JP2010179255A - Agitating and mixing device, and precipitating vessel equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agitating and mixing device in which an agitating and mixing efficiency is greatly enhanced and which reduces a holding time. <P>SOLUTION: The agitating and mixing device 2 includes a cylindrical container 21 of which the bottom is closed and of which the top is opened, an inflow pipe 51 connected to the bottom of the cylindrical container 21 with a pipe and allowing to inflow waste water P1 and a flocculant P2 to the inside of the cylindrical container 21, and an agitating member 23 generating down-flow in the inside of the cylindrical container 21. The waste water P1 and the flocculant P2 are agitated and mixed at a strongly agitating part formed with the up-flow of the waste water P1 and the flocculant P2 inflowing to the inside of the cylindrical container 21 through the inflow pipe 51, and with the down-flow by the agitating member 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an agitation and mixing device used in a treatment process in which waste water and a treatment agent are agitated and mixed (for example, agitation and mixing of waste water and a flocculant) in a wastewater treatment facility, and a precipitation equipped with the agitation and mixing device. Regarding the tank.

Stir mixing is a basic operation of wastewater treatment and there are many examples of methods and equipment.
Depending on the type of wastewater and the purpose of the treatment, in many cases, uniform stirring and mixing are required, and improvements and developments are being made to improve mixing efficiency, such as wastewater treatment using chemicals.

  A typical example of wastewater treatment using chemicals is the coagulation sedimentation method. Treated water is obtained by bringing a flocculant into contact with the wastewater to precipitate the contaminated components dissolved in the wastewater as sludge, and separating the sludge. As shown in FIG. 6, a typical process flow includes a mixing tank 100 in which the flocculant P2 is added to the waste water P1 and agitated and mixed, a flocculating tank 102 in which the agglomeration aid P3 is added and agitated and mixed, and then a static bath. And a coagulating sedimentation tank 104 for depositing sludge. In the coagulation sedimentation tank 104, the precipitated sludge is scraped to the center of the tank by the sludge squeezer 105, extracted from the bottom of the tank, and transferred to the outside by the sludge extraction pump (not shown). ing. Here, the mixing tank 100 may be referred to as a rapid stirring tank, and the aggregation tank 102 may be referred to as a slow stirring tank. In the mixing tank 100, the purpose is to stir and mix the waste water P1 and the flocculant P2 by high-speed stirring at about 300 rpm, and in the coagulating tank 102, the purpose is to grow aggregated flocs by slow stirring at about 50 rpm. In the mixing tank 100 and the coagulation tank 102, the stirrer 101 is often used, and the mixing tank 100 is designed with a residence time of 5 minutes or longer in the mixing tank 100 and 20 minutes or longer in the coagulation tank 102 (refer to Non-Patent Documents 1 and 371 below). ).

National Urban Cleanup Council, “Plans and Design Guidelines for Final Waste Disposal Site Development”, page 371

  Therefore, the conventionally used coagulation sedimentation method has a drawback in that the volume of the mixing tank 100 and the coagulation tank 102 increases because the residence time is long. Moreover, since there are many apparatuses, there existed a fault that a maintenance burden was large.

The present invention has been conceived in view of the above problems, and an object of the present invention is to provide a stirring and mixing apparatus capable of greatly improving the stirring and mixing efficiency and shortening the residence time.
Another object of the present invention is to have the function of a conventional mixing tank and the function of a coagulation tank while having a single structure of one tank, so that the number of devices including a stirrer and the number of water tanks are increased. It is providing the sedimentation tank which can reduce equipment and can simplify an installation.

  The gist of the present invention is an agitation and mixing device for agitating and mixing water to be treated and a treatment agent, wherein the bottom part is closed and the upper part is opened, and a pipe is connected to the lower part of the cylindrical container. An inflow pipe for allowing the water to be treated and the treatment agent to flow into the inside of the cylindrical container, and stirring means for generating a downward flow inside the cylindrical container, and the inside of the cylindrical container via the inflow pipe The water to be treated and the treatment agent are stirred and mixed in a strong stirring portion formed by the water to be treated that has flowed into the water, the upward flow of the treatment agent, and the downward flow of the stirring means.

  According to the above-described configuration, the downflow generated by the stirring means collides with the upflow of the water to be treated and the processing agent to form a strong turbulent stirring portion, so that the stirring and mixing efficiency is improved. In addition, the contact time is ensured in the upward flow portion from the strong stirring portion to the overflow portion, and stirring and mixing are further promoted by rising while swirling and mixing. As described above, since the stirring and mixing efficiency is improved, the residence time can be significantly shortened, so that the volume of the apparatus can be reduced.

  Here, examples of the combination of the water to be treated and the treatment agent to be stirred and mixed include waste water and a flocculant, raw water and a pH adjuster, and raw water and powdered activated carbon. Of course, the present invention is not limited to these, and can be widely applied to an apparatus for stirring and mixing water to be treated and a treatment agent.

  In the present invention, the treated water may be waste water and the treating agent may be a flocculant. That is, the present invention can be applied to an apparatus that stirs and mixes wastewater and a flocculant in the course of wastewater treatment.

  In the present invention, an outer cylinder that is open on both the top and bottom of the cylindrical container is provided outside the cylindrical container, and a cutout portion is formed in the upper peripheral edge of the cylindrical container. It is desirable to provide a coagulation aid adding means for adding the coagulation aid to the water surface portion where the stirred mixed solution flows from the notch to the outer cylinder.

  According to such a configuration, when the stirred mixed solution overflows, it always flows from the notch portion. Therefore, the contact efficiency between the stirred mixed liquid and the coagulation aid is good. In addition, after the mixed liquid that has overflowed contacts the flocculation aid, a floc of sludge is efficiently grown by forming a downward flow while swirling gently between the cylindrical container and the outer cylinder. It becomes possible to make it. In order to improve the contact efficiency between the stirred mixed solution and the coagulant aid, it is preferable to limit the notched portion to one location.

  Another gist of the present invention is a settling tank provided with the stirring and mixing device according to claim 3, wherein the water surface position of the settling tank is from the upper surface to the bottom surface of the cutout portion of the cylindrical container constituting the stirring and mixing device. The stirring and mixing apparatus is installed so that it exists in the range to.

  Here, the installation position of the stirring and mixing apparatus is regulated as described above for the following reason. That is, when the water surface position of the settling tank is below the bottom surface of the cutout portion of the cylindrical container, the stirred mixture overflowed from the cylindrical container is below the bottom surface of the cutout portion of the cylindrical container. Since it falls to a certain surface of the water, there is no process of forming a downward flow while gently swirling between the cylindrical container and the outer cylinder, and it becomes impossible to efficiently grow flocs of coagulated sludge. Because. On the other hand, when the water surface position of the settling tank is above the upper surface of the cutout portion of the cylindrical container, the stirred mixed liquid cannot inherently overflow from the cylindrical container.

  With the above configuration, the cylindrical container that functions to stir and mix the waste water and the flocculant corresponds to a conventional mixing tank. The outer cylinder that functions to form a space for growing flocs of the coagulated sludge corresponds to the conventional coagulation tank. Therefore, while having a single tank structure, it has the functions of a conventional mixing tank and a coagulation tank, thereby reducing the number of devices including a stirrer and the number of water tanks and simplifying the equipment. can do.

  In addition, the stirring and mixing device provided in the settling tank has a structure in which the waste water and the flocculant reliably pass through the strong stirring section, so that the stirring and mixing efficiency can be improved and the residence time can be shortened, so the volume of the device can be reduced. it can. Therefore, it is possible to use a sedimentation tank having a small volume according to the stirring and mixing apparatus.

According to the stirring and mixing apparatus according to the present invention, since the waste water and the flocculant reliably pass through the strong stirring section, the stirring and mixing efficiency can be improved and the residence time can be shortened, so that the volume of the apparatus can be reduced. .
Moreover, according to the precipitation tank provided with the stirring and mixing apparatus according to the present invention, while having a single structure of one tank, it has a function of a mixing tank and a function of a coagulation tank of a conventional example. The equipment can be simplified by reducing the number of equipment and the number of water tanks.

The block diagram of the sedimentation tank provided with the stirring mixing apparatus which concerns on this invention. 1 is a schematic elevation view of a stirring and mixing apparatus according to the present invention. 1 is a schematic plan view of a stirring and mixing apparatus according to the present invention. The block diagram which shows the other example of application of a stirring and mixing apparatus. The block diagram which shows the further another example of application of a stirring and mixing apparatus. Flow diagram of standard coagulation sedimentation method.

  The stirring and mixing apparatus according to the present invention will be described in detail based on the embodiments. The present invention is not limited to the following embodiment.

  FIG. 1 is a configuration diagram of a precipitation tank equipped with a stirring and mixing apparatus according to the present invention, FIG. 2 is a schematic elevation view of the stirring and mixing apparatus according to the present invention, and FIG. 3 is a plan view of the stirring and mixing apparatus according to the present invention. . The settling tank 1 is equipped with the stirring and mixing apparatus 2 of the present invention. The stirring and mixing device 2 is disposed at the water surface position of the settling tank 1. More specific installation positions will be described later.

  As an outline of the processing of the sedimentation tank 1 equipped with the stirring and mixing device 2, the waste water P1 and the flocculant P2 are allowed to flow into the lower portion of the stirring and mixing device 2, and the flocculating aid P3 is introduced from the upper portion of the stirring and mixing device 2. The agglomerated sludge generated by the stirring and mixing device 2 is precipitated at the lower part of the settling tank 1. Then, the precipitated sludge is scraped to the center of the sedimentation tank 1 by the sludge scraper 3, extracted from the bottom of the sedimentation tank 1, and transferred to the outside by the sludge extraction pump 4. On the other hand, the clear treated water separated from the sludge overflows from the upper part of the settling tank 1.

Next, a specific configuration of the stirring and mixing apparatus 2 will be described.
The stirring and mixing device 2 has a cylindrical container 21. The cylindrical container 21 is closed at the lower part and opened at the upper part, and a stirring member 23 is provided therein. The stirring member 23 is driven by a motor 24. On the outside of the cylindrical container 21, an outer cylinder 22 that is open at both the upper and lower portions is provided. The outer cylinder 22 is disposed so as to be concentric with the cylindrical container 21.

  A mounting plate 25 for mounting the motor 24 is disposed above the cylindrical container 21 and the outer cylinder 22. A bracket 41 a is formed on the lower surface of the mounting plate 25, the lower end portion of the support member 42 a is fixed to the outer cylinder 22, and the outer cylinder 22 is fixed to the mounting plate 25. The cylindrical container 21 is also fixed to the mounting plate 25 by a bracket 41b and a support member 42b, like the outer cylinder 22. Further, the upper end portion of the cylindrical container 21 is located below the upper end portion of the outer cylinder 22. A cutout portion 35 is formed in the upper peripheral edge of the cylindrical container 21. The cutout portion 35 functions to regulate the overflow position when the mixed liquid mixed and stirred inside the cylindrical container 21 overflows the outer cylinder 22. A dropping nozzle 50 for dropping the agglomeration aid P3 toward the notch portion 35 is disposed immediately above the notch portion 35.

  An inflow pipe 51 through which the waste water P1 and the flocculant P2 flow into the cylindrical container 21 is connected to the lower part of the cylindrical container 21 by piping.

  Here, the installation position of the stirring and mixing apparatus 2 will be described. In the present embodiment, as shown in FIG. 2, the stirring and mixing device 2 is installed in the settling tank 1 so that the bottom surface position of the cutout portion 35 and the water surface position L1 of the settling tank 1 are equal. The present invention is not limited to this, and the stirring and mixing device 2 is installed such that the water surface position L1 of the settling tank 1 exists in the range from the bottom surface 35a to the top surface 35b of the cutout portion 35 of the cylindrical container 21. Just do it. In this way, when the water surface position L1 of the sedimentation tank 1 is below the bottom surface 35a of the cutout portion 35 of the cylindrical container 21, the stirred mixed liquid overflowing from the cylindrical container 21 is cylindrical. The process of forming a downward flow while gently swirling between the cylindrical container 21 and the outer cylinder 22 is caused by dropping to the water surface below the bottom surface 35a of the cutout portion 35 of the cylindrical container 21. This is because it becomes impossible to efficiently grow flocs of the coagulated sludge. On the other hand, when the water surface position L1 of the settling tank 1 is above the upper surface 35b of the cutout portion 35 of the cylindrical container 21, the stirred mixed solution cannot inherently overflow from the cylindrical container 21. is there.

Next, the treatment in the precipitation tank 1 equipped with the stirring and mixing device 2 having the above-described configuration will be described in detail.
The waste water P1 and the flocculant P2 are injected into the lower part of the cylindrical container 21. Thereby, in the cylindrical container 21, waste water P1 and the flocculant P2 contact, and it stir-reacts and produces | generates coagulated sludge. And the liquid mixture containing this coagulated sludge flows into the outer cylinder 22 side over the notch part 35. At this time, since the aggregation assistant P3 is configured to be dropped into the notch 35, the contact efficiency between the mixed solution and the aggregation assistant P3 is improved. Moreover, since the flow by the stirring member 23 is a downward flow and the inflow of the waste water P1 is in the lower part of the cylindrical container 21, the flow of the waste water is an upward flow. As a result, the downward flow and the upward flow collide with each other and the turbulent flow occurs. Thus, the contact efficiency between the waste water P1 and the flocculant P2 in the cylindrical container 21 is improved, and the generation efficiency of the coagulated sludge is improved. In addition, the contact time is ensured in the upward flow portion from the strong stirring portion to the overflow portion, and stirring and mixing are further promoted by rising while swirling and mixing.

  Next, the stirred mixed liquid rising while swirling and mixing in the cylindrical container 21 flows into the outer cylinder 22 side beyond the notch 35. At this time, since the coagulation aid P3 is dropped into the cutout portion 35, the agitated mixed liquid that has flowed into contact with the coagulation aid P3, and thereafter, the space between the cylindrical container 21 and the outer cylinder 22 is shown in FIG. A downward flow is formed while gently turning in the circumferential direction K1. Thereby, flocs of coagulated sludge grow.

  Thus, the stirring and mixing efficiency is improved and the residence time can be shortened, so that the volume of the apparatus can be reduced.

  Moreover, the cylindrical container which fulfills the function of stirring and mixing the waste water and the flocculant corresponds to a conventional mixing tank. The outer cylinder that functions to form a space for growing flocs of the coagulated sludge corresponds to the conventional coagulation tank. Therefore, although having a single structure of one tank, it has the function of a conventional mixing tank and the function of a coagulation tank, so that a process composed of three tanks, a mixing tank, a coagulation tank, and a coagulation sedimentation tank, is one tank. Can only be simplified. That is, since it has a single structure, the number of equipment including a stirrer and the number of water tanks can be reduced and facilities can be simplified compared to the conventional example.

(Experimental example)
The volume of the cylindrical chamber 21 was operated under the conditions of waste water inflow 110m ³ / d using the apparatus of 0.032 ^3. As a result, coagulated sludge and treated water having the same properties as the standard coagulation sedimentation method described in the background art were obtained. The residence time under these conditions was 0.42 minutes, and it was confirmed that the residence time can be significantly shortened compared to the standard residence time of 5 minutes.

(Other matters)
(1) In the above embodiment, the apparatus for stirring and mixing the waste water and the flocculant has been described. However, the stirring and mixing apparatus 2 according to the present invention also applies to the apparatus for stirring and mixing the raw water P4 and the pH adjuster P5 shown in FIG. Applicable. That is, the raw water P4 and the pH adjuster P5 are caused to flow into the bottom of the stirring and mixing device 2. In view of the pH of the raw water P4 and the target pH for pH adjustment, an alkali or an acid is used as the pH adjuster P5. It is preferable to control the input amount of the pH adjuster P5 by a measured value of a pH meter (not shown). The pH adjustment is performed in every process such as pre-treatment and post-treatment of a wastewater treatment facility.

  (2) In the above embodiment, the apparatus for stirring and mixing the waste water and the flocculant has been described. However, the stirring and mixing apparatus 2 according to the present invention is also applicable to the apparatus for stirring and mixing the raw water P4 and the powdered activated carbon P6 shown in FIG. it can. That is, the raw water P4 and the powder activity P6 are caused to flow into the bottom of the stirring and mixing apparatus 2. Powdered activated carbon may be charged in a dry state, but if it is suspended in water in a separate water tank in advance and charged with a pump, labor can be saved. The raw water P4 and the powdered activated carbon P6 come into contact with each other in the stirring and mixing device 2 and flow out as treated water. Thereafter, the treated water and the powdered activated carbon P6 are separated as necessary. Since the powdered activated carbon P6 can adsorb soluble organic substances and chromaticity components in the raw water P4, it can be carried out in a desired process of a wastewater treatment facility.

  The present invention relates to an agitation and mixing device for use in wastewater treatment facilities such as human waste treatment plants, sewage treatment plants, and landfill leachate treatment facilities to add coagulant to waste water to generate agglomerated sludge, and the agitation and mixing device. It can be applied to the settling tank provided.

21: Cylindrical container 22: Outer cylinder 23: Stirring member 24: Motor 25: Mounting plate 35: Notch portion 35a: Upper surface of the notch portion 35b: Bottom surface of the notch portion 35

Claims (4)

A stirring and mixing device for stirring and mixing water to be treated and a treatment agent,
A cylindrical container with a closed bottom and an open top;
A pipe connected to a lower portion of the cylindrical container, an inflow pipe for allowing the water to be treated and the treatment agent to flow into the cylindrical container, and a stirring means for generating a downward flow inside the cylindrical container;
With
The water to be treated and the treatment agent are agitated in a strong stirring part formed by the water to be treated that has flowed into the cylindrical container through the inflow pipe and the upward flow of the treatment agent and the downward flow by the stirring means. An agitation and mixing apparatus characterized by mixing.   The stirring and mixing apparatus according to claim 1, wherein the water to be treated is waste water, and the treatment agent is a flocculant.   An outer cylinder that is concentrically formed with the cylindrical container and that is open at the top and bottom is provided outside the cylindrical container, and a notch is formed in the upper peripheral edge of the cylindrical container. 3. The agitation / mixing device according to claim 2, further comprising an agglomeration aid addition means for adding the agglomeration aid to a water surface portion where the agitation mixed solution flows from the portion to the outer cylinder. A precipitation tank comprising the stirring and mixing device according to claim 3,
The settling tank, wherein the settling apparatus is installed so that a water surface position of the settling tank exists in a range from a top surface to a bottom surface of the cutout portion of the cylindrical container constituting the stirring and mixing apparatus.

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