JP2005152777A - Filtration tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filtration tank capable of highly maintaining a cleaning performance of a filter medium without performing the maintenance of a diffuser pipe for a long period of time. <P>SOLUTION: The inside of the filtration tank 1 is composed of a raw water supply pipe 2, an upper filter medium runoff prevention plate 3, a filtration layer 4 comprising the filter medium, the diffuser pipe 5, a filter medium support plate 6 and a treated water discharge pipe 7 etc. Therein, a circulation path 11 is formed so as to branch off from the treated water discharge pipe 7. The circulation path 11 on which a motor-operated valve 8, a pump 9 and a check valve 10 are arranged is connected to the diffuser pipe 5. An air supply pipe on which a blower 12 as an air supply source and a check valve 13 are arranged is connected to the diffuser pipe 5. In the filtration tank thus constituted, one part of the treated water is passed through the circulation path 11 and water is supplied to the diffuser pipe 5 during the filtration of the raw water. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a filter tank in which a filter layer is formed by a filter medium for physically removing suspended matter contained in waste water or a filter medium for fixing microorganisms to remove soluble substances.

  A sewage or muddy water treatment device is filled with a filter medium such as gravel, sand, activated carbon, or plastic filter medium in a circular or rectangular filter tank to form a filter layer, and raw water is supplied from the top of the filter tank. Supply and pass water in a downward flow, or supply raw water from the lower part of the filtration tank and pass it in an upward flow to physically remove suspended matter. In addition, microorganisms are fixed on the particulate carrier filter medium, and dissolved substances such as organic substances and nitrogen components are biologically oxidized.

  When these filtration tanks are subjected to filtration treatment for a certain period of time, the filtration layer is clogged with suspended solids and biofilms, and therefore it is necessary to periodically clean the filter medium.

As a cleaning method for the filter media, an air diffuser for cleaning is placed in the lower part of the filter tank, air is blown out from a plurality of through holes provided in the air diffuser, and along with the wash water injected into the filter tank The suspended matter and biofilm attached to the filter medium are peeled off and discharged out of the filtration tank as washing waste water.
JP 2000-024679 A JP-A-6-198295

  However, in the above-described conventional technology, when air is no longer ejected from the through hole of the air diffuser after the filter media cleaning is completed, residual suspended matters that are not discharged during the filter media cleaning and biofilms generated during the filtration operation Dirt such as adheres to the surface of the through-hole of the diffuser tube and inside the through-hole, causing clogging. When air is blown out from the through-hole of the air diffuser during the next cleaning, the deposits at the center of the through-hole are removed by being blown away by the blown-out air, but dirt attached around the inner wall surface of the through-hole is removed. It remains without being completely removed, and when it comes into contact with the air that blows out, the dirt is dried and hardened.

  If such a phenomenon is repeated for each cleaning and the dirt around the through-hole of the air diffuser becomes large, there is a problem that the amount of air jetted is reduced and the cleaning performance of the filter medium is deteriorated. In addition, it is conceivable to increase the diameter of the through hole of the air diffuser in advance so that the cleaning performance of the filter medium can be maintained for a long time even if dirt around the through hole of the air diffuser becomes large. When the hole is enlarged, the output pressure of air is lowered, and the cleaning performance of the filter medium is also lowered.

  The present invention was devised to solve the above-described problems, and an object of the present invention is to provide a filtration tank that can maintain the cleaning performance of a filter medium at a high level without performing maintenance of an air diffuser for a long period of time. It is said.

  In order to achieve the above-mentioned object, the invention according to claim 1 supplies raw air to a raw water supply unit, a filtration layer for filtering raw water, a treated water discharge unit for discharging filtered treated water, and air to the filtration layer. In a filtration tank comprising a diffuser tube having a through-hole formed therein, a water supply source is connected to the diffuser tube, and water is supplied from the water supply source to the diffuser tube during a filtration operation to penetrate the diffuser tube. It is a filtration tank characterized by draining water from the hole.

  The invention according to claim 2 is characterized in that the water supply source is configured to branch the treated water from the treated drainage portion and circulate a part of the treated water to the diffuser. It is a filtration tank of claim | item 1.

  According to the present invention, water is allowed to flow out from the through hole of the air diffuser after completion of cleaning of the filter medium, so that the dirt attached to the through hole of the air diffuser is prevented from being dried and the attached dirt is removed. The cleaning performance of the filter medium can be maintained without carrying out maintenance of the diffuser pipe for a long period of time, preventing clogging of the holes of the diffuser pipe, and removing and cleaning the filter medium. This maintains the filtration performance at a constant level for a long time.

  In addition, by using a part of the treated water treated in the filtration tank as the water discharged from the hole of the air diffuser, it is possible to save the trouble of drawing water from other places. Can save water to supply.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of a filtration tank to which the present invention is applied.

  As shown in FIG. 1, the inside of the filtration tank 1 includes a raw water supply pipe 2 as a raw water supply section, an upper filter material outflow prevention plate 3, a filtration layer 4 composed of a filter material, an air diffuser tube 5, and a filter material support plate. 6, a treated water discharge pipe 7 serving as a treated water discharge unit, and the like. A circulation path 11 is formed by branching from the treated water discharge pipe 7. In the circulation path 11, an electric valve 8, a pump 9, and a check valve 10 are arranged and connected to the diffuser pipe 5. On the other hand, an air supply pipe in which a blower 12 as an air supply source and a check valve 13 are arranged is also connected to the air diffusion pipe 5.

  The filtration tank 1 is called a downward flow type filtration tank. The raw water supplied from the raw water supply pipe 2 flows in from the upper part of the filtration tank 1 and the treated water purified by the filtration layer 4 is treated water. It passes through the discharge pipe 7 and is taken out as treated water.

  The filtration tank 1 is a pressure vessel having a circular cross section, and can treat water in a cooling tower on the roof of a building, water in a distant pond, and fountain. Further, because of the pressure vessel, the flow rate can be easily adjusted without overflowing water from the filtration tank 1. Further, the filtration tank 1 may be a container other than the pressure container, and may be an open container, for example, but the pressure loss when the filtration layer 4 is clogged so that water does not flow from the filtration tank 1 is reduced. Adjustments such as having to determine the flow rate in consideration are necessary.

  The raw water supply pipe 2 is introduced into the filtration tank 1 from the outside and extends to the center position of the filtration layer 4. The opening through which the raw water is discharged from the raw water supply pipe 2 is open upward in a trumpet shape so that the raw water flows evenly on the surface of the filtration layer 4.

  The upper filter medium outflow prevention plate 3 is used to prevent the filter medium from being discharged from the filter tank 1 when the filter medium is washed. The upper filter material outflow prevention plate 3 has a structure that allows water to pass through, such as a net shape or a slit shape, and is formed to withstand water pressure or air pressure from the air diffuser pipe 5. Moreover, the total area of the opening part through which the water of the upper filter material outflow prevention plate 3 passes needs to be at least equal to or larger than the pipe cross-sectional area of the raw water supply pipe 2, and the filter medium used for the filter layer 4 passes therethrough. You must not do it.

  In addition, when using a filter medium with very small particles such as sand or anthracite and heavy specific gravity, it is possible to prevent the discharge of the filter medium by adjusting the flow rate of water or air during cleaning. The upper filter material outflow prevention plate 3 may not be installed.

  The filter layer 4 is made of fiber filter material, plastic filter material, or the like having a specific gravity of 1 or more. This is because when the specific gravity is less than 1, it is lighter than water, and the filter medium floats on the water and the filtration layer 4 cannot be formed stably.

  By the way, since the filter medium with a high filling rate and a high porosity has a high filtration capacity and a small pressure loss, a load applied to a raw water supply device such as a pump and a filtration tank is small. Further, in order to increase the cleaning efficiency because the filter medium is easy to move during cleaning of the filter medium, the specific gravity is preferably close to 1. For example, a specific gravity of about 1.4 does not float on water, and the cleaning efficiency is also good. FIG. 3 shows an example of a filter medium taking these points into consideration, and a filter medium 14 made of plastic is shown.

  The filter medium 14 shown in FIG. 3 is the same as the filter medium disclosed in Japanese Patent Laid-Open No. 2002-233717, and the side edges of one side of the plastic belt-like sheet member having no through-holes are folded so that the ridges are continuous. The other side edge of the belt-like sheet member is converged and arranged at the central portion, thereby forming a substantially spherical shape as a whole.

  The air diffuser 6 is installed in the lower part in the filtration layer 4, and has a shape in which a plurality of through holes 15 are opened toward the filtration layer 4 in the pipe. FIG. 4 is an example of the air diffuser 5 and is a view seen from the upper side of the filtration tank 1. The shape of the air diffuser pipe 5 is circular according to the cross-sectional shape of the filtration tank 1, and piping is arranged around the circumference, so that air is evenly fed into the circumferential pipe from the center of the circle to the circumferential pipe. Air is sent in. Through holes 15 are formed not only in the upper part of the diffuser pipe 5 but also in the obliquely lower part of the diffuser pipe 5 so that air is blown out upward of the circumferential pipe and obliquely downward of the circumferential pipe.

  For example, when a spherical filtration medium 14 having a filtration tank inner diameter of φ1500 mm and a diameter of φ15 mm is used, the diffuser pipe 5 has a circumferential diameter of φ1000 to 1300 mm, a pipe inner diameter of φ15 to 25 mm, and a diameter of the through hole 15 of φ2 A pitch of 100 mm to 150 mm is desirable.

  Like the upper filter material outflow prevention plate 3, the filter material support plate 6 is provided so that the filter medium is not discharged from the filter tank 1, and may have a structure that allows water such as a net shape or a slit shape to pass through. It is configured to withstand the water pressure and air pressure during cleaning and to withstand the weight of the filtration layer 4.

  The total area of the opening part through which the water of the filter medium support plate 6 passes needs to be at least larger than the pipe cross-sectional area of the raw water supply pipe 2, and is configured so that the filter medium used for the filter layer 4 does not pass through. ing.

  The treated water discharge pipe 7 is a pipe introduced into the filtration tank 1 from the outside, and discharges the treated water filtered by the filtration layer 4 to the outside and sends the washing water to the filtration layer 4 when the filter medium is washed. Is. The treated water discharge pipe 7 extends to the center position of the filtration layer 4 so that the cleaning water can be evenly fed, and the opening is opened upward in a trumpet shape.

  A circulation path 11 or the like is configured as a water supply source for supplying water to the air diffusion pipe 5, and the circulation path 11 is branched from the middle of the treated water discharge pipe 7, and a part of the filtered treated water that flows to the treated water discharge pipe 7. Is supplied to the diffusing tube 5. The motor-operated valve 8 is provided in order to prevent the cleaning water from flowing into the diffuser pipe 5 at the time when the cleaning water is sent into the filter tank 1 from the treated water discharge pipe 7 when the filter medium is cleaned. .

  In addition, as a water supply source for supplying water to the air diffuser 5, a water supply is provided between the check valve 13 and the air diffuser 5 without adopting a configuration in which a part of the treated water is circulated to the air diffuser 5 as described above. It is good also as a structure which connects a water supply source directly and sends tap water directly.

  The pump 9 sends part of the treated water to the diffuser pipe 5 during the filtering operation, and causes the water to flow out from the through hole 15 of the diffuser pipe 5. A check valve 13 is provided so that water flowing through the circulation path 11 does not flow into the blower 12 when the pump 9 is in operation and the blower fails, and the air sent from the blower 12 to the diffuser pipe 5 is circulated when the filter medium is washed. A check valve 10 is provided so as not to flow into the path 11.

  FIG. 5 shows the entire filtration processing system using the downward flow filtration tank configured as described above, and FIG. 6 shows the control operation.

  The configuration around the filtration tank 1 in FIG. 5 is exactly the same as the configuration shown in FIG. 1, and the components having the same numbers have the same functions as those described in FIG.

  As a configuration newly added to the configuration of FIG. 1, a pump 41 is installed upstream of the raw water supply pipe 2, and an electric valve 51 is provided between the pump 41 and the filtration tank 1 in the treated water discharge pipe 7. An electric valve 57 is installed.

  Further, there is a washing water supply pipe 42 which branches from between the pump 41 and the motor operated valve 51 and extends between the motor operated valve 57 and the filtration tank 1 in the treated water discharge pipe 7. A motorized valve 52 is provided.

  On the other hand, there is a cleaning drainage pipe 43 branched from the motor-operated valve 51 on the raw water supply pipe 2 and the filtration tank 1 and connected to the drainage groove 45, and the cleaning drainage pipe 43 is provided with an electric valve 53. Has been.

  Further, there is a rinse drain discharge pipe 44 branched from the circulation path 11 and the motor operated valve 17 in the treated water discharge pipe 7 and flowing into the drain groove 45, and the motor operated valve 54 is installed on the rinse drain discharge pipe 44. Has been.

  The pump 41, the pump 9, the blower 12, and the motor operated valves 8, 51, 52, 53, 54, 57 are connected to a control panel or the like and controlled according to the control operation of FIG. Although the motorized valve is used in the above embodiment, a manual valve may be used, and the number of valves can be reduced by using a three-way valve or a five-way valve.

  According to the control operation of FIG. 6, first, the pump 41 and the pump 9 are operated, the blower 12 is stopped, the motor-operated valves 51, 57, and 8 are opened, the other motor-operated valves are closed, and the filtration operation is performed. Is called. The raw water that has flowed into the filtration tank 1 from the raw water supply pipe 2 by the operation of the pump 41 is filtered by the filtration layer 4, and the treated water that has been filtered passes through the treated water discharge pipe 7 and the electric valve 57 to the outside. It is taken out.

  On the other hand, part of the treated water passes through the motor-operated valve 8, is pushed out from the pump 9, flows into the diffuser pipe 5 through the check valve 10, and flows out from the through hole 15 of the diffuser pipe 5. In this way, since water always flows out from the through hole 15 of the air diffuser 5 during the filtration operation, it is possible to prevent the dirt attached to the through hole 15 from being dried, and the dirt is not firmly solidified. The clogging of the through hole 15 can be prevented.

  Next, when a certain time elapses due to a timer or the like in the control panel, the filtration operation is switched to the cleaning operation. As shown in FIG. 6, the cleaning operation is divided into three stages. In the first first stage (air cleaning), the pump 41 and the pump 9 are stopped, the motor-operated valve 52 and the motor-operated valve 53 are opened, and other motor-operated valves. After closing the filter, the blower 12 is operated, and only the air is blown out from the diffuser tube 5 to stir the filter medium of the filter layer 4 and to remove the dirt, such as suspended matter attached to the filter medium, from the filter medium. Let

  In the next second stage (air backwashing), the pump 41 is operated from the state of the first stage, and the raw water is supplied to the treated water discharge pipe 7 through the washing water supply pipe 42 and ejected from the lower part in the filtration tank 1. In this way, while further enhancing the cleaning performance by the water flow and air, the dirt is passed through the cleaning drainage pipe 43 from the raw water supply pipe 2 along with the cleaning drainage and discarded into the drainage groove 45.

  In the final third stage (rinse cleaning), the blower 12 and the pump 41 are stopped from the state of the second stage, the motorized valves 51 and 54 are opened, the other valves are closed, and then the pump 41 is restarted. Make it work. After the second stage air backwashing is completed, in order to prevent dirt such as suspended matter and biofilms that have not been discharged together with the washing wastewater from flowing out as treated water, it is necessary to maintain a certain amount after washing. Raw water is supplied from the hourly raw water supply pipe 2 into the filtration tank 1, and the treated water that has passed through the filtration layer 4 is discarded into the drainage groove 45 via the treated water discharge pipe 7 and the rinse drain discharge pipe 44. The frequency of cleaning and the time of each stage of the cleaning operation are managed by a timer in the control panel.

  The frequency of cleaning and the time of each stage of the cleaning operation are affected by the amount of filter medium, the type of filter medium, the amount of dirt, the amount of air, the pump performance, etc. The filter tank 1 has a cross-sectional diameter of φ1500 mm, the amount of filter medium is 1500 L (liter), the filtration flow rate is 40 t (tons) per hour (cleaning flow rate: 40 t / h), and the water in the tidal pond 250 t Is operated in a circulatory system for 24 hours, the air flow rate is 800 L / min, the cleaning frequency is 1 week to 1 month, the first stage of the cleaning operation is 5 to 25 minutes, and the second stage is 5 to 15 Minutes, the third stage is 1-5 minutes.

  In addition, by removing dirt without using water in the first stage, it is possible to save the amount of washing water used in the second stage, so when processing water such as fountains and cooling towers in the circulation system, The amount of water added to the cooling tower can be reduced.

  Note that the cleaning operation may be started from the second stage without performing the first stage of the cleaning operation, but in this case, it is necessary to extend the time of the second stage.

  Next, the Example which applied this invention to the upward flow type filtration tank is shown.

  2 is a schematic configuration diagram when applied to an upward flow filtration tank, FIG. 7 is an overall configuration diagram of a filtration processing system using the upward flow filtration tank of FIG. 2, and FIG. 8 is the system of FIG. This shows the control operation.

  In the upward flow type filtration tank, processing from raw water to treated water is performed from the lower part to the upper part of the filtration tank 21, so that the raw water supply pipe 22 is at the lower part of the filtration tank 21 and the treated water discharge pipe 27 is the filtration tank. It arrange | positions at the upper part of 21 and is arrange | positioned contrary to the downward flow type filtration tank of FIG.

  Since the filtration tank 21 is not a sealed container but is open at the top, it is necessary to adjust the treatment flow rate so that the treated water does not overflow from the filtration tank 21.

  Moreover, the filter medium which forms the filtration layer 24 uses the floating type filter medium using the material whose specific gravity is smaller than water, such as a polystyrene foam.

  The upper filter material outflow prevention plate 23 is used to prevent the filter medium from being discharged from the filter tank 21 when the filter medium is washed. The filter medium support plate 26 is also provided so that the filter medium is not discharged from the filter tank 21, as is the upper filter medium outflow prevention plate 23. Both the upper filter material outflow prevention plate 23 and the filter material support plate 26 may have a net-like or slit-like structure that allows water to pass through, and are formed so as to withstand the water pressure and air pressure during the filter material cleaning. ing.

  The air diffuser 25 has the structure described with reference to FIG. 4, and air and water are ejected from the through hole 15. A circulation path 31 or the like is configured as a water supply source for supplying water to the diffuser pipe 25, and the circulation path 31 is branched from the middle of the treated water discharge pipe 27 and a part of the filtered treated water flowing into the treated water discharge pipe 27. Is supplied to the air diffuser 25. The motor-operated valve 28 is provided in order to prevent the cleaning wastewater from flowing into the diffuser 25 at the time when the cleaning wastewater flows into the treated water discharge pipe 27 when the filter medium is cleaned.

  In addition, as a water supply source for supplying water to the air diffusion pipe 25, a water supply is provided between the check valve 33 and the air diffusion pipe 25 without adopting a configuration in which a part of the treated water is circulated to the air diffusion pipe 25 as described above. It is good also as a structure which connects a water supply source directly and sends tap water directly.

  In the case of cleaning the filter medium, air is supplied from the blower 32 to the diffuser pipe 25, and the filter medium is washed with the cleaning water supplied from the raw water supply pipe 22 into the filter tank 21 while stirring the filter medium of the filter layer 24. The cleaning waste water is discharged from the processing discharge discharge pipe 27.

  The check valve 30 prevents air from the blower 32 from entering the circulation path 31 at the time of cleaning the filter medium, and the check valve 33 is water that is sent from the circulation path 31 to the air diffuser 25 during the filtration operation. Is prevented from flowing into the blower 32.

  As described above, the floating filter medium is used as the filter medium, but a filter medium having a specific gravity greater than that of water may be used. When using a filter medium with a specific gravity greater than that of water, the filter medium must be sufficiently agitated and washed with air, so a stirring blade, etc. should be installed at the bottom of the filter tank to force the filter medium. It is necessary to add a structure such as stirring.

  In the filtration processing system of FIG. 7, in addition to the configuration of the upward flow filtration tank of FIG. 2, a pump 61 is provided on the raw water supply pipe 22 to send the raw water from the raw water supply pipe 22 into the filtration tank 1. An electrically operated valve 71 is installed on the treated water discharge pipe 27. A part of the treated water discharge pipe 27 is branched in front of the motor-operated valve 71 and connected to the drain groove 73, and the motor-operated valve 72 is arranged on the pipe toward the drain groove 73.

  The control operation of the filtration processing system of FIG. 7 described above will be described with reference to FIG.

  First, the blower 32 is stopped, the pumps 61 and 29 are operated, the motorized valves 71 and 28 are opened, the motorized valve 72 is closed, and the filtration operation is performed. During the filtration operation, the raw water is pushed out by the pump 61 and flows into the filtration tank 21 through the raw water supply pipe 22, and the raw water that has flowed into the filtration tank 21 is filtered by the filtration layer 24 to the treated water discharge pipe 27. The filtered treated water reaches the motorized valve 71 via the treated water discharge pipe 27 and is taken out to the outside.

  On the other hand, part of the treated water that passes through the treated water discharge pipe 27 passes through the motor-operated valve 28, is pushed out by the pump 29, and is supplied to the diffuser pipe 25 through the check valve 30. A part of the treated water supplied to the air diffuser 25 flows out from the through hole 15. As described above, since water always flows out from the through hole 15 of the air diffuser 25 during the filtration operation, it is possible to prevent the dirt adhering to the through hole 15 from being dried, and the dirt is not firmly solidified. The clogging of the through hole 15 can be prevented.

  On the other hand, the cleaning operation is divided into three stages similar to the operation described in FIG. 6. In the first first stage (air cleaning), the pumps 61 and 29 are stopped, the motor-operated valve 72 is opened, and the other motor-operated valves. Is closed, the blower 32 is operated, and only the air is ejected from the diffuser tube 25 to stir the filter medium and to remove the dirt composed of suspended matter or the like adhering to the filter medium from the filter medium.

  In the next second stage (air backwashing), the pump 61 is operated from the state of the first stage, and the raw water is ejected from the lower part of the filtration tank 21 through the raw water supply pipe 22, thereby further washing with water flow and air. While enhancing the performance, the dirt is discarded into the drainage groove 73 from the treated water discharge pipe 27 via the motor-operated valve 72 together with the cleaning drainage.

  In the final third stage (rinse cleaning), the blower 32 is stopped from the state of the second stage, and the pump 61 is operated as it is. The raw water supplied from the raw water supply pipe 22 passes through the filtration layer 24 and flows into the treated water discharge pipe 27, and the rinse drainage is discarded into the drainage groove 73 via the motor operated valve 72. The frequency of cleaning and the time of each stage of the cleaning operation are managed by a timer in the control panel.

It is a schematic block diagram of the downward flow type filtration tank of this invention. It is a schematic block diagram of the upward flow type filtration tank of this invention. It is a figure which shows an example of the filter material which comprises a filtration layer. It is a figure which shows an example of a structure of a diffuser tube. It is a piping system diagram of a filtration processing system using a downward flow type filtration tank. It is a figure which shows the control action of the system of FIG. It is a piping system diagram of a filtration processing system using an upward flow type filtration tank. It is a figure which shows the control action of the system of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filtration tank 2 Raw water supply pipe 3 Upper filter material outflow prevention plate 4 Filtration layer 5 Aeration pipe 6 Filter material support plate 7 Treated water discharge pipe 8 Electric valve 9 Pump 10 Check valve 11 Circulation path 12 Blower 13 Check valve 14 Filtration Material 15 Through-hole 21 Filtration tank 22 Raw water supply pipe 23 Upper filter material outflow prevention plate 24 Filtration layer 25 Aeration pipe 26 Filter material support plate 27 Treated water discharge pipe 28 Electric valve 29 Pump 30 Check valve 31 Circulation path 32 Blower 33 Reverse Stop valve

Claims (2)

In a filtration tank comprising a raw water supply part, a filtration layer for filtering raw water, a treated water discharge part for discharging filtered treated water, and an air diffuser tube having a through hole for supplying air to the filtration layer,
A filtration tank, wherein a water supply source is connected to the diffuser pipe, and water is supplied from the water supply source to the diffuser pipe during a filtering operation to discharge water from a through hole of the diffuser pipe. 2. The filtration tank according to claim 1, wherein the water supply source is configured to divide the treated water from the treated drainage unit and circulate a part of the treated water to the aeration pipe.

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