JP2013144278A - Moving bed type sand filtration apparatus and method of operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving bed type sand filtration apparatus which allows power saving and reduction of the amount of cleaning drain while carrying out appropriate cleaning of filter sand, and its operating method.SOLUTION: The moving bed type sand filtration apparatus 1 filtrates raw water by causing raw water to flow upward in a filtration layer 3 formed by filling a filtration vessel 2 with filter sand as a filter medium, cleans the filter sand used in the filtration treatment while raising the filter sand with air-lift air from an air-lift pump 10 and discharges the water raised, together with the filter sand, by the air-lift air through a cleaning drain cutoff valve 24 as cleaning drain. The apparatus 1 includes a pressure type water gauge 21 detecting the pressure of raw water at the inflow inlet 4 to the filtration layer 3 and a controller 22 which operates the air-lift pump 10 and opens the cleaning drain cutoff valve 24 when the pressure or water level detected by the pressure type water gauge 21 exceeds a predetermined value.

Description

  The present invention relates to a sand transfer type sand filtration device suitably used for water treatment of sewage / clean water, general waste water and the like, and an operation method thereof.

An example of this type of moving sand filter is shown in FIG. 4 (see Patent Document 1).
The moving bed type sand filtration device 51 shown in FIG. 4 includes a filtration layer 53 formed by filling a filtration tank 52 with filtration sand as a filter medium, and as treated water containing suspended solids (SS). The raw water is flowed upward through the filtration layer 53 to filter the raw water.

In the moving bed type sand filtration device 51, when the raw water is flowing into the filtration layer 53, the air lift pump 54 is continuously operated, so that the filtered sand subjected to the filtration treatment is converted into air lift air. Washing while raising, separating the filtration sand and SS by the separator 55, and draining SS outside the apparatus as washing waste water, while returning the filtration sand to the surface of the filtration layer 53 again. Has been.
That is, the filtration layer 53 is constantly flowed and circulated by the air lift pump 54 using air lift air, and the washing waste water is always discharged out of the apparatus. Here, the air lift air of the air lift pump 54 is normally supplied by the compressor 56.

  In addition, the same operation as the above-described filtration device 51 is also performed for a multi-module type filtration device having a configuration in which a plurality of filtration tanks are combined (see Patent Document 2).

JP 2003-251109 A JP-A-8-103604

By the way, in the conventional moving bed type sand filtration apparatus 51, when the raw water is flowing into the filtration layer 53, by continuously operating the air lift pump 54, the filtration layer 53 is constantly flowed and circulated. Continuous operation is performed in which the washing waste water is always discharged out of the apparatus.
For this reason, there are problems that the power cost increases and the amount of washing waste water increases.
In addition, it is considered that the above problem can be solved by performing intermittent operation in which the air lift pump 54 is repeatedly operated and stopped while the raw water containing SS is passed through the filtration layer 53. If only the intermittent operation is performed, the filtration sand subjected to the filtration treatment is not properly washed, and the SS and the filtration sand may be fixed.

  The present invention has been made in view of the problems as described above, and is capable of saving power and reducing the amount of washing waste water while properly washing the sand, and its operation. It is intended to provide a method.

In order to achieve the above object, the sand transfer type sand filtration apparatus according to the first invention comprises:
The raw water is filtered by flowing the raw water upward through a filtration layer formed by filling the filtration tank with filter sand as a filter medium. It is a moving bed sand filtration device that is configured to wash while being raised, and to discharge water that is raised with the filter sand by the air lift air through the washing drainage shutoff valve as washing wastewater,
Pressure detecting means for detecting the pressure of the inflow portion into the filtration layer of the raw water;
Control means for operating the air lift pump and opening the cleaning drainage shut-off valve when the pressure detected by the pressure detection means exceeds a predetermined value;
It is characterized by providing.

  In the first invention, the control means activates the air lift pump and opens the cleaning drainage shutoff valve when the pressure detected by the pressure detection means exceeds a predetermined time in a state where the pressure is less than a predetermined value. Is preferable (second invention).

Next, the operation method of the sand transfer type sand filtration device according to the third invention is as follows:
The raw water is filtered by flowing the raw water upward through a filtration layer formed by filling the filtration tank with filter sand as a filter medium. The operation method of the moving bed sand filtration apparatus configured to wash while being raised, and to discharge water that is raised together with the filtration sand by the air lift air as washing wastewater through a washing drainage shutoff valve,
When the pressure of the inflow portion to the filtration layer of the raw water becomes a predetermined value or more, the air lift pump is operated and the washing drainage shutoff valve is opened.

  In 3rd invention, when the pressure of the inflow part to the said filtration layer of raw | natural water exceeds a predetermined time in the state of less than predetermined value, while operating the said air lift pump, it is preferable to open the said washing | cleaning waste_water | drain cutoff valve. (4th invention).

In the present invention, the pressure of the inflow portion into the raw water filtration layer (hereinafter, this pressure is referred to as “raw water inflow portion pressure”) is detected. This raw water inflow pressure increases as the raw water continues to flow into the filtration layer and the amount of SS deposited increases.
According to the present invention, when the raw water inflow portion pressure becomes equal to or higher than a predetermined value, the air lift pump is operated and the cleaning drainage shutoff valve is opened. On the other hand, when the raw water inflow portion pressure becomes less than a predetermined value, the operation of the air lift pump is stopped and the washing drainage shutoff valve is closed. Since such intermittent operation is carried out, it is possible to save power and reduce the amount of washing waste water while properly washing the filter sand.

For example, when the SS concentration of the raw water is low, the increase in the pressure of the raw water inflow portion is delayed, and the filtration sand is not washed for a long time, and the SS and the filtration sand may be fixed.
Therefore, by adopting a configuration in which the air lift pump is activated and the washing drainage shutoff valve is opened when the raw water inflow portion pressure is less than a predetermined value and exceeds a predetermined time, the sand filter is filtered at regular intervals. Since the cleaning is reliably performed, it is possible to prevent the SS and the filtration sand from sticking.

Structural explanatory drawing which represented typically the moving-bed-type sand filtration apparatus which concerns on the 1st Embodiment of this invention. Graph (a) showing the relationship between the differential pressure (water level), the operation / stop of the air lift pump, and the opening / closing of the flush drainage shutoff valve, and the timing of the operation / stop of the airlift pump and the opening / closing of the flush drainage shutoff valve by the timer control circuit Graph (b) Structural explanatory drawing which represented typically the moving-bed-type sand filtration apparatus which concerns on the 2nd Embodiment of this invention. Structural explanatory diagram schematically showing a conventional sand transfer device

  Next, specific embodiments of the sand transfer type sand filtration apparatus and the operation method thereof according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a structural explanatory view schematically showing a moving sand filter according to the first embodiment of the present invention.

<Overview of the moving sand filter>
A moving bed type sand filtration apparatus 1 shown in FIG. 1 is formed by filling a filtration tank 2 composed of a cylindrical body 2a and an inverted cone bottom 2b, and filtration sand as a filter medium into the filtration tank 2. The filtration layer 3 is provided.

<Description of raw water inflow section>
In the lower part of the filtration tank 2, a raw water inflow portion 4 is provided for allowing raw water as treated water containing suspended solids (SS) to flow into the filtration layer 3. The raw water inflow section 4 is provided with a raw water dispersion plate 5 made of an aggregate of single or plural dispersion plates having a triangular or pentagonal cross section and having an open lower surface side. The raw water inflow pipe 7 is connected via the pipe 6, and the raw water is supplied from the raw water inflow pipe 7 to the raw water dispersion plate 5 via the guide pipe 6. And raw | natural water is flowed out from the lower side of the raw | natural water dispersion | distribution board 5, is filtered by the filtration layer 3 while flowing to the upper part of the filtration layer 3, The filtered water to which this filtration process was performed is provided in the upper part of the filtration tank 2. The collected water is collected in the water collecting trough 8 and sent from the filtered water outflow pipe 9 to the next processing apparatus (not shown).

<Description of air lift pump>
The filter tank 2 is equipped with an air lift pump 10. The air lift pump 10 includes an air lift pipe 12 inserted from the upper part to the lower part of the filtration tank 2 in an internal device outer cylinder 11 disposed in the center of the filtration tank 2, and a pressure as a supply source of air lift air. An open / close air compressor (hereinafter simply referred to as “compressor”) 13 is provided.

  An air supply pipe 14 for supplying air lift air from the compressor 13 is connected to the lower end of the air lift pipe 12. The air supply pipe 14 is provided with an air valve 15 that opens and closes the pipe line and adjusts the flow rate of air lift air flowing through the pipe line. By opening the air valve 15, air lift air is blown into the air lift pipe 12 from the compressor 13 through the air supply pipe 14, and the filtered sand subjected to the filtration process is raised together with water in the air lift pipe 12. It can be washed with stirring.

<Description of cleaning drain pipe and cleaning drain shutoff valve>
Air lift air, filtered sand and water that have risen in the air lift pipe 12 are separated by a separator 16. The filtered sand separated by the separator 16 is washed by the sand washer 17 in a counterflow with filtered water and returned to the filtration layer 3 again. The water separated by the separator 16 contains a large amount of SS, and is discharged from the cleaning drain pipe 19 through the cleaning drain pipe 19 through the hole of the orifice plate 18 to the outside as cleaning drainage.

<Description of pressure detection means>
A water level gauge tube 20 is connected to the raw water dispersion plate 5, and a pressure type water level gauge (or a contact-attached water level gauge) 21 is attached to the upper end portion of the water level gauge tube 20. Here, as the water level gauge tube 20, the air vent pipe of the raw water dispersion plate 5 may be diverted. The pressure type water level gauge 21 measures the height of the liquid level in the water level gauge pipe 20 by detecting the pressure of the raw water inflow portion 4, and corresponds to the “pressure detection means” of the present invention. is there. It is assumed that the pressure water level gauge 21 has an alarm contact.

The mounting height L of the pressure type water level meter 21 is set to be equal to or higher than the water level height corresponding to the total filtration differential pressure ΔP from the filtered water surface WL. Here, the total filtration differential pressure ΔP is the sum of the normal filtration layer differential pressure ΔP ₁ and the differential pressure ΔP ₂ due to SS deposits in the raw water, and is applied to the filtration layer 3 from the raw water inflow portion 4 of the raw water. As the inflow continues and the amount of SS deposited increases, it increases. That is, the pressure in the water level gauge tube 20 and the water level are in a unique relationship, and the pressure and the water level in the water level gauge tube 20 both increase as the amount of accumulated SS increases.

<Description of control means>
The air valve 15 and the cleaning / drainage cutoff valve 24 are provided with a controller 22 for controlling the opening / closing operation of the valves. A measurement signal from the pressure type water level gauge 21 is given to the controller 22. Further, a timer control circuit 23 is incorporated in the controller 22.
This controller 22 opens the air valve 15 to open the air lift when the pressure or water level detected by the pressure type water level gauge 21 exceeds a predetermined value or when the timer set time Ts by the timer control circuit 23 is exceeded. The pump 10 is operated or the cleaning / drainage cutoff valve 24 is opened, and corresponds to the “control means” of the present invention.

<Description of effects>
In the moving bed type sand filtration device 1 configured as described above, the operation of the air lift pump 10 is sufficiently operated to flow and circulate the filtration layer 3 to drain the washing wastewater outside the device. After confirming this, the air valve 15 is closed by transmission of a valve closing operation signal from the controller 22 to stop the operation of the air lift pump 10, thereby stopping the flow and circulation of the filtration layer 3.
When a load and load type compressor is used as the compressor 13, it is preferable that the compressor 13 is stopped after a predetermined time has elapsed after the air valve 15 is closed. Thereby, abnormal heating of the electric motor which is a drive source of the compressor 13 can be prevented.

  The raw water is supplied from the raw water inflow pipe 7 to the raw water dispersion plate 5 through the guide pipe 6. The raw water supplied to the raw water dispersion plate 5 flows out from the lower side of the raw water dispersion plate 5 and is dispersed in the filtration layer 3. The raw water dispersed in the filtration layer 3 is taken upward into the filtration layer 3 and is filtered by the filtration layer 3 while flowing to the upper part of the filtration layer 3.

  In the state where the air lift pump 10 is continuously operated, the SS in the raw water moves toward the lower end of the air lift pipe 12 together with the filtered sand by the flow and circulation of the filtration layer 3. In the stopped state, since the flow and circulation of the filtration layer 3 are stopped, SS in the raw water accumulates in the periphery of the raw water dispersion plate 5 and in the gap between the filtration sands in the upper part.

As the inflow of raw water into the filtration layer 3 continues and the amount of SS deposited increases, the total filtration differential pressure ΔP (normal filtration layer differential pressure ΔP ₁ + differential pressure ΔP ₂ due to SS deposits in the raw water) increases. That is, the pressure and water level in the water level gauge tube 20 are both increased (FIGS. 2 (a) medium time _{t 0 ~t 1, t 2 ~t} 3, t 4 ~t 5).

Here, if the measured value based on the measurement signal from the pressure type water level gauge 21 is equal to or higher than the alarm setting level ΔP ′ (time t ₁ , t ₃ , t _{5 in} FIG. 2A), the controller 22 sends the air valve 15. In addition, a valve opening operation signal is transmitted toward the washing drainage shutoff valve 24, the air valve 15 is opened and the air lift pump 10 is actuated to start the flow and circulation of the filtration layer 3, and the washing drainage shutoff valve 24. Is opened, and the discharge operation of the cleaning waste water from the cleaning drain pipe 19 is started (time t _{1 to} t ₂ , t ₃ to t ₄ , t ₅ to in FIG. 2A).
When a load and load type compressor is used as the compressor 13, it is preferable to start the compressor 13 first and then open the air valve 15.

At times t _{1 to} t ₂ , t ₃ to t ₄ , and t ₅ to in FIG. 2A, the cleaning waste water is discharged from the cleaning drain pipe 19 to the outside of the apparatus, but at times t _{0 to} t in FIG. _{In 1} , t _{2 to} t ₃ , and t _{4 to} t ₅ , the cleaning drainage shutoff valve 24 is closed and the discharge of the cleaning drainage to the outside of the apparatus is stopped.

If the measured value based on the measurement signal from the pressure type water level gauge 21 becomes the alarm setting level ΔP ₁ during the operation of the air lift pump 10 (time t ₂ , t _{4 in} FIG. 2A), the air valve from the controller 22 15 and the washing drainage shut-off valve 24 are respectively transmitted, and the air valve 15 is closed to stop the operation of the air lift pump 10, thereby stopping the flow and circulation of the filtration layer 3 and washing drainage. The shut-off valve 24 is closed to stop the discharge of the cleaning waste water from the cleaning drain pipe 19 to the outside of the apparatus.

Thus, based on the measurement signal from the pressure-type water level gauge 21, the intermittent operation in which the operation and stop of the air lift pump 10 and the opening and closing of the flush drainage shutoff valve 24 are repeated is performed, so that the sand is properly washed. However, it is possible to save power and reduce the amount of washing waste water.
In addition, since it is necessary to stop in a state where SS in the filtration layer 3 is exhausted as much as possible, it is necessary to perform continuous washing in advance when stopping the sand transfer type sand filtration device 1 for a long period of time (stopping inflow of raw water). It is preferable to carry out continuous washing for at least one day or more.

  By the way, when the SS concentration of the raw water is low, the increase of the total filtration differential pressure ΔP is delayed, and the flow / circulation of the filtration layer 3 is stopped for a long time. However, stopping the flow / circulation of the filtration layer 3 for a long time may lead to the occurrence of a problem that the SS and the filtration sand adhere to each other. Therefore, in order to prevent such a problem, the filtration layer 3 is removed at regular intervals. Need to flow and circulate.

Therefore, when the measured value based on the measurement signal from the pressure type water level gauge 21 does not reach the alarm setting level ΔP ′ but exceeds the timer setting time Ts (from time t ₆ in FIG. 2B), the controller 22. The valve opening operation signal is transmitted to the air valve 15 and the cleaning / drainage shutoff valve 24 from each of the air valve 15 and the air lift pump 10 is operated by opening the air valve 15 to start the flow / circulation of the filtration layer 3 and cleaning. The drainage shut-off valve 24 is opened to start the cleaning drainage operation from the cleaning drainpipe 19. Thereby, since washing | cleaning of filtration sand is reliably performed for every fixed time (timer setting time Ts), adhesion of SS and filtration sand can be prevented beforehand.
When the measured value by the pressure type water level gauge 21 returns to ΔP ₁ (time t ₇ in FIG. 2B), a valve closing operation signal is sent from the controller 22 to the air valve 15 and the washing drainage shutoff valve 24. The transmission and the circulation of the filtration layer 3 are stopped by closing the air valve 15 and stopping the operation of the air lift pump 10, and the cleaning drainage shutoff valve 24 is closed and the cleaning drainage pipe 19 is connected to the outside of the apparatus. The discharge of the washing waste water is stopped, the timer set time Ts by the timer control circuit 23 is reset, and the counting is started again.

[Second Embodiment]
FIG. 3 is a structural explanatory view schematically showing a sand transfer type sand filtration apparatus according to the second embodiment of the present invention.
1 A of moving bed type sand filtration apparatuses of this embodiment are provided with two or more things equivalent to the filtration tank 2 in the moving bed type sand filtration apparatus 1 of 1st Embodiment, The multimodule of the structure which put together these filtration tanks 2 Of the type. Therefore, in the present embodiment, the same or similar parts as those in the first embodiment will be denoted by the same reference numerals in the drawings, and detailed description thereof will be omitted. Hereinafter, the first embodiment differs from the first embodiment. The explanation will focus on points.

In the moving bed type sand filtration apparatus 1A of the present embodiment, a plurality of (two in this example) equivalent to the filtration tank 2 in the moving bed type sand filtration apparatus 1 of the first embodiment are arranged and each filtration is performed. A wall between the tanks 2 is removed, and a concrete tank 30 surrounding all the filtration tanks 2 is provided as an outer wall of the filtration layer 3.
A pressure adjusting tank 31 is attached to the upper part of the concrete tank 30, and a raw water inflow channel 32 is provided adjacent to the pressure adjusting tank 31.
The raw water is poured into the pressure adjusting tank 31 from the raw water inflow channel 32 and is supplied from the pressure adjusting tank 31 to the lower part of the filtration layer 3 through the raw water inflow pipe 7, the guide pipe 6 and the raw water dispersing plate 5. ing. The filtered water that has been filtered by the filtration layer 3 overflows from the top of the concrete tank 30 and is sent from the outflow water channel 33 to the next processing device (not shown).
Further, the cleaning waste water is discharged from the cleaning drain pipe 19.

In the floor moving sand filtration apparatus 1A of the present embodiment, a pressure-type water level meter (or a contact-attached water level meter) 21 is installed in a pressure regulating tank 31 into which raw water flows from a raw water inflow channel 32.
As in the first embodiment, the pressure-type water level gauge 21 is provided with an alarm contact, and the mounting height L of the pressure-type water level gauge 21 is the water level height corresponding to the total filtration differential pressure ΔP from the filtered water level WL. More than minutes.

  In the multi-module type moving bed sand filtration apparatus 1A configured as described above, the same operation method as that of the moving bed sand filtration apparatus 1 of the first embodiment is implemented. That is, based on the measurement signal from the pressure-type water level gauge 21, when the intermittent operation in which the operation and stop of the air lift pump 10 and the opening and closing of the cleaning drainage shutoff valve 24 are repeated is performed and the timer set time Ts is exceeded, While the air lift pump 10 is operated, the cleaning drainage shutoff valve 24 is opened. Therefore, the same effect as the first embodiment can be obtained.

  As mentioned above, although the moving-bed-type sand filtration apparatus of this invention and its operating method were demonstrated based on several embodiment, this invention is not limited to the structure described in the said embodiment, In each embodiment. The configurations can be appropriately changed within a range not departing from the gist, such as appropriately combining the configurations described.

  The moving bed sand filtration apparatus and the operation method thereof according to the present invention have the characteristics that power can be saved and the amount of washing wastewater can be reduced while properly washing the filtration sand. It can be suitably used for water treatment applications such as clean water and general waste water.

DESCRIPTION OF SYMBOLS 1,1A Transfer bed type sand filter 2 Filtration tank 3 Filtration layer 4 Raw water inflow part 10 Air lift pump 12 Air lift pipe 13 Pressure open / close air compressor 15 Air valve 19 Washing drain pipe 20 Water level pipe 21 Pressure type water level gauge (Pressure detection) means)
22 Controller (control means)
23 Timer control circuit 24 Washing drain cutoff valve 31 Pressure control tank

Claims (4)

The raw water is filtered by flowing the raw water upward through a filtration layer formed by filling the filtration tank with filter sand as a filter medium. It is a moving bed sand filtration device that is configured to wash while being raised, and to discharge water that is raised with the filter sand by the air lift air through the washing drainage shutoff valve as washing wastewater,
Pressure detecting means for detecting the pressure of the inflow portion into the filtration layer of the raw water;
Control means for operating the air lift pump and opening the cleaning drainage shut-off valve when the pressure detected by the pressure detection means exceeds a predetermined value;
A moving bed type sand filtration apparatus comprising:   2. The control unit according to claim 1, wherein when the pressure detected by the pressure detection unit exceeds a predetermined time in a state where the pressure is less than a predetermined value, the control unit operates the air lift pump and opens the cleaning drainage shutoff valve. Moving bed sand filtration equipment. The raw water is filtered by flowing the raw water upward through a filtration layer formed by filling the filtration tank with filter sand as a filter medium. The operation method of the moving bed sand filtration apparatus configured to wash while being raised, and to discharge water that is raised together with the filtration sand by the air lift air as washing wastewater through a washing drainage shutoff valve,
When the pressure of the inflow part to the said filtration layer of raw | natural water becomes more than predetermined value, while operating the said air lift pump, the said washing | cleaning waste_water | drain cutoff valve is opened, The moving bed type sand filtration apparatus characterized by the above-mentioned how to drive.   The moving bed according to claim 3, wherein when the pressure of the inflow portion into the filtration layer of the raw water is less than a predetermined value and exceeds a predetermined time, the air lift pump is operated and the washing drainage shutoff valve is opened. Of operating a sand filter.

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