JPH09131598A - Fixed type multi bed biological contact filtrating device and device therefor in water treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a large quantity of sludge caused by the addition of a large quantity of a flocculant and to eliminate fear about health trouble due to aluminum by filtering a water to be filtered with a biological contact filer pond, in which a hollow filter medium and a filter medium composed of a ceramic are packed respectively in the upper bed and in the lower bed, and then, filtering it with a sand filtration or membrane filtration. SOLUTION: As for a city water treatment, at first a flocculant and an alkaline agent are added to a raw water supplied from a raw water tank, the result is stirred quickly in a quick stirring pond 2 and is slowly stirred in a floc forming pond 3 to form a floc. Next, a filtrate after forming the floc is biologically filtered in a 1st biological contact filter pond 4. In such a case, a suspended material in the water to be treated is deposited on the filter medium in the upper bed 5 of the filter pond 4 and after that, a suspended material not deposited on the filter medium of the upper bed 5 is deposited on the filter medium in the lower bed 6. Next, the filtrate is biologically filtered in a 2nd biological contact filter pond 7. In the 2nd biological contact filter pond 7, a suspended material not deposited on the filter medium in the upper bed 8 is similarly deposited on the filter medium in the lower bed 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed bed type multi-layer type biological contact filtration method and apparatus for water treatment, and more specifically, to a water treatment field requiring coagulation precipitation method such as tap water or industrial water. The present invention relates to a fixed bed type multi-layer type biological contact filtration method and an apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, an apparatus as shown in FIG. 3 has been used in a water treatment technique which requires this type of coagulating sedimentation method.

That is, this device, as shown in FIG.
A flocculant, an alkaline agent, and a chlorine agent are added to the raw water from the raw water tank 1a, the mixture is rapidly stirred in the rapid stirring tank 2a after adding the flocculant, and then slowly mixed in the floc formation tank 3a to form flocs. After forming, sludge etc. is settled in the settling tank 11,
After that, the sand is filtered and processed in the sand filter 10a.

[0004]

However, in such a system, it is necessary to add an excess of an aluminum compound as a coagulant depending on the water quality of the raw water. As a result,
There is a problem that the amount of sludge generated increases.

Further, when the aluminum concentration in the purified water becomes high due to the addition of a large amount of the coagulant, there is a risk of health problems.

The coagulant as described above is originally used to reduce the turbidity of water quality, but it is also intended to remove the precipitate of microorganisms.

Therefore, for example, when a eutrophic lake is used as a water source, even if the water quality of the raw water is low, microorganisms (especially algae)
Tends to increase, in which case a large amount of coagulant will be added only to prevent microbial leakage into the purified water.

The present invention has been made to solve the above problems, and prevents the generation of a large amount of sludge due to the addition of a large amount of a coagulant, and prevents the health hazard due to a high aluminum concentration. The challenge is to resolve the concerns.

[0009]

The present invention has been made as a fixed bed type multi-layer type biological contact filtration method and apparatus for solving the above-mentioned problems. The feature of the filtration method is to filter the treated water in a biological contact filtration basin in which the upper side is filled with a hollow filter medium and the lower side is filled with a ceramic filter medium, and then sand filtration or membrane filtration is performed. It is in.

The fixed bed type multi-layer type biological contact filtration device is characterized by a biological contact filtration basin in which the upper side is filled with a hollow filter medium and the lower side is filled with a ceramic filter medium, It is provided with a sand filter 10 or a membrane filter for filtering the treated water after being filtered in the contact filter.

That is, since filtration is carried out in the biological contact filtration basin as described above before such sand filtration or membrane filtration, a certain amount of turbidity in the treated water, which causes turbidity, or a certain amount of microorganisms is first detected in the upper stage. The suspended filter and the microorganisms which are supported by the hollow filter medium of 1. and are not supported by the hollow filter medium on the upper side are supported by the filter medium made of ceramic on the lower side.

Therefore, only suspended substances and microorganisms which are not supported by the hollow filter material on the upper side or the filter material made of ceramic on the lower side are filtered by sand filtration or membrane filtration. This will reduce the burden on the.

It is preferable to arrange two biological contact filtration basins in series, and in this case, after a certain amount of suspended matter or microorganisms have been filtered in the first stage biological contact filtration turbidity, the suspended matter that could not be filtered. And microorganisms can be filtered in the second-stage biological contact filter. In particular, it is effective when the turbidity of the treated water is high or when the reproduction of microorganisms is remarkable.

The material of the hollow filter medium is exemplified by synthetic resin.

Further, the particle size of the ceramic filter medium is
It is preferably 1.0 to 2.0 mm. If it is 2.0 mm or more, the function of removing microorganisms and suspended matter may be deteriorated, and if it is 1.0 mm or less, filtration resistance may increase and the water level in the biological contact filter may rise.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a schematic block diagram of a fixed bed type multi-layer type biological contact filtration apparatus for treating clean water as an example.

In FIG. 1, reference numeral 1 denotes a raw water tank for storing raw water, and the raw water tank 1 stores raw water from rivers, lakes, etc. to be treated with clean water.

Reference numeral 2 denotes a rapid stirring pond for adding a flocculant or an alkaline agent to the raw water and then performing rapid stirring. Reference numeral 3 denotes a floc formation pond for forming flocs after the rapid stirring.

Numeral 4 is a first fixed bed type biological contact filter for biologically filtering the treated water after the formation of the flocs. The upper layer is filled with a large number of polypropylene-made filter media to form an upper layer 5. In addition, the lower layer is filled with a large number of ceramic filter media to form the lower layer 6 and is formed into two layers of upper and lower layers.

The polypropylene filter material of the upper layer 5 is 4
It is formed into a hollow cylinder having an outer diameter of 5 mm and a length of 5 mm, and the hole diameter of the hollow portion (inner diameter of the filter medium) is 2 mm.

The ceramic filter material of the lower layer 6 is
It has a spherical shape with a diameter of 1.5 mm.

Numeral 7 is a fixed bed type second biological contact filter for further biologically filtering the treated water after being filtered by the first biological contact filter 4, and in the upper stage there are a large number of synthetic resin filter media. To form an upper layer 8, and a lower layer is filled with a large number of ceramic filter media to form a lower layer 9 to form two layers, an upper layer and a lower layer.

The filter material made of synthetic resin of the upper layer 8 is formed into a hollow cylindrical shape having an outer diameter of 4 mm and a length of 5 mm as in the case of the first biological contact filtration basin 4, and the hole diameter of the hollow portion is formed to 2 mm. However, the ceramic filter material of the lower layer 9 is formed into a spherical shape having a diameter of 1.0 mm.

The synthetic resin filter medium of the upper layers 5 and 8 of both the first biological contact filtration basin 4 and the second biological contact filtration basin 7 is specifically made of polypropylene, and the lower layers 6 and 9 are made of ceramic. The filter-making material is specifically composed of calcined diatomaceous earth.

Numeral 10 designates the first biological contact filtration basin 4 and the second biological contact filtration basin 4.
The sand filtration basin for sand-filtering the treated water after biological filtration in the biological contact filtration basin 7 is shown.

Next, a method of performing biological contact filtration with the fixed bed type multi-layer type biological contact filtration apparatus having the above-mentioned structure will be described.

First, a flocculant and an alkaline agent are added to the raw water supplied from the raw water tank 1.

Immediately after the addition of the coagulant and the alkaline agent,
Rapid stirring is performed in the rapid stirring tank 2.

After rapidly stirring in the rapid stirring pond 2,
Stir slowly in the floc formation pond 3 to form flocs.

Next, the filtrate after flock formation is supplied to the first biological contact filtration basin 4 for biological filtration.

In this case, first, a certain amount of suspended substances (including microbes as well as suspended matter) in the treated water is carried on the filter material of the upper layer 5 of the first biological contact filtration basin 4, and then the upper layer. Suspended substances not supported by the filter material of layer 5 are supported by the filter material of lower layer 6.

Next, the filtrate filtered in the first biological contact filtration basin 4 is further biologically filtered in the second biological contact filtration basin 7.

That is, also in the second biological contact filtration basin 7, a certain amount of suspended substance is first supported by the filter material of the upper layer 8, and then the unsupported suspended substance is supported by the filter material of the lower layer 9. It

In this way, since the biological filtration is carried out in the upper layers 5, 8 and the lower layers 6, 9 of the first biological contact filtration basin 4 and the second biological contact filtration basin 7, the second biological contact filtration basin 7 The turbidity of the treated water after passing will be considerably lower than the turbidity of the treated water before passing through the first biological contact filtration basin 4, and a considerable amount of microorganisms will also be removed. Incidentally, in the present embodiment, when the turbidity of the treated water before passing through the first biological contact filtration basin 4 was about 500 degrees, the turbidity of the treated water after passing through the second biological contact filtration basin 7 was 5 degrees. It became possible to reduce to the following.

After that, a chlorine agent is injected into the treated water that has passed through the second biological contact filtration basin 7, and then sand filtration is performed in the sand filtration basin 10.

In this sand filtration basin 10, since a considerable amount of suspended matter is filtered in the first biological contact filtration basin 4 and the second biological contact filtration basin 7, the sand filtration basin 10 has a small amount of suspended matter. Only suspended material will be filtered.

As described above, in this embodiment, not only the suspended matter can be filtered by the two-stage biological contact filtration basins 4 and 7 to reduce the turbidity, but also a considerable amount of microorganisms are filtered. Therefore, the amount of the coagulant added to the raw water can be significantly reduced compared to the conventional case.

By the way, in this embodiment, even when the turbidity was 300 degrees or more, the addition amount of the coagulant could be reduced to 1/2 to 1/4 as compared with the conventional case.

Further, as a result of filtering a considerable amount of suspended substances in the first biological contact filtration basin 4 and the second biological contact filtration basin 7, it is possible to reduce the load on the filtration in the sand filtration basin 10. became.

Further, in both the first biological contact filtration basin 4 and the second biological contact filtration basin 7, upper layers 5 and 8 filled with polypropylene filter media and lower layers 6 and 9 filled with ceramic filter media are provided. Therefore, it is possible to perform a suitable filtration that does not impair the function of turbidity reduction and biological filtration and does not raise the filtration resistance carelessly.

That is, the first biological contact filtration basin 4 and the second
When only the hollow cylindrical filter material made of polypropylene is filled in the whole biological contact filtration basin 7, if the amount of the suspended substance carried exceeds the allowable range, the turbidity may suddenly increase. If the whole of the biological contact filtration basin 4 and the second biological contact filtration basin 7 is filled with only the ceramic filter medium, the filtration resistance becomes large, and the first biological contact filtration basin 4 and the second biological contact filtration basin 7 Since there is a risk that the water level of the above may rise carelessly, it is preferable to fill the upper layers 5 and 8 with the hollow polypropylene filter medium and the lower layers 6 and 9 with the spherical ceramic filter medium as described above. .

In the above embodiment, the polypropylene used as the filter material filled in the upper layers 5 and 8 of the first biological contact filtration basin 4 and the second biological contact filtration basin 7 is made of polypropylene. The material is not limited to the embodiment, and other materials such as polyethylene can be used, and materials other than synthetic resin, such as ceramics, can be used. However, from the viewpoint of cost, it is preferable to use a so-called general-purpose synthetic resin such as the above polypropylene.

The shape of the filter medium is not limited to the cylindrical shape as in the embodiment, but may be, for example, a rectangular tube shape. The point is that it should be hollow.

Further, in the above embodiment, good results were obtained by using a hollow cylindrical filter medium having an outer diameter of 4 mm and a vertical dimension of 5 mm, but the diameter and size of this filter medium are also limited to those in the above embodiment. Not a thing.

Further, the material of the filter medium filled in the lower layers 6 and 9 is not limited to the calcined diatomaceous earth of this embodiment, and it is also possible to use other ceramic materials. The point is that a ceramic material may be used.

Further, the shape of the filter material of the lower layers 6 and 9 is not limited to the spherical shape of the embodiment.

Further, the particle size of this filter medium is not limited to the above embodiment, but from the viewpoint of filtration performance, it is 1.0
It is preferably about 2.0 mm.

Further, in the above embodiment, since the two-stage biological contact filtration basin, that is, the first biological contact filtration basin 4 and the second biological contact filtration basin 7 are arranged in series, it is possible to treat treated water with a high turbidity. However, the provision of the two-stage biological contact filtration basin is not an essential condition for the present invention, and it is also possible to provide only one stage of the biological contact filtration basin.

Further, in the above-mentioned embodiment, since the rapid filtration basin 2 and the floc formation basin 3 are provided, in the case of treated water having high turbidity, the suspended substance is preliminarily passed through the two-stage biological contact filtration basin. It was possible to remove the
Providing such a rapid filtration basin 2 and a floc formation basin 3 is not an essential condition of the present invention.

That is, in the present invention, since the biological filtration is carried out by the biological contact filtration basins 4 and 7 as described above, when the turbidity of the raw water is 15 degrees or less, the addition of the coagulant is unnecessary, and therefore the rapid filtration basin 2 It is not necessary to provide the flock formation pond 3. That is, in the present invention, the addition of the coagulant may be performed as necessary depending on the water quality (turbidity) of the raw water.

On the other hand, when the turbidity of the raw water is 15 degrees or more, it is necessary to add the coagulant, and therefore it is necessary to provide the rapid filtration basin 2 and the floc formation basin 3 as in the above embodiment. However, even in that case, the amount of the coagulant added is significantly reduced as compared with the conventional case.

Further, in the above embodiment, the sand filtration basin 10 is provided for sand filtration, but membrane filtration may be performed instead of this sand filtration.

Further, in the above embodiment, the case where treated water is used as tap water has been described, but the kind of treated water is not limited to this, and the present invention can be applied to various industrial waters. It is possible.

[0055]

EXAMPLES Next, more specific examples of the present invention will be described.

Example 1 In this example, a column having two layers, an upper layer filled with a synthetic resin filter medium and a lower layer filled with a ceramic filter medium, and a column filled with only a ceramic filter medium as a comparative example. The turbidity change and the filtration resistance were compared when the biological filtration was performed in continuous operation.

When raw water having a turbidity of about 50 degrees was passed through the column of Example 1 and the column of Comparative Example once, the change in turbidity and the filtration resistance were measured every 30 minutes to 1 hour.

As a filter medium in the column of Example 1, a hollow cylindrical polypropylene filter medium having an outer diameter of 4 mm and a length of 5 mm was packed in the upper stage over a layer height of 1.5 m, and a lower stage was made of a spherical ceramic having a diameter of 2 mm. The filter medium was filled over a bed height of 0.5 m.

On the other hand, as the filter medium in the column of the comparative example,
A spherical ceramic filter medium having a diameter of 2 mm was filled over a layer height of 1.5 m. The measurement results are shown in Table 1 below.

[0060]

[Table 1]

As is clear from Table 1, the throughput of the column of Example 1 was maintained even after 13 hours,
As a result, raw water with an average turbidity of about 54 degrees could be reduced to about 1 degree.

Even with the treatment with the column of the comparative example, it was possible to reduce it to 2.6 degrees after 13 hours of treatment.

However, there was a large difference in filtration resistance between Example 1 and Comparative Example.

That is, in the comparative example, the treated water overflowed from the column 13 hours after the filtration resistance became large, but the column of Example 1 did not cause such overflow, and The water level hardly increased. Incidentally, in Example 1, the operation could be performed for 27 hours without causing an overflow.

Example 2 In this example, the change in turbidity and the filtration resistance during continuous operation for 18 hours using a two-stage column were measured every hour.

A hollow cylindrical polypropylene filter medium having an outer diameter of 4 mm and a length of 5 mm is provided in the upper part of the first column with a bed height of 1.5.
Then, the lower layer was filled with a spherical ceramic filter medium having a diameter of 2 mm over a layer height of 0.5 m.

In addition, the outer diameter of the upper column in the second column is 4 mm.
With a 5 mm long hollow cylindrical polypropylene filter material
It was filled over 1.5 m, and the lower part was filled with a spherical ceramic filter medium having a diameter of 1.5 mm over a layer height of 0.5 m.

The column used had a diameter of 100 mm and a length of 4000 mm.

The coagulant injection rate was 20 mg / L.
Table 2 shows the measurement results.

[0070]

[Table 2]

As is clear from Table 2, the turbidity of the treated water after passing through the first column was considerably reduced, but the turbidity of the treated water after passing through the second column was further reduced. Finally, the removal rate of suspended matter was 99.9%.

The filtration resistance was such that overflow from the column did not occur, and the filtration resistance of the second column was smaller than that of the first column.

In Table 1, treated water 1 means treated water after passing through the first column, and treated water 2 means treated water after passing through the second column.

Example 3 In this Example as well, the change in turbidity and the filtration resistance in the case of continuous operation using a two-stage column were measured as in Example 2.
In this example, the operation was performed for 205 hours.

In this example, the diameter and length of the upper hollow cylindrical polypropylene filter medium in the column were the same as in Example 2, but the diameter of the lower spherical ceramic filter medium was changed.

That is, the diameter of the spherical ceramic filter medium in the first column was 1.5 mm, and the diameter of the spherical ceramic filter medium in the second column was 1.0 mm.

No coagulant was injected. The measurement results are shown in Table 3 below.

[0078]

[Table 3]

As is clear from Table 3, the turbidity of the treated water after passing through the first column and after passing through the second column was considerably reduced, and the removal rate of suspended matter was 92%. It was

Further, the filtration resistance also showed a low value until 100 hours passed, and no remarkable increase in resistance value was observed even after 205 hours of treatment.

Example 4 In this example, raw water was treated in a two-column column having two layers, an upper layer filled with a synthetic resin filter medium and a lower layer filled with a ceramic filter medium, and a comparative example. As a result, the change in turbidity was compared with the case where raw water was treated in a column packed with only a synthetic resin filter medium.

A hollow cylindrical polypropylene filter medium having an outer diameter of 4 mm and a length of 5 mm was filled in the upper column of the first column of this Example over a layer height of 1.5 m, and the lower column had a spherical ceramic having a diameter of 2 mm. The filter media was filled over a bed height of 0.5 m.

In addition, the outer diameter of the upper column in the second column is 4
A hollow cylindrical polypropylene filter medium having a length of 5 mm and a length of 1.5 mm was filled in the layer height of 1.5 m, and a spherical ceramic filter medium having a diameter of 1.5 mm was filled in the lower stage over a layer height of 0.5 m.

On the other hand, as the filter medium in the column of the comparative example,
A spherical ceramic filter medium having a diameter of 4 mm was filled over a layer height of 2.0 m. The measurement results are shown in Table 4 below.

[0085]

[Table 4]

As is clear from Table 4, 2 of the present embodiment
When treated with a column of columns, the turbidity was significantly reduced as compared with the comparative example.

Example 5 In this example, the injection rate of the coagulant with respect to the turbidity of the raw water was compared between the case where the biological treatment was carried out using the two-stage column as described above and the case where the system using the conventional settling tank was used. It is a comparison.

The results are shown in FIG.

As is clear from FIG. 2, the turbidity of raw water is 15
Up to 100 ° C, injection of coagulant was not necessary at all, and even if the turbidity of raw water was 15 ° C or higher, the injection rate could be significantly reduced compared to the conventional method.

[0090]

As described above, according to the present invention, before the filtration by sand filtration or membrane filtration, the biological contact material is filled with a hollow filter medium on the upper side and a ceramic filter medium on the lower side. Since the treated water is filtered in the filtration pond, the turbidity can be reduced by such a biological filtration sedimentation pond and the turbidity can be reduced, and a considerable amount of microorganisms are also filtered. There is an effect that it can be remarkably reduced as compared with the conventional case.

As a result, there is a real merit that a large amount of sludge is not generated unlike the conventional case, and the concern about a health hazard due to an increase in aluminum concentration can be eliminated.

Further, as a result of filtering a considerable amount of microorganisms and suspended matter in the biological filtration sedimentation basin, it becomes possible to reduce the load on filtration by sand filtration or membrane filtration.

Furthermore, since the upper layer filled with the hollow filter medium and the lower layer filled with the ceramic filter medium are filtered, the turbidity reduction and biological filtration functions are not impaired, and the filtration resistance is not impaired. There is an effect that suitable filtration can be performed to the extent that it is not easily prepared.

Furthermore, since it can be treated by biological filtration, NH
₃ , Fe, Mn, etc. can be taken in, and there is an advantage that it is not necessary to add a chlorine agent in advance before the biological filtration treatment.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a fixed bed type multi-layer biological contact filtration apparatus in water purification treatment as an example.

FIG. 2 is a graph showing the coagulant injection rate with respect to raw water turbidity.

FIG. 3 is a schematic block diagram of a fixed-layer-type multi-layer biological contact filtration device in conventional water purification treatment.

[Explanation of symbols]

4 ... 1st biological contact filtration basin 7 ... 2nd biological contact filtration basin 10 ... sand filtration basin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C02F 1/44 C02F 3/06 ZAB 3/06 ZAB 3/10 A 3/10 B01D 29/08 540A (72) Inventor Ryuji Hanamoto 6-101 3-2-1 Kashinodai, Nishi-ku, Kobe-shi (72) Hironobu Nishio 4--4-508 Tsuruko, Nada-ku, Kobe-shi (72) Inventor Mitsuaki Nuno, Sumiyoshi-ku, Osaka-shi Kanda 3-8-23-205 (72) Inventor Kenichiro Mizuno 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (8)

[Claims] 1. A method for filtering treated water in a biological contact filtration basin in which a hollow filter medium is filled in the upper side and a filter medium made of ceramic is filled in the lower side, and then filtered by sand filtration or membrane filtration. Fixed-layer multi-layer biological contact filtration method for water treatment. 2. The fixed bed-type multi-layer biological contact filtration method for water treatment according to claim 1, wherein the biological contact filtration basins are arranged in two places in series. 3. The fixed bed type multi-layer type biological contact filtration method for water treatment according to claim 1, wherein the hollow filter medium is made of synthetic resin. 4. The particle size of the ceramic filter medium is 1.
The fixed bed type multi-layer type biological contact filtration method for water treatment according to any one of claims 1 to 3, which has a thickness of 0 to 2.0 mm. 5. A biological contact filter which is filled with a hollow filter medium on the upper side and is filled with a ceramic filter medium on the lower side, and for treating the treated water after being filtered in the biological contact filter. A fixed bed type multi-layer biological contact filtration apparatus in water treatment, comprising a sand filtration apparatus 10 or a membrane filtration apparatus. 6. The fixed bed type multi-layer type biological contact filtration apparatus for water treatment according to claim 5, wherein the biological contact filtration basins are arranged in series at two locations. 7. The fixed bed type multi-layer biological contact filtration apparatus for water treatment according to claim 5, wherein the hollow filter medium is made of synthetic resin. 8. The particle size of the ceramic filter medium is 1.
The fixed bed type multi-layer biological contact filtration apparatus for water treatment according to any one of claims 5 to 7, which has a thickness of 0 to 2.0 mm.