JPH0359758B2 - - 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. 3, this is done by opening and closing a valve 3 provided at the discharge end of the supernatant liquid drawing pipe 2 based on a detection signal from a 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, near the end of the supernatant liquid drawing process when the extraction 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) 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 biological treatment apparatus described above, the supernatant liquid is drawn out by gravity as described above, so the drawing flow rate is large at the initial stage of drawing. Therefore, the reality is that the supernatant liquid withdrawal process is started after the activated sludge has settled to a predetermined level or lower (for example, approximately half the liquid level in the static separation process), and the sludge is still There were problems in that the separation process and the supernatant liquid drawing process took a long time, and the drawing time was fixed and could not be adjusted according to the conditions such as the properties of the sludge.

This invention has been made in view of the above circumstances, and an object of the present invention is to provide a batch-type biological treatment apparatus that takes advantage of the advantages of a float-type supernatant liquid drawing pipe and can adjust the supernatant liquid drawing flow rate. With the goal.

"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, one end connected to the base end of the supernatant liquid withdrawal pipe and the other end opened at a position below the supernatant liquid withdrawal lower limit level in the biological treatment tank of the treated water tank. , a communication pipe for introducing the supernatant liquid drawn out by the supernatant liquid drawing pipe into the treatment water tank, a pump for discharging the supernatant liquid received in the treatment water tank, and a liquid level in the treatment water tank. The pump is configured to include a control means for directly or indirectly detecting the liquid level in a state beyond the lower end of the opening of the communicating pipe to start and stop the pump.

"Function" In the batch-type biological treatment apparatus of the present invention, the supernatant liquid in the biological treatment tank is led into the treated water tank through the supernatant liquid drawing pipe and discharged by the pump. The drawing flow rate of the supernatant liquid can be easily adjusted by adjusting the discharge flow rate by the pump.

``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 sludge separation process, 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. The movable pulleys 20a, 20b are freely movable left and right, and 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.
The fixed pulley 21 is rotatable in the same vertical plane as 20b, and the left movable pulley 20a is wound around the right movable pulley 20b via the fixed pulley 21, and one end is connected to the supernatant liquid drawing pipe. 14 through a thimble 22a,
The wire rope 22 has the other end connected to two weights 24 inserted into a guide tube 23 provided vertically on the lower surface of the support frame 16. The cylinder body 17b of the air cylinder 17 has a spude controller 2.
Two air pipes 2 each equipped with 5a and 25b
6a and 26b are connected, and these two air pipes 26
a, 26b are connected to four electromagnetic switching valves 29 which are connected to a compressed air source 28 by an air supply pipe 27, and as shown in FIG. By supplying the rod 17a to
At the same time, as shown in FIG.
a to the cylinder body 17b, the rod 17a is extended, and the movable pulleys 20a, 20
b can be lowered to approach the fixed pulley 21. In addition, the guide tube 2
A stopper 30 made of a pipe having a diameter smaller than that of the weight 24 or a member having a U-shaped cross section when viewed from above is provided at the joint with the support frame 16 of No. It has become impossible to slip out. 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 parts of the member 18, there are wheels 3 at both ends of the axles 32a, 32a, respectively.
Guide wheels 32, 32 comprising guide wheels 2b, 32b are installed with their axes facing forward and backward, and the guide wheels 3
2 and 32 are adapted to move up and down along the guide rails 31 and 31. Furthermore, the biological treatment tank 10 is provided with a first level switch 33 that detects when the level of the supernatant liquid reaches the lower limit level LWL for drawing the supernatant liquid,
A signal from the first level switch 33 causes the electromagnetic switching valve 29 to be switched to the position shown in FIG.

On the other hand, next to the biological treatment tank 10, there is installed a treated water tank 34 (supernatant liquid tank) in which the outer end of the communication pipe 13 is exposed.
A pump 36 with a discharge pipe 35 connected to the discharge side is installed at the inner bottom of the pump. The discharge pipe 35 is provided with a flow meter 37 and a flow rate adjustment valve 38 whose opening degree is adjusted by a signal from the flow meter 37, and a circulation pipe 39 for returning the supernatant liquid to the treated water tank 34. The circulation pipe 39 is connected to the circulation pipe 39 and is provided with an orifice 39a. The treated water tank 34 also includes an upper level switch 40a that detects when the liquid level in the treated water tank 34 reaches a predetermined upper limit level H ₂ WL and starts the pump 36; a lower level switch 4 that detects when the liquid level reaches a predetermined lower limit level _L2WL and stops the pump 36;
0b, the upper level switch 40a and the lower level switch 40b detect the liquid level of the treated water tank 34, and a liquid level detection device 40 that stops the pump 36 based on the detection signal.
(control means).

Here, the installation height of the opening of the communication pipe 13 provided in the treated water tank 34 may be equal to or lower than the lower limit level LWL for drawing out the supernatant liquid in the biological treatment tank 10; S and the above-mentioned supernatant liquid withdrawal lower limit level LWL, preferably the supernatant liquid withdrawal lower limit level LWL.
It is best to install it near the LWL.

Further, the capacity of the treated water tank 34 is much smaller than the amount of water treated in one cycle of the biological treatment tank 10. Furthermore, the liquid level detection position height of the lower level switch 40b (that is, the lower limit level L ₂ WL of the treated water tank 34) is the same level as the lower limit level LWL for drawing out the supernatant liquid of the biological treatment tank 10, and the lower end of the opening of the communication pipe 13. , preferably the same level as the supernatant liquid withdrawal lower limit level LWL. Furthermore, the detection position of the upper level switch 40a (that is, the upper limit level H ₂ WL of the treated water tank 34) is naturally higher than the liquid level detection position of the lower level switch 40b, and the supernatant liquid of the biological treatment tank 10 is flows into the treated water tank 34 through the supernatant liquid withdrawal pipe 14, and the liquid level in the biological treatment tank 10 and the treated water tank 34 is equal to (balances) each other. A level near the lower limit level for supernatant liquid withdrawal, which exceeds the lower limit level LWL for drawing out the supernatant liquid, is preferable.

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 is drawn out from the extraction port 12 into the supernatant liquid withdrawal pipe 1.
4, flows down by gravity and flows into the treated water tank 34 via the communication pipe 13, but since the capacity of the treated water tank 34 is extremely small, the liquid level in the treated water tank 34 rises immediately and the upper level switch 40a is turned on. enters,
The pump 36 is started, which causes the treated water tank 34
The supernatant liquid inside is discharged through the discharge pipe 35. As a result of this discharge, the liquid levels in the biological treatment tank 10 and the treated water tank 34 become approximately equal (balanced), and from now on, the amount of supernatant liquid withdrawn from the biological treatment tank 10 and the treated water tank 34 are equal to each other. Since the liquid level in the water tank 34 decreases at approximately the same level, it becomes approximately equal to the discharge amount of the supernatant liquid discharged from the treated water tank 34 via the pump 36. At this time, the drawing flow rate of the supernatant liquid from the biological treatment tank 10 can be adjusted in advance by adjusting the discharge flow rate of the supernatant liquid by the pump 36; , a flow rate adjustment valve 3 provided in the discharge pipe 35
This can be done by known means such as controlling the rotation of the pump 36 or the rotation of the pump 36.

On the other hand, the withdrawal of the supernatant liquid progresses and the biological treatment tank 10
When the liquid level reaches the supernatant liquid withdrawal lower limit level LWL, the first level switch 33 of the biological treatment tank 10 detects this, and the lifting device 15 is activated by the detection signal.
is activated, the supernatant liquid drawing tube 14 is raised, and the drawing of the supernatant liquid is stopped. Further, the pump 36 is operated until the liquid level in the treated water tank reaches the lower limit level L ₂ WL and the lower level switch 40b detects this.

In this manner, in the biological treatment apparatus having the above configuration, the treated water tank 34 is installed next to the biological treatment tank 10, and the extraction of the supernatant liquid is changed from the initial natural flow to extraction by the pump 36. By adjusting the discharge flow rate of the supernatant liquid from the treated water tank 34, the flow rate of the supernatant liquid withdrawn from the biological treatment tank 10 can be adjusted in advance. Therefore, since the supernatant liquid can be drawn out at a lower drawing flow rate (flow rate) than when using gravity flow, the amount of sludge mixed into the supernatant liquid is lower than before, and this also makes it possible to In the separation process, sludge is completely removed to the lower limit level for supernatant liquid withdrawal.
Even if the precipitation has not reached a predetermined level below the LWL,
In the middle of this static separation process (for example, when the sludge has settled only 40% to 70% of the predetermined level)
However, the supernatant liquid drawing process can be started in parallel with the static separation process, and as a result, the total time of the static separation process and the supernatant liquid drawing process can be shortened. Further, the timing of switching from the initial gravity flow to the extraction by the pump 36 is determined by the upper level switch 40a and the lower level switch 4.
Optimal setting can be achieved by adjusting the mounting position of 0b.

Furthermore, the supernatant liquid of the biological treatment tank 10 flows into the treated water tank 34 via the supernatant liquid withdrawal pipe 14.
This depends on the level difference between the liquid level in the biological treatment tank 10 and the liquid level in the treated water tank 34 or the opening of the communication pipe 13, so if the liquid level in the biological treatment tank 10 approaches the lower limit level LWL for drawing supernatant liquid, the pump 36 Even if the pump is operated at a large discharge flow rate for some reason, the amount of supernatant liquid to be drawn out is limited to the natural flow rate due to the level difference, and the supernatant liquid can be drawn out safely.

By the way, in the above embodiment, when the lower level switch 40b is provided at the same level as the first level switch 33 of the biological treatment tank 10 or near the same level, the first level switch 33 of the biological treatment tank 10 and the lower level switch 40b can be processed by one level switch, so that one of them can be omitted. Also, in place of the first level switch 33 or the lower level switch 40b, an integrated flow meter can be installed on the discharge side piping of the low flow rate pump 36. The pump 36 detects that an amount of liquid equal to the amount of supernatant liquid discharged in one cycle of the biological treatment tank 10 has been discharged from the treated water tank 34.
may be stopped. Furthermore, in the above embodiment, the upper level switch 40a was used as a means for starting the pump 36, but at the beginning of drawing out the supernatant liquid, the liquid levels in the biological treatment tank 10 and the treated water tank 34 are made to be the same, so that the inside of the communication pipe 13 is no longer allowed to flow. Since the supernatant liquid can be prevented from flowing, a timer, instead of the upper level switch 40a, receives a signal indicating the start of supernatant liquid withdrawal, for example, an activation signal of the electromagnetic switching valve 29 of the lifting device 15. The pump 36 may be activated for a predetermined time from the time the signal is received. Therefore, the control means for starting and stopping the pump according to the present invention directly or indirectly controls the treatment water tank 3.
Any device that can detect the liquid level in step 4 may be used. Also,
Of course, the drawing of the supernatant liquid may be started and ended by opening and closing the valve 3 as shown in FIG. 13, instead of using the lifting device 15.

Furthermore, the biological treatment tank 10 is equipped with a liquid level meter and a sludge interface meter that can continuously or intermittently measure the liquid level and the sludge interface. Therefore, the rotation speed of the flow rate regulating valve 38 or the pump 36 may be controlled to continuously control the amount of supernatant liquid discharged by the pump 36.

Furthermore, the height of the open end of the communicating pipe can be adjusted by connecting another pipe, etc. to the open end of the communicating pipe 13 via a rotary joint, and changing the rotational position of the bent pipe, etc. You can also do it like this.

"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,
This system changes the process of drawing out the supernatant liquid from the biological treatment tank through the natural flow of the supernatant liquid drawing pipe to discharging the supernatant liquid from the treated water tank using a pump at a predetermined timing. The supernatant liquid withdrawal flow rate can be optimally adjusted by adjusting with known means, and since the discharge flow rate is inevitably limited to natural flow, it is possible to reliably prevent sludge from being mixed into the supernatant liquid. In addition, the time required for the static separation step and the supernatant liquid drawing process can be shortened, and the supernatant liquid drawing time can be adjusted according to the conditions such as the properties of the sludge.

[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 sectional views for explaining the operation, and Figs. FIG. 13 is a sectional view showing a conventional example. 10... Biological treatment tank, 11... Float, 12... Extraction port, 13... Communication pipe, 14... Supernatant liquid withdrawal pipe,
34...Treatment water tank, 36...Pump, 40...Liquid level detection device (control means).

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;
One end is connected to the proximal end of the supernatant liquid drawing pipe, and the other end is opened at a position below the lower limit level for supernatant liquid drawing in the biophysical tank of the treated water tank, and the supernatant liquid is drawn out by the supernatant liquid drawing pipe. a communication pipe for introducing supernatant liquid into the treated water tank; a pump for discharging the supernatant liquid received in the treatment water tank; and a control means for starting and stopping the pump by detecting directly or indirectly. 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.