JPH0734912B2 - Immersion filter bed biological treatment equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to an immersion filter bed biological treatment apparatus for treating wastewater generated from a paper or pulp manufacturing process.

<Prior art> Conventionally, activated sludge method and sprinkling filter method have been widely used as biological treatment methods for removing organic matter (BOD or COD) in wastewater of paper and pulp, but in recent years, environmental regulations have been added. As a result, the immersion filter method has been reconsidered because it can be operated and controlled easily and an arbitrary organic matter removal rate can be obtained.

In the immersion filter bed, the water to be treated containing organic matter is introduced from the upper or lower part of the filler layer composed of gravel, crushed stone, Raschig rings, reticulate bodies, etc., and microorganisms (aerobic microorganisms or anaerobic microorganisms) that have adhered to the filler layer are introduced. By the action of microorganisms, organic substances in water to be treated are biologically decomposed and removed. Also, if such a treatment is continued, the filling material layer becomes clogged due to the enlargement of microorganisms and the accumulation of suspended substances in the water to be treated,
Since it is not possible to secure a certain amount of water flow or anaerobic microorganisms occur in the case of aerobic microbial treatment, cleaning water and / or cleaning gas is periodically introduced from the bottom of the packing material layer to eliminate clogging. To do.

However, in the conventional biological treatment apparatus using the immersion filter bed method (hereinafter referred to as the immersion filter bed apparatus), natural gravel or crushed stone having a specific gravity of about 2 or more is used as the filler in most cases. When wastewater containing a large amount of fine debris such as wastewater is directly treated with such a submerged filter device, the uneven parts of natural gravel or crushed stone or the protrusions, pointed parts, etc. that are formed by breaking them (hereinafter referred to as unevenness) Fine fiber waste is caught in the
It grows into a large nodule by using it as a core to cause clogging, and in order to eliminate this clogging, cleaning water and / or cleaning gas (mainly air) is periodically introduced from the lower part of the filler layer for cleaning. However, the state in which the filler hardly floats and flows and the fine fiber debris is caught on the uneven portions of natural gravel or crushed stone cannot be easily eliminated, and the cleaning effect is insufficient. Therefore, in order to prevent the fine fiber wastes from flowing into the filler layer, it is necessary to provide a coagulation sedimentation step or a coagulation flotation separation step as a pre-treatment, which requires a large equipment cost.

<Problems to be Solved by the Invention> The present invention solves the problem of insufficient cleaning caused by trapping fine fiber wastes in paper / pulp wastewater in a state of being caught in the filler layer, and fine fiber wastes. It is an object of the present invention to provide a submerged filter device in which fine fibers are easily discharged to the outside of the system by washing even if they are hardly trapped in the filler layer and are trapped in the filler layer.

<Means for Solving the Problems> The present invention is to form a filler layer by filling a filler having an aerobic microorganism or an anaerobic microorganism on its surface to form a filler layer, and from the top or bottom of the filler layer. The present invention relates to a submerged filter apparatus for removing organic matter in paper / pulp wastewater by the action of the aerobic microorganisms or anaerobic microorganisms by inflowing paper / pulp wastewater containing organic matter and fine fiber wastes, and forming the filler layer. The surface of the filler is a smooth granular material, and it sediments during the treatment of the water to be treated to form a fixed filler layer, and washing water and / or washing air flows from the bottom of the filler layer during cleaning. Specific gravity 1.0 to 1.
5. The use of the one having a particle size of 5 mm or more solves the drawbacks of the conventional immersion filter bed device.

<Operation> The present invention will be described in detail with reference to the drawings.

FIG. 1 is a vertical cross-sectional explanatory view showing an example in which the present invention is applied to a submerged filter apparatus using aerobic microorganisms, in which a floor plate 2 having a large number of openings is provided at the bottom of a circular or rectangular tank 1. A filling material layer 4 is formed by filling a filling material 3 on the upper part of the floor plate 2, and a sprinkling pipe 7 having a large number of holes communicating with the raw water pipe 5 and the washing water pipe 6 on the lower part of the floor plate 2; A large number of water sprinkling pipes 9 each having a large number of holes communicating with the pipes 8 are buried, and further, an outlet pipe is provided above the filling material layer 4.
A trough 11 communicating with 10 is provided. In addition, the filler 3 has a smooth granular surface, has no irregularities, and has a specific gravity of 1.
Those having a particle size of 0 to 1.5 and a particle size of 5 mm or more, for example, natural stone is crushed and the specific gravity is adjusted to granulate, fired artificial stone, granulated, fired brick, or granular plastic. Here, the shape of the filler 3 is a smooth surface granular material,
In order to maintain an appropriate porosity of the filler layer 4 and to allow the filler layer 4 to smoothly flow during cleaning, which will be described later, it is desirable that the filler layer 4 has a substantially spherical shape.

Paper containing organic matter and fine fiber waste by the device of the present invention
In order to treat pulp wastewater, the sprinkler pipe 7 is connected via the raw water pipe 5.
The water to be treated flows in from the hole of (1) and the air flows in from the hole of the sprinkling pipe 9 via the air pipe 8. By doing so, the organic matter in the water to be treated is biologically oxidized by the action of the aerobic microorganisms grown on the filler layer 4, and the treated water from which the organic matter has been removed can be obtained from the outlet pipe 10 through the trough 11. it can. In this embodiment, the water to be treated flows into the filler layer in an upward flow, but since the particle diameter of the filler is 5 mm or more, usually 5 mm to 30 mm, it is relatively large, so the specific gravity of the filler used is large. Even if is close to 1.0, the filler layer does not float and flow at a normal treatment flow rate, and a filler layer that sediments in the treated water is formed. Moreover, since the granular material having a smooth surface is used as the filler 3, there is no uneven portion unlike the conventional natural gravel or crushed stone, and the fine fiber waste contained in the water to be treated is unlikely to be caught in the filler 3. Most of the material passes through the filler layer 4.

When granulated and fired artificial stone is used as the filler 3 used in the present invention, a crack may be formed on the surface when the artificial stone is granulated and fired. Even if is formed, this crack is filled with the microorganisms that settle, and the catching of fine fiber scraps or the like does not occur.Therefore, the surface of the present invention has a crack on such a surface as a smooth granular material. What is formed is also included in the range.

If the treatment as described above is continued, the filler layer 4 is clogged due to the enlargement of aerobic microorganisms and the slight accumulation of SS in the water to be treated. More wash water and / or wash air from the air diffuser 9 through the air pipe 8 is introduced at a flow rate of about 3 to 6 times the water flow rate or the air flow rate during normal processing to eliminate clogging.
At this time, since the packing material 3 having a specific gravity of 1.0 to 1.5 is used, the packing material 3 is easily floated by the upward flow of the cleaning water and / or the cleaning air close to the specific gravity of the water in the tank 1, and the packing material 3 Are separated from each other and the filling material tank 4 causes a gentle flow.
Due to the mutual separation of the fillers 3, some SS accumulated between the fillers 3 is easily expelled above the filler tank 4, and the fillers 3 are filled due to a slight collision between the fillers 3 due to the flow of the filler layer 4. The surplus aerobic microorganisms that have settled on the surface of the material 3 are peeled off and easily expelled above the filler layer 4, and the clogging of the filler layer 4 is eliminated. Thus the filler layer 4
Surplus aerobic microorganisms and some
SS is discharged to the outside of the system from the outlet pipe 10 via the trough 11.

Here, the specific gravity of the filler 3 is set to 1.0 to 1.5 because the specific gravity is 1.
When it is less than 0, the filler 3 is always in a floating state even after the microorganisms adhere to the surface of the filler 3, and when the cleaning water and / or the cleaning air flows in as an upward flow, the filler 3 troughs 11
If the specific gravity of the filling material 3 exceeds 1.5, the washing water and / or the washing air will flow at a considerably high flow rate in order to give a gentle flow to the filling material layer 4 during washing. This is because it has to flow in and waste energy.

The most effective cleaning method for cleaning the filler layer 4 in the apparatus of the present invention is as follows. First, only the cleaning air is flowed in from the air diffuser 9 through the air pipe 8 for 3 to 15 minutes, the filler 3 is separated from each other by the rising flow of the cleaning air, and the filler layer 4 is caused to flow to fill the fillers 3 with each other. Lightly collide with each other to make some SS accumulated between the fillers 3 in a floating state, and strip off surplus aerobic microorganisms grown on the surface of the filler 3. Next, wash air is introduced from the air diffuser pipe 9 via the air pipe 8 and wash water is introduced from the sprinkler pipe 7 via the wash water pipe 6 for 5 to 20 minutes at the same time, and the wash air and the wash water rise due to the wash air. In addition to causing the same effect as in the case of only inflow of flushing water, a small amount of SS accumulated between the fillers 3 due to inflow of washing water and excess aerobic microorganisms peeled off from the surface of the filler 3 are expelled from the filler layer 4. , Through the trough 11 to the outside of the system through the outlet pipe 10.

As described above, by first providing the cleaning process using the cleaning air alone and then the cleaning process using both the cleaning air and the cleaning water, some of the SS accumulated between the fillers 3 is floated, and excess SS is generated from the surface of the filler 3. The aerobic microorganisms can be stripped off, the SS and surplus aerobic microorganisms from the filler layer 4 can be effectively removed, and a washing process using only washing air can be performed to significantly reduce the washing water. be able to.

An example of applying the present invention to a submerged filter apparatus using aerobic microorganisms has been described above. However, even when the present invention is applied to a submerged filter apparatus using anaerobic microorganisms, the upper part of the tank 1 is sealed. The generated gas is collected, and the collected gas is introduced from the hole of the air diffuser 9 instead of the air, which is the same as the submerged filter apparatus using aerobic microorganisms, and thus detailed description thereof will be omitted.

<Example 1> A tank having a width of 8 m, a length of 8 m and a height of 5 m has a particle size of 20 to 30 mm and a specific gravity of 1.
We treated raw synthetic wastewater from an integrated pulp and paper mill in a submerged filter apparatus using aerobic microorganisms with a nearly spherical artificial stone as a filler and the height of the filler layer was 3.5 m. As a result, inflow SS was 250 mg /, while outflow SS was 200-300 mg /
Therefore, most of the fine fiber waste contained in the inflow water easily passed through the filler layer and flowed out, and it was possible to obtain a good result in which the fine fiber waste was not captured in the filler layer. The BOD at this time is 300 mg / influent water and 8 outflow water.
It was 0 mg /, and the BOD removal rate was 73%.

<Example 2> Submerged filter apparatus A using aerobic microorganisms having a particle size of 5 to 15 mm and a specific gravity of 1.2 as a substantially spherical artificial stone and having a height of the filler layer of 3.2 m (Example of the present invention) ), Particle size 20 to 30 mm, specific gravity
The natural crushed stone of 2.6 is used as the filler, and the height of the filler layer is 3.2m.
Immersion filter bed device B using conventional aerobic microorganisms (conventional example)
The papermaking wastewater containing fine fiber waste was continuously flowed into it to intentionally create a closed state of the filler layer. Then, both devices were washed with air alone and then with water / air in combination under the same conditions once a day, and the rise from the closed state was compared. As a result, as shown in FIG. 2, the immersion filter bed A returned to the original performance with a COD removal rate of 60% in about 3 days, but the immersion filter bed B showed a COD removal rate even after 10 days. Four
It was 0%, and there was partial blockage that could not be resolved by washing.

<Effect> As described above, in the present invention, when the paper / pulp wastewater is treated by the dipping filter device, the filler is a granular material having a smooth surface and a specific gravity of 1.0 to 1.5 and a particle diameter of 5 mm or more. By using the product, the fine fiber waste contained in the paper / pulp wastewater is unlikely to be caught in the filler, and even if it is trapped in the packed bed, it can be easily discharged out of the system by washing. This is possible, and there is no need to provide a coagulation-sedimentation step or the like in the previous stage of the immersion filter bed device as in the conventional case. Further, when the filler layer of the device of the present invention is washed, by first performing air alone and then using water and air together, it is possible to significantly reduce the washing water and perform more effective washing.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing an example in which the present invention is applied to a submerged filter apparatus using aerobic microorganisms, and FIG. 2 is a rise from a closed state of a filler layer of the present invention apparatus and a conventional apparatus. FIG. 1 ... Tank, 2 ... Floor plate 3 ... Filling material, 4 ... Filling material layer, 5 ... Raw water pipe, 6 ... Washing water pipe, 7 ... Sprinkling pipe, 8 ... Air pipe, 9 ... Diffusing pipe, 10 ...... Exit pipe 11 …… Trough

Claims (1)

[Claims] 1. A filling material layer is formed by filling a filling material having microorganisms grown on its surface to form a filling material layer, and a paper / pulp wastewater containing organic matter and fine fiber wastes is introduced into the filling material layer for biological treatment. In a biological treatment apparatus of the immersion filter bed method for removing organic matter by treatment, the surface is a granular material having a smooth surface, and it sediments during the treatment of water to be treated to form a fixed filler layer. Rinsing water and / or cleaning air from the bottom easily floats during cleaning. Specific gravity 1.0 to 1.5, particle size 5 mm.
An immersion filter bed biological treatment apparatus comprising the above-mentioned filler.