JPH02227189A - Biological treatment apparatus - Google Patents

Abstract

PURPOSE:To make the clogging of a packing material hard to generate and to drastically enhance the concn. of bacteria in a tank by vertically providing filament bundles each composed of single filament aggregates throughout the tank as a packing material so that the lower ends of said bundles are fixed to the support provided to the lower part of the tank and the upper ends thereof are made free. CONSTITUTION:Water to be treated is allowed to flow in from a water sprinkling pipe 7 through a raw water pipe 5 to pass through a packing material bed as a rising stream from the lower end parts of long fiber bundles 3 to the upper end parts thereof and aerating air flows in from the perforations of an air diffusion pipe 9 through an air pipe 8. During a time when the inflow water to be treated rises through the packing material bed 4, the org. substance in the water to be treated is biologically oxidized and decomposed by the action of aerobic bacteria adhered to the surfaces of single filaments constituting the filament bundles 3 and the purified treated water is obtained from an outlet pipe 10 through a trough 11. The inflow air rises in the tank 1 as air bubbles to be discharged into the open air. SS in the water to be treated is partially caught by the filament bundles 3 but the greater part of SS passes through the filament bundles 3 to rise and flows out from an outlet pipe 10 along with treated water.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention involves introducing water to be treated containing pollutants such as organic matter and nitrogen components into a tank filled with a filler for adhesion of microorganisms. This invention relates to a submerged filter biological treatment device that performs biological treatment under aerobic or anaerobic conditions.

<Conventional technology> Conventionally, methods have been used to remove organic matter (BOD or C0D) contained in water to be treated such as wastewater, or to remove nitrogen components (N
As a biological treatment device that performs nitrification or denitrification of (Ha-N, NO3-N, etc.), it is easy to operate and manage, can perform relatively high-load treatment, and can obtain any removal rate. Submerged filter bed biological treatment devices (hereinafter referred to as submerged filter bed devices) are widely used.

The immersion filter bed device is capable of filtering water from the top or bottom of a filler layer made of gravel, crushed stone, porous artificial stone (for example, calcined aggregate), inorganic materials such as anthracite, or plastics in various shapes such as honeycomb. , the contaminants in the water to be treated are biologically removed by the action of microorganisms (aerobic microorganisms or anaerobic microorganisms) that have grown on the filler layer when the water to be treated contains pollutants such as organic matter and nitrogen components. It decomposes and removes contaminants such as organic matter and nitrogen components, and has the advantage of being able to increase the concentration of microorganisms in the tank to a certain extent compared to so-called floating biological treatment equipment, and therefore being able to treat high loads of pollutants such as organic matter and nitrogen components. ing.

Generally, in such submerged filter bed devices, as the treatment continues, the filler layer becomes clogged due to enlargement of biofilm or accumulation of suspended solids (SS) in the water to be treated, and the filter cannot reach the specified level. The quality of the treated water may deteriorate due to the inability to secure sufficient water flow or, in the case of aerobic microbial treatment, microorganisms become anaerobic, so cleaning water and cleaning gas should be periodically introduced from the bottom of the filler layer. A so-called cleaning operation is performed to eliminate clogging of the filler layer.

<Problems to be Solved by the Invention> However, the conventional submerged filter bed apparatus using the above-mentioned filler has the following problems.

In other words, when granular materials such as gravel or crushed stone are used as fillers, clogging is likely to occur due to the small porosity.
In addition to the above-mentioned problem of increased cleaning frequency, in the case of fillers such as gravel and crushed stone, which have a relatively large specific gravity, the filler will not work even if cleaning water or cleaning gas flows in during cleaning. In the case of filling materials such as artificial stone and anthracite, which have a relatively light specific gravity, it is difficult to fluidize them, and therefore it is difficult to sufficiently eliminate clogging. If the flow rate of the cleaning fluid is increased, the filler may flow out of the tank, and if the flow rate is decreased to avoid this, there is a problem that cleaning will be insufficient.

Furthermore, in the case of plastic fillers in various shapes such as honeycomb, - many have large porosity for boat fishing;
Therefore, it is relatively difficult to cause clogging and is easy to clean, but on the other hand, the surface area per filling volume (d/
Since the ITr (hereinafter simply referred to as surface area) is small, there is a problem that the amount of microorganisms that adhere to the tank is not so large, that is, the concentration of microorganisms in the tank is not so high.

The present invention solves these problems in conventional submerged filter bed devices, and the filling material layer is difficult to clog, and even if it does become clogged, it can be cleaned extremely easily, and the microorganisms in the tank are The object of the present invention is to provide a submerged filter bed device that can dramatically increase the concentration compared to conventional filters.

<Means for Solving the Problems> The present invention, which has been made to solve the above-mentioned problems, provides a submerged filter bed device having a filler for microbial adhesion in the tank, in which a collection of single fibers is used as the filler. The lower end of the long fiber bundle is fixed to a support attached to the lower part of the tank, and the long fiber bundle is erected throughout the tank with its upper end being a free end. This is a biological treatment device that uses

The present invention will be explained in detail below using the drawings.

The drawing is a schematic cross-sectional view showing an example of an embodiment of the present invention, and shows an upflow type submerged filter device using aerobic microorganisms, in which the lower part of a tank l having a circular or rectangular cross section, etc. A support 2 made of a perforated plate or the like is attached to the support 2, and the lower end of a long fiber bundle 3 made of an aggregate of single fibers is fixed to the support 2, and the upper end of the long fiber bundle 3 is set as a free end. By filling the bundles 3 into the tank 1 relatively densely, the long fiber bundles 3 are erected throughout the tank 1 to form a filler layer 4.

Further, in the tank 1 at the lower part of the support 2, there is a water sprinkler pipe 7 with many holes that communicates with the raw water pipe 5 and the washing water pipe 6, and an aeration pipe 9 with many holes that communicates with the air pipe 8. Furthermore, a trough 11 is provided in the tank l above the filler layer 4, which communicates with the outlet pipe 10 of the treated water.

To explain the long fiber bundle 3 used in the present invention, the material is, for example, synthetic fiber such as acrylic fiber, polyester fiber, polyamide fiber, or natural fiber such as cotton or wool, and the length is, for example, 1,000 m to 3,000 m. It is made by assembling a plurality of single fibers.

The thickness of the above-mentioned single fibers is preferably 10μ to 80μ, and usually around 35μ.The long fiber bundle 3 made of such a collection of single fibers has a relatively strong layer, so 1, if the packing density is appropriate, it will not bend horizontally, even if the water to be treated flows downward from the top to the bottom of the long fiber bundle 3. Although the lower part of the long fiber bundle 3 is slightly bent and its height is slightly reduced, it is not bent.

In addition, in the case of the long fiber bundle 3, microorganisms are attached to the surface of each single fiber that constitutes the long fiber bundle 3, and therefore, when ordinary threads or string-like bodies are used as a filler for microorganism attachment. It is possible to obtain a much larger amount of microorganisms than in the conventional method.

Next, to explain the packing density of the long fiber bundle 3, the higher the density, the more surface area per packing volume (
This increases the surface area on which microorganisms can adhere, but pressure loss increases and clogging becomes more likely. Also,
As the packing density decreases, pressure loss decreases and clogging becomes less likely to occur, but conversely, the surface area on which microorganisms can adhere decreases, making it impossible to obtain a high-performance biological treatment device. If the packing density is made smaller, it becomes difficult to stand the long fiber bundle 3 in the tank l. Therefore, there is an optimal range for the packing density of the long fiber bundle 3. For example, when using the long fiber bundle 3 consisting of an aggregate of single fibers with a length of 1.000n to 3.000fl, the volume of the tank 1 is 1 d. 10kg to 100kg (dry weight)
It is preferable to set the packing density so that the long fiber bundle becomes a long fiber bundle.By setting the packing density to such a packing density, the long fiber bundle 3 can be placed upright in the tank 1, and the porosity is higher than that of conventional granular fillers. 2 to 3 times the surface area when used, and the surface area is 10 to 50
It is possible to form a packing material layer that is extremely suitable for a submerged filter bed device.

<Operation> When treating water containing organic matter, for example, using the immersion filter bed apparatus shown in the drawings, the procedure is as follows.

That is, the water to be treated is introduced through the holes of the water sprinkler pipe 7 through the raw water pipe 5, and passed through the filler layer 4 in an upward flow from the lower end of the long fiber bundle 3 to the upper end, and the air pipe 8 is Aeration air is made to flow in from the hole of the aeration pipe 9 through the aeration pipe. While the inflowed water to be treated rises between the filler layers 4, the organic matter in the water to be treated is transformed into living organisms by the action of aerobic microorganisms that have grown on the surface of each single fiber constituting the long fiber bundle 3. Treated water that has been chemically oxidized, decomposed and purified is obtained from the outlet pipe 10 via the trough 11. On the other hand, the inflowing air becomes bubbles and rises inside the tank 1, and is released into the atmosphere as is. Further, although some of the SS contained in the water to be treated is captured by the long fiber bundles 3, most of it passes through the long fiber bundles 3 and rises, and flows out from the outlet pipe 10 together with the treated water.

In this way, when the device of the present invention is of an upward flow type, compared to the case of a device using conventional granular materials, S
Since the rate at which S is trapped or deposited in the filler layer 4 is extremely low and the porosity is high, the filler layer 4 is extremely unlikely to be clogged.

In addition, in the apparatus of the present invention, the long fiber bundle 3 made of an aggregate of single fibers having the diameter as described above is used as the filler, and since the long fiber bundle 3 is packed relatively densely, the calculated surface area is It is 10 to 50 times that of conventional granular fillers or plastic fillers of various shapes, and therefore the amount of microorganisms that can be held within the filler layer 4 can be dramatically increased, making it more effective than conventional fillers. Biological treatment can be performed.

As mentioned above, when the device of the present invention is of the upward flow type, clogging is extremely difficult, but if water continues to flow for a long time, SS will occur.
The amount of trapped water gradually increases, and the biofilm that has grown on the surface of each single fiber constituting the long fiber bundle 3 becomes enlarged, and the filler layer 4 tends to become clogged. Stop and perform the following cleaning.

That is, cleaning air flows in from the aeration pipe 9 via the air pipe 8 at a flow rate greater than the flow rate of aeration air during water flow. Due to the inflow of air, the water in the tank 1 is stirred and the long fiber bundles 3 are vibrated, and the SS trapped between the long fiber bundles 3 is easily separated and becomes a floating state, and the long fiber bundles 3 Excess aerobic microorganisms that have grown on the surface of the single fibers that make up the fibers are also effectively removed.

Next, while continuing the inflow of the air, or after stopping the inflow of the air, wash water is caused to flow into the tank 1 via the wash water pipe 6. Since the lower end of the long fiber bundle 3 is fixed to the support 2 and its upper end is a free end, the upward flow of the inflowing washing water causes the long fiber bundle 3 to use the support 2 as a fixed part. It becomes like a streamer, and each fiber vibrates.

Therefore, the detached surplus aerobic microorganisms and SS cannot remain in the long fiber bundle 3 and are expelled, and the washing wastewater containing a large amount of these suspended matter is discharged from the outlet pipe 10 via the trough 11. Ru.

In the submerged filter bed device of the present invention, the lower end of the long fiber bundle 3 is connected to the support body 2.
Since the upper end is the free end, the long fiber bundle 3 is fixed with a relatively small amount of washing air and washing water.
The long fiber bundle 3 can be easily vibrated or swung, and since the lower end is fixed, even if high-velocity washing water flows in, the long fiber bundle 3 remains in the tank! There is no leakage to the outside, and therefore, the biological treatment device of the present invention can effectively unclog the filler layer 4 in a short time.

In the above-described embodiment, an upflow type submerged filter bed device has been described, but the present invention is a downflow type submerged filter device in which the water to be treated is passed in a downward flow from the upper end of the long fiber bundle as a filler toward the lower end. In that case, the lower part of the long fiber bundle will bend slightly due to the downward flow of the water to be treated, and its height will shrink slightly, but the long fiber bundle as a whole will remain within the tank. Since the upright state can be maintained and the water to be treated passes between the upright long fiber bundles in a downward flow, pressure loss does not increase significantly. In such a downflow type device, while the water to be treated passes through in a downward flow, SS in the water to be treated is captured in the voids of the long fiber bundles,
Therefore, it is more prone to clogging than the above-mentioned upward flow type, but
On the other hand, it has the advantage that less SS flows out into the treated water and clearer treated water can be obtained. however,
The frequency of clogging is lower than that of conventional equipment using granular fillers, and when clogging occurs, the clogging can be sufficiently cleared by cleaning in exactly the same manner as in the case of the upward flow type. There is no problem because it can be done.

Furthermore, the device of the present invention can be used as a submerged filter bed device using anaerobic microorganisms, such as an anaerobic fermentation device. Since it is the same as the submerged filter bed device using aerobic microorganisms except that the air is introduced through the hole of the aeration tube, detailed explanation will be omitted.

Effect> As explained above, since the biological treatment device of the present invention uses a long fiber bundle consisting of an aggregate of single fibers as a filler, each single fiber itself functions effectively as a carrier for microbial attachment. , compared to devices using conventional granular fillers or honeycomb fillers, it is possible to create a submerged filter bed device with an extremely large surface/area, 10 to 50 times larger.
Therefore, the amount of microorganisms retained in the tank can be dramatically increased compared to the conventional method. Moreover, while securing such a large surface area, the porosity is also twice that of conventional granular fillers.
It is possible to increase the amount of water by up to 3 times, and therefore, it is extremely difficult to clog.Especially when the device of the present invention is of an upward flow type, the frequency of cleaning can be extremely reduced.

In addition, even if clogging occurs, the long fiber bundle can be easily vibrated by a relatively small amount of washing water or the inflow of cleaning gas, and therefore, the long fiber bundle can be easily vibrated on the surface of each single fiber that makes up the long fiber bundle. The surplus microorganisms and SS trapped in the long fiber bundles can be effectively removed.

Furthermore, in the present invention, since the lower end of the long fiber bundle is fixed, there is no fear that the filler will flow out of the tank even if washing water flows in at a high flow rate.

Examples will be described below to make the effects of the present invention more clear.

<Example> A perforated plate was attached to the bottom of a steel plate tank with a diameter of 650 fl and a height of 3,000 days (straight part), and the perforated plate had a diameter of 35 μm.
The lower end of a long fiber bundle consisting of an aggregate of acrylic single fibers with a length of 2,400 fl is fixed, and the upper end is a free end. The packing density of the fiber bundle was 25 kg (dry weight >/d), and wastewater with an average BOD concentration of 500 μ/1 was collected from the bottom of the tank at LV = 0, 6 m/H (B OD volume load approximately 3
kg/n? - day), and at the same time, aeration air was flowed in from the bottom of the tank at LV = 15 m/H to perform aerobic biological treatment.

When the system was operated under these conditions for 30 days, the average treated water quality in steady state was BOD 28/l and the average removal rate was 94.4%.

Furthermore, the inflow LV of wastewater is increased to LV=1m/H (BOD
After continuous operation for 15 days under these conditions, the average treated water quality was BO
D41/l (average removal rate 91.8%).

During the above operation, there was no significant increase in pressure loss, and there was no problem with operation.
Twice on the 5th day, water flow was temporarily stopped and the following cleaning was performed.

That is, cleaning air at LV=40m/H is introduced from the bottom of the tank for 3 minutes, and then the inflow of air is stopped and LV-
When the filler layer was washed by flowing washing water at 20 m/h for 3 minutes, it was confirmed that excess aerobic microorganisms could be effectively removed.

For comparison, a particle size of 10 to 30M and a specific gravity of 1.2 were placed in a steel plate tank with a diameter of 650fi and a height of 3.000m (straight section).
Filled with artificial stones to a height of 2,400m,
A conventional upflow type submerged filter apparatus was constructed, and wastewater treatment by the apparatus was carried out in parallel with the above-mentioned treatment and under exactly the same conditions as in the above-mentioned case.

As a result, the average treated water quality when wastewater was passed at LV = 0.6 m/H was BOD 53 ■/l (average removal rate 89.4%), and when LV = 1.0 m/H The average treated water quality was BODl 10/l (average removal rate 78.0%), and both results were worse than in the case of the apparatus of the present invention.

In addition, in the immersion filter device of the comparative example, after the start of operation,
From around day O, the increase in pressure loss due to clogging became noticeable, so from day 10 onwards, the following cleaning had to be carried out regularly once a day.

That is, first, cleaning air is flowed in at LV = 50 m/H for 5 minutes, and then in addition to the air, cleaning water is flowed in at LV = 10 m/H.
/H, and such cleaning using air and water is carried out for 1 hour.
It lasted 0 minutes.

[Brief explanation of the drawing]

The drawing is a schematic sectional view showing an example of an embodiment of the present invention. 1... Tank 2... Support 3... Long fiber bundle 4... Filler layer 5... Raw water pipe
6...Cleaning wood pipe 7...Water pipe
8...Air pipe 9...Diffuser pipe 10...Outlet pipe 11...Trough

Claims (1)

[Claims] 1. Filling a tank with a filler with microorganisms on its surface to form a filler layer, and flowing the water to be treated into the filler layer to make the water In a submerged filter biological treatment device for biological treatment, a long fiber bundle consisting of an aggregate of single fibers is used as the filler, and the lower end of the long fiber bundle is attached to a support attached to the bottom of the tank. A biological treatment device characterized in that long fiber bundles are fixed and erected throughout the tank with their upper ends as free ends. 2. The biological treatment device according to claim 1, wherein a long fiber bundle consisting of an aggregate of single fibers having a thickness of 10 μm to 80 μm is used. 3. 10 to 100 long fiber bundles per 1 m^2 of tank volume
Claim 1: The tank is installed vertically in the tank so that the dry weight is 1 kg (dry weight).
Or the biological treatment device according to claim 2.