JP2014018725A - Filtration system and washing method of filtration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filtration system and a method for washing the filtration system capable of backwashing a floating filter medium layer at an effective timing even when the inflow amount of raw water varies.SOLUTION: There is provided a filtration system which comprises: a first vertical hole 10 having a floating filter medium layer 12, a screen 11 for preventing the outflow of the floating filter medium layer 12, a raw water inflow port 13 and a backwash effluent discharge port 14 and a filtrate water storage part 15 provided on an upper side of the screen 11; a backwashing mechanism for backwashing the floating filter medium layer 12 in a downflow manner and a second vertical hole 20 into which raw water is flowed; a raw water supply passage 41 for supplying raw water; and a backwashing mechanism controller which does not allow the start of backwashing of the floating filter medium layer 12 using the backwashing mechanism when the inflow amount of raw water flowing into the vertical hole 20 per unit time exceeds a predetermined amount and allows the start of backwashing of the floating filter medium layer 12 using the backwashing mechanism when the inflow amount of raw water flowing into the vertical hole 20 per unit time is equal to or smaller than the predetermined amount.

Description

  The present invention relates to a filtration system and a cleaning method for the filtration system, and more particularly to a filtration system having a floating filter medium layer made of a floating filter medium and a cleaning method for a floating filter medium layer of the filtration system.

  Conventionally, as a filtration system that filters raw water such as sewage to obtain filtered water, it is placed above the floating filter media layer made of a large number of foamed filter media made of foamed polymer, and prevents the floating filter media from flowing out. There is known an upward flow filtration system comprising a screen, a raw water inlet and a backwash drainage outlet disposed below the floating filter material layer, and a filtrate storage part located above the screen. (For example, refer to Patent Document 1).

  Further, in recent years, by arranging the above-mentioned floating filter material layer, screen, raw water inlet, backwash drainage outlet and filtrate storage part in a vertical hole formed by excavating the ground etc., forming a filtration system, It has also been proposed that overflow water of a combined sewer can be treated on-site (in-situ) (see, for example, Patent Document 2).

  In the conventional filtration system using the floating filter medium, the raw water flowing in from the raw water inlet is passed upward through the floating filter medium layer, so that impurities (for example, garbage, foreign matters, etc.) and floating suspensions are suspended. Filtered water from which turbid substances have been removed is obtained. In addition, in the above conventional filtration system, the filtered water stored in the filtrate storage part is allowed to flow down naturally, so that contaminants and suspended suspended solids captured by the floating filter material layer are removed along with the continuation of filtration. The floating filter medium layer was backwashed (hereinafter sometimes referred to as “backwash”) in countercurrent.

  Here, conventionally, the backwashing of the floating filter medium layer is usually performed when, for example, the filtration resistance of the floating filter medium layer increases and the filtration differential pressure becomes a predetermined value or more. .

Japanese Patent No. 3853738 JP 2010-221197 A

  However, it is not always efficient to determine the timing of backwashing using only the value of the filtration differential pressure as an index and perform backwashing. Specifically, for example, when treating overflow water from a combined sewer that flows sewage and rainwater through the same pipe, the amount of raw water (overflow) flowing into the filtration system increases depending on the weather. When it fluctuates, if the timing of backwashing is determined using only the value of the filtration differential pressure as an index, there are cases where filtration and backwashing cannot be performed efficiently. That is, if the timing of backwashing is determined using only the value of the filtration differential pressure as an index without considering the magnitude of the inflow of raw water, the filtration is interrupted even when the inflow of raw water is large and should continue filtration. Efficient filtration and backwashing will be performed because backwashing will be carried out, or the amount of raw water inflow will be small and raw water will not always be filtered. I could not.

  Accordingly, an object of the present invention is to provide a filtration system and a filtration system washing method capable of backwashing a floating filter material layer at an effective timing even when the inflow of raw water fluctuates. And

  An object of the present invention is to advantageously solve the above-described problems, and the filtration system of the present invention includes a floating filter medium layer made of a floating filter medium, and an upper side of the floating filter medium layer. A first vertical hole including a screen for preventing outflow, a raw water inflow port and a backwash drainage port disposed below the floating filter material layer, and a filtrate storage part provided on the upper side of the screen; A backwashing mechanism for draining water in the first vertical hole from the backwash drainage outlet and backwashing the floating filter material layer in a downward flow; a second vertical hole into which raw water flows; and the second A raw water supply channel for supplying raw water from the vertical hole to the first vertical hole via the raw water inlet; and when an inflow amount of the raw water flowing into the second vertical hole per unit time exceeds a predetermined amount The backwashing of the floating filter media layer using the backwashing mechanism When the flow rate of the raw water flowing into the second vertical hole per unit time is not more than a predetermined amount, the start of the backwashing of the floating filter material layer using the backwashing mechanism is allowed. And a backwash mechanism controller. In this way, if a backwash mechanism controller that controls the start of backwashing using the backwashing mechanism based on the inflow amount of raw water is provided, backwashing is permitted only when the inflow amount of raw water is small. Filtration can be continued without allowing the start of backwashing when there is a large amount of inflow. Therefore, avoid backwashing at an inefficient timing when the inflow of raw water is large, and ensure that backwashing is performed at a timing when the inflow of raw water is small, and wash the filtration system efficiently. be able to.

  In the filtration system according to the present invention, the backwashing mechanism controller reduces the backwashing when the inflow amount of raw water flowing into the second vertical hole per unit time decreases and the inflow amount reaches the predetermined amount. It is preferable to start the backwashing of the floating filter medium layer by operating the mechanism. If backwashing is started at the timing when the inflow of raw water decreases to a predetermined value, backwashing can be performed at an appropriate timing when the inflow of raw water flowing into the second vertical hole varies. This is because it can.

  The filtration system of the present invention further includes a water level meter that measures the water level in the second vertical hole, and a raw water pump that transfers the raw water into the first vertical hole via the raw water supply channel. The backwashing mechanism controller preferably grasps the amount of raw water flowing into the second vertical hole per unit time based on the measured value of the water level meter. When the raw water in the second vertical hole is transferred using the raw water pump, the water level in the second vertical hole varies depending on the inflow amount of the raw water. Therefore, if the water level gauge is used, the amount of raw water flowing into the second vertical hole can be easily grasped.

  Furthermore, the filtration system of the present invention includes a water level meter that measures the water level in the second vertical hole, a raw water pump that transfers the raw water into the first vertical hole via the raw water supply channel, and the water level. A raw water pump controller that activates the raw water pump when the measured water level exceeds a predetermined value, and stops the raw water pump when the water level is equal to or lower than the predetermined value; It is preferable to grasp the inflow amount of the raw water flowing into the second vertical hole per unit time based on the operation time or stop time of the raw water pump. When the raw water in the second vertical hole is transferred using the raw water pump, the water level in the second vertical hole varies depending on the inflow amount of the raw water. Therefore, when the raw water pump is started / stopped according to the water level of the raw water in the second vertical hole, the inflow amount of the raw water can be easily grasped based on the operation time or stop time of the pump. .

  Moreover, this invention aims at solving the said subject advantageously, and the washing | cleaning method of the filtration system of this invention is arrange | positioned above the floating filter material layer and the floating filter material layer which consists of a floating filter material. A first screen comprising a screen for preventing the floating filter material from flowing out, a raw water inlet and a backwash drainage port disposed below the floating filter material layer, and a filtrate storage unit provided on the screen. A back washing mechanism for discharging water in the first vertical hole from the back washing drain outlet and back washing the floating filter material layer in a downward flow; a second vertical hole into which raw water flows; A cleaning method for a filtration system having a raw water supply channel for supplying raw water from the second vertical hole to the first vertical hole via the raw water inlet, wherein raw water flowing from the raw water inlet is Passing water upward through the floating filter material layer Per unit time, including a filtration step of filtering raw water, and a backwashing step of discharging the water in the first vertical hole from the backwash drainage outlet and backwashing the floating filter material layer in a downward flow The backwashing step is performed only when the amount of raw water flowing into the second vertical hole is equal to or less than a predetermined amount. In this way, by performing the backwashing process only when the amount of raw water flowing into the second vertical hole per unit time is less than or equal to a predetermined amount, backwashing is allowed only when the amount of raw water inflow is small. And when there is much inflow of raw | natural water, filtration can be continued, without permitting the start of backwashing. Therefore, it is possible to avoid backwashing at an inefficient timing when the inflow amount is large, and to ensure that backwashing is performed at a timing at which the inflow amount of raw water is small, thereby efficiently washing the filtration system. it can.

  Further, the cleaning method of the filtration system of the present invention starts the backwashing process when the inflow amount of the raw water flowing into the second vertical hole per unit time decreases and the inflow amount becomes the predetermined amount. It is preferable. If backwashing is started at the timing when the inflow of raw water decreases to a predetermined value, backwashing can be performed at an appropriate timing when the inflow of raw water flowing into the second vertical hole varies. This is because it can.

  Furthermore, in the cleaning method for a filtration system according to the present invention, the filtration system further includes a raw water pump that transfers the raw water into the first vertical hole via the raw water supply flow path, Including a water level measurement step for measuring a water level, grasping an inflow amount of raw water flowing into the second vertical hole per unit time based on the water level measured in the water level measurement step, and performing the backwashing step preferable. When the raw water in the second vertical hole is transferred using the raw water pump, the water level in the second vertical hole varies depending on the inflow amount of the raw water. Therefore, if the water level measured in the water level measurement process is used, the amount of raw water flowing into the second vertical hole can be easily grasped.

  The filtration system cleaning method of the present invention further includes a raw water pump that transfers the raw water into the first vertical hole through the raw water supply flow path, and the filtration system includes When the water level in the vertical hole of 2 exceeds a predetermined value, the raw water pump is started, the raw water is transferred into the first vertical hole for filtration, and the water level in the second vertical hole is below a predetermined value. In this case, the raw water pump is stopped and the filtration is temporarily suspended until the water level in the second vertical hole exceeds a predetermined value, and the unit is based on the operation time or the stop time of the raw water pump in the filtration step. It is preferable that the amount of raw water flowing into the second vertical hole per hour is grasped and the backwashing step is performed. When the raw water in the second vertical hole is transferred using the raw water pump, the water level in the second vertical hole varies depending on the inflow amount of the raw water. Therefore, when starting / stopping the raw water pump according to the level of the raw water in the second vertical hole, it is possible to easily grasp the inflow amount of the raw water based on the operation time or stop time of the pump. .

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the inflow of raw | natural water is fluctuate | varied, the washing | cleaning method of the filtration system and filtration system which can backwash a floating filter material layer at an effective timing can be provided. .

It is explanatory drawing which shows an example of the installation position of the typical filtration system according to this invention. It is explanatory drawing explaining schematic structure of the typical filtration system according to this invention. It is explanatory drawing explaining schematic structure of the modification of the filtration system according to this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, what attached | subjected the same code | symbol in each figure shall show the same component.

  Here, the filtration system of the present invention is not particularly limited, and can be used for sewage treatment and the like. Specifically, as shown in FIG. 1 as an example of the installation position of the filtration system 100, the filtration system of the present invention is in the vicinity of the combined sewage pipe 111 in a combined sewer that allows rainwater and sewage to flow through the same pipeline. It is possible to use it when the overflow (nQ excess) that exceeds the planned interception amount nQ and cannot be treated at the sewage treatment plant is treated on-site. The “planned interception amount nQ” is the planned interception amount of the interception pipe designed according to the treatment capacity of the sewage treatment plant, where “n” is a numerical value that varies depending on the city. Further, “Q” is the maximum amount of sewage during fine weather hours.

  In the combined sewer system to which the filtration system 100 of the present invention shown in FIG. 1 is applied, when the amount of rainwater and sewage flowing into the combined sewer pipe 111 exceeds the planned interception amount, the overflow water (raw water) is It flows into the filtration system 100 through an overflow section (not shown) provided in the combined sewage pipe 111 and is processed. Here, the overflow section is desirably provided on the downstream side of the existing rainwater spout 112. However, if it is difficult to install the rainwater spout 112 on the downstream side, the rainwater spout 112 may be provided on the upstream side of the rainwater spout 112. Then, the overflow water (filtered water) that has been filtered by the filtration system 100 and improved in water quality is discharged into the river 114 and the like.

  Here, as shown in FIG. 2, the filtration system 100 of an example of the present invention includes a first vertical hole 10 as a filtration tank having the floating filter medium layer 12, a backwash mechanism for backwashing the floating filter medium layer 12, and A second vertical hole 20 as a raw water tank, a raw water supply passage 41 for supplying raw water from the second vertical hole 20 to the first vertical hole 10, and a third vertical hole 30 as a backwash drainage tank are provided. Yes. The filtration system 100 further includes a control device including a backwashing mechanism controller 51 that controls the timing of the start of backwashing using the backwashing mechanism based on the amount of raw water flowing into the second vertical hole 20. It is characterized by that. For this reason, in this filtration system 100, it can avoid performing backwashing when there is much inflow of raw | natural water, and can perform backwashing at the effective timing with little inflow of raw | natural water.

  In addition, the raw water flow path of the filtration system 100 is provided with a flow rate adjustment valve 115 as a raw water inflow blocking mechanism that blocks the inflow of raw water into the second vertical hole 20. In addition, a lid (not shown) that prevents a person or an object from falling into the vertical hole is disposed at the opening of the first vertical hole 10, the second vertical hole 20, and the third vertical hole 30 to the ground G. ing.

  The first vertical hole 10 functions as a filtration tank for filtering raw water to obtain filtered water. As the first vertical hole 10, for example, a structure such as a new manhole formed by excavating the ground G Can be used. As shown in FIG. 2, in the first vertical hole 10, the screen 11, the floating filter medium layer 12 made of a plurality of floating filter media supported by the screen 11, and the floating filter medium layer 12 are installed below. The raw water inlet 13, the plurality of backwash drainage outlets 14 installed below the floating filter material layer 12, the filtrate storage part 15 provided on the upper side of the screen 11, and the upper side of the screen 11. A filtered water outlet 16 is disposed. In the first vertical hole 10, a blower (not shown) for improving the flowability of the floating filter medium may be optionally disposed in the backflow cleaning of the floating filter medium layer 12.

  Here, the floating filter medium is a filter medium having a specific gravity smaller than that of the raw water (that is, floating in the raw water). And in the filtration system 100, known floating filter media, such as the particulate floating filter material made from a foaming polymer described in Patent Document 1 and Patent Document 2, can be used as the floating filter medium.

  Moreover, as the screen 11 arrange | positioned above the floating filter material layer 12, the screen which can prevent the outflow of a floating filter medium, for example, a punching metal etc. can be used. In addition, the floating filter medium layer 12 is provided with the first vertical hole 10 in which water is introduced to a predetermined height, and then a screen 11 is installed on the upper side of the input floating filter medium, thereby providing the first It can be provided in the vertical hole 10.

  The second vertical hole 20 functions as a raw water tank that stores the raw water filtered in the first vertical hole 10, and the second vertical hole 20 excavates the ground G in the same manner as the first vertical hole 10. It is possible to use a new manhole or other structure formed in this way. Further, the upper part of the second vertical hole 20 communicates with the merging sewage pipe 111 via a raw water flow path having a flow rate adjusting valve 115.

Furthermore, in the 2nd vertical hole 20, the raw | natural water pump 21 which transfers the raw | natural water in the 2nd vertical hole 20 in the 1st vertical hole 10 via the raw | natural water supply flow path 41, and the water level in the 2nd vertical hole 20 And a water level gauge 23 for measuring water.
Here, the suction port 22 of the raw water pump 21 is located in the second vertical hole 20. The discharge port of the raw water pump 21 is connected to the raw water supply channel 41, and the raw water supply channel 41 connects the discharge port of the raw water pump 21 and the raw water inlet 13 of the first vertical hole 10. . A known pump can be appropriately selected and used as the raw water pump.
The water level gauge 23 is connected to a backwash mechanism controller 51. The water level gauge 23 detects the measured water level and outputs a detection signal to the backwash mechanism controller 51. As the water level gauge 23, a known water level gauge can be appropriately selected and used.

  Here, the 2nd vertical hole 20 and the 1st vertical hole 10 are connected by the raw | natural water supply path 41. FIG. The raw water supply channel 41 supplies raw water from the second vertical hole 20 to the first vertical hole 10 through the raw water inlet 13 of the first vertical hole 10. The raw water supply path 41 has a raw water supply valve 42. The raw water supply valve 42 is connected to a control device (not shown) including a backwash mechanism controller 51, and the opening and closing of the raw water supply valve 42 can be controlled by the control device.

  The third vertical hole 30 functions as a backwash drainage tank that stores backwash drainage discharged from the backwash drainage outlet 14 of the first vertical hole 10 when the floating filter material layer 12 is backwashed. As the third vertical hole 30, similarly to the first vertical hole 10 and the second vertical hole 20, a structure such as a new manhole formed by excavating the ground G can be used.

  Here, in this filtration system 100, the lower part of the third vertical hole 30 is connected to the interception pipe 113 shown in FIG. 1 via a drain pipe (not shown), and the interception pipe 113 is used for the sewage treatment. It extends to the place. The drainage pipe may be connected to the merging sewage pipe 111 on the downstream side of the overflow section where the raw water (overflow water) overflows from the merging sewage pipe 111.

  Further, in the filtration system 100, a plurality of (six in FIG. 2) backwash drainage outlets 14 positioned below the first vertical hole 10 are water collection pipes 61 that discharge the backwash drainage from the first vertical hole 10. The water collecting pipe 61 extends to the lower part of the third vertical hole 30. That is, the water collection pipe 61 connects the backwash drainage outlet 14 and the third vertical hole 30. The water collection pipe 61 has a water collection pipe valve 62. The water collection pipe valve 62 is connected to the backwash mechanism controller 51, and the opening and closing of the water collection pipe valve 62 can be controlled by the backwash mechanism controller 51.

Here, the water collection pipe 61 and the water collection pipe valve 62 constitute a backwashing mechanism. The backwashing mechanism drains the water in the first vertical hole 10 from the backwashing drainage outlet 14 and backwashes the floating filter material layer 12 in a downward flow.
Specifically, in the filtration system 100 in which the first vertical hole 10 and the third vertical hole 30 are communicated with each other via the water collecting pipe 61, the water level in the third vertical hole 30 is the water level in the first vertical hole 10. If lower than that, the water in the first vertical hole 10 can be sent into the third vertical hole 30 via the water collection pipe 61 by using the water head difference by opening the water collection pipe valve 62. it can. And the water (backwash drainage) sent out in the 3rd vertical hole can be sent out to a interception pipe by natural flow, for example.

The backwashing mechanism controller 51 constitutes a part of a control device (not shown). The backwashing mechanism controller 51 is connected to the water level gauge 23 and the water collecting pipe valve 62, and the backwashing mechanism controller 51 uses a backwashing mechanism (the water collecting pipe 61 and the water collecting pipe valve 62). The start timing of the backwashing of the floating filter material layer 12 is controlled. That is, in FIG. 2, the backwash mechanism controller 51 grasps the inflow amount of raw water flowing into the second vertical hole 20 per unit time based on the measured value of the water level gauge 23, and the grasped inflow amount of the raw water is When the amount exceeds the predetermined amount, the backwashing of the floating filter material layer 12 using the backwashing mechanism is not permitted to start (that is, the water collection piping valve 62 is kept closed). On the other hand, when the grasped inflow amount of the raw water is equal to or less than the predetermined amount, the start of the floating filter material layer using the backwashing mechanism is allowed (that is, the water collecting piping valve 62 is allowed to open).
Here, grasping | ascertaining of the inflow amount of raw | natural water using the water level gauge 23 can be performed as follows, for example. That is, in the filtration system 100, the amount of raw water inflow per unit time is Q [m ³ ], the amount of raw water discharged by the raw water pump 21 per unit time is q [m ³ ], and the bottom area of the second vertical hole 20 Is A [m ² ], and the water level in the second vertical hole 20 decreased per unit time is H [m], the formula:
Q = q + (A × H)
Is established. Therefore, the backwashing mechanism controller 51 uses the above formula to change the water level change amount H in the second vertical hole 20 measured by the water level gauge 23, the discharge amount q of the raw water pump 21, and the second vertical hole. From the bottom area A of 20, the inflow amount Q of the raw water flowing into the second vertical hole 20 can be grasped.
Since the bottom area A is a constant value, as is clear from the above formula, when the discharge amount q of the raw water pump 21 per unit time is constant, the inflow amount Q of the raw water is within the second vertical hole 20. It is a linear function with the amount of change in water level as a variable. Therefore, if the correlation between the amount of change in the water level and the amount of inflow is obtained in advance and stored in the backwash mechanism controller 51, the backwash mechanism controller 51 uses the correlation to determine only the amount of change in the water level. It is also possible to grasp the inflow of raw water.

Here, measurement of the flow rate in the channel installed in the ground, for example, measurement of the flow rate of the overflow water that has overflowed from the combined sewage pipe 111 to the raw water channel is generally difficult. In the filtration system 100, the amount of raw water flowing into the second vertical hole 20 can be easily grasped by using the water level gauge 23 in this way. Further, if the water level gauge 23 is installed in the second vertical hole 20, there is no need to bury the inflow measurement equipment in the ground, so the structure of the filtration system 100 is simplified and the installation cost is reduced. be able to.
In the example shown in FIG. 2, the water level gauge 23 is used. However, in the filtration system of the present invention, the amount of raw water flowing into the second vertical hole per unit time can be grasped. The following means may be used. For example, the inflow of raw water can be grasped using a cough type flow meter.

  And in this filtration system 100, as explained below, the overflow water (raw water) flowing into the second vertical hole 20 from the combined sewage pipe 111 is filtered by the floating filter material layer 12 of the first vertical hole 10, or The floating filter medium layer 12 in the first vertical hole 10 is backwashed. The timing of backwashing the floating filter material layer 12 is determined based on the amount of raw water flowing into the second vertical hole 20. And in the filtration system 100, the inflow amount of raw | natural water is grasped | ascertained based on the water level of the 2nd vertical hole 20 measured by the water level measurement process demonstrated in detail later.

<Filtration process>
In the filtration system 100, the control device opens the raw water supply valve 42, closes the water collection piping valve 62, operates the raw water pump 21, and enters the second vertical hole 20 from the combined sewage pipe 111 through the raw water flow path. The raw water that has flowed in is caused to flow from the raw water inlet 13 into the first vertical hole 10. And this raw | natural water is made to flow through the floating filter material layer 12 by flowing upward, and raw water is filtered. The obtained filtered water flows upward in the filtrate storage part 15 and then is discharged to a river or the like via the filtrate outlet 16.
In addition, when filtering raw water, if the raw water flows in the first vertical hole 10 in an upward flow, the water collecting piping valve 62 may be opened, but from the viewpoint of efficiently filtering the raw water, It is preferable to filter the raw water with the water collection piping valve 62 closed.
Here, at the time of raw water filtration, the flow rate of raw water sent from the second vertical hole 20 into the first vertical hole 10 through the raw water supply channel 41 and the raw water inlet 13 flows into the second vertical hole 20. When the flow rate of the raw water is larger than the flow rate of the raw water, that is, when the discharge amount of the raw water pump 21 is larger than the flow rate of the raw water, the water level LV in the second vertical hole 20 is two points from the position indicated by the solid line in FIG. It drops to the position indicated by the chain line.
Therefore, in the filtration system 100, in order to prevent the raw water pump 21 from idling due to a drop in the water level in the second vertical hole 20, the water level in the second vertical hole 20 is set at a predetermined position (for example, two in FIG. 2). When the pressure drops to the position indicated by the dotted line), the operation of the raw water pump 21 is stopped, the first piping valve 42 is closed, and the raw water filtration is stopped. When the raw water is stored again in the second vertical hole 20 and the water level in the second vertical hole 20 rises, the raw water supply pump 42 is opened, the operation of the raw water pump 21 is restarted, and the raw water is filtered again. .

<Water level measurement process>
Here, during the filtration step, the water level gauge 23 measures the water level in the second vertical hole 20 and outputs the measured water level to the backwash mechanism controller 51. As described above, the backwashing mechanism controller 51 grasps the amount of raw water flowing into the second vertical hole per unit time based on the signal output from the water level gauge 23. Note that the water level measurement step may be performed during the standby of the filtration system 100 during the implementation of the backwashing step, which will be described later, or when the filtration step and the backwashing step are not performed, other than during the filtration step. Good.

And in this filtration system 100, the backwashing process demonstrated below is implemented only when the inflow of raw | natural water is below predetermined amount.
That is, when the amount of raw water flowing into the second vertical hole 20 per unit time exceeds a predetermined amount, the backwashing mechanism controller 51 starts the backwashing of the floating filter material layer 12 using the backwashing mechanism. Do not allow, continue to perform the filtration process. On the other hand, when the inflow amount of the raw water flowing into the second vertical hole 20 per unit time is equal to or less than the predetermined amount, the filtration step is ended and the backwashing of the floating filter material layer 12 using the backwashing mechanism is started. .

  In addition, regarding the inflow amount of raw water, the “predetermined amount” allowing the start of the backwashing process can be determined experimentally.

<Backwash process>
In the filtration system 100, when the amount of raw water flowing into the second vertical hole 20 falls below a predetermined amount, the control device including the backwash mechanism controller 51 closes the raw water supply valve 42 and opens the water collection piping valve 62. Then, the operation of the raw water pump 21 is stopped. As a result, the water in the first vertical hole 10 is supplied to the third vertical hole 10 via the water collecting pipe 61 using the difference (water head difference) between the water level in the first vertical hole 10 and the water level in the third vertical hole 30. The filtered water stored in the filtered water storage unit 15 is passed through the floating filter material layer 12 in a downward flow, and a large number of floating filter media constituting the floating filter material layer 12 are moved downward. Expand. Then, the impurities and floating suspended substances captured in the floating filter medium layer 12 are discharged from the floating filter medium layer 12, and the floating filter medium layer 12 is back-washed. In addition, the water that has flowed from the first vertical hole 10 into the third vertical hole 30 (backwash drainage containing impurities and suspended suspended matter supplemented by the floating filter material layer 12) is allowed to flow down naturally. The material is sent from the third vertical hole 30 to the shielding tube 113.

In addition, when the water in the first vertical hole 10 is allowed to flow naturally into the third vertical hole 30, the water level in the third vertical hole 30 is the water level in the first vertical hole 10 when backwashing is started ( Usually, it is necessary to be lower than the position where the filtrate outlet 16 is provided. Therefore, in this filtration system 100, when the amount of raw water flowing into the second vertical hole 20 is less than or equal to a predetermined value and the water level in the third vertical hole 30 is less than or equal to the water level in the first vertical hole 10. It is preferable to control the opening and closing of the raw water supply valve 42 and the water collection piping valve 62 with a control device including the backwashing mechanism controller 51 so as to start the backwashing of the floating filter material layer 12. Specifically, the amount of raw water flowing into the second vertical hole 20 is equal to or less than a predetermined amount, and the water level in the third vertical hole 30 is located below the water level in the first vertical hole 10. In addition, the control device allows the raw water supply valve 42 to be closed and the water collection piping valve 62 to be opened.
Moreover, in this filtration system 100, the backwashing process may be started as soon as the inflow amount of the raw water flowing into the second vertical hole 20 is equal to or less than a predetermined amount. However, the backwashing process is started in the second vertical hole 20 during the backwashing process. In order to prevent the raw water from overflowing from the second vertical hole 20 even if the raw water flows in, the inflow amount of the raw water flowing into the second vertical hole 20 becomes a predetermined amount or less, and the second vertical hole 20 The backwashing process may be started when the water level of the raw water becomes equal to or lower than a predetermined value. That is, the control device including the backwashing mechanism controller 51 has a raw water supply valve when the inflow amount of raw water becomes a predetermined amount or less and the water level in the second vertical hole 20 becomes a predetermined value or less. 42 is closed, the water collection piping valve 62 is opened, and the operation of the raw water pump 21 is preferably stopped.

In this filtration system 100, the filtration process is terminated and the backwash process is started only when the inflow amount of the raw water flowing into the second vertical hole 20 becomes a predetermined amount or less. It is possible to avoid starting the backwash process when the amount of raw water flowing into the water is large. Moreover, it is possible to ensure that the backwashing process is started at a timing when the amount of inflow of raw water is small, and the filtration system 100 can be washed efficiently.
Moreover, when using a manhole as the 2nd vertical hole 20, the 2nd vertical hole 20 can be utilized in order to store raw | natural water temporarily. Therefore, the timing for performing backwashing can be controlled more efficiently.

In addition, from the viewpoint of starting the backwashing process at a more appropriate timing, the backwashing process is preferably started when the inflow amount of the raw water decreases and the inflow amount becomes a predetermined amount or less. Even if the inflow of raw water is less than the specified amount, if the backwash process is started at a timing when the inflow of raw water tends to increase, the filtration process will be delayed and the raw water will be filtered efficiently This is because there is a case that cannot be done.
Further, for example, when the backwashing is completed within 1 minute, the inflow amount is an inflow amount that does not fill the second vertical hole 20 during the 1 minute in which the backwashing is performed, and the second vertical hole It is more preferable to start backwashing at a timing when the water level of 20 decreases to a water level at which the raw water pump 21 should be stopped in order to prevent the raw water pump 21 from being idle (for example, a position indicated by a two-dot chain line in FIG. 2). .

  Here, in the filtration system 100 of the above example, the third vertical hole 30 is provided. However, when the shielding tube 113 is installed in a place deeper than the first vertical hole 10, the third vertical hole 30 is provided. In this case, the backwash drainage can be directly discharged from the backwash drain discharge port 14 to the interception pipe 113 via the water collection pipe 61.

  Moreover, in the filtration system 100 of the above-described example, the backwash drainage water is supplied from the third vertical hole 30 to the interception pipe 113 by utilizing the water head difference, for example, as shown in FIG. 3 described below. As in the filtration system 200, a drainage pump may be installed in the third vertical hole 30, and the backwash wastewater may be fed using the drainage pump.

A filtration system 200 shown in FIG. 3 is a modification of the filtration system according to the present invention.
The filtration system 200 shown in FIG.
-The point further including the drainage pump 31 installed in the 3rd vertical hole 30, and the raw | natural water pump controller 52 which controls operation | movement of the raw | natural water pump 21,
-The raw water pump controller 52 is connected to the water level gauge 23 and the raw water pump 21,
The backwashing mechanism controller 51 is further connected to the drainage pump 31, and
The configuration of the backwashing mechanism is different from that of the previous filtration system 100 in that the backwashing mechanism is constituted by the water collection pipe 61, the water collection pipe valve 62, and the drainage pump 31.

  In the filtration system 200, the raw water pump controller 52 controls the operation (operation / stop) of the raw water pump 21 based on the water level measured by the water level gauge 23. Specifically, the raw water pump controller 52 activates the raw water pump 21 when the water level in the second vertical hole 20 measured by the water level gauge 23 exceeds a predetermined value. On the other hand, the raw water pump controller 52 stops the operation of the raw water pump 21 when the water level in the second vertical hole 20 is a predetermined value or less.

  That is, when the flow rate of the raw water sent from the second vertical hole 20 into the first vertical hole 10 is larger than the flow rate of the raw water flowing into the second vertical hole 20, the water level LV in the second vertical hole 20. However, since it falls from the position shown by a solid line in FIG. 3 to the position shown by a two-dot chain line, the raw water pump controller 52 stops the operation of the raw water pump 21. Further, when the raw water flows into the second vertical hole 20 while the raw water pump 21 is stopped and the water level in the second vertical hole 20 is recovered, the raw water pump controller 52 activates the raw water pump 21.

  Furthermore, in this filtration system 200, the raw water pump controller 52 outputs the operation time of the raw water pump 21 to the backwash mechanism controller 51, and the backwash mechanism controller 51 performs unit time based on the operation time of the raw water pump 21. The amount of raw water flowing into the second vertical hole 20 is ascertained.

  The “operation time” of the raw water pump 21 refers to the time during which the raw water pump 21 is operating, that is, the time from when the raw water pump 21 is started until it stops.

Here, the difference between the water level at which the raw water pump controller 52 stops the operation of the raw water pump 21 and the water level at which the raw water pump controller 52 restarts the operation of the raw water pump 21 is h [m]. The time is t [min], the bottom area of the second vertical hole is A [m ² ], the amount of raw water flowing in during time t is Q ′ [m ³ ], and the discharge of the raw water pump 21 If the quantity is q ′ [m ³ / min], the formula:
Q ′ = (q ′ × t) + (A × h)
Is established.
Therefore, when the discharge amount of the raw water pump 21 is constant, the operation time of the raw water pump 21 is longer if the amount of raw water flowing into the second vertical hole 20 is large, and is short if the amount of inflow is small. . On the other hand, the stop time of the raw water pump 21 (the time until the raw water pump controller 52 stops the operation of the raw water pump 21 and restarts it, that is, the time until the water level in the second vertical hole 20 is recovered). If the flow rate of raw water flowing into the second vertical hole 20 is large, the flow rate is short. If the flow rate is small, the flow rate is long.

Therefore, the backwashing mechanism controller 51 uses the above equation to calculate the operation time t of the raw water pump 21, the discharge amount q ′ of the raw water pump 21, the bottom area A of the second vertical hole 20, and the water level difference h. Therefore, it is possible to grasp the inflow amount of the raw water flowing into the second vertical hole 20 per unit time, and to control the start of the backwashing of the floating filter material layer using the backwashing mechanism. That is, in FIG. 3, the backwash mechanism controller 51 grasps the amount of raw water flowing into the second vertical hole 20 per unit time based on the operation time of the raw water pump 21, and the grasped amount of raw water inflow is determined. When the amount exceeds the predetermined amount, the backwashing of the floating filter material layer 12 using the backwashing mechanism is not permitted to start (that is, the water collection piping valve 62 is kept closed). On the other hand, when the grasped inflow amount of the raw water is equal to or less than the predetermined amount, the start of the floating filter material layer using the backwashing mechanism is allowed (that is, the water collecting piping valve 62 is allowed to open).
In this way, by controlling the operation of the raw water pump 21 based on the water level measured by the water level gauge 23 and grasping the operation time of the raw water pump 21, the amount of raw water flowing into the second vertical hole 20 can be easily reduced. Can be measured.
The time during which the pump is stopped (stop time) t ′ [min], the bottom area A [m ² ] of the second vertical hole, and the water level at which the raw water pump controller 52 stops the operation of the raw water pump 21 Between the difference h [m] between the raw water pump controller 52 and the water level at which the operation of the raw water pump 21 is resumed, and the inflow amount Q ″ [m ³ / min] of raw water per unit time, the formula:
Q ″ × t ′ = A × h
Is established.
Therefore, in this filtration system 200, the backwashing mechanism controller 51 uses the backwashing mechanism by grasping the inflow amount of the raw water flowing into the second vertical hole 20 per unit time even if the above formula is used. The start of backwashing of the floating filter media layer can be controlled.

Further, in the filtration system 200, the drainage pump 31 is disposed below the third vertical hole 30. The drainage pump 31 is connected to the backwashing mechanism controller 51, and its operation is controlled by the backwashing mechanism controller 51. Here, in the filtration system 200, the suction port 32 of the drainage pump 31 is located in the third vertical hole 30. Moreover, the discharge port of the drainage pump 31 is connected to the interception pipe 113 shown in FIG. 1 through the drainage pipe, and the interception pipe 113 extends to the sewage treatment plant. The drainage pipe may be connected to the merged sewage pipe 111 on the downstream side of the overflow section where the raw water (overflow water) overflows from the merged sewage pipe 111. As the drainage pump 31, a known pump can be appropriately selected and used.
In FIG. 3, the drain pump 31 is connected to a backwash mechanism controller 51, and its operation / stop is controlled by the backwash mechanism controller 51. However, the drain pump 31 is operated / stopped manually. May be. Moreover, when the intercepting pipe exists in a part deeper than the third vertical hole, since the backwash waste water can be discharged by natural flow, the drain pump 31 can be omitted.

  And in this filtration system 200, as explained below, the overflow water (raw water) flowing into the second vertical hole 20 from the combined sewage pipe 111 is filtered by the floating filter material layer 12 of the first vertical hole 10, or The floating filter medium layer 12 in the first vertical hole 10 is backwashed. Also in the filtration system 200, as in the filtration system 100, the timing for backwashing the floating filter material layer 12 is determined based on the amount of raw water flowing into the second vertical hole 20. Here, in the filtration system 200, as described above, the inflow amount of the raw water is grasped based on the operation time of the raw water pump 21. And operation | movement of the raw | natural water pump 21 is controlled based on the water level of the 2nd vertical hole 20 measured by the water level measurement process demonstrated below.

<Filtration process>
In the filtration system 200, when the water level measured by the water level gauge 23 exceeds a predetermined value, the raw water pump controller 52 activates the raw water pump 21 to filter the raw water. In this case, the control device including the backwash mechanism controller 51 and the raw water pump controller 52 opens the raw water supply valve 42, closes the water collection piping valve 62, and operates the raw water pump 21 in this state, thereby joining The raw water that has flowed into the second vertical hole 20 from the sewage pipe 111 through the raw water flow path is sent to the lower part of the first vertical hole 10. And the raw | natural water is filtered by flowing the raw | natural water sent to the floating filter material layer 12 by an upward flow. The obtained filtered water flows upward in the filtrate storage part 15 and then is discharged to a river or the like via the filtrate outlet 16.

  Here, when the raw water is filtered, the raw water flow rate that flows from the second vertical hole 20 into the first vertical hole 10 through the raw water supply path 41 and the raw water inlet 13 flows into the second vertical hole 20. When the flow rate is larger than the flow rate of the raw water, that is, when the discharge amount of the raw water pump 21 is larger than the inflow amount of the raw water, the water level LV in the second vertical hole 20 is, for example, from the position indicated by the solid line in FIG. It drops to the position shown by. Therefore, when the water level measured by the water level gauge 23 drops below a predetermined value, the raw water pump controller 52 stops the raw water pump 21 and performs filtration until the water level in the second vertical hole 20 exceeds the predetermined value. Is temporarily interrupted to prevent the raw water pump 21 from idling. Then, when raw water is stored again in the second vertical hole 20 and the water level in the second vertical hole 20 rises, the raw water supply valve 42 is opened, the operation of the raw water pump 21 is resumed, and the raw water filtration is resumed. . The raw water supply valve 42 is closed while the raw water pump 21 is stopped.

  As with the filtration system 100, in the filtration system 200, if the raw water flows in the first vertical hole 10 in an upward flow, the raw water may be filtered with the water collection piping valve 62 opened. From the viewpoint of efficiently filtering the raw water, it is preferable to filter the raw water with the water collecting piping valve 62 closed.

<Water level measurement process>
Here, during the filtration process, the water level gauge 23 measures the water level in the second vertical hole 20 and outputs the measured water level to the raw water pump controller 52. The raw water pump controller 52 controls the operation / stop of the raw water pump 21 based on the signal output from the water level gauge 23 as described above.

And in this filtration system 200, the backwashing process demonstrated below is implemented only when the inflow of raw | natural water grasped | ascertained from the operation time of the raw | natural water pump 21 is below a predetermined amount.
That is, when the amount of raw water flowing into the second vertical hole 20 per unit time exceeds a predetermined amount, the backwashing mechanism controller 51 starts the backwashing of the floating filter material layer 12 using the backwashing mechanism. Do not allow, continue to perform the filtration process. On the other hand, when the inflow amount of the raw water flowing into the second vertical hole 20 per unit time is equal to or less than the predetermined amount, the filtration step is ended and the backwashing of the floating filter material layer 12 using the backwashing mechanism is started. .
In addition, the backwashing mechanism controller 51 can grasp | ascertain the inflow amount of raw | natural water from the operation time of the raw | natural water pump 21 as mentioned above.

  Here, the inflow amount of the raw water flowing into the second vertical hole 20 per unit time is determined based on the operation time of the raw water pump 21, but is not particularly limited, and is based on the stop time of the raw water pump 21. The inflow amount may be grasped. Moreover, you may grasp | ascertain the inflow of raw | natural water based on the known method which can measure an inflow directly or indirectly. For example, the inflow amount of the raw water may be grasped based on the rotational speed of the raw water pump 21 when the rotational speed of the raw water pump 21 can be adjusted. Further, when the raw water pump 21 performs a constant water level control, it may be grasped based on the inverter frequency of the raw water pump 21.

<Backwash process>
Moreover, in the filtration system 200, when the inflow amount of the raw water flowing into the second vertical hole 20 becomes a predetermined amount or less, the control device 50 including the backwash mechanism controller 51 stops the raw water pump 21 and the raw water supply valve 42. Is closed, the water collection piping valve 62 is opened, and the drainage pump 31 is operated. Thereby, the water in the first vertical hole 10 is discharged to the lower part of the third vertical hole 30 via the water collecting pipe 61, and the filtrate stored in the filtrate storage part 15 is directed downward to the floating filter medium layer 12. A large number of floating filter media constituting the floating filter material layer 12 are developed downward by flowing water. Then, the impurities and floating suspended substances captured in the floating filter medium layer 12 are discharged from the floating filter medium layer 12, and the floating filter medium layer 12 is back-washed. In addition, the water that flows into the third vertical hole 30 from the first vertical hole 10 (backwash drainage containing impurities and floating suspended matter supplemented by the floating filter material layer 12) is discharged from the drain pump 31. Through the third vertical hole 30 to the shielding tube 113.

  In the filtration system 200, the water level in the third vertical hole 30 is set at a predetermined position (for example, a solid line in FIG. 3) in order to prevent the drain pump 31 from idling due to a drop in the water level in the third vertical hole 30. In the third vertical hole 30, the operation of the drain pump 31 is stopped until the water level in the third vertical hole 30 rises.

  And according to this filtration system 200, it can avoid starting a backwash process when there is much inflow of raw | natural water into the 2nd vertical hole 20, like the previous filtration system 100. FIG. Moreover, it is possible to ensure that the backwashing process is started at a timing when the amount of raw water inflow is small, and the filtration system 200 can be efficiently washed.

  In addition, from the viewpoint of starting the backwashing process at a more appropriate timing, the backwashing process is preferably started when the inflow amount of the raw water decreases and the inflow amount becomes a predetermined amount or less. Even if the inflow of raw water is less than the specified amount, if the backwash process is started at a timing when the inflow of raw water tends to increase, the filtration process will be delayed and the raw water will be filtered efficiently This is because there is a case that cannot be done.

  As mentioned above, although the filtration system of this invention was demonstrated using an example, the filtration system of this invention is not limited to the said example, A change can be suitably added to the filtration system of this invention.

For example, switching from the above-described filtration step to the backwashing step, or switching from the backwashing step to the filtration step, further includes filtration differential pressure, precipitation, water level of the intercepting pipe that discharges backwash drainage, or a combination thereof. And the inflow of raw water may be used.
When switching between the filtration step and the backwashing step is performed using both the filtration differential pressure and the inflow amount of the raw water, specifically, it is performed as follows. The filtration system performs filtration while grasping the amount of inflow based on the operation time or stop time of the raw water pump 21 or the rotation speed of the raw water pump 21, and the filtration differential pressure approaches the upper limit value at which backwashing should be started. Check the inflow of raw water. And when the inflow of raw water exceeds a predetermined amount, the filtration is continued until the filtration differential pressure reaches the upper limit, and whether or not backwashing is performed according to the inflow at the time when the filtration differential pressure reaches the upper limit. decide. On the other hand, when the inflow amount is equal to or less than the predetermined amount, the filtration is continued until the water level in the second vertical hole 20 decreases, or the raw water pump 21 can be changed when the number of revolutions of the raw water pump 21 can be changed. The rotational speed of the pump 21 is increased to lower the water level of the second vertical hole 20. Then, backwashing is performed after confirming that the water level of the second vertical hole 20 has decreased.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the inflow of raw | natural water is fluctuate | varied, the washing | cleaning method of the filtration system and filtration system which can backwash a floating filter material layer at an effective timing can be provided. .

DESCRIPTION OF SYMBOLS 10 1st vertical hole 11 Screen 12 Floating filter material layer 13 Raw water inlet 14 Backwash drainage outlet 15 Filtrated water storage part 16 Filtration water outlet 20 Second vertical hole 21 Raw water pump 22 Inlet 30 Third vertical hole 31 Drain pump 32 Suction port 41 Raw water supply path 42 Raw water supply valve 50 Controller 51 Backwash mechanism controller 52 Raw water pump controller 61 Water collection pipe 62 Water collection pipe valve 100 Filtration system 111 Combined sewage pipe 112 Rain spout 113 Intercept pipe 114 River 115 Flow control valve 200 Filtration system

Claims (8)

A floating filter layer made of a floating filter medium, a screen arranged on the upper side of the floating filter medium to prevent the floating filter medium from flowing out, a raw water inlet and a backwash drainage outlet arranged below the floating filter medium layer And a first vertical hole provided with a filtrate storage part provided on the upper side of the screen,
A backwashing mechanism for draining water in the first vertical hole from the backwashing drainage outlet and backwashing the floating filter material layer in a downward flow;
A second vertical hole into which raw water flows,
A raw water supply channel for supplying raw water from the second vertical hole to the first vertical hole via the raw water inlet;
When the amount of raw water flowing into the second vertical hole per unit time exceeds a predetermined amount, the backwashing of the floating filter medium layer using the backwashing mechanism is not permitted to start, and per unit time A backwashing mechanism controller that permits the backwashing of the floating filter material layer using the backwashing mechanism when the inflow amount of the raw water flowing into the second vertical hole is a predetermined amount or less; Featuring a filtration system.   The backwashing mechanism controller operates the backwashing mechanism when the inflow of raw water flowing into the second vertical hole per unit time decreases and the inflow reaches the predetermined amount, so that the floating The filtration system according to claim 1, wherein reverse flow cleaning of the filter medium layer is started. A water level meter for measuring the water level in the second vertical hole;
A raw water pump for transferring the raw water into the first vertical hole via the raw water supply channel;
The filtration system according to claim 1 or 2, wherein the backwashing mechanism controller grasps an inflow amount of raw water flowing into the second vertical hole per unit time based on a measurement value of the water level gauge. A water level meter for measuring the water level in the second vertical hole;
A raw water pump for transferring the raw water into the first vertical hole via the raw water supply channel;
A raw water pump controller that activates the raw water pump when the water level measured by the water level meter exceeds a predetermined value, and stops the raw water pump when the water level is equal to or lower than a predetermined value;
The filtration system according to claim 1 or 2, wherein the backflow mechanism controller grasps an inflow amount of raw water flowing into the second vertical hole per unit time based on an operation time or a stop time of the raw water pump. A floating filter layer made of a floating filter medium, a screen arranged on the upper side of the floating filter medium to prevent the floating filter medium from flowing out, a raw water inlet and a backwash drainage outlet arranged below the floating filter medium layer And a first vertical hole provided with a filtrate storage part provided on the upper side of the screen; water in the first vertical hole is discharged from the backwash drainage outlet, and the floating filter material layer is flowed downward A backwashing mechanism for backwashing at a second; a second vertical hole into which raw water flows; a raw water supply channel for supplying raw water from the second vertical hole to the first vertical hole via the raw water inlet A filtration system cleaning method comprising:
A filtration step of filtering the raw water by passing the raw water flowing in from the raw water inlet into the floating filter material layer in an upward flow;
Draining the water in the first vertical hole from the backwash drainage outlet, and backwashing the backflow filter layer in a downward flow,
A cleaning method for a filtration system, wherein the backwashing step is performed only when the amount of raw water flowing into the second vertical hole per unit time is equal to or less than a predetermined amount.   The backwashing process is started when the inflow amount of raw water flowing into the second vertical hole per unit time decreases and the inflow amount reaches the predetermined amount. How to clean the filtration system. The filtration system further includes a raw water pump that transfers the raw water into the first vertical hole through the raw water supply channel,
Including a water level measurement step of measuring the water level in the second vertical hole,
7. The backwashing process is performed according to claim 5, wherein an inflow amount of raw water flowing into the second vertical hole per unit time is grasped based on a water level measured in the water level measurement process, and the backwashing process is performed. A method for cleaning the described filtration system. The filtration system further includes a raw water pump that transfers the raw water into the first vertical hole through the raw water supply channel,
In the filtration step, when the water level in the second vertical hole exceeds a predetermined value, the raw water pump is activated, the raw water is transferred into the first vertical hole, the filtration is performed, and the second vertical hole If the water level within is below a predetermined value, the raw water pump is stopped and filtration is temporarily interrupted until the water level in the second vertical hole exceeds a predetermined value,
The amount of raw water flowing into the second vertical hole per unit time is grasped based on the operation time or stop time of the raw water pump in the filtration step, and the backwashing step is performed. Item 7. The method for cleaning a filtration system according to Item 5 or 6.

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