JP5319592B2 - Suspended water filtration method and filtration apparatus - Google Patents

Description

The present invention relates to a high-speed filtration separation method and apparatus for suspended water containing suspended particles such as sewage, industrial wastewater, and irrigation water, and removes suspended particles in suspended water (hereinafter also referred to as “raw water”) at high speed. It relates to the technology that can. In particular, the present invention is a high-speed solid-liquid separation technique for sewage flowing into a sewage treatment facility, or a combined sewer rainwater overflow (abbreviated as CSO) containing organic suspended particles, or various industrial wastewater, It is an innovative technology that is extremely suitable for water treatment.

In recent years, the pollution load of rainwater overflowing water (CSO) in public water areas in a combined sewer has become a major problem. The sewage flowing into the sewage treatment facility is first precipitated and separated in the settling basin and then treated with activated sludge. However, since the SS removal rate in the first settling basin is poor, a coagulant is added and coagulated and settled. Examples are prevalent in Scandinavia. However, this method has a drawback that a large amount of sludge is generated, the coagulation sedimentation rate is small, and a large sedimentation basin is required. Therefore, a new technology that can separate CSO and sewage into a solid-liquid separation with as much compact equipment as possible is awaited.
Conventionally, filtration methods using anthracite, sand, and various granular solids (for example, granular plastic) as filter media have been studied. For example, in the sewage treatment field, filtration is often performed using the above-mentioned anthracite, sand, etc., for a suspended substance having a relatively large particle size such as activated sludge treated water. In this case, the drainage flow rate is often 100 to 500 m / d.
In addition, in order to increase the water flow rate, the filter medium particle size may be increased to reduce clogging, but in this case, inconsistencies such as deterioration of the SS removal rate have occurred. In particular, since organic SS contained in sewage and the like has a strong adhesive force, a technology capable of satisfying the conflicting requirement that the SS removal rate is high and clogging is low is desired for such sewage and the like.

As an alternative to the above-mentioned bead-based filter media, for example, in Japanese Patent Publication No. 62-55885 and Japanese Patent Laid-Open No. 10-305204, a large number of fiber masses in which short fibers made of organic fibers having a fiber length of 5 to 50 mm are entangled. There is a device that uses the filter as a filter medium. The filtration apparatus using this filter medium can perform filtration at a high speed of 600 m / d or more when treating wastewater containing suspended substances.
In such a fiber filter medium, in the case of so-called backwashing, which removes suspended substances adhering in the filtration process, the suspended substances are removed from the fiber filter medium by supplying washing water and air or either into the filter tower. However, since the difference in specific gravity between the fiber and the suspended substance is small, the fiber filter medium sometimes flows out from the upper part of the filtration tower, or separation of the fiber filter medium and the suspended substance may be insufficient. In addition, after the backwash, the fiber filter medium is naturally settled and filtration begins. At this time, the filter medium is not sufficiently compacted, and the suspended matter removal rate is sufficient to allow water to pass with a low filling rate. There was a case that did not come out.

In addition, as a method for washing the fiber filter medium, in order to prevent the fiber filter medium from flowing out, in the washing process, once the washing water is filled in the filtration tower, the filtration layer is fluidized by ventilation, and suspended substances adhering to the fiber filter medium are removed. There was a method of repeating the process of peeling and then allowing the washing waste water containing suspended substances to flow out from the bottom of the filtration tower. However, this method has problems such that the separated suspended substance adheres to the fiber filter medium again and the washing effect is low, or the washing time is long because the process of draining from the bottom of the filtration tower is repeated.
Japanese Patent Application Laid-Open No. 2004-89766 discloses a filter tower in which a synthetic fiber yarn fringe-like member or fiber bundle string-like member is fixed inside the filtration tower and the upper end is fixed by a fixing member to hang a large number. A method is described in which suspended water is introduced from the lower part, passed as an upward flow for filtration, and filtered water is discharged from the upper part. In a filtration tower using this filter medium, suspended water such as sewage can be filtered at a high speed of 1440 m / d with little clogging. Even in this case, it is not easy to backwash the fiber member to which the suspended substance is adhered, and when the fiber member is operated for a long time, the suspended substance may penetrate into the inside of the string and the washing effect may be insufficient.

Furthermore, Japanese Patent Laid-Open No. 9-234309 discloses a packed filtration tower having a filter layer made of a large number of fiber mass filter media or sponge filter media inside, and a filtration target liquid into which the filtration target liquid is put from the top of the packed filter tower. Introducing means, means for extracting liquid to be filtered from the lower part of the packed filtration tower, cleaning liquid introducing means for introducing a cleaning liquid from the lower part of the packed filtration tower, and the packed filtration tower In a filtration device having a cleaning liquid take-out means for taking out the cleaning liquid from the upper part of the filter and an air introducing means for sending air from below the filter layer, the filter layer is immersed in the liquid and then filled with the liquid. The liquid level is gradually lowered by letting it flow out from the lower part of the filter tower, and during that time, air is sent from below the filter bed and bubbled, thereby causing the filter medium to settle while shaking to compress the filter bed. ,Previous Filtration device is described which is characterized in that it comprises a filtration layer compression operation control means for controlling the operation of each unit. However, even when the above apparatus is used, when the short fiber lump filter medium having a low density of the fiber filter medium is used, the fiber lump filter medium is not compressed and the solids removal rate may be low.
Japanese Examined Patent Publication No. 62-55885 JP-A-10-305204 JP 2004-89766 A JP-A-9-234309

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a new technology capable of high-speed filtration of suspended particles in various raw waters such as sewage, various wastewaters, and irrigation water by a simple and compact device. To do. In particular, it is an object of the present invention to provide a high-speed filtration method capable of stably obtaining a high removal rate of suspended solids and continuing a higher removal rate for a long time, and a filtration device used in the method. Furthermore, it is an object of the present invention to provide a filtration method capable of obtaining good treatment performance even when the cleaning step is shortened and a filtration device used in the method.

In order to solve the above-mentioned problems, in the present invention, in the filtration method of suspended water using a filtration tower packed with short fiber lumps of fiber filter medium having a short fiber length of 5 to 100 mm, the fiber filter medium includes: The density is 25 kg / m ³ or more, and the following three steps after filtration treatment:
(1) A washing step of peeling off the solid matter attached to the fiber filter medium in the filtration tower, supplying air and washing water from the bottom of the filtration tower and discharging the solid substance peeled off from the fiber filter medium from the top of the filtration tower. ,
(2) After the washing step, in a state where the entire fiber filter medium in the filtration tower is submerged, a consolidation process by air supplying air from the bottom of the filtration tower in order to consolidate the fiber filter medium in the filtration tower,
(3) Furthermore, after the step of compacting with air, compaction with water that compacts the fiber filter medium by draining all or part of the liquid in the gap between the fiber filter medium and the fiber filter medium in the filter tower from the bottom of the filter tower. Process,
This is a suspension water filtration method characterized by

Further, the present invention provides a filtration apparatus for use in filtering method of the preceding Symbol aqueous suspension, the upper, the inlet pipe of the raw water to be treated, the drain pipe of the washing water, the density inside the 25 kg / m ³ or more A filtration layer filled with short fiber lumps of fiber filter material, a treated water collector at the bottom, a supply pipe for supplying air to the filtration layer, and wash water that flows upward through the filtration layer A drain pipe for draining all or part of the liquid in the filtration layer from the water collection device , or is obtained by a filtration device, characterized in that it comprises a filtration tower and an emissions pipe a part of the liquid was raised to filtration layer intermediate for draining of the filtration layer from the water collecting device.

In the filtration device, the filtration tower upper portion is provided with a porous member for preventing the outflow of the fiber filtration medium having an opening smaller than the shortest length of the diameter of the fiber filtration medium or the length of the linear portion. The filtration layer in the filtration tower can be installed at a part or all of the upper and lower surfaces and side surfaces of the perforation for preventing outflow. It can be integrated by being surrounded by members .

By carrying out the present invention, a fiber filter medium having a density of 25 kg / m ³ or more is used, and by providing a consolidation process, the fiber filter medium has a sufficiently high density in the filtration process. However, the removal rate of suspended solids in the raw water will be higher than the method of filtering with the fiber filter medium submerged, and the processing performance of the filtration device using the fiber filter medium will be increased significantly and stably. Can do. Further, water and aeration can be carried out at a high speed without worrying about the outflow of the fiber filter medium, the washing time can be compressed, the washing efficiency is improved, and the filtration performance in the subsequent filtration step is improved.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an example of a flow configuration diagram for carrying out the present invention.
In FIG. 1, a filtration tower 1 includes a raw water introduction pipe 4 to be treated at the upper part, a filtration layer 2 filled with short fiber lump-like fiber filter medium in the filtration tower, and a treated water collector at the lower part. 3, a supply pipe 6 for supplying air, and a treated water outflow pipe 5 (also referred to as a header pipe) raised from the water collection device 3 to at least the upper part of the filtration layer 2. A drain pipe 7 for draining the liquid is provided. The drain pipe 7 is provided with a valve 12, and a water level meter 13 is installed in the water collecting device 3, and the valve 12 is opened and closed according to the indicated value of the water level meter 13. A control mechanism is provided. If there is no need, installation of the water level gauge 13 is unnecessary. Particularly important here is that the density of the fiber filter medium is 25 kg / m ³ or more.

Raw water is secondary treated water for sewage treatment, first settling basin effluent, rainy effluent, various industrial wastewater, effluent treatment, etc. But you can.
The short fiber lump-like fiber filter medium used in the present invention will be described. The short fiber used in the present invention has a fiber length of 5 to 100 mm, the component is a polyester type such as polyethylene terephthalate, a polyamide type such as nylon 6 and nylon 66, a polyvinyl alcohol type, etc., and has a true specific gravity. One or more. The short fibers are bonded to each other using a manufacturing method such as resin pond, thermal pond, needle punch, air laid, spun lace, spun bond, melt bron, flash spin, stitch pond, and the like to form a raw fabric. The raw fabric may be a sheet having a thickness of several mm to several tens of mm, a width of 1 m to 3 m, and a length of several m to several thousand m, or a diameter of several mm to several tens of mm and a length of Some have a rod shape of several meters to several thousand meters. The term “small block” as used in the present invention refers to a state in which the original fabric is cut into an arbitrary size having a side length or diameter of 1 mm to 50 mm to form a small block. In the present invention, this small lump is referred to as a short fiber lump-like fiber filter medium, or simply a fiber filter medium. The density of the short fiber lump-like fiber filter used in the present invention is 25 kg / m 3 or more in an absolute dry state, and the shape thereof may be any shape such as a sphere, a cube, a cuboid, or a column. it can.

The water collecting device can be selected from those with gravel spread, perforated block type, wheeler type, strainer type, porous bottom type, porous tube type, etc. Since the block is light and easy to construct, it is preferable as a water collecting device for fiber filter media.
The water collecting device is provided with a sensor 13 for detecting the water level in the filtration tower, a discharge pipe 7 for draining water in the filtration tower provided for compressing the fiber filter medium, and a valve 12 in the discharge pipe 7. ing. An arbitrary sensor 13 can be used, and an ultrasonic level meter, a guide pulse type, a pressure, a differential pressure type, a float type, a laser type, and the like can be used. Let's take an example.
The raw water is continuously passed through the introduction pipe 4 and filtered by a fiber filter medium packed in the filtration tower. The water flow rate in the filtration process is more compact than the conventional filtration using a sand filtration layer, and when the water flow rate is high, suspended substances in the raw water are short-passed together with the treated water. In order to suppress the outflow, 500 to 2000 m / d is preferable. In addition, the height of the filtration layer at this time is designed so that the frequency of backwashing is 1 to 5 times a day, and the free board part on the upper part of the filtration layer is designed not to be extremely high. preferable.

The fiber filter medium obtained by filtering a certain amount of raw water is washed periodically, or by detecting an increase in filtration resistance, because the inside and surface thereof are covered with suspended solids. In the washing, air is supplied from the lower part of the filtration tower, and the suspended substances are peeled off from the fiber filter medium. The aeration speed and the aeration time are generally carried out at an aeration speed of 0.1 to 5.0 m / min and an aeration time of 3 to 30 min.
Waste water after washing containing suspended solids separated from the fiber filter medium is discharged out of the system through the discharge pipe 7 or the treated water outflow pipe 5 while supplying raw water from the introduction pipe 4, so that the regenerated fiber filter medium is recovered. Use again (cleaning process). Separately, a cleaning water supply pipe may be supplied from the upper or lower part of the filtration tower (not shown), and the cleaning waste water may be discharged from the discharge pipe 7 or the treated water outflow pipe 5. As the washing water, any liquid such as sewage secondary treated water, industrial water, rain water, or raw filter water can be used.

  In the present invention, after the washing step, a part or all of the liquid in the filtration tower is drained from the discharge pipe 7 installed in the water collecting device 3 in order to fill the fiber filter material submerged in water with higher density. A water compression step is provided. The void in the fiber filter medium itself is as high as 95% or more, and even when it contains moisture in water, the apparent specific gravity of the fiber filter medium is around 1.1, so that the conventional fiber filter medium is simply allowed to settle naturally in water. Then, since the difference in specific gravity between the water-containing fiber filter medium (specific gravity of about 1.1) and water (specific gravity of about 1) is small, it cannot be said that the fiber filter medium is closely packed. The gap (also referred to as a void) was large. However, in the filtration method and apparatus having the structure of the present invention, by draining a part or all of the liquid in the filtration tower, the fiber filter medium containing moisture (specific gravity about 1.1) and the density of air (specific gravity) Since about 0.001) becomes large, the fiber filter medium is consolidated to fill the voids by its own weight.

At this time, it is particularly important to use a short fiber lump-like fiber filter medium having a density of 25 kg / m ³ or more. Table 1 shows the relationship between the density of the fiber filter medium and the consolidation rate. The consolidation ratio indicates the ratio of the height of the filtration layer decreased by the consolidation process when the standing height when the fiber filter medium is simply settled is 100, and the higher the consolidation ratio, the denser the fiber filter medium becomes. It shows the state. From Table 1, when the density of the fiber filter medium is 10 kg / m ³ , the consolidation ratio is zero, and when the density is 25 kg / m ³ , the consolidation tends to increase, and the density is constant at about 30% at the density of 100 kg / m ³ . . When the density of the fiber filter medium is 10 kg / m ³ or less, the water retention rate of the fiber filter medium is low, and when the water is drained through the drain pipe G, the water inside the fiber filter medium is drained, resulting in a fiber filter medium containing almost no moisture. As a result, the fiber filter medium that does not contain moisture has a smaller specific gravity difference in air than the fiber filter medium that contains moisture, and cannot be sufficiently compressed in the compression step described above. From this, the density of the fiber filter media is related to the water retention rate and is an extremely important factor for determining the compression rate, and the effect can be exhibited particularly when the density of the fiber filter media is 25 kg / m ³ or more.

  Subsequently, when the filtration is resumed, the fiber filter medium in the filtration tower is sufficiently consolidated and the voids are reduced, so that the suspended matter in the water to be treated is well captured and the suspended matter removal rate is high. . Compared to the conventional method of simply sinking and filling the fiber filter medium, the filtration performance becomes higher when the water is drained and filtered in the compacted state because the voids are reduced. Of course, the fiber filter medium packed with high density does not expand during filtration. By the way, the larger the filtration tower, the longer the drainage time, and the time varies from time to time. In some cases, the filtration may be started in a state where water is not sufficiently drained, that is, in a state where the density is not high, and a predetermined filtration performance may not be satisfied. In some cases, the level inside the filtration tower installed in the water collector, here the pressure type level gauge, continuously detects the level inside the filtration tower and confirms that it is below the specified level. Then, the valve 12 installed in the discharge pipe 7 may be closed. By doing in this way, the fiber filter medium in a filtration tower can always be maintained in a high-density state, and good treated water quality can be obtained.

In the apparatus of FIG. 1, an air compaction process can be provided between the cleaning process and the water compaction process. The air compaction step is a step that is provided after the cleaning step, and supplies the air from the air supply pipe in a state where at least the filtration layer is filled with the liquid to consolidate the fiber filter medium. In the filtration layer supplied with air, the apparent specific gravity of the liquid in the filtration layer becomes lighter than in the state where air is not retained, so the difference in specific gravity between the fiber filter medium and the liquid with a reduced apparent specific gravity becomes large, and the filtration layer The bottom fiber filter media can be consolidated. On the other hand, the fiber filter material above the middle part of the filtration layer is fluidized by the action of air and is not consolidated.
In the present invention, after the air compaction process is completed, the water compaction process described above is performed. The water compaction step is a step of discharging the liquid in the filtration layer from the bottom of the filtration tower, and in this way, the fiber filter medium above the filtration layer that has not been compacted in the air compaction step can be consolidated. , The whole layer can be consolidated.

FIG. 2 is a flow configuration diagram of another example for carrying out the present invention. In the upper part, an inlet pipe 4 for raw water to be treated, a drain pipe 9 for washing water, and a short fiber in the filtration tower. A filtration layer 2 filled with a lump-like fiber filter material, a treated water collection device 3, a supply pipe 6 for supplying air, a wash water flow pipe 8 for flowing in an upward flow, and a collection pipe at the lower part of the filtration tower. In the filtration tower 1, which includes a treated water outflow pipe 5 raised from the water device 3 to at least the upper part of the filtration layer and a drain pipe 7 for draining the liquid in the water collection device 3, Equipped with a valve 12, as an efficient backwashing method for the fiber filter media in the filtration layer 2, the wash water is passed in an upward flow, and the suspended substances attached to the fiber filter media can be easily removed by supplying air. It is to make. Also in this case, the density of the fiber filter medium is set to 25 kg / m ³ or more. If necessary, a water level meter 13 may be installed in the water collecting device, and a mechanism for controlling the opening and closing of the valve 12 according to the indicated value of the water level meter 13 may be provided.

  The raw water is continuously passed through the introduction pipe 4 and filtered by a fiber filter medium packed in the filtration tower. The fiber filter medium obtained by filtering a certain amount of raw water has its inside and surface covered with suspended solids, and therefore enters the washing process periodically or by detecting an increase in filtration resistance. In the cleaning, cleaning water is supplied from the lower part of the filtration tower through the cleaning water flow pipe 8 and air is supplied through the air supply pipe 6. The rising flow rate of the washing water is determined in consideration of the rate of expansion of the fiber filter medium and the like, and the expansion rate and the like. Further, the aeration speed is a speed at which the suspended substances adhering to the fiber filter material are peeled off, and the air is aerated at a speed of about 0.1 to 5.0 m / min. The water flow and the air flow are performed at the same time, or either, or a combination thereof, and may be performed continuously, intermittently, or alternately, and the speed may be increased or decreased. You may give changes such as. In particular, when water flow and ventilation are performed at the same time, it is efficient because the suspended substance can be peeled and discharged simultaneously. The wash water containing the separated suspended matter flows out through the drain pipe 9 of the wash water installed in the upper part of the filtration tower. Washing for a certain period of time or the concentration of suspended solids contained in the washing water is detected, and the washing process ends according to the detected value. The washing time takes a time for the suspended substances attached to the fiber filter material to peel off, and is generally performed for 3 to 30 minutes.

After the washing step, the fiber filtration medium enters a consolidation step with air or a consolidation step with water. When the water flow or aeration is stopped, the fiber filter medium that has been expanded or fluidized in the liquid settles, but the density of the fiber filter medium is not sufficient by simply allowing the fiber filter medium to settle as described above. According to the present invention, in order to fill the fiber filter material submerged in water with a higher density, a compaction step with air or a compaction step with water is performed. In addition, when the compaction process by air is implemented, the compaction process by water is implemented after that. Also here, the density of the fiber filter medium is 25 kg / m ³ or more, so the water retention is good and the fiber filter medium is well consolidated.
As described above, the filtration device shown in FIG. 2 is capable of efficiently separating and separating the suspended material from the fiber filter material to which the suspended material is adhered, and always during the filtration, the fiber filter medium in the filtration tower. Can be kept in a high density state, and a good quality of treated water can be obtained. In addition, since the density of the fiber filter medium is 25 kg / m ³ or more, the water retention is good, and the filter tower in which the fiber filter medium has a sufficiently high density is simply a conventional method of filtering with the fiber filter medium submerged. In comparison, the filtration performance is high.

  FIG. 3 is a flow configuration diagram of another example for carrying out the present invention, and the porous member 10 for preventing the outflow of the fiber filter medium is installed in the filtration device of FIG. There is a concern that the fiber filter medium may flow out of the drain pipe 9 of the cleaning water during the water flow or ventilation process in the back washing process of the fiber filter medium. In particular, in the aeration process, if a large amount of suspended matter is peeled off from the fiber filter medium, the aeration speed increases. In this case, the fiber filter medium may flow out of the drain pipe 9 due to the rising air velocity. Therefore, in the present invention, the fiber filter medium flows out of the drain pipe 9 in the fiber filter medium outflow prevention porous member 10 having an opening smaller than the shortest length among the diameter of the fiber filter medium or the length of the straight line portion. Do not install the unit at any angle from horizontal to vertical with respect to the water surface. As the porous member for preventing outflow, various members such as a strainer using a mesh made of various stainless steel weaves, a wedge wire, a bar screen, etc. can be used, but at least the opening is the diameter of the fiber filter medium, or It is made smaller than the shortest length among the lengths of the straight portions. The mounting angle may be such that it is installed horizontally on the surface of the filtration tower and covers the entire surface of the filtration tower, or it is installed near the drain pipe 9 of the washing water in the vertical direction or at an arbitrary angle relative to the horizontal. Also good.

In any case, the flow rate of the cleaning water per area in contact with the water of the porous member (also referred to as water area load) in order to prevent the fiber filter medium from being stuck to the porous member due to the flow of the cleaning water. ) Is provided with a porous member so as to be 10 to 200 m / h. A porous member with a water area load of 10 m / h or less is an excessive facility and has a high initial cost, and at a water area load of 200 m / h or more, the fiber filter material sticks to the porous member. In particular, when the washing water flow rate is varied in the backwashing step, it is preferable to provide a mechanism for controlling the supply rate of the washing water so that the water area load is within the above range.
In the present invention, water flow and aeration can be carried out at high speed without worrying about the outflow of the fiber filter medium, and the washing time can be greatly reduced as compared with the conventional case, and the washing efficiency is improved. Filtration performance is good. Of course, since the fiber filter medium has a sufficiently high density, the filtration performance becomes higher compared to the conventional method in which the filter medium is simply filtered with the fiber filter medium submerged.

  FIG. 4 is a flow configuration diagram of another example for carrying out the present invention, in which part or all of the fiber filter medium in the filtration tower is surrounded by the porous member 10 for preventing outflow on the upper and lower surfaces. It is the filtration apparatus which is in the form. The life of the fiber filter medium is about 3 to 10 years, and the fiber filter medium that has exceeded the service life is replaced periodically or when a predetermined filtration performance cannot be obtained. Conventionally, the work of discharging the fiber filter medium from the inside of the filtration tower tank takes a lot of labor, and the cost for replacement has been enormous. In addition, when filling a fiber filter medium into a large filter basin, the labor was enormous. In the present invention, the upper and lower surfaces and side surfaces of the fiber filter medium are integrated by being surrounded by the porous member for preventing outflow (hereinafter, the enclosure is also referred to as a container), and a predetermined amount of the fiber filter medium is previously filled in the container at a factory or the like. , Hang it on the filter pond. In addition, when replacing the fiber filter medium, it is only necessary to pull up the container, so that the labor required for the replacement is reduced to about ½. The size of the container can be any size, but it may be a rectangular parallelepiped or cube having a side of approximately 0.5 to 3 m, or a bag. Several of these containers will be installed in the filtration basin.

Since the container is a porous member having an opening smaller than the shortest length of the diameter of the fiber filter medium or the length of the straight line portion, the container installed in the filtration tower can be filtered as it is. The filling amount of the fiber filter medium in the container can be filled in an arbitrary amount, but in order to improve the flow of the fiber filter medium due to water flow and aeration in the backwashing process, there is at least an upper space of about 50 cm. preferable.
Of course, at the end of the backwashing process, a compaction process with air and a compaction process with water, or a compaction process with water are performed to compact the fiber filter medium.

  FIG. 5 is a flow configuration diagram of another example for carrying out the present invention. In the upper part, an inlet pipe 4 for raw water to be treated, a drain pipe 9 for washing water, and a small amount of short fibers in a filter tower are shown. Filtration layer 2 filled with massive fibers, treated water collection device 3 at the bottom, supply tube 6 for supplying air, wash water flow tube 8 for upflow, and water collection device 3 and at least the upper part of the filtration layer 2 and the treated water outflow pipe 5, and a filtration tower having an intermediate drain pipe 11 for draining a part of the liquid in the filtration layer 2. A washing step for peeling off the solid matter adhering to the fiber filter medium in the tower 1, a consolidation process for supplying air from the bottom of the filtration tower in order to consolidate the fiber filter medium in the filtration tower after the washing process, and a fiber filter medium In order to consolidate the water, the drain pipe 12 provided at the bottom of the filtration tower after the air compaction step. Through, it is provided with a consolidation step by the water to drain some of the liquid in the filtration tower.

  In the cleaning method, air is supplied from the air supply pipe 6 or the cleaning water flow pipe 8 is used for cleaning using any cleaning water such as secondary treated water, industrial water, city water, or filtered raw water. The cleaned cleaning wastewater is drained through a drain pipe 9 for cleaning water. The rising flow rate of the washing water is determined in consideration of the rate of expansion of the fiber filter medium and the like, and the expansion rate and the like. Further, the aeration speed is a speed at which the suspended substances attached to the fiber filter material are peeled off, and the air is ventilated at a speed of about 0.1 to 5.0 m / min. The water flow and the air flow are performed at the same time, or either, or a combination thereof, and may be performed continuously, intermittently, or alternately, and the speed may be increased or decreased. You may give changes such as. In particular, when water flow and ventilation are performed at the same time, it is efficient because the suspended substance can be peeled and discharged simultaneously. The washing time takes a time for the suspended substances attached to the fiber filter material to peel off, and is generally performed for 3 to 30 minutes.

  In the subsequent consolidation step with air, the operation is performed as described above. In the air compaction step, the bottom of the filtration layer is compacted, and thereafter, it is only necessary to consolidate other than the bottom of the filtration layer in the water compaction step. In the consolidation step with water, the water level in the portion other than the bottom of the filtration layer that has not been consolidated in the consolidation step with air is lowered through the drain pipe 13 provided at the bottom of the filtration tower. For example, if the bottom of the filtration layer consolidated in the air consolidation step is about 40% of the entire filtration layer, the water level lowered in the water consolidation step is preferably 60% or more of the entire filtration layer. By doing in this way, in the consolidation process by air, the bottom part of the filtration layer is consolidated, and in the consolidation process by water, the other part is consolidated, and if both are combined, the entire layer is consolidated. As this effect, the amount of drainage in the consolidation process can be reduced.

Hereinafter, the present invention will be specifically described with reference to Examples and Reference Examples.
Reference example 1
Filtration using a fiber filter medium (density 90 kg / m ³ ) was performed using a φ160 mm filtration device shown in FIG. The fiber filter material was polyethylene terephthalate (PET) having a true specific gravity of 1.38, and the manufacturing method was to cut a 10 mm square of the felt manufactured by heat treatment by the needle punch manufacturing method. The filter tower was previously filled with 20 L of fiber filter material (apparent volume). After supplying raw water at a water velocity of 1000 m / d for 2 hours, the process shifted to a washing step. In the washing step, air was aerated from the bottom of the filtration tower at a rate of 1.5 m / min and supplied for about 10 minutes to peel off the suspended substances attached to the fiber filter medium. Subsequently, the raw water was supplied, and the suspended substance separated from the treated water outflow pipe 5 was discharged. After discharging the suspended solids, the filling height of the fiber filter medium in the liquid was 1200 mm (the water level was 100 mm higher than the upper surface of the filtration layer). In the next consolidation step, all of the liquid in the filtration tower was drained through the discharge pipe 7. At this time, the filling height of the fiber filter medium was 900 mm, and the fiber filter medium could be consolidated. Subsequently, when filtration was started, the SS of the treated water was 2 mg / L and the SS removal rate was 80% with respect to the concentration of suspended solids (also referred to as SS) of 10 mg / L after 30 minutes. Processing performance could be obtained.

Reference example 2
This Reference Example was the same as Reference Example 1 except that the density of the fiber filter medium (polyethylene terephthalate, 10 mm square, production was the same as Reference Example 1) was 40 kg / m ³ . In the consolidation step, the filling height of the fiber filter material after discharging the entire amount of the liquid in the filtration tower was 1000 mm. When filtration was started, 30 minutes later, the SS of the treated water was 4 mg / L and the SS removal rate was 60% with respect to the SS concentration of raw water of 10 mg / L.

Reference example 3
This Reference Example was the same as Reference Example 1 except that the density of the fiber filter medium (polyethylene terephthalate, 10 mm square, production was the same as Reference Example 1) was 25 kg / m ³ . The filling height of the fiber filter material after discharging the entire amount of the liquid in the filtration tower in the consolidation step was 1050 mm. When filtration was started, the SS of the treated water was 5 mg / L and the SS removal rate was 50% with respect to the SS concentration of 10 mg / L of the raw water 30 minutes later.

Comparative Example 1
This comparative example is a comparative example of Reference Example 1. The same as Reference Example 1 except that the density of the fiber filter medium (polyethylene terephthalate, 10 mm square, production is the same as in Reference Example 1) was 8 kg / m ³ . Even when the entire amount of the liquid in the filtration tower was discharged in the consolidation step, the filling height of the fiber filter medium was 1200 mm, and there was almost no consolidation effect. Subsequently, was started filtration, after 30 minutes, SS in the treated water with respect to SS concentration 10 mg / L of raw water is 6 mg / L, SS removal rate of 40%, performance is compared with the reference example 1 It was low. The reason for this can be considered that the filtration layer is not sufficiently consolidated, and there are many voids and SS is likely to leak.

Example 1
Example 1 is an example of FIG. It was carried out in an apparatus provided with a consolidation process with air in Reference Example 1. After the cleaning step similar to that in Reference Example 1, in the compaction step with air, the fiber filter medium at the bottom of the filtration layer was compacted by supplying air at 2 m / min. Next, in the consolidation step with water, the entire amount of the liquid in the filtration layer was drained from the bottom of the filtration tower. The filling height of the fiber filter medium at the end of the washing process was 1200 mm, 1050 mm at the end of the air compaction process, and 900 mm at the end of the water compaction process, confirming the effect of consolidation. Subsequently, when filtration was started, the SS of the treated water was 2 mg / L with respect to the concentration of suspended solids (also referred to as SS) 10 mg / L after 30 minutes, and good treatment performance could be obtained. . In addition, the amount of drainage of the consolidation process with water was 20L.

Example 2
Example 2 is an example using the filtration device of FIG. Example 1 is the same as in Example 1 except that the drainage consolidation step using an intermediate drainage pipe 11 with water. In the washing step, washing water was passed through the washing water passage pipe 8 at 1 m / min and air was washed from the air supply pipe 6 at 1.5 m / min for 10 minutes. The washing waste water was drained through a drain pipe 9 for washing water. In the consolidation step with air after the washing step, the fiber filter medium at the bottom of the filtration layer was consolidated by supplying air at 2 m / min. Next, in the compaction step with water, the fiber filter medium in the middle of the filtration layer was consolidated by draining from the intermediate drain pipe 11 to the middle of the filtration layer. The amount of drainage was 10 L, which was half that of Example 1 . Subsequently, when filtration was started, the SS of the treated water was 2 mg / L with respect to the concentration of suspended solids (also referred to as SS) 10 mg / L after 30 minutes, and good treatment performance could be obtained. .

Example 3
A filtration test was performed using the filtration apparatus shown in FIG. The flow rate of the raw water was 20 m ³ / d, the flow rate in the filtration layer was 1000 m / d, and the treated water was continuously discharged from the treated water outflow pipe 5. When SS in the raw water was captured by the fiber filter medium, the filtration performance deteriorated, so a backwash process was performed every 12 o'clock. In the backwashing method, air was supplied from the air supply pipe 6, the fiber filter medium to which SS adhered was shaken, and the SS was peeled off from the fiber filter medium. Thereafter, the cleaning water was supplied from the cleaning water flow pipe 8, and the cleaning water containing SS was discharged from the cleaning water drain pipe 9. The aeration rate was 1.5 m / min and the water flow rate was 1.0 m / min. After repeating the above backwashing process five times, the washing water in the filtration tower is drained by opening the valve 12 from the discharge pipe 7, and the water level in the water collecting device becomes 400 mm. When 13 was detected, a signal for closing the valve 12 was issued. Furthermore, after that, the washing water was supplied from the washing water flow pipe 8 to immerse the fiber filter medium, and then the filtration was resumed. In addition, the filling height of the fiber filter material after completion of water flow at the time of backwashing was 1200 mm, and the filling height of the fiber filter material at the time of resuming filtration was 900 mm. Further, the backwash time was 90 minutes, and outflow of the filter medium was seen through the discharge pipe C.
The filtration performance after 1 week was 3 mg / L for SS of treated water against SS concentration of 10 mg / L for raw water.

Example 4
A continuous filtration test was performed using the filtration apparatus shown in FIG. 2 is the same as the filtration apparatus shown in FIG. 2 except that there is a porous member 10 for preventing the outflow of the fiber filter medium. The slit width of the porous member 10 for preventing outflow of the fiber filter medium was 5 mm. The flow rate of the raw water was 20 m ³ / d, the flow rate in the filtration layer was 1000 m / d, and the treated water was continuously discharged from the treated water outflow pipe 5. When SS in the raw water was captured by the fiber filter medium, the filtration performance deteriorated, so a backwash process was performed every 12 o'clock. In the backwashing method, air was supplied from the air supply pipe 6, cleaning water was supplied from the cleaning water flow pipe 8, and the cleaning water containing SS was discharged from the cleaning water drain pipe 9. The aeration rate was 1.5 m / min and the water flow rate was 1.0 m / min. After back washing for about 8 minutes, the valve 12 is opened from the discharge pipe 7 to drain the washing water in the filtration tower, and the water level in the water collecting device is 400 mm. When detected, a signal for closing the valve 12 was issued. Thereafter, filtration was resumed. In addition, the filling height of the fiber filter material after completion of water flow at the time of backwashing was 1200 mm, and the filling height of the fiber filter material at the time of resuming filtration was 900 mm. The total backwash time was 15 minutes, and the drainage time was 4 minutes.
The filtration performance after one week was 2 mg / L for the SS of the treated water with respect to the SS concentration of 10 mg / L for the raw water. Further, there was no outflow of fiber filter media. Compared to Example 3 , the backwash time was shortened and the cleaning effect was improved, so the water quality was good.

Example 5
A filtration test was performed using the filtration apparatus shown in FIG. Except that the entire fiber filter medium is surrounded by the porous member 10, it is the same as Reference Example 1. The slit width of the porous member 10 for preventing outflow of the fiber filter medium was 5 mm. The time for newly filling the filter medium in the filtration tower was 10 minutes in Reference Example 1, but 3 minutes in this Example. Since the entire fiber filter medium is surrounded by a porous member, it is only necessary to submerge the container, and the work time is overwhelmingly reduced. The filtration performance was the same as in Reference Example 1.

The flow block diagram which shows an example for implementing this invention The flow block diagram which shows the other example for implementing this invention The flow block diagram which shows the other example for implementing this invention The flow block diagram which shows the other example for implementing this invention The flow block diagram which shows the other example for implementing this invention

  1: Filtration tower, 2: Filtration bed, 3: Water collecting device, 4: Raw water introduction pipe, 5: Treated water outflow pipe, 6: Air supply pipe, 7: Discharge pipe, 8: Wash water flow pipe, 9 : Drain pipe for washing water, 10: Porous member for preventing outflow, 11: Startup discharge pipe, 12, 14: Valve, 13: Water level gauge

Claims (4)

In the method for filtering suspended water using a filtration tower packed with short fiber lumps of fiber filter medium having a short fiber length of 5 to 100 mm, the fiber filter medium has a density of 25 kg / m ³ or more, and is subjected to filtration treatment. A method for filtering suspended water, comprising performing the following three steps later.
(1) A washing step of peeling off the solid matter attached to the fiber filter medium in the filtration tower, supplying air and washing water from the bottom of the filtration tower and discharging the solid substance peeled off from the fiber filter medium from the top of the filtration tower. ,
(2) After the washing step, in a state where the entire fiber filter medium in the filtration tower is submerged, a consolidation process by air supplying air from the bottom of the filtration tower in order to consolidate the fiber filter medium in the filtration tower,
(3) Furthermore, after the step of compacting with air, compaction with water that compacts the fiber filter medium by draining all or part of the liquid in the gap between the fiber filter medium and the fiber filter medium in the filter tower from the bottom of the filter tower. Process. It is a filtration apparatus used for the filtration method of suspension water of Claim 1 , Comprising: At the upper part, the introduction pipe | tube of the raw | natural water processed, the drainage pipe | tube of a wash water, and the inside of a short fiber with a density of 25 kg / m < ³ > or more inside A filtration layer filled with massive fiber filter material, a treated water collecting device at the bottom, a supply pipe for supplying air to the filtration layer, and a wash water flow pipe for flowing upward through the filtration layer A treated water outflow pipe set up above the filtration layer from the water collection device, a discharge pipe for draining all or part of the liquid in the filtration layer from the water collection device , or the water collection device Kararo filtration apparatus characterized in that it comprises a filtration column and a part of the liquid emissions tubes is raised to the filtration layer intermediate for draining of the over layer. In the upper part of the filtration tower, a porous member for preventing the outflow of the fiber filter medium having an opening smaller than the shortest length among the diameter of the fiber filter medium or the length of the straight part is provided in the upper part of the filtration tower. The filtration apparatus according to claim 2 , wherein the filtration apparatus is installed upstream of a drain pipe for washing water of the fiber filter medium. 4. The filtration apparatus according to claim 3 , wherein a part or all of the filtration layer in the filtration tower is integrated with the upper and lower surfaces and side surfaces surrounded by the outflow prevention porous member.

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