JP2022013214A - Filtration device, filtration system, method for cleaning mesh filter, and method for cleaning strainer filter - Google Patents

Abstract

To provide a technique for sufficiently removing dirt adhering to a sponge filter included in the filtration device.SOLUTION: A filtration device 10 comprises: a container 11; and a sponge filter 12 as a filter medium arranged inside the container. The container 11 is connected with: a connecting pipe 91 being an inflow pipe; and a connecting pipe 92 being an outflow pipe. The connecting pipe 91 is provided with a valve 91X, and the connecting pipe 92 is provided with a valve 92X. When the sponge filter 12 is cleaned, the valve X of the connecting pipe 92 is closed. Meanwhile, the valve 91X of the connecting pipe 91 is operated so that a state in which water flows from the connecting pipe 91 into the container 11 and a state in which water flows out from the container 11 flows through the drain pipe 91Y are repeated alternately a plurality of times.SELECTED DRAWING: Figure 5

Description

The present invention mainly relates to a filter cleaning technique for removing stains on a filter contained in a filtration device generated in a filtration device for filtering a liquid. The filtration device also includes a strainer.

For example, a filtration device or a filtration system is used when purifying sewage such as muddy water or industrial wastewater or desalinating seawater. The filtration system is configured by connecting filtration devices in multiple stages.
The filtration device consists of an inflow pipe, which is a pipe for inflowing sewage containing impurities to be filtered, a container connected to the outflow pipe for flowing out purified water, and an inflow pipe to the outflow pipe in the container. The sewage was placed in the container so that it would always pass through it (for example, the inside of the container was divided into a space connected to the inflow pipe and a space connected to the outflow pipe). Equipped with a filter.
As is common sense, the sewage that has flowed into the container from the inflow pipe becomes purified water by being filtered by the filter when passing through the filter, and flows out from the outflow pipe. When the filtration device is connected in multiple stages, the sewage that flows into the container of the filtration device on the downstream side from the inflow pipe is the purified water that flows out from the outflow pipe connected to the container of the filtration device one upstream. In the present application, in each filtration device, the liquid flowing into the container is referred to as sewage, and the liquid flowing out of the container is referred to as purified water.

By the way, when the filtration device is used, the filter becomes dirty due to the adhesion of the filtered solid matter. If the filter becomes dirty, sewage cannot pass through the filter, and the filtration device may not function properly. This problem becomes more pronounced when the turbidity of the sewage is high.
For example, when an attempt is made to filter muddy water generated by civil engineering work with a filtration device or a filtration system, the filtration device may not function normally in a short time of about 15 minutes.

One of the countermeasures against the dirt on the filter in the filtration device is to remove the dirt on the filter.
A well-known method of removing stains on a filter is, for example, backwashing.
In backwashing, purified water (in many cases, fresh water) was poured into the container from the outflow pipe from which purified water normally flows, passed through the filter, and adhered to the filter separated from the filter when passing through the filter. This is a process in which purified water containing dirt is discharged to the outside of the container from an inflow pipe that normally flows the sewage into the container. By this backwash, in which purified water is poured into the container in the opposite direction to the normal direction, dirt adhering to the filter can be removed to some extent.
However, there are cases where the stains adhering to the filter are not sufficiently removed only by backwashing.

An object of the present invention is to provide a technique capable of removing stains adhering to a filter in a filtration device provided with a certain type of filter better than backwashing.

The present invention adheres to a filter in a filtration device equipped with a filter (generally, it is a strainer used at an intake port, but since it also has a filter for filtering solid matter, it is treated as a kind of filtration device in the present application). The challenge is to provide a technique that can remove the dirt that has been removed better than backwashing.

In order to solve this problem, the applicant of the present application has repeated research. As a result, it has been found that the dirt adhering to the filter under specific conditions can be better removed by using air which is not generally used for cleaning the filter.
Moreover, if the dirt adhering to the filter can be better removed by using the air that exists everywhere, it is easier to use than the backwash that generally uses fresh water, and it is advantageous in terms of cost.
The invention described below is based on such findings.

The invention of the present application is divided into a first invention and a second invention for convenience. The first invention is as follows.
The first invention is a container, an inflow pipe which is a pipe connected to the container for inflowing sewage containing impurities into the container, and a pipe connected to the container for discharging purified water from the container. A certain outflow pipe and a mesh filter, which is a mesh-like filter, are arranged in the container so that sewage from the inflow pipe to the outflow pipe always passes through the outflow pipe. It is a method of cleaning a mesh filter that removes dirt adhering to the mesh filter in the filtering device, and supplies air bubbles into the sewage or purified water in the container at the time of cleaning the mesh filter. However, it is a method of cleaning a mesh filter (sometimes referred to simply as a “cleaning method”) in which at least a part of the mesh filter is exposed to the foam.
The inventor of the present application has found that when the filter is a mesh filter, air bubbles can easily remove dirt adhering to the filter. Based on this finding, the gist of the first invention is to supply air bubbles into sewage or purified water in which the mesh filter is immersed, and to expose at least a part of the mesh filter to the air bubbles.
When the mesh filter is exposed to air bubbles, the bubbles adhere to or pass through the mesh filter. As a result, for example, due to friction caused by bubbles, dirt adhering to the mesh filter is separated from the mesh filter. This effect is hidden when the filter is a resin filter, a fiber filter, a sponge filter, or the like, and is remarkable when the filter is a mesh-like mesh filter. This is because if the filter has a certain thickness, such as a sponge filter, the foam has the property of being difficult to penetrate into the inside of the filter, but the surface is where the dirt adheres most. The inventor thinks that if there are many mesh filters, the effect of removing stains can be well exerted only by stimulating the surface of the mesh filter with bubbles.
As the mesh filter, there is also a resin mesh filter made of a resin such as polyester, polyethylene, nylon, etc., and even if the mesh filter is a resin mesh filter, the effect of the first invention is superior to the conventional one. However, the effect of removing stains by bubbles is particularly remarkable when the mesh filter is made of metal, for example, stainless steel. It seems that this is because when the mesh filter is made of metal, dirt adheres only to the surface of the mesh filter.
That is, the mesh filter to which the first invention of the present application is applied may be made of resin, but is made of metal, for example, stainless steel.
It should be noted that the air bubbles do not need to be directly supplied to the inside of the container. For example, the foam may be supplied into the inflow or outflow pipe and indirectly from there into the container.

In the cleaning method according to the first invention, when the foam is supplied into the sewage in the container or the purified water, the sewage is supplied to the container from the inflow pipe and the outflow pipe from the container is supplied. It may stop the discharge of the purified water through. This is to wash the mesh filter with air bubbles while stopping the entry and exit of sewage or purified water into the container.
When the mesh filter is washed with foam in a state where sewage or purified water enters and exits the container, a large water pressure is likely to be applied to the sewage or purified water in the container. When a large amount of water pressure is applied to sewage or purified water, the air bubbles in them become smaller. Then, the effect of cleaning the mesh filter with foam is reduced, so it is desirable to avoid cleaning the mesh filter with sewage or purified water flowing in and out of the container.
In addition, when supplying bubbles into the container, an opening provided in the container at a position higher than the water surface of sewage or purified water (for example, if there is an opening on the upper surface of the container, "at a position higher than the water surface of sewage or purified water". The condition that "there is an opening" is satisfied.) It is preferable to open. According to this, the air pressure in the container and, by extension, the water pressure of the sewage or purified water in the container can be reduced. As a result, it becomes easy to prevent the bubbles from becoming smaller and the effect of cleaning the mesh filter by the bubbles from being reduced.

In the cleaning method according to the first invention, the foam supply point in the container may be in the range of 1/5 below the depth of the container. Bubbles rise from bottom to top in sewage or purified water. Therefore, the deeper the bubble supply point, the higher the probability that the bubble will come into contact with the mesh filter, which is advantageous. If the foam is supplied in the lower 1/5 of the depth of the container, the probability that the foam will contact the mesh filter (or the ratio of the foam to contact in the area of the mesh filter or the unit area of the mesh filter). It is advantageous because the amount of bubbles that come into contact with each other increases.

As another aspect of the first invention, the inventor of the present application also proposes a filtration device. The effect of the invention of the filtration device is equal to the effect of the method of cleaning the mesh filter according to the first invention. Further, it is also an effect of the filtration device that it is suitable for carrying out the cleaning method according to the first invention.
An example of the filtration device according to the first invention is a container, an inflow pipe which is a pipe connected to the container for inflowing sewage containing impurities into the container, and the container for discharging purified water from the container. It is a mesh-like filter arranged in the container so that the outflow pipe, which is a connected pipe, and the sewage flowing from the inflow pipe to the outflow pipe in the container always pass through the outflow pipe. It is a filtration device having a mesh filter.
The filtration device includes an air supply pipe that supplies air bubbles into the sewage or purified water in the container when the mesh filter is washed, and the air supply pipe is supplied from the air supply pipe. The foam exposes at least a portion of the mesh filter.
Even in this case, the air bubbles do not need to be directly supplied to the inside of the container. For example, it may be connected to an air supply pipe, an inflow pipe or an outflow pipe, and bubbles supplied into them may be indirectly supplied into the container from there.

The air supply pipe may be configured such that the supply point of the foam in the container is in the range of 1/5 below the depth of the container. The effect of the present invention is equal to the effect of the cleaning method according to the first invention to the same effect. As already mentioned, the air supply pipe does not have to supply air directly into the container. It means that the position when the air bubbles reach the inside of the container is within the range of 1/5 of the depth of the container.
The container may be vertically long. For example, the container may be a vertically long cylinder or a conical trapezoid. If the container is vertically long, the foam supply position in the container tends to be the deep part of the container.
In the filtration device of the first invention, valves are provided in each of the inflow pipe and the outflow pipe, and the inflow is performed when the foam is supplied into the sewage or the purified water in the container. A state in which the valve of the pipe is in a state of stopping the supply of the sewage from the inflow pipe to the container, and the valve of the outflow pipe is in a state of stopping the discharge of the purified water from the container through the outflow pipe. You may be able to do it. According to this, air bubbles can be supplied into the container with the inflow and outflow of sewage and purified water to the container stopped. The effect is as described above in the description of the method of the first invention.

The inventor of the present application also proposes a filtration system including a filtration device according to the present invention as an aspect of the present invention.
The filtration system of the present invention includes a plurality of filtration devices connected in multiple stages, and at least one of the plurality of filtration devices is one of the filtration devices described so far according to the first invention of the present application. It is a filtration system. The effect of this filtration system is that it is easier to clean the mesh filter of the plurality of filtration devices corresponding to the filtration device of the present invention provided with at least the mesh filter.

The second invention of the present application is as follows.
The second invention comprises a case having an opening and a strainer filter which is a filter covering the opening of the case, connected to a pipe connected to a pump, and submerged or immersed in sewage. It is a method of cleaning a strainer filter in a strainer used for sucking up the sewage through a pipe.
In this method of cleaning the strainer filter, the strainer is submerged in or immersed in sewage and passed through the pipe to the case through the pipe until air is ejected from the strainer filter into the sewage. Send air.
When air is sent into the strainer case that is submerged or submerged in sewage in this way, the air does not flow out smoothly from the fine strainer filter, and it is irregular or sudden. The air goes out. It is good to give the outflowing air enough force to blow off the dirt on the strainer filter. That is, the air pressure inside the strainer case needs to be increased to some extent. By doing so, when the air flows out from the strainer filter into the sewage, the air intermittently gains momentum and flows out so as to repeat a small explosion. As a result, dirt on the strainer filter is efficiently removed.
Sudden outflow of air from the strainer filter in a small explosion-like state often occurs when the strainer filter has a certain degree of fineness. An outflow of air such as an explosion generally occurs when the strainer filter has a mesh size of 500 μm or less, and almost certainly occurs when the strainer filter has a mesh size of 200 μm or less.
Further, it is preferable that the air is sent into the strainer case continuously to some extent so that the air pressure in the case is kept high to some extent for a while, for example, for a few minutes. Thereby, a small explosion as described above due to the outflow of air from the strainer can be promoted.

When the sewage is sucked up from the strainer again after cleaning the strainer filter, it is preferable to bleed the air in the case and the pipe of the strainer before starting the sucking up of the sewage.
If the air pressure inside the strainer case is too high, for example, even if the pump is immersed to apply negative pressure to the pipe, sewage cannot be successfully drawn into the case through the strainer filter. In order to prevent such a problem, it is advisable to reduce the air pressure in the strainer case and the hose, for example, to normal pressure or almost normal pressure.
For example, if the other end of the pipe to which one end is connected to the strainer of the pipe is opened, the air pressure in the strainer case and the pipe drops to almost normal pressure within a few seconds.

The figure which shows schematic about the whole structure of the filtration system by one Embodiment. A side sectional view conceptually showing the configuration of the most upstream filtration device included in the filtration system shown in FIG. 1. A side sectional view conceptually showing the configuration of the second and third filtration devices from the upstream side included in the filtration system shown in FIG. 1. The figure which conceptually showed the flow of the air supplied to the strainer and discharged from the strainer at the time of cleaning process of a strainer filter. FIG. 2 is a side sectional view of the filtration device shown in FIG. 2 for conceptually explaining the cleaning process of the sponge filter. The side sectional view of the filtration device shown in FIG. 3 for conceptually explaining the flow of sewage and purified water in the filtration device when the mesh filter is washed by "backwash 1". The side sectional view of the filtration device shown in FIG. 3 for conceptually explaining the flow of sewage and purified water in the filtration device when the mesh filter is washed by "backwash 2". The side sectional view of the filtration device shown in FIG. 3 for conceptually explaining the flow of sewage and purified water in the filtration device when the mesh filter is washed by "foam washing".

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.
Described in this embodiment is a filtration system. FIG. 1 shows an overall configuration diagram showing a schematic configuration of the filtration system. In FIG. 1, the illustration of the third valve, which will be described later, is omitted.

The filtration system described in this embodiment is for filtering sewage and converting it into purified water that can be discharged into a general environment. The sewage is not particularly limited as long as it is a liquid to be filtered by a filtration device or a filtration system, but in the filtration system of this embodiment, muddy water is the target of filtration.

The filtration system in this embodiment is composed of a plurality of, but not limited to, seven filtration devices 10, 20, 30, 40, 50, 60, and 70 connected in multiple stages from the upstream side in this embodiment. It has become a thing. Generally, the filtration device 10 to the filtration device 70 are intended to filter fine solids in sewage toward the downstream side. In the following description, regarding the flow direction of sewage, purified water, or sewage and purified water, the direction from upstream to downstream is referred to as "forward direction", and the direction from downstream to upstream is referred to as "reverse direction".

The filtration system has a strainer 110 on the upstream side of the filtration device 10 to the filtration device 70, in other words, in the uppermost stream.
The strainer 110 serves as an intake port for taking in sewage, and when used, the strainer 110 is submerged or immersed in a sewage pool (not shown) in which sewage, which is muddy water, is accumulated. The strainer 110 has a function of serving as an intake port for taking in sewage and a function of removing some solid matter in the sewage. The strainer 110 may be a known or well-known strainer, and may be a commercially available strainer.
The strainer 110 includes a hollow case 112 and a strainer filter 111 that covers an opening (not shown) appropriately provided in the case 112. The strainer filter 111 is a filter for removing some solid matter in sewage, for example, a film-like or plate-like filter made of stainless steel mesh. That is, since it has a function of removing some solid matter, it can be said that the strainer 110 is also a filtration device in a broad sense.
Although not limited to this, the strainer filter 111 in this embodiment is made of a stainless steel mesh, and its eye size is, for example, 150 μm.
The strainer 110 is connected to a tube, generally a hose 121, which is a flexible tube. The hose 121 may be known or well-known, and may be commercially available. The hose 121 is connected to the pump 130. At a minimum, the pump 130 is required to have a function of causing the strainer 110 to suck sewage and pulling the sewage sucked by the strainer 110 by applying a negative pressure to the inside of the strainer 110 via the hose 121. .. As long as it is possible, the pump 130 may be known or well known, or may be commercially available. The pump 130 in this embodiment is also capable of sending air to the strainer 110. The reason why the air is sent to the strainer 110 is to clean the strainer filter 111 of the strainer 110 (remove the solid matter clogged in the eyes of the strainer filter 111) as described later. The function of drawing sewage through the strainer 110 and the function of sending air to the strainer 110 do not necessarily have to be achieved by one pump 130, and each of the above two functions is assigned to another pump. It is also possible.
The pump 130 is connected downstream thereof to a pipe, generally a flexible pipe, a hose 122. The length may be different, but the hose 122 may be the same as the hose 121. The hose 122 is for connecting the pump 130 and a connection pipe 91 to be described later connected to the filtration device 10 which is the most upstream filtration device, and connects the sewage drawn from the sewage pool by the pump 130. It has a function of flowing into a pipe 91.

The filtration device 10 is connected to the hose 122 by a connecting pipe 91. As is the case with the connecting pipes 92 to 97 described later, the connecting pipe 91 is a pipe, and is not limited to this, but in this embodiment, it is a metal pipe. For the filtration device 10, the connection pipe 91 corresponds to an inflow pipe for supplying sewage to the container of the filtration device 10 described later. The connecting pipe 91 branches in the middle. The pipe branching from the connecting pipe 91 is a drainage pipe 91Y. As is the case with the drainage pipes 92Y to 97Y described later, the drainage pipe 91Y is a pipe, and is not limited to this, but in this embodiment, it is a metal pipe. As is the case with the drainage pipes 92Y to 97Y described later, the tip of the drainage pipe 91Y is connected to a residue reservoir for collecting the residue generated from the filtration device 10 to the filtration device 70 as described later. However, the residue reservoirs in which the tips of the drainage pipes 91Y to 97Y are connected to each other may or may not be the same.
A valve 91X is provided at the connection portion of the connection pipe 91 with the drain pipe 91Y. The function of the valve 91X will be described later.

The filtration device 10 and the filtration device 20 are connected to each other by a connecting pipe 92. The connection pipe 92 discharges purified water from the container described later of the filtration device 10, and corresponds to an outflow pipe for the filtration device 10, but supplies purified water to the container described later of the filtration device 20. It corresponds to an inflow pipe for the filtration device 20.
The filtration device 20 and the filtration device 30 are connected to each other by a connecting pipe 93. The connection pipe 93 discharges purified water from the container described later of the filtration device 20 and corresponds to an outflow pipe for the filtration device 20, but supplies purified water to the container described later of the filtration device 30. It corresponds to an inflow pipe for the filtration device 30.
The filtration device 30 and the filtration device 40 are connected to each other by a connecting pipe 94. The connection pipe 94 discharges purified water from the container described later of the filtration device 30, and corresponds to an outflow pipe for the filtration device 30, but supplies purified water to the container described later of the filtration device 40. It corresponds to an inflow pipe for the filtration device 40.
The filtration device 40 and the filtration device 50 are connected to each other by a connecting pipe 95. The connection pipe 95 discharges purified water from the container described later of the filtration device 40, and corresponds to an outflow pipe for the filtration device 40, but supplies purified water to the container described later of the filtration device 50. It corresponds to an inflow pipe for the filtration device 50.
The filtration device 50 and the filtration device 60 are connected to each other by a connecting pipe 96. The connection pipe 96 discharges purified water from the container described later of the filtration device 50, and corresponds to an outflow pipe for the filtration device 50, but supplies purified water to the container described later of the filtration device 60. It corresponds to an inflow pipe for the filtration device 60.
The filtration device 60 and the filtration device 70 are connected to each other by a connecting pipe 97. The connection pipe 97 discharges purified water from the container described later of the filtration device 60, and corresponds to an outflow pipe for the filtration device 60, but supplies purified water to the container described later of the filtration device 70. It corresponds to an inflow pipe for the filtration device 70.
An outflow pipe 98 extends from the filtration device 70. The outflow pipe 98 discharges purified water from a container described later in the filtration device 70, and corresponds to an outflow pipe for the filtration device 70. The purified water flowing out of the outflow pipe 70 is clean enough to be discharged into the environment.

The connection pipe 92 is branched from the drain pipe 92Y on the way, and a valve 92X is provided at the connection portion between the connection pipe 92 and the drain pipe 92Y.
The connection pipe 93 is branched from the drain pipe 93Y on the way, and a valve 93X is provided at a connection portion between the connection pipe 93 and the drain pipe 93Y.
The connection pipe 94 is branched from the drain pipe 94Y on the way, and a valve 94X is provided at the connection portion between the connection pipe 94 and the drain pipe 94Y.
The connection pipe 95 is branched from the drain pipe 95Y on the way, and a valve 95X is provided at the connection portion between the connection pipe 95 and the drain pipe 95Y.
The connection pipe 96 is branched from the drain pipe 96Y on the way, and a valve 96X is provided at a connection portion between the connection pipe 96 and the drain pipe 96Y.
The connection pipe 97 is branched from the drain pipe 97Y on the way, and a valve 97X is provided at the connection portion between the connection pipe 97 and the drain pipe 97Y.
The outflow pipe 98 is provided with a valve 98Y.

The functions of the valves 91X to 97X will be described.
The valves 91X to 97X can all take two similar states.
First, the valve 91X will be described.
The valve 91X connects a state in which sewage flows forward from the hose 122 on the upstream side to the filtration device 10 on the downstream side via the connection pipe 91, and the connection pipe 91 on the downstream side of the valve 91X and the drain pipe 91Y. Then, it is possible to take two states, that is, the sewage and the purified water accumulated in the container described later of the filtration device 10 are poured into the drain pipe 91Y.
The valve 92X forwards from the upstream filtration device 10 to the downstream filtration device 20 via the connecting pipe 92 for sewage for the downstream filtration device 20 (which is for the upstream filtration device 10). (The same applies to the following), and the connection pipe 92 on the downstream side of the valve 92X is connected to the drain pipe 92Y, and the sewage and purified water collected in the filtration device 20 are sent to the drain pipe 92Y. It is possible to take two states, the pouring state and the pouring state.
Similar to the valves 91X and 92X, the valves 93X to 97X are connected from the upstream filtration devices 20, 30, 40, 50 and 60 to the downstream filtration devices 30, 40, 50, 60 and 70, respectively. A state in which sewage flows forward for the filtration devices 30, 40, 50, 60, 70 on the downstream side through pipes 93 to 97 (in short, drainage pipes 93 to drainage on the upstream side and downstream side of valves 93X to 97X). (The state in which the pipes 97 are connected to each other), the connection pipes 93 to 97 on the downstream side of the valves 93X to 97X, and the drainage pipes 93Y to 97Y are connected, and the sewage and purified water collected in the filtration devices 30 to 70, respectively. It is possible to take two states, that is, a state in which the water is poured into the drain pipes 93Y to 97Y, respectively.
Of the above-mentioned two states that can be taken by the valves 91X to 97X, the state described above is referred to as the A state, and the state described later is referred to as the B state.
Further, the valves 91X to 97X completely block the connecting pipes 91 to 97 to block the flow of sewage and the like in the forward and reverse directions of the connecting pipes 91 to 97, and are located on the upstream side of the valves 91X to 97X. A state in which the flow of sewage and purified water from the filtration device 10 to the filtration device 60 to the drain pipes 91Y to 97Y is also blocked (in short, a state in which all the flow of sewage or purified water between all the pipes connected to the valves 91X to 97 is prohibited. ) May be taken. This is not always the case, but the valves 91X to 97Y do. This state that the valves 91X to 97X can take is referred to as a C state.
As described above, in this embodiment, the valves 91X to 97X can take any of the three states of the A state, the B state, and the C state. However, as will be described later, there are cases where at least one of the above-mentioned states of the valves 91X to 97X is not required. With respect to the valves 91X to 97X, there is no problem even if the unnecessary state cannot be taken.
On the other hand, the valve 98X is capable of taking two states. The valve 98X has two states, one is a state in which the purified water flowing out from the filtering device 70 is allowed to flow in the forward direction in the connecting pipe 98 connected to the filtering device 70, and the other is a state in which the purified water is prohibited from flowing in the forward direction. Can be taken.

Next, the filtration device 10 to the filtration device 70 will be described.
Of the filtration devices 10 to 70, in this embodiment, only the filtration device 10 located at the uppermost stream is a filtration device provided with a sponge filter. However, it is not necessary that the filtration device provided with the sponge filter is located at the uppermost stream of the filtration devices 10 to 70 in which the filtration devices are connected in multiple stages. Further, a plurality of filtration devices provided with a sponge filter may exist in the filtration devices 10 to 70 connected in multiple stages.

The configuration of the filtration device 10 will be described with reference to FIG.
If the filtration device 10 is provided with a sponge filter as a filter medium, the other configurations can be the same as those of the conventional filtration device except that a cleaning tube described later is connected. ..
The filtration device 10 includes a container 11. The container 11 may be the same as that provided in the conventional filtration device. The container 11 is a watertight and airtight case having a pressure resistance that can withstand a certain amount of internal pressure. The container 11 can be made entirely of metal. Alternatively, at least a part of the container 11 may be made of a transparent material (for example, glass or resin) so that the state of the sponge filter inside the container 11 can be visually observed.
The container 11 is vertically long in this embodiment, but is not limited to this. The shape of the container 11 can be, for example, a cylindrical shape having a vertical axis or a conical trapezoidal shape. Although not limited to this, the shape of the container 11 in this embodiment is a conical trapezoid that narrows slightly upward.

The downstream side of the connecting pipe 91 and the upstream side of the connecting pipe 92 are connected to the container 11, respectively. As described above, the connecting pipe 91 is an inflow pipe for the filtration device 10, and the connection pipe 92 is an outflow pipe for the filtration device 10. The downstream side of the connecting pipe 91 is connected to the lower side of the container 11, but not limited to this, to the lower end of the container 11 in this embodiment. The connection pipe 91 may be connected to the lower surface (bottom) of the container 11. Similarly, but not limited to, the upstream side of the connecting pipe 92 is connected to the lower side of the container 11, and in this embodiment, to the lower end of the container 11. The upstream side of the connecting pipe 92 is connected to the intake pipe 13 extending to the inside of the container 10. The water intake pipe 13 bends upward inside the container 11 and extends coaxially upward with the container 11. A large number of intake holes 13X, which are holes, are formed in a certain area above the intake pipe 13. The water intake hole 13X is a hole for taking in purified water generated by the sewage passing through the sponge filter when the filtration device 10 filters the sewage into the water pipe 13.
In this embodiment, the water intake pipe 13 extends to the upper part of the container 11, more specifically, but not limited to, the upper surface of the container 11, and extends outward from the upper surface of the container 11 at the upper surface of the container 11. It is connected to the cleaning pipe 14. The cleaning pipe 14 extends toward the residue reservoir. The residue reservoir referred to here may or may not be the same as the residue reservoir described above. An auxiliary valve 14X, which is a valve, is attached to the cleaning pipe 14. The auxiliary valve 14X can select two states, a state in which sewage and purified water can pass through the cleaning pipe 14, and a state in which it cannot pass through. The connecting pipe 92, the intake pipe 13, and the cleaning pipe 14 may be a series of pipes. On the other hand, the intake pipe 13 and the cleaning pipe 14 do not necessarily have to be connected, and in that case, the upper end of the intake pipe 13 does not have to extend to the uppermost portion of the container 11. Even when the water intake pipe 13 and the cleaning pipe 14 are not connected, the connection position between the cleaning pipe 14 and the container 11 is higher than the connection position between the container 11 and the downstream side of the connection pipe 91. Should be located in. For example, the connection position of the cleaning pipe 14 with respect to the container may be the upper end or the upper surface of the container 11.

A sponge filter 12 is arranged in the container 11. The sponge filter 12 filters the sewage that has flowed in from the connecting pipe 91 that is the inflow pipe, and purifies the water that flows out from the connecting pipe 92 that is the outflow pipe. The sponge filter 12 exits the connecting pipe 92 so that when the filtration device 10 filters the sewage, the sewage flowing in from the connecting pipe 91 becomes purified water from the connecting pipe 92 and covers the entire path outflowing. It is necessary that the purified water is shaped so as to pass through the sponge filter 12, and it is sufficient if the conditions are satisfied. Although not limited to this, the sponge filter 12 in this embodiment is annular when viewed in a plan view. Although not limited to this, the annular sponge filter 12 is the entire space inside the container 11 above a predetermined height below the range where the intake hole 13X of the intake pipe 13 exists. The shape is such that it occupies a space (however, the space occupied by the intake pipe 13 is excluded). Since the range occupied by the sponge filter 12 is such, the sewage flowing from the connecting pipe 91 does not reach the intake hole 13X of the intake pipe 13 unless it passes through the sponge filter 12. Therefore, only the purified water generated by the sewage passing through the sponge filter 12 is taken into the intake pipe 13 from the intake hole 13X. However, the shape of the sponge filter 12 is not limited to this. For example, if the entire inner peripheral surface of the annular sponge filter 12 is in contact with the outer peripheral surface of the intake pipe 13, there is a gap between the outer surface of the sponge filter 12 and the inner surface of the container 11. It doesn't matter if it is vacant.
The sponge filter 12 is a filter made of a flexible sponge (porous structure). The flexibility required for the sponge filter 12 is such that it shrinks or expands due to a change in water pressure generated in the container 11 when the sponge filter 12 of the filtration device 10 is washed, as will be described later. ..

Next, the configurations of the filtration device 20 to the filtration device 60 will be described.
The filtration device 20 to the filtration device 60 adopt the same configuration as the filtration device 10 except that the filter medium is not a sponge filter. However, the filtration device 20 to 60 may be different from the filtration device 10 in a portion other than the filter medium. For example, the shapes and sizes of the containers may be different between the filtration devices 20 to 60 and the filtration devices 10, and the shapes of the filter media may be different.

First, the filtration devices 20 and 30 will be described. Although not limited to this, the configurations of the filtration devices 20 and 30 may all be the same as those of the filtration device 10 except for the filter medium, and the configuration of the filtration devices 20 and 30 is not limited to this, but in this embodiment, FIG. As shown, it is. The wavy hatching in FIG. 3 indicates a portion where sewage or purified water is present.
The filtration devices 20 and 30 have components having the same configurations and functions as the container 11, the intake pipe 13 having the intake hole 13X, and the cleaning pipe 14 having the auxiliary valve 14X, which are provided in the filtration device 10. .. In FIG. 3 showing the filtration devices 20 and 30, each component having the same reference numeral in the 10s as the component included in the filtration device 10 is designated by the reference numeral in the 20s for the filtration device 20. 30 is indicated by a reference numeral in the 30s.
In the filtration device 20, the one connected to the container 21 is the downstream side of the connecting pipe 92, and the one connected to the lower end of the intake pipe 23 is the upstream side of the connecting pipe 93.
In the filtration device 30, it is the downstream side of the connecting pipe 93 that is connected to the container 31, and the upstream side of the connecting pipe 94 that is connected to the lower end of the intake pipe 33.
The filter medium in the filtration devices 20 and 30 may be basically any. Although not limited to this, the filter media in the filtration devices 20 and 30 in this embodiment are mesh filters 22 and 32 which are film-shaped or plate-shaped filters made of stainless steel mesh. However, the mesh filters 22 and 32 do not necessarily have to be made of stainless steel.
As shown in FIG. 3, the mesh filters 22 and 32 are arranged horizontally, but not limited to, inside the containers 21 and 31, except for the portion where the intake pipes 23 and 33 are present. It covers the entire range of the horizontal sections 21 and 31. The height position where the mesh filters 22 and 32 are present is somewhere above the downstream side of the connecting pipes 92 and 93 and below the range where the intake holes 23X and 33X of the intake pipes 23 and 33 are present. Is. Since the mesh filters 22 and 32 exist at such positions and their existence range is as described above, the sewage that has entered the containers 21 and 31 from the connecting pipes 92 and 93 does not pass through the mesh filters 22 and 32. , The inside of the intake pipes 23 and 33 cannot be reached. A plurality of mesh filters 22 and 32, for example, about three may be superposed.
The size of the mesh filter 22 and the size of the mesh filter 32 are generally larger in the former case. For example, the mesh size of the mesh filter 22 is 100 μm, and the mesh size of the mesh filter 23 is 50 μm, for example.
The mesh filters 22 and 32 do not need to be arranged horizontally. When one or more mesh filters 22 and 32 are viewed in a plan view in a container 11 having a conical trapezoidal shape or a cylindrical shape, for example, an intake pipe 23 whose central axis coincides with the central axis of the container 11. , 33 may be arranged so as to surround the vertical portion in a circle (in the case of a plurality of mesh filters 22 and 32, concentrically around the intake pipes 23 and 33). That is, the mesh filters 22 and 32 are arranged in the container in a state where the rectangular mesh filters 22 and 32 are rolled into a cylindrical shape. In this case, the height of the container 11 over the entire length of the mesh filters 22 and 23 when viewed in a plan view, except for the range corresponding to the cross section of the horizontal portion of the intake pipe 13 through which the mesh filters 22 and 32 penetrate. If it exists over the entire length in the direction, the sewage that has entered the containers 21 and 31 from the connecting pipes 92 and 93 cannot reach the inside of the intake pipes 23 and 33 unless it passes through the mesh filters 22 and 32.
Although not limited to this, the filtration devices 20 and 30 of this embodiment have a configuration not found in the other filtration devices 10, 40 to 70. It is an air supply pipe 25, 35. The tips of the air supply pipes 25 and 35 are connected to the downstream side of the valves 92X and 93X in the connection pipes 92 and 93 to which the downstream side thereof is connected to the containers 21 and 31. The base ends of the air supply pipes 25 and 35 are connected to an air supply device (for example, a known or well-known air pump) (for example, a known or well-known air pump) (not shown). The air supply pipes 25 and 35 are for sending the air supplied from the air supply device to the inside of the containers 21 and 31, preferably near the bottom of the containers 21 and 31. The air supply pipes 25 and 35 may be directly connected to the containers 21 and 31 as long as air can be sent into the containers 21 and 31. If air is supplied near the bottom of the containers 21 and 31, the tips of the air supply pipes 25 and 35 should be connected to the bottom or bottom of the containers 21 and 31.

Although not shown, the configurations of the filtration devices 40 to 60 follow the configurations of the filtration devices 10 to 30.
In this embodiment, the only difference between the filtration devices 40 to 60 and the filtration device 10 is the difference in the filter media. The filtration devices 40 to 60 are connected to cleaning pipes 44, 54, 64 having auxiliary valves 44X, 54X, 64X, respectively, but none of them may be used.
The filter medium in the filtration device 40 to the filtration device 60 is, for example, a filter premised on replacement, for example, a resin filter made of a resin (for example, acrylonitrile resin or polypropylene resin). The resin filter may have an annular shape (cylindrical shape) in a plan view like the sponge filter 12 in the filtration device 10, or as an example of the shapes of the mesh filters 22 and 32 in the filtration devices 20 and 30, as described above. It may be in the form of a film or a plate, and may be arranged in a circular shape in a plan view, for example, horizontally or in a state of being rolled into a cylinder. In any case, the sewage flowing into the filtration devices 40 to 60 always passes through the resin filter to be purified water, and if so, the resin filter is sufficient.
The resin filters in the filtration devices 40 to 60 are generally such that smaller solids can be filtered as they are downstream. The size of the solid matter that can be filtered out by the resin filter used in the filtration devices 40 to 60 is, for example, 5 μm in the filtration device 40 and 0.5 μm in the filtration devices 50 and 60.

The filtration device 70 is a filtration device for performing so-called microfiltration, but not limited to this. For example, the filtration device 70 may be a known or well-known filtration device using a hollow fiber membrane as a filter medium, and this is the case in this embodiment.
The size of the solid matter that can be filtered by the filtration device 70 is, for example, 0.01 μm.

The usage and operation of the filtration system described above will be described.
In the filtration system, the sewage (muddy water) taken from the sewage pool is filtered, and the purified water is discharged from the filtration device 70 through the outflow pipe 98 (normal time), and the strainer filter 111 of the strainer 110 is washed. , The case of cleaning the sponge filter 12 of the filtration device 10, and the case of cleaning the mesh filters 22 and 32 of the filtration devices 20 and 30 will be mainly described.

<Normal time>
Normally, the muddy water taken from the sewage pool is filtered, and purified water is discharged from the filtration device 70.
First, the pump 130 is driven and a negative pressure is applied to the inside of the strainer 110 via the hose 121. Then, the sewage is taken into the case 112 of the strainer 110 through the strainer filter 111. The strainer filter 111 removes some solid matter in the sewage. The strainer filter 111 becomes dirty due to this, and eventually becomes clogged.
The sewage reaches the pump 130 from the strainer 110 via the hose 121, and reaches the upstream side of the connecting pipe 91 from the pump 130 via the hose 122.

At this time, all the valves 91X to 97X are in the A state, and the valve 98X is in a state of allowing the purified water flowing out from the filtration device 70 to flow in the forward direction in the connecting pipe 98. That is, in all of the connecting pipes 91 to 98 from the most upstream to the most downstream, forward flow of purified water or sewage is permitted.
At this time, the auxiliary valves 14X, 24X, 34X, 44X, 55X, 66X are all in a state where sewage and purified water cannot pass through the cleaning pipes 14, 24, 34, 44, 54, 64. Therefore, sewage and purified water do not flow out from the cleaning pipes 14, 24, 34, 44, 54, 64, which are connected to the filtration devices 10 to 60, respectively.

The sewage that has entered the container 11 of the filtration device 10 from the connection pipe 91 passes through the sponge filter 12 and becomes purified water. At this time, the solid matter in the sewage is filtered out by the sponge filter 12. The sponge filter 12 becomes dirty due to this, and eventually becomes clogged. The purified water enters the intake pipe 13 through the intake hole 13X of the intake pipe 13 existing along the axis of the sponge filter 12, and flows into the connection pipe 92 connected at the downstream end of the intake pipe 13. The flow direction (direction in which water pressure is applied) of sewage and purified water in the above filtration device 10 is roughly indicated by an arrow in FIG.
Then, the purified water passes through the connecting pipe 92 in the forward direction and flows into the filtration device 20.

In the filtration device 20, substantially the same thing as that done in the filtration device 10 is repeated.
The sewage that has entered the container 21 of the filtration device 20 from the connection pipe 92 passes through the mesh filter 22 and becomes purified water. At this time, the solid matter in the sewage is filtered out by the mesh filter 22. As a result, the mesh filter 22 becomes dirty and eventually becomes clogged. The purified water enters the intake pipe 23 through the intake hole 23X of the intake pipe 23 and flows into the connection pipe 93 connected at the downstream end of the intake pipe 23. The flow direction (direction in which water pressure is applied) of sewage and purified water in the above filtration device 20 is roughly indicated by an arrow in FIG. By the way, this arrow is also valid when the filtration device 30 filters the sewage.
Then, the purified water passes through the connecting pipe 93 in the forward direction and flows into the filtration device 30.
Similarly, the sewage that has entered the filtration device 30 from the connection pipe 93 is filtered there and flows into the connection pipe 94 as purified water, and the sewage that has entered the filtration device 40 from the connection pipe 94 is filtered there and becomes purified water for connection. The sewage that flows into the pipe 95 and enters the filtration device 50 from the connection pipe 95 is filtered there and flows into the connection pipe 96 as purified water, and the sewage that enters the filtration device 60 from the connection pipe 96 is filtered there and becomes purified water. And flows into the connecting pipe 97, and the sewage that has entered the filtering device 70 from the connecting pipe 97 is filtered there and becomes purified water and flows into the outflow pipe 98.
As a result, purified water flows out from the downstream end of the outflow pipe 98. Purified water is released into the environment, for example, into rivers. The purified water released is clean enough to be released into the environment.
In normal times, the pump 130 is usually driven continuously. As a result, a series of forward water pressures are applied to the sewage and purified water existing between the strainer 110 and the outflow pipe 98. However, the pump 130 may be driven in batch.

<Cleaning of strainer filter 111 of strainer 110>
As described above, if the normal processing is continued to some extent, the strainer filter 111 of the strainer 110 becomes dirty and eventually becomes clogged. Therefore, it is necessary to clean the strainer filter 111.
In this embodiment, the strainer filter 111 is washed as follows.
As described above, the pump 130 is connected to the strainer 110 via the hose 121. Normally, the hose 121 functions to carry sewage from the strainer 110 to the pump 130.
When cleaning the strainer 110, air is sent from the pump 130 to the strainer 110. When air is sent, the strainer 110 remains submerged or submerged in a sewage pool.
When air is sent to the strainer 110 in this state, air flows out from the inside of the strainer 110 through the strainer filter 111. The direction of air flow at that time is shown in FIG. The outflowing air is given a momentum to the extent that dirt attached to the strainer filter 111 is blown away. That is, the air pressure in the case 112 of the strainer 110 needs to be increased to some extent. By doing so, when the air flows out from the strainer filter 111 into the sewage, the air intermittently increases its momentum and flows out so as to repeat a small explosion. As a result, dirt on the strainer filter 111 is efficiently removed.
Sudden outflow of air from the strainer filter 111 in a state such as a small explosion often occurs when the strainer filter 111 has a certain degree of fine mesh. An outflow of air such as an explosion generally occurs when the strainer filter 111 has a mesh size of 500 μm or less, and almost certainly occurs when the strainer filter 111 has a mesh size of 200 μm or less. The strainer filter 111 of this embodiment is selected from such a range, but is not limited to 150 μm.
Further, it is preferable that the air is sent into the case 112 of the strainer 110 continuously to some extent so that the air pressure in the case 112 is kept high to some extent for a while, for example, for a few minutes. Thereby, a small explosion as described above due to the outflow of air from the strainer 110 can be promoted.
After cleaning the strainer 110, the pump 130 stops sending air to the strainer 110. However, even if a negative pressure is applied to the hose 121 by the pump 130 as it is, high-pressure air is accumulated in the case 112 of the strainer 110, so that sewage cannot be drawn well. In order to prevent such a problem, it is advisable to reduce the air pressure in the case 112 and the hose 121 of the strainer 110. For example, since it may take about 1 second, if the connection between the hose 121 and the pump 130 is disconnected, the air pressure in the case 112 and the hose 121 of the strainer 110 will be lowered to the extent that the above-mentioned problems do not occur.
Of course, the process for reducing the air pressure in the case 112 and the hose 121 of the strainer 110 is not limited to disconnecting the hose 121 and the pump 130. For example, a branch pipe may be connected to the hose 121, and the air pressure in the case 112 of the hose 121 and the strainer 110 may be lowered by opening the tip of the branch pipe.
After reducing the air pressure in the case 112 of the hose 121 and the strainer 110, for example, the process returns to normal processing.

<When cleaning the sponge filter 12 of the filtration device 10>
If the normal treatment is continued to some extent, the sponge filter 12 of the filtration device 10 becomes dirty and eventually becomes clogged. Therefore, it is necessary to clean the sponge filter 12.
In this embodiment, the sponge filter 12 is washed as follows.
When cleaning the sponge filter 12, the valve 92X of the connecting pipe 92 located on the downstream side of the filtration device 10 is set to the B state or the C state. When the valve 92X is in the B state, sewage and purified water collected in the filtration device 20 connected to the downstream side of the filtration device 10 via the connecting pipe 92 (sewage will come out first, and only sewage will come out. It may not come. In the same case in the present application, it is the same.) Is in a state of flowing into the drain pipe 92B. At this time, the portion of the connecting pipe 92 on the filtration device 10 side of the valve 92X is not connected to the portion of the connecting pipe 92 on the filtration device 20 side of the valve 92X or the drain pipe 92Y. Seen from 10, the connecting pipe 92 is in a closed state. Further, when the valve 92X is in the C state, the connecting pipe 92 is completely shut off at the portion of the valve 92X, so that the connecting pipe 92 is in a closed state when viewed from the filtration device 10.
That is, by setting the valve 92X in the B state or the C state, the connection pipe 92, which is an outflow pipe for the filtration device 10, is in a closed state when viewed from the filtration device 10.
On the other hand, in this state, the process of alternately setting the valve 91X on the upstream side of the filtration device 10, that is, the connection pipe 91 which is the inflow pipe for the filtration device 10, into the A state and the B state is repeated a plurality of times. When the valve 91X is in the A state, sewage flows forward from the hose 122 on the upstream side to the filtration device 10 on the downstream side via the connecting pipe 91. When the valve 91X is in the B state, the connection pipe 91 on the downstream side of the valve 91X and the drain pipe 91Y are connected, and the sewage and purified water collected in the container 11 of the filtration device 10 are guided to the drain pipe 91Y. ..
While the A state and the B state are repeated a plurality of times, the pump 130 is continuously driven so that the sewage in the connecting pipe 91 is continuously subjected to the forward pressure. At least, when the valve 91X is in the A state, it is necessary that a forward pressure is applied to the sewage in the connecting pipe 91.
The repeated A state and B state in the valve 91X may be started from either of them, but if the sponge filter 12 of the filtration device 10 is washed after the normal processing, it starts from the A state. Would be normal.
In the valve 91X, the A state and the B state may be alternately performed, for example, for about 2 to 3 seconds each. As will be described later, the sewage and purified water sent from the drainage pipe 91Y to the outside, for example, the residue reservoir may be visually inspected, and the A state and the B state may be repeated until they are cleaned to some extent.
Switching between the A state and the B state of the valve 91X may be repeated, for example, 10 times or more. Then, the cleaning effect of the sponge filter 12 is improved.
The alternate switching between the A state and the B state of the valve 91X may be performed by manually operating the valve 91X. On the other hand, the above-mentioned alternating switching of the valve 91X may be realized by a control device (not shown) for causing the valve 91X to automatically switch between the A state and the B state. According to this, it is possible to save the trouble of having to manually and repeatedly switch the valve 91X between the A state and the B state. The above-mentioned control device is a drive device capable of both setting the valve 91X in the A state to the B state and the valve 91X in the B state to the A state (one drive device may be used, but the above-mentioned control device). It may be two in which each of the two operations is allocated.) And, for example, a computer device for outputting data or a signal for the driving device to repeatedly execute the above two operations to the driving device. If so, those skilled in the art will be able to easily create it.
The control device may automatically execute not only the control of the valve 91X when cleaning the sponge filter 12 but also the control of putting the valve 92X into the B state or the C state. Further, the control device operates the auxiliary valve 14X, which may be performed when cleaning the sponge filter 12, so that the sewage and purified water from the container 11 can pass through the cleaning pipe 14. However, it may be automatically executed.

The flow direction (direction in which water pressure is applied) of sewage and purified water in the filtration device 10 when the valve 91X is in the A state is roughly indicated by an arrow in FIG. 5 (A). Further, the flow direction (direction in which water pressure is applied) of sewage and purified water in the filtration device 10 when the valve 91X is in the B state is roughly indicated by an arrow in FIG. 5 (B). It should be noted that both FIGS. 5A and 5B are views in the case where the auxiliary valve 14X is in a state where sewage and purified water can pass through the cleaning pipe 14, as will be described later.
As shown in FIG. 5A, when the valve 91X is in the A state, water pressure in the forward direction acts on the sewage in the connecting pipe 91, which is the inflow pipe for the filtration device 10, for example, from the pump 130. This water pressure extends from the connecting pipe 91 to the inside of the container 11 of the filtration device 10. As a result, when the valve 91X is in the A state, the water pressure applied to the sewage and purified water in the container 11 increases. As a result, the sponge filter 12 shrinks its volume.
On the other hand, as shown in FIG. 5B, when the valve 91X is in the B state, the sewage and purified water in the container 11 of the filtering device 10 are the sewage and purified water collected in the container 11 of the filtering device 10. It is guided from the connecting pipe 91 on the downstream side of the 91X to the drain pipe 91Y via the valve 91X. That is, since the sewage and purified water in the container 11 are reduced, the water pressure in the container 11 is lowered. As a result, the sponge filter 12 expands its volume.
In this way, the sponge filter 12 contracts and expands as the water pressure rises and falls. Due to such dynamic movement of the sponge filter 12, the solid stains (residues) adhering to the sponge filter 12 are better than those obtained by the conventional backwashing, and are separated from the sponge filter 12. Then, it is sent from the drain pipe 91Y to an external, for example, a residue reservoir together with the sewage and purified water.

By the way, in this embodiment, although it is not always necessary, when the valve 91X is made to repeat the A state and the B state, the auxiliary valve 14X provided in the cleaning pipe 14 connected to the container 11 of the filtration device 10 is used. It is opened so as to maintain a state in which the sewage and purified water accumulated in the container 11 are allowed to flow out of the container 11 through the cleaning pipe 14.
By doing so, both when the valve 91X is in the A state and sewage flows into the container 10 from the connection pipe 91 and when the valve 91X is in the B state and the sewage and purified water flow out from the container 11 to the drain pipe 91Y, for cleaning. Sewage and purified water will flow out from the pipe 14. At that time, a state in which sewage and purified water and air are mixed in the container 11 occurs, and a force acts on the sewage and purified water in the container 11 in different directions of the cleaning pipe 14 and the connecting pipe 91. When the 91X is in the A state or the B state, sudden sewage and purified water are likely to jump out from the cleaning pipe 14. As a result, the above-mentioned dynamic motion of the sponge filter 12 becomes larger, so that the dirt adhering to the sponge filter 12 is more easily separated from the sponge filter 12.

After cleaning the sponge filter 12, for example, both the valve 91X and the valve 92X are returned to the A state. Doing so will allow the filtration system to perform normal processing, or at least prepare for it.
As the cleaning of the sponge filter 12, it is also possible to perform backwashing (treatments of backwashing 1 and 2) described later. Naturally, the backwashing process and the cleaning process of the sponge filter 12 described above are not performed at the same time.

<When cleaning the mesh filters 22 and 32 of the filtration devices 20 and 30>
If the normal processing is continued to some extent, dirt accumulates on the mesh filters 22 and 32 of the filtration devices 20 and 30, and eventually clogging occurs. Therefore, it is necessary to clean the mesh filters 22 and 23. Since the cleaning of the mesh filter 22 in the filtration device 20 and the cleaning of the mesh filter 32 in the filtration device 30 are substantially the same processing, the processing of cleaning the mesh filter 22 in the filtration device 20 will be described.
In this embodiment, there are three types of cleaning processes for the mesh filter 22. There are two backwashing treatments (hereinafter referred to as "backwashing 1 treatment" and "backwashing 2 treatment", respectively) and a treatment using air (hereinafter referred to as "foam washing treatment"). It is called.). These three processes will be described in order.

(Treatment of backwash 1)
The treatment of backwash 1 is not so different from the prior art.
When the backwash 1 process is executed, the valve 93X provided in the connecting pipe 93 connected to the downstream side of the filtration device 20 is set to the A state. Further, the valve 92X provided in the connecting pipe 92 connected to the upstream side of the filtration device 20 is set to the B state.
The auxiliary valve 24X of the cleaning pipe 24 connected to the upper surface of the container 21 is in an open state, that is, the sewage and purified water accumulated in the container 21 flow out of the container 21 through the cleaning pipe 24. However, even if it is in a closed state, that is, a state in which sewage and purified water accumulated in the container 21 are not allowed to flow out of the container 21 through the cleaning pipe 24. good.

In this state, the valve 92X originally located on the upstream side of the filtration device 20 is in the B state, that is, the connection pipe 92 and the drainage pipe 92Y on the downstream side of the valve 92X are connected to the inside of the filtration device 20. Since the sewage and purified water collected in the drain pipe 92Y are poured into the drain pipe 92Y, the sewage and purified water collected in the container 21 flow out from the drain pipe 92Y and head toward the residual reservoir.
On the other hand, the valve 93X, which is normally located on the downstream side of the filtration device 20, is in the A state, that is, from the filtration device 20 on the upstream side to the filtration device 30 on the downstream side in the forward direction via the connecting pipe 93. When the sewage for the filtration device 30 on the downstream side is allowed to flow, the flow of water in the connecting pipe 93 is directed in the opposite direction. This is because the valve 93X is in the A state when it is clogged, the connection pipes 93 are connected on both sides of the valve 93X, and the sewage and purified water in the filtration device 20 are upstream as described above. This is because the water is gradually discharged from the drain pipe 92Y on the side, and the water pressure in the forward direction from the filtration device 20 to the filtration device 30 does not work in the connection pipe 93. On the other hand, since a large amount of sewage and purified water are accumulated in the container 31 of the filtration device 30 on the downstream side of the filtration device 20, when the water level in the container 31 exceeds the water level of the container 21 of the filtration device 20. Since the sewage and purified water collected in the container 31 of the filtration device 30 tend to flow toward the filtration device 20, water pressure in the opposite direction acts in the connection pipe 93. This phenomenon becomes more remarkable, for example, when the valve 94X further downstream of the filtration device 30 is put into the B state or the C state.
Then, as shown in FIG. 6, the directions of the flow or water pressure of the sewage and purified water in the filtration device 20 are opposite to those in the normal state (see FIG. 3).

In short, in the treatment of the backwash 1, when the auxiliary valve 24X of the cleaning pipe 24 is closed, the flow or the direction of the water pressure of the sewage and purified water in the filtration device 20 is those in the normal state. It is completely opposite to the orientation. The mesh filter 22 is subjected to water pressure from purified water in a direction opposite to that in the normal state toward sewage. This is a state equivalent to performing so-called general backwashing.
When a state equivalent to that of general backwashing occurs, sewage and purified water from the filtration device 30 may flow back into the filtration device 20, and the sewage and the sewage in the container 21 of the filtration device 20 may occur. The purified water will be further discharged from the drain pipe 92Y to the residue reservoir. By passing the purified water through the mesh filter 22 in the opposite direction, the dirt adhering to the mesh filter 22 is removed.

On the other hand, when the auxiliary valve 24X of the cleaning pipe 24 is opened, the sewage and purified water collected in the container 21 of the filtration device 20 flow out to the external residue reservoir through the cleaning pipe 24. Cannot be forbidden. Therefore, a part of the sewage and purified water collected in the container 21 of the filtration device 20 flows out to the external residue reservoir through the cleaning pipe 24.

(Treatment of backwash 2)
The treatment of the backwash 2 is similar to the treatment of the backwash 1, but the valve 92X is in the B state in that the valve 92X provided in the connecting pipe 92 connected to the upstream side of the filtration device 20 is in the C state. It is different from the treatment of backwash 1. When the valve 92X is in the C state, the connection pipe 92 on the upstream side of the valve 92X, the connection pipe 92 on the downstream side of the valve 92X, and the drainage pipe 92Y are cut off from each other at the portion of the valve 92X.
On the other hand, the auxiliary valve 24X of the cleaning pipe 24 connected to the upper surface of the container 21 is in an open state.

Even in this state, as in the case of the backwash 1, a flow of sewage and purified water in the opposite direction from the filtration device 30 to the filtration device 20 occurs inside the connection pipe 93.
However, since the valve 92X is in the C state, the sewage and purified water collected in the container 21 of the filtration device 20 may flow out from the container 21 through the connection pipe 92 or the drain pipe 92Y on the upstream side of the filtration device 20. do not have.
Therefore, the sewage and purified water collected in the container 21 of the filtration device 20 may have the auxiliary valve 24X opened, and go to the residue storage through the cleaning pipe 24. The flow of sewage and purified water generated in the container 21 at this time, or the direction of the water pressure acting on the sewage and purified water is shown by an arrow in FIG.
At this time, inside the container 21 of the filtration device 20, the dirt adhering to the mesh filter 22 is well separated from the mesh filter 22.
The solid residue separated from the mesh filter 22 passes through the cleaning pipe 24 and heads for the residue reservoir in a state of being contained in sewage and purified water.

(Foam cleaning process)
When the foam cleaning process is executed, the valve 93X provided in the connecting pipe 93 connected to the downstream side of the filtration device 20 is set to the C state. Further, the valve 92X provided in the connecting pipe 92 connected to the upstream side of the filtration device 20 is in the B state or the C state.
In this state, the sewage or purified water collected in the container 21 of the filtration device 20 cannot flow out from either the connecting pipe 92 or the connecting pipe 93, and the container 21 has either the connecting pipe 92 or the connecting pipe 93. Therefore, neither sewage nor purified water will flow in.
That is, when the bubbles are supplied, no flow occurs in the sewage and purified water in the filtration device 20, and the pressure in a specific direction does not work. This makes it possible to avoid the phenomenon that the air bubbles become smaller due to the increase in the water pressure applied to the sewage and the purified water in the filtration device 20. When the air bubbles become smaller, the effect of cleaning the mesh filter 22 by the bubbles becomes smaller, so that it is a great advantage to avoid the phenomenon that the bubbles become smaller. As a measure for reducing the pressure acting on the sewage and purified water in the filtration device 20, it is conceivable to open an opening provided in the container located higher than the water surface of the sewage or purified water. In this embodiment, the purpose can be achieved by opening the auxiliary valve 24X and putting the cleaning pipe 24 in a communicating state. When the cleaning pipe 24 is in a communicating state, the air pressure of the air in the upper part of the container 21 drops to the normal pressure, so that the water pressure of the sewage and the purified water in the container 21 naturally decreases. As a result, it is possible to avoid a situation in which the foam becomes smaller and the effect of foam cleaning is reduced.
In this state, air is supplied from the air supply pipe 25 into the container 21. The supply of air from the air supply pipe 25 into the container 21 is such that a large number of air bubbles are generated in the sewage and purified water collected in the container 21. Bubbles should be generated from the bottom of the container 21 as much as possible, for example, if the mesh filter is horizontal, at least from below the mesh filter 22. By doing so, the area of the mesh filter 22 exposed to the bubbles becomes large.
Further, even if the mesh filter 22 is circular or concentric around the vertical portion of the intake pipe 23 when viewed in a plan view, bubbles should be generated from the lower part of the container 21 as much as possible. Is. In this case, as described above, the mesh filter 22 covers the entire area in the height direction of the container 21, but it is natural that the bubbles rise from the bottom to the top in the sewage or purified water. This is because the area of the mesh filter 22 exposed to bubbles increases and the amount of bubbles in contact with the mesh filter 22 per unit area increases as the location where the above is generated is on the lower side of the container 21. The range in which the air bubbles should be supplied in the container 21 (the place where the bubbles start to move in the container 21) is preferably the range of 1/5 below the depth of the container 21. In this embodiment, air bubbles are supplied from the air supply pipe 25 to the inside of the connecting pipe 92, and air bubbles are supplied from the connecting pipe 92 to the inside of the container 21. The foam when it reaches the inside of the container 21 is located in the lower 1/5 of the depth of the container 21, but in this embodiment, it is generally located in the lower 1/10.
In any case, when the mesh filter 22 is exposed to bubbles, the bubbles adhere to or pass through the mesh filter 22. As a result, for example, due to friction caused by bubbles, dirt adhering to the mesh filter 22 is separated from the mesh filter 22. This effect is hidden in the case of the resin filter, the fiber filter, and the sponge filter, and becomes remarkable when the filter is the mesh filter 22. This is because if the mesh filter 22 has the property that bubbles do not easily penetrate into the inside of the filter, for example, the sponge filter, but the surface of the filter is the most adhered to the dirt, the surface of the mesh filter 22 is the bubbles. It is considered that the effect of removing stains is well exerted only by stimulating the foam.
The effect of removing stains by bubbles is particularly remarkable when the mesh filter 22 is made of metal, for example, stainless steel. It seems that this is because when the mesh filter 22 is made of metal, dirt adheres only to the surface of the mesh filter 22.
The dirt, which is a solid substance separated from the mesh filter 22, can be discharged from the drain pipe 92Y to the residue reservoir together with the sewage and purified water, for example, by setting the valve 92X to the B state.
When the air is continuously supplied by the air supply pipe 25 for a certain period of time of about 2 to 3 minutes, the cleaning effect of the mesh filter 22 is high and it is easy to obtain.

<Others>
In this embodiment, the filters included in the filtration devices 40 to 70 are not washed. However, this is not the case. For example, the conventional backwashing may be performed by these filtration devices 40 to 70.

10, 20, 30, 40, 50, 60, 70 Filtering device 11, 21, 31 Container 12 Sponge filter 13, 23, 33 Intake pipe 14, 24, 34 Cleaning pipe 14X, 24X, 34X Auxiliary valve 22, 32 mesh Filter 25, 35 Air supply pipe 91-97 Connection pipe 98 Outflow pipe 91X-98X Valve 91Y-97Y Drain pipe 98Y Outflow pipe 110 Strainer 111 Strainer filter 121, 122 Hose 130 Pump

Claims (11)

A container, an inflow pipe which is a pipe connected to the container for inflowing sewage containing impurities into the container, and an outflow pipe which is a pipe connected to the container for discharging purified water from the container. In a filtration device having a mesh filter, which is a mesh-like filter, arranged in the container so that sewage from the inflow pipe to the outflow pipe always passes through the container. A method for cleaning a mesh filter that removes dirt adhering to the mesh filter.
At the time of cleaning the mesh filter, air bubbles are supplied into the sewage or purified water in the container, and at least a part of the mesh filter is exposed to the bubbles.
How to clean the mesh filter. When supplying the sewage in the container or the foam into the purified water, the sewage is supplied to the container from the inflow pipe and the purified water is discharged from the container through the outflow pipe. And stop,
The method for cleaning a mesh filter according to claim 1. The supply point of the foam in the container is set to the range of 1/5 below the depth of the container.
The method for cleaning a mesh filter according to claim 1. A container, an inflow pipe which is a pipe connected to the container for inflowing sewage containing impurities into the container, and an outflow pipe which is a pipe connected to the container for discharging purified water from the container. A filtration device having a mesh filter, which is a mesh-like filter, arranged in the container so that sewage from the inflow pipe to the outflow pipe always passes through the container. hand,
An air supply pipe for supplying air bubbles into the sewage or purified water in the container at the time of cleaning the mesh filter is provided, and the bubbles supplied from the air supply pipe are used to supply the mesh filter. At least part of it is exposed,
Filtration device. The mesh filter is made of metal,
The filtration device according to claim 4. In the air supply pipe, the supply point of the foam in the container is in the range of 1/5 below the depth of the container.
The filtration device according to claim 4. The container is vertically long,
The filtration device according to claim 4. A valve is provided in each of the inflow pipe and the outflow pipe.
When supplying the foam into the sewage or purified water in the container, the valve of the inflow pipe is in a state of stopping the supply of the sewage from the inflow pipe to the container, and the outflow pipe. The valve can be put into a state of stopping the discharge of the purified water from the container through the outflow pipe.
The filtration device according to claim 4. A plurality of filtration devices connected in multiple stages are included, and at least one of the plurality of filtration devices is the filtration device according to any one of claims 4 to 8.
Filtration system. A case having an opening and a strainer filter which is a filter covering the opening of the case are provided, and the strainer filter is connected to a pipe connected to a pump, and is submerged or immersed in sewage. A method of cleaning a strainer filter in a strainer used to suck up sewage.
With the strainer submerged or immersed in sewage, air is sent to the case through the pipe until air is ejected from the strainer filter into the sewage.
How to clean the strainer filter. When the sewage is sucked up from the strainer again after cleaning the strainer filter, the air in the case and the pipe of the strainer is evacuated prior to starting the sucking up of the sewage.
The method for cleaning a strainer filter according to claim 10.

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