JPH10211404A - Apparatus and method for filtration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently wash filter media while a filtration rate is improved by a method wherein in a filter media layer in which raw water is passed through to filter, the filter media of which a specific gravity and a particle size are within specific ranges is used, the height of the filter media layer is specified, and flow velocity of raw water and a turibidity of treated water are specified. SOLUTION: In a filtration apparatus main body 1, a raw water introduction channel 5 is connected to an upper part, a treated water discharge opening 6 is provided to a lower part, and a filter media layer 2 in the filtration apparatus main body 1 is formed to have 1.0 to 1.5m height. As the filter media of the filter media layer 2, for example, anthracite is used, and the anthracite is a granular body of 0.8 to 1.1mm particle size, 1.4 or under uniformity coefficient of the particle size, 2 or under specific gravity, and 50% void ratio. Then, the raw water is filtered at 300m/day flow velocity, and turbidity of the treated water after filtration is 0.1 degree or under. Thereby, when raw water of average 2 degree turbidity is treated, filtration can be carried out for 70h or longer filtration duration time, and in the case of average 0.35 degree turbidity, the filtration can be carried out for 240h or longer filtration duration time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a filtration device and a filtration method for filtering raw water through a filter medium layer made of a granular filter medium used in purification treatment of clean water and sewage.

[0002]

2. Description of the Related Art In recent years, a filtration apparatus for purifying clean water and sewage, particularly a filtration apparatus for obtaining highly purified water, is provided with a filter medium layer filled with a granular filter medium such as sand so as to have a predetermined height. The device is being used.

[0003] That is, this is a filtration device in which sand is filled as a filter medium to a height of about 60 cm to form a single filter medium layer, and raw water is introduced from above the filter medium layer and filtered. The sand used as the filter medium usually has a specific gravity of 2.57 to 2.67, a particle size of about 0.45 to 0.7 mm, and a shape close to a sphere.

[0004]

When raw water is passed through such a filter medium layer of the sand filter medium, the turbidity in the raw water is suppressed mainly on the surface of the filter medium. Then, the clogging of the filter medium is accelerated because the turbidity in the raw water is quickly retained to the limit value. On the other hand, if the height of the filter medium layer is too high, the filtration resistance increases and the filtration speed cannot be increased.

Therefore, an appropriate flow rate of water is determined by the material of the filter medium such as the particle size and specific gravity and the height of the filter medium layer. When the above-mentioned filter medium layer using sand as the filter medium is used, Usually, it was 120 to 150 m / day, and it was difficult to improve the speed of the filtration treatment. In addition, as a method of increasing the flow rate of water flow, there is a method of adding a polymer flocculant to raw water and filtering the water. However, in the case of clean water, the polymer flocculant is mixed with the treated water for safety and sanitation. There was a problem.

[0006] When filtration is continued for a certain period of time and the filter medium is blocked and the filtration capacity is reduced, unfiltered water is stored in the upper part of the filter medium layer. The storage height of the unfiltered water is used as a filtration resistance value as a measure of the processing capacity of the filter medium, and the time until the filtration resistance value reaches a predetermined value is referred to as a filtration continuation time.

[0007] In a usual filtration device, the length of the continuous filtration step is determined by the duration of the filtration, and after the filtration step is continued for a certain period of time, the filtration is stopped and the washing step is performed. In the case of filter media, the amount of untreated water above the filter media is 1
The filtration resistance value is set so as to perform the washing step when it reaches 00 to 200 cm, and the filtration duration is generally 24 to 48 hours as a time. And it was difficult to improve work efficiency.

On the other hand, there is a multi-layer filtration device which uses a plurality of filter media having different specific gravities and particle diameters to reduce the filtration resistance value and enable high-speed filtration. Since the turbid matter is confined at the boundary between the layers, there is a problem that it is complicated to determine the optimum cleaning method for removing the turbid substance and to grasp and manage the amounts of water and air.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a filtration apparatus and a filtration method capable of improving a filtration rate without deteriorating the quality of treated water and further facilitating washing of a filter medium. The task is to provide

[0010]

SUMMARY OF THE INVENTION The present invention has been made as a filtering device and a filtering method in order to solve such a problem, and the feature of the filtering device is that a filtering material layer comprising a single granular filtering material is provided. 2 having a filtration device main body 1 formed with
In a filtration device for filtering raw water by passing raw water through a filtration material layer 2 in the filtration device main body 1, the filtration material has a specific gravity of 2 or less and a particle size of 0.3.
8 to 1.1 mm, and the height h of the filter medium layer 2 is 1.0 to 1.0 mm.
1.5 m, and it is possible to pass raw water through the filter medium layer 2 at a flow velocity (LV) of 300 m / day or more to reduce the turbidity of the treated water after filtration to 0.1 degree or less. It is in.

Further, as another means, a washing water supply part and a gas supply part are formed in the filtration device main body,
When the washing water supply unit and the gas supply unit wash the filter medium layer,
The cleaning water and the gas can be supplied separately or simultaneously to the filter medium layer.

The filtering method is characterized in that a granular filter medium having a specific gravity of 2 or less and a particle size of 0.8 to 1.1 mm has a height of 1.0.
Raw water is supplied to the filter medium layer formed at
/ Day, and the turbidity of the treated water after filtration is set to 0.1 ° or less. Further, another characteristic of the filtering method is that after performing the filtration of the raw water for a certain period of time, the supply of the raw water to the filter medium layer is stopped to lower the water level to a predetermined position, and gas is injected into the filter medium layer from below. Then, the filter medium layer is washed by injecting the gas and the washing water, and further injecting the washing water, and the raw water is again supplied to the filter medium layer to perform filtration.

That is, according to the present invention, the filter medium layer of the filter device main body 1 is formed from a granular filter medium having a specific gravity of 2 or less and a particle size of 0.8 mm or more and 1.1 mm or less, which is lighter and larger than conventional sand.
Since a filter medium layer having a height of 1.5 m was formed, when filtration was performed using this filter medium layer, even if raw water was passed through the filter medium layer 2 at a flow rate of 300 m / day or more, the treated water after filtration was used. The turbidity can be reduced to 0.1 degree or less, the filtration can be performed at a higher speed than the conventional filtration speed, and the quality of the treated water can be maintained at a high level.

Although the height h of the filter medium layer 2 is higher than that of a conventional filter medium layer formed using sand as a filter medium, the filtration speed can be increased, so that the area of the filter device main body 1 can be reduced.

Furthermore, because of the filter medium layer as described above,
When the raw water having an average turbidity of 2 degrees is treated, the filtration duration is 70 hours or more. When the turbidity of the raw water is 0.35 degrees on average, the filtration duration is 240 hours or more. It becomes possible to continue the filtration process continuously without any processing. The term “filtration duration” as used herein means a filtration resistance value of 20
Time to reach 0 cm. The average turbidity refers to the average turbidity when raw water flows for the duration of filtration.

In addition, when the filtration step is continued for a certain period of time, the filtration is stopped, the air is washed first, the filter medium is further washed with washing water and air, and then the filter medium layer is washed only with the washing water. Can be reliably washed, and can be satisfactorily washed because it is a lighter filter medium than a conventional sand filter medium.

Further, since the filter layer is formed deeper than the conventional filter medium layer, it is difficult to clean the entire layer. However, when the air and the reverse cleaning are used as described above, the entire layer can be surely cleaned. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a filter device main body, and an upper portion of the filter device main body 1 is connected to a raw water introduction passage 5 for introducing raw water to be treated into the device main body 1, and a lower portion of the filter device main body. A treated water discharge port 6 for discharging treated water treated in the main body 1 to the outside is provided.

Reference numeral 2 denotes a filter medium layer in which a filter medium is filled in the filter device main body 1, and the height (h) of the filter medium layer 2 is 1.0 to 1..
This is a filter material layer formed of a single material and formed to a length of 5 m.

Anthracite is used as a filter medium of the filter medium layer 2 and has a particle diameter of 0.8 mm.
It is a crushed light granular material having a uniformity coefficient of particle diameter of 1.4 or less, specific gravity of 2 or less, and a porosity of 50%. As described above, this anthracite has a low specific gravity and a large porosity, so that it is not limited to filtering turbid matter on the surface of the filter medium, and also has a large surface area due to a crushed shape instead of a spherical shape. The trapping amount is larger than that of a filter medium such as sand.

Further, since the uniformity coefficient of the particle size is 1.4 or less, the particle size gradient between the coarse filter material and the fine filter material can be reduced, and the filter material is dispersed in an appropriate state without being hardened by the diameter. . That is, in the state of filtration, coarse particles are less likely to be collected in the lower layer and fine particles are less likely to be collected in the upper layer, and the surface layer of the filter material is less likely to be clogged, so that a sufficient filtration duration can be maintained.

Reference numeral 3 denotes a washing water supply pipe for introducing washing water for washing the filter medium layer 2 provided at the bottom of the filter device main body 1 from below, and 4 similarly similarly air-washes the filter medium layer 2 from below. Is an air introduction pipe for introducing air for use.

Next, the filtering apparatus 10 having such a configuration
Is used for the advanced purification treatment of clean water.

First, the untreated raw water is subjected to coarse sediment removal by a sand basin, and then, as shown in FIG.
, A coagulant such as aluminum sulfate is added and the mixture is treated in the precipitation tank 7. The supernatant water subjected to the coagulation and sedimentation treatment is subjected to ozone treatment in an ozone tank 9 to which an ozone generator 8 is connected.

The treated water subjected to the ozone treatment passes through a biological activated carbon treatment tank 11 and a re-coagulation tank 12, and the supernatant treated water is introduced into the filtration device main body 1 of the filtration device 10 through the raw water introduction passage 5 as filtration raw water. Is done. At this time, the turbidity of the filtered raw water is a maximum of 10 degrees, a minimum of 0.1 degrees and an average of about 2 degrees at a predetermined flow rate.

The raw water is introduced into the upper part of the filter medium layer 2 in the filter device main body 1, flows downward in the filter medium layer 2, and is filtered.

The filter medium of the present embodiment is made of anthracite, which has a larger particle size, a lower specific gravity, and is less pulverized because it has a smaller particle size than the above-mentioned conventional filter medium such as sand. Even if the height (h) of the tank 2 is higher than the height of the conventional filter medium layer made of sand, the water permeability of the raw water in the filter medium layer 2 is good, and the height of the filter medium layer 2 can be increased.

When the height of the filter medium layer 2 is increased, the portion where the raw water comes into contact with the filter medium increases, so that a high flow rate, for example, LV3
Even when filtration is performed at a flow rate of 00 m / day, the turbidity of the treated water after filtration is a predetermined value (in this embodiment, the turbidity is 0.1%).
Degree) or less, and the filtration efficiency can be improved while maintaining the quality of the purified water.

When the raw water is continuously introduced into the filter medium layer 2 at a constant flow rate and the filtration process is continued, turbidity in the raw water is suppressed on the surface of the filter medium, and the filtration resistance of the filter medium increases. After the filtration is continued for a certain period of time, it is necessary to periodically wash the filter medium.

The decrease in the filtering capacity of the filter medium is usually represented by the height h 'of the water collected on the upper part of the filter medium layer 2, and the time until the height value (filtration resistance value) reaches 200 cm is called the filtration continuation time. .

Since the filter medium of the present embodiment, ie, anthracite, has a larger diameter than that of a filter medium such as sand, the time until the surface of the filter medium is closed, ie, the filtration continuation time is long.

After the elapse of the filtration continuation time, the supply of the raw water from the raw water introduction passage 5 is stopped to stop the filtration, and the filter medium is washed.

In this cleaning step, first, the water level is lowered to a predetermined position, and then 0.9 m / m
In, air is injected from below the filter medium layer 2 to wash the filter medium with air for one minute. Then, while injecting the same amount of air as above, washing water is injected from the washing water supply pipe 3 at 0.83 m / min, and the filter medium is washed with both the air and the washing water for one minute.

Next, the supply of air and washing water is stopped,
After allowing to settle for 1 minute, this time, backwashing is performed for 10 minutes only with washing water, and after this backwashing, settling is performed again for 1 minute.

After the washing step is completed in this way, the washing water is discharged from the filtering device main body 1, and the filtering step is performed again.

In this washing step, the filter medium is washed while being stirred with air and washing water. However, since the anthracite of the filter medium is a light filter medium having a low specific gravity, it can be easily developed, flowed, or easily stirred, and can be washed well. can do.

In addition, even if the washing step is carried out reliably with air and washing water as described above, since the filter medium layer is a single filter medium layer, it is necessary to maintain the structure of the filter medium like a multilayer filter medium layer. Therefore, the washing and the filtration process after the washing can be performed quickly.

Further, as described above, the filter medium layer 2 is formed deeper than the conventional filter medium layer using sand or the like. Therefore, in order to surely clean the entire filter medium layer, the filter medium layer 2 is more thoroughly cleaned than the conventional filter medium layer. However, the backwashing with the washing water can surely wash the entire layer by performing the air washing stepwise.

After the completion of the washing step, the filtration capacity of the filter medium is restored, so that the raw water is again introduced into the filtration device main body 1 from the raw water introduction path 5 until the filtration resistance value reaches a predetermined value again.
That is, the filtration step can be continuously performed during the filtration continuation time.

In the above embodiment, anthracite is used as the filter medium, but the material of the filter medium is not limited to this, and may be, for example, a filter medium made of synthetic resin, pumice, activated carbon, or the like. In short, any granular filter medium having specific gravity, diameter, and porosity satisfying the above conditions may be used.

Further, in the above embodiment, the filtration device 10 is used for water treatment. However, the filtration by the filtration device of the present invention is not limited to water supply, but is used for sewage treatment such as drainage. May be.

Further, in the above embodiment, the raw water introduced into the filtration device is supplied to the coagulation tank 7a, the settling tank 7, the ozone tank 9,
Although the treated water pretreated by the biological activated carbon treatment tank 11 and the re-coagulation tank 12 was used, it is not a condition to use the treated water that has been subjected to such treatment. I can do it.

[0044]

Next, in the filtration apparatus shown in the above embodiment, first, the turbidity of the treated water after filtration by changing the diameter of the filter medium, the height of the filter medium layer, and the flow rate of the raw water in various ways is determined by a predetermined standard. An experiment was performed to determine whether or not the above condition was satisfied. The results are shown in Table 1.

[0045]

[Table 1]

The raw water before filtration was introduced with an average turbidity of 2 degrees, and whether or not the treated water after filtration had a standard (turbidity of 0.1) was indicated by ×. All types of filter media use anthracite and have particle sizes of 0.8 mm, 1.1 mm,
A 1.5 mm one was prepared.

Further, the flow rate (LV) was set to be constant at 300 m / day, and the height of the filter medium was set to 1 m, 1.5 m and 2 m, respectively, and the experiment was conducted at each filter medium layer height.

Further, the filtration speed is 200 (LV),
Experiments were carried out at a flow rate of 300, 380, 400, 500, and 800 m / day using a filter medium having a particle diameter of 1.1 mm. Further, an experiment was performed by filtering raw water at a flow rate (LV) of 300 and 500 m / day using a filter medium having a particle size of 0.8 mm and 1.5 mm.

As shown in Table 1, the particle size of the filter medium was 0.8 m
In the case of m, the flow rate LV has a processing capacity that satisfies the standard regardless of whether it is 300 or 500 m / day. The experiment was performed with the height of the filter medium layer being 1.5 m.

When the particle size of the filter medium was 1.1 mm, the standard was satisfied up to the flow velocity LV of 380 m / day, but the standard was not satisfied when the flow velocity LV was 400 m / day or more.

Further, when the particle size was 1.5 mm, the treated water after filtration did not satisfy the standard at any flow rate.

From the above results, the height of the filter medium layer was 1.0 m
It was higher, and when the particle size of the filter medium was 0.8 mm and 1.1 mm, the raw water could be filtered to the reference value (turbidity 0.1 degrees or less).

Based on the above results, turbidity of 0.1 to 0.1 mm was obtained using anthracite having a particle size of 0.8 mm and 1.1 mm.
Raw water at 10 degrees was filtered at a flow rate LV of 300 m / day, and the filtration continuation time until reaching a filtration resistance value of 200 cm was measured. The water temperature was measured at 10 ° C. and 30 ° C., respectively. As shown in Table 2, the treated water was below the reference value of 0.1 degrees for any turbidity raw water.

[0054]

[Table 2]

In this case, the filtration continuation time was 48 hours or less at a water temperature of 10 ° C. when the particle size of the filter medium was 0.8 mm, but was 72 hours at a water temperature of 30 ° C. In addition, when the filter medium is 1.1 mm, even when the water temperature is 10 ° C., it takes 72 hours, and when the water temperature is 30 ° C., 168 hours.
It was time.

[0056]

As described above, when the filtration device of the present invention is used, the filtration speed can be increased without lowering the quality of the treated water, so that the filtration efficiency is improved, and in particular, the high-speed filtration device is improved. Suitable as. In addition, since the configuration of the filter medium layer is simple, manufacturing and installation are easy, and manufacturing costs and management and maintenance costs can be reduced.

Further, the filter medium can be easily and reliably washed, and at the same time, since the filtration time is long, the frequency of washing can be reduced and the filtration step can be continuously performed for a long period of time.

Further, since the height of the filter medium layer is higher than that of the conventional filter medium layer formed using sand as the filter medium, and the filtration speed can be increased, the area of the filter device can be reduced.
It is possible to install a filtering device even in a small area.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of a filtration device of the present invention.

FIG. 2 is a flowchart illustrating an example of water treatment using a filtration device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Filter medium layer 3 Cleaning water supply part 4 Gas supply part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01D 29/38 580A

Claims (9)

[Claims] 1. A filter device main body (1) on which a filter medium layer (2) made of a single granular filter material is formed.
(1) In a filtration device for filtering raw water by passing raw water through a filter medium layer (2) in (1), the filter medium has a specific gravity of 2 or less and a particle size of 0.8 to 1.1.
mm, and the height (h) of the filter medium layer (2) is 1.0 to 1.5 m.
And that the raw water can be passed through the filter medium layer (2) at a flow rate (LV) of 300 m / day or more to reduce the turbidity of the treated water after filtration to 0.1 ° or less. Characteristic filtration device. 2. The filtration device according to claim 1, wherein the filtration duration is 70 hours or more when the turbidity of the raw water is 2 degrees on average. 3. The filtration device according to claim 1, wherein the filtration continuation time is 240 hours or more when the turbidity of the raw water is 0.35 degrees on average. 4. A washing water supply unit is provided in the filtration device main body (1).
(3) and a gas supply section (4) are formed, and the cleaning water supply section (3) and the gas supply section (4) supply the cleaning water and the cleaning gas during the cleaning of the filter medium layer (2). Filter media layers separately or simultaneously
The filtration device according to any one of claims 1 to 3, wherein the filtration device is provided so as to be supplied to (2). 5. Raw water is supplied to a filter medium layer having a specific gravity of 2 or less and a granular filter medium having a particle diameter of 0.8 to 1.1 mm formed at a height of 1.0 to 1.5 m by a flow rate (LV) of 300 m / day or more. A filtration method wherein the turbidity of the treated water after filtration is adjusted to 0.1 ° or less. 6. The turbidity of the raw water is 2 degrees on average, and in this case, the filtration duration is 70 hours or more.
The filtration method described in 1. 7. The filtration method according to claim 5, wherein the turbidity of the raw water is 0.35 degrees on average, and in this case, the filtration duration is 240 hours or more. 8. After the raw water is filtered for a certain period,
By stopping the supply of raw water to the filter medium layer, lowering the water level to a predetermined position, injecting gas from below into the filter medium layer, then simultaneously injecting gas and washing water, and further injecting only washing water The filtration method according to any one of claims 5 to 7, wherein the filter medium layer is washed, and raw water is again supplied to the filter medium layer to perform filtration. 9. The method according to claim 5, wherein the filter medium layer is made of a single filter medium, and the filtration is performed without adding a polymer flocculant to the raw water.
The filtration method according to claim 8.