JPH0359759B2 - - Google Patents

Description

Detailed Description of the Invention "Industrial Application Field" This invention is a wastewater treatment method that repeats a cycle consisting of at least an aeration process, a sludge standing separation process, and a supernatant liquid withdrawal process in a single biological treatment tank. The present invention relates to a batch-type biological treatment apparatus that performs this process, and particularly to means for adjusting the drawing flow rate of a float-type supernatant liquid drawing pipe for discharging a supernatant liquid.

"Prior Art" Conventionally, in a batch-type biological treatment apparatus having a float-type supernatant liquid withdrawal tube, the start and end of supernatant liquid withdrawal are determined by the descent of the supernatant liquid withdrawal tube 1, as shown in FIG. and by rising or the first
As shown in FIG. 4, this is done by opening and closing a valve 8 provided at the discharge end of the supernatant liquid drawing pipe 2 based on a detection signal from the liquid level detector 4. The drawing of the supernatant liquid was left to natural flow due to the level difference between the liquid level in the biological treatment tank 5 and the discharge openings of the supernatant liquid drawing pipes 1 and 2. Therefore, in the gap at the end of the supernatant liquid drawing process where the outlet ports 1a, 2a of the supernatant liquid drawing pipes 1, 2 and the sludge interface S approach, the above-mentioned level difference becomes small and the supernatant liquid drawing flow rate (flow rate) increases. This had the advantage of being smaller and avoiding sludge entrainment. Furthermore, by forming the floats 1b and 2b of the supernatant liquid withdrawal tubes 1 and 2 in an annular shape, scum floating on the supernatant liquid is prevented from flowing into the extraction ports 1a and 2a of the supernatant liquid withdrawal tubes 1 and 2. It also had the advantage of being able to do so.

"Problems to be Solved by the Invention" However, in the conventional batch-type biological treatment equipment described above, there is a limit to the prevention of sludge entrainment, and sludge with a high SVI (sludge capacity index), which has poor settling properties, gets entrained and rises. There was a problem that the quality of the clear liquid deteriorated. Therefore, in order to solve this problem, the opening ends of the supernatant liquid drawing pipes 1 and 2 are brought closer to the lower limit level for supernatant liquid drawing and the final drawing flow rate is reduced, and the initial and middle drawing flow rates are accordingly reduced. Therefore, the problem arises that the overall drawing time becomes longer. In addition, batch-type biological treatment equipment has the problem that a large amount of supernatant liquid is discharged at one time, resulting in a large-sized treatment equipment for the next process.

This invention has been made in view of the above circumstances, and is designed to minimize the influence on the overall drawing process time, and to prevent sludge from being drawn into the gap at the end of the supernatant liquid drawing process, where the supernatant liquid drawing port and the sludge interface approach each other. It is an object of the present invention to provide a batch-type biological treatment device that can perform drawing at a very low flow rate (flow rate) to prevent this problem, and also allows the device for the next step to be made smaller.

"Means for Solving the Problems" In order to achieve the above object, the present invention is provided in a biological treatment tank, and has a float and a supernatant extraction port at the tip, so that at least the tip A supernatant liquid withdrawal pipe that follows fluctuations in water level, a treatment water tank having a capacity greater than the amount of supernatant liquid discharged in one cycle of the biological treatment tank, and one end connected to the base end of the supernatant liquid withdrawal pipe. a communicating pipe whose other end opens at a position below the lower limit level for supernatant liquid withdrawal in the biological treatment tank of the treatment water tank, and which introduces the supernatant liquid drawn by the supernatant liquid withdrawal pipe into the treatment water tank; Then, it is directly or indirectly detected that a predetermined amount of supernatant liquid has been drawn into the treated water tank, and the supernatant liquid received in the treated water tank is transferred to a predetermined amount of supernatant liquid in the next cycle of the biological treatment tank. A discharge means is provided for discharging the liquid within a range where the liquid level in the treated water tank remains at a height equal to or higher than the opening position of the communication pipe when the liquid is received in the treated water tank.

"Operation" In the batch-type biological treatment apparatus of the present invention, the supernatant liquid in the biological treatment tank is led to the treatment water tank through the supernatant liquid drawing pipe, and the liquid level in the biological treatment tank is at the lower limit level for supernatant liquid drawing. After reaching this point, the discharge means is activated and the supernatant liquid introduced into the treated water tank is discharged.

``Example'' Hereinafter, an example of the present invention will be described in Figures 1 to 11.
This will be explained with reference to the figures.

10 in the figure is a biological treatment tank, and this biological treatment tank 10
The cycle shown in Fig. 9 consisting of receiving raw wastewater and aeration process, standing separation process of sludge, and supernatant liquid drawing process is repeated. and,
Inside this biological treatment tank 10, there is a float 1 at the tip.
1 and a supernatant liquid extraction port 12, and the proximal end is a communicating tube 1.
A supernatant liquid withdrawal pipe 14 is connected to the biological treatment tank 10 and communicated with the outside of the biological treatment tank 10. A tilting device 15 for tilting is installed.

The supernatant liquid drawing pipe 14 is a straight pipe 1 of a predetermined length.
A liquid collection pipe 14c having the outlet port 12 is connected to the tip of the straight pipe 14a via a 45-degree bent pipe 14b, and a 90-degree bent pipe 14d is connected to the base end of the straight pipe 14a.
are connected in series, and the bent tube 14d at the base end
is connected to the bent pipe of the communication pipe 13 fixed to the tank wall 10a via a rotary joint 14e so as to be freely rotatable up and down. A pair of left and right connecting plates 14f, 14f are fixedly attached to the liquid collecting pipe 14c, and above the liquid collecting pipe 14c, four pipes 11a, . . . are formed by combining them into a rectangular ring shape. The float 11 is attached to a pair of left and right mounting plates 11b, 11 across the left and right pipes 11a facing each other so that the outlet 12 of the liquid collecting pipe 14c is located below the center of the float 11.
b is connected to the connecting plates 14f, 14f by a connecting shaft 14g, and is provided so as to be freely rotatable up and down with respect to the connecting plates 14f, 14f.

The lifting device 15 also includes a support pedestal 16 that is formed of an angle material and is fixedly installed on the upper part of the tank wall 10a of the biological treatment tank 10, and a rod 17a that is placed downwardly at the center of the upper part of the support pedestal 16. Air cylinder 17 fixedly mounted facing toward
A pair of front and rear diamond-shaped mounting plates 19, 19 are fixed to the tip of the rod 17a of the air cylinder 17 via a connecting member 18, and are attached to the left and right of a pair of rhombic mounting plates 19, 19 with their axes facing front and back, and rotate within the same vertical plane. A pair of left and right movable pulleys 20a and 20b are attached to the support pedestal 16 with their axes facing forward and backward so that they are located slightly below the extended end of the rod 17a of the air cylinder 17.
a, 20b, and a fixed pulley 21 rotatable in the same vertical plane as the left movable pulley 20a, the fixed pulley 21, and the right movable pulley 20b. Pulled pipe 14
The connecting shaft 14g is connected to the connecting shaft 14g via a thimble 22a, and the other end is inserted into a guide tube 23 provided vertically on the lower surface of the support frame 16.
The wire rope 22 is connected to several weights 24. And the air cylinder 17
Two air pipes 26a, 26b each equipped with a spude controller 25a, 25b are connected to the cylinder body 17b, and these two air pipes 26a, 26b are connected to compressed air by an air supply pipe 27. As shown in FIG.
b, thereby contracting the rod 17a and raising the movable pulleys 20a and 20b to separate them from the fixed pulley 21. At the same time, as shown in FIG. 26a to the cylinder body 17b, the rod 17a is extended, and the movable pulley 20
a, 20b can be lowered to approach the fixed pulley 21. Further, at the joint portion of the guide tube 23 to the support frame 16,
A stopper 30 is provided, which is made of a pipe with a smaller diameter than the weight 24 or a member having a U-shaped cross section when viewed from above.
It is designed so that it does not slip upward from 3. Furthermore, guide rails 31, 31 formed by arranging a pair of left and right angle members facing each other are attached to the front and rear sides of the interior of the support frame 16, and are connected to the mounting plates 19, 19. At the upper and lower portions of the member 18, there are guide wheels 3 that are provided with wheels 32b, 32b at both ends of axles 32a, 32a, respectively.
2 and 32 are mounted with their axes facing forward and backward, and these guide wheels 32 and 32 are connected to the guide rails 31 and 3.
It is designed to move up and down along 1.

On the other hand, next to the biological treatment tank 10, there is installed a treated water tank 33 (supernatant liquid tank) in which the outer end of the communication pipe 13 is exposed.
A pump 35 with a discharge pipe 34 connected to the discharge side is installed at the inner bottom of the tank 33, and a pump 35 is installed in the treated water tank 33 to ensure that the liquid level in the treated water tank 33 is at a predetermined lower limit level.
A first level switch 36 is provided which detects when the level reaches L ₂ WL and stops the pump 35 based on the detection signal. In addition, the biological treatment tank 10 detects when the liquid level of the supernatant liquid reaches the lower limit level LWL for drawing the supernatant liquid,
Based on the detection signal, the electromagnetic switching valve 29 is switched to the position shown in FIG.
2nd level switch (liquid level detector) 3
7 is provided. The pump 35, first level switch 36, and second level switch 37 in this embodiment constitute a discharge means according to the present invention.

Here, the treated water tank 33 has a capacity greater than the amount of supernatant liquid treated in one cycle of the biological treatment tank 10. Further, the installation height of the opening of the communication pipe 13 provided in the treated water tank 33 is below the lower limit level LWL for drawing out the supernatant liquid of the biological treatment tank 10. Furthermore, the height of the liquid level detection position of the first level switch 36 (the lower limit level L ₂ WL) is the same as that of the biological treatment tank 1.
Liquid level in the treated water tank 33 (upper limit level H ₂ WL) when the drawing of the supernatant liquid, which is caused to flow down to the treated water tank 33 through the supernatant liquid drawing pipe 14, is completed.
is the lower limit level for drawing out the supernatant liquid of the biological treatment tank 10.
Between the same level as LWL and the lower end of the opening of the communication pipe 13, preferably the lower limit level for supernatant liquid withdrawal.
The same level as LWL, and its upper limit level H ₂ WL
The capacity between the lower limit level L ₂ WL is biological treatment tank 1
The height is approximately the same as the amount of supernatant liquid discharged in one cycle of 0. That is, biological treatment tank 1
The treated water tank 33 when a predetermined amount of supernatant liquid is received in the treated water tank 33 in the next cycle of 0
The lower limit level L ₂ WL, which is the liquid level when the supernatant liquid discharge from the treated water tank 33 is completed, is set so that the upper limit level H ₂ WL, which is the liquid level at and this lower limit level
The first level switch 36 is configured to detect the liquid level that has reached L ₂ WL. In this case, it is acceptable even if both the upper limit level H ₂ WL and the lower limit level L ₂ WL are higher than the position of the communication pipe 13.

In addition, HWL in the figure is the upper limit level for drawing out the supernatant liquid of the biological treatment tank 10, and corresponds to the water level of the biological treatment tank 10 in the sludge static separation process.

Next, the operation of the biological treatment apparatus having the above-mentioned configuration will be explained. Before explaining the operation of the entire biological treatment apparatus, the operation of the raising and lowering device 15 will be explained first.

The supernatant liquid withdrawal pipe 14 is
To float above the liquid surface, set the electromagnetic switching valve 29 to the position shown in Fig. 1 to supply compressed air to the upper air pipe 26a.
is supplied to the cylinder body 17b from the rod 17a.
Stretch. Then, the movable pulleys 20a, 20b
The rod 1 descends and approaches the fixed pulley 21, but the rod 1
At the extended end of 7a, there is an allowance in the length of the wire rope 22 that used to make the supernatant liquid drawing pipe 14 stand up, so that the supernatant liquid drawing pipe 14
is rotated downward at the rotary joint 14e and floated above the supernatant liquid level. At this time, the wire rope 22 does not loosen because a weight 24 is provided at its end, but when the liquid level of the supernatant liquid is at the upper limit level HWL for drawing out the supernatant liquid, the weight 24 is attached to the end of the wire rope 22 as shown in Fig. 1. 24 descends to the lower end of the guide tube 23.

In addition, the supernatant liquid drawing pipe 1 is raised by the lifting device 15.
4, the electromagnetic switching valve 29 is switched to the position shown in FIG. Then, compressed air flows from the lower air pipe 26b to the cylinder body 17b.
The rod 17a contracts as the movable pulleys 20a and 20b rise and move away from the fixed pulley 21. The wire rope 22 is a movable pulley 2
Since the wire ropes 22 are wound alternately around the fixed pulleys 21, as the movable pulleys 20a and 20b rise, the weight 24 first hits the stopper 30, and the weight 24 engages with the stopper 30. When the supernatant liquid withdrawal pipe 14 is stopped and cannot rise any further, the supernatant liquid withdrawal pipe 14 is pulled up via the wire rope 22 and becomes an upright state as shown in FIG.

Next, in the biological treatment apparatus configured as described above, a case will be described in which the supernatant liquid of the biological treatment tank 10 whose liquid level is at the upper limit level HWL for drawing out the supernatant liquid is discharged. In this case, the lifting device 15 is operated as described above to float the supernatant liquid withdrawal tube 14 above the liquid surface. Then, the supernatant liquid in the biological treatment tank 10 is
Due to the level difference between the liquid level in the biological treatment tank 10 and the opening of the communication pipe 13, the supernatant liquid enters the inside of the supernatant liquid withdrawal pipe 14 from the extraction port 12, flows down naturally, and flows into the treated water tank 34 via the communication pipe 13. Then, when the liquid level of the treated water tank 33 rises and exceeds the level of the communication pipe 13, the amount of supernatant liquid to be withdrawn is equal to the level of the descending liquid level of the biological treatment tank 10 and the rising liquid level of the treated water tank 33. Since it is determined by the difference, it rapidly decreases, and the closer it gets to the lower limit level LWL for drawing supernatant liquid, the smaller the level difference becomes, and the drawing flow rate decreases to prevent sludge from being entrained. And biological treatment tank 1
When the liquid level reaches the supernatant liquid withdrawal lower limit level LWL and the second level switch 37 detects this,
In response to the detection signal, the electromagnetic switching valve 29 of the lifting device 15 is switched, and the supernatant liquid withdrawal pipe 14 is raised.
At the same time as the drawing of supernatant liquid from the biological treatment tank 10 is stopped, the pump 35 is started, and the pump 35 is started during the next raw wastewater reception, aeration process, and static separation process, that is, before the start of the next supernatant liquid drawing process. 1 level switch 36
Drain the supernatant liquid to the lower limit level L ₂ WL.

Therefore, in the batch type biological treatment apparatus having the above configuration, the above upper limit level H ₂ WL of the treatment water tank 33 is
By adjusting the position of the first level switch 36, the inflection point where the amount of supernatant liquid withdrawn rapidly decreases (the time when it exceeds the liquid level communication pipe 13 of the treated water tank 33)
can be moved to adjust the supernatant liquid withdrawal time or to adjust the supernatant liquid withdrawal flow rate near the supernatant liquid withdrawal lower limit level LWL of the biological treatment tank 10 so as not to cause sludge entrainment.

Furthermore, the pump 35 only needs to discharge the supernatant liquid in the treated water tank 33 before the start of the next supernatant liquid drawing process, which eliminates the problem of a large amount of supernatant liquid at one time, which has been considered a drawback of conventional batch-type biological treatment equipment. The problem of water being discharged has been solved, the pump 35 has become smaller, the treated water tank 33 can be effectively used as a sterilization tank, etc., and the processing equipment for the next process that performs tertiary treatment can be made smaller. There are advantages.

In addition, the supernatant liquid withdrawal time or the biological treatment tank 10
In order to further adjust the supernatant liquid withdrawal speed near the supernatant liquid withdrawal lower limit level LWL, the opening position of the communication pipe 13 may be made variable as shown in FIG. 12.

In FIG. 12, a 90 degree bent pipe 13b is connected to the open end of the communication pipe 13 via a rotary joint 13a so as to be able to rotate up and down, and by changing the height of the outward opening of the bent pipe 13b, The above-mentioned inflection point at which the amount of supernatant liquid withdrawn decreases is moved to allow adjustment of the supernatant liquid withdrawal time or flow rate. Naturally, in this case as well, the opening of the bent pipe 13b must be below the lower limit level LWL for drawing out the supernatant liquid and the upper limit level H ₂ WL.

Further, in the above embodiment, in order to detect that a predetermined amount of supernatant liquid in one cycle of the biological treatment tank 10 has been drawn into the treated water tank 33, the biological treatment tank 10
Based on the supernatant liquid level of 0, it is detected when the supernatant liquid withdrawal lower limit level LWL is reached,
A second level switch 37 is provided which stops drawing out the supernatant liquid from the biological treatment tank 10 and starts the pump 35 based on the detection signal. Based on the level, a liquid level detector is installed in the treated water tank 33 to detect when the liquid level reaches the upper limit level H ₂ WL.
may be provided. Furthermore, for example, the biological treatment tank 10
If the supernatant liquid discharged in one cycle is always constant and the relationship between the liquid levels in the biological treatment tank 10 and the treated water tank 33 is constant, a liquid level detector and a pump are installed to stop drawing out the supernatant liquid. 35 may be provided separately for the biological treatment tank 10 and the treated water tank 33. In addition, if the liquid level in the treated water tank 33 (upper limit level H ₂ WL) when the drawing of the supernatant liquid from the biological treatment tank 10 to the treated water tank 33 is completed is the same level as the lower limit level LWL for drawing out the supernatant liquid, When the drawing of the clear liquid is finished, the supernatant liquid no longer flows through the communication pipe 13, so instead of the second level switch 37, for example, a timer is used, and the time for drawing the supernatant liquid is set in advance with some margin. However, after the drawing of the supernatant liquid is completed, the pump 35 may be activated by the timer, in short, a predetermined amount of the supernatant liquid in one cycle of the biological treatment tank is directly or indirectly drawn into the treated water tank. Any device that can detect this is fine.

Furthermore, in the above embodiment, the first level switch 36 was used to detect that the liquid level in the treated water tank 33 had reached the predetermined lower limit level _L2WL and stop the pump 35. An integrated flow meter is attached to the discharge side piping of the biological treatment tank 10, and this detects when a liquid volume approximately equal to the amount of supernatant liquid discharged in one cycle of the biological treatment tank 10 is discharged from the treated water tank 33, and the pump 35 is activated. It may be stopped. Furthermore, if the biological treatment tank 10 and the treated water tank 33 are configured to be located at a higher position than the equipment for the next process, the pump 35 can of course be omitted, and instead, the supernatant liquid is pumped from the treated water tank 33 using a solenoid valve or the like. Emissions should be controlled. Therefore, the ejection means according to the present invention has various configurations.

Furthermore, it goes without saying that the present invention can be similarly applied to a biological treatment apparatus in which the drawing of supernatant liquid is started and ended by opening and closing the valve 3 as shown in FIG. 14, not by the raising device 15. .

"Effects of the Invention" As explained above, the batch type biological treatment device of the present invention has a treated water tank installed beside the biological treatment tank,
The supernatant liquid in the biological treatment tank is guided into the treated water tank through a supernatant liquid withdrawal pipe, and when the liquid level in the biological treatment tank approaches the lower limit level for supernatant liquid withdrawal, the liquid level in the treated water tank decreases. Since it exceeds the level of the communication pipe, the flow rate of supernatant liquid drawn into the treatment water tank is greatly reduced, so even in the case of sludge with poor settling properties,
It is possible to reliably prevent the entrainment of sludge without significantly increasing the drawing time, and the supernatant liquid in the treated water tank can be removed after the liquid level in the biological treatment tank reaches the lower limit level for drawing the supernatant liquid. Since the liquid is discharged by a discharge means, the problem of a large amount of supernatant liquid being discharged at one time can be solved, and the processing equipment for the next step can be downsized.

[Brief explanation of drawings]

Figures 1 to 11 show an embodiment of the present invention, in which Figure 1 is a cross-sectional view of the entire structure, Figure 2 is a plan view of a supernatant liquid withdrawal pipe, and Figure 3 is a cross-sectional view of the main parts. A side view, FIG. 4 is a cross-sectional view taken in the direction of the arrow in FIG. 2, FIG. 5 is an enlarged view of the lifting device, FIG. - cross-sectional view,
Fig. 8 is a view taken along the - arrow in Fig. 5, Fig. 9 is an explanatory diagram of the wastewater treatment process, Figs. 10 and 11 are overall cross-sectional views for explaining the action, and Fig. 12 is another example of the process. A partial view showing an example, and FIGS. 13 and 14 are schematic cross-sectional views showing a conventional example, respectively. 10... Biological treatment tank, 11... Float, 12... Extraction port, 13... Communication pipe, 14... Supernatant liquid withdrawal pipe,
33...Treatment water tank, 35...Pump, 36...First level switch, 37...Second level switch.

Claims (1)

[Scope of Claims] 1. A supernatant liquid withdrawal pipe that is installed in a biological treatment tank and has a float and a supernatant liquid extraction port at its tip portion, and at least the tip portion follows fluctuations in water level;
A treatment water tank having a capacity equal to or greater than the amount of supernatant liquid discharged in one cycle of the biological treatment tank; a communication pipe that opens at a position below the lower limit level for supernatant liquid withdrawal and introduces the supernatant liquid drawn by the supernatant liquid withdrawal pipe into the treatment water tank; The supernatant liquid is directly or indirectly detected and received into the treated water tank, and the treated water tank is used when a predetermined amount of supernatant liquid is received into the treated water tank in the next cycle of the biological treatment tank. A batch-type biological treatment apparatus, comprising a discharge means for discharging the liquid within a range where the liquid level remains at a height equal to or higher than the opening position of the communication pipe. 2. The batch-type biological treatment apparatus according to claim 1, wherein the communication pipe is provided below the lower limit level for drawing out the supernatant liquid of the biological treatment tank.