JP3419640B2 - Filtration device and filtration method - Google Patents

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 filtering device and a filtering method for filtering raw water with a filter medium layer made of granular filter medium used in purification treatment of tap water, sewage and the like.

[0002]

2. Description of the Related Art In recent years, purification treatment of clean water or sewage, particularly filtration provided with a filter medium layer filled with granular filter medium such as sand so as to have a predetermined height in a filter device for obtaining highly purified water. The device is in use.

That is, it is a filter 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 for filtration. The sand used as the filter medium has a specific gravity of 2.57 to 2.67, a particle size of about 0.45 to 0.7 mm, and a nearly spherical shape.

[0004]

When raw water is passed through the filter medium layer of such a sand filter medium, suspended matter in the raw water is retained mainly on the surface of the filter medium, so that the flow velocity of the water is too fast. Then, the suspended solids in the raw water are quickly retained up to the limit value, and the clogging of the filter medium is accelerated. Further, if the height of the filter medium layer is too high, the filtration resistance becomes high 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 particle diameter and specific gravity and the height of the filter medium layer. When using the filter medium layer containing sand as described above, It was usually 120 to 150 m / day, and it was difficult to improve the speed of filtration treatment. Also, as a method of improving the flow rate of water flow, there is a method of adding a polymer flocculant to raw water and filtering it. However, in the case of clean water, the polymer flocculant is mixed with treated water for safety and hygiene. There was a problem.

[0006] Further, when filtration is continued for a certain period of time and the filter medium is clogged so that the filtering ability is lowered, unfiltered water is stored in the upper portion of the filter medium layer. The storage height of the unfiltered water is used as a guideline for the treatment capacity of the filter medium as a filtration resistance value, and the time until the filtration resistance value reaches a predetermined value is called the filtration continuation time.

In a normal filtration device, the length of continuous filtration process is determined by this filtration duration, and after the filtration process is continued for a certain period of time, the filtration is stopped and the washing process is carried out. In the case of filter media, the untreated water above the filter media is 1
The filtration resistance value is set so that the washing step is performed when it reaches 00 to 200 cm, and the duration of the filtration is generally 24 to 48 hours, and the filtration step should be continuously performed for a longer period of time. It was difficult to improve work efficiency.

On the other hand, there is also a multi-layer filtration device in which a plurality of filter media having different specific gravities and particle sizes are used to reduce the filtration resistance value and enable high-speed filtration. In the case of such a multi-layer filtration device, each filter media is used. Since the suspended matter is retained at the boundary of the layers, there is a problem that it is complicated to grasp the optimal cleaning method for removing the suspended matter and the amount of water and the amount of air and control.

The present invention has been made to solve the above-mentioned problems, and a filtration device and a filtration method capable of improving the filtration rate without lowering the quality of treated water and satisfactorily washing the filtration medium. The challenge is to provide.

[0010]

The present invention has been made as a filtering device and a filtering method in order to solve such problems, and the characteristic of the filtering device is that the filtering material layer is composed of a single granular filtering material. 2 has a filtering device body 1 formed with
In a filtering device for filtering raw water by passing raw water through a filtering medium layer 2 in the filtering device body 1, the filtering 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
It should be possible to reduce the turbidity of treated water after filtration to 0.1 m or less by forming raw water at a flow rate (LV) of 300 m / day or more and passing it through the filter layer 2 It is in.

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

The characteristic of the filtration method is 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.
The flow rate of 300 m of raw water is applied to the filter media layer formed to ~ 1.5 m.
Per day, and the turbidity of the treated water after filtration is set to 0.1 degrees or less. Another feature of the filtration method is that after the raw water is filtered 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 a gas is injected from below to the filter medium layer. Then, the gas and the cleaning water are sprayed, and further the cleaning water is sprayed to clean the filter medium layer, and the raw water is again supplied to the filter medium layer for filtration.

That is, according to the present invention, the filter medium layer of the filter device main body 1 has a specific gravity of 2 or less and a particle size of 1.0 to 1.0 from a lighter and larger granular filter medium than the conventional sand having a particle size of 0.8 mm or more and 1.1 mm or less.
Since a filter material layer with a height of 1.5 m was formed, when filtration is performed using this filter material layer, even if the raw water is passed through the filter material layer 2 at a flow rate of 300 m / day or more, the treated water after filtration is filtered. The turbidity can be set to 0.1 degree or less, the filtration process can be performed at a higher speed than the conventional filtration rate, and the quality of the treated water can be kept high.

Further, although the height h of the filter medium layer 2 is higher than that of the filter medium layer formed by using the conventional sand as the filter medium, the filtration speed can be increased, so that the area of the filter device main body 1 can be made small.

Further, since it is the filter medium layer as described above,
When the raw water has an average turbidity of 2 degrees, the filtration duration is 70 hours or longer, and when the raw water has an average turbidity of 0.35 degrees, the filtration duration is 240 hours or longer and the filter medium is washed for a long time. It becomes possible to continue the filtration process continuously without using. The filtration duration is the filtration resistance value of 20.
It means the time to reach 0 cm. Further, the average turbidity means the average turbidity when the raw water is allowed to flow for the filtration duration time.

In addition, when the filtration is stopped after continuing the filtration step for a certain period of time, washing with air is first performed, and then the filter medium is washed with wash water and air, and then the filter medium layer is washed only with the wash water. Can be surely washed, and particularly because it is a lighter filter medium than the conventional sand filter medium, it can be favorably washed.

Further, since it is formed in a deeper layer than the conventional filter medium layer, it is difficult to wash the entire layer, but when air and back washing are used as described above, the entire layer can be surely washed. .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

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

Reference numeral 2 is a filter medium layer in which a filter medium is filled inside the filter body 1, and the height (h) of the filter medium layer 2 is 1.0 to 1.
It is a filter medium layer made of a single material and formed to 5 m.

An anthracite is used as the filter medium of the filter medium layer 2, and the anthracite has a particle size of 0.8 mm.
It is a crushed light granular body having a particle diameter uniformity coefficient of 1.4 or less, a specific gravity of 2 or less, and a porosity of 50%. As mentioned above, this anthracite has a low specific gravity and a large porosity, so it does not stop at filtering the suspended matter on the surface of the filter medium. The amount of trapped is larger than that of a filter medium such as sand.

Further, since the uniform coefficient of particle size is 1.4 or less, the particle size gradient between the coarse-grained filter medium and the fine-grained filter medium can be made small, and the filter medium is dispersed in a proper state without being solidified depending on the diameter. . That is, in the filtered state, coarse particles are less likely to gather in the lower layer and fine particles are less likely to be gathered in the upper layer, and the surface layer of the filter medium is less likely to be blocked, 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 filtering device body 1 from below, and 4 similarly air-washes the filter medium layer 2 from below. It is an air introduction pipe for introducing air for.

Next, the filtration device 10 having such a configuration
The case where is used for advanced purification treatment of tap water will be described.

First, after the untreated raw water is subjected to removal of coarse dust by a sand basin, as shown in FIG.
In, a coagulant such as aluminum sulfate is added and treated in the precipitation tank 7. The supernatant water that has been subjected to the coagulation sedimentation treatment is subjected to ozone treatment in an ozone tank 9 to which an ozone generator 8 is connected.

Then, the treated water that has been subjected to the ozone treatment passes through the biological activated carbon treatment tank 11 and the re-aggregation tank 12 and the supernatant treated water is introduced as filtration raw water into the filtration device main body 1 of the filtration device 10 through the raw water introduction passage 5. To be done. At this time, the turbidity of the raw water for filtration is 10 degrees at maximum, 0.1 degree at minimum, and about 2 degrees on average at a predetermined flow rate.

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

The filter medium of the present embodiment has a larger particle size than the conventional filter medium such as sand, has a small specific gravity, and is crushed, so that the filter medium is made of anthracite which is less flat. Even if the height (h) of the tank 2 is made higher than that of the conventional filter medium layer made of sand, the water permeability of the raw water 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 the flow velocity is high, for example, LV3.
Even when filtered at a flow rate of 00 m / day, the turbidity of the treated water after filtration has a predetermined value (in the case of the present embodiment, the turbidity is 0.1
It is possible to improve the filtration efficiency while maintaining the quality of 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, suspended matter in the raw water is retained on the surface of the filter medium and the filtration resistance of the filter medium increases. It is necessary to wash the filter medium periodically after continuing the filtration for a certain period.

The decrease in the filtering ability of the filter medium is usually expressed by the height h'of the water accumulated on the upper part of the filter medium layer 2. The time until the value of this height (filtration resistance value) reaches 200 cm is called the filtration continuation time. .

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

After the lapse of this filtration duration time, the supply of the raw water from the raw water introducing passage 5 is stopped to stop the filtration, and the filter material washing step is performed.

In this cleaning step, first, the water level is lowered to a predetermined position, and then 0.9 m / m from the air introducing pipe 4.
In, air is jetted from below the filter medium layer 2 to wash the filter medium with air for 1 minute. Then, while injecting the same amount of air as the above, the wash water is jetted from the wash water supply pipe 3 at 0.83 m / min, and the filter medium is washed with both the air and the wash water for 1 minute.

Next, the supply of air and washing water is stopped,
After sedating for 1 minute, this time, backwashing is performed with wash water alone for 10 minutes, and after this backwashing, sedation is again performed for 1 minute.

After the cleaning process is completed in this way, the cleaning water is discharged from the filtering device body 1 and the filtering process is performed again.

In this washing process, the filter medium is washed with air and washing water while being stirred, but since the anthracite of the filter medium is a light filter medium having a low specific gravity, it is easy to be spread, fluidized or stirred, and washed well. can do.

Even if the cleaning process is reliably performed with air and cleaning 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 multi-layer filter medium layer. Therefore, the washing process and the filtering process after the washing process can be performed promptly.

Further, as described above, since the filter medium layer 2 is formed in a deeper layer than the conventional one using sand or the like, in order to surely wash the entire filter medium layer, the filter medium layer is washed more carefully than the conventional filter medium layer. However, backwashing with washing water can surely wash the entire layer by performing air washing in stages.

After the washing step, the filtering ability of the filter medium is restored, so that raw water is again introduced into the filtering apparatus main body 1 from the raw water introducing passage 5 until the filtration resistance value reaches a predetermined value again.
That is, the filtration step can be continuously performed during the filtration duration time.

Although anthracite is used as the filter medium in the above embodiment, the material of the filter medium is not limited to this, and may be a filter medium made of synthetic resin, pumice, activated carbon or the like. The point is that any particulate filter material having specific gravity, diameter, and porosity satisfying the above conditions may be used.

Further, in the above-mentioned embodiment, the filtering device 10 is used for treating tap water, but filtering by the filtering device of the present invention is not limited to tap water, but is used for treating sewage such as waste water. You may.

Further, in the above-mentioned embodiment, the raw water introduced into the filter is the coagulation tank 7a, the precipitation tank 7, the ozone tank 9,
Although the treated water pretreated by the biological activated carbon treatment tank 11 and the re-agglomeration tank 12 was used, it is not a condition to use the treated water treated in this way, and water that requires wide filtration is treated. You can do it.

[0044]

EXAMPLES Next, in the filtration device shown in the above-mentioned embodiment, first, the turbidity of the treated water after the filtration was carried out by changing the diameter of the filter medium, the height of the filter medium layer, and the flow rate of the raw water to predetermined criteria. An experiment was conducted to determine whether or not the results are satisfied, and the results are shown in Table 1.

[0045]

[Table 1]

As raw water before filtration, one having an average turbidity of 2 degrees was introduced and whether or not the standard (turbidity 0.1) of the treated water after filtration was satisfied was indicated by ◯ ×. Anthracite is used for all types of filter media, and the particle size is 0.8 mm, 1.1 mm,
The thing of 1.5 mm was prepared.

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

Further, the filtration rate is 200 (LV),
An experiment was conducted using a filter medium having a particle size of 1.1 mm for each flow rate of 300, 380, 400, 500, 800 m / day. Further, an experiment was conducted 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 is 0.8 m.
In the case of m, the processing capacity satisfying the standard is obtained when the flow rate LV is either 300 or 500 m / day. In addition, the height of the filter medium layer was 1.5 m in the experiment.

Further, when the particle size of the filter medium was 1.1 mm, the result satisfied the standard up to the flow rate LV of 380 m / day, but did not satisfy the standard at the flow rate LV of 400 m / day or more.

Further, at a particle size of 1.5 mm, the treated water after filtration did not meet the standard at any flow rate.

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

Based on the above results, using anthracite having a particle size of 0.8 mm and 1.1 mm, the turbidity of 0.1
Raw water of 10 degrees was filtered at a flow rate LV of 300 m / day, and the filtration duration time until the filtration resistance value reached 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 standard value of 0.1 degree in any raw water of turbidity.

[0054]

[Table 2]

In this case, the duration of filtration 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 it was 72 hours at a water temperature of 30 ° C. When the filter medium is 1.1 mm, it takes 72 hours even when the water temperature is 10 ° C, and 168 when the water temperature is 30 ° C.
It was time.

[0056]

As described above, when the filtration device of the present invention is used, the filtration rate can be increased without deteriorating the quality of the treated water, so that the filtration efficiency is improved, especially the high-speed filtration device. Suitable as Further, since the structure of the filter medium layer is simple, it can be easily manufactured and installed, and the manufacturing cost and the management and maintenance cost can be reduced.

Furthermore, the filter material can be easily and surely washed, and at the same time, the filtration duration is long, so that 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 filter medium layer formed by using the conventional sand as the filter medium and the filtration speed can be made higher, the area of the filter device can be made smaller.
It is possible to install the filtering device even in a small area.

[Brief description of drawings]

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

FIG. 2 is an explanatory flow diagram showing an example of clean water treatment using a filtration device.

[Explanation of symbols]

1 device body 2 Filter media layer 3 Wash water supply section 4 Gas supply section

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI B01D 29/38 580A (56) References JP-A-3-4913 (JP, A) JP-A-8-290020 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 39/00-39/20

Claims (10)

(57) [Claims] 1. A filter device body (1) having a filter medium layer (2) formed of a single granular filter medium, the filter device body being provided.
(1) In a filter device for filtering raw water by passing raw water through the filter medium layer (2), 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.
It is possible to reduce the turbidity of the treated water after filtration to 0.1 degrees or less by passing the raw water through the filter medium layer (2) at a flow rate (LV) of 300 m / day or more. Characteristic filtering 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 duration is 240 hours or more when the turbidity of the raw water is 0.35 degrees on average. 4. The washing water supply unit is provided in the filtration device 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 cleaning water and cleaning gas when cleaning the filter medium layer (2). Filter media layers separately or simultaneously
The filtration device according to any one of claims 1 to 3, which is provided so as to be able to supply to (2). 5. The filter medium comprises anthracite as claimed in claim 1.
5. The filtration device according to any one of 4 to 4. 6. A raw material water having a flow velocity (LV) of 300 m / day or more in a filter medium layer having a specific gravity of 2 or less and a particle size of 0.8 to 1.1 mm and a height of 1.0 to 1.5 m. The filtration method is characterized in that the turbidity of the treated water after filtration is 0.1 degree or less. 7. The turbidity of the raw water is 2 degrees on average, and the filtration duration is 70 hours or more in this case.
The filtration method according to. 8. A the raw water turbidity average 0.35 degrees, and the method of filtration according to claim 6 filtration duration time in this case is not less than 240 hours. 9. After filtering the raw water for a certain period of time,
By stopping the supply of raw water to the filter medium layer to lower the water level to a predetermined position, injecting gas into the filter medium layer from below, then simultaneously injecting gas and cleaning water, and further injecting only cleaning water. 9. The filtration method according to claim 6, wherein the filter material layer is washed, and raw water is supplied again to the filter material layer to perform filtration. 10. The filter medium comprises anthracite.
The filtration method according to any one of 6 to 9.