JPH0952096A - Aeration tank for purifying treatment of sewage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aeration tank capable of performing effective purifying treatment to a degree capable of reutilizing treated watder as washing water within a short time when sewage such as waste washing water is purified using bacteria (lactic acid bacteria, yeast, actinomyces, photosynthetic bacteria or filamentous fungi). SOLUTION: Almost semispherical projections with a height of 10-30mm are formed to the vertical inner wall surfaces 6, 7 of a container housing mixed sewage of sewage to be treated and bacteria at random and an air diffusing pipe 2 is arranged to the bottom part of the container and vertical revolving streams 5 are generated in the mixed sewage in the container by air bubbles diffused from the air diffusing pipe to bring mixed sewage revolving streams into contact with the projections on the vertical inner wall surfaces of the container. In order to effectively generate revolving streams, the bottom part of the container is formed so as to have a circular arc bottom surface 9 and a cylindrical guide means 10 is horizontally arranged to the center of the container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sewage capable of effectively performing biological purification when biological sewage such as laundry wastewater is brought into contact with microorganisms under aeration to biologically purify it. The present invention relates to an aeration tank for purification.

[0002]

2. Description of the Related Art As a method for biologically purifying wastewater, an activated sludge method has been widely used. This method introduces activated sludge, which consists of aggregates of suspended solids, organic matter, bacteria, and protozoa in water, into the aeration tank and contacts it with aeration in an aerated state to decompose organic matter in the wastewater and reduce BOD. Let Sludge containing activated sludge is led to a sedimentation basin or sedimentation tank to settle and remove the activated sludge, the supernatant water is discharged, and part of the settled sludge is returned to the aeration tank to maintain a constant concentration of the activated sludge in the aeration tank. I do.

[0003]

The above-mentioned activated sludge method has an advantage of decomposing organic matter in the sewage to obtain treated water having a low BOD. However, the activated sludge grows during the purification treatment, resulting in excess surplus. Sludge is generated and its disposal becomes a problem.

Furthermore, when the treated wastewater is purified by the activated sludge method and the treated water is reused as the washing water, the activated sludge is black, and even if a trace amount remains in the treated water, it is washed. When used as water, there was a problem that the laundry darkened.

Therefore, the present inventors have studied a method of biologically purifying laundry wastewater and reusing the treated water as laundry water. As a result, lactic acid bacteria, yeasts and actinomycetes have been used without using activated sludge. It was found that purified treated water that can be reused as wash water can be obtained by contacting one or more microorganisms selected from bacteria, photosynthetic bacteria, filamentous fungi, etc. with laundry wastewater under aeration conditions.

However, when carrying out the above method of purifying laundry wastewater by using a predetermined microorganism, if an aeration tank conventionally used in the activated sludge method is used, flocs are contained in the laundry wastewater in the aeration layer. The formation of (degradation products of pollutants with microorganisms attached and grown) is not effectively performed, and the flocs are formed only to the extent that small flocs float in the washing wastewater, and the washing wastewater is discharged from the aeration tank. At the same time, as a result of the outflow of microorganisms, there is a problem that the purification treatment takes time and the desired biological purification treatment cannot be efficiently performed.

Therefore, the present invention solves the above-mentioned problems that occur when an aeration tank which has been conventionally used is used, and when the washing wastewater is purified using microorganisms, the treated water is reused as washing water. The purpose of the present invention is to provide an aeration tank capable of performing an effective purification treatment in a short time so that it can be used.

[0008]

That is, in the aeration tank for purifying sewage of the present invention, approximately semi-spherical projections are randomly formed on the inner wall surface in the longitudinal direction of the container for storing the mixed sewage of sewage and microorganisms to be treated. Then, an air diffuser is arranged at the bottom of the container, and a vertical swirl flow is generated in the mixed wastewater in the container by the air bubbles diffused from the air diffuser, and the swirl flow of the mixed wastewater is generated on the protrusions on the vertical inner wall surface of the container. The feature is that they are brought into contact with each other.

According to the present invention, a centrifugal action is generated in the vertical swirling flow of the mixed sewage in the container, which swirls while violently colliding with the protrusion formed on the inner wall surface of the container. When the mixed sewage collides with the protrusions, contaminants such as organic substances and suspended matter in the sewage are crushed, are easily affected by microorganisms, and decomposition by microorganisms is promoted. In addition, decomposed pollutants and microorganisms adhere and grow on the downstream side of the swirling flow of the projections to form flocs, and these flocs serve as settlement sites for microorganisms. The flocs formed on the protrusions on the inner wall surface of the container become less likely to flow out as the waste water is discharged from the aeration tank, and as a result of staying in the aeration tank, it effectively acts on the biological purification treatment in the aeration tank. It will be.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 show an embodiment of the aeration tank of the present invention, and are a perspective view and a front sectional view in which one of the tank walls in the vertical direction is cut away. The container 1 of the aeration tank has a quadrangular prism shape, an air diffuser pipe 2 is arranged at the bottom of the container 1, and air is blown from a blower 3 installed outside the tank through the air diffuser pipe 2 into the tank. 4 (a mixed wastewater of laundry wastewater and microorganisms) is diffused, and a vertical swirl flow 5 is generated in the mixed wastewater in the container by the bubbles released from the air diffuser 2 (see FIG. 2).

A large number of substantially hemispherical projections 8 are formed on a pair of vertical inner wall surfaces 6 and 7 facing each other against which a vertical swirling flow strikes. The shape of the protrusion 8 is preferably a hemisphere as shown in FIG. 3, but it does not necessarily have to be a true hemisphere.
The tip of the protrusion may be sharply sharpened or gently sharpened. In the present specification, the term “substantially hemispherical” is used to include all of these shapes. The projection height from the inner wall surface of the projection 8 (h in FIG. 3), that is, the radius of the substantially hemispherical sphere is such that the volume of the aeration tank container is 40 to 3000 L.
It has been found from various experiments that the swirling flow 5 and the projection 8 can be effectively contacted with each other by setting the thickness to about 10 to 30 mm in the case of (liter). However,
In a large aeration tank, it may be possible to make more effective contact by making the height of the protrusions 8 higher than this.

The projections 8 are arranged in such a manner that they are not aligned in a straight line in the vertical and horizontal directions of the inner wall surfaces 6, 7.
Arrange randomly. When arranged in a straight line, swirling flow 5
And the protrusions 8 are not effectively contacted with each other. In order to make the swirl flow and the respective projections contact each other efficiently, it is desirable to form the projections in a zigzag shape in which the vertical straight line is gradually divided left and right.

If the number of the projections 8 is too large, the contact with the swirling flow will not be effectively made. Preferably, the total area of formation of the protrusions 8 is 35 to 50 with respect to the area of the entire plane portion of the wall surfaces 6 and 7 where the protrusions 8 are to be formed.
%, In other words, the area of the portion where the projection 8 is not formed is 65 to 5 of the total area of the wall surfaces 6 and 7.
Protrusions are provided in such a number as to be about 50%.

In the illustrated example, a pair of opposing inner wall surfaces 6 and 7 on which the projection 8 is formed are connected by an arcuate bottom surface 9. This makes it possible to smoothly swirl the vertical swirling flow 5 in the container and prevent suspension from accumulating at the bottom of the container.

In order to surely generate the vertical swirl flow 5, the air diffuser 2 is arranged near one of the opposing inner wall surfaces 6 along the inner wall surface 6, and further, the swirl flow 5 is provided. It is desirable to arrange the guiding means in the container 1. As the guiding means, a cylinder 10 as shown in FIGS.
Is preferably arranged horizontally in the middle of the opposing inner wall surfaces 6 and 7 on which the projections are formed, so that the swirl flow 5 can be more effectively given a centrifugal action. The diameter of the cylinder 10 is preferably in the range of 30 to 40% of the distance between the opposing inner wall surfaces 6 and 7 (width of the container 1). As a guide means for the swirling flow 5, a baffle plate composed of a flat plate 11 as shown in FIG. 4 may be arranged vertically at a distance from the inner wall surface 6 near the air diffuser 2.

FIG. 5 shows still another embodiment of the aeration tank according to the present invention, in which a pair of vertical inner wall surfaces 6 facing each other.
The structure in which the protrusion 8 is formed on the protrusion 7 and the vertically mixed sewage swirl flow 5 is brought into contact with the protrusion 8 is the same as that of the embodiment of FIGS. In the embodiment shown in FIG. 5, a submersible pump 12 is further arranged at the bottom of the container so that the discharge pipe 13 of this pump is projected above the water surface in the container and the outlet opening 13a of the discharge pipe is directed downward. There is. The height of the discharge pipe outlet opening 13a from the water surface is preferably at least 30 cm or more. By having such a structure,
The submersible pump 12 sucks up the sewage in the container to above the sewage surface and recirculates the sewage to hit the sewage surface in the container to give a strong impact to the sewage, such as laundry wastewater,
The detergent component contained in the dirty water foams and is quickly decomposed. Since the floating substances in the wastewater are adsorbed by the bubbles of the detergent, the floating substances in the wastewater can be effectively separated and removed by separating the bubbles from the wastewater. Furthermore, the impact due to the recirculation makes the contact between the air and the sewage more effective, thereby improving the aeration conditions.

The effects of the present invention will be described below with reference to experimental examples. 30 L of washing wastewater was introduced into the aeration tank shown in FIGS. 1 and 2 having an aeration tank container capacity of 40 L, and a purification treatment experiment by microorganisms was conducted. The radius (height) of the semi-spherical projection 8 is 20 m
m, and the total formation area of the projections 8 was 40% with respect to the area of the flat portion of the inner wall surfaces 6 and 7. In addition, a vertical swirl flow 5 was generated in the aeration tank by blowing air from the air diffuser 2 at a blowing rate of 2.5 m ³ / min. As a microorganism, a mixture of lactic acid bacteria, actinomycetes and photosynthetic bacteria 30 m
L was added. The purification treatment was carried out at room temperature for 24 hours, and the transparency and suspended matter (SS) of the treated water were measured by the following methods.

Transparency: A mark was placed on the tip of the measure, and the measure was inserted into the treated water in the aeration tank where the treatment was completed, and the depth (cm) at which the mark at the tip of the measure was visually invisible was read by the measure. The deeper the depth, the better the transparency and the better purification treatment. Suspension (SS): According to the GFP filtration method specified in JIS K 0102 14.1.

The measurement results are shown in Tables 1 and 2. In the table, "Blank" is the washing wastewater before purification treatment; "Experiment 1" is the one in which the mixed wastewater of the washing wastewater and the microorganisms is simply put in the aeration tank and left standing; "Experiment 2" is The mixed sewage in the aeration tank with no protrusions on the inner wall was treated by causing air to diffuse from the diffuser to generate a swirling flow; "Experiment 3" was an aeration tank with protrusions on the inner wall (Fig. 1, What was processed by generating a swirling flow using 2); "Experiment 4" was to form a protrusion on the inner wall surface and to reflux and hit with a submersible pump (front lift: 8 m, discharge rate: 3 L / min) And a swirling flow is generated by using the aeration tank (FIG. 5) for performing the above.

Table 1: Transparency measurement results Blank experiment 1 experiment 2 experiment 3 experiment 4 ^* Washing wastewater ○ ○ ○ ○ ○ Microorganisms ○ ○ ○ ○ Air blowing ○ ○ ○ Protrusion formation ○ ○ Reflux / brushing ○ Transparency (cm) 4 16 27 34 51 .

Table 2: Results of measurement of suspended solids (SS) Blank experiment 1 experiment 2 experiment 3 experiment 4 ^* Washing wastewater ○ ○ ○ ○ ○ Microorganisms ○ ○ ○ ○ Air blowing ○ ○ ○ Protrusion formation ○ ○ Refluxing and hitting ○ SS (mg / L) 56 24 7.4 4.8 2.8 Note *) In Experiment 4, after the purification treatment of Experiment 3 was performed for 24 hours, the water was continuously refluxed and hammered for 3 hours. The transparency and SS were measured.

[0022]

As can be seen from the above description, according to the aeration tank of the present invention, a protrusion is formed on the inner wall surface of the aeration tank container, and the vertical swirl flow of the wastewater in the aeration tank and the mixed wastewater of microorganisms is mixed. By violently colliding the protrusion with the protrusion, the biological purification treatment can be performed more effectively. Such an aeration tank can be effectively used for efficiently performing biological purification treatment on laundry wastewater to obtain treated water that can be reused as laundry water again.

Further, by disposing the cylindrical swirling flow guide means in the tank, the sewage swirling flow in the tank can be more effectively centrifugally exerted, and the projection formed on the inner wall surface of the container and the swirling Contact and collision with the stream can be performed efficiently.

Further, a submersible pump is installed at the bottom of the aeration tank container to suck up the sewage in the container to a position above the sewage surface, discharge the sewage so that it hits the water surface, and recirculate the sewage so that the detergent component in the waste water Can be decomposed and purified more effectively, and the contact between air and sewage can be made even more effective, so that aeration conditions can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an aeration tank of the present invention.

FIG. 2 is a front sectional view of the aeration tank of FIG.

FIG. 3 is an enlarged cross-sectional view of a protrusion formed on the inner wall surface of the aeration tank.

FIG. 4 is a front sectional view showing another embodiment of the swirling flow guide means.

FIG. 5 is a front sectional view showing another embodiment of the aeration tank of the present invention.

[Explanation of symbols]

 1: Container 2: Air diffuser 4: Sewage / microorganism mixed wastewater 5: Vertical swirling flow 6,7: Opposing inner wall surface 8: Protrusion 9: Arc bottom 10: Cylindrical guide means 11: Flat guide means 12: Underwater Pump 13: Discharge pipe 13a: Discharge pipe outlet opening

Claims (11)

[Claims] 1. A substantially semi-spherical projection is randomly formed on a vertical inner wall surface of a container for storing mixed wastewater containing sewage and microorganisms to be treated, and an air diffuser is provided at the bottom of the container. Aeration for sewage purification treatment, characterized in that a swirling flow in a vertical direction is generated in the mixed sewage in the container by the bubbles that are diffused, and the swirling flow of the mixed sewage is brought into contact with the projections on the vertical inner wall surface of the container. Tank. 2. The radius of the substantially semi-spherical protrusion is 10 to 3
The aeration tank according to claim 1, which is 0 mm. 3. The container has a quadrangular prism shape, and the protrusions are formed on a pair of vertical inner wall surfaces facing each other against which a vertically mixed swirling swirl flow strikes, and the air diffusing tubes are set on the inner wall surfaces facing each other. The aeration tank according to claim 1, wherein the aeration tank is arranged in the vicinity of one of the inner wall surfaces and along the inner wall surface. 4. The aeration tank according to claim 3, wherein the pair of opposed inner wall surfaces are connected by an arcuate bottom surface. 5. The aeration tank according to claim 3, wherein a guide means for guiding the vertical swirling flow of the mixed sewage is provided inside the container. 6. The aeration tank according to claim 5, wherein the guide means is a cylinder horizontally arranged in the middle of the pair of opposed inner wall surfaces having a projection. 7. The aeration tank according to claim 6, wherein the diameter of the cylinder is 30 to 40% of the distance between the pair of opposed inner wall surfaces having the projections formed thereon. 8. The aeration tank according to claim 5, wherein the guide means is a flat plate that is vertically arranged in the vicinity of an inner wall surface in which the air diffusing pipe is arranged in the vicinity thereof and at a distance from the inner wall surface. 9. The aeration tank according to claim 1, wherein the protrusion is formed in a zigzag shape. 10. The protrusions are formed such that the total area of the protrusions is about 35 to 50% of the total area of the flat surface of the wall surface on which the protrusions are to be formed.
The aeration tank described. 11. A mixed submersible discharged from a discharge pipe opening by disposing a submersible pump at the bottom of the container, projecting the pump discharge pipe above the water surface in the container, and opening the discharge pipe downward. The aeration tank according to claim 1, wherein the air is discharged so as to be struck toward the water surface.