JP2000140873A - Aerobic treating tank and sewage treating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aerobic treating tank capable of preventing the deterioration of treating performance accompanied with the formation of carrier concn. distribution and to provide a sewage treating method using the tank. SOLUTION: In the aerobic treating tank 1, an air supply means is provided at the bottom part and a screen 6 preventing the flowing out of a carrier is provided in the vicinity of a discharge port of treated water and an immobilized carrier 2 at which microorganisms are immobilized is kept in a floating state. In such a case, the air supply at the downstream side is increased and the water stream made to flow to the upstream side is formed in the tank by using the aerobic treating tank where a fine bubble diffuser 8 group at the upstream side of the treating tank and an air diffusing plate 3 group disposed at the downstream side each as an air supply means are disposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aerobic treatment tank for sewage and a sewage treatment method using the sewage.
The present invention relates to an aerobic treatment tank for biologically treating organic wastewater such as night soil and industrial wastewater using a microorganism-immobilized carrier, and a sewage treatment method using the same.

[0002]

2. Description of the Related Art Conventionally, in order to treat BOD and nitrogen in sewage and industrial wastewater at high speed and in a short time, a method using a carrier on which microorganisms are immobilized has been practiced. In this method, microorganisms are immobilized on a carrier having a density about several percent higher than water and injected into an aerobic treatment tank, and the carrier is applied while flowing by a water flow in the tank generated by a diffuser or an amount of diffused air. Treated water is biologically treated.

FIG. 1 shows an example of the structure of a conventional aerobic treatment tank. An aerobic treatment tank 1 is loaded with an immobilization carrier 2 on which microorganisms are immobilized, and an air supply pipe 4 for supplying air to a diffuser plate 3. Here, the water to be treated is
The water enters the aerobic treatment tank 1 through the inflow pipe 5, and the treated water flows out of the outflow pipe 7
However, the screen 6 prevents the immobilized carrier 2 from flowing out. In such a structure, the immobilization carrier 2 raises the flow of the water to be treated flowing from the inflow pipe 5 to the outflow pipe 7 and rises from the tank bottom to the top generated by the buoyancy of the air supplied from the diffuser plate 3. Combined with the flow, it flows in the tank. However, when observing the floating state of the immobilization carrier, the immobilization carrier 2 flows from the tank bottom to the top due to the buoyancy of the air supplied from the diffusing plate 3, but most of the immobilization carrier 2 is in the inflow pipe 5. Together with the to-be-processed water flowing in from the aerobic treatment tank to the outflow pipe 7 side. As a result, the carrier concentration on the upstream side of the tank (on the inflow pipe 5 side) decreased, and on the contrary, the carrier concentration on the downstream side of the tank (the outflow pipe 7 side) increased. As described above, the carrier may be deposited on the downstream portion in the tank, and there is a problem that the supply of dissolved oxygen to the deposited carrier and the efficiency of treating BOD and nitrogen by microorganisms are reduced.

[0004]

SUMMARY OF THE INVENTION The present invention provides an aerobic treatment tank capable of solving the above-mentioned disadvantages of the prior art and preventing a decrease in treatment performance due to formation of a carrier concentration distribution, and a sewage treatment method using the same. The purpose is to do.

[0005]

According to the present invention, a fine bubble diffuser group is provided on the upstream side of a processing tank and a diffuser plate group is provided on the downstream side so that the air supply amount can be increased on the downstream side. This solves the above problem. That is, the present invention has an air supply means at the bottom, a screen for preventing the carrier from flowing out near the outlet of the treated water, and an aerobic treatment tank for sewage that holds the carrier in which microorganisms are immobilized in a suspended state. The present invention provides an aerobic treatment tank characterized in that a fine bubble diffuser group is installed upstream of a treatment tank and a diffuser plate group is installed downstream of the treatment tank as air supply means.

[0006] In the aerobic treatment tank of the present invention,
It is preferable that the air supply means is provided, a guide plate is provided on the front surface of the screen, an air avoiding convex portion is provided at a lower portion of the screen, or both the air avoiding convex portion and the guide plate are provided.

[0007] The present invention further increases the downstream air supply amount by using the aerobic treatment tank of the present invention as described above,
It is an object of the present invention to provide a sewage treatment method characterized by forming a water flow flowing upstream in a tank.

[0008]

Next, the present invention will be described in more detail with reference to the drawings. FIG. 1 is an explanatory diagram of an aerobic treatment tank showing one embodiment of the present invention. 1, the same components as those in FIG. 2 are denoted by the same reference numerals. At the bottom of the aerobic treatment tank 1 of the present invention, a fine bubble diffuser 8 is provided on the upstream side, and a diffuser plate 3 is provided on the downstream side. It is connected to the supply pipe 4 and is configured so that the air supply amount can be set independently of each other. In order to prevent the immobilization carrier 2 from adhering to the screen 6, a guide plate 10 is provided in front of the screen 6,
An air avoiding convex portion 9 is provided at a lower portion of the housing so that air does not flow.

[0009] The water flow in the aerobic treatment tank thus configured is as follows. Here, the flow ratio of air between the diffuser plate 3 having low oxygen dissolving efficiency and the fine bubble diffuser 8 having high oxygen dissolving efficiency is 3: 1. As a result, since the air supply amount on the downstream side of the tank is three times larger than that on the upstream side, a large circulation flow can be formed from the downstream side to the upstream side by the air lift effect. Since the immobilized carrier 2 flows in the tank by this large circulation flow, the carrier does not accumulate on the downstream side of the tank as in the related art. Further, the amount of air supplied from the diffuser plate 3 having a low oxygen dissolving efficiency is three times as large as the amount of air supplied from the fine diffuser 8 having a high oxygen dissolving efficiency. It can be.

A guide plate 10 is provided on the front of the screen 6.
, A downward flow parallel to the screen surface can be formed, and the immobilization carrier 2 can be prevented from flowing perpendicular to the screen surface where it adheres to the screen 6, and the immobilization carrier 2 adheres to the screen 6. Can be prevented.

Further, by providing the air avoiding convex portion 9 at the lower portion of the screen 6, the inflow of air into the lower portion of the screen 6 is prevented, and the downward flow from the screen 6 and the upward flow from the diffusing plate 3 are prevented. Can be combined to form a water flow heading upstream of the tank, and a large circulation flow from the downstream side to the upstream side based on the difference in the air supply amount at the tank bottom can be further increased.

Therefore, by combining the diffuser plate and the fine bubble diffuser as described above, the flow in the tank can be formed while the oxygen supply amount in each part in the tank is the same.
As a result, formation of a carrier concentration distribution can be prevented and eliminated. Furthermore, the installation of the guide plate can prevent the immobilization carrier from adhering to the screen, and the installation of the air avoiding projection prevents air from flowing into the lower portion of the screen, thereby further increasing the flow in the tank.

In the above embodiment, the arrangement of the fine bubble diffuser and the diffuser plate is one combination having an area of one to one.
A plurality of combinations having an area of one to many may be used. In addition, although the air supply amount is set to 1: 3, the air supply amount may be set to 1: 3. Furthermore, in the arrangement of the fine bubble diffuser and the diffuser plate,
Although the microbubble diffuser group arrangement part and the diffuser plate group arrangement part were not separated by a plate, in the aerobic treatment tank of the present invention, the bottom part and the upper part (water surface part) of the tank may be separated by a partition plate opened. .

[0014]

The aerobic treatment tank of the present invention has a fine bubble diffuser on the upstream side and a diffuser plate on the downstream side.
Since the flow in the tank can be formed while maintaining the same amount of oxygen supply in each section in the tank, formation of a carrier concentration distribution can be prevented or eliminated, and high processing performance can be maintained. In addition, the installation of the guide plate can prevent the immobilization carrier from adhering to the screen, and the installation of the air avoiding projection prevents air from flowing into the lower portion of the screen, thereby forming a stronger flow in the tank and maintaining high processing performance. be able to. Furthermore, by providing the guide plate and the air avoiding convex portion, it is possible to form a water flow heading upstream of the tank by combining the downward flow from the screen and the upward flow from the diffuser plate, and reduce the air supply amount at the bottom of the tank. The large circulating flow from the downstream side to the upstream side based on the difference can be further strengthened, the floating state of the immobilized carrier can be made more uniform, and higher processing performance can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an aerobic treatment tank showing one embodiment of the present invention.

FIG. 2 is an explanatory view of a conventional aerobic treatment tank.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 aerobic treatment tank 2 immobilization carrier 3 diffuser plate 4 air supply pipe 5 inflow pipe 6 screen 7 outflow pipe 8 fine bubble diffuser 9 air avoidance convex part 10 guide plate

Claims (3)

[Claims] 1. A wastewater aerobic treatment tank having an air supply means at the bottom and a screen near the outlet of treated water for preventing the carrier from flowing out, and holding the microorganism-immobilized carrier in a floating state. An aerobic treatment tank comprising a fine bubble diffuser group upstream of the treatment tank and a diffuser plate group downstream of the treatment tank. 2. The aerobic treatment tank according to claim 1, wherein a guide plate is provided on a front surface of the screen, and a convex portion for avoiding air is provided on a lower portion of the screen. 3. A sewage treatment method characterized by using the aerobic treatment tank according to claim 1 or 2 to increase the amount of air supply on the downstream side and to form a water flow flowing upstream in the tank.