JP2014018728A - Filtration system and operation method of filtration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filtration system capable of preventing the occurrence of corrosion in a filtration tank due to hydrogen sulfide or the like and a method for operating the filtration system.SOLUTION: There are provided a filtration system which comprises: a filtration tank having a floating filter medium layer, a screen for preventing the outflow of the floating filter medium layer, a raw water inflow port and a backwash effluent discharge port and a filtrate water storage part; and a wall surface washing mechanism for washing an upper inner surface by spraying washing water on the upper inner surface located at an upper side from the filtrate water storage part among the inner walls of the filtration tank, and a method for operating the filtration system.

Description

  The present invention relates to a filtration system and a method for operating the filtration system, and more particularly, to a filtration system having a floating filter medium layer made of a floating filter medium and suitably used for treating sewage, and a method for operating the filtration system.

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

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

  In the conventional filtration system using the floating filter medium, the raw water flowing in from the raw water inlet is passed upward through the floating filter medium layer, so that impurities (for example, garbage, foreign matters, etc.) and floating suspensions are suspended. Filtered water from which turbid substances have been removed is obtained. In addition, in the conventional filtration system described above, when the floating filter layer is supplemented with contaminants and suspended suspended solids and filtration resistance increases as filtration continues, filtered water stored in the filtrate storage section is allowed to flow down naturally. Thus, the floating filter medium layer is backwashed (hereinafter sometimes referred to as “backwashing”) in a downward flow.

Here, in the conventional filtration system, the floating filter medium 3 constituting the floating filter medium layer 2 is moved downward by a downward flow, as shown in FIG. 4 (a), in the filtration tank 1 of the filtration system being backwashed. The floating filter material layer 2 is backwashed. Therefore, as shown in FIG. 4 (b), the state in the filtration tank 1 of the filtration system immediately after the end of backwashing, the floating filter material layer 2 immediately after the end of backwashing is in a state where the floating filter media is not uniformly aligned and is biased As a result, distribution may occur in the thickness of the floating filter medium layer 2 in the filtration tank 1. And if raw water is filtered with the floating filter medium layer 2 with non-uniform thickness, the property of the filtrate obtained especially in the part where the thickness of the floating filter medium layer 2 is thin deteriorates, and the filtration performance of the filtration system may be lowered. .
In FIG. 4, reference numeral 4 indicates a raw water inlet, reference numeral 5 indicates a backwash drainage outlet, reference numeral 6 indicates a screen, reference numeral 7 indicates a filtrate storage part, and reference numeral 8 indicates an air supply described later. No. 9 indicates a valve that can be freely opened and closed.

  Therefore, in the conventional filtration system, an air supply nozzle is arranged below the floating filter material layer, and air is supplied from the air supply nozzle after the backwashing of the floating filter material layer and before resuming filtration. The floating filter media are aligned. Specifically, in the above conventional filtration system, after the backwashing is completed, before the filtration is resumed, air is ejected from the air supply nozzle to the floating filter material layer, and the floating filter medium is removed by the water flow generated by the ejection of air. By flowing and aligning, the thickness of the floating filter medium layer is made uniform, and the deterioration of the filtration performance of the filtration system due to the non-uniform thickness of the floating filter medium layer is suppressed.

Japanese Patent No. 3853738 JP 2010-221197 A

  Here, the water present in the filtration tank after the backwashing of the floating filter layer is completed, the organic matter contained in the water used for backwashing from the beginning, or the organic matter discharged from the floating filter layer during backwashing Contains organic matter. In addition, some organic substances (contaminants and suspended suspended solids) that could not be removed during the backwashing remain in the floating filter layer after the backwashing.

Therefore, when the ventilation tank is not provided with the opening for ventilation in the filtration tank where the floating filter material layer etc. are arranged, or when the number of ventilation openings arranged in the filtration tank is small, or formed by excavating the ground For example, when a filtration system is configured by placing a floating filter layer in the vertical hole, for example, organic substances contained in the water in the filtration tank after an end of backwashing until the filtration is restarted are anaerobic microorganisms. May be decomposed (anaerobic fermentation occurs) to generate hydrogen sulfide (H ₂ S) or the like. In addition, hydrogen sulfide (H ₂ S), etc., when the time until resumption of filtration is long after completion of backwashing (for example, after completion of backwashing, the filtration system is not immediately resumed and waits for the filtration system. This is particularly likely to occur in the case of a state.

  Therefore, in the above conventional filtration system, hydrogen sulfide generated in the filtration tank dissolves in water droplets attached to the wall surface of the filtration tank due to condensation, and then is oxidized by sulfur-oxidizing bacteria to become sulfuric acid. There is a risk of corrosion of metals, concrete, etc. In addition, corrosion of metals and concrete due to hydrogen sulfide generated after the end of backwashing is especially the case when air is blown from the air supply nozzle to the floating filter layer before the filtration is resumed, and the floating filter is aligned. It is easy to generate. When air is sprayed, hydrogen sulfide dissolved in the water is released into the air supplied to the filtration tank, and the hydrogen sulfide released into the air rises in the filtration tank together with the air, resulting in condensation. This is because after dissolving in water droplets or the like adhering to the wall of the filtration tank, it is oxidized by sulfur-oxidizing bacteria to become sulfuric acid, which causes corrosion of metals, concrete, etc. in the filtration tank.

  Then, this invention aims at providing the operating method of the filtration system which can suppress generation | occurrence | production of the corrosion in the filtration tank resulting from hydrogen sulfide etc., and a filtration system.

An object of the present invention is to advantageously solve the above-described problems, and the filtration system of the present invention includes a floating filter medium layer made of a floating filter medium, and an upper side of the floating filter medium layer. A filtration tank comprising a screen for preventing outflow, a raw water inflow port and a backwash drainage port installed below the floating filter material layer, and a filtrate storage part provided on the upper side of the screen, and the filtration A wall surface cleaning mechanism for cleaning the upper inner wall surface by spraying cleaning water onto the upper inner wall surface located above the filtered water storage portion of the inner wall surface of the tank. Thus, if a wall surface cleaning mechanism is provided, the upper inner wall surface can be cleaned with cleaning water. Therefore, even when hydrogen sulfide or the like dissolves in water droplets or the like adhering to the wall surface of the filtration tank and changes to sulfuric acid, the sulfuric acid can be washed away to suppress the occurrence of corrosion in the filtration tank.
The filtration system is a filtration system that has a floating filter media alignment mechanism that jets gas to the floating filter media layer and aligns the floating filter media, and jets gas to the floating filter media layer to align the floating filter media. In particular, hydrogen sulfide or the like easily dissolves in water droplets or the like adhering to the wall of the filtration tank when the gas is sprayed. Therefore, particularly in a filtration system having a floating filter media alignment mechanism, the occurrence of corrosion in the filtration tank can be suppressed by providing a wall surface cleaning mechanism.

  Here, in the filtration system of the present invention, it is preferable that the wall surface cleaning mechanism includes a nozzle that sprays the cleaning water on the upper inner wall surface. This is because the upper inner wall surface can be efficiently cleaned by providing a nozzle for spraying the cleaning water in the form of droplets.

  Further, in the filtration system of the present invention, the wall cleaning mechanism includes a tap water supply unit, a tap water ejection unit provided above the filtrate storage unit in the filtration tank, and the tap water supply unit. It is preferable to have a tap water flow path connecting the tap water ejection part and to wash the upper inner wall surface by spraying tap water from the tap water ejection part onto the upper inner wall surface. This is because if the tap water supply section, the tap water ejection section and the tap water flow path are provided and tap water is used as the cleaning water, the upper inner wall surface can be efficiently cleaned. In addition, the wash water used for cleaning the upper inner wall surface flows into the filtered water storage section through the wall surface. If tap water is used as the cleaning water, the quality of the filtered water stored in the filtered water storage section is reduced. This is because deterioration can be suppressed.

Moreover, this invention aims at solving the said subject advantageously, and the operating method of the filtration system of this invention is arrange | positioned above the floating filter medium layer and the floating filter medium layer which consists of a floating filter medium. A filtration comprising a screen for preventing the floating filter material from flowing out, a raw water inlet and a backwash drainage port installed below the floating filter material layer, and a filtrate storage part provided above the screen. An operation method of a filtration system having a tank, wherein raw water is introduced from the raw water inlet, and the raw water that has been introduced is passed through the floating filter material layer in an upward flow to filter the raw water, and After the filtration step, the water in the filtration tank is discharged from the backwash drainage outlet, the backwashing process in which the floating filter material layer is backwashed in a downward flow, and the filtration wall among the inner wall surfaces of the filtration tank. Located above the water reservoir Characterized in that it comprises a wall cleaning step of cleaning the upper inner wall surface that the wash water spouting put in the upper inner wall surface. Thus, if a wall surface washing process is provided, an upper inner wall surface can be washed with washing water. Therefore, even when hydrogen sulfide or the like dissolves in water droplets or the like adhering to the wall surface of the filtration tank and changes to sulfuric acid, the sulfuric acid can be washed away to suppress the occurrence of corrosion in the filtration tank.
In addition, after carrying out the backwashing step, when performing the floating filter media alignment step of aligning the floating filter media constituting the floating filter media layer by injecting gas to the floating filter media layer, the wall surface washing step after the floating filter media alignment step If it carries out, generation | occurrence | production of the corrosion in the filtration tank resulting from the hydrogen sulfide etc. which are discharge | released in gas when a gas is sprayed can be suppressed.

  Here, in the operation method of the filtration system of the present invention, in the wall surface cleaning step, the cleaning water is preferably sprayed on the upper inner wall surface in the form of droplets. This is because the upper inner wall surface can be efficiently cleaned if the cleaning water is sprayed in the form of droplets.

  Moreover, it is preferable that the operating method of the filtration system of this invention uses a tap water as said washing water in the said wall surface washing process. This is because if the tap water is used as the cleaning water, the upper inner wall surface can be efficiently cleaned. In addition, the wash water used for cleaning the upper inner wall surface flows into the filtered water storage section through the wall surface. If tap water is used as the cleaning water, the quality of the filtered water stored in the filtered water storage section is reduced. This is because deterioration can be suppressed.

  According to the filtration system and the operation method of the filtration system of the present invention, it is possible to suppress the occurrence of corrosion in the filtration tank due to hydrogen sulfide or the like.

It is explanatory drawing which shows an example of the installation position of the typical filtration system according to this invention. It is explanatory drawing explaining schematic structure of the typical filtration system according to this invention. It is explanatory drawing which shows the state which is implementing the backwashing process, the floating filter media alignment process, and the wall surface washing process about the principal part of the filtration system shown in FIG. 2, (a) is the filtration system which is implementing the backwashing process (B) shows the state of the filtration system performing the floating filter media alignment step, and (c) shows the state of the filtration system performing the wall surface washing step. Yes. It is explanatory drawing which shows the state in the filter tank of the conventional filtration system, (a) has shown the state in the filter tank in which the floating filter material layer is backwashed, (b) is the reverse of the floated filter material layer. The state in the filtration tank immediately after completion | finish of washing is shown.

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

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

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

Here, as shown in FIG. 2, the filtration system 100 of an example of the present invention is installed under the ground G, and the first vertical hole 10 as a filtration tank having the floating filter material layer 12 and the raw water tank. The second vertical hole 20, the third vertical hole 30 as a backwash drainage tank, and the raw water flow path connecting the merged sewer pipe 111 and the second vertical hole 20. The filtration system 100 is characterized in that tap water as cleaning water is sprayed onto the inner wall surface of the first vertical hole 10 so that the inner wall surface can be washed with tap water.
In addition, the raw water flow path of the filtration system 100 is provided with a flow rate adjustment valve 115 as a raw water inflow blocking mechanism that blocks the inflow of raw water into the second vertical hole 20. In addition, a lid (not shown) for preventing a person or an object from falling into the vertical hole is disposed at the opening of the first vertical hole 10, the second vertical hole 20, and the third vertical hole 30 to the ground G. ing.

The first vertical hole 10 functions as a filtration tank for filtering raw water to obtain filtered water. As the first vertical hole 10, for example, a structure such as a new manhole formed by excavating the ground G Can be used. As shown in FIG. 2, in the first vertical hole 10, the screen 11, the floating filter medium layer 12 made of a plurality of floating filter media supported by the screen 11, and the floating filter medium layer 12 are installed below. The raw water inlet 13, the plurality of backwash drainage outlets 14 installed below the floating filter material layer 12, the filtrate storage part 15 provided on the upper side of the screen 11, and the upper side of the screen 11. A filtered water outlet 16 is disposed.
Further, below the floating filter medium layer 12 in the first vertical hole 10, an air ejection part 51 that constitutes a part of a floating filter medium alignment mechanism described in detail later is disposed. The air ejection part 51 is located above the raw water inlet 13 and the backwash drainage outlet 14.
Furthermore, on the upper side of the filtrate storage part 15 of the first vertical hole 10, more specifically, on the upper side of the horizontal plane passing through the lower end of the filtrate outlet 16, the water supply constituting a part of the wall cleaning mechanism described later in detail. A water ejection part 71 is provided.

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

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

Here, the floating filter medium alignment mechanism is for ejecting a gas such as air to the floating filter medium layer 12 to align the floating filter medium constituting the floating filter medium layer 12. And in this filtration system 100, the floating filter media alignment mechanism includes an air ejection part 51, a blower (not shown) as an air supply source for supplying air to the air ejection part 51, and a blower and an air ejection part 51. An air supply pipe 52 to be connected and an air supply pipe valve 53 provided in the air supply pipe 52 are configured.
Therefore, in the filtration system 100, by opening the air supply piping valve 53 and operating a blower (not shown), air is sent into the first vertical hole 10 via the air supply piping 52, and the floating filter medium layer 12 can be sprinkled with air. The opening / closing of the air supply piping valve 53 can be controlled by a control device (not shown).

The air ejection part 51 which comprises a part of floating filter media alignment mechanism can be installed in arbitrary positions, if it is a position which can spray air with respect to the floating filter material layer 12. FIG. Specifically, the air ejection part 51 blows air against the floating filter material layer 12 after backwashing according to the material of the floating filter used, the filtering conditions, the backwashing conditions, and the like, The floating filter medium constituting the layer 12 can be installed at a position where it can flow. More specifically, the air ejection part 51 is not particularly limited, and is, for example, a place of 0 to 120 cm downward from the lower surface of the floating filter material layer 12 after passing raw water at a linear velocity of 1000 m / day. It can be installed above the raw water inlet 13.
In addition, the air ejection part 51 can be fixed in the 1st vertical hole 10 using known means, such as a volt | bolt.

Here, the air ejection part 51 can be made into an arbitrary shape as long as air (gas) can be ejected. And as the air ejection part 51, it does not specifically limit, The grid | lattice-like pipe body formed by combining the pipe provided with the several ejection nozzle in a grid | lattice form can be used.
In addition, it is preferable that the size of the lattice is larger than that of the floating filter medium and that the clogging does not occur due to contaminants in the raw water during the filtration of the raw water. This is because when the size of the lattice is smaller than that of the floating filter medium, the floating filter medium cannot be developed downward when the floating filter medium layer 12 is backwashed. Further, when clogging occurs at the lower part of the first vertical hole 10, maintenance is difficult.

Further, the wall surface cleaning mechanism sprays cleaning water on the upper inner wall surfaces 81A, 81B, 81C located above the filtration tank storage unit 15 among the inner wall surfaces of the first vertical hole 10 as a filtration tank. This is for cleaning the wall surfaces 81A, 81B, 81C.
In the filtration system 100, the inner wall surface of the first vertical hole 10 as a filtration tank has a side wall surface of the first vertical hole 10 and an upper surface (that is, a lid disposed on the opening of the first vertical hole 10. Bottom surface) and a bottom surface. In the filtration system 100, the top surface of the filtrate storage unit 15 is a horizontal plane that passes through the lower end of the filtrate outlet 16. Therefore, in the filtration system 100, the upper inner wall surface located above the filtration tank reservoir 15 is provided on the side wall surfaces 81 </ b> B and 81 </ b> C of the first vertical hole 10 located above the horizontal plane passing through the lower end of the filtrate outlet 16. And a bottom surface 81 </ b> A of the lid provided at the opening of the first vertical hole 10.

And in this filtration system 100, a wall surface washing mechanism is a tap water ejection part 71, a tap water supply part (not shown) as a tap water supply source which supplies a tap water to the tap water ejection part 71, tap water A tap water supply pipe 72 as a tap water flow path connecting the supply section and the tap water ejection section 71 and a tap water supply pipe valve 73 provided in the tap water supply pipe 72 are configured.
Therefore, in the filtration system 100, the tap water supply piping valve 73 is opened, and the tap water is sent into the first vertical hole 10 from a tap water supply section (not shown) such as a water pipe, for example. Tap water can be sprayed on 81A, 81B, 81C. The opening / closing of the tap water supply piping valve 73 can be controlled by a control device (not shown).

  In addition, the wall surface cleaning mechanism of the filtration system of the present invention may spray water other than tap water as cleaning water. Examples of the cleaning water include middle water, industrial water, filtered water in the filtrate storage section, and the like. May be used. However, since the cleaning water used for cleaning the upper inner wall surface flows down to the filtrate storage part through the inner wall surface, from the viewpoint of not deteriorating the properties of the filtrate flowing out from the filtration system, the cleaning water is tap water. It is preferable to use clean water.

The tap water ejection part 71 constituting a part of the wall surface cleaning mechanism can be installed at any position as long as tap water can be sprayed onto the upper inner wall surfaces 81A, 81B, 81C. Specifically, the tap water jetting portion 71 is located at a distance of, for example, 0.25 to 1.0 m from each upper inner wall surface 81A, 81B, 81C in a state of being opposed to the upper inner wall surfaces 81A, 81B, 81C. Can be arranged.
In addition, the tap water ejection part 71 can be fixed in the 1st vertical hole 10 using known means, such as a volt | bolt.

Here, the tap water jet part 71 can be made into an arbitrary shape as long as tap water as washing water can be jetted. And as the tap water ejection part 71, it does not specifically limit, The grid-like pipe body which combines the pipe provided with the several ejection nozzle in a grid | lattice form, or the sprinkler which can eject tap water in multiple directions is used. be able to.
A known nozzle or sprinkler can be used as the nozzle or sprinkler of the grid-like pipe body, but from the viewpoint of efficiently cleaning the upper inner wall surfaces 81A, 81B, 81C over a wide area, It is preferable that the nozzle and sprinkler of the pipe body are configured so that tap water can be sprayed out.

  Incidentally, in the filtration system 100, the tap water supply pipe 72 is branched into three between the tap water jet part 71 and the tap water supply pipe valve 73, and a total of three tap water jet parts 71 are connected to the upper inner wall surfaces 81A and 81B. , 81C to face each other. However, in the filtration system of the present invention, as long as the upper inner wall surface can be cleaned, only one tap water ejection part may be provided in the upper part of the first vertical hole.

  The second vertical hole 20 functions as a raw water tank that stores the raw water filtered in the first vertical hole 10, and the second vertical hole 20 excavates the ground G in the same manner as the first vertical hole 10. It is possible to use a new manhole or other structure formed in this way. And as shown in FIG. 2, the raw | natural water pump 21 is arrange | positioned in the lower part of the 2nd vertical hole 20. As shown in FIG. Further, the upper part of the second vertical hole 20 communicates with the merging sewage pipe 111 via a raw water flow path having a flow rate adjusting valve 115. Further, a water level gauge (not shown) for measuring the water level in the second vertical hole 20 is installed in the second vertical hole 20. In addition, as a raw | natural water pump 21 and a water level meter, a well-known pump and a water level meter can be selected suitably, and can be used.

  In the filtration system 100, the suction port of the raw water pump 21 is located in the second vertical hole 20. The discharge port of the raw water pump 21 is connected to the raw water pipe 41, and the raw water pipe 41 connects the discharge port of the raw water pump 21 and the raw water inlet 13 of the first vertical hole 10. The raw water pipe 41 has a raw water pipe valve 42.

  Therefore, in the filtration system 100 in which the raw water pump 21 is disposed in the second vertical hole 20, the raw water in the second vertical hole 20 is opened via the raw water pipe 41 by opening the raw water piping valve 42 and operating the raw water pump 21. Can be delivered into the first vertical hole 10. Note that the opening and closing of the raw water piping valve 42 can be controlled by a control device (not shown).

  The third vertical hole 30 functions as a backwash drainage tank that stores backwash drainage discharged from the backwash drainage outlet 14 of the first vertical hole 10 when the floating filter material layer 12 is backwashed. As the third vertical hole 30, similarly to the first vertical hole 10 and the second vertical hole 20, a structure such as a new manhole formed by excavating the ground G can be used. And as shown in FIG. 2, the drainage pump 31 is arrange | positioned in the lower part of the 3rd vertical hole 30. As shown in FIG. A water level meter (not shown) for measuring the water level in the third vertical hole 30 is installed in the third vertical hole 30. As the drainage pump 31 and the water level gauge, known pumps and water level gauges can be appropriately selected and used.

  Here, in the filtration system 100, the suction port of the drainage pump 31 is located in the third vertical hole 30. Moreover, the discharge port of the drainage pump 31 is connected to the interception pipe 113 shown in FIG. 1 through the drainage pipe, and the interception pipe 113 extends to the sewage treatment plant. The drainage pipe may be connected to the merging sewage pipe 111 on the downstream side of the overflow section where the raw water (overflow water) overflows from the merging sewage pipe 111.

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

  Therefore, in the filtration system 100 in which the first vertical hole 10 and the third vertical hole 30 are communicated with each other via the water collecting pipe 61, the water level in the third vertical hole 30 is lower than the water level in the first vertical hole 10. In this case, the water in the first vertical hole 10 can be sent into the third vertical hole 30 through the water collection pipe 61 by opening the water collection pipe valve 62. And the water (backwash drainage) sent out in the 3rd vertical hole can be sent out to the interception pipe via the drainage pump 31. The opening / closing of the water collection piping valve 62 can be controlled by a control device (not shown).

And in this filtration system 100, the overflow water (raw water) which flowed in into the 2nd vertical hole 20 from the merged sewer pipe 111 is filtered with the floating filter material layer 12 of the 1st vertical hole 10 as follows. Moreover, in this filtration system 100, when filtration resistance rises more than predetermined value regularly, the floating filter material layer 12 in the 1st vertical hole 10 is backwashed as follows. And after the backwashing of the floating filter medium layer 12 is finished, before resuming the filtration of the raw water, the floating filter medium layer 12 is formed by blowing gas to the floating filter medium layer 12 as follows. Align the filter media. Moreover, in this filtration system 100, after aligning floating filter media, the upper inner wall surfaces 81A, 81B, 81C of the first vertical hole 10 are washed with tap water at an arbitrary timing.
In addition, after backflushing the floating filter material layer 12, the filtration system 100 may be arbitrarily set in a standby state (states in which the pumps are not operated and the valves are closed) until the filtration is resumed. Incidentally, when the filtration system 100 is put in a standby state after the end of backwashing, it is preferable to align the floating filter media immediately before resuming filtration. This is because if the floating filter media are aligned immediately before resuming filtration, the water flowing into the air supply pipe can be discharged and filtered. Moreover, it is because the lower surface of a floating filter material layer can also be wash | cleaned.

<Filtration process>
As shown in FIG. 2, in the filtration system 100, the raw water pump 21 is operated with the raw water piping valve 42 opened and the air supply piping valve 53, the water collection piping valve 62 and the tap water supply piping valve 73 closed. The raw water that has flowed into the second vertical hole 20 from the merging sewage pipe 111 through the raw water flow path is sent to the lower part of the first vertical hole 10, and the raw water is passed upward through the floating filter material layer 12. To obtain filtered water. Then, after the filtrate water obtained flows through the filtrate water storage unit 15 in an upward flow, it is discharged to a river or the like via the filtrate water outlet 16.
When raw water is filtered, the air supply pipe valve 53 and the water collection pipe valve 62 may be opened as long as the raw water flows in the first vertical hole 10 in an upward flow. From the viewpoint of filtering, it is preferable to filter the raw water with the air supply piping valve 53 and the water collection piping valve 62 closed. Moreover, when filtering raw | natural water, the tap water supply piping valve 73 may be opened and may be closed. That is, in the filtration system 100, tap water may be sprayed onto the upper inner wall surfaces 81A, 81B, 81C during the raw water filtration to wash the upper inner wall surfaces 81A, 81B, 81C.

  Here, when the raw water is filtered, the flow rate of the raw water sent from the second vertical hole 20 into the first vertical hole 10 through the raw water pipe 41 and the raw water inlet 13 flows into the second vertical hole 20. When the flow rate is larger than the flow rate, that is, when the discharge amount of the raw water pump 21 is larger than the inflow amount of the raw water, the water level LV in the second vertical hole 20 is, for example, a two-dot chain line from the position shown by the solid line in FIG. Decreases to the position shown.

  Therefore, in the filtration system 100, in order to prevent the raw water pump 21 from idling due to a drop in the water level in the second vertical hole 20, the water level in the second vertical hole 20 is set at a predetermined position (for example, two in FIG. 2). When the pressure drops to the position indicated by the dotted line), the operation of the raw water pump 21 is stopped, the raw water piping valve 42 is closed, and the raw water filtration is stopped. And when raw | natural water is again stored in the 2nd vertical hole 20 and the water level in the 2nd vertical hole 20 rises, the raw | natural water piping valve 42 will be opened, the driving | operation of the raw | natural water pump 21 will be restarted, and filtration of raw | natural water will be restarted. .

<Backwash process>
Further, as shown in FIG. 3A, in the filtration system 100, when the filtration resistance increases to a predetermined value or more regularly, the raw water piping valve 42 is closed and the raw water pump 21 is stopped, and at least water collection. By operating the drainage pump 31 with the piping valve 62 opened, the floating filter material layer 12 is backwashed. Specifically, the water in the first vertical hole 10 is discharged to the lower part of the third vertical hole 30 through the water collecting pipe 61, and the filtrate stored in the filtrate storage part 15 is transferred to the floating filter material layer 12. A large number of floating filter media 12 </ b> A constituting the floating filter material layer 12 are expanded downward by passing water in a downward flow. Then, the impurities and floating suspended substances captured in the floating filter medium layer 12 are discharged from the floating filter medium layer 12, and the floating filter medium layer 12 is back-washed. In addition, the water that flows into the third vertical hole 30 from the first vertical hole 10 (backwash drainage containing impurities and floating suspended matter supplemented by the floating filter material layer 12) is discharged from the drain pump 31. Through the third vertical hole 30 to the shielding tube 113. Therefore, the water level in the 1st vertical hole 10 falls, for example from the position shown by a dashed-two dotted line to the position shown by a continuous line in Fig.3 (a), and the water level in the 3rd vertical hole 30 is shown in FIG. Ascending from the position indicated by the two-dot chain line to the position indicated by the solid line in a).
In the case of backwashing the floating filter material layer 12, if the filtrate flows downward in the first vertical hole 10, the raw water piping valve 42 may be opened and the raw water pump 21 may be operated. From the viewpoint of efficiently backwashing the floating filter material layer 12, it is preferable to backwash the floating filter material layer 12 with the raw water piping valve 42 closed and the raw water pump 21 stopped. Further, when the floating filter material layer 12 is backwashed, the tap water supply piping valve 73 may be opened or closed. That is, in the filtration system 100, tap water may be sprayed onto the upper inner wall surfaces 81A, 81B, 81C during the backwashing of the floating filter material layer 12 to wash the upper inner wall surfaces 81A, 81B, 81C.

  Here, in the filtration system 100, in order to prevent the drainage pump 31 from idling due to a drop in the water level in the third vertical hole 30, the water level in the third vertical hole 30 is set at a predetermined position (for example, FIG. In the case of a drop to a position indicated by a two-dot chain line in a), the operation of the drain pump 31 is stopped until the water level in the third vertical hole 30 rises.

  Further, in the filtration system 100, when the water in the first vertical hole 10 is allowed to flow naturally into the third vertical hole 30 at a high flow rate, the water level in the third vertical hole 30 is the same as that when starting backwashing. It is necessary to be below the water level in one vertical hole 10 (usually, the position where the filtered water outlet 16 is provided). Therefore, in this filtration system 100, the reverse of the floating filter material layer 12 is obtained only when the water level in the third vertical hole 30 measured by the water level meter installed in the third vertical hole 30 is equal to or lower than the water level in the first vertical hole 10. Control of opening and closing of the raw water piping valve 42 and the water collecting piping valve 62 is controlled by a control device (not shown) so as to start washing. Specifically, only when the water level in the third vertical hole 30 is located below the water level in the first vertical hole 10, the control device closes the raw water piping valve 42 and opens the water collection piping valve 62. Allow to open.

  Here, since raw water is passed upward through the floating filter material layer 12 in the filtration step, the floating filter material constituting the floating filter material layer 12 was consolidated toward the screen 11 at the start of the backwashing step. Is in a state. Therefore, when the backwashing of the floating filter material layer 12 is started, the floating filter medium is developed downward in a lump shape.

  Therefore, without being particularly limited, in the backwashing step, immediately after the backwashing is started, air is blown from the air ejection portion 51 to the floating filter material 12A, thereby dispersing the massive floating filter material, and the floating filter material layer 12. The cleaning efficiency may be improved. Specifically, in the backwashing process, immediately after the backwashing is started, the air supply piping valve 53 is opened for a predetermined time, and the blower is operated, so that air is jetted upward from the air jetting part 51 and floated. The filter medium may be dispersed.

In the filtration system 100, means for supplying tap water, medium water, and industrial water to the upper portion of the first vertical hole 10 is provided, and the floating filter material layer 12 is formed using tap water, intermediate water, and industrial water. You may make it perform backwashing. Specifically, in the filtration system 100, as shown in the following (1) to (3), the floating filter material layer 12 is back-washed using the filtered water stored in the filtered water storage unit 15 and tap water. May be.
(1) First, as described above, the filtered water stored in the filtrate storage unit 15 is passed through the floating filter medium layer 12 in a downward flow, and the floating filter medium layer 12 is back-washed, and then the water collecting piping valve 62 Close.
(2) Next, tap water is supplied to the filtrate storage unit 15 to fill the filtrate storage unit 15 with tap water.
(3) Finally, by operating the drain pump 31 with the water collection piping valve 62 opened, the tap water stored in the filtrate storage unit 15 is passed through the floating filter material layer 12 in a downward flow. The floating filter material layer 12 is backwashed. The tap water passed through the floating filter material layer 12 is discharged to the lower part of the third vertical hole 30 through the water collecting pipe 61 and then sent out to the collecting pipe using the backwash pump 31.
Incidentally, when backflushing the floating filter material layer 12 using tap water, the tap water supply in the above (2) is to open the tap water supply piping valve 73 and jet the tap water from the tap water ejection part 71. May be performed.

<Standby process>
In the filtration system 100, when the backwash process is completed, the raw water pipe valve 42, the air supply pipe valve 53, the water collection pipe valve 62, and the tap water supply pipe valve 73 are optionally closed, and the raw water pump 21 and the drainage pump 31 are closed. Then, the operation of the filtration system 100 is stopped with the operation of the blower (not shown) stopped.
In addition, this standby process is implemented when there is no inflow of the raw water into the 1st vertical hole 10 after completion | finish of a backwash process, or when the inflow amount of the raw water into the 1st vertical hole 10 is small.

  Here, in the filtration system 100, the floating filter medium layer 12 is backwashed by developing the floating filter medium 12A constituting the floating filter medium layer 12 downward by a downward flow in the backwashing step. Therefore, as shown by a two-dot chain line in FIG. 3B, in the floating filter medium layer 12 immediately after the end of the backwashing, the floating filter medium gathers in a biased state without being uniformly aligned. As a result, the floating filter medium layer 12 Distribution may occur in the thickness. And when filtration of raw | natural water is restarted in the state where the thickness of the floating filter material layer 12 is non-uniform | heterogenous, the property of the filtrate obtained especially in the part with the thin thickness of the floating filter material layer 12 will deteriorate, and the filtration performance of a filtration system will fall. there is a possibility.

<Floating filter alignment process>
Therefore, in this filtration system 100, as shown in FIG. 3 (b), after the backwashing step and the standby step, the air supply piping valve 53 is opened, the raw water piping valve 42, the water collection piping valve 62, and the tap water supply. By operating a blower (not shown) with the piping valve 72 closed, the air 54 is supplied into the first vertical hole 10 through the air supply piping 52 and the air ejection portion 51. Then, air (bubbles) 54 is sprayed onto the floating filter medium layer 12 made of the floating filter medium gathered in an uneven manner, and the floating filter medium constituting the floating filter medium layer 12 is aligned. Specifically, a flow of water is generated in the first vertical hole 10 by the ejection of air, and the floating filter medium is caused to flow by the flow of the water, thereby aligning the floating filter medium and forming the floating filter medium layer 12 in FIG. The state indicated by the dotted line is changed to the state indicated by the solid line in FIG.

The air may be supplied continuously or intermittently (pulsed). In addition, the time for supplying air can be any time as long as the floating filter media can be aligned, and can be, for example, 2 to 10 seconds.
Further, in the floating filter media alignment step, the raw water piping valve 42 may be opened and air may be sprayed onto the floating filter media layer 12 while the raw water pump 21 is operated. That is, in the floating filter media alignment step, the floating filter media may be aligned while passing raw water through the floating filter media layer 12. Furthermore, in the floating filter media alignment step, the tap water supply piping valve 73 may be open or closed. That is, in the filtration system 100, tap water may be sprayed on the upper inner wall surfaces 81A, 81B, 81C during the alignment of the floating filter media to clean the upper inner wall surfaces 81A, 81B, 81C.

Here, the first vertical hole 10 is formed by excavating the ground G, and a lid is disposed at the opening of the first vertical hole 10. The organic matter contained in the water staying in the vertical hole 10 is decomposed by anaerobic microorganisms. And most of hydrogen sulfide etc. which generate | occur | produced by decomposition | disassembly of organic substance melt | dissolves in the staying water which has stayed in the 1st vertical hole 10. FIG. Therefore, in the filtration system 100, when air is ejected upward from the air ejection part 51 in order to make the floating filter medium flow and make the thickness of the floating filter medium layer 12 uniform before resuming filtration, it dissolves in the accumulated water. Hydrogen sulfide and the like that have been released are released into the air. The hydrogen sulfide and the like released into the air rise in the first vertical hole 10 together with the air and dissolve in water droplets or the like adhering to the inner wall surface of the first vertical hole 10 due to dew condensation or the like. Oxidized by oxidizing bacteria or the like to become sulfuric acid.
Therefore, in the filtration system 100, a wall surface cleaning process, which will be described later, is performed after the floating filter medium alignment process.

<Wall cleaning process>
Specifically, in the filtration system 100, as shown in FIG. 3C, the tap water supply piping valve 73 is opened, and the water collection piping valve 62 and the air supply piping valve 53 are closed after the floating filtration material alignment step. State. And tap water is sprayed on upper inner wall surface 81A, 81B, 81C via the tap water supply piping 72 and the tap water ejection part 71, and upper inner wall surface 81A, 81B, 81C located above the filtrate water storage part 15 is used. Wash. That is, the water droplets containing sulfuric acid adhering to the upper inner wall surface are washed away with tap water to prevent the occurrence of corrosion in the first vertical hole 10.
In the wall surface washing step, tap water may be sprayed onto the upper inner wall surfaces 81A, 81B, 81C while the raw water piping valve 42 is opened and the raw water pump 21 is operated. That is, in the wall surface washing step, the upper inner wall surfaces 81A, 81B, 81C may be washed while passing raw water through the floating filter material layer 12.

  Here, the tap water may be sprayed continuously or intermittently (pulse-like). Moreover, the time for spraying tap water can be set to an arbitrary time as long as the upper inner wall surfaces 81A, 81B, 81C can be washed.

In the filtration system 100, the filtration process is performed again after the above-described floating filter alignment process, and the raw water is filtered using the floating filter layer 12 having a uniform thickness. Thereafter, the backwashing step, the standby step, the floating filter material alignment step, and the filtration step are repeated while appropriately performing the wall surface washing step.
If the filtration step, backwashing step, floating filter media alignment step, etc. are repeated in sequence, the wall surface washing step can be carried out at any timing as long as the occurrence of corrosion in the first vertical hole 10 as a filtration layer can be suppressed. can do.

Here, in the filtration system 100, as described above, since the wall surface washing process is performed after the floating filter media alignment process, the first after the back washing process is performed, for example, when the standby process is performed. Even when organic substances contained in the water in the vertical hole 10 are decomposed by anaerobic microorganisms and hydrogen sulfide or the like is generated, the occurrence of corrosion in the first vertical hole 10 can be suppressed. That is, in this filtration system 100, water droplets adhering to the upper inner wall surfaces 81A, 81B, 81C of the first vertical hole 10 are washed away in the wall surface washing step after the floating filter media alignment step. Even when hydrogen sulfide or the like is released into the gas, and the released hydrogen sulfide or the like dissolves in water droplets attached to the wall surface and changes to sulfuric acid, the sulfuric acid can be washed away to suppress the occurrence of corrosion. .
In the filtration system 100, the inner wall surface located below the filtered water outlet 16 among the inner wall surfaces of the first vertical hole 10 is made of raw water or filtered water if the filtration step is performed after the floating filter material alignment step. Since it is washed, the occurrence of corrosion can be suppressed without washing in the wall surface washing step.

  As mentioned above, although the filtration system of the present invention and the operation method of the filtration system were explained using an example, the filtration system of the present invention and the operation method of the filtration system are not limited to the above example, and the filtration system of the present invention. And the operation method of the filtration system can be changed as appropriate.

Specifically, in the filtration system of the present invention, a filtration process, a backwash process, a standby process, which is an optional process, and a floating filter media alignment process are repeatedly performed. In the case of backwashing the floating filter material layer using the filtered water stored in the storage unit and tap water, the backwashing step and the wall surface washing step using tap water may be performed simultaneously. That is, in the filtration system of the present invention, after sequentially performing the first filtration step, the first backwashing step, the standby step, and the first floating filter media alignment step, a second filtration step, When carrying out the second backwashing step, the second backwashing step and the wall surface washing step using tap water may be carried out simultaneously.
More specifically, in the second backwashing step, after the floating filter material layer is backwashed using the filtrate stored in the filtrate storage part, the wall surface washing step is performed using tap water and the wall surface washing is performed. The tap water used in the process may be stored in the filtrate storage unit, and the floating filter material layer may be backwashed again using the stored tap water. In this way, if the floating filter medium layer is backwashed with tap water used as the cleaning water in the wall surface cleaning process, the time and cost required for backwashing the floating filter medium layer can be reduced while suppressing the occurrence of corrosion. Can do.

  Moreover, in the filtration system 100 of the above example, a vertical hole formed by excavating the ground G is used. However, the filtration system of the present invention is a filtration tank installed on the ground (for example, a filtration tank having a small number of openings for ventilation). Etc. may be used.

  According to the filtration system and the operation method of the filtration system of the present invention, even when the floating filter medium is aligned by blowing the gas to the floating filter medium layer after the backwashing of the floating filter medium layer, it is released into the gas. It is possible to suppress the occurrence of corrosion in the filtration tank caused by hydrogen sulfide or the like.

DESCRIPTION OF SYMBOLS 1 Filtration tank 2 Floating filter layer 3 Floating filter medium 4 Raw water inlet 5 Backwash drainage outlet 6 Screen 7 Filtrated water storage part 8 Air supply nozzle 9 Valve 10 First vertical hole 11 Screen 12 Floating filter medium layer 13 Raw water inlet 14 Backwash drain outlet 15 Filtrated water storage part 16 Filtrated water outlet 20 Second vertical hole 21 Raw water pump 30 Third vertical hole 31 Drain pump 41 Raw water pipe 42 Raw water pipe valve 51 Air ejection part 52 Air supply pipe 53 Air supply pipe valve 54 Air bubbles 61 Water collection pipe 62 Water collection pipe valve 71 Tap water ejection part 72 Tap water supply pipe 73 Tap water supply pipe valve 81A, 81B, 81C Upper inner wall surface 100 Filtration system 111 Combined sewer pipe 112 Rain spout 113 Intercept pipe 114 River 115 Flow control valve

Claims (6)

A floating filter layer made of a floating filter medium, a screen disposed above the floating filter medium layer to prevent the floating filter medium from flowing out, a raw water inlet and a backwash drainage outlet installed below the floating filter medium layer; And a filtration tank provided with a filtrate storage part provided on the upper side of the screen,
Of the inner wall surface of the filtration tank, a wall surface cleaning mechanism for cleaning the upper inner wall surface by spraying cleaning water on the upper inner wall surface located above the filtrate storage part,
A filtration system comprising:   The filtration system according to claim 1, wherein the wall surface cleaning mechanism includes a nozzle that sprays the cleaning water onto the upper inner wall surface. The wall surface cleaning mechanism is
A tap water supply unit;
A tap water ejection part provided above the filtrate storage part in the filtration tank,
A tap water flow path connecting the tap water supply unit and the tap water ejection unit;
3. The filtration system according to claim 1, wherein the upper inner wall surface is washed by spraying tap water from the tap water ejection portion onto the upper inner wall surface. A floating filter layer made of a floating filter medium, a screen disposed above the floating filter medium layer to prevent the floating filter medium from flowing out, a raw water inlet and a backwash drainage outlet installed below the floating filter medium layer; And an operation method of a filtration system having a filtration tank provided with a filtrate storage part provided on the upper side of the screen,
A filtration step of filtering the raw water by allowing the raw water to flow in from the raw water inlet and passing the raw water that has flowed in the upward flow through the floating filter medium layer;
After the filtration step, the water in the filtration tank is discharged from the backwash drainage outlet, and the backwash step for backwashing the floating filter material layer in a downward flow,
Of the inner wall surface of the filtration tank, a wall surface cleaning step for cleaning the upper inner wall surface by spraying cleaning water on the upper inner wall surface located above the filtrate storage part,
A method for operating a filtration system, comprising:   The method of operating a filtration system according to claim 4, wherein, in the wall surface cleaning step, the cleaning water is sprayed on the upper inner wall surface in the form of droplets. The operation method of the filtration system according to claim 4 or 5, wherein tap water is used as the cleaning water in the wall surface cleaning step.

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