JPH07136681A - Batch type waste water treatment apparatus - Google Patents

Abstract

PURPOSE:To improve treatment capacity by increasing the concentration of microorganisms in a treatment tank and facilitate the discharge of only supernatant by feeding a large number of fluid type carriers which float freely with waste water in the course of aeration and precipitate with sludge in the course of precipitation into the treatment tank. CONSTITUTION:A large number of carriers 5 which have a specific gravity of 1.01-1.04 including microorganisms deposited and are sponge with open pores of 60-700mum diameter and of a size of 5-15mm are fed into a treatment tank 1. In an aeration process, a whirlpool is produced by aeration air from an aerator 2, and the carriers float freely in treated water 6. Since the carriers 5 are suitable for microorganisms to adhere and propagate on them, a high efficiency of purification can be attained while the concentration of microorganisms in the treatment tank 1 being increased. The formation of an anaerobic area in the carrier 5 enables nitration and denitrification even in the course of aeration. In the precipetation process, the carriers precipitate with sludge so that the separation between supernatant 5a and sludge 7 can be carried out efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement for improving the treatment capacity of a batch type sewage treatment apparatus provided with a carrier for microorganisms in a treatment tank or with a draft tube for promoting a swirling flow.

[0002]

2. Description of the Related Art It is well known that a batch type sewage treatment apparatus is provided with a carrier carrying a microbial group capable of decomposing sewage in a treatment tank. Generally, a relatively large carrier is fixed in the treatment tank. , To which microorganisms adhere and propagate (see, for example, Japanese Patent Application Laid-Open No. 3-284
397). In addition, an air diffuser is provided in the processing tank,
It is also common to eject fine bubbles during the aeration process to promote the reaction and to perform mixing and stirring in the treatment tank by utilizing the upward flow of bubbles to further promote this upward flow. A method using a draft tube is also well known.

[0003]

Generally, in order to increase the treatment capacity of the wastewater treatment apparatus, it is desirable to increase the total volume of the carrier and increase the concentration of microorganisms in the treatment tank. However, in the conventional device, since the carrier fixed in the treatment tank hinders the flow of the treated water, it is not possible to obtain good results simply by enlarging the carrier. It was necessary to design with due consideration to the layout of the.

Further, when the batch type treatment is carried out using an ordinary draft tube type treatment tank, when the sludge and the treated water are separated in the sedimentation step, the supernatant water is discharged from the outside or the inside of the draft tube. After the water level drops below the upper end of the draft tube, as the discharge progresses, clear water and sludge will bypass the lower part of the tube and move to the discharge side, increasing the sludge interface on the discharge side. The sludge is caught before the discharge of the supernatant water is completed and is discharged together with the supernatant water. Therefore, it is difficult to improve the processing capacity by using the draft tube in the batch system in which the batch processing is performed using the same processing tank.

The present invention has been made for the purpose of solving the problems in the prior art and improving the treatment capacity of the batch type sewage treatment apparatus.

[0006]

In order to achieve the above object, the batch type sewage treatment apparatus of the first invention is a granular type which freely floats and moves with sewage during the aeration step and precipitates with sludge during the settling step. Alternatively, a fluid type carrier having a lump shape or a shape similar to this is used, and a large number of this carrier is put into the processing tank.

Since this carrier is used repeatedly, an outflow prevention means is provided to prevent the carrier from being discharged together with the sludge during the discharging process. As the outflow prevention means, for example, a screen is provided in a sludge discharge pipe, or a treatment tank is divided into a floating chamber in which a carrier can freely float and move and a sludge discharge chamber in which activated sludge can flow but a carrier cannot flow. There are partition walls for carrier separation.

In the batch type sewage treatment apparatus of the second invention, the draft tube for guiding the aeration air jetted from the air diffuser to the water surface of the sewage to promote the swirling flow is provided in the treatment tank, and the draft tube A plurality of small-diameter communicating holes that penetrate the inside and outside are formed on the wall surface. In the device provided with this draft tube, the flow type carrier in the first invention can be used, or the draft tube can be provided with a heating means.

[0009]

Since the carrier is a fluid type in which the carrier can freely float and move together with the sewage, the flow in the treatment tank is not obstructed, and it becomes easy to increase the amount of the carrier input and increase the concentration of microorganisms in the treatment tank. Further, since the carrier precipitates together with the sludge and separates from the supernatant water, it is easy to discharge only the supernatant water even if the microorganism concentration is high, and the carrier is prevented from being extracted together with the excess sludge by the outflow preventing means.

Further, the draft tube can efficiently generate the swirling flow by the aeration air, and the supernatant water can be moved through the communication hole of the wall surface after the precipitation, so that the sludge interface on the discharge side rises when the supernatant water is discharged. Never do
No sludge entrainment occurs. Further, the heating means prevents a decrease in processing capacity during cold weather.

[0011]

1 to 3 show a first embodiment corresponding to claims 1 and 3.
1 is a sectional view, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 shows a main part of a float-type treated water withdrawing device which is a supernatant discharge means. It is a figure. In the figure, 1 is a treatment tank, 2 is an aeration device which is an aeration means, 3 is a treated water drawing device which is a supernatant discharging means, 4 is a sludge drawing pipe which is a sludge discharging means, 5 is a fluid type carrier, 6 Is a treated water, 7 is a sludge, and 8 is a treated water inflow pipe. In addition, in FIG. 1, when the carrier 5 is precipitated with the sludge 7, the separated supernatant water 6a has a maximum water level (HWL) and a minimum water level (LW).
L) both are shown.

The aeration device 2 is arranged at the bottom of the processing tank 1 and has a large number of small holes so that the high pressure air supplied through the air supply pipe 2a is ejected into the processing tank 1 as aeration air. Has become. The treated water drawing device 3 is adapted to discharge the supernatant water 6a through the float 3a, the movable pipe 3b and the drawing pipe 3c, and the float 3a moves up and down according to the fluctuation of the water level to draw the supernatant water 6a. . Figure 3
As shown in FIG. 3, the movable tube 3b has a structure in which a T-shaped member 3d provided at the base thereof is rotatably supported by a mounting stay 3e, and a pull-out tube 3c is connected to one mounting stay 3e. .. 3f is a lid and 3g is a seal.

The sludge drawing pipe 4 is arranged in the lower part of the treatment tank 1, and a screen 9a is attached to the opening as an outflow preventing means. As the screen 9a, for example, a mesh screen in which a punching metal is cap-shaped is used, and the size of the mesh is set to, for example, 3 mm width so that the carrier 5 does not pass through.

As a carrier for supporting microorganisms used in this type of sewage treatment apparatus, microorganisms are easily adhered and the adhered area is large, the carrier itself is stable and less deteriorated, and the fluidity is good. In general, properties such as excellent wear resistance are required. This invention is intended for batch type treatment, and because it has a feature such as a higher withdrawal speed compared to the continuous type because it is a precipitation process in a completely static state and the treated water is withdrawn in a short time. In addition to the above, in addition to the above, it is possible to freely float and move on the water flow by aeration air during the aeration process, settle with sludge in the precipitation process, and be discharged together with sludge during sludge discharge In addition, it is also necessary to form an anaerobic area inside and efficiently remove nitrogen.

According to the research conducted by the present inventors, the specific gravity is about 1.01 to 1.04 when the microorganisms are attached, and the pore size is 60 to
It was confirmed that such a condition can be satisfied with a small piece having a sponge shape having a continuous hole of 700 μm and an outer dimension of 5 to 15 mm. Therefore, in the embodiment, for example, a cubic, rectangular parallelepiped, or spherical piece of urethane sponge, polyvinyl alcohol sponge, or the like, which satisfies the above conditions, is used as the carrier 5, and a large number of carriers 5 are put into the processing tank 1.

The apparatus of the embodiment is constructed as described above,
The treated water 6 is caused to flow into the treatment tank 1 in the inflow process, the treated water 6 is purified by the activity of microorganisms in the aeration process, the sludge 7 is precipitated in the precipitation process to separate the supernatant water 6a, and the supernatant water is discharged in the discharge process. The operation of discharging 6a and discharging the surplus of the sludge 7 as necessary is performed in the same manner as in the normal batch system.

Here, in the aeration step described above, a swirling flow as illustrated by an arrow in FIG. 2 is generated by the aeration air ejected from the aeration device 2. In the embodiment, however, the carrier 5 is treated water 6
Since it also floats freely, even if a large number of carriers 5 are put into the processing tank 1, the movement itself is not hindered by the speed of the swirling flow being slightly slowed down. Moreover, the carrier 5
Is suitable for adhering and propagating microorganisms, the concentration of microorganisms in the treatment tank 1 can be increased and purification can be efficiently and stably performed, and high-load treatment becomes easy. Further, since the sludge retention area is less likely to occur, the design of the treatment tank 1 becomes easy. Furthermore, since an anaerobic area is formed inside the carrier 5, nitrification and denitrification will proceed even during aeration, and the generation of excess sludge will be reduced.

Further, in the precipitation step, the carrier 5 precipitates together with the sludge 7, so that the supernatant water 6a and the sludge 7 are mixed even if the microorganism concentration is high.
And are easily separated. Therefore, in the discharging step, only the supernatant water 6a can be efficiently discharged by the treated water drawing device 3, and the carrier 5 is not discharged together with the supernatant water 6a. Further, since the carrier 9 is prevented from passing through the screen 9a attached to the sludge drawing pipe 4, the carrier 5 is not discharged together with the sludge 7 when the excess sludge is discharged in the discharging step.

As described above, it is possible to prevent the carrier 5 from being discharged together with the sludge 7 by attaching the screen 9a to the sludge extraction pipe 4. However, when the viscosity of the sludge to be extracted is high, the screen 9a can be prevented. Even if the mesh is smaller than the size of the carrier 5, the carrier 5 is more likely to be extracted together with the sludge 7 unless the drawing speed is extremely reduced. However, in the case of drawing by a pump or drawing using a head difference, the drawing speed is extremely reduced and the carrier 5
It is difficult to prevent the discharge of

Claim 4 solves such a problem, and FIG. 4 shows an embodiment corresponding to this. That is, in the figure, 9b is a carrier separating partition wall as an outflow preventing means, which is formed by using a flat plate-shaped member such as a perforated steel plate or a mesh screen. The carrier separating partition 9b is arranged in a portion near the opening 4a of the sludge drawing pipe 4 in a state of partitioning the inside of the treatment tank 1. The carrier separating partition 9b has a relatively small capacity on the sludge drawing pipe 4 side. The sludge discharge chamber 1a and the large-capacity floating chamber 1b are formed on the opposite side, and the carrier 5 is put into the floating chamber 1b. The holes, meshes, or comb-shaped gaps in the partition wall 9b for separating the carrier are smaller than the outer dimensions of the carrier 5, and the size is such that the carrier 5 cannot pass through in a normal state.

Therefore, in the aeration process, the sludge 7 can also flow into the sludge discharge chamber 1a, but the carrier 5 cannot be flowed into the sludge discharge chamber 1a because it is blocked by the partition wall 9b for carrier separation, and floats in the floating chamber 1b. It will only be done. Further, since only the sludge 7 is deposited on the bottom of the sludge discharge chamber 1a in the sedimentation step, it is sufficient to pull it out from the sludge withdrawal pipe 4, and the carrier 5 is not simultaneously withdrawn.

FIG. 4 shows an example in which a partition 9b for separating a carrier is provided inside the treatment tank 1 of FIG. 1 to divide it into a sludge discharge chamber 1a and a floating chamber 1b. Other structures such as forming the sludge discharge chamber 1a and providing a carrier separating partition wall 9b therebetween can be adopted. Also,
The carrier separating partition wall 9b is preferably movable in the vertical direction so that it can be easily removed during inspection or cleaning. For example, a guide groove or the like is provided on the wall surface of the processing tank 1 and inserted from above. It is possible to adopt a structure such as Further, a scraping board for filth having an appropriate structure may be added so that the clogging can be removed if necessary.

FIG. 5 shows an embodiment of the second invention corresponding to claim 5, and the same portions as those in FIG. 1 are designated by the same reference numerals.
The precipitation state is shown in accordance with. The treatment tank 1 of this embodiment is different from that of FIG. 1 in the shape of a pot having a circular cross section, and a fixed drawing pipe is used as the treated water drawing device 3. The sludge drawing pipe 4 is not shown.

In the figure, 11 is a draft tube, the lower end of which is lower than the sludge interface 7a at the time of sedimentation and the upper end of which is lower than the maximum water level so as not to hinder the flow of the treated water 6. It is attached by a support member 12 having a different shape so as to be located in the central portion of the processing tank 1, that is, directly above the aeration device 2. Reference numeral 11a denotes a small-diameter communicating hole formed by communicating the inside and outside with the wall surface of the draft tube 11, and a plurality of communicating holes 11a are provided at least at a portion above the minimum water level.

In such a structure, when aeration air is ejected from the aeration device 2 in the aeration step, the swirling flow as shown by the arrow in the figure caused by the upward flow due to the bubbles is promoted by the draft tube 11 and the microorganisms are aerated. Purification of the treated water 6 by the activity is promoted. After that, as shown in the drawing, the sludge 7 is precipitated and separated from the supernatant water 6a in the precipitation step, so the supernatant water 6a is discharged until the water level becomes the minimum water level in the discharge step. Since the inner clear water 6a can move to the outside through the communication hole 11a, the position of the sludge interface 7a does not change, and as a result, the clear water 6a
The sludge 7 is not caught and discharged during the discharge of a, and only the supernatant water 6a can be discharged without any trouble. The drawing tube of the treated water drawing device 3 may be provided inside the draft tube 11.

In the draft tube type apparatus as described above, the fluid type carrier 5 of the first invention can be used. 6 and 7 show a corresponding embodiment of claim 6 in which a large number of carriers 5 are put in the processing tank 1. Here, a swirling flow is generated by the bubbles ejected from the aeration device 2 as shown by the arrow in FIG. 6, and when a large number of carriers 5 are introduced, the swirling flow speed tends to be slightly slowed down. The decrease is compensated by the action of the draft tube 11, the mixing and stirring in the processing tank 1 is promoted, and the purifying action is efficiently performed. In this embodiment, the sludge drawing pipe 4 having the screen 9a is used, and the sludge 7 separated from the supernatant water 6a and precipitated as shown in FIG.
It is possible to prevent the carrier 5 from being simultaneously withdrawn when the sludge withdrawing pipe 4 is withdrawn.

By the way, it is known that in this type of apparatus, the processing capacity at the time of cold is lowered, but at about 15 ° C. or lower, the nitrogen removal rate becomes particularly remarkable. 8 and 9
In order to prevent the deterioration of the capacity during cold weather, the draft tube 11 in FIG. 5 is provided with a heating means.

That is, 13 is a hot water pipe spirally wound around the outer periphery of the draft tube 11 and fixed, 14 is a hot water supply part, and hot water is circulated through the hot water pipe 13 to heat the treated water 6 as necessary. You can do it. The hot water supply unit 14 is, for example, an electric heater 14a, a circulation pump 1
In addition to 4b and the tank 14c, a control unit (not shown) and the like are provided, but an appropriate heating method other than the one shown, such as heat exchange with the draft tube 11 itself as a heating element, may be adopted.

By providing such a heating means, it is possible to prevent the performance from deteriorating in cold weather and maintain a predetermined function. In particular, by providing the hot water pipe 13 which is a heat exchanger on the wall surface of the draft tube 11 as in this embodiment, the movement of the swirling flow is hardly disturbed by the heating means, and rather the draft tube 11 is rather prevented.
By the action of, the movement of the swirling flow is promoted and the flow velocity increases, so that the heat transfer rate increases and the heat exchange action is promoted. Therefore, the heat exchanger portion such as the hot water pipe 13 need only be small, and the cost of the entire device can be reduced.

Although FIGS. 8 and 9 show examples in which the carrier 5 is not used, the treatment capacity can be improved by using the fluid carrier 5 as in the other embodiments. .

[0031]

As is apparent from the above description, the batch-type wastewater treatment apparatus of the first invention has a flow type carrier that freely floats and moves with sewage during the aeration process and precipitates with sludge during the precipitation process. It is designed such that a large number of them are put into the processing tank.

Therefore, the carrier freely floats and does not hinder the flow in the treatment tank, so that a large amount of the carrier can be added and the concentration of microorganisms in the treatment tank can be increased to improve the treatment capacity. . In addition, since the carrier precipitates together with the sludge and separates from the supernatant water, it becomes easy to discharge only the supernatant water even if the concentration of microorganisms is high, and by providing a carrier outflow prevention means, it prevents outflow when pulling out excess sludge. The carrier can be used repeatedly.

In the second invention, a draft tube for guiding the aeration air ejected from the air diffuser to the surface of the sewage to promote a swirling flow is provided, and a plurality of communication passages penetrating the inside and the outside of the draft tube are provided. A hole is formed.

Therefore, since the supernatant water can be moved through the communication hole of the wall surface during the discharge of the supernatant water after the precipitation, the sludge is not caught and the swirl flow can be efficiently generated. It becomes easy to adopt it in the apparatus of the type, and it is possible to obtain the batch type waste water treatment apparatus having a high treatment capacity. Further, by using a fluid type carrier, the processing capacity can be further improved, and in the case where a heating means is further provided, it is possible to prevent a decrease in the nitrogen removal rate during cold weather and maintain a predetermined processing capacity. Is possible.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the structure of an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cutaway front view of a main part of the treated water drawing device of the embodiment.

FIG. 4 is a schematic cross-sectional view showing the configuration of another embodiment.

FIG. 5 is a schematic cross-sectional view showing the configuration of still another embodiment.

FIG. 6 is a schematic cross-sectional view showing the configuration of another embodiment.

FIG. 7 is a schematic cross-sectional view showing a state after precipitation of the example.

FIG. 8 is a schematic diagram showing the configuration of yet another embodiment.

FIG. 9 is a sectional view of an essential part of the embodiment.

[Explanation of symbols]

 1 Treatment Tank 1a Sludge Discharge Chamber 1b Floating Chamber 2 Aeration Device 3 Treated Water Extraction Device 4 Sludge Extraction Pipe 5 Carrier 6 Treated Water 6a Clear Water 7 Sludge 8 Treated Water Inlet Pipe 9a Screen 9b Carrier Separation Partition 11 Draft Tube 11a Communication Hole 13 Hot water piping

Claims (7)

[Claims] 1. A diffusing means for ejecting air into the treatment tank during the aeration step, a supernatant discharging means for discharging supernatant water and a sludge discharging means for discharging sludge during the discharging step after the precipitation step. A batch-type sewage treatment apparatus, in which a large number of granular or lumpy or similar microbial carriers that float freely with sewage during the aeration process and precipitate with sludge in the sedimentation process are put into the treatment tank. A batch type sewage treatment device characterized by the above. 2. The batch type sewage treatment apparatus according to claim 1, further comprising outflow prevention means for preventing the carrier from being discharged together with the sludge by the sludge discharge means. 3. The batch type sewage treatment apparatus according to claim 2, wherein the outflow prevention means is a screen provided on the discharge pipe of the sludge discharge means. 4. The outflow prevention means is a carrier separating partition that divides the treatment tank into a floating chamber in which the carrier can freely float and move and a sludge discharge chamber in which the activated sludge can flow but the carrier cannot flow. Item 2. The batch type sewage treatment apparatus according to item 2. 5. An air diffuser for ejecting air into the treatment tank during the aeration step, a supernatant discharge means for discharging supernatant water and a sludge discharge means for discharging sludge during the discharging step after the precipitation step. A batch type sewage treatment apparatus, in which a draft tube that guides aeration air ejected from an air diffuser to the surface of the sewage to promote a swirling flow is provided inside the treatment tank, and the inside and outside of the draft tube penetrate through the wall. A batch-type sewage treatment apparatus having a plurality of communication holes formed therein. 6. The treatment tank is mixed with a large number of granular or lumpy or similar microbial carriers that freely float and move with sewage during the aeration step and precipitate with sludge during the precipitation step. Batch type sewage treatment equipment. 7. The batch type sewage treatment apparatus according to claim 5, wherein the draft tube is provided with a heating means.