JP3166584B2 - Wastewater treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus, and more particularly to a wastewater treatment apparatus provided with a screen at a discharge port of a treatment tank for preventing a carrier having microorganisms immobilized thereon from flowing out.

[0002]

2. Description of the Related Art In the case of a biological wastewater treatment apparatus, for example, a nitrification apparatus, nitrifying bacteria are difficult to proliferate. Therefore, a carrier having nitrifying bacteria immobilized is introduced into a treatment tank into which wastewater flows, and air aeration means is used. The wastewater is biologically treated by bringing the sewage and the carrier into contact with each other under aerobic conditions with air that is 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 does not flow off, but solids in the wastewater and fibers such as hair adhere to the screen due to long-term use. Clogging occurs.

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

[0004]

However, in the conventional structure in which an air jetting device is provided below the screen and bubbles are made to collide with the screen to clean the screen, the inside of the nitrification tank is aerobic. Due to the water flow generated in the nitrification tank by the aeration air from the air aeration means, the direction of the rising air bubbles from the air ejection device changes, and the air bubbles often do not collide with the screen effectively. There was a drawback that it had to be manually cleaned on a regular basis. In addition, in order to reduce the frequency of cleaning by the operator, the amount of air to be blown out from the air blowout device must be extremely large, and there is a disadvantage that running costs are increased.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wastewater treatment apparatus capable of reducing the number of times the operator has to clean the screen and reducing operating costs. .

[0006]

Means for Solving the Problems In order to achieve the above object, the present invention provides a biological treatment of the wastewater by contacting a wastewater with a carrier on which microorganisms are immobilized in a treatment tank. In a wastewater treatment apparatus in which a screen is provided at a discharge port of a tank to prevent the carrier from flowing out of the treatment tank, the screen is provided inside the treatment tank so as to be 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 driven by an air lift action by air from an air ejection unit.

According to the present invention, a guide plate is provided in parallel with the surface of the screen to form a flow path between the screen and the guide plate. A stream of water was generated. In this way, by generating a water flow parallel to the surface of the screen, it becomes difficult for solids in the wastewater and fibers such as hair to adhere to the screen. In addition, since the attached matter attached to the screen is scraped off by the water flow, the screen is washed. Thereby, clogging of the screen can be prevented. In addition, since the water flow is generated using the air lift function as power, unlike the case of a pump or the like, the carrier is not damaged. Also, if the air source that generates the air lift function is also used as an air aeration device that supplies air to the microorganisms carried on the carrier, no special air jetting means for generating a water flow is required, which increases running costs. do not do.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wastewater treatment apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view illustrating a wastewater treatment apparatus according to a first embodiment of the present invention, and is an example in which the wastewater treatment apparatus is applied as a nitrification apparatus. In the nitrification apparatus, a carrier carrying nitrifying bacteria in addition to activated sludge is charged. Is done. FIG. 2 is a sectional view of a main part of FIG. The description of the activated sludge on the drawing is omitted.

As shown in FIG. 1, a nitrification apparatus 10 mainly includes a nitrification tank 12 into which wastewater containing, for example, sewage containing organic substances and ammonia nitrogen components flows, and a nitrification tank 12.
An air aerator 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 treated water treated in the nitrification tank 12. The screen 20 is provided with a water flow generating mechanism for generating a water flow along the surface of the screen 20.

The air aerator 16 is provided with a plurality of diffuser plates 22, 22... Disposed so as to cover substantially the entire area near the bottom of the nitrification tank 12. And a blower 26 for supplying air. The screen 20 is provided to be inclined on the bottom side of the nitrification tank 12, and has a rectangular frame 28 with a spacing such that a large number of wedge wires 30, 30,... Do not pass through the carrier 14, as shown in FIG. Are arranged vertically. Screen 2
A rectangular upper plate 32 is provided on the upper end of the screen 0 along the width direction of the screen 20 so that the treated water treated in the nitrification tank 12 is not 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.
A trough 36 that guides the treated water that has passed through the screen 20 to the outside of the nitrification apparatus 10 is formed by the side wall of the nitrification tank 12 and the support plate 34. As a result, part of the treated water and activated sludge treated in the nitrification tank 12 pass through the screen 20 and pass through the trough 3.
6 and the carrier 14 introduced into the nitrification tank 12
The screen prevents the nitrification tank 12 from flowing out.

Next, a water flow generating mechanism for generating a water flow along a number of wedge wires 30 of the screen will be described. Inside the screen 20 in the nitrification tank 12, a guide plate 38 is provided in parallel with 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 shape of a trumpet and formed near the liquid surface 46. The lower end 48 of the guide plate 38 is bent obliquely downward, and
A 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 with the guide plate 38 and the diffusion plate 22.
This serves to make it difficult for air aerated from the air to enter the flow channel 40 from the lower opening 52 of the flow channel 40.

A bubble collecting plate 54, which forms a C-shaped cross section with the guide plate, is provided inside the screen 20 in the nitrification tank 12.
Is provided. Thereby, the diffuser plate 22 is moved from the nitrification tank 12
Bubbles due to the air aerated inside can be easily collected between the guide plate 38 and the foam collection 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 waste water such as sewage flows into the nitrification tank 12 through an inflow pipe 18. In the nitrification tank 12, the activated sludge, the carrier 14 supporting the nitrifying bacteria, and the wastewater are brought into aerobic contact with the aeration air from the diffuser plate 22. Thereby, the nitrification treatment of the wastewater is performed. The treated water 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 the nitrification treatment, solids in the wastewater and fibers such as hair adhere to the screen 20, and the screen causes clogging by the adhered matter. However, in the present invention, air bubbles aerated into the processing tank 12 from the diffuser plate 22 are collected between the guide plate 38 and the foam collection plate 54, and the air lift action by the air causes the guide plate 38 to move.
The liquid level 46 between the liquid and the foam collection plate 54 rises from the other liquid level 46 in the nitrification tank 12. The raised liquid level 46 flows into the flow channel 40 from the upper opening 44 of the flow channel 40, and descends in the flow channel 40 to form a water flow 55 flowing from the lower opening 52. As described above, by generating a water flow parallel to the surface of the screen 20, it is difficult for the solids in the wastewater and the fibers such as hair to adhere to the screen 20. Also, the screen 20
The screen 20 is washed because the adhered matter is scraped off by the water flow. Thereby, the screen 20
Clogging can be prevented. Therefore, since the frequency of cleaning the screen 20 by the operator can be significantly reduced, the labor of the operator can be reduced and the operation cost can be reduced.

In preventing the clogging of the screen 20, the flow velocity of the water flow 55 for cleaning the screen 20 is smaller than the flow velocity of the treated water in the nitrification tank 12 passing through the screen 20 and flowing out to the trough 36. If the setting is made five times or more, clogging of the screen 20 can be more effectively prevented. In order to obtain the water flow 55 that meets the set conditions, the guide plate 3 is moved by the air lift action.
8 between the foaming plate 54 and the other liquid level 5 cm
It is preferable to make the height higher.

Further, according to the present invention, since the water flow 55 is generated by the air lift function, the carrier 14 in the nitrification tank 12 is not destroyed unlike the case where the water flow is generated by a pump. Further, since the air diffuser plate 22 for supplying air to the microorganisms carried on the carrier 14 can also be used as an air source for generating an air lift action, the running cost does not increase. Accordingly, the amount of air used can be significantly reduced as compared with the conventional wastewater treatment apparatus that cleans the screen 20 by causing air bubbles to collide with the screen 20, thereby reducing the air cost.

Next, a second embodiment of the wastewater treatment apparatus of the present invention will be described with reference to FIGS. The same members and devices as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the second embodiment, the liquid level 46 is effectively raised by the air lift function. That is, similarly to the first embodiment, a 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 disposed near the upper end of the screen 8 along the longitudinal direction of the screen 20, and a side plate 56 </ b> A of the distribution gutter 56 on the screen 20 side is connected to an upper end of the guide plate 38 and on the opposite side to the screen 20. The side plate 56B is formed so as to be higher in height than the side plate 56A. A plurality of air lift pipes 58 communicate with the distribution gutter 56, and the air lift pipes 58 are provided vertically from the bottom of the distribution gutter 56 to near the bottom of the nitrification tank 12. Also, air lift piping 5
8, an air supply portion 58A having a slightly larger diameter is formed, and the air supply portion 58A is provided with the blower 2.
The air pipe 24 connected to 6 is communicated. This allows
The air lift function 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. A weir 60 that can move up and down along the longitudinal direction is provided in the distribution gutter 56. This weir 6
0, the liquid level in the distribution trough 56 exceeds the weir 60 and the flow path 4
Since the water flows down uniformly to zero, the water flow 55 can be generated evenly over the entire area in the longitudinal direction of the screen 20. Also, by adjusting the height of the weir 60, the flow path 40
, That is, the flow velocity in the flow path 40 can be adjusted.

Therefore, according to the second embodiment, the cleaning of the screen 20 by the water flow
The dispersion of the partial cleaning of the
The whole can be washed evenly. Further, the amount of air for generating the water flow 55 can be small. Next, a wastewater treatment apparatus according to a third embodiment 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 denoted by the same reference numerals, and description thereof is omitted.

In the first and second embodiments, a downward flow is generated in the flow channel 40 by raising the liquid level 46. In the third embodiment, however, the downward flow is generated in the flow channel 40 by an air lift action. This is a case where the screen 20 is washed by generating an upward flow. As shown in FIG. 5, a pair of plate members 6 are provided at lower ends of a vertically provided screen 20 and a vertically provided guide plate 62 like the screen 20.
A bubble collection guide path 64 is formed in which the air bubbles 3 and 63 face each other in a C-shape.
The flow is guided into the flow path 40 at 4 to generate an upward flow in the flow path 40. This pair of plate members 63, 63
One of the plate members 63 also forms the bottom surface of the trough 36. Also, the distance L between the screen 20 and the guide plate 62
Performs cleaning of the screen 20 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 in consideration of the relationship with the amount of air from the diffusion plate 22. The flow rate of the water stream 66 is set to be 5 times or more.

According to the third embodiment, similarly to the first and second embodiments, the generation of the water flow 66 in the flow path 40 and the cleaning of the screen 20 by this are 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 an upward flow, in addition to the cleaning of the screen 20 by the water flow 66, the screen 20 by air bubbles. Is performed at the same time. That is, air bubbles ejected from the diffuser plate 22 rise while contacting the screen 20, so that the screen 20 can be washed with both the water flow 66 and the air bubbles.

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

[0022]

As described above, according to the wastewater treatment apparatus of the present invention, since a water flow parallel to the screen surface is generated, for example, solids and fibers in the wastewater adhere to the screen. In addition, it is difficult to perform the cleaning, and the attached matter attached to the screen is scraped off by the water flow, so that the screen is washed. Therefore, clogging of the screen can be effectively prevented. In addition, since the water flow is generated by the air lift function, the carrier in the processing tank is not broken.

Therefore, as compared with a conventional wastewater treatment apparatus that cleans a screen by colliding bubbles with the screen, the number of times the operator has to clean the screen can be reduced, and the operating cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view for explaining a first embodiment of a wastewater treatment apparatus according to the present invention.

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

FIG. 3 is a longitudinal sectional view illustrating a second embodiment of the wastewater treatment apparatus of the present invention.

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

FIG. 5 is a longitudinal sectional view illustrating a wastewater treatment apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Nitrification apparatus 12 ... Nitrification tank 14 ... Carrier which carries nitrification bacteria 16 ... Air aeration apparatus 20 ... Screen 22 ... Diffusion plate 26 ... Blower 36 ... Trough 38 ... Guide plate 40 ... Flow path 55, 66 ... Water flow 56 ... Distribution gutter

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-38299 (JP, A) JP-A 63-115493 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 3/08 B01D 35/02

Claims (5)

(57) [Claims] 1. A wastewater treatment method comprising the steps of: contacting a carrier on which microorganisms are immobilized with wastewater in a treatment tank to biologically treat the wastewater;
In a wastewater treatment apparatus in which a screen is provided at an outlet of the treatment tank to prevent the carrier from flowing out of the treatment tank, the screen is substantially parallel to the screen surface inside the screen in the treatment tank. Wastewater characterized by providing a guide plate so as to form a flow passage between the screen and the guide plate, and generating a water flow in the flow passage powered by an air lift action by air from an air jetting means. Processing equipment. 2. A foam collecting plate which forms a cross section with the guide plate inside the screen in the processing tank is provided, and the air jetting means is arranged below the guide plate and the foam collecting plate. and, according to claim 1, characterized in that to generate a downward flow in the flow channel by increasing the liquid level of the current foam plates and the guide plate by air lift action of air ejected from the air ejection means Wastewater treatment equipment. 3. A foam collecting guide path having a C-shaped cross section is formed at a lower end of said screen and said guide plate, and said air jetting means is arranged below said foam collecting guide path. The wastewater treatment apparatus according to claim 1, wherein air from the air 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 method according to claim 1, wherein the flow rate of the water flow for cleaning the screen is at least five times the flow velocity of the processing water discharged from the processing tank through the screen. 2 or 3 wastewater treatment devices. 5. The wastewater treatment apparatus according to claim 1, wherein said air jetting means is also used as an air aeration apparatus for supplying air to microorganisms carried on said carrier.