JP2008093552A - Moving-bed filtration apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving-bed filtration apparatus capable of automatically washing a screen. <P>SOLUTION: The moving-bed filtration apparatus includes: a water level adjusting device 40 for adjusting the water level of raw water inside a filter tank 1 at a predetermined level position below the screen 2; a washing device 50 arranging a spray nozzle 56 above the screen 2 in a state of directing a spray opening toward the upper surface of the screen 2, and for spraying washing water supplied from a water supply device to the upper surface of the screen 2 from the spray nozzle 56; and a washing control device 60 constituting a washing cycle by performing stop of raw water pump P<SB>1</SB>by sequential control, adjustment of the water level by the water level adjusting device 40, and spray of the washing water to the upper surface of the screen 2 by the washing device 50 over a predetermined period of time in this order, and for repeating this washing cycle at a time interval set by a timer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a moving bed filtering apparatus, and more particularly to a moving bed filtering apparatus having an automatic screen cleaning function.

Conventionally, as a device for purifying sewage such as sewage, filter media layers are formed by accumulating resin filter media having levitating properties in a filtration tank, and raw water is filtered through the filter media layer from above to below. In addition, a moving-bed type filtration device is used in which treated water is taken out of the filtration tank, and the filter medium is pulled out from the upper part of the filter medium layer and purified, and then returned to the filtration tank. An example of a bed filtration device is shown.
JP 2005-296792 A

  And in order to prevent the above-mentioned filter medium having the floatability from rising and form a filter medium layer, as described in the above-mentioned patent document, a screen having a mountain-shaped cross section with the center (center) as the apex at the top of the filter tank In order to provide gas-liquid permeability, this screen usually has a configuration in which wedge wires are arranged side by side with a small gap.

  However, since this screen is in contact with highly contaminated raw water that has flowed into the upper part of the filtration tank, the screen is subject to the attachment and accumulation of suspended solids mixed in the raw water as the operating time of the filtration device elapses. In particular, a diffusion device is installed at the bottom of the filtration tank to supply air to the filter medium layer to form a biofilm on the surface of the filter medium, and to perform biofilm filtration along with physical filtration with the filter medium. In the filtration apparatus, the biofilm adheres and accumulates on the screen, so that the adhering deposit closes the gap portion of the wedge wire of the screen and becomes clogged. If this clogging occurs over a wide area, the air rising in the filter medium layer accumulates under the vicinity of the center of the screen, forming a cavity, making it difficult to pull out the filter medium from the top of the filter medium layer. Since the filter media is hindered and the liquid flow resistance of the screen increases, the level of the water level at the top of the filtration tank fluctuates greatly, which may hinder smooth filtration due to overflow of raw water and fluctuations in the discharge rate of treated water. Will come.

  Therefore, in order to prevent clogging of the screen, the field workers have conventionally cleaned the screen from the top of the filtration tank about once a week. However, this cleaning requires manual labor and maintenance costs. If the filter is installed in a place where workers for inspection and cleaning are difficult to access, such as deep underground, it is more difficult to clean the screen manually.

  The present invention is intended to solve the above-mentioned conventional problems, and an object of the present invention is to provide a moving bed type filtration device capable of automatically performing screen cleaning without manpower.

  In order to achieve the above-mentioned object, the moving bed type filtration apparatus according to claim 1, wherein a screen having a mountain-shaped cross section with the center at the top is disposed in the filtration tank to form a filter medium layer floating below the screen. The raw water supplied by the pump is filtered through the filter medium layer from the top to the bottom, and treated water is taken out of the filtration tank, and the filter medium is extracted from the top of the filter medium layer and purified, and then the filter medium is removed. In a moving bed type filtration apparatus comprising a filter medium regenerating apparatus for returning to the lower part of the filter tank and an air diffuser for supplying air to the filter medium layer, the water level of the raw water in the filter tank is set below the screen. A water level adjusting device that adjusts to a predetermined level position, and a spray nozzle disposed above the screen with a spray nozzle facing the upper surface of the screen, and the cleaning water supplied by the water supply device is placed in front of the spray nozzle. A cleaning device sprayed on the upper surface of the screen, stop of the raw water pump by sequence control, adjustment of the water level by the water level adjusting device, and spraying of the cleaning water on the upper surface of the screen for a predetermined time by the cleaning device, A cleaning cycle is configured by performing in this order, and a cleaning control device that repeats the cleaning cycle at time intervals set by a timer is provided.

  According to the first aspect of the present invention, the level of the raw water in the filtration tank is adjusted to the level position on the lower side of the screen by the water level adjusting device while the raw water pump is stopped, and the cleaning water is blown from the spray nozzle to the upper surface of the screen. As a result, the cleaning water is sprayed on the upper surface of the screen with the water surface of the raw water spaced apart downward, and the deposited deposits on the screen are surely and easily separated and removed. Since the process is automatically repeated, the screen can be automatically cleaned without manpower.

  In this invention, the spray nozzle of the cleaning device may be configured such that a large number of spray nozzles are fixedly arranged at an upper position of the screen so that cleaning water is sprayed over a wide range on the upper surface of the screen. As described above, the spray nozzle of the cleaning device is attached to a rotating body that is rotatably supported around a central axis, and the cleaning nozzle rotates the spray water about the central axis from the screen. If it is configured to spray on the upper surface, the cleaning water can be sprayed uniformly on the upper surface of the screen by a small number of spray nozzles, and the amount of cleaning water used can be reduced.

  In the invention described in claim 2, the rotating body of the cleaning device may be configured to be rotationally driven by a rotary driving machine such as a motor. However, as in the invention described in claim 3, the rotating body and the attachment attached thereto. If the spray nozzle is configured to be driven to rotate around the central axis by the reaction force of the cleaning water jet from the spray nozzle, the rotary drive unit and the rotation control device are not required, and the apparatus is simplified. -It is particularly preferable because it requires a low cost and the operation cost is reduced.

  As described above, according to the present invention, the screen provided in the upper part of the filtration tank can be automatically washed without manpower, and the smooth operation and the maintenance cost of the moving bed type filtration apparatus can be reduced. It contributes.

  In addition to the above-described effects, according to the second aspect of the invention, the number of spray nozzles and the amount of cleaning water used can be reduced.

  In addition to the above effects, according to the third aspect of the invention, the cleaning device according to the second aspect of the invention can be made simple and low-cost, and its operating cost can be low.

  Hereinafter, an embodiment of the present invention will be described with reference to an example shown in FIGS. In FIG. 1, reference numeral 1 denotes a filtration tank, and a screen 2 having a chevron cross section with the center at the top is attached to the upper part of the filtration tank, and a filter medium comprising an aggregate of filter media 3 having fine floating properties below the screen 2. Layer 4 is formed over a predetermined height. The filter medium is made of a porous resin having a diameter of several millimeters, and is prevented from floating on the water surface by the screen 2. As shown in FIG. 2, the screen 2 has a large number of wedge wires 5 arranged in parallel with a small gap g (0.7 mm in this example). The separation and removal method will be described later. Reference numeral 50 denotes a rotary cleaning device provided above the screen 2, and 45 denotes an ultrasonic level meter for detecting the water level Lh of the raw water in the filtration tank 1, details of which will be described later.

Reference numeral 11 denotes a raw water inflow pipe, which is connected to the raw water tank 12 via the raw water pump P _1, and a guide plate 13 that expands upward is attached to the tip of the filtration tank 1. Reference numeral 15 denotes an air diffuser which is connected to an air supply blower 16 for supplying air into the filter medium layer 4 to maintain the growth of a biofilm composed of microorganisms attached to the surface of the filter medium 3. Reference numeral 21 denotes a water collecting pipe provided at a lower position of the air diffusion pipe 15, and a strainer is provided at a water collecting port provided at a predetermined interval. 23 is a treated water discharge pipe connected to the water collecting pipe 21, and its intermediate part 23 a is raised to the normal water level Lh of the raw water in the filtration tank 1, and then connected to the miscellaneous water tank 25 via the UV sterilizer 24. Has been. The intermediate portion 23 a communicates with the outside air through the vent pipe 26.

The raw water supplied into the filtration tank 1 through the raw water inflow pipe 11 by the operation of the raw water pump P ₁ passes from the upper side to the lower side through the filter medium layer 4 and is physically filtered by the filter medium 3 and the biofilm attached to the filter medium 3. is purified by receiving a biological membrane filtration according to the in-off valve V ₁ open state of the treated water discharge pipe 23, flows in the form of overflow in the intermediate portion 23a, after sterilization by ultraviolet sterilizer 24, chore aquarium 25 as treated water Is discharged. In this example, this treated water is supplied to a sand basin by a miscellaneous water supply device 27 having a pump and a pressure tank, and used as washing water for a sand basin equipment. Is also used.

Reference numeral 30 denotes a filter medium regenerator, and a filter medium drawing tube 32 having a tip opened at a position directly below the center of the screen 2 is connected to an intermediate part of the filter medium storage / separation tank 31 constituting the main body. At the bottom of Matarozai reservoir separation tank 31, the on-off valve V ₃ and the drain pipe 33 provided with a pump P ₂ of filter medium drawing is connected, the drain pipe 33 of the water inlet pipe 11 via an on-off valve V ₄ Connected to the middle part. 34 is a secondary pipe for water intake which one end opens into the filter tank 1, is connected via a return pump P ₃ to the top of the filter material reservoir separator tank 31, in the connecting point Q, a reflux water supply pipe below It is connected to the filter medium return pipe 35 that also serves as the filter medium return pipe 35, and the tip of the filter medium return pipe 35 opens into the lower part of the filtration tank 1.

When the filter medium is regenerated by the filter medium regenerating apparatus 30, first, as a filter medium drawing process, the on-off valves V ₂ , V ₃ , and V ₄ are opened, the pump P ₂ is operated, and the filter medium 3 is pulled out together with the raw water from the upper part of the filter tank 1. . While the filter medium 3 sucked into the filter medium storage / separation tank 31 is raised by buoyancy and left to stand, the attached sludge is separated and regenerated downward by gravity, and the raw water containing the sludge flows into the drain pipe 33 and the raw water. It returns to the inside of the filtration tank 1 through the pipe 11. Next, as the filter medium returning step, each on-off valve is closed (hereinafter the same), the on-off valves V ₅ , V ₆ , V ₇ are opened, the return pump P ₃ is operated, and the filter tank 1 is drawn out. If the treated water is fed from the auxiliary pipe 34 to the filter medium return pipe 35 via the connection point Q, the filter medium 3 floating on the top of the filter medium storage / separation tank 31 is caught in the treated water, and the filter medium return pipe 35 is Then, it is returned to the filtration tank 1. Next, as the waste sludge step of discharging the sludge at the bottom of the filter media storage separation tank 31, driving a pump P ₂ to open the on-off valve _{V 7, V 3, V 8} , filter media return pipe 35 from the bottom of the filter tank 1 The treated water that is made to flow backward flows through the filter medium storage and separation tank 31 as a downward flow, and is discharged to the sand basin through the sludge pipe 36. And each process of these filter media reproduction | regeneration is intermittently implemented by predetermined | prescribed cycle time by the control apparatus which is not shown in figure.

41 is a discharge pipe provided with a closing valve V _9, one end is open at the bottom of the filtration tank 1, the other end is connected to Haidorokan 36 through an intermediate portion of drain pipe 33, these conduits In addition, by using the pump P ₂ and the on-off valve V ₈ , together with the level meter 45 described above, a water level adjusting device 40 that discharges treated water in the filtration tank 1 and adjusts the water level of the raw water is configured.

  Next, FIG. 3 and FIG. 4 show the details of the rotary cleaning device 50, and a rotary shaft is attached to the upward bent end portion of the water supply pipe 51 that is fixedly attached to the wall portion through the wall portion of the filtration tank 1. A rotating body 53 formed by connecting a joint 52 and connecting a tee to a short tubular shaft fitted and communicated with the rotary joint 52 is rotatable around a central axis 54 extending vertically through the center of the screen 2. Further, it is supported by a rotary joint 52. A pair of horizontal pipes 55, 55 extending in the horizontal direction are connected to the rotating body 53, and spray nozzles 56, 56 are attached to the bent end portions 55a, 55a at the ends of the horizontal pipes.

  As shown in FIG. 4, since the bent end 55a is oriented in a direction inclined by an angle θ with respect to the vertically downward direction, the injection port 57 of the spray nozzle 56 is also inclined by the angle θ. It faces the upper surface of the screen 2. Due to the inclined arrangement of the spray nozzle 56, the spray nozzle 56 (with the rotating body 53 and the horizontal pipes 55, 55) is caused by the reaction force F of the spray (specifically, the horizontal component force Fx) when the cleaning water is sprayed as described later. It will rotate around the central axis 54. The above inclination angle θ may be selected within a range of, for example, 10 to 30 degrees according to the injection flow rate of the cleaning water, and in this example, θ = 20 degrees.

Further, as shown in FIG. 1, the water supply pipe 51 via an on-off valve V _10, and is connected to a pressurized water supply side of the service water feed device 27 described above. Reference numeral 60 denotes a cleaning control device, and cleaning of the screen 2 is performed as follows under the control.

That is, the filtration of the raw water by the filtration tank 1 and the regeneration of the filter medium 3 by the filter medium regenerating apparatus 30 are carried out by controlling the respective parts such as the above-described pumps and on-off valves by a control apparatus (not shown) for controlling the entire filtering apparatus. During the operation of the filtration device, as shown in FIG. 5, the cleaning control device 60 first instructs the raw water pump P ₁ to stop when a time interval T ₁ (for example, 7 days) preset by a built-in timer has elapsed. the emitted, subsequently with emitting opening command the opening and closing valve V _8, V ₉ thereto and a position and a discharge amount of the pump P ₂ of the water level Lh of the raw water detected by the level gauge 45, the operation of the pump P ₂ The time T ₂ required to lower the raw water level in the filtration tank 1 to a predetermined level Ld position below the screen 2 is calculated, and the pump P _{2 is connected} to the time T by the built-in timer for adjusting the water level. Let run for _two . As a result, a predetermined amount of treated water in the filtration tank 1 flows out to the sedimentation basin through the discharge pipe 41, a part of the drain pipe 33, and the mud pipe 36 as shown by the thick arrows in FIG. As shown in FIG. 3, the water level is lowered to the level Ld position.

Therefore, after closing the on-off valves V ₈ and V ₉ , the on-off valve V ₁₀ is opened for a predetermined time T ₃ by another timer for setting the washing time incorporated in the washing control device 60. As a result, the cleaning water supplied from the miscellaneous water supply device 27 is supplied to the cleaning device 50 through the water supply pipe 51 as shown by the bold arrows, and sprayed from the spray ports 57 of the spray nozzles 56 onto the upper surface of the screen 2. In addition, the spray nozzle 56 rotates around the central axis 54 together with the rotating body 53 (and the horizontal tube 55) by the reaction force of the cleaning water jet.

  As a result, the cleaning water is uniformly sprayed on the upper surface of the screen 2, and as shown in FIG. 2, the sprayed water W causes deposits such as suspended matter or biofilm attached to the wedge wire 5. S is separated and removed downward, and the screen 2 is cleaned. At this time, since the water level of the raw water is at a lower position apart from the screen 2 together with the filter medium 3, the deposit S can be reliably and easily separated from the wedge wire 5 by spraying the cleaning water. It can be cleaned efficiently.

After the washing water is sprayed for a predetermined time T ₃ (for example, 15 minutes), the on-off valve V ₁₀ is closed to complete the washing cycle by the sequence control, so that the filtration device returns to the normal operation state. You can do it. The above washing cycle, the washing controller 60 is automatically repeated every time interval T ₁ of the above, clogging over a wide range of the screen 2 is prevented, it is to the filtration device can operate without hindrance.

  Further, in this example, the spray nozzle 56 in the cleaning device 50 is configured to self-rotate by the reaction force of the cleaning water jet from the spray nozzle, so that the device can be simple and low-cost, and can be driven by rotation. Therefore, it has the advantage that it is economical without the cost of power.

The present invention is not limited to the above example. For example, the rotating body 53 of the cleaning device 50 may be driven to rotate by a rotary driving machine such as a motor, and the central axis 54 of the rotating body 53 is a screen. It may be provided at a position eccentric from the center of 2 or inclined with respect to the vertical direction. Further, instead of the ultrasonic level meter 45 described above, a detection unit underwater immersion type level meter may be used to directly detect that the water level of the raw water has reached the level Ld. control by the time T ₂ is not required.

  In the above example, the case where the rotary cleaning device 50 that rotates the spray nozzle 56 around the central axis 54 is used has been described. However, the fixed cleaning device in which the spray nozzle is fixedly disposed at an upper position of the screen 2. May be used. As an example in this case, a large number (for example, six) of the horizontal pipes 55 in the above example are arranged radially in a plane, and the bases thereof are connected to the upward bent ends of the water supply pipes 51 via joint members. Examples of the cleaning device include a fixed connection, a spray nozzle 56 attached to a vertically downward bent end portion 55a of each horizontal pipe 55, and spraying cleaning water over a wide range on the upper surface of the screen 2.

  Further, instead of the natural sedimentation type filter medium storage / separation tank 31 of the above example, a cyclone type filter medium storage / separation tank that performs centrifugal separation is used, or the extraction of the filter medium from these separation tanks is made downward through the top of the screen. Specific configuration of each part of the filter medium regeneration device, the filtration tank, and other moving bed type filtration devices, such as a type that is performed through a drawing tube that opens in a tube, or an electrolytic sterilization device is used instead of the ultraviolet sterilization device 24 Or other than the above.

  Further, as the cleaning water for the screen cleaning, if the pressurized water of the pressurized water supply device for other uses is used like the miscellaneous water supply device 27 in the above example, a dedicated pump for supplying the cleaning water and its operating cost are unnecessary. In this case, the cleaning water can be procured at low cost. Instead, a water supply device such as the above-described dedicated pump may be provided.

1 is an overall system diagram of a moving bed filtration apparatus showing an example of an embodiment of the present invention. It is a principal part expanded sectional view of the screen in FIG. It is an upper part enlarged vertical sectional view of the filtration tank in FIG. It is an AA side view (enlarged) view of the bent end portion of the horizontal pipe in FIG. It is a time chart which shows the control content by the washing | cleaning control apparatus in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Filtration tank, 2 ... Screen, 3 ... Filter medium, 4 ... Filter medium layer, 11 ... Raw water inflow pipe, 15 ... Air diffusion pipe, 21 ... Water collecting pipe, 27 ... Miscellaneous water supply apparatus, 30 ... Filter medium reproduction | regeneration apparatus, 33 ... Drainage Pipe 36, Mud pipe, 40 ... Water level adjusting device, 41 ... Discharge pipe, 45 ... Level meter, 50 ... Cleaning device, 51 ... Water supply pipe, 52 ... Rotary joint, 53 ... Rotating body, 54 ... Center axis, 55 ... horizontal pipe, 56 ... spray nozzle, 57 ... injection opening 60 ... washing control device, P 1 _... raw water pump, P 2 _... pump, V 8 _... off valve, V 9 _... off valve, V _{10 ...} off valve.

Claims (3)

A screen with a chevron section with the center at the top is arranged in the filtration tank to form a filter medium layer floating below it, and the raw water supplied by the raw water pump is passed through the filter medium layer from above to filter it. Then, the treated water is taken out of the filtration tank, and after purifying the filter medium by pulling it out from the upper part of the filter medium layer, the filter medium is returned to the lower part of the filter tank, and air is supplied to the filter medium layer. In the moving bed type filtration device with a diffuser,
A water level adjusting device for adjusting the level of the raw water in the filtration tank to a predetermined level position below the screen;
A cleaning device in which a spray nozzle is disposed at an upper position of the screen with an injection port facing the upper surface of the screen, and cleaning water supplied by a water supply device is sprayed from the spray nozzle onto the upper surface of the screen;
The raw water pump is stopped by sequence control, the water level is adjusted by the water level adjusting device, and the cleaning water is sprayed onto the upper surface of the screen for a predetermined time in this order to constitute a cleaning cycle. A cleaning control device that repeats this cleaning cycle at time intervals set by a timer,
A moving bed type filtration apparatus characterized by comprising.   The spray nozzle of the cleaning device is attached to a rotating body supported rotatably around a central axis, and sprays the cleaning water from the spray nozzle that rotates around the central axis onto the upper surface of the screen. The moving bed type filtration apparatus according to claim 1, which is configured as described above.   3. The floor moving type according to claim 2, wherein the rotating body and the spray nozzle attached to the rotating body are rotationally driven around the central axis line by a reaction force of the spray of cleaning water from the spray nozzle. Filtration device.

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