JP2960282B2 - Gravity filtration device using long fiber bundle and cleaning method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to tap water for industrial works, sewage, river water, lake water, lake sedimentation, coagulated sedimentation supernatant water, intermediate water for various processes, various recovered water such as recovered water in papermaking process, various wastewater, biological treatment. The present invention relates to a gravity type filtration device using a long fiber bundle for removing suspended matter in a liquid to be treated such as treated water or a valuables-containing liquid, sake, oil or the like of the device at a high flow rate, and a cleaning method thereof.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 2-149305 discloses a filter using a long fiber bundle.

[0003] In this filtration apparatus, a perforated plate is horizontally provided in a filtration tower in a watertight manner, and a nozzle in which a long fiber bundle is bundled is fixed to each hole of the perforated plate. In the undiluted solution containing the suspension, the free fiber is in an upright floating state with its tip as a free end. However, it does not bend horizontally, but captures suspended matter in the voids in the long fiber bundle and discharges filtered water through the nozzle from the lower part of the perforated plate to the outside of the tower.

[0004]

The filtering device using the long fiber bundle can make the flow rate of the liquid to be treated extremely high as compared with a filtering device such as a conventional packed bed type filtering device.
Also, the washing step by backwashing or the like can be completed in a very short time, but when exchanging long fiber bundles, a troublesome operation of removing the end plate and the like of the filtration tower is required.

[0005] In addition, when the filtration device is used as a gravity filtration device, there are the following various problems.

First, in the case of performing filtration by gravity, if the long fiber bundles are packed too densely, the pressure loss becomes too large and the filtration flow rate cannot be increased. To increase the filtration flow rate, it is necessary to coarsen the filling of the long fiber bundle. However, if the packing density is increased, there is a problem that the suspended matter leaks particularly at the beginning of filtration.

Therefore, when gravity filtration is performed using a long fiber bundle, it is necessary to solve the above-mentioned problem.

[0008] When gravity filtration is performed, a certain level of water is required at the upper part of the long fiber bundle. At the end of the filtration, air is introduced from the lower part of the long fiber bundle to remove the suspended matter trapped in the long fiber bundle. At the time of peeling, it is necessary to increase the discharge pressure of the blower because there is water up to the water level described above.
It must set up a blower.

It is an object of the present invention to provide a gravity filtration apparatus using a long fiber bundle in which the long fiber bundle can be easily replaced.

[0010] Another object of the present invention is to provide a washing method capable of obtaining a filtrate having high clarity from the beginning of filtration without increasing pressure loss so much when gravity filtration is performed using a long fiber bundle. It is to disclose.

It is still another object of the present invention to disclose a cleaning method capable of sufficiently agitating long fiber bundles with a blower having a relatively low head.

[0012]

SUMMARY OF THE INVENTION A gravity filtration apparatus using a long fiber bundle which achieves the object of the present invention comprises a filtration tank having an upper opening and a space at the bottom in the filtration tank. A filter body provided with a filter medium made of a long fiber bundle having an upper end as a free end in a frame arranged detachably, a cleaning air pipe communicating with a bottom space of the filter tank, and an upper part of the filter tank. A treatment liquid supply port provided, a discharge pipe for discharging a filtrate connected to the bottom space of the filtration tank to the outside of the tank, and discharging the liquid in the filtration tank to the outside of the tank above the filter medium. A trough for maintaining a constant liquid level, the liquid to be treated supplied from the liquid to be treated supply port into the filtration tank is filtered through the filter by gravity, and the filtrate is passed through the discharge pipe. It is characterized by discharging. In addition, the method of cleaning a gravity type filtration device using the long fiber bundle is such that the liquid in the filtration tank is discharged from the trough, the liquid level is lowered to the trough, and the long fiber bundle is blown by air from the cleaning air pipe. After performing the washing, the air washing and washing of the long fiber bundle by the upward flow of the washing water are performed, and further,
After the completion of the washing step, the water in the filtration tank is drained to a liquid level slightly above the tip of the long fiber bundle or to a liquid level at which part or all of the long fiber bundle is exposed.

[0013]

DETAILED DESCRIPTION FIG. 1 is a schematic view showing an embodiment of a filtration equipment, FIG. 2 A in Figure 1 - shows a detailed view of the A line cross-section.

Reference numeral 1 denotes a biological treatment apparatus in which three aerobic contact oxidation tanks are arranged in parallel in a filtration tank 1a and filled with a filler 1b for supporting microorganisms formed of gravel, crushed stone, inorganic or organic molded products. The stock solution supplied from the lower part of each filter tank 1a and the air for respiration of microorganisms are subjected to biological treatment through the filler 1b by ascending flow, and the processing liquid is discharged from the upper part of the tank 1a to the outside of the tank. A discharge groove 1c is formed at the upper part of the outer periphery of the tank 1a of the biological treatment apparatus 1, and the processing liquid discharged from the upper part of the tank 1a is sent to the discharge groove 1c so that a certain head is held.

Reference numeral 2 denotes a filtration device for performing filtration using the treatment liquid of the biological treatment device 1 as a liquid to be treated, and a filtration tank 2a having an open top.
A plurality (8 in this embodiment) of gravity type filtration devices A in which long fiber bundles are arranged as filter media 2b are provided. The discharge groove 1c is located above each filtration tank 2a of the filtration device 2,
The processing liquid of the biological treatment apparatus, which is the liquid to be processed, is dropped and supplied to each filtration tank 2a through a valve (not shown) provided for each filtration tank 2a. It has become. In the present embodiment, the biological treatment device 1 and the filtration device 2 are both made of concrete, and are integrally formed as shown in FIG.

The filter media 2 b composed of long fiber bundles arranged in the filtration tank 2 a are provided in four individually removable frames 3, and each frame 3 is further divided into four by a partition plate 4. It is divided into sections. The bottom 3a of the frame 3 is formed of a perforated plate, and a nozzle 2c serving as a base of a long fiber bundle 2b as a filtering material is attached to a hole of the perforated plate.
The frame 3 is positioned so that a flange 2e formed on the upper outer periphery of the frame 3 abuts on a step 2d formed on the inner wall surface of the filtration tank 2a in order to facilitate the upward extraction. For example, it can be easily fixed by, for example, passing a hole formed in the flange portion through a bolt implanted in the step portion and screwing it with a nut.

A space 5 is formed between the bottom 3a of the frame 3 and the bottom of each filtration tank 2a as shown in FIG.
Inside a pair of air pipes 6a, 6 used in the cleaning process.
b are connected in parallel, and the filtrate in the space 5 is discharged out of the tank through the discharge pipe 7. In the present embodiment, the filtration device is provided with a cleaning drainage tank 8 for storing the cleaning drainage generated during the cleaning step below the filtration tank 2a.

On the other hand, a trough 9 for draining liquid is arranged above the frame 3 so as to lower the liquid level in the filtration tank 2a to a certain level at the start of the washing step.

The filtering device comprising a plurality of gravity type filtration tanks 2a using the above-mentioned long fiber bundle as a filtering material is provided with a plurality of filtration tanks 2a.
While cleaning any filtration tank 2a of a has been Rotating Activation operation for performing the filtration process by the remaining filtration tank 2a, for the filtration tank 2a in the filtration step,
The liquid to be treated is dropped and supplied.

Since the filtration head 2b of the long fiber bundle has a very low head loss, the filtration speed of the liquid to be treated in the filtration tank 2a can be increased. In addition, filtration by a long fiber bundle captures suspended matter in voids in the long fiber bundle. However, when the amount of captured suspended matter increases, as shown in FIG. As the shrinkage in the direction increases, a large number of long fiber bundles overlap as a whole and the pressure loss increases, so that the filtration capacity reaches the limit and removes suspended matter attached to the long fibers. A cleaning step is required, and the supply of the water to be treated to the filtration tank 2a that requires cleaning is stopped.

Hereinafter, the cleaning step will be described with reference to FIG.

In order to obtain a filtrate having a constant flow rate, the water head (liquid level) in the filtration tank 2a gradually increases as the filtration capacity of the filter medium 2b composed of long fiber bundles decreases. As shown in FIG. 3 (a), a predetermined limit head H1 is set.
Then, the filtration step is stopped, a valve (not shown) of a pipe (not shown) leading to the trough 9 is opened, and a valve (not shown) of FIG.
As shown in the figure, the liquid level in the filtration tank 2a is changed to the liquid level H of the trough 9.
2 to improve the efficiency of the cleaning process shown in FIGS. 3 (c) to 3 (e).

The washing step is first although the air cleaning shown in FIG. 3 (c) is carried out, need a large source of compressed air capacity to supply air at a time both of a pair of air pipes 6a and 6b When air is supplied only to the air pipe 6a on one side and the inside of the long fiber bundle is supplied through the nozzle 2c which forms the base of the air tube 6a, the adhered matter such as a suspended matter adhered to the surface of the long fiber bundle Is started, and the long fiber bundle row on one side that has shrunk and overlapped stands upright. Then, by supplying air only to the air pipe 6b on the other side, the long fiber bundle row on the other side is erected. At this time, the liquid level in the filtration tank 2a is H2
Since the pressure has been lowered to that, the pressure of the supplied air can be reduced accordingly.

Subsequently, as shown in FIG. 3 (d), mixed washing of water washing by the upward flow and the above-described air washing is performed. Although considerable cleaning is performed in the cleaning process up to this point,
For final cleaning, as shown in FIG. 3E, water cleaning using only water can be performed. During the above-mentioned cleaning process, the valve of the trough 9 is in an open state, and the cleaning drainage generated at that time is stored in the cleaning drainage tank 8 via the trough 9 and a pipe (not shown).

By the water washing shown in FIG. 3 (e), the long fiber bundles are brought into an upright state by the upward flow of the washing water upward from the base thereof. Since the voids formed by the individual long fibers are relatively large, the efficiency of capturing suspended matter in the water to be treated is poor in this state.

Then, after the final water washing is completed, the water in the filtration tank 2a is drained from the discharge pipe 7 by descending flow, and the water level is raised from H2.
When lowered to H3, the water level slightly above the tip of the long fiber bundle, the long fiber bundle shrinks in the height direction but does not bend horizontally, and overlaps each other moderately and is good for trapping suspended matter. To form a suitable gap.

In order to form the above-mentioned good voids, the same can be achieved even if the drainage is performed until a part or the whole of the long fiber bundle is exposed.

Thus, the washing process is completed, and the process stands by for the filtration process.

If the filtration performance cannot be recovered even after the washing step, the long fiber bundle needs to be replaced. In this embodiment, since the four frames 3 are removably arranged in the filtration tank 2a, it is only necessary to take out only the frame 3 in which the long fiber bundles requiring replacement are arranged. At this time, since the upper portion of the filtration tank 2a is open, the frame 3 can be directly taken out by a simple operation of simply removing the trough 9.

The four frames 3 may be individually detachable from the filtration tank 2a, or the four frames 3 may be connected to each other by bolts or the like to be integrated and taken out. .

Further, in this embodiment, a filtration device using a long fiber bundle is installed at the subsequent stage of the biological treatment device, and the treated water of the biological treatment device at the preceding stage is used as a liquid to be treated. due to the gravity filtration using a pump for pumping up above the filtration tank 2a of the liquid to be treated is not
It becomes important .

It is needless to say that the water to be treated may be directly supplied to the filtration device using the long fiber bundle for filtration.

[0033]

As described above, according to the gravity filtration apparatus using the long fiber bundle of the present invention, the long fiber bundle is provided on the frame which is open at the top and which is detachably disposed. This eliminates the need for any troublesome work such as removing the end plate, etc. as in a conventional pressure-type filtration device using a long fiber bundle, and the long fiber bundle can be removed together with the frame simply by removing the trough. The operation of replacing the fiber bundle becomes extremely easy.

In the washing operation, the liquid in the filtration tank is previously discharged from the trough at the end of the filtration step, so that the blower head when injecting air from the lower part of the long fiber bundle can be reduced. When a plurality of air pipes are arranged in the bottom space of the filtration tank, air can be separately injected from the plurality of cleaning air pipes, whereby the capacity of the blower can be reduced.

When the long fiber bundle is applied to a gravity filtration device, if the long fiber bundle is packed too densely, the pressure loss becomes too large, so that the filtration flow rate cannot be increased so much. When trying to increase the filtration flow rate by coarsely filling, the suspension leaks at the beginning of filtration, but according to the washing method of the present invention, even if the long fiber bundle is roughly filled to some extent to increase the filtration flow rate, After washing, prior to the filtration step, the water in the filtration tank is extracted to a level slightly higher than the tip of the long fiber bundle, so the long fiber bundles shrink slightly in the height direction and overlap with each other appropriately, so filtration is performed. It is possible to obtain a good filtrate in which the suspension does not leak from the beginning.

Further, when the washing and drainage tank is installed below the filtration tank, the installation area can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a filtration facility capable of effectively implementing the present invention.

A line detailed cross-sectional view - Figure 2 A in Figure 1.

FIG. 3 is a schematic diagram showing a regeneration step and the like of the secondary filtration device shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biological treatment apparatus 1a Filtration tank 1b Filler 1c Discharge groove (liquid supply port to be treated) 2 Filtration apparatus 2a Filtration tank 2b Filtering material 2c Nozzle 2d Step 2e Flange 3 Frame 3a Bottom 4 Partition plate 5 Vacancy 6a, 6b Air pipe 7 Drain pipe 8 Washing drain tank 9 Trough

Claims (7)

(57) [Claims] 1. A filter medium comprising a filter tank having an upper open end, and a long fiber bundle having an upper end as a free end is disposed in a frame body which is detachably disposed so as to have an empty space at the bottom in the filter tank. The provided filter body, the washing air pipe communicating with the bottom space of the filtration tank, the treatment liquid supply port provided at the top of the filtration tank, and the filtrate connected to the bottom space of the filtration tank. A discharge pipe for discharging the liquid outside the tank, and a trough for discharging the liquid in the filtration tank to the outside of the tank above the filter medium and maintaining a constant liquid level,
A gravity type filtration method using a long fiber bundle, characterized in that the liquid to be treated supplied into the filtration tank from the liquid to be treated supply port is filtered through the filter by gravity, and the filtrate is discharged through the discharge pipe. Filtration equipment. 2. A gravity filtration device using a long fiber bundle according to claim 1, wherein the liquid supply port to be treated is connected to a drainage means of a water treatment device arranged in a preceding stage. 3. A gravity filter using a long fiber bundle according to claim 1, wherein a plurality of washing air pipes are arranged in parallel in a bottom space of the filtration tank. 4. A gravity filtration device using a long fiber bundle according to claim 1, further comprising a washing drainage tank for storing washing wastewater below the filtration tank. 5. A method for cleaning a gravity filtration device using a long fiber bundle according to claim 1, wherein the cleaning step includes discharging the liquid in the filtration tank from the trough and lowering the liquid level to the trough. Washing the long fiber bundle with air from the washing air pipe in a state where the long fiber bundle is washed by the air washing and the rising flow of the washing water. Method of cleaning the filtration device. 6. After completion of the cleaning step according to claim 5,
A gravity filtration device using a long fiber bundle characterized in that water in the filtration tank is withdrawn to a liquid level slightly above the end of the long fiber bundle, or to a liquid level at which a part or all of the long fiber bundle is exposed. Cleaning method. 7. The cleaning of a gravity type filtration device using a long fiber bundle according to claim 5, wherein the air cleaning is performed by alternately supplying cleaning air to a pair of air pipes arranged in parallel. Method.