JPH09117785A - Waste water treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the frequency of screen cleanings and to reduce the running coat by generating a water current with an air lifting action as the power in a passage between a guide plate almost parallel to the face of a screen provided in a treating tank and the screen. SOLUTION: The bubble caused by the air aerated into a treating tank 12 from a diffuser plate 22 is collected between a guide plate 38 and a bubble collecting plate 54, and the liq. surface 46 between the guide plate 38 and bubble collecting plate 54 is raised above the other liq. surfaces of the nitration tank 12 by the air lifting action. The liq. surface 46 flows into a passage 40 from the upper opening 44 of the passage 40 and then descends to form a water current 55 flowing out of the lower opening 52. Consequently, a water current parallel to the face of a screen 20 is generated, and the solid and fibrous matter such as hair in the waste water are hardly deposited on the screen 20. Since the deposit on the screen 20 is rubbed off by the water current, the screen is cleaned, and the clogging of the screen 20 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment device, and more particularly to a wastewater treatment device provided with a screen for preventing outflow of a carrier on which microorganisms are immobilized at a discharge port of a treatment tank.

[0002]

2. Description of the Related Art In the case of a biological wastewater treatment apparatus, for example, a nitrifying apparatus, nitrifying bacteria are difficult to reproduce. The waste water is biologically treated by bringing the wastewater and the carrier into contact with each other under aerobic conditions with air aerated into the treatment tank. In this case, a screen is provided at the outlet of the nitrification tank so that the carrier charged into the nitrification tank is not washed away, but solid components in waste water and fiber components such as hair adhere to the screen due to long-term use. Clogging occurs.

Conventionally, as a measure for preventing the clogging of the screen, an air ejecting device is provided below the screen, and rising screen air bubbles ejected from the air ejecting device toward the screen collide with the screen to clean the screen surface. Was.

[0004]

However, in the conventional structure in which the screen is cleaned by providing the air jetting device below the screen and causing the bubbles to collide with the screen, the inside of the nitrification tank is kept in an aerobic state. Due to the water flow generated in the nitrification tank by the aeration air from the air aeration means, the direction of the rising bubbles from the air ejection device often changes and the bubbles do not often collide effectively with the screen. It had the drawback of having to manually clean it regularly. In addition, in order to reduce the cleaning frequency of the worker, the amount of air ejected from the air ejection device must be extremely increased, which has a drawback of increasing running cost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wastewater treatment apparatus which can reduce the number of times a worker needs to clean a screen and can reduce operating costs. .

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention biologically treats the wastewater by contacting a wastewater with a carrier on which microorganisms are immobilized in a treatment tank, and further treating the wastewater. In a wastewater treatment device in which a screen is provided at the discharge port of the tank to prevent the carrier from flowing out of the treatment tank, the inside of the screen in the treatment tank is made substantially parallel to the screen surface. A guide plate is provided to form a flow path between the screen and the guide plate, and a water flow is generated in the flow path, which is powered by the air lift action by the air from the air jetting means.

According to the present invention, the guide plate is provided parallel to the surface of the screen to form the flow path between the screen and the guide plate, and the air is ejected from the air ejecting means into the flow path. A stream of water was generated. In this way, by generating a water flow parallel to the screen surface, solid components in waste water and fiber components such as hair are less likely to adhere to the screen. Further, since the deposits attached to the screen are scraped off by the water stream, the screen is washed. This can prevent clogging of the screen. In addition, since the water flow is generated by using the air lift action as power, the carrier is not damaged unlike the case of a pump or the like. Also, if the air source for generating the air lift function is also used as the air aeration device that supplies air to the microorganisms carried on the carrier, no special air jetting means for generating the water flow is required, and the running cost is increased. do not do.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a wastewater treatment apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view illustrating a first embodiment of a wastewater treatment apparatus of the present invention, which is an example of application as a nitrification apparatus. In addition to activated sludge, a carrier carrying nitrifying bacteria is introduced into the nitrification apparatus. To be done. FIG. 2 is a cross-sectional view of the main part of FIG. The description of activated sludge in the drawing is omitted.

As shown in FIG. 1, the nitrification apparatus 10 mainly comprises a nitrification tank 12 into which wastewater containing organic substances and ammonia nitrogen components, such as sewage, flows, and a nitrification tank 12
At the bottom of the inside, an air aeration device 16 for supplying air to the microorganisms carried on a large number of carriers 14, 14, ..., a wastewater inflow pipe 18, and an outlet for the treated water treated in the nitrification tank 12 The screen 20 is provided and a water flow generation mechanism that generates a water flow along the surface of the screen 20.

The air aeration device 16 is provided with a plurality of air diffuser plates 22, 22, ... Arranged to cover almost the entire area near the bottom of the nitrification tank 12, and the air diffuser plate 22 is compressed via an air pipe 24. The blower 26 supplies air. The screen 20 is provided so as to be inclined toward the bottom of the nitrification tank 12, and as shown in FIG. 2, a large number of wedge wires 30, 30, ... Are arranged vertically. Also, screen 2
At the upper end of 0, a rectangular upper plate 32 is provided along the width direction of the screen 20 so that the treated water treated in the nitrification tank 12 will not be discharged beyond the screen 20. The lower end of the screen 20 is fixed to a substantially horizontal support plate 34 supported on the side wall of the nitrification tank 12,
The side wall of the nitrification tank 12 and the support plate 34 form a trough 36 that guides the treated water that has passed through the screen 20 to the outside of the nitrification apparatus 10. As a result, part of the treated water and activated sludge treated in the nitrification tank 12 passes through the screen 20 and the trough 3
6, the carrier 14 put into the nitrification tank 12 while flowing out to
The screen prevents the outflow to the outside of the nitrification tank 12.

Next, a water flow generating mechanism for generating a water flow along a large number of wedge wires 30 of the screen will be described. A guide plate 38 is provided inside the screen 20 in the nitrification tank 12 in parallel to the surface of the screen 20, and a flow path 40 is formed between the screen 20 and the guide plate 38. The upper end 42 of the guide plate 38 is bent obliquely upward, and the upper opening 44 of the flow path 40 is formed in the vicinity of the liquid surface 46 in the shape of a trumpet tube. Further, the lower end portion 48 of the guide plate 38 is bent obliquely downward and the screen 20
At the lower end of the parallel plate 5 parallel to the lower end 48 of the guide plate 38
0 is provided. The parallel plate 50 forms the lower opening 52 of the flow path 40 together with the guide plate 38, and the diffuser plate 22.
It serves to prevent the air aerated from the inside of the channel 40 from intruding through the lower opening 52 of the channel 40.

A foam collecting plate 54 is formed inside the screen 20 in the nitrification tank 12 to form a V-shaped cross section with the guide plate.
Is provided. Thereby, the diffuser plate 22 to the nitrification tank 12
It becomes easy to collect air bubbles due to the air aerated therein between the guide plate 38 and the foam collecting plate 54. Next, the operation of the nitrification device 10 to which the wastewater treatment device of the present invention is applied will be described.

Raw wastewater such as sewage flows into the nitrification tank 12 through an inflow pipe 18. In the nitrification tank 12, the carrier 14 carrying the activated sludge and the nitrifying bacteria and the wastewater are brought into contact with each other in an aerobic state by the aeration air from the diffuser plate 22. As a result, nitrification treatment of the waste water is performed. The treated water that has been subjected to the nitrification treatment in the nitrification tank 12 passes through the screen 20 and is discharged to the trough 36, and is sent to the next treatment step.

In this nitrification treatment, solids in waste water and fibers such as hair adhere to the screen 20, and the screen causes clogging due to the adhered substances. However, in the present invention, the air bubbles aerated from the air diffuser plate 22 into the processing tank 12 gather between the guide plate 38 and the foam collecting plate 54, and the air lift action of the air causes the guide plate 38 to move.
The liquid level 46 between the bubble collecting plate 54 and the bubble collecting plate 54 rises above the other liquid level 46 in the nitrification tank 12. The raised liquid level 46 flows into the flow path 40 from the upper opening 44 of the flow path 40, descends in the flow path 40, and forms a water flow 55 flowing from the lower opening 52. As described above, by generating the water flow parallel to the surface of the screen 20, the solid content in the waste water and the fiber content such as hair are less likely to adhere to the screen 20. Also, the screen 20
Since the adhered matter adhered to the is scraped off by the water flow, the screen 20 is washed. This allows the screen 20
Clogging can be prevented. Therefore, the frequency of cleaning the screen 20 by the worker can be significantly reduced, so that the labor of the worker can be reduced and the operating cost can be reduced.

In preventing clogging of the screen 20, the flow velocity of the water flow 55 for cleaning the screen 20 is different from the flow velocity of the treated water in the nitrification tank 12 passing through the screen 20 and flowing out to the trough 36. By setting it to be 5 times or more, the clogging of the screen 20 can be prevented more effectively. In order to obtain the water flow 55 that meets this set condition, the guide plate 3 is operated by the air lift action.
The liquid level 46 between 8 and the foam collecting plate 54 is 5 cm higher than the other liquid levels.
It is preferable to increase it above.

Further, according to the present invention, since the water flow 55 is generated by the air lift action, the carrier 14 in the nitrification tank 12 is not destroyed unlike the case where the water flow is generated by the pump. Further, since the air diffuser plate 22 for supplying air to the microorganisms carried on the carrier 14 can also serve as an air source for generating the air lift action, the running cost does not increase. Therefore, the amount of air used can be significantly reduced as compared with the conventional wastewater treatment device in which bubbles are made to collide with the screen 20 to clean the screen 20, resulting in a reduction in air cost.

Next, a second embodiment of the wastewater treatment apparatus of the present invention will be described with reference to FIGS. 3 and 4. The same members and devices as those described in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The second embodiment more effectively achieves the rise of the liquid surface 46 by the air lift action. That is, similar to the first embodiment, the guide plate 38 is provided inside the screen 20 in the nitrification tank 12 in parallel with the surface of the screen 20. This guide plate 3
A distribution gutter 56 is arranged in the vicinity of the upper end of 8 along the longitudinal direction of the screen 20, and a side plate 56A of the distribution gutter 56 on the screen 20 side is connected to the upper end of a guide plate 38 and is opposite to the screen 20. The side plate 56B is formed to have a height larger than that of the side plate 56A. A plurality of air lift pipes 58 are connected to the distribution gutter 56, and the air lift pipes 58 are provided vertically from the bottom of the distribution gutter 56 to the vicinity of the bottom of the nitrification tank 12. Also, air lift piping 5
An air supply portion 58A having a slightly larger diameter is formed in the middle of 8, and the blower 2 is provided in the air supply portion 58A.
The air pipe 24 connected to 6 is communicated. This allows
The air lift action is easily generated in the air lift pipe 58, and the liquid level in the distribution gutter 56 can be effectively raised with a small amount of air. In addition, a weir 60 that is vertically movable along the longitudinal direction is provided in the distribution gutter 56. This dam 6
0 causes the liquid level in the distribution gutter 56 to exceed the weir 60,
Since the water flows evenly to 0, the water flow 55 can be generated uniformly over the entire area of the screen 20 in the longitudinal direction. Further, by adjusting the height of the weir 60, the flow path 40
It is possible to adjust the flow velocity that drops into the channel, that is, the flow velocity in the flow channel 40.

Therefore, according to the second embodiment, in cleaning the screen 20 with the water flow, the screen 20
There is no variation in the partial cleaning of the screen 20
The whole can be washed evenly. Further, the amount of air that generates the water flow 55 can be small. Next, a third embodiment of the wastewater treatment apparatus of the present invention will be described with reference to FIG. The same members and devices as those described in the first and second embodiments are designated by the same reference numerals and the description thereof will be omitted.

In the first and second embodiments, the downward flow is generated in the flow passage 40 by raising the liquid level 46, but in the third embodiment, the air lift action is applied to the flow passage 40. This is a case where the screen 20 is washed by generating an upward flow. As shown in FIG. 5, the pair of plate members 6 are provided at the lower ends of the screen 20 provided vertically and the guide plate 62 provided vertically like the screen 20, respectively.
A foam collecting guide path 64 is formed by facing the air-conditioning elements 3 and 63 in a V shape, and the air aerated from the diffuser plate 22 is collected.
It is introduced into the flow channel 40 at 4 to generate an upward flow in the flow channel 40. This pair of plate members 63, 63
One of the plate members 63 also forms the bottom surface of the trough 36. Further, the distance L between the screen 20 and the guide plate 62
In consideration of the relationship with the amount of air from the diffuser plate 22, the screen 20 is washed with respect to the flow velocity at which the treated water in the nitrification tank 12 passes through the screen 20 and flows out to the trough 36. The flow rate of the water flow 66 is set to be 5 times or more.

According to the third embodiment, similarly to the first and second embodiments, the water flow 66 is generated in the flow channel 40, and the screen 20 is washed by the same. However, in the case of the third embodiment, unlike the first and second embodiments, since the direction of the water flow 66 is the upward flow, in addition to the cleaning of the screen 20 by the water flow 66, the screen 20 by bubbles is used. Wash at the same time. That is, the air bubbles ejected from the air diffuser plate 22 rise while coming into contact with the screen 20, so that the screen 20 can be cleaned by both the water flow 66 and the air bubbles.

In the present embodiment, the example of the nitrification apparatus has been described, but the present invention is not limited to this, and a treatment provided with a screen for preventing the carrier on which microorganisms are immobilized from flowing out of the treatment tank. Applies to all tanks.

[0022]

As described above, according to the waste water treatment apparatus of the present invention, the water flow parallel to the screen surface is generated, so that, for example, the solid content or the fiber content in the waste water adheres to the screen. It becomes difficult to do so, and since the adhered matter adhered to the screen is scraped off by the water flow, the screen is cleaned. Therefore, it is possible to effectively prevent clogging of the screen. Moreover, since the water flow is generated by the air lift action, the carrier in the processing tank is not destroyed.

Therefore, as compared with the conventional wastewater treatment apparatus for cleaning the screen by colliding bubbles with the screen, it is possible to reduce the number of times the worker cleans the screen and to reduce the operating cost.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view illustrating a first embodiment of a wastewater treatment device according to the present invention.

FIG. 2 is a cross-sectional view of a main part showing a main part of a wastewater treatment device according to the present invention.

FIG. 3 is a vertical cross-sectional view illustrating a second embodiment of a wastewater treatment device of the present invention.

FIG. 4 is a plan view of FIG. 3 seen from above.

FIG. 5 is a vertical cross-sectional view illustrating a third embodiment of the wastewater treatment apparatus of the present invention

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Nitrification device 12 ... Nitrification tank 14 ... Nitrifying bacteria-carrying carrier 16 ... Air aeration device 20 ... Screen 22 ... Diffuser plate 26 ... Blower 36 ... Trough 38 ... Guide plate 40 ... Flow paths 55, 66 ... Water flow 56 ... Distribution gutter

Claims (5)

[Claims] 1. A biological treatment of the wastewater is carried out by bringing the wastewater into contact with a carrier on which microorganisms are immobilized in a treatment tank.
In a wastewater treatment apparatus in which a screen is provided at the discharge port of the treatment tank to prevent the carrier from flowing out of the treatment tank, the inside of the screen in the treatment tank is substantially parallel to the screen surface. A wastewater characterized by forming a flow path between the screen and the guide plate as described above, and generating a water flow powered by the air lift action by the air from the air jetting means in the flow path. Processing equipment. 2. A foam collecting plate that forms a V-shaped cross section with the guide plate is provided inside the screen in the processing tank, and the air jetting means is arranged below the guide plate and the foam collecting plate. Then, a downward flow is generated in the flow path by raising the liquid level between the guide plate and the foam collecting plate by the air lift action of the air ejected from the air ejecting means. Wastewater treatment equipment. 3. A foam collecting guide path having a V-shaped cross section is formed at lower ends of the screen and the guide plate, and the air ejecting means is arranged below the foam collecting guide path. 2. The waste water treatment apparatus according to claim 1, wherein the air from the inside is guided into the flow path by the bubble collection guide path, and an upward flow is generated in the flow path by an air lift action. 4. The flow velocity of the water flow for cleaning the screen is 5 times or more the flow velocity of the treated water discharged from the treatment tank passing through the screen. 2 or 3 wastewater treatment equipment. 5. The waste water treatment apparatus according to claim 1, wherein the air jetting means also serves as an air aeration apparatus for supplying air to the microorganisms carried on the carrier.