JPH0226694A - Supernatant liquid discharge apparatus - Google Patents

Abstract

PURPOSE:To prevent the mixing of sludge by controlling the position of a supernatant liquid discharge pipe and that of an opening end corresponding to the level of a liquid surface by arranging a trough having a supernatant liquid take-in port and a float rotatable around the horizontal axis of the trough to the leading end of the supernatant liquid discharge pipe. CONSTITUTION:The connection pipe 2 connected to a discharge pipe 4 through a rotary joint 3 is provided to the lower part of a liquid tank 1 in a freely rotatable manner and a plurality of supernatant liquid discharge pipes 6 are connected to said connection pipe 2 and the other opening ends 6a thereof are fixed to a trough 7 horizontally arranged on a liquid surface 11 so as to pierce the same. A supernatant liquid take-in port 7 is provided to the trough 7 on the side of the supernatant liquid discharge pipes 6 in order to prevent the mixing of sludge from the opening ends 6a and, further, floats 8 rotatable around the horizontal axis of the trough 7 are arranged to said discharge pipes 6 in parallel to the trough 7. When drain is started, the aforementioned opening ends 6a are lowered from the liquid surface 11 by the moving operation of the floats 8 and, when a water level is lowered to the vicinity of a sludge interface 12, the opening ends 6a are raised above the liquid surface 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a supernatant liquid discharge device used in patch-type water treatment such as batch-type activated sludge treatment.

[Prior art] Water treatment using the batch type activated sludge method, which is known as a typical example of batch type water treatment, involves the process of flowing wastewater into a biological treatment tank, undergoing aeration and sedimentation treatment, and then discharging the treated water. It is done repeatedly.

In the discharge process, only the upper supernatant liquid is discharged from the sludge interface produced when sewage is settled, and various devices have been devised in the past. For example, “Water and Wastewater J Vol. 28
．． An example is introduced in No. 4 (1986), p. 72-75.

FIGS. 5 and 6 show a cross section and a plane of this conventional example.

This conventional example has the following configuration.

One end of a connecting pipe 2 arranged horizontally at the bottom of the liquid tank 1 is rotatably fixed to a side wall, and the other end projects into the side chamber 13 from a through hole in the opposing side wall.

A rotary seal 14 is provided in the through hole to prevent the liquid in the liquid tank from flowing out, and supports the connecting pipe 2. One end of four supernatant liquid discharge pipes 6 is fixed in communication with the connecting pipe section in the liquid tank in a direction perpendicular to the axis, and the other end on the water surface side is fixed to a trough 7. Baffle floats 1f are rotatably attached to both ends of the trough 7 to prevent scum floating on the liquid surface from flowing in through the suction port of the trough 7.

An arm 16 is fixed to a connecting pipe protruding outside the liquid tank, and the tip of the arm 16 is connected by a connecting rod 15 to a rod of a cylinder 9 provided on the ceiling of the side chamber.

To discharge the supernatant using this device, perform the following operations.

When the precipitation process is completed, by moving the rod of the cylinder 9 downward, the connecting pipe 2 is rotated, and the supernatant liquid discharge pipe 6 fixed to the connecting pipe is rotated into the trough 7 and the trough 7 at the tip of the supernatant liquid discharge pipe 6. Connected baffle float 1
7 is positioned near the liquid surface, and the baffle float 17 prevents the inflow of scum, while allowing the supernatant liquid to naturally flow into the opening of the supernatant liquid discharge pipe 6 and draining it out of the liquid tank. As the surface descends, the rod of the hydraulic cylinder is lowered,
The baffle float and the end opening of the supernatant liquid discharge pipe are operated so as to be located near the liquid level.

When the supernatant liquid reaches the bottom liquid level (slightly above the sludge interface), the rod of the cylinder 9 is raised and the tip opening of the supernatant liquid discharge pipe 6 is connected to the liquid level 1 with the baffle float 17.
After raising the tank higher, the wastewater is poured in and subjected to aeration and sedimentation treatment, and the same operation is repeated.

[The invention attempts to solve i! I subject] However, conventional devices have the following drawbacks.

1) When the supernatant liquid is not discharged, it is necessary to lift the tip of the supernatant liquid discharge pipe, the trough, and the baffle float into the air, which requires a large driving force for the cylinder.

2) When discharging the supernatant liquid, it is necessary to control the baffle float to the liquid level position by lowering the rod of the cylinder in synchronization with the drop in the liquid level, so a synchronized control device is required.

3) When the baffle float, which is raised in the air, is lowered to float above the liquid surface at the start of supernatant liquid discharge, the scum present in the baffle float is sucked into the supernatant liquid discharge pipe, deteriorating the quality of the discharged liquid. let

[Means for Solving the Problems] The present invention solves the problems of the prior art described above, allows discharge of supernatant liquid after sewage treatment with a simple operation, and uses a drive device for operation compared to the conventional one. The present invention provides a supernatant fluid discharge device that can be used on a fairly small scale, and its configuration is as follows.

A connecting pipe 2, which is sealed at one end and rotatably connected to a pipe 4 piped outside the liquid tank at the other end, is connected to a plurality of brackets A fixed to the lower part of the liquid below the bottom discharge liquid level 11a. It is rotatably supported around a horizontal axis, and one end of a supernatant liquid discharge pipe 6 extending in the liquid surface direction is fixed to the connecting pipe 2 in a communicating state, and the other end is opened and serves as a supernatant liquid intake port. A float 8 is connected to the horizontal axis 7b of the trough 7 via a bracket B, and the float 8 can be rotated by a drive device 9 about the horizontal axis of the trough 7. A supernatant liquid discharge device characterized by:

[Function] Figures 4 (a), (0), and (8) explain the operation of the main parts of the supernatant liquid discharge device according to the present invention.

(A) shows a state in which the supernatant liquid is not discharged. In this state, the float 8 is rotated counterclockwise (θ) by the drive device 9 with the horizontal shaft b of the trough 7 as the rotation center and the middle of the supernatant liquid discharge pipe 6 as the reaction force point 9b. is positioned above the float 8 floating on the liquid surface. As a result, the open end 6a of the supernatant liquid discharge pipe 6 fixed to the trough 7 is located above the liquid level (ho), and the liquid does not flow into the discharge pipe.

(b) and (8) indicate the state during discharge of the supernatant liquid. In this state, the drive device 9 rotates the float 8 clockwise around the horizontal axis 7b of the trough 7 (θ, θ,). As a result, the trough 7 rotates the float 8
trough 7.
The open end 7b of the supernatant liquid discharge pipe fixed to is immersed in the liquid, and the liquid flows into the discharge pipe and is discharged out of the liquid tank.

Since the float 8 is always floating on the liquid surface, even if the liquid level drops as the supernatant liquid is discharged, the float automatically follows the liquid level and the liquid is discharged.

If the rotation angle θ of the trough 7 and the float 8 is kept constant, the liquid discharge height h is deep at the start of discharge and becomes shallower as the liquid level 1 decreases.

When the liquid level 1 decreases, it approaches the sludge interface 12, which is preferable because water can be drained from a shallow depth from the liquid level 1 and a clear supernatant liquid can be discharged.

The liquid discharge depth (h) is controlled by the rotation angle (θ) of the trough 7 and float 8, and the rotation angle (θ) is determined by the amount of movement of the foot by the drive device (if a cylinder is used as the drive device). The case is controlled by the stroke (S)).

That is, the relationship shown in Table 1 is obtained.

Table-1 Here, the rotation angle (θ) is the axial extension line of the supernatant liquid discharge pipe,
Indicates the angle between the line connecting the center of rotation of the trough and the center of the float.

[Embodiment] FIGS. 1 and 2 are side views of an apparatus according to an embodiment of the present invention.

FIG. 3 is a plan view of the apparatus of the embodiment in a substantially horizontal position.

A plurality of brackets A5 are fixed to the lower side wall of the liquid tank 1. The mounting position of the bracket A is such that the supernatant liquid discharge pipe 6 is slanted upward to be discharged, so that the supernatant liquid is at the lowest discharge level 1.
．． It is necessary to keep it below 1a.

A connecting pipe 2 whose one end is sealed and whose other end is connected by a rotation joint 3 to a discharge pipe 4 piped outside the liquid tank is rotatably supported around a horizontal axis by the bracket A5.

One ends of a plurality (four) of supernatant liquid discharge pipes 6 extending in the direction of the water surface are welded and fixed to the connecting pipe 2 at appropriate intervals so that the insides of the pipes are in communication with each other.

The other end of the supernatant liquid discharge pipe 6 remains open and the liquid level 11
It is extended to the vicinity, penetrates into the horizontally arranged trough 7, and is fixed.

A notch is provided in the direction of the supernatant liquid discharge pipe of the trough 7 to form a supernatant liquid intake lower a. That is, when the open end 6a of the supernatant liquid discharge pipe 6 is submerged in the liquid, 1. When liquid is introduced from the supernatant liquid intake lower a of the trough 7 and discharged from the sekiguchi 46a through the discharge pipe to the outside of the liquid tank, when the liquid level is high, the supernatant liquid discharge pipe 6 is in a nearly vertical state. Since the liquid is taken in from below, no scum is mixed in, and since it is separated from the sludge interface 12, there is no effect of water flow that occurs when taking in the liquid.Also, when the drainage liquid level reaches the bottom, the supernatant liquid is discharged. Although the inclination of the pipe 6 is close to horizontal, the supernatant liquid intake lower a is submerged in the liquid to prevent scum from being mixed in and to take in the liquid from a nearly horizontal direction, so that it is not connected to the sludge interface 12. Even if the distance is short, there is no risk of sludge being mixed in by water flow.

In addition, if a device that can properly remove scum is installed,
Of course, if scum does not occur much, the supernatant liquid intake lower a of the trough may be moved upward.

A horizontal shaft 7b is provided at the center of both ends of the trough 7 in a protruding manner. Brackets B8a fixed to both ends of a float 8 arranged parallel to the outside of the trough are rotatably connected to this horizontal shaft 7b.

Another bracket C8b is provided at the axial center of the float 8 at a position approximately 90 degrees apart from the bracket Baa and protrudes from the outer surface, and is connected to a rod 9a of the drive device 9, which will be described later.
is connected with a pin.

The drive device 9 uses a cylinder connected to a reaction force point 9b provided at an axially intermediate portion of the two supernatant liquid discharge pipes 6.

This cylinder may be driven by either hydraulic or pneumatic pressure, and is remotely controlled from an operation panel outside the liquid tank (not shown).

In addition to the hydraulic or pneumatic cylinder type as shown in this embodiment, the drive device may be a hydraulic or pneumatic cylinder type as shown in this embodiment, or the bracket C of the float.
The rope end is fixed at the end of the rope, and the rope is tensioned by a drive device such as a winch installed outside the liquid tank via a roller provided on the connecting pipe, or a rotating mechanism is attached to the bracket B8a of the float 8. , a method of transmitting relative rotation to a gear or the like provided on the horizontal shaft 7b of the trough 7 may be used.

10 is a stopper for preventing the supernatant liquid discharge device from contacting the side wall of the liquid tank 1 at the highest liquid level.

When discharging the supernatant liquid from batch-type activated sludge water treatment using the apparatus configured as described above, the procedure is as follows.

This device is kept floating on the liquid surface during all the water treatment steps, including inflow of sewage, aeration, sedimentation, and wastewater, and the drive device is operated only during the draining step. At the start of drainage, the float 8 is rotated clockwise around the horizontal axis 7b of the trough 7, so that the open end 6a of the supernatant liquid discharge pipe reaches the liquid level 11.
Make it lower.

As a result, the supernatant liquid slightly below the liquid level 11 is continuously discharged out of the liquid tank through the discharge pipe. As the supernatant liquid is discharged, the liquid level 11 decreases, and when it reaches a predetermined water depth near the sludge interface 12, a drainage stop signal is sent from a liquid level gauge separately installed for water treatment process control, and the drive device 9 moves the float 8 to the trough. 7
The opening end 6a of the supernatant liquid discharge pipe 6 is made to be above the liquid level 11 by rotating it counterclockwise with respect to the horizontal axis of the supernatant liquid discharge pipe 6.

When sewage is introduced in this state, the liquid level gradually rises without being drained, and the aeration, sedimentation, and drainage steps are then repeated.

It goes without saying that this device can be used for discharging supernatant liquid in batch-type sedimentation processes other than discharging supernatant liquid in batch-type activated sludge treatment.

[Effects of the Invention] According to the present invention, a float is connected via a bracket to the horizontal shaft of a trough having a supernatant fluid inlet, and the float is rotated by a drive device about the shaft of the trough, Since the system is configured to control the discharge of supernatant liquid, the device is supported on a float above the liquid level during the entire water treatment process, and the drive device is operated only when starting and stopping drainage. This makes it a very simple automatic device.

In addition, since the drive device is only used for relative rotation of the float and trough, a smaller device should be used when the supernatant liquid is not being discharged as in the conventional method, compared to the method of lifting the float and trough into the air. becomes possible.

In addition, if the rotation angle of the float and trough is kept constant, the supernatant liquid will be discharged at a certain depth from the liquid level at the start of the discharge, and as the liquid level descends (as it approaches the sludge interface) it will become shallower from the liquid level. position, allowing clear supernatant liquid to be discharged.

It is also possible to keep the discharge depth of the supernatant constant by adjusting the rotation angles of the float and the trough during the discharge of the supernatant.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 show an embodiment of the present invention;
The figure is a side view showing the itl position of the device during supernatant liquid discharge.
The figure shows the situation when drainage is stopped after reaching the bottom liquid level, Figure 3 is a plan view when the device is in a nearly horizontal state, Figure 4 is an explanatory diagram of the main parts of the supernatant liquid discharge of the present invention, and Figure 5 6 are explanatory diagrams of a conventional device. 1...Liquid tank 2...Connecting pipe 3...Rotating joint 4...Discharge pipe 5...Bracket A
6...Supernatant liquid discharge pipe 6a...Open end
7...Trough 7a...Liquid collection population 7b
...Horizontal shaft 8...Float 8a...Bracket B8b...Bracket C 9...Drive device (cylinder) 9a...Cylinder rod 9b...Fixing point 10.
... Stopper 11 ... Liquid level 11a ... Minimum discharge liquid level 12 ... Sludge interface 13 ... Side chamber
14... Rotating seal 15... J knot 1
16...Arm 17...Baffle float

Claims (1)

[Claims] 1 One end is sealed and the other end is a pipe (4
) is rotatably connected to the connecting pipe (2), which is rotatably supported around a horizontal axis by a plurality of brackets A fixed to the lower part of the liquid tank below the lowest discharge liquid level (11a),
One end of a supernatant liquid discharge pipe (6) extending in the liquid surface direction is fixed in communication with the connecting pipe (2), and the other end is opened and fixed to a trough (7) having a supernatant liquid intake port. has been
A float (8) is connected to the horizontal shaft (7b) of the trough (7) via a bracket B.
) is a supernatant liquid discharge device characterized in that it is rotatable by a drive device (9) about the horizontal axis of the trough (7).