JPH0595700U - Aerobic biological filtration equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] Completely solves the drawbacks of conventional aerobic biological filtration equipment, can effectively clean the filter medium, has excellent microbial retention, and has less clogging and filter medium outflow. Providing equipment. According to a first aspect of the present invention, a packed fixed bed filled with a granular solid having a three-dimensional mesh structure is formed in a biological filtration tank, and at least one layer of a lattice member is horizontally arranged in the fixed packed bed. Aerobic biological filtration equipment.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an aerobic biological filtration device for purifying various organic wastewater such as sewage and industrial wastewater.

[0002]

[Prior Art]

 BACKGROUND ART Conventionally, an aerobic biological filtration device (Bio-logical Aerated Filter, abbreviated as BAF) using a granular mineral such as anthracite is known. Since BAF can perform biological treatment and SS removal by filtration in the same tank and there is no need to set up SS precipitation process, BAF has been attracting great interest in recent years.

However, the conventional BAF has the following drawbacks and thus has limited application fields. Microorganisms only adhere to the surface of granular filter media such as anthracite in the order of micron, so the amount of microorganisms retained in the system is small, and as a result, the bioreaction rate (and therefore the processing capacity) is not large. When organic sewage containing a large amount of SS (organic sewage supplied to the treatment tank for treatment is sometimes referred to as raw water) is supplied, the packed fixed bed of granular filter media such as anthracite in the packed fixed bed is severely clogged. Occurs, which causes a rapid increase in filtration resistance and renders processing impossible. Therefore, in the case of high SS raw water (usually SS 100 mg / liter or more), a precipitation tank is required before B AF.

When raw water having a high BOD is supplied, a microbial membrane is violently increased in the upper part of the packed fixed bed, resulting in rapid clogging of the filter bed. Previously, it was difficult to apply to raw water with BOD of 150 mg / liter or more. Support beds such as gravel that support biofouling media such as anthracite are easily contaminated by biological slums. When cleaning the filter bed, loss of outflow of filter material is likely to occur.

[0005]

[Problems to be solved by the device]

 An object of the present invention is to provide a new type BAF device that can completely solve the above-mentioned drawbacks of the conventional BAF, and an object of the present invention is to provide a BAF device that is excellent in microbial retention and has less clogging and filter medium outflow. To do.

[0006]

[Means for Solving the Problems]

 The above object is achieved by the aerobic biological filtration device of the present invention described below. That is, a packed and fixed bed having a three-dimensional network structure and filled with a granular solid is formed in the biological filtration tank, and at least one planar grid member for dividing the bed into upper and lower sections is arranged in the packed and fixed bed. It is an aerobic biological filtration device characterized by performing.

The aerobic biological filter of the present invention supplies at least a filter bed filled with granular solids, a biological filter having an air diffuser and a washing device, an organic wastewater, and an outflow of treated water. Equipped with means.

The feature of the filter bed of the above-mentioned biological filtration tank of the present invention is that the granular solid packed in the filter bed and forming the packed and fixed bed has a three-dimensional network structure. The granular solid having a three-dimensional network structure here is preferably a granular solid in which a three-dimensional network structure is formed by using a material having a specific gravity close to 1.0.

Another feature of the filter bed of the above-mentioned biological filtration tank of the present invention is that the packed fixed bed packed with the particulate solid in the filter bed is used in the packed fixed bed for the reasons described in detail below. By arranging a planar lattice member transversely, the packed fixed bed is divided into multiple stages. The number of tiers to be divided is appropriately determined according to the conditions such as the height of the filter bed.

The term “planar lattice member” as used in the present invention does not mean only a lattice member formed by orthogonal linear members, but other mesh members, members made by forming a large number of holes in a flat plate, etc. However, the packed fixed bed is divided into upper and lower parts, which prevents free movement of the granular filter material between the separated fixed packed layers, but does not cause clogging by the microbial membrane or SS, and allows organic wastewater to pass freely. Means any separating member having the function of The planar lattice member is preferably rigid, but may be flexible. This is a lattice member in order to avoid confusion with other members of the device of the present invention, such as a granular solid having a three-dimensional mesh structure or a net member. Hereinafter, for convenience, a case where the packed fixed layer is divided into two stages will be described.

[0011]

[Constitution and operation of device]

 The main configuration of the aerobic biological filtration apparatus of the present invention will be described with reference to FIG. However, the present invention is not limited to the following description. In the aerobic biological filtration tank 1 of the present invention shown in FIG. 1, organic wastewater flows in through an inflow pipe 2 in the upper part of the tank, and treated water in the aerobic biological filtration tank 1 flows out through an outflow part in the lower portion, an outflow pipe 3 Is piped from the outflow section to the level close to the upper interface of the fixed bed filled with filter medium.

[0012] B ₁ and B ₂ are two fixed packing layers in which the lattice member 4 is horizontally arranged in the filter bed of the aerobic biological filtration tank 1 and partitioned, and the upper layer is B ₁ . These packed fixed layers are packed with a granular solid having a three-dimensional network structure and a specific gravity close to 1.0 (for example, polyurethane foam particles). The diameter of the holes of the lattice member 4 is selected to be a diameter that hinders the free movement of the granular filter media forming the fixed packing layers B ₁ and B ₂ . The lower fixed packed bed B ₂ is supported by a support member 5 provided at the bottom of the biological filtration tank 1. It is preferable that the supporting member 5 is also made of a porous member (eg, grating) similar to the lattice member 4.

An air diffuser 6 for supplying oxygen to microorganisms is provided below the packed fixed bed B ₂ of the biological filtration tank 1. Further, the biological filtration tank 1 is provided with an air supply device for cleaning as cleaning equipment. 7, a water supply device 8 for backwashing, and a washing drainage outflow pipe 9 and a mesh member 10 for blocking outflow of the filter medium are arranged above the biological filtration tank 1.

One of the important components in the present invention is to adopt a granular solid having a three-dimensional network structure (for example, polyurethane foam) as the filter medium, and the three-dimensional network filter medium is filled in the filter bed. Thus, the packed fixed layer is formed, and the organic fixed water and the oxygen-containing bubbles are brought into contact with each other in the packed fixed layer.

The filter medium such as anthracite used in the conventional BAF can retain microbes only on its surface, but the filter medium of the present invention has a three-dimensional mesh-like three-dimensional structure inside the filter medium. In addition to the surface, it is possible to maintain a high concentration of microorganisms inside the filter medium itself. As a result, the present invention can maintain a much higher concentration of microorganisms in the BAF system than in the conventional BAF, and can greatly improve the biological reaction rate (processing capacity).

Here, in the present invention, the packed and fixed bed of the three-dimensional mesh filter medium needs to be operated as an aerobic immersion filter bed. If the filter bed is not soaked and operated, the removal of SS and BOD will be significantly deteriorated, and the filter material will be compressed by its own weight, and clogging due to SS will easily occur.

The immersed granular filter medium of the present invention has a large porosity of 90% or more, so that the increase in filtration resistance due to the capture of SS is extremely small. Also, due to the characteristics of such a filter medium, clogging due to the enlargement of the microbial membrane is unlikely to occur. Appropriate shapes and particle sizes of the granular solid of the present invention are cubes or cuboids, and the particle size is preferably 10 mm or less at the thinnest portion. This is because if the thinnest part of the filter medium is made larger than 10 mm, the dissolved oxygen does not sufficiently penetrate into the filter medium and the inside of the filter medium is easily anaerobicized. The preferred example of the granular solid of the present invention is a rectangular parallelepiped having a particle size of 10 × 25 × 25 mm. However, this is not the case when pure oxygen or oxygen-enriched gas is used as the gas supplied for respiration of microorganisms, and the thinnest part of the filter medium may be 10 mm or more, for example, about 20 mm.

Another important component of the present invention is a lattice member. Without a grid member, the filter medium is light (specific gravity is close to 1.0) when washing the packed fixed bed with air and backwashing with water at the same time. As a result, the filter bed B ₁ is also compressed upward together with the filter material of the filter bed B ₂ and cannot be fluidized at all, and cleaning cannot be performed well.

On the other hand, when the lattice member is provided at an appropriate position (for example, the thickness of the fixed packing layer B ₂ is 0.8 to 1.5 m), that is, in the case of the device of FIG. When the packed fixed bed is divided into the packed fixed bed B ₁ (filter bed B ₁ ) and the packed fixed bed B ₂ (filter bed B ₂ ) at the middle portion in the height direction, the packed fixed bed B is simultaneously washed with air and water. ₂ (filter bed B ₂₎ slag material raised by the grid members is prevented, prevents the filling fixing layer B ₁ slag material filter material filling the fixed layer B ₂ is compressed, the result packed fixed layer B ₁ slag material Air and water can be washed effectively at the same time, and can be effectively washed.

It is not preferable to install the lattice member at a position too close to the interface A. It is good to provide it at a position of 0.5 m or less, preferably 0.8 to 1.5 m from the interface A at least. This lattice member plays an important function when cleaning a filter medium having a three-dimensional network structure.

The hole diameter of the lattice member is preferably set to be slightly smaller than the particle diameter of the filter medium of the filter bed B ₂ . For example, when the particle size of the filter medium of the filter bed B _{2 is} a rectangular parallelepiped with a size of 10 × 25 × 25 mm, it is appropriate that the hole diameter of the lattice member is 20 mm. .

[0022]

【Example】

An embodiment of the present invention will be described with reference to FIG. However, the present invention is not limited by the following description. Organic sewage 2, such as sewage, is introduced from above the device of the present invention. The liquid dispersion plate 11 is placed at the inflow position of the organic sewage 2 to disperse and inject the organic sewage 2. In the present invention, it is not necessary to reduce the SS by precipitating the organic sewage 2 such as sewage as in the case of the conventional BAF, and it may flow directly into the present apparatus. Then, the organic sewage 2 flows down through the packed fixed layers B ₁ and B _{2 of the} filter medium having a three-dimensional network structure such as polyurethane foam and comes into countercurrent contact with the oxygen-containing bubbles supplied from the diffuser 6. To do.

Since microorganisms such as BOD-assimilating bacteria are retained and immobilized at a high concentration on the surface and inside of the filter medium having a three-dimensional network structure, when the BOD of sewage 2 is rapidly removed by a biological reaction. At the same time, the SS of the sewage 2 is captured and removed in the voids of the filter medium, and finally the treated water 3 with a sufficiently reduced BOD and SS (10 mg / liter or less) flows out. The feature of the aerobic filter bed of the present invention is that the filter medium has a large porosity, and therefore the filter bed has a very large porosity, so that clogging is less likely to occur as compared with the conventional BAF.

However, even if the apparatus of the present invention is operated for a long time, the filtration resistance reaches the upper limit or SS leaks to the treated water, so the filter bed is washed at that point.

The three-dimensional mesh-like filter medium of the present invention, which has a specific gravity close to that of water, has a small difference in specific gravity from water, and therefore cannot be easily washed by simple backwashing. However, the method using the lattice member of the present invention is applied. Therefore, effective cleaning can be performed. When a grid member is installed, it can be washed well with twice as much washing water as the volume of the fixed packed bed, and the filtration resistance after washing is the filtration resistance when the clean filter medium is filled (called the initial filtration resistance). Recover up to.

However, when the grid member is not provided, the upper part of the packed fixed bed is compressed, and even if the washing water is used in an amount three times the volume of the packed fixed bed, almost no cleaning is possible, and the initial filtration resistance is restored. It was confirmed that I could not.

Filter bed B₁, B₂The procedure of cleaning is described with reference to FIG. 1. (1) The inflow of the organic waste water 2 is stopped and the treated water outflow valve 12 is closed. (2) The air-washing blower 13 is driven, and the air for air-washing is vigorously filtered on the bed B.₁, B₂Send to. If this operation is continued for 5 to 10 minutes, filter bed B₁, B₂Can be loosened enough. (3) The backwash water is fed by driving the water washing pump 14 while driving the air-washing blower 13. By this operation (3), the amount of SS captured is the filter bed B.₂Much larger than filter bed B ₁ Fluidize violently, the trapped SS and the excess biofilm are separated, and the cleaning wastewater flows out from the outflow pipe 9. Since the outflow of the filter medium is blocked by the mesh member (net) 10, there is no outflow to the outside of the system.

On the other hand, since the filter bed B ₂ is a downward flow filtration, the SS in the organic sewage 2 is trapped from above the filter bed, and therefore the amount of trapped SS is smaller than that of the filter bed B _1, so that the filter medium is fluidized. Without doing so, effective cleaning can be achieved simply by passing the air and water streams upwardly and vigorously between the filter media.

[0029]

[Effect of the device]

 According to the present invention, the following effects can be obtained and the drawbacks of the conventional BAF can be solved. 1. Since it is difficult for the filter medium to close the porosity of 90% or more, it is not necessary to provide a sedimentation tank before the BAF. Also, since the increase in filtration resistance is extremely small, it can be applied to high BOD and high SS wastewater. 2. Since a filter medium having a three-dimensional network structure is used, the concentration of microorganisms that can be maintained in the filter bed is 5 to 10 times higher than that of the conventional BAF, so the reaction rate is fast. 3. There is no clogging on the support floor because a grid member is used instead of a filter media support floor composed of gravel. 4. There is no outflow of filter material during cleaning. 5. The filter member can be effectively washed by the horizontally arranged lattice member in the filling and fixing layer in the filling and fixing tank. 6. Organic wastewater can be highly purified by a single stage of a reactor (BAF).

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the structure and function of an aerobic biological filtration device of the present invention.

[Explanation of symbols]

1 Aerobic biological filtration tank 2 Organic sewage supply pipe 3 Treated water outflow part 4 Lattice member (grating) 5 Supporting member 6 Aeration device 7 Cleaning air supply device 8 Water supply device for backwashing 9 Cleaning drainage outflow pipe 10 Reticulated member 11 Dispersed plate of sewage 12 Treated water outflow valve 13 Blower for washing with air 14 Pump for washing with water A Upper interface of packed fixed bed B ₁ Fixed fixed bed (upper stage) B ₂ Fixed fixed layer (lower stage)

Claims (1)

[Scope of utility model registration request] 1. At least one planar lattice member for forming a packed fixed bed having a three-dimensional network structure and filled with a granular solid in a biological filtration tank, and dividing the bed into upper and lower layers within the packed fixed bed. An aerobic biological filtration device comprising: