JP2002336601A - Deaerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deaerating apparatus, in which bubbles in a liquid to be treated is satisfactorily removed before the liquid to be treated is introduced into a flocculating and settling tank. SOLUTION: In the deaerating apparatus 10 for removing the bubbles from the liquid to be treated before being introduced into the settling tank 12 to clarify the liquid to be treated by precipitation separation, a flow passage 34 formed along the circumferential direction of the side wall 16 of the settling tank on the upper part of the side wall is provided and the liquid to be treated is introduced into one end of the flow passage and flows out from another end of the flow passage to be introduced into the settling tank. In the constitution, the bubbles in the liquid to be treated are floated and removed while the liquid to be treated is fluidized in the flow passage. At this time, the water depth of the flow passage is relatively shallow and then the floating and removal of the bubbles are efficiently performed. The exclusive installation space for the deaerating apparatus becomes needless, because the flow passage of the deaerating apparatus is used also for a part of the settling tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sedimentation tank for clarifying a liquid to be treated by settling and separating suspended substances and the like in a liquid to be treated. The present invention relates to a deaerator for removing bubbles contained in the liquid to be treated.

[0002]

2. Description of the Related Art There is a coagulation sedimentation tank as a sedimentation type water treatment apparatus. In this method, suspended substances and the like contained in a liquid to be treated such as factory wastewater are aggregated and flocculated by an appropriate additive, and the suspended substances and the like are to be precipitated and removed from the liquid to be treated.

If the liquid to be treated is introduced into such a coagulating sedimentation tank while containing air bubbles, the coagulation of the suspended substance is hindered, or the air bubbles adhere to fine particles such as coagulated flocs and suspended substances. These settlements are hindered. These cause the water quality of the treated liquid to deteriorate.

[0004] Therefore, conventionally, a deaerator has been installed in the preceding stage of the coagulation sedimentation tank to achieve deaeration, that is, removal of bubbles in the liquid to be treated. The conventional general deaerator uses a cylindrical or rectangular parallelepiped water tank. The liquid to be treated introduced therein is subjected to coarse bubble aeration, and the bubbles in the liquid to be treated are removed by removing the coarse bubbles. And a method of removing bubbles in the liquid to be treated by mechanical stirring.

[0005]

However, the conventional degassing apparatus as described above may not provide a sufficient degassing effect.

Accordingly, an object of the present invention is to provide a deaerator capable of sufficiently removing bubbles in a liquid to be treated before introducing the liquid to a sedimentation tank such as a coagulation sedimentation tank. .

[0007]

Means for Solving the Problems In order to achieve the above object, the present inventor has conducted various studies, and as a result, the conventional deaerator
It was considered that the bubbles were not sufficiently removed because the water depth of the water tank was considerably deep, and the water pressure was high at the bottom of the water tank, and it also took time for the bubbles to reach the upper surface of the blower.

From this finding, it is sufficient to construct a deaerator having a shallow water tank, but a new problem arises in that the bottom area of the deaerator is increased and the installation space is increased. .

Therefore, the present invention provides a deaerator for removing air bubbles from a liquid to be treated which is introduced into a sedimentation tank for clarifying the liquid to be treated by sedimentation separation. A flow path formed along the direction is provided, a liquid to be treated is introduced into one end of the flow path, and the liquid to be treated flows out from the other end of the flow path and is introduced into the precipitation tank. And

In this deaerator, while the liquid to be treated is flowing from one end of the flow path to the other end, bubbles in the liquid to be treated can be lifted and removed. Since this flow path is provided above the side wall of the settling tank, its water depth is relatively shallow. Therefore, the floating removal of bubbles is performed efficiently. In addition, since the flow path of the deaerator becomes a part of the settling tank, a dedicated installation space for the deaerator is not required.

It is preferable that the flow path is provided with aeration means for blowing coarse bubbles into the liquid to be treated flowing therethrough. This is because the bubbles in the liquid to be treated are taken in by the coarse bubbles and removed by blowing the coarse bubbles.

It is preferable that a plurality of baffle plates are alternately arranged in the flow path in the flow direction of the liquid to be treated, left and right or up and down. By alternately arranging the baffle plates, the flow path is extended, the period of floating removal of air bubbles becomes sufficient, and the liquid to be treated is stirred to promote the removal of air bubbles.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 show an embodiment of a deaerator according to the present invention. The deaerator 10 according to this embodiment is applied to a coagulation sedimentation tank (hereinafter, simply referred to as a “sedimentation tank”) 12, which is a kind of sedimentation separation type sedimentation tank.

The illustrated settling tank 12 has a bottom portion 14 and a cylindrical side wall 16 erected on the bottom portion 14, and a cylindrical mixing chamber 18 is provided inside the bottom portion 14. An inlet 20 through which a liquid to be treated such as factory wastewater is introduced is formed in an upper portion of the mixing chamber 18. When the liquid to be treated is introduced into the mixing chamber 18, an additive such as a polymer flocculant is injected, and suspended substances and the like in the liquid to be treated are aggregated to form flocs. The liquid to be treated containing the flocculated floc is mixed in the mixing chamber 1
8 is uniformly distributed and supplied into the sedimentation tank 12 from the distributor 22 below. As a result, a uniform upward flow is generated in the sedimentation tank 12, and flocculated flocs and the like in the liquid to be treated are settled and separated by gravity, and the upper layer of the liquid to be treated in the sedimentation tank 12 becomes an extremely clear supernatant liquid. . The supernatant liquid passes through the trough 24 and flows out of the outlet 26 of the precipitation tank 12 as a clear and processed liquid.

During the operation, the liquid level of the liquid to be treated in the sedimentation tank 12 is maintained at substantially the same height as the upper edge of the trough 24. The liquid inlet 20 of the mixing chamber 18 is provided at a position lower than the upper edge of the trough 24.

The deaerator 10 according to the present embodiment, which is applied to such a sedimentation tank 12, comprises a side wall 1 of the sedimentation tank 12.
6 is provided with an annular bottom plate 28 fixed to the outer peripheral surface by appropriate means such as welding. The bottom plate 28 extends substantially horizontally outward from the side wall 16. The height of the bottom plate 28 is above the side wall 16 of the sedimentation tank 12, and specifically, between the upper edge of the trough 24 (that is, the liquid surface of the liquid to be treated) and the inlet 20 of the mixing chamber 18. It is an intermediate position in the height direction. In addition, as shown in FIG.
The height position of the bottom plate 28 can be lower than the position of the inlet 20.

The deaerator 10 has a cylindrical outer plate 30 fixed to the outer peripheral edge of the bottom plate 28 by welding or the like. The outer plate 30 extends substantially vertically upward, and its upper edge is positioned higher than the upper edge of the trough 24.

The outer plate 30, the bottom plate 28, and the side wall 16 of the settling tank 12 define an annular groove.
, A partition plate 32 is attached. Thus, the groove becomes one annular flow path 34 extending from one surface side of the partition plate 32 to the other surface side. At one end of the flow path 34, that is, at a position adjacent to one surface of the partition plate 32, an outlet end of an introduction pipe 36 for introducing the liquid to be treated is provided. Further, the partition plate 3 is provided on the bottom plate 28.
The outlet 38 of the liquid to be treated is located at a position adjacent to the other surface of
Are formed. Therefore, when the liquid to be treated is introduced into the flow path 34 through the introduction pipe 36, the liquid to be treated flows in the direction of arrow A in FIG. The outlet 38 of the flow path 34 and the inlet 20 of the mixing chamber 18 are connected via a transfer pipe 40.

The deaerator 10 of the illustrated embodiment further includes an air supply pipe 42 disposed on the bottom plate 28. The air supply pipe 42 has an air pump 4 outside the deaerator 10.
4 air outlets are connected. The air supply pipe 4
2, air outlets 46 are formed at appropriate intervals. The diameter of the air outlet 46 is relatively large, and when the air pump 44 is driven to send air into the air supply pipe 42,
Bubbles with a large diameter, so-called coarse bubbles, are blown into the liquid to be treated in the flow path 34.

As shown in FIG. 2, a plurality of baffle plates 48 are alternately attached to the flow path 34 of the deaerator 10 along the flow direction (arrow A direction) of the liquid to be treated. I have.

The deaerator 10 having such a configuration is installed as a part of the sedimentation tank 12 and is provided above the side wall 16 of the sedimentation tank 12. No special installation space is required.

At one end of the flow path 34 of the deaerator 10,
When a liquid to be treated such as factory wastewater is introduced from the inlet pipe 36, the liquid to be treated flows in the flow path 34 toward the outlet 38 on the other end side, and flows from the outlet 38 through the transfer pipe 40 into the mixing chamber 18. be introduced. In this case, the inlet 20 of the mixing chamber 18 is located at a position lower than the upper edge of the trough 24 of the sedimentation tank 12 (the liquid level in the sedimentation tank), and the bottom plate 28 of the deaerator 10 is located lower than the inlet 20. High and trough 24
Since the liquid to be processed is located at a position lower than the upper edge of the liquid, the liquid to be processed introduced into the flow path 34 naturally flows to the outlet 38 and then flows to the mixing chamber 18.

While the liquid to be processed is flowing in the flow path 34, the bubbles in the liquid to be processed float and float to the atmosphere.
At this time, the air pump 44 is driven, and the air becomes coarse bubbles from the outlet 46 of the air supply pipe 42,
Is blown into the liquid to be processed flowing through the flow path 34, so that the bubbles in the liquid to be processed are taken in by the coarse bubbles, and the removal is promoted.

Here, the degassing device 10 according to the illustrated embodiment
Since the flow path 34 is installed above the sedimentation tank 12, its water depth is as shallow as about 30 cm to 100 cm,
It will be understood that the pressure of the liquid to be processed flowing at the bottom of the flow path 34 is low. Therefore, bubbles in the liquid to be processed flowing at the bottom of the flow path 34 are also efficiently removed.

The channel 34 has a plurality of baffle plates 48.
Are alternately attached, so that the flow path 34 is extended, and a sufficient period for removing bubbles is obtained. Moreover, during the period, the liquid to be treated is exposed to coarse bubbles, so that the bubbles are surely removed. Furthermore, the baffle plate 4
Due to the presence of 8, the liquid to be treated is subjected to a stirring action, which also promotes the removal of bubbles in the liquid to be treated. This stirring action also plays a role in preventing precipitation of suspended substances and the like contained in the liquid to be treated.

In consideration of the stirring effect of the baffle plate 48 and the stirring effect of aeration of the coarse bubbles, a pH adjuster is supplied to the flow path 34 to adjust the pH of the liquid to be treated, or to adjust the pH of the inorganic coagulant. (PAC) may be added to cause a primary agglutination reaction of the suspended substance in the liquid to be treated.

Although the preferred embodiments of the present invention have been described in detail, it goes without saying that the present invention is not limited to the above embodiments.

For example, in the above embodiment, the flow path 34 is formed by the side wall 16, the bottom plate 28 and the outer plate 30 of the sedimentation tank 12, but the gutter-like member is provided on the upper part of the side wall of the sedimentation tank 12 in the circumferential direction. It may be attached along. Also, for a large sedimentation tank, the flow path does not need to be formed over the entire circumference.

Although a plurality of baffle plates 48 are alternately arranged in the flow path 34 in the left and right direction along the flow direction of the liquid to be treated, they may be alternately arranged in the up and down direction. In this case, the effect of preventing sedimentation of suspended substances and the like is further improved.

Further, the means for aerating the coarse bubbles is not limited to the means using the air supply pipe 42, and a configuration in which an air nozzle is directly attached to the bottom plate 28 may be considered.

Depending on the properties of the liquid to be treated, only one of the coarse bubble aeration means and the baffle plate may be provided in the flow path, or both of them may be omitted. This is because a certain deaeration effect can be obtained only by flowing the liquid to be processed through the shallow flow path.

Further, the deaerator according to the present invention can be applied to a sedimentation tank in which coagulation is not performed inside the tank.

[0034]

As described above, according to the deaerator according to the present invention,
Before introducing the liquid to be treated into the settling tank, it is possible to sufficiently remove bubbles from the liquid to be treated. Therefore, sedimentation and separation of suspended substances and the like in the sedimentation tank can be efficiently performed.
In particular, in the coagulation sedimentation tank, since the air bubbles prevent the formation of coagulated flocs, the deaerator according to the present invention having a high deaeration effect is effective.

Further, since the degassing device according to the present invention requires substantially no installation space, the site of the water treatment facility can be effectively used or the site can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a deaerator according to the present invention and a flocculation settling tank to which the deaerator is attached.

FIG. 2 is a schematic sectional view taken along line II-II of FIG.

FIG. 3 is a view showing a modification of the deaerator according to the present invention, and is a longitudinal sectional view partially showing an upper part of the coagulation and sedimentation apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Deaerator, 12 ... Coagulation sedimentation tank, 16 ... Side wall, 18
... mixing chamber, 20 ... inlet, 24 ... trough,
28 ... bottom plate, 30 ... outer plate, 32 ... partition plate, 34 ... flow path, 36 ... introduction tube, 38 ... outlet, 40 ... transfer tube, 42
... Air supply pipe (coarse bubble aeration means).

Claims (3)

[Claims] 1. A deaerator for removing air bubbles from a liquid to be treated which is introduced into a sedimentation tank for clarifying the liquid to be treated by settling separation, comprising: Wherein the liquid to be treated is introduced into one end of the flow path, and the liquid to be treated flows out from the other end of the flow path and is introduced into the sedimentation tank. And deaerator. 2. The deaerator according to claim 1, further comprising an aerator for blowing coarse bubbles into the liquid to be processed flowing through the flow path. 3. The degassing device according to claim 1, wherein the flow path includes a plurality of baffle plates alternately arranged along a flow direction of the liquid to be treated.