JPH04322792A - Biological filter equipment for organic sewage - Google Patents

Abstract

PURPOSE:To improve the quality of treated water and to reduce the volume or setting area of the entire filter equipment by biologically treating water also in a treated water storage tank in the equipment for cleaning org. sewage. CONSTITUTION:A packed bed 8 of a granular filter medium is provided in a treated water storage tank 7 into which treated water is introduced from a biological tank filter 1, a diffuser 10 is furnished in the bed 8 to diffuse an oxygen-contg. gas into the bed 8 to carry out biological treatment, and the bottom of the treated water storage tank 7 and the lower part of the biological tank filter 1 are connected through a backwashing water passage 13.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a biological filtration device for purifying various organic wastewater such as sewage, human waste, and industrial wastewater.
In particular, the present invention relates to a biological filtration device that uses a treated water storage tank to increase processing capacity.

0002

[Prior Art] Conventionally, as a method for biologically treating organic wastewater such as sewage, human waste, and industrial wastewater, there is a biological filter bed method in which microorganisms are supported on granular filter media. If the treatment is carried out under conditions where oxygen-containing gas such as air is passed through, it becomes biological treatment under aerobic conditions, and the biological filter bed is immersed in the liquid, or the wastewater is drained from above the filter bed. Depending on the state in which the filter is dispersed and flows down into the filter bed, it can be divided into the submerged filter bed method and the trickling filter bed method, each of which has its own advantages.

[0003] An outline of an aerobic submerged biological filter bed device, which is one type of the device, has a structure as shown in the schematic diagram of FIG. This device allows organic sewage to flow down into a packed bed made of various granular filter media such as anthracite provided in a biological filtration tank 1 while supplying air in a distributed manner from an air supply pipe 3 and an aeration device 4. For wastewater, the filtration action of SS is performed using a granular filter medium, and the biological treatment is performed using a biofilm on the surface of the filter medium. The packed bed that performs this biological treatment is usually
It is called biological filter bed 2.

[0004] In this device, a treated water storage tank 7 is provided downstream of the biological filtration tank 1 having the biological filtration bed 2, and stores the treated water discharged from the biological filtration tank 1. The storage tank 7 not only stores the treated water for use in some purpose or for release, but also needs to backwash the biological filter bed 2 when the filtration resistance of the biological filter bed 2 increases. Therefore, the amount of treated water necessary for backwashing is stored.

[0005]

However, the required volume of a treated water storage tank attached to a tank having a biological filter bed is required to be three times or more larger than the volume of the tank having the biological filter bed. This is because it is said that in order to backwash a biological filter bed, an amount of backwash water that is three times or more of the volume of the biological filter bed is required. For this reason, the conventional biological filter bed apparatus has the disadvantage that the installation area of the treated water storage tank is large and the construction cost is high.

[0006] The present invention makes effective use of the treated water storage tank, which is used only for storing treated water in conventional biological filter devices, to store treated water and purify the water at the same time. The purpose is to significantly reduce the installation area or volume of the entire device (combining the filtration tank and treated water storage tank) compared to conventional devices, or to further improve the quality of the treated water.

[0007]

[Means for Solving the Problems] The present invention supplies organic wastewater to a biological filtration tank that has a packed bed filled with granular filter media and has an aeration device that introduces oxygen-containing gas into the packed bed. In a device for biological filtration, a packed bed of granular filter media is provided in a treated water storage tank into which treated water from the biological filtration tank flows, and an aeration device is provided to introduce oxygen-containing gas into the packed bed, and The biological filtration system for organic wastewater is characterized in that a liquid path is provided that connects the bottom of the treated water storage tank to the lower part of the biological filtration tank and sends water in the treated water storage tank to the biological filtration tank. achieved its purpose.

[0008] The biological filtration tank having a packed bed filled with granular filter media used in the present invention can be exactly the same as the tank having an aerobic submerged biological filter bed used in conventional devices. All known materials such as anthracite, sand, chamotte, anti-flinder, plastic particles, porous elastic granules such as polyurethane pieces, and porous ceramic granules can be used. A diffuser is provided in the packed bed filled with the granular filter medium to disperse and supply an oxygen-containing gas such as air into the packed bed. This supply of air causes aerobic microorganisms to grow in the packed bed, and this bed acts as an aerobic biological filter bed. Furthermore, air for periodically cleaning the packed bed is sent from the air diffuser during the air cleaning. Organic wastewater may be allowed to flow into this biological filtration tank from top to bottom or from bottom to top, but a downward flow type is preferable. The treated water from the biological filtration tank is sent to the treated water storage tank through a liquid path.

A packed bed of granular filter media is provided in the treated water storage tank. The type of granular filter medium used in this packed bed may be the same as the granular filter medium used in the biological filtration tank, such as anthracite or sand, but especially porous elastic granules with a cubic network structure such as polyurethane pieces. It is preferable to use porous ceramic granules, and since they have excellent effects in these cases, these will be referred to as "granular solids." It is preferable that the granular filter media, especially the granular solids, have a relatively large particle size and a shape with large gaps between them. This is because water in the treated water storage tank is taken out and sent rapidly when backwashing the biological filtration tank, so it is necessary to allow the water to freely flow through the packed bed. Further, the volume of the treated water storage tank is preferably large enough to store the amount of water necessary to backwash the biological filtration tank, despite the presence of the packed bed of granular filter media. Furthermore, an aeration device for distributing and supplying an oxygen-containing gas, such as air, is provided in the packed bed of the granular filter medium, and the gas is supplied into the packed bed to perform aerobic biological treatment in the packed bed. let The water treated in this treated water storage tank (to distinguish it from the treated water from the biological filtration tank)
(referred to as "highly treated water") will flow out from the storage tank as is, or if necessary, it will be further purified and then released.
Or reused.

[0010] Then, a liquid path is provided from the bottom of the treated water storage tank to the biological filtration tank, and a transfer means such as a pump is provided in the middle so that the treated water can be sent from the treated water storage tank to the biological filtration tank. When backwashing the tank, the treated water is sent to perform backwashing.

[0011]

[Function] In the present invention, a packed bed of granular filter media is also provided in the treated water storage tank so that aerobic biological treatment can be performed there as well, so the biological treatment area is widened and the overall biological treatment capacity is increased. I will do it. Therefore, if the amount of organic wastewater to be treated is constant, it will be treated to a higher level, and if the water quality remains the same as before, the volume of the entire biological filtration system can be reduced. Therefore, the installation area can be reduced.

Furthermore, in the present invention, when backwashing a biological filter tank, the water being treated in the granular filter media packed bed of the treated water storage tank is also sent, and this water can be accompanied by microorganisms on the packed bed. However, the packed bed of the biological filtration tank becomes dirty or has a large amount of microorganisms attached to it due to the filtration and biological treatment of organic sewage, and this packed bed is reversed. The backwash wastewater discharged during washing contains a large amount of these substances, so there is no need to use purified treated water as backwash water for backwashing, so it is not necessary to use purified treated water in the treated water storage tank. The presence of water during treatment within the granular filter medium does not cause any problems.

Further, in the present invention, since the treatment is further performed in the granular filter material packed bed of the treated water storage tank, the treatment in the biological filtration tank may be limited to an insufficient level, so that the biological filtration tank can be downsized. can. In any case, if the purified water (highly treated water) flowing out from the treated water storage tank has the same quality as the treated water in the treated water storage tank in the conventional equipment at the stage of its outflow or just before that, then The same purpose is achieved with the device.

[0014]

[Examples] The present invention will be specifically explained below with reference to Examples. However, the present invention is not limited to this example.

Example 1 As shown in FIG. 1, a biological filtration tank 1 has an aerobic biological filter bed 2 filled with anthracite granular filter media having an average particle size of 3 mm. An air diffuser 4 is provided at the bottom of the bed 2 for supplying oxygen to living organisms and cleaning the biological filter bed 2 with air, and an air supply pipe 3 is connected to the air diffuser 4. Organic wastewater is introduced from the organic wastewater inflow pipe 5 provided above the tank 1, and the air supply pipe 3
The air is supplied from the air diffuser 4 and dispersed into the biological filter bed 2, and the organic wastewater is subjected to aerobic biological treatment in the biological filter bed 2, and the treated water with reduced BOD etc. The treated water is sent from the lower part of the tank 1 to the treated water storage tank 7 via the treated water outflow pipe 6.

A packed bed 8 filled with small pieces of polyurethane foam (10 mm square) is provided in the treated water storage tank 7.
An air diffuser 10 connected to an air supply pipe 9 is provided at the lower part of the packed bed 8, and air is distributed and supplied into the packed bed 8 from the air diffuser 10, and the treated water is converted into biological materials by the packed bed 8. Process. The filling layer 8 is supported by a water-permeable support plate 10 below, and a net 11 is placed above to prevent small pieces of polyurethane foam from floating due to air bubbles. It is not necessary when the granular solid does not float.

In this biological treatment in the packed bed 8, soluble BOD or NH3-N remaining in the treated water is removed by living organisms attached to the small pieces of polyurethane foam in the packed bed 8. As a result, highly treated water of extremely good quality is formed and flows out of the system through the outflow pipe 12. Since it is extremely easy to reduce the quality of the treated water flowing out of the biological filtration tank 1 to 10 mg/liter or less of SS by the treatment in the previous biological filtration tank 1, if the granular solids in the packed bed 8 are made coarse, the packed bed 8 is not clogged by SS.

[0018] As a result, the clogging of the biological filter bed in the biological filter tank 1 progresses, and its filtration resistance increases from 500 to 1000 m.
When mH2O increases, stop the organic wastewater supply,
The valve 14 of the liquid pipe 13 communicating from the bottom of the treated water storage tank 7 to the lower part of the biological filtration tank 1 is opened, and the pump 15 is driven to send the water in the storage tank 7 to the lower part of the biological filtration tank 1, and the biological filtration bed is Backwash 2. The backwash wastewater is discharged from a backwash wastewater outflow pipe 16 provided at the upper part of the biological filtration tank 1. At this time, keep the valve provided on the treated water outflow pipe closed. And the storage tank 7
When the water level in the tank 7 gradually decreases and the storage tank 7 becomes almost empty, the pump 15 is stopped and the valve 14 is closed to complete the backwashing operation. At this time, the SS and biofilm retained in the packed bed 8 of the storage tank 7 flow out when the water level falls, and the packed bed 8 is thereby also cleaned at the same time. Note that, before operating the pump 15 for backwashing, the packed bed 8 can be cleaned more effectively by sending a large amount of air from the air diffuser 10 for several minutes to clean the packed bed 8 in advance. .

When the backwashing of the biological filter bed 2 is completed in this way, the supply of organic sewage is started, the valve of the treated water outflow pipe 6 is opened, and the treatment is restarted. The water level in the storage tank 7 gradually rises, during which biological treatment is performed in the packed bed 8, etc., and the water level in the storage tank 7 increases.
When reaching the upper part of the outlet pipe 12, the highly treated water begins to flow out. In this embodiment, the treated water from the biological filtration tank 1 is allowed to flow in an upward flow into the packed bed 8 of the storage tank 7, but it may be made to flow in a downward flow. The aeration device may be located at any position as long as the inside of the packed bed (biological filtration tank and treated water storage tank) can maintain an aerobic state, and may be located within the packed bed or below the packed bed.

[0020]

[Effects of the Invention] In the present invention, the volume of the treated water storage tank, which was used only as a storage tank in the conventional biological filter bed device, is effectively utilized to carry out further biological treatment within that space. Since the treatment is carried out better and the treatment from the biological filtration tank is further purified, highly treated water with better water quality than before can be obtained. In addition, if the quality of this final advanced treated water is the same as the quality of treated water obtained with conventional equipment, a biological filtration tank is installed in consideration of the amount of biological treatment performed in the packed bed of the treated water storage tank. Since the biological treatment can be reduced by the amount mentioned above, the volume of the biological filter tank can be considerably reduced, for example, to less than half the volume of the biological filter bed tank in conventional equipment. can do. Therefore, it is possible to reduce the volume and installation area of the entire device.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of an apparatus in an embodiment of the invention.

FIG. 2 shows a schematic diagram of a conventional aerobic submerged biological filter bed device.

[Explanation of symbols]

1 Biological filtration tank 2 Biological filter bed 3 Air supply pipe 4 Air diffuser 5 Organic wastewater inflow pipe 6 Treated water outflow pipe 7 Treated water storage tank 8 Filled bed 9 Air supply pipe 10　　　　Air diffuser 11 Net 12 Outflow pipe 13 Liquid pipe 14 Valve 15 Pump 16 Washing drainage outflow pipe

Claims (1)

[Claims] 1. A device for biological filtration by supplying organic wastewater to a biological filtration tank having a packed bed filled with granular filter media and having an aeration device for introducing oxygen-containing gas into the packed bed, A packed bed of granular filter media is provided in the treated water storage tank into which the treated water from the biological filtration tank flows, and an aeration device is provided to introduce oxygen-containing gas into the packed bed, and a gas containing gas is introduced from the bottom of the treated water storage tank. A biological filtration device for organic wastewater, characterized in that a liquid path is provided that is connected to a lower part of the biological filtration tank and sends water in the treated water storage tank to the biological filtration tank.