JPH0641677Y2 - Upflow type continuous biofilm filter - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is designed to reduce the concentration of organic substances or nitrogen in low to high concentrations in river water or lake water with relatively advanced pollution, sewage, night soil, industrial wastewater, etc. The present invention relates to a biological treatment technology for purifying contained water with microorganisms.

[Conventional technology]

There are many biological treatment technologies since ancient times, and they are still popular today. Among them, those using a medium for adhering microorganisms have made many technological advances in recent years, and in particular, a granular material is used as a medium and moved by an air lift pipe,
For example, the continuous biofilm filtration device as disclosed in JP-A-61-291099 has few constituent elements and has been expected by many people.

[Problems to be solved by the device]

However, such a continuous biofilm filtration device generally has a downward flow type configuration, and when raw water is passed through in an upward flow type for treatment, air supplied to maintain aerobic conditions, etc. Since the SS trapped between the granular media is entrained in the treated water by the agitation action of the air bubbles in (3), the SS removal capability is significantly reduced, making it difficult to put the upflow system into practical use.

The present invention is intended to provide an upflow continuous biofilm filtration device that enables an upflow system that has been difficult to put into practical use in the past, obtains a high biological treatment effect, and has a high SS trapping effect. is there.

[Means for Solving the Problems]

The present invention forms a packed bed of granular medium in a tank, opens a raw water inlet at the bottom of the tank, and provides a treated water outlet at the top of the tank.
In an upflow continuous biofilm filter for cleaning while circulating and transporting the granular medium from the lower part to the upper part of the packed bed by an air lift pipe, an air diffuser is provided between the raw water inlet and the upper end of the packed bed. Is horizontally arranged, and a lower part of the air diffuser is a filtration part and an upper part of the air diffuser is a biological treatment part.

Further, the present invention is characterized in that, in the upward flow type continuous biofilm filtration device, a circulation path for circulating a part of the treated water flowing out from the treated water outlet to the raw water inlet is provided. Is.

[Action]

In the present invention, the raw water is supplied from the raw water inlet at the lower part of the tank and is passed upward, while the air-lift pipe cleans the granular medium while transferring it upward from the lower part of the packed bed and refills it. Circulated to the top of the bed. Therefore, the packed bed gradually moves downward as a whole.

The raw water that has reached the packed bed in an upward flow from the lower part of the tank is trapped by SS in the raw water by coming into contact with the granular medium to which the biofilm that has moved from the biological treatment section to the filtration section is sufficiently attached. At this time, since the filter unit does not diffuse air from the air diffuser, the SS trapping effect is enhanced. Next, when the raw water reaches the upper biological treatment section, since the aerobic state is maintained by the air diffuser, the growth of the biofilm occurs on the surface of the granular medium, and the pollutants in the raw water are biologically oxidized / oxidized. Disassemble.

In this case, since the granular medium circulated and transferred to the upper part of the biological treatment section by the air lift pipe is subjected to intense cleaning during the transfer in the air lift pipe, the surface biofilm is very thin and Although the thickness of the biofilm increases as it moves, the amount of biofilm adhering to the granular medium in the biological treatment section is relatively small, so there is little SS that separates due to the stirring action of the bubbles from the air diffuser, Moreover, since the raw water passes through the filtration section, there is almost no inert SS, and after biological treatment is effectively performed, it becomes treated water and is taken out from the treated water outflow section at the top of the tank.

Further, in the above treatment, when treating the nitrogen-containing wastewater,
Nitrifying bacteria spontaneously grow in the biological treatment section, and nitrification action occurs. In such a case, if a circulation path for circulating a part of the treated water in the lower part of the tank is provided, a part of the circulated treated water is mixed with the raw water, and a denitrification phenomenon occurs in the filtration section.
It also enables denitrification.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings.
Is a treatment tank in which the packed layer A of the granular medium 2 is formed,
The lower open end of the air lift pipe 4 connected to the air introduction pipe 3 and vertically arranged in the central portion of the processing tank 1 is opened to the lower part inside the packed bed A, and the upper open end is opened to the granular medium separation chamber 5. There is. Further, a cleaning drainage pipe 6 guided to the outside of the processing tank 1 is connected to the granular medium separating chamber 5, and the lower end of the granular medium separating chamber 5 is opened above the packed bed A.

An inflow port 8 of a raw water inflow pipe 7 is opened in the lower part of the treatment tank 1,
Between the inflow port 8 and the upper end of the packed bed A, an air diffuser pipe 10 for obtaining an aerobic condition is connected horizontally to the oxygen or other oxygen-containing gas introduction pipe 9 and arranged below the air diffuser pipe 10. The filtration section B is provided, and the biological treatment section C is located above the air diffuser 10.

In the figure, 11 is an overflow launder provided on the upper part of the treatment tank 1, and a treated water outflow pipe 12 is connected.

The granular medium 2 may be any one commonly used as a filter medium, such as sand, anthracite, activated carbon, lightweight aggregate, plastic filter medium, and the like.
The particle size is also not particularly limited, but if it is too fine, water resistance increases, and if it is too coarse, the air lift power becomes excessive, so about 2-10 mm is desirable.

Then, the raw water flows into the treatment tank 1 through the raw water inflow pipe 7 from the inflow port 8 and flows upward, while the air introduction pipe 3
Due to the action of the air lift pipe 4 caused by the air blown in from the granular medium 2 in the lower part of the filtering section B, the granular medium separation chamber 5
Be transferred to. During this time, the granular medium 2 is washed in the air lift pipe 4 by vigorous agitation, is separated in the granular medium separation chamber 5, and the cleaning drainage is discharged from the cleaning drain pipe 6 to the outside of the system, and the cleaned granular medium 2 is It is circulated and transferred from the lower end to the upper part of the biological treatment section C. Therefore, the packed bed A as a whole gradually moves downward.

Now, the raw water flowing upward in the treatment tank 1 comes into contact with the granular medium 2 having the biofilm sufficiently adhered in the upper biological treatment section C and moved to the filtration section B, so that SS in the raw water is SS. Is removed by the biofilm filtration action (the granular medium 2 itself does not have a filtration action because of its large particle size, but the biofilm attached to the granular medium has a strong adhesive force and can capture SS),
Some dissolved organic matter is also adsorbed and removed by the biofilm. Next, when the biological treatment portion C is passed through the filtration portion B, the biological treatment portion C
Is maintained in an aerobic state by the oxygen-containing gas diffused from the oxygen-containing gas introduction pipe 9 through the air diffusing pipe 10, the dissolved organic matter and ammonia nitrogen are biooxidized, and the biofilm is also proliferated.

By the way, since the granular medium circulated and transferred to the biological treatment section C via the air lift pipe 4 and the medium separation chamber 5 is subjected to intense cleaning in the air lift pipe 4, the biofilm on the surface thereof is several to 10 μm. Although very thin on the order, the granular medium 2 moves from the top to the bottom, at which time the thickness of the biofilm gradually increases. Therefore, although the biological treatment section C is sent by the air diffuser 10, since the amount of the biological film attached to the granular medium 2 is relatively small, the SS that is separated due to the stirring action of the bubbles is also small. For example, taking sewage as an example, it is possible to reduce the SS of the treated water to 20 mg / l or less, which is comparable to the activated sludge treatment.

In this way, after the raw water is filtered and biological treatment is performed in the same treatment tank in the upward flow, the treated water is spilled by the overflow launderer 11.
Is taken out through the treated water outflow pipe 12.

In the present invention described above, the most important point is how to contact the raw water with the granular medium 2. That is, the position of the air diffuser 10 for maintaining the aerobic condition in the packed bed A is largely related to the biofilm filtration action.

Specifically, the lower part of the air diffusing tube 10 should be the filtration part B, and the granular medium 2 of the filtration part B should be one in which the biofilm is sufficiently attached (the particle size of the granular medium 2 used in biofilm filtration is ,
It is extremely larger than the particle size of the filter media used in normal clarification filtration.
Therefore, the filtration effect does not occur unless the biofilm is sufficiently attached.) It is important that the biofilm is not excessively attached to the granular medium 2 of the biological treatment unit C, and the filtration unit B and the biological treatment unit It is not said that the layer thickness of the part C is large, but there is an appropriate range according to each processing characteristic.
0 to 1000 mm is preferable, and the biological treatment section C is appropriately 1000 to 2000 mm.

Furthermore, an example in which the drainage of the urban drainage canal is purified by the present invention is shown below.

Major Specifications treatment tank dimensions of the device: diameter 2.2 m × height 5.5m filler layer thickness: Filtration section 700mm biological treatment unit 1500mm particulate media: anthracite processing condition of treated water having a particle size of 3~6mm: 200~250m ³ / day BOD Load: 2.7-4.2 kg / m ³・ BOD 70-110 mg / l, SS 40-90 mg / l raw water was treated at a day, BOD 10-20 mg / l, SS 5-30 mg / l was purified and high Despite the load treatment, the treated water quality was almost the same as the activated sludge treated water.

Further, as shown in FIG. 2, the treated water outflow pipe 12 is once introduced into the distribution tank 13, and a part of the treated water is circulated from the distribution tank 13 through the circulation pipe 14.
Then, the raw water pump 16 causes the raw water pump 16 to flow together with the raw water through the raw water inflow pipe 7 and the inflow port 8 into the filtration section B, so that the ammonia-containing wastewater can be denitrified.

For example, when ammonia-containing wastewater such as sewage is treated at a BOD load of about 1 kg / m ³ · day or less, nitrifying bacteria grow naturally in the biological treatment section C and nitrification occurs. When the raw water is circulated in the raw water tank 15 through the circulation pipe 14 and the raw water pump 16 causes the raw water to flow into the filtration section B from the inflow port 8, the denitrification phenomenon occurs in the filtration section B.

[Effect of device]

The present invention enables upflow continuous biological filtration, which was conventionally difficult because a large amount of SS remains in the treated water, and as a result, the following useful effects occur.

Biological treatment and solid-liquid separation are possible in a single treatment tank, and no post treatment is required.

Since the backwashing operation is unnecessary, backwashing operation can be simplified, and the auxiliary equipment such as backwashing pump, backwashing blower, and water tank for backwashing can be simplified. it can.

For the biofilm adhering to the granular medium in the biological treatment section,
Since there is no inert SS in the raw water, a high biological treatment effect can be expected.

Since the biofilm is sufficiently attached to the granular medium in the filtration section, the SS trapping effect is high.

The quality of treated water is comparable to that of sewage treatment.

It is also possible to denitrify by circulating a part of the treated water.

[Brief description of drawings]

1 and 2 are vertical sectional views showing an embodiment of the present invention. 1 ... Treatment tank, 2 ... Granular medium, 3 ... Air introduction pipe, 4
…… Air lift pipe, 5 …… Particle separation chamber, 6 …… Cleaning and draining pipe, 7 …… Raw water inflow pipe, 8 …… Inflow port, 9 …… Oxygen-containing gas introduction pipe, 10 …… Aeration pipe, 11 …… Overflow ronder, 12 …… Treatment water outflow pipe, 13 …… Distribution tank, 14 …… Circulation piping, 15 …… Raw water tank, 16 …… Raw water pump, A …… Packed bed,
B: filtration section, C: biological treatment section.

Claims (2)

[Scope of utility model registration request] 1. A packed bed of a granular medium is formed in a tank, a raw water inlet is opened at a lower part of the tank, a treated water outlet is provided at an upper part of the tank, and an air lift pipe is provided from a lower part to an upper part of the packed bed. In an upward flow type continuous biofilm filtration device that performs cleaning while circulating and transporting the granular medium, an air diffuser is horizontally arranged between the raw water inlet and the upper end of the packed bed, and a portion lower than the air diffuser is installed. An upflow type continuous biofilm filtration device characterized in that a biological treatment part is provided above the aeration device as a filtration part. 2. A packed bed of a granular medium is formed in a tank, a raw water inlet is opened at a lower part of the tank, a treated water outlet is provided at an upper part of the tank, and an air lift pipe is provided from a lower part to an upper part of the packed bed. In an upward flow type continuous biofilm filtration device that performs cleaning while circulating and transporting the granular medium, an air diffuser is horizontally arranged between the raw water inlet and the upper end of the packed bed, and a portion lower than the air diffuser is installed. The biological treatment section is located above the air diffuser as the filtration section,
An upflow continuous biofilm filtration device, characterized in that a circulation path for circulating a part of the treated water flowing out of the treated water outlet is circulated in the lower part of the tank.