JPH07284793A - Sewage treatment tank - Google Patents

Abstract

PURPOSE:To prevent the clogging of a screen and the outflow of a carrier by dividing a treatment tank into a treatment chamber and an extraction chamber by the screen and forming a slit longitudinally to the screen. CONSTITUTION:A treatment tank 1 is divided by a screen 5 into a treatment chamber filled with a carrier 4 on which active sludge is deposited and an extraction chamber IB for discharging treated water. The extraction chamber 1B is made to be a constant volume irrespective of the capacity of the treatment tank 1, and the volume ratio of the extraction chamber 1B to the treatment chamber 1A is set up preferably to be 1/4-1/3. In the screen 5, a reinforcing ring 5a is formed with lots of flat plates 5b made of FRP or stainless steel which are installed in parallel at specified intervals and longitudinally inside the reinforcing ring 5a to form a longitudinal slit S which continues in the longitudinal direction between the flat plates 5b. The width of the slit S is about 10-mm to prevent the passage of the carrier 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment tank for purifying inflowing wastewater with activated sludge.

[0002]

2. Description of the Related Art Conventionally, water treatment with, for example, a batch type activated sludge is carried out by the method disclosed in Japanese Patent Laid-Open No. 185085. That is,
As shown in FIG. 8, according to the batch activated sludge method, first, in the inflow process, the sewage 3 is introduced into the treatment tank 1 from the outside, and then in the aeration process, the sewage 3 installed in the treatment tank 1 is dispersed. Air bubbles are discharged from the trachea or the like to disperse the sludge 2 in the wastewater 3 to cause convection inside. Next, in the precipitation step, the sludge 2 dispersed in the wastewater 3 is deposited on the bottom surface side with the passage of time. A layer 3 of clear water that has been purified above the sludge 2
A is formed, and the supernatant water 3A is discharged to the outside in the discharging step, and one cycle is completed.

The processing tank 1 is filled with a carrier 4 made of sponge, plastic, ceramic or the like.
The sludge 2 adheres to the surface of the carrier 4, and the carrier 4 to which the sludge 2 adheres is well dispersed in the wastewater 3 so that the purification treatment capacity is improved. However, the carrier 4 floating in the sewage 3 may flow out to the outside in the discharging step. In order to prevent the carrier 4 from flowing out, conventionally, for example, a screen as shown in FIGS. 9 to 11 is used, Although this screen prevents the carrier 4 from flowing out, it has a shape as shown in FIG. 9, that is, a plurality of horizontal plates 5.
In a screen in which lateral slits 52, 52 are formed between 1, 51, 51, the carrier 4 is placed in the lateral slit 52.
Is attached, and sludge, dust, hair, etc. are lateral slits 5.
There is a problem that it gets stuck in 2 and causes clogging,
Further, as shown in FIG. 10, when a screen is formed by punching metal 53 having a large number of through holes 53a, 53a, sludge, dust, etc. are similarly attached to the through holes 53a, 53a, and There is a problem that it enlarges and blocks the through hole 53a, and further, the mesh 5 as shown in FIG.
Even when the screen is composed of No. 4, there is a problem that sludge and dust adhere to the meshes and block the meshes.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above problems of the prior art, and does not provide a sewage treatment tank that does not cause clogging and can favorably prevent the carrier from flowing out. The first gist is for the purpose of
In a batch-type sewage treatment tank that performs purification treatment with activated sludge by sequentially performing steps of aeration, precipitation, and discharge of treated water, a treatment chamber formed by filling the inside of the treatment tank with a carrier to which the activated sludge adheres, That is, the drawing chamber for discharging water is partitioned via a screen, and a vertical slit is formed in at least a part of the screen. A second gist is to provide a cleaning device for removing the carrier, dust and the like attached to the screen. A third aspect is a floating type in which the cleaning device moves up and down along the slit as the water level in the processing tank fluctuates, and contacts the screen surface to remove dust and the like when the cleaning device moves up and down. The fourth gist is that in the treated water discharge step,
A prevention plate for receiving the carrier flowed from the processing chamber side to the extraction chamber side and preventing the sludge attached to the carrier from falling off,
It is provided integrally with the processing chamber side of the screen or the screen. Further, a fifth gist is a continuous type sewage treatment tank in which inflow and discharge are continuously performed to perform purification treatment with activated sludge, and the inside of the treatment tank is provided with a screen having at least a part of a vertical slit, That is, it is divided into a treatment chamber filled with a carrier to which activated sludge adheres and a drawing chamber for discharging treated water.

[0005]

In the first aspect, the inside of the treatment tank is divided into the treatment chamber and the drawing chamber by the screen, and since the screen has the vertical slits, when the treated water is drawn from the drawing chamber. Since the carrier filled in the processing chamber is not blocked by the screen and flows out to the extraction chamber side, it is possible to prevent the carrier from flowing out, and since the screen has a vertical slit. By properly circulating the carrier along the longitudinal slits, it is possible to prevent the carrier and other dust from adhering to the screen, and prevent the screen from clogging. The second
In the summary of the above, the cleaning device is operated, and the carrier, dust, etc. adhering to the screen are well removed by the cleaning device,
The screen can be prevented from clogging. Also, the third
If the cleaning device is a floating type, the floating type cleaning device moves up and down along the slit of the screen as the water level in the treatment tank fluctuates. It is possible to satisfactorily remove adhered carriers, dust, etc., and since it operates with a simple structure due to fluctuations in water level, separate equipment such as a pump is unnecessary. Further, in the fourth aspect, since the prevention plate is integrally provided on the treatment chamber side of the screen or on the screen, the prevention plate receives the carrier flowing to the screen side when the treated water is discharged from the drawing chamber. The sludge adhering to the carrier can be favorably prevented from being sucked into the extraction chamber side, and the sludge can be favorably prevented from flowing out. Further, in the fifth aspect, by installing a screen having a vertical slit in a continuous type sewage treatment tank that continuously inflows and discharges, and dividing the inside of the treatment tank into a treatment chamber and a drawing chamber,
The screen can receive the carrier and prevent the carrier from flowing out to the outside mixed with the treated water continuously withdrawn from the extraction chamber. Moreover, since the screen has a vertical slit, the carrier and dust can be prevented. It is possible to reduce the adherence of the like to the screen.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a batch type treatment tank, in which sludge 2 is deposited on the bottom side of the treatment tank 1 and sewage 3 is flown into the upper part of the treatment sewage 3 to collect sludge on the surface thereof. A large number of the adhered carriers 4 are filled, and in this example, the inside of the processing tank 1 is
It is desirable to partition the processing chamber 1A on the left side and the drawing chamber 1B on the right side through the screen 5 so that the drawing chamber 1B has a constant capacity regardless of the capacity of the processing tank 1. The chamber 1B is formed to have a volume ratio of about 1/4 to 1/3 with respect to the processing chamber 1A.

Further, the screen 5 has a structure as shown in an enlarged scale in FIG. 2, and has a ring-shaped reinforcing ring 5a arranged in contact with the inner circumference of the cylindrical processing tank 1 and this reinforcing ring. It is formed by a plurality of flat plates 5b, 5b, 5b arranged in parallel in the longitudinal direction at a predetermined interval inside the flat plate 5b.
Is made of FRP or stainless steel,
A vertical slit S continuous in the vertical direction between the flat plates 5b and 5b.
Is formed, and the width of the vertical slit S is set to about 10 mm, and the gap of about 10 mm is a gap that the carrier 4 cannot pass through.

Returning to FIG. 1, the processing chamber 1 of the screen 5 is described.
On the A side, a preventive plate 6 is arranged in parallel with the screen 5 at a distance from the screen 5, and the lower end of the preventive plate 6 is 100 to 1 from the upper surface line 2L of the sludge 2.
It is located about 50 mm above and the upper end of the prevention plate 6 is located about 300 to 500 mm below the upper surface line HWL of the dirty water 3.

In addition, the processing chamber 1A has three spaces at predetermined intervals.
The individual aeration blowers 7, 7, 7 are arranged above, and pipes 8, 8, 8 are vertically hung from the respective aeration blowers 7, 7, 7 into the processing chamber 1A. , 8,
The lower part of 8 is arranged in the sludge 2 and the air diffusers 9, 9,
9 is provided, and each aeration blower 7, 7, 7 is actuated so that the aeration pipe 9,
Bubbles are ejected from the processing chamber 1A into the processing chamber 1A.
The inside of A is configured to be aerated by the ejected bubbles.

On the other hand, in the drawing chamber 1B, a sludge drawing pump 10 arranged in the sludge 2 is provided, and a sludge drawing pipe 11 is connected to the sludge drawing pump 10 to operate the sludge drawing pump 10. By doing so, the sludge 2 can be discharged to the outside through the pipe 11. On the left side of the sludge drawing pump 10, a drawing pump 12 for drawing the treated water to the outside is provided, and the drawing pump 12 A drawing pipe 13 is connected to the. This withdrawal pump 12 is installed at a position slightly lower than the lower limit water level LWL of the sewage 3, and an inverted umbrella-shaped sludge receiver 14 is installed below the withdrawal pump 12 and the withdrawal pump 12 The structure is such that the sludge receiver 14 prevents the sludge from being sucked into the extraction pump 12 when is activated. The U-shaped air lift pipe 15 is connected to the lower part of the sludge receiver 14. Further, the lower end of an air pipe 17 connected to a blower 16 via a valve 19 is connected to the air lift pipe 15, and the tip end of the air lift pipe 15 is connected to an external sludge via a pipe 18. It is extended to the side of the concentrated storage tank. That is, when the blower 16 is actuated and the valve 19 is opened, air is blown from the air pipe 17 into the air lift pipe 15, and the sludge accumulated on the upper surface of the sludge receiver 14 along with the air rising in the air lift pipe 15 is removed. It flows through the pipe 18 and discharges the sludge to an external sludge concentration storage tank.

A pair of branched valves 20, 20 are connected to the blower 16, and each valve 2
The cleaning pipes 21 and 21 are connected to 0 and 20, respectively, and the pair of cleaning pipes 21 and 21 are connected to the screen 5
Are suspended in parallel with the screen 5 on the front and back sides, and cleaning diffusers 22 and 22 are provided at the lower ends of the cleaning pipes 21 and 21, respectively, and the blower 16 is operated to operate the diffusers 22. By blowing air from the screens 22, 22, the screen 5 is washed by the blown air, and the screens 5 are washed by the valves 20, 20, the washing pipes 21, 21, and the air diffusers 22, 22 for washing.
Of the cleaning device. That is, as shown in FIG. 3, the air blown from the cleaning air diffusers 22 and 22 is
As shown by the arrow, it vigorously flows upward, and at this time, carriers, sludge, dust, etc. adhering to the vertical slits S of the screen 5 are floated upward along the vertical slits S by the rising force of bubbles, It is possible to eliminate clogging of the vertical slit S.

Even in the aeration process in which air bubbles are jetted from the air diffusers 9, 9, 9, the sewage 3 flows in the direction of the arrow as shown in FIG. Even if sludge or the like is attached, the carrier and the sludge and the like rise along the vertical slits S due to the flow of the bubbles and the wastewater 3, so that the carrier and the sludge and the like are hardly attached to the vertical slit S, or even if they are attached. As compared with the conventional screen, the sludge is seldom enlarged in the vertical slit S to block the vertical slit S. Further, naturally, the entanglement of hair or the like floating in the dirty water 3 is reduced as compared with the conventional one, and the vertical slit S is not clogged. Also,
After the completion of the precipitation step, when the withdrawal pump 12 is operated and the supernatant water is withdrawn from the withdrawal pipe 13 to the outside,
The carrier 4 on the processing chamber 1A side is made to flow to the drawing pump 12 side, but the carrier 4 is not blocked by the screen 5 and does not flow to the drawing chamber 1B side, and the carrier 4 does not flow to the outside.

In this example, the processing chamber 1A for the screen 5 is also provided.
Since the prevention plate 6 is provided on the side, the carrier 4 flowing toward the drawing pump 12 side is received by the prevention plate 6 and the carrier 4
Is less likely to adhere to the screen 5 side, and the carrier 4
It is less likely that sludge attached to the surface will fall to the extraction chamber 1B side by the extraction force of the extraction pump 12. Even in the carrier 4 submerged in the sludge 2, when denitrifying bacteria act and nitrogen gas floats in the anaerobic state, the carrier 4 is accompanied by this.
Since it floats up in the dirty water 3, such a carrier 4 can be well received by the prevention plate 6, and the sludge adhering to the carrier 4 can be prevented from flowing out to the extraction chamber 1B side.

In FIG. 1, the prevention plate 6 is provided separately from the screen 5 on the processing chamber 1A side. However, as shown in FIG. 4, the prevention plate 6 is integrated with the screen 5. It is also possible to integrally integrate the prevention plate 6 in the center of the screen 5 in the lateral direction, receive the carrier 4 by this prevention plate 6, and prevent the sludge adhering to the surface of the carrier 4 from flowing out to the extraction chamber 1B side. be able to. The cleaning device can be controlled, for example, to open the valves 20 and 20 at the end of the aeration process and eject bubbles from the cleaning air diffusers 22 and 22 to clean the screen 5. Also, the air diffuser 2 for cleaning
By installing one of the air diffusers 9 near the screen 5 instead of 2, it is possible to perform both aeration and cleaning.

5 and 6 show another example of the cleaning device. That is, the cleaning device shown in FIG. 5 and FIG.
5 is a vertical cross section of the screen, and FIG. 6 is a flat cross section, between the flat plates 5b and 5b forming the screen 5. The connecting rods 26 are inserted into the vertical slits S of the plurality of hollow floating bodies 25 on both ends of the connecting rods 26 and on the front and back sides of the screen 5 via the connecting rods 27, respectively.
25, 25 are arranged, and the plurality of hollow floating bodies 25, 25, 25 can move up and down along the vertical slit S, and the waste water 3 flows into the treatment tank 1 to change the water level. The hollow floating body 25 rises as it rises, and the hollow floating body 25 descends due to the drop in the water level due to the treatment water being drawn out by the drawing pump 12, and especially when the hollow floating body 25 rises due to this change in the water level. Since the hollow floating body 25 swings and abuts on the back surface of the screen 5 and ascends, when the hollow floating bodies 25 come into contact with the screen 5, the carriers, sludge, dust, etc. adhering to the screen 5 are satisfactorily scratched. The screen 5 can be dropped and washed. In this way, the hollow floating body 25 always moves up and down in one cycle from the inflow process to the discharge process, so that enlargement of the biofilm on the surface of the screen 5 and accumulation of dust and the like are suppressed.

Next, FIG. 7 shows a continuous processing tank 30 provided with a screen 5. The processing tank 30 is divided by the screen 5 into a left processing chamber 30A and a right drawing chamber 30B. The treatment chamber 30A is filled with a large number of carriers having sludge attached thereto, and in the treatment tank 30, wastewater continuously flows into the treatment chamber 30A from the outside and continuously from the extraction chamber 30B. Treated water is drawn to the outside, and even in such a continuous type treatment tank 30, the screen 5 having a large number of vertical slits S shown in FIG. The vertical slit S prevents the carrier, sludge, dust, etc. from adhering to the surface of the screen 5,
It is possible to reduce clogging of the screen 5 and maintain good sewage treatment capacity.

[0017]

INDUSTRIAL APPLICABILITY The present invention relates to a batch-type sewage treatment tank in which the steps of inflowing sewage, aeration, precipitation, and discharging treated water are sequentially carried out to perform purification treatment with activated sludge. The processing chamber filled with the carrier and the extraction chamber for discharging the treated water are divided by the screen, and at least a part of the screen is formed with a vertical slit, so that the processing chamber is formed by the screen. It is possible to prevent the carrier filled in the column from flowing out to the extraction chamber side, prevent the activated sludge adhering to the carrier from flowing out to the outside, and maintain the purification treatment capacity with abundant activated sludge. Also, the vertical slits formed on the screen have very little adherence of carriers, sludge, dust, etc., and the adhered sludge etc. are well along the slit due to air bubbles during aeration. Can be separated, it may be a structure with less clogging. Further, by providing the cleaning device for removing dust and the like adhering to the screen, it is possible to more reliably prevent the screen from being blocked by cleaning the screen through the cleaning device. In addition, since the cleaning device is a floating type that moves up and down along the slit as the water level in the treatment tank changes, it does not require a separate pump or the like with a simple structure and moves up and down as the water level changes. It is possible to satisfactorily remove dust and the like adhering to the screen. Further, since the prevention plate is provided integrally with the screen on the processing chamber side or the screen, the carrier flowing to the drawing chamber side when the treated water is drawn from the drawing chamber is received by the prevention plate and adheres to the surface of the carrier. It is possible to satisfactorily prevent the sludge from being drawn to the extraction chamber side and flowing out, and it is possible to reliably prevent the sludge from flowing out. Further, in a continuous type sewage treatment tank in which inflow and discharge are continuously performed to perform purification treatment with activated sludge, the inside of the treatment tank is
A continuous type sewage treatment tank is divided into a treatment chamber filled with a carrier to which activated sludge adheres and a drawing chamber for discharging treated water through a screen having a vertical slit in at least a part thereof. Also in the above, it is possible to surely prevent the carrier filled in the processing chamber from flowing out to the extraction chamber side through the screen, and the vertical slits formed in the screen allow the carrier to the screen,
The clogging of the screen can be prevented by reducing the adhesion of sludge and the like.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a batch type processing tank.

FIG. 2 is an enlarged configuration diagram of a screen.

FIG. 3 is an explanatory diagram showing a flow direction of dirty water with respect to a screen.

FIG. 4 is an enlarged configuration diagram showing a modified example of the screen.

FIG. 5 is a side view of a floating type cleaning device.

FIG. 6 is a plan configuration diagram of FIG.

FIG. 7 is a cross-sectional configuration diagram of a continuous processing tank.

FIG. 8 is a process diagram showing a treatment process of a batch-type sewage treatment tank.

FIG. 9 is an enlarged view of a main part of a conventional screen.

FIG. 10 is an enlarged view of a main part of a conventional screen.

FIG. 11 is an enlarged view of a main part of a conventional screen.

[Explanation of symbols]

 Single batch type treatment tank 1A Treatment room 1B Extraction room 2 Sludge 3 Sewage 4 Carrier 5 Screen 5a Reinforcement ring 5b Flat plate 6 Prevention plate 7 Aeration blower 9 Aeration pipe 10 Sludge extraction pump 12 Extraction pump 14 Sludge receiver 15 Air lift pipe 16 Blow 19, 20 Valve 21 Washing pipe 22 Washing air diffuser 25 Hollow floating body 26, 27 Connecting rod 30 Continuous treatment tank 30A Treatment chamber 30B Extraction chamber S Vertical slit

Claims (5)

[Claims] 1. A batch-type sewage treatment tank in which sewage inflow, aeration, precipitation, and treated water discharge are sequentially performed to perform purification treatment with activated sludge, and the inside of the treatment tank is filled with a carrier to which the activated sludge adheres. A sewage treatment tank characterized by partitioning a treatment chamber and a drawing chamber for discharging treated water through a screen, and forming a vertical slit in at least a part of the screen. 2. The sewage treatment tank according to claim 1, further comprising a cleaning device for removing carriers, dust, and the like attached to the screen. 3. The cleaning device is of a floating type, which moves up and down along the slit as the water level in the processing tank fluctuates, and contacts the screen surface to remove dust and the like when the water moves up and down. Sewage treatment tank described in. 4. A preventive plate for receiving a carrier flowed from the treatment chamber side to the extraction chamber side in the treated water discharge step and preventing sludge from adhering to the carrier is disposed on the treatment chamber side of the screen or the screen. The sewage treatment tank according to claim 1 or 2, wherein the sewage treatment tank is provided integrally with the sewage treatment tank. 5. A continuous type sewage treatment tank in which inflow and discharge are continuously performed to perform purification treatment with activated sludge, and the inside of the treatment tank is treated with a screen having a longitudinal slit in at least a part thereof. A sewage treatment tank characterized by being divided into a treatment chamber filled with a carrier to which is attached and a withdrawal chamber for discharging treated water.