JPH05184819A - Filter for sewage and the like - Google Patents

Abstract

PURPOSE:To nun a filter for a long time without causing filter membrane clogging by filtering raw water with a two-layer filter medium consisting of filter cloth and filter membrane and washing and regenerating the filter cloth that can be easily washed. CONSTITUTION:A lot of filter plates 3 which form a filter bed in the recessed shape on both the faces are freely movably arranged in parallel along a guide rail. A filter membrane 8 in the shape of a sheet is spread on the filter bed of the filter plate 3 and filter cloth 9 is installed so that it may cover the filter membrane 8. An original liquid is fed to a filter chamber whose inner face is constituted of the filter cloth 9 between the filter plates 3 and is filtered by the filter membrane 8 to take out it after its coarse impurities are captured by the filter cloth 9. Since the original liquid filtered by the filter membrane 8 is passed through cake formed on the filter cloth 9 face when it is filtered by the filter cloth 9 to give it cake filtration, the filter membrane 8 does not clog for a long time. When the filter cloth 9 clogs, it is easily regenerated by opening the filter plates 3 to give it washing, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a filtration device for sewage produced in large quantities in rivers and the like.

[0002]

2. Description of the Related Art Conventionally, in order to separate contaminants from wastewater such as sewage, first, the wastewater is concentrated in a sedimentation basin, the precipitated sludge is extracted, and a coagulant or a filter aid is added to the sludge for filtration. It is dehydrated and the cake is incinerated or discarded. The above is a general method for treating sewage that has been conventionally performed, but on the other hand, for the filtration operation during the conventional sewage treatment step,
It is also known to use a pressure filter to use a sheet-shaped microfiltration membrane as the filter medium.

Japanese Examined Patent Publication No. 3-55173 is one such example. In this type, a flat plate-shaped filter membrane is stretched over a filter bed of a large number of filter plates arranged in parallel, and a filter membrane formed between the filter plates. The undiluted solution is supplied to the filtration chamber consisting of the above and filtered.

In Japanese Patent Publication No. 47-20058, a filter cloth is stretched between a large number of filter plates arranged in parallel, and the filtration chamber formed between the filter plates has a relatively small amount of contaminants such as seawater and tap water. An apparatus capable of supplying and processing a large amount of is described.

[0005]

However, among the conventional techniques, the method of concentrating sewage and pressurizing it is troublesome in concentrating and coagulating, and since the filter cloth is used as the filter medium, the water quality of the filtrate obtained. There is a limit to turbidity and turbidity cannot be discharged as it is, and further treatment is required. In addition, special fair 3
In the case of using a filtration membrane such as -55173, a clear filtrate can be obtained, but depending on the raw water, the filtration membrane is clogged in a short time, and when clogged, it cannot be regenerated unless it is decomposed. Also, in the case of using a filter cloth as in Japanese Patent Publication No. 47-20058, it is easy to regenerate when the filter cloth is clogged, but the turbidity of the obtained filtrate is naturally limited as in the case of the pressure dehydrator. There is.

[0006]

The present invention solves the above-mentioned conventional problems by using a sheet-shaped microfiltration membrane and a filter cloth in combination, that is, the filter cloth contains foreign matters. Focusing on the fact that the filterability of the raw water, which has been removed by filtration, is significantly higher than the filterability of the filter cloth, the raw water is a two-layer filter medium consisting of the filter cloth and the filter membrane. The filter cloth, which can be easily washed, is washed and regenerated so that a large amount of a clear filtrate can be obtained by continuing the filtration until the filtration membrane is clogged.

According to the present invention, the means for obtaining a large amount of the above filtrate is as follows. That is, a large number of filter plates are movably provided along the guide rails, sheet-like filter media having a large number of fine through holes are stretched on the filter beds of these filter plates, respectively, and a filter cloth covering these filter media is provided. In the filter plate, when these filter plates are closed, the undiluted liquid supply port opening to the filtration chamber formed by the filter cloth between the filter plates and the filtration bed on the back side of the flat film-like filter medium are provided. The opening for the filtrate to be opened is opened. The filter plates provided movably along the guide rails may be opened and closed at the same time, or may be opened one by one. Further, the filter cloth provided between the filter plates may be fixed to the filter plates, or may run outside the row of filter plates.

[0008]

The apparatus according to the present invention is configured as described above, and therefore, the undiluted solution supplied to the filtration chamber is filtered by the filter cloth and then precisely filtered by the sheet-shaped filter material, and then the outside of the machine. Taken out. At this time, in the sheet-shaped filter medium, i.e., the microfiltration membrane, since the contaminants in the stock solution are removed by the filter cloth, the filtrate passes through the contaminants, so-called cake filtration is performed, so the filtration membrane is It is possible to perform continuous operation for a long time as compared with the clogging time of the filter medium without clogging for a long time. Therefore, by cleaning the filter material that can be washed and regenerated by opening the filter plate for a fixed time, it is possible to perform a long-term microfiltration operation. Hereinafter, the present invention will be specifically described based on Examples.

[0009]

1 is a schematic side view of a filter press according to the present invention, in which reference numeral 1 is a frame and 2 is a frame.
Is a guide rail bridged between frames 1 and 1, and
Filter plates movably aligned on guide rails, 4 is a link chain connecting the filter plates, 5 is a drive chain for opening and closing the connected filter plates, and 6 is a hydraulic cylinder for tightening the filter plates. , 7 are movable heads respectively provided at both ends of the filter plate row. In the illustrated filter press, the filter plate row opens and closes when the left and right filter plate groups approach or move away from each other with the center portion as a boundary. Is done.

The filtration device according to the present invention is provided between the filter plates of the above-mentioned filter press, and the configuration thereof will be described with reference to FIG. In FIG. 2, reference numeral 8 indicates
A sheet-shaped filter membrane stretched over the filter bed of the filter plate 3, 9 is a filter cloth provided so as to cover the filter membrane 8, and 10 is the filter membrane 8
It is a sheet-like support member having water permeability for supporting.
In the case shown in FIG. 2, a pair of filter cloths 9 and 9 provided between the filter plates.
However, the upper support bar 1
1 is provided, and the upper support bar 11 is wound around drive wheels 12 provided on the masts of both shoulders of the filter plate 3
3 is connected to one end of the filter cloth 9, while the lower end portions of the filter cloths 9 and 9 are wound around a return roll 14 provided at the lower portion of the filter plate 3 and then similarly provided to the adjacent filter plates 3 and 3. It is attached to the lower end of one filter cloth 9, and the lower support bar 1 is attached to this attached portion.
5, the lower support bar 15 is connected to the chain 13 described above.
And the pair of filter cloths 9, 9 are connected to the other end of the drive wheel 12.
It is designed to run up and down by driving. Code 1
6 is a liquid supply plate for supplying the undiluted solution, and 17 is a supply port opened between a pair of filter cloths. Further, reference numeral 18 is an outlet for the filtrate, which is opened in the support member portion on the back surface of the filtration membrane 8. Although the ultrafiltration membrane is used as the filtration membrane in the illustrated example, it may be a microfiltration membrane such as reverse osmosis membrane or ceramics.

The above is an example in which the present invention is applied to a filter cloth traveling type filter press. Next, FIG. 3 shows a case where the present invention is applied to a filter cloth fixed type filter press. The lower ends of the pair of filter cloths 9 and 9 are fixed to the lower portions of the filter plates 3, and by opening the filter plates 3 and 3, the lower portions of the filter cloths 9 and 9 forming the filtration chamber are opened. Although not shown, a cleaning nozzle is provided so that the inner surface of the filter cloth can be cleaned. Further, in the filter press of the type shown in FIG. 3, the filter plate 3 may be opened either individually or all filter plates may be opened simultaneously.

The filtration apparatus according to the present invention is constructed as described above, and the stock solution supplied from the supply port 17 between the filter cloths is filtered by the filter cloths 9, 9 and then the filtrate is filtered. Membrane 8,
After being filtered by 8, the filtrate can be taken out of the machine through the outlet 18. This filtrate is capable of separating even fine contaminants by means of the filtration membrane 8 and enables precise filtration as compared with the conventional filter press. The lower part of the filter chamber formed by the filter cloths 9 and 9 can be opened and the cake formed in the filter chamber can be peeled off and dropped by opening the filter plates 3 and 3. In this case, the filter cloth traveling type can be removed by scraping or washing, and the filter cloth fixed type can be removed by shaking or washing.

During the above filtering operation, the filter cloth 9
Large contaminants in the stock solution are removed, and the filtrate is so-called cake filtered by the captured contaminants to remove even fine particles. Therefore, the clogging time of the filtration membrane 8 is much longer than the clogging time of the filter cloth 9, and the filtration operation can be continued only by washing and regenerating the filter cloth 9. That is, when the present invention is applied to a filter press having a short filter cycle (within 1 hour) of a filter cloth traveling type, it is possible to continuously operate for a long time by regenerating the filter cloths 9, 9. Even in the case of the undiluted solution such as No. 3 which has poor filterability and must be filtered by a long filtration cycle (20 hours), the filter membrane 8 can be filtered by the filter cloth 9 or more even if the filter cloths 9, 9 are clogged. It has the property of being capable of continuous and precise filtration operation.

Next, the filterability of the filter cloths 8 and 8 and the filtration membranes 9 and 9 will be described in detail with reference to FIG. As a result of testing the sludge having a difficult filtration property generated in a certain water purification plant, there is a large difference in the filterability (filtrate amount / time) between the filter cloth 9 stretched on the filter membrane 8 and the filter membrane 8. There was found. Figure 4 shows the accumulated filtrate volume (l / m) when sludge (2.61% w / v) from a certain water purification plant was filtered with a filter cloth for a long time using a leaf filter.
2) and a plot of the cumulative filtrate amount when the filtrate obtained by the filtration is filtered with an ultrafiltration membrane. In the figure, reference numerals 1 to 3 indicate the cumulative filtrate amount by the filter cloth, Reference numeral 1 indicates a pressure of 7 kg / cm2, reference numeral 2 indicates a pressure of 10 kg / cm2, reference numeral 3
Shows the case of a pressurizing pressure of 15 kg / cm 2. Also, reference numerals 4 to 7
Indicates the cumulative amount of filtrate obtained by the ultrafiltration membrane, and the reference numeral 4 indicates that the filtrate (26 mg / l) with a stable concentration obtained by stirring with a filter cloth was stirred to 3
The pressure is 5 kg / cm 2, and the pressure is 5 kg, and the pressure is 3 kg / cm 2 without stirring.
A high turbidity filtrate (2700 mg / l) at the initial stage of filtration with a filter cloth was stirred and pressure-filtered at 3 kg / cm 2, and the reference numeral 7 was also a high turbidity filtrate with a filter cloth ( 2700 mg
/ l) was pressure filtered at 3 kg / cm 2. The filter cloth used had an air permeability of 300cc / cm2min, and the ultrafiltration membrane used was
It had a molecular weight cut off of 50,000.

According to the above diagram, in the case of filter cloth,
The cumulative filtrate volume reaches half of the final filtrate volume after 2 hours, whereas the filter membrane has much better filterability than this and the high turbidity at the initial stage of filtration with the filter cloth. Even the filterability of the filtrate with a certain degree doubles, and the filtrate having a stable turbidity shows a filterability of about 10 times. That is, the permeation amount of the filtrate per unit time and unit filtration area of the filter membrane is much larger than that of the filter cloth, and it can be confirmed that the filtration capacity of the filter cloth is not hindered by the filter membrane.

Therefore, by using a filter cloth and a filter membrane as a filter medium in a pressure filter such as a filter press, the filter capacity is the same as that of the conventional filter press, and precise filtration is possible. It is a thing. The filtration device according to the present invention, particularly when used for the filtration of sludge that has a poor filtration property and requires a long time for filtration, does not require any trouble in driving operation,
However, a clean filtrate can be obtained. In addition, even when used in a filter press that opens the whole plate at the same time,
Only by removing the clogging of the filter cloth, a continuous and clean filtrate can be obtained. In other words, a filter press is used to enable a large amount of microfiltration of difficult-to-filter sludge containing organic components. It is a thing.

[0017]

As described above, the present invention enables continuous filtration of a large amount of slurry by stacking a filter cloth and a filtration membrane and utilizing their respective filtration characteristics. Can be easily applied to a filter press or the like, and in addition to solving the problems in the filtration of the conventional hardly-filterable slurry, the filtration accuracy can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic side view of a filter press according to the present invention.

FIG. 2 is a vertical sectional side view of a main part of the filtration device according to the present invention.

FIG. 3 is likewise a vertical cross-sectional side view of another embodiment.

FIG. 4 is a table showing filterability of filter cloths and filtration membranes.

[Explanation of symbols]

 2 Guide rail 3 Filter plate 8 Filtration membrane 9 Filter cloth 17 Supply port 18 Outlet

Claims (4)

[Claims] 1. A large number of filter plates 3 are movably provided along a guide rail 2, and a sheet-shaped filter medium 8 having a large number of fine through holes is stretched on a filter bed of these filter plates 3 respectively. A filter cloth 9 that covers the filter medium 8 is provided, and the filter plate 3 is
When these filter plates 3 are closed, the undiluted solution supply port 17 that is opened in the filtration chamber formed by the filter cloth 8 between the filter plates and the filter that is opened in the filtration bed behind the sheet-shaped filter medium 8 are provided. A filtration device for sewage or the like, characterized in that a liquid outlet 18 is opened. 2. The apparatus for filtering sewage or the like according to claim 1, wherein a plurality of filter plates 3 movably provided along the guide rails 2 are opened and closed at the same time. 3. The filter cloth 9 according to claim 1, wherein a large number of filter plates 3 movably provided along the guide rails 2 are opened from one end thereof to one plate, and a filter cloth 9 covering the filter material 8 is provided.
A device for filtering sewage, which is fixed to a filter plate 3. 4. The filter device for claim 1 according to claim 1, wherein a filter cloth 9 capable of covering the filter medium 8 is allowed to run along the filter plate 3 between the filter plates.