JP2015027646A - Filtration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filtration apparatus which can discharge efficiently captured matter peeled from a filter medium during washing, prevent outflow of the filter medium contained in washing drainage from a drainage trough by means of a simple appliance and reduce the washing time and the amount of washing water in washing.SOLUTION: A filtration apparatus 1 includes a filtration layer 10 formed by packing a filter medium in the filtration tank 2 and a discharge trough 20 arranged above the filter layer 10, and a screen 60 is arranged on a side wall 22 of the discharge trough 20 which peels captured matter captured by the filtration layer 10 from the filter medium 11 by washing and discharges as washing drainage. The arrangement angle α of the screen 60 is 45-90 degree, and the arrangement width W is 14-36% of the inside-dimension width WT of the discharge trough 20.

Description

  The present invention relates to a filtration device including a discharge trough from which detained matter captured in a filter layer is separated from a filter medium by cleaning and discharged as cleaning waste water.

  A filtration apparatus having a filter layer formed by filling a filter medium with a filter medium allows water to be treated to flow into the filtration apparatus from above and traps and separates turbidity in the water to be treated by the filter layer from below. When the filtration process to be taken out is carried out for a certain period of time, turbidity exceeding the target value leaks to the treated water or the loss head reaches the set value, so the detained matter captured in the filter layer is separated from the filter medium by washing and discharged as washing wastewater. A cleaning process for regenerating the drainage layer from the trough is performed.

  As a method of cleaning the filtration apparatus, a surface washing / back washing combined type in which surface washing with washing water (hereinafter referred to as “surface washing”) and backwashing with washing water (hereinafter referred to as “back washing”) is performed, or There are backflow cleaning with air (hereinafter referred to as “air washing”), and air washing and back washing combined methods in which back washing is performed. In any of the washing methods, the backwash water flowing from the lower part of the filter bed at the time of washing fluidizes the filter bed, and the filter medium rises with the wash water while being rubbed and expanded. The detained material separated from the filter medium is discharged as washing wastewater from a discharge trough provided in the upper part of the filter layer by an upward water flow.

  However, since the drainage trough is formed in a bowl shape with an opening at the top, there is a risk that a part of the filter medium will flow out together with the cleaning drainage. Needed to be installed. However, when the discharge trough is installed at a high position, there is a problem that the detained matter discharge efficiency is deteriorated, and that an extra washing time and an amount of washing water are required for washing.

  In the following Patent Document 1, it is proposed to cover between drainage troughs with a filter medium outflow prevention net as a countermeasure against the outflow of the filter medium. However, if the upper space of the filter medium is covered with a filter medium outflow prevention net, it will be difficult to visually confirm the state of the filter medium and the surface washing pipe, etc. existing under the filter medium outflow prevention net. There was a problem that maintenance was difficult.

  Furthermore, in Patent Document 2 described below, as a measure to prevent the outflow of the filter medium, a cylindrical or polygonal screen having a water passing portion around the washing outflow portion is provided, or a bowl-shaped drainage trough having an open top is provided as an umbrella. It has been proposed to cover with a dome-shaped or dome-shaped screen. However, if the entire periphery is a water-permeable portion formed of a cylindrical or polygonal screen, or the opening of the drainage trough is covered with a screen, the filter medium contained in the cleaning wastewater is placed on the upper portion of the screen 101 as shown in FIG. Since it accumulates as the accumulated filter medium 102, the accumulated filter medium 102 adheres to the screen 101 due to the flocculant and turbidity contained in the raw filter water that flows in at the start of filtration after washing, and clogging occurs, and it should be discharged originally during washing. There was a defect that the discharge of detainment was hindered. Although it has been proposed to introduce a water flow or air in the opposite direction to the screen in order to eliminate the accumulated filter media, a large amount of water or air is required to spread the water flow or air to every corner of the screen. In many cases, there are four or more exhaust troughs that are necessary for large-scale filtration devices, so there is a problem that the installation cost will be very high if each exhaust trough is equipped with a cleaning valve and piping. there were.

  Furthermore, in Patent Document 3 below, an inclined plate is provided between the upper part of the filter layer and the lower part of the discharge trough to create a flow path for the cleaning drainage, and the filter medium contained in the cleaning drainage is provided by a baffle provided between the inclined plate and the discharge trough. It has been proposed to separate and return to the filter bed. However, since it is necessary to install a large structure below the discharge trough, there is a problem that the installation cost becomes high and the maintainability of the filter layer is impaired.

No. 53-115465 Japanese Patent No. 3479894 Japanese Patent No. 4831052

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to be able to efficiently discharge the detained material that has peeled off the filter medium during cleaning from the discharge trough with simple equipment. Simultaneously, it is providing the filtration apparatus which can prevent that the filter medium contained in washing | cleaning drainage flows out from a drainage trough.

  Another object is to provide a filtration device that can prevent the filter medium contained in the cleaning wastewater from flowing out from the discharge trough even if the cleaning time and the amount of cleaning water during cleaning are reduced.

  In order to achieve the above object, a filtration device according to claim 1 of the present invention includes a filter layer formed by filling a filter tank with a filter medium, and a discharge trough installed above the filter layer. In the filtration apparatus, the detained matter trapped in the filter layer is separated from the filter medium by cleaning and is provided with a screen on the side wall of the discharge trough from which it is discharged as cleaning waste water.

  Moreover, the filtration apparatus according to claim 2 of the present invention is characterized in that, in the filtration apparatus according to claim 1, the installation angle of the screen installed on the side wall is 45 degrees to 90 degrees. is there.

  Moreover, the filtration apparatus according to claim 3 of the present invention is the filtration apparatus according to claim 1 or 2, wherein the installation width of the screen installed on the side wall is 14% to 14% of the inner width of the discharge trough. It is characterized by 36%.

  In the filtering device of the present invention having the above-described configuration, since the screen is installed on the side wall of the discharge trough, the detained matter can be discharged efficiently, and at the same time, the detained matter is discharged from the discharge trough as washing waste water. In this case, the filter medium contained in the cleaning wastewater can be blocked by the screen, and the filter medium can be prevented from being discharged from the discharge trough together with the cleaning wastewater. Therefore, the installation position of the discharge trough is higher than the surface of the filter layer, but can be installed at a position lower than the conventional one, so that the filtration time can be shortened and the amount of filtered water can be reduced.

  Furthermore, in the filtration device of the present invention, since the installation angle of the screen installed on the side wall is 45 degrees to 90 degrees, the filter medium whose flow is prevented by the screen falls by its own weight without being deposited on the screen, The clogging due to the filter medium adhering to the screen can be prevented, and the detained matter can be discharged efficiently.

  Furthermore, in the filtration device of the present invention, the installation width of the screen installed on the side wall is 14% to 36% with respect to the inner width of the discharge trough, and therefore when the detained matter is discharged from the discharge trough as washing waste water. The filter media contained in the cleaning wastewater is effectively blocked by the screen, so that the filter media can be prevented from being discharged from the discharge trough together with the cleaning wastewater, and installed in other discharge troughs. Since a predetermined gap can be formed between the screen and the screen, the maintenance of the filter layer can be easily performed. Furthermore, by setting the installation width of the screen to 14% to 36% with respect to the inner width of the discharge trough, the installation cost of the screen can be reduced and the installation cost of the screen can be reduced.

Schematic cross-sectional explanatory drawing of the filtration device according to the present invention 1 is a schematic plan view of the filtration device of FIG. Cross-sectional explanatory drawing showing examples of various shapes of the discharge trough according to the present invention Cross-sectional explanatory drawing which shows the example of the state by which the screen which concerns on this invention was installed in various discharge troughs The figure which showed the relation of the overpass of the filter medium and the accumulation state in the installation angle and the installation width of the screen installed in the discharge trough Schematic explanatory diagram showing a state in which a detained object is fixed to a screen of a conventional example

  Hereinafter, a filtration device according to an embodiment of the present invention will be described with reference to the drawings. However, the scope of the present invention is not intended to be limited to the contents described in this embodiment.

  FIG. 1 is a schematic cross-sectional explanatory view of the filtration device according to the present invention, FIG. 2 is a schematic plan explanatory view of the filtration device of FIG. 1, and FIG. 3 is a cross-sectional explanatory view showing examples of various shapes of the discharge trough according to the present invention, FIG. 4 is an explanatory cross-sectional view showing an example of a state in which the screen according to the present invention is installed in various discharge troughs.

  The filtration device 1 according to the present invention includes a filtration layer 10 and a discharge trough 20. Further, the filtration device 1 includes a treated water introduction pipe 30 at the top of the filtration tank 2, a washing water introduction pipe 40 and an air introduction pipe 50 at the bottom of the filtration tank 2.

  The filter layer 10 is formed of a filter medium 11 filled in the filtration tank 2. The filter layer 10 is a multilayer (10A, 10B) formed of two types of filter media (11A, 11B). A filter medium 11A having a large effective diameter, such as anthracite, is used for the upper filter layer 10A, and a filter medium 11B having a small effective diameter, for example, silica sand, is used for the lower filter layer 10B. In addition, although a present Example demonstrates the case where the filter layer 10 is a multilayer, a single layer may be sufficient.

  The discharge trough 20 is located above the filtration tank 2, and the bottom surface 21 of the discharge trough 20 is installed at a position higher than the surface 12A of the upper filter layer 10A when the filter layer 10 expands during cleaning.

  As shown in FIG. 2, the discharge trough 20 is installed across the other peripheral wall 3 </ b> B facing the central portion of the filtration tank 2 from the one peripheral wall 3 </ b> A. In addition, the discharge trough 20 may be installed along the peripheral wall 3 of the filtration tank 2. The cross-sectional shape obtained by cutting the discharge trough 20 in the vertical direction is as shown in FIG. 3, and the cross section is generally rectangular, but it may be polygonal or U-shaped.

  As shown in FIG. 4, a screen 60 is installed at the upper end 23 of the side wall 22 of the discharge trough 20. The installation angle α of the screen 60 is an angle formed with the horizontal line m drawn from the upper end 23 of the side wall 22 of the discharge trough 20. As shown in FIG. 5, the installation angle α is preferably in the range of 45 degrees to 90 degrees. A range of 60 to 75 degrees is more preferable. This is because the filter medium 11 easily flows into the discharge trough 20 when the angle is 45 degrees or less, and the filter medium 11 is deposited on the screen 60 when the angle is 90 degrees or more.

  The installation width W of the screen 60 is the length W in the width direction of the screen as shown in FIG. 4, and the ratio based on the inner width WT of the discharge trough 20 is 14% to 36% as shown in FIG. A range of 21% to 29% is more preferable. If it is 14% or less, the filter medium 11 easily flows into the discharge trough, and if it is 36% or more, the distance between the screen 60 and the screen 60 installed in the other discharge trough 20 becomes narrow, and maintenance of the filter layer 10 is performed. This is because the screen 60 becomes larger and the installation cost of the screen 60 becomes higher.

  The screen 60 is preferably installed at the upper end 23 of the side wall 22 of the discharge trough 20, but may be installed at the lower end 24 of the side wall 22 and the central portion 25 between the upper end 23 and the lower end 24. Further, the screen 60 is installed on both sides when the discharge trough 20 is installed in the central portion of the filtration tank 2, but when the discharge trough 20 is installed along the peripheral wall 3 of the filtration tank 2, It will be installed only on one side. The number of screens 60 installed on one side of the side wall 22 of the discharge trough 20 is preferably one, but a plurality of screens 60 may be installed.

  The screen 60 is preferably mesh-shaped, but may be slit-shaped. Further, in the case of the mesh-shaped screen 60, it is desirable that the mesh opening be smaller than the particles of the filter medium 11 and larger than the retention. Furthermore, a planar shape is generally used as the shape of the screen 60, but it may be a curved shape.

  A treated water introduction pipe 30 for introducing treated water is installed in the upper part of the filtration tank 2. A cleaning drainage discharge pipe 26 for discharging the cleaning wastewater to the outside of the filtration tank 2 is connected to the end of the discharge trough 20.

  Below the lower filtration layer 10B, in the lower part of the filtration tank 2, a washing water introduction pipe 40 that introduces washing water that also serves as a treated water discharge pipe that discharges the treated water, and an air that introduces air for performing air washing. An introduction pipe 50 is installed.

  Next, an operation method of the filtration device 1 according to the above configuration will be described. The operation of the filtration device 1 includes a filtration process and a cleaning process.

  The filtration process includes the water to be treated by opening the valve of the water to be treated introduction pipe 30, introducing the water to be treated from above the filtration tank 2, and passing the water to be treated from the top to the bottom of the filter layer 10. The suspended turbidity is captured and separated by the filter layer 10, and the treated water is stored in a storage tank (not shown) via a treated water discharge pipe also serving as a washing water introduction pipe 40 installed at the lower part of the filtration tank 2. Is done.

  When the filtration process is carried out for a certain period of time, turbidity exceeding the target value leaks into the treated water or the loss head reaches the set value, and thus a cleaning process is necessary.

  In the cleaning process, the valve of the treated water introduction pipe 30 is closed and the valve installed in the passage connecting the treated water discharge pipe that also serves as the washing water introduction pipe 40 and the storage tank is closed. . Next, after the valve of the air introduction pipe 50 is released and air is introduced and air washing is performed for a certain period of time, it is installed in a passage connecting the washing water introduction pipe 40 and a washing water tank (not shown). The valve is opened, washing water is introduced, and backwashing is performed. The air washing is finished when a certain time has elapsed since the back washing was started, and thereafter only the back washing is performed.

  When backwashing is performed, the wash water introduced from the wash water introduction pipe 40 installed in the lower part of the filtration tank 2 flows from the bottom to the top of the filter layer 10 and is captured by the filter layer 10 by the water flow of the wash water. The detained material separated from the filter medium 11 is transported to above the filter layer 10, flows into the discharge trough 20 as cleaning wastewater, and is discharged out of the filtration tank 2 through the cleaning drainage discharge pipe 26.

  In this case, although the filter medium 11 is mixed with the detained material in the washing wastewater, the filter medium 11 is prevented from flowing into the discharge trough 20 by the screen 60 installed on the side wall 22 of the discharge trough 20, and the detained material is removed. Only the cleaning waste water contained passes through the screen 60 and flows into the discharge trough 20. Since the filter medium 11 blocked by the screen 60 falls from the screen 60 by its own weight, the filter medium is prevented from being deposited on the screen 60.

  As described above, since the screen 60 is installed on the side wall 22 of the discharge trough 20, it is possible to prevent the filter medium 11 contained in the cleaning wastewater from flowing out and to discharge the detained material efficiently.

  Moreover, the installation position of the discharge trough 20 in the filtration tank 2 can be set to a position slightly higher than the filtration layer surface 12A of the upper filtration layer 10A that expands during backwashing. That is, since the installation position of the discharge trough 20 can be set to a position lower than the conventional installation position, it is possible to shorten the cleaning time at the time of backwashing and to reduce the cleaning water.

  Furthermore, since it is a simple facility in which the screen 60 is simply installed on the side wall 22 of the discharge trough 20, it is possible to reduce the facility cost.

  Furthermore, since the installation angle α formed between the screen 60 installed on the side wall 22 and the water change line m drawn from the upper end 23 of the side wall 22 is 45 to 90 degrees, the filter medium 11 whose flow is prevented by the screen 60 is the screen. It is possible to prevent clogging due to falling by its own weight without being deposited on 60 and preventing the clogging due to the filter medium 11 adhering to the screen 60 and discharging the detained material efficiently.

  Further, since the installation width W of the screen 60 installed on the side wall 22 is 14% to 36% of the inner width WT of the discharge trough 20, it is included in the cleaning wastewater when the detained matter is discharged from the discharge trough as the cleaning wastewater. It is possible to efficiently block the filter medium being filtered by the screen and prevent the filter medium from being discharged from the discharge trough out of the filtration tank 2 together with the washing waste water, and the screen 60 and the adjacent discharge trough 20. Since a sufficient gap can be formed between the screen 60 and the screen 60 installed in the filter layer 10, the filter layer 10 can be easily maintained.

  In addition, in the said Example, although the air-washing and backwash combined use type was demonstrated, the case of a surface wash and backwash combined use type is also the same.

DESCRIPTION OF SYMBOLS 1 Filtration apparatus 2 Filtration tank 3, 3A, 3B Perimeter wall 10, 10A, 10B Filter layer 11, 11A, 11B Filter medium 12, 12A Filter layer surface 20 Discharge trough 21 Bottom surface 22 Side wall 23 Upper end 24 Lower end 25 Center part 26 Washing drain discharge pipe 30 treated water introduction pipe 40 wash water introduction pipe (treated water discharge pipe)
50 Air introduction pipe 60 Screen m Horizontal line W Installation width WT Inner width of discharge trough α Installation angle

Claims (3)

In a filtration device comprising a filter layer formed by filling a filter medium with a filter medium, and a discharge trough installed above the filter layer,
A filtration device, wherein a detained matter trapped in the filter layer is separated from the filter medium by washing and is discharged as washing waste water on a side wall of the discharge trough. The filtration device according to claim 1,
The filtration apparatus, wherein an installation angle of the screen installed on the side wall is 45 degrees to 90 degrees. In the filtration device according to claim 1 or 2,
The filtration apparatus according to claim 1, wherein an installation width of the screen installed on the side wall is 14% to 36% of an inner width of the discharge trough.

Images