JPS6327832Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This idea is especially useful in batch-type activated sludge treatment equipment, which processes wastewater by repeating a cycle of aeration, sedimentation, and discharge in a single treatment tank. The present invention relates to a decanter equipped with a scum removing device.

[Conventional technology]

Generally, in batch-type activated sludge treatment equipment in a single treatment tank, the supernatant liquid is discharged after the sedimentation process, and if there is scum floating in the treatment tank at the time of discharge, the scum is also removed. Needs to be removed. Therefore, even in the batch type activated sludge treatment apparatus, it is necessary to provide a supernatant liquid discharge device and some kind of scum removal means, as in the case of a general sludge treatment apparatus. In general sludge treatment equipment, the water level in the tank is approximately constant or only slightly fluctuates, so scum removal methods include a fixed skimmer combined with a buttful, or a floating skimmer on the liquid surface with a small water area. Floating skimmers and the like are being used with some success.

[Problem that the invention attempts to solve]

However, in the case of batch-type activated sludge treatment equipment, the water level in the tank fluctuates by as much as 2m to 3m, so simply reusing a skimmer that is generally intended for activated sludge treatment equipment, where water level fluctuations are extremely small, is not effective. There was a problem in that the scum collection could not be expected at all. For this reason, in batch-type activated sludge treatment equipment, various improvements have been made to the supernatant liquid discharge device, but the scum removal means is a very complicated mechanism similar to the supernatant liquid discharge device.
There are many problems in terms of space and cost, and further automation would be extremely expensive, so there are problems that are not considered much at present. This idea was devised to solve the problems mentioned above, and although it has a mechanically simple configuration, it can remove scum that has formed on the liquid level in the tank even when the water level in the tank fluctuates greatly. It is an object of the present invention to provide a decanter with a scum removing device that can reliably collect and discharge scum, automate the collection and discharge, and cause no cost problems.

[Means to solve the problem]

The decanter with a scum removal device according to this invention is
A shaft pipe extending laterally is rotatably supported on the inner bottom side of a treatment tank that receives inflow sewage and performs activated sludge treatment, and a supernatant liquid discharge pipe and a scum discharge pipe are connected to this shaft pipe. The supernatant liquid discharge pipe and the scum discharge pipe are connected at right angles at predetermined intervals, and each free end of the supernatant liquid discharge pipe and the scum discharge pipe is connected to an overflow pipe that floats on the liquid level in the processing tank. The supernatant liquid inflow path is connected to the shaft pipe by the supernatant liquid discharge pipe, and the scum inflow path is connected to the scum discharge system outside the system through the shaft pipe by the scum discharge pipe. The supernatant liquid inlet is provided with a supernatant liquid inlet formed with a supernatant overflow weir that is submerged below the liquid surface while the liquid surface of the overflow pipe is floating, and the above-mentioned scum inflow A predetermined lowering position of the overflow pipe, for example L.
It is equipped with a scum inlet that forms a scum overflow weir that is submerged below the liquid level near the water level, which is slightly higher than the WL.

[Effect]

The decanter with a scum removal device of this invention rotates the shaft pipe to drain the overflow pipe at the high water level (HWL) in the treatment tank when discharging the supernatant liquid after the aeration and precipitation processes in the treatment tank. When suspended, the supernatant overflow weir of the overflow pipe is submerged in water, and the supernatant fluid flows into the supernatant fluid inlet channel from the supernatant fluid inlet having the supernatant overflow weir. Then, the incoming supernatant liquid flows down the supernatant liquid discharge pipe, passes through the shaft pipe, and is discharged to the outside of the system. At this time, the scum overflow weir of the overflow pipe is held above the liquid level, so that the supernatant liquid does not flow into the scum inflow path from the scum inflow port. Due to the discharge of such supernatant liquid, the water level in the treatment tank gradually decreases, and the overflow pipe also descends following the liquid level, so that the scum overflow weir of the overflow pipe gradually lowers the liquid level. , and the water level in the treatment tank is low (L.
Near WL), the scum overflow weir becomes approximately at the same height as the above-mentioned skimming overflow weir, and both are submerged below the liquid level. For this reason, the low water level (LW) in the treatment tank is
Scum flows into the scum inflow path from the scum inlet at the liquid level near L), and the inflowing scum flows down the scum discharge pipe and is discharged out of the system through the scum discharge path in the shaft pipe. At the same time, supernatant liquid flows in from the supernatant liquid inlet, and the supernatant liquid is discharged out of the system through the above-mentioned supernatant liquid discharge path.

【Example】

An embodiment of this invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, the decanter 1 according to this invention is installed in a single treatment tank 10 that performs activated sludge treatment by repeating a cycle of an aeration process, a settling process, and a discharge process. . That is, the decanter 1 has a shaft pipe 2 that is rotatably supported on the bottom side of the processing tank 10 in the axial direction and extends laterally (substantially horizontally in the illustrated example). This shaft pipe 2 forms a supernatant liquid discharge passage, has a supernatant liquid discharge port 2a at one end, and has a rotating means 7.
It can be rotated around the axis. A plurality of arm-shaped discharge pipes 3 extending perpendicularly to the shaft pipe 2 are integrally connected to the shaft pipe 2 at predetermined intervals. More specifically, the discharge pipe 3 is composed of a supernatant liquid discharge pipe 3a and a scum discharge pipe 3b, and the scum discharge pipe 3b has a horizontal pipe portion 2b inserted into the shaft pipe 2. This horizontal pipe portion 2b extends within the shaft pipe 2 to the opposite side of the supernatant liquid discharge port 2a, and forms a scum discharge path within the shaft pipe 2. The other end of the shaft pipe 2 is closed with the horizontal pipe section 2b. Therefore, the shaft pipe 2 in the illustrated example has a double pipe structure in the portion through which the horizontal pipe portion 2b is inserted. As described above, the supernatant liquid discharge pipe 3a and the scum discharge pipe 3b are integrally connected to the shaft pipe 2 at a substantially right angle, so that they can swing vertically around the shaft pipe 2. There is. An overflow pipe 4 is horizontally connected to each free end of the supernatant liquid discharge pipe 3a and the scum discharge pipe 3b. In this overflow pipe 4, as shown in FIGS. 1 to 6, a supernatant fluid inflow path 5 and a scum inflow path 6 are separated from each other by a partition portion 4a. Here, the supernatant fluid inflow path 5 is communicated with the shaft pipe 2 through the supernatant fluid discharge pipe 3a, and the scum inflow path 6 is communicated with the scum discharge pipe 3b. The overflow pipe 4 also has a supernatant overflow weir 5a on the side closer to the shaft pipe 2, and a supernatant liquid inlet 5b communicating with the supernatant liquid inflow path 5, and A scum inlet 6b that has a scum overflow weir 6a on the far side and communicates with the scum inflow path 6 is provided. These supernatant liquid inlet 5b and scum inlet 6b
is formed by cutting out a predetermined portion of the overflow pipe 4. In this case, the supernatant overflow weir 5a is formed so that the supernatant overflow weir 5a is submerged near the liquid level no matter what the water level is in the processing tank 10. In addition, in the positional relationship with the supernatant overflow weir 5a, the scum overflow weir 6a gradually approaches the liquid level due to the lowering of the overflow pipe 4 as the water level in the treatment tank 10 decreases, and the overflow It is formed to be submerged at a predetermined lowering position of the pipe 4, for example near the water level slightly higher than LWL, at the same height as the above-mentioned supernatant overflow weir 5a. At both ends of such an overflow pipe 4, an overflow pipe 4 is provided.
Both ends of a float 8, which also serves as a scum baffle and is parallel to the outside of the supernatant overflow weir 5a, are connected by support arms 9 so as to be able to swing up and down, and the float 8 allows the scum floating on the liquid surface to be moved upwardly and downwardly. This prevents water from flowing into the supernatant overflow weir 5a. Next, the operation will be explained. In the treatment tank 10, activated sludge treatment of the inflowing sewage is performed, with the aeration process, the settling process, and the discharge process of discharging the supernatant liquid using the decanter 1 as one cycle. Incidentally, the settled sludge in the treatment tank 10 is drawn out at an appropriate time. In such an activated sludge treatment apparatus, in the discharge step, the shaft pipe 2 is rotated by the rotating means 7 to move the decanter 1 from the upper limit position shown by the dashed line in FIG. 2 to the use position shown by the solid line in the same figure. By lowering the water level, the high water level (H.
A float 8 floats on the liquid surface of WL), and the overflow pipe 4 is connected to the supernatant overflow weir 5a as shown in FIGS. 1 and 5.
is submerged near the liquid level, and the scum overflow weir 6a
is held in a position protruding above the liquid level. Therefore, in this state, the supernatant liquid between the overflow pipe 4 and the float 8 in the processing tank 10 overflows the supernatant overflow weir 5a and flows from the supernatant liquid inlet 5b to the supernatant liquid inflow path. 5. In this case, since the scum overflow weir 6a is held above the liquid level as described above, the supernatant liquid will not flow into the scum inflow path 6 from the scum inflow port 6b. Then, the supernatant liquid that has flowed into the supernatant liquid inflow path 5 flows down the supernatant liquid discharge pipe 3a of that system, reaches the inside of the shaft pipe 2, and passes through the shaft pipe 2 to the supernatant liquid discharge port 2a. is discharged from the system. Due to such discharge of the supernatant liquid, the water level in the processing tank 10 gradually decreases, and the decanter 1 descends along with the liquid level by an arcuate movement around the shaft pipe 2. In this descending process, the scum overflow weir 6a
is displaced in a direction that gradually approaches the liquid level, and the treatment tank 1
When the liquid level in 0 becomes near the low water level (LWL), the overflow pipe 4 is displaced to the state shown by the two-dot chain line in FIG. 2 and in FIG. 6, and in this state, the scum overflow weir 6
a is at approximately the same height as the supernatant overflow weir 5a, and both are submerged below the liquid level. Then, the liquid level in the treatment tank 10 is at a low water level (LW
L), the scum floating on the liquid surface overflows the scum overflow weir 6a and the scum inlet 6a.
scum flows into the scum inflow path 6 from the scum inflow path 6, then flows down the scum discharge pipe 3b of the system, passes through the horizontal pipe portion 2b (scum discharge path) in the shaft pipe 2, and is discharged to the outside of the system. At the same time, the low water level (LW) in the treatment tank 10
The supernatant liquid near L) also overflows the supernatant overflow weir 5a, flows into the supernatant liquid inflow path 5, flows through the shaft pipe 2 as described above, and is discharged to the outside of the system. Therefore, near the low water level (LWL) of the treatment tank 10, both the supernatant liquid and the scum are simultaneously discharged through their respective dedicated discharge paths. The decanter 1 is connected to the L.
When it reaches WL, it returns to the upper limit position shown by the dashed line in FIG. 2. In order to effectively remove scum,
Discharge of the supernatant liquid is stopped at LWL, scum is discharged to LLWL a little lower, and decanter 1 is stopped at L.
It is preferable to operate at LWL to return to the upper limit position, and it is also possible to do this, and also to drain the supernatant liquid at LWL as necessary.
It is also possible to stop at a point slightly above . In the above embodiment, the decanter 1 may be lowered to a position lower than LWL so that the scum can be sufficiently discharged. Further, a valve is provided in the scum discharge system in the decanter 1,
Scum discharge may be arbitrarily controlled by opening and closing this valve. Furthermore, either one or both of the above-mentioned skimming overflow weir 5a and scum overflow weir 6a is provided with a height adjustment mechanism, or the L.
The amount of scum discharged may be adjusted by making the area around WL adjustable. In this case, it is recommended that the adjustment be made electrically or manually so that scum is not discharged from the LWL during normal times, and scum can be discharged only when necessary. Other embodiments are shown in FIGS. 7-9. The difference between this embodiment and the previous embodiment is that the inside of the overflow pipe 4 is partitioned by a radial partition portion 4a, which allows a plurality of supernatant liquids to flow in each of the overflow pipes 4 in the axial direction. The difference is that the passage 5 and the scum inflow passage 6 are formed to be separated from each other, and other aspects are the same as in the previous embodiment. Therefore, even in this embodiment, the same operational results as in the previous embodiment can be obtained.

[Effect of the idea]

As described above, according to this invention, the supernatant liquid and the scum are individually separated by a single overflow pipe that floats on the liquid level in the treatment tank and moves up and down following fluctuations in the liquid level. Since it can be collected and discharged separately, even if the water level in the treatment tank fluctuates greatly, the supernatant liquid and scum can be reliably separated and automatically and efficiently collected and discharged regardless of the fluctuations. Furthermore, since the structure is extremely simple, there are no space or cost problems, and there is an effect that a decanter with a scum removal device suitable for batch type activated sludge treatment equipment can be provided.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a decanter with a scum removing device according to an embodiment of the invention, Fig. 2 is a schematic side view that also serves as an explanation of its operation, Fig. 3 is an enlarged sectional view of the main parts, and Fig. 4 The figure is an enlarged plan view of the overflow pipe, FIG. 5 is a sectional view taken along the line - - in FIG.
Fig. 7 is a plan view of an overflow pipe according to another embodiment, Fig. 8 is a sectional view taken along the - line in Fig. 7, and Fig. 9 is a sectional view taken along the - line in Fig. 7. be. In the figure, 2 is a shaft pipe, 3a is a supernatant liquid discharge pipe, 3b is a scum discharge pipe, 4 is an overflow pipe,
5 is a supernatant liquid inlet, 5a is a supernatant overflow weir, 5b is a supernatant liquid inlet, 6 is a scum inflow path, 6a is a scum overflow weir, and 6b is a scum inlet.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A shaft pipe extending laterally at the inner bottom side of a treatment tank that receives inflow sewage and performs activated sludge treatment is rotatably supported in the direction of the axis, and The supernatant liquid discharge pipe and the scum discharge pipe are connected in a perpendicular direction at predetermined intervals, and the liquid in the processing tank is connected by spanning the free ends of the supernatant liquid discharge pipe and the scum discharge pipe. An overflow pipe is provided to float the scum on the surface, and inside the overflow pipe there is a supernatant fluid inflow channel that communicates with the shaft pipe through the supernatant fluid discharge pipe, and a supernatant fluid inflow channel that communicates with the shaft pipe through the scum discharge pipe. The scum inflow path connected to the scum discharge path of the overflow pipe is separated from the scum inflow path, and the supernatant liquid inflow path is separated from the scum inflow path connected to the scum discharge path of the overflow pipe. The scum inflow path has a clear liquid inlet, and as the overflow pipe descends as the water level in the processing tank decreases, the scum inflow path gradually approaches the liquid level and is submerged below the liquid level at a predetermined lowering position of the overflow pipe. A decanter with a scum removal device, characterized in that it has a scum inlet in which a scum overflow weir is formed. (2) The scum according to claim 1 of the utility model registration claim, characterized in that the overflow pipe is connected to a float that also serves as a scum buttful and is located outside of the supernatant inlet side of the overflow pipe. Decanter with removal device.