid matter in the wastewater and the scum X that flow down from the front chamber A1 and the side chamber A2 toward the bottom chamber A3 sink to the lower edge 16 of the scum storage tank F due to the water force, and the lower edge 16 is removed. After passing through, the solid matter or scum X having a smaller specific gravity of water is gently lifted inside the scum storage tank F and floated to the surface layer portion.

In addition, solids and scum X which could not sink to the lower edge 16 of the scum storage tank F due to the water force.
Floats or floats as it is toward the surface layer of the front chamber A1 of the precipitation separation tank A, and a part thereof floats or floats on the surface layer of the side chamber A2. Among them, the solid matter and the scum X that have floated to the surface layer of the front chamber A1 flow down due to the repeated settling of water due to the next influent water flow, and eventually pass through the lower edge 16 of the scum storage tank F. Then, the scum storage tank F is lifted up and rises, whereby the scum layer Z is gradually formed on the surface layer portion, and the scum X is accumulated.

On the other hand, the solid sludge Y which has been subjected to solid-liquid treatment in the precipitation separation tank A and settled in the bottom chamber A3 at the bottom of the tank is anaerobically generated by the progress of anaerobicization due to the water temperature and hydraulic conditions. The gas is gradually contained in the accumulated sludge Y, and buoyancy with respect to the accumulated sludge Y is eventually formed by the anaerobic gas, so that a part of the accumulated sludge Y begins to separate and float up, and the scum thus formed. X rises while floating in the scum storage tank F.

Further, a short-time effusion action by the air diffuser 14 (for example, several times to several tens of seconds once or twice a day)
As a result, buoyancy against the accumulated sludge Y is positively formed, or by opening and closing the valve of the air supply pipe 15 at the time of inspection every 3 to 4 months, air is blown to the accumulated sludge Y by the air blower 14 from the air diffuser 14. By blowing, the buoyancy is given to the accumulated sludge Y, and a part of the accumulated sludge Y is separated in due time to become the scum X and float in the scum storage tank F. At that time, if the air-jetting time from the air diffuser 14 is long, the scum layer Z of the scum storage tank F is destroyed. Therefore, the air-jetting time should be a short time of several seconds to several tens of seconds. Is desirable.

Further, the returned sludge treated water and the circulated treated water generated in the secondary treatment stage described later are returned to the sedimentation separation tank A and mixed with the primary treated water and also with the accumulated sludge Y. The generated denitrifying gas imparts buoyancy to the accumulated sludge Y, so that the accumulated sludge Y becomes scum and floats in the scum storage tank F.

As described above, the scum X floated and stored in the scum storage tank F one after another causes the scum layer Z on the upper side of the scum storage tank F to gradually become a consolidated state by the buoyancy of the scum layer Z on the lower side. Then, the water content of the scum layer Z is lowered and concentrated, whereby the volume is reduced, and the water is floated and accumulated inside the scum storage tank F.

In the above case, although the accumulated sludge Y is agitated by the blast effect from the air diffuser 14, the blast time is extremely short and still intermittent. Therefore, the anaerobic property in the tank of the precipitation separation tank A is appropriately maintained, and the habit of anaerobic microorganisms is not impaired.

The scum X stored in the tank of the scum storage tank F is pulverized into a muddy state by agitating the air diffuser 14 when the sludge is collected about once a year, by agitation.
The vacuum hose does not impair the recovery workability.

[0030]

[Modification] In the case of the first embodiment described above, the main body front wall 9 and the main body bottom 5 in the wastewater purification tank T are formed in an arc shape, and the main body side wall 10 and the main body bottom 5 are formed in an arc shape. By adopting the tank form, the accumulated sludge Y is gathered immediately below the scum storage tank F and settles and accumulates, so that the floating sludge Y in the scum storage tank F is accommodated. However, as shown in the schematic perspective view of FIG. 4, when the bottom of the precipitation separation tank A has a horizontal bottom shape, the eaves 17 in which the lower portion of the scum storage tank F is expanded into a skirt shape is provided. By forming the scum, it is desirable that the scum X can be efficiently floated and accommodated in the scum storage tank F.

Further, in the case of the first embodiment, the advection passage 11 is formed at the rear inside position of the scum storage tank F.
As shown in FIG. 4, the advection passage 18 may be vertically formed at the rear outer position of the side partition wall 7 of the scum storage tank F.

[0032]

[Second Embodiment] In the case of the first embodiment described above, when the flow force of the inflow sewage from the inflow pipe 1 is strong, the inflow sewage is fed to the front partition wall of the scum storage tank F. Although the downward flow is made gentle by hitting the eaves portion 19 tilted backward to the upper portion of 8 to make it flow down, FIG.
As shown in FIG. 6 and FIG. 6, at the depth position in the middle portion of the precipitation separation tank A, the layer thickness is relatively thin and a spherical filter medium (not shown) is provided inside.
A filter bed 20 having a proper rectifying effect filled with the same and a kind of anaerobic filter bed effect is layered. As a result, when the inflowing sewage passes through the filter bed 20, it is rectified into a gentler flow force and flows down to prevent the generated scum Y from being destroyed, and the scum Y floats to the scum storage tank F. Is increasing.

[0033]

[Modification] Further, in the case of the schematic perspective view shown in FIG. 7, the eaves expanded in a skirt shape are formed in the lower portion of the scum storage tank F incorporated in the sedimentation separation tank A in which the filter bed 20 is layered. Part 1
7 and the advection passage 18 is formed at the rear outer position of the side partition wall 7 of the scum storage tank F.

The treated water solid-liquid separated in the settling separation tank A of the first or second embodiment described above is transferred from the lower inlet 12 opening at the rear position of the scum storage tank F to the advection passage 11, 18 is moved up and advancing from the overflow port 13 of the overflow partition 6 to the next anaerobic filter bed tank B.

When the treated water flowing into the anaerobic filter bed B passes through the anaerobic filter bed 21 layered in the anaerobic filter bed B in a downward flow, the spherical filter medium filled in the anaerobic filter bed 21 ( Anaerobic treatment by anaerobic microorganisms living in (not shown),
It flows into the bottom chamber 22 of the anaerobic filter bed tank B. The treated water, which has been subjected to the primary treatment, rises in the advection passage 24 formed in the overflow partition 23 between the anaerobic filter bed B and the next biological filtration tank C, and is discharged from the overflow port 25 of the overflow partition 23. It is transferred to the next biological filtration tank C.

Next, the details of the biological filtration tank C constituting the secondary treatment apparatus are disclosed in Japanese Patent Application No. 10-180388, but the biological filtration tank C is provided with the following configuration. ing.

First, an upper porous plate 30 for preventing floating of the fluidized bed carrier V and a lower porous plate 31 for preventing sedimentation of the hollow filter medium are provided above and below the biological filtration tank C. . Reference numeral 32 denotes an air diffuser, which is horizontally arranged in a grid pattern at a position near the lower porous plate 31 between the biological processing chambers partitioned by the upper porous plate 30 and the lower porous plate 31. , 70 to 80% of the volume of the fluid carrier V is filled.

Reference numeral 33 is a bottom chamber of the biological filtration tank C, and a backwash pipe 34 is provided above the bottom chamber. Reference numeral 35 is a submerged partition wall to the treated water tank D, and aerobic treated water submersible ports 36 are opened on both left and right sides of a lower end portion thereof.

Reference numeral 37 is a return air lift pipe for pumping backwashing water at the time of backwashing, and an inflow port 38 at the lower end thereof is inserted from the submerged port 36 on one side to face the vicinity of the center of the bottom chamber 33. On the other hand, the sewage return pipe 3 connected to the upper end of the
The front end discharge port 9 faces the upper part of the front chamber A1 of the precipitation separation tank A. Reference numeral 40 denotes an air lift pipe for circulating the aerobic treated water that has been secondarily treated, which is erected on the other side position of the back surface of the submerged partition wall 35, and has an inflow port 41 at the lower end of the subflow port 36 of the other side. The tip end discharge port of the circulation return pipe 42 connected to the vicinity of the anaerobic filter bed tank B is faced to the upper part thereof.

The primary treated water that has flowed into the biological filtration tank C is agitated by the diffuser pipe 32 so that the fluid carrier V in the aerobic treatment zone M above the diffuser pipe 34 is agitated.
Is slowly fluidized and biologically treated by aerobic microorganisms attached to the surface of the carrier or the inside of the carrier. In addition, the fluidized carriers come into contact with each other, adhere to the surface of the carrier, and the biofilm formed by the microorganisms is appropriately peeled off, whereby the fluidized carrier is held in an appropriate amount.

Next, the aerobic treated water biologically treated by aeration stirring is suspended in the aerobically treated water in the filtration treatment zone N by the fluid carrier V filled in the lower side of the aeration pipe 32. A physical filtration process is performed by capturing the substance, the excess biofilm separated from the carrier V, and other SS components. The treated water that has passed through the filtration treatment zone N flows down to the bottom chamber 33 of the biological filtration tank C,
The water is sent to the next treated water tank D by submerging through the submerged ports 36 formed on the left and right sides of the submerged partition wall 35.

At midnight when there is no inflow of dirty water, a backwash blower (not shown) is driven and aeration from the backwash pipe 34 of the bottom chamber 33 is ejected. Then, first, the filtration processing zone N
The fluidized carrier V of No. 3 starts to flow at once due to the aeration action from the backwash pipe 34, and the sludge and SS components accumulated between the fluidized carriers V of the filtration processing zone N and inside the carrier are fluidized, and As a result, the fluidized contact is carried out by receiving a stronger aeration and stirring action than that of the usual aeration and stirring action, and the backwashing treatment is performed on the fluidized carrier V in the filtration treatment zone N.

The backwashing water containing the surplus biofilm, sludge, SS and the like separated by the backwashing is pumped up from the inflow port 38 of the returning air lift pipe 37, and the wastewater returning pipe 3
It is returned to the precipitation separation tank A from No. 9 for reprocessing. At that time, a small amount is pumped up from the inlet 41 of the circulation air lift pipe 40 and returned to the advection chamber.

At the time of the above-mentioned backwash, a part of the fluid carrier V in the filtration treatment zone N floats to the upper side of the air diffusing pipe 32 and swirls, and a part of the fluid carrier V in the aerobic treatment zone M. However, the sedimentation flow to the lower side of the diffuser pipe 32 causes the carriers V of the filtration treatment zone N and the aerobic treatment zone M to be appropriately mixed to be in a mixed state, and again, diffusion diffusion by the diffusion pipe 32 is aerobic. The treatment is performed in the treatment zone N, and the filtration treatment in the filtration treatment zone N is performed. Therefore, by repeating the aeration and stirring by the backwash pipe 34, the filtration treatment zone N
And the fluid carrier V in the aerobic treatment zone M are appropriately switched up and down, whereby the role of the treatment function for the fluid carrier V is exchanged, so that the fluid carrier V in the biological filtration tank C is exchanged.
Of the filtration treatment zone N is effectively prevented.

The secondary treated water that has flowed down to the bottom chamber 33 of the biological filtration tank C flows into the treated water tank D after flowing through the submerged port 36 with the next treated water tank D, and disinfects the supernatant liquid. After being disinfected in the tank E, it is discharged from the discharge pipe 2.

[0046]

Since the present invention is constructed as described above,
The solid matter and scum contained in the inflowing sewage are also floated to the scum storage tank provided in the flow retention zone without destroying the scum or the like generated in the process of solid-liquid separation,
The accumulated sludge in the tank is scummed by anaerobic gas, nitrogen gas, or fumes from the air diffuser to float on the scum storage tank, and the scum floating on the scum storage tank is concentrated to a consolidated state. By storing it, it is possible to dramatically improve the volume reduction of the sludge, and to bring various effects such as contributing to downsizing and compacting of the sewage treatment tank.

[Brief description of drawings]

FIG. 1 is a vertical side view of a sewage purification tank.

FIG. 2 is a plan view of a wastewater septic tank.

FIG. 3 is a partially cutaway perspective view showing a state in which a scum storage tank is incorporated in a precipitation separation tank.

FIG. 4 is a schematic perspective view showing a modified example of the first embodiment.

FIG. 5 is a vertical cross-sectional side view showing a second embodiment in which a scum storage tank is incorporated in a sedimentation separation tank in which filter beds are layered.

FIG. 6 is a partially cutaway perspective view showing a precipitation separation tank according to a second embodiment.

FIG. 7 is a schematic perspective view showing a modified example of the second embodiment.

FIG. 8 is a cross-sectional view showing a biological filtration tank.

FIG. 9 is a perspective view showing an internal structure of a biological filtration tank.

[Explanation of symbols]

T Sewage septic tank A sedimentation tank A A1 front room A2 Side room A3 bottom chamber B Anaerobic filter bed C biological filtration tank D treatment tank E disinfection tank F scum storage tank M Aerobic treatment zone N filtration zone V fluid carrier X scum Y sediment sludge Z scum layer 1 Inlet 2 Outlet 3 Lower opening 4 Upper opening 5 Body bottom 6,23 Overflow bulkhead 7 side wall 8 front partition 9 front wall 10 Main body side wall 11, 18, 24 Moving passage 12 Lower inlet 13, 25, 28 Overflow outlet 14 Air diffuser 15 Air pipe 16 bottom edge 17, 19 eaves 20 filter bed 21 Anaerobic filter bed 22 Eave room 30 Upper perforated plate 31 Lower perforated plate 32 Air diffuser 33 Bottom chamber of biological filtration tank 34 Backflow tube 35 Submerged bulkhead to treated water tank 36 Submerged entrance to aerobic treated water 37 Airlift pipe for return 38 Inflow port at the lower end of the return air lift pipe 39 Sewage return pipe 40 Air lift pipe for circulation 41 Circulation air lift pipe inlet 42 Circulation return pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayoshi Miyauchi 33 Yamanashi, Yamayashiki-cho, Chiryu-shi, Aichi Fuji Clean Industry Co., Ltd., Water Environment Research Laboratory (56) Reference JP-A-10-202248 (JP, A) Kaihei 9-248587 (JP, A) JP-A-64-27691 (JP, A) JP-A-3-296482 (JP, A) Actual development Sho-55-31453 (JP, U) (58) Fields investigated ( Int.Cl. ⁷ , DB name) C02F 1/24

Claims (5)

(57) [Claims] 1. The method comprises the following steps of treating organic wastewater in a sedimentation separation tank, settling in the sedimentation separation tank, or accumulating gas or bubbles in the accumulated sludge to float as scum, A means for accommodating the gas and bubbles in a step of accommodating the scum in a scum storage tank is a secondary device in which the water to be treated in the precipitation separation tank is located downstream of the precipitation separation tank. In the wastewater treatment method that mixes with the return water from the treatment tank, the filter bed that moderates the flow of the inflowing wastewater into the sedimentation tank is settled down in the sedimentation tank, or the accumulated sludge is not covered with gas or A sewage treatment method characterized in that scum having buoyancy imparted by having bubbles is floated and stored in a scum storage tank. 2. The method comprises the following steps of treating organic wastewater in a sedimentation tank, that is, settling in the sedimentation tank or accumulating gas or air bubbles in the accumulated sludge to float as scum. And a step of accommodating the scum in the scum storage tank, and further, means for accommodating the gas or bubbles is intermittently diffused by an air diffuser provided at the bottom of the precipitation separation tank. In the sewage treatment method, which is the sewage treatment method, the flow of sewage flowing into the sedimentation separation tank is moderated, and the filter bed is allowed to settle in the sedimentation separation tank, or the accumulated sludge is buoyant by adding gas or bubbles. The scum provided with is floated and stored in a scum storage tank. 3. A sewage treatment apparatus having a precipitation separation tank, comprising a scum storage tank for containing scum generated in the precipitation separation tank, wherein the scum storage tank is surrounded by partition walls,
The upper end of the partition wall is provided with an upper opening projecting up to a portion above the water level in the precipitation separation tank, and the lower part of the partition wall is provided with a lower opening communicating with the water surface of the precipitation separation tank, The sewage treatment apparatus is characterized in that the precipitation separation tank is provided with a return pipe from a secondary treatment tank arranged on the downstream side of the precipitation separation tank. 4. A sewage treatment apparatus having a precipitation separation tank, comprising a scum storage tank for storing scum generated in the precipitation separation tank, wherein the scum storage tank is surrounded by partition walls,
The upper end of the partition wall is provided with an upper opening projecting to a position above the water level in the precipitation separation tank, and the lower part of the partition wall is provided with a lower opening communicating with the water surface of the precipitation separation tank. A sewage treatment apparatus, wherein an air diffuser is arranged below the lower opening of the scum storage tank. 5. A sedimentary separation tank is provided with a filter bed for softening the flow of inflowing wastewater, and the sedimentary sludge, gas, and air bubbles are deposited on the sedimentary separation tank by flowing down the filter bed. The sewage treatment apparatus according to claim 3 or 4, further comprising a scum storage tank in which the scum to which buoyancy is imparted by being floated and accommodated in the scum storage tank.