JP6651131B2 - Water collecting mechanism and gravity filtration pond equipped with the water collecting mechanism - Google Patents

Description

  The present invention relates to a water collection mechanism for a gravity filtration pond and a gravity filtration pond provided with the water collection mechanism.

  Water purification plants take raw water from water sources such as rivers and reservoirs, purify it, and supply it to general demand as tap water. As a method of the purification treatment, a rapid filtration method is widely used (see Patent Document 1).

  The rapid filtration system refers to a system in which raw water is subjected to a coagulation sedimentation treatment to remove suspended solids and colloids as much as possible in a sedimentation basin and then filtered in a rapid filtration basin. The treated water discharged from the rapid filtration pond is generally supplied as tap water after being sterilized.

The following two types are known as rapid filtration systems.
(1) A type in which a filtration pond is divided into a plurality of filtration sections by a section dividing plate, and backflow washing is performed for each filtration section. (2) A type in which filtration is performed in a single filtration section (general gravity type filtration pond)
Based on FIG. 7A, a description will be given of a filtration process in a rapid filtration pond for purifying raw water by a rapid filtration method. Raw water from the raw culvert 1 flows into the filtration section 3 through the raw water inflow hole 2 and passes through the filter medium 4 arranged in the filtration section 3 at high speed, so that suspended substances such as flocs in the raw water flow into the filter medium. Attached or removed by sieving through a filtration layer. The filtered purified water passes through the water collecting device 5, flows into the water purification chamber 6, and flows out of the water purification pipe 7 to the water purifier 8.

  If the filtration process is continued, suspended matter removed from the raw water accumulates on the filter media 4 and clogging occurs between the filter media, and the filtration capacity of the rapid filtration pond decreases. When the filtration capacity is reduced, the turbidity of the filtered water increases and the water quality deteriorates, or the head loss increases and it becomes difficult to obtain a required filtration flow rate. For this reason, it is necessary to regenerate the filter medium 4 by backwashing in which the filter medium 4 is intermittently washed to remove suspended substances deposited on the filter medium 4.

  In the case of a filtration pond divided into a plurality of sections, when one filtration section is washed to remove deposits (flock) of the filter medium layer, the filtration resistance of the filtration section disappears and the filtration flow rate increases. Then, the raw water passes through the filter medium without being sufficiently filtered, or the flocs that are lightly captured (retained) in the filter medium layer immediately after the washing flow out, resulting in deterioration of the quality of purified water.

Therefore, in the case of a filtration pond divided into a plurality of sections, conventionally, as shown in FIGS. 7 (b), (c), and (d), in order to prevent the flow rate from increasing in the water purification pipe 7, which is the final outlet of the filtration section. A flow rate adjusting mechanism 60 is provided. The flow rate adjusting mechanism 60 has a small-diameter water passage hole 64 in a flap valve-shaped baffle plate 61, and the baffle plate 61 is attached to a support plate 62 by a hinge 63 so as to be freely opened and closed. This baffle plate 61 acts as a filtration resistor during filtration.
The baffle plate 61 discharges purified water through a small-diameter water passage hole 64 during filtration, and rebounds by a backwashing water flow as shown in FIG. 6C during backwashing, and removes a large amount of backwash water with a small resistance. Water can be passed.
However, since backwash water is directly sprayed on the baffle plate at the time of backwashing, the hinge 63 of the baffle plate is easily damaged, and the baffle plate may be missing in several years. Further, there is a problem that the baffle plate hinders the flow of water (causes turbulence) and adversely affects the uniform cleaning of the filtered sand.
Further, in a general gravity filter having a single filtration section, there is a problem that the filtration speed and the backwash speed vary at different locations when viewed on the plane of the filter.

JP-A-2003-299911

An object of the present invention is to eliminate variations in filtration speed and backwash speed at different locations in a filtration pond.
More specifically, the present invention relates to a gravity-type filtration pond in which the filtration basin is divided into a plurality of filtration sections, without providing the baffle plate 61, even immediately after backwashing one filtration section, It is an object of the present invention to provide a water collecting mechanism that prevents a filtration flow rate from increasing.
In addition, the present invention makes the filtration speed and the backwashing speed uniform in a gravity filtration pond having a single filtration section (suppresses the dispersion of the filtration speed and the backwashing speed at different points when viewed in the plane of the filtration pond). ).

The present invention for solving the above problems is as described below.
(1) The original culvert,
A filtration section having a filter medium layer and performing a filtration treatment of the water to be treated,
A water purifier for storing purified water obtained in the filtration section,
Used in gravity filtration ponds containing
A water collecting mechanism provided in the filtration section,
The water collecting mechanism includes a water collecting device that supports a filter medium and divides a filtering space into upper and lower portions, and a flow rate adjusting mechanism provided below the water collecting device,
The flow rate adjustment mechanism includes a perforated plate having a plurality of backwash hole, and a member for closing the backwash holes upstream of the perforated plate, member for closing the backwash holes, wherein the filtration Gyakuaraiana the closed by narrowing the flow passage area of the filtered water acts to reduce the water flow of filtration water through the backwash hole, the flow path of the backwash water by opening the backwashing pores during backwashing spread area, catchment mechanism, characterized in that said a member acting to backwash holes to increase the water flow of backwash water to pass through the securing the amount of water required for cleaning.
(2) a perforated plate having a plurality of backwash holes, wherein the flow rate adjusting mechanism comprises:
Having a water hole for filtered water to pass through, and a valve body having a larger diameter than the backwash hole,
The water collecting mechanism according to (1), wherein the valve body has an end portion fixed to the perforated plate so as to close the backwash hole on an upstream side of the perforated plate.
(3) a perforated plate having a plurality of backwash holes, wherein the flow rate adjusting mechanism comprises:
Consisting of a long band or sheet,
The band body or the sheet body is fixed to the perforated plate so as to cover the plurality of backwash holes on the upstream side of the perforated plate, and filtered water is provided at a position corresponding to each of the plurality of backwash holes. The water collecting mechanism according to the above (1), wherein the water collecting mechanism has a water passage hole for passing therethrough.
(4) a perforated plate having a plurality of backwash holes;
Consisting of a ball and
The ball is semi-fixed to the perforated plate so that a flow path space for filtered water is formed between the ball and the wall of the perforated plate forming the backwash hole on the upstream side of the backwash hole. The water collecting mechanism according to (1), wherein:
(5) Raw culvert,
A filtration section having a filter medium layer and performing a filtration treatment of the water to be treated,
A water purifier for storing purified water obtained in the filtration section,
And a gravity filter provided with the water collecting mechanism according to any one of the above (1) to (4).
(6) The gravity filtration pond according to the above (5), wherein the filtration section has a single filtration section.
(7) The gravity type filtration pond according to the above (5), further comprising a backflow washing device having a plurality of the filtration sections and performing backflow washing by moving the filtration sections for each section.

  By adopting the water collecting mechanism in the present invention, the filtration speed at different locations in the filtration section is made uniform, so that the filtration speed does not increase at a specific location. For this reason, the raw water does not pass through the filter medium without being sufficiently filtered, and the flocs that are lightly captured (retained) in the filter medium layer immediately after washing do not flow out, so that the water quality of purified water can be prevented from deteriorating. In addition, at the time of backwashing, the backwashing speed at different portions of the filtration section is made uniform, and uniform washing becomes possible.

It is a figure which shows the outline of a backwash washing | cleaning apparatus mobile filtration device. (A) is a top view of a backflow washing | cleaning apparatus mobile filtration device, (b) is A-A 'sectional drawing of (a). It is a figure which shows the state at the time of filtration of the filtration apparatus of embodiment which concerns on this invention, and backwashing. It is a figure showing the structure of the flow velocity adjusting mechanism concerning the embodiment of the present invention. FIG. 4 is a diagram illustrating a planar structure of a valve body used in the flow rate adjusting mechanism illustrated in FIG. 3. FIG. 4 is a diagram illustrating a structure of a flow rate adjusting mechanism having a structure different from that of FIG. 3 according to the embodiment of the present invention. FIG. 5 is a diagram illustrating a structure of a flow rate adjusting mechanism having a structure different from that of FIGS. 3 and 4 according to the embodiment of the present invention. It is a figure which shows the structure of the conventional backflow washing | cleaning apparatus mobile filtration device.

In the following, a case where the water collecting mechanism of the present invention is applied to a gravity filter of a backflow washing device moving type having a plurality of filtration sections will be described as an example.
First, an example of the configuration of the gravity filtration pond according to the present invention will be described with reference to FIGS. 1 (a) and 1 (b).
FIG. 1A is a plan view of the filtration pond. The filtration pond of the filtration device 100 is divided into a plurality of filtration sections 3 by a section dividing plate 15.
FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. 1A, and shows a state where backflow cleaning (hereinafter, also referred to as “backwashing”) is performed for one section.

Hereinafter, a filtration device according to an embodiment of the present invention will be described.
(Filtration process)
Raw water flows into the filtration section 3 from the raw culvert 1 uniformly through the raw water inlet 2.
In the filtration section 3, a filter medium 4 is deposited on a water collecting device 5. The raw water passes through the filter medium 4 to remove suspended solids, becomes purified water, and flows out to the water purifier 8 through the water collecting device 5, the water purifying room 6, and the water purifying pipe 7.

(Backwashing process)
The backflow cleaning device 20 includes an electric traveling platform 21, a backflow cleaning pump 22, a surface cleaning pump 23, a drainage pump 24, a cleaner box 25, a driving device 26, and a control panel 27.
When the backwashing of the filtration section 3 becomes necessary, the carriage 21 stops immediately above any of the filtration sections 3 in the filtration pond, and the backwashing pump 22 operates so that the purified water in the water purifier 8 is backwashed. And discharged as surface cleaning water. The purified water is pressurized by a backwashing pump 22, a part thereof is further pressurized by a surface washing pump 23 through a backwashing pipe and used as surface washing water, and a part of the purified water flows back through the purified water pipe 7 from the lower part of the water purifier 8. And used as backwash water. The wastewater from which the filter medium 4 has been washed is collected by a drainage pump 24, discharged to a drainage ladle 12 and flows into a drainage drain 13.

The state of the filtration layer before and after backwashing will be described with reference to FIG.
FIG. 2A shows a state before backwashing, and FIG. 2B shows a state after backwashing.
Before backwashing, as shown in FIG. 2A, the raw water W is purified through the filtration layer 4 of each section divided by the section dividing plate 15 and flows into the water purification chamber 6 via the water collecting device 5. At this time, there is no large difference in the filtration resistance in any of the filtration layers, and there is no large difference in the filtration speed 29.
However, immediately after backwashing one filtration section, as shown in FIG. 2 (b), the sediment (flock) 28 of the filtration section is removed, and only the filtration section has a reduced filtration resistance. Increase.

Therefore, in the present invention, an increase in flow velocity is suppressed by disposing a flow velocity adjusting mechanism (filtering resistor) below the water collecting device.
Hereinafter, an embodiment of the flow rate adjusting mechanism will be described.

(Embodiment 1)
3 and 4 are views showing the structure of the embodiment of the flow rate adjusting mechanism.
The flow velocity adjusting mechanism 30 is disposed below the water collecting device 5.
In addition, the water collecting device 5 is provided as a floor plate that divides a filtration section into an upper space and a lower space, and generally includes a perforated plate or a partition plate with a plurality of water collecting nozzles. Illustration is omitted.

The flow rate adjusting mechanism 30 includes a perforated plate 31 provided with a plurality of backwash holes 32 at predetermined intervals, and a valve body 33 provided to close the backwash holes 32 of the perforated plate 31. The valve body 33 is fixed to the perforated plate 31 by a support portion 35 at an end thereof, and can be rotated upward (opened) with the support portion 35 as a fulcrum by the backwash water flow. It has become.
During filtration, the valve element 33 is pressed against the perforated plate 31 by the flow of the filtered water and its own weight, etc., so that the filtered water flows into the water purification chamber at a reduced flow rate through the water passage holes 34. At this time, since the water hole 34 has a small diameter, the valve body 33 acts as a filtration resistor against the filtered water.
On the other hand, at the time of backwashing, the valve body 33 rotates (opens) about the support portion 35 as a fulcrum as shown in FIG. The amount of water required for washing can be secured.

FIG. 4 is a plan view of an example of the valve element 33.
The valve body 33 has a larger diameter than the backwash hole 32. A water hole 34 for filtered water is provided at the center of the valve body 33, and the valve body 33 is fixed to a perforated plate by a holding member 36 at a support portion 35.

(Embodiment 2)
FIG. 5 shows an example of a flow rate adjusting mechanism 40 according to a different embodiment.
The flow velocity adjusting mechanism 40 according to the present embodiment has a long flexible band member 41 provided with a plurality of water passage holes 42. The band 41 is fixed to the perforated plate 31 in which the backwash holes 32 are formed at predetermined intervals as shown in FIG.
At the time of filtration, since the band body 41 is pressed against the perforated plate 31 by the flow of the filtered water and its own weight or the like, the filtered water flows into the water purification chamber at a reduced flow rate through the water holes 42. At this time, since the water passage hole 42 has a small diameter, it acts as a filtration resistor against the filtered water.
On the other hand, at the time of backwashing, the band body 41 other than the pressing member 43 floats (opens) due to the water flow of the backwash water in the flexible band body 41, thereby increasing the flow area of the backwash water. The amount of water required for backwashing can be secured.

  When a plurality of band members 41 are arranged in parallel, instead of forming the flow velocity adjusting mechanism in a band shape as described above, a full sheet type covering the entire surface of the perforated plate 31 may be used. This is a shape having slits (cuts) in some places of the full sheet type, that is, a shape in which a plurality of band bodies 41 are partially connected. At the time of backwashing, the flexible sheet is floated by the backwashing water flow, so that the sheets other than the pressing member 43 are floated, and the slits of the sheet are opened, so that the flow path area is widened and the amount of water necessary for backwashing is secured. it can.

(Embodiment 3)
This embodiment will be described with reference to FIG.
In FIG. 6, the flow rate adjusting mechanism 50 includes a perforated plate 51 having a water passage hole 52 and a ball 53 that is semi-fixed to the perforated plate 51 by gravity on the support member 54 on the upstream side of the water passage hole 52 (see FIG. 6). The perforated plate 51 and the support member 54 may be integrated.)
The space between the ball 53 and the perforated plate 51 forms a flow path 55 of the filtered water.
Since the cross-sectional area of the flow channel 55 is formed small, the filtration resistance of the flow channel 55 is large, and the flow rate of the filtered water does not increase even immediately after backwashing.
On the other hand, at the time of backwashing, the ball 50 rises due to the water pressure of the backwashing water, the gap with the perforated plate 51 is widened, and it does not act as a resistor against the backwashing water, and secures a flow rate necessary for backwashing. Can be.
The material of the ball 53 is preferably a resin, a composite material of a resin and a metal, or a ceramic.
Further, the ball 50 is preferably fixed with a resin material that expands and contracts with respect to the perforated plate 51 or the support member 54.

As described above, the flow rate adjusting mechanisms 30, 40, and 50 are disposed below the water collecting device 5, and there are many small flow rate adjusting mechanisms to reduce the impact force during backwashing. (Hinges and baffles) are less likely to occur.
Further, since the flow rate adjusting mechanisms 30, 40, and 50 in the present invention do not obstruct the ventilation, they can be manufactured as a type that is also used for both washing and cleaning.
Further, there is an effect of equalizing the backwashing.
In addition, at the time of filtration, a pressure loss (resistor) is produced, but it also has an effect of equalizing the filtration speed.

  Although the case where the water collecting mechanism of the present invention is applied to a gravity filter having a plurality of filtration sections has been described above, the water collecting mechanism of the present invention is applied to a gravity filter having a single filter section. However, it is clear that the effect of making the filtration speed uniform can be obtained.

1 Raw culvert 2 Raw water inlet 3 Filtration section (section of filtration pond)
Reference Signs List 4 filter media, filtration layer 5 water collecting device 6 water purification room 7 water purification tube 8 water purification conduit 9 backwash sliding valve 10 water purification masou 11 water purification outflow pipe 12 drainage drain 13 drainage 14 drainage pipe 15 section dividing plate 20 backflow cleaning device 21 traveling Table 22 Backflow cleaning pump 23 Surface cleaning pump (filtration drain pump)
DESCRIPTION OF SYMBOLS 24 Drain pump 25 Cleaner box 26 Drive device 27 Control panel 28 Deposit 29, 29 'Filtration speed 30, 40, 50 Flow rate adjusting mechanism 31 Perforated plate 32 Backwash hole 33 Valve body 34 Water passage hole 35 Supporting part 36 Pressing member 41 Band body 42 water passage hole 43 pressing member 51 perforated plate 52 water passage hole 53 ball 54 support member 55 water passage 60 flow rate adjusting mechanism 61 baffle plate 62 support plate 63 hinge 64 water passage hole 100 filtration device

Claims (7)

Raw culvert,
A filtration section having a filter medium layer and performing a filtration treatment of the water to be treated,
A water purifier for storing purified water obtained in the filtration section,
Used in gravity filtration ponds containing
A water collecting mechanism provided in the filtration section,
The water collecting mechanism includes a water collecting device that supports a filter medium and divides a filtering space into upper and lower portions, and a flow rate adjusting mechanism provided below the water collecting device,
The flow rate adjustment mechanism includes a perforated plate having a plurality of backwash hole, and a member for closing the backwash holes upstream of the perforated plate, member for closing the backwash holes, wherein the filtration Gyakuaraiana the closed by narrowing the flow passage area of the filtered water acts to reduce the water flow of filtration water through the backwash hole, the flow path of the backwash water by opening the backwashing pores during backwashing spread area, catchment mechanism, characterized in that said a member acting to backwash holes to increase the water flow of backwash water to pass through the securing the amount of water required for cleaning. The flow rate adjusting mechanism, a perforated plate having a plurality of backwash holes,
Having a water hole for filtered water to pass through, and a valve body having a larger diameter than the backwash hole,
2. The water collecting mechanism according to claim 1, wherein an end of the valve body is fixed to the perforated plate so as to close the backwash hole on an upstream side of the perforated plate. 3. The flow rate adjusting mechanism, a perforated plate having a plurality of backwash holes,
Consisting of a long band or sheet,
The band body or the sheet body is fixed to the perforated plate so as to cover the plurality of backwash holes on the upstream side of the perforated plate, and filtered water is provided at a position corresponding to each of the plurality of backwash holes. The water collecting mechanism according to claim 1, further comprising a water passage hole for passing the water collecting hole. The flow rate adjusting mechanism, a perforated plate having a plurality of backwash holes,
Consisting of a ball and
The ball is semi-fixed to the perforated plate so that a flow path space for filtered water is formed between the ball and the wall of the perforated plate forming the backwash hole on the upstream side of the backwash hole. The water collecting mechanism according to claim 1, wherein: Raw culvert,
A filtration section having a filter medium layer and performing a filtration treatment of the water to be treated,
A water purifier for storing purified water obtained in the filtration section,
A gravity type filtration pond comprising the water collecting mechanism according to any one of claims 1 to 4.   The gravity filtration pond according to claim 5, wherein the filtration section has a single filtration section.   The gravity type filtration pond according to claim 5, comprising a plurality of the filtration sections, and a backwashing device for performing backflow washing by moving the filtration sections for each section.

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