JPH0631295A - Sewage treatment device - Google Patents

Abstract

PURPOSE:To provide an easy-to-maintain device which prevents a denitrification bacteria or nitration bacteria-fixing cattier from flowing out of each reaction tank or from being migrated to the outflow side of each reaction tank when the carrier is charged in a denitrification tank or a nitration tank. CONSTITUTION:A partition plate 4 is vertically or obliquely installed across the entire width of each reaction tank or at a part of the width at the near side to the outflow end 2 of each reaction tank 1, and an opening 5 is provided at the lower part of the partition plate 4. Consequently, a still zone 7 for shielding against the adverse effects of fluid circulation and stirring in each tank is formed in a space between the partition plate 4 and the outflow side 2 of each tank. The maximum value of a speed at which a blend ascends in an ascending curve in the still zone 7 is set to be smaller than the minimum value of a precipitation speed of the microbe fixing carrier is each tank 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment apparatus for treating sewage, industrial wastewater and the like.

[0002]

2. Description of the Related Art Conventionally, sewage is first introduced into a denitrification tank and then into a nitrification tank, and a part of the nitrification tank mixture is circulated in the denitrification tank and the rest is introduced into a sedimentation tank. At this time, polluted organic substances such as BOD and nitrogen are removed in the denitrification tank, and Kjeldahl nitrogen containing ammonia nitrogen is oxidized to nitric acid or nitrous acid in the nitrification tank. In this process, it is a general technique to remove nitrogen by performing nitrification / denitrification with floating activated sludge.

[0003]

However, in the above-mentioned nitrogen removal technique, the total residence time in the nitrification tank and the denitrification tank is 1
It takes 2 to 16 hours, and it is not applicable to ordinary existing sewage treatment plants that are designed and operated with aeration tank residence time of 6 to 8 hours because it is difficult to secure new land. I want to.

Therefore, in order to shorten the retention time of wastewater in the reaction tank, it has been studied to increase the nitrification or denitrification rate by immobilizing nitrifying bacteria or denitrifying bacteria on the carrier. However, in order to put such a technique into practical use, when a carrier on which denitrifying bacteria or nitrifying bacteria are immobilized is introduced into a denitrifying tank or a nitrifying tank, these microorganisms-immobilized carriers do not flow out from each reaction tank, An apparatus is indispensable for remaining in each reaction tank and contributing to the nitrification or denitrification reaction. Further, from the viewpoint of facilitating maintenance management, it is necessary for this device to accumulate fiber components, dust, and the like, which are often contained in wastewater such as sewage, and to not close the openings thereof.

Further, when these microorganisms-immobilized carriers are put into each reaction tank, there is a liquid flow from each reaction tank inflow side to each outflow side. However, in an extreme case, there is almost no microorganism-immobilized carrier on the inflow side of each reaction tank, and efficient nitrification or denitrification reaction cannot be expected.
In particular, in the case of sewage, such a phenomenon is likely to occur because the amount of inflow water varies greatly over time and the amount of inflow water increases depending on the time of day.

The present invention solves the above-mentioned problems, and when a carrier on which denitrifying bacteria or nitrifying bacteria are immobilized is introduced into a denitrifying tank or a nitrifying tank, these carriers flow out from each reaction tank or each reaction It is an object of the present invention to provide a device that is not unevenly distributed on the outflow side of a tank and that is easy to maintain and manage.

[0007]

In order to solve the above problems, the sewage treatment apparatus of the present invention comprises a denitrification tank for biologically denitrifying under anoxic conditions and a biological denitrification under aerobic conditions. The nitrification tank for nitrification is arranged in this order, and a part of the nitrification-treated water is circulated to the inflow part of the denitrification tank, while the rest of the nitrification-treated water flows out through the settling tank and the sludge extracted from this settling tank. In a sewage treatment device that simultaneously removes BOD components and nitrogen in the inflowing wastewater by returning part or all of the water to the inflow part of the denitrification tank, the sedimentation property that is sufficiently fluidized in the denitrification tank A denitrifying bacterium immobilizing carrier having, and having a nitrifying bacterium immobilizing carrier having a sedimentation property that is sufficiently fluidized in a nitrification tank, and before the outflow end of each tank,
By installing the partition plate vertically or diagonally over the entire tank width or a part of it, and by providing an opening at the bottom of the partition plate, the space between the partition plate and each tank outflow end can be A static zone is provided to block the effects of liquid flow and agitation in the tank, and the maximum value of the rising linear velocity of the mixed solution in this static zone depends on the sedimentation speed of the microorganism-immobilized carrier in each tank. It is configured to be smaller than the minimum value.

Further, one or two or more further stationary zones are installed in a direction away from the outflow end with respect to the stationary zones in each tank. Furthermore, the bottom of the stationary zone in each tank is configured to have an upward slope toward the outflow side.

Further, one or a plurality of inclined plate claws having an upward slope with respect to the outflow direction of the liquid is installed at the outflow end of each tank. In addition, a screen for preventing the outflow of the microorganism-immobilized carrier was installed at the outflow end of each tank.

[0010]

In the above-mentioned structure, the partition plate is vertically or obliquely provided in front of the outflow end of the nitrification tank in which the nitrifying bacteria immobilizing carrier having a sedimentation property is introduced or the denitrification tank in which the denitrifying bacteria immobilizing carrier having a sedimentation property is introduced. Moreover, the carrier can be prevented from flowing out of the tank by arranging it over the entire tank width or a part thereof. Further, by providing an opening at the bottom of the partition plate, a stationary zone for blocking the influence of liquid flow and stirring in each tank is provided in the space between the partition plate and the outflow end of each tank.
And the maximum value of the rising linear velocity of the mixed solution in this stationary zone is
By designing to be smaller than the minimum value of the settling speed of the immobilized carrier in each tank, the microorganism-immobilized carrier beyond the partition plate surely sediments in the stationary zone. The outflow to the outside of the tank can be suppressed. On the other hand, since this static zone has a simple structure, the fiber components and dust contained in sewage and the like flow out of each reaction tank without accumulating in the static zone.

Further, when two or more static zones are installed in the nitrification tank or the denitrification tank, it is possible to avoid the problem that the microorganism-immobilized carrier is present at a high density near the outflow end in each reaction tank. It is possible, and the carrier will be present in each reaction vessel approximately evenly.

Further, since the bottom of the stationary zone in each tank has an upward slope toward the outflow side, the carrier settled in the stationary zone surely returns to each tank in a fluidized / stirred state. be able to.

Further, by providing one or a plurality of inclined plate claws having an upward slope with respect to the outflow direction of the liquid at the outflow end of each tank, the fiber content and dust can be more reliably outflowed out of each tank. Further, by installing the carrier outflow prevention screen at the outflow end of the nitrification tank or the denitrification tank, the outflow of the microorganism-immobilized carrier to the outside of each tank can be more reliably suppressed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram showing an example of a stationary zone provided in a denitrification tank as a reaction tank and a nitrification tank. Before the outflow end 2 of the reaction tank 1, the mixed liquid 3 in the reaction tank 1
The partition plate 4 is installed vertically or obliquely from the position higher than the liquid surface of the above, and over the entire tank width or a part thereof. At this time, the partition plate 4 does not come into contact with the bottom surface of the reaction tank 1 at its lower part, and accordingly, the opening 5 is formed in the lower part of the partition plate 4.
It is installed to have. FIG. 1B is the same as FIG.
It is the figure which looked at the reaction tank 1 of (a) from the outflow end 2 side. The reaction vessel 1 is charged with a microorganism-immobilized carrier 6 having a sedimentation property. As the carrier 6 for immobilizing microorganisms, a carrier for immobilizing denitrifying bacteria is used in the denitrification tank, and a carrier for immobilizing nitrifying bacteria is used in the nitrification tank. The mixed solution 3 in the tank is biologically nitrified or denitrified by flowing together with the microorganism-immobilized carrier 6 by a stirring or diffusing device.

At this time, the mixed liquid 3 is flowed from the denitrification tank toward the nitrification tank, and there is a liquid flow in the direction from the inflow side to the outflow side in each reaction tank 1. Outflow of the microorganism-immobilized carrier 6 from the tank 1 is suppressed.
Even when the microorganism-immobilized carrier 6 exceeds the partition plate 4, the maximum linear velocity of the mixed solution 3 in the stationary zone 7 is smaller than the minimum sedimentation velocity of the microorganism-immobilized carrier 6 in the tank 1. For,
The microorganism-immobilized carrier 6 does not rise in the stationary zone 7, and after falling to the bottom of the stationary zone 7, the stationary zone 7
To the inflow side of the reaction tank 1. On the other hand, the fiber components, dust, etc. 8 in the mixed liquid 3 flow out of the tank 1 together with the outflow water 9.

FIG. 2 is a view showing another embodiment of the stationary zone provided in the reaction tank. A stationary zone 7 is provided by the partition plate 4 as in FIG.
Has an upward slope. Therefore, the microorganism-immobilized carrier 6 returns from the stationary zone 7 to the inflow side of the reaction tank 1 more easily than in the case of the embodiment shown in FIG.

FIG. 3 is a view showing still another embodiment of the stationary zone provided in the reaction tank. As in the case of FIG. 1, a stationary zone 7 is provided by the partition plate 4, and an inclined bottom portion 11 is provided similarly to the bottom portion 10 of FIG. It has a slope extending beyond 4 to the inflow side of sewage. Therefore, the microorganism-immobilized carrier 6 returns from the stationary zone 7 to the inflow side of the reaction tank 1 more easily than in the case of the embodiment shown in FIG.

FIG. 4 is a view showing still another embodiment of the stationary zone provided in the reaction tank. Here, the reaction tank 1
Is divided into a plurality of sections 12 in the direction from the outflow side to the inflow side, and each of the sections 12 is provided with a stationary zone 7. Of these stationary zones 7, those located away from the outflow end are surrounded by the partition plate 4 and the partition wall 13 as shown. Although not shown in the drawing, the one provided at the outflow end is surrounded by the partition plate 4 and the outflow end wall as in the case of the previous embodiments. As shown, each stationary zone 7 can be provided with a bottom 10 having an upward slope toward the outflow side, as in the case of the embodiment shown in FIG. 2 or 3. For this reason, it is possible to avoid the problem that the microorganism-immobilized carrier 6 is present at a high density near the outflow end in the tank 1, and the microorganism-immobilized carrier 6 can be present in the tank 1 almost uniformly.

FIG. 5 is a view showing still another embodiment of the stationary zone provided in the reaction tank. As in the case of the embodiment described above, it is possible to have a stationary zone 7 provided by a partition plate 4 and also a bottom part 10 with an upward slope towards the outflow side, here additionally the tank 1 At the outflow end 2 of the sloping plate, the slope plate slopes 1 upwardly with respect to the outflow direction of the liquid.
4 are provided. For this reason, the fiber component, dust, etc. 8 contained in the treated water is guided to the slope plate 14 so that it flows out of the tank 1 more easily than in the above-described respective embodiments.

FIG. 6 is a view showing still another embodiment of the stationary zone provided in the reaction tank. As in the case of the embodiment described above, it is possible to have a stationary zone 7 provided by a partition plate 4 and also a bottom part 10 with an upward slope towards the outflow side, here additionally the tank 1 A screen 15 is installed above the outflow end 2 of the so as to face the flow of the liquid and is inclined toward the stationary zone 7. For this reason, the outflow of the microorganism-immobilized carrier 6 is more reliably suppressed than in the above-described respective embodiments.

[0021]

As described above, according to the present invention, the partition plate is installed in front of the outflow end of the reaction tank in which the microorganism-immobilized carrier having a sedimentation property is put, so that the microorganism-immobilized carrier is removed from the tank. Can be suppressed to some extent. Further, an opening is provided at the bottom of the partition plate, and a stationary zone is provided in the space between the partition plate and the outflow end of each tank to block the influence of liquid flow and agitation in each tank, and The maximum value of the rising linear velocity of the mixed solution in this static zone was designed to be smaller than the minimum value of the sedimentation velocity of the immobilized carrier in each tank, so that the microorganism-immobilized carrier beyond the partition plate was Since it will certainly settle in the stationary zone, it is possible to prevent the microorganism-immobilized carrier from flowing out of each tank. Therefore, by these, the outflow of the microorganism-immobilized carrier to the outside of each tank can be reliably suppressed, and these microorganism-immobilized carriers can be favorably involved in the nitrification or denitrification reaction in each reaction tank. On the other hand, the static zone has a simple structure, and since the liquid flows at the speed at which the microorganism-immobilized carrier settles, the fiber content and dust contained in sewage etc. will not be accumulated in the static zone and will go out of each tank. leak. Therefore, the maintenance of the reaction tank becomes easy.

When two or more static zones are installed in the nitrification tank or the denitrification tank, it is possible to avoid the problem that the carrier is denser near the outflow end in each tank. Since they are almost evenly present in each reaction tank, the nitrification or denitrification reaction can be carried out more efficiently.

Further, since the bottom of the stationary zone of each reaction tank has an upward slope toward the outflow side, the microorganism-immobilized carrier settled in the stationary zone is in each reaction tank in a fluidized / stirred state. Since it can be reliably returned to the above, it is not only effective for nitrification and denitrification in the tank, but also a special device for returning the microorganism-immobilized carrier is not required, and in terms of maintenance and operation cost Be advantageous.

Further, by providing one or a plurality of inclined plate sekis having an upward slope in the outflow direction of the liquid at the outflow end of each tank, fiber components and dust are guided to the inclined plate sekis more reliably. It flows out of each tank, and the maintenance of the reaction tank becomes easier.

Further, by installing the carrier outflow prevention screen at the outflow end of the nitrification tank or the denitrification tank, the outflow of the microorganism-immobilized carrier to the outside of each tank can be more reliably suppressed. As a result, nitrification and denitrification are performed more effectively, and no special equipment for returning the microorganism-immobilized carrier is required, which is advantageous in terms of maintenance and operation costs.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a stationary zone provided in a reaction tank.

FIG. 2 is a diagram showing another example of a stationary zone provided in a reaction tank.

FIG. 3 is a view showing still another embodiment of the stationary zone provided in the reaction tank.

FIG. 4 is a view showing still another embodiment of the stationary zone provided in the reaction tank.

FIG. 5 is a view showing still another embodiment of the stationary zone provided in the reaction tank.

FIG. 6 is a view showing still another embodiment of the stationary zone provided in the reaction tank.

[Explanation of symbols]

 1 Reaction Tank 2 Outflow End 3 Mixed Liquid 4 Partition Plate 5 Opening Area 6 Microorganism Immobilization Carrier 7 Stationary Zone 10,11 Stationary Zone Bottom 14 Inclined Plate Seki 15 Screen

Claims (5)

[Claims] 1. A denitrification tank for biologically denitrifying under anoxic conditions and a nitrification tank for biologically nitrifying under aerobic conditions are arranged in this order, and a part of the nitrification-treated water is removed. While circulating the denitrification tank inflow part, the remaining nitrification water flows out through the settling basin and at the same time, returns some or all of the sludge extracted from this settling basin to the denitrification tank inflow part. In the sewage treatment apparatus that simultaneously removes the BOD component and nitrogen, the carrier for immobilizing denitrifying bacteria having a sedimentation property, which is introduced into the denitrification tank so that it can flow sufficiently, and the denitrifying bacterium immobilizing carrier that has been introduced into the nitrification tank so that it can flow sufficiently And a carrier for immobilizing nitrifying bacteria having a sedimentation property, and a partition plate is installed vertically or obliquely over the entire width or a part of the tank in front of the outflow end of each of the above-mentioned tanks and opened at the bottom of the partition plate. By having a hole,
A static zone is provided in the space between the partition plate and the outflow end of each tank to block the effects of liquid flow and agitation in each tank, and the maximum linear velocity of the liquid mixture rises in this static zone. A sewage treatment apparatus characterized in that the value is smaller than the minimum value of the sedimentation speed of the microorganism-immobilized carrier in each tank. 2. The sewage treatment apparatus according to claim 1, wherein one or two or more further stationary zones are installed in a direction farther from the outflow end than the stationary zone in each tank. 3. The sewage treatment apparatus according to claim 1 or 2, wherein the bottom of the stationary zone in each tank has an upward slope toward the outflow side. 4. One or a plurality of inclined plate claws having an upward slope with respect to the outflow direction of the liquid is installed at the outflow end of each tank. Sewage treatment equipment. 5. A screen for preventing the outflow of the microorganism-immobilized carrier is installed at the outflow end of each tank.
The sewage treatment apparatus according to any one of 1 to 3.